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 tracer *tracer, u32 mask, int set)
 183 {
 184         if (mask & TRACE_ITER_FUNCTION)
 185                 wakeup_function_set(set);
 186
 187         return trace_keep_overwrite(tracer, mask, set);
 188 }
 189
 190 static int start_func_tracer(int graph)
 191 {
 192         int ret;
 193
 194         ret = register_wakeup_function(graph, 0);
 195
 196         if (!ret && tracing_is_enabled())
 197                 tracer_enabled = 1;
 198         else
 199                 tracer_enabled = 0;
 200
 201         return ret;
 202 }
 203
 204 static void stop_func_tracer(int graph)
 205 {
 206         tracer_enabled = 0;
 207
 208         unregister_wakeup_function(graph);
 209 }
 210
 211 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 212 static int
 213 wakeup_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 214 {
 215
 216         if (!(bit & TRACE_DISPLAY_GRAPH))
 217                 return -EINVAL;
 218
 219         if (!(is_graph() ^ set))
 220                 return 0;
 221
 222         stop_func_tracer(!set);
 223
 224         wakeup_reset(wakeup_trace);
 225         tracing_max_latency = 0;
 226
 227         return start_func_tracer(set);
 228 }
 229
 230 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
 231 {
 232         struct trace_array *tr = wakeup_trace;
 233         struct trace_array_cpu *data;
 234         unsigned long flags;
 235         int pc, ret = 0;
 236
 237         if (!func_prolog_preempt_disable(tr, &data, &pc))
 238                 return 0;
 239
 240         local_save_flags(flags);
 241         ret = __trace_graph_entry(tr, trace, flags, pc);
 242         atomic_dec(&data->disabled);
 243         preempt_enable_notrace();
 244
 245         return ret;
 246 }
 247
 248 static void wakeup_graph_return(struct ftrace_graph_ret *trace)
 249 {
 250         struct trace_array *tr = wakeup_trace;
 251         struct trace_array_cpu *data;
 252         unsigned long flags;
 253         int pc;
 254
 255         if (!func_prolog_preempt_disable(tr, &data, &pc))
 256                 return;
 257
 258         local_save_flags(flags);
 259         __trace_graph_return(tr, trace, flags, pc);
 260         atomic_dec(&data->disabled);
 261
 262         preempt_enable_notrace();
 263         return;
 264 }
 265
 266 static void wakeup_trace_open(struct trace_iterator *iter)
 267 {
 268         if (is_graph())
 269                 graph_trace_open(iter);
 270 }
 271
 272 static void wakeup_trace_close(struct trace_iterator *iter)
 273 {
 274         if (iter->private)
 275                 graph_trace_close(iter);
 276 }
 277
 278 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
 279                             TRACE_GRAPH_PRINT_ABS_TIME | \
 280                             TRACE_GRAPH_PRINT_DURATION)
 281
 282 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 283 {
 284         /*
 285          * In graph mode call the graph tracer output function,
 286          * otherwise go with the TRACE_FN event handler
 287          */
 288         if (is_graph())
 289                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
 290
 291         return TRACE_TYPE_UNHANDLED;
 292 }
 293
 294 static void wakeup_print_header(struct seq_file *s)
 295 {
 296         if (is_graph())
 297                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
 298         else
 299                 trace_default_header(s);
 300 }
 301
 302 static void
 303 __trace_function(struct trace_array *tr,
 304                  unsigned long ip, unsigned long parent_ip,
 305                  unsigned long flags, int pc)
 306 {
 307         if (is_graph())
 308                 trace_graph_function(tr, ip, parent_ip, flags, pc);
 309         else
 310                 trace_function(tr, ip, parent_ip, flags, pc);
 311 }
 312 #else
 313 #define __trace_function trace_function
 314
 315 static int
 316 wakeup_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 317 {
 318         return -EINVAL;
 319 }
 320
 321 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
 322 {
 323         return -1;
 324 }
 325
 326 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 327 {
 328         return TRACE_TYPE_UNHANDLED;
 329 }
 330
 331 static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
 332 static void wakeup_trace_open(struct trace_iterator *iter) { }
 333 static void wakeup_trace_close(struct trace_iterator *iter) { }
 334
 335 #ifdef CONFIG_FUNCTION_TRACER
 336 static void wakeup_print_header(struct seq_file *s)
 337 {
 338         trace_default_header(s);
 339 }
 340 #else
 341 static void wakeup_print_header(struct seq_file *s)
 342 {
 343         trace_latency_header(s);
 344 }
 345 #endif /* CONFIG_FUNCTION_TRACER */
 346 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 347
 348 /*
 349  * Should this new latency be reported/recorded?
