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authorGleb Natapov <gleb@redhat.com>2011-05-04 16:31:03 +0300
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-05-05 23:16:59 -0700
commit29ce831000081dd757d3116bf774aafffc4b6b20 (patch)
tree0b992d993b02d3479a150e9fc508d110dc45631d
parentbad6e1393cb505fe17747344a23666464daa3fa7 (diff)
rcu: provide rcu_virt_note_context_switch() function.
Provide rcu_virt_note_context_switch() for vitalization use to note quiescent state during guest entry. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-rw-r--r--include/linux/rcutiny.h8
-rw-r--r--include/linux/rcutree.h10
-rw-r--r--kernel/rcutree.c1
3 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 30ebd7c8d874..52b3e0281fd0 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -100,6 +100,14 @@ static inline void rcu_note_context_switch(int cpu)
}
/*
+ * Take advantage of the fact that there is only one CPU, which
+ * allows us to ignore virtualization-based context switches.
+ */
+static inline void rcu_virt_note_context_switch(int cpu)
+{
+}
+
+/*
* Return the number of grace periods.
*/
static inline long rcu_batches_completed(void)
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 284dad10c55b..e65d06634dd8 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -35,6 +35,16 @@ extern void rcu_note_context_switch(int cpu);
extern int rcu_needs_cpu(int cpu);
extern void rcu_cpu_stall_reset(void);
+/*
+ * Note a virtualization-based context switch. This is simply a
+ * wrapper around rcu_note_context_switch(), which allows TINY_RCU
+ * to save a few bytes.
+ */
+static inline void rcu_virt_note_context_switch(int cpu)
+{
+ rcu_note_context_switch(cpu);
+}
+
#ifdef CONFIG_TREE_PREEMPT_RCU
extern void exit_rcu(void);
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index b2fe2a273df2..54ff7eb92819 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -157,6 +157,7 @@ void rcu_note_context_switch(int cpu)
rcu_sched_qs(cpu);
rcu_preempt_note_context_switch(cpu);
}
+EXPORT_SYMBOL_GPL(rcu_note_context_switch);
#ifdef CONFIG_NO_HZ
DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {