Re: [PATCH] nvme: remove pci device if no longer present

[Christoph Hellwig <hch@infradead.org>]

Please CC the linux-nvme list on any nvme issues.  Also this
code is getting a little too fancy for living in nvme, I think we
need to move it into the PCI core, ensure we properly take drv->lock
to synchronize it, and check for dev->drv instead of the private data
which is a guestimate.

On Fri, Jun 30, 2017 at 04:56:04PM -0700, Wei Zhang wrote:
> This patch removes the PCI device from the kernel's topology tree
> if the device is no longer present.
> 
> Commit ddf097ec1d44c9648c4738d7cf2819411b44253a (NVMe: Unbind driver on
> failure) left the PCI device in the kernel's topology upon device failure.
> However, this does not work well for the slot power off/on test cases.
> After a slot power off, we need to manually remove the PCI device
> before triggering the rescan, in order for the SSD to be rediscovered.
> 
> Fixes: ddf097ec1d44c9648c4738d7cf2819411b44253a
> Signed-off-by: Wei Zhang <wzhang@fb.com>
> Reviewed-by: Jens Axboe <axboe@fb.com>
> ---
>  drivers/nvme/host/pci.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 32a98e2..094b22f 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -2174,8 +2174,19 @@ static void nvme_remove_dead_ctrl_work(struct work_struct *work)
>  	struct pci_dev *pdev = to_pci_dev(dev->dev);
>  
>  	nvme_kill_queues(&dev->ctrl);
> -	if (pci_get_drvdata(pdev))
> -		device_release_driver(&pdev->dev);
> +
> +	/*
> +	 * Remove the PCI device from the topology tree if the device is no longer
> +	 * present.  Without removing, slot power off/on test cannot re-discover
> +	 * the SSD.
> +	 */
> +	if (pci_get_drvdata(pdev)) {
> +		if (!pci_device_is_present(pdev)) {
> +			pci_stop_and_remove_bus_device_locked(pdev);
> +		} else {
> +			device_release_driver(&pdev->dev);
> +		}
> +	}
>  	nvme_put_ctrl(&dev->ctrl);
>  }
>  
> -- 
> 2.9.3
> 
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