On Thu, Nov 09, 2017 at 02:15:08PM +0300, Mika Westerberg wrote: > During PCIe surprise hot-unplug the device is not accessible anymore and > register reads return 0xffffffff. When that happens pciehp_unconfigure_device() > may inadvertently think the device below the bridge may be a display > device of somesort as reading PCI_BRIDGE_CONTROL register also returns > 0xff. This results failure of the remove operation: > > pciehp 0000:00:1c.0:pcie004: Slot(0): Link Down > pciehp 0000:00:1c.0:pcie004: Slot(0): Card present > pciehp 0000:00:1c.0:pcie004: Cannot remove display device 0000:01:00.0 > > Because of this the hierarchy is left untouched preventing further > hotplug operations. > > Now, it is not clear why the check is there in the first place and why > we would like to prevent removing a bridge if it has PCI_BRIDGE_CTL_VGA > set. In case of PCIe surprise hot-unplug, it would not even be possible > to prevent the removal. > > Given this and the issue described above, I think it makes sense to drop > the whole PCI_BRIDGE_CONTROL check from pciehp_unconfigure_device(). > While there do the same for shpchp_configure_device() based on the same > reasoning and the fact that the same bug might trigger in standard PCI > hotplug as well. > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> Hi Bjorn, Any comments on this patch?
