I looked at the macvtap driver and it seems that it should have the below issue, same as tap. Arnd? On Tue, Apr 13, 2010 at 05:59:44PM +0300, Michael S. Tsirkin wrote: > The following situation was observed in the field: > tap1 sends packets, tap2 does not consume them, as a result > tap1 can not be closed. This happens because > tun/tap devices can hang on to skbs undefinitely. > > As noted by Herbert, possible solutions include a timeout followed by a > copy/change of ownership of the skb, or always copying/changing > ownership if we're going into a hostile device. > > This patch implements the second approach. > > Note: one issue still remaining is that since skbs > keep reference to tun socket and tun socket has a > reference to tun device, we won't flush backlog, > instead simply waiting for all skbs to get transmitted. > At least this is not user-triggerable, and > this was not reported in practice, my assumption is > other devices besides tap complete an skb > within finite time after it has been queued. > > A possible solution for the second issue > would not to have socket reference the device, > instead, implement dev->destructor for tun, and > wait for all skbs to complete there, but this > needs some thought, probably too risky for 2.6.34. > > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > Tested-by: Yan Vugenfirer <yvugenfi@xxxxxxxxxx> > > --- > > Please review the below, and consider for 2.6.34, > and stable trees. > > drivers/net/tun.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index 96c39bd..4326520 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -387,6 +387,10 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) > } > } > > + /* Orphan the skb - required as we might hang on to it > + * for indefinite time. */ > + skb_orphan(skb); > + > /* Enqueue packet */ > skb_queue_tail(&tun->socket.sk->sk_receive_queue, skb); > dev->trans_start = jiffies; > -- > 1.7.0.2.280.gc6f05 > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
