diff mbox series

[3/3] rcu/exp: Remove full barrier upon main thread wakeup

Message ID 20231218231916.11719-4-frederic@kernel.org
State New
Headers
Series timers & RCU: Fix TREE03 stalls |

Commit Message

Frederic Weisbecker Dec. 18, 2023, 11:19 p.m. UTC 
  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 <frederic@kernel.org>
---
 kernel/rcu/tree_exp.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
diff mbox series

Patch

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;