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
  39 static int save_flags;
  40
  41 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  42 static int wakeup_display_graph(struct trace_array *tr, int set);
  43 # define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
  44 #else
  45 static inline int wakeup_display_graph(struct trace_array *tr, int set)
  46 {
  47         return 0;
  48 }
  49 # define is_graph(tr) false
  50 #endif
  51
  52
  53 #ifdef CONFIG_FUNCTION_TRACER
  54
  55 static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
  56 static void wakeup_graph_return(struct ftrace_graph_ret *trace);
  57
  58 static bool function_enabled;
  59
  60 /*
  61  * Prologue for the wakeup function tracers.
  62  *
  63  * Returns 1 if it is OK to continue, and preemption
  64  *            is disabled and data->disabled is incremented.
  65  *         0 if the trace is to be ignored, and preemption
  66  *            is not disabled and data->disabled is
  67  *            kept the same.
  68  *
  69  * Note, this function is also used outside this ifdef but
  70  *  inside the #ifdef of the function graph tracer below.
  71  *  This is OK, since the function graph tracer is
  72  *  dependent on the function tracer.
  73  */
  74 static int
  75 func_prolog_preempt_disable(struct trace_array *tr,
  76                             struct trace_array_cpu **data,
  77                             int *pc)
  78 {
  79         long disabled;
  80         int cpu;
  81
  82         if (likely(!wakeup_task))
  83                 return 0;
  84
  85         *pc = preempt_count();
  86         preempt_disable_notrace();
  87
  88         cpu = raw_smp_processor_id();
  89         if (cpu != wakeup_current_cpu)
  90                 goto out_enable;
  91
  92         *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
  93         disabled = atomic_inc_return(&(*data)->disabled);
  94         if (unlikely(disabled != 1))
  95                 goto out;
  96
  97         return 1;
  98
  99 out:
 100         atomic_dec(&(*data)->disabled);
 101
 102 out_enable:
 103         preempt_enable_notrace();
 104         return 0;
 105 }
 106
 107 /*
 108  * wakeup uses its own tracer function to keep the overhead down:
 109  */
 110 static void
 111 wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
 112                    struct ftrace_ops *op, struct pt_regs *pt_regs)
 113 {
 114         struct trace_array *tr = wakeup_trace;
 115         struct trace_array_cpu *data;
 116         unsigned long flags;
 117         int pc;
 118
 119         if (!func_prolog_preempt_disable(tr, &data, &pc))
 120                 return;
 121
 122         local_irq_save(flags);
 123         trace_function(tr, ip, parent_ip, flags, pc);
 124         local_irq_restore(flags);
 125
 126         atomic_dec(&data->disabled);
 127         preempt_enable_notrace();
 128 }
 129
 130 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
 131 {
 132         int ret;
 133
 134         /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
 135         if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
 136                 return 0;
 137
 138         if (graph)
 139                 ret = register_ftrace_graph(&wakeup_graph_return,
 140                                             &wakeup_graph_entry);
 141         else
 142                 ret = register_ftrace_function(tr->ops);
 143
 144         if (!ret)
 145                 function_enabled = true;
 146
 147         return ret;
 148 }
 149
 150 static void unregister_wakeup_function(struct trace_array *tr, int graph)
 151 {
 152         if (!function_enabled)
 153                 return;
 154
 155         if (graph)
 156                 unregister_ftrace_graph();
 157         else
 158                 unregister_ftrace_function(tr->ops);
 159
 160         function_enabled = false;
 161 }
 162
 163 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
 164 {
 165         if (!(mask & TRACE_ITER_FUNCTION))
 166                 return 0;
 167
 168         if (set)
 169                 register_wakeup_function(tr, is_graph(tr), 1);
 170         else
 171                 unregister_wakeup_function(tr, is_graph(tr));
 172         return 1;
 173 }
 174 #else
 175 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
 176 {
 177         return 0;
 178 }
 179 static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
 180 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
 181 {
 182         return 0;
 183 }
 184 #endif /* CONFIG_FUNCTION_TRACER */
 185
 186 static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
 187 {
 188         struct tracer *tracer = tr->current_trace;
 189
 190         if (wakeup_function_set(tr, mask, set))
 191                 return 0;
 192
 193 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 194         if (mask & TRACE_ITER_DISPLAY_GRAPH)
 195                 return wakeup_display_graph(tr, set);
 196 #endif
 197
 198         return trace_keep_overwrite(tracer, mask, set);
 199 }
 200
