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McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org, Chen Liqin , Lennox Wu , "3.2.x.." , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 24/26] score: Add missing RCU idle APIs on idle loop Date: Thu, 30 Aug 2012 14:05:41 -0700 Message-Id: <1346360743-3628-24-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.8 In-Reply-To: <1346360743-3628-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20120830210520.GA2824@linux.vnet.ibm.com> <1346360743-3628-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12083021-7408-0000-0000-0000080B5748 X-Gm-Message-State: ALoCoQmdqeFokbpvYzG9Itt1vxRkJeIetzF7cwohPsks0VXS9+vqb8C+GRru1s5Y4EJo+wJptoy0 From: Frederic Weisbecker 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 scores's idle loop. Reported-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker Cc: Chen Liqin Cc: Lennox Wu Cc: 3.2.x.. Cc: Paul E. McKenney Reviewed-by: Josh Triplett --- arch/score/kernel/process.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/arch/score/kernel/process.c b/arch/score/kernel/process.c index 2707023..637970c 100644 --- a/arch/score/kernel/process.c +++ b/arch/score/kernel/process.c @@ -27,6 +27,7 @@ #include #include #include +#include void (*pm_power_off)(void); EXPORT_SYMBOL(pm_power_off); @@ -50,9 +51,10 @@ void __noreturn cpu_idle(void) { /* endless idle loop with no priority at all */ while (1) { + rcu_idle_enter(); while (!need_resched()) barrier(); - + rcu_idle_exit(); schedule_preempt_disabled(); } }