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    SubjectRe: [PATCH 1/8] pci: Make sriov work with hotplug removal
    (2011/10/19 2:02), Yinghai Lu wrote:
    > On 10/18/2011 09:49 AM, Bjorn Helgaas wrote:
    >> On Mon, Oct 17, 2011 at 4:24 PM, Yinghai Lu<> wrote:
    >>> On 10/17/2011 03:12 PM, Bjorn Helgaas wrote:
    >>>> Maybe this is the best we can do, but it still doesn't seem ideal, and
    >>>> it's certainly not obvious when reading the code. It doesn't seem
    >>>> right for the driver ->remove() method to be calling
    >>>> pci_destroy_dev(). Won't the core data structures be corrupted if a
    >>>> defective driver doesn't call pci_disable_sriov()? Seems like we
    >>>> could end up with a device that's been physically removed, but still
    >>>> has pci_dev structs hanging around.
    >>> i did add some print out in
    >>> pci_stop_bus_device
    >>> when stop PF, that function is called for those VFs.
    >>> also driver have to call pci_disable_sriov() and that is current design.
    >> Yep. But I don't have to like the current design :) It doesn't seem
    >> as robust as it could be.
    >> It took me a long time to puzzle out what was happening here. Here's
    >> some possible changelog text that would have saved me a lot of time:
    >> The PCI hot-remove path calls pci_stop_bus_devices() via
    >> pci_remove_bus_device().
    >> pci_stop_bus_devices() traverses the bus->devices list (point A below),
    >> stopping each device in turn, which calls the driver remove() method. When
    >> the device is an SR-IOV PF, the driver calls pci_disable_sriov(), which
    >> also uses pci_remove_bus_device() to remove the VF devices from the
    >> bus->devices list (point B).
    >> pci_remove_bus_device
    >> pci_stop_bus_device
    >> pci_stop_bus_devices(subordinate)
    >> list_for_each(bus->devices)<-- A
    >> pci_stop_bus_device(PF)
    >> ...
    >> driver->remove
    >> pci_disable_sriov
    >> ...
    >> pci_remove_bus_device(VF)
    >> <remove from bus_list> <-- B
    >> At B, we're changing the same list we're iterating through at A, so when
    >> the driver remove() method returns, the pci_stop_bus_devices() iterator has
    >> a pointer to a list entry that has already been freed.
    >> This patch avoids the problem by building a separate list of all PFs on
    >> the bus and traversing that at A instead of the bus->devices list.
    > yes.

    I have one question.

    I think pci_stop_bus_devices() is called only when bridge device is removed.
    Are you trying to hot-remove the bridge device that has SR-IOV capable
    devices on the subordinate bus?

    Kenji Kaneshige

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      Last update: 2011-10-25 14:37    [W:0.025 / U:0.236 seconds]
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