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authorHerbert Xu <herbert@gondor.apana.org.au>2009-07-02 23:03:55 +0000
committerDavid S. Miller <davem@davemloft.net>2009-07-05 18:03:18 -0700
commitd23e43658aed286b885d398ff0810f04f6aae97f (patch)
tree49449c308390dc319fc83378dbd357041c7f27ea /drivers/net/tun.c
parentc001c213b109c8baeeb6d012b422bf059b18368f (diff)
tun: Fix device unregister race
It is currently possible for an asynchronous device unregister to cause the same tun device to be unregistered twice. This is because the unregister in tun_chr_close only checks whether __tun_get(tfile) != NULL. This however has nothing to do with whether the device has already been unregistered. All it tells you is whether __tun_detach has been called. This patch fixes this by using the most obvious thing to test whether the device has been unregistered. It also moves __tun_detach outside of rtnl_unlock since nothing that it does requires that lock. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/tun.c')
-rw-r--r--drivers/net/tun.c16
1 files changed, 9 insertions, 7 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 11a0ba47b677..b393536012fb 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1324,20 +1324,22 @@ static int tun_chr_close(struct inode *inode, struct file *file)
struct tun_file *tfile = file->private_data;
struct tun_struct *tun;
-
- rtnl_lock();
tun = __tun_get(tfile);
if (tun) {
- DBG(KERN_INFO "%s: tun_chr_close\n", tun->dev->name);
+ struct net_device *dev = tun->dev;
+
+ DBG(KERN_INFO "%s: tun_chr_close\n", dev->name);
__tun_detach(tun);
/* If desireable, unregister the netdevice. */
- if (!(tun->flags & TUN_PERSIST))
- unregister_netdevice(tun->dev);
-
+ if (!(tun->flags & TUN_PERSIST)) {
+ rtnl_lock();
+ if (dev->reg_state == NETREG_REGISTERED)
+ unregister_netdevice(dev);
+ rtnl_unlock();
+ }
}
- rtnl_unlock();
tun = tfile->tun;
if (tun)