From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754658Ab3F0T7O (ORCPT ); Thu, 27 Jun 2013 15:59:14 -0400 Received: from e23smtp06.au.ibm.com ([202.81.31.148]:57800 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754535Ab3F0T7K (ORCPT ); Thu, 27 Jun 2013 15:59:10 -0400 From: "Srivatsa S. Bhat" Subject: [PATCH v3 17/45] tick-broadcast: 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, Thomas Gleixner , "Srivatsa S. Bhat" Date: Fri, 28 Jun 2013 01:25:37 +0530 Message-ID: <20130627195536.29830.580.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-Content-Scanned: Fidelis XPS MAILER x-cbid: 13062719-7014-0000-0000-0000033E2BC6 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: Thomas Gleixner Signed-off-by: Srivatsa S. Bhat --- kernel/time/tick-broadcast.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 9d96a54..1e4ac45 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -227,12 +227,14 @@ static void tick_do_broadcast(struct cpumask *mask) */ static void tick_do_periodic_broadcast(void) { + get_online_cpus_atomic(); raw_spin_lock(&tick_broadcast_lock); cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask); tick_do_broadcast(tmpmask); raw_spin_unlock(&tick_broadcast_lock); + put_online_cpus_atomic(); } /* @@ -335,11 +337,13 @@ out: */ void tick_broadcast_on_off(unsigned long reason, int *oncpu) { + get_online_cpus_atomic(); if (!cpumask_test_cpu(*oncpu, cpu_online_mask)) printk(KERN_ERR "tick-broadcast: ignoring broadcast for " "offline CPU #%d\n", *oncpu); else tick_do_broadcast_on_off(&reason); + put_online_cpus_atomic(); } /* @@ -505,6 +509,7 @@ static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) ktime_t now, next_event; int cpu, next_cpu = 0; + get_online_cpus_atomic(); raw_spin_lock(&tick_broadcast_lock); again: dev->next_event.tv64 = KTIME_MAX; @@ -562,6 +567,7 @@ again: goto again; } raw_spin_unlock(&tick_broadcast_lock); + put_online_cpus_atomic(); } /* @@ -756,6 +762,7 @@ void tick_broadcast_switch_to_oneshot(void) struct clock_event_device *bc; unsigned long flags; + get_online_cpus_atomic(); raw_spin_lock_irqsave(&tick_broadcast_lock, flags); tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT; @@ -764,6 +771,7 @@ void tick_broadcast_switch_to_oneshot(void) tick_broadcast_setup_oneshot(bc); raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); + put_online_cpus_atomic(); }