 350  */
 351 static int report_latency(cycle_t delta)
 352 {
 353         if (tracing_thresh) {
 354                 if (delta < tracing_thresh)
 355                         return 0;
 356         } else {
 357                 if (delta <= tracing_max_latency)
 358                         return 0;
 359         }
 360         return 1;
 361 }
 362
 363 static void
 364 probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
 365 {
 366         if (task != wakeup_task)
 367                 return;
 368
 369         wakeup_current_cpu = cpu;
 370 }
 371
 372 static void notrace
 373 probe_wakeup_sched_switch(void *ignore,
 374                           struct task_struct *prev, struct task_struct *next)
 375 {
 376         struct trace_array_cpu *data;
 377         cycle_t T0, T1, delta;
 378         unsigned long flags;
 379         long disabled;
 380         int cpu;
 381         int pc;
 382
 383         tracing_record_cmdline(prev);
 384
 385         if (unlikely(!tracer_enabled))
 386                 return;
 387
 388         /*
 389          * When we start a new trace, we set wakeup_task to NULL
 390          * and then set tracer_enabled = 1. We want to make sure
 391          * that another CPU does not see the tracer_enabled = 1
 392          * and the wakeup_task with an older task, that might
 393          * actually be the same as next.
 394          */
 395         smp_rmb();
 396
 397         if (next != wakeup_task)
 398                 return;
 399
 400         pc = preempt_count();
 401
 402         /* disable local data, not wakeup_cpu data */
 403         cpu = raw_smp_processor_id();
 404         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 405         if (likely(disabled != 1))
 406                 goto out;
 407
 408         local_irq_save(flags);
 409         arch_spin_lock(&wakeup_lock);
 410
 411         /* We could race with grabbing wakeup_lock */
 412         if (unlikely(!tracer_enabled || next != wakeup_task))
 413                 goto out_unlock;
 414
 415         /* The task we are waiting for is waking up */
 416         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 417
 418         __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
 419         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 420
 421         T0 = data->preempt_timestamp;
 422         T1 = ftrace_now(cpu);
 423         delta = T1-T0;
 424
 425         if (!report_latency(delta))
 426                 goto out_unlock;
 427
 428         if (likely(!is_tracing_stopped())) {
 429                 tracing_max_latency = delta;
 430                 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
 431         }
 432
 433 out_unlock:
 434         __wakeup_reset(wakeup_trace);
 435         arch_spin_unlock(&wakeup_lock);
 436         local_irq_restore(flags);
 437 out:
 438         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 439 }
 440
 441 static void __wakeup_reset(struct trace_array *tr)
 442 {
 443         wakeup_cpu = -1;
 444         wakeup_prio = -1;
 445         tracing_dl = 0;
 446
 447         if (wakeup_task)
 448                 put_task_struct(wakeup_task);
 449
 450         wakeup_task = NULL;
 451 }
 452
 453 static void wakeup_reset(struct trace_array *tr)
 454 {
 455         unsigned long flags;
 456
 457         tracing_reset_online_cpus(&tr->trace_buffer);
 458
 459         local_irq_save(flags);
 460         arch_spin_lock(&wakeup_lock);
 461         __wakeup_reset(tr);
 462         arch_spin_unlock(&wakeup_lock);
 463         local_irq_restore(flags);
 464 }
 465
 466 static void
 467 probe_wakeup(void *ignore, struct task_struct *p, int success)
 468 {
 469         struct trace_array_cpu *data;
 470         int cpu = smp_processor_id();
 471         unsigned long flags;
 472         long disabled;
 473         int pc;
 474
 475         if (likely(!tracer_enabled))
 476                 return;
 477
 478         tracing_record_cmdline(p);
 479         tracing_record_cmdline(current);
 480
 481         /*
 482          * Semantic is like this:
 483          *  - wakeup tracer handles all tasks in the system, independently
 484          *    from their scheduling class;
 485          *  - wakeup_rt tracer handles tasks belonging to sched_dl and
 486          *    sched_rt class;
 487          *  - wakeup_dl handles tasks belonging to sched_dl class only.
