Re: [PATCH v5 06/11] PCI: Expose reset type to users of pci_reset_bus()

[Alex Williamson <alex.williamson@xxxxxxxxxx>]

On Thu, 11 Oct 2018 04:49:58 +0000
Sinan Kaya <okaya@xxxxxxxxxx> wrote:

> Looking to have more control between the users of the API vs. what the API
> can do internally. The new reset_type tells the PCI core about the bounds
> of the request.
> 
> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxx>
> ---
>  drivers/pci/pci.c           | 17 ++++++++++++++---
>  drivers/vfio/pci/vfio_pci.c |  6 ++++--
>  include/linux/pci.h         |  2 +-
>  3 files changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index a1a7dd6988be..a3a1c2a5e0cf 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5236,13 +5236,24 @@ static int __pci_reset_bus(struct pci_bus *bus)
>  /**
>   * pci_reset_bus - Try to reset a PCI bus
>   * @pdev: top level PCI device to reset via slot/bus
> + * @reset_type: resets to try
>   *
>   * Same as above except return -EAGAIN if the bus cannot be locked
>   */
> -int pci_reset_bus(struct pci_dev *pdev)
> +int pci_reset_bus(struct pci_dev *pdev, u32 reset_type)
>  {
> -	return (!pci_probe_reset_slot(pdev->slot)) ?
> -	    __pci_reset_slot(pdev->slot) : __pci_reset_bus(pdev->bus);
> +	if ((reset_type & PCI_RESET_LINK) == PCI_RESET_LINK)
> +		return (!pci_probe_reset_slot(pdev->slot)) ?
> +				__pci_reset_slot(pdev->slot) :
> +				__pci_reset_bus(pdev->bus);
> +
> +	if ((reset_type & PCI_RESET_BUS) == PCI_RESET_BUS)
> +		return __pci_reset_bus(pdev->bus);
> +
> +	if ((reset_type & PCI_RESET_SLOT) == PCI_RESET_SLOT)
> +		return __pci_reset_slot(pdev->slot);
> +
> +	return -EINVAL;


Having three cases here still seems strange.  The below still has some
duplicate probing but doesn't it do the same thing with less redundancy?

if ((reset_type & PCI_RESET_SLOT) && !pci_probe_reset_slot(pdev->slot))
	return __pci_reset_slot(pdev->slot);

if ((reset_type & PCI_RESET_BUS) && !pci_probe_reset_bus(pdev->slot))
	return __pci_reset_bus(pdev->bus);

return -EINVAL;

Thanks,
Alex

>  }
>  EXPORT_SYMBOL_GPL(pci_reset_bus);
>  
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index fe7ada997c51..0e80c72b1eaa 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -1015,7 +1015,8 @@ static long vfio_pci_ioctl(void *device_data,
>  						    &info, slot);
>  		if (!ret)
>  			/* User has access, do the reset */
> -			ret = pci_reset_bus(vdev->pdev);
> +			ret = pci_reset_bus(vdev->pdev,
> +				slot ? PCI_RESET_SLOT :	PCI_RESET_BUS);
>  
>  hot_reset_release:
>  		for (i--; i >= 0; i--)
> @@ -1390,7 +1391,8 @@ static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev)
>  	}
>  
>  	if (needs_reset)
> -		ret = pci_reset_bus(vdev->pdev);
> +		ret = pci_reset_bus(vdev->pdev,
> +				slot ? PCI_RESET_SLOT :	PCI_RESET_BUS);
>  
>  put_devs:
>  	for (i = 0; i < devs.cur_index; i++) {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 1c120cf00dd8..cf1e847ea02e 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1171,7 +1171,7 @@ int pci_reset_function_locked(struct pci_dev *dev, u32 reset_type);
>  int pci_try_reset_function(struct pci_dev *dev, u32 reset_type);
>  int pci_probe_reset_slot(struct pci_slot *slot);
>  int pci_probe_reset_bus(struct pci_bus *bus);
> -int pci_reset_bus(struct pci_dev *dev);
> +int pci_reset_bus(struct pci_dev *dev, u32 reset_type);
>  void pci_reset_secondary_bus(struct pci_dev *dev);
>  void pcibios_reset_secondary_bus(struct pci_dev *dev);
>  void pci_update_resource(struct pci_dev *dev, int resno);