linux-kernel - Re: [PATCH] x86, vsyscall: Fix build warning in vsyscall

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Date:	Mon, 13 Jun 2011 09:03:22 -0400
From:	Andrew Lutomirski <luto@....edu>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Rakib Mullick <rakib.mullick@...il.com>, hpa@...or.com,
	tglx@...utronix.de, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86, vsyscall: Fix build warning in vsyscall_64.c

On Mon, Jun 13, 2011 at 5:29 AM, Ingo Molnar <mingo@...e.hu> wrote:
>
> * Andrew Lutomirski <luto@....edu> wrote:
>
>> On Sat, Jun 11, 2011 at 3:31 AM, Rakib Mullick <rakib.mullick@...il.com> wrote:
>> > Due to commit 5cec93c216db77 (x86-64: Emulate legacy vsyscalls), we get the following warning:
>> >
>> >   arch/x86/kernel/vsyscall_64.c: In function ‘do_emulate_vsyscall’:
>> >   arch/x86/kernel/vsyscall_64.c:111:7: warning: ‘ret’ may be used uninitialized in this function
>>
>> What's the code path that uses ret without initializing it?
>
> If the code is correct but GCC got confused then please use the
> simplest possible patch to help GCC find its way around the code.

The simplest patch is to mark ret as uninitialized_var.

Before making that change, though, I'd like to try to reproduce this,
since it's possible that something's wrong with the BUG macro.  That's
why I'm waiting to hear what gcc version gets the warning.

--Andy
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