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From: Frederic Weisbecker <frederic@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Neeraj Upadhyay <neeraj.upadhyay@amd.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	Zqiang <qiang.zhang1211@gmail.com>, rcu <rcu@vger.kernel.org>
Subject: [PATCH 07/11] rcu/nocb: Remove halfway (de-)offloading handling from rcu_core()'s QS reporting
Date: Thu, 30 May 2024 15:45:48 +0200	[thread overview]
Message-ID: <20240530134552.5467-8-frederic@kernel.org> (raw)
In-Reply-To: <20240530134552.5467-1-frederic@kernel.org>

RCU core can't be running anymore while in the middle of (de-)offloading
since this sort of transition now only applies to offline CPUs.

The locked callback acceleration handling during the transition can
therefore be removed.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/rcu/tree.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e904c187c281..c502a38dc5f3 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2381,7 +2381,6 @@ rcu_report_qs_rdp(struct rcu_data *rdp)
 {
 	unsigned long flags;
 	unsigned long mask;
-	bool needacc = false;
 	struct rcu_node *rnp;
 
 	WARN_ON_ONCE(rdp->cpu != smp_processor_id());
@@ -2418,23 +2417,11 @@ rcu_report_qs_rdp(struct rcu_data *rdp)
 			 * to return true.  So complain, but don't awaken.
 			 */
 			WARN_ON_ONCE(rcu_accelerate_cbs(rnp, rdp));
-		} else if (!rcu_segcblist_completely_offloaded(&rdp->cblist)) {
-			/*
-			 * ...but NOCB kthreads may miss or delay callbacks acceleration
-			 * if in the middle of a (de-)offloading process.
-			 */
-			needacc = true;
 		}
 
 		rcu_disable_urgency_upon_qs(rdp);
 		rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags);
 		/* ^^^ Released rnp->lock */
-
-		if (needacc) {
-			rcu_nocb_lock_irqsave(rdp, flags);
-			rcu_accelerate_cbs_unlocked(rnp, rdp);
-			rcu_nocb_unlock_irqrestore(rdp, flags);
-		}
 	}
 }
 
-- 
2.45.1


  parent reply	other threads:[~2024-05-30 13:46 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-30 13:45 [PATCH 00/11] rcu/nocb: (De-)offloading on offline CPUs Frederic Weisbecker
2024-05-30 13:45 ` [PATCH 01/11] rcu/nocb: Introduce RCU_NOCB_LOCKDEP_WARN() Frederic Weisbecker
2024-05-30 13:45 ` [PATCH 02/11] rcu/nocb: Move nocb field at the end of state struct Frederic Weisbecker
2024-05-30 13:45 ` [PATCH 03/11] rcu/nocb: Assert no callbacks while nocb kthread allocation fails Frederic Weisbecker
2024-05-30 13:45 ` [PATCH 04/11] rcu/nocb: Introduce nocb mutex Frederic Weisbecker
2024-05-30 13:45 ` [PATCH 05/11] rcu/nocb: (De-)offload callbacks on offline CPUs only Frederic Weisbecker
2024-05-30 13:45 ` [PATCH 06/11] rcu/nocb: Remove halfway (de-)offloading handling from bypass Frederic Weisbecker
2024-05-30 13:45 ` Frederic Weisbecker [this message]
2024-05-30 13:45 ` [PATCH 08/11] rcu/nocb: Remove halfway (de-)offloading handling from rcu_core Frederic Weisbecker
2024-05-30 13:45 ` [PATCH 09/11] rcu/nocb: Remove SEGCBLIST_RCU_CORE Frederic Weisbecker
2024-05-30 13:45 ` [PATCH 10/11] rcu/nocb: Remove SEGCBLIST_KTHREAD_CB Frederic Weisbecker
2024-05-30 13:45 ` [PATCH 11/11] rcu/nocb: Simplify (de-)offloading state machine Frederic Weisbecker
2024-07-02 23:19   ` Boqun Feng
2024-07-03 12:17     ` Frederic Weisbecker
2024-07-03 22:56   ` [PATCH 11/11 v2] " Frederic Weisbecker
2024-07-03 23:52     ` Paul E. McKenney
2024-07-19 17:30 ` [PATCH 00/11] rcu/nocb: (De-)offloading on offline CPUs Paul E. McKenney

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