kernel/trace/trace_sched_wakeup.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * trace task wakeup timings
   4  *
   5  * Copyright (C) 2007-2008 Steven Rostedt <[email protected]>
   6  * Copyright (C) 2008 Ingo Molnar <[email protected]>
   7  *
   8  * Based on code from the latency_tracer, that is:
   9  *
  10  *  Copyright (C) 2004-2006 Ingo Molnar
  11  *  Copyright (C) 2004 Nadia Yvette Chambers
  12  */
  13 #include <linux/module.h>
  14 #include <linux/kallsyms.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/ftrace.h>
  17 #include <linux/sched/rt.h>
  18 #include <linux/sched/deadline.h>
  19 #include <trace/events/sched.h>
  20 #include "trace.h"
  21
  22 static struct trace_array       *wakeup_trace;
  23 static int __read_mostly        tracer_enabled;
  24
  25 static struct task_struct       *wakeup_task;
  26 static int                      wakeup_cpu;
  27 static int                      wakeup_current_cpu;
  28 static unsigned                 wakeup_prio = -1;
  29 static int                      wakeup_rt;
  30 static int                      wakeup_dl;
  31 static int                      tracing_dl = 0;
  32
  33 static arch_spinlock_t wakeup_lock =
  34         (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  35
  36 static void wakeup_reset(struct trace_array *tr);
  37 static void __wakeup_reset(struct trace_array *tr);
  38 static int start_func_tracer(struct trace_array *tr, int graph);
  39 static void stop_func_tracer(struct trace_array *tr, int graph);
  40
  41 static int save_flags;
  42
  43 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  44 # define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
  45 #else
  46 # define is_graph(tr) false
  47 #endif
  48
  49 #ifdef CONFIG_FUNCTION_TRACER
  50
  51 static bool function_enabled;
  52
  53 /*
  54  * Prologue for the wakeup function tracers.
  55  *
  56  * Returns 1 if it is OK to continue, and preemption
  57  *            is disabled and data->disabled is incremented.
  58  *         0 if the trace is to be ignored, and preemption
  59  *            is not disabled and data->disabled is
  60  *            kept the same.
  61  *
  62  * Note, this function is also used outside this ifdef but
  63  *  inside the #ifdef of the function graph tracer below.
  64  *  This is OK, since the function graph tracer is
  65  *  dependent on the function tracer.
  66  */
  67 static int
  68 func_prolog_preempt_disable(struct trace_array *tr,
  69                             struct trace_array_cpu **data,
  70                             int *pc)
  71 {
  72         long disabled;
  73         int cpu;
  74
  75         if (likely(!wakeup_task))
  76                 return 0;
  77
  78         *pc = preempt_count();
  79         preempt_disable_notrace();
  80
  81         cpu = raw_smp_processor_id();
  82         if (cpu != wakeup_current_cpu)
  83                 goto out_enable;
  84
  85         *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
  86         disabled = atomic_inc_return(&(*data)->disabled);
  87         if (unlikely(disabled != 1))
  88                 goto out;
  89
  90         return 1;
  91
  92 out:
  93         atomic_dec(&(*data)->disabled);
  94
  95 out_enable:
  96         preempt_enable_notrace();
  97         return 0;
  98 }
  99
 100 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 101
 102 static int wakeup_display_graph(struct trace_array *tr, int set)
 103 {
 104         if (!(is_graph(tr) ^ set))
 105                 return 0;
 106
 107         stop_func_tracer(tr, !set);
 108
 109         wakeup_reset(wakeup_trace);
 110         tr->max_latency = 0;
 111
 112         return start_func_tracer(tr, set);
 113 }
 114
 115 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
 116 {
 117         struct trace_array *tr = wakeup_trace;
 118         struct trace_array_cpu *data;
 119         unsigned long flags;
 120         int pc, ret = 0;
 121
 122         if (ftrace_graph_ignore_func(trace))
 123                 return 0;
 124         /*
 125          * Do not trace a function if it's filtered by set_graph_notrace.
 126          * Make the index of ret stack negative to indicate that it should
 127          * ignore further functions.  But it needs its own ret stack entry
 128          * to recover the original index in order to continue tracing after
 129          * returning from the function.
