kernel/rcu/rcutorture.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Read-Copy Update module-based torture test facility
   4  *
   5  * Copyright (C) IBM Corporation, 2005, 2006
   6  *
   7  * Authors: Paul E. McKenney <[email protected]>
   8  *        Josh Triplett <[email protected]>
   9  *
  10  * See also:  Documentation/RCU/torture.rst
  11  */
  12
  13 #define pr_fmt(fmt) fmt
  14
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19 #include <linux/kthread.h>
  20 #include <linux/err.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/smp.h>
  23 #include <linux/rcupdate_wait.h>
  24 #include <linux/rcu_notifier.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/sched/signal.h>
  27 #include <uapi/linux/sched/types.h>
  28 #include <linux/atomic.h>
  29 #include <linux/bitops.h>
  30 #include <linux/completion.h>
  31 #include <linux/moduleparam.h>
  32 #include <linux/percpu.h>
  33 #include <linux/notifier.h>
  34 #include <linux/reboot.h>
  35 #include <linux/freezer.h>
  36 #include <linux/cpu.h>
  37 #include <linux/delay.h>
  38 #include <linux/stat.h>
  39 #include <linux/srcu.h>
  40 #include <linux/slab.h>
  41 #include <linux/trace_clock.h>
  42 #include <asm/byteorder.h>
  43 #include <linux/torture.h>
  44 #include <linux/vmalloc.h>
  45 #include <linux/sched/debug.h>
  46 #include <linux/sched/sysctl.h>
  47 #include <linux/oom.h>
  48 #include <linux/tick.h>
  49 #include <linux/rcupdate_trace.h>
  50 #include <linux/nmi.h>
  51
  52 #include "rcu.h"
  53
  54 MODULE_LICENSE("GPL");
  55 MODULE_AUTHOR("Paul E. McKenney <[email protected]> and Josh Triplett <[email protected]>");
  56
  57 /* Bits for ->extendables field, extendables param, and related definitions. */
  58 #define RCUTORTURE_RDR_SHIFT_1   8      /* Put SRCU index in upper bits. */
  59 #define RCUTORTURE_RDR_MASK_1    (1 << RCUTORTURE_RDR_SHIFT_1)
  60 #define RCUTORTURE_RDR_SHIFT_2   9      /* Put SRCU index in upper bits. */
  61 #define RCUTORTURE_RDR_MASK_2    (1 << RCUTORTURE_RDR_SHIFT_2)
  62 #define RCUTORTURE_RDR_BH        0x01   /* Extend readers by disabling bh. */
  63 #define RCUTORTURE_RDR_IRQ       0x02   /*  ... disabling interrupts. */
  64 #define RCUTORTURE_RDR_PREEMPT   0x04   /*  ... disabling preemption. */
  65 #define RCUTORTURE_RDR_RBH       0x08   /*  ... rcu_read_lock_bh(). */
  66 #define RCUTORTURE_RDR_SCHED     0x10   /*  ... rcu_read_lock_sched(). */
  67 #define RCUTORTURE_RDR_RCU_1     0x20   /*  ... entering another RCU reader. */
  68 #define RCUTORTURE_RDR_RCU_2     0x40   /*  ... entering another RCU reader. */
  69 #define RCUTORTURE_RDR_NBITS     7      /* Number of bits defined above. */
  70 #define RCUTORTURE_MAX_EXTEND    \
  71         (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  72          RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  73 #define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
  74                                         /* Must be power of two minus one. */
  75 #define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  76
  77 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  78               "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
  79 torture_param(int, fqs_duration, 0, "Duration of fqs bursts (us), 0 to disable");
  80 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  81 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  82 torture_param(int, fwd_progress, 1, "Number of grace-period forward progress tasks (0 to disable)");
  83 torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  84 torture_param(int, fwd_progress_holdoff, 60, "Time between forward-progress tests (s)");
  85 torture_param(bool, fwd_progress_need_resched, 1, "Hide cond_resched() behind need_resched()");
  86 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  87 torture_param(bool, gp_cond_exp, false, "Use conditional/async expedited GP wait primitives");
  88 torture_param(bool, gp_cond_full, false, "Use conditional/async full-state GP wait primitives");
  89 torture_param(bool, gp_cond_exp_full, false,
  90                     "Use conditional/async full-stateexpedited GP wait primitives");
  91 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  92 torture_param(bool, gp_normal, false, "Use normal (non-expedited) GP wait primitives");
  93 torture_param(bool, gp_poll, false, "Use polling GP wait primitives");
  94 torture_param(bool, gp_poll_exp, false, "Use polling expedited GP wait primitives");
  95 torture_param(bool, gp_poll_full, false, "Use polling full-state GP wait primitives");
  96 torture_param(bool, gp_poll_exp_full, false, "Use polling full-state expedited GP wait primitives");
  97 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  98 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  99 torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers");
 100 torture_param(int, n_barrier_cbs, 0, "# of callbacks/kthreads for barrier testing");
 101 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
 102 torture_param(int, nreaders, -1, "Number of RCU reader threads");
 103 torture_param(int, object_debug, 0, "Enable debug-object double call_rcu() testing");
 104 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
 105 torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (jiffies), 0=disable");
 106 torture_param(int, nocbs_nthreads, 0, "Number of NOCB toggle threads, 0 to disable");
 107 torture_param(int, nocbs_toggle, 1000, "Time between toggling nocb state (ms)");
 108 torture_param(int, read_exit_delay, 13, "Delay between read-then-exit episodes (s)");
 109 torture_param(int, read_exit_burst, 16, "# of read-then-exit bursts per episode, zero to disable");
 110 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
 111 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 112 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 113 torture_param(int, stall_cpu_holdoff, 10, "Time to wait before starting stall (s).");
 114 torture_param(bool, stall_no_softlockup, false, "Avoid softlockup warning during cpu stall.");
 115 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 116 torture_param(int, stall_cpu_block, 0, "Sleep while stalling.");
 117 torture_param(int, stall_gp_kthread, 0, "Grace-period kthread stall duration (s).");
 118 torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s");
 119 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 120 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 121 torture_param(int, test_boost_duration, 4, "Duration of each boost test, seconds.");
 122 torture_param(int, test_boost_interval, 7, "Interval between boost tests, seconds.");
 123 torture_param(int, test_nmis, 0, "End-test NMI tests, 0 to disable.");
 124 torture_param(bool, test_no_idle_hz, true, "Test support for tickless idle CPUs");
 125 torture_param(int, test_srcu_lockdep, 0, "Test specified SRCU deadlock scenario.");
 126 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
 127
 128 static char *torture_type = "rcu";
 129 module_param(torture_type, charp, 0444);
 130 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 131
 132 static int nrealnocbers;
 133 static int nrealreaders;
 134 static struct task_struct *writer_task;
 135 static struct task_struct **fakewriter_tasks;
 136 static struct task_struct **reader_tasks;
 137 static struct task_struct **nocb_tasks;
 138 static struct task_struct *stats_task;
 139 static struct task_struct *fqs_task;
 140 static struct task_struct *boost_tasks[NR_CPUS];
 141 static struct task_struct *stall_task;
 142 static struct task_struct **fwd_prog_tasks;
 143 static struct task_struct **barrier_cbs_tasks;
 144 static struct task_struct *barrier_task;
 145 static struct task_struct *read_exit_task;
 146
 147 #define RCU_TORTURE_PIPE_LEN 10
 148
 149 // Mailbox-like structure to check RCU global memory ordering.
 150 struct rcu_torture_reader_check {
 151         unsigned long rtc_myloops;
 152         int rtc_chkrdr;
 153         unsigned long rtc_chkloops;
 154         int rtc_ready;
 155         struct rcu_torture_reader_check *rtc_assigner;
 156 } ____cacheline_internodealigned_in_smp;
 157
 158 // Update-side data structure used to check RCU readers.
 159 struct rcu_torture {
 160         struct rcu_head rtort_rcu;
 161         int rtort_pipe_count;
 162         struct list_head rtort_free;
 163         int rtort_mbtest;
 164         struct rcu_torture_reader_check *rtort_chkp;
 165 };
 166
 167 static LIST_HEAD(rcu_torture_freelist);
 168 static struct rcu_torture __rcu *rcu_torture_current;
 169 static unsigned long rcu_torture_current_version;
 170 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 171 static DEFINE_SPINLOCK(rcu_torture_lock);
 172 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 173 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 174 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 175 static struct rcu_torture_reader_check *rcu_torture_reader_mbchk;
 176 static atomic_t n_rcu_torture_alloc;
 177 static atomic_t n_rcu_torture_alloc_fail;
 178 static atomic_t n_rcu_torture_free;
 179 static atomic_t n_rcu_torture_mberror;
 180 static atomic_t n_rcu_torture_mbchk_fail;
 181 static atomic_t n_rcu_torture_mbchk_tries;
 182 static atomic_t n_rcu_torture_error;
 183 static long n_rcu_torture_barrier_error;
 184 static long n_rcu_torture_boost_ktrerror;
 185 static long n_rcu_torture_boost_failure;
 186 static long n_rcu_torture_boosts;
 187 static atomic_long_t n_rcu_torture_timers;
 188 static long n_barrier_attempts;
 189 static long n_barrier_successes; /* did rcu_barrier test succeed? */
 190 static unsigned long n_read_exits;
 191 static struct list_head rcu_torture_removed;
 192 static unsigned long shutdown_jiffies;
 193 static unsigned long start_gp_seq;
 194 static atomic_long_t n_nocb_offload;
 195 static atomic_long_t n_nocb_deoffload;
 196
 197 static int rcu_torture_writer_state;
 198 #define RTWS_FIXED_DELAY        0
 199 #define RTWS_DELAY              1
 200 #define RTWS_REPLACE            2
 201 #define RTWS_DEF_FREE           3
 202 #define RTWS_EXP_SYNC           4
 203 #define RTWS_COND_GET           5
 204 #define RTWS_COND_GET_FULL      6
 205 #define RTWS_COND_GET_EXP       7
 206 #define RTWS_COND_GET_EXP_FULL  8
 207 #define RTWS_COND_SYNC          9
 208 #define RTWS_COND_SYNC_FULL     10
 209 #define RTWS_COND_SYNC_EXP      11
 210 #define RTWS_COND_SYNC_EXP_FULL 12
 211 #define RTWS_POLL_GET           13
 212 #define RTWS_POLL_GET_FULL      14
 213 #define RTWS_POLL_GET_EXP       15
 214 #define RTWS_POLL_GET_EXP_FULL  16
 215 #define RTWS_POLL_WAIT          17
 216 #define RTWS_POLL_WAIT_FULL     18
 217 #define RTWS_POLL_WAIT_EXP      19
 218 #define RTWS_POLL_WAIT_EXP_FULL 20
 219 #define RTWS_SYNC               21
 220 #define RTWS_STUTTER            22
 221 #define RTWS_STOPPING           23
 222 static const char * const rcu_torture_writer_state_names[] = {
 223         "RTWS_FIXED_DELAY",
 224         "RTWS_DELAY",
 225         "RTWS_REPLACE",
 226         "RTWS_DEF_FREE",
 227         "RTWS_EXP_SYNC",
 228         "RTWS_COND_GET",
 229         "RTWS_COND_GET_FULL",
 230         "RTWS_COND_GET_EXP",
 231         "RTWS_COND_GET_EXP_FULL",
 232         "RTWS_COND_SYNC",
 233         "RTWS_COND_SYNC_FULL",
 234         "RTWS_COND_SYNC_EXP",
 235         "RTWS_COND_SYNC_EXP_FULL",
 236         "RTWS_POLL_GET",
 237         "RTWS_POLL_GET_FULL",
 238         "RTWS_POLL_GET_EXP",
 239         "RTWS_POLL_GET_EXP_FULL",
 240         "RTWS_POLL_WAIT",
 241         "RTWS_POLL_WAIT_FULL",
 242         "RTWS_POLL_WAIT_EXP",
 243         "RTWS_POLL_WAIT_EXP_FULL",
 244         "RTWS_SYNC",
 245         "RTWS_STUTTER",
 246         "RTWS_STOPPING",
 247 };
 248
 249 /* Record reader segment types and duration for first failing read. */
 250 struct rt_read_seg {
 251         int rt_readstate;
 252         unsigned long rt_delay_jiffies;
 253         unsigned long rt_delay_ms;
 254         unsigned long rt_delay_us;
 255         bool rt_preempted;
 256 };
 257 static int err_segs_recorded;
 258 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 259 static int rt_read_nsegs;
 260
 261 static const char *rcu_torture_writer_state_getname(void)
 262 {
 263         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 264
 265         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 266                 return "???";
 267         return rcu_torture_writer_state_names[i];
 268 }
 269
 270 #ifdef CONFIG_RCU_TRACE
 271 static u64 notrace rcu_trace_clock_local(void)
 272 {
 273         u64 ts = trace_clock_local();
 274
 275         (void)do_div(ts, NSEC_PER_USEC);
 276         return ts;
 277 }
 278 #else /* #ifdef CONFIG_RCU_TRACE */
 279 static u64 notrace rcu_trace_clock_local(void)
 280 {
 281         return 0ULL;
 282 }
 283 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 284
 285 /*
 286  * Stop aggressive CPU-hog tests a bit before the end of the test in order
 287  * to avoid interfering with test shutdown.
 288  */
 289 static bool shutdown_time_arrived(void)
 290 {
 291         return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
 292 }
 293
 294 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 295 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 296                                         /*  and boost task create/destroy. */
 297 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 298 static bool barrier_phase;              /* Test phase. */
 299 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 300 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 301 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 302
 303 static atomic_t rcu_fwd_cb_nodelay;     /* Short rcu_torture_delay() delays. */
 304
 305 /*
 306  * Allocate an element from the rcu_tortures pool.
 307  */
 308 static struct rcu_torture *
 309 rcu_torture_alloc(void)
 310 {
 311         struct list_head *p;
 312
 313         spin_lock_bh(&rcu_torture_lock);
 314         if (list_empty(&rcu_torture_freelist)) {
 315                 atomic_inc(&n_rcu_torture_alloc_fail);
 316                 spin_unlock_bh(&rcu_torture_lock);
 317                 return NULL;
 318         }
 319         atomic_inc(&n_rcu_torture_alloc);
 320         p = rcu_torture_freelist.next;
 321         list_del_init(p);
 322         spin_unlock_bh(&rcu_torture_lock);
 323         return container_of(p, struct rcu_torture, rtort_free);
 324 }
 325
 326 /*
 327  * Free an element to the rcu_tortures pool.
 328  */
 329 static void
 330 rcu_torture_free(struct rcu_torture *p)
 331 {
 332         atomic_inc(&n_rcu_torture_free);
 333         spin_lock_bh(&rcu_torture_lock);
 334         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 335         spin_unlock_bh(&rcu_torture_lock);
 336 }
 337
 338 /*
 339  * Operations vector for selecting different types of tests.
 340  */
 341
 342 struct rcu_torture_ops {
 343         int ttype;
 344         void (*init)(void);
 345         void (*cleanup)(void);
 346         int (*readlock)(void);
 347         void (*read_delay)(struct torture_random_state *rrsp,
 348                            struct rt_read_seg *rtrsp);
 349         void (*readunlock)(int idx);
 350         int (*readlock_held)(void);
 351         unsigned long (*get_gp_seq)(void);
 352         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 353         void (*deferred_free)(struct rcu_torture *p);
 354         void (*sync)(void);
 355         void (*exp_sync)(void);
 356         unsigned long (*get_gp_state_exp)(void);
 357         unsigned long (*start_gp_poll_exp)(void);
 358         void (*start_gp_poll_exp_full)(struct rcu_gp_oldstate *rgosp);
 359         bool (*poll_gp_state_exp)(unsigned long oldstate);
 360         void (*cond_sync_exp)(unsigned long oldstate);
 361         void (*cond_sync_exp_full)(struct rcu_gp_oldstate *rgosp);
 362         unsigned long (*get_comp_state)(void);
 363         void (*get_comp_state_full)(struct rcu_gp_oldstate *rgosp);
 364         bool (*same_gp_state)(unsigned long oldstate1, unsigned long oldstate2);
 365         bool (*same_gp_state_full)(struct rcu_gp_oldstate *rgosp1, struct rcu_gp_oldstate *rgosp2);
 366         unsigned long (*get_gp_state)(void);
 367         void (*get_gp_state_full)(struct rcu_gp_oldstate *rgosp);
 368         unsigned long (*get_gp_completed)(void);
 369         void (*get_gp_completed_full)(struct rcu_gp_oldstate *rgosp);
 370         unsigned long (*start_gp_poll)(void);
 371         void (*start_gp_poll_full)(struct rcu_gp_oldstate *rgosp);
 372         bool (*poll_gp_state)(unsigned long oldstate);
 373         bool (*poll_gp_state_full)(struct rcu_gp_oldstate *rgosp);
 374         bool (*poll_need_2gp)(bool poll, bool poll_full);
 375         void (*cond_sync)(unsigned long oldstate);
 376         void (*cond_sync_full)(struct rcu_gp_oldstate *rgosp);
 377         call_rcu_func_t call;
 378         void (*cb_barrier)(void);
 379         void (*fqs)(void);
 380         void (*stats)(void);
 381         void (*gp_kthread_dbg)(void);
 382         bool (*check_boost_failed)(unsigned long gp_state, int *cpup);
 383         int (*stall_dur)(void);
 384         void (*get_gp_data)(int *flags, unsigned long *gp_seq);
 385         void (*gp_slow_register)(atomic_t *rgssp);
 386         void (*gp_slow_unregister)(atomic_t *rgssp);
 387         long cbflood_max;
 388         int irq_capable;
 389         int can_boost;
 390         int extendables;
 391         int slow_gps;
 392         int no_pi_lock;
 393         const char *name;
 394 };
 395
 396 static struct rcu_torture_ops *cur_ops;
 397
 398 /*
 399  * Definitions for rcu torture testing.
 400  */
 401
 402 static int torture_readlock_not_held(void)
 403 {
 404         return rcu_read_lock_bh_held() || rcu_read_lock_sched_held();
 405 }
 406
 407 static int rcu_torture_read_lock(void)
 408 {
 409         rcu_read_lock();
 410         return 0;
 411 }
 412
 413 static void
 414 rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 415 {
 416         unsigned long started;
 417         unsigned long completed;
 418         const unsigned long shortdelay_us = 200;
 419         unsigned long longdelay_ms = 300;
 420         unsigned long long ts;
 421
 422         /* We want a short delay sometimes to make a reader delay the grace
 423          * period, and we want a long delay occasionally to trigger
 424          * force_quiescent_state. */
 425
 426         if (!atomic_read(&rcu_fwd_cb_nodelay) &&
 427             !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 428                 started = cur_ops->get_gp_seq();
 429                 ts = rcu_trace_clock_local();
 430                 if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 431                         longdelay_ms = 5; /* Avoid triggering BH limits. */
 432                 mdelay(longdelay_ms);
 433                 rtrsp->rt_delay_ms = longdelay_ms;
 434                 completed = cur_ops->get_gp_seq();
 435                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 436                                           started, completed);
 437         }
 438         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 439                 udelay(shortdelay_us);
 440                 rtrsp->rt_delay_us = shortdelay_us;
 441         }
 442         if (!preempt_count() &&
 443             !(torture_random(rrsp) % (nrealreaders * 500))) {
 444                 torture_preempt_schedule();  /* QS only if preemptible. */
 445                 rtrsp->rt_preempted = true;
 446         }
 447 }
 448
 449 static void rcu_torture_read_unlock(int idx)
 450 {
 451         rcu_read_unlock();
 452 }
 453
 454 /*
 455  * Update callback in the pipe.  This should be invoked after a grace period.
 456  */
 457 static bool
 458 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 459 {
 460         int i;
 461         struct rcu_torture_reader_check *rtrcp = READ_ONCE(rp->rtort_chkp);
 462
 463         if (rtrcp) {
 464                 WRITE_ONCE(rp->rtort_chkp, NULL);
 465                 smp_store_release(&rtrcp->rtc_ready, 1); // Pair with smp_load_acquire().
 466         }
 467         i = rp->rtort_pipe_count;
 468         if (i > RCU_TORTURE_PIPE_LEN)
 469                 i = RCU_TORTURE_PIPE_LEN;
 470         atomic_inc(&rcu_torture_wcount[i]);
 471         WRITE_ONCE(rp->rtort_pipe_count, i + 1);
 472         ASSERT_EXCLUSIVE_WRITER(rp->rtort_pipe_count);
 473         if (i + 1 >= RCU_TORTURE_PIPE_LEN) {
 474                 rp->rtort_mbtest = 0;
 475                 return true;
 476         }
 477         return false;
 478 }
 479
 480 /*
 481  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 482  * primitives.
