From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Mon, 16 May 2011 09:24:04 +0000 (-0700)
Subject: rcu: Add memory barriers
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=0bbcc529fcea9c7de5e2e7243f9913b8f7302a8c;p=linux-beck.git

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 e486f7c3ffb8..3731141d8ad7 100644
--- 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;