 201 static int start_func_tracer(struct trace_array *tr, int graph)
 202 {
 203         int ret;
 204
 205         ret = register_wakeup_function(tr, graph, 0);
 206
 207         if (!ret && tracing_is_enabled())
 208                 tracer_enabled = 1;
 209         else
 210                 tracer_enabled = 0;
 211
 212         return ret;
 213 }
 214
 215 static void stop_func_tracer(struct trace_array *tr, int graph)
 216 {
 217         tracer_enabled = 0;
 218
 219         unregister_wakeup_function(tr, graph);
 220 }
 221
 222 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 223 static int wakeup_display_graph(struct trace_array *tr, int set)
 224 {
 225         if (!(is_graph(tr) ^ set))
 226                 return 0;
 227
 228         stop_func_tracer(tr, !set);
 229
 230         wakeup_reset(wakeup_trace);
 231         tr->max_latency = 0;
 232
 233         return start_func_tracer(tr, set);
 234 }
 235
 236 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
 237 {
 238         struct trace_array *tr = wakeup_trace;
 239         struct trace_array_cpu *data;
 240         unsigned long flags;
 241         int pc, ret = 0;
 242
 243         if (ftrace_graph_ignore_func(trace))
 244                 return 0;
 245         /*
 246          * Do not trace a function if it's filtered by set_graph_notrace.
 247          * Make the index of ret stack negative to indicate that it should
 248          * ignore further functions.  But it needs its own ret stack entry
 249          * to recover the original index in order to continue tracing after
 250          * returning from the function.
 251          */
 252         if (ftrace_graph_notrace_addr(trace->func))
 253                 return 1;
 254
 255         if (!func_prolog_preempt_disable(tr, &data, &pc))
 256                 return 0;
 257
 258         local_save_flags(flags);
 259         ret = __trace_graph_entry(tr, trace, flags, pc);
 260         atomic_dec(&data->disabled);
 261         preempt_enable_notrace();
 262
 263         return ret;
 264 }
 265
 266 static void wakeup_graph_return(struct ftrace_graph_ret *trace)
 267 {
 268         struct trace_array *tr = wakeup_trace;
 269         struct trace_array_cpu *data;
 270         unsigned long flags;
 271         int pc;
 272
 273         if (!func_prolog_preempt_disable(tr, &data, &pc))
 274                 return;
 275
 276         local_save_flags(flags);
 277         __trace_graph_return(tr, trace, flags, pc);
 278         atomic_dec(&data->disabled);
 279
 280         preempt_enable_notrace();
 281         return;
 282 }
 283
 284 static void wakeup_trace_open(struct trace_iterator *iter)
 285 {
 286         if (is_graph(iter->tr))
 287                 graph_trace_open(iter);
 288 }
 289
 290 static void wakeup_trace_close(struct trace_iterator *iter)
 291 {
 292         if (iter->private)
 293                 graph_trace_close(iter);
 294 }
 295
 296 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
 297                             TRACE_GRAPH_PRINT_ABS_TIME | \
 298                             TRACE_GRAPH_PRINT_DURATION)
 299
 300 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 301 {
 302         /*
 303          * In graph mode call the graph tracer output function,
 304          * otherwise go with the TRACE_FN event handler
 305          */
 306         if (is_graph(iter->tr))
 307                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
 308
 309         return TRACE_TYPE_UNHANDLED;
 310 }
 311
 312 static void wakeup_print_header(struct seq_file *s)
 313 {
 314         if (is_graph(wakeup_trace))
 315                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
 316         else
 317                 trace_default_header(s);
 318 }
 319
 320 static void
 321 __trace_function(struct trace_array *tr,
 322                  unsigned long ip, unsigned long parent_ip,
 323                  unsigned long flags, int pc)
 324 {
 325         if (is_graph(tr))
 326                 trace_graph_function(tr, ip, parent_ip, flags, pc);
 327         else
 328                 trace_function(tr, ip, parent_ip, flags, pc);
 329 }
 330 #else
 331 #define __trace_function trace_function
 332
 333 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 334 {
 335         return TRACE_TYPE_UNHANDLED;
 336 }
 337
 338 static void wakeup_trace_open(struct trace_iterator *iter) { }
 339 static void wakeup_trace_close(struct trace_iterator *iter) { }
 340
 341 #ifdef CONFIG_FUNCTION_TRACER
 342 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
 343 {
 344         return -1;
 345 }
 346 static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
 347 static void wakeup_print_header(struct seq_file *s)
 348 {
 349         trace_default_header(s);
 350 }
 351 #else
 352 static void wakeup_print_header(struct seq_file *s)
 353 {
 354         trace_latency_header(s);
 355 }
 356 #endif /* CONFIG_FUNCTION_TRACER */
 357 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 358
 359 /*
 360  * Should this new latency be reported/recorded?
