linux-kernel - Re: [PATCH] epoll: initialize slack for negative timeout values

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Message-ID: <alpine.DEB.2.00.1011271057110.28998@davide-lnx1>
Date:	Sat, 27 Nov 2010 10:58:32 -0800 (PST)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Shawn Bohrer <shawn.bohrer@...il.com>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Mike Frysinger <vapier.adi@...il.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] epoll: initialize slack for negative timeout values

On Wed, 24 Nov 2010, Shawn Bohrer wrote:

> When a negative timeout value is passed to epoll the 'slack' variable is
> currently uninitialized:
> 
> fs/eventpoll.c: In function ‘ep_poll’:
> fs/eventpoll.c:1119: warning: ‘slack’ may be used uninitialized in this function
> 
> In this case a NULL pointer is passed to schedule_hrtimeout_range()
> specifying an infinite timeout.  The current implementation of
> schedule_hrtimeout_range() does not use slack in this case, but we
> should still initialize slack to 0 in case future implementations use it.

Thanks.


> Signed-off-by: Shawn Bohrer <shawn.bohrer@...il.com>

Acked-by: Davide Libenzi <davidel@...ilserver.org>



> ---
>  fs/eventpoll.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/eventpoll.c b/fs/eventpoll.c
> index 8cf0724..c24a032 100644
> --- a/fs/eventpoll.c
> +++ b/fs/eventpoll.c
> @@ -1116,7 +1116,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
>  {
>  	int res, eavail, timed_out = 0;
>  	unsigned long flags;
> -	long slack;
> +	long slack = 0;
>  	wait_queue_t wait;
>  	struct timespec end_time;
>  	ktime_t expires, *to = NULL;



- Davide