kernel/trace/trace_sched_wakeup.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * trace task wakeup timings
   4  *
   5  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   6  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
   7  *
   8  * Based on code from the latency_tracer, that is:
   9  *
  10  *  Copyright (C) 2004-2006 Ingo Molnar
  11  *  Copyright (C) 2004 Nadia Yvette Chambers
  12  */
  13 #include <linux/module.h>
  14 #include <linux/kallsyms.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/ftrace.h>
  17 #include <linux/sched/rt.h>
  18 #include <linux/sched/deadline.h>
  19 #include <trace/events/sched.h>
  20 #include "trace.h"
  21
  22 static struct trace_array       *wakeup_trace;
  23 static int __read_mostly        tracer_enabled;
  24
  25 static struct task_struct       *wakeup_task;
  26 static int                      wakeup_cpu;
  27 static int                      wakeup_current_cpu;
  28 static unsigned                 wakeup_prio = -1;
  29 static int                      wakeup_rt;
  30 static int                      wakeup_dl;
  31 static int                      tracing_dl = 0;
  32
  33 static arch_spinlock_t wakeup_lock =
  34         (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  35
  36 static void wakeup_reset(struct trace_array *tr);
  37 static void __wakeup_reset(struct trace_array *tr);
  38 static int start_func_tracer(struct trace_array *tr, int graph);
  39 static void stop_func_tracer(struct trace_array *tr, int graph);
  40
  41 static int save_flags;
  42
  43 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  44 # define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
  45 #else
  46 # define is_graph(tr) false
  47 #endif
  48
  49 #ifdef CONFIG_FUNCTION_TRACER
  50
  51 static bool function_enabled;
  52
  53 /*
  54  * Prologue for the wakeup function tracers.
  55  *
  56  * Returns 1 if it is OK to continue, and preemption
  57  *            is disabled and data->disabled is incremented.
  58  *         0 if the trace is to be ignored, and preemption
  59  *            is not disabled and data->disabled is
  60  *            kept the same.
  61  *
  62  * Note, this function is also used outside this ifdef but
  63  *  inside the #ifdef of the function graph tracer below.
  64  *  This is OK, since the function graph tracer is
  65  *  dependent on the function tracer.
  66  */
  67 static int
  68 func_prolog_preempt_disable(struct trace_array *tr,
  69                             struct trace_array_cpu **data,
  70                             int *pc)
  71 {
  72         long disabled;
  73         int cpu;
  74
  75         if (likely(!wakeup_task))
  76                 return 0;
  77
  78         *pc = preempt_count();
  79         preempt_disable_notrace();
  80
  81         cpu = raw_smp_processor_id();
  82         if (cpu != wakeup_current_cpu)
  83                 goto out_enable;
  84
  85         *data = per_cpu_ptr(tr->array_buffer.data, cpu);
  86         disabled = atomic_inc_return(&(*data)->disabled);
  87         if (unlikely(disabled != 1))
  88                 goto out;
  89
  90         return 1;
  91
  92 out:
  93         atomic_dec(&(*data)->disabled);
  94
  95 out_enable:
  96         preempt_enable_notrace();
  97         return 0;
  98 }
  99
 100 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 101
 102 static int wakeup_display_graph(struct trace_array *tr, int set)
 103 {
 104         if (!(is_graph(tr) ^ set))
 105                 return 0;
 106
 107         stop_func_tracer(tr, !set);
 108
 109         wakeup_reset(wakeup_trace);
 110         tr->max_latency = 0;
 111
 112         return start_func_tracer(tr, set);
 113 }
 114
 115 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
 116 {
 117         struct trace_array *tr = wakeup_trace;
 118         struct trace_array_cpu *data;
 119         unsigned long flags;
 120         int pc, ret = 0;
 121
 122         if (ftrace_graph_ignore_func(trace))
 123                 return 0;
 124         /*
 125          * Do not trace a function if it's filtered by set_graph_notrace.
 126          * Make the index of ret stack negative to indicate that it should
 127          * ignore further functions.  But it needs its own ret stack entry
 128          * to recover the original index in order to continue tracing after
 129          * returning from the function.
