1 /*
2  * trace task wakeup timings
3  *
4  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
6  *
7  * Based on code from the latency_tracer, that is:
8  *
9  *  Copyright (C) 2004-2006 Ingo Molnar
10  *  Copyright (C) 2004 Nadia Yvette Chambers
11  */
12 #include <linux/module.h>
13 #include <linux/kallsyms.h>
14 #include <linux/uaccess.h>
15 #include <linux/ftrace.h>
16 #include <linux/sched/rt.h>
17 #include <linux/sched/deadline.h>
18 #include <trace/events/sched.h>
19 #include "trace.h"
20 
21 static struct trace_array	*wakeup_trace;
22 static int __read_mostly	tracer_enabled;
23 
24 static struct task_struct	*wakeup_task;
25 static int			wakeup_cpu;
26 static int			wakeup_current_cpu;
27 static unsigned			wakeup_prio = -1;
28 static int			wakeup_rt;
29 static int			wakeup_dl;
30 static int			tracing_dl = 0;
31 
32 static arch_spinlock_t wakeup_lock =
33 	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
34 
35 static void wakeup_reset(struct trace_array *tr);
36 static void __wakeup_reset(struct trace_array *tr);
37 
38 static int save_flags;
39 
40 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
41 static int wakeup_display_graph(struct trace_array *tr, int set);
42 # define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
43 #else
44 static inline int wakeup_display_graph(struct trace_array *tr, int set)
45 {
46 	return 0;
47 }
48 # define is_graph(tr) false
49 #endif
50 
51 
52 #ifdef CONFIG_FUNCTION_TRACER
53 
54 static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
55 static void wakeup_graph_return(struct ftrace_graph_ret *trace);
56 
57 static bool function_enabled;
58 
59 /*
60  * Prologue for the wakeup function tracers.
61  *
62  * Returns 1 if it is OK to continue, and preemption
63  *            is disabled and data->disabled is incremented.
64  *         0 if the trace is to be ignored, and preemption
65  *            is not disabled and data->disabled is
66  *            kept the same.
67  *
68  * Note, this function is also used outside this ifdef but
69  *  inside the #ifdef of the function graph tracer below.
70  *  This is OK, since the function graph tracer is
71  *  dependent on the function tracer.
72  */
73 static int
74 func_prolog_preempt_disable(struct trace_array *tr,
75 			    struct trace_array_cpu **data,
76 			    int *pc)
77 {
78 	long disabled;
79 	int cpu;
80 
81 	if (likely(!wakeup_task))
82 		return 0;
83 
84 	*pc = preempt_count();
85 	preempt_disable_notrace();
86 
87 	cpu = raw_smp_processor_id();
88 	if (cpu != wakeup_current_cpu)
89 		goto out_enable;
90 
91 	*data = per_cpu_ptr(tr->trace_buffer.data, cpu);
92 	disabled = atomic_inc_return(&(*data)->disabled);
93 	if (unlikely(disabled != 1))
94 		goto out;
95 
96 	return 1;
97 
98 out:
99 	atomic_dec(&(*data)->disabled);
100 
101 out_enable:
102 	preempt_enable_notrace();
103 	return 0;
104 }
105 
106 /*
107  * wakeup uses its own tracer function to keep the overhead down:
108  */
109 static void
110 wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
111 		   struct ftrace_ops *op, struct pt_regs *pt_regs)
112 {
113 	struct trace_array *tr = wakeup_trace;
114 	struct trace_array_cpu *data;
115 	unsigned long flags;
116 	int pc;
117 
118 	if (!func_prolog_preempt_disable(tr, &data, &pc))
119 		return;
120 
121 	local_irq_save(flags);
122 	trace_function(tr, ip, parent_ip, flags, pc);
123 	local_irq_restore(flags);
124 
125 	atomic_dec(&data->disabled);
126 	preempt_enable_notrace();
127 }
128 
129 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
130 {
131 	int ret;
132 
133 	/* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
134 	if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
135 		return 0;
136 
137 	if (graph)
138 		ret = register_ftrace_graph(&wakeup_graph_return,
139 					    &wakeup_graph_entry);
140 	else
141 		ret = register_ftrace_function(tr->ops);
142 
143 	if (!ret)
144 		function_enabled = true;
145 
146 	return ret;
147 }
148 
149 static void unregister_wakeup_function(struct trace_array *tr, int graph)
150 {
151 	if (!function_enabled)
152 		return;
153 
154 	if (graph)
155 		unregister_ftrace_graph();
156 	else
157 		unregister_ftrace_function(tr->ops);