 130          */
 131         if (ftrace_graph_notrace_addr(trace->func))
 132                 return 1;
 133
 134         if (!func_prolog_preempt_disable(tr, &data, &pc))
 135                 return 0;
 136
 137         local_save_flags(flags);
 138         ret = __trace_graph_entry(tr, trace, flags, pc);
 139         atomic_dec(&data->disabled);
 140         preempt_enable_notrace();
 141
 142         return ret;
 143 }
 144
 145 static void wakeup_graph_return(struct ftrace_graph_ret *trace)
 146 {
 147         struct trace_array *tr = wakeup_trace;
 148         struct trace_array_cpu *data;
 149         unsigned long flags;
 150         int pc;
 151
 152         ftrace_graph_addr_finish(trace);
 153
 154         if (!func_prolog_preempt_disable(tr, &data, &pc))
 155                 return;
 156
 157         local_save_flags(flags);
 158         __trace_graph_return(tr, trace, flags, pc);
 159         atomic_dec(&data->disabled);
 160
 161         preempt_enable_notrace();
 162         return;
 163 }
 164
 165 static struct fgraph_ops fgraph_wakeup_ops = {
 166         .entryfunc = &wakeup_graph_entry,
 167         .retfunc = &wakeup_graph_return,
 168 };
 169
 170 static void wakeup_trace_open(struct trace_iterator *iter)
 171 {
 172         if (is_graph(iter->tr))
 173                 graph_trace_open(iter);
 174 }
 175
 176 static void wakeup_trace_close(struct trace_iterator *iter)
 177 {
 178         if (iter->private)
 179                 graph_trace_close(iter);
 180 }
 181
 182 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
 183                             TRACE_GRAPH_PRINT_ABS_TIME | \
 184                             TRACE_GRAPH_PRINT_DURATION)
 185
 186 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 187 {
 188         /*
 189          * In graph mode call the graph tracer output function,
 190          * otherwise go with the TRACE_FN event handler
 191          */
 192         if (is_graph(iter->tr))
 193                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
 194
 195         return TRACE_TYPE_UNHANDLED;
 196 }
 197
 198 static void wakeup_print_header(struct seq_file *s)
 199 {
 200         if (is_graph(wakeup_trace))
 201                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
 202         else
 203                 trace_default_header(s);
 204 }
 205 #endif /* else CONFIG_FUNCTION_GRAPH_TRACER */
 206
 207 /*
 208  * wakeup uses its own tracer function to keep the overhead down:
 209  */
 210 static void
 211 wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
 212                    struct ftrace_ops *op, struct pt_regs *pt_regs)
 213 {
 214         struct trace_array *tr = wakeup_trace;
 215         struct trace_array_cpu *data;
 216         unsigned long flags;
 217         int pc;
 218
 219         if (!func_prolog_preempt_disable(tr, &data, &pc))
 220                 return;
 221
 222         local_irq_save(flags);
 223         trace_function(tr, ip, parent_ip, flags, pc);
 224         local_irq_restore(flags);
 225
 226         atomic_dec(&data->disabled);
 227         preempt_enable_notrace();
 228 }
 229
 230 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
 231 {
 232         int ret;
 233
 234         /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
 235         if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
 236                 return 0;
 237
 238         if (graph)
 239                 ret = register_ftrace_graph(&fgraph_wakeup_ops);
 240         else
 241                 ret = register_ftrace_function(tr->ops);
 242
 243         if (!ret)
 244                 function_enabled = true;
 245
 246         return ret;
 247 }
 248
 249 static void unregister_wakeup_function(struct trace_array *tr, int graph)
 250 {
 251         if (!function_enabled)
 252                 return;
 253
 254         if (graph)
 255                 unregister_ftrace_graph(&fgraph_wakeup_ops);
 256         else
 257                 unregister_ftrace_function(tr->ops);
 258
 259         function_enabled = false;
 260 }
 261
 262 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
 263 {
 264         if (!(mask & TRACE_ITER_FUNCTION))
 265                 return 0;
 266
 267         if (set)
 268                 register_wakeup_function(tr, is_graph(tr), 1);
 269         else
 270                 unregister_wakeup_function(tr, is_graph(tr));
 271         return 1;
 272 }
 273 #else /* CONFIG_FUNCTION_TRACER */
 274 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
 275 {
 276         return 0;
 277 }
 278 static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
 279 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
 280 {
 281         return 0;
 282 }
 283 #endif /* else CONFIG_FUNCTION_TRACER */
 284
 285 #ifndef CONFIG_FUNCTION_GRAPH_TRACER
 286 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 287 {
 288         return TRACE_TYPE_UNHANDLED;
 289 }
 290
 291 static void wakeup_trace_open(struct trace_iterator *iter) { }
 292 static void wakeup_trace_close(struct trace_iterator *iter) { }
 293
 294 static void wakeup_print_header(struct seq_file *s)
 295 {
 296         trace_default_header(s);
 297 }
 298 #endif /* !CONFIG_FUNCTION_GRAPH_TRACER */
 299
 300 static void
 301 __trace_function(struct trace_array *tr,
 302                  unsigned long ip, unsigned long parent_ip,
 303                  unsigned long flags, int pc)
