[PATCH v2] nvme/pci: Log PCI_STATUS when the controller dies

[J Freyensee]

On Thu, 2016-12-01 at 16:42 -0800, Andy Lutomirski wrote:
> When debugging nvme controller crashes, it's nice to know whether
> the controller died cleanly so that the failure is just reflected in
> CSTS, it died and put an error in PCI_STATUS, or whether it died so
> badly that it stopped responding to PCI configuration space reads.
> 
> Signed-off-by: Andy Lutomirski <luto at kernel.org>
> ---
>  drivers/nvme/host/pci.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 0248d0e21fee..f8dd83be01d9 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -1292,10 +1292,22 @@ static void nvme_watchdog_timer(unsigned long
> data)
>  
>  	/* Skip controllers under certain specific conditions. */
>  	if (nvme_should_reset(dev, csts)) {
> -		if (!nvme_reset(dev))
> -			dev_warn(dev->dev,
> -				"Failed status: 0x%x, reset
> controller.\n",
> -				csts);
> +		if (!nvme_reset(dev)) {
> +			/* Read a config register to help see what
> died. */
> +			u16 pci_status;
> +			int result;
> +
> +			result =
> pci_read_config_word(to_pci_dev(dev->dev),
> +						      PCI_STATUS,
> &pci_status);
> +			if (result == PCIBIOS_SUCCESSFUL)
> +				dev_warn(dev->dev,
> +					 "controller is down; will
> reset: CSTS=0x%x, PCI_STATUS=0x%hx\n",
> +					 csts, pci_status);
> +			else
> +				dev_warn(dev->dev,
> +					 "controller is down; will
> reset: CSTS=0x%x, PCI_STATUS read failed (%d)\n",
> +					 csts, result);
> +		}
>  		return;

Looks a lot more like what Keith suggested.

Reviewed-by: Jay Freyensee <james_p_freyensee at linux.intel.com>