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From: Joel Fernandes <joelagnelf@nvidia.com>
To: linux-kernel@vger.kernel.org,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Boqun Feng <boqun@kernel.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Zqiang <qiang.zhang@linux.dev>
Cc: rcu@vger.kernel.org
Subject: [PATCH v1 1/6] rcu: Remove unused expedited_need_qs field from rcu_state
Date: Sat, 18 Jul 2026 13:15:32 -0400	[thread overview]
Message-ID: <20260718171539.3781595-2-joelagnelf@nvidia.com> (raw)
In-Reply-To: <20260718171539.3781595-1-joelagnelf@nvidia.com>

The ->expedited_need_qs counter was part of the old expedited
grace-period machinery that spun waiting for each CPU to check in.
The current implementation instead tracks holdout CPUs via the
rcu_node structures' ->expmask fields and waits on the ->exp_wq[]
wait queues, so nothing reads or writes ->expedited_need_qs any
longer.

Remove the field to avoid wasting space in rcu_state and to keep
readers of the expedited code from searching for nonexistent users.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 kernel/rcu/tree.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 7dfc57e9adb1..beb86e39909a 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -386,7 +386,6 @@ struct rcu_state {
 	struct mutex exp_mutex;			/* Serialize expedited GP. */
 	struct mutex exp_wake_mutex;		/* Serialize wakeup. */
 	unsigned long expedited_sequence;	/* Take a ticket. */
-	atomic_t expedited_need_qs;		/* # CPUs left to check in. */
 	struct swait_queue_head expedited_wq;	/* Wait for check-ins. */
 	int ncpus_snap;				/* # CPUs seen last time. */
 	u8 cbovld;				/* Callback overload now? */
-- 
2.34.1


  reply	other threads:[~2026-07-18 17:15 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-18 17:15 [PATCH v1 0/6] RCU and torture fixes and cleanups Joel Fernandes
2026-07-18 17:15 ` Joel Fernandes [this message]
2026-07-18 17:15 ` [PATCH v1 2/6] rcu: Remove unused rdp parameter from trace_rcu_this_gp() Joel Fernandes
2026-07-18 17:15 ` [PATCH v1 3/6] rcu: Remove unused func parameter from callback-enqueue functions Joel Fernandes
2026-07-18 17:15 ` [PATCH v1 4/6] torture: Don't leak shuffle_tmp_mask when shuffler kthread fails to start Joel Fernandes
2026-07-18 17:15 ` [PATCH v1 5/6] scftorture: Count single_rpc offline failures in statistics output Joel Fernandes
2026-07-18 17:17   ` Joel Fernandes
2026-07-18 17:15 ` [PATCH v1 6/6] scftorture: Make invoker threads actually wait for all threads to start Joel Fernandes
2026-07-18 17:17   ` Joel Fernandes
2026-07-20 15:52 ` [PATCH v1 0/6] RCU and torture fixes and cleanups Paul E. McKenney

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