[tip: core/rcu] rcu/nocb: Move trace_rcu_nocb_wake() calls outside nocb_lock when possible

From: tip-bot2 for Frederic Weisbecker
Date: Sun Apr 11 2021 - 09:44:46 EST


The following commit has been merged into the core/rcu branch of tip:

Commit-ID: e02691b7ef51c5fac0eee5a6ebde45ce92958fae
Gitweb: https://git.kernel.org/tip/e02691b7ef51c5fac0eee5a6ebde45ce92958fae
Author: Frederic Weisbecker <frederic@xxxxxxxxxx>
AuthorDate: Tue, 23 Feb 2021 01:10:02 +01:00
Committer: Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 15 Mar 2021 13:54:55 -07:00

rcu/nocb: Move trace_rcu_nocb_wake() calls outside nocb_lock when possible

Those tracing calls don't need to be under ->nocb_lock. This commit
therefore moves them outside of that lock.

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>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
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 b08564b..9846c8a 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1703,9 +1703,9 @@ 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;
}

@@ -1955,9 +1955,9 @@ 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.
@@ -1992,8 +1992,8 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
TPS("WakeOvfIsDeferred"));
rcu_nocb_unlock_irqrestore(rdp, flags);
} else {
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WakeNot"));
rcu_nocb_unlock_irqrestore(rdp, flags);
+ trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WakeNot"));
}
return;
}