On Mon, Apr 23, 2018 at 9:56 AM, Björn Töpel <[email protected]> wrote:
> From: Magnus Karlsson <[email protected]>
>
> 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 <[email protected]>
> ---
> +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.
