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    SubjectRe: [PATCH v5 04/16] PCI: prevent duplicate slot names
    * Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>:
    > Alex Chiang wrote:
    >> Ugh, I'm not sure which is worse, an unbalanced API vs passing a
    >> hotplug_slot to pci_destroy_slot.
    >>
    >> pci_destroy_slot should never touch the pci_slot->hotplug
    >> argument, I think, because it is possible for non-hotplug callers
    >> to call pci_create_slot.
    >>
    >> I think the rule should just be:
    >>
    >> - all hotplug drivers must use pci_hp_register/deregister
    >> - hotplug drivers must pass a valid hotplug_slot argument
    >>
    >> - all detection drivers must use pci_create/destroy_slot
    >> - detection drivers must pass NULL for hotplug_slot
    >>
    >
    > I'm still concerned about one thing. Now that we added hotplug
    > arg to pci_create_slot(), pci_bus_sem could be used for changing
    > pci_slot->hotplug. But if there is no generic API to clean up
    > pci_slot->hotplug, we can't use pci_bus_sem because pci hotplug
    > core cannot hold pci_bus_sem. As a result, we need to add the
    > following rule in addition to the above rules.
    >
    > - hotplug core driver must hold some mutex/semaphore when
    > calling pci_create_slot()
    > - hotplug core driver must hold the same mutex/semaphore
    > when cleaning up pci_slot->hotplug.
    >
    > That is, even though pci_create_slot provides the interface to
    > setup pci_slot->hotplug, caller needs to pay attention to race
    > condition about pci_slot->hotplug. I think it's a little strange.

    I think we can use your earlier patch that replaced the hotplug
    list spinlock with a pci_hp_mutex, and that should implement the
    two new rules you mention, right?

    Let me try and insert your patch into the rest of my series and
    see how it looks.

    /ac



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