From: Robert Milasan <rmilasan@suse.com>
Date: Thu, 28 Mar 2013 09:24:43 +0000
Subject: udev always rename network

udev: ensure that the network interfaces are renamed even if they exist
(bnc#809843).
---
 src/udev/udev-event.c | 46 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 43 insertions(+), 3 deletions(-)

Index: systemd-204/src/udev/udev-event.c
===================================================================
--- systemd-204.orig/src/udev/udev-event.c
+++ systemd-204/src/udev/udev-event.c
@@ -750,6 +750,7 @@ static int rename_netif(struct udev_even
         struct udev_device *dev = event->dev;
         int sk;
         struct ifreq ifr;
+        int loop;
         int err;
 
         log_debug("changing net interface name from '%s' to '%s'\n",
@@ -766,12 +767,51 @@ static int rename_netif(struct udev_even
         strscpy(ifr.ifr_name, IFNAMSIZ, udev_device_get_sysname(dev));
         strscpy(ifr.ifr_newname, IFNAMSIZ, event->name);
         err = ioctl(sk, SIOCSIFNAME, &ifr);
-        if (err >= 0) {
+        if (err == 0) {
                 print_kmsg("renamed network interface %s to %s\n", ifr.ifr_name, ifr.ifr_newname);
-        } else {
+		goto out;
+	}
+
+	/* keep trying if the destination interface name already exists */
+	err = -errno;
+	if (err != -EEXIST) {
+		goto out;
+	}
+
+        /* free our own name, another process may wait for us */
+        snprintf(ifr.ifr_newname, IFNAMSIZ, "rename%u", udev_device_get_ifindex(dev));
+        err = ioctl(sk, SIOCSIFNAME, &ifr);
+        if (err < 0) {
                 err = -errno;
-                log_error("error changing net interface name %s to %s: %m\n", ifr.ifr_name, ifr.ifr_newname);
+                goto out;
         }
+
+	/* log temporary name */
+	print_kmsg("renamed network interface %s to %s\n", ifr.ifr_name, ifr.ifr_newname);
+
+        /* wait a maximum of 90 seconds for our target to become available */
+	strscpy(ifr.ifr_name, IFNAMSIZ, ifr.ifr_newname);
+	strscpy(ifr.ifr_newname, IFNAMSIZ, event->name);
+        loop = 90 * 20;
+        while (loop--) {
+        	const struct timespec duration = { 0, 1000 * 1000 * 1000 / 20 };
+
+		log_debug("wait for netif '%s' to become free, loop=%i\n", event->name, (90 * 20) - loop);
+        	nanosleep(&duration, NULL);
+
+		err = ioctl(sk, SIOCSIFNAME, &ifr);
+		if (err == 0) {
+			print_kmsg("renamed network interface %s to %s\n", ifr.ifr_name, ifr.ifr_newname);
+			break;
+		}
+		err = -errno;
+		if (err != -EEXIST)
+			break;
+	}
+
+out:
+        if (err < 0)
+		log_error("error changing net interface name %s to %s: %m\n", ifr.ifr_name, ifr.ifr_newname);
         close(sk);
         return err;
 }