Re: [PATCH bpf-next v4 03/17] xsk: Add getsockopt XDP_OPTIONS

["Björn Töpel" <bjorn.topel@gmail.com>]

On Wed, 12 Jun 2019 at 20:05, Maxim Mikityanskiy <maximmi@mellanox.com> wrote:
>
> Make it possible for the application to determine whether the AF_XDP
> socket is running in zero-copy mode. To achieve this, add a new
> getsockopt option XDP_OPTIONS that returns flags. The only flag
> supported for now is the zero-copy mode indicator.
>

Acked-by: Björn Töpel <bjorn.topel@intel.com>

> Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
> Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
> Acked-by: Saeed Mahameed <saeedm@mellanox.com>
> ---
>  include/uapi/linux/if_xdp.h       |  8 ++++++++
>  net/xdp/xsk.c                     | 20 ++++++++++++++++++++
>  tools/include/uapi/linux/if_xdp.h |  8 ++++++++
>  3 files changed, 36 insertions(+)
>
> diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
> index caed8b1614ff..faaa5ca2a117 100644
> --- a/include/uapi/linux/if_xdp.h
> +++ b/include/uapi/linux/if_xdp.h
> @@ -46,6 +46,7 @@ struct xdp_mmap_offsets {
>  #define XDP_UMEM_FILL_RING             5
>  #define XDP_UMEM_COMPLETION_RING       6
>  #define XDP_STATISTICS                 7
> +#define XDP_OPTIONS                    8
>
>  struct xdp_umem_reg {
>         __u64 addr; /* Start of packet data area */
> @@ -60,6 +61,13 @@ struct xdp_statistics {
>         __u64 tx_invalid_descs; /* Dropped due to invalid descriptor */
>  };
>
> +struct xdp_options {
> +       __u32 flags;
> +};
> +
> +/* Flags for the flags field of struct xdp_options */
> +#define XDP_OPTIONS_ZEROCOPY (1 << 0)
> +
>  /* Pgoff for mmaping the rings */
>  #define XDP_PGOFF_RX_RING                        0
>  #define XDP_PGOFF_TX_RING               0x80000000
> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> index b68a380f50b3..35ca531ac74e 100644
> --- a/net/xdp/xsk.c
> +++ b/net/xdp/xsk.c
> @@ -650,6 +650,26 @@ static int xsk_getsockopt(struct socket *sock, int level, int optname,
>
>                 return 0;
>         }
> +       case XDP_OPTIONS:
> +       {
> +               struct xdp_options opts = {};
> +
> +               if (len < sizeof(opts))
> +                       return -EINVAL;
> +
> +               mutex_lock(&xs->mutex);
> +               if (xs->zc)
> +                       opts.flags |= XDP_OPTIONS_ZEROCOPY;
> +               mutex_unlock(&xs->mutex);
> +
> +               len = sizeof(opts);
> +               if (copy_to_user(optval, &opts, len))
> +                       return -EFAULT;
> +               if (put_user(len, optlen))
> +                       return -EFAULT;
> +
> +               return 0;
> +       }
>         default:
>                 break;
>         }
> diff --git a/tools/include/uapi/linux/if_xdp.h b/tools/include/uapi/linux/if_xdp.h
> index caed8b1614ff..faaa5ca2a117 100644
> --- a/tools/include/uapi/linux/if_xdp.h
> +++ b/tools/include/uapi/linux/if_xdp.h
> @@ -46,6 +46,7 @@ struct xdp_mmap_offsets {
>  #define XDP_UMEM_FILL_RING             5
>  #define XDP_UMEM_COMPLETION_RING       6
>  #define XDP_STATISTICS                 7
> +#define XDP_OPTIONS                    8
>
>  struct xdp_umem_reg {
>         __u64 addr; /* Start of packet data area */
> @@ -60,6 +61,13 @@ struct xdp_statistics {
>         __u64 tx_invalid_descs; /* Dropped due to invalid descriptor */
>  };
>
> +struct xdp_options {
> +       __u32 flags;
> +};
> +
> +/* Flags for the flags field of struct xdp_options */
> +#define XDP_OPTIONS_ZEROCOPY (1 << 0)
> +
>  /* Pgoff for mmaping the rings */
>  #define XDP_PGOFF_RX_RING                        0
>  #define XDP_PGOFF_TX_RING               0x80000000
> --
> 2.19.1
>