On 2/20/22 10:34 PM, Dongli Zhang wrote:
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index aa27268..bf7d8cd 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1062,13 +1062,16 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
> struct netdev_queue *queue;
> struct tun_file *tfile;
> int len = skb->len;
> + enum skb_drop_reason drop_reason;
this function is already honoring reverse xmas tree style, so this needs
to be moved up.
>
> rcu_read_lock();
> tfile = rcu_dereference(tun->tfiles[txq]);
>
> /* Drop packet if interface is not attached */
> - if (!tfile)
> + if (!tfile) {
> + drop_reason = SKB_DROP_REASON_DEV_READY;
> goto drop;
> + }
>
> if (!rcu_dereference(tun->steering_prog))
> tun_automq_xmit(tun, skb);
> @@ -1078,22 +1081,32 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
> /* Drop if the filter does not like it.
> * This is a noop if the filter is disabled.
> * Filter can be enabled only for the TAP devices. */
> - if (!check_filter(&tun->txflt, skb))
> + if (!check_filter(&tun->txflt, skb)) {
> + drop_reason = SKB_DROP_REASON_DEV_FILTER;
> goto drop;
> + }
>
> if (tfile->socket.sk->sk_filter &&
> - sk_filter(tfile->socket.sk, skb))
> + sk_filter(tfile->socket.sk, skb)) {
> + drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
> goto drop;
> + }
>
> len = run_ebpf_filter(tun, skb, len);
> - if (len == 0)
> + if (len == 0) {
> + drop_reason = SKB_DROP_REASON_BPF_FILTER;
how does this bpf filter differ from SKB_DROP_REASON_SOCKET_FILTER? I
think the reason code needs to be a little clearer on the distinction.
