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From: david.laight.linux@gmail.com
To: Waiman Long <longman@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Boqun Feng <boqun@kernel.org>,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Yafang Shao <loaor.shao@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>
Cc: David Laight <david.laight@aculab.com>,
	David Laight <david.laight.linux@gmail.com>
Subject: [PATCH v3 next 1/5] Only clear node->locked in the slow osq_lock() path
Date: Fri,  6 Mar 2026 22:51:46 +0000	[thread overview]
Message-ID: <20260306225150.93178-2-david.laight.linux@gmail.com> (raw)
In-Reply-To: <20260306225150.93178-1-david.laight.linux@gmail.com>

From: David Laight <david.laight@aculab.com>

node->locked is used to indicate that the owner of the lock has handed it
off to the waiting CPU.
As such it's value is only relevant in the slow path so it need not be
initialised in the fast path.

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
 kernel/locking/osq_lock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c
index b4233dc2c2b0..96c6094157b5 100644
--- a/kernel/locking/osq_lock.c
+++ b/kernel/locking/osq_lock.c
@@ -97,7 +97,6 @@ bool osq_lock(struct optimistic_spin_queue *lock)
 	int curr = encode_cpu(smp_processor_id());
 	int old;
 
-	node->locked = 0;
 	node->next = NULL;
 	node->cpu = curr;
 
@@ -113,6 +112,7 @@ bool osq_lock(struct optimistic_spin_queue *lock)
 
 	prev = decode_cpu(old);
 	node->prev = prev;
+	node->locked = 0;
 
 	/*
 	 * osq_lock()			unqueue
-- 
2.39.5


  reply	other threads:[~2026-03-06 22:51 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-06 22:51 [PATCH v3 next 0/5] locking/osq_lock: Optimisations to osq_lock code david.laight.linux
2026-03-06 22:51 ` david.laight.linux [this message]
2026-03-06 23:01   ` [PATCH v3 next 1/5] Only clear node->locked in the slow osq_lock() path David Laight
2026-03-06 22:51 ` [PATCH v3 next 2/5] Optimise vcpu_is_preempted() check david.laight.linux
2026-03-06 23:01   ` David Laight
2026-03-06 23:03   ` David Laight
2026-03-06 22:51 ` [PATCH v3 next 3/5] Use node->prev_cpu instead of saving node->prev david.laight.linux
2026-03-06 23:01   ` David Laight
2026-03-06 23:03   ` David Laight
2026-03-06 22:51 ` [PATCH v3 next 4/5] Optimise decode_cpu() and per_cpu_ptr() david.laight.linux
2026-03-06 23:01   ` David Laight
2026-03-06 23:03   ` David Laight
2026-03-06 22:51 ` [PATCH v3 next 5/5] Avoid writing to node->next in the osq_lock() fast path david.laight.linux
2026-03-06 23:04   ` David Laight
2026-03-07  0:06   ` Linus Torvalds
2026-03-07 11:32     ` David Laight
2026-03-11 19:27   ` Waiman Long
2026-03-11 19:40     ` Waiman Long
2026-03-11 21:50     ` David Laight
2026-03-06 22:59 ` [PATCH v3 next 0/5] locking/osq_lock: Optimisations to osq_lock code David Laight

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