On Tue, 30 Apr 2019 at 20:12, Maxim Mikityanskiy <maximmi@xxxxxxxxxxxx> 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.
>
> Signed-off-by: Maxim Mikityanskiy <maximmi@xxxxxxxxxxxx>
> Reviewed-by: Tariq Toukan <tariqt@xxxxxxxxxxxx>
> Acked-by: Saeed Mahameed <saeedm@xxxxxxxxxxxx>
> ---
> include/uapi/linux/if_xdp.h | 7 +++++++
> net/xdp/xsk.c | 22 ++++++++++++++++++++++
> tools/include/uapi/linux/if_xdp.h | 7 +++++++
> 3 files changed, 36 insertions(+)
>
> diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
> index caed8b1614ff..9ae4b4e08b68 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 +61,12 @@ struct xdp_statistics {
> __u64 tx_invalid_descs; /* Dropped due to invalid descriptor */
> };
>
> +struct xdp_options {
> + __u32 flags;
> +};
> +
> +#define XDP_OPTIONS_FLAG_ZEROCOPY (1 << 0)
Nit: The other flags doesn't use "FLAG" in its name, but that doesn't
really matter.
> +
> /* 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..998199109d5c 100644
> --- a/net/xdp/xsk.c
> +++ b/net/xdp/xsk.c
> @@ -650,6 +650,28 @@ 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;
> +
> + opts.flags = 0;
Maybe get rid of this, in favor of "opts = {}" if the structure grows?
> +
> + mutex_lock(&xs->mutex);
> + if (xs->zc)
> + opts.flags |= XDP_OPTIONS_FLAG_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..9ae4b4e08b68 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 +61,12 @@ struct xdp_statistics {
> __u64 tx_invalid_descs; /* Dropped due to invalid descriptor */
> };
>
> +struct xdp_options {
> + __u32 flags;
> +};
> +
> +#define XDP_OPTIONS_FLAG_ZEROCOPY (1 << 0)
> +
> /* Pgoff for mmaping the rings */
> #define XDP_PGOFF_RX_RING 0
> #define XDP_PGOFF_TX_RING 0x80000000
> --
> 2.19.1
>
