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From: Nilay Shroff <nilay@linux.ibm.com>
To: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org
Cc: syzbot+2bcecf3c38cb3e8fdc8d@syzkaller.appspotmail.com,
	Yu Kuai <yukuai3@huawei.com>
Subject: Re: [PATCH] nbd: fix lockdep deadlock warning
Date: Wed, 9 Jul 2025 13:29:07 +0530	[thread overview]
Message-ID: <95e6bce2-19dc-4085-908e-c81fa7a1d5d3@linux.ibm.com> (raw)
In-Reply-To: <20250709014109.2292837-1-ming.lei@redhat.com>



On 7/9/25 7:11 AM, Ming Lei wrote:
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 7bdc7eb808ea..136640e4c866 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -1473,7 +1473,15 @@ static int nbd_start_device(struct nbd_device *nbd)
>  		return -EINVAL;
>  	}
>  
> -	blk_mq_update_nr_hw_queues(&nbd->tag_set, config->num_connections);
> +retry:
> +	mutex_unlock(&nbd->config_lock);
> +	blk_mq_update_nr_hw_queues(&nbd->tag_set, num_connections);
> +	mutex_lock(&nbd->config_lock);
> +
> +	/* if another code path updated nr_hw_queues, retry until succeed */
> +	if (num_connections != config->num_connections)
> +		goto retry;
> +

Don't we need to update num_connections to config->num_connections
here before we attempt retry?

Thanks,
--Nilay


  parent reply	other threads:[~2025-07-09  7:59 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-09  1:41 [PATCH] nbd: fix lockdep deadlock warning Ming Lei
2025-07-09  6:46 ` 余快
2025-07-09  7:59 ` Nilay Shroff [this message]
2025-07-09  8:10   ` Ming Lei

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