linux-kernel - Re: [PATCH] ftrace: '< 0' test on unsigned

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Message-ID: <alpine.DEB.2.00.0903011613000.4771@gandalf.stny.rr.com>
Date:	Sun, 1 Mar 2009 16:14:29 -0500 (EST)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Roel Kluin <roel.kluin@...il.com>
cc:	lkml <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] ftrace: '< 0' test on unsigned


On Sun, 1 Mar 2009, Roel Kluin wrote:

> or should this be fixed, with
> 
>         if (!cnt || cnt > DEFINE)
> 
> if so, what should DEFINE be?

Hi Roel,

Thanks, but I already put in the fix for this. Since Andrew pointed out
that cnt was unsigned in my "cut and paste" from this function. I went 
back and fixed it. There should be no DEFINE. cnt can never be less than 
zero, so simply checking for (!cnt) is sufficient.

-- Steve


> 
> This patch wasn't tested in any way.
> ------------------------------>8-------------8<---------------------------------
> cnt is unsigned, so the '< 0' test won't work.
> 
> Signed-off-by: Roel Kluin <roel.kluin@...il.com>
> ---
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index fdf913d..6dab415 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -1129,7 +1129,7 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
>  	size_t read = 0;
>  	ssize_t ret;
>  
> -	if (!cnt || cnt < 0)
> +	if (!cnt || (ssize_t)cnt < 0)
>  		return 0;
>  
>  	mutex_lock(&ftrace_regex_lock);
> 
> 
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