On Wed, Nov 6, 2013 at 10:15 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> commit dfb66fee4715c747a94abd45c20fbe302b10e49c
> Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Date: Wed Nov 6 10:11:48 2013 -0700
>
> PCI: Add pci_upstream_bridge()
>
> This adds a pci_upstream_bridge() interface to find the PCI-to-PCI bridge
> upstream from a device. If the device is on a root bus, i.e., the upstream
> bridge is a host bridge instead of a PCI bridge, this returns NULL. If the
> device is a VF, this returns the bridge upstream from the PF corresponding
> to the VF. This is important for VFs on virtual buses, where
> "dev->bus->self == NULL".
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index d3a888a..e09d19a 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -480,6 +480,18 @@ static inline bool pci_is_root_bus(struct pci_bus *pbus)
> return !(pbus->parent);
> }
>
> +static inline struct pci_dev *pci_upstream_bridge(struct pci_dev *dev)
> +{
> + if (pci_is_root_bus(dev->bus))
> + return NULL;
> +
> + dev = pci_physfn(dev);
> + if (pci_is_root_bus(dev->bus))
> + return NULL;
Maybe we can drop the first pci_is_root_bus() checking.
for physfn, pci_physfn will return it's self.
> +
> + return dev->bus->self;
> +}
> +
> #ifdef CONFIG_PCI_MSI
> static inline bool pci_dev_msi_enabled(struct pci_dev *pci_dev)
> {
> commit 4e5415f02e32c85e902cd9692eab18200e14b347
> Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Date: Wed Nov 6 10:00:51 2013 -0700
>
> PCI: Enable upstream bridges even for VFs on virtual buses
>
> Previously we enabled the upstream PCI-to-PCI bridge only when
> "dev->bus->self != NULL". In the case of a VF on a virtual bus, where
> "bus->self == NULL", we didn't enable the upstream bridge.
>
> This fixes that by enabling the upstream bridge of the PF corresponding to
> the VF.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index ac40f90..744dc26 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1150,10 +1150,8 @@ static void pci_enable_bridge(struct pci_dev *dev)
> {
> int retval;
>
> - if (!dev)
> - return;
> -
> - pci_enable_bridge(dev->bus->self);
> + if (!pci_is_root_bus(dev->bus))
> + pci_enable_bridge(pci_upstream_bridge(dev));
>
> if (pci_is_enabled(dev)) {
> if (!dev->is_busmaster)
> @@ -1188,7 +1186,8 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
> if (atomic_inc_return(&dev->enable_cnt) > 1)
> return 0; /* already enabled */
>
> - pci_enable_bridge(dev->bus->self);
> + if (!pci_is_root_bus(dev->bus))
> + pci_enable_bridge(pci_upstream_bridge(dev));
>
> /* only skip sriov related */
> for (i = 0; i <= PCI_ROM_RESOURCE; i++)
still have problem.
pci_upstream_bridge() could return NULL. so later pci_enable_bridge()
referring dev->bus could panic, as you remove !dev checking.
Maybe you can cache return from pci_upstream_bridge and check that before
calling pci_enable_bridge.
Thanks
Yinghai
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