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TOMOYO Linux Cross Reference
Linux/kernel/trace/trace_sched_wakeup.c

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  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 }
175 
176 static void wakeup_trace_close(struct trace_iterator *iter)
177 {
178         if (iter->private)
179                 graph_trace_close(iter);
180 }
181 
182 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
183                             TRACE_GRAPH_PRINT_CPU |  \
184                             TRACE_GRAPH_PRINT_REL_TIME | \
185                             TRACE_GRAPH_PRINT_DURATION | \
186                             TRACE_GRAPH_PRINT_OVERHEAD | \
187                             TRACE_GRAPH_PRINT_IRQS)
188 
189 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
190 {
191         /*
192          * In graph mode call the graph tracer output function,
193          * otherwise go with the TRACE_FN event handler
194          */
195         if (is_graph(iter->tr))
196                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
197 
198         return TRACE_TYPE_UNHANDLED;
199 }
200 
201 static void wakeup_print_header(struct seq_file *s)
202 {
203         if (is_graph(wakeup_trace))
204                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
205         else
206                 trace_default_header(s);
207 }
208 #endif /* else CONFIG_FUNCTION_GRAPH_TRACER */
209 
210 /*
211  * wakeup uses its own tracer function to keep the overhead down:
212  */
213 static void
214 wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
215                    struct ftrace_ops *op, struct pt_regs *pt_regs)
216 {
217         struct trace_array *tr = wakeup_trace;
218         struct trace_array_cpu *data;
219         unsigned long flags;
220         int pc;
221 
222         if (!func_prolog_preempt_disable(tr, &data, &pc))
223                 return;
224 
225         local_irq_save(flags);
226         trace_function(tr, ip, parent_ip, flags, pc);
227         local_irq_restore(flags);
228 
229         atomic_dec(&data->disabled);
230         preempt_enable_notrace();
231 }
232 
233 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
234 {
235         int ret;
236 
237         /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
238         if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
239                 return 0;
240 
241         if (graph)
242                 ret = register_ftrace_graph(&fgraph_wakeup_ops);
243         else
244                 ret = register_ftrace_function(tr->ops);
245 
246         if (!ret)
247                 function_enabled = true;
248 
249         return ret;
250 }
251 
252 static void unregister_wakeup_function(struct trace_array *tr, int graph)
253 {
254         if (!function_enabled)
255                 return;
256 
257         if (graph)
258                 unregister_ftrace_graph(&fgraph_wakeup_ops);
259         else
260                 unregister_ftrace_function(tr->ops);
261 
262         function_enabled = false;
263 }
264 
265 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
266 {
267         if (!(mask & TRACE_ITER_FUNCTION))
268                 return 0;
269 
270         if (set)
271                 register_wakeup_function(tr, is_graph(tr), 1);
272         else
273                 unregister_wakeup_function(tr, is_graph(tr));
274         return 1;
275 }
276 #else /* CONFIG_FUNCTION_TRACER */
277 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
278 {
279         return 0;
280 }
281 static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
282 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
283 {
284         return 0;
285 }
286 #endif /* else CONFIG_FUNCTION_TRACER */
287 
288 #ifndef CONFIG_FUNCTION_GRAPH_TRACER
289 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
290 {
291         return TRACE_TYPE_UNHANDLED;
292 }
293 
294 static void wakeup_trace_open(struct trace_iterator *iter) { }
295 static void wakeup_trace_close(struct trace_iterator *iter) { }
296 
297 static void wakeup_print_header(struct seq_file *s)
298 {
299         trace_default_header(s);
300 }
301 #endif /* !CONFIG_FUNCTION_GRAPH_TRACER */
302 
303 static void
304 __trace_function(struct trace_array *tr,
305                  unsigned long ip, unsigned long parent_ip,
306                  unsigned long flags, int pc)
307 {
308         if (is_graph(tr))
309                 trace_graph_function(tr, ip, parent_ip, flags, pc);
310         else
311                 trace_function(tr, ip, parent_ip, flags, pc);
312 }
313 
314 static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
315 {
316         struct tracer *tracer = tr->current_trace;
317 
318         if (wakeup_function_set(tr, mask, set))
319                 return 0;
320 
321 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
322         if (mask & TRACE_ITER_DISPLAY_GRAPH)
323                 return wakeup_display_graph(tr, set);
324 #endif
325 
326         return trace_keep_overwrite(tracer, mask, set);
327 }
328 
329 static int start_func_tracer(struct trace_array *tr, int graph)
330 {
331         int ret;
332 
333         ret = register_wakeup_function(tr, graph, 0);
334 
335         if (!ret && tracing_is_enabled())
336                 tracer_enabled = 1;
337         else
338                 tracer_enabled = 0;
339 
340         return ret;
341 }
342 
343 static void stop_func_tracer(struct trace_array *tr, int graph)
344 {
345         tracer_enabled = 0;
346 
347         unregister_wakeup_function(tr, graph);
348 }
349 
350 /*
351  * Should this new latency be reported/recorded?
