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    SubjectRe: [PATCH 1/7] PCI: Make sriov work with hotplug remove
    On Mon, 2012-01-23 at 11:34 -0800, Linus Torvalds wrote:
    > On Mon, Jan 23, 2012 at 10:45 AM, Linus Torvalds
    > <> wrote:
    > >
    > > Why isn't this magically true in this case? If some *other* random
    > > entry than the one that is being iterated over can magically be
    > > removed, then the whole thing is just pure and utter crap, and no
    > > amount of list maintenance can ever fix it.
    > >
    > > So explain.
    > Ahh. I finally understand what's going on. The virtual device attached
    > to a physical device can go away, and it's on the same damn list.
    > That's broken. Virtual devices set up by a physical device should be
    > *children* of the physical device, not "siblings". But that's
    > apparently not what the broken virtual PCI layer does.

    Thank the PCI SIG for that ... they are sibling functions (or even
    devices in some case) of the PF :-(

    > So I think that there are two possible solutions:
    > (a) fix the virtual devices that are attached to physical devices to
    > really be children of the physical device, with the physical device as
    > a "bridge" to that virtual bus.

    This will confuse various other aspects of the PCI code since they are
    really siblings from an addressing standpoint (ie bus/dev/fn)


    > I think this is the correct solution from any sane standpoint (now the
    > topology of the device tree actually matches the logical
    > relationship), which is why I think this is the RightThing(tm) to do.
    > And it should automatically fix this insane issue where removing a
    > device from a bus can remove *multiple* devices from the same list.
    > (b) if that isn't an option, and the virtual devices make a mess, at
    > least don't make the code uglier, just do something like:
    > while (!list_empty(&bus->devices)) {
    > struct pci_dev *dev = list_first_entry(struct pci_dev, bus_list);
    > pci_stop_bus_device(dev);
    > }
    > which at least isn't butt ugly. Add a large comment about how
    > pci_stop_bus_device() can remove multiple devices due to the virtual
    > devices having been done badly.
    > Who is in charge of the whole 'is_virtfn' mess? How realistic is it to
    > fix that crud?
    > Linus
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      Last update: 2012-01-24 05:37    [W:0.022 / U:72.056 seconds]
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