 483  */
 484 static void
 485 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 486 {
 487         struct rcu_torture *rp;
 488         struct rcu_torture *rp1;
 489
 490         if (old_rp)
 491                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 492         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 493                 if (rcu_torture_pipe_update_one(rp)) {
 494                         list_del(&rp->rtort_free);
 495                         rcu_torture_free(rp);
 496                 }
 497         }
 498 }
 499
 500 static void
 501 rcu_torture_cb(struct rcu_head *p)
 502 {
 503         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 504
 505         if (torture_must_stop_irq()) {
 506                 /* Test is ending, just drop callbacks on the floor. */
 507                 /* The next initialization will pick up the pieces. */
 508                 return;
 509         }
 510         if (rcu_torture_pipe_update_one(rp))
 511                 rcu_torture_free(rp);
 512         else
 513                 cur_ops->deferred_free(rp);
 514 }
 515
 516 static unsigned long rcu_no_completed(void)
 517 {
 518         return 0;
 519 }
 520
 521 static void rcu_torture_deferred_free(struct rcu_torture *p)
 522 {
 523         call_rcu_hurry(&p->rtort_rcu, rcu_torture_cb);
 524 }
 525
 526 static void rcu_sync_torture_init(void)
 527 {
 528         INIT_LIST_HEAD(&rcu_torture_removed);
 529 }
 530
 531 static bool rcu_poll_need_2gp(bool poll, bool poll_full)
 532 {
 533         return poll;
 534 }
 535
 536 static struct rcu_torture_ops rcu_ops = {
 537         .ttype                  = RCU_FLAVOR,
 538         .init                   = rcu_sync_torture_init,
 539         .readlock               = rcu_torture_read_lock,
 540         .read_delay             = rcu_read_delay,
 541         .readunlock             = rcu_torture_read_unlock,
 542         .readlock_held          = torture_readlock_not_held,
 543         .get_gp_seq             = rcu_get_gp_seq,
 544         .gp_diff                = rcu_seq_diff,
 545         .deferred_free          = rcu_torture_deferred_free,
 546         .sync                   = synchronize_rcu,
 547         .exp_sync               = synchronize_rcu_expedited,
 548         .same_gp_state          = same_state_synchronize_rcu,
 549         .same_gp_state_full     = same_state_synchronize_rcu_full,
 550         .get_comp_state         = get_completed_synchronize_rcu,
 551         .get_comp_state_full    = get_completed_synchronize_rcu_full,
 552         .get_gp_state           = get_state_synchronize_rcu,
 553         .get_gp_state_full      = get_state_synchronize_rcu_full,
 554         .get_gp_completed       = get_completed_synchronize_rcu,
 555         .get_gp_completed_full  = get_completed_synchronize_rcu_full,
 556         .start_gp_poll          = start_poll_synchronize_rcu,
 557         .start_gp_poll_full     = start_poll_synchronize_rcu_full,
 558         .poll_gp_state          = poll_state_synchronize_rcu,
 559         .poll_gp_state_full     = poll_state_synchronize_rcu_full,
 560         .poll_need_2gp          = rcu_poll_need_2gp,
 561         .cond_sync              = cond_synchronize_rcu,
 562         .cond_sync_full         = cond_synchronize_rcu_full,
 563         .get_gp_state_exp       = get_state_synchronize_rcu,
 564         .start_gp_poll_exp      = start_poll_synchronize_rcu_expedited,
 565         .start_gp_poll_exp_full = start_poll_synchronize_rcu_expedited_full,
 566         .poll_gp_state_exp      = poll_state_synchronize_rcu,
 567         .cond_sync_exp          = cond_synchronize_rcu_expedited,
 568         .call                   = call_rcu_hurry,
 569         .cb_barrier             = rcu_barrier,
 570         .fqs                    = rcu_force_quiescent_state,
 571         .gp_kthread_dbg         = show_rcu_gp_kthreads,
 572         .check_boost_failed     = rcu_check_boost_fail,
 573         .stall_dur              = rcu_jiffies_till_stall_check,
 574         .get_gp_data            = rcutorture_get_gp_data,
 575         .gp_slow_register       = rcu_gp_slow_register,
 576         .gp_slow_unregister     = rcu_gp_slow_unregister,
 577         .irq_capable            = 1,
 578         .can_boost              = IS_ENABLED(CONFIG_RCU_BOOST),
 579         .extendables            = RCUTORTURE_MAX_EXTEND,
 580         .name                   = "rcu"
 581 };
 582
 583 /*
 584  * Don't even think about trying any of these in real life!!!
 585  * The names includes "busted", and they really means it!
 586  * The only purpose of these functions is to provide a buggy RCU
 587  * implementation to make sure that rcutorture correctly emits
 588  * buggy-RCU error messages.
 589  */
 590 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 591 {
 592         /* This is a deliberate bug for testing purposes only! */
 593         rcu_torture_cb(&p->rtort_rcu);
 594 }
 595
 596 static void synchronize_rcu_busted(void)
 597 {
 598         /* This is a deliberate bug for testing purposes only! */
 599 }
 600
 601 static void
 602 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 603 {
 604         /* This is a deliberate bug for testing purposes only! */
 605         func(head);
 606 }
 607
 608 static struct rcu_torture_ops rcu_busted_ops = {
 609         .ttype          = INVALID_RCU_FLAVOR,
 610         .init           = rcu_sync_torture_init,
 611         .readlock       = rcu_torture_read_lock,
 612         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 613         .readunlock     = rcu_torture_read_unlock,
 614         .readlock_held  = torture_readlock_not_held,
 615         .get_gp_seq     = rcu_no_completed,
 616         .deferred_free  = rcu_busted_torture_deferred_free,
 617         .sync           = synchronize_rcu_busted,
 618         .exp_sync       = synchronize_rcu_busted,
 619         .call           = call_rcu_busted,
 620         .irq_capable    = 1,
 621         .name           = "busted"
 622 };
 623
 624 /*
 625  * Definitions for srcu torture testing.
 626  */
 627
 628 DEFINE_STATIC_SRCU(srcu_ctl);
 629 static struct srcu_struct srcu_ctld;
 630 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 631 static struct rcu_torture_ops srcud_ops;
 632
 633 static void srcu_get_gp_data(int *flags, unsigned long *gp_seq)
 634 {
 635         srcutorture_get_gp_data(srcu_ctlp, flags, gp_seq);
 636 }
 637
 638 static int srcu_torture_read_lock(void)
 639 {
 640         if (cur_ops == &srcud_ops)
 641                 return srcu_read_lock_nmisafe(srcu_ctlp);
 642         else
 643                 return srcu_read_lock(srcu_ctlp);
 644 }
 645
 646 static void
 647 srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 648 {
 649         long delay;
 650         const long uspertick = 1000000 / HZ;
 651         const long longdelay = 10;
 652
 653         /* We want there to be long-running readers, but not all the time. */
 654
 655         delay = torture_random(rrsp) %
 656                 (nrealreaders * 2 * longdelay * uspertick);
 657         if (!delay && in_task()) {
 658                 schedule_timeout_interruptible(longdelay);
 659                 rtrsp->rt_delay_jiffies = longdelay;
 660         } else {
 661                 rcu_read_delay(rrsp, rtrsp);
 662         }
 663 }
 664
 665 static void srcu_torture_read_unlock(int idx)
 666 {
 667         if (cur_ops == &srcud_ops)
 668                 srcu_read_unlock_nmisafe(srcu_ctlp, idx);
 669         else
 670                 srcu_read_unlock(srcu_ctlp, idx);
 671 }
 672
 673 static int torture_srcu_read_lock_held(void)
 674 {
 675         return srcu_read_lock_held(srcu_ctlp);
 676 }
 677
 678 static unsigned long srcu_torture_completed(void)
 679 {
 680         return srcu_batches_completed(srcu_ctlp);
 681 }
 682
 683 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 684 {
 685         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 686 }
 687
 688 static void srcu_torture_synchronize(void)
 689 {
 690         synchronize_srcu(srcu_ctlp);
 691 }
 692
 693 static unsigned long srcu_torture_get_gp_state(void)
 694 {
 695         return get_state_synchronize_srcu(srcu_ctlp);
 696 }
 697
 698 static unsigned long srcu_torture_start_gp_poll(void)
 699 {
 700         return start_poll_synchronize_srcu(srcu_ctlp);
 701 }
 702
 703 static bool srcu_torture_poll_gp_state(unsigned long oldstate)
 704 {
 705         return poll_state_synchronize_srcu(srcu_ctlp, oldstate);
 706 }
 707
 708 static void srcu_torture_call(struct rcu_head *head,
 709                               rcu_callback_t func)
 710 {
 711         call_srcu(srcu_ctlp, head, func);
 712 }
 713
 714 static void srcu_torture_barrier(void)
 715 {
 716         srcu_barrier(srcu_ctlp);
 717 }
 718
 719 static void srcu_torture_stats(void)
 720 {
 721         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 722 }
 723
 724 static void srcu_torture_synchronize_expedited(void)
 725 {
 726         synchronize_srcu_expedited(srcu_ctlp);
 727 }
 728
 729 static struct rcu_torture_ops srcu_ops = {
 730         .ttype          = SRCU_FLAVOR,
 731         .init           = rcu_sync_torture_init,
 732         .readlock       = srcu_torture_read_lock,
 733         .read_delay     = srcu_read_delay,
 734         .readunlock     = srcu_torture_read_unlock,
 735         .readlock_held  = torture_srcu_read_lock_held,
 736         .get_gp_seq     = srcu_torture_completed,
 737         .deferred_free  = srcu_torture_deferred_free,
 738         .sync           = srcu_torture_synchronize,
 739         .exp_sync       = srcu_torture_synchronize_expedited,
 740         .get_gp_state   = srcu_torture_get_gp_state,
 741         .start_gp_poll  = srcu_torture_start_gp_poll,
 742         .poll_gp_state  = srcu_torture_poll_gp_state,
 743         .call           = srcu_torture_call,
 744         .cb_barrier     = srcu_torture_barrier,
 745         .stats          = srcu_torture_stats,
 746         .get_gp_data    = srcu_get_gp_data,
 747         .cbflood_max    = 50000,
 748         .irq_capable    = 1,
 749         .no_pi_lock     = IS_ENABLED(CONFIG_TINY_SRCU),
 750         .name           = "srcu"
 751 };
 752
 753 static void srcu_torture_init(void)
 754 {
 755         rcu_sync_torture_init();
 756         WARN_ON(init_srcu_struct(&srcu_ctld));
 757         srcu_ctlp = &srcu_ctld;
 758 }
 759
 760 static void srcu_torture_cleanup(void)
 761 {
 762         cleanup_srcu_struct(&srcu_ctld);
 763         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 764 }
 765
 766 /* As above, but dynamically allocated. */
 767 static struct rcu_torture_ops srcud_ops = {
 768         .ttype          = SRCU_FLAVOR,
 769         .init           = srcu_torture_init,
 770         .cleanup        = srcu_torture_cleanup,
 771         .readlock       = srcu_torture_read_lock,
 772         .read_delay     = srcu_read_delay,
 773         .readunlock     = srcu_torture_read_unlock,
 774         .readlock_held  = torture_srcu_read_lock_held,
 775         .get_gp_seq     = srcu_torture_completed,
 776         .deferred_free  = srcu_torture_deferred_free,
 777         .sync           = srcu_torture_synchronize,
 778         .exp_sync       = srcu_torture_synchronize_expedited,
 779         .get_gp_state   = srcu_torture_get_gp_state,
 780         .start_gp_poll  = srcu_torture_start_gp_poll,
 781         .poll_gp_state  = srcu_torture_poll_gp_state,
 782         .call           = srcu_torture_call,
 783         .cb_barrier     = srcu_torture_barrier,
 784         .stats          = srcu_torture_stats,
 785         .get_gp_data    = srcu_get_gp_data,
 786         .cbflood_max    = 50000,
 787         .irq_capable    = 1,
 788         .no_pi_lock     = IS_ENABLED(CONFIG_TINY_SRCU),
 789         .name           = "srcud"
 790 };
 791
 792 /* As above, but broken due to inappropriate reader extension. */
 793 static struct rcu_torture_ops busted_srcud_ops = {
 794         .ttype          = SRCU_FLAVOR,
 795         .init           = srcu_torture_init,
 796         .cleanup        = srcu_torture_cleanup,
 797         .readlock       = srcu_torture_read_lock,
 798         .read_delay     = rcu_read_delay,
 799         .readunlock     = srcu_torture_read_unlock,
 800         .readlock_held  = torture_srcu_read_lock_held,
 801         .get_gp_seq     = srcu_torture_completed,
 802         .deferred_free  = srcu_torture_deferred_free,
 803         .sync           = srcu_torture_synchronize,
 804         .exp_sync       = srcu_torture_synchronize_expedited,
 805         .call           = srcu_torture_call,
 806         .cb_barrier     = srcu_torture_barrier,
 807         .stats          = srcu_torture_stats,
 808         .irq_capable    = 1,
 809         .no_pi_lock     = IS_ENABLED(CONFIG_TINY_SRCU),
 810         .extendables    = RCUTORTURE_MAX_EXTEND,
 811         .name           = "busted_srcud"
 812 };
 813
 814 /*
 815  * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
 816  * This implementation does not necessarily work well with CPU hotplug.
 817  */
 818
 819 static void synchronize_rcu_trivial(void)
 820 {
 821         int cpu;
 822
 823         for_each_online_cpu(cpu) {
 824                 torture_sched_setaffinity(current->pid, cpumask_of(cpu));
 825                 WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 826         }
 827 }
 828
 829 static int rcu_torture_read_lock_trivial(void)
 830 {
 831         preempt_disable();
 832         return 0;
 833 }
 834
 835 static void rcu_torture_read_unlock_trivial(int idx)
 836 {
 837         preempt_enable();
 838 }
 839
 840 static struct rcu_torture_ops trivial_ops = {
 841         .ttype          = RCU_TRIVIAL_FLAVOR,
 842         .init           = rcu_sync_torture_init,
 843         .readlock       = rcu_torture_read_lock_trivial,
 844         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 845         .readunlock     = rcu_torture_read_unlock_trivial,
 846         .readlock_held  = torture_readlock_not_held,
 847         .get_gp_seq     = rcu_no_completed,
 848         .sync           = synchronize_rcu_trivial,
 849         .exp_sync       = synchronize_rcu_trivial,
 850         .irq_capable    = 1,
 851         .name           = "trivial"
 852 };
 853
 854 #ifdef CONFIG_TASKS_RCU
 855
 856 /*
 857  * Definitions for RCU-tasks torture testing.
 858  */
 859
 860 static int tasks_torture_read_lock(void)
 861 {
 862         return 0;
 863 }
 864
 865 static void tasks_torture_read_unlock(int idx)
 866 {
 867 }
 868
 869 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 870 {
 871         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 872 }
 873
 874 static void synchronize_rcu_mult_test(void)
 875 {
 876         synchronize_rcu_mult(call_rcu_tasks, call_rcu_hurry);
 877 }
 878
 879 static struct rcu_torture_ops tasks_ops = {
 880         .ttype          = RCU_TASKS_FLAVOR,
 881         .init           = rcu_sync_torture_init,
 882         .readlock       = tasks_torture_read_lock,
 883         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 884         .readunlock     = tasks_torture_read_unlock,
 885         .get_gp_seq     = rcu_no_completed,
 886         .deferred_free  = rcu_tasks_torture_deferred_free,
 887         .sync           = synchronize_rcu_tasks,
 888         .exp_sync       = synchronize_rcu_mult_test,
 889         .call           = call_rcu_tasks,
 890         .cb_barrier     = rcu_barrier_tasks,
 891         .gp_kthread_dbg = show_rcu_tasks_classic_gp_kthread,
 892         .get_gp_data    = rcu_tasks_get_gp_data,
 893         .irq_capable    = 1,
 894         .slow_gps       = 1,
 895         .name           = "tasks"
 896 };
 897
 898 #define TASKS_OPS &tasks_ops,
 899
 900 #else // #ifdef CONFIG_TASKS_RCU
 901
 902 #define TASKS_OPS
 903
 904 #endif // #else #ifdef CONFIG_TASKS_RCU
 905
 906
 907 #ifdef CONFIG_TASKS_RUDE_RCU
 908
 909 /*
 910  * Definitions for rude RCU-tasks torture testing.
 911  */
 912
 913 static void rcu_tasks_rude_torture_deferred_free(struct rcu_torture *p)
 914 {
 915         call_rcu_tasks_rude(&p->rtort_rcu, rcu_torture_cb);
 916 }
 917
 918 static struct rcu_torture_ops tasks_rude_ops = {
 919         .ttype          = RCU_TASKS_RUDE_FLAVOR,
 920         .init           = rcu_sync_torture_init,
 921         .readlock       = rcu_torture_read_lock_trivial,
 922         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 923         .readunlock     = rcu_torture_read_unlock_trivial,
 924         .get_gp_seq     = rcu_no_completed,
 925         .deferred_free  = rcu_tasks_rude_torture_deferred_free,
 926         .sync           = synchronize_rcu_tasks_rude,
 927         .exp_sync       = synchronize_rcu_tasks_rude,
 928         .call           = call_rcu_tasks_rude,
 929         .cb_barrier     = rcu_barrier_tasks_rude,
 930         .gp_kthread_dbg = show_rcu_tasks_rude_gp_kthread,
 931         .get_gp_data    = rcu_tasks_rude_get_gp_data,
 932         .cbflood_max    = 50000,
 933         .irq_capable    = 1,
 934         .name           = "tasks-rude"
 935 };
 936
 937 #define TASKS_RUDE_OPS &tasks_rude_ops,
 938
 939 #else // #ifdef CONFIG_TASKS_RUDE_RCU
 940
 941 #define TASKS_RUDE_OPS
 942
 943 #endif // #else #ifdef CONFIG_TASKS_RUDE_RCU
 944
 945
 946 #ifdef CONFIG_TASKS_TRACE_RCU
 947
 948 /*
 949  * Definitions for tracing RCU-tasks torture testing.
 950  */
 951
 952 static int tasks_tracing_torture_read_lock(void)
 953 {
 954         rcu_read_lock_trace();
 955         return 0;
 956 }
 957
 958 static void tasks_tracing_torture_read_unlock(int idx)
 959 {
 960         rcu_read_unlock_trace();
 961 }
 962
 963 static void rcu_tasks_tracing_torture_deferred_free(struct rcu_torture *p)
 964 {
 965         call_rcu_tasks_trace(&p->rtort_rcu, rcu_torture_cb);
 966 }
 967
 968 static struct rcu_torture_ops tasks_tracing_ops = {
 969         .ttype          = RCU_TASKS_TRACING_FLAVOR,
 970         .init           = rcu_sync_torture_init,
 971         .readlock       = tasks_tracing_torture_read_lock,
 972         .read_delay     = srcu_read_delay,  /* just reuse srcu's version. */
 973         .readunlock     = tasks_tracing_torture_read_unlock,
 974         .readlock_held  = rcu_read_lock_trace_held,
 975         .get_gp_seq     = rcu_no_completed,
 976         .deferred_free  = rcu_tasks_tracing_torture_deferred_free,
 977         .sync           = synchronize_rcu_tasks_trace,
 978         .exp_sync       = synchronize_rcu_tasks_trace,
 979         .call           = call_rcu_tasks_trace,
 980         .cb_barrier     = rcu_barrier_tasks_trace,
 981         .gp_kthread_dbg = show_rcu_tasks_trace_gp_kthread,
 982         .get_gp_data    = rcu_tasks_trace_get_gp_data,
 983         .cbflood_max    = 50000,
 984         .irq_capable    = 1,
 985         .slow_gps       = 1,
 986         .name           = "tasks-tracing"
 987 };
 988
 989 #define TASKS_TRACING_OPS &tasks_tracing_ops,
 990
 991 #else // #ifdef CONFIG_TASKS_TRACE_RCU
 992
 993 #define TASKS_TRACING_OPS
 994
 995 #endif // #else #ifdef CONFIG_TASKS_TRACE_RCU
 996
 997
 998 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 999 {
1000         if (!cur_ops->gp_diff)
1001                 return new - old;
1002         return cur_ops->gp_diff(new, old);
1003 }
1004
1005 /*
1006  * RCU torture priority-boost testing.  Runs one real-time thread per
1007  * CPU for moderate bursts, repeatedly starting grace periods and waiting
1008  * for them to complete.  If a given grace period takes too long, we assume
1009  * that priority inversion has occurred.
1010  */
1011
1012 static int old_rt_runtime = -1;
1013
1014 static void rcu_torture_disable_rt_throttle(void)
1015 {
1016         /*
1017          * Disable RT throttling so that rcutorture's boost threads don't get
1018          * throttled. Only possible if rcutorture is built-in otherwise the
1019          * user should manually do this by setting the sched_rt_period_us and
1020          * sched_rt_runtime sysctls.
1021          */
1022         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
1023                 return;
1024
1025         old_rt_runtime = sysctl_sched_rt_runtime;
1026         sysctl_sched_rt_runtime = -1;
1027 }
1028
1029 static void rcu_torture_enable_rt_throttle(void)
1030 {
1031         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
1032                 return;
1033
1034         sysctl_sched_rt_runtime = old_rt_runtime;
1035         old_rt_runtime = -1;
1036 }
1037
1038 static bool rcu_torture_boost_failed(unsigned long gp_state, unsigned long *start)
1039 {
1040         int cpu;
1041         static int dbg_done;
1042         unsigned long end = jiffies;
1043         bool gp_done;
1044         unsigned long j;
1045         static unsigned long last_persist;
1046         unsigned long lp;
1047         unsigned long mininterval = test_boost_duration * HZ - HZ / 2;
1048
1049         if (end - *start > mininterval) {
1050                 // Recheck after checking time to avoid false positives.
