From: tip-bot for Frederic Weisbecker Date: Thu, 27 Sep 2012 05:24:22 +0000 (-0700) Subject: xtensa: Add missing RCU idle APIs on idle loop X-Git-Tag: next-20121002~90^2 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=ded389d476027ac271c176c01631d0da3d36c480;p=karo-tx-linux.git xtensa: Add missing RCU idle APIs on idle loop Commit-ID: 11ad47a0edbd62bfc0547cfcdf227a911433f207 Gitweb: http://git.kernel.org/tip/11ad47a0edbd62bfc0547cfcdf227a911433f207 Author: Frederic Weisbecker AuthorDate: Wed, 22 Aug 2012 17:27:34 +0200 Committer: Paul E. McKenney CommitDate: Sun, 23 Sep 2012 07:44:51 -0700 xtensa: 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 xtensa's idle loop. Reported-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker Cc: # 3.3+ Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett Signed-off-by: Chris Zankel --- diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c index 2c8d6a3d250a..bc44311aa18c 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(); } }