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Commit 7e18d8e7 authored by Steven Rostedt's avatar Steven Rostedt Committed by Thomas Gleixner
Browse files

ftrace: add function tracing to wake up tracing 



This patch adds function tracing to the functions that are called
on the CPU of the task being traced.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Cc: pq@iki.fi
Cc: proski@gnu.org
Cc: sandmann@redhat.com
Cc: a.p.zijlstra@chello.nl
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 4902f884

kernel/trace/trace_sched_wakeup.c

+66 −1
Original line number Diff line number Diff line
@@ -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);