352  */
353 static bool report_latency(struct trace_array *tr, u64 delta)
354 {
355         if (tracing_thresh) {
356                 if (delta < tracing_thresh)
357                         return false;
358         } else {
359                 if (delta <= tr->max_latency)
360                         return false;
361         }
362         return true;
363 }
364 
365 static void
366 probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
367 {
368         if (task != wakeup_task)
369                 return;
370 
371         wakeup_current_cpu = cpu;
372 }
373 
374 static void
375 tracing_sched_switch_trace(struct trace_array *tr,
376                            struct task_struct *prev,
377                            struct task_struct *next,
378                            unsigned long flags, int pc)
379 {
380         struct trace_event_call *call = &event_context_switch;
381         struct trace_buffer *buffer = tr->array_buffer.buffer;
382         struct ring_buffer_event *event;
383         struct ctx_switch_entry *entry;
384 
385         event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
386                                           sizeof(*entry), flags, pc);
387         if (!event)
388                 return;
389         entry   = ring_buffer_event_data(event);
390         entry->prev_pid                 = prev->pid;
391         entry->prev_prio                = prev->prio;
392         entry->prev_state               = task_state_index(prev);
393         entry->next_pid                 = next->pid;
394         entry->next_prio                = next->prio;
395         entry->next_state               = task_state_index(next);
396         entry->next_cpu = task_cpu(next);
397 
398         if (!call_filter_check_discard(call, entry, buffer, event))
399                 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
400 }
401 
402 static void
403 tracing_sched_wakeup_trace(struct trace_array *tr,
404                            struct task_struct *wakee,
405                            struct task_struct *curr,
406                            unsigned long flags, int pc)
407 {
408         struct trace_event_call *call = &event_wakeup;
409         struct ring_buffer_event *event;
410         struct ctx_switch_entry *entry;
411         struct trace_buffer *buffer = tr->array_buffer.buffer;
412 
413         event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
414                                           sizeof(*entry), flags, pc);
415         if (!event)
416                 return;
417         entry   = ring_buffer_event_data(event);
418         entry->prev_pid                 = curr->pid;
419         entry->prev_prio                = curr->prio;
420         entry->prev_state               = task_state_index(curr);
421         entry->next_pid                 = wakee->pid;
422         entry->next_prio                = wakee->prio;
423         entry->next_state               = task_state_index(wakee);
424         entry->next_cpu                 = task_cpu(wakee);
425 
426         if (!call_filter_check_discard(call, entry, buffer, event))
427                 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
428 }
429 
430 static void notrace
431 probe_wakeup_sched_switch(void *ignore, bool preempt,
432                           struct task_struct *prev, struct task_struct *next)
433 {
434         struct trace_array_cpu *data;
435         u64 T0, T1, delta;
436         unsigned long flags;
437         long disabled;
438         int cpu;
439         int pc;
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         pc = preempt_count();
459 
460         /* disable local data, not wakeup_cpu data */
461         cpu = raw_smp_processor_id();
462         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
463         if (likely(disabled != 1))
464                 goto out;
465 
466         local_irq_save(flags);
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, flags, pc);
477         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
478         __trace_stack(wakeup_trace, flags, 0, pc);
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 = 0;
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         unsigned long flags;
531         long disabled;
532         int pc;
533 
534         if (likely(!tracer_enabled))
535                 return;
536 
537         tracing_record_cmdline(p);
538         tracing_record_cmdline(current);
539 
540         /*
541          * Semantic is like this:
542          *  - wakeup tracer handles all tasks in the system, independently
543          *    from their scheduling class;
544          *  - wakeup_rt tracer handles tasks belonging to sched_dl and
545          *    sched_rt class;
546          *  - wakeup_dl handles tasks belonging to sched_dl class only.
