On Tue, Nov 18, 2014 at 01:20:41PM +0800, Jason Wang wrote:
> After commit 5d097109257c03a71845729f8db6b5770c4bbedc
> ("tun: only queue packets on device"), NETDEV_TX_OK was returned for
> dropped packets. This will confuse pktgen since dropped packets were
> counted as sent ones.
>
> Fixing this by returning NET_XMIT_DROP to let pktgen count it as error
> packet.
>
> Cc: Michael S. Tsirkin <m...@redhat.com>
> Signed-off-by: Jason Wang <jasow...@redhat.com>
> ---
> drivers/net/tun.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index e3fa65a..ac53a73 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -819,7 +819,7 @@ drop:
> skb_tx_error(skb);
> kfree_skb(skb);
> rcu_read_unlock();
> - return NETDEV_TX_OK;
> + return NET_XMIT_DROP;
Quoted from linux/drivers/firewire/net.c:
/*
* FIXME: According to a patch from 2003-02-26, "returning non-zero
* causes serious problems" here, allegedly. Before that patch,
* -ERRNO was returned which is not appropriate under Linux 2.6.
* Perhaps more needs to be done? Stop the queue in serious
* conditions and restart it elsewhere?
*/
I saw many drivers return NETDEV_TX_OK in xmit for drop packets, eg:
virtio_net.c
> }
>
> static void tun_net_mclist(struct net_device *dev)
> --
> 1.9.1
--
Amos.
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