From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matthias Schwarzott <zzam@gentoo.org>
Date: Tue, 23 Jan 2007 16:12:55 +0000
Subject: [PATCH] Sanitizing netif-rename code
Message-Id: <200701231712.56015.zzam@gentoo.org>
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List-Id: <linux-hotplug.vger.kernel.org>
To: linux-hotplug@vger.kernel.org

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Hi there!

The attached patch comes origins from this Bugreport:
http://bugs.gentoo.org/show_bug.cgi?id=158531

The original code from udev_device.c / function rename_netif looks like this:
while (loop--) {
	retval = ioctl(sk, SIOCSIFNAME, &ifr);
	if (retval != 0) {
		if (errno != EEXIST) {
			err("error changing net interface name %s to %s: %s",
				ifr.ifr_name, ifr.ifr_newname, strerror(errno));
			break;
		}
		dbg("wait for netif '%s' to become free, loop=%i", udev->name, (30 * 20) -
			loop);
		usleep(1000 * 1000 / 20);
	}
}


In some loop the rename-syscall will succeed, and retval is 0.
In this case the loop is not left, but just retried the loop and executing the 
rename code over and over again.

Attached patch adds something similar to that (inside the loop):
if (retval == 0)
	break;

Greetings
  Matthias

-- 
Matthias Schwarzott (zzam)

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diff -Nur udev-103old/udev_device.c udev-103/udev_device.c
--- udev-103old/udev_device.c	2006-10-20 14:43:35.000000000 +0200
+++ udev-103/udev_device.c	2006-12-20 12:04:52.000000000 +0100
@@ -122,16 +122,18 @@
 		strlcpy(ifr.ifr_newname, udev->name, IFNAMSIZ);
 		loop = 30 * 20;
 		while (loop--) {
-			retval = ioctl(sk, SIOCSIFNAME, &ifr);	
-			if (retval != 0) {
+			retval = ioctl(sk, SIOCSIFNAME, &ifr);
+			if (retval == 0) {
+				break;
+			} else {
 				if (errno != EEXIST) {
 					err("error changing net interface name %s to %s: %s",
 					    ifr.ifr_name, ifr.ifr_newname, strerror(errno));
 					break;
 				}
-				dbg("wait for netif '%s' to become free, loop=%i", udev->name, (30 * 20) - loop);
-				usleep(1000 * 1000 / 20);
 			}
+			dbg("wait for netif '%s' to become free, loop=%i", udev->name, (30 * 20) - loop);
+			usleep(1000 * 1000 / 20);
 		}
 	}
 

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