 488          */
 489         if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
 490             (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
 491             (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
 492                 return;
 493
 494         pc = preempt_count();
 495         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 496         if (unlikely(disabled != 1))
 497                 goto out;
 498
 499         /* interrupts should be off from try_to_wake_up */
 500         arch_spin_lock(&wakeup_lock);
 501
 502         /* check for races. */
 503         if (!tracer_enabled || tracing_dl ||
 504             (!dl_task(p) && p->prio >= wakeup_prio))
 505                 goto out_locked;
 506
 507         /* reset the trace */
 508         __wakeup_reset(wakeup_trace);
 509
 510         wakeup_cpu = task_cpu(p);
 511         wakeup_current_cpu = wakeup_cpu;
 512         wakeup_prio = p->prio;
 513
 514         /*
 515          * Once you start tracing a -deadline task, don't bother tracing
 516          * another task until the first one wakes up.
 517          */
 518         if (dl_task(p))
 519                 tracing_dl = 1;
 520         else
 521                 tracing_dl = 0;
 522
 523         wakeup_task = p;
 524         get_task_struct(wakeup_task);
 525
 526         local_save_flags(flags);
 527
 528         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 529         data->preempt_timestamp = ftrace_now(cpu);
 530         tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
 531
 532         /*
 533          * We must be careful in using CALLER_ADDR2. But since wake_up
 534          * is not called by an assembly function  (where as schedule is)
 535          * it should be safe to use it here.
 536          */
 537         __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
 538
 539 out_locked:
 540         arch_spin_unlock(&wakeup_lock);
 541 out:
 542         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 543 }
 544
 545 static void start_wakeup_tracer(struct trace_array *tr)
 546 {
 547         int ret;
 548
 549         ret = register_trace_sched_wakeup(probe_wakeup, NULL);
 550         if (ret) {
 551                 pr_info("wakeup trace: Couldn't activate tracepoint"
 552                         " probe to kernel_sched_wakeup\n");
 553                 return;
 554         }
 555
 556         ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
 557         if (ret) {
 558                 pr_info("wakeup trace: Couldn't activate tracepoint"
 559                         " probe to kernel_sched_wakeup_new\n");
 560                 goto fail_deprobe;
 561         }
 562
 563         ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 564         if (ret) {
 565                 pr_info("sched trace: Couldn't activate tracepoint"
 566                         " probe to kernel_sched_switch\n");
 567                 goto fail_deprobe_wake_new;
 568         }
 569
 570         ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 571         if (ret) {
 572                 pr_info("wakeup trace: Couldn't activate tracepoint"
 573                         " probe to kernel_sched_migrate_task\n");
 574                 return;
 575         }
 576
 577         wakeup_reset(tr);
 578
 579         /*
 580          * Don't let the tracer_enabled = 1 show up before
 581          * the wakeup_task is reset. This may be overkill since
 582          * wakeup_reset does a spin_unlock after setting the
 583          * wakeup_task to NULL, but I want to be safe.
 584          * This is a slow path anyway.
