From bd1bb4504d1afe264fd3f739614b97aac8d62bf0 Mon Sep 17 00:00:00 2001
From: Tom Gundersen <teg@jklm.no>
Date: Tue, 25 Aug 2015 14:12:19 +0200
Subject: [PATCH] udev: net_id - support predictable ifnames on virtio buses

Virtio buses are undeterministically enumerated, so we cannot use them as a basis
for deterministic naming (see bf81e792f3c0). However, we are guaranteed that there
is only ever one virtio bus for every parent device, so we can simply skip over
the virtio buses when naming the devices.

Cherry-picked from: 54683f0f9b97a8f88aaf4fbb45b4d729057b101c
Resolves: #1259015
---
 src/udev/udev-builtin-net_id.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/udev/udev-builtin-net_id.c b/src/udev/udev-builtin-net_id.c
index dd2886caf2..ddd83d4f1b 100644
--- a/src/udev/udev-builtin-net_id.c
+++ b/src/udev/udev-builtin-net_id.c
@@ -283,8 +283,16 @@ static int names_pci(struct udev_device *dev, struct netnames *names) {
         struct udev_device *parent;
 
         parent = udev_device_get_parent(dev);
+
+        /* there can only ever be one virtio bus per parent device, so we can
+           safely ignore any virtio buses. see
+           <http://lists.linuxfoundation.org/pipermail/virtualization/2015-August/030331.html> */
+        while (parent && streq_ptr("virtio", udev_device_get_subsystem(parent)))
+                parent = udev_device_get_parent(parent);
+
         if (!parent)
                 return -ENOENT;
+
         /* check if our direct parent is a PCI device with no other bus in-between */
         if (streq_ptr("pci", udev_device_get_subsystem(parent))) {
                 names->type = NET_PCI;