[PATCH tip/core/rcu 15/15] rcu: Add ACCESS_ONCE() for RCU_INIT_POINTER()

[Paul E. McKenney]

From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>

It is permissible to use RCU_INIT_POINTER() instead of rcu_assign_pointer()
in a couple of cases where readers might be concurrently accessing the
pointer being assigned to: (1) When assigning NULL and (2) When assigning
a pointer that is already visible to readers.  In these two cases, we
should really be using ACCESS_ONCE() to prevent compiler mischief.  This
commit therefore adds the ACCESS_ONCE().

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
 include/linux/rcupdate.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 321ed0d4e675..7ba3f2470396 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -989,7 +989,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
  */
 #define RCU_INIT_POINTER(p, v) \
 	do { \
-		p = RCU_INITIALIZER(v); \
+		ACCESS_ONCE(p) = (v); \
 	} while (0)
 
 /**
-- 
1.8.1.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/