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From: Mani Tofigh <mt4022@columbia.edu>
To: Nilay Shroff <nilay@linux.ibm.com>, Jens Axboe <axboe@kernel.dk>
Cc: Mohamed Khalfella <mkhalfella@purestorage.com>,
	Keith Busch <kbusch@kernel.org>, Ming Lei <tom.leiming@gmail.com>,
	Bart Van Assche <bvanassche@acm.org>,
	Christoph Hellwig <hch@lst.de>,
	Josef Bacik <josef@toxicpanda.com>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	tz2294@columbia.edu, stable@vger.kernel.org
Subject: Re: [PATCH] blk-mq: take quiesce_lock when removing a queue from the tag set
Date: Fri, 6 Nov 2026 11:17:53 -0500	[thread overview]
Message-ID: <c0a08333-c236-4e41-867f-d94bc34ede6b@columbia.edu> (raw)
In-Reply-To: <b7d03393-79a1-4457-8ddf-e0d141e4b3e9@linux.ibm.com>



On 11/4/26 8:19 AM, Nilay Shroff wrote:
> Now that set->quiesce_lock serializes both traversal of set->tag_list
> in blk_mq_[un]quiesce_tagset() as well as modifications in
> blk_mq_[add|del]_queue_tag_set(), do we still need RCU protection for
> this list?


I don't think so.  The quiesce walks are the only users that don't
hold tag_list_lock and I didn't find any other reader of the list in
block or drivers.


I'd like to keep this fix minimal for stable though.  I'll drop the RCU
and add the __guarded_by() annotations as a separate cleanup.


Thanks!
Mani

      reply	other threads:[~2026-11-06 16:17 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-03 19:04 Mani Tofigh via B4 Relay
2026-11-03 19:51 ` Mohamed Khalfella
2026-11-04  7:19 ` Christoph Hellwig
2026-11-04 13:26   ` Nilay Shroff
2026-11-04 13:19 ` Nilay Shroff
2026-11-06 16:17   ` Mani Tofigh [this message]

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