158 
159 	function_enabled = false;
160 }
161 
162 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
163 {
164 	if (!(mask & TRACE_ITER_FUNCTION))
165 		return 0;
166 
167 	if (set)
168 		register_wakeup_function(tr, is_graph(tr), 1);
169 	else
170 		unregister_wakeup_function(tr, is_graph(tr));
171 	return 1;
172 }
173 #else
174 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
175 {
176 	return 0;
177 }
178 static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
179 static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
180 {
181 	return 0;
182 }
183 #endif /* CONFIG_FUNCTION_TRACER */
184 
185 static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
186 {
187 	struct tracer *tracer = tr->current_trace;
188 
189 	if (wakeup_function_set(tr, mask, set))
190 		return 0;
191 
192 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
193 	if (mask & TRACE_ITER_DISPLAY_GRAPH)
194 		return wakeup_display_graph(tr, set);
195 #endif
196 
197 	return trace_keep_overwrite(tracer, mask, set);
198 }
199 
200 static int start_func_tracer(struct trace_array *tr, int graph)
201 {
202 	int ret;
203 
204 	ret = register_wakeup_function(tr, graph, 0);
205 
206 	if (!ret && tracing_is_enabled())
207 		tracer_enabled = 1;
208 	else
209 		tracer_enabled = 0;
210 
211 	return ret;
212 }
213 
214 static void stop_func_tracer(struct trace_array *tr, int graph)
215 {
216 	tracer_enabled = 0;
217 
218 	unregister_wakeup_function(tr, graph);
219 }
220 
221 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
222 static int wakeup_display_graph(struct trace_array *tr, int set)
223 {
224 	if (!(is_graph(tr) ^ set))
225 		return 0;
226 
227 	stop_func_tracer(tr, !set);
228 
229 	wakeup_reset(wakeup_trace);
230 	tr->max_latency = 0;
231 
232 	return start_func_tracer(tr, set);
233 }
234 
235 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
236 {
237 	struct trace_array *tr = wakeup_trace;
238 	struct trace_array_cpu *data;
239 	unsigned long flags;
240 	int pc, ret = 0;
241 
242 	if (ftrace_graph_ignore_func(trace))
243 		return 0;
244 	/*
245 	 * Do not trace a function if it's filtered by set_graph_notrace.
246 	 * Make the index of ret stack negative to indicate that it should
247 	 * ignore further functions.  But it needs its own ret stack entry
248 	 * to recover the original index in order to continue tracing after
249 	 * returning from the function.
250 	 */
251 	if (ftrace_graph_notrace_addr(trace->func))
252 		return 1;
253 
254 	if (!func_prolog_preempt_disable(tr, &data, &pc))
255 		return 0;
256 
257 	local_save_flags(flags);
258 	ret = __trace_graph_entry(tr, trace, flags, pc);
259 	atomic_dec(&data->disabled);
260 	preempt_enable_notrace();
261 
262 	return ret;
263 }
264 
265 static void wakeup_graph_return(struct ftrace_graph_ret *trace)
266 {
267 	struct trace_array *tr = wakeup_trace;
268 	struct trace_array_cpu *data;
269 	unsigned long flags;
270 	int pc;
271 
272 	if (!func_prolog_preempt_disable(tr, &data, &pc))
273 		return;
274 
275 	local_save_flags(flags);
276 	__trace_graph_return(tr, trace, flags, pc);
277 	atomic_dec(&data->disabled);
278 
279 	preempt_enable_notrace();
280 	return;
281 }
282 
283 static void wakeup_trace_open(struct trace_iterator *iter)
284 {
285 	if (is_graph(iter->tr))
286 		graph_trace_open(iter);
287 }
288 
289 static void wakeup_trace_close(struct trace_iterator *iter)
290 {
291 	if (iter->private)
292 		graph_trace_close(iter);
293 }
294 
295 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
296 			    TRACE_GRAPH_PRINT_ABS_TIME | \
297 			    TRACE_GRAPH_PRINT_DURATION)
298 
299 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
300 {
301 	/*
302 	 * In graph mode call the graph tracer output function,
303 	 * otherwise go with the TRACE_FN event handler
304 	 */
305 	if (is_graph(iter->tr))
306 		return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
307 
308 	return TRACE_TYPE_UNHANDLED;
309 }
310 
311 static void wakeup_print_header(struct seq_file *s)
312 {
313 	if (is_graph(wakeup_trace))
314 		print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
315 	else
316 		trace_default_header(s);
317 }
318 
319 static void