547          */
548         if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
549             (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
550             (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
551                 return;
552 
553         pc = preempt_count();
554         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
555         if (unlikely(disabled != 1))
556                 goto out;
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 = 1;
579         else
580                 tracing_dl = 0;
581 
582         wakeup_task = get_task_struct(p);
583 
584         local_save_flags(flags);
585 
586         data = per_cpu_ptr(wakeup_trace->array_buffer.data, wakeup_cpu);
587         data->preempt_timestamp = ftrace_now(cpu);
588         tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
589         __trace_stack(wakeup_trace, flags, 0, pc);
590 
591         /*
592          * We must be careful in using CALLER_ADDR2. But since wake_up
593          * is not called by an assembly function  (where as schedule is)
594          * it should be safe to use it here.
595          */
596         __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
597 
598 out_locked:
599         arch_spin_unlock(&wakeup_lock);
600 out:
601         atomic_dec(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
602 }
603 
604 static void start_wakeup_tracer(struct trace_array *tr)
605 {
606         int ret;
607 
608         ret = register_trace_sched_wakeup(probe_wakeup, NULL);
609         if (ret) {
610                 pr_info("wakeup trace: Couldn't activate tracepoint"
611                         " probe to kernel_sched_wakeup\n");
612                 return;
613         }
614 
615         ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
616         if (ret) {
617                 pr_info("wakeup trace: Couldn't activate tracepoint"
618                         " probe to kernel_sched_wakeup_new\n");
619                 goto fail_deprobe;
620         }
621 
622         ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
623         if (ret) {
624                 pr_info("sched trace: Couldn't activate tracepoint"
625                         " probe to kernel_sched_switch\n");
626                 goto fail_deprobe_wake_new;
627         }
628 
629         ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
630         if (ret) {
631                 pr_info("wakeup trace: Couldn't activate tracepoint"
632                         " probe to kernel_sched_migrate_task\n");
633                 goto fail_deprobe_sched_switch;
634         }
635 
636         wakeup_reset(tr);
637 
638         /*
639          * Don't let the tracer_enabled = 1 show up before
640          * the wakeup_task is reset. This may be overkill since
641          * wakeup_reset does a spin_unlock after setting the
642          * wakeup_task to NULL, but I want to be safe.
643          * This is a slow path anyway.
644          */
645         smp_wmb();
646 
647         if (start_func_tracer(tr, is_graph(tr)))
648                 printk(KERN_ERR "failed to start wakeup tracer\n");
649 
650         return;
651 fail_deprobe_sched_switch:
652         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
653 fail_deprobe_wake_new:
654         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
655 fail_deprobe:
656         unregister_trace_sched_wakeup(probe_wakeup, NULL);
657 }
658 
659 static void stop_wakeup_tracer(struct trace_array *tr)
660 {
661         tracer_enabled = 0;
662         stop_func_tracer(tr, is_graph(tr));
663         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
664         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
665         unregister_trace_sched_wakeup(probe_wakeup, NULL);
666         unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
667 }
668 
669 static bool wakeup_busy;
670 
671 static int __wakeup_tracer_init(struct trace_array *tr)
672 {
673         save_flags = tr->trace_flags;
674 
675         /* non overwrite screws up the latency tracers */
676         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
677         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
678 
679         tr->max_latency = 0;
680         wakeup_trace = tr;
681         ftrace_init_array_ops(tr, wakeup_tracer_call);
682         start_wakeup_tracer(tr);
683 
684         wakeup_busy = true;
685         return 0;
686 }
