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Date:   Mon, 26 Jun 2023 10:01:36 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Bart Van Assche <bvanassche@acm.org>
Cc:     Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        linux-block@vger.kernel.org, Damien Le Moal <dlemoal@kernel.org>,
        Ming Lei <ming.lei@redhat.com>,
        Mike Snitzer <snitzer@kernel.org>
Subject: Re: [PATCH v4 5/7] block: Preserve the order of requeued requests
Message-ID: <20230626080136.GA27039@lst.de>
References: <20230621201237.796902-1-bvanassche@acm.org> <20230621201237.796902-6-bvanassche@acm.org> <20230623055053.GE9085@lst.de> <6e57f158-a98c-0355-25a4-2d12f3ec0b23@acm.org>
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On Fri, Jun 23, 2023 at 01:08:33PM -0700, Bart Van Assche wrote:
> Does it matter in this context whether list_empty_careful() or list_empty() 
> is used? If blk_mq_process_requeue_list() is called concurrently with code 
> that adds an element to one of these two lists it is guaranteed that the 
> queue will be run again. This is why I think that it is fine that the list 
> checks in blk_mq_process_requeue_list() race with concurrent list 
> additions.

As far as I can tell we're not holding the relevant lock, so I think we
need list_empty_careful.  Or am I missing something?