 304 {
 305         if (is_graph(tr))
 306                 trace_graph_function(tr, ip, parent_ip, flags, pc);
 307         else
 308                 trace_function(tr, ip, parent_ip, flags, pc);
 309 }
 310
 311 static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
 312 {
 313         struct tracer *tracer = tr->current_trace;
 314
 315         if (wakeup_function_set(tr, mask, set))
 316                 return 0;
 317
 318 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 319         if (mask & TRACE_ITER_DISPLAY_GRAPH)
 320                 return wakeup_display_graph(tr, set);
 321 #endif
 322
 323         return trace_keep_overwrite(tracer, mask, set);
 324 }
 325
 326 static int start_func_tracer(struct trace_array *tr, int graph)
 327 {
 328         int ret;
 329
 330         ret = register_wakeup_function(tr, graph, 0);
 331
 332         if (!ret && tracing_is_enabled())
 333                 tracer_enabled = 1;
 334         else
 335                 tracer_enabled = 0;
 336
 337         return ret;
 338 }
 339
 340 static void stop_func_tracer(struct trace_array *tr, int graph)
 341 {
 342         tracer_enabled = 0;
 343
 344         unregister_wakeup_function(tr, graph);
 345 }
 346
 347 /*
 348  * Should this new latency be reported/recorded?
 349  */
 350 static bool report_latency(struct trace_array *tr, u64 delta)
 351 {
 352         if (tracing_thresh) {
 353                 if (delta < tracing_thresh)
 354                         return false;
 355         } else {
 356                 if (delta <= tr->max_latency)
 357                         return false;
 358         }
 359         return true;
 360 }
 361
 362 static void
 363 probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
 364 {
 365         if (task != wakeup_task)
 366                 return;
 367
 368         wakeup_current_cpu = cpu;
 369 }
 370
 371 static void
 372 tracing_sched_switch_trace(struct trace_array *tr,
 373                            struct task_struct *prev,
 374                            struct task_struct *next,
 375                            unsigned long flags, int pc)
 376 {
 377         struct trace_event_call *call = &event_context_switch;
 378         struct ring_buffer *buffer = tr->trace_buffer.buffer;
 379         struct ring_buffer_event *event;
 380         struct ctx_switch_entry *entry;
 381
 382         event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
 383                                           sizeof(*entry), flags, pc);
 384         if (!event)
 385                 return;
 386         entry   = ring_buffer_event_data(event);
 387         entry->prev_pid                 = prev->pid;
 388         entry->prev_prio                = prev->prio;
 389         entry->prev_state               = task_state_index(prev);
 390         entry->next_pid                 = next->pid;
 391         entry->next_prio                = next->prio;
 392         entry->next_state               = task_state_index(next);
 393         entry->next_cpu = task_cpu(next);
 394
 395         if (!call_filter_check_discard(call, entry, buffer, event))
 396                 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
 397 }
 398
 399 static void
 400 tracing_sched_wakeup_trace(struct trace_array *tr,
 401                            struct task_struct *wakee,
 402                            struct task_struct *curr,
 403                            unsigned long flags, int pc)
 404 {
 405         struct trace_event_call *call = &event_wakeup;
 406         struct ring_buffer_event *event;
 407         struct ctx_switch_entry *entry;
 408         struct ring_buffer *buffer = tr->trace_buffer.buffer;
 409
 410         event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
 411                                           sizeof(*entry), flags, pc);
 412         if (!event)
 413                 return;
 414         entry   = ring_buffer_event_data(event);
 415         entry->prev_pid                 = curr->pid;
 416         entry->prev_prio                = curr->prio;
 417         entry->prev_state               = task_state_index(curr);
 418         entry->next_pid                 = wakee->pid;
 419         entry->next_prio                = wakee->prio;
 420         entry->next_state               = task_state_index(wakee);
 421         entry->next_cpu                 = task_cpu(wakee);
 422
 423         if (!call_filter_check_discard(call, entry, buffer, event))
 424                 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
 425 }
 426
 427 static void notrace
 428 probe_wakeup_sched_switch(void *ignore, bool preempt,
 429                           struct task_struct *prev, struct task_struct *next)
 430 {
 431         struct trace_array_cpu *data;
 432         u64 T0, T1, delta;
 433         unsigned long flags;
 434         long disabled;
 435         int cpu;
 436         int pc;
 437
 438         tracing_record_cmdline(prev);
 439
 440         if (unlikely(!tracer_enabled))
 441                 return;
 442
 443         /*
 444          * When we start a new trace, we set wakeup_task to NULL
 445          * and then set tracer_enabled = 1. We want to make sure
 446          * that another CPU does not see the tracer_enabled = 1
 447          * and the wakeup_task with an older task, that might
 448          * actually be the same as next.