1051                 smp_mb(); // Time check before grace-period check.
1052                 if (cur_ops->poll_gp_state(gp_state))
1053                         return false; // passed, though perhaps just barely
1054                 if (cur_ops->check_boost_failed && !cur_ops->check_boost_failed(gp_state, &cpu)) {
1055                         // At most one persisted message per boost test.
1056                         j = jiffies;
1057                         lp = READ_ONCE(last_persist);
1058                         if (time_after(j, lp + mininterval) && cmpxchg(&last_persist, lp, j) == lp)
1059                                 pr_info("Boost inversion persisted: No QS from CPU %d\n", cpu);
1060                         return false; // passed on a technicality
1061                 }
1062                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
1063                 n_rcu_torture_boost_failure++;
1064                 if (!xchg(&dbg_done, 1) && cur_ops->gp_kthread_dbg) {
1065                         pr_info("Boost inversion thread ->rt_priority %u gp_state %lu jiffies %lu\n",
1066                                 current->rt_priority, gp_state, end - *start);
1067                         cur_ops->gp_kthread_dbg();
1068                         // Recheck after print to flag grace period ending during splat.
1069                         gp_done = cur_ops->poll_gp_state(gp_state);
1070                         pr_info("Boost inversion: GP %lu %s.\n", gp_state,
1071                                 gp_done ? "ended already" : "still pending");
1072
1073                 }
1074
1075                 return true; // failed
1076         } else if (cur_ops->check_boost_failed && !cur_ops->check_boost_failed(gp_state, NULL)) {
1077                 *start = jiffies;
1078         }
1079
1080         return false; // passed
1081 }
1082
1083 static int rcu_torture_boost(void *arg)
1084 {
1085         unsigned long endtime;
1086         unsigned long gp_state;
1087         unsigned long gp_state_time;
1088         unsigned long oldstarttime;
1089
1090         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
1091
1092         /* Set real-time priority. */
1093         sched_set_fifo_low(current);
1094
1095         /* Each pass through the following loop does one boost-test cycle. */
1096         do {
1097                 bool failed = false; // Test failed already in this test interval
1098                 bool gp_initiated = false;
1099
1100                 if (kthread_should_stop())
1101                         goto checkwait;
1102
1103                 /* Wait for the next test interval. */
1104                 oldstarttime = READ_ONCE(boost_starttime);
1105                 while (time_before(jiffies, oldstarttime)) {
1106                         schedule_timeout_interruptible(oldstarttime - jiffies);
1107                         if (stutter_wait("rcu_torture_boost"))
1108                                 sched_set_fifo_low(current);
1109                         if (torture_must_stop())
1110                                 goto checkwait;
1111                 }
1112
1113                 // Do one boost-test interval.
1114                 endtime = oldstarttime + test_boost_duration * HZ;
1115                 while (time_before(jiffies, endtime)) {
1116                         // Has current GP gone too long?
1117                         if (gp_initiated && !failed && !cur_ops->poll_gp_state(gp_state))
1118                                 failed = rcu_torture_boost_failed(gp_state, &gp_state_time);
1119                         // If we don't have a grace period in flight, start one.
1120                         if (!gp_initiated || cur_ops->poll_gp_state(gp_state)) {
1121                                 gp_state = cur_ops->start_gp_poll();
1122                                 gp_initiated = true;
1123                                 gp_state_time = jiffies;
1124                         }
1125                         if (stutter_wait("rcu_torture_boost")) {
1126                                 sched_set_fifo_low(current);
1127                                 // If the grace period already ended,
1128                                 // we don't know when that happened, so
1129                                 // start over.
1130                                 if (cur_ops->poll_gp_state(gp_state))
1131                                         gp_initiated = false;
1132                         }
1133                         if (torture_must_stop())
1134                                 goto checkwait;
1135                 }
1136
1137                 // In case the grace period extended beyond the end of the loop.
1138                 if (gp_initiated && !failed && !cur_ops->poll_gp_state(gp_state))
1139                         rcu_torture_boost_failed(gp_state, &gp_state_time);
1140
1141                 /*
1142                  * Set the start time of the next test interval.
1143                  * Yes, this is vulnerable to long delays, but such
1144                  * delays simply cause a false negative for the next
1145                  * interval.  Besides, we are running at RT priority,
1146                  * so delays should be relatively rare.
1147                  */
1148                 while (oldstarttime == READ_ONCE(boost_starttime) && !kthread_should_stop()) {
1149                         if (mutex_trylock(&boost_mutex)) {
1150                                 if (oldstarttime == boost_starttime) {
1151                                         WRITE_ONCE(boost_starttime,
1152                                                    jiffies + test_boost_interval * HZ);
1153                                         n_rcu_torture_boosts++;
1154                                 }
1155                                 mutex_unlock(&boost_mutex);
1156                                 break;
1157                         }
1158                         schedule_timeout_uninterruptible(HZ / 20);
1159                 }
1160
1161                 /* Go do the stutter. */
1162 checkwait:      if (stutter_wait("rcu_torture_boost"))
1163                         sched_set_fifo_low(current);
1164         } while (!torture_must_stop());
1165
1166         /* Clean up and exit. */
1167         while (!kthread_should_stop()) {
1168                 torture_shutdown_absorb("rcu_torture_boost");
1169                 schedule_timeout_uninterruptible(HZ / 20);
1170         }
1171         torture_kthread_stopping("rcu_torture_boost");
1172         return 0;
1173 }
1174
1175 /*
1176  * RCU torture force-quiescent-state kthread.  Repeatedly induces
1177  * bursts of calls to force_quiescent_state(), increasing the probability
1178  * of occurrence of some important types of race conditions.
1179  */
1180 static int
1181 rcu_torture_fqs(void *arg)
1182 {
1183         unsigned long fqs_resume_time;
1184         int fqs_burst_remaining;
1185         int oldnice = task_nice(current);
1186
1187         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
1188         do {
1189                 fqs_resume_time = jiffies + fqs_stutter * HZ;
1190                 while (time_before(jiffies, fqs_resume_time) &&
1191                        !kthread_should_stop()) {
1192                         schedule_timeout_interruptible(HZ / 20);
1193                 }
1194                 fqs_burst_remaining = fqs_duration;
1195                 while (fqs_burst_remaining > 0 &&
1196                        !kthread_should_stop()) {
1197                         cur_ops->fqs();
1198                         udelay(fqs_holdoff);
1199                         fqs_burst_remaining -= fqs_holdoff;
1200                 }
1201                 if (stutter_wait("rcu_torture_fqs"))
1202                         sched_set_normal(current, oldnice);
1203         } while (!torture_must_stop());
1204         torture_kthread_stopping("rcu_torture_fqs");
1205         return 0;
1206 }
1207
1208 // Used by writers to randomly choose from the available grace-period primitives.
1209 static int synctype[ARRAY_SIZE(rcu_torture_writer_state_names)] = { };
1210 static int nsynctypes;
1211
1212 /*
1213  * Determine which grace-period primitives are available.
1214  */
1215 static void rcu_torture_write_types(void)
1216 {
1217         bool gp_cond1 = gp_cond, gp_cond_exp1 = gp_cond_exp, gp_cond_full1 = gp_cond_full;
1218         bool gp_cond_exp_full1 = gp_cond_exp_full, gp_exp1 = gp_exp, gp_poll_exp1 = gp_poll_exp;
1219         bool gp_poll_exp_full1 = gp_poll_exp_full, gp_normal1 = gp_normal, gp_poll1 = gp_poll;
1220         bool gp_poll_full1 = gp_poll_full, gp_sync1 = gp_sync;
1221
1222         /* Initialize synctype[] array.  If none set, take default. */
1223         if (!gp_cond1 &&
1224             !gp_cond_exp1 &&
1225             !gp_cond_full1 &&
1226             !gp_cond_exp_full1 &&
1227             !gp_exp1 &&
1228             !gp_poll_exp1 &&
1229             !gp_poll_exp_full1 &&
1230             !gp_normal1 &&
1231             !gp_poll1 &&
1232             !gp_poll_full1 &&
1233             !gp_sync1) {
1234                 gp_cond1 = true;
1235                 gp_cond_exp1 = true;
1236                 gp_cond_full1 = true;
1237                 gp_cond_exp_full1 = true;
1238                 gp_exp1 = true;
1239                 gp_poll_exp1 = true;
1240                 gp_poll_exp_full1 = true;
1241                 gp_normal1 = true;
1242                 gp_poll1 = true;
1243                 gp_poll_full1 = true;
1244                 gp_sync1 = true;
1245         }
1246         if (gp_cond1 && cur_ops->get_gp_state && cur_ops->cond_sync) {
1247                 synctype[nsynctypes++] = RTWS_COND_GET;
1248                 pr_info("%s: Testing conditional GPs.\n", __func__);
1249         } else if (gp_cond && (!cur_ops->get_gp_state || !cur_ops->cond_sync)) {
1250                 pr_alert("%s: gp_cond without primitives.\n", __func__);
1251         }
1252         if (gp_cond_exp1 && cur_ops->get_gp_state_exp && cur_ops->cond_sync_exp) {
1253                 synctype[nsynctypes++] = RTWS_COND_GET_EXP;
1254                 pr_info("%s: Testing conditional expedited GPs.\n", __func__);
1255         } else if (gp_cond_exp && (!cur_ops->get_gp_state_exp || !cur_ops->cond_sync_exp)) {
1256                 pr_alert("%s: gp_cond_exp without primitives.\n", __func__);
1257         }
1258         if (gp_cond_full1 && cur_ops->get_gp_state && cur_ops->cond_sync_full) {
1259                 synctype[nsynctypes++] = RTWS_COND_GET_FULL;
1260                 pr_info("%s: Testing conditional full-state GPs.\n", __func__);
1261         } else if (gp_cond_full && (!cur_ops->get_gp_state || !cur_ops->cond_sync_full)) {
1262                 pr_alert("%s: gp_cond_full without primitives.\n", __func__);
1263         }
1264         if (gp_cond_exp_full1 && cur_ops->get_gp_state_exp && cur_ops->cond_sync_exp_full) {
1265                 synctype[nsynctypes++] = RTWS_COND_GET_EXP_FULL;
1266                 pr_info("%s: Testing conditional full-state expedited GPs.\n", __func__);
1267         } else if (gp_cond_exp_full &&
1268                    (!cur_ops->get_gp_state_exp || !cur_ops->cond_sync_exp_full)) {
1269                 pr_alert("%s: gp_cond_exp_full without primitives.\n", __func__);
1270         }
1271         if (gp_exp1 && cur_ops->exp_sync) {
1272                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
1273                 pr_info("%s: Testing expedited GPs.\n", __func__);
1274         } else if (gp_exp && !cur_ops->exp_sync) {
1275                 pr_alert("%s: gp_exp without primitives.\n", __func__);
1276         }
1277         if (gp_normal1 && cur_ops->deferred_free) {
1278                 synctype[nsynctypes++] = RTWS_DEF_FREE;
1279                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
1280         } else if (gp_normal && !cur_ops->deferred_free) {
1281                 pr_alert("%s: gp_normal without primitives.\n", __func__);
1282         }
1283         if (gp_poll1 && cur_ops->get_comp_state && cur_ops->same_gp_state &&
1284             cur_ops->start_gp_poll && cur_ops->poll_gp_state) {
1285                 synctype[nsynctypes++] = RTWS_POLL_GET;
1286                 pr_info("%s: Testing polling GPs.\n", __func__);
1287         } else if (gp_poll && (!cur_ops->start_gp_poll || !cur_ops->poll_gp_state)) {
1288                 pr_alert("%s: gp_poll without primitives.\n", __func__);
1289         }
1290         if (gp_poll_full1 && cur_ops->get_comp_state_full && cur_ops->same_gp_state_full
1291             && cur_ops->start_gp_poll_full && cur_ops->poll_gp_state_full) {
1292                 synctype[nsynctypes++] = RTWS_POLL_GET_FULL;
1293                 pr_info("%s: Testing polling full-state GPs.\n", __func__);
1294         } else if (gp_poll_full && (!cur_ops->start_gp_poll_full || !cur_ops->poll_gp_state_full)) {
1295                 pr_alert("%s: gp_poll_full without primitives.\n", __func__);
1296         }
1297         if (gp_poll_exp1 && cur_ops->start_gp_poll_exp && cur_ops->poll_gp_state_exp) {
1298                 synctype[nsynctypes++] = RTWS_POLL_GET_EXP;
1299                 pr_info("%s: Testing polling expedited GPs.\n", __func__);
1300         } else if (gp_poll_exp && (!cur_ops->start_gp_poll_exp || !cur_ops->poll_gp_state_exp)) {
1301                 pr_alert("%s: gp_poll_exp without primitives.\n", __func__);
1302         }
1303         if (gp_poll_exp_full1 && cur_ops->start_gp_poll_exp_full && cur_ops->poll_gp_state_full) {
1304                 synctype[nsynctypes++] = RTWS_POLL_GET_EXP_FULL;
1305                 pr_info("%s: Testing polling full-state expedited GPs.\n", __func__);
1306         } else if (gp_poll_exp_full &&
1307                    (!cur_ops->start_gp_poll_exp_full || !cur_ops->poll_gp_state_full)) {
1308                 pr_alert("%s: gp_poll_exp_full without primitives.\n", __func__);
1309         }
1310         if (gp_sync1 && cur_ops->sync) {
1311                 synctype[nsynctypes++] = RTWS_SYNC;
1312                 pr_info("%s: Testing normal GPs.\n", __func__);
1313         } else if (gp_sync && !cur_ops->sync) {
1314                 pr_alert("%s: gp_sync without primitives.\n", __func__);
1315         }
1316 }
1317
1318 /*
1319  * Do the specified rcu_torture_writer() synchronous grace period,
1320  * while also testing out the polled APIs.  Note well that the single-CPU
1321  * grace-period optimizations must be accounted for.
1322  */
1323 static void do_rtws_sync(struct torture_random_state *trsp, void (*sync)(void))
1324 {
1325         unsigned long cookie;
1326         struct rcu_gp_oldstate cookie_full;
1327         bool dopoll;
1328         bool dopoll_full;
1329         unsigned long r = torture_random(trsp);
1330
1331         dopoll = cur_ops->get_gp_state && cur_ops->poll_gp_state && !(r & 0x300);
1332         dopoll_full = cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full && !(r & 0xc00);
1333         if (dopoll || dopoll_full)
1334                 cpus_read_lock();
1335         if (dopoll)
1336                 cookie = cur_ops->get_gp_state();
1337         if (dopoll_full)
1338                 cur_ops->get_gp_state_full(&cookie_full);
1339         if (cur_ops->poll_need_2gp && cur_ops->poll_need_2gp(dopoll, dopoll_full))
1340                 sync();
1341         sync();
1342         WARN_ONCE(dopoll && !cur_ops->poll_gp_state(cookie),
1343                   "%s: Cookie check 3 failed %pS() online %*pbl.",
1344                   __func__, sync, cpumask_pr_args(cpu_online_mask));
1345         WARN_ONCE(dopoll_full && !cur_ops->poll_gp_state_full(&cookie_full),
1346                   "%s: Cookie check 4 failed %pS() online %*pbl",
1347                   __func__, sync, cpumask_pr_args(cpu_online_mask));
1348         if (dopoll || dopoll_full)
1349                 cpus_read_unlock();
1350 }
1351
1352 /*
1353  * RCU torture writer kthread.  Repeatedly substitutes a new structure
1354  * for that pointed to by rcu_torture_current, freeing the old structure
1355  * after a series of grace periods (the "pipeline").
1356  */
1357 static int
1358 rcu_torture_writer(void *arg)
1359 {
1360         bool boot_ended;
1361         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
1362         unsigned long cookie;
1363         struct rcu_gp_oldstate cookie_full;
1364         int expediting = 0;
1365         unsigned long gp_snap;
1366         unsigned long gp_snap1;
1367         struct rcu_gp_oldstate gp_snap_full;
1368         struct rcu_gp_oldstate gp_snap1_full;
1369         int i;
1370         int idx;
1371         int oldnice = task_nice(current);
1372         struct rcu_gp_oldstate rgo[NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE];
1373         struct rcu_torture *rp;
1374         struct rcu_torture *old_rp;
1375         static DEFINE_TORTURE_RANDOM(rand);
1376         unsigned long stallsdone = jiffies;
1377         bool stutter_waited;
1378         unsigned long ulo[NUM_ACTIVE_RCU_POLL_OLDSTATE];
1379
1380         // If a new stall test is added, this must be adjusted.
1381         if (stall_cpu_holdoff + stall_gp_kthread + stall_cpu)
1382                 stallsdone += (stall_cpu_holdoff + stall_gp_kthread + stall_cpu + 60) * HZ;
1383         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
1384         if (!can_expedite)
1385                 pr_alert("%s" TORTURE_FLAG
1386                          " GP expediting controlled from boot/sysfs for %s.\n",
1387                          torture_type, cur_ops->name);
1388         if (WARN_ONCE(nsynctypes == 0,
1389                       "%s: No update-side primitives.\n", __func__)) {
1390                 /*
1391                  * No updates primitives, so don't try updating.
1392                  * The resulting test won't be testing much, hence the
1393                  * above WARN_ONCE().
1394                  */
1395                 rcu_torture_writer_state = RTWS_STOPPING;
1396                 torture_kthread_stopping("rcu_torture_writer");
1397                 return 0;
1398         }
1399
1400         do {
1401                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
1402                 torture_hrtimeout_us(500, 1000, &rand);
1403                 rp = rcu_torture_alloc();
1404                 if (rp == NULL)
1405                         continue;
1406                 rp->rtort_pipe_count = 0;
1407                 ASSERT_EXCLUSIVE_WRITER(rp->rtort_pipe_count);
1408                 rcu_torture_writer_state = RTWS_DELAY;
1409                 udelay(torture_random(&rand) & 0x3ff);
1410                 rcu_torture_writer_state = RTWS_REPLACE;
1411                 old_rp = rcu_dereference_check(rcu_torture_current,
1412                                                current == writer_task);
1413                 rp->rtort_mbtest = 1;
1414                 rcu_assign_pointer(rcu_torture_current, rp);
1415                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1416                 if (old_rp) {
1417                         i = old_rp->rtort_pipe_count;
1418                         if (i > RCU_TORTURE_PIPE_LEN)
1419                                 i = RCU_TORTURE_PIPE_LEN;
1420                         atomic_inc(&rcu_torture_wcount[i]);
1421                         WRITE_ONCE(old_rp->rtort_pipe_count,
1422                                    old_rp->rtort_pipe_count + 1);
1423                         ASSERT_EXCLUSIVE_WRITER(old_rp->rtort_pipe_count);
1424
1425                         // Make sure readers block polled grace periods.
