linux-kernel - Re: [PATCH] fs/eventpoll.c: fix compilation warning

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Date:	Fri, 14 Jan 2011 09:33:16 +0000
From:	Jack Stone <jwjstone@...tmail.fm>
To:	Viresh Kumar <viresh.kumar@...com>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] fs/eventpoll.c: fix compilation warning




Viresh Kumar" <viresh.kumar@...com> wrote:

>This patch fixes following compilation warning
>fs/eventpoll.c:1119: warning: 'slack' may be used uninitialized in this
>function
>
>Signed-off-by: Viresh Kumar <viresh.kumar@...com>
>---
> 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;

I don't think this is the correct fix. This function is fine unless timeout is negative.

If a negative timeout is possible then this function will create timer far in the future. I'll leave it up to the maintainer how to solve that one. The two solutions I can see are making timeout unsigned or extending the bottom case of the if to <=0.

Either way we should use uninitalized_var() rather than setting it to zero.

Hope this makes sense,

Jack

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