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Date: Thu, 2 Mar 2006 19:48:41 -0800
From: Andrew Morton <akpm@osdl.org>
To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: ram.gupta5@gmail.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fix potential jiffies overflow
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Atsushi Nemoto <anemo@mba.ocn.ne.jp> wrote:
>
> >>>>> On Thu, 2 Mar 2006 18:45:02 -0800, Andrew Morton <akpm@osdl.org> said:
> akpm> Thanks, that looks like 2.6.16 material.
> 
> akpm> What happens if the machine slept for more than 49.7 days?
> 
> Well, jiffies will lose 49.7 days...  Then, how about this?  We can
> sleep 136 years.
> 
> 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..be5d079 100644
> --- a/arch/i386/kernel/time.c
> +++ b/arch/i386/kernel/time.c
> @@ -400,7 +400,7 @@ static int timer_resume(struct sys_devic
>  {
>  	unsigned long flags;
>  	unsigned long sec;
> -	unsigned long sleep_length;
> +	u64 sleep_length;
>  
>  #ifdef CONFIG_HPET_TIMER
>  	if (is_hpet_enabled())
> @@ -408,7 +408,7 @@ static int timer_resume(struct sys_devic
>  #endif
>  	setup_pit_timer();
>  	sec = get_cmos_time() + clock_cmos_diff;
> -	sleep_length = (get_cmos_time() - sleep_start) * HZ;
> +	sleep_length = (u64)(get_cmos_time() - sleep_start) * HZ;
>  	write_seqlock_irqsave(&xtime_lock, flags);
>  	xtime.tv_sec = sec;
>  	xtime.tv_nsec = 0;

but...

	wall_jiffies += sleep_length;

wall_jiffies is 32-bit.