From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751406Ab3EEGVA (ORCPT ); Sun, 5 May 2013 02:21:00 -0400 Received: from terminus.zytor.com ([198.137.202.10]:60385 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751298Ab3EEGU6 (ORCPT ); Sun, 5 May 2013 02:20:58 -0400 Date: Sat, 4 May 2013 23:20:29 -0700 From: tip-bot for Thomas Gleixner Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de, prarit@redhat.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, prarit@redhat.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/urgent] tick: Cleanup NOHZ per cpu data on cpu down Git-Commit-ID: ae7868e241c015aadc8632d9fe633a102a5918f6 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: ae7868e241c015aadc8632d9fe633a102a5918f6 Gitweb: http://git.kernel.org/tip/ae7868e241c015aadc8632d9fe633a102a5918f6 Author: Thomas Gleixner AuthorDate: Fri, 3 May 2013 15:02:50 +0200 Committer: Thomas Gleixner CommitDate: Sun, 5 May 2013 08:15:11 +0200 tick: Cleanup NOHZ per cpu data on cpu down Prarit reported a crash on CPU offline/online. The reason is that on CPU down the NOHZ related per cpu data of the dead cpu is not cleaned up. If at cpu online an interrupt happens before the per cpu tick device is registered the irq_enter() check potentially sees stale data and dereferences a NULL pointer. Cleanup the data after the cpu is dead. Reported-by: Prarit Bhargava Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305031451561.2886@ionos Signed-off-by: Thomas Gleixner --- kernel/time/tick-common.c | 1 + kernel/time/tick-internal.h | 6 ++++++ kernel/time/tick-sched.c | 7 +++++++ 3 files changed, 14 insertions(+) diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c index 6176a3e..29b765d 100644 --- a/kernel/time/tick-common.c +++ b/kernel/time/tick-common.c @@ -387,6 +387,7 @@ static int tick_notify(struct notifier_block *nb, unsigned long reason, tick_shutdown_broadcast_oneshot(dev); tick_shutdown_broadcast(dev); tick_shutdown(dev); + tick_shutdown_nohz(dev); break; case CLOCK_EVT_NOTIFY_SUSPEND: diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h index f0299ea..9644b29 100644 --- a/kernel/time/tick-internal.h +++ b/kernel/time/tick-internal.h @@ -144,3 +144,9 @@ static inline int tick_device_is_functional(struct clock_event_device *dev) #endif extern void do_timer(unsigned long ticks); + +#ifdef CONFIG_NO_HZ +extern void tick_shutdown_nohz(unsigned int *cpup); +#else +static inline void tick_shutdown_nohz(unsigned int *cpup) { } +#endif diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 225f8bf..e985ccd 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -797,6 +797,13 @@ static inline void tick_check_nohz(int cpu) } } +void tick_shutdown_nohz(unsigned int *cpup) +{ + struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); + + memset(ts, 0, sizeof(*ts)); +} + #else static inline void tick_nohz_switch_to_nohz(void) { }