320 __trace_function(struct trace_array *tr,
321 		 unsigned long ip, unsigned long parent_ip,
322 		 unsigned long flags, int pc)
323 {
324 	if (is_graph(tr))
325 		trace_graph_function(tr, ip, parent_ip, flags, pc);
326 	else
327 		trace_function(tr, ip, parent_ip, flags, pc);
328 }
329 #else
330 #define __trace_function trace_function
331 
332 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
333 {
334 	return TRACE_TYPE_UNHANDLED;
335 }
336 
337 static void wakeup_trace_open(struct trace_iterator *iter) { }
338 static void wakeup_trace_close(struct trace_iterator *iter) { }
339 
340 #ifdef CONFIG_FUNCTION_TRACER
341 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
342 {
343 	return -1;
344 }
345 static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
346 static void wakeup_print_header(struct seq_file *s)
347 {
348 	trace_default_header(s);
349 }
350 #else
351 static void wakeup_print_header(struct seq_file *s)
352 {
353 	trace_latency_header(s);
354 }
355 #endif /* CONFIG_FUNCTION_TRACER */
356 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
357 
358 /*
359  * Should this new latency be reported/recorded?
360  */
361 static bool report_latency(struct trace_array *tr, u64 delta)
362 {
363 	if (tracing_thresh) {
364 		if (delta < tracing_thresh)
365 			return false;
366 	} else {
367 		if (delta <= tr->max_latency)
368 			return false;
369 	}
370 	return true;
371 }
372 
373 static void
374 probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
375 {
376 	if (task != wakeup_task)
377 		return;
378 
379 	wakeup_current_cpu = cpu;
380 }
381 
382 static void
383 tracing_sched_switch_trace(struct trace_array *tr,
384 			   struct task_struct *prev,
385 			   struct task_struct *next,
386 			   unsigned long flags, int pc)
387 {
388 	struct trace_event_call *call = &event_context_switch;
389 	struct ring_buffer *buffer = tr->trace_buffer.buffer;
390 	struct ring_buffer_event *event;
391 	struct ctx_switch_entry *entry;
392 
393 	event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
394 					  sizeof(*entry), flags, pc);
395 	if (!event)
396 		return;
397 	entry	= ring_buffer_event_data(event);
398 	entry->prev_pid			= prev->pid;
399 	entry->prev_prio		= prev->prio;
400 	entry->prev_state		= prev->state;
401 	entry->next_pid			= next->pid;
402 	entry->next_prio		= next->prio;
403 	entry->next_state		= next->state;
404 	entry->next_cpu	= task_cpu(next);
405 
406 	if (!call_filter_check_discard(call, entry, buffer, event))
407 		trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
408 }
409 
410 static void
411 tracing_sched_wakeup_trace(struct trace_array *tr,
412 			   struct task_struct *wakee,
413 			   struct task_struct *curr,
414 			   unsigned long flags, int pc)
415 {
416 	struct trace_event_call *call = &event_wakeup;
417 	struct ring_buffer_event *event;
418 	struct ctx_switch_entry *entry;
419 	struct ring_buffer *buffer = tr->trace_buffer.buffer;
420 
421 	event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
422 					  sizeof(*entry), flags, pc);
423 	if (!event)
424 		return;
425 	entry	= ring_buffer_event_data(event);
426 	entry->prev_pid			= curr->pid;
427 	entry->prev_prio		= curr->prio;
428 	entry->prev_state		= curr->state;
429 	entry->next_pid			= wakee->pid;
430 	entry->next_prio		= wakee->prio;
431 	entry->next_state		= wakee->state;
432 	entry->next_cpu			= task_cpu(wakee);
433 
434 	if (!call_filter_check_discard(call, entry, buffer, event))
435 		trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
436 }
437 
438 static void notrace
439 probe_wakeup_sched_switch(void *ignore, bool preempt,
440 			  struct task_struct *prev, struct task_struct *next)
441 {
442 	struct trace_array_cpu *data;
443 	u64 T0, T1, delta;
444 	unsigned long flags;
445 	long disabled;
446 	int cpu;
447 	int pc;
448 
449 	tracing_record_cmdline(prev);
450 
451 	if (unlikely(!tracer_enabled))
452 		return;
453 
454 	/*
455 	 * When we start a new trace, we set wakeup_task to NULL
456 	 * and then set tracer_enabled = 1. We want to make sure
457 	 * that another CPU does not see the tracer_enabled = 1
458 	 * and the wakeup_task with an older task, that might
459 	 * actually be the same as next.
