[PATCH tip/core/rcu 06/22] rcu: Replace smp_wmb() with smp_store_release() for stall check

[Paul E. McKenney]

This commit gets rid of the smp_wmb() in record_gp_stall_check_time()
in favor of an smp_store_release().

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
 kernel/rcu/tree.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d526c2125564..78dd96e8ce3e 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1246,9 +1246,9 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
 	unsigned long j1;
 
 	rsp->gp_start = j;
-	smp_wmb(); /* Record start time before stall time. */
 	j1 = rcu_jiffies_till_stall_check();
-	WRITE_ONCE(rsp->jiffies_stall, j + j1);
+	/* Record ->gp_start before ->jiffies_stall. */
+	smp_store_release(&rsp->jiffies_stall, j + j1); /* ^^^ */
 	rsp->jiffies_resched = j + j1 / 2;
 	rsp->n_force_qs_gpstart = READ_ONCE(rsp->n_force_qs);
 }
-- 
2.17.1