 361  */
 362 static bool report_latency(struct trace_array *tr, u64 delta)
 363 {
 364         if (tracing_thresh) {
 365                 if (delta < tracing_thresh)
 366                         return false;
 367         } else {
 368                 if (delta <= tr->max_latency)
 369                         return false;
 370         }
 371         return true;
 372 }
 373
 374 static void
 375 probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
 376 {
 377         if (task != wakeup_task)
 378                 return;
 379
 380         wakeup_current_cpu = cpu;
 381 }
 382
 383 static void
 384 tracing_sched_switch_trace(struct trace_array *tr,
 385                            struct task_struct *prev,
 386                            struct task_struct *next,
 387                            unsigned long flags, int pc)
 388 {
 389         struct trace_event_call *call = &event_context_switch;
 390         struct ring_buffer *buffer = tr->trace_buffer.buffer;
 391         struct ring_buffer_event *event;
 392         struct ctx_switch_entry *entry;
 393
 394         event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
 395                                           sizeof(*entry), flags, pc);
 396         if (!event)
 397                 return;
 398         entry   = ring_buffer_event_data(event);
 399         entry->prev_pid                 = prev->pid;
 400         entry->prev_prio                = prev->prio;
 401         entry->prev_state               = task_state_index(prev);
 402         entry->next_pid                 = next->pid;
 403         entry->next_prio                = next->prio;
 404         entry->next_state               = task_state_index(next);
 405         entry->next_cpu = task_cpu(next);
 406
 407         if (!call_filter_check_discard(call, entry, buffer, event))
 408                 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
 409 }
 410
 411 static void
 412 tracing_sched_wakeup_trace(struct trace_array *tr,
 413                            struct task_struct *wakee,
 414                            struct task_struct *curr,
 415                            unsigned long flags, int pc)
 416 {
 417         struct trace_event_call *call = &event_wakeup;
 418         struct ring_buffer_event *event;
 419         struct ctx_switch_entry *entry;
 420         struct ring_buffer *buffer = tr->trace_buffer.buffer;
 421
 422         event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
 423                                           sizeof(*entry), flags, pc);
 424         if (!event)
 425                 return;
 426         entry   = ring_buffer_event_data(event);
 427         entry->prev_pid                 = curr->pid;
 428         entry->prev_prio                = curr->prio;
 429         entry->prev_state               = task_state_index(curr);
 430         entry->next_pid                 = wakee->pid;
 431         entry->next_prio                = wakee->prio;
 432         entry->next_state               = task_state_index(wakee);
 433         entry->next_cpu                 = task_cpu(wakee);
 434
 435         if (!call_filter_check_discard(call, entry, buffer, event))
 436                 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
 437 }
 438
 439 static void notrace
 440 probe_wakeup_sched_switch(void *ignore, bool preempt,
 441                           struct task_struct *prev, struct task_struct *next)
 442 {
 443         struct trace_array_cpu *data;
 444         u64 T0, T1, delta;
 445         unsigned long flags;
 446         long disabled;
 447         int cpu;
 448         int pc;
 449
 450         tracing_record_cmdline(prev);
 451
 452         if (unlikely(!tracer_enabled))
 453                 return;
 454
 455         /*
 456          * When we start a new trace, we set wakeup_task to NULL
 457          * and then set tracer_enabled = 1. We want to make sure
 458          * that another CPU does not see the tracer_enabled = 1
 459          * and the wakeup_task with an older task, that might
 460          * actually be the same as next.
