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 #endif /* CONFIG_FUNCTION_TRACER */
 134
 135 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
 136 {
 137         int ret;
 138
 139         /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
 140         if (function_enabled || (!set && !(trace_flags & TRACE_ITER_FUNCTION)))
 141                 return 0;
 142
 143         if (graph)
 144                 ret = register_ftrace_graph(&wakeup_graph_return,
 145                                             &wakeup_graph_entry);
 146         else
 147                 ret = register_ftrace_function(tr->ops);
 148
 149         if (!ret)
 150                 function_enabled = true;
 151
 152         return ret;
 153 }
 154
 155 static void unregister_wakeup_function(struct trace_array *tr, int graph)
 156 {
 157         if (!function_enabled)
 158                 return;
 159
 160         if (graph)
 161                 unregister_ftrace_graph();
 162         else
 163                 unregister_ftrace_function(tr->ops);
 164
 165         function_enabled = false;
 166 }
 167
 168 static void wakeup_function_set(struct trace_array *tr, int set)
 169 {
 170         if (set)
 171                 register_wakeup_function(tr, is_graph(), 1);
 172         else
 173                 unregister_wakeup_function(tr, is_graph());
 174 }
 175
 176 static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
 177 {
 178         struct tracer *tracer = tr->current_trace;
 179
 180         if (mask & TRACE_ITER_FUNCTION)
 181                 wakeup_function_set(tr, set);
 182
 183         return trace_keep_overwrite(tracer, mask, set);
 184 }
 185
 186 static int start_func_tracer(struct trace_array *tr, int graph)
 187 {
 188         int ret;
 189
 190         ret = register_wakeup_function(tr, graph, 0);
 191
 192         if (!ret && tracing_is_enabled())
 193                 tracer_enabled = 1;
 194         else
 195                 tracer_enabled = 0;
 196
 197         return ret;
 198 }
 199
 200 static void stop_func_tracer(struct trace_array *tr, int graph)
 201 {
 202         tracer_enabled = 0;
 203
 204         unregister_wakeup_function(tr, graph);
 205 }
 206
 207 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 208 static int
 209 wakeup_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 210 {
 211
 212         if (!(bit & TRACE_DISPLAY_GRAPH))
 213                 return -EINVAL;
 214
 215         if (!(is_graph() ^ set))
 216                 return 0;
 217
 218         stop_func_tracer(tr, !set);
 219
 220         wakeup_reset(wakeup_trace);
 221         tr->max_latency = 0;
 222
 223         return start_func_tracer(tr, set);
 224 }
 225
 226 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
 227 {
 228         struct trace_array *tr = wakeup_trace;
 229         struct trace_array_cpu *data;
 230         unsigned long flags;
 231         int pc, ret = 0;
 232
 233         if (!func_prolog_preempt_disable(tr, &data, &pc))
 234                 return 0;
 235
 236         local_save_flags(flags);
 237         ret = __trace_graph_entry(tr, trace, flags, pc);
 238         atomic_dec(&data->disabled);
 239         preempt_enable_notrace();
 240
 241         return ret;
 242 }
 243
 244 static void wakeup_graph_return(struct ftrace_graph_ret *trace)
 245 {
 246         struct trace_array *tr = wakeup_trace;
 247         struct trace_array_cpu *data;
 248         unsigned long flags;
 249         int pc;
 250
 251         if (!func_prolog_preempt_disable(tr, &data, &pc))
 252                 return;
 253
 254         local_save_flags(flags);
 255         __trace_graph_return(tr, trace, flags, pc);
 256         atomic_dec(&data->disabled);
 257
 258         preempt_enable_notrace();
 259         return;
 260 }
 261
 262 static void wakeup_trace_open(struct trace_iterator *iter)
 263 {
 264         if (is_graph())
 265                 graph_trace_open(iter);
 266 }
 267
 268 static void wakeup_trace_close(struct trace_iterator *iter)
 269 {
 270         if (iter->private)
 271                 graph_trace_close(iter);
 272 }
 273
 274 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
 275                             TRACE_GRAPH_PRINT_ABS_TIME | \
 276                             TRACE_GRAPH_PRINT_DURATION)
 277
 278 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 279 {
 280         /*
 281          * In graph mode call the graph tracer output function,
 282          * otherwise go with the TRACE_FN event handler
 283          */
 284         if (is_graph())
 285                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
 286
 287         return TRACE_TYPE_UNHANDLED;
 288 }
 289
 290 static void wakeup_print_header(struct seq_file *s)
 291 {
 292         if (is_graph())
 293                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
 294         else
 295                 trace_default_header(s);
 296 }
 297
 298 static void
 299 __trace_function(struct trace_array *tr,
 300                  unsigned long ip, unsigned long parent_ip,
 301                  unsigned long flags, int pc)
 302 {
 303         if (is_graph())
 304                 trace_graph_function(tr, ip, parent_ip, flags, pc);
