[PATCH v8 net-next 4/4] veth: rely on skb_cow_data_for_xdp utility routine

[Lorenzo Bianconi <lorenzo@xxxxxxxxxx>]

Rely on skb_cow_data_for_xdp utility routine and remove duplicated
code.

Acked-by: Jesper Dangaard Brouer <hawk@xxxxxxxxxx>
Reviewed-by: Toke Hoiland-Jorgensen <toke@xxxxxxxxxx>
Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
---
 drivers/net/veth.c | 79 +++-------------------------------------------
 1 file changed, 5 insertions(+), 74 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 578e36ea1589..a7a541c1a374 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -721,7 +721,8 @@ static void veth_xdp_get(struct xdp_buff *xdp)
 
 static int veth_convert_skb_to_xdp_buff(struct veth_rq *rq,
 					struct xdp_buff *xdp,
-					struct sk_buff **pskb)
+					struct sk_buff **pskb,
+					struct bpf_prog *prog)
 {
 	struct sk_buff *skb = *pskb;
 	u32 frame_sz;
@@ -729,80 +730,10 @@ static int veth_convert_skb_to_xdp_buff(struct veth_rq *rq,
 	if (skb_shared(skb) || skb_head_is_locked(skb) ||
 	    skb_shinfo(skb)->nr_frags ||
 	    skb_headroom(skb) < XDP_PACKET_HEADROOM) {
-		u32 size, len, max_head_size, off, truesize, page_offset;
-		struct sk_buff *nskb;
-		struct page *page;
-		int i, head_off;
-		void *va;
-
-		/* We need a private copy of the skb and data buffers since
-		 * the ebpf program can modify it. We segment the original skb
-		 * into order-0 pages without linearize it.
-		 *
-		 * Make sure we have enough space for linear and paged area
-		 */
-		max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE -
-						  VETH_XDP_HEADROOM);
-		if (skb->len > PAGE_SIZE * MAX_SKB_FRAGS + max_head_size)
-			goto drop;
-
-		size = min_t(u32, skb->len, max_head_size);
-		truesize = SKB_HEAD_ALIGN(size) + VETH_XDP_HEADROOM;
-
-		/* Allocate skb head */
-		va = page_pool_dev_alloc_va(rq->page_pool, &truesize);
-		if (!va)
-			goto drop;
-
-		nskb = napi_build_skb(va, truesize);
-		if (!nskb) {
-			page_pool_free_va(rq->page_pool, va, true);
+		if (skb_cow_data_for_xdp(rq->page_pool, pskb, prog))
 			goto drop;
-		}
-
-		skb_reserve(nskb, VETH_XDP_HEADROOM);
-		skb_copy_header(nskb, skb);
-		skb_mark_for_recycle(nskb);
-
-		if (skb_copy_bits(skb, 0, nskb->data, size)) {
-			consume_skb(nskb);
-			goto drop;
-		}
-		skb_put(nskb, size);
 
-		head_off = skb_headroom(nskb) - skb_headroom(skb);
-		skb_headers_offset_update(nskb, head_off);
-
-		/* Allocate paged area of new skb */
-		off = size;
-		len = skb->len - off;
-
-		for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) {
-			size = min_t(u32, len, PAGE_SIZE);
-			truesize = size;
-
-			page = page_pool_dev_alloc(rq->page_pool, &page_offset,
-						   &truesize);
-			if (!page) {
-				consume_skb(nskb);
-				goto drop;
-			}
-
-			skb_add_rx_frag(nskb, i, page, page_offset, size,
-					truesize);
-			if (skb_copy_bits(skb, off,
-					  page_address(page) + page_offset,
-					  size)) {
-				consume_skb(nskb);
-				goto drop;
-			}
-
-			len -= size;
-			off += size;
-		}
-
-		consume_skb(skb);
-		skb = nskb;
+		skb = *pskb;
 	}
 
 	/* SKB "head" area always have tailroom for skb_shared_info */
@@ -850,7 +781,7 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq,
 	}
 
 	__skb_push(skb, skb->data - skb_mac_header(skb));
-	if (veth_convert_skb_to_xdp_buff(rq, xdp, &skb))
+	if (veth_convert_skb_to_xdp_buff(rq, xdp, &skb, xdp_prog))
 		goto drop;
 	vxbuf.skb = skb;
 
-- 
2.43.0