From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761567AbZBLX2S (ORCPT ); Thu, 12 Feb 2009 18:28:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750764AbZBLX2F (ORCPT ); Thu, 12 Feb 2009 18:28:05 -0500 Received: from mail-fx0-f20.google.com ([209.85.220.20]:43201 "EHLO mail-fx0-f20.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751899AbZBLX2E (ORCPT ); Thu, 12 Feb 2009 18:28:04 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=AFu1es8XzCbubB0H3dd6I8gAbkYmpNvyTdHjtBJHjf5OTwfcgiCwlBQppYSJ+LhVis Q1dQUzIRCIfmzt9kl8tmgAxfPNTdDuYquUcQjhcnVKelk+UGT0IMn+Sdn9nD28OzROEV gO0T7G5fXXdiPRYQsO+tYyE6vql0H0XtWeFVc= Date: Fri, 13 Feb 2009 00:27:58 +0100 From: Frederic Weisbecker To: Arnaldo Carvalho de Melo Cc: Steven Rostedt , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] rt/threadirqs: don't need to save irqs in do_hardirq() Message-ID: <20090212232758.GA5865@nowhere> References: <4994ae18.1358560a.454d.403b@mx.google.com> <20090212232459.GD5348@ghostprotocols.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090212232459.GD5348@ghostprotocols.net> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 12, 2009 at 09:24:59PM -0200, Arnaldo Carvalho de Melo wrote: > Em Thu, Feb 12, 2009 at 07:27:08PM +0100, Frederic Weisbecker escreveu: > > do_hardirq() has only one caller do_irqd() in a path where irq are already > > disabled. So we don't need to save irqs while holding desc->lock > > > > Replace spin_lock_irqsave by spin_lock. > > > > Signed-off-by: Frederic Weisbecker > > --- > > kernel/irq/manage.c | 4 ++-- > > 1 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c > > index ed7c5e3..6e9baf8 100644 > > --- a/kernel/irq/manage.c > > +++ b/kernel/irq/manage.c > > @@ -905,7 +905,7 @@ static void do_hardirq(struct irq_desc *desc) > > { > > unsigned long flags; > > Can flags be removed too? Actually... I cheated. Once the two patches were done, I saw the unused variable warning. So I remade the second patch to remove flags but..yes it should be on the first patch, I must confess... > > - spin_lock_irqsave(&desc->lock, flags); > > + spin_lock(&desc->lock); > > > > if (!(desc->status & IRQ_INPROGRESS)) > > goto out; > > @@ -921,7 +921,7 @@ static void do_hardirq(struct irq_desc *desc) > > else > > thread_do_irq(desc); > > out: > > - spin_unlock_irqrestore(&desc->lock, flags); > > + spin_unlock(&desc->lock); > > > > if (waitqueue_active(&desc->wait_for_handler)) > > wake_up(&desc->wait_for_handler);