Merge branch 'idle.2013.09.25a' into HEAD

[karo-tx-linux.git] / kernel / rcutree.c

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index a06d172c75e028d40c8fe5d066f722ccfe1f11b1..240604aa3f700daa4a443b112eda717c8fd79bf6 100644 (file)
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -650,21 +650,34 @@ void rcu_nmi_exit(void)
 }
 
 /**
- * rcu_is_cpu_idle - see if RCU thinks that the current CPU is idle
+ * __rcu_is_watching - are RCU read-side critical sections safe?
+ *
+ * Return true if RCU is watching the running CPU, which means that
+ * this CPU can safely enter RCU read-side critical sections.  Unlike
+ * rcu_is_watching(), the caller of __rcu_is_watching() must have at
+ * least disabled preemption.
+ */
+bool __rcu_is_watching(void)
+{
+       return atomic_read(this_cpu_ptr(&rcu_dynticks.dynticks)) & 0x1;
+}
+
+/**
+ * rcu_is_watching - see if RCU thinks that the current CPU is idle
  *
  * If the current CPU is in its idle loop and is neither in an interrupt
  * or NMI handler, return true.
  */
-int rcu_is_cpu_idle(void)
+bool rcu_is_watching(void)
 {
        int ret;
 
        preempt_disable();
-       ret = (atomic_read(this_cpu_ptr(&rcu_dynticks.dynticks)) & 0x1) == 0;
+       ret = __rcu_is_watching();
        preempt_enable();
        return ret;
 }
-EXPORT_SYMBOL(rcu_is_cpu_idle);
+EXPORT_SYMBOL_GPL(rcu_is_watching);
 
 #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU)
 
@@ -2321,7 +2334,7 @@ static void __call_rcu_core(struct rcu_state *rsp, struct rcu_data *rdp,
         * If called from an extended quiescent state, invoke the RCU
         * core in order to force a re-evaluation of RCU's idleness.
         */
-       if (rcu_is_cpu_idle() && cpu_online(smp_processor_id()))
+       if (!rcu_is_watching() && cpu_online(smp_processor_id()))
                invoke_rcu_core();
 
        /* If interrupts were disabled or CPU offline, don't invoke RCU core. */