 305         else
 306                 trace_function(tr, ip, parent_ip, flags, pc);
 307 }
 308 #else
 309 #define __trace_function trace_function
 310
 311 static int
 312 wakeup_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 313 {
 314         return -EINVAL;
 315 }
 316
 317 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
 318 {
 319         return -1;
 320 }
 321
 322 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 323 {
 324         return TRACE_TYPE_UNHANDLED;
 325 }
 326
 327 static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
 328 static void wakeup_trace_open(struct trace_iterator *iter) { }
 329 static void wakeup_trace_close(struct trace_iterator *iter) { }
 330
 331 #ifdef CONFIG_FUNCTION_TRACER
 332 static void wakeup_print_header(struct seq_file *s)
 333 {
 334         trace_default_header(s);
 335 }
 336 #else
 337 static void wakeup_print_header(struct seq_file *s)
 338 {
 339         trace_latency_header(s);
 340 }
 341 #endif /* CONFIG_FUNCTION_TRACER */
 342 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 343
 344 /*
 345  * Should this new latency be reported/recorded?
 346  */
 347 static int report_latency(struct trace_array *tr, cycle_t delta)
 348 {
 349         if (tracing_thresh) {
 350                 if (delta < tracing_thresh)
 351                         return 0;
 352         } else {
 353                 if (delta <= tr->max_latency)
 354                         return 0;
 355         }
 356         return 1;
 357 }
 358
 359 static void
 360 probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
 361 {
 362         if (task != wakeup_task)
 363                 return;
 364
 365         wakeup_current_cpu = cpu;
 366 }
 367
 368 static void
 369 tracing_sched_switch_trace(struct trace_array *tr,
 370                            struct task_struct *prev,
 371                            struct task_struct *next,
 372                            unsigned long flags, int pc)
 373 {
 374         struct ftrace_event_call *call = &event_context_switch;
 375         struct ring_buffer *buffer = tr->trace_buffer.buffer;
 376         struct ring_buffer_event *event;
 377         struct ctx_switch_entry *entry;
 378
 379         event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
 380                                           sizeof(*entry), flags, pc);
 381         if (!event)
 382                 return;
 383         entry   = ring_buffer_event_data(event);
 384         entry->prev_pid                 = prev->pid;
 385         entry->prev_prio                = prev->prio;
 386         entry->prev_state               = prev->state;
 387         entry->next_pid                 = next->pid;
 388         entry->next_prio                = next->prio;
 389         entry->next_state               = next->state;
 390         entry->next_cpu = task_cpu(next);
 391
 392         if (!call_filter_check_discard(call, entry, buffer, event))
 393                 trace_buffer_unlock_commit(buffer, event, flags, pc);
 394 }
 395
 396 static void
 397 tracing_sched_wakeup_trace(struct trace_array *tr,
 398                            struct task_struct *wakee,
 399                            struct task_struct *curr,
 400                            unsigned long flags, int pc)
 401 {
 402         struct ftrace_event_call *call = &event_wakeup;
 403         struct ring_buffer_event *event;
 404         struct ctx_switch_entry *entry;
 405         struct ring_buffer *buffer = tr->trace_buffer.buffer;
 406
 407         event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
 408                                           sizeof(*entry), flags, pc);
 409         if (!event)
 410                 return;
 411         entry   = ring_buffer_event_data(event);
 412         entry->prev_pid                 = curr->pid;
 413         entry->prev_prio                = curr->prio;
 414         entry->prev_state               = curr->state;
 415         entry->next_pid                 = wakee->pid;
 416         entry->next_prio                = wakee->prio;
 417         entry->next_state               = wakee->state;
 418         entry->next_cpu                 = task_cpu(wakee);
 419
 420         if (!call_filter_check_discard(call, entry, buffer, event))
 421                 trace_buffer_unlock_commit(buffer, event, flags, pc);
 422 }
 423
 424 static void notrace
 425 probe_wakeup_sched_switch(void *ignore,
 426                           struct task_struct *prev, struct task_struct *next)
 427 {
 428         struct trace_array_cpu *data;
 429         cycle_t T0, T1, delta;
 430         unsigned long flags;
 431         long disabled;
 432         int cpu;
 433         int pc;
 434
 435         tracing_record_cmdline(prev);
 436
 437         if (unlikely(!tracer_enabled))
 438                 return;
 439
 440         /*
 441          * When we start a new trace, we set wakeup_task to NULL
 442          * and then set tracer_enabled = 1. We want to make sure
 443          * that another CPU does not see the tracer_enabled = 1
 444          * and the wakeup_task with an older task, that might
 445          * actually be the same as next.