460 	 */
461 	smp_rmb();
462 
463 	if (next != wakeup_task)
464 		return;
465 
466 	pc = preempt_count();
467 
468 	/* disable local data, not wakeup_cpu data */
469 	cpu = raw_smp_processor_id();
470 	disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
471 	if (likely(disabled != 1))
472 		goto out;
473 
474 	local_irq_save(flags);
475 	arch_spin_lock(&wakeup_lock);
476 
477 	/* We could race with grabbing wakeup_lock */
478 	if (unlikely(!tracer_enabled || next != wakeup_task))
479 		goto out_unlock;
480 
481 	/* The task we are waiting for is waking up */
482 	data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
483 
484 	__trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
485 	tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
486 
487 	T0 = data->preempt_timestamp;
488 	T1 = ftrace_now(cpu);
489 	delta = T1-T0;
490 
491 	if (!report_latency(wakeup_trace, delta))
492 		goto out_unlock;
493 
494 	if (likely(!is_tracing_stopped())) {
495 		wakeup_trace->max_latency = delta;
496 		update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
497 	}
498 
499 out_unlock:
500 	__wakeup_reset(wakeup_trace);
501 	arch_spin_unlock(&wakeup_lock);
502 	local_irq_restore(flags);
503 out:
504 	atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
505 }
506 
507 static void __wakeup_reset(struct trace_array *tr)
508 {
509 	wakeup_cpu = -1;
510 	wakeup_prio = -1;
511 	tracing_dl = 0;
512 
513 	if (wakeup_task)
514 		put_task_struct(wakeup_task);
515 
516 	wakeup_task = NULL;
517 }
518 
519 static void wakeup_reset(struct trace_array *tr)
520 {
521 	unsigned long flags;
522 
523 	tracing_reset_online_cpus(&tr->trace_buffer);
524 
525 	local_irq_save(flags);
526 	arch_spin_lock(&wakeup_lock);
527 	__wakeup_reset(tr);
528 	arch_spin_unlock(&wakeup_lock);
529 	local_irq_restore(flags);
530 }
531 
532 static void
533 probe_wakeup(void *ignore, struct task_struct *p)
534 {
535 	struct trace_array_cpu *data;
536 	int cpu = smp_processor_id();
537 	unsigned long flags;
538 	long disabled;
539 	int pc;
540 
541 	if (likely(!tracer_enabled))
542 		return;
543 
544 	tracing_record_cmdline(p);
545 	tracing_record_cmdline(current);
546 
547 	/*
548 	 * Semantic is like this:
549 	 *  - wakeup tracer handles all tasks in the system, independently
550 	 *    from their scheduling class;
551 	 *  - wakeup_rt tracer handles tasks belonging to sched_dl and
552 	 *    sched_rt class;
553 	 *  - wakeup_dl handles tasks belonging to sched_dl class only.
