[PATCH] net: Ignore sysfs network device rename bugs.

[ebiederm@xmission.com (Eric W. Biederman)]

The generic networking code ensures that no two networking devices
have the same name, so  there is no time except when sysfs has
implementation bugs that device_rename when called from
dev_change_name will fail. 

The current error handling for errors from device_rename in
dev_change_name is wrong and results in an unusable and unrecoverable
network device if device_rename is happens to return an error.

This patch removes the buggy error handling.  Which confines the mess
when device_rename hits a problem to sysfs, instead of propagating it
the rest of the network stack.  Making linux a little more robust.

Without this patch you can observe what happens when sysfs has a bug
when CONFIG_SYSFS_DEPRECATED is not set and you attempt to rename
a real network device to a name like (broken_parity_status, device,
modalias, power, resource2, subsystem_vendor, class,  driver, irq,
msi_bus, resource, subsystem, uevent, config, enable, local_cpus,
numa_node, resource0, subsystem_device, vendor)

Greg has a patch that fixes the sysfs bugs but he doesn't trust it
for a 2.6.21 timeframe.  This patch which just ignores errors should
be safe and it keeps the system from going completely wacky.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 net/core/dev.c |   11 ++++-------
 1 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 5984b55..cf054f9 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -751,13 +751,10 @@ int dev_change_name(struct net_device *dev, char *newname)
 	else
 		strlcpy(dev->name, newname, IFNAMSIZ);
 
-	err = device_rename(&dev->dev, dev->name);
-	if (!err) {
-		hlist_del(&dev->name_hlist);
-		hlist_add_head(&dev->name_hlist, dev_name_hash(dev->name));
-		raw_notifier_call_chain(&netdev_chain,
-				NETDEV_CHANGENAME, dev);
-	}
+	device_rename(&dev->dev, dev->name);
+	hlist_del(&dev->name_hlist);
+	hlist_add_head(&dev->name_hlist, dev_name_hash(dev->name));
+	raw_notifier_call_chain(&netdev_chain, NETDEV_CHANGENAME, dev);
 
 	return err;
 }
-- 
1.5.0.4