[PATCH v4 bpf-next 01/13] xdp: introduce mb in xdp_buff/xdp_frame

[Lorenzo Bianconi]

Introduce multi-buffer bit (mb) in xdp_frame/xdp_buffer data structure
in order to specify if this is a linear buffer (mb = 0) or a multi-buffer
frame (mb = 1). In the latter case the shared_info area at the end of the
first buffer is been properly initialized to link together subsequent
buffers.

Signed-off-by: Lorenzo Bianconi <lore...@kernel.org>
---
 include/net/xdp.h | 8 ++++++--
 net/core/xdp.c    | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 3814fb631d52..42f439f9fcda 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -72,7 +72,8 @@ struct xdp_buff {
        void *data_hard_start;
        struct xdp_rxq_info *rxq;
        struct xdp_txq_info *txq;
-       u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
+       u32 frame_sz:31; /* frame size to deduce data_hard_end/reserved 
tailroom*/
+       u32 mb:1; /* xdp non-linear buffer */
 };
 
 /* Reserve memory area at end-of data area.
@@ -96,7 +97,8 @@ struct xdp_frame {
        u16 len;
        u16 headroom;
        u32 metasize:8;
-       u32 frame_sz:24;
+       u32 frame_sz:23;
+       u32 mb:1; /* xdp non-linear frame */
        /* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
         * while mem info is valid on remote CPU.
         */
@@ -141,6 +143,7 @@ void xdp_convert_frame_to_buff(struct xdp_frame *frame, 
struct xdp_buff *xdp)
        xdp->data_end = frame->data + frame->len;
        xdp->data_meta = frame->data - frame->metasize;
        xdp->frame_sz = frame->frame_sz;
+       xdp->mb = frame->mb;
 }
 
 static inline
@@ -167,6 +170,7 @@ int xdp_update_frame_from_buff(struct xdp_buff *xdp,
        xdp_frame->headroom = headroom - sizeof(*xdp_frame);
        xdp_frame->metasize = metasize;
        xdp_frame->frame_sz = xdp->frame_sz;
+       xdp_frame->mb = xdp->mb;
 
        return 0;
 }
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 48aba933a5a8..884f140fc3be 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -454,6 +454,7 @@ struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct 
xdp_buff *xdp)
        xdpf->headroom = 0;
        xdpf->metasize = metasize;
        xdpf->frame_sz = PAGE_SIZE;
+       xdpf->mb = xdp->mb;
        xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
 
        xsk_buff_free(xdp);
-- 
2.26.2