554 	 */
555 	if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
556 	    (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
557 	    (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
558 		return;
559 
560 	pc = preempt_count();
561 	disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
562 	if (unlikely(disabled != 1))
563 		goto out;
564 
565 	/* interrupts should be off from try_to_wake_up */
566 	arch_spin_lock(&wakeup_lock);
567 
568 	/* check for races. */
569 	if (!tracer_enabled || tracing_dl ||
570 	    (!dl_task(p) && p->prio >= wakeup_prio))
571 		goto out_locked;
572 
573 	/* reset the trace */
574 	__wakeup_reset(wakeup_trace);
575 
576 	wakeup_cpu = task_cpu(p);
577 	wakeup_current_cpu = wakeup_cpu;
578 	wakeup_prio = p->prio;
579 
580 	/*
581 	 * Once you start tracing a -deadline task, don't bother tracing
582 	 * another task until the first one wakes up.
583 	 */
584 	if (dl_task(p))
585 		tracing_dl = 1;
586 	else
587 		tracing_dl = 0;
588 
589 	wakeup_task = p;
590 	get_task_struct(wakeup_task);
591 
592 	local_save_flags(flags);
593 
594 	data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
595 	data->preempt_timestamp = ftrace_now(cpu);
596 	tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
597 
598 	/*
599 	 * We must be careful in using CALLER_ADDR2. But since wake_up
600 	 * is not called by an assembly function  (where as schedule is)
601 	 * it should be safe to use it here.
602 	 */
603 	__trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
604 
605 out_locked:
606 	arch_spin_unlock(&wakeup_lock);
607 out:
608 	atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
609 }
610 
611 static void start_wakeup_tracer(struct trace_array *tr)
612 {
613 	int ret;
614 
615 	ret = register_trace_sched_wakeup(probe_wakeup, NULL);
616 	if (ret) {
617 		pr_info("wakeup trace: Couldn't activate tracepoint"
618 			" probe to kernel_sched_wakeup\n");
619 		return;
620 	}
621 
622 	ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
623 	if (ret) {
624 		pr_info("wakeup trace: Couldn't activate tracepoint"
625 			" probe to kernel_sched_wakeup_new\n");
626 		goto fail_deprobe;
627 	}
628 
629 	ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
630 	if (ret) {
631 		pr_info("sched trace: Couldn't activate tracepoint"
632 			" probe to kernel_sched_switch\n");
633 		goto fail_deprobe_wake_new;
634 	}
635 
636 	ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
637 	if (ret) {
638 		pr_info("wakeup trace: Couldn't activate tracepoint"
639 			" probe to kernel_sched_migrate_task\n");
640 		return;
641 	}
642 
643 	wakeup_reset(tr);
644 
645 	/*
646 	 * Don't let the tracer_enabled = 1 show up before
647 	 * the wakeup_task is reset. This may be overkill since
648 	 * wakeup_reset does a spin_unlock after setting the
649 	 * wakeup_task to NULL, but I want to be safe.
650 	 * This is a slow path anyway.
651 	 */
652 	smp_wmb();
653 
654 	if (start_func_tracer(tr, is_graph(tr)))
655 		printk(KERN_ERR "failed to start wakeup tracer\n");
656 
657 	return;
658 fail_deprobe_wake_new:
659 	unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
660 fail_deprobe:
661 	unregister_trace_sched_wakeup(probe_wakeup, NULL);
662 }
663 
664 static void stop_wakeup_tracer(struct trace_array *tr)
665 {
666 	tracer_enabled = 0;
667 	stop_func_tracer(tr, is_graph(tr));
668 	unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
669 	unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
670 	unregister_trace_sched_wakeup(probe_wakeup, NULL);
671 	unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
672 }
673 
674 static bool wakeup_busy;
675 
676 static int __wakeup_tracer_init(struct trace_array *tr)
677 {
678 	save_flags = tr->trace_flags;
679 
680 	/* non overwrite screws up the latency tracers */
