Commit e35259a9 authored Jul 10, 2008 by Max Krasnyansky Committed by David S. Miller Jul 10, 2008

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 <maxk@qualcomm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ccf9b3b8

drivers/net/tun.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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;

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