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From: David Laight <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>
Subject: Re: [PATCH v3 next 1/5] Only clear node->locked in the slow osq_lock() path
Date: Fri, 6 Mar 2026 23:01:14 +0000	[thread overview]
Message-ID: <20260306230114.74a7fc23@pumpkin> (raw)
In-Reply-To: <20260306225150.93178-2-david.laight.linux@gmail.com>

On Fri,  6 Mar 2026 22:51:46 +0000
david.laight.linux@gmail.com wrote:

Apologies to Yafang for mistyping his address...

> From: David Laight <david.laight.linux@gmail.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


  reply	other threads:[~2026-03-06 23:01 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 ` [PATCH v3 next 1/5] Only clear node->locked in the slow osq_lock() path david.laight.linux
2026-03-06 23:01   ` David Laight [this message]
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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