[PATCH 14/16] rcu/nocb: Only cancel nocb timer if not polling

[Frederic Weisbecker]

No need to disarm the nocb_timer if rcu_nocb is polling because it
shouldn't be armed either.

Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
---
 kernel/rcu/tree_plugin.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index eb8614577a2c..b1f76f341c66 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2178,16 +2178,16 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
 	my_rdp->nocb_gp_gp = needwait_gp;
 	my_rdp->nocb_gp_seq = needwait_gp ? wait_gp_seq : 0;
 	if (bypass) {
-		raw_spin_lock_irqsave(&my_rdp->nocb_gp_lock, flags);
-		// Avoid race with first bypass CB.
-		WRITE_ONCE(my_rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
-		del_timer(&my_rdp->nocb_timer);
 		if (!rcu_nocb_poll) {
+			raw_spin_lock_irqsave(&my_rdp->nocb_gp_lock, flags);
+			// Avoid race with first bypass CB.
+			WRITE_ONCE(my_rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
+			del_timer(&my_rdp->nocb_timer);
 			// At least one child with non-empty ->nocb_bypass, so set
 			// timer in order to avoid stranding its callbacks.
 			mod_timer(&my_rdp->nocb_bypass_timer, j + 2);
+			raw_spin_unlock_irqrestore(&my_rdp->nocb_gp_lock, flags);
 		}
-		raw_spin_unlock_irqrestore(&my_rdp->nocb_gp_lock, flags);
 	}
 	if (rcu_nocb_poll) {
 		/* Polling, so trace if first poll in the series. */
-- 
2.25.1