From a7e4074dccd282f494d542150ef6235b3270b0a2 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Tue, 19 Dec 2023 00:19:16 +0100 Subject: rcu/exp: Remove full barrier upon main thread wakeup When an expedited grace period is ending, care must be taken so that all the quiescent states propagated up to the root are correctly ordered against the wake up of the main expedited grace period workqueue. This ordering is already carried through the root rnp locking augmented by an smp_mb__after_unlock_lock() barrier. Therefore the explicit smp_mb() placed before the wake up is not needed and can be removed. Signed-off-by: Frederic Weisbecker Reviewed-by: Paul E. McKenney Signed-off-by: Boqun Feng --- kernel/rcu/tree_exp.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 2ac440bc7e10..014ddf672165 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -198,10 +198,9 @@ static void __rcu_report_exp_rnp(struct rcu_node *rnp, } if (rnp->parent == NULL) { raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - if (wake) { - smp_mb(); /* EGP done before wake_up(). */ + if (wake) swake_up_one_online(&rcu_state.expedited_wq); - } + break; } mask = rnp->grpmask; -- cgit v1.2.3