 449          */
 450         smp_rmb();
 451
 452         if (next != wakeup_task)
 453                 return;
 454
 455         pc = preempt_count();
 456
 457         /* disable local data, not wakeup_cpu data */
 458         cpu = raw_smp_processor_id();
 459         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 460         if (likely(disabled != 1))
 461                 goto out;
 462
 463         local_irq_save(flags);
 464         arch_spin_lock(&wakeup_lock);
 465
 466         /* We could race with grabbing wakeup_lock */
 467         if (unlikely(!tracer_enabled || next != wakeup_task))
 468                 goto out_unlock;
 469
 470         /* The task we are waiting for is waking up */
 471         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 472
 473         __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
 474         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 475
 476         T0 = data->preempt_timestamp;
 477         T1 = ftrace_now(cpu);
 478         delta = T1-T0;
 479
 480         if (!report_latency(wakeup_trace, delta))
 481                 goto out_unlock;
 482
 483         if (likely(!is_tracing_stopped())) {
 484                 wakeup_trace->max_latency = delta;
 485                 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
 486         }
 487
 488 out_unlock:
 489         __wakeup_reset(wakeup_trace);
 490         arch_spin_unlock(&wakeup_lock);
 491         local_irq_restore(flags);
 492 out:
 493         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 494 }
 495
 496 static void __wakeup_reset(struct trace_array *tr)
 497 {
 498         wakeup_cpu = -1;
 499         wakeup_prio = -1;
 500         tracing_dl = 0;
 501
 502         if (wakeup_task)
 503                 put_task_struct(wakeup_task);
 504
 505         wakeup_task = NULL;
 506 }
 507
 508 static void wakeup_reset(struct trace_array *tr)
 509 {
 510         unsigned long flags;
 511
 512         tracing_reset_online_cpus(&tr->trace_buffer);
 513
 514         local_irq_save(flags);
 515         arch_spin_lock(&wakeup_lock);
 516         __wakeup_reset(tr);
 517         arch_spin_unlock(&wakeup_lock);
 518         local_irq_restore(flags);
 519 }
 520
 521 static void
 522 probe_wakeup(void *ignore, struct task_struct *p)
 523 {
 524         struct trace_array_cpu *data;
 525         int cpu = smp_processor_id();
 526         unsigned long flags;
 527         long disabled;
 528         int pc;
 529
 530         if (likely(!tracer_enabled))
 531                 return;
 532
 533         tracing_record_cmdline(p);
 534         tracing_record_cmdline(current);
 535
 536         /*
 537          * Semantic is like this:
 538          *  - wakeup tracer handles all tasks in the system, independently
 539          *    from their scheduling class;
 540          *  - wakeup_rt tracer handles tasks belonging to sched_dl and
 541          *    sched_rt class;
 542          *  - wakeup_dl handles tasks belonging to sched_dl class only.
