From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Tue, 17 Nov 2015 18:56:55 +0000 (-0800)
Subject: rcu: Make expedited grace periods resolve stall-warning ties
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=73f36f9de8bed78bcda2704a348594c20518b455;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

rcu: Make expedited grace periods resolve stall-warning ties

Currently, if a grace period ends just as the stall-warning timeout
fires, an empty stall warning will be printed.  This is not helpful,
so this commit avoids these useless warnings by rechecking completion
after awakening in synchronize_sched_expedited_wait().

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

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 33d7e2551165..bc6b79716a86 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3757,7 +3757,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
 				rsp->expedited_wq,
 				sync_rcu_preempt_exp_done(rnp_root),
 				jiffies_stall);
-		if (ret > 0)
+		if (ret > 0 || sync_rcu_preempt_exp_done(rnp_root))
 			return;
 		if (ret < 0) {
 			/* Hit a signal, disable CPU stall warnings. */