[PATCH tip/core/rcu 03/10] rcu: Flag lockless access to ->gp_flags with ACCESS_ONCE()

[Paul E. McKenney]

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

This commit applies ACCESS_ONCE() to an outside-of-lock access to
->gp_flags.  Although it is hard to imagine any sane compiler messing
this particular case up, the documentation benefits are substantial.
Plus the definition of "sane compiler" grows ever looser.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
 kernel/rcutree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 62b67b7..6d028fd 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1481,7 +1481,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
 		/* Handle grace-period start. */
 		for (;;) {
 			wait_event_interruptible(rsp->gp_wq,
-						 rsp->gp_flags &
+						 ACCESS_ONCE(rsp->gp_flags) &
 						 RCU_GP_FLAG_INIT);
 			if (rcu_gp_init(rsp))
 				break;
-- 
1.8.1.5

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