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