From: Will Deacon <will@kernel.org>
To: Zenghui Yu <yuzenghui@huawei.com>
Cc: peterz@infradead.org, mingo@redhat.com, longman@redhat.com,
boqun.feng@gmail.com, wanghaibin.wang@huawei.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] locking/qspinlock: Fix typo of lock word transition in the uncontended case
Date: Mon, 9 Aug 2021 14:40:48 +0100 [thread overview]
Message-ID: <20210809134047.GB1207@willie-the-truck> (raw)
In-Reply-To: <20210715030847.2038-1-yuzenghui@huawei.com>
On Thu, Jul 15, 2021 at 11:08:47AM +0800, Zenghui Yu wrote:
> If the queue head is the only one in the queue and nobody is concurrently
> setting PENDING bit, the uncontended transition should be n,0,0 -> 0,0,1.
>
> Fix the typo.
>
> Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
> ---
> kernel/locking/qspinlock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
> index cbff6ba53d56..591835415698 100644
> --- a/kernel/locking/qspinlock.c
> +++ b/kernel/locking/qspinlock.c
> @@ -355,7 +355,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
> * If we observe contention, there is a concurrent locker.
> *
> * Undo and queue; our setting of PENDING might have made the
> - * n,0,0 -> 0,0,0 transition fail and it will now be waiting
> + * n,0,0 -> 0,0,1 transition fail and it will now be waiting
> * on @next to become !NULL.
> */
I think this is an important typo fix as you're right that we don't
transition directly from having a waitqueue installed in the tail straight
to an unlocked state.
Acked-by: Will Deacon <will@kernel.org>
Then again, I acked the patch introducing this comment so what do I know?
Will
next prev parent reply other threads:[~2021-08-09 13:40 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-15 3:08 [PATCH] locking/qspinlock: Fix typo of lock word transition in the uncontended case Zenghui Yu
2021-08-09 13:40 ` Will Deacon [this message]
2021-08-09 16:22 ` Waiman Long
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