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author | Michael S. Tsirkin <mst@redhat.com> | 2010-04-13 04:59:44 +0000 |
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committer | David S. Miller <davem@davemloft.net> | 2010-04-14 04:52:03 -0700 |
commit | 0110d6f22f392f976e84ab49da1b42f85b64a3c5 (patch) | |
tree | 6894f343f66337babdb5615c5a384c49396ade20 | |
parent | 5c659322a904a7cc0265e7b183372b9bdebec6db (diff) | |
download | linux-3.10-0110d6f22f392f976e84ab49da1b42f85b64a3c5.tar.gz linux-3.10-0110d6f22f392f976e84ab49da1b42f85b64a3c5.tar.bz2 linux-3.10-0110d6f22f392f976e84ab49da1b42f85b64a3c5.zip |
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>
-rw-r--r-- | 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 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; |