rcu: Add memory barriers

Add the memory barriers added by e59fb3120b.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index e486f7c3ffb8b239a31eddb37f9ed0251629bdeb..3731141d8ad7936b6ca537b5dae911a9989b4316 100644 (file)
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -907,6 +907,12 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
        unsigned long gp_duration;
 
        WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
+
+       /*
+        * Ensure that all grace-period and pre-grace-period activity
+        * is seen before the assignment to rsp->completed.
+        */
+       smp_mb(); /* See above block comment. */
        gp_duration = jiffies - rsp->gp_start;
        if (gp_duration > rsp->gp_max)
                rsp->gp_max = gp_duration;