kernel/trace/trace_sched_wakeup.c

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