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Date: Tue, 28 May 2024 08:31:09 +0200
From: Christoph Hellwig <hch@lst.de>
To: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Tanjore Suresh <tansuresh@google.com>,
	Martin Belanger <Martin.Belanger@dell.com>,
	Oliver O'Halloran <oohall@gmail.com>,
	Daniel Wagner <dwagner@suse.de>, Keith Busch <kbusch@kernel.org>,
	Lukas Wunner <lukas@wunner.de>, David Jeffery <djeffery@redhat.com>,
	Jeremy Allison <jallison@ciq.com>, Jens Axboe <axboe@fb.com>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org
Subject: Re: [PATCH v6 3/4] driver core: shut down devices asynchronously
Message-ID: <20240528063109.GA29965@lst.de>
References: <20240516154920.221445-1-stuart.w.hayes@gmail.com> <20240516154920.221445-4-stuart.w.hayes@gmail.com>
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In-Reply-To: <20240516154920.221445-4-stuart.w.hayes@gmail.com>
User-Agent: Mutt/1.5.17 (2007-11-01)

On Thu, May 16, 2024 at 10:49:19AM -0500, Stuart Hayes wrote:
> Add /sys/kernel/async_shutdown to allow user control of this feature:
> 
>   safe: shut down all devices synchronously, unless driver prefers async
> 	shutdown (driver opt-in) (default)
>   on:	shut down all devices asynchronously, unless disabled by the driver
> 	(driver opt-out)
>   off:	shut down all devices synchronously

The on option seems very odd.  IMHO safe is the only really sensible
option, and maybe we have to support off as a bandaid due to userspace
behavior dependent on synchronous shutdown, but I'd rather try even
without that first.