 446          */
 447         smp_rmb();
 448
 449         if (next != wakeup_task)
 450                 return;
 451
 452         pc = preempt_count();
 453
 454         /* disable local data, not wakeup_cpu data */
 455         cpu = raw_smp_processor_id();
 456         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 457         if (likely(disabled != 1))
 458                 goto out;
 459
 460         local_irq_save(flags);
 461         arch_spin_lock(&wakeup_lock);
 462
 463         /* We could race with grabbing wakeup_lock */
 464         if (unlikely(!tracer_enabled || next != wakeup_task))
 465                 goto out_unlock;
 466
 467         /* The task we are waiting for is waking up */
 468         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 469
 470         __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
 471         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 472
 473         T0 = data->preempt_timestamp;
 474         T1 = ftrace_now(cpu);
 475         delta = T1-T0;
 476
 477         if (!report_latency(wakeup_trace, delta))
 478                 goto out_unlock;
 479
 480         if (likely(!is_tracing_stopped())) {
 481                 wakeup_trace->max_latency = delta;
 482                 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
 483         }
 484
 485 out_unlock:
 486         __wakeup_reset(wakeup_trace);
 487         arch_spin_unlock(&wakeup_lock);
 488         local_irq_restore(flags);
 489 out:
 490         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 491 }
 492
 493 static void __wakeup_reset(struct trace_array *tr)
 494 {
 495         wakeup_cpu = -1;
 496         wakeup_prio = -1;
 497         tracing_dl = 0;
 498
 499         if (wakeup_task)
 500                 put_task_struct(wakeup_task);
 501
 502         wakeup_task = NULL;
 503 }
 504
 505 static void wakeup_reset(struct trace_array *tr)
 506 {
 507         unsigned long flags;
 508
 509         tracing_reset_online_cpus(&tr->trace_buffer);
 510
 511         local_irq_save(flags);
 512         arch_spin_lock(&wakeup_lock);
 513         __wakeup_reset(tr);
 514         arch_spin_unlock(&wakeup_lock);
 515         local_irq_restore(flags);
 516 }
 517
 518 static void
 519 probe_wakeup(void *ignore, struct task_struct *p, int success)
 520 {
 521         struct trace_array_cpu *data;
 522         int cpu = smp_processor_id();
 523         unsigned long flags;
 524         long disabled;
 525         int pc;
 526
 527         if (likely(!tracer_enabled))
 528                 return;
 529
 530         tracing_record_cmdline(p);
 531         tracing_record_cmdline(current);
 532
 533         /*
 534          * Semantic is like this:
 535          *  - wakeup tracer handles all tasks in the system, independently
 536          *    from their scheduling class;
 537          *  - wakeup_rt tracer handles tasks belonging to sched_dl and
 538          *    sched_rt class;
 539          *  - wakeup_dl handles tasks belonging to sched_dl class only.
 540          */
 541         if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
 542             (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
 543             (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
 544                 return;
 545
 546         pc = preempt_count();
 547         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 548         if (unlikely(disabled != 1))
 549                 goto out;
 550
 551         /* interrupts should be off from try_to_wake_up */
 552         arch_spin_lock(&wakeup_lock);
 553
 554         /* check for races. */
 555         if (!tracer_enabled || tracing_dl ||
 556             (!dl_task(p) && p->prio >= wakeup_prio))
 557                 goto out_locked;
 558
 559         /* reset the trace */
 560         __wakeup_reset(wakeup_trace);
 561
 562         wakeup_cpu = task_cpu(p);
 563         wakeup_current_cpu = wakeup_cpu;
 564         wakeup_prio = p->prio;
 565
 566         /*
 567          * Once you start tracing a -deadline task, don't bother tracing
 568          * another task until the first one wakes up.