 130          */
 131         if (ftrace_graph_notrace_addr(trace->func))
 132                 return 1;
 133
 134         if (!func_prolog_preempt_disable(tr, &data, &pc))
 135                 return 0;
 136
 137         local_save_flags(flags);
 138         ret = __trace_graph_entry(tr, trace, flags, pc);
 139         atomic_dec(&data->disabled);
 140         preempt_enable_notrace();
 141
 142         return ret;
 143 }
 144
 145 static void wakeup_graph_return(struct ftrace_graph_ret *trace)
 146 {
 147         struct trace_array *tr = wakeup_trace;
 148         struct trace_array_cpu *data;
 149         unsigned long flags;
 150         int pc;
 151
 152         ftrace_graph_addr_finish(trace);
 153
 154         if (!func_prolog_preempt_disable(tr, &data, &pc))
 155                 return;
 156
 157         local_save_flags(flags);
 158         __trace_graph_return(tr, trace, flags, pc);
 159         atomic_dec(&data->disabled);
 160
 161         preempt_enable_notrace();
 162         return;
 163 }
 164
 165 static struct fgraph_ops fgraph_wakeup_ops = {
 166         .entryfunc = &wakeup_graph_entry,
 167         .retfunc = &wakeup_graph_return,
 168 };
 169
 170 static void wakeup_trace_open(struct trace_iterator *iter)
 171 {
 172         if (is_graph(iter->tr))
 173                 graph_trace_open(iter);
 174         else
 175                 iter->private = NULL;
 176 }
 177
 178 static void wakeup_trace_close(struct trace_iterator *iter)
 179 {
 180         if (iter->private)
 181                 graph_trace_close(iter);
 182 }
 183
 184 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
 185                             TRACE_GRAPH_PRINT_CPU |  \
 186                             TRACE_GRAPH_PRINT_REL_TIME | \
 187                             TRACE_GRAPH_PRINT_DURATION | \
 188                             TRACE_GRAPH_PRINT_OVERHEAD | \
 189                             TRACE_GRAPH_PRINT_IRQS)
 190
 191 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 192 {
 193         /*
 194          * In graph mode call the graph tracer output function,
 195          * otherwise go with the TRACE_FN event handler
 196          */
 197         if (is_graph(iter->tr))
 198                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
 199
 200         return TRACE_TYPE_UNHANDLED;
 201 }
 202
 203 static void wakeup_print_header(struct seq_file *s)
 204 {
 205         if (is_graph(wakeup_trace))
 206                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
 207         else
 208                 trace_default_header(s);
 209 }
 210 #endif /* else CONFIG_FUNCTION_GRAPH_TRACER */
 211
 212 /*
 213  * wakeup uses its own tracer function to keep the overhead down:
 214  */
 215 static void
 216 wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
 217                    struct ftrace_ops *op, struct pt_regs *pt_regs)
 218 {
 219         struct trace_array *tr = wakeup_trace;
 220         struct trace_array_cpu *data;
 221         unsigned long flags;
 222         int pc;
 223
 224         if (!func_prolog_preempt_disable(tr, &data, &pc))
 225                 return;
 226
 227         local_irq_save(flags);
 228         trace_function(tr, ip, parent_ip, flags, pc);
 229         local_irq_restore(flags);
 230
 231         atomic_dec(&data->disabled);
 232         preempt_enable_notrace();
 233 }
 234
 235 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
 236 {
 237         int ret;
 238
 239         /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
 240         if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
 241                 return 0;
 242
 243         if (graph)
 244                 ret = register_ftrace_graph(&fgraph_wakeup_ops);
 245         else
 246                 ret = register_ftrace_function(tr->ops);
 247
 248         if (!ret)
 249                 function_enabled = true;
 250
 251         return ret;
 252 }
 253
 254 static void unregister_wakeup_function(struct trace_array *tr, int graph)
 255 {
 256         if (!function_enabled)
 257                 return;
 258
 259         if (graph)
 260                 unregister_ftrace_graph(&fgraph_wakeup_ops);
 261         else
 262                 unregister_ftrace_function(tr->ops);
 263
 264         function_enabled = false;
 265 }
 266
 267 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
 268 {
 269         if (!(mask & TRACE_ITER_FUNCTION))
 270                 return 0;
 271
 272         if (set)
 273                 register_wakeup_function(tr, is_graph(tr), 1);
 274         else
 275                 unregister_wakeup_function(tr, is_graph(tr));
 276         return 1;
 277 }
 278 #else /* CONFIG_FUNCTION_TRACER */
 279 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
 280 {
 281         return 0;
 282 }
 283 static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
 284 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
 285 {
 286         return 0;
 287 }
 288 #endif /* else CONFIG_FUNCTION_TRACER */
 289
 290 #ifndef CONFIG_FUNCTION_GRAPH_TRACER
 291 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 292 {
 293         return TRACE_TYPE_UNHANDLED;
 294 }
 295
 296 static void wakeup_trace_open(struct trace_iterator *iter) { }
 297 static void wakeup_trace_close(struct trace_iterator *iter) { }
 298
 299 static void wakeup_print_header(struct seq_file *s)
 300 {
 301         trace_default_header(s);
 302 }
 303 #endif /* !CONFIG_FUNCTION_GRAPH_TRACER */
 304
 305 static void
