netdev - Re: [PATCH bpf-next v3 06/15] xsk: add Rx receive functions and poll support

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Date:   Tue, 22 May 2018 09:42:15 +0200
From:   Björn Töpel <bjorn.topel@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     "Karlsson, Magnus" <magnus.karlsson@...el.com>,
        "Duyck, Alexander H" <alexander.h.duyck@...el.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        Alexei Starovoitov <ast@...com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Netdev <netdev@...r.kernel.org>,
        Björn Töpel <bjorn.topel@...el.com>,
        michael.lundkvist@...csson.com,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        "Singhai, Anjali" <anjali.singhai@...el.com>,
        "Zhang, Qi Z" <qi.z.zhang@...el.com>
Subject: Re: [PATCH bpf-next v3 06/15] xsk: add Rx receive functions and poll support

2018-05-04 14:59 GMT+02:00 Daniel Borkmann <daniel@...earbox.net>:
[...]
>> +
>> +int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
>> +{
>> +     int err;
>> +
>> +     err = __xsk_rcv(xs, xdp);
>> +     if (likely(!err))
>> +             xdp_return_buff(xdp);
>> +     else
>> +             xs->rx_dropped++;
>
> This is triggered from __bpf_tx_xdp_map() -> __xsk_map_redirect().
> Should this be percpu counter instead?
>

No, it shouldn't be percpu, but the drop count shouldn't be increased
here. It should be increased as a result of full queue event. Thanks
for pointing this out, I'll fix it.


Björn

[...]