linux-kernel - Re: [PATCH] cfs: NULL pointer check

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Date:	Fri, 16 Sep 2011 13:57:58 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	Wang Xingchao <xingchao.wang@...el.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, peterz@...radead.org,
	alex.shi@...el.com
Subject: Re: [PATCH] cfs: NULL pointer check

On Fri, Sep 16, 2011 at 01:48:53PM -0400, Wang Xingchao wrote:
> se maybe NULL if cfs_rq->rb_leftmost is NULL

I don't think se could be NULL here. Because we call check_preempt_tick()
iff 'cfs_rq->nr_running > 1'.

Thanks,
Yong

> 
> Signed-off-by: Wang Xingchao <xingchao.wang@...el.com>
> ---
>  kernel/sched_fair.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> index fef0bfd..109b232 100644
> --- a/kernel/sched_fair.c
> +++ b/kernel/sched_fair.c
> @@ -1130,6 +1130,10 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
>  		return;
>  
>  	se = __pick_first_entity(cfs_rq);
> +
> +	if (!se)
> +		return;
> +
>  	delta = curr->vruntime - se->vruntime;
>  
>  	if (delta < 0)
> -- 
> 1.7.1
> 
> --
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