[PATCH 12/16] rcu/nocb: Cancel nocb_timer upon nocb_gp wakeup

From: Frederic Weisbecker
Date: Thu Jan 28 2021 - 12:19:53 EST


As we wake up in nocb_gp_wait(), there is no need to keep the nocb_timer
around as we are going to go through the whole rdp list again. Any update
performed before the timer was armed will now be visible after the
nocb_gp_lock acquire.

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 | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index dae892ac570a..39fb792704ed 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2212,6 +2212,10 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
raw_spin_lock_irqsave(&my_rdp->nocb_gp_lock, flags);
if (bypass)
del_timer(&my_rdp->nocb_bypass_timer);
+ if (my_rdp->nocb_defer_wakeup > RCU_NOCB_WAKE_NOT) {
+ WRITE_ONCE(my_rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
+ del_timer(&my_rdp->nocb_timer);
+ }
WRITE_ONCE(my_rdp->nocb_gp_sleep, true);
raw_spin_unlock_irqrestore(&my_rdp->nocb_gp_lock, flags);
}
--
2.25.1