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authorIngo Molnar <mingo@kernel.org>2012-08-04 21:21:14 +0200
committerIngo Molnar <mingo@kernel.org>2012-08-05 12:37:14 +0200
commit1d17d17484d40f2d5b35c79518597a2b25296996 (patch)
treea11000cb9a7197b5d70573d0faa417cb36ba0e4b /kernel/time
parente7882d6c40874a5b5033ca85f7508a602a60b662 (diff)
time: Fix adjustment cleanup bug in timekeeping_adjust()
Tetsuo Handa reported that sporadically the system clock starts counting up too quickly which is enough to confuse the hangcheck timer to print a bogus stall warning. Commit 2a8c0883 "time: Move xtime_nsec adjustment underflow handling timekeeping_adjust" overlooked this exit path: } else return; which should really be a proper exit sequence, fixing the bug as a side effect. Also make the flow more readable by properly balancing curly braces. Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote: Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote: Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: john.stultz@linaro.org Cc: a.p.zijlstra@chello.nl Cc: richardcochran@gmail.com Cc: prarit@redhat.com Link: http://lkml.kernel.org/r/20120804192114.GA28347@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/timekeeping.c31
1 files changed, 17 insertions, 14 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 2988bc819187..e16af197a2bc 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -923,20 +923,22 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
if (likely(error <= interval))
adj = 1;
else
- adj = timekeeping_bigadjust(tk, error, &interval,
- &offset);
- } else if (error < -interval) {
- /* See comment above, this is just switched for the negative */
- error >>= 2;
- if (likely(error >= -interval)) {
- adj = -1;
- interval = -interval;
- offset = -offset;
- } else
- adj = timekeeping_bigadjust(tk, error, &interval,
- &offset);
- } else
- return;
+ adj = timekeeping_bigadjust(tk, error, &interval, &offset);
+ } else {
+ if (error < -interval) {
+ /* See comment above, this is just switched for the negative */
+ error >>= 2;
+ if (likely(error >= -interval)) {
+ adj = -1;
+ interval = -interval;
+ offset = -offset;
+ } else {
+ adj = timekeeping_bigadjust(tk, error, &interval, &offset);
+ }
+ } else {
+ goto out_adjust;
+ }
+ }
if (unlikely(tk->clock->maxadj &&
(tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) {
@@ -999,6 +1001,7 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
tk->xtime_nsec -= offset;
tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
+out_adjust:
/*
* It may be possible that when we entered this function, xtime_nsec
* was very small. Further, if we're slightly speeding the clocksource