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Re: [PATCH] make ps2 mouse work ...

To: Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] make ps2 mouse work ...
From: Vojtech Pavlik <vojtech@suse.cz>
Date: Wed, 16 Jun 2004 14:11:49 +0200
Cc: Jun Sun <jsun@mvista.com>, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org
In-reply-to: <20040615205611.1e9cbfcc.akpm@osdl.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20040615191023.G28403@mvista.com> <20040615205611.1e9cbfcc.akpm@osdl.org>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.4.1i
On Tue, Jun 15, 2004 at 08:56:11PM -0700, Andrew Morton wrote:

> > I found this problem on a MIPS machine.  The problem is 
> > likely to happen on other register-rich RISC arches too.
> > 
> > cmdcnt needs to be volatile since it is modified by
> > irq routine and read by normal process context.
> 
> volatile is not the preferred way to fix this up.  This points at either a
> locking error in the psmouse driver or a missing "memory" thingy in the
> mips port somewhere.
> 
> Please describe the bug which led to this patch.  Where was it getting stuck?

My current BK tree has this fixed using atomic bitfields, which do
compilation and memory barriers. I plan to sync it to Linus post 2.6.7.

-- 
Vojtech Pavlik
SuSE Labs, SuSE CR

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