From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933194Ab2IFV3I (ORCPT ); Thu, 6 Sep 2012 17:29:08 -0400 Received: from ogre.sisk.pl ([193.178.161.156]:40616 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752024Ab2IFV3F convert rfc822-to-8bit (ORCPT ); Thu, 6 Sep 2012 17:29:05 -0400 From: "Rafael J. Wysocki" To: John Stultz Subject: Re: [PATCH] wakeup: Use irqsave/irqrestore for events_lock Date: Thu, 6 Sep 2012 23:35:22 +0200 User-Agent: KMail/1.13.6 (Linux/3.6.0-rc3+; KDE/4.6.0; x86_64; ; ) Cc: lkml , Android Team , Arve =?utf-8?q?Hj=C3=B8nnev=C3=A5g?= , "Jon Medhurst (Tixy)" References: <1346954857-52669-1-git-send-email-john.stultz@linaro.org> In-Reply-To: <1346954857-52669-1-git-send-email-john.stultz@linaro.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Message-Id: <201209062335.23013.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, September 06, 2012, John Stultz wrote: > Jon Medhurst (Tixy) recently noticed a problem with the > events_lock usage. One of the Android patches that uses > wakeup_sources calls wakeup_source_add() with irqs disabled. > However, the event_lock usage in wakeup_source_add() uses > spin_lock_irq()/spin_unlock_irq(), which reenables interrupts. > This results in lockdep warnings. > > The fix is to use spin_lock_irqsave()/spin_lock_irqrestore() > instead for the events_lock. > > Full bug report here: > https://bugs.launchpad.net/linaro-landing-team-arm/+bug/1037565 > > Cc: Rafael J. Wysocki > Cc: Android Team > Cc: Arve Hjønnevåg > Cc: Jon Medhurst (Tixy) > Reported-and-debugged-by: Jon Medhurst (Tixy) > Signed-off-by: John Stultz Thanks, applied to the linux-next brach of the linux-pm.git tree as v3.7 material. Please consider CCing PM-related patches to linux-pm@vger.kernel.org in the future, that makes it much easier for me to handle them. Thanks, Rafael > --- > drivers/base/power/wakeup.c | 17 +++++++++++------ > 1 file changed, 11 insertions(+), 6 deletions(-) > > diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c > index cbb463b..0e4b093 100644 > --- a/drivers/base/power/wakeup.c > +++ b/drivers/base/power/wakeup.c > @@ -127,6 +127,8 @@ EXPORT_SYMBOL_GPL(wakeup_source_destroy); > */ > void wakeup_source_add(struct wakeup_source *ws) > { > + unsigned long flags; > + > if (WARN_ON(!ws)) > return; > > @@ -135,9 +137,9 @@ void wakeup_source_add(struct wakeup_source *ws) > ws->active = false; > ws->last_time = ktime_get(); > > - spin_lock_irq(&events_lock); > + spin_lock_irqsave(&events_lock, flags); > list_add_rcu(&ws->entry, &wakeup_sources); > - spin_unlock_irq(&events_lock); > + spin_unlock_irqrestore(&events_lock, flags); > } > EXPORT_SYMBOL_GPL(wakeup_source_add); > > @@ -147,12 +149,14 @@ EXPORT_SYMBOL_GPL(wakeup_source_add); > */ > void wakeup_source_remove(struct wakeup_source *ws) > { > + unsigned long flags; > + > if (WARN_ON(!ws)) > return; > > - spin_lock_irq(&events_lock); > + spin_lock_irqsave(&events_lock, flags); > list_del_rcu(&ws->entry); > - spin_unlock_irq(&events_lock); > + spin_unlock_irqrestore(&events_lock, flags); > synchronize_rcu(); > } > EXPORT_SYMBOL_GPL(wakeup_source_remove); > @@ -723,15 +727,16 @@ bool pm_get_wakeup_count(unsigned int *count, bool block) > bool pm_save_wakeup_count(unsigned int count) > { > unsigned int cnt, inpr; > + unsigned long flags; > > events_check_enabled = false; > - spin_lock_irq(&events_lock); > + spin_lock_irqsave(&events_lock, flags); > split_counters(&cnt, &inpr); > if (cnt == count && inpr == 0) { > saved_count = count; > events_check_enabled = true; > } > - spin_unlock_irq(&events_lock); > + spin_unlock_irqrestore(&events_lock, flags); > return events_check_enabled; > } > >