On Wed, Sep 19, 2018 at 04:30:37PM +0000, Sinan Kaya 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 | 18 +++++++++++++++---
> drivers/vfio/pci/vfio_pci.c | 6 ++++--
> include/linux/pci.h | 2 +-
> 3 files changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index b4f14419bd51..f11d29f32119 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5232,13 +5232,25 @@ 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) {
> + return (!pci_probe_reset_slot(pdev->slot)) ?
> + __pci_reset_slot(pdev->slot) :
> + __pci_reset_bus(pdev->bus);
> + }
> +
> + if (reset_type & PCI_RESET_BUS)
> + return __pci_reset_bus(pdev->bus);
> +
> + if (reset_type & PCI_RESET_SLOT)
> + return __pci_reset_slot(pdev->slot);
I don't understand this code. We have
#define PCI_RESET_LINK (PCI_RESET_SLOT | PCI_RESET_BUS)
so if either PCI_RESET_BUS or PCI_RESET_SLOT is set, we should take
the first "if" above, which always returns, and the last two should
never be reached. What am I missing?
> +
> + return -EINVAL;
> }
> 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);
This is the only place in the whole series where a caller uses
something other than PCI_RESET_ANY. Inquiring minds want to know why.
I'm sure it's the right thing to do, it's just that we'll need to know
how to choose in future cases.
>
> 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 4fdddcb85066..85f48e156753 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1128,7 +1128,7 @@ 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);
> --
> 2.18.0
>
