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Date: Wed, 29 Oct 2025 09:58:10 +0100
From: Christoph Hellwig <hch@lst.de>
To: Martin Wilck <mwilck@suse.com>
Cc: Christoph Hellwig <hch@lst.de>, Bart Van Assche <bvanassche@acm.org>,
	Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
	Benjamin Marzinski <bmarzins@redhat.com>,
	Hannes Reinecke <hare@suse.com>
Subject: Re: [PATCH 0/3] Fix a deadlock related to modifying queue
 attributes
Message-ID: <20251029085810.GA32474@lst.de>
References: <20250702182430.3764163-1-bvanassche@acm.org> <20250703090906.GG4757@lst.de> <918963a5-a349-433a-80a8-6d06c609f20e@acm.org> <20250708095707.GA28737@lst.de> <b23c05be-2bde-424a-a275-811ccc01567c@acm.org> <20250710080341.GA8622@lst.de> <563ef9b02d49fa05418c7a1b0b384d898819e0e9.camel@suse.com>
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On Mon, Oct 27, 2025 at 03:43:50PM +0100, Martin Wilck wrote:
> As Bart's patch only addresses the regression introduced by
> b07a889e8335 ("block: move q->sysfs_lock and queue-freeze under
> show/store method"), can we perhaps leave non-sysfs users of queue
> freezing aside in this context?
> 
> As far as sysfs users are concerned, what problem do you see with
> Bart's approach to introduce a timeout for freezing the queues, and
> returning an error to user space if this timeout is exceeded?
> 
> Would you be willing to accept the set if we'd use the timeout approach
> for all affected sysfs attributes?

Maybe it's because the discussion, but I have no idea what you are
trying to advocate for.  But a timeout for a locking operation is
not an option to work around deadlocks.