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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 William Lee Irwin III
11 */
12#include <linux/module.h>
13#include <linux/fs.h>
14#include <linux/debugfs.h>
15#include <linux/kallsyms.h>
16#include <linux/uaccess.h>
17#include <linux/ftrace.h>
18#include <trace/events/sched.h>
19
20#include "trace.h"
21
22static struct trace_array *wakeup_trace;
23static int __read_mostly tracer_enabled;
24
25static struct task_struct *wakeup_task;
26static int wakeup_cpu;
27static int wakeup_current_cpu;
28static unsigned wakeup_prio = -1;
29static int wakeup_rt;
30
31static arch_spinlock_t wakeup_lock =
32 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
33
34static void wakeup_reset(struct trace_array *tr);
35static void __wakeup_reset(struct trace_array *tr);
36static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
37static void wakeup_graph_return(struct ftrace_graph_ret *trace);
38
39static int save_lat_flag;
40
41#define TRACE_DISPLAY_GRAPH 1
42
43static struct tracer_opt trace_opts[] = {
44#ifdef CONFIG_FUNCTION_GRAPH_TRACER
45 /* display latency trace as call graph */
46 { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
47#endif
48 { } /* Empty entry */
49};
50
51static struct tracer_flags tracer_flags = {
52 .val = 0,
53 .opts = trace_opts,
54};
55
56#define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
57
58#ifdef CONFIG_FUNCTION_TRACER
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 */
74static int
75func_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 = tr->data[cpu];
93 disabled = atomic_inc_return(&(*data)->disabled);
94 if (unlikely(disabled != 1))
95 goto out;
96
97 return 1;
98
99out:
100 atomic_dec(&(*data)->disabled);
101
102out_enable:
103 preempt_enable_notrace();
104 return 0;
105}
106
107/*
108 * wakeup uses its own tracer function to keep the overhead down:
109 */
110static void
111wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
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
129static struct ftrace_ops trace_ops __read_mostly =
130{
131 .func = wakeup_tracer_call,
132 .flags = FTRACE_OPS_FL_GLOBAL,
133};
134#endif /* CONFIG_FUNCTION_TRACER */
135
136static int start_func_tracer(int graph)
137{
138 int ret;
139
140 if (!graph)
141 ret = register_ftrace_function(&trace_ops);
142 else
143 ret = register_ftrace_graph(&wakeup_graph_return,
144 &wakeup_graph_entry);
145
146 if (!ret && tracing_is_enabled())
147 tracer_enabled = 1;
148 else
149 tracer_enabled = 0;
150
151 return ret;
152}
153
154static void stop_func_tracer(int graph)
155{
156 tracer_enabled = 0;
157
158 if (!graph)
159 unregister_ftrace_function(&trace_ops);
160 else
161 unregister_ftrace_graph();
162}
163
164#ifdef CONFIG_FUNCTION_GRAPH_TRACER
165static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
166{
167
168 if (!(bit & TRACE_DISPLAY_GRAPH))
169 return -EINVAL;
170
171 if (!(is_graph() ^ set))
172 return 0;
173
174 stop_func_tracer(!set);
175
176 wakeup_reset(wakeup_trace);
177 tracing_max_latency = 0;
178
179 return start_func_tracer(set);
180}
181
182static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
183{
184 struct trace_array *tr = wakeup_trace;
185 struct trace_array_cpu *data;
186 unsigned long flags;
187 int pc, ret = 0;
188
189 if (!func_prolog_preempt_disable(tr, &data, &pc))
190 return 0;
191
192 local_save_flags(flags);
193 ret = __trace_graph_entry(tr, trace, flags, pc);