1426                         if (cur_ops->get_gp_state && cur_ops->poll_gp_state) {
1427                                 idx = cur_ops->readlock();
1428                                 cookie = cur_ops->get_gp_state();
1429                                 WARN_ONCE(cur_ops->poll_gp_state(cookie),
1430                                           "%s: Cookie check 1 failed %s(%d) %lu->%lu\n",
1431                                           __func__,
1432                                           rcu_torture_writer_state_getname(),
1433                                           rcu_torture_writer_state,
1434                                           cookie, cur_ops->get_gp_state());
1435                                 if (cur_ops->get_gp_completed) {
1436                                         cookie = cur_ops->get_gp_completed();
1437                                         WARN_ON_ONCE(!cur_ops->poll_gp_state(cookie));
1438                                 }
1439                                 cur_ops->readunlock(idx);
1440                         }
1441                         if (cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full) {
1442                                 idx = cur_ops->readlock();
1443                                 cur_ops->get_gp_state_full(&cookie_full);
1444                                 WARN_ONCE(cur_ops->poll_gp_state_full(&cookie_full),
1445                                           "%s: Cookie check 5 failed %s(%d) online %*pbl\n",
1446                                           __func__,
1447                                           rcu_torture_writer_state_getname(),
1448                                           rcu_torture_writer_state,
1449                                           cpumask_pr_args(cpu_online_mask));
1450                                 if (cur_ops->get_gp_completed_full) {
1451                                         cur_ops->get_gp_completed_full(&cookie_full);
1452                                         WARN_ON_ONCE(!cur_ops->poll_gp_state_full(&cookie_full));
1453                                 }
1454                                 cur_ops->readunlock(idx);
1455                         }
1456                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1457                         case RTWS_DEF_FREE:
1458                                 rcu_torture_writer_state = RTWS_DEF_FREE;
1459                                 cur_ops->deferred_free(old_rp);
1460                                 break;
1461                         case RTWS_EXP_SYNC:
1462                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1463                                 do_rtws_sync(&rand, cur_ops->exp_sync);
1464                                 rcu_torture_pipe_update(old_rp);
1465                                 break;
1466                         case RTWS_COND_GET:
1467                                 rcu_torture_writer_state = RTWS_COND_GET;
1468                                 gp_snap = cur_ops->get_gp_state();
1469                                 torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1470                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1471                                 cur_ops->cond_sync(gp_snap);
1472                                 rcu_torture_pipe_update(old_rp);
1473                                 break;
1474                         case RTWS_COND_GET_EXP:
1475                                 rcu_torture_writer_state = RTWS_COND_GET_EXP;
1476                                 gp_snap = cur_ops->get_gp_state_exp();
1477                                 torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1478                                 rcu_torture_writer_state = RTWS_COND_SYNC_EXP;
1479                                 cur_ops->cond_sync_exp(gp_snap);
1480                                 rcu_torture_pipe_update(old_rp);
1481                                 break;
1482                         case RTWS_COND_GET_FULL:
1483                                 rcu_torture_writer_state = RTWS_COND_GET_FULL;
1484                                 cur_ops->get_gp_state_full(&gp_snap_full);
1485                                 torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1486                                 rcu_torture_writer_state = RTWS_COND_SYNC_FULL;
1487                                 cur_ops->cond_sync_full(&gp_snap_full);
1488                                 rcu_torture_pipe_update(old_rp);
1489                                 break;
1490                         case RTWS_COND_GET_EXP_FULL:
1491                                 rcu_torture_writer_state = RTWS_COND_GET_EXP_FULL;
1492                                 cur_ops->get_gp_state_full(&gp_snap_full);
1493                                 torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1494                                 rcu_torture_writer_state = RTWS_COND_SYNC_EXP_FULL;
1495                                 cur_ops->cond_sync_exp_full(&gp_snap_full);
1496                                 rcu_torture_pipe_update(old_rp);
1497                                 break;
1498                         case RTWS_POLL_GET:
1499                                 rcu_torture_writer_state = RTWS_POLL_GET;
1500                                 for (i = 0; i < ARRAY_SIZE(ulo); i++)
1501                                         ulo[i] = cur_ops->get_comp_state();
1502                                 gp_snap = cur_ops->start_gp_poll();
1503                                 rcu_torture_writer_state = RTWS_POLL_WAIT;
1504                                 while (!cur_ops->poll_gp_state(gp_snap)) {
1505                                         gp_snap1 = cur_ops->get_gp_state();
1506                                         for (i = 0; i < ARRAY_SIZE(ulo); i++)
1507                                                 if (cur_ops->poll_gp_state(ulo[i]) ||
1508                                                     cur_ops->same_gp_state(ulo[i], gp_snap1)) {
1509                                                         ulo[i] = gp_snap1;
1510                                                         break;
1511                                                 }
1512                                         WARN_ON_ONCE(i >= ARRAY_SIZE(ulo));
1513                                         torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1514                                                                   &rand);
1515                                 }
1516                                 rcu_torture_pipe_update(old_rp);
1517                                 break;
1518                         case RTWS_POLL_GET_FULL:
1519                                 rcu_torture_writer_state = RTWS_POLL_GET_FULL;
1520                                 for (i = 0; i < ARRAY_SIZE(rgo); i++)
1521                                         cur_ops->get_comp_state_full(&rgo[i]);
1522                                 cur_ops->start_gp_poll_full(&gp_snap_full);
1523                                 rcu_torture_writer_state = RTWS_POLL_WAIT_FULL;
1524                                 while (!cur_ops->poll_gp_state_full(&gp_snap_full)) {
1525                                         cur_ops->get_gp_state_full(&gp_snap1_full);
1526                                         for (i = 0; i < ARRAY_SIZE(rgo); i++)
1527                                                 if (cur_ops->poll_gp_state_full(&rgo[i]) ||
1528                                                     cur_ops->same_gp_state_full(&rgo[i],
1529                                                                                 &gp_snap1_full)) {
1530                                                         rgo[i] = gp_snap1_full;
1531                                                         break;
1532                                                 }
1533                                         WARN_ON_ONCE(i >= ARRAY_SIZE(rgo));
1534                                         torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1535                                                                   &rand);
1536                                 }
1537                                 rcu_torture_pipe_update(old_rp);
1538                                 break;
1539                         case RTWS_POLL_GET_EXP:
1540                                 rcu_torture_writer_state = RTWS_POLL_GET_EXP;
1541                                 gp_snap = cur_ops->start_gp_poll_exp();
1542                                 rcu_torture_writer_state = RTWS_POLL_WAIT_EXP;
1543                                 while (!cur_ops->poll_gp_state_exp(gp_snap))
1544                                         torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1545                                                                   &rand);
1546                                 rcu_torture_pipe_update(old_rp);
1547                                 break;
1548                         case RTWS_POLL_GET_EXP_FULL:
1549                                 rcu_torture_writer_state = RTWS_POLL_GET_EXP_FULL;
1550                                 cur_ops->start_gp_poll_exp_full(&gp_snap_full);
1551                                 rcu_torture_writer_state = RTWS_POLL_WAIT_EXP_FULL;
1552                                 while (!cur_ops->poll_gp_state_full(&gp_snap_full))
1553                                         torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1554                                                                   &rand);
1555                                 rcu_torture_pipe_update(old_rp);
1556                                 break;
1557                         case RTWS_SYNC:
1558                                 rcu_torture_writer_state = RTWS_SYNC;
1559                                 do_rtws_sync(&rand, cur_ops->sync);
1560                                 rcu_torture_pipe_update(old_rp);
1561                                 break;
1562                         default:
1563                                 WARN_ON_ONCE(1);
1564                                 break;
1565                         }
1566                 }
1567                 WRITE_ONCE(rcu_torture_current_version,
1568                            rcu_torture_current_version + 1);
1569                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1570                 if (can_expedite &&
1571                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1572                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1573                         if (expediting >= 0)
1574                                 rcu_expedite_gp();
1575                         else
1576                                 rcu_unexpedite_gp();
1577                         if (++expediting > 3)
1578                                 expediting = -expediting;
1579                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1580                         can_expedite = !rcu_gp_is_expedited() &&
1581                                        !rcu_gp_is_normal();
1582                 }
1583                 rcu_torture_writer_state = RTWS_STUTTER;
1584                 boot_ended = rcu_inkernel_boot_has_ended();
1585                 stutter_waited = stutter_wait("rcu_torture_writer");
1586                 if (stutter_waited &&
1587                     !atomic_read(&rcu_fwd_cb_nodelay) &&
1588                     !cur_ops->slow_gps &&
1589                     !torture_must_stop() &&
1590                     boot_ended &&
1591                     time_after(jiffies, stallsdone))
1592                         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1593                                 if (list_empty(&rcu_tortures[i].rtort_free) &&
1594                                     rcu_access_pointer(rcu_torture_current) != &rcu_tortures[i]) {
1595                                         tracing_off();
1596                                         if (cur_ops->gp_kthread_dbg)
1597                                                 cur_ops->gp_kthread_dbg();
1598                                         WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
1599                                         rcu_ftrace_dump(DUMP_ALL);
1600                                 }
1601                 if (stutter_waited)
1602                         sched_set_normal(current, oldnice);
1603         } while (!torture_must_stop());
1604         rcu_torture_current = NULL;  // Let stats task know that we are done.
1605         /* Reset expediting back to unexpedited. */
1606         if (expediting > 0)
1607                 expediting = -expediting;
1608         while (can_expedite && expediting++ < 0)
1609                 rcu_unexpedite_gp();
1610         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1611         if (!can_expedite)
1612                 pr_alert("%s" TORTURE_FLAG
1613                          " Dynamic grace-period expediting was disabled.\n",
1614                          torture_type);
1615         rcu_torture_writer_state = RTWS_STOPPING;
1616         torture_kthread_stopping("rcu_torture_writer");
1617         return 0;
1618 }
1619
1620 /*
1621  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1622  * delay between calls.
1623  */
1624 static int
1625 rcu_torture_fakewriter(void *arg)
1626 {
1627         unsigned long gp_snap;
1628         struct rcu_gp_oldstate gp_snap_full;
1629         DEFINE_TORTURE_RANDOM(rand);
1630
1631         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1632         set_user_nice(current, MAX_NICE);
1633
1634         if (WARN_ONCE(nsynctypes == 0,
1635                       "%s: No update-side primitives.\n", __func__)) {
1636                 /*
1637                  * No updates primitives, so don't try updating.
1638                  * The resulting test won't be testing much, hence the
1639                  * above WARN_ONCE().
1640                  */
1641                 torture_kthread_stopping("rcu_torture_fakewriter");
1642                 return 0;
1643         }
1644
1645         do {
1646                 torture_hrtimeout_jiffies(torture_random(&rand) % 10, &rand);
1647                 if (cur_ops->cb_barrier != NULL &&
1648                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1649                         cur_ops->cb_barrier();
1650                 } else {
1651                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1652                         case RTWS_DEF_FREE:
1653                                 break;
1654                         case RTWS_EXP_SYNC:
1655                                 cur_ops->exp_sync();
1656                                 break;
1657                         case RTWS_COND_GET:
1658                                 gp_snap = cur_ops->get_gp_state();
1659                                 torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1660                                 cur_ops->cond_sync(gp_snap);
1661                                 break;
1662                         case RTWS_COND_GET_EXP:
1663                                 gp_snap = cur_ops->get_gp_state_exp();
1664                                 torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1665                                 cur_ops->cond_sync_exp(gp_snap);
1666                                 break;
1667                         case RTWS_COND_GET_FULL:
1668                                 cur_ops->get_gp_state_full(&gp_snap_full);
1669                                 torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1670                                 cur_ops->cond_sync_full(&gp_snap_full);
1671                                 break;
1672                         case RTWS_COND_GET_EXP_FULL:
1673                                 cur_ops->get_gp_state_full(&gp_snap_full);
1674                                 torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1675                                 cur_ops->cond_sync_exp_full(&gp_snap_full);
1676                                 break;
1677                         case RTWS_POLL_GET:
1678                                 gp_snap = cur_ops->start_gp_poll();
1679                                 while (!cur_ops->poll_gp_state(gp_snap)) {
1680                                         torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1681                                                                   &rand);
1682                                 }
1683                                 break;
1684                         case RTWS_POLL_GET_FULL:
1685                                 cur_ops->start_gp_poll_full(&gp_snap_full);
1686                                 while (!cur_ops->poll_gp_state_full(&gp_snap_full)) {
1687                                         torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1688                                                                   &rand);
1689                                 }
1690                                 break;
1691                         case RTWS_POLL_GET_EXP:
1692                                 gp_snap = cur_ops->start_gp_poll_exp();
1693                                 while (!cur_ops->poll_gp_state_exp(gp_snap)) {
1694                                         torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1695                                                                   &rand);
1696                                 }
1697                                 break;
1698                         case RTWS_POLL_GET_EXP_FULL:
1699                                 cur_ops->start_gp_poll_exp_full(&gp_snap_full);
1700                                 while (!cur_ops->poll_gp_state_full(&gp_snap_full)) {
1701                                         torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1702                                                                   &rand);
1703                                 }
1704                                 break;
1705                         case RTWS_SYNC:
1706                                 cur_ops->sync();
1707                                 break;
1708                         default:
1709                                 WARN_ON_ONCE(1);
1710                                 break;
1711                         }
1712                 }
1713                 stutter_wait("rcu_torture_fakewriter");
1714         } while (!torture_must_stop());
1715
1716         torture_kthread_stopping("rcu_torture_fakewriter");
1717         return 0;
1718 }
1719
1720 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1721 {
1722         kfree(rhp);
1723 }
1724
1725 // Set up and carry out testing of RCU's global memory ordering
1726 static void rcu_torture_reader_do_mbchk(long myid, struct rcu_torture *rtp,
1727                                         struct torture_random_state *trsp)
1728 {
1729         unsigned long loops;
1730         int noc = torture_num_online_cpus();
1731         int rdrchked;
1732         int rdrchker;
1733         struct rcu_torture_reader_check *rtrcp; // Me.
1734         struct rcu_torture_reader_check *rtrcp_assigner; // Assigned us to do checking.
1735         struct rcu_torture_reader_check *rtrcp_chked; // Reader being checked.
1736         struct rcu_torture_reader_check *rtrcp_chker; // Reader doing checking when not me.
1737
1738         if (myid < 0)
1739                 return; // Don't try this from timer handlers.
1740
1741         // Increment my counter.
1742         rtrcp = &rcu_torture_reader_mbchk[myid];
1743         WRITE_ONCE(rtrcp->rtc_myloops, rtrcp->rtc_myloops + 1);
1744
1745         // Attempt to assign someone else some checking work.
1746         rdrchked = torture_random(trsp) % nrealreaders;
1747         rtrcp_chked = &rcu_torture_reader_mbchk[rdrchked];
1748         rdrchker = torture_random(trsp) % nrealreaders;
1749         rtrcp_chker = &rcu_torture_reader_mbchk[rdrchker];
1750         if (rdrchked != myid && rdrchked != rdrchker && noc >= rdrchked && noc >= rdrchker &&
1751             smp_load_acquire(&rtrcp->rtc_chkrdr) < 0 && // Pairs with smp_store_release below.
1752             !READ_ONCE(rtp->rtort_chkp) &&
1753             !smp_load_acquire(&rtrcp_chker->rtc_assigner)) { // Pairs with smp_store_release below.
1754                 rtrcp->rtc_chkloops = READ_ONCE(rtrcp_chked->rtc_myloops);
1755                 WARN_ON_ONCE(rtrcp->rtc_chkrdr >= 0);
1756                 rtrcp->rtc_chkrdr = rdrchked;
1757                 WARN_ON_ONCE(rtrcp->rtc_ready); // This gets set after the grace period ends.
1758                 if (cmpxchg_relaxed(&rtrcp_chker->rtc_assigner, NULL, rtrcp) ||
1759                     cmpxchg_relaxed(&rtp->rtort_chkp, NULL, rtrcp))
1760                         (void)cmpxchg_relaxed(&rtrcp_chker->rtc_assigner, rtrcp, NULL); // Back out.
1761         }
1762
1763         // If assigned some completed work, do it!
1764         rtrcp_assigner = READ_ONCE(rtrcp->rtc_assigner);
1765         if (!rtrcp_assigner || !smp_load_acquire(&rtrcp_assigner->rtc_ready))
1766                 return; // No work or work not yet ready.
1767         rdrchked = rtrcp_assigner->rtc_chkrdr;
1768         if (WARN_ON_ONCE(rdrchked < 0))
1769                 return;
1770         rtrcp_chked = &rcu_torture_reader_mbchk[rdrchked];
1771         loops = READ_ONCE(rtrcp_chked->rtc_myloops);
1772         atomic_inc(&n_rcu_torture_mbchk_tries);
1773         if (ULONG_CMP_LT(loops, rtrcp_assigner->rtc_chkloops))
1774                 atomic_inc(&n_rcu_torture_mbchk_fail);
1775         rtrcp_assigner->rtc_chkloops = loops + ULONG_MAX / 2;
1776         rtrcp_assigner->rtc_ready = 0;
1777         smp_store_release(&rtrcp->rtc_assigner, NULL); // Someone else can assign us work.
1778         smp_store_release(&rtrcp_assigner->rtc_chkrdr, -1); // Assigner can again assign.
1779 }
1780
1781 /*
1782  * Do one extension of an RCU read-side critical section using the
1783  * current reader state in readstate (set to zero for initial entry
1784  * to extended critical section), set the new state as specified by
1785  * newstate (set to zero for final exit from extended critical section),
1786  * and random-number-generator state in trsp.  If this is neither the
1787  * beginning or end of the critical section and if there was actually a
1788  * change, do a ->read_delay().
1789  */
1790 static void rcutorture_one_extend(int *readstate, int newstate,
1791                                   struct torture_random_state *trsp,
1792                                   struct rt_read_seg *rtrsp)
1793 {
1794         unsigned long flags;
1795         int idxnew1 = -1;
1796         int idxnew2 = -1;
1797         int idxold1 = *readstate;
1798         int idxold2 = idxold1;
1799         int statesnew = ~*readstate & newstate;
1800         int statesold = *readstate & ~newstate;
1801
1802         WARN_ON_ONCE(idxold2 < 0);
1803         WARN_ON_ONCE((idxold2 >> RCUTORTURE_RDR_SHIFT_2) > 1);
1804         rtrsp->rt_readstate = newstate;
1805
1806         /* First, put new protection in place to avoid critical-section gap. */
1807         if (statesnew & RCUTORTURE_RDR_BH)
1808                 local_bh_disable();
1809         if (statesnew & RCUTORTURE_RDR_RBH)
1810                 rcu_read_lock_bh();
1811         if (statesnew & RCUTORTURE_RDR_IRQ)
1812                 local_irq_disable();
1813         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1814                 preempt_disable();
1815         if (statesnew & RCUTORTURE_RDR_SCHED)
1816                 rcu_read_lock_sched();
1817         if (statesnew & RCUTORTURE_RDR_RCU_1)
1818                 idxnew1 = (cur_ops->readlock() & 0x1) << RCUTORTURE_RDR_SHIFT_1;
1819         if (statesnew & RCUTORTURE_RDR_RCU_2)
1820                 idxnew2 = (cur_ops->readlock() & 0x1) << RCUTORTURE_RDR_SHIFT_2;
1821
1822         /*
1823          * Next, remove old protection, in decreasing order of strength
1824          * to avoid unlock paths that aren't safe in the stronger
1825          * context. Namely: BH can not be enabled with disabled interrupts.
1826          * Additionally PREEMPT_RT requires that BH is enabled in preemptible
1827          * context.
1828          */
1829         if (statesold & RCUTORTURE_RDR_IRQ)
1830                 local_irq_enable();
1831         if (statesold & RCUTORTURE_RDR_PREEMPT)
1832                 preempt_enable();
1833         if (statesold & RCUTORTURE_RDR_SCHED)
1834                 rcu_read_unlock_sched();
1835         if (statesold & RCUTORTURE_RDR_BH)
1836                 local_bh_enable();
1837         if (statesold & RCUTORTURE_RDR_RBH)
1838                 rcu_read_unlock_bh();
1839         if (statesold & RCUTORTURE_RDR_RCU_2) {
1840                 cur_ops->readunlock((idxold2 >> RCUTORTURE_RDR_SHIFT_2) & 0x1);
1841                 WARN_ON_ONCE(idxnew2 != -1);
1842                 idxold2 = 0;
1843         }
1844         if (statesold & RCUTORTURE_RDR_RCU_1) {
1845                 bool lockit;
1846
1847                 lockit = !cur_ops->no_pi_lock && !statesnew && !(torture_random(trsp) & 0xffff);
1848                 if (lockit)
1849                         raw_spin_lock_irqsave(&current->pi_lock, flags);
1850                 cur_ops->readunlock((idxold1 >> RCUTORTURE_RDR_SHIFT_1) & 0x1);
1851                 WARN_ON_ONCE(idxnew1 != -1);
1852                 idxold1 = 0;
1853                 if (lockit)
1854                         raw_spin_unlock_irqrestore(&current->pi_lock, flags);
1855         }
1856
1857         /* Delay if neither beginning nor end and there was a change. */
1858         if ((statesnew || statesold) && *readstate && newstate)
1859                 cur_ops->read_delay(trsp, rtrsp);
1860
1861         /* Update the reader state. */
1862         if (idxnew1 == -1)
1863                 idxnew1 = idxold1 & RCUTORTURE_RDR_MASK_1;
1864         WARN_ON_ONCE(idxnew1 < 0);
1865         if (WARN_ON_ONCE((idxnew1 >> RCUTORTURE_RDR_SHIFT_1) > 1))
1866                 pr_info("Unexpected idxnew1 value of %#x\n", idxnew1);
1867         if (idxnew2 == -1)
1868                 idxnew2 = idxold2 & RCUTORTURE_RDR_MASK_2;
1869         WARN_ON_ONCE(idxnew2 < 0);
1870         WARN_ON_ONCE((idxnew2 >> RCUTORTURE_RDR_SHIFT_2) > 1);
1871         *readstate = idxnew1 | idxnew2 | newstate;
1872         WARN_ON_ONCE(*readstate < 0);
1873         if (WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT_2) > 1))
1874                 pr_info("Unexpected idxnew2 value of %#x\n", idxnew2);
1875 }
1876
1877 /* Return the biggest extendables mask given current RCU and boot parameters. */
1878 static int rcutorture_extend_mask_max(void)
1879 {
1880         int mask;
1881
1882         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1883         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1884         mask = mask | RCUTORTURE_RDR_RCU_1 | RCUTORTURE_RDR_RCU_2;
1885         return mask;
1886 }
1887
1888 /* Return a random protection state mask, but with at least one bit set. */
1889 static int
1890 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1891 {
1892         int mask = rcutorture_extend_mask_max();
1893         unsigned long randmask1 = torture_random(trsp);
1894         unsigned long randmask2 = randmask1 >> 3;
1895         unsigned long preempts = RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED;
1896         unsigned long preempts_irq = preempts | RCUTORTURE_RDR_IRQ;
1897         unsigned long bhs = RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1898
1899         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT_1);
1900         /* Mostly only one bit (need preemption!), sometimes lots of bits. */
1901         if (!(randmask1 & 0x7))
1902                 mask = mask & randmask2;
1903         else
1904                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1905
1906         // Can't have nested RCU reader without outer RCU reader.
