4.4-stable review patch. If anyone has any objections, please let me know.
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From: Alex Williamson alex.williamson@redhat.com
[ Upstream commit 16b6c8bb687cc3bec914de09061fcb8411951fda ]
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: Alex Williamson alex.williamson@redhat.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/remove.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/pci/remove.c +++ b/drivers/pci/remove.c @@ -20,9 +20,9 @@ static void pci_stop_dev(struct pci_dev pci_pme_active(dev, false);
if (dev->is_added) { + device_release_driver(&dev->dev); pci_proc_detach_device(dev); pci_remove_sysfs_dev_files(dev); - device_release_driver(&dev->dev); dev->is_added = 0; }