[PATCH net-next 2/8] net: macb: account for stats in Rx XDP codepaths

[Théo Lebrun]

gem_xdp_run() returns an action.
Wrt stats, we land in three different cases:
 - Packet is handed to the stack (XDP_PASS), turns into an SKB and gets
   accounted for below in gem_rx(). No fix here.
 - Packet is dropped (XDP_DROP|ABORTED), we must increment the dropped
   counter. Missing; add it.
 - Packet is passed along (XDP_TX|REDIRECT), we must increment bytes &
   packets counters. Missing; add it.

Along the way, use local variables to store rx_bytes, rx_packets and
rx_dropped. Then increase stats only once at the end of gem_rx(). This
is simpler because all three stats must modified on a per interface and
per queue basis.

Signed-off-by: Théo Lebrun <theo.lebrun@xxxxxxxxxxx>
---
 drivers/net/ethernet/cadence/macb_main.c | 47 +++++++++++++++++++++++---------
 1 file changed, 34 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index ab73d1a522c2..1aa90499343a 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -1627,6 +1627,7 @@ static u32 gem_xdp_run(struct macb_queue *queue, void *buff_head,
 static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
 		  int budget)
 {
+	unsigned int packets = 0, dropped = 0, bytes = 0;
 	struct skb_shared_info *shinfo;
 	struct macb *bp = queue->bp;
 	struct macb_dma_desc *desc;
@@ -1669,8 +1670,7 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
 		if (unlikely(!buff_head)) {
 			dev_err_ratelimited(&bp->pdev->dev,
 					    "inconsistent Rx descriptor chain\n");
-			bp->dev->stats.rx_dropped++;
-			queue->stats.rx_dropped++;
+			dropped++;
 			break;
 		}
 
@@ -1700,11 +1700,29 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
 			if (last_frame) {
 				ret = gem_xdp_run(queue, buff_head, &data_len,
 						  &headroom, addr - gem_rx_pad(bp));
-				if (ret == XDP_REDIRECT)
-					xdp_flush = true;
 
-				if (ret != XDP_PASS)
-					goto next_frame;
+				switch (ret) {
+				/* continue to SKB handling codepath */
+				case XDP_PASS:
+					break;
+
+				/* dropped packet cases */
+				case XDP_ABORTED:
+				case XDP_DROP:
+					dropped++;
+					queue->rx_buff[entry] = NULL;
+					continue;
+
+				/* redirect/tx cases */
+				case XDP_REDIRECT:
+					xdp_flush = true;
+					fallthrough;
+				case XDP_TX:
+					packets++;
+					bytes += data_len;
+					queue->rx_buff[entry] = NULL;
+					continue;
+				}
 			}
 
 			queue->skb = napi_build_skb(buff_head, gem_total_rx_buffer_size(bp));
@@ -1743,10 +1761,8 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
 
 		/* now everything is ready for receiving packet */
 		if (last_frame) {
-			bp->dev->stats.rx_packets++;
-			queue->stats.rx_packets++;
-			bp->dev->stats.rx_bytes += queue->skb->len;
-			queue->stats.rx_bytes += queue->skb->len;
+			packets++;
+			bytes += queue->skb->len;
 
 			queue->skb->protocol = eth_type_trans(queue->skb, bp->dev);
 			skb_checksum_none_assert(queue->skb);
@@ -1769,7 +1785,6 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
 			queue->skb = NULL;
 		}
 
-next_frame:
 		queue->rx_buff[entry] = NULL;
 		continue;
 
@@ -1784,11 +1799,17 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
 						virt_to_head_page(buff_head),
 						false);
 
-		bp->dev->stats.rx_dropped++;
-		queue->stats.rx_dropped++;
+		dropped++;
 		queue->rx_buff[entry] = NULL;
 	}
 
+	bp->dev->stats.rx_packets += packets;
+	queue->stats.rx_packets += packets;
+	bp->dev->stats.rx_dropped += dropped;
+	queue->stats.rx_dropped += dropped;
+	bp->dev->stats.rx_bytes += bytes;
+	queue->stats.rx_bytes += bytes;
+
 	if (xdp_flush)
 		xdp_do_flush();
 

-- 
2.53.0