1907         if (!(mask & RCUTORTURE_RDR_RCU_1) && (mask & RCUTORTURE_RDR_RCU_2)) {
1908                 if (oldmask & RCUTORTURE_RDR_RCU_1)
1909                         mask &= ~RCUTORTURE_RDR_RCU_2;
1910                 else
1911                         mask |= RCUTORTURE_RDR_RCU_1;
1912         }
1913
1914         /*
1915          * Can't enable bh w/irq disabled.
1916          */
1917         if (mask & RCUTORTURE_RDR_IRQ)
1918                 mask |= oldmask & bhs;
1919
1920         /*
1921          * Ideally these sequences would be detected in debug builds
1922          * (regardless of RT), but until then don't stop testing
1923          * them on non-RT.
1924          */
1925         if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1926                 /* Can't modify BH in atomic context */
1927                 if (oldmask & preempts_irq)
1928                         mask &= ~bhs;
1929                 if ((oldmask | mask) & preempts_irq)
1930                         mask |= oldmask & bhs;
1931         }
1932
1933         return mask ?: RCUTORTURE_RDR_RCU_1;
1934 }
1935
1936 /*
1937  * Do a randomly selected number of extensions of an existing RCU read-side
1938  * critical section.
1939  */
1940 static struct rt_read_seg *
1941 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1942                        struct rt_read_seg *rtrsp)
1943 {
1944         int i;
1945         int j;
1946         int mask = rcutorture_extend_mask_max();
1947
1948         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1949         if (!((mask - 1) & mask))
1950                 return rtrsp;  /* Current RCU reader not extendable. */
1951         /* Bias towards larger numbers of loops. */
1952         i = torture_random(trsp);
1953         i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1954         for (j = 0; j < i; j++) {
1955                 mask = rcutorture_extend_mask(*readstate, trsp);
1956                 rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1957         }
1958         return &rtrsp[j];
1959 }
1960
1961 /*
1962  * Do one read-side critical section, returning false if there was
1963  * no data to read.  Can be invoked both from process context and
1964  * from a timer handler.
1965  */
1966 static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
1967 {
1968         bool checkpolling = !(torture_random(trsp) & 0xfff);
1969         unsigned long cookie;
1970         struct rcu_gp_oldstate cookie_full;
1971         int i;
1972         unsigned long started;
1973         unsigned long completed;
1974         int newstate;
1975         struct rcu_torture *p;
1976         int pipe_count;
1977         int readstate = 0;
1978         struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1979         struct rt_read_seg *rtrsp = &rtseg[0];
1980         struct rt_read_seg *rtrsp1;
1981         unsigned long long ts;
1982
1983         WARN_ON_ONCE(!rcu_is_watching());
1984         newstate = rcutorture_extend_mask(readstate, trsp);
1985         rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1986         if (checkpolling) {
1987                 if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
1988                         cookie = cur_ops->get_gp_state();
1989                 if (cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full)
1990                         cur_ops->get_gp_state_full(&cookie_full);
1991         }
1992         started = cur_ops->get_gp_seq();
1993         ts = rcu_trace_clock_local();
1994         p = rcu_dereference_check(rcu_torture_current,
1995                                   !cur_ops->readlock_held || cur_ops->readlock_held());
1996         if (p == NULL) {
1997                 /* Wait for rcu_torture_writer to get underway */
1998                 rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1999                 return false;
2000         }
2001         if (p->rtort_mbtest == 0)
2002                 atomic_inc(&n_rcu_torture_mberror);
2003         rcu_torture_reader_do_mbchk(myid, p, trsp);
2004         rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
2005         preempt_disable();
2006         pipe_count = READ_ONCE(p->rtort_pipe_count);
2007         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
2008                 // Should not happen in a correct RCU implementation,
2009                 // happens quite often for torture_type=busted.
2010                 pipe_count = RCU_TORTURE_PIPE_LEN;
2011         }
2012         completed = cur_ops->get_gp_seq();
2013         if (pipe_count > 1) {
2014                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
2015                                           ts, started, completed);
2016                 rcu_ftrace_dump(DUMP_ALL);
2017         }
2018         __this_cpu_inc(rcu_torture_count[pipe_count]);
2019         completed = rcutorture_seq_diff(completed, started);
2020         if (completed > RCU_TORTURE_PIPE_LEN) {
2021                 /* Should not happen, but... */
2022                 completed = RCU_TORTURE_PIPE_LEN;
2023         }
2024         __this_cpu_inc(rcu_torture_batch[completed]);
2025         preempt_enable();
2026         if (checkpolling) {
2027                 if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
2028                         WARN_ONCE(cur_ops->poll_gp_state(cookie),
2029                                   "%s: Cookie check 2 failed %s(%d) %lu->%lu\n",
2030                                   __func__,
2031                                   rcu_torture_writer_state_getname(),
2032                                   rcu_torture_writer_state,
2033                                   cookie, cur_ops->get_gp_state());
2034                 if (cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full)
2035                         WARN_ONCE(cur_ops->poll_gp_state_full(&cookie_full),
2036                                   "%s: Cookie check 6 failed %s(%d) online %*pbl\n",
2037                                   __func__,
2038                                   rcu_torture_writer_state_getname(),
2039                                   rcu_torture_writer_state,
2040                                   cpumask_pr_args(cpu_online_mask));
2041         }
2042         rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
2043         WARN_ON_ONCE(readstate);
2044         // This next splat is expected behavior if leakpointer, especially
2045         // for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels.
2046         WARN_ON_ONCE(leakpointer && READ_ONCE(p->rtort_pipe_count) > 1);
2047
2048         /* If error or close call, record the sequence of reader protections. */
2049         if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
2050                 i = 0;
2051                 for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
2052                         err_segs[i++] = *rtrsp1;
2053                 rt_read_nsegs = i;
2054         }
2055
2056         return true;
2057 }
2058
2059 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
2060
2061 /*
2062  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
2063  * incrementing the corresponding element of the pipeline array.  The
2064  * counter in the element should never be greater than 1, otherwise, the
2065  * RCU implementation is broken.
2066  */
2067 static void rcu_torture_timer(struct timer_list *unused)
2068 {
2069         atomic_long_inc(&n_rcu_torture_timers);
2070         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand), -1);
2071
2072         /* Test call_rcu() invocation from interrupt handler. */
2073         if (cur_ops->call) {
2074                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
2075
2076                 if (rhp)
2077                         cur_ops->call(rhp, rcu_torture_timer_cb);
2078         }
2079 }
2080
2081 /*
2082  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
2083  * incrementing the corresponding element of the pipeline array.  The
2084  * counter in the element should never be greater than 1, otherwise, the
2085  * RCU implementation is broken.
2086  */
2087 static int
2088 rcu_torture_reader(void *arg)
2089 {
2090         unsigned long lastsleep = jiffies;
2091         long myid = (long)arg;
2092         int mynumonline = myid;
2093         DEFINE_TORTURE_RANDOM(rand);
2094         struct timer_list t;
2095
2096         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
2097         set_user_nice(current, MAX_NICE);
2098         if (irqreader && cur_ops->irq_capable)
2099                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
2100         tick_dep_set_task(current, TICK_DEP_BIT_RCU);
2101         do {
2102                 if (irqreader && cur_ops->irq_capable) {
2103                         if (!timer_pending(&t))
2104                                 mod_timer(&t, jiffies + 1);
2105                 }
2106                 if (!rcu_torture_one_read(&rand, myid) && !torture_must_stop())
2107                         schedule_timeout_interruptible(HZ);
2108                 if (time_after(jiffies, lastsleep) && !torture_must_stop()) {
2109                         torture_hrtimeout_us(500, 1000, &rand);
2110                         lastsleep = jiffies + 10;
2111                 }
2112                 while (torture_num_online_cpus() < mynumonline && !torture_must_stop())
2113                         schedule_timeout_interruptible(HZ / 5);
2114                 stutter_wait("rcu_torture_reader");
2115         } while (!torture_must_stop());
2116         if (irqreader && cur_ops->irq_capable) {
2117                 del_timer_sync(&t);
2118                 destroy_timer_on_stack(&t);
2119         }
2120         tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
2121         torture_kthread_stopping("rcu_torture_reader");
2122         return 0;
2123 }
2124
2125 /*
2126  * Randomly Toggle CPUs' callback-offload state.  This uses hrtimers to
2127  * increase race probabilities and fuzzes the interval between toggling.
2128  */
2129 static int rcu_nocb_toggle(void *arg)
2130 {
2131         int cpu;
2132         int maxcpu = -1;
2133         int oldnice = task_nice(current);
2134         long r;
2135         DEFINE_TORTURE_RANDOM(rand);
2136         ktime_t toggle_delay;
2137         unsigned long toggle_fuzz;
2138         ktime_t toggle_interval = ms_to_ktime(nocbs_toggle);
2139
2140         VERBOSE_TOROUT_STRING("rcu_nocb_toggle task started");
2141         while (!rcu_inkernel_boot_has_ended())
2142                 schedule_timeout_interruptible(HZ / 10);
2143         for_each_possible_cpu(cpu)
2144                 maxcpu = cpu;
2145         WARN_ON(maxcpu < 0);
2146         if (toggle_interval > ULONG_MAX)
2147                 toggle_fuzz = ULONG_MAX >> 3;
2148         else
2149                 toggle_fuzz = toggle_interval >> 3;
2150         if (toggle_fuzz <= 0)
2151                 toggle_fuzz = NSEC_PER_USEC;
2152         do {
2153                 r = torture_random(&rand);
2154                 cpu = (r >> 1) % (maxcpu + 1);
2155                 if (r & 0x1) {
2156                         rcu_nocb_cpu_offload(cpu);
2157                         atomic_long_inc(&n_nocb_offload);
2158                 } else {
2159                         rcu_nocb_cpu_deoffload(cpu);
2160                         atomic_long_inc(&n_nocb_deoffload);
2161                 }
2162                 toggle_delay = torture_random(&rand) % toggle_fuzz + toggle_interval;
2163                 set_current_state(TASK_INTERRUPTIBLE);
2164                 schedule_hrtimeout(&toggle_delay, HRTIMER_MODE_REL);
2165                 if (stutter_wait("rcu_nocb_toggle"))
2166                         sched_set_normal(current, oldnice);
2167         } while (!torture_must_stop());
2168         torture_kthread_stopping("rcu_nocb_toggle");
2169         return 0;
2170 }
2171
2172 /*
2173  * Print torture statistics.  Caller must ensure that there is only
2174  * one call to this function at a given time!!!  This is normally
2175  * accomplished by relying on the module system to only have one copy
2176  * of the module loaded, and then by giving the rcu_torture_stats
2177  * kthread full control (or the init/cleanup functions when rcu_torture_stats
2178  * thread is not running).
2179  */
2180 static void
2181 rcu_torture_stats_print(void)
2182 {
2183         int cpu;
2184         int i;
2185         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
2186         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
2187         struct rcu_torture *rtcp;
2188         static unsigned long rtcv_snap = ULONG_MAX;
2189         static bool splatted;
2190         struct task_struct *wtp;
2191
2192         for_each_possible_cpu(cpu) {
2193                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2194                         pipesummary[i] += READ_ONCE(per_cpu(rcu_torture_count, cpu)[i]);
2195                         batchsummary[i] += READ_ONCE(per_cpu(rcu_torture_batch, cpu)[i]);
2196                 }
2197         }
2198         for (i = RCU_TORTURE_PIPE_LEN; i >= 0; i--) {
2199                 if (pipesummary[i] != 0)
2200                         break;
2201         }
2202
2203         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
2204         rtcp = rcu_access_pointer(rcu_torture_current);
2205         pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
2206                 rtcp,
2207                 rtcp && !rcu_stall_is_suppressed_at_boot() ? "ver" : "VER",
2208                 rcu_torture_current_version,
2209                 list_empty(&rcu_torture_freelist),
2210                 atomic_read(&n_rcu_torture_alloc),
2211                 atomic_read(&n_rcu_torture_alloc_fail),
2212                 atomic_read(&n_rcu_torture_free));
2213         pr_cont("rtmbe: %d rtmbkf: %d/%d rtbe: %ld rtbke: %ld ",
2214                 atomic_read(&n_rcu_torture_mberror),
2215                 atomic_read(&n_rcu_torture_mbchk_fail), atomic_read(&n_rcu_torture_mbchk_tries),
2216                 n_rcu_torture_barrier_error,
2217                 n_rcu_torture_boost_ktrerror);
2218         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
2219                 n_rcu_torture_boost_failure,
2220                 n_rcu_torture_boosts,
2221                 atomic_long_read(&n_rcu_torture_timers));
2222         torture_onoff_stats();
2223         pr_cont("barrier: %ld/%ld:%ld ",
2224                 data_race(n_barrier_successes),
2225                 data_race(n_barrier_attempts),
2226                 data_race(n_rcu_torture_barrier_error));
2227         pr_cont("read-exits: %ld ", data_race(n_read_exits)); // Statistic.
2228         pr_cont("nocb-toggles: %ld:%ld\n",
2229                 atomic_long_read(&n_nocb_offload), atomic_long_read(&n_nocb_deoffload));
2230
2231         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
2232         if (atomic_read(&n_rcu_torture_mberror) ||
2233             atomic_read(&n_rcu_torture_mbchk_fail) ||
2234             n_rcu_torture_barrier_error || n_rcu_torture_boost_ktrerror ||
2235             n_rcu_torture_boost_failure || i > 1) {
2236                 pr_cont("%s", "!!! ");
2237                 atomic_inc(&n_rcu_torture_error);
2238                 WARN_ON_ONCE(atomic_read(&n_rcu_torture_mberror));
2239                 WARN_ON_ONCE(atomic_read(&n_rcu_torture_mbchk_fail));
2240                 WARN_ON_ONCE(n_rcu_torture_barrier_error);  // rcu_barrier()
2241                 WARN_ON_ONCE(n_rcu_torture_boost_ktrerror); // no boost kthread
2242                 WARN_ON_ONCE(n_rcu_torture_boost_failure); // boost failed (TIMER_SOFTIRQ RT prio?)
2243                 WARN_ON_ONCE(i > 1); // Too-short grace period
2244         }
2245         pr_cont("Reader Pipe: ");
2246         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2247                 pr_cont(" %ld", pipesummary[i]);
2248         pr_cont("\n");
2249
2250         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
2251         pr_cont("Reader Batch: ");
2252         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2253                 pr_cont(" %ld", batchsummary[i]);
2254         pr_cont("\n");
2255
2256         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
2257         pr_cont("Free-Block Circulation: ");
2258         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2259                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
2260         }
2261         pr_cont("\n");
2262
2263         if (cur_ops->stats)
2264                 cur_ops->stats();
2265         if (rtcv_snap == rcu_torture_current_version &&
2266             rcu_access_pointer(rcu_torture_current) &&
2267             !rcu_stall_is_suppressed()) {
2268                 int __maybe_unused flags = 0;
2269                 unsigned long __maybe_unused gp_seq = 0;
2270
2271                 if (cur_ops->get_gp_data)
2272                         cur_ops->get_gp_data(&flags, &gp_seq);
2273                 wtp = READ_ONCE(writer_task);
2274                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#x cpu %d\n",
2275                          rcu_torture_writer_state_getname(),
2276                          rcu_torture_writer_state, gp_seq, flags,
2277                          wtp == NULL ? ~0U : wtp->__state,
2278                          wtp == NULL ? -1 : (int)task_cpu(wtp));
2279                 if (!splatted && wtp) {
2280                         sched_show_task(wtp);
2281                         splatted = true;
2282                 }
2283                 if (cur_ops->gp_kthread_dbg)
2284                         cur_ops->gp_kthread_dbg();
2285                 rcu_ftrace_dump(DUMP_ALL);
2286         }
2287         rtcv_snap = rcu_torture_current_version;
2288 }
2289
2290 /*
2291  * Periodically prints torture statistics, if periodic statistics printing
2292  * was specified via the stat_interval module parameter.
2293  */
2294 static int
2295 rcu_torture_stats(void *arg)
2296 {
2297         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
2298         do {
2299                 schedule_timeout_interruptible(stat_interval * HZ);
2300                 rcu_torture_stats_print();
2301                 torture_shutdown_absorb("rcu_torture_stats");
2302         } while (!torture_must_stop());
2303         torture_kthread_stopping("rcu_torture_stats");
2304         return 0;
2305 }
2306
2307 /* Test mem_dump_obj() and friends.  */
2308 static void rcu_torture_mem_dump_obj(void)
2309 {
2310         struct rcu_head *rhp;
2311         struct kmem_cache *kcp;
2312         static int z;
2313
2314         kcp = kmem_cache_create("rcuscale", 136, 8, SLAB_STORE_USER, NULL);
2315         if (WARN_ON_ONCE(!kcp))
2316                 return;
2317         rhp = kmem_cache_alloc(kcp, GFP_KERNEL);
2318         if (WARN_ON_ONCE(!rhp)) {
2319                 kmem_cache_destroy(kcp);
2320                 return;
2321         }
2322         pr_alert("mem_dump_obj() slab test: rcu_torture_stats = %px, &rhp = %px, rhp = %px, &z = %px\n", stats_task, &rhp, rhp, &z);
2323         pr_alert("mem_dump_obj(ZERO_SIZE_PTR):");
2324         mem_dump_obj(ZERO_SIZE_PTR);
2325         pr_alert("mem_dump_obj(NULL):");
2326         mem_dump_obj(NULL);
2327         pr_alert("mem_dump_obj(%px):", &rhp);
2328         mem_dump_obj(&rhp);
2329         pr_alert("mem_dump_obj(%px):", rhp);
2330         mem_dump_obj(rhp);
2331         pr_alert("mem_dump_obj(%px):", &rhp->func);
2332         mem_dump_obj(&rhp->func);
2333         pr_alert("mem_dump_obj(%px):", &z);
2334         mem_dump_obj(&z);
2335         kmem_cache_free(kcp, rhp);
2336         kmem_cache_destroy(kcp);
2337         rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
2338         if (WARN_ON_ONCE(!rhp))
2339                 return;
2340         pr_alert("mem_dump_obj() kmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
2341         pr_alert("mem_dump_obj(kmalloc %px):", rhp);
2342         mem_dump_obj(rhp);
2343         pr_alert("mem_dump_obj(kmalloc %px):", &rhp->func);
2344         mem_dump_obj(&rhp->func);
2345         kfree(rhp);
2346         rhp = vmalloc(4096);
2347         if (WARN_ON_ONCE(!rhp))
2348                 return;
2349         pr_alert("mem_dump_obj() vmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
2350         pr_alert("mem_dump_obj(vmalloc %px):", rhp);
2351         mem_dump_obj(rhp);
2352         pr_alert("mem_dump_obj(vmalloc %px):", &rhp->func);
2353         mem_dump_obj(&rhp->func);
2354         vfree(rhp);
2355 }
2356
2357 static void
2358 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
2359 {
2360         pr_alert("%s" TORTURE_FLAG
2361                  "--- %s: nreaders=%d nfakewriters=%d "
2362                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
2363                  "shuffle_interval=%d stutter=%d irqreader=%d "
2364                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
2365                  "test_boost=%d/%d test_boost_interval=%d "
2366                  "test_boost_duration=%d shutdown_secs=%d "
2367                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
2368                  "stall_cpu_block=%d "
2369                  "n_barrier_cbs=%d "
2370                  "onoff_interval=%d onoff_holdoff=%d "
2371                  "read_exit_delay=%d read_exit_burst=%d "
2372                  "nocbs_nthreads=%d nocbs_toggle=%d "
2373                  "test_nmis=%d\n",
2374                  torture_type, tag, nrealreaders, nfakewriters,
2375                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
2376                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
2377                  test_boost, cur_ops->can_boost,
2378                  test_boost_interval, test_boost_duration, shutdown_secs,
2379                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
2380                  stall_cpu_block,
2381                  n_barrier_cbs,
2382                  onoff_interval, onoff_holdoff,
2383                  read_exit_delay, read_exit_burst,
2384                  nocbs_nthreads, nocbs_toggle,
2385                  test_nmis);
2386 }
2387
2388 static int rcutorture_booster_cleanup(unsigned int cpu)
2389 {
2390         struct task_struct *t;
2391
2392         if (boost_tasks[cpu] == NULL)
2393                 return 0;
2394         mutex_lock(&boost_mutex);
2395         t = boost_tasks[cpu];
2396         boost_tasks[cpu] = NULL;
2397         rcu_torture_enable_rt_throttle();
2398         mutex_unlock(&boost_mutex);
2399
2400         /* This must be outside of the mutex, otherwise deadlock! */
2401         torture_stop_kthread(rcu_torture_boost, t);
2402         return 0;
2403 }
2404
2405 static int rcutorture_booster_init(unsigned int cpu)
2406 {
2407         int retval;
2408
2409         if (boost_tasks[cpu] != NULL)
2410                 return 0;  /* Already created, nothing more to do. */
2411
2412         // Testing RCU priority boosting requires rcutorture do
2413         // some serious abuse.  Counter this by running ksoftirqd
2414         // at higher priority.
