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Date: Wed, 3 Jun 2026 10:54:02 +0100
From: Keith Busch <kbusch@kernel.org>
To: Gui-Dong Han <hanguidong02@gmail.com>
Cc: sven@kernel.org, linux-nvme@lists.infradead.org, axboe@kernel.dk,
	hch@lst.de, sagi@grimberg.me, j@jannau.net, neal@gompa.dev,
	asahi@lists.linux.dev, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, baijiaju1990@gmail.com
Subject: Re: [PATCH] nvme-apple: Use acquire/release for queue enabled state
Message-ID: <ah_5utfy2oJbUCw7@kbusch-mbp>
References: <20260603072205.3291888-1-hanguidong02@gmail.com>
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In-Reply-To: <20260603072205.3291888-1-hanguidong02@gmail.com>

On Wed, Jun 03, 2026 at 03:22:05PM +0800, Gui-Dong Han wrote:
> apple_nvme_init_queue() initializes queue state and then marks the queue
> enabled. The interrupt and request paths check enabled before using that
> queue state.
> 
> The existing wmb() after WRITE_ONCE(enabled, true) orders the enabled
> store before later queue use, but it does not publish the earlier
> initialization before enabled becomes visible.
> 
> Use a release store when enabling the queue and acquire loads when
> testing it. Keep the existing wmb() in place for the
> store-before-later-use ordering.

Doesn't smp_store_release() already get you those semantics?

Also, there are a few other places doing the READ/WRITE_ONCE() calls in
apple_nvme_disable. Do you want to update those too for consistency?