From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937131AbZDIWml (ORCPT ); Thu, 9 Apr 2009 18:42:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761961AbZDIWmb (ORCPT ); Thu, 9 Apr 2009 18:42:31 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:54474 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761466AbZDIWma (ORCPT ); Thu, 9 Apr 2009 18:42:30 -0400 Date: Thu, 9 Apr 2009 15:39:21 -0700 From: Andrew Morton To: Atsushi Nemoto Cc: a.zummo@towertech.it, rtc-linux@googlegroups.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rtc: Make rtc_update_irq callable with irqs enabled Message-Id: <20090409153921.04b6384c.akpm@linux-foundation.org> In-Reply-To: <1239036633-10032-1-git-send-email-anemo@mba.ocn.ne.jp> References: <1239036633-10032-1-git-send-email-anemo@mba.ocn.ne.jp> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 7 Apr 2009 01:50:31 +0900 Atsushi Nemoto wrote: > The rtc_update_irq() might be called with irqs enabled, if a interrupt > handler was registered without IRQF_DISABLED. Why? What are the consequences of not merging the patch? Is it a bugfix? If so, what are the user-visible effects of the bug? See, I need to decide if this patch is needed in 2.6.30 (and earlier), but the changelog doesn't include enough info to make that decision. > Use spin_lock_irqsave/spin_unlock_irqrestore instead of > spin_lock/spin_unlock. > > Signed-off-by: Atsushi Nemoto > --- > drivers/rtc/interface.c | 10 ++++++---- > 1 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c > index 4348c4b..a8641f7 100644 > --- a/drivers/rtc/interface.c > +++ b/drivers/rtc/interface.c > @@ -376,14 +376,16 @@ EXPORT_SYMBOL_GPL(rtc_update_irq_enable); > void rtc_update_irq(struct rtc_device *rtc, > unsigned long num, unsigned long events) > { > - spin_lock(&rtc->irq_lock); > + unsigned long flags; > + > + spin_lock_irqsave(&rtc->irq_lock, flags); > rtc->irq_data = (rtc->irq_data + (num << 8)) | events; > - spin_unlock(&rtc->irq_lock); > + spin_unlock_irqrestore(&rtc->irq_lock, flags); > > - spin_lock(&rtc->irq_task_lock); > + spin_lock_irqsave(&rtc->irq_task_lock, flags); > if (rtc->irq_task) > rtc->irq_task->func(rtc->irq_task->private_data); > - spin_unlock(&rtc->irq_task_lock); > + spin_unlock_irqrestore(&rtc->irq_task_lock, flags); > > wake_up_interruptible(&rtc->irq_queue); > kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);