locking: Rename __RAW_SPIN_LOCK_UNLOCKED to __ARCH_SPIN_LOCK_UNLOCKED
[linux-2.6.git] / kernel / trace / trace_sched_wakeup.c
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
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
31 static arch_spinlock_t wakeup_lock =
32         (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
33
34 static void __wakeup_reset(struct trace_array *tr);
35
36 static int save_lat_flag;
37
38 #ifdef CONFIG_FUNCTION_TRACER
39 /*
40  * irqsoff uses its own tracer function to keep the overhead down:
41  */
42 static void
43 wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
44 {
45         struct trace_array *tr = wakeup_trace;
46         struct trace_array_cpu *data;
47         unsigned long flags;
48         long disabled;
49         int resched;
50         int cpu;
51         int pc;
52
53         if (likely(!wakeup_task))
54                 return;
55
56         pc = preempt_count();
57         resched = ftrace_preempt_disable();
58
59         cpu = raw_smp_processor_id();
60         if (cpu != wakeup_current_cpu)
61                 goto out_enable;
62
63         data = tr->data[cpu];
64         disabled = atomic_inc_return(&data->disabled);
65         if (unlikely(disabled != 1))
66                 goto out;
67
68         local_irq_save(flags);
69
70         trace_function(tr, ip, parent_ip, flags, pc);
71
72         local_irq_restore(flags);
73
74  out:
75         atomic_dec(&data->disabled);
76  out_enable:
77         ftrace_preempt_enable(resched);
78 }
79
80 static struct ftrace_ops trace_ops __read_mostly =
81 {
82         .func = wakeup_tracer_call,
83 };
84 #endif /* CONFIG_FUNCTION_TRACER */
85
86 /*
87  * Should this new latency be reported/recorded?
88  */
89 static int report_latency(cycle_t delta)
90 {
91         if (tracing_thresh) {
92                 if (delta < tracing_thresh)
93                         return 0;
94         } else {
95                 if (delta <= tracing_max_latency)
96                         return 0;
97         }
98         return 1;
99 }
100
101 static void probe_wakeup_migrate_task(struct task_struct *task, int cpu)
102 {
103         if (task != wakeup_task)
104                 return;
105
106         wakeup_current_cpu = cpu;
107 }
108
109 static void notrace
110 probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
111         struct task_struct *next)
112 {
113         struct trace_array_cpu *data;
114         cycle_t T0, T1, delta;
115         unsigned long flags;
116         long disabled;
117         int cpu;
118         int pc;
119
120         tracing_record_cmdline(prev);
121
122         if (unlikely(!tracer_enabled))
123                 return;
124
125         /*
126          * When we start a new trace, we set wakeup_task to NULL
127          * and then set tracer_enabled = 1. We want to make sure
128          * that another CPU does not see the tracer_enabled = 1
129          * and the wakeup_task with an older task, that might
130          * actually be the same as next.