681 	set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
682 	set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
683 
684 	tr->max_latency = 0;
685 	wakeup_trace = tr;
686 	ftrace_init_array_ops(tr, wakeup_tracer_call);
687 	start_wakeup_tracer(tr);
688 
689 	wakeup_busy = true;
690 	return 0;
691 }
692 
693 static int wakeup_tracer_init(struct trace_array *tr)
694 {
695 	if (wakeup_busy)
696 		return -EBUSY;
697 
698 	wakeup_dl = 0;
699 	wakeup_rt = 0;
700 	return __wakeup_tracer_init(tr);
701 }
702 
703 static int wakeup_rt_tracer_init(struct trace_array *tr)
704 {
705 	if (wakeup_busy)
706 		return -EBUSY;
707 
708 	wakeup_dl = 0;
709 	wakeup_rt = 1;
710 	return __wakeup_tracer_init(tr);
711 }
712 
713 static int wakeup_dl_tracer_init(struct trace_array *tr)
714 {
715 	if (wakeup_busy)
716 		return -EBUSY;
717 
718 	wakeup_dl = 1;
719 	wakeup_rt = 0;
720 	return __wakeup_tracer_init(tr);
721 }
722 
723 static void wakeup_tracer_reset(struct trace_array *tr)
724 {
725 	int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
726 	int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
727 
728 	stop_wakeup_tracer(tr);
729 	/* make sure we put back any tasks we are tracing */
730 	wakeup_reset(tr);
731 
732 	set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
733 	set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
734 	ftrace_reset_array_ops(tr);
735 	wakeup_busy = false;
736 }
737 
738 static void wakeup_tracer_start(struct trace_array *tr)
739 {
740 	wakeup_reset(tr);
741 	tracer_enabled = 1;
742 }
743 
744 static void wakeup_tracer_stop(struct trace_array *tr)
745 {
746 	tracer_enabled = 0;
747 }
748 
749 static struct tracer wakeup_tracer __read_mostly =
750 {
751 	.name		= "wakeup",
752 	.init		= wakeup_tracer_init,
753 	.reset		= wakeup_tracer_reset,
754 	.start		= wakeup_tracer_start,
755 	.stop		= wakeup_tracer_stop,
756 	.print_max	= true,
757 	.print_header	= wakeup_print_header,
758 	.print_line	= wakeup_print_line,
759 	.flag_changed	= wakeup_flag_changed,
760 #ifdef CONFIG_FTRACE_SELFTEST
761 	.selftest    = trace_selftest_startup_wakeup,
762 #endif
763 	.open		= wakeup_trace_open,
764 	.close		= wakeup_trace_close,
765 	.allow_instances = true,
766 	.use_max_tr	= true,
767 };
768 
769 static struct tracer wakeup_rt_tracer __read_mostly =
770 {
771 	.name		= "wakeup_rt",
772 	.init		= wakeup_rt_tracer_init,
773 	.reset		= wakeup_tracer_reset,
774 	.start		= wakeup_tracer_start,
775 	.stop		= wakeup_tracer_stop,
776 	.print_max	= true,
777 	.print_header	= wakeup_print_header,
778 	.print_line	= wakeup_print_line,
779 	.flag_changed	= wakeup_flag_changed,
780 #ifdef CONFIG_FTRACE_SELFTEST
781 	.selftest    = trace_selftest_startup_wakeup,
782 #endif
783 	.open		= wakeup_trace_open,
784 	.close		= wakeup_trace_close,
785 	.allow_instances = true,
786 	.use_max_tr	= true,
787 };
788 
789 static struct tracer wakeup_dl_tracer __read_mostly =
790 {
791 	.name		= "wakeup_dl",
792 	.init		= wakeup_dl_tracer_init,
793 	.reset		= wakeup_tracer_reset,
794 	.start		= wakeup_tracer_start,
795 	.stop		= wakeup_tracer_stop,
796 	.print_max	= true,
797 	.print_header	= wakeup_print_header,
798 	.print_line	= wakeup_print_line,
799 	.flag_changed	= wakeup_flag_changed,
800 #ifdef CONFIG_FTRACE_SELFTEST
801 	.selftest    = trace_selftest_startup_wakeup,
802 #endif
803 	.open		= wakeup_trace_open,
804 	.close		= wakeup_trace_close,
805 	.allow_instances = true,
806 	.use_max_tr	= true,
807 };
808 
809 __init static int init_wakeup_tracer(void)
810 {
811 	int ret;
812 
813 	ret = register_tracer(&wakeup_tracer);
814 	if (ret)
815 		return ret;
816 
817 	ret = register_tracer(&wakeup_rt_tracer);
818 	if (ret)
819 		return ret;
820 
821 	ret = register_tracer(&wakeup_dl_tracer);
822 	if (ret)
823 		return ret;
824 
825 	return 0;
826 }
827 core_initcall(init_wakeup_tracer);
828