dev: Acquire netdev_rename_lock before restoring dev->name in dev_change_name().

The cited commit forgot to add netdev_rename_lock in one of the
error paths in dev_change_name().

Let's hold netdev_rename_lock before restoring the old dev->name.

Fixes: 0840556 ("net: Protect dev->name by seqlock.")
Signed-off-by: Kuniyuki Iwashima <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: q2ven

net/core/dev.c

@@ -1389,7 +1389,9 @@ int dev_change_name(struct net_device *dev, const char *newname)
 rollback:
 	ret = device_rename(&dev->dev, dev->name);
 	if (ret) {
+		write_seqlock_bh(&netdev_rename_lock);
 		memcpy(dev->name, oldname, IFNAMSIZ);
+		write_sequnlock_bh(&netdev_rename_lock);
 		WRITE_ONCE(dev->name_assign_type, old_assign_type);
 		up_write(&devnet_rename_sem);
 		return ret;