From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner+w=401wt.eu-S1752347AbXC3Tvy@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752347AbXC3Tvy (ORCPT <rfc822;w@1wt.eu>);
	Fri, 30 Mar 2007 15:51:54 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753119AbXC3Tvy
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Fri, 30 Mar 2007 15:51:54 -0400
Received: from ns2.suse.de ([195.135.220.15]:46017 "EHLO mx2.suse.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752347AbXC3Tvx (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Fri, 30 Mar 2007 15:51:53 -0400
Date: Fri, 30 Mar 2007 12:49:56 -0700
From: Greg KH <gregkh@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
       Mitch Williams <mitch.a.williams@intel.com>,
       linux-pci@atrey.karlin.mff.cuni.cz, linux-kernel@vger.kernel.org,
       auke-jan.h.kok@intel.com
Subject: Re: [PATCH 2.6.21-rc5] Flush MSI-X table writes (rev 3)
Message-ID: <20070330194956.GA8028@suse.de>
References: <1175280848.17652.5.camel@strongmad> <m1irciime5.fsf@ebiederm.dsl.xmission.com> <20070330124747.f20c9eb0.akpm@linux-foundation.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20070330124747.f20c9eb0.akpm@linux-foundation.org>
User-Agent: Mutt/1.5.14 (2007-02-12)
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Mar 30, 2007 at 12:47:47PM -0700, Andrew Morton wrote:
> On Fri, 30 Mar 2007 13:04:02 -0600
> ebiederm@xmission.com (Eric W. Biederman) wrote:
> 
> > Mitch Williams <mitch.a.williams@intel.com> writes:
> > 
> > > This patch fixes a kernel bug which is triggered when using the
> > > irqbalance daemon with MSI-X hardware.
> > >
> > > Because both MSI-X interrupt messages and MSI-X table writes are posted,
> > > it's possible for them to cross while in-flight.  This results in
> > > interrupts being received long after the kernel thinks they're disabled,
> > > and in interrupts being sent to stale vectors after rebalancing.
> > >
> > > This patch performs a read flush after writes to the MSI-X table for
> > > mask and unmask operations.  Since the SMP affinity is set while
> > > the interrupt is masked, and since it's unmasked immediately after,
> > > no additional flushes are required in the various affinity setting
> > > routines.
> > >
> > > This patch has been validated with (unreleased) network hardware which
> > > uses MSI-X.
> > >
> > > Revised with input from Eric Biederman.
> > 
> > Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
> 
> Did we end up deciding whether this is (needed*safe) enough for 2.6.21?

I say no for now, I have seen no bug reports for any hardware that is
not in a lab for this.

thanks,

greg k-h