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From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com,
	rostedt@goodmis.org, Christoph Hellwig <hch@infradead.org>,
	"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH v2 1/5] torture: Remove support for SRCU-lite
Date: Tue,  1 Jul 2025 17:23:26 -0700	[thread overview]
Message-ID: <20250702002330.1074433-1-paulmck@kernel.org> (raw)
In-Reply-To: <2994ade2-bd06-4ba7-bcc9-be4d0d15ea0c@paulmck-laptop>

Because SRCU-lite is being replaced by SRCU-fast, this commit removes
support for SRCU-lite from refscale.c.

Both SRCU-lite and SRCU-fast provide faster readers by dropping the
smp_mb() call from their lock and unlock primitives, but incur a pair
of added RCU grace periods during the SRCU grace period.  There is a
trivial mapping from the SRCU-lite API to that of SRCU-fast, so there
should be no transition issues.

[ paulmck: Apply Christoph Hellwig feedback. ]

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/refscale.c | 32 +-------------------------------
 1 file changed, 1 insertion(+), 31 deletions(-)

diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index f11a7c2af778c..f4b2cea1cce5e 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -246,36 +246,6 @@ static const struct ref_scale_ops srcu_fast_ops = {
 	.name		= "srcu-fast"
 };
 
-static void srcu_lite_ref_scale_read_section(const int nloops)
-{
-	int i;
-	int idx;
-
-	for (i = nloops; i >= 0; i--) {
-		idx = srcu_read_lock_lite(srcu_ctlp);
-		srcu_read_unlock_lite(srcu_ctlp, idx);
-	}
-}
-
-static void srcu_lite_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
-{
-	int i;
-	int idx;
-
-	for (i = nloops; i >= 0; i--) {
-		idx = srcu_read_lock_lite(srcu_ctlp);
-		un_delay(udl, ndl);
-		srcu_read_unlock_lite(srcu_ctlp, idx);
-	}
-}
-
-static const struct ref_scale_ops srcu_lite_ops = {
-	.init		= rcu_sync_scale_init,
-	.readsection	= srcu_lite_ref_scale_read_section,
-	.delaysection	= srcu_lite_ref_scale_delay_section,
-	.name		= "srcu-lite"
-};
-
 #ifdef CONFIG_TASKS_RCU
 
 // Definitions for RCU Tasks ref scale testing: Empty read markers.
@@ -1193,7 +1163,7 @@ ref_scale_init(void)
 	long i;
 	int firsterr = 0;
 	static const struct ref_scale_ops *scale_ops[] = {
-		&rcu_ops, &srcu_ops, &srcu_fast_ops, &srcu_lite_ops, RCU_TRACE_OPS RCU_TASKS_OPS
+		&rcu_ops, &srcu_ops, &srcu_fast_ops, RCU_TRACE_OPS RCU_TASKS_OPS
 		&refcnt_ops, &rwlock_ops, &rwsem_ops, &lock_ops, &lock_irq_ops,
 		&acqrel_ops, &sched_clock_ops, &clock_ops, &jiffies_ops,
 		&typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,
-- 
2.40.1


  reply	other threads:[~2025-07-02  0:23 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-24 16:13 [PATCH 0/5] Remove SRCU-lite in favor of SRCU-fast Paul E. McKenney
2025-06-24 16:13 ` [PATCH 1/5] torture: Remove support for SRCU-lite Paul E. McKenney
2025-06-25 12:05   ` Christoph Hellwig
2025-06-26 10:54     ` Paul E. McKenney
2025-06-26 11:03       ` Christoph Hellwig
2025-06-26 14:37         ` Paul E. McKenney
2025-06-24 16:13 ` [PATCH 2/5] rcutorture: Remove SRCU-lite scenarios Paul E. McKenney
2025-06-24 16:13 ` [PATCH 3/5] rcutorture: Remove support for SRCU-lite Paul E. McKenney
2025-06-24 16:13 ` [PATCH 4/5] srcu: Remove SRCU-lite implementation Paul E. McKenney
2025-06-24 16:14 ` [PATCH 5/5] checkpatch: Remove SRCU-lite deprecation Paul E. McKenney
2025-07-02  0:23 ` [PATCH v2 0/5] Remove SRCU-lite in favor of SRCU-fast Paul E. McKenney
2025-07-02  0:23   ` Paul E. McKenney [this message]
2025-07-02  0:23   ` [PATCH v2 2/5] rcutorture: Remove SRCU-lite scenarios Paul E. McKenney
2025-07-02  0:23   ` [PATCH v2 3/5] rcutorture: Remove support for SRCU-lite Paul E. McKenney
2025-07-02  0:23   ` [PATCH v2 4/5] srcu: Remove SRCU-lite implementation Paul E. McKenney
2025-07-02  0:23   ` [PATCH v2 5/5] checkpatch: Remove SRCU-lite deprecation Paul E. McKenney

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