2415         if (IS_BUILTIN(CONFIG_RCU_TORTURE_TEST)) {
2416                 struct sched_param sp;
2417                 struct task_struct *t;
2418
2419                 t = per_cpu(ksoftirqd, cpu);
2420                 WARN_ON_ONCE(!t);
2421                 sp.sched_priority = 2;
2422                 sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
2423         }
2424
2425         /* Don't allow time recalculation while creating a new task. */
2426         mutex_lock(&boost_mutex);
2427         rcu_torture_disable_rt_throttle();
2428         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
2429         boost_tasks[cpu] = kthread_run_on_cpu(rcu_torture_boost, NULL,
2430                                               cpu, "rcu_torture_boost_%u");
2431         if (IS_ERR(boost_tasks[cpu])) {
2432                 retval = PTR_ERR(boost_tasks[cpu]);
2433                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
2434                 n_rcu_torture_boost_ktrerror++;
2435                 boost_tasks[cpu] = NULL;
2436                 mutex_unlock(&boost_mutex);
2437                 return retval;
2438         }
2439         mutex_unlock(&boost_mutex);
2440         return 0;
2441 }
2442
2443 static int rcu_torture_stall_nf(struct notifier_block *nb, unsigned long v, void *ptr)
2444 {
2445         pr_info("%s: v=%lu, duration=%lu.\n", __func__, v, (unsigned long)ptr);
2446         return NOTIFY_OK;
2447 }
2448
2449 static struct notifier_block rcu_torture_stall_block = {
2450         .notifier_call = rcu_torture_stall_nf,
2451 };
2452
2453 /*
2454  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
2455  * induces a CPU stall for the time specified by stall_cpu.  If a new
2456  * stall test is added, stallsdone in rcu_torture_writer() must be adjusted.
2457  */
2458 static int rcu_torture_stall(void *args)
2459 {
2460         int idx;
2461         int ret;
2462         unsigned long stop_at;
2463
2464         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
2465         if (rcu_cpu_stall_notifiers) {
2466                 ret = rcu_stall_chain_notifier_register(&rcu_torture_stall_block);
2467                 if (ret)
2468                         pr_info("%s: rcu_stall_chain_notifier_register() returned %d, %sexpected.\n",
2469                                 __func__, ret, !IS_ENABLED(CONFIG_RCU_STALL_COMMON) ? "un" : "");
2470         }
2471         if (stall_cpu_holdoff > 0) {
2472                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
2473                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
2474                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
2475         }
2476         if (!kthread_should_stop() && stall_gp_kthread > 0) {
2477                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin GP stall");
2478                 rcu_gp_set_torture_wait(stall_gp_kthread * HZ);
2479                 for (idx = 0; idx < stall_gp_kthread + 2; idx++) {
2480                         if (kthread_should_stop())
2481                                 break;
2482                         schedule_timeout_uninterruptible(HZ);
2483                 }
2484         }
2485         if (!kthread_should_stop() && stall_cpu > 0) {
2486                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin CPU stall");
2487                 stop_at = ktime_get_seconds() + stall_cpu;
2488                 /* RCU CPU stall is expected behavior in following code. */
2489                 idx = cur_ops->readlock();
2490                 if (stall_cpu_irqsoff)
2491                         local_irq_disable();
2492                 else if (!stall_cpu_block)
2493                         preempt_disable();
2494                 pr_alert("%s start on CPU %d.\n",
2495                           __func__, raw_smp_processor_id());
2496                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(), stop_at) &&
2497                        !kthread_should_stop())
2498                         if (stall_cpu_block) {
2499 #ifdef CONFIG_PREEMPTION
2500                                 preempt_schedule();
2501 #else
2502                                 schedule_timeout_uninterruptible(HZ);
2503 #endif
2504                         } else if (stall_no_softlockup) {
2505                                 touch_softlockup_watchdog();
2506                         }
2507                 if (stall_cpu_irqsoff)
2508                         local_irq_enable();
2509                 else if (!stall_cpu_block)
2510                         preempt_enable();
2511                 cur_ops->readunlock(idx);
2512         }
2513         pr_alert("%s end.\n", __func__);
2514         if (rcu_cpu_stall_notifiers && !ret) {
2515                 ret = rcu_stall_chain_notifier_unregister(&rcu_torture_stall_block);
2516                 if (ret)
2517                         pr_info("%s: rcu_stall_chain_notifier_unregister() returned %d.\n", __func__, ret);
2518         }
2519         torture_shutdown_absorb("rcu_torture_stall");
2520         while (!kthread_should_stop())
2521                 schedule_timeout_interruptible(10 * HZ);
2522         return 0;
2523 }
2524
2525 /* Spawn CPU-stall kthread, if stall_cpu specified. */
2526 static int __init rcu_torture_stall_init(void)
2527 {
2528         if (stall_cpu <= 0 && stall_gp_kthread <= 0)
2529                 return 0;
2530         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
2531 }
2532
2533 /* State structure for forward-progress self-propagating RCU callback. */
2534 struct fwd_cb_state {
2535         struct rcu_head rh;
2536         int stop;
2537 };
2538
2539 /*
2540  * Forward-progress self-propagating RCU callback function.  Because
2541  * callbacks run from softirq, this function is an implicit RCU read-side
2542  * critical section.
2543  */
2544 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
2545 {
2546         struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
2547
2548         if (READ_ONCE(fcsp->stop)) {
2549                 WRITE_ONCE(fcsp->stop, 2);
2550                 return;
2551         }
2552         cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
2553 }
2554
2555 /* State for continuous-flood RCU callbacks. */
2556 struct rcu_fwd_cb {
2557         struct rcu_head rh;
2558         struct rcu_fwd_cb *rfc_next;
2559         struct rcu_fwd *rfc_rfp;
2560         int rfc_gps;
2561 };
2562
2563 #define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
2564 #define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
2565 #define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
2566 #define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
2567 #define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
2568
2569 struct rcu_launder_hist {
2570         long n_launders;
2571         unsigned long launder_gp_seq;
2572 };
2573
2574 struct rcu_fwd {
2575         spinlock_t rcu_fwd_lock;
2576         struct rcu_fwd_cb *rcu_fwd_cb_head;
2577         struct rcu_fwd_cb **rcu_fwd_cb_tail;
2578         long n_launders_cb;
2579         unsigned long rcu_fwd_startat;
2580         struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
2581         unsigned long rcu_launder_gp_seq_start;
2582         int rcu_fwd_id;
2583 };
2584
2585 static DEFINE_MUTEX(rcu_fwd_mutex);
2586 static struct rcu_fwd *rcu_fwds;
2587 static unsigned long rcu_fwd_seq;
2588 static atomic_long_t rcu_fwd_max_cbs;
2589 static bool rcu_fwd_emergency_stop;
2590
2591 static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
2592 {
2593         unsigned long gps;
2594         unsigned long gps_old;
2595         int i;
2596         int j;
2597
2598         for (i = ARRAY_SIZE(rfp->n_launders_hist) - 1; i > 0; i--)
2599                 if (rfp->n_launders_hist[i].n_launders > 0)
2600                         break;
2601         pr_alert("%s: Callback-invocation histogram %d (duration %lu jiffies):",
2602                  __func__, rfp->rcu_fwd_id, jiffies - rfp->rcu_fwd_startat);
2603         gps_old = rfp->rcu_launder_gp_seq_start;
2604         for (j = 0; j <= i; j++) {
2605                 gps = rfp->n_launders_hist[j].launder_gp_seq;
2606                 pr_cont(" %ds/%d: %ld:%ld",
2607                         j + 1, FWD_CBS_HIST_DIV,
2608                         rfp->n_launders_hist[j].n_launders,
2609                         rcutorture_seq_diff(gps, gps_old));
2610                 gps_old = gps;
2611         }
2612         pr_cont("\n");
2613 }
2614
2615 /* Callback function for continuous-flood RCU callbacks. */
2616 static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
2617 {
2618         unsigned long flags;
2619         int i;
2620         struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
2621         struct rcu_fwd_cb **rfcpp;
2622         struct rcu_fwd *rfp = rfcp->rfc_rfp;
2623
2624         rfcp->rfc_next = NULL;
2625         rfcp->rfc_gps++;
2626         spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
2627         rfcpp = rfp->rcu_fwd_cb_tail;
2628         rfp->rcu_fwd_cb_tail = &rfcp->rfc_next;
2629         WRITE_ONCE(*rfcpp, rfcp);
2630         WRITE_ONCE(rfp->n_launders_cb, rfp->n_launders_cb + 1);
2631         i = ((jiffies - rfp->rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
2632         if (i >= ARRAY_SIZE(rfp->n_launders_hist))
2633                 i = ARRAY_SIZE(rfp->n_launders_hist) - 1;
2634         rfp->n_launders_hist[i].n_launders++;
2635         rfp->n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
2636         spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
2637 }
2638
2639 // Give the scheduler a chance, even on nohz_full CPUs.
2640 static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
2641 {
2642         if (IS_ENABLED(CONFIG_PREEMPTION) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
2643                 // Real call_rcu() floods hit userspace, so emulate that.
2644                 if (need_resched() || (iter & 0xfff))
2645                         schedule();
2646                 return;
2647         }
2648         // No userspace emulation: CB invocation throttles call_rcu()
2649         cond_resched();
2650 }
2651
2652 /*
2653  * Free all callbacks on the rcu_fwd_cb_head list, either because the
2654  * test is over or because we hit an OOM event.
2655  */
2656 static unsigned long rcu_torture_fwd_prog_cbfree(struct rcu_fwd *rfp)
2657 {
2658         unsigned long flags;
2659         unsigned long freed = 0;
2660         struct rcu_fwd_cb *rfcp;
2661
2662         for (;;) {
2663                 spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
2664                 rfcp = rfp->rcu_fwd_cb_head;
2665                 if (!rfcp) {
2666                         spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
2667                         break;
2668                 }
2669                 rfp->rcu_fwd_cb_head = rfcp->rfc_next;
2670                 if (!rfp->rcu_fwd_cb_head)
2671                         rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
2672                 spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
2673                 kfree(rfcp);
2674                 freed++;
2675                 rcu_torture_fwd_prog_cond_resched(freed);
2676                 if (tick_nohz_full_enabled()) {
2677                         local_irq_save(flags);
2678                         rcu_momentary_dyntick_idle();
2679                         local_irq_restore(flags);
2680                 }
2681         }
2682         return freed;
2683 }
2684
2685 /* Carry out need_resched()/cond_resched() forward-progress testing. */
2686 static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
2687                                     int *tested, int *tested_tries)
2688 {
2689         unsigned long cver;
2690         unsigned long dur;
2691         struct fwd_cb_state fcs;
2692         unsigned long gps;
2693         int idx;
2694         int sd;
2695         int sd4;
2696         bool selfpropcb = false;
2697         unsigned long stopat;
2698         static DEFINE_TORTURE_RANDOM(trs);
2699
2700         pr_alert("%s: Starting forward-progress test %d\n", __func__, rfp->rcu_fwd_id);
2701         if (!cur_ops->sync)
2702                 return; // Cannot do need_resched() forward progress testing without ->sync.
2703         if (cur_ops->call && cur_ops->cb_barrier) {
2704                 init_rcu_head_on_stack(&fcs.rh);
2705                 selfpropcb = true;
2706         }
2707
2708         /* Tight loop containing cond_resched(). */
2709         atomic_inc(&rcu_fwd_cb_nodelay);
2710         cur_ops->sync(); /* Later readers see above write. */
2711         if  (selfpropcb) {
2712                 WRITE_ONCE(fcs.stop, 0);
2713                 cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
2714         }
2715         cver = READ_ONCE(rcu_torture_current_version);
2716         gps = cur_ops->get_gp_seq();
2717         sd = cur_ops->stall_dur() + 1;
2718         sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
2719         dur = sd4 + torture_random(&trs) % (sd - sd4);
2720         WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
2721         stopat = rfp->rcu_fwd_startat + dur;
2722         while (time_before(jiffies, stopat) &&
2723                !shutdown_time_arrived() &&
2724                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2725                 idx = cur_ops->readlock();
2726                 udelay(10);
2727                 cur_ops->readunlock(idx);
2728                 if (!fwd_progress_need_resched || need_resched())
2729                         cond_resched();
2730         }
2731         (*tested_tries)++;
2732         if (!time_before(jiffies, stopat) &&
2733             !shutdown_time_arrived() &&
2734             !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2735                 (*tested)++;
2736                 cver = READ_ONCE(rcu_torture_current_version) - cver;
2737                 gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
2738                 WARN_ON(!cver && gps < 2);
2739                 pr_alert("%s: %d Duration %ld cver %ld gps %ld\n", __func__,
2740                          rfp->rcu_fwd_id, dur, cver, gps);
2741         }
2742         if (selfpropcb) {
2743                 WRITE_ONCE(fcs.stop, 1);
2744                 cur_ops->sync(); /* Wait for running CB to complete. */
2745                 pr_alert("%s: Waiting for CBs: %pS() %d\n", __func__, cur_ops->cb_barrier, rfp->rcu_fwd_id);
2746                 cur_ops->cb_barrier(); /* Wait for queued callbacks. */
2747         }
2748
2749         if (selfpropcb) {
2750                 WARN_ON(READ_ONCE(fcs.stop) != 2);
2751                 destroy_rcu_head_on_stack(&fcs.rh);
2752         }
2753         schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
2754         atomic_dec(&rcu_fwd_cb_nodelay);
2755 }
2756
2757 /* Carry out call_rcu() forward-progress testing. */
2758 static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
2759 {
2760         unsigned long cver;
2761         unsigned long flags;
2762         unsigned long gps;
2763         int i;
2764         long n_launders;
2765         long n_launders_cb_snap;
2766         long n_launders_sa;
2767         long n_max_cbs;
2768         long n_max_gps;
2769         struct rcu_fwd_cb *rfcp;
2770         struct rcu_fwd_cb *rfcpn;
2771         unsigned long stopat;
2772         unsigned long stoppedat;
2773
2774         pr_alert("%s: Starting forward-progress test %d\n", __func__, rfp->rcu_fwd_id);
2775         if (READ_ONCE(rcu_fwd_emergency_stop))
2776                 return; /* Get out of the way quickly, no GP wait! */
2777         if (!cur_ops->call)
2778                 return; /* Can't do call_rcu() fwd prog without ->call. */
2779
2780         /* Loop continuously posting RCU callbacks. */
2781         atomic_inc(&rcu_fwd_cb_nodelay);
2782         cur_ops->sync(); /* Later readers see above write. */
2783         WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
2784         stopat = rfp->rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
2785         n_launders = 0;
2786         rfp->n_launders_cb = 0; // Hoist initialization for multi-kthread
2787         n_launders_sa = 0;
2788         n_max_cbs = 0;
2789         n_max_gps = 0;
2790         for (i = 0; i < ARRAY_SIZE(rfp->n_launders_hist); i++)
2791                 rfp->n_launders_hist[i].n_launders = 0;
2792         cver = READ_ONCE(rcu_torture_current_version);
2793         gps = cur_ops->get_gp_seq();
2794         rfp->rcu_launder_gp_seq_start = gps;
2795         tick_dep_set_task(current, TICK_DEP_BIT_RCU);
2796         while (time_before(jiffies, stopat) &&
2797                !shutdown_time_arrived() &&
2798                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2799                 rfcp = READ_ONCE(rfp->rcu_fwd_cb_head);
2800                 rfcpn = NULL;
2801                 if (rfcp)
2802                         rfcpn = READ_ONCE(rfcp->rfc_next);
2803                 if (rfcpn) {
2804                         if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
2805                             ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
2806                                 break;
2807                         rfp->rcu_fwd_cb_head = rfcpn;
2808                         n_launders++;
2809                         n_launders_sa++;
2810                 } else if (!cur_ops->cbflood_max || cur_ops->cbflood_max > n_max_cbs) {
2811                         rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
2812                         if (WARN_ON_ONCE(!rfcp)) {
2813                                 schedule_timeout_interruptible(1);
2814                                 continue;
2815                         }
2816                         n_max_cbs++;
2817                         n_launders_sa = 0;
2818                         rfcp->rfc_gps = 0;
2819                         rfcp->rfc_rfp = rfp;
2820                 } else {
2821                         rfcp = NULL;
2822                 }
2823                 if (rfcp)
2824                         cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
2825                 rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
2826                 if (tick_nohz_full_enabled()) {
2827                         local_irq_save(flags);
2828                         rcu_momentary_dyntick_idle();
2829                         local_irq_restore(flags);
2830                 }
2831         }
2832         stoppedat = jiffies;
2833         n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
2834         cver = READ_ONCE(rcu_torture_current_version) - cver;
2835         gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
2836         pr_alert("%s: Waiting for CBs: %pS() %d\n", __func__, cur_ops->cb_barrier, rfp->rcu_fwd_id);
2837         cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
2838         (void)rcu_torture_fwd_prog_cbfree(rfp);
2839
2840         if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
2841             !shutdown_time_arrived()) {
2842                 if (WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED) && cur_ops->gp_kthread_dbg)
2843                         cur_ops->gp_kthread_dbg();
2844                 pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld #online %u\n",
2845                          __func__,
2846                          stoppedat - rfp->rcu_fwd_startat, jiffies - stoppedat,
2847                          n_launders + n_max_cbs - n_launders_cb_snap,
2848                          n_launders, n_launders_sa,
2849                          n_max_gps, n_max_cbs, cver, gps, num_online_cpus());
2850                 atomic_long_add(n_max_cbs, &rcu_fwd_max_cbs);
2851                 mutex_lock(&rcu_fwd_mutex); // Serialize histograms.
2852                 rcu_torture_fwd_cb_hist(rfp);
2853                 mutex_unlock(&rcu_fwd_mutex);
2854         }
2855         schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
2856         tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
2857         atomic_dec(&rcu_fwd_cb_nodelay);
2858 }
2859
2860
2861 /*
2862  * OOM notifier, but this only prints diagnostic information for the
2863  * current forward-progress test.
