Re: [PATCH v3, part1 09/10] PCI, IOV: simplify IOV implementation

[Yinghai Lu]

On Sat, May 25, 2013 at 6:48 AM, Jiang Liu <liuj97@xxxxxxxxx> wrote:
> Trivial changes to IOV:
> 1) use new PCI interfaces to simplify IOV implementation
> 2) fix some reference count related race windows
>
> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
> Cc: Donald Dutile <ddutile@xxxxxxxxxx>
> Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
> Cc: Ram Pai <linuxram@xxxxxxxxxx>
> Cc: linux-pci@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
>  drivers/pci/iov.c | 58 +++++++++++++++++++++----------------------------------
>  1 file changed, 22 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index 8f1e117..3e33499 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -51,43 +51,30 @@ static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
>         return child;
>  }
>
> -static void virtfn_remove_bus(struct pci_bus *bus, int busnr)
> +static void virtfn_remove_bus(struct pci_bus *physbus, struct pci_bus *virtbus)
>  {
> -       struct pci_bus *child;
> -
> -       if (bus->number == busnr)
> -               return;
> -
> -       child = pci_find_bus(pci_domain_nr(bus), busnr);
> -       BUG_ON(!child);
> -
> -       if (list_empty(&child->devices))
> -               pci_remove_bus(child);
> +       if (physbus != virtbus && list_empty(&virtbus->devices))
> +               pci_remove_bus(virtbus);
>  }
>
>  static int virtfn_add(struct pci_dev *dev, int id, int reset)
>  {
>         int i;
> -       int rc;
> +       int rc = -ENOMEM;
>         u64 size;
>         char buf[VIRTFN_ID_LEN];
> -       struct pci_dev *virtfn;
> +       struct pci_dev *virtfn = NULL;
>         struct resource *res;
>         struct pci_sriov *iov = dev->sriov;
>         struct pci_bus *bus;
>
> -       virtfn = pci_alloc_dev(NULL);
> -       if (!virtfn)
> -               return -ENOMEM;
> -
>         mutex_lock(&iov->dev->sriov->lock);
>         bus = virtfn_add_bus(dev->bus, virtfn_bus(dev, id));
> -       if (!bus) {
> -               kfree(virtfn);
> -               mutex_unlock(&iov->dev->sriov->lock);
> -               return -ENOMEM;
> -       }
> -       virtfn->bus = pci_bus_get(bus);
> +       if (bus)
> +               virtfn = pci_alloc_dev(bus);
> +       if (!virtfn)
> +               goto failed0;
> +
>         virtfn->devfn = virtfn_devfn(dev, id);
>         virtfn->vendor = dev->vendor;
>         pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_DID, &virtfn->device);
> @@ -136,7 +123,8 @@ failed1:
>         pci_dev_put(dev);
>         mutex_lock(&iov->dev->sriov->lock);
>         pci_stop_and_remove_bus_device(virtfn);
> -       virtfn_remove_bus(dev->bus, virtfn_bus(dev, id));
> +       virtfn_remove_bus(dev->bus, bus);
> +failed0:

need to swap above two lines. otherwise virtual bus could not be removed.

>         mutex_unlock(&iov->dev->sriov->lock);
>
>         return rc;
> @@ -145,20 +133,15 @@ failed1:
>  static void virtfn_remove(struct pci_dev *dev, int id, int reset)
>  {
>         char buf[VIRTFN_ID_LEN];
> -       struct pci_bus *bus;
>         struct pci_dev *virtfn;
>         struct pci_sriov *iov = dev->sriov;
>
> -       bus = pci_find_bus(pci_domain_nr(dev->bus), virtfn_bus(dev, id));
> -       if (!bus)
> -               return;
> -
> -       virtfn = pci_get_slot(bus, virtfn_devfn(dev, id));
> +       virtfn = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus),
> +                                            virtfn_bus(dev, id),
> +                                            virtfn_devfn(dev, id));
>         if (!virtfn)
>                 return;
>
> -       pci_dev_put(virtfn);
> -
>         if (reset) {
>                 device_release_driver(&virtfn->dev);
>                 __pci_reset_function(virtfn);
> @@ -176,9 +159,11 @@ static void virtfn_remove(struct pci_dev *dev, int id, int reset)
>
>         mutex_lock(&iov->dev->sriov->lock);
>         pci_stop_and_remove_bus_device(virtfn);
> -       virtfn_remove_bus(dev->bus, virtfn_bus(dev, id));
> +       virtfn_remove_bus(dev->bus, virtfn->bus);
>         mutex_unlock(&iov->dev->sriov->lock);
>
> +       /* balance pci_get_domain_bus_and_slot() */
> +       pci_dev_put(virtfn);
>         pci_dev_put(dev);
>  }
>
> @@ -335,13 +320,14 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
>                 if (!pdev)
>                         return -ENODEV;
>
> -               pci_dev_put(pdev);
> -
> -               if (!pdev->is_physfn)
> +               if (!pdev->is_physfn) {
> +                       pci_dev_put(pdev);
>                         return -ENODEV;
> +               }
>
>                 rc = sysfs_create_link(&dev->dev.kobj,
>                                         &pdev->dev.kobj, "dep_link");
> +               pci_dev_put(pdev);
>                 if (rc)
>                         return rc;
>         }
> --
> 1.8.1.2
>
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