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