(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<yinghai.lu@xxxxxxxxxx> 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? Regards, Kenji Kaneshige -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
