[PATCH 04/13] rcu/nocb: Move trace_rcu_nocb_wake() calls outside nocb_lock when possible

From: Frederic Weisbecker
Date: Mon Feb 22 2021 - 19:11:46 EST


Those tracing calls don't need to be under the nocb lock. Move them
outside.

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 | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 924fa3d1df0d..587df271d640 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1715,9 +1715,9 @@ static bool wake_nocb_gp(struct rcu_data *rdp, bool force,

lockdep_assert_held(&rdp->nocb_lock);
if (!READ_ONCE(rdp_gp->nocb_gp_kthread)) {
+ rcu_nocb_unlock_irqrestore(rdp, flags);
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
TPS("AlreadyAwake"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
return false;
}

@@ -1967,9 +1967,9 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
// If we are being polled or there is no kthread, just leave.
t = READ_ONCE(rdp->nocb_gp_kthread);
if (rcu_nocb_poll || !t) {
+ rcu_nocb_unlock_irqrestore(rdp, flags);
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
TPS("WakeNotPoll"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
return;
}
// Need to actually to a wakeup.
@@ -2004,8 +2004,8 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
TPS("WakeOvfIsDeferred"));
rcu_nocb_unlock_irqrestore(rdp, flags);
} else {
+ rcu_nocb_unlock_irqrestore(rdp, flags);
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WakeNot"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
}
return;
}
--
2.25.1