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authorFrederic Weisbecker <fweisbec@gmail.com>2012-08-22 17:27:34 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-10-13 05:38:54 +0900
commit2ddcad1f012eb832b5ad61f27888bf36eb495e83 (patch)
treec3fa632bd3094ea0031a41d7cf8ce75d64c1e781
parentd2d41b722e5faf418c1a660eaa602d06e50402eb (diff)
downloadlwn-2ddcad1f012eb832b5ad61f27888bf36eb495e83.tar.gz
lwn-2ddcad1f012eb832b5ad61f27888bf36eb495e83.zip
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 <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Chris Zankel <chris@zankel.net> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/xtensa/kernel/process.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 6a2d6edf8f72..7a41d9ec8ac7 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -31,6 +31,7 @@
#include <linux/mqueue.h>
#include <linux/fs.h>
#include <linux/slab.h>
+#include <linux/rcupdate.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
@@ -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();
}
}