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>

1 files changed, 2 insertions, 1 deletions

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);