131          */
132         smp_rmb();
133
134         if (next != wakeup_task)
135                 return;
136
137         pc = preempt_count();
138
139         /* disable local data, not wakeup_cpu data */
140         cpu = raw_smp_processor_id();
141         disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
142         if (likely(disabled != 1))
143                 goto out;
144
145         local_irq_save(flags);
146         __raw_spin_lock(&wakeup_lock);
147
148         /* We could race with grabbing wakeup_lock */
149         if (unlikely(!tracer_enabled || next != wakeup_task))
150                 goto out_unlock;
151
152         /* The task we are waiting for is waking up */
153         data = wakeup_trace->data[wakeup_cpu];
154
155         trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
156         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
157
158         T0 = data->preempt_timestamp;
159         T1 = ftrace_now(cpu);
160         delta = T1-T0;
161
162         if (!report_latency(delta))
163                 goto out_unlock;
164
165         if (likely(!is_tracing_stopped())) {
166                 tracing_max_latency = delta;
167                 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
168         }
169
170 out_unlock:
171         __wakeup_reset(wakeup_trace);
172         __raw_spin_unlock(&wakeup_lock);
173         local_irq_restore(flags);
174 out:
175         atomic_dec(&wakeup_trace->data[cpu]->disabled);
176 }
177
178 static void __wakeup_reset(struct trace_array *tr)
179 {
180         wakeup_cpu = -1;
181         wakeup_prio = -1;
182
183         if (wakeup_task)
184                 put_task_struct(wakeup_task);
185
186         wakeup_task = NULL;
187 }
188
189 static void wakeup_reset(struct trace_array *tr)
190 {
191         unsigned long flags;
192
193         tracing_reset_online_cpus(tr);
194
195         local_irq_save(flags);
196         __raw_spin_lock(&wakeup_lock);
197         __wakeup_reset(tr);
198         __raw_spin_unlock(&wakeup_lock);
199         local_irq_restore(flags);
200 }
201
202 static void
203 probe_wakeup(struct rq *rq, struct task_struct *p, int success)
204 {
205         struct trace_array_cpu *data;
206         int cpu = smp_processor_id();
207         unsigned long flags;
208         long disabled;
209         int pc;
210
211         if (likely(!tracer_enabled))
212                 return;
213
214         tracing_record_cmdline(p);
215         tracing_record_cmdline(current);
216
217         if ((wakeup_rt && !rt_task(p)) ||
218                         p->prio >= wakeup_prio ||
219                         p->prio >= current->prio)
220                 return;
221
222         pc = preempt_count();
223         disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
224         if (unlikely(disabled != 1))
225                 goto out;
226
227         /* interrupts should be off from try_to_wake_up */
228         __raw_spin_lock(&wakeup_lock);
229
230         /* check for races. */
231         if (!tracer_enabled || p->prio >= wakeup_prio)
232                 goto out_locked;
233
234         /* reset the trace */
235         __wakeup_reset(wakeup_trace);
236
237         wakeup_cpu = task_cpu(p);
238         wakeup_current_cpu = wakeup_cpu;
239         wakeup_prio = p->prio;
240
241         wakeup_task = p;
242         get_task_struct(wakeup_task);
243
244         local_save_flags(flags);
245
246         data = wakeup_trace->data[wakeup_cpu];
247         data->preempt_timestamp = ftrace_now(cpu);
248         tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
249
250         /*
251          * We must be careful in using CALLER_ADDR2. But since wake_up
252          * is not called by an assembly function  (where as schedule is)
253          * it should be safe to use it here.
254          */
255         trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
256
257 out_locked:
258         __raw_spin_unlock(&wakeup_lock);
259 out:
260         atomic_dec(&wakeup_trace->data[cpu]->disabled);
261 }
262
263 static void start_wakeup_tracer(struct trace_array *tr)
264 {
265         int ret;
266
267         ret = register_trace_sched_wakeup(probe_wakeup);
268         if (ret) {
269                 pr_info("wakeup trace: Couldn't activate tracepoint"
270                         " probe to kernel_sched_wakeup\n");
271                 return;
272         }
273
274         ret = register_trace_sched_wakeup_new(probe_wakeup);
275         if (ret) {
276                 pr_info("wakeup trace: Couldn't activate tracepoint"
277                         " probe to kernel_sched_wakeup_new\n");
278                 goto fail_deprobe;
279         }
280
281         ret = register_trace_sched_switch(probe_wakeup_sched_switch);
282         if (ret) {
283                 pr_info("sched trace: Couldn't activate tracepoint"
284                         " probe to kernel_sched_switch\n");
285                 goto fail_deprobe_wake_new;
286         }
287
288         ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task);
289         if (ret) {
290                 pr_info("wakeup trace: Couldn't activate tracepoint"
291                         " probe to kernel_sched_migrate_task\n");
292                 return;
293         }
294
295         wakeup_reset(tr);
296
297         /*
298          * Don't let the tracer_enabled = 1 show up before
299          * the wakeup_task is reset. This may be overkill since
300          * wakeup_reset does a spin_unlock after setting the
301          * wakeup_task to NULL, but I want to be safe.
