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Date: Thu, 3 Jul 2025 11:06:46 +0200
From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>, Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Nilay Shroff <nilay@linux.ibm.com>, stable@vger.kernel.org
Subject: Re: [PATCH 1/3] block: Remove queue freezing from several sysfs
 store callbacks
Message-ID: <20250703090646.GE4757@lst.de>
References: <20250702182430.3764163-1-bvanassche@acm.org> <20250702182430.3764163-2-bvanassche@acm.org> <aGXmJg-ZIuFO9WnP@fedora>
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On Thu, Jul 03, 2025 at 10:08:38AM +0800, Ming Lei wrote:
> On Wed, Jul 02, 2025 at 11:24:28AM -0700, Bart Van Assche wrote:
> > Freezing the request queue from inside sysfs store callbacks may cause a
> > deadlock in combination with the dm-multipath driver and the
> > queue_if_no_path option. Additionally, freezing the request queue slows
> > down system boot on systems where sysfs attributes are set synchronously.
> > 
> > Fix this by removing the blk_mq_freeze_queue() / blk_mq_unfreeze_queue()
> > calls from the store callbacks that do not strictly need these callbacks.
> 
> Please add commit log why freeze isn't needed for these sysfs attributes
> callbacks.

Yes.  I'm rather doubtful about some of them, but waiting for a full
explanation.  The explanation might be easier to deliver by doing one
patch per attribute.