 306 __trace_function(struct trace_array *tr,
 307                  unsigned long ip, unsigned long parent_ip,
 308                  unsigned long flags, int pc)
 309 {
 310         if (is_graph(tr))
 311                 trace_graph_function(tr, ip, parent_ip, flags, pc);
 312         else
 313                 trace_function(tr, ip, parent_ip, flags, pc);
 314 }
 315
 316 static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
 317 {
 318         struct tracer *tracer = tr->current_trace;
 319
 320         if (wakeup_function_set(tr, mask, set))
 321                 return 0;
 322
 323 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 324         if (mask & TRACE_ITER_DISPLAY_GRAPH)
 325                 return wakeup_display_graph(tr, set);
 326 #endif
 327
 328         return trace_keep_overwrite(tracer, mask, set);
 329 }
 330
 331 static int start_func_tracer(struct trace_array *tr, int graph)
 332 {
 333         int ret;
 334
 335         ret = register_wakeup_function(tr, graph, 0);
 336
 337         if (!ret && tracing_is_enabled())
 338                 tracer_enabled = 1;
 339         else
 340                 tracer_enabled = 0;
 341
 342         return ret;
 343 }
 344
 345 static void stop_func_tracer(struct trace_array *tr, int graph)
 346 {
 347         tracer_enabled = 0;
 348
 349         unregister_wakeup_function(tr, graph);
 350 }
 351
 352 /*
 353  * Should this new latency be reported/recorded?
 354  */
 355 static bool report_latency(struct trace_array *tr, u64 delta)
 356 {
 357         if (tracing_thresh) {
 358                 if (delta < tracing_thresh)
 359                         return false;
 360         } else {
 361                 if (delta <= tr->max_latency)
 362                         return false;
 363         }
 364         return true;
 365 }
 366
 367 static void
 368 probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
 369 {
 370         if (task != wakeup_task)
 371                 return;
 372
 373         wakeup_current_cpu = cpu;
 374 }
 375
 376 static void
 377 tracing_sched_switch_trace(struct trace_array *tr,
 378                            struct task_struct *prev,
 379                            struct task_struct *next,
 380                            unsigned long flags, int pc)
 381 {
 382         struct trace_event_call *call = &event_context_switch;
 383         struct trace_buffer *buffer = tr->array_buffer.buffer;
 384         struct ring_buffer_event *event;
 385         struct ctx_switch_entry *entry;
 386
 387         event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
 388                                           sizeof(*entry), flags, pc);
 389         if (!event)
 390                 return;
 391         entry   = ring_buffer_event_data(event);
 392         entry->prev_pid                 = prev->pid;
 393         entry->prev_prio                = prev->prio;
 394         entry->prev_state               = task_state_index(prev);
 395         entry->next_pid                 = next->pid;
 396         entry->next_prio                = next->prio;
 397         entry->next_state               = task_state_index(next);
 398         entry->next_cpu = task_cpu(next);
 399
 400         if (!call_filter_check_discard(call, entry, buffer, event))
 401                 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
 402 }
 403
 404 static void
 405 tracing_sched_wakeup_trace(struct trace_array *tr,
 406                            struct task_struct *wakee,
 407                            struct task_struct *curr,
 408                            unsigned long flags, int pc)
 409 {
 410         struct trace_event_call *call = &event_wakeup;
 411         struct ring_buffer_event *event;
 412         struct ctx_switch_entry *entry;
 413         struct trace_buffer *buffer = tr->array_buffer.buffer;
 414
 415         event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
 416                                           sizeof(*entry), flags, pc);
 417         if (!event)
 418                 return;
 419         entry   = ring_buffer_event_data(event);
 420         entry->prev_pid                 = curr->pid;
 421         entry->prev_prio                = curr->prio;
 422         entry->prev_state               = task_state_index(curr);
 423         entry->next_pid                 = wakee->pid;
 424         entry->next_prio                = wakee->prio;
 425         entry->next_state               = task_state_index(wakee);
 426         entry->next_cpu                 = task_cpu(wakee);
 427
 428         if (!call_filter_check_discard(call, entry, buffer, event))
 429                 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
 430 }
 431
 432 static void notrace
 433 probe_wakeup_sched_switch(void *ignore, bool preempt,
 434                           struct task_struct *prev, struct task_struct *next)
 435 {
 436         struct trace_array_cpu *data;
 437         u64 T0, T1, delta;
 438         unsigned long flags;
 439         long disabled;
 440         int cpu;
 441         int pc;
 442
 443         tracing_record_cmdline(prev);
 444
 445         if (unlikely(!tracer_enabled))
 446                 return;
 447
 448         /*
 449          * When we start a new trace, we set wakeup_task to NULL
 450          * and then set tracer_enabled = 1. We want to make sure
 451          * that another CPU does not see the tracer_enabled = 1
 452          * and the wakeup_task with an older task, that might
 453          * actually be the same as next.
