virtio_net: introduce receive_mergeable_xdp()

The purpose of this patch is to simplify the receive_mergeable().
Separate all the logic of XDP into a function.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/virtio_net.c

@@ -1308,6 +1308,66 @@ static void *mergeable_xdp_get_buf(struct virtnet_info *vi,
 	return page_address(*page) + VIRTIO_XDP_HEADROOM;
 }
 
+static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
+					     struct virtnet_info *vi,
+					     struct receive_queue *rq,
+					     struct bpf_prog *xdp_prog,
+					     void *buf,
+					     void *ctx,
+					     unsigned int len,
+					     unsigned int *xdp_xmit,
+					     struct virtnet_rq_stats *stats)
+{
+	struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
+	int num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
+	struct page *page = virt_to_head_page(buf);
+	int offset = buf - page_address(page);
+	unsigned int xdp_frags_truesz = 0;
+	struct sk_buff *head_skb;
+	unsigned int frame_sz;
+	struct xdp_buff xdp;
+	void *data;
+	u32 act;
+	int err;
+
+	data = mergeable_xdp_get_buf(vi, rq, xdp_prog, ctx, &frame_sz, &num_buf, &page,
+				     offset, &len, hdr);
+	if (unlikely(!data))
+		goto err_xdp;
+
+	err = virtnet_build_xdp_buff_mrg(dev, vi, rq, &xdp, data, len, frame_sz,
+					 &num_buf, &xdp_frags_truesz, stats);
+	if (unlikely(err))
+		goto err_xdp;
+
+	act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats);
+
+	switch (act) {
+	case XDP_PASS:
+		head_skb = build_skb_from_xdp_buff(dev, vi, &xdp, xdp_frags_truesz);
+		if (unlikely(!head_skb))
+			break;
+		return head_skb;
+
+	case XDP_TX:
+	case XDP_REDIRECT:
+		return NULL;
+
+	default:
+		break;
+	}
+
+	put_xdp_frags(&xdp);
+
+err_xdp:
+	put_page(page);
+	mergeable_buf_free(rq, num_buf, dev, stats);
+
+	stats->xdp_drops++;
+	stats->drops++;
+	return NULL;
+}
+
 static struct sk_buff *receive_mergeable(struct net_device *dev,
 					 struct virtnet_info *vi,
 					 struct receive_queue *rq,
@@ -1327,8 +1387,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	unsigned int headroom = mergeable_ctx_to_headroom(ctx);
 	unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
 	unsigned int room = SKB_DATA_ALIGN(headroom + tailroom);
-	unsigned int frame_sz;
-	int err;
 
 	head_skb = NULL;
 	stats->bytes += len - vi->hdr_len;
@@ -1348,41 +1406,10 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	rcu_read_lock();
 	xdp_prog = rcu_dereference(rq->xdp_prog);
 	if (xdp_prog) {
-		unsigned int xdp_frags_truesz = 0;
-		struct xdp_buff xdp;
-		void *data;
-		u32 act;
-
-		data = mergeable_xdp_get_buf(vi, rq, xdp_prog, ctx, &frame_sz,
-					     &num_buf, &page, offset, &len, hdr);
-		if (unlikely(!data))
-			goto err_xdp;
-
-		err = virtnet_build_xdp_buff_mrg(dev, vi, rq, &xdp, data, len, frame_sz,
-						 &num_buf, &xdp_frags_truesz, stats);
-		if (unlikely(err))
-			goto err_xdp;
-
-		act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats);
-
-		switch (act) {
-		case XDP_PASS:
-			head_skb = build_skb_from_xdp_buff(dev, vi, &xdp, xdp_frags_truesz);
-			if (unlikely(!head_skb))
-				goto err_xdp_frags;
-
-			rcu_read_unlock();
-			return head_skb;
-		case XDP_TX:
-		case XDP_REDIRECT:
-			rcu_read_unlock();
-			goto xdp_xmit;
-		default:
-			break;
-		}
-err_xdp_frags:
-		put_xdp_frags(&xdp);
-		goto err_xdp;
+		head_skb = receive_mergeable_xdp(dev, vi, rq, xdp_prog, buf, ctx,
+						 len, xdp_xmit, stats);
+		rcu_read_unlock();
+		return head_skb;
 	}
 	rcu_read_unlock();
 
@@ -1452,9 +1479,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	ewma_pkt_len_add(&rq->mrg_avg_pkt_len, head_skb->len);
 	return head_skb;
 
-err_xdp:
-	rcu_read_unlock();
-	stats->xdp_drops++;
 err_skb:
 	put_page(page);
 	mergeable_buf_free(rq, num_buf, dev, stats);
@@ -1462,7 +1486,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 err_buf:
 	stats->drops++;
 	dev_kfree_skb(head_skb);
-xdp_xmit:
 	return NULL;
 }