tun: Persistent devices can get stuck in xoff state

The scenario goes like this. App stops reading from tun/tap. TX queue gets full and driver does netif_stop_queue(). App closes fd and TX queue gets flushed as part of the cleanup. Next time the app opens tun/tap and starts reading from it but the xoff state is not cleared. We're stuck. Normally xoff state is cleared when netdev is brought up. But in the case of persistent devices this happens only during initial setup. The fix is trivial. If device is already up when an app opens it we clear xoff state and that gets things moving again. Signed-off-by: Max Krasnyansky <[email protected]> Tested-by: Christian Borntraeger <[email protected]> Signed-off-by: David S. Miller <[email protected]>
hjking · Jul 10, 2008 · e35259a · e35259a
1 parent ccf9b3b
commit e35259a
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
@@ -602,6 +602,12 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 	tun->attached = 1;
 	get_net(dev_net(tun->dev));
 
+	/* Make sure persistent devices do not get stuck in
+	 * xoff state.
+	 */
+	if (netif_running(tun->dev))
+		netif_wake_queue(tun->dev);
+
 	strcpy(ifr->ifr_name, tun->dev->name);
 	return 0;