From 3def22b0e862682b45394b8d12d628714d6082d0 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 22 Aug 2012 17:27:34 +0200 Subject: [PATCH] xtensa: Add missing RCU idle APIs on idle loop commit 11ad47a0edbd62bfc0547cfcdf227a911433f207 upstream. 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 xtensa's idle loop. Reported-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker Cc: Chris Zankel Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett Signed-off-by: Greg Kroah-Hartman --- arch/xtensa/kernel/process.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c index 2c8d6a3d250af..bc44311aa18cc 100644 --- a/arch/xtensa/kernel/process.c +++ b/arch/xtensa/kernel/process.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include @@ -110,8 +111,10 @@ void cpu_idle(void) /* endless idle loop with no priority at all */ while (1) { + rcu_idle_enter(); while (!need_resched()) platform_idle(); + rcu_idle_exit(); schedule_preempt_disabled(); } } -- 2.47.2