2864  */
2865 static int rcutorture_oom_notify(struct notifier_block *self,
2866                                  unsigned long notused, void *nfreed)
2867 {
2868         int i;
2869         long ncbs;
2870         struct rcu_fwd *rfp;
2871
2872         mutex_lock(&rcu_fwd_mutex);
2873         rfp = rcu_fwds;
2874         if (!rfp) {
2875                 mutex_unlock(&rcu_fwd_mutex);
2876                 return NOTIFY_OK;
2877         }
2878         WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
2879              __func__);
2880         for (i = 0; i < fwd_progress; i++) {
2881                 rcu_torture_fwd_cb_hist(&rfp[i]);
2882                 rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rfp[i].rcu_fwd_startat)) / 2);
2883         }
2884         WRITE_ONCE(rcu_fwd_emergency_stop, true);
2885         smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
2886         ncbs = 0;
2887         for (i = 0; i < fwd_progress; i++)
2888                 ncbs += rcu_torture_fwd_prog_cbfree(&rfp[i]);
2889         pr_info("%s: Freed %lu RCU callbacks.\n", __func__, ncbs);
2890         cur_ops->cb_barrier();
2891         ncbs = 0;
2892         for (i = 0; i < fwd_progress; i++)
2893                 ncbs += rcu_torture_fwd_prog_cbfree(&rfp[i]);
2894         pr_info("%s: Freed %lu RCU callbacks.\n", __func__, ncbs);
2895         cur_ops->cb_barrier();
2896         ncbs = 0;
2897         for (i = 0; i < fwd_progress; i++)
2898                 ncbs += rcu_torture_fwd_prog_cbfree(&rfp[i]);
2899         pr_info("%s: Freed %lu RCU callbacks.\n", __func__, ncbs);
2900         smp_mb(); /* Frees before return to avoid redoing OOM. */
2901         (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
2902         pr_info("%s returning after OOM processing.\n", __func__);
2903         mutex_unlock(&rcu_fwd_mutex);
2904         return NOTIFY_OK;
2905 }
2906
2907 static struct notifier_block rcutorture_oom_nb = {
2908         .notifier_call = rcutorture_oom_notify
2909 };
2910
2911 /* Carry out grace-period forward-progress testing. */
2912 static int rcu_torture_fwd_prog(void *args)
2913 {
2914         bool firsttime = true;
2915         long max_cbs;
2916         int oldnice = task_nice(current);
2917         unsigned long oldseq = READ_ONCE(rcu_fwd_seq);
2918         struct rcu_fwd *rfp = args;
2919         int tested = 0;
2920         int tested_tries = 0;
2921
2922         VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
2923         rcu_bind_current_to_nocb();
2924         if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
2925                 set_user_nice(current, MAX_NICE);
2926         do {
2927                 if (!rfp->rcu_fwd_id) {
2928                         schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
2929                         WRITE_ONCE(rcu_fwd_emergency_stop, false);
2930                         if (!firsttime) {
2931                                 max_cbs = atomic_long_xchg(&rcu_fwd_max_cbs, 0);
2932                                 pr_alert("%s n_max_cbs: %ld\n", __func__, max_cbs);
2933                         }
2934                         firsttime = false;
2935                         WRITE_ONCE(rcu_fwd_seq, rcu_fwd_seq + 1);
2936                 } else {
2937                         while (READ_ONCE(rcu_fwd_seq) == oldseq && !torture_must_stop())
2938                                 schedule_timeout_interruptible(HZ / 20);
2939                         oldseq = READ_ONCE(rcu_fwd_seq);
2940                 }
2941                 pr_alert("%s: Starting forward-progress test %d\n", __func__, rfp->rcu_fwd_id);
2942                 if (rcu_inkernel_boot_has_ended() && torture_num_online_cpus() > rfp->rcu_fwd_id)
2943                         rcu_torture_fwd_prog_cr(rfp);
2944                 if ((cur_ops->stall_dur && cur_ops->stall_dur() > 0) &&
2945                     (!IS_ENABLED(CONFIG_TINY_RCU) ||
2946                      (rcu_inkernel_boot_has_ended() &&
2947                       torture_num_online_cpus() > rfp->rcu_fwd_id)))
2948                         rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
2949
2950                 /* Avoid slow periods, better to test when busy. */
2951                 if (stutter_wait("rcu_torture_fwd_prog"))
2952                         sched_set_normal(current, oldnice);
2953         } while (!torture_must_stop());
2954         /* Short runs might not contain a valid forward-progress attempt. */
2955         if (!rfp->rcu_fwd_id) {
2956                 WARN_ON(!tested && tested_tries >= 5);
2957                 pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
2958         }
2959         torture_kthread_stopping("rcu_torture_fwd_prog");
2960         return 0;
2961 }
2962
2963 /* If forward-progress checking is requested and feasible, spawn the thread. */
2964 static int __init rcu_torture_fwd_prog_init(void)
2965 {
2966         int i;
2967         int ret = 0;
2968         struct rcu_fwd *rfp;
2969
2970         if (!fwd_progress)
2971                 return 0; /* Not requested, so don't do it. */
2972         if (fwd_progress >= nr_cpu_ids) {
2973                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Limiting fwd_progress to # CPUs.\n");
2974                 fwd_progress = nr_cpu_ids;
2975         } else if (fwd_progress < 0) {
2976                 fwd_progress = nr_cpu_ids;
2977         }
2978         if ((!cur_ops->sync && !cur_ops->call) ||
2979             (!cur_ops->cbflood_max && (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0)) ||
2980             cur_ops == &rcu_busted_ops) {
2981                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
2982                 fwd_progress = 0;
2983                 return 0;
2984         }
2985         if (stall_cpu > 0) {
2986                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
2987                 fwd_progress = 0;
2988                 if (IS_MODULE(CONFIG_RCU_TORTURE_TEST))
2989                         return -EINVAL; /* In module, can fail back to user. */
2990                 WARN_ON(1); /* Make sure rcutorture notices conflict. */
2991                 return 0;
2992         }
2993         if (fwd_progress_holdoff <= 0)
2994                 fwd_progress_holdoff = 1;
2995         if (fwd_progress_div <= 0)
2996                 fwd_progress_div = 4;
2997         rfp = kcalloc(fwd_progress, sizeof(*rfp), GFP_KERNEL);
2998         fwd_prog_tasks = kcalloc(fwd_progress, sizeof(*fwd_prog_tasks), GFP_KERNEL);
2999         if (!rfp || !fwd_prog_tasks) {
3000                 kfree(rfp);
3001                 kfree(fwd_prog_tasks);
3002                 fwd_prog_tasks = NULL;
3003                 fwd_progress = 0;
3004                 return -ENOMEM;
3005         }
3006         for (i = 0; i < fwd_progress; i++) {
3007                 spin_lock_init(&rfp[i].rcu_fwd_lock);
3008                 rfp[i].rcu_fwd_cb_tail = &rfp[i].rcu_fwd_cb_head;
3009                 rfp[i].rcu_fwd_id = i;
3010         }
3011         mutex_lock(&rcu_fwd_mutex);
3012         rcu_fwds = rfp;
3013         mutex_unlock(&rcu_fwd_mutex);
3014         register_oom_notifier(&rcutorture_oom_nb);
3015         for (i = 0; i < fwd_progress; i++) {
3016                 ret = torture_create_kthread(rcu_torture_fwd_prog, &rcu_fwds[i], fwd_prog_tasks[i]);
3017                 if (ret) {
3018                         fwd_progress = i;
3019                         return ret;
3020                 }
3021         }
3022         return 0;
3023 }
3024
3025 static void rcu_torture_fwd_prog_cleanup(void)
3026 {
3027         int i;
3028         struct rcu_fwd *rfp;
3029
3030         if (!rcu_fwds || !fwd_prog_tasks)
3031                 return;
3032         for (i = 0; i < fwd_progress; i++)
3033                 torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_tasks[i]);
3034         unregister_oom_notifier(&rcutorture_oom_nb);
3035         mutex_lock(&rcu_fwd_mutex);
3036         rfp = rcu_fwds;
3037         rcu_fwds = NULL;
3038         mutex_unlock(&rcu_fwd_mutex);
3039         kfree(rfp);
3040         kfree(fwd_prog_tasks);
3041         fwd_prog_tasks = NULL;
3042 }
3043
3044 /* Callback function for RCU barrier testing. */
3045 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
3046 {
3047         atomic_inc(&barrier_cbs_invoked);
3048 }
3049
3050 /* IPI handler to get callback posted on desired CPU, if online. */
3051 static int rcu_torture_barrier1cb(void *rcu_void)
3052 {
3053         struct rcu_head *rhp = rcu_void;
3054
3055         cur_ops->call(rhp, rcu_torture_barrier_cbf);
3056         return 0;
3057 }
3058
3059 /* kthread function to register callbacks used to test RCU barriers. */
3060 static int rcu_torture_barrier_cbs(void *arg)
3061 {
3062         long myid = (long)arg;
3063         bool lastphase = false;
3064         bool newphase;
3065         struct rcu_head rcu;
3066
3067         init_rcu_head_on_stack(&rcu);
3068         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
3069         set_user_nice(current, MAX_NICE);
3070         do {
3071                 wait_event(barrier_cbs_wq[myid],
3072                            (newphase =
3073                             smp_load_acquire(&barrier_phase)) != lastphase ||
3074                            torture_must_stop());
3075                 lastphase = newphase;
3076                 if (torture_must_stop())
3077                         break;
3078                 /*
3079                  * The above smp_load_acquire() ensures barrier_phase load
3080                  * is ordered before the following ->call().
3081                  */
3082                 if (smp_call_on_cpu(myid, rcu_torture_barrier1cb, &rcu, 1))
3083                         cur_ops->call(&rcu, rcu_torture_barrier_cbf);
3084
3085                 if (atomic_dec_and_test(&barrier_cbs_count))
3086                         wake_up(&barrier_wq);
3087         } while (!torture_must_stop());
3088         if (cur_ops->cb_barrier != NULL)
3089                 cur_ops->cb_barrier();
3090         destroy_rcu_head_on_stack(&rcu);
3091         torture_kthread_stopping("rcu_torture_barrier_cbs");
3092         return 0;
3093 }
3094
3095 /* kthread function to drive and coordinate RCU barrier testing. */
3096 static int rcu_torture_barrier(void *arg)
3097 {
3098         int i;
3099
3100         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
3101         do {
3102                 atomic_set(&barrier_cbs_invoked, 0);
3103                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
3104                 /* Ensure barrier_phase ordered after prior assignments. */
3105                 smp_store_release(&barrier_phase, !barrier_phase);
3106                 for (i = 0; i < n_barrier_cbs; i++)
3107                         wake_up(&barrier_cbs_wq[i]);
3108                 wait_event(barrier_wq,
3109                            atomic_read(&barrier_cbs_count) == 0 ||
3110                            torture_must_stop());
3111                 if (torture_must_stop())
3112                         break;
3113                 n_barrier_attempts++;
3114                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
3115                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
3116                         n_rcu_torture_barrier_error++;
3117                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
3118                                atomic_read(&barrier_cbs_invoked),
3119                                n_barrier_cbs);
3120                         WARN_ON(1);
3121                         // Wait manually for the remaining callbacks
3122                         i = 0;
3123                         do {
3124                                 if (WARN_ON(i++ > HZ))
3125                                         i = INT_MIN;
3126                                 schedule_timeout_interruptible(1);
3127                                 cur_ops->cb_barrier();
3128                         } while (atomic_read(&barrier_cbs_invoked) !=
3129                                  n_barrier_cbs &&
3130                                  !torture_must_stop());
3131                         smp_mb(); // Can't trust ordering if broken.
3132                         if (!torture_must_stop())
3133                                 pr_err("Recovered: barrier_cbs_invoked = %d\n",
3134                                        atomic_read(&barrier_cbs_invoked));
3135                 } else {
3136                         n_barrier_successes++;
3137                 }
3138                 schedule_timeout_interruptible(HZ / 10);
3139         } while (!torture_must_stop());
3140         torture_kthread_stopping("rcu_torture_barrier");
3141         return 0;
3142 }
3143
3144 /* Initialize RCU barrier testing. */
3145 static int rcu_torture_barrier_init(void)
3146 {
3147         int i;
3148         int ret;
3149
3150         if (n_barrier_cbs <= 0)
3151                 return 0;
3152         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
3153                 pr_alert("%s" TORTURE_FLAG
3154                          " Call or barrier ops missing for %s,\n",
3155                          torture_type, cur_ops->name);
3156                 pr_alert("%s" TORTURE_FLAG
3157                          " RCU barrier testing omitted from run.\n",
3158                          torture_type);
3159                 return 0;
3160         }
3161         atomic_set(&barrier_cbs_count, 0);
3162         atomic_set(&barrier_cbs_invoked, 0);
3163         barrier_cbs_tasks =
3164                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
3165                         GFP_KERNEL);
3166         barrier_cbs_wq =
3167                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
3168         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
3169                 return -ENOMEM;
3170         for (i = 0; i < n_barrier_cbs; i++) {
3171                 init_waitqueue_head(&barrier_cbs_wq[i]);
3172                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
3173                                              (void *)(long)i,
3174                                              barrier_cbs_tasks[i]);
3175                 if (ret)
3176                         return ret;
3177         }
3178         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
3179 }
3180
3181 /* Clean up after RCU barrier testing. */
3182 static void rcu_torture_barrier_cleanup(void)
3183 {
3184         int i;
3185
3186         torture_stop_kthread(rcu_torture_barrier, barrier_task);
3187         if (barrier_cbs_tasks != NULL) {
3188                 for (i = 0; i < n_barrier_cbs; i++)
3189                         torture_stop_kthread(rcu_torture_barrier_cbs,
3190                                              barrier_cbs_tasks[i]);
3191                 kfree(barrier_cbs_tasks);
3192                 barrier_cbs_tasks = NULL;
3193         }
3194         if (barrier_cbs_wq != NULL) {
3195                 kfree(barrier_cbs_wq);
3196                 barrier_cbs_wq = NULL;
3197         }
3198 }
3199
3200 static bool rcu_torture_can_boost(void)
3201 {
3202         static int boost_warn_once;
3203         int prio;
3204
3205         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
3206                 return false;
3207         if (!cur_ops->start_gp_poll || !cur_ops->poll_gp_state)
3208                 return false;
3209
3210         prio = rcu_get_gp_kthreads_prio();
3211         if (!prio)
3212                 return false;
3213
3214         if (prio < 2) {
3215                 if (boost_warn_once == 1)
3216                         return false;
3217
3218                 pr_alert("%s: WARN: RCU kthread priority too low to test boosting.  Skipping RCU boost test. Try passing rcutree.kthread_prio > 1 on the kernel command line.\n", KBUILD_MODNAME);
3219                 boost_warn_once = 1;
3220                 return false;
3221         }
3222
3223         return true;
3224 }
3225
3226 static bool read_exit_child_stop;
3227 static bool read_exit_child_stopped;
3228 static wait_queue_head_t read_exit_wq;
3229
3230 // Child kthread which just does an rcutorture reader and exits.
3231 static int rcu_torture_read_exit_child(void *trsp_in)
3232 {
3233         struct torture_random_state *trsp = trsp_in;
3234
3235         set_user_nice(current, MAX_NICE);
3236         // Minimize time between reading and exiting.
3237         while (!kthread_should_stop())
3238                 schedule_timeout_uninterruptible(HZ / 20);
3239         (void)rcu_torture_one_read(trsp, -1);
3240         return 0;
3241 }
3242
3243 // Parent kthread which creates and destroys read-exit child kthreads.
3244 static int rcu_torture_read_exit(void *unused)
3245 {
3246         bool errexit = false;
3247         int i;
3248         struct task_struct *tsp;
3249         DEFINE_TORTURE_RANDOM(trs);
3250
3251         // Allocate and initialize.
3252         set_user_nice(current, MAX_NICE);
3253         VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of test");
3254
3255         // Each pass through this loop does one read-exit episode.
3256         do {
3257                 VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of episode");
3258                 for (i = 0; i < read_exit_burst; i++) {
3259                         if (READ_ONCE(read_exit_child_stop))
3260                                 break;
3261                         stutter_wait("rcu_torture_read_exit");
3262                         // Spawn child.
3263                         tsp = kthread_run(rcu_torture_read_exit_child,
3264                                           &trs, "%s", "rcu_torture_read_exit_child");
3265                         if (IS_ERR(tsp)) {
3266                                 TOROUT_ERRSTRING("out of memory");
3267                                 errexit = true;
3268                                 break;
3269                         }
3270                         cond_resched();
3271                         kthread_stop(tsp);
3272                         n_read_exits++;
3273                 }
3274                 VERBOSE_TOROUT_STRING("rcu_torture_read_exit: End of episode");
3275                 rcu_barrier(); // Wait for task_struct free, avoid OOM.
3276                 i = 0;
3277                 for (; !errexit && !READ_ONCE(read_exit_child_stop) && i < read_exit_delay; i++)
3278                         schedule_timeout_uninterruptible(HZ);
3279         } while (!errexit && !READ_ONCE(read_exit_child_stop));
3280
3281         // Clean up and exit.
3282         smp_store_release(&read_exit_child_stopped, true); // After reaping.
3283         smp_mb(); // Store before wakeup.
3284         wake_up(&read_exit_wq);
3285         while (!torture_must_stop())
3286                 schedule_timeout_uninterruptible(HZ / 20);
3287         torture_kthread_stopping("rcu_torture_read_exit");
3288         return 0;
3289 }
3290
3291 static int rcu_torture_read_exit_init(void)
3292 {
3293         if (read_exit_burst <= 0)
3294                 return 0;
3295         init_waitqueue_head(&read_exit_wq);
3296         read_exit_child_stop = false;
3297         read_exit_child_stopped = false;
3298         return torture_create_kthread(rcu_torture_read_exit, NULL,
3299                                       read_exit_task);
3300 }
3301
3302 static void rcu_torture_read_exit_cleanup(void)
3303 {
3304         if (!read_exit_task)
3305                 return;
3306         WRITE_ONCE(read_exit_child_stop, true);
3307         smp_mb(); // Above write before wait.
3308         wait_event(read_exit_wq, smp_load_acquire(&read_exit_child_stopped));
3309         torture_stop_kthread(rcutorture_read_exit, read_exit_task);
3310 }
3311
3312 static void rcutorture_test_nmis(int n)
3313 {
3314 #if IS_BUILTIN(CONFIG_RCU_TORTURE_TEST)
3315         int cpu;
3316         int dumpcpu;
3317         int i;
3318
3319         for (i = 0; i < n; i++) {
3320                 preempt_disable();
3321                 cpu = smp_processor_id();
3322                 dumpcpu = cpu + 1;
3323                 if (dumpcpu >= nr_cpu_ids)
3324                         dumpcpu = 0;
3325                 pr_alert("%s: CPU %d invoking dump_cpu_task(%d)\n", __func__, cpu, dumpcpu);
3326                 dump_cpu_task(dumpcpu);
3327                 preempt_enable();
3328                 schedule_timeout_uninterruptible(15 * HZ);
3329         }
3330 #else // #if IS_BUILTIN(CONFIG_RCU_TORTURE_TEST)
3331         WARN_ONCE(n, "Non-zero rcutorture.test_nmis=%d permitted only when rcutorture is built in.\n", test_nmis);
3332 #endif // #else // #if IS_BUILTIN(CONFIG_RCU_TORTURE_TEST)
3333 }
3334
3335 static enum cpuhp_state rcutor_hp;
3336
3337 static void
3338 rcu_torture_cleanup(void)
3339 {
3340         int firsttime;
3341         int flags = 0;
3342         unsigned long gp_seq = 0;
3343         int i;
3344
3345         if (torture_cleanup_begin()) {
3346                 if (cur_ops->cb_barrier != NULL) {
3347                         pr_info("%s: Invoking %pS().\n", __func__, cur_ops->cb_barrier);
3348                         cur_ops->cb_barrier();
3349                 }
3350                 if (cur_ops->gp_slow_unregister)
3351                         cur_ops->gp_slow_unregister(NULL);
3352                 return;
3353         }
3354         if (!cur_ops) {
3355                 torture_cleanup_end();
3356                 return;
3357         }
3358
3359         rcutorture_test_nmis(test_nmis);
3360
3361         if (cur_ops->gp_kthread_dbg)
3362                 cur_ops->gp_kthread_dbg();
3363         rcu_torture_read_exit_cleanup();
3364         rcu_torture_barrier_cleanup();
3365         rcu_torture_fwd_prog_cleanup();
3366         torture_stop_kthread(rcu_torture_stall, stall_task);
3367         torture_stop_kthread(rcu_torture_writer, writer_task);
3368
3369         if (nocb_tasks) {
3370                 for (i = 0; i < nrealnocbers; i++)
3371                         torture_stop_kthread(rcu_nocb_toggle, nocb_tasks[i]);
3372                 kfree(nocb_tasks);
3373                 nocb_tasks = NULL;
3374         }
3375
3376         if (reader_tasks) {
3377                 for (i = 0; i < nrealreaders; i++)
3378                         torture_stop_kthread(rcu_torture_reader,
3379                                              reader_tasks[i]);
3380                 kfree(reader_tasks);
3381                 reader_tasks = NULL;
3382         }
3383         kfree(rcu_torture_reader_mbchk);
3384         rcu_torture_reader_mbchk = NULL;
3385
3386         if (fakewriter_tasks) {
3387                 for (i = 0; i < nfakewriters; i++)
3388                         torture_stop_kthread(rcu_torture_fakewriter,
3389                                              fakewriter_tasks[i]);
3390                 kfree(fakewriter_tasks);
3391                 fakewriter_tasks = NULL;
3392         }
3393
3394         if (cur_ops->get_gp_data)
3395                 cur_ops->get_gp_data(&flags, &gp_seq);
3396         pr_alert("%s:  End-test grace-period state: g%ld f%#x total-gps=%ld\n",
3397                  cur_ops->name, (long)gp_seq, flags,
3398                  rcutorture_seq_diff(gp_seq, start_gp_seq));
3399         torture_stop_kthread(rcu_torture_stats, stats_task);
3400         torture_stop_kthread(rcu_torture_fqs, fqs_task);
3401         if (rcu_torture_can_boost() && rcutor_hp >= 0)
3402                 cpuhp_remove_state(rcutor_hp);
3403
3404         /*
3405          * Wait for all RCU callbacks to fire, then do torture-type-specific
3406          * cleanup operations.
3407          */
3408         if (cur_ops->cb_barrier != NULL) {
3409                 pr_info("%s: Invoking %pS().\n", __func__, cur_ops->cb_barrier);
3410                 cur_ops->cb_barrier();
3411         }
3412         if (cur_ops->cleanup != NULL)
3413                 cur_ops->cleanup();
3414
3415         rcu_torture_mem_dump_obj();
3416
3417         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
3418
3419         if (err_segs_recorded) {
3420                 pr_alert("Failure/close-call rcutorture reader segments:\n");
3421                 if (rt_read_nsegs == 0)
3422                         pr_alert("\t: No segments recorded!!!\n");
3423                 firsttime = 1;
3424                 for (i = 0; i < rt_read_nsegs; i++) {
3425                         pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
3426                         if (err_segs[i].rt_delay_jiffies != 0) {
3427                                 pr_cont("%s%ldjiffies", firsttime ? "" : "+",
3428                                         err_segs[i].rt_delay_jiffies);
3429                                 firsttime = 0;
3430                         }
3431                         if (err_segs[i].rt_delay_ms != 0) {
3432                                 pr_cont("%s%ldms", firsttime ? "" : "+",
3433                                         err_segs[i].rt_delay_ms);
3434                                 firsttime = 0;
3435                         }
3436                         if (err_segs[i].rt_delay_us != 0) {
3437                                 pr_cont("%s%ldus", firsttime ? "" : "+",
3438                                         err_segs[i].rt_delay_us);
3439                                 firsttime = 0;
3440                         }
3441                         pr_cont("%s\n",
3442                                 err_segs[i].rt_preempted ? "preempted" : "");
3443
3444                 }
3445         }
3446         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
3447                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
3448         else if (torture_onoff_failures())
3449                 rcu_torture_print_module_parms(cur_ops,
3450                                                "End of test: RCU_HOTPLUG");
3451         else
3452                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
3453         torture_cleanup_end();
3454         if (cur_ops->gp_slow_unregister)
3455                 cur_ops->gp_slow_unregister(NULL);
3456 }
3457
3458 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
3459 static void rcu_torture_leak_cb(struct rcu_head *rhp)
3460 {
3461 }
3462
3463 static void rcu_torture_err_cb(struct rcu_head *rhp)
3464 {
3465         /*
3466          * This -might- happen due to race conditions, but is unlikely.
