net: mvneta: update frags bit before passing the xdp buffer to eBPF layer

Update frags bit (XDP_FLAGS_HAS_FRAGS) in xdp_buff to notify
XDP/eBPF layer and XDP remote drivers if this is a "non-linear"
XDP buffer. Access skb_shared_info only if XDP_FLAGS_HAS_FRAGS flag
is set in order to avoid possible cache-misses.

Acked-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/c00a73097f8a35860d50dae4a36e6cc9ef7e172f.1642758637.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 83c8908..a3e74a4 100644 (file)
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -2065,9 +2065,14 @@ mvneta_xdp_put_buff(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
 {
        int i;
 
+       if (likely(!xdp_buff_has_frags(xdp)))
+               goto out;
+
        for (i = 0; i < sinfo->nr_frags; i++)
                page_pool_put_full_page(rxq->page_pool,
                                        skb_frag_page(&sinfo->frags[i]), true);
+
+out:
        page_pool_put_page(rxq->page_pool, virt_to_head_page(xdp->data),
                           sync_len, true);
 }
@@ -2269,7 +2274,6 @@ mvneta_swbm_rx_frame(struct mvneta_port *pp,
        int data_len = -MVNETA_MH_SIZE, len;
        struct net_device *dev = pp->dev;
        enum dma_data_direction dma_dir;
-       struct skb_shared_info *sinfo;
 
        if (*size > MVNETA_MAX_RX_BUF_SIZE) {
                len = MVNETA_MAX_RX_BUF_SIZE;
@@ -2289,11 +2293,9 @@ mvneta_swbm_rx_frame(struct mvneta_port *pp,
 
        /* Prefetch header */
        prefetch(data);
+       xdp_buff_clear_frags_flag(xdp);
        xdp_prepare_buff(xdp, data, pp->rx_offset_correction + MVNETA_MH_SIZE,
                         data_len, false);
-
-       sinfo = xdp_get_shared_info_from_buff(xdp);
-       sinfo->nr_frags = 0;
 }
 
 static void
@@ -2327,6 +2329,9 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,
                skb_frag_off_set(frag, pp->rx_offset_correction);
                skb_frag_size_set(frag, data_len);
                __skb_frag_set_page(frag, page);
+
+               if (!xdp_buff_has_frags(xdp))
+                       xdp_buff_set_frags_flag(xdp);
        } else {
                page_pool_put_full_page(rxq->page_pool, page, true);
        }
@@ -2348,8 +2353,12 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct page_pool *pool,
                      struct xdp_buff *xdp, u32 desc_status)
 {
        struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
-       int i, num_frags = sinfo->nr_frags;
        struct sk_buff *skb;
+       u8 num_frags;
+       int i;
+
+       if (unlikely(xdp_buff_has_frags(xdp)))
+               num_frags = sinfo->nr_frags;
 
        skb = build_skb(xdp->data_hard_start, PAGE_SIZE);
        if (!skb)
@@ -2361,6 +2370,9 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct page_pool *pool,
        skb_put(skb, xdp->data_end - xdp->data);
        skb->ip_summed = mvneta_rx_csum(pp, desc_status);
 
+       if (likely(!xdp_buff_has_frags(xdp)))
+               goto out;
+
        for (i = 0; i < num_frags; i++) {
                skb_frag_t *frag = &sinfo->frags[i];
 
@@ -2369,6 +2381,7 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct page_pool *pool,
                                skb_frag_size(frag), PAGE_SIZE);
        }
 
+out:
        return skb;
 }