veth: rely on skb_pp_cow_data utility routine

Rely on skb_pp_cow_data utility routine and remove duplicated code.

Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/029cc14cce41cb242ee7efdcf32acc81f1ce4e9f.1707729884.git.lorenzo@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/veth.c

@@ -729,80 +729,10 @@ 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;
+		if (skb_pp_cow_data(rq->page_pool, pskb, XDP_PACKET_HEADROOM))
-		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);
+		skb = *pskb;
-		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);
-			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 "head" area always have tailroom for skb_shared_info */

include/linux/skbuff.h

@@ -3446,6 +3446,8 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f)
 	__skb_frag_ref(&skb_shinfo(skb)->frags[f]);
 }
 
+int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
+		    unsigned int headroom);
 int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
 			 struct bpf_prog *prog);
 bool napi_pp_put_page(struct page *page, bool napi_safe);

net/core/skbuff.c

@@ -895,8 +895,8 @@ static bool is_pp_page(struct page *page)
 	return (page->pp_magic & ~0x3UL) == PP_SIGNATURE;
 }
 
-static int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
+int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
-			   unsigned int headroom)
+		    unsigned int headroom)
 {
 #if IS_ENABLED(CONFIG_PAGE_POOL)
 	u32 size, truesize, len, max_head_size, off;
@@ -975,6 +975,7 @@ static int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
 	return -EOPNOTSUPP;
 #endif
 }
+EXPORT_SYMBOL(skb_pp_cow_data);
 
 int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
 			 struct bpf_prog *prog)