194 atomic_dec(&data->disabled);
195 preempt_enable_notrace();
196
197 return ret;
198}
199
200static void wakeup_graph_return(struct ftrace_graph_ret *trace)
201{
202 struct trace_array *tr = wakeup_trace;
203 struct trace_array_cpu *data;
204 unsigned long flags;
205 int pc;
206
207 if (!func_prolog_preempt_disable(tr, &data, &pc))
208 return;
209
210 local_save_flags(flags);
211 __trace_graph_return(tr, trace, flags, pc);
212 atomic_dec(&data->disabled);
213
214 preempt_enable_notrace();
215 return;
216}
217
218static void wakeup_trace_open(struct trace_iterator *iter)
219{
220 if (is_graph())
221 graph_trace_open(iter);
222}
223
224static void wakeup_trace_close(struct trace_iterator *iter)
225{
226 if (iter->private)
227 graph_trace_close(iter);
228}
229
230#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
231 TRACE_GRAPH_PRINT_ABS_TIME | \
232 TRACE_GRAPH_PRINT_DURATION)
233
234static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
235{
236 /*
237 * In graph mode call the graph tracer output function,
238 * otherwise go with the TRACE_FN event handler
239 */
240 if (is_graph())
241 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
242
243 return TRACE_TYPE_UNHANDLED;
244}
245
246static void wakeup_print_header(struct seq_file *s)
247{
248 if (is_graph())
249 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
250 else
251 trace_default_header(s);
252}
253
254static void
255__trace_function(struct trace_array *tr,
256 unsigned long ip, unsigned long parent_ip,
257 unsigned long flags, int pc)
258{
259 if (is_graph())
260 trace_graph_function(tr, ip, parent_ip, flags, pc);
261 else
262 trace_function(tr, ip, parent_ip, flags, pc);
263}
264#else
265#define __trace_function trace_function
266
267static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
268{
269 return -EINVAL;
270}
271
272static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
273{
274 return -1;
275}
276
277static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
278{
279 return TRACE_TYPE_UNHANDLED;
280}
281
282static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
283static void wakeup_print_header(struct seq_file *s) { }
284static void wakeup_trace_open(struct trace_iterator *iter) { }
285static void wakeup_trace_close(struct trace_iterator *iter) { }
286#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
287
288/*
289 * Should this new latency be reported/recorded?
290 */
291static int report_latency(cycle_t delta)
292{
293 if (tracing_thresh) {
294 if (delta < tracing_thresh)
295 return 0;
296 } else {
297 if (delta <= tracing_max_latency)
298 return 0;
299 }
300 return 1;
301}
302
303static void
304probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
305{
306 if (task != wakeup_task)
307 return;
308
309 wakeup_current_cpu = cpu;
310}
311
312static void notrace
313probe_wakeup_sched_switch(void *ignore,
314 struct task_struct *prev, struct task_struct *next)
315{
316 struct trace_array_cpu *data;
317 cycle_t T0, T1, delta;
318 unsigned long flags;
319 long disabled;
320 int cpu;
321 int pc;
322
323 tracing_record_cmdline(prev);
324
325 if (unlikely(!tracer_enabled))
326 return;
327
328 /*
329 * When we start a new trace, we set wakeup_task to NULL
330 * and then set tracer_enabled = 1. We want to make sure
331 * that another CPU does not see the tracer_enabled = 1
332 * and the wakeup_task with an older task, that might
333 * actually be the same as next.
334 */
335 smp_rmb();
336
337 if (next != wakeup_task)
338 return;
339
340 pc = preempt_count();
341
342 /* disable local data, not wakeup_cpu data */
343 cpu = raw_smp_processor_id();
344 disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
345 if (likely(disabled != 1))
346 goto out;
347
348 local_irq_save(flags);
349 arch_spin_lock(&wakeup_lock);
350
351 /* We could race with grabbing wakeup_lock */
352 if (unlikely(!tracer_enabled || next != wakeup_task))
353 goto out_unlock;
354
355 /* The task we are waiting for is waking up */
356 data = wakeup_trace->data[wakeup_cpu];
357
358 __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
359 tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
360
361 T0 = data->preempt_timestamp;
362 T1 = ftrace_now(cpu);
363 delta = T1-T0;
364
365 if (!report_latency(delta))
366 goto out_unlock;
367
368 if (likely(!is_tracing_stopped())) {
369 tracing_max_latency = delta;
370 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
371 }
372
373out_unlock:
374 __wakeup_reset(wakeup_trace);
375 arch_spin_unlock(&wakeup_lock);
376 local_irq_restore(flags);
377out:
378 atomic_dec(&wakeup_trace->data[cpu]->disabled);
379}
380
381static void __wakeup_reset(struct trace_array *tr)
382{
383 wakeup_cpu = -1;
384 wakeup_prio = -1;
385
386 if (wakeup_task)
387 put_task_struct(wakeup_task);
388
389 wakeup_task = NULL;
390}
391
392static void wakeup_reset(struct trace_array *tr)
393{
394 unsigned long flags;
395
396 tracing_reset_online_cpus(tr);
397
398 local_irq_save(flags);
399 arch_spin_lock(&wakeup_lock);
400 __wakeup_reset(tr);
401 arch_spin_unlock(&wakeup_lock);
402 local_irq_restore(flags);
403}
404
405static void
406probe_wakeup(void *ignore, struct task_struct *p, int success)
407{
408 struct trace_array_cpu *data;
409 int cpu = smp_processor_id();
410 unsigned long flags;
411 long disabled;
412 int pc;
413
414 if (likely(!tracer_enabled))
415 return;
416
417 tracing_record_cmdline(p);
418 tracing_record_cmdline(current);
419
420 if ((wakeup_rt && !rt_task(p)) ||
421 p->prio >= wakeup_prio ||
422 p->prio >= current->prio)
423 return;
424
425 pc = preempt_count();
426 disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
427 if (unlikely(disabled != 1))
428 goto out;
429
430 /* interrupts should be off from try_to_wake_up */
431 arch_spin_lock(&wakeup_lock);
432
433 /* check for races. */
434 if (!tracer_enabled || p->prio >= wakeup_prio)
435 goto out_locked;
436
437 /* reset the trace */
438 __wakeup_reset(wakeup_trace);
439
440 wakeup_cpu = task_cpu(p);
441 wakeup_current_cpu = wakeup_cpu;
442 wakeup_prio = p->prio;
443
444 wakeup_task = p;
445 get_task_struct(wakeup_task);
446
447 local_save_flags(flags);
448
449 data = wakeup_trace->data[wakeup_cpu];
450 data->preempt_timestamp = ftrace_now(cpu);
451 tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
452
453 /*
454 * We must be careful in using CALLER_ADDR2. But since wake_up
455 * is not called by an assembly function (where as schedule is)
456 * it should be safe to use it here.
457 */
458 __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
459
460out_locked:
461 arch_spin_unlock(&wakeup_lock);
462out:
463 atomic_dec(&wakeup_trace->data[cpu]->disabled);
464}
465
466static void start_wakeup_tracer(struct trace_array *tr)
467{
468 int ret;
469
470 ret = register_trace_sched_wakeup(probe_wakeup, NULL);
471 if (ret) {
472 pr_info("wakeup trace: Couldn't activate tracepoint"
473 " probe to kernel_sched_wakeup\n");
474 return;
475 }
476
477 ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
478 if (ret) {
479 pr_info("wakeup trace: Couldn't activate tracepoint"
480 " probe to kernel_sched_wakeup_new\n");
481 goto fail_deprobe;
482 }
483
484 ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
485 if (ret) {
486 pr_info("sched trace: Couldn't activate tracepoint"
487 " probe to kernel_sched_switch\n");
488 goto fail_deprobe_wake_new;
489 }
490
491 ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
492 if (ret) {
493 pr_info("wakeup trace: Couldn't activate tracepoint"
494 " probe to kernel_sched_migrate_task\n");
495 return;
496 }
497
498 wakeup_reset(tr);
499
500 /*
501 * Don't let the tracer_enabled = 1 show up before
502 * the wakeup_task is reset. This may be overkill since
503 * wakeup_reset does a spin_unlock after setting the
504 * wakeup_task to NULL, but I want to be safe.
505 * This is a slow path anyway.
506 */
507 smp_wmb();
508
509 if (start_func_tracer(is_graph()))
510 printk(KERN_ERR "failed to start wakeup tracer\n");
511
512 return;
513fail_deprobe_wake_new:
514 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
515fail_deprobe:
516 unregister_trace_sched_wakeup(probe_wakeup, NULL);
517}
518
519static void stop_wakeup_tracer(struct trace_array *tr)
520{
521 tracer_enabled = 0;
522 stop_func_tracer(is_graph());
523 unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
524 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
525 unregister_trace_sched_wakeup(probe_wakeup, NULL);
526 unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
527}
528
529static int __wakeup_tracer_init(struct trace_array *tr)
530{
531 save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
532 trace_flags |= TRACE_ITER_LATENCY_FMT;
533
534 tracing_max_latency = 0;
535 wakeup_trace = tr;
536 start_wakeup_tracer(tr);
537 return 0;
538}
539
540static int wakeup_tracer_init(struct trace_array *tr)
541{
542 wakeup_rt = 0;
543 return __wakeup_tracer_init(tr);
544}
545
546static int wakeup_rt_tracer_init(struct trace_array *tr)
547{
548 wakeup_rt = 1;
549 return __wakeup_tracer_init(tr);
550}
551
552static void wakeup_tracer_reset(struct trace_array *tr)
553{
554 stop_wakeup_tracer(tr);
555 /* make sure we put back any tasks we are tracing */
556 wakeup_reset(tr);
557
558 if (!save_lat_flag)
559 trace_flags &= ~TRACE_ITER_LATENCY_FMT;
560}
561
562static void wakeup_tracer_start(struct trace_array *tr)
563{
564 wakeup_reset(tr);
565 tracer_enabled = 1;
566}
567
568static void wakeup_tracer_stop(struct trace_array *tr)
569{
570 tracer_enabled = 0;
571}
572
573static struct tracer wakeup_tracer __read_mostly =
574{
575 .name = "wakeup",
576 .init = wakeup_tracer_init,
577 .reset = wakeup_tracer_reset,
578 .start = wakeup_tracer_start,
579 .stop = wakeup_tracer_stop,
580 .print_max = 1,
581 .print_header = wakeup_print_header,
582 .print_line = wakeup_print_line,
583 .flags = &tracer_flags,
584 .set_flag = wakeup_set_flag,
585#ifdef CONFIG_FTRACE_SELFTEST
586 .selftest = trace_selftest_startup_wakeup,
587#endif
588 .open = wakeup_trace_open,
589 .close = wakeup_trace_close,
590 .use_max_tr = 1,
591};
592
593static struct tracer wakeup_rt_tracer __read_mostly =
594{
595 .name = "wakeup_rt",
596 .init = wakeup_rt_tracer_init,
597 .reset = wakeup_tracer_reset,
598 .start = wakeup_tracer_start,
599 .stop = wakeup_tracer_stop,
600 .wait_pipe = poll_wait_pipe,
601 .print_max = 1,
602 .print_header = wakeup_print_header,
603 .print_line = wakeup_print_line,
604 .flags = &tracer_flags,
605 .set_flag = wakeup_set_flag,
606#ifdef CONFIG_FTRACE_SELFTEST
607 .selftest = trace_selftest_startup_wakeup,
608#endif
609 .open = wakeup_trace_open,
610 .close = wakeup_trace_close,
611 .use_max_tr = 1,
612};
613
614__init static int init_wakeup_tracer(void)
615{
616 int ret;
617
618 ret = register_tracer(&wakeup_tracer);
619 if (ret)
620 return ret;
621
622 ret = register_tracer(&wakeup_rt_tracer);
623 if (ret)
624 return ret;
625
626 return 0;
627}
628device_initcall(init_wakeup_tracer);
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 William Lee Irwin III
11 */
12#include <linux/module.h>
13#include <linux/fs.h>
14#include <linux/debugfs.h>
15#include <linux/kallsyms.h>
16#include <linux/uaccess.h>
17#include <linux/ftrace.h>
18#include <trace/events/sched.h>
19
20#include "trace.h"
21
22static struct trace_array *wakeup_trace;
23static int __read_mostly tracer_enabled;
24
25static struct task_struct *wakeup_task;
26static int wakeup_cpu;
27static int wakeup_current_cpu;
28static unsigned wakeup_prio = -1;
29static int wakeup_rt;
30
31static arch_spinlock_t wakeup_lock =
32 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
33
34static void wakeup_reset(struct trace_array *tr);
35static void __wakeup_reset(struct trace_array *tr);
36static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
37static void wakeup_graph_return(struct ftrace_graph_ret *trace);
38
39static int save_lat_flag;
40
41#define TRACE_DISPLAY_GRAPH 1
42
43static struct tracer_opt trace_opts[] = {
44#ifdef CONFIG_FUNCTION_GRAPH_TRACER
45 /* display latency trace as call graph */
46 { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
47#endif
48 { } /* Empty entry */
49};
50
51static struct tracer_flags tracer_flags = {
52 .val = 0,
53 .opts = trace_opts,
54};
55
56#define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
57
58#ifdef CONFIG_FUNCTION_TRACER
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 */
74static int
75func_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 = tr->data[cpu];
93 disabled = atomic_inc_return(&(*data)->disabled);
94 if (unlikely(disabled != 1))
95 goto out;
96
97 return 1;
98
99out:
100 atomic_dec(&(*data)->disabled);
101
102out_enable:
103 preempt_enable_notrace();
104 return 0;
105}
106
107/*
108 * wakeup uses its own tracer function to keep the overhead down:
109 */
110static void
111wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
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
129static struct ftrace_ops trace_ops __read_mostly =
130{
131 .func = wakeup_tracer_call,
132 .flags = FTRACE_OPS_FL_GLOBAL,
133};
134#endif /* CONFIG_FUNCTION_TRACER */
135
136static int start_func_tracer(int graph)
137{
138 int ret;
139
140 if (!graph)
141 ret = register_ftrace_function(&trace_ops);
142 else
143 ret = register_ftrace_graph(&wakeup_graph_return,
144 &wakeup_graph_entry);
145
146 if (!ret && tracing_is_enabled())
147 tracer_enabled = 1;
148 else
149 tracer_enabled = 0;
150
151 return ret;
152}
153
154static void stop_func_tracer(int graph)
155{
156 tracer_enabled = 0;
157
158 if (!graph)
159 unregister_ftrace_function(&trace_ops);
160 else
161 unregister_ftrace_graph();
162}
163
164#ifdef CONFIG_FUNCTION_GRAPH_TRACER
165static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
166{
167
168 if (!(bit & TRACE_DISPLAY_GRAPH))
169 return -EINVAL;
170
171 if (!(is_graph() ^ set))
172 return 0;
173
174 stop_func_tracer(!set);
175
176 wakeup_reset(wakeup_trace);
177 tracing_max_latency = 0;
178
179 return start_func_tracer(set);
180}
181
182static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
183{
184 struct trace_array *tr = wakeup_trace;
185 struct trace_array_cpu *data;
186 unsigned long flags;
187 int pc, ret = 0;
188
189 if (!func_prolog_preempt_disable(tr, &data, &pc))
190 return 0;
191
192 local_save_flags(flags);
193 ret = __trace_graph_entry(tr, trace, flags, pc);
194 atomic_dec(&data->disabled);
195 preempt_enable_notrace();
196
197 return ret;
198}
199
200static void wakeup_graph_return(struct ftrace_graph_ret *trace)
201{
202 struct trace_array *tr = wakeup_trace;
203 struct trace_array_cpu *data;
204 unsigned long flags;
205 int pc;
206
207 if (!func_prolog_preempt_disable(tr, &data, &pc))
208 return;
209
210 local_save_flags(flags);
211 __trace_graph_return(tr, trace, flags, pc);
212 atomic_dec(&data->disabled);
213
214 preempt_enable_notrace();
215 return;
216}
217
218static void wakeup_trace_open(struct trace_iterator *iter)
219{
220 if (is_graph())
221 graph_trace_open(iter);
222}
223
224static void wakeup_trace_close(struct trace_iterator *iter)
225{
226 if (iter->private)
227 graph_trace_close(iter);
228}
229
230#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
231 TRACE_GRAPH_PRINT_ABS_TIME | \
232 TRACE_GRAPH_PRINT_DURATION)
233
234static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
235{
236 /*
237 * In graph mode call the graph tracer output function,
238 * otherwise go with the TRACE_FN event handler
239 */
240 if (is_graph())
241 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
242
243 return TRACE_TYPE_UNHANDLED;
244}
245
246static void wakeup_print_header(struct seq_file *s)
247{
248 if (is_graph())
249 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
250 else
251 trace_default_header(s);
252}
253
254static void
255__trace_function(struct trace_array *tr,
256 unsigned long ip, unsigned long parent_ip,
257 unsigned long flags, int pc)
258{
259 if (is_graph())
260 trace_graph_function(tr, ip, parent_ip, flags, pc);
261 else
262 trace_function(tr, ip, parent_ip, flags, pc);
263}
264#else
265#define __trace_function trace_function
266
267static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
268{
269 return -EINVAL;
270}
271
272static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
273{
274 return -1;
275}
276
277static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
278{
279 return TRACE_TYPE_UNHANDLED;
280}
281
282static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
283static void wakeup_trace_open(struct trace_iterator *iter) { }
284static void wakeup_trace_close(struct trace_iterator *iter) { }
285
286#ifdef CONFIG_FUNCTION_TRACER
287static void wakeup_print_header(struct seq_file *s)
288{
289 trace_default_header(s);
290}
291#else
292static void wakeup_print_header(struct seq_file *s)
293{
294 trace_latency_header(s);
295}
296#endif /* CONFIG_FUNCTION_TRACER */
297#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
298
299/*
300 * Should this new latency be reported/recorded?
301 */
302static int report_latency(cycle_t delta)
303{
304 if (tracing_thresh) {
305 if (delta < tracing_thresh)
306 return 0;
307 } else {
308 if (delta <= tracing_max_latency)
309 return 0;
310 }
311 return 1;
312}
313
314static void
315probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
316{
317 if (task != wakeup_task)
318 return;
319
320 wakeup_current_cpu = cpu;
321}
322
323static void notrace
324probe_wakeup_sched_switch(void *ignore,
325 struct task_struct *prev, struct task_struct *next)
326{
327 struct trace_array_cpu *data;
328 cycle_t T0, T1, delta;
329 unsigned long flags;
330 long disabled;
331 int cpu;
332 int pc;
333
334 tracing_record_cmdline(prev);
335
336 if (unlikely(!tracer_enabled))
337 return;
338
339 /*
340 * When we start a new trace, we set wakeup_task to NULL
341 * and then set tracer_enabled = 1. We want to make sure
342 * that another CPU does not see the tracer_enabled = 1
343 * and the wakeup_task with an older task, that might
344 * actually be the same as next.
345 */
346 smp_rmb();
347
348 if (next != wakeup_task)
349 return;
350
351 pc = preempt_count();
352
353 /* disable local data, not wakeup_cpu data */
354 cpu = raw_smp_processor_id();
355 disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
356 if (likely(disabled != 1))
357 goto out;
358
359 local_irq_save(flags);
360 arch_spin_lock(&wakeup_lock);
361
362 /* We could race with grabbing wakeup_lock */
363 if (unlikely(!tracer_enabled || next != wakeup_task))
364 goto out_unlock;
365
366 /* The task we are waiting for is waking up */
367 data = wakeup_trace->data[wakeup_cpu];
368
369 __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
370 tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
371
372 T0 = data->preempt_timestamp;
373 T1 = ftrace_now(cpu);
374 delta = T1-T0;
375
376 if (!report_latency(delta))
377 goto out_unlock;
378
379 if (likely(!is_tracing_stopped())) {
380 tracing_max_latency = delta;
381 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
382 }
383
384out_unlock:
385 __wakeup_reset(wakeup_trace);
386 arch_spin_unlock(&wakeup_lock);
387 local_irq_restore(flags);
388out:
389 atomic_dec(&wakeup_trace->data[cpu]->disabled);
390}
391
392static void __wakeup_reset(struct trace_array *tr)
393{
394 wakeup_cpu = -1;
395 wakeup_prio = -1;
396
397 if (wakeup_task)
398 put_task_struct(wakeup_task);
399
400 wakeup_task = NULL;
401}
402
403static void wakeup_reset(struct trace_array *tr)
404{
405 unsigned long flags;
406
407 tracing_reset_online_cpus(tr);
408
409 local_irq_save(flags);
410 arch_spin_lock(&wakeup_lock);
411 __wakeup_reset(tr);
412 arch_spin_unlock(&wakeup_lock);
413 local_irq_restore(flags);
414}
415
416static void
417probe_wakeup(void *ignore, struct task_struct *p, int success)
418{
419 struct trace_array_cpu *data;
420 int cpu = smp_processor_id();
421 unsigned long flags;
422 long disabled;
423 int pc;
424
425 if (likely(!tracer_enabled))
426 return;
427
428 tracing_record_cmdline(p);
429 tracing_record_cmdline(current);
430
431 if ((wakeup_rt && !rt_task(p)) ||
432 p->prio >= wakeup_prio ||
433 p->prio >= current->prio)
434 return;
435
436 pc = preempt_count();
437 disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
438 if (unlikely(disabled != 1))
439 goto out;
440
441 /* interrupts should be off from try_to_wake_up */
442 arch_spin_lock(&wakeup_lock);
443
444 /* check for races. */
445 if (!tracer_enabled || p->prio >= wakeup_prio)
446 goto out_locked;
447
448 /* reset the trace */
449 __wakeup_reset(wakeup_trace);
450
451 wakeup_cpu = task_cpu(p);
452 wakeup_current_cpu = wakeup_cpu;
453 wakeup_prio = p->prio;
454
455 wakeup_task = p;
456 get_task_struct(wakeup_task);
457
458 local_save_flags(flags);
459
460 data = wakeup_trace->data[wakeup_cpu];
461 data->preempt_timestamp = ftrace_now(cpu);
462 tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
463
464 /*
465 * We must be careful in using CALLER_ADDR2. But since wake_up
466 * is not called by an assembly function (where as schedule is)
467 * it should be safe to use it here.
468 */
469 __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
470
471out_locked:
472 arch_spin_unlock(&wakeup_lock);
473out:
474 atomic_dec(&wakeup_trace->data[cpu]->disabled);
475}
476
477static void start_wakeup_tracer(struct trace_array *tr)
478{
479 int ret;
480
481 ret = register_trace_sched_wakeup(probe_wakeup, NULL);
482 if (ret) {
483 pr_info("wakeup trace: Couldn't activate tracepoint"
484 " probe to kernel_sched_wakeup\n");
485 return;
486 }
487
488 ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
489 if (ret) {
490 pr_info("wakeup trace: Couldn't activate tracepoint"
491 " probe to kernel_sched_wakeup_new\n");
492 goto fail_deprobe;
493 }
494
495 ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
496 if (ret) {
497 pr_info("sched trace: Couldn't activate tracepoint"
498 " probe to kernel_sched_switch\n");
499 goto fail_deprobe_wake_new;
500 }
501
502 ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
503 if (ret) {
504 pr_info("wakeup trace: Couldn't activate tracepoint"
505 " probe to kernel_sched_migrate_task\n");
506 return;
507 }
508
509 wakeup_reset(tr);
510
511 /*
512 * Don't let the tracer_enabled = 1 show up before
513 * the wakeup_task is reset. This may be overkill since
514 * wakeup_reset does a spin_unlock after setting the
515 * wakeup_task to NULL, but I want to be safe.
