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Date:   Tue, 8 Nov 2022 10:23:31 -0700
From:   Keith Busch <kbusch@kernel.org>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Gerd Bayer <gbayer@linux.ibm.com>, Jens Axboe <axboe@fb.com>,
        Sagi Grimberg <sagi@grimberg.me>,
        Niklas Schnelle <schnelle@linux.ibm.com>,
        linux-kernel@vger.kernel.org, linux-next@vger.kernel.org,
        linux-nvme@lists.infradead.org
Subject: Re: nvme-pci: NULL pointer dereference in nvme_dev_disable() on
 linux-next
Message-ID: <Y2qQk/LuiNNdmdRD@kbusch-mbp>
References: <fad4d2d5e24eabe1a4fcab75c5d080a6229dc88b.camel@linux.ibm.com>
 <20221108074846.GA22674@lst.de>
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On Tue, Nov 08, 2022 at 08:48:47AM +0100, Christoph Hellwig wrote:
> Below is the minimal fix.  I'll see if I sort out the mess that is
> probe/reset failure vs ->remove a bit better, though.

This looks good to go. I vote apply for 6.1, and we should consider
merging your larger refactor for 6.2 after more test/review.

Reviewed-by: Keith Busch <kbusch@kernel.org>
 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index f94b05c585cbc..577bacdcfee08 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -5160,6 +5160,8 @@ EXPORT_SYMBOL_GPL(nvme_start_freeze);
>  
>  void nvme_stop_queues(struct nvme_ctrl *ctrl)
>  {
> +	if (!ctrl->tagset)
> +		return;
>  	if (!test_and_set_bit(NVME_CTRL_STOPPED, &ctrl->flags))
>  		blk_mq_quiesce_tagset(ctrl->tagset);
>  	else
> @@ -5169,6 +5171,8 @@ EXPORT_SYMBOL_GPL(nvme_stop_queues);
>  
>  void nvme_start_queues(struct nvme_ctrl *ctrl)
>  {
> +	if (!ctrl->tagset)
> +		return;
>  	if (test_and_clear_bit(NVME_CTRL_STOPPED, &ctrl->flags))
>  		blk_mq_unquiesce_tagset(ctrl->tagset);
>  }
>