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Bhat" Subject: [PATCH v6 17/46] clockevents: Use get/put_online_cpus_atomic() in clockevents_notify() 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 Date: Mon, 18 Feb 2013 18:10:42 +0530 Message-ID: <20130218124042.26245.92242.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130218123714.26245.61816.stgit@srivatsabhat.in.ibm.com> References: <20130218123714.26245.61816.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13021812-4790-0000-0000-000006F5F231 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130218_074248_162148_4CE50157 X-CRM114-Status: GOOD ( 11.18 ) X-Spam-Score: -1.9 (-) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-1.9 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [122.248.162.1 listed in list.dnswl.org] 3.0 KHOP_BIG_TO_CC Sent to 10+ recipients instaed of Bcc or a list -0.7 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: linux-arch@vger.kernel.org, linux@arm.linux.org.uk, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, fweisbec@gmail.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, xiaoguangrong@linux.vnet.ibm.com, rjw@sisk.pl, sbw@mit.edu, wangyun@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, netdev@vger.kernel.org, vincent.guittot@linaro.org, walken@google.com, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org The cpu idle code invokes clockevents_notify() during idle state transitions and the cpu offline code invokes it during the CPU_DYING phase. There seems to be a race-condition between the two, where the clockevents_lock never gets released, ending in a lockup. This can be fixed by synchronizing clockevents_notify() with CPU offline, by wrapping its contents within get/put_online_cpus_atomic(). Signed-off-by: Srivatsa S. Bhat --- kernel/time/clockevents.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 30b6de0..ca340fd 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -17,6 +17,7 @@ #include #include #include +#include #include "tick-internal.h" @@ -431,6 +432,7 @@ void clockevents_notify(unsigned long reason, void *arg) unsigned long flags; int cpu; + get_online_cpus_atomic(); raw_spin_lock_irqsave(&clockevents_lock, flags); clockevents_do_notify(reason, arg); @@ -459,6 +461,7 @@ void clockevents_notify(unsigned long reason, void *arg) break; } raw_spin_unlock_irqrestore(&clockevents_lock, flags); + put_online_cpus_atomic(); } EXPORT_SYMBOL_GPL(clockevents_notify); #endif