[PATCH v7 bpf-next 03/14] net: mvneta: update mb bit before passing the xdp buffer to eBPF layer

[Lorenzo Bianconi]

Update multi-buffer bit (mb) in xdp_buff to notify XDP/eBPF layer and
XDP remote drivers if this is a "non-linear" XDP buffer. Access
xdp_shared_info only if xdp_buff mb is set.

Signed-off-by: Lorenzo Bianconi <lore...@kernel.org>
---
 drivers/net/ethernet/marvell/mvneta.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c 
b/drivers/net/ethernet/marvell/mvneta.c
index b21ba3e36264..009b2c5a90b1 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -2041,12 +2041,16 @@ mvneta_xdp_put_buff(struct mvneta_port *pp, struct 
mvneta_rx_queue *rxq,
 {
        int i;
 
+       if (likely(!xdp->mb))
+               goto out;
+
        for (i = 0; i < xdp_sinfo->nr_frags; i++) {
                skb_frag_t *frag = &xdp_sinfo->frags[i];
 
                page_pool_put_full_page(rxq->page_pool,
                                        xdp_get_frag_page(frag), true);
        }
+out:
        page_pool_put_page(rxq->page_pool, virt_to_head_page(xdp->data),
                           sync_len, true);
 }
@@ -2246,7 +2250,6 @@ mvneta_swbm_rx_frame(struct mvneta_port *pp,
 {
        unsigned char *data = page_address(page);
        int data_len = -MVNETA_MH_SIZE, len;
-       struct xdp_shared_info *xdp_sinfo;
        struct net_device *dev = pp->dev;
        enum dma_data_direction dma_dir;
 
@@ -2270,9 +2273,6 @@ mvneta_swbm_rx_frame(struct mvneta_port *pp,
        prefetch(data);
        xdp_prepare_buff(xdp, data, pp->rx_offset_correction + MVNETA_MH_SIZE,
                         data_len, false);
-
-       xdp_sinfo = xdp_get_shared_info_from_buff(xdp);
-       xdp_sinfo->nr_frags = 0;
 }
 
 static void
@@ -2307,12 +2307,18 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,
                xdp_set_frag_size(frag, data_len);
                xdp_set_frag_page(frag, page);
 
+               if (!xdp->mb) {
+                       xdp_sinfo->data_length = *size;
+                       xdp->mb = 1;
+               }
                /* last fragment */
                if (len == *size) {
                        struct xdp_shared_info *sinfo;
 
                        sinfo = xdp_get_shared_info_from_buff(xdp);
                        sinfo->nr_frags = xdp_sinfo->nr_frags;
+                       sinfo->data_length = xdp_sinfo->data_length;
+
                        memcpy(sinfo->frags, xdp_sinfo->frags,
                               sinfo->nr_frags * sizeof(skb_frag_t));
                }
@@ -2327,11 +2333,15 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct 
mvneta_rx_queue *rxq,
                      struct xdp_buff *xdp, u32 desc_status)
 {
        struct xdp_shared_info *xdp_sinfo = xdp_get_shared_info_from_buff(xdp);
-       int i, num_frags = xdp_sinfo->nr_frags;
        skb_frag_t frag_list[MAX_SKB_FRAGS];
+       int i, num_frags = 0;
        struct sk_buff *skb;
 
-       memcpy(frag_list, xdp_sinfo->frags, sizeof(skb_frag_t) * num_frags);
+       if (unlikely(xdp->mb)) {
+               num_frags = xdp_sinfo->nr_frags;
+               memcpy(frag_list, xdp_sinfo->frags,
+                      sizeof(skb_frag_t) * num_frags);
+       }
 
        skb = build_skb(xdp->data_hard_start, PAGE_SIZE);
        if (!skb)
@@ -2343,6 +2353,9 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct 
mvneta_rx_queue *rxq,
        skb_put(skb, xdp->data_end - xdp->data);
        mvneta_rx_csum(pp, desc_status, skb);
 
+       if (likely(!xdp->mb))
+               return skb;
+
        for (i = 0; i < num_frags; i++) {
                struct page *page = xdp_get_frag_page(&frag_list[i]);
 
@@ -2404,6 +2417,7 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
                        frame_sz = size - ETH_FCS_LEN;
                        desc_status = rx_status;
 
+                       xdp_buf.mb = 0;
                        mvneta_swbm_rx_frame(pp, rx_desc, rxq, &xdp_buf,
                                             &size, page);
                } else {
-- 
2.30.2