 543          */
 544         if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
 545             (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
 546             (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
 547                 return;
 548
 549         pc = preempt_count();
 550         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 551         if (unlikely(disabled != 1))
 552                 goto out;
 553
 554         /* interrupts should be off from try_to_wake_up */
 555         arch_spin_lock(&wakeup_lock);
 556
 557         /* check for races. */
 558         if (!tracer_enabled || tracing_dl ||
 559             (!dl_task(p) && p->prio >= wakeup_prio))
 560                 goto out_locked;
 561
 562         /* reset the trace */
 563         __wakeup_reset(wakeup_trace);
 564
 565         wakeup_cpu = task_cpu(p);
 566         wakeup_current_cpu = wakeup_cpu;
 567         wakeup_prio = p->prio;
 568
 569         /*
 570          * Once you start tracing a -deadline task, don't bother tracing
 571          * another task until the first one wakes up.
 572          */
 573         if (dl_task(p))
 574                 tracing_dl = 1;
 575         else
 576                 tracing_dl = 0;
 577
 578         wakeup_task = p;
 579         get_task_struct(wakeup_task);
 580
 581         local_save_flags(flags);
 582
 583         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 584         data->preempt_timestamp = ftrace_now(cpu);
 585         tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
 586
 587         /*
 588          * We must be careful in using CALLER_ADDR2. But since wake_up
 589          * is not called by an assembly function  (where as schedule is)
 590          * it should be safe to use it here.
 591          */
 592         __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
 593
 594 out_locked:
 595         arch_spin_unlock(&wakeup_lock);
 596 out:
 597         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 598 }
 599
 600 static void start_wakeup_tracer(struct trace_array *tr)
 601 {
 602         int ret;
 603
 604         ret = register_trace_sched_wakeup(probe_wakeup, NULL);
 605         if (ret) {
 606                 pr_info("wakeup trace: Couldn't activate tracepoint"
 607                         " probe to kernel_sched_wakeup\n");
 608                 return;
 609         }
 610
 611         ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
 612         if (ret) {
 613                 pr_info("wakeup trace: Couldn't activate tracepoint"
 614                         " probe to kernel_sched_wakeup_new\n");
 615                 goto fail_deprobe;
 616         }
 617
 618         ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 619         if (ret) {
 620                 pr_info("sched trace: Couldn't activate tracepoint"
 621                         " probe to kernel_sched_switch\n");
 622                 goto fail_deprobe_wake_new;
 623         }
 624
 625         ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 626         if (ret) {
 627                 pr_info("wakeup trace: Couldn't activate tracepoint"
 628                         " probe to kernel_sched_migrate_task\n");
 629                 return;
 630         }
 631
 632         wakeup_reset(tr);
 633
 634         /*
 635          * Don't let the tracer_enabled = 1 show up before
 636          * the wakeup_task is reset. This may be overkill since
 637          * wakeup_reset does a spin_unlock after setting the
 638          * wakeup_task to NULL, but I want to be safe.
 639          * This is a slow path anyway.
 640          */
 641         smp_wmb();
 642
 643         if (start_func_tracer(tr, is_graph(tr)))
 644                 printk(KERN_ERR "failed to start wakeup tracer\n");
 645
 646         return;
 647 fail_deprobe_wake_new:
 648         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 649 fail_deprobe:
 650         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 651 }
 652
 653 static void stop_wakeup_tracer(struct trace_array *tr)
 654 {
 655         tracer_enabled = 0;
 656         stop_func_tracer(tr, is_graph(tr));
 657         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 658         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 659         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 660         unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 661 }
 662
 663 static bool wakeup_busy;
 664
 665 static int __wakeup_tracer_init(struct trace_array *tr)
 666 {
 667         save_flags = tr->trace_flags;
 668
 669         /* non overwrite screws up the latency tracers */
 670         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