687 
688 static int wakeup_tracer_init(struct trace_array *tr)
689 {
690         if (wakeup_busy)
691                 return -EBUSY;
692 
693         wakeup_dl = 0;
694         wakeup_rt = 0;
695         return __wakeup_tracer_init(tr);
696 }
697 
698 static int wakeup_rt_tracer_init(struct trace_array *tr)
699 {
700         if (wakeup_busy)
701                 return -EBUSY;
702 
703         wakeup_dl = 0;
704         wakeup_rt = 1;
705         return __wakeup_tracer_init(tr);
706 }
707 
708 static int wakeup_dl_tracer_init(struct trace_array *tr)
709 {
710         if (wakeup_busy)
711                 return -EBUSY;
712 
713         wakeup_dl = 1;
714         wakeup_rt = 0;
715         return __wakeup_tracer_init(tr);
716 }
717 
718 static void wakeup_tracer_reset(struct trace_array *tr)
719 {
720         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
721         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
722 
723         stop_wakeup_tracer(tr);
724         /* make sure we put back any tasks we are tracing */
725         wakeup_reset(tr);
726 
727         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
728         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
729         ftrace_reset_array_ops(tr);
730         wakeup_busy = false;
731 }
732 
733 static void wakeup_tracer_start(struct trace_array *tr)
734 {
735         wakeup_reset(tr);
736         tracer_enabled = 1;
737 }
738 
739 static void wakeup_tracer_stop(struct trace_array *tr)
740 {
741         tracer_enabled = 0;
742 }
743 
744 static struct tracer wakeup_tracer __read_mostly =
745 {
746         .name           = "wakeup",
747         .init           = wakeup_tracer_init,
748         .reset          = wakeup_tracer_reset,
749         .start          = wakeup_tracer_start,
750         .stop           = wakeup_tracer_stop,
751         .print_max      = true,
752         .print_header   = wakeup_print_header,
753         .print_line     = wakeup_print_line,
754         .flag_changed   = wakeup_flag_changed,
755 #ifdef CONFIG_FTRACE_SELFTEST
756         .selftest    = trace_selftest_startup_wakeup,
757 #endif
758         .open           = wakeup_trace_open,
759         .close          = wakeup_trace_close,
760         .allow_instances = true,
761         .use_max_tr     = true,
762 };
763 
764 static struct tracer wakeup_rt_tracer __read_mostly =
765 {
766         .name           = "wakeup_rt",
767         .init           = wakeup_rt_tracer_init,
768         .reset          = wakeup_tracer_reset,
769         .start          = wakeup_tracer_start,
770         .stop           = wakeup_tracer_stop,
771         .print_max      = true,
772         .print_header   = wakeup_print_header,
773         .print_line     = wakeup_print_line,
774         .flag_changed   = wakeup_flag_changed,
775 #ifdef CONFIG_FTRACE_SELFTEST
776         .selftest    = trace_selftest_startup_wakeup,
777 #endif
778         .open           = wakeup_trace_open,
779         .close          = wakeup_trace_close,
780         .allow_instances = true,
781         .use_max_tr     = true,
782 };
783 
784 static struct tracer wakeup_dl_tracer __read_mostly =
785 {
786         .name           = "wakeup_dl",
787         .init           = wakeup_dl_tracer_init,
788         .reset          = wakeup_tracer_reset,
789         .start          = wakeup_tracer_start,
790         .stop           = wakeup_tracer_stop,
791         .print_max      = true,
792         .print_header   = wakeup_print_header,
793         .print_line     = wakeup_print_line,
794         .flag_changed   = wakeup_flag_changed,
795 #ifdef CONFIG_FTRACE_SELFTEST
796         .selftest    = trace_selftest_startup_wakeup,
797 #endif
798         .open           = wakeup_trace_open,
799         .close          = wakeup_trace_close,
800         .allow_instances = true,
801         .use_max_tr     = true,
802 };
803 
804 __init static int init_wakeup_tracer(void)
805 {
806         int ret;
807 
808         ret = register_tracer(&wakeup_tracer);
809         if (ret)
810                 return ret;
811 
812         ret = register_tracer(&wakeup_rt_tracer);
813         if (ret)
814                 return ret;
815 
816         ret = register_tracer(&wakeup_dl_tracer);
817         if (ret)
818                 return ret;
819 
820         return 0;
821 }
822 core_initcall(init_wakeup_tracer);
823 

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