Messages in this thread Patch in this message | | | Date | Mon, 22 May 2006 16:14:28 -0400 | From | Dave Jones <> | Subject | Re: [PATCH] s390: next_timer_interrupt overflow in stop_hz_timer |
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On Sun, May 21, 2006 at 09:00:51PM +0000, Linux Kernel wrote: > commit 92f63cd000059366af18712367216d96180e0ec0 > tree 4f88c3875afaa8183d6cfcff685e03ac7684d82d > parent 0662b71322e211dba9a4bc0e6fbca7861a2b5a7d > author Martin Schwidefsky <schwidefsky@de.ibm.com> Sun, 21 May 2006 05:00:25 -0700 > committer Linus Torvalds <torvalds@g5.osdl.org> Mon, 22 May 2006 02:59:21 -0700 > > [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> > > arch/s390/kernel/time.c | 2 +- > 1 files changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c > index 029f099..ce19ad4 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. */
arch/s390/kernel/time.c: In function 'stop_hz_timer': arch/s390/kernel/time.c:275: error: expected ')' before 'next' arch/s390/kernel/time.c:275: error: expected ')' before 'jiffies'
Dave
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