linux-kernel - Re: [PATCH] clockevent: don't remove broadcast device when cpu is dead

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Message-ID: <4B4BDD7B.2070308@redhat.com>
Date:	Tue, 12 Jan 2010 10:24:59 +0800
From:	Xiaotian Feng <dfeng@...hat.com>
To:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Magnus Damm <damm@...l.co.jp>,
	H Hartley Sweeten <hsweeten@...ionengravers.com>
CC:	Xiaotian Feng <dfeng@...hat.com>, stable@...nel.org
Subject: Re: [PATCH] clockevent: don't remove broadcast device when cpu is
 dead

Hi:

     Any comments on the patch? Marc confirmed this patch also fixed his 
hang at suspend/resume stage. Thanks.

     (Cc'ed stable@...nel.org)

Regards
Xiaotian

On 01/07/2010 11:22 AM, Xiaotian Feng wrote:
> Marc reported BUG during shutdown, after debugging, kernel is trying
> to remove a broadcast device which mode is CLOCK_EVT_MODE_ONESHOT.
>
> The root cause for this bug is that in clockevents_notify,
> "cpumask_weight(dev->cpumask) == 1" is always true even if dev is a
> broadcast device. We need to use tick_is_broadcast_device to check
> if it is a broadcast device.
>
> Reported-by: Marc Dionne<marc.c.dionne@...il.com>
> Tested-by: Marc Dionne<marc.c.dionne@...il.com>
> Signed-off-by: Xiaotian Feng<dfeng@...hat.com>
> Cc: Thomas Gleixner<tglx@...utronix.de>
> Cc: Magnus Damm<damm@...l.co.jp>
> Cc: H Hartley Sweeten<hsweeten@...ionengravers.com>
> ---
>   kernel/time/clockevents.c |    2 +-
>   1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
> index 6f740d9..0223d83 100644
> --- a/kernel/time/clockevents.c
> +++ b/kernel/time/clockevents.c
> @@ -259,7 +259,7 @@ void clockevents_notify(unsigned long reason, void *arg)
>   		cpu = *((int *)arg);
>   		list_for_each_entry_safe(dev, tmp,&clockevent_devices, list) {
>   			if (cpumask_test_cpu(cpu, dev->cpumask)&&
> -			    cpumask_weight(dev->cpumask) == 1) {
> +			    !tick_is_broadcast_device(dev)) {
>   				BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
>   				list_del(&dev->list);
>   			}
>    

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