diff options
| -rw-r--r-- | kernel/trace/trace_sched_wakeup.c | 67 |
1 files changed, 66 insertions, 1 deletions
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index 5d2fb48e47f..bf7e91caef5 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -30,6 +30,69 @@ static DEFINE_SPINLOCK(wakeup_lock); static void __wakeup_reset(struct trace_array *tr); +#ifdef CONFIG_FTRACE +/* + * irqsoff uses its own tracer function to keep the overhead down: + */ +static void +wakeup_tracer_call(unsigned long ip, unsigned long parent_ip) +{ + struct trace_array *tr = wakeup_trace; + struct trace_array_cpu *data; + unsigned long flags; + long disabled; + int resched; + int cpu; + + if (likely(!wakeup_task)) + return; + + resched = need_resched(); + preempt_disable_notrace(); + + cpu = raw_smp_processor_id(); + data = tr->data[cpu]; + disabled = atomic_inc_return(&data->disabled); + if (unlikely(disabled != 1)) + goto out; + + spin_lock_irqsave(&wakeup_lock, flags); + + if (unlikely(!wakeup_task)) + goto unlock; + + /* + * The task can't disappear because it needs to + * wake up first, and we have the wakeup_lock. + */ + if (task_cpu(wakeup_task) != cpu) + goto unlock; + + trace_function(tr, data, ip, parent_ip, flags); + + unlock: + spin_unlock_irqrestore(&wakeup_lock, flags); + + out: + atomic_dec(&data->disabled); + + /* + * To prevent recursion from the scheduler, if the + * resched flag was set before we entered, then + * don't reschedule. + */ + if (resched) + preempt_enable_no_resched_notrace(); + else + preempt_enable_notrace(); +} + +static struct ftrace_ops trace_ops __read_mostly = +{ + .func = wakeup_tracer_call, +}; +#endif /* CONFIG_FTRACE */ + /* * Should this new latency be reported/recorded? */ @@ -73,7 +136,7 @@ wakeup_sched_switch(void *private, void *rq, struct task_struct *prev, if (next != wakeup_task) return; - /* The task we are waitng for is waking up */ + /* The task we are waiting for is waking up */ data = tr->data[wakeup_cpu]; /* disable local data, not wakeup_cpu data */ @@ -290,6 +353,7 @@ static void start_wakeup_tracer(struct trace_array *tr) smp_wmb(); tracer_enabled = 1; + register_ftrace_function(&trace_ops); return; fail_deprobe_wake_new: @@ -305,6 +369,7 @@ fail_deprobe: static void stop_wakeup_tracer(struct trace_array *tr) { tracer_enabled = 0; + unregister_ftrace_function(&trace_ops); marker_probe_unregister("kernel_sched_schedule", sched_switch_callback, &wakeup_trace); |