virtio_net: unify the code for recycling the xmit ptr

There are two completely similar and independent implementations. This
is inconvenient for the subsequent addition of new types. So extract a
function from this piece of code and call this function uniformly to
recover old xmit ptr.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20240229072044.77388-18-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/net/virtio_net.c

@@ -80,6 +80,11 @@ struct virtnet_stat_desc {
 	size_t offset;
 };
 
+struct virtnet_sq_free_stats {
+	u64 packets;
+	u64 bytes;
+};
+
 struct virtnet_sq_stats {
 	struct u64_stats_sync syncp;
 	u64_stats_t packets;
@@ -372,6 +377,31 @@ static struct xdp_frame *ptr_to_xdp(void *ptr)
 	return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG);
 }
 
+static void __free_old_xmit(struct send_queue *sq, bool in_napi,
+			    struct virtnet_sq_free_stats *stats)
+{
+	unsigned int len;
+	void *ptr;
+
+	while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
+		++stats->packets;
+
+		if (!is_xdp_frame(ptr)) {
+			struct sk_buff *skb = ptr;
+
+			pr_debug("Sent skb %p\n", skb);
+
+			stats->bytes += skb->len;
+			napi_consume_skb(skb, in_napi);
+		} else {
+			struct xdp_frame *frame = ptr_to_xdp(ptr);
+
+			stats->bytes += xdp_get_frame_len(frame);
+			xdp_return_frame(frame);
+		}
+	}
+}
+
 /* Converting between virtqueue no. and kernel tx/rx queue no.
  * 0:rx0 1:tx0 2:rx1 3:tx1 ... 2N:rxN 2N+1:txN 2N+2:cvq
  */
@@ -798,37 +828,19 @@ static void virtnet_rq_unmap_free_buf(struct virtqueue *vq, void *buf)
 
 static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi)
 {
-	unsigned int len;
-	unsigned int packets = 0;
-	unsigned int bytes = 0;
-	void *ptr;
+	struct virtnet_sq_free_stats stats = {0};
 
-	while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
-		if (likely(!is_xdp_frame(ptr))) {
-			struct sk_buff *skb = ptr;
-
-			pr_debug("Sent skb %p\n", skb);
-
-			bytes += skb->len;
-			napi_consume_skb(skb, in_napi);
-		} else {
-			struct xdp_frame *frame = ptr_to_xdp(ptr);
-
-			bytes += xdp_get_frame_len(frame);
-			xdp_return_frame(frame);
-		}
-		packets++;
-	}
+	__free_old_xmit(sq, in_napi, &stats);
 
 	/* Avoid overhead when no packets have been processed
 	 * happens when called speculatively from start_xmit.
 	 */
-	if (!packets)
+	if (!stats.packets)
 		return;
 
 	u64_stats_update_begin(&sq->stats.syncp);
-	u64_stats_add(&sq->stats.bytes, bytes);
-	u64_stats_add(&sq->stats.packets, packets);
+	u64_stats_add(&sq->stats.bytes, stats.bytes);
+	u64_stats_add(&sq->stats.packets, stats.packets);
 	u64_stats_update_end(&sq->stats.syncp);
 }
 
@@ -967,15 +979,12 @@ static int virtnet_xdp_xmit(struct net_device *dev,
 			    int n, struct xdp_frame **frames, u32 flags)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
+	struct virtnet_sq_free_stats stats = {0};
 	struct receive_queue *rq = vi->rq;
 	struct bpf_prog *xdp_prog;
 	struct send_queue *sq;
-	unsigned int len;
-	int packets = 0;
-	int bytes = 0;
 	int nxmit = 0;
 	int kicks = 0;
-	void *ptr;
 	int ret;
 	int i;
 
@@ -994,20 +1003,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
 	}
 
 	/* Free up any pending old buffers before queueing new ones. */
-	while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
-		if (likely(is_xdp_frame(ptr))) {
-			struct xdp_frame *frame = ptr_to_xdp(ptr);
-
-			bytes += xdp_get_frame_len(frame);
-			xdp_return_frame(frame);
-		} else {
-			struct sk_buff *skb = ptr;
-
-			bytes += skb->len;
-			napi_consume_skb(skb, false);
-		}
-		packets++;
-	}
+	__free_old_xmit(sq, false, &stats);
 
 	for (i = 0; i < n; i++) {
 		struct xdp_frame *xdpf = frames[i];
@@ -1027,8 +1023,8 @@ static int virtnet_xdp_xmit(struct net_device *dev,
 	}
 out:
 	u64_stats_update_begin(&sq->stats.syncp);
-	u64_stats_add(&sq->stats.bytes, bytes);
-	u64_stats_add(&sq->stats.packets, packets);
+	u64_stats_add(&sq->stats.bytes, stats.bytes);
+	u64_stats_add(&sq->stats.packets, stats.packets);
 	u64_stats_add(&sq->stats.xdp_tx, n);
 	u64_stats_add(&sq->stats.xdp_tx_drops, n - nxmit);
 	u64_stats_add(&sq->stats.kicks, kicks);