linux-kernel - [RFC PATCH 4/6] hrtimer: change call site of timer_stats_hrtimer_clear_start

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Date:	Sun, 29 Aug 2010 23:05:07 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	tglx@...utronix.de, akpm@...ux-foundation.org, mingo@...e.hu,
	arjan@...ux.intel.com, a.p.zijlstra@...llo.nl, tj@...nel.org,
	oleg@...hat.com
Subject: [RFC PATCH 4/6] hrtimer: change call site of timer_stats_hrtimer_clear_start_info()

From: Yong Zhang <yong.zhang@...driver.com>

Put timer_stats_hrtimer_clear_start_info() to the real cancel
place.

Because remove_hrtimer() is used for internal, and it could be called
as below:
int __hrtimer_start_range_ns(ARG) {
	...
	remove_hrtimer();
	...
	timer_stats_hrtimer_set_start_info();
}

Then if remove_hrtimer() clear the start_site, the following
timer_stats_hrtimer_set_start_info() will record the caller of
__hrtimer_start_range_ns as start_site. But this is not what
we want.

Signed-off-by: Yong Zhang <yong.zhang0@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
 kernel/hrtimer.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index ce66917..2b79ab4 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -772,7 +772,7 @@ static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
 {
 #ifdef CONFIG_TIMER_STATS
-	if (likely(!timer_stats_active))
+	if (!timer->start_site)
 		return;
 	timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
 				 timer->function, timer->start_comm, 0);
@@ -942,7 +942,6 @@ remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
 		 * rare case and less expensive than a smp call.
 		 */
 		debug_deactivate(timer);
-		timer_stats_hrtimer_clear_start_info(timer);
 		reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases);
 		__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE,
 				 reprogram);
@@ -1055,9 +1054,10 @@ int hrtimer_try_to_cancel(struct hrtimer *timer)
 
 	base = lock_hrtimer_base(timer, &flags);
 
-	if (!hrtimer_callback_running(timer))
+	if (!hrtimer_callback_running(timer)){
+		timer_stats_hrtimer_clear_start_info(timer);
 		ret = remove_hrtimer(timer, base);
-
+	}
 	unlock_hrtimer_base(timer, &flags);
 
 	return ret;
-- 
1.7.0.4

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