 585          */
 586         smp_wmb();
 587
 588         if (start_func_tracer(is_graph()))
 589                 printk(KERN_ERR "failed to start wakeup tracer\n");
 590
 591         return;
 592 fail_deprobe_wake_new:
 593         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 594 fail_deprobe:
 595         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 596 }
 597
 598 static void stop_wakeup_tracer(struct trace_array *tr)
 599 {
 600         tracer_enabled = 0;
 601         stop_func_tracer(is_graph());
 602         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 603         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 604         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 605         unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 606 }
 607
 608 static int __wakeup_tracer_init(struct trace_array *tr)
 609 {
 610         save_flags = trace_flags;
 611
 612         /* non overwrite screws up the latency tracers */
 613         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
 614         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
 615
 616         tracing_max_latency = 0;
 617         wakeup_trace = tr;
 618         start_wakeup_tracer(tr);
 619         return 0;
 620 }
 621
 622 static int wakeup_tracer_init(struct trace_array *tr)
 623 {
 624         wakeup_dl = 0;
 625         wakeup_rt = 0;
 626         return __wakeup_tracer_init(tr);
 627 }
 628
 629 static int wakeup_rt_tracer_init(struct trace_array *tr)
 630 {
 631         wakeup_dl = 0;
 632         wakeup_rt = 1;
 633         return __wakeup_tracer_init(tr);
 634 }
 635
 636 static int wakeup_dl_tracer_init(struct trace_array *tr)
 637 {
 638         wakeup_dl = 1;
 639         wakeup_rt = 0;
 640         return __wakeup_tracer_init(tr);
 641 }
 642
 643 static void wakeup_tracer_reset(struct trace_array *tr)
 644 {
 645         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
 646         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
 647
 648         stop_wakeup_tracer(tr);
 649         /* make sure we put back any tasks we are tracing */
 650         wakeup_reset(tr);
 651
 652         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
 653         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
 654 }
 655
 656 static void wakeup_tracer_start(struct trace_array *tr)
 657 {
 658         wakeup_reset(tr);
 659         tracer_enabled = 1;
 660 }
 661
 662 static void wakeup_tracer_stop(struct trace_array *tr)
 663 {
 664         tracer_enabled = 0;
 665 }
 666
 667 static struct tracer wakeup_tracer __read_mostly =
 668 {
 669         .name           = "wakeup",
 670         .init           = wakeup_tracer_init,
 671         .reset          = wakeup_tracer_reset,
 672         .start          = wakeup_tracer_start,
 673         .stop           = wakeup_tracer_stop,
 674         .print_max      = true,
 675         .print_header   = wakeup_print_header,
 676         .print_line     = wakeup_print_line,
 677         .flags          = &tracer_flags,
 678         .set_flag       = wakeup_set_flag,
 679         .flag_changed   = wakeup_flag_changed,
 680 #ifdef CONFIG_FTRACE_SELFTEST
 681         .selftest    = trace_selftest_startup_wakeup,
 682 #endif
 683         .open           = wakeup_trace_open,
 684         .close          = wakeup_trace_close,
 685         .use_max_tr     = true,
 686 };
 687
 688 static struct tracer wakeup_rt_tracer __read_mostly =
 689 {
 690         .name           = "wakeup_rt",
 691         .init           = wakeup_rt_tracer_init,
 692         .reset          = wakeup_tracer_reset,
 693         .start          = wakeup_tracer_start,
 694         .stop           = wakeup_tracer_stop,
 695         .wait_pipe      = poll_wait_pipe,
 696         .print_max      = true,
 697         .print_header   = wakeup_print_header,
 698         .print_line     = wakeup_print_line,
 699         .flags          = &tracer_flags,
 700         .set_flag       = wakeup_set_flag,
 701         .flag_changed   = wakeup_flag_changed,
 702 #ifdef CONFIG_FTRACE_SELFTEST
 703         .selftest    = trace_selftest_startup_wakeup,
 704 #endif
 705         .open           = wakeup_trace_open,
 706         .close          = wakeup_trace_close,
 707         .use_max_tr     = true,
 708 };
 709
 710 static struct tracer wakeup_dl_tracer __read_mostly =
 711 {
 712         .name           = "wakeup_dl",
 713         .init           = wakeup_dl_tracer_init,
 714         .reset          = wakeup_tracer_reset,
 715         .start          = wakeup_tracer_start,
 716         .stop           = wakeup_tracer_stop,
 717         .wait_pipe      = poll_wait_pipe,
 718         .print_max      = true,
 719         .print_header   = wakeup_print_header,
 720         .print_line     = wakeup_print_line,
 721         .flags          = &tracer_flags,
 722         .set_flag       = wakeup_set_flag,
 723         .flag_changed   = wakeup_flag_changed,
 724 #ifdef CONFIG_FTRACE_SELFTEST
 725         .selftest    = trace_selftest_startup_wakeup,
 726 #endif
 727         .open           = wakeup_trace_open,
 728         .close          = wakeup_trace_close,
 729         .use_max_tr     = true,
 730 };
 731
 732 __init static int init_wakeup_tracer(void)
 733 {
 734         int ret;
 735
 736         ret = register_tracer(&wakeup_tracer);
 737         if (ret)
 738                 return ret;
 739
 740         ret = register_tracer(&wakeup_rt_tracer);
 741         if (ret)
 742                 return ret;
 743
 744         ret = register_tracer(&wakeup_dl_tracer);
 745         if (ret)
 746                 return ret;
 747
 748         return 0;
 749 }
 750 core_initcall(init_wakeup_tracer);