From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Thu, 9 Jul 2009 09:24:26 +0000 (+0200)
Subject: timer stats: fix quick check optimization
X-Git-Tag: firefly_0821_release~13387^2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f9f868dbcca961ed62f1df1d114abd0c38c47dce;p=firefly-linux-kernel-4.4.55.git

timer stats: fix quick check optimization

git commit 507e1231 "timer stats: Optimize by adding quick check to
avoid function calls" added one wrong check so that one unnecessary
function call isn't elimated.

time_stats_account_hrtimer() checks if timer->start_pid isn't
initialized in order to find out if timer_stats_update_stats() should
be called.  However start_pid is initialized with -1 instead of 0, so
that the function call always happens.

Check timer->start_site like in timer_stats_account_timer() to fix
this.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 54648e625efd..4759917adc71 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -448,7 +448,7 @@ extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
 
 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
 {
-	if (likely(!timer->start_pid))
+	if (likely(!timer->start_site))
 		return;
 	timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
 				 timer->function, timer->start_comm, 0);