Messages in this thread | | | From | Linus Torvalds <> | Date | Mon, 23 Jan 2012 11:34:25 -0800 | Subject | Re: [PATCH 1/7] PCI: Make sriov work with hotplug remove |
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On Mon, Jan 23, 2012 at 10:45 AM, Linus Torvalds <torvalds@linux-foundation.org> 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.
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.
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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