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