Messages in this thread | | | Date | Thu, 2 Mar 2006 18:45:02 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] fix potential jiffies overflow |
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Atsushi Nemoto <anemo@mba.ocn.ne.jp> wrote: > > >>>>> On Thu, 2 Mar 2006 10:43:12 -0600, "Ram Gupta" <ram.gupta5@gmail.com> said: > >> I found i386 timer_resume is updating jiffies, not jiffies_64. It > >> looks there is a potential overflow problem. Is this a correct > >> fix? > > ram> The 64-bit jiffies value is not atomic. You need to hold > ram> xtime_lock to read it. > > OK, and I guess wall_jiffies also needs xtime_lock. > > > I found i386 timer_resume is updating jiffies, not jiffies_64. It > looks there is a potential overflow problem. And jiffies_64 and > wall_jiffies should be protected by xtime_lock. > > 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..9d30747 100644 > --- a/arch/i386/kernel/time.c > +++ b/arch/i386/kernel/time.c > @@ -412,9 +412,9 @@ static int timer_resume(struct sys_devic > write_seqlock_irqsave(&xtime_lock, flags); > 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; > + write_sequnlock_irqrestore(&xtime_lock, flags); > if (last_timer->resume) > last_timer->resume(); > cur_timer = last_timer;
Thanks, that looks like 2.6.16 material.
What happens if the machine slept for more than 49.7 days?
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