On Tue, 30 Jul 2019 at 19:43, Kevin Laatz <kevin.laatz@xxxxxxxxx> wrote:
>
> This patch adds a 'flags' field to the umem_config and umem_reg structs.
> This will allow for more options to be added for configuring umems.
>
> The first use for the flags field is to add a flag for unaligned chunks
> mode. These flags can either be user-provided or filled with a default.
>
> Signed-off-by: Kevin Laatz <kevin.laatz@xxxxxxxxx>
> Signed-off-by: Ciara Loftus <ciara.loftus@xxxxxxxxx>
>
> ---
> v2:
> - Removed the headroom check from this patch. It has moved to the
> previous patch.
>
> v4:
> - modified chunk flag define
> ---
> tools/include/uapi/linux/if_xdp.h | 9 +++++++--
> tools/lib/bpf/xsk.c | 3 +++
> tools/lib/bpf/xsk.h | 2 ++
> 3 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/tools/include/uapi/linux/if_xdp.h b/tools/include/uapi/linux/if_xdp.h
> index faaa5ca2a117..a691802d7915 100644
> --- a/tools/include/uapi/linux/if_xdp.h
> +++ b/tools/include/uapi/linux/if_xdp.h
> @@ -17,6 +17,10 @@
> #define XDP_COPY (1 << 1) /* Force copy-mode */
> #define XDP_ZEROCOPY (1 << 2) /* Force zero-copy mode */
>
> +/* Flags for xsk_umem_config flags */
> +#define XDP_UMEM_UNALIGNED_CHUNK_FLAG_SHIFT 15
> +#define XDP_UMEM_UNALIGNED_CHUNK_FLAG (1 << XDP_UMEM_UNALIGNED_CHUNK_FLAG_SHIFT)
> +
> struct sockaddr_xdp {
> __u16 sxdp_family;
> __u16 sxdp_flags;
> @@ -49,8 +53,9 @@ struct xdp_mmap_offsets {
> #define XDP_OPTIONS 8
>
> struct xdp_umem_reg {
> - __u64 addr; /* Start of packet data area */
> - __u64 len; /* Length of packet data area */
> + __u64 addr; /* Start of packet data area */
> + __u64 len:48; /* Length of packet data area */
> + __u64 flags:16; /* Flags for umem */
So, the flags member moved from struct sockaddr_xdp to struct
xdp_umem_reg. Makes sense. However, I'm not a fan of the bitfield. Why
not just add the flags member after the last member (headroom) and
deal with it in xsk.c/xsk_setsockopt and libbpf? The bitfield
preserves the size, but makes it hard to read/error prone IMO.
Björn
> __u32 chunk_size;
> __u32 headroom;
> };
> diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
> index 5007b5d4fd2c..5e7e4d420ee0 100644
> --- a/tools/lib/bpf/xsk.c
> +++ b/tools/lib/bpf/xsk.c
> @@ -116,6 +116,7 @@ static void xsk_set_umem_config(struct xsk_umem_config *cfg,
> cfg->comp_size = XSK_RING_CONS__DEFAULT_NUM_DESCS;
> cfg->frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE;
> cfg->frame_headroom = XSK_UMEM__DEFAULT_FRAME_HEADROOM;
> + cfg->flags = XSK_UMEM__DEFAULT_FLAGS;
> return;
> }
>
> @@ -123,6 +124,7 @@ static void xsk_set_umem_config(struct xsk_umem_config *cfg,
> cfg->comp_size = usr_cfg->comp_size;
> cfg->frame_size = usr_cfg->frame_size;
> cfg->frame_headroom = usr_cfg->frame_headroom;
> + cfg->flags = usr_cfg->flags;
> }
>
> static int xsk_set_xdp_socket_config(struct xsk_socket_config *cfg,
> @@ -182,6 +184,7 @@ int xsk_umem__create(struct xsk_umem **umem_ptr, void *umem_area, __u64 size,
> mr.len = size;
> mr.chunk_size = umem->config.frame_size;
> mr.headroom = umem->config.frame_headroom;
> + mr.flags = umem->config.flags;
>
> err = setsockopt(umem->fd, SOL_XDP, XDP_UMEM_REG, &mr, sizeof(mr));
> if (err) {
> diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
> index 833a6e60d065..44a03d8c34b9 100644
> --- a/tools/lib/bpf/xsk.h
> +++ b/tools/lib/bpf/xsk.h
> @@ -170,12 +170,14 @@ LIBBPF_API int xsk_socket__fd(const struct xsk_socket *xsk);
> #define XSK_UMEM__DEFAULT_FRAME_SHIFT 12 /* 4096 bytes */
> #define XSK_UMEM__DEFAULT_FRAME_SIZE (1 << XSK_UMEM__DEFAULT_FRAME_SHIFT)
> #define XSK_UMEM__DEFAULT_FRAME_HEADROOM 0
> +#define XSK_UMEM__DEFAULT_FLAGS 0
>
> struct xsk_umem_config {
> __u32 fill_size;
> __u32 comp_size;
> __u32 frame_size;
> __u32 frame_headroom;
> + __u32 flags;
> };
>
> /* Flags for the libbpf_flags field. */
> --
> 2.17.1
>
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