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
......@@ -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);
......
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