[PATCH v8 bpf-next 07/14] net: xdp: add multi-buff support to xdp_build_skb_from_fram

[Lorenzo Bianconi]

Introduce xdp multi-buff support to
__xdp_build_skb_from_frame/xdp_build_skb_from_fram utility
routines.

Signed-off-by: Lorenzo Bianconi <lore...@kernel.org>
---
 net/core/xdp.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/net/core/xdp.c b/net/core/xdp.c
index 430f516259d9..7388bc6d680b 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -603,9 +603,21 @@ struct sk_buff *__xdp_build_skb_from_frame(struct 
xdp_frame *xdpf,
                                           struct sk_buff *skb,
                                           struct net_device *dev)
 {
+       skb_frag_t frag_list[MAX_SKB_FRAGS];
        unsigned int headroom, frame_size;
+       int i, num_frags = 0;
        void *hard_start;
 
+       /* XDP multi-buff frame */
+       if (unlikely(xdpf->mb)) {
+               struct xdp_shared_info *xdp_sinfo;
+
+               xdp_sinfo = xdp_get_shared_info_from_frame(xdpf);
+               num_frags = xdp_sinfo->nr_frags;
+               memcpy(frag_list, xdp_sinfo->frags,
+                      sizeof(skb_frag_t) * num_frags);
+       }
+
        /* Part of headroom was reserved to xdpf */
        headroom = sizeof(*xdpf) + xdpf->headroom;
 
@@ -624,6 +636,20 @@ struct sk_buff *__xdp_build_skb_from_frame(struct 
xdp_frame *xdpf,
        if (xdpf->metasize)
                skb_metadata_set(skb, xdpf->metasize);
 
+       /* Single-buff XDP frame */
+       if (likely(!num_frags))
+               goto out;
+
+       for (i = 0; i < num_frags; i++) {
+               struct page *page = xdp_get_frag_page(&frag_list[i]);
+
+               skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
+                               page, xdp_get_frag_offset(&frag_list[i]),
+                               xdp_get_frag_size(&frag_list[i]),
+                               xdpf->frame_sz);
+       }
+
+out:
        /* Essential SKB info: protocol and skb->dev */
        skb->protocol = eth_type_trans(skb, dev);
 
-- 
2.30.2