 454          */
 455         smp_rmb();
 456
 457         if (next != wakeup_task)
 458                 return;
 459
 460         pc = preempt_count();
 461
 462         /* disable local data, not wakeup_cpu data */
 463         cpu = raw_smp_processor_id();
 464         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
 465         if (likely(disabled != 1))
 466                 goto out;
 467
 468         local_irq_save(flags);
 469         arch_spin_lock(&wakeup_lock);
 470
 471         /* We could race with grabbing wakeup_lock */
 472         if (unlikely(!tracer_enabled || next != wakeup_task))
 473                 goto out_unlock;
 474
 475         /* The task we are waiting for is waking up */
 476         data = per_cpu_ptr(wakeup_trace->array_buffer.data, wakeup_cpu);
 477
 478         __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
 479         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 480         __trace_stack(wakeup_trace, flags, 0, pc);
 481
 482         T0 = data->preempt_timestamp;
 483         T1 = ftrace_now(cpu);
 484         delta = T1-T0;
 485
 486         if (!report_latency(wakeup_trace, delta))
 487                 goto out_unlock;
 488
 489         if (likely(!is_tracing_stopped())) {
 490                 wakeup_trace->max_latency = delta;
 491                 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu, NULL);
 492         }
 493
 494 out_unlock:
 495         __wakeup_reset(wakeup_trace);
 496         arch_spin_unlock(&wakeup_lock);
 497         local_irq_restore(flags);
 498 out:
 499         atomic_dec(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
 500 }
 501
 502 static void __wakeup_reset(struct trace_array *tr)
 503 {
 504         wakeup_cpu = -1;
 505         wakeup_prio = -1;
 506         tracing_dl = 0;
 507
 508         if (wakeup_task)
 509                 put_task_struct(wakeup_task);
 510
 511         wakeup_task = NULL;
 512 }
 513
 514 static void wakeup_reset(struct trace_array *tr)
 515 {
 516         unsigned long flags;
 517
 518         tracing_reset_online_cpus(&tr->array_buffer);
 519
 520         local_irq_save(flags);
 521         arch_spin_lock(&wakeup_lock);
 522         __wakeup_reset(tr);
 523         arch_spin_unlock(&wakeup_lock);
 524         local_irq_restore(flags);
 525 }
 526
 527 static void
 528 probe_wakeup(void *ignore, struct task_struct *p)
 529 {
 530         struct trace_array_cpu *data;
 531         int cpu = smp_processor_id();
 532         unsigned long flags;
 533         long disabled;
 534         int pc;
 535
 536         if (likely(!tracer_enabled))
 537                 return;
 538
 539         tracing_record_cmdline(p);
 540         tracing_record_cmdline(current);
 541
 542         /*
 543          * Semantic is like this:
 544          *  - wakeup tracer handles all tasks in the system, independently
 545          *    from their scheduling class;
 546          *  - wakeup_rt tracer handles tasks belonging to sched_dl and
 547          *    sched_rt class;
 548          *  - wakeup_dl handles tasks belonging to sched_dl class only.
