From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753469Ab2DROSo (ORCPT ); Wed, 18 Apr 2012 10:18:44 -0400 Received: from na3sys009aog118.obsmtp.com ([74.125.149.244]:44505 "EHLO na3sys009aog118.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751064Ab2DROSm (ORCPT ); Wed, 18 Apr 2012 10:18:42 -0400 Message-ID: <4F8ECD39.3080900@ti.com> Date: Wed, 18 Apr 2012 19:48:33 +0530 From: Santosh Shilimkar User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120329 Thunderbird/11.0.1 MIME-Version: 1.0 To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, suresh.b.siddha@intel.com, svenjoac@gmx.de, tglx@linutronix.de, rjw@sisk.pl CC: linux-tip-commits@vger.kernel.org Subject: Re: [tip:timers/urgent] tick: Fix oneshot broadcast setup really References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 18 April 2012 06:49 PM, Shilimkar, Santosh wrote: > On Wed, Apr 18, 2012 at 5:37 PM, tip-bot for Thomas Gleixner > wrote: >> Commit-ID: b435092f70ec5ebbfb6d075d5bf3c631b49a51de >> Gitweb: http://git.kernel.org/tip/b435092f70ec5ebbfb6d075d5bf3c631b49a51de >> Author: Thomas Gleixner >> AuthorDate: Wed, 18 Apr 2012 12:08:23 +0200 >> Committer: Thomas Gleixner >> CommitDate: Wed, 18 Apr 2012 14:00:56 +0200 >> >> tick: Fix oneshot broadcast setup really >> >> Sven Joachim reported, that suspend/resume on rc3 trips over a NULL >> pointer dereference. Linus spotted the clockevent handler being NULL. >> >> commit fa4da365b(clockevents: tTack broadcast device mode change in >> tick_broadcast_switch_to_oneshot()) tried to fix a problem with the >> broadcast device setup, which was introduced in commit 77b0d60c5( >> clockevents: Leave the broadcast device in shutdown mode when not >> needed). >> >> The initial commit avoided to set up the broadcast device when no >> broadcast request bits were set, but that left the broadcast device >> disfunctional. In consequence deep idle states which need the >> broadcast device were not woken up. >> >> commit fa4da365b tried to fix that by initializing the state of the >> broadcast facility, but that missed the fact, that nothing initializes >> the event handler and some other state of the underlying clock event >> device. >> >> The fix is to revert both commits and make only the mode setting of >> the clock event device conditional on the state of active broadcast >> users. >> >> That initializes everything except the low level device mode, but this >> happens when the broadcast functionality is invoked by deep idle. >> >> Reported-and-tested-by: Sven Joachim >> Signed-off-by: Thomas Gleixner >> Cc: Rafael J. Wysocki >> Cc: Linus Torvalds >> Cc: Suresh Siddha >> Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1204181205540.2542@ionos >> >> --- >> kernel/time/tick-broadcast.c | 7 +------ >> 1 files changed, 1 insertions(+), 6 deletions(-) >> >> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c >> index bf57abd..119aca5 100644 >> --- a/kernel/time/tick-broadcast.c >> +++ b/kernel/time/tick-broadcast.c >> @@ -531,7 +531,6 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) >> int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC; >> >> bc->event_handler = tick_handle_oneshot_broadcast; >> - clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); >> >> /* Take the do_timer update */ >> tick_do_timer_cpu = cpu; >> @@ -549,6 +548,7 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) >> to_cpumask(tmpmask)); >> >> if (was_periodic && !cpumask_empty(to_cpumask(tmpmask))) { >> + clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); For some reason above if() check fails in my case, so broadcast device never set to ONESHOT mode. That explains the problem I am seeing on OMAP with the $subject patch. At this point of time bc->mode is CLOCK_EVT_MODE_UNUSED. Regards Santosh