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authorJohn Stultz <john.stultz@linaro.org>2014-11-24 20:35:45 -0800
committerIngo Molnar <mingo@kernel.org>2014-11-25 07:18:34 +0100
commitcb2aa63469f81426c7406227be70b628b42f7a05 (patch)
treed60788e5bc21d11592a0e3c42c44443789f4dd6b /kernel/time
parent21b6c0512e8aca75ce76365e1aef9fb16e007100 (diff)
time: Fix sign bug in NTP mult overflow warning
In commit 6067dc5a8c2b ("time: Avoid possible NTP adjustment mult overflow") a new check was added to watch for adjustments that could cause a mult overflow. Unfortunately the check compares a signed with unsigned value and ignored the case where the adjustment was negative, which causes spurious warn-ons on some systems (and seems like it would result in problematic time adjustments there as well, due to the early return). Thus this patch adds a check to make sure the adjustment is positive before we check for an overflow, and resovles the issue in my testing. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Debugged-by: pang.xunlei <pang.xunlei@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Link: http://lkml.kernel.org/r/1416890145-30048-1-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/timekeeping.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 29a7d6709da1..2dc0646258ae 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1330,7 +1330,7 @@ static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
*
* XXX - TODO: Doc ntp_error calculation.
*/
- if (tk->tkr.mult + mult_adj < mult_adj) {
+ if ((mult_adj > 0) && (tk->tkr.mult + mult_adj < mult_adj)) {
/* NTP adjustment caused clocksource mult overflow */
WARN_ON_ONCE(1);
return;