 461          */
 462         smp_rmb();
 463
 464         if (next != wakeup_task)
 465                 return;
 466
 467         pc = preempt_count();
 468
 469         /* disable local data, not wakeup_cpu data */
 470         cpu = raw_smp_processor_id();
 471         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 472         if (likely(disabled != 1))
 473                 goto out;
 474
 475         local_irq_save(flags);
 476         arch_spin_lock(&wakeup_lock);
 477
 478         /* We could race with grabbing wakeup_lock */
 479         if (unlikely(!tracer_enabled || next != wakeup_task))
 480                 goto out_unlock;
 481
 482         /* The task we are waiting for is waking up */
 483         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 484
 485         __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
 486         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 487
 488         T0 = data->preempt_timestamp;
 489         T1 = ftrace_now(cpu);
 490         delta = T1-T0;
 491
 492         if (!report_latency(wakeup_trace, delta))
 493                 goto out_unlock;
 494
 495         if (likely(!is_tracing_stopped())) {
 496                 wakeup_trace->max_latency = delta;
 497                 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
 498         }
 499
 500 out_unlock:
 501         __wakeup_reset(wakeup_trace);
 502         arch_spin_unlock(&wakeup_lock);
 503         local_irq_restore(flags);
 504 out:
 505         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 506 }
 507
 508 static void __wakeup_reset(struct trace_array *tr)
 509 {
 510         wakeup_cpu = -1;
 511         wakeup_prio = -1;
 512         tracing_dl = 0;
 513
 514         if (wakeup_task)
 515                 put_task_struct(wakeup_task);
 516
 517         wakeup_task = NULL;
 518 }
 519
 520 static void wakeup_reset(struct trace_array *tr)
 521 {
 522         unsigned long flags;
 523
 524         tracing_reset_online_cpus(&tr->trace_buffer);
 525
 526         local_irq_save(flags);
 527         arch_spin_lock(&wakeup_lock);
 528         __wakeup_reset(tr);
 529         arch_spin_unlock(&wakeup_lock);
 530         local_irq_restore(flags);
 531 }
 532
 533 static void
 534 probe_wakeup(void *ignore, struct task_struct *p)
 535 {
 536         struct trace_array_cpu *data;
 537         int cpu = smp_processor_id();
 538         unsigned long flags;
 539         long disabled;
 540         int pc;
 541
 542         if (likely(!tracer_enabled))
 543                 return;
 544
 545         tracing_record_cmdline(p);
 546         tracing_record_cmdline(current);
 547
 548         /*
 549          * Semantic is like this:
 550          *  - wakeup tracer handles all tasks in the system, independently
 551          *    from their scheduling class;
 552          *  - wakeup_rt tracer handles tasks belonging to sched_dl and
 553          *    sched_rt class;
 554          *  - wakeup_dl handles tasks belonging to sched_dl class only.
 555          */
 556         if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
 557             (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
 558             (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
 559                 return;
 560
 561         pc = preempt_count();
 562         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 563         if (unlikely(disabled != 1))
 564                 goto out;
 565
 566         /* interrupts should be off from try_to_wake_up */
 567         arch_spin_lock(&wakeup_lock);
 568
 569         /* check for races. */
 570         if (!tracer_enabled || tracing_dl ||
 571             (!dl_task(p) && p->prio >= wakeup_prio))
 572                 goto out_locked;
 573
 574         /* reset the trace */
 575         __wakeup_reset(wakeup_trace);
 576
 577         wakeup_cpu = task_cpu(p);
 578         wakeup_current_cpu = wakeup_cpu;
 579         wakeup_prio = p->prio;
 580
 581         /*
 582          * Once you start tracing a -deadline task, don't bother tracing
 583          * another task until the first one wakes up.
