netdev - Re: [PATCH bpf-next 14/15] xsk: statistics support

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Date:   Wed, 25 Apr 2018 12:50:36 +0200
From:   Magnus Karlsson <magnus.karlsson@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     Björn Töpel <bjorn.topel@...il.com>,
        "Karlsson, Magnus" <magnus.karlsson@...el.com>,
        Alexander Duyck <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>,
        Daniel Borkmann <daniel@...earbox.net>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Network Development <netdev@...r.kernel.org>,
        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 14/15] xsk: statistics support

On Tue, Apr 24, 2018 at 6:58 PM, Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
> On Mon, Apr 23, 2018 at 9:56 AM, Björn Töpel <bjorn.topel@...il.com> wrote:
>> From: Magnus Karlsson <magnus.karlsson@...el.com>
>>
>> In this commit, a new getsockopt is added: XDP_STATISTICS. This is
>> used to obtain stats from the sockets.
>>
>> Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
>
>> +static int xsk_getsockopt(struct socket *sock, int level, int optname,
>> +                         char __user *optval, int __user *optlen)
>> +{
>> +       struct sock *sk = sock->sk;
>> +       struct xdp_sock *xs = xdp_sk(sk);
>> +       int len;
>> +
>> +       if (level != SOL_XDP)
>> +               return -ENOPROTOOPT;
>> +
>> +       if (get_user(len, optlen))
>> +               return -EFAULT;
>> +       if (len < 0)
>> +               return -EINVAL;
>> +
>> +       switch (optname) {
>> +       case XDP_STATISTICS:
>> +       {
>> +               struct xdp_statistics stats;
>> +
>> +               if (len != sizeof(stats))
>> +                       return -EINVAL;
>> +
>> +               mutex_lock(&xs->mutex);
>> +               stats.rx_dropped = xs->rx_dropped;
>> +               stats.rx_invalid_descs = xskq_nb_invalid_descs(xs->rx);
>> +               stats.tx_invalid_descs = xskq_nb_invalid_descs(xs->tx);
>> +               mutex_unlock(&xs->mutex);
>> +
>> +               if (copy_to_user(optval, &stats, sizeof(stats)))
>> +                       return -EFAULT;
>> +               return 0;
>
> For forward compatibility, could allow caller to pass a struct larger
> than stats and return the number of bytes filled in.

Yes definitely. Will fix right away.

> The lock can also be elided with something like gnet_stats, but it is probably
> taken rarely enough that that is not worth the effort, at least right now.

Will put this on the ever expanding todo list for future patches ;-).

Thanks: Magnus