This is commit 0110d6f22f392f976e84ab49da1b42f85b64a3c5 in net-2.6 Please cherry-pick this fix for F13 (in fact, it's needed for F12 as well).
----- Forwarded message from "Michael S. Tsirkin" mst@redhat.com -----
Date: Wed, 21 Apr 2010 14:35:57 +0300 From: "Michael S. Tsirkin" mst@redhat.com To: stable@kernel.org Cc: "David S. Miller" davem@davemloft.net, Herbert Xu herbert@gondor.hengli.com.au, Paul Moore paul.moore@hp.com, David Woodhouse David.Woodhouse@intel.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jan Kiszka jan.kiszka@siemens.com, qemu-devel qemu-devel@nongnu.org Subject: Re: [PATCH] tun: orphan an skb on tx Message-ID: 20100421113557.GA31606@redhat.com In-Reply-To: 20100413145944.GA7716@redhat.com
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@redhat.com Tested-by: Yan Vugenfirer yvugenfi@redhat.com
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
This is commit 0110d6f22f392f976e84ab49da1b42f85b64a3c5 in net-2.6 Please cherry-pick this fix in stable kernels (2.6.32 and 2.6.33).
Thanks!
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