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Date: Tue, 1 Nov 2016 06:43:52 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: linux-nvme@lists.infradead.org, Jens Axboe <axboe@kernel.dk>,
        Jay Freyensee <james_p_freyensee@linux.intel.com>,
        Solganik Alexander <sashas@lightbitslabs.com>,
        Christoph Hellwig <hch@lst.de>,
        "# v4 . 8+" <stable@vger.kernel.org>
Subject: Re: [PATCH] nvmet: Fix possible infinite loop triggered on hot
 namespace removal
Message-ID: <20161101134352.GA5096@infradead.org>
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>  void nvmet_ns_disable(struct nvmet_ns *ns)
> @@ -324,13 +324,10 @@ void nvmet_ns_disable(struct nvmet_ns *ns)
>  	struct nvmet_subsys *subsys = ns->subsys;
>  	struct nvmet_ctrl *ctrl;
>  
> -	mutex_lock(&subsys->lock);
> -	if (list_empty(&ns->dev_link)) {
> -		mutex_unlock(&subsys->lock);
> +	if (!test_and_clear_bit(NVMET_NS_ENABLED, &ns->flags))
>  		return;
> -	}
> -	list_del_init(&ns->dev_link);
> -	mutex_unlock(&subsys->lock);
> +
> +	list_del_rcu(&ns->dev_link);

We'll still need the lock here, don't we?