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SubjectRe: [PATCH] fix potential jiffies overflow
On 3/2/06, Atsushi Nemoto <anemo@mba.ocn.ne.jp> wrote:
> I found i386 timer_resume is updating jiffies, not jiffies_64. It
> looks there is a potential overflow problem. Is this a correct fix?
>
> Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
>
> diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
> index a14d594..e4ed172 100644
> --- a/arch/i386/kernel/time.c
> +++ b/arch/i386/kernel/time.c
> @@ -413,7 +413,7 @@ static int timer_resume(struct sys_devic
> xtime.tv_sec = sec;
> xtime.tv_nsec = 0;
> write_sequnlock_irqrestore(&xtime_lock, flags);
> - jiffies += sleep_length;
> + jiffies_64 += sleep_length;
> wall_jiffies += sleep_length;
> if (last_timer->resume)
> last_timer->resume();


The 64-bit jiffies value is not atomic. You need to hold xtime_lock to read it.
-
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