revert "clocksource: make clocksource watchdog cycle through online CPUs"

Revert commit 1ada5cba6a0318f90e45b38557e7b5206a9cba38 ("clocksource:
make clocksource watchdog cycle through online CPUs") due to the
regression reported by Gabriel C at

	http://lkml.org/lkml/2008/2/24/281

(short vesion: it makes TSC be marked as always unstable on his
machine).

Cc: Andi Kleen <ak@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Robert Hancock <hancockr@shaw.ca>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Gabriel C <nix.or.die@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/time/clocksource.c

@@ -141,13 +141,8 @@ static void clocksource_watchdog(unsigned long data)
 	}
 
 	if (!list_empty(&watchdog_list)) {
-		/* Cycle through CPUs to check if the CPUs stay synchronized to
-		 * each other. */
-		int next_cpu = next_cpu(raw_smp_processor_id(), cpu_online_map);
-		if (next_cpu >= NR_CPUS)
-			next_cpu = first_cpu(cpu_online_map);
-		watchdog_timer.expires += WATCHDOG_INTERVAL;
-		add_timer_on(&watchdog_timer, next_cpu);
+		__mod_timer(&watchdog_timer,
+			    watchdog_timer.expires + WATCHDOG_INTERVAL);
 	}
 	spin_unlock(&watchdog_lock);
 }
@@ -169,7 +164,7 @@ static void clocksource_check_watchdog(struct clocksource *cs)
 		if (!started && watchdog) {
 			watchdog_last = watchdog->read();
 			watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
-			add_timer_on(&watchdog_timer, first_cpu(cpu_online_map));
+			add_timer(&watchdog_timer);
 		}
 	} else {
 		if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
@@ -190,8 +185,7 @@ static void clocksource_check_watchdog(struct clocksource *cs)
 				watchdog_last = watchdog->read();
 				watchdog_timer.expires =
 					jiffies + WATCHDOG_INTERVAL;
-				add_timer_on(&watchdog_timer,
-						first_cpu(cpu_online_map));
+				add_timer(&watchdog_timer);
 			}
 		}
 	}