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    Subject[PATCH v3, part1 09/10] PCI, IOV: simplify IOV implementation
    Date
    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@huawei.com>
    Cc: Donald Dutile <ddutile@redhat.com>
    Cc: Yinghai Lu <yinghai@kernel.org>
    Cc: Ram Pai <linuxram@us.ibm.com>
    Cc: linux-pci@vger.kernel.org
    Cc: linux-kernel@vger.kernel.org
    ---
    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:
    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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