[PATCH v2 1/3] rcu: Use READ_ONCE() and WRITE_ONCE() for shared variable rcu_gp_ctr

[Junchang Wang <junchangwang@xxxxxxxxx>]

Signed-off-by: Junchang Wang <junchangwang@xxxxxxxxx>
Reviewed-by: Akira Yokosawa <akiyks@xxxxxxxxx>
---
 CodeSamples/defer/rcu.c | 2 +-
 CodeSamples/defer/rcu.h | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/CodeSamples/defer/rcu.c b/CodeSamples/defer/rcu.c
index 4b868cc..66792e5 100644
--- a/CodeSamples/defer/rcu.c
+++ b/CodeSamples/defer/rcu.c
@@ -35,7 +35,7 @@ void synchronize_rcu(void)
 
 	/* Advance to a new grace-period number, enforce ordering. */
 
-	rcu_gp_ctr += 2;
+	WRITE_ONCE(rcu_gp_ctr, rcu_gp_ctr + 2);
 	smp_mb();
 
 	/*
diff --git a/CodeSamples/defer/rcu.h b/CodeSamples/defer/rcu.h
index f493f8b..b49ab14 100644
--- a/CodeSamples/defer/rcu.h
+++ b/CodeSamples/defer/rcu.h
@@ -41,7 +41,7 @@ static inline void rcu_read_lock(void)
 	 * periodic per-thread processing.)
 	 */
 
-	__get_thread_var(rcu_reader_gp) = rcu_gp_ctr + 1;
+	__get_thread_var(rcu_reader_gp) = READ_ONCE(rcu_gp_ctr) + 1;
 	smp_mb();
 }
 
@@ -55,7 +55,7 @@ static inline void rcu_read_unlock(void)
 	 */
 
 	smp_mb();
-	__get_thread_var(rcu_reader_gp) = rcu_gp_ctr;
+	__get_thread_var(rcu_reader_gp) = READ_ONCE(rcu_gp_ctr);
 }
 
 extern void synchronize_rcu(void);
-- 
2.7.4