[PATCH net-next 10/17] virtio_net: separate receive_mergeable

[Xuan Zhuo <xuanzhuo@linux.alibaba.com>]

This commit separates the function receive_mergeable(),
put the logic of appending frag to the skb as an independent function.
The subsequent commit will reuse it.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/net/virtio/main.c       | 77 ++++++++++++++++++++-------------
 drivers/net/virtio/virtio_net.h |  4 ++
 2 files changed, 51 insertions(+), 30 deletions(-)

diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c
index e64d52e7d95b..3ea75c62b384 100644
--- a/drivers/net/virtio/main.c
+++ b/drivers/net/virtio/main.c
@@ -1405,6 +1405,49 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
 	return NULL;
 }
 
+struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
+					struct sk_buff *curr_skb,
+					struct page *page, void *buf,
+					int len, int truesize)
+{
+	int num_skb_frags;
+	int offset;
+
+	num_skb_frags = skb_shinfo(curr_skb)->nr_frags;
+	if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
+		struct sk_buff *nskb = alloc_skb(0, GFP_ATOMIC);
+
+		if (unlikely(!nskb))
+			return NULL;
+
+		if (curr_skb == head_skb)
+			skb_shinfo(curr_skb)->frag_list = nskb;
+		else
+			curr_skb->next = nskb;
+		curr_skb = nskb;
+		head_skb->truesize += nskb->truesize;
+		num_skb_frags = 0;
+	}
+
+	if (curr_skb != head_skb) {
+		head_skb->data_len += len;
+		head_skb->len += len;
+		head_skb->truesize += truesize;
+	}
+
+	offset = buf - page_address(page);
+	if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
+		put_page(page);
+		skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
+				     len, truesize);
+	} else {
+		skb_add_rx_frag(curr_skb, num_skb_frags, page,
+				offset, len, truesize);
+	}
+
+	return curr_skb;
+}
+
 static struct sk_buff *receive_mergeable(struct net_device *dev,
 					 struct virtnet_info *vi,
 					 struct virtnet_rq *rq,
@@ -1454,8 +1497,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	if (unlikely(!curr_skb))
 		goto err_skb;
 	while (--num_buf) {
-		int num_skb_frags;
-
 		buf = virtnet_rq_get_buf(rq, &len, &ctx);
 		if (unlikely(!buf)) {
 			pr_debug("%s: rx error: %d buffers out of %d missing\n",
@@ -1480,34 +1521,10 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 			goto err_skb;
 		}
 
-		num_skb_frags = skb_shinfo(curr_skb)->nr_frags;
-		if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
-			struct sk_buff *nskb = alloc_skb(0, GFP_ATOMIC);
-
-			if (unlikely(!nskb))
-				goto err_skb;
-			if (curr_skb == head_skb)
-				skb_shinfo(curr_skb)->frag_list = nskb;
-			else
-				curr_skb->next = nskb;
-			curr_skb = nskb;
-			head_skb->truesize += nskb->truesize;
-			num_skb_frags = 0;
-		}
-		if (curr_skb != head_skb) {
-			head_skb->data_len += len;
-			head_skb->len += len;
-			head_skb->truesize += truesize;
-		}
-		offset = buf - page_address(page);
-		if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
-			put_page(page);
-			skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
-					     len, truesize);
-		} else {
-			skb_add_rx_frag(curr_skb, num_skb_frags, page,
-					offset, len, truesize);
-		}
+		curr_skb  = virtnet_skb_append_frag(head_skb, curr_skb, page,
+						    buf, len, truesize);
+		if (!curr_skb)
+			goto err_skb;
 	}
 
 	ewma_pkt_len_add(&rq->mrg_avg_pkt_len, head_skb->len);
diff --git a/drivers/net/virtio/virtio_net.h b/drivers/net/virtio/virtio_net.h
index 480b533bd61e..1ca92eea8203 100644
--- a/drivers/net/virtio/virtio_net.h
+++ b/drivers/net/virtio/virtio_net.h
@@ -339,4 +339,8 @@ void virtnet_rq_free_unused_bufs(struct virtqueue *vq);
 void virtnet_check_sq_full_and_disable(struct virtnet_info *vi,
 				       struct net_device *dev,
 				       struct virtnet_sq *sq);
+struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
+					struct sk_buff *curr_skb,
+					struct page *page, void *buf,
+					int len, int truesize);
 #endif
-- 
2.32.0.3.g01195cf9f