Re: [PATCH net-next] fq_codel: report congestion notification at enqueue time

David Miller
2012-06-29T07:53:57Z

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 29 Jun 2012 07:50:08 +0200

> Hmm, problem is the sender thinks the packet was queued for
> transmission.
>
> ret = macvlan_queue_xmit(skb, dev);
> if (likely(ret == NET_XMIT_SUCCESS || ret == NET_XMIT_CN)) {
> struct macvlan_pcpu_stats *pcpu_stats;
>
> pcpu_stats = this_cpu_ptr(vlan->pcpu_stats);
> u64_stats_update_begin(&pcpu_stats->syncp);
> pcpu_stats->tx_packets++;
> pcpu_stats->tx_bytes += len;
> u64_stats_update_end(&pcpu_stats->syncp);
> } else {
> this_cpu_inc(vlan->pcpu_stats->tx_dropped);
> }
>
> NET_XMIT_CN has a lazy semantic it seems.
>
> I will just dont rely on it.

I think we cannot just ignore this issue. I will take a deeper look,
because we should have NET_XMIT_CN be very well defined and adjust any
mis-use.