netdev - Re: [PATCH bpf-next 05/15] xsk: add support for bind for Rx

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Date:   Tue, 24 Apr 2018 20:43:30 +0200
From:   Björn Töpel <bjorn.topel@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     "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 05/15] xsk: add support for bind for Rx

2018-04-24 18:55 GMT+02:00 Willem de Bruijn <willemdebruijn.kernel@...il.com>:
> On Mon, Apr 23, 2018 at 9:56 AM, Björn Töpel <bjorn.topel@...il.com> wrote:
>> From: Magnus Karlsson <magnus.karlsson@...el.com>
>>
>> Here, the bind syscall is added. Binding an AF_XDP socket, means
>> associating the socket to an umem, a netdev and a queue index. This
>> can be done in two ways.
>>
>> The first way, creating a "socket from scratch". Create the umem using
>> the XDP_UMEM_REG setsockopt and an associated fill queue with
>> XDP_UMEM_FILL_QUEUE. Create the Rx queue using the XDP_RX_QUEUE
>> setsockopt. Call bind passing ifindex and queue index ("channel" in
>> ethtool speak).
>>
>> The second way to bind a socket, is simply skipping the
>> umem/netdev/queue index, and passing another already setup AF_XDP
>> socket. The new socket will then have the same umem/netdev/queue index
>> as the parent so it will share the same umem. You must also set the
>> flags field in the socket address to XDP_SHARED_UMEM.
>>
>> Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
>> ---
>
>> +static struct socket *xsk_lookup_xsk_from_fd(int fd, int *err)
>> +{
>> +       struct socket *sock;
>> +
>> +       *err = -ENOTSOCK;
>> +       sock = sockfd_lookup(fd, err);
>> +       if (!sock)
>> +               return NULL;
>> +
>> +       if (sock->sk->sk_family != PF_XDP) {
>> +               *err = -ENOPROTOOPT;
>> +               sockfd_put(sock);
>> +               return NULL;
>> +       }
>> +
>> +       *err = 0;
>> +       return sock;
>> +}
>
> In this and similar cases, can use ERR_PTR to avoid the extra argument.

Noted. Thanks!