From 1d17d17484d40f2d5b35c79518597a2b25296996 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@kernel.org>
Date: Sat, 4 Aug 2012 21:21:14 +0200
Subject: [PATCH] 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>
---
kernel/time/timekeeping.c | 31 +++++++++++++++++--------------
1 file 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
--
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