From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754691Ab3F0T7X (ORCPT ); Thu, 27 Jun 2013 15:59:23 -0400 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:49069 "EHLO e28smtp01.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754535Ab3F0T7R (ORCPT ); Thu, 27 Jun 2013 15:59:17 -0400 From: "Srivatsa S. Bhat" Subject: [PATCH v3 18/45] time/clocksource: Use get/put_online_cpus_atomic() to prevent CPU offline To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, walken@google.com, vincent.guittot@linaro.org, laijs@cn.fujitsu.com, David.Laight@aculab.com Cc: rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, sbw@mit.edu, fweisbec@gmail.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, John Stultz , Thomas Gleixner , "Srivatsa S. Bhat" Date: Fri, 28 Jun 2013 01:25:55 +0530 Message-ID: <20130627195554.29830.38682.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130627195136.29830.10445.stgit@srivatsabhat.in.ibm.com> References: <20130627195136.29830.10445.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13062719-4790-0000-0000-00000902DF6E Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Once stop_machine() is gone from the CPU offline path, we won't be able to depend on disabling preemption to prevent CPUs from going offline from under us. Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. Cc: John Stultz Cc: Thomas Gleixner Signed-off-by: Srivatsa S. Bhat --- kernel/time/clocksource.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index e713ef7..c4bbc25 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -30,6 +30,7 @@ #include /* for spin_unlock_irq() using preempt_count() m68k */ #include #include +#include #include "tick-internal.h" @@ -252,6 +253,7 @@ static void clocksource_watchdog(unsigned long data) int64_t wd_nsec, cs_nsec; int next_cpu, reset_pending; + get_online_cpus_atomic(); spin_lock(&watchdog_lock); if (!watchdog_running) goto out; @@ -329,6 +331,7 @@ static void clocksource_watchdog(unsigned long data) add_timer_on(&watchdog_timer, next_cpu); out: spin_unlock(&watchdog_lock); + put_online_cpus_atomic(); } static inline void clocksource_start_watchdog(void) @@ -367,6 +370,7 @@ static void clocksource_enqueue_watchdog(struct clocksource *cs) { unsigned long flags; + get_online_cpus_atomic(); spin_lock_irqsave(&watchdog_lock, flags); if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { /* cs is a clocksource to be watched. */ @@ -386,6 +390,7 @@ static void clocksource_enqueue_watchdog(struct clocksource *cs) /* Check if the watchdog timer needs to be started. */ clocksource_start_watchdog(); spin_unlock_irqrestore(&watchdog_lock, flags); + put_online_cpus_atomic(); } static void clocksource_dequeue_watchdog(struct clocksource *cs)