softlockup: Stop spurious softlockup messages due to overflow

commit 8c2eb4805d422bdbf60ba00ff233c794d23c3c00 upstream.

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>
LKML-Reference: <1268994482.1798.6.camel@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 81324d12eb35a5db7fae8a0ae3d18c76ca38ce67..d2080ad196fd0ffc950f63f6de4ae03cc189f780 100644 (file)
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -140,11 +140,11 @@ void softlockup_tick(void)
         * Wake up the high-prio watchdog task twice per
         * threshold timespan.
         */
-       if (now > touch_timestamp + softlockup_thresh/2)
+       if (time_after(now - softlockup_thresh/2, touch_timestamp))
                wake_up_process(per_cpu(watchdog_task, this_cpu));
 
        /* Warn about unreasonable delays: */
-       if (now <= (touch_timestamp + softlockup_thresh))
+       if (time_before_eq(now - softlockup_thresh, touch_timestamp))
                return;
 
        per_cpu(print_timestamp, this_cpu) = touch_timestamp;