• Alex Williamson's avatar
    PCI: Detach driver before procfs & sysfs teardown on device remove · 96ed7ca7
    Alex Williamson authored
    
    [ Upstream commit 16b6c8bb ]
    
    When removing a device, for example a VF being removed due to SR-IOV
    teardown, a "soft" hot-unplug via 'echo 1 > remove' in sysfs, or an actual
    hot-unplug, we first remove the procfs and sysfs attributes for the device
    before attempting to release the device from any driver bound to it.
    Unbinding the driver from the device can take time.  The device might need
    to write out data or it might be actively in use.  If it's in use by
    userspace through a vfio driver, the unbind might block until the user
    releases the device.  This leads to a potentially non-trivial amount of
    time where the device exists, but we've torn down the interfaces that
    userspace uses to examine devices, for instance lspci might generate this
    sort of error:
    
      pcilib: Cannot open /sys/bus/pci/devices/0000:01:0a.3/config
      lspci: Unable to read the standard configuration space header of device 0000:01:0a.3
    
    We don't seem to have any dependence on this teardown ordering in the
    kernel, so let's unbind the driver first, which is also more symmetric with
    the instantiation of the device in pci_bus_add_device().
    Signed-off-by: 's avatarAlex Williamson <alex.williamson@redhat.com>
    Signed-off-by: 's avatarBjorn Helgaas <bhelgaas@google.com>
    Signed-off-by: 's avatarSasha Levin <alexander.levin@verizon.com>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    96ed7ca7