302          * This is a slow path anyway.
303          */
304         smp_wmb();
305
306         register_ftrace_function(&trace_ops);
307
308         if (tracing_is_enabled())
309                 tracer_enabled = 1;
310         else
311                 tracer_enabled = 0;
312
313         return;
314 fail_deprobe_wake_new:
315         unregister_trace_sched_wakeup_new(probe_wakeup);
316 fail_deprobe:
317         unregister_trace_sched_wakeup(probe_wakeup);
318 }
319
320 static void stop_wakeup_tracer(struct trace_array *tr)
321 {
322         tracer_enabled = 0;
323         unregister_ftrace_function(&trace_ops);
324         unregister_trace_sched_switch(probe_wakeup_sched_switch);
325         unregister_trace_sched_wakeup_new(probe_wakeup);
326         unregister_trace_sched_wakeup(probe_wakeup);
327         unregister_trace_sched_migrate_task(probe_wakeup_migrate_task);
328 }
329
330 static int __wakeup_tracer_init(struct trace_array *tr)
331 {
332         save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
333         trace_flags |= TRACE_ITER_LATENCY_FMT;
334
335         tracing_max_latency = 0;
336         wakeup_trace = tr;
337         start_wakeup_tracer(tr);
338         return 0;
339 }
340
341 static int wakeup_tracer_init(struct trace_array *tr)
342 {
343         wakeup_rt = 0;
344         return __wakeup_tracer_init(tr);
345 }
346
347 static int wakeup_rt_tracer_init(struct trace_array *tr)
348 {
349         wakeup_rt = 1;
350         return __wakeup_tracer_init(tr);
351 }
352
353 static void wakeup_tracer_reset(struct trace_array *tr)
354 {
355         stop_wakeup_tracer(tr);
356         /* make sure we put back any tasks we are tracing */
357         wakeup_reset(tr);
358
359         if (!save_lat_flag)
360                 trace_flags &= ~TRACE_ITER_LATENCY_FMT;
361 }
362
363 static void wakeup_tracer_start(struct trace_array *tr)
364 {
365         wakeup_reset(tr);
366         tracer_enabled = 1;
367 }
368
369 static void wakeup_tracer_stop(struct trace_array *tr)
370 {
371         tracer_enabled = 0;
372 }
373
374 static struct tracer wakeup_tracer __read_mostly =
375 {
376         .name           = "wakeup",
377         .init           = wakeup_tracer_init,
378         .reset          = wakeup_tracer_reset,
379         .start          = wakeup_tracer_start,
380         .stop           = wakeup_tracer_stop,
381         .print_max      = 1,
382 #ifdef CONFIG_FTRACE_SELFTEST
383         .selftest    = trace_selftest_startup_wakeup,
384 #endif
385 };
386
387 static struct tracer wakeup_rt_tracer __read_mostly =
388 {
389         .name           = "wakeup_rt",
390         .init           = wakeup_rt_tracer_init,
391         .reset          = wakeup_tracer_reset,
392         .start          = wakeup_tracer_start,
393         .stop           = wakeup_tracer_stop,
394         .wait_pipe      = poll_wait_pipe,
395         .print_max      = 1,
396 #ifdef CONFIG_FTRACE_SELFTEST
397         .selftest    = trace_selftest_startup_wakeup,
398 #endif
399 };
400
401 __init static int init_wakeup_tracer(void)
402 {
403         int ret;
404
405         ret = register_tracer(&wakeup_tracer);
406         if (ret)
407                 return ret;
408
409         ret = register_tracer(&wakeup_rt_tracer);
410         if (ret)
411                 return ret;
412
413         return 0;
414 }
415 device_initcall(init_wakeup_tracer);