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| author |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2006-05-20 15:00:25 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@g5.osdl.org> | 2006-05-21 12:59:21 -0700 |
| commit | 92f63cd000059366af18712367216d96180e0ec0 (patch) | |
| tree | 4f88c3875afaa8183d6cfcff685e03ac7684d82d /arch/s390 | |
| parent | [PATCH] Fix a NO_IDLE_HZ timer bug (diff) | |
| download | linux-dev-92f63cd000059366af18712367216d96180e0ec0.tar.xz linux-dev-92f63cd000059366af18712367216d96180e0ec0.zip | |
[PATCH] s390: next_timer_interrupt overflow in stop_hz_timer
The 32 bit unsigned substraction (next - jiffies) in stop_hz_timer can
overflow if jiffies gets advanced between next_timer_interrupt and the read
under the xtime lock. The cast to a u64 then results in a large value
which causes the cpu to wait too long. Fix this by casting next and
jiffies independently to u64 before subtracting them.
(Spotted by Zachary Amsden <zach@vmware.com>)
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/kernel/time.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index 029f09901b85..ce19ad4e92ec 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -272,7 +272,7 @@ static inline void stop_hz_timer(void) next = next_timer_interrupt(); do { seq = read_seqbegin_irqsave(&xtime_lock, flags); - timer = (__u64)(next - jiffies) + jiffies_64; + timer = (__u64 next) - (__u64 jiffies) + jiffies_64; } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); todval = -1ULL; /* Be careful about overflows. */ |