 549          */
 550         if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
 551             (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
 552             (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
 553                 return;
 554
 555         pc = preempt_count();
 556         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
 557         if (unlikely(disabled != 1))
 558                 goto out;
 559
 560         /* interrupts should be off from try_to_wake_up */
 561         arch_spin_lock(&wakeup_lock);
 562
 563         /* check for races. */
 564         if (!tracer_enabled || tracing_dl ||
 565             (!dl_task(p) && p->prio >= wakeup_prio))
 566                 goto out_locked;
 567
 568         /* reset the trace */
 569         __wakeup_reset(wakeup_trace);
 570
 571         wakeup_cpu = task_cpu(p);
 572         wakeup_current_cpu = wakeup_cpu;
 573         wakeup_prio = p->prio;
 574
 575         /*
 576          * Once you start tracing a -deadline task, don't bother tracing
 577          * another task until the first one wakes up.
 578          */
 579         if (dl_task(p))
 580                 tracing_dl = 1;
 581         else
 582                 tracing_dl = 0;
 583
 584         wakeup_task = get_task_struct(p);
 585
 586         local_save_flags(flags);
 587
 588         data = per_cpu_ptr(wakeup_trace->array_buffer.data, wakeup_cpu);
 589         data->preempt_timestamp = ftrace_now(cpu);
 590         tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
 591         __trace_stack(wakeup_trace, flags, 0, pc);
 592
 593         /*
 594          * We must be careful in using CALLER_ADDR2. But since wake_up
 595          * is not called by an assembly function  (where as schedule is)
 596          * it should be safe to use it here.
 597          */
 598         __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
 599
 600 out_locked:
 601         arch_spin_unlock(&wakeup_lock);
 602 out:
 603         atomic_dec(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
 604 }
 605
 606 static void start_wakeup_tracer(struct trace_array *tr)
 607 {
 608         int ret;
 609
 610         ret = register_trace_sched_wakeup(probe_wakeup, NULL);
 611         if (ret) {
 612                 pr_info("wakeup trace: Couldn't activate tracepoint"
 613                         " probe to kernel_sched_wakeup\n");
 614                 return;
 615         }
 616
 617         ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
 618         if (ret) {
 619                 pr_info("wakeup trace: Couldn't activate tracepoint"
 620                         " probe to kernel_sched_wakeup_new\n");
 621                 goto fail_deprobe;
 622         }
 623
 624         ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 625         if (ret) {
 626                 pr_info("sched trace: Couldn't activate tracepoint"
 627                         " probe to kernel_sched_switch\n");
 628                 goto fail_deprobe_wake_new;
 629         }
 630
 631         ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 632         if (ret) {
 633                 pr_info("wakeup trace: Couldn't activate tracepoint"
 634                         " probe to kernel_sched_migrate_task\n");
 635                 goto fail_deprobe_sched_switch;
 636         }
 637
 638         wakeup_reset(tr);
 639
 640         /*
 641          * Don't let the tracer_enabled = 1 show up before
 642          * the wakeup_task is reset. This may be overkill since
 643          * wakeup_reset does a spin_unlock after setting the
 644          * wakeup_task to NULL, but I want to be safe.
 645          * This is a slow path anyway.
 646          */
 647         smp_wmb();
 648
 649         if (start_func_tracer(tr, is_graph(tr)))
 650                 printk(KERN_ERR "failed to start wakeup tracer\n");
 651
 652         return;
 653 fail_deprobe_sched_switch:
 654         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 655 fail_deprobe_wake_new:
 656         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 657 fail_deprobe:
 658         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 659 }
 660
 661 static void stop_wakeup_tracer(struct trace_array *tr)
 662 {
 663         tracer_enabled = 0;
 664         stop_func_tracer(tr, is_graph(tr));
 665         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 666         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 667         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 668         unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 669 }
 670
 671 static bool wakeup_busy;
 672
 673 static int __wakeup_tracer_init(struct trace_array *tr)
 674 {
 675         save_flags = tr->trace_flags;
 676
 677         /* non overwrite screws up the latency tracers */
