From: Andrew Morton <akpm@osdl.org>
Subject: Re: Fw: [Bugme-new] [Bug 4166] New: BUG: using smp_processor_id()
 in preemptible [00000001] code: nfsd/2783
Date: Mon, 7 Feb 2005 16:21:17 -0800
Message-ID: <20050207162117.2f791fca.akpm@osdl.org>
References: <20050204134809.2d341367.akpm@osdl.org>
	<20050207234119.GA13400@plap.qlogic.org>
	<20050207160056.0c50305e.akpm@osdl.org>
	<20050208000830.GA13631@plap.qlogic.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Received: from fw.osdl.org ([65.172.181.6]:43931 "EHLO mail.osdl.org")
	by vger.kernel.org with ESMTP id S261352AbVBHAQW (ORCPT
	<rfc822;linux-scsi@vger.kernel.org>); Mon, 7 Feb 2005 19:16:22 -0500
In-Reply-To: <20050208000830.GA13631@plap.qlogic.org>
Sender: linux-scsi-owner@vger.kernel.org
List-Id: linux-scsi@vger.kernel.org
To: Andrew Vasquez <andrew.vasquez@qlogic.com>
Cc: linux-scsi@vger.kernel.org, James.Bottomley@SteelEye.com

Andrew Vasquez <andrew.vasquez@qlogic.com> wrote:
>
> On Mon, 07 Feb 2005, Andrew Morton wrote:
> 
> > Andrew Vasquez <andrew.vasquez@qlogic.com> wrote:
> > >
> > > -	if (smp_processor_id() == ha->last_irq_cpu || was_empty)
> > > +	if (_smp_processor_id() == ha->last_irq_cpu || was_empty)
> > 
> > Am I correct in assuming that if we are preempted, and if
> > _smp_processor_id() returns the wrong number, the driver will continue to
> > function correctly?  And that we simply missed a little optimisation
> > opportunity?
> 
> Yes, the driver will continue to operate correctly.  Another
> suggestion made was to explicitly disable/enable preemption around the
> 'if' statement.  The s/smp_processor_id/_smp_processor_id/ seemed like
> the least intrusive option in the interim...

It makes perfect sense.  James, I'll add this to this evening's patchbatch.