516 * This is a slow path anyway.
517 */
518 smp_wmb();
519
520 if (start_func_tracer(is_graph()))
521 printk(KERN_ERR "failed to start wakeup tracer\n");
522
523 return;
524fail_deprobe_wake_new:
525 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
526fail_deprobe:
527 unregister_trace_sched_wakeup(probe_wakeup, NULL);
528}
529
530static void stop_wakeup_tracer(struct trace_array *tr)
531{
532 tracer_enabled = 0;
533 stop_func_tracer(is_graph());
534 unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
535 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
536 unregister_trace_sched_wakeup(probe_wakeup, NULL);
537 unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
538}
539
540static int __wakeup_tracer_init(struct trace_array *tr)
541{
542 save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
543 trace_flags |= TRACE_ITER_LATENCY_FMT;
544
545 tracing_max_latency = 0;
546 wakeup_trace = tr;
547 start_wakeup_tracer(tr);
548 return 0;
549}
550
551static int wakeup_tracer_init(struct trace_array *tr)
552{
553 wakeup_rt = 0;
554 return __wakeup_tracer_init(tr);
555}
556
557static int wakeup_rt_tracer_init(struct trace_array *tr)
558{
559 wakeup_rt = 1;
560 return __wakeup_tracer_init(tr);
561}
562
563static void wakeup_tracer_reset(struct trace_array *tr)
564{
565 stop_wakeup_tracer(tr);
566 /* make sure we put back any tasks we are tracing */
567 wakeup_reset(tr);
568
569 if (!save_lat_flag)
570 trace_flags &= ~TRACE_ITER_LATENCY_FMT;
571}
572
573static void wakeup_tracer_start(struct trace_array *tr)
574{
575 wakeup_reset(tr);
576 tracer_enabled = 1;
577}
578
579static void wakeup_tracer_stop(struct trace_array *tr)
580{
581 tracer_enabled = 0;
582}
583
584static struct tracer wakeup_tracer __read_mostly =
585{
586 .name = "wakeup",
587 .init = wakeup_tracer_init,
588 .reset = wakeup_tracer_reset,
589 .start = wakeup_tracer_start,
590 .stop = wakeup_tracer_stop,
591 .print_max = 1,
592 .print_header = wakeup_print_header,
593 .print_line = wakeup_print_line,
594 .flags = &tracer_flags,
595 .set_flag = wakeup_set_flag,
596#ifdef CONFIG_FTRACE_SELFTEST
597 .selftest = trace_selftest_startup_wakeup,
598#endif
599 .open = wakeup_trace_open,
600 .close = wakeup_trace_close,
601 .use_max_tr = 1,
602};
603
604static struct tracer wakeup_rt_tracer __read_mostly =
605{
606 .name = "wakeup_rt",
607 .init = wakeup_rt_tracer_init,
608 .reset = wakeup_tracer_reset,
609 .start = wakeup_tracer_start,
610 .stop = wakeup_tracer_stop,
611 .wait_pipe = poll_wait_pipe,
612 .print_max = 1,
613 .print_header = wakeup_print_header,
614 .print_line = wakeup_print_line,
615 .flags = &tracer_flags,
616 .set_flag = wakeup_set_flag,
617#ifdef CONFIG_FTRACE_SELFTEST
618 .selftest = trace_selftest_startup_wakeup,
619#endif
620 .open = wakeup_trace_open,
621 .close = wakeup_trace_close,
622 .use_max_tr = 1,
623};
624
625__init static int init_wakeup_tracer(void)
626{
627 int ret;
628
629 ret = register_tracer(&wakeup_tracer);
630 if (ret)
631 return ret;
632
633 ret = register_tracer(&wakeup_rt_tracer);
634 if (ret)
635 return ret;
636
637 return 0;
638}
639device_initcall(init_wakeup_tracer);