hrtimer: Fix /proc/timer_list regression

commit 507e123 (timer stats: Optimize by adding quick check to avoid
function calls) introduced a regression in /proc/timer_list.

/proc/timer_list shows now
 #0: <c27d46b0>, tick_sched_timer, S:01, <(null)>, /-1
instead of
 #0: <c27d46b0>, tick_sched_timer, S:01, hrtimer_start, swapper/0

Revert the hrtimer quick check for now. The optimization needs more
thought, but this is neither 2.6.32-rc7 nor stable material.

[ tglx: - Removed unrelated changes from the original patch
  	- Prevent unneccesary call to timer_stats_update_stats
	- massaged the changelog ]

Signed-off-by: Feng Tang <feng.tang@intel.com>
LKML-Reference: <alpine.LFD.2.00.0911181933540.24119@localhost.localdomain>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: stable@kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/hrtimer.h

@@ -446,7 +446,7 @@ 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_site))
+	if (likely(!timer_stats_active))
 		return;
 	timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
 				 timer->function, timer->start_comm, 0);
@@ -457,8 +457,6 @@ extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer,
 
 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
 {
-	if (likely(!timer_stats_active))
-		return;
 	__timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
 }