 584          */
 585         if (dl_task(p))
 586                 tracing_dl = 1;
 587         else
 588                 tracing_dl = 0;
 589
 590         wakeup_task = p;
 591         get_task_struct(wakeup_task);
 592
 593         local_save_flags(flags);
 594
 595         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 596         data->preempt_timestamp = ftrace_now(cpu);
 597         tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
 598
 599         /*
 600          * We must be careful in using CALLER_ADDR2. But since wake_up
 601          * is not called by an assembly function  (where as schedule is)
 602          * it should be safe to use it here.
 603          */
 604         __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
 605
 606 out_locked:
 607         arch_spin_unlock(&wakeup_lock);
 608 out:
 609         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 610 }
 611
 612 static void start_wakeup_tracer(struct trace_array *tr)
 613 {
 614         int ret;
 615
 616         ret = register_trace_sched_wakeup(probe_wakeup, NULL);
 617         if (ret) {
 618                 pr_info("wakeup trace: Couldn't activate tracepoint"
 619                         " probe to kernel_sched_wakeup\n");
 620                 return;
 621         }
 622
 623         ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
 624         if (ret) {
 625                 pr_info("wakeup trace: Couldn't activate tracepoint"
 626                         " probe to kernel_sched_wakeup_new\n");
 627                 goto fail_deprobe;
 628         }
 629
 630         ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 631         if (ret) {
 632                 pr_info("sched trace: Couldn't activate tracepoint"
 633                         " probe to kernel_sched_switch\n");
 634                 goto fail_deprobe_wake_new;
 635         }
 636
 637         ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 638         if (ret) {
 639                 pr_info("wakeup trace: Couldn't activate tracepoint"
 640                         " probe to kernel_sched_migrate_task\n");
 641                 return;
 642         }
 643
 644         wakeup_reset(tr);
 645
 646         /*
 647          * Don't let the tracer_enabled = 1 show up before
 648          * the wakeup_task is reset. This may be overkill since
 649          * wakeup_reset does a spin_unlock after setting the
 650          * wakeup_task to NULL, but I want to be safe.
 651          * This is a slow path anyway.
 652          */
 653         smp_wmb();
 654
 655         if (start_func_tracer(tr, is_graph(tr)))
 656                 printk(KERN_ERR "failed to start wakeup tracer\n");
 657
 658         return;
 659 fail_deprobe_wake_new:
 660         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 661 fail_deprobe:
 662         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 663 }
 664
 665 static void stop_wakeup_tracer(struct trace_array *tr)
 666 {
 667         tracer_enabled = 0;
 668         stop_func_tracer(tr, is_graph(tr));
 669         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 670         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 671         unregister_trace_sched_wakeup(probe_wakeup, NULL);
 672         unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
 673 }
 674
 675 static bool wakeup_busy;
 676
 677 static int __wakeup_tracer_init(struct trace_array *tr)
 678 {
 679         save_flags = tr->trace_flags;
 680
 681         /* non overwrite screws up the latency tracers */
 682         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
 683         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
 684
 685         tr->max_latency = 0;
 686         wakeup_trace = tr;
 687         ftrace_init_array_ops(tr, wakeup_tracer_call);
 688         start_wakeup_tracer(tr);
 689
 690         wakeup_busy = true;
 691         return 0;
 692 }
 693
 694 static int wakeup_tracer_init(struct trace_array *tr)
 695 {
 696         if (wakeup_busy)
 697                 return -EBUSY;
 698
 699         wakeup_dl = 0;
 700         wakeup_rt = 0;
 701         return __wakeup_tracer_init(tr);
 702 }
 703
