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authorMichael S. Tsirkin <mst@redhat.com>2010-04-13 04:59:44 +0000
committerDavid S. Miller <davem@davemloft.net>2010-04-14 04:52:03 -0700
commit0110d6f22f392f976e84ab49da1b42f85b64a3c5 (patch)
tree6894f343f66337babdb5615c5a384c49396ade20 /drivers
parent5c659322a904a7cc0265e7b183372b9bdebec6db (diff)
tun: orphan an skb on tx
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@redhat.com> Tested-by: Yan Vugenfirer <yvugenfi@redhat.com> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/tun.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 96c39bddc78..43265207d46 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;