From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Wed, 23 Mar 2016 17:43:23 +0000 (-0700)
Subject: rcu: Don't kick unless grace period or request
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=aa3e0bf1aa76579c6c51a2c1116a630aa716379d;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git

rcu: Don't kick unless grace period or request

The current code can result in spurious kicks when there are no grace
periods in progress and no grace-period-related requests.  This is
sort of OK for a diagnostic aid, but the resulting ftrace-dump messages
in dmesg are annoying.  This commit therefore avoids spurious kicks
in the common case.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
---

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 865af187498e..96c52e43f7ca 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1304,7 +1304,8 @@ static void rcu_stall_kick_kthreads(struct rcu_state *rsp)
 	if (!rcu_kick_kthreads)
 		return;
 	j = READ_ONCE(rsp->jiffies_kick_kthreads);
-	if (time_after(jiffies, j) && rsp->gp_kthread) {
+	if (time_after(jiffies, j) && rsp->gp_kthread &&
+	    (rcu_gp_in_progress(rsp) || READ_ONCE(rsp->gp_flags))) {
 		WARN_ONCE(1, "Kicking %s grace-period kthread\n", rsp->name);
 		rcu_ftrace_dump(DUMP_ALL);
 		wake_up_process(rsp->gp_kthread);