 569          */
 570         if (dl_task(p))
 571                 tracing_dl = 1;
 572         else
 573                 tracing_dl = 0;
 574
 575         wakeup_task = p;
 576         get_task_struct(wakeup_task);
 577
 578         local_save_flags(flags);
 579
 580         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 581         data->preempt_timestamp = ftrace_now(cpu);
 582         tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
 583
 584         /*
 585          * We must be careful in using CALLER_ADDR2. But since wake_up
 586          * is not called by an assembly function  (where as schedule is)
 587          * it should be safe to use it here.
 588          */
 589         __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
 590
 591 out_locked:
 592         arch_spin_unlock(&wakeup_lock);
 593 out:
 594         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 595 }
 596
 597 static void start_wakeup_tracer(struct trace_array *tr)
 598 {
 599         int ret;
 600
 601         ret = register_trace_sched_wakeup(probe_wakeup, NULL);
 602         if (ret) {
 603                 pr_info("wakeup trace: Couldn't activate tracepoint"
 604                         " probe to kernel_sched_wakeup\n");
 605                 return;
 606         }
 607
 608         ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
 609         if (ret) {
 610                 pr_info("wakeup trace: Couldn't activate tracepoint"
 611                         " probe to kernel_sched_wakeup_new\n");
 612                 goto fail_deprobe;
 613         }
 614
 615         ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 616         if (ret) {
 617                 pr_info("sched trace: Couldn't activate tracepoint"
 618                         " probe to kernel_sched_switch\n");
 619                 goto fail_deprobe_wake_new;
 620         }
 621
 622         ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 623         if (ret) {
 624                 pr_info("wakeup trace: Couldn't activate tracepoint"
 625                         " probe to kernel_sched_migrate_task\n");
 626                 return;
 627         }
 628
 629         wakeup_reset(tr);
 630
 631         /*
 632          * Don't let the tracer_enabled = 1 show up before
 633          * the wakeup_task is reset. This may be overkill since
 634          * wakeup_reset does a spin_unlock after setting the
 635          * wakeup_task to NULL, but I want to be safe.
 636          * This is a slow path anyway.
 637          */
 638         smp_wmb();
 639
 640         if (start_func_tracer(tr, is_graph()))
 641                 printk(KERN_ERR "failed to start wakeup tracer\n");
 642
 643         return;
 644 fail_deprobe_wake_new:
 645         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 646 fail_deprobe:
 647         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 648 }
 649
 650 static void stop_wakeup_tracer(struct trace_array *tr)
 651 {
 652         tracer_enabled = 0;
 653         stop_func_tracer(tr, is_graph());
 654         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 655         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 656         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 657         unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 658 }
 659
 660 static bool wakeup_busy;
 661
 662 static int __wakeup_tracer_init(struct trace_array *tr)
 663 {
 664         save_flags = trace_flags;
 665
 666         /* non overwrite screws up the latency tracers */
 667         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
 668         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
 669
 670         tr->max_latency = 0;
 671         wakeup_trace = tr;
 672         ftrace_init_array_ops(tr, wakeup_tracer_call);
 673         start_wakeup_tracer(tr);
 674
 675         wakeup_busy = true;
 676         return 0;
 677 }
 678
 679 static int wakeup_tracer_init(struct trace_array *tr)
 680 {
 681         if (wakeup_busy)
 682                 return -EBUSY;
 683
 684         wakeup_dl = 0;
 685         wakeup_rt = 0;
 686         return __wakeup_tracer_init(tr);
 687 }
 688
 689 static int wakeup_rt_tracer_init(struct trace_array *tr)
 690 {
 691         if (wakeup_busy)
 692                 return -EBUSY;
 693
