Re: [PATCH V6 11/11] nvme: pci: support nested EH

[Christoph Hellwig <hch@lst.de>]

On Wed, May 16, 2018 at 08:20:31PM -0600, Keith Busch wrote:
> On Thu, May 17, 2018 at 07:10:59AM +0800, Ming Lei wrote:
> > All simulation in block/011 may happen in reality.
> 
> If this test actually simulates reality, then the following one line
> patch (plus explanation for why) would be a real "fix" as this is very
> successful in passing block/011. :)
> 
> ---
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 1faa32cd07da..dcc5746304c4 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -2118,6 +2118,12 @@ static int nvme_pci_enable(struct nvme_dev *dev)
>  
>  	if (pci_enable_device_mem(pdev))
>  		return result;
> +	/*
> +	 * blktests block/011 disables the device without the driver knowing.
> +	 * We'll just enable the device twice to get the enable_cnt > 1
> +	 * so that the test's disabling does absolutely nothing.
> +	 */
> +	pci_enable_device_mem(pdev);

Heh.  But yes, this test and the PCI "enable" interface in sysfs look
horribly wrong. pci_disable_device/pci_enable_device aren't something we
can just do underneath the driver.  Even if injecting the lowlevel
config space manipulations done by it might be useful and a good test
the Linux state ones are just killing the driver.

The enable attribute appears to have been added by Arjan for the
Xorg driver.  I think if we have a driver bound to the device we
should not allow it.