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To: afranck@gmx.de
Cc: David Howells <dhowells@cambridge.redhat.com>,
        Linus Torvalds <torvalds@transmeta.com>,
        Andrew Morton <andrewm@uow.edu.au>, Ben LaHaise <bcrl@redhat.com>,
        Alan Cox <alan@lxorguk.ukuu.org.uk>,
        Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] 2nd try: i386 rw_semaphores fix 
In-Reply-To: Your message of "Wed, 11 Apr 2001 15:40:21 +0200."
             <3AD45EC5.81EB82AD@akustik.rwth-aachen.de> 
Date: Wed, 11 Apr 2001 15:17:19 +0100
Message-ID: <16795.986998639@warthog.cambridge.redhat.com>
From: David Howells <dhowells@cambridge.redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org

> I'd like you to look over it. It seems newer GCC's (snapshots and the
> upcoming 3.0) will be more strict when modifying some values through
> assembler-passed pointers - in this case, the passed semaphore structure got
> freed too early, causing massive stack corruption on early bootup.
>
> The solution was to directly mention the modified element (in this case,
> sem->count) with a "=m" qualifier, which told GCC that the contents of the
> semaphore structure are still really needed. It does not seem to have any
> bad side effects on older GCC, but lets the code work on people trying to
> use the newer snapshots.

I've just consulted with one of the gcc people we have here, and he says that
the '"memory"' constraint should do the trick.

Do I take it that that is actually insufficient?

David
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