Re: [PATCH v2] xen/pciback: support driver_override

[Boris Ostrovsky]

On 09/02/2016 08:30 AM, Juergen Gross wrote:
> Support the driver_override scheme introduced with commit 782a985d7af2
> ("PCI: Introduce new device binding path using pci_dev.driver_override")
>
> As pcistub_probe() is called for all devices (it has to check for a
> match based on the slot address rather than device type) it has to
> check for driver_override set to "pciback" itself.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> V2: removed now unused label
> ---
>  drivers/xen/xen-pciback/pci_stub.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
> index 258b7c3..85c28f7 100644
> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -25,6 +25,8 @@
>  #include "conf_space.h"
>  #include "conf_space_quirks.h"
>  
> +#define PCISTUB_DRIVER_NAME "pciback"
> +
>  static char *pci_devs_to_hide;
>  wait_queue_head_t xen_pcibk_aer_wait_queue;
>  /*Add sem for sync AER handling and xen_pcibk remove/reconfigue ops,
> @@ -529,16 +531,18 @@ static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  				"don't have a normal (0) or bridge (1) "
>  				"header type!\n");
>  			err = -ENODEV;
> -			goto out;
>  		}
>  
> +	} else if (!dev->driver_override ||
> +		   strcmp(dev->driver_override, PCISTUB_DRIVER_NAME))
> +		/* Didn't find the device */
> +		err = -ENODEV;
> +
> +	if (!err) {
>  		dev_info(&dev->dev, "seizing device\n");
>  		err = pcistub_seize(dev);
> -	} else
> -		/* Didn't find the device */
> -		err = -ENODEV;
> +	}

Should devices with pciback override be displayed in
/sys/bus/pci/drivers/pciback/slots? If they should then they need to be
either added to pcistub_device_ids or kept on some other list.

Also, do you think checking override might better be done first, before
testing for ID match?

-boris


>  
> -out:
>  	return err;
>  }
>  
> @@ -945,7 +949,7 @@ static const struct pci_error_handlers xen_pcibk_error_handler = {
>  static struct pci_driver xen_pcibk_pci_driver = {
>  	/* The name should be xen_pciback, but until the tools are updated
>  	 * we will keep it as pciback. */
> -	.name = "pciback",
> +	.name = PCISTUB_DRIVER_NAME,
>  	.id_table = pcistub_ids,
>  	.probe = pcistub_probe,
>  	.remove = pcistub_remove,