 671         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
 672
 673         tr->max_latency = 0;
 674         wakeup_trace = tr;
 675         ftrace_init_array_ops(tr, wakeup_tracer_call);
 676         start_wakeup_tracer(tr);
 677
 678         wakeup_busy = true;
 679         return 0;
 680 }
 681
 682 static int wakeup_tracer_init(struct trace_array *tr)
 683 {
 684         if (wakeup_busy)
 685                 return -EBUSY;
 686
 687         wakeup_dl = 0;
 688         wakeup_rt = 0;
 689         return __wakeup_tracer_init(tr);
 690 }
 691
 692 static int wakeup_rt_tracer_init(struct trace_array *tr)
 693 {
 694         if (wakeup_busy)
 695                 return -EBUSY;
 696
 697         wakeup_dl = 0;
 698         wakeup_rt = 1;
 699         return __wakeup_tracer_init(tr);
 700 }
 701
 702 static int wakeup_dl_tracer_init(struct trace_array *tr)
 703 {
 704         if (wakeup_busy)
 705                 return -EBUSY;
 706
 707         wakeup_dl = 1;
 708         wakeup_rt = 0;
 709         return __wakeup_tracer_init(tr);
 710 }
 711
 712 static void wakeup_tracer_reset(struct trace_array *tr)
 713 {
 714         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
 715         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
 716
 717         stop_wakeup_tracer(tr);
 718         /* make sure we put back any tasks we are tracing */
 719         wakeup_reset(tr);
 720
 721         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
 722         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
 723         ftrace_reset_array_ops(tr);
 724         wakeup_busy = false;
 725 }
 726
 727 static void wakeup_tracer_start(struct trace_array *tr)
 728 {
 729         wakeup_reset(tr);
 730         tracer_enabled = 1;
 731 }
 732
 733 static void wakeup_tracer_stop(struct trace_array *tr)
 734 {
 735         tracer_enabled = 0;
 736 }
 737
 738 static struct tracer wakeup_tracer __read_mostly =
 739 {
 740         .name           = "wakeup",
 741         .init           = wakeup_tracer_init,
 742         .reset          = wakeup_tracer_reset,
 743         .start          = wakeup_tracer_start,
 744         .stop           = wakeup_tracer_stop,
 745         .print_max      = true,
 746         .print_header   = wakeup_print_header,
 747         .print_line     = wakeup_print_line,
 748         .flag_changed   = wakeup_flag_changed,
 749 #ifdef CONFIG_FTRACE_SELFTEST
 750         .selftest    = trace_selftest_startup_wakeup,
 751 #endif
 752         .open           = wakeup_trace_open,
 753         .close          = wakeup_trace_close,
 754         .allow_instances = true,
 755         .use_max_tr     = true,
 756 };
 757
 758 static struct tracer wakeup_rt_tracer __read_mostly =
 759 {
 760         .name           = "wakeup_rt",
 761         .init           = wakeup_rt_tracer_init,
 762         .reset          = wakeup_tracer_reset,
 763         .start          = wakeup_tracer_start,
 764         .stop           = wakeup_tracer_stop,
 765         .print_max      = true,
 766         .print_header   = wakeup_print_header,
 767         .print_line     = wakeup_print_line,
 768         .flag_changed   = wakeup_flag_changed,
 769 #ifdef CONFIG_FTRACE_SELFTEST
 770         .selftest    = trace_selftest_startup_wakeup,
 771 #endif
 772         .open           = wakeup_trace_open,
 773         .close          = wakeup_trace_close,
 774         .allow_instances = true,
 775         .use_max_tr     = true,
 776 };
 777
 778 static struct tracer wakeup_dl_tracer __read_mostly =
 779 {
 780         .name           = "wakeup_dl",
 781         .init           = wakeup_dl_tracer_init,
 782         .reset          = wakeup_tracer_reset,
 783         .start          = wakeup_tracer_start,
 784         .stop           = wakeup_tracer_stop,
 785         .print_max      = true,
 786         .print_header   = wakeup_print_header,
 787         .print_line     = wakeup_print_line,
 788         .flag_changed   = wakeup_flag_changed,
 789 #ifdef CONFIG_FTRACE_SELFTEST
 790         .selftest    = trace_selftest_startup_wakeup,
 791 #endif
 792         .open           = wakeup_trace_open,
 793         .close          = wakeup_trace_close,
 794         .allow_instances = true,
 795         .use_max_tr     = true,
 796 };
 797
 798 __init static int init_wakeup_tracer(void)
 799 {
 800         int ret;
 801
 802         ret = register_tracer(&wakeup_tracer);
 803         if (ret)
 804                 return ret;
 805
 806         ret = register_tracer(&wakeup_rt_tracer);
 807         if (ret)
 808                 return ret;
 809
 810         ret = register_tracer(&wakeup_dl_tracer);
 811         if (ret)
 812                 return ret;
 813
 814         return 0;
 815 }
 816 core_initcall(init_wakeup_tracer);