linux-kernel - Re: [PATCH 1/9] trace: Fix uninitialized variable compiler warning

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Date:	Mon, 28 Nov 2011 11:19:18 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	fweisbec@...il.com, mingo@...hat.com, paulus@...ba.org,
	acme@...stprotocols.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/9] trace: Fix uninitialized variable compiler warning

On Sun, 2011-11-27 at 19:04 +0100, Jiri Olsa wrote:
> Initialize page2 variable to make compiler happy.

What compiler is this? Because this is a compiler bug. In fact, there's
no check for page2 being NULL, so if it is used uninitialized it will
crash the kernel. I don't like these "make the compiler shut up" fixes,
because honestly, changes like this hide bugs.

Nacked-by: Steven Rostedt <rostedt@...dmis.org>

-- Steve

> 
> Signed-off-by: Jiri Olsa <jolsa@...hat.com>
> ---
>  kernel/trace/trace.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 9e158cc..4a06862 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3655,8 +3655,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
>  	struct page *pages[2];
>  	int nr_pages = 1;
>  	ssize_t written;
> -	void *page1;
> -	void *page2;
> +	void *page1, *page2 = NULL;
>  	int offset;
>  	int size;
>  	int len;


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