softlockup: Stop spurious softlockup messages due to overflow
Colin Ian King [Fri, 19 Mar 2010 10:28:02 +0000 (10:28 +0000)]
Ensure additions on touch_ts do not overflow.  This can occur
when the top 32 bits of the TSC reach 0xffffffff causing
additions to touch_ts to overflow and this in turn generates
spurious softlockup warnings.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: <stable@kernel.org>
LKML-Reference: <1268994482.1798.6.camel@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/softlockup.c

index 0d4c789..4b493f6 100644 (file)
@@ -155,11 +155,11 @@ void softlockup_tick(void)
         * Wake up the high-prio watchdog task twice per
         * threshold timespan.
         */
-       if (now > touch_ts + softlockup_thresh/2)
+       if (time_after(now - softlockup_thresh/2, touch_ts))
                wake_up_process(per_cpu(softlockup_watchdog, this_cpu));
 
        /* Warn about unreasonable delays: */
-       if (now <= (touch_ts + softlockup_thresh))
+       if (time_before_eq(now - softlockup_thresh, touch_ts))
                return;
 
        per_cpu(softlockup_print_ts, this_cpu) = touch_ts;