 704 static int wakeup_rt_tracer_init(struct trace_array *tr)
 705 {
 706         if (wakeup_busy)
 707                 return -EBUSY;
 708
 709         wakeup_dl = 0;
 710         wakeup_rt = 1;
 711         return __wakeup_tracer_init(tr);
 712 }
 713
 714 static int wakeup_dl_tracer_init(struct trace_array *tr)
 715 {
 716         if (wakeup_busy)
 717                 return -EBUSY;
 718
 719         wakeup_dl = 1;
 720         wakeup_rt = 0;
 721         return __wakeup_tracer_init(tr);
 722 }
 723
 724 static void wakeup_tracer_reset(struct trace_array *tr)
 725 {
 726         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
 727         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
 728
 729         stop_wakeup_tracer(tr);
 730         /* make sure we put back any tasks we are tracing */
 731         wakeup_reset(tr);
 732
 733         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
 734         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
 735         ftrace_reset_array_ops(tr);
 736         wakeup_busy = false;
 737 }
 738
 739 static void wakeup_tracer_start(struct trace_array *tr)
 740 {
 741         wakeup_reset(tr);
 742         tracer_enabled = 1;
 743 }
 744
 745 static void wakeup_tracer_stop(struct trace_array *tr)
 746 {
 747         tracer_enabled = 0;
 748 }
 749
 750 static struct tracer wakeup_tracer __read_mostly =
 751 {
 752         .name           = "wakeup",
 753         .init           = wakeup_tracer_init,
 754         .reset          = wakeup_tracer_reset,
 755         .start          = wakeup_tracer_start,
 756         .stop           = wakeup_tracer_stop,
 757         .print_max      = true,
 758         .print_header   = wakeup_print_header,
 759         .print_line     = wakeup_print_line,
 760         .flag_changed   = wakeup_flag_changed,
 761 #ifdef CONFIG_FTRACE_SELFTEST
 762         .selftest    = trace_selftest_startup_wakeup,
 763 #endif
 764         .open           = wakeup_trace_open,
 765         .close          = wakeup_trace_close,
 766         .allow_instances = true,
 767         .use_max_tr     = true,
 768 };
 769
 770 static struct tracer wakeup_rt_tracer __read_mostly =
 771 {
 772         .name           = "wakeup_rt",
 773         .init           = wakeup_rt_tracer_init,
 774         .reset          = wakeup_tracer_reset,
 775         .start          = wakeup_tracer_start,
 776         .stop           = wakeup_tracer_stop,
 777         .print_max      = true,
 778         .print_header   = wakeup_print_header,
 779         .print_line     = wakeup_print_line,
 780         .flag_changed   = wakeup_flag_changed,
 781 #ifdef CONFIG_FTRACE_SELFTEST
 782         .selftest    = trace_selftest_startup_wakeup,
 783 #endif
 784         .open           = wakeup_trace_open,
 785         .close          = wakeup_trace_close,
 786         .allow_instances = true,
 787         .use_max_tr     = true,
 788 };
 789
 790 static struct tracer wakeup_dl_tracer __read_mostly =
 791 {
 792         .name           = "wakeup_dl",
 793         .init           = wakeup_dl_tracer_init,
 794         .reset          = wakeup_tracer_reset,
 795         .start          = wakeup_tracer_start,
 796         .stop           = wakeup_tracer_stop,
 797         .print_max      = true,
 798         .print_header   = wakeup_print_header,
 799         .print_line     = wakeup_print_line,
 800         .flag_changed   = wakeup_flag_changed,
 801 #ifdef CONFIG_FTRACE_SELFTEST
 802         .selftest    = trace_selftest_startup_wakeup,
 803 #endif
 804         .open           = wakeup_trace_open,
 805         .close          = wakeup_trace_close,
 806         .allow_instances = true,
 807         .use_max_tr     = true,
 808 };
 809
 810 __init static int init_wakeup_tracer(void)
 811 {
 812         int ret;
 813
 814         ret = register_tracer(&wakeup_tracer);
 815         if (ret)
 816                 return ret;
 817
 818         ret = register_tracer(&wakeup_rt_tracer);
 819         if (ret)
 820                 return ret;
 821
 822         ret = register_tracer(&wakeup_dl_tracer);
 823         if (ret)
 824                 return ret;
 825
 826         return 0;
 827 }
 828 core_initcall(init_wakeup_tracer);