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