3467          * The scenario that leads to this happening is that the
3468          * first of the pair of duplicate callbacks is queued,
3469          * someone else starts a grace period that includes that
3470          * callback, then the second of the pair must wait for the
3471          * next grace period.  Unlikely, but can happen.  If it
3472          * does happen, the debug-objects subsystem won't have splatted.
3473          */
3474         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
3475 }
3476 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
3477
3478 /*
3479  * Verify that double-free causes debug-objects to complain, but only
3480  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
3481  * cannot be carried out.
3482  */
3483 static void rcu_test_debug_objects(void)
3484 {
3485 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
3486         struct rcu_head rh1;
3487         struct rcu_head rh2;
3488         struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
3489
3490         init_rcu_head_on_stack(&rh1);
3491         init_rcu_head_on_stack(&rh2);
3492         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
3493
3494         /* Try to queue the rh2 pair of callbacks for the same grace period. */
3495         preempt_disable(); /* Prevent preemption from interrupting test. */
3496         rcu_read_lock(); /* Make it impossible to finish a grace period. */
3497         call_rcu_hurry(&rh1, rcu_torture_leak_cb); /* Start grace period. */
3498         local_irq_disable(); /* Make it harder to start a new grace period. */
3499         call_rcu_hurry(&rh2, rcu_torture_leak_cb);
3500         call_rcu_hurry(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
3501         if (rhp) {
3502                 call_rcu_hurry(rhp, rcu_torture_leak_cb);
3503                 call_rcu_hurry(rhp, rcu_torture_err_cb); /* Another duplicate callback. */
3504         }
3505         local_irq_enable();
3506         rcu_read_unlock();
3507         preempt_enable();
3508
3509         /* Wait for them all to get done so we can safely return. */
3510         rcu_barrier();
3511         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
3512         destroy_rcu_head_on_stack(&rh1);
3513         destroy_rcu_head_on_stack(&rh2);
3514         kfree(rhp);
3515 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
3516         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
3517 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
3518 }
3519
3520 static void rcutorture_sync(void)
3521 {
3522         static unsigned long n;
3523
3524         if (cur_ops->sync && !(++n & 0xfff))
3525                 cur_ops->sync();
3526 }
3527
3528 static DEFINE_MUTEX(mut0);
3529 static DEFINE_MUTEX(mut1);
3530 static DEFINE_MUTEX(mut2);
3531 static DEFINE_MUTEX(mut3);
3532 static DEFINE_MUTEX(mut4);
3533 static DEFINE_MUTEX(mut5);
3534 static DEFINE_MUTEX(mut6);
3535 static DEFINE_MUTEX(mut7);
3536 static DEFINE_MUTEX(mut8);
3537 static DEFINE_MUTEX(mut9);
3538
3539 static DECLARE_RWSEM(rwsem0);
3540 static DECLARE_RWSEM(rwsem1);
3541 static DECLARE_RWSEM(rwsem2);
3542 static DECLARE_RWSEM(rwsem3);
3543 static DECLARE_RWSEM(rwsem4);
3544 static DECLARE_RWSEM(rwsem5);
3545 static DECLARE_RWSEM(rwsem6);
3546 static DECLARE_RWSEM(rwsem7);
3547 static DECLARE_RWSEM(rwsem8);
3548 static DECLARE_RWSEM(rwsem9);
3549
3550 DEFINE_STATIC_SRCU(srcu0);
3551 DEFINE_STATIC_SRCU(srcu1);
3552 DEFINE_STATIC_SRCU(srcu2);
3553 DEFINE_STATIC_SRCU(srcu3);
3554 DEFINE_STATIC_SRCU(srcu4);
3555 DEFINE_STATIC_SRCU(srcu5);
3556 DEFINE_STATIC_SRCU(srcu6);
3557 DEFINE_STATIC_SRCU(srcu7);
3558 DEFINE_STATIC_SRCU(srcu8);
3559 DEFINE_STATIC_SRCU(srcu9);
3560
3561 static int srcu_lockdep_next(const char *f, const char *fl, const char *fs, const char *fu, int i,
3562                              int cyclelen, int deadlock)
3563 {
3564         int j = i + 1;
3565
3566         if (j >= cyclelen)
3567                 j = deadlock ? 0 : -1;
3568         if (j >= 0)
3569                 pr_info("%s: %s(%d), %s(%d), %s(%d)\n", f, fl, i, fs, j, fu, i);
3570         else
3571                 pr_info("%s: %s(%d), %s(%d)\n", f, fl, i, fu, i);
3572         return j;
3573 }
3574
3575 // Test lockdep on SRCU-based deadlock scenarios.
3576 static void rcu_torture_init_srcu_lockdep(void)
3577 {
3578         int cyclelen;
3579         int deadlock;
3580         bool err = false;
3581         int i;
3582         int j;
3583         int idx;
3584         struct mutex *muts[] = { &mut0, &mut1, &mut2, &mut3, &mut4,
3585                                  &mut5, &mut6, &mut7, &mut8, &mut9 };
3586         struct rw_semaphore *rwsems[] = { &rwsem0, &rwsem1, &rwsem2, &rwsem3, &rwsem4,
3587                                           &rwsem5, &rwsem6, &rwsem7, &rwsem8, &rwsem9 };
3588         struct srcu_struct *srcus[] = { &srcu0, &srcu1, &srcu2, &srcu3, &srcu4,
3589                                         &srcu5, &srcu6, &srcu7, &srcu8, &srcu9 };
3590         int testtype;
3591
3592         if (!test_srcu_lockdep)
3593                 return;
3594
3595         deadlock = test_srcu_lockdep / 1000;
3596         testtype = (test_srcu_lockdep / 10) % 100;
3597         cyclelen = test_srcu_lockdep % 10;
3598         WARN_ON_ONCE(ARRAY_SIZE(muts) != ARRAY_SIZE(srcus));
3599         if (WARN_ONCE(deadlock != !!deadlock,
3600                       "%s: test_srcu_lockdep=%d and deadlock digit %d must be zero or one.\n",
3601                       __func__, test_srcu_lockdep, deadlock))
3602                 err = true;
3603         if (WARN_ONCE(cyclelen <= 0,
3604                       "%s: test_srcu_lockdep=%d and cycle-length digit %d must be greater than zero.\n",
3605                       __func__, test_srcu_lockdep, cyclelen))
3606                 err = true;
3607         if (err)
3608                 goto err_out;
3609
3610         if (testtype == 0) {
3611                 pr_info("%s: test_srcu_lockdep = %05d: SRCU %d-way %sdeadlock.\n",
3612                         __func__, test_srcu_lockdep, cyclelen, deadlock ? "" : "non-");
3613                 if (deadlock && cyclelen == 1)
3614                         pr_info("%s: Expect hang.\n", __func__);
3615                 for (i = 0; i < cyclelen; i++) {
3616                         j = srcu_lockdep_next(__func__, "srcu_read_lock", "synchronize_srcu",
3617                                               "srcu_read_unlock", i, cyclelen, deadlock);
3618                         idx = srcu_read_lock(srcus[i]);
3619                         if (j >= 0)
3620                                 synchronize_srcu(srcus[j]);
3621                         srcu_read_unlock(srcus[i], idx);
3622                 }
3623                 return;
3624         }
3625
3626         if (testtype == 1) {
3627                 pr_info("%s: test_srcu_lockdep = %05d: SRCU/mutex %d-way %sdeadlock.\n",
3628                         __func__, test_srcu_lockdep, cyclelen, deadlock ? "" : "non-");
3629                 for (i = 0; i < cyclelen; i++) {
3630                         pr_info("%s: srcu_read_lock(%d), mutex_lock(%d), mutex_unlock(%d), srcu_read_unlock(%d)\n",
3631                                 __func__, i, i, i, i);
3632                         idx = srcu_read_lock(srcus[i]);
3633                         mutex_lock(muts[i]);
3634                         mutex_unlock(muts[i]);
3635                         srcu_read_unlock(srcus[i], idx);
3636
3637                         j = srcu_lockdep_next(__func__, "mutex_lock", "synchronize_srcu",
3638                                               "mutex_unlock", i, cyclelen, deadlock);
3639                         mutex_lock(muts[i]);
3640                         if (j >= 0)
3641                                 synchronize_srcu(srcus[j]);
3642                         mutex_unlock(muts[i]);
3643                 }
3644                 return;
3645         }
3646
3647         if (testtype == 2) {
3648                 pr_info("%s: test_srcu_lockdep = %05d: SRCU/rwsem %d-way %sdeadlock.\n",
3649                         __func__, test_srcu_lockdep, cyclelen, deadlock ? "" : "non-");
3650                 for (i = 0; i < cyclelen; i++) {
3651                         pr_info("%s: srcu_read_lock(%d), down_read(%d), up_read(%d), srcu_read_unlock(%d)\n",
3652                                 __func__, i, i, i, i);
3653                         idx = srcu_read_lock(srcus[i]);
3654                         down_read(rwsems[i]);
3655                         up_read(rwsems[i]);
3656                         srcu_read_unlock(srcus[i], idx);
3657
3658                         j = srcu_lockdep_next(__func__, "down_write", "synchronize_srcu",
3659                                               "up_write", i, cyclelen, deadlock);
3660                         down_write(rwsems[i]);
3661                         if (j >= 0)
3662                                 synchronize_srcu(srcus[j]);
3663                         up_write(rwsems[i]);
3664                 }
3665                 return;
3666         }
3667
3668 #ifdef CONFIG_TASKS_TRACE_RCU
3669         if (testtype == 3) {
3670                 pr_info("%s: test_srcu_lockdep = %05d: SRCU and Tasks Trace RCU %d-way %sdeadlock.\n",
3671                         __func__, test_srcu_lockdep, cyclelen, deadlock ? "" : "non-");
3672                 if (deadlock && cyclelen == 1)
3673                         pr_info("%s: Expect hang.\n", __func__);
3674                 for (i = 0; i < cyclelen; i++) {
3675                         char *fl = i == 0 ? "rcu_read_lock_trace" : "srcu_read_lock";
3676                         char *fs = i == cyclelen - 1 ? "synchronize_rcu_tasks_trace"
3677                                                      : "synchronize_srcu";
3678                         char *fu = i == 0 ? "rcu_read_unlock_trace" : "srcu_read_unlock";
3679
3680                         j = srcu_lockdep_next(__func__, fl, fs, fu, i, cyclelen, deadlock);
3681                         if (i == 0)
3682                                 rcu_read_lock_trace();
3683                         else
3684                                 idx = srcu_read_lock(srcus[i]);
3685                         if (j >= 0) {
3686                                 if (i == cyclelen - 1)
3687                                         synchronize_rcu_tasks_trace();
3688                                 else
3689                                         synchronize_srcu(srcus[j]);
3690                         }
3691                         if (i == 0)
3692                                 rcu_read_unlock_trace();
3693                         else
3694                                 srcu_read_unlock(srcus[i], idx);
3695                 }
3696                 return;
3697         }
3698 #endif // #ifdef CONFIG_TASKS_TRACE_RCU
3699
3700 err_out:
3701         pr_info("%s: test_srcu_lockdep = %05d does nothing.\n", __func__, test_srcu_lockdep);
3702         pr_info("%s: test_srcu_lockdep = DNNL.\n", __func__);
3703         pr_info("%s: D: Deadlock if nonzero.\n", __func__);
3704         pr_info("%s: NN: Test number, 0=SRCU, 1=SRCU/mutex, 2=SRCU/rwsem, 3=SRCU/Tasks Trace RCU.\n", __func__);
3705         pr_info("%s: L: Cycle length.\n", __func__);
3706         if (!IS_ENABLED(CONFIG_TASKS_TRACE_RCU))
3707                 pr_info("%s: NN=3 disallowed because kernel is built with CONFIG_TASKS_TRACE_RCU=n\n", __func__);
3708 }
3709
3710 static int __init
3711 rcu_torture_init(void)
3712 {
3713         long i;
3714         int cpu;
3715         int firsterr = 0;
3716         int flags = 0;
3717         unsigned long gp_seq = 0;
3718         static struct rcu_torture_ops *torture_ops[] = {
3719                 &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops, &busted_srcud_ops,
3720                 TASKS_OPS TASKS_RUDE_OPS TASKS_TRACING_OPS
3721                 &trivial_ops,
3722         };
3723
3724         if (!torture_init_begin(torture_type, verbose))
3725                 return -EBUSY;
3726
3727         /* Process args and tell the world that the torturer is on the job. */
3728         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
3729                 cur_ops = torture_ops[i];
3730                 if (strcmp(torture_type, cur_ops->name) == 0)
3731                         break;
3732         }
3733         if (i == ARRAY_SIZE(torture_ops)) {
3734                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
3735                          torture_type);
3736                 pr_alert("rcu-torture types:");
3737                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
3738                         pr_cont(" %s", torture_ops[i]->name);
3739                 pr_cont("\n");
3740                 firsterr = -EINVAL;
3741                 cur_ops = NULL;
3742                 goto unwind;
3743         }
3744         if (cur_ops->fqs == NULL && fqs_duration != 0) {
3745                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
3746                 fqs_duration = 0;
3747         }
3748         if (nocbs_nthreads != 0 && (cur_ops != &rcu_ops ||
3749                                     !IS_ENABLED(CONFIG_RCU_NOCB_CPU))) {
3750                 pr_alert("rcu-torture types: %s and CONFIG_RCU_NOCB_CPU=%d, nocb toggle disabled.\n",
3751                          cur_ops->name, IS_ENABLED(CONFIG_RCU_NOCB_CPU));
3752                 nocbs_nthreads = 0;
3753         }
3754         if (cur_ops->init)
3755                 cur_ops->init();
3756
3757         rcu_torture_init_srcu_lockdep();
3758
3759         if (nreaders >= 0) {
3760                 nrealreaders = nreaders;
3761         } else {
3762                 nrealreaders = num_online_cpus() - 2 - nreaders;
3763                 if (nrealreaders <= 0)
3764                         nrealreaders = 1;
3765         }
3766         rcu_torture_print_module_parms(cur_ops, "Start of test");
3767         if (cur_ops->get_gp_data)
3768                 cur_ops->get_gp_data(&flags, &gp_seq);
3769         start_gp_seq = gp_seq;
3770         pr_alert("%s:  Start-test grace-period state: g%ld f%#x\n",
3771                  cur_ops->name, (long)gp_seq, flags);
3772
3773         /* Set up the freelist. */
3774
3775         INIT_LIST_HEAD(&rcu_torture_freelist);
3776         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
3777                 rcu_tortures[i].rtort_mbtest = 0;
3778                 list_add_tail(&rcu_tortures[i].rtort_free,
3779                               &rcu_torture_freelist);
3780         }
3781
3782         /* Initialize the statistics so that each run gets its own numbers. */
3783
3784         rcu_torture_current = NULL;
3785         rcu_torture_current_version = 0;
3786         atomic_set(&n_rcu_torture_alloc, 0);
3787         atomic_set(&n_rcu_torture_alloc_fail, 0);
3788         atomic_set(&n_rcu_torture_free, 0);
3789         atomic_set(&n_rcu_torture_mberror, 0);
3790         atomic_set(&n_rcu_torture_mbchk_fail, 0);
3791         atomic_set(&n_rcu_torture_mbchk_tries, 0);
3792         atomic_set(&n_rcu_torture_error, 0);
3793         n_rcu_torture_barrier_error = 0;
3794         n_rcu_torture_boost_ktrerror = 0;
3795         n_rcu_torture_boost_failure = 0;
3796         n_rcu_torture_boosts = 0;
3797         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
3798                 atomic_set(&rcu_torture_wcount[i], 0);
3799         for_each_possible_cpu(cpu) {
3800                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
3801                         per_cpu(rcu_torture_count, cpu)[i] = 0;
3802                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
3803                 }
3804         }
3805         err_segs_recorded = 0;
3806         rt_read_nsegs = 0;
3807
3808         /* Start up the kthreads. */
3809
3810         rcu_torture_write_types();
3811         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
3812                                           writer_task);
3813         if (torture_init_error(firsterr))
3814                 goto unwind;
3815         if (nfakewriters > 0) {
3816                 fakewriter_tasks = kcalloc(nfakewriters,
3817                                            sizeof(fakewriter_tasks[0]),
3818                                            GFP_KERNEL);
3819                 if (fakewriter_tasks == NULL) {
3820                         TOROUT_ERRSTRING("out of memory");
3821                         firsterr = -ENOMEM;
3822                         goto unwind;
3823                 }
3824         }
3825         for (i = 0; i < nfakewriters; i++) {
3826                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
3827                                                   NULL, fakewriter_tasks[i]);
3828                 if (torture_init_error(firsterr))
3829                         goto unwind;
3830         }
3831         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
3832                                GFP_KERNEL);
3833         rcu_torture_reader_mbchk = kcalloc(nrealreaders, sizeof(*rcu_torture_reader_mbchk),
3834                                            GFP_KERNEL);
3835         if (!reader_tasks || !rcu_torture_reader_mbchk) {
3836                 TOROUT_ERRSTRING("out of memory");
3837                 firsterr = -ENOMEM;
3838                 goto unwind;
3839         }
3840         for (i = 0; i < nrealreaders; i++) {
3841                 rcu_torture_reader_mbchk[i].rtc_chkrdr = -1;
3842                 firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
3843                                                   reader_tasks[i]);
3844                 if (torture_init_error(firsterr))
3845                         goto unwind;
3846         }
3847         nrealnocbers = nocbs_nthreads;
3848         if (WARN_ON(nrealnocbers < 0))
3849                 nrealnocbers = 1;
3850         if (WARN_ON(nocbs_toggle < 0))
3851                 nocbs_toggle = HZ;
3852         if (nrealnocbers > 0) {
3853                 nocb_tasks = kcalloc(nrealnocbers, sizeof(nocb_tasks[0]), GFP_KERNEL);
3854                 if (nocb_tasks == NULL) {
3855                         TOROUT_ERRSTRING("out of memory");
3856                         firsterr = -ENOMEM;
3857                         goto unwind;
3858                 }
3859         } else {
3860                 nocb_tasks = NULL;
3861         }
3862         for (i = 0; i < nrealnocbers; i++) {
3863                 firsterr = torture_create_kthread(rcu_nocb_toggle, NULL, nocb_tasks[i]);
3864                 if (torture_init_error(firsterr))
3865                         goto unwind;
3866         }
3867         if (stat_interval > 0) {
3868                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
3869                                                   stats_task);
3870                 if (torture_init_error(firsterr))
3871                         goto unwind;
3872         }
3873         if (test_no_idle_hz && shuffle_interval > 0) {
3874                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
3875                 if (torture_init_error(firsterr))
3876                         goto unwind;
3877         }
3878         if (stutter < 0)
3879                 stutter = 0;
3880         if (stutter) {
3881                 int t;
3882
3883                 t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
3884                 firsterr = torture_stutter_init(stutter * HZ, t);
3885                 if (torture_init_error(firsterr))
3886                         goto unwind;
3887         }
3888         if (fqs_duration < 0)
3889                 fqs_duration = 0;
3890         if (fqs_holdoff < 0)
3891                 fqs_holdoff = 0;
3892         if (fqs_duration && fqs_holdoff) {
3893                 /* Create the fqs thread */
3894                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
3895                                                   fqs_task);
3896                 if (torture_init_error(firsterr))
3897                         goto unwind;
3898         }
3899         if (test_boost_interval < 1)
3900                 test_boost_interval = 1;
3901         if (test_boost_duration < 2)
3902                 test_boost_duration = 2;
3903         if (rcu_torture_can_boost()) {
3904
3905                 boost_starttime = jiffies + test_boost_interval * HZ;
3906
3907                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
3908                                              rcutorture_booster_init,
3909                                              rcutorture_booster_cleanup);
3910                 rcutor_hp = firsterr;
3911                 if (torture_init_error(firsterr))
3912                         goto unwind;
3913         }
3914         shutdown_jiffies = jiffies + shutdown_secs * HZ;
3915         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
3916         if (torture_init_error(firsterr))
3917                 goto unwind;
3918         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
3919                                       rcutorture_sync);
3920         if (torture_init_error(firsterr))
3921                 goto unwind;
3922         firsterr = rcu_torture_stall_init();
3923         if (torture_init_error(firsterr))
3924                 goto unwind;
3925         firsterr = rcu_torture_fwd_prog_init();
3926         if (torture_init_error(firsterr))
3927                 goto unwind;
3928         firsterr = rcu_torture_barrier_init();
3929         if (torture_init_error(firsterr))
3930                 goto unwind;
3931         firsterr = rcu_torture_read_exit_init();
3932         if (torture_init_error(firsterr))
3933                 goto unwind;
3934         if (object_debug)
3935                 rcu_test_debug_objects();
3936         torture_init_end();
3937         if (cur_ops->gp_slow_register && !WARN_ON_ONCE(!cur_ops->gp_slow_unregister))
3938                 cur_ops->gp_slow_register(&rcu_fwd_cb_nodelay);
3939         return 0;
3940
3941 unwind:
3942         torture_init_end();
3943         rcu_torture_cleanup();
3944         if (shutdown_secs) {
3945                 WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
3946                 kernel_power_off();
3947         }
3948         return firsterr;
3949 }
3950
3951 module_init(rcu_torture_init);
3952 module_exit(rcu_torture_cleanup);