From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757867AbYJFX0t (ORCPT ); Mon, 6 Oct 2008 19:26:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756878AbYJFXWS (ORCPT ); Mon, 6 Oct 2008 19:22:18 -0400 Received: from mx2.suse.de ([195.135.220.15]:55076 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756545AbYJFXWR (ORCPT ); Mon, 6 Oct 2008 19:22:17 -0400 Date: Mon, 6 Oct 2008 16:17:29 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Thomas Gleixner , Ingo Molnar Subject: [patch 14/28] clockevents: prevent multiple init/shutdown Message-ID: <20081006231729.GO20567@suse.de> References: <20081006225949.357365087@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="timer-fix-04.patch" In-Reply-To: <20081006231639.GA20567@suse.de> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.25-stable review patch. If anyone has any objections, please let us know. ------------------ From: Thomas Gleixner commit 9c17bcda991000351cb2373f78be7e4b1c44caa3 upstream While chasing the C1E/HPET bugreports I went through the clock events code inch by inch and found that the broadcast device can be initialized and shutdown multiple times. Multiple shutdowns are not critical, but useless waste of time. Multiple initializations are simply broken. Another CPU might have the device in use already after the first initialization and the second init could just render it unusable again. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/time/tick-broadcast.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -209,7 +209,7 @@ static void tick_do_broadcast_on_off(voi struct clock_event_device *bc, *dev; struct tick_device *td; unsigned long flags, *reason = why; - int cpu; + int cpu, bc_stopped; spin_lock_irqsave(&tick_broadcast_lock, flags); @@ -227,6 +227,8 @@ static void tick_do_broadcast_on_off(voi if (!tick_device_is_functional(dev)) goto out; + bc_stopped = cpus_empty(tick_broadcast_mask); + switch (*reason) { case CLOCK_EVT_NOTIFY_BROADCAST_ON: case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: @@ -248,9 +250,10 @@ static void tick_do_broadcast_on_off(voi break; } - if (cpus_empty(tick_broadcast_mask)) - clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); - else { + if (cpus_empty(tick_broadcast_mask)) { + if (!bc_stopped) + clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); + } else if (bc_stopped) { if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) tick_broadcast_start_periodic(bc); else @@ -500,9 +503,12 @@ static void tick_broadcast_clear_oneshot */ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { - bc->event_handler = tick_handle_oneshot_broadcast; - clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); - bc->next_event.tv64 = KTIME_MAX; + /* Set it up only once ! */ + if (bc->event_handler != tick_handle_oneshot_broadcast) { + bc->event_handler = tick_handle_oneshot_broadcast; + clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); + bc->next_event.tv64 = KTIME_MAX; + } } /* --