PCI: Create SR-IOV virtfn/physfn links before attaching driver

BugLink: http://bugs.launchpad.net/bugs/1745054

[ Upstream commit 27d61629 ]

When creating virtual functions, create the "virtfn%u" and "physfn" links
in sysfs *before* attaching the driver instead of after.  When we attach
the driver to the new virtual network interface first, there is a race when
the driver attaches to the new sends out an "add" udev event, and the
network interface naming software (biosdevname or systemd, for example)
tries to look at these links.
Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.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>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/pci/iov.c

@@ -161,7 +161,6 @@ static int virtfn_add(struct pci_dev *dev, int id, int reset)
 	pci_device_add(virtfn, virtfn->bus);
 	mutex_unlock(&iov->dev->sriov->lock);
 
-	pci_bus_add_device(virtfn);
 	sprintf(buf, "virtfn%u", id);
 	rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
 	if (rc)
@@ -172,6 +171,8 @@ static int virtfn_add(struct pci_dev *dev, int id, int reset)
 
 	kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);
 
+	pci_bus_add_device(virtfn);
+
 	return 0;
 
 failed2: