timer: Avoid reading uninitialized data

timer->expires may be uninitialized, so check timer_pending() before
touching timer->expires to pacify kmemcheck.

Signed-off-by: Pavel Roskin <proski@gnu.org>
LKML-Reference: <20090718204602.5191.360.stgit@mj.roinet.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/timer.c

@@ -714,7 +714,7 @@ int mod_timer(struct timer_list *timer, unsigned long expires)
 	 * networking code - if the timer is re-modified
 	 * to be the same thing then just return:
 	 */
-	if (timer->expires == expires && timer_pending(timer))
+	if (timer_pending(timer) && timer->expires == expires)
 		return 1;
 
 	return __mod_timer(timer, expires, false, TIMER_NOT_PINNED);