From mboxrd@z Thu Jan 1 00:00:00 1970 From: tip-bot for Frederic Weisbecker Subject: [tip:core/rcu] alpha: Add missing RCU idle APIs on idle loop Date: Wed, 26 Sep 2012 22:16:00 -0700 Message-ID: Reply-To: linux-kernel@vger.kernel.org, mingo@kernel.org, hpa@zytor.com, paulmck@linux.vnet.ibm.com, fweisbec@gmail.com, linux-alpha@vger.kernel.org, mattst88@gmail.com, ink@jurassic.park.msu.ru, tglx@linutronix.de, josh@joshtriplett.org, rth@twiddle.net, mcree@orcon.net.nz Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline Sender: linux-alpha-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: linux-tip-commits@vger.kernel.org Cc: hpa@zytor.com, mingo@kernel.org, paulmck@linux.vnet.ibm.com, fweisbec@gmail.com, linux-alpha@vger.kernel.org, mattst88@gmail.com, ink@jurassic.park.msu.ru, tglx@linutronix.de, josh@joshtriplett.org, rth@twiddle.net, mcree@orcon.net.nz Commit-ID: 4c94cada48f7c660eca582be6032427a5e367117 Gitweb: http://git.kernel.org/tip/4c94cada48f7c660eca582be6032427a5e367117 Author: Frederic Weisbecker AuthorDate: Wed, 22 Aug 2012 17:27:34 +0200 Committer: Paul E. McKenney CommitDate: Sun, 23 Sep 2012 07:44:43 -0700 alpha: Add missing RCU idle APIs on idle loop In the old times, the whole idle task was considered as an RCU quiescent state. But as RCU became more and more successful overtime, some RCU read side critical section have been added even in the code of some architectures idle tasks, for tracing for example. So nowadays, rcu_idle_enter() and rcu_idle_exit() must be called by the architecture to tell RCU about the part in the idle loop that doesn't make use of rcu read side critical sections, typically the part that puts the CPU in low power mode. This is necessary for RCU to find the quiescent states in idle in order to complete grace periods. Add this missing pair of calls in the Alpha's idle loop. Reported-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker Tested-by: Michael Cree Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Matt Turner Cc: alpha Cc: Paul E. McKenney Cc: # 3.3+ Reviewed-by: Josh Triplett --- arch/alpha/kernel/process.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c index db56f31..83638aa 100644 --- a/arch/alpha/kernel/process.c +++ b/arch/alpha/kernel/process.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include @@ -54,9 +55,11 @@ cpu_idle(void) /* FIXME -- EV6 and LCA45 know how to power down the CPU. */ + rcu_idle_enter(); while (!need_resched()) cpu_relax(); + rcu_idle_exit(); schedule_preempt_disabled(); } }