 678         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
 679         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
 680
 681         tr->max_latency = 0;
 682         wakeup_trace = tr;
 683         ftrace_init_array_ops(tr, wakeup_tracer_call);
 684         start_wakeup_tracer(tr);
 685
 686         wakeup_busy = true;
 687         return 0;
 688 }
 689
 690 static int wakeup_tracer_init(struct trace_array *tr)
 691 {
 692         if (wakeup_busy)
 693                 return -EBUSY;
 694
 695         wakeup_dl = 0;
 696         wakeup_rt = 0;
 697         return __wakeup_tracer_init(tr);
 698 }
 699
 700 static int wakeup_rt_tracer_init(struct trace_array *tr)
 701 {
 702         if (wakeup_busy)
 703                 return -EBUSY;
 704
 705         wakeup_dl = 0;
 706         wakeup_rt = 1;
 707         return __wakeup_tracer_init(tr);
 708 }
 709
 710 static int wakeup_dl_tracer_init(struct trace_array *tr)
 711 {
 712         if (wakeup_busy)
 713                 return -EBUSY;
 714
 715         wakeup_dl = 1;
 716         wakeup_rt = 0;
 717         return __wakeup_tracer_init(tr);
 718 }
 719
 720 static void wakeup_tracer_reset(struct trace_array *tr)
 721 {
 722         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
 723         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
 724
 725         stop_wakeup_tracer(tr);
 726         /* make sure we put back any tasks we are tracing */
 727         wakeup_reset(tr);
 728
 729         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
 730         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
 731         ftrace_reset_array_ops(tr);
 732         wakeup_busy = false;
 733 }
 734
 735 static void wakeup_tracer_start(struct trace_array *tr)
 736 {
 737         wakeup_reset(tr);
 738         tracer_enabled = 1;
 739 }
 740
 741 static void wakeup_tracer_stop(struct trace_array *tr)
 742 {
 743         tracer_enabled = 0;
 744 }
 745
 746 static struct tracer wakeup_tracer __read_mostly =
 747 {
 748         .name           = "wakeup",
 749         .init           = wakeup_tracer_init,
 750         .reset          = wakeup_tracer_reset,
 751         .start          = wakeup_tracer_start,
 752         .stop           = wakeup_tracer_stop,
 753         .print_max      = true,
 754         .print_header   = wakeup_print_header,
 755         .print_line     = wakeup_print_line,
 756         .flag_changed   = wakeup_flag_changed,
 757 #ifdef CONFIG_FTRACE_SELFTEST
 758         .selftest    = trace_selftest_startup_wakeup,
 759 #endif
 760         .open           = wakeup_trace_open,
 761         .close          = wakeup_trace_close,
 762         .allow_instances = true,
 763         .use_max_tr     = true,
 764 };
 765
 766 static struct tracer wakeup_rt_tracer __read_mostly =
 767 {
 768         .name           = "wakeup_rt",
 769         .init           = wakeup_rt_tracer_init,
 770         .reset          = wakeup_tracer_reset,
 771         .start          = wakeup_tracer_start,
 772         .stop           = wakeup_tracer_stop,
 773         .print_max      = true,
 774         .print_header   = wakeup_print_header,
 775         .print_line     = wakeup_print_line,
 776         .flag_changed   = wakeup_flag_changed,
 777 #ifdef CONFIG_FTRACE_SELFTEST
 778         .selftest    = trace_selftest_startup_wakeup,
 779 #endif
 780         .open           = wakeup_trace_open,
 781         .close          = wakeup_trace_close,
 782         .allow_instances = true,
 783         .use_max_tr     = true,
 784 };
 785
 786 static struct tracer wakeup_dl_tracer __read_mostly =
 787 {
 788         .name           = "wakeup_dl",
 789         .init           = wakeup_dl_tracer_init,
 790         .reset          = wakeup_tracer_reset,
 791         .start          = wakeup_tracer_start,
 792         .stop           = wakeup_tracer_stop,
 793         .print_max      = true,
 794         .print_header   = wakeup_print_header,
 795         .print_line     = wakeup_print_line,
 796         .flag_changed   = wakeup_flag_changed,
 797 #ifdef CONFIG_FTRACE_SELFTEST
 798         .selftest    = trace_selftest_startup_wakeup,
 799 #endif
 800         .open           = wakeup_trace_open,
 801         .close          = wakeup_trace_close,
 802         .allow_instances = true,
 803         .use_max_tr     = true,
 804 };
 805
 806 __init static int init_wakeup_tracer(void)
 807 {
 808         int ret;
 809
 810         ret = register_tracer(&wakeup_tracer);
 811         if (ret)
 812                 return ret;
 813
 814         ret = register_tracer(&wakeup_rt_tracer);
 815         if (ret)
 816                 return ret;
 817
 818         ret = register_tracer(&wakeup_dl_tracer);
 819         if (ret)
 820                 return ret;
 821
 822         return 0;
 823 }
 824 core_initcall(init_wakeup_tracer);