 694         wakeup_dl = 0;
 695         wakeup_rt = 1;
 696         return __wakeup_tracer_init(tr);
 697 }
 698
 699 static int wakeup_dl_tracer_init(struct trace_array *tr)
 700 {
 701         if (wakeup_busy)
 702                 return -EBUSY;
 703
 704         wakeup_dl = 1;
 705         wakeup_rt = 0;
 706         return __wakeup_tracer_init(tr);
 707 }
 708
 709 static void wakeup_tracer_reset(struct trace_array *tr)
 710 {
 711         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
 712         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
 713
 714         stop_wakeup_tracer(tr);
 715         /* make sure we put back any tasks we are tracing */
 716         wakeup_reset(tr);
 717
 718         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
 719         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
 720         ftrace_reset_array_ops(tr);
 721         wakeup_busy = false;
 722 }
 723
 724 static void wakeup_tracer_start(struct trace_array *tr)
 725 {
 726         wakeup_reset(tr);
 727         tracer_enabled = 1;
 728 }
 729
 730 static void wakeup_tracer_stop(struct trace_array *tr)
 731 {
 732         tracer_enabled = 0;
 733 }
 734
 735 static struct tracer wakeup_tracer __read_mostly =
 736 {
 737         .name           = "wakeup",
 738         .init           = wakeup_tracer_init,
 739         .reset          = wakeup_tracer_reset,
 740         .start          = wakeup_tracer_start,
 741         .stop           = wakeup_tracer_stop,
 742         .print_max      = true,
 743         .print_header   = wakeup_print_header,
 744         .print_line     = wakeup_print_line,
 745         .flags          = &tracer_flags,
 746         .set_flag       = wakeup_set_flag,
 747         .flag_changed   = wakeup_flag_changed,
 748 #ifdef CONFIG_FTRACE_SELFTEST
 749         .selftest    = trace_selftest_startup_wakeup,
 750 #endif
 751         .open           = wakeup_trace_open,
 752         .close          = wakeup_trace_close,
 753         .allow_instances = true,
 754         .use_max_tr     = true,
 755 };
 756
 757 static struct tracer wakeup_rt_tracer __read_mostly =
 758 {
 759         .name           = "wakeup_rt",
 760         .init           = wakeup_rt_tracer_init,
 761         .reset          = wakeup_tracer_reset,
 762         .start          = wakeup_tracer_start,
 763         .stop           = wakeup_tracer_stop,
 764         .print_max      = true,
 765         .print_header   = wakeup_print_header,
 766         .print_line     = wakeup_print_line,
 767         .flags          = &tracer_flags,
 768         .set_flag       = wakeup_set_flag,
 769         .flag_changed   = wakeup_flag_changed,
 770 #ifdef CONFIG_FTRACE_SELFTEST
 771         .selftest    = trace_selftest_startup_wakeup,
 772 #endif
 773         .open           = wakeup_trace_open,
 774         .close          = wakeup_trace_close,
 775         .allow_instances = true,
 776         .use_max_tr     = true,
 777 };
 778
 779 static struct tracer wakeup_dl_tracer __read_mostly =
 780 {
 781         .name           = "wakeup_dl",
 782         .init           = wakeup_dl_tracer_init,
 783         .reset          = wakeup_tracer_reset,
 784         .start          = wakeup_tracer_start,
 785         .stop           = wakeup_tracer_stop,
 786         .print_max      = true,
 787         .print_header   = wakeup_print_header,
 788         .print_line     = wakeup_print_line,
 789         .flags          = &tracer_flags,
 790         .set_flag       = wakeup_set_flag,
 791         .flag_changed   = wakeup_flag_changed,
 792 #ifdef CONFIG_FTRACE_SELFTEST
 793         .selftest    = trace_selftest_startup_wakeup,
 794 #endif
 795         .open           = wakeup_trace_open,
 796         .close          = wakeup_trace_close,
 797         .use_max_tr     = true,
 798 };
 799
 800 __init static int init_wakeup_tracer(void)
 801 {
 802         int ret;
 803
 804         ret = register_tracer(&wakeup_tracer);
 805         if (ret)
 806                 return ret;
 807
 808         ret = register_tracer(&wakeup_rt_tracer);
 809         if (ret)
 810                 return ret;
 811
 812         ret = register_tracer(&wakeup_dl_tracer);
 813         if (ret)
 814                 return ret;
 815
 816         return 0;
 817 }
 818 core_initcall(init_wakeup_tracer);