[PATCH 3.4 70/92] clocksource: Fix abs() usage w/ 64bit values

lizf
2016-04-18T11:02:11Z

From: John Stultz <john.stultz@linaro.org>

3.4.112-rc1 review patch. If anyone has any objections, please let me know.

------------------

commit 67dfae0cd72fec5cd158b6e5fb1647b7dbe0834c upstream.

This patch fixes one cases where abs() was being used with 64-bit
nanosecond values, where the result may be capped at 32-bits.

This potentially could cause watchdog false negatives on 32-bit
systems, so this patch addresses the issue by using abs64().

Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1442279124-7309-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
kernel/time/clocksource.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index c958338..b3f5407 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -291,7 +291,7 @@ static void clocksource_watchdog(unsigned long data)
continue;

/* Check the deviation from the watchdog clocksource. */
- if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) {
+ if ((abs64(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) {
clocksource_unstable(cs, cs_nsec - wd_nsec);
continue;
}
--
1.9.1