[PATCH 4/6] net: macb: account for stats in Rx XDP codepaths

["Théo Lebrun" <theo.lebrun@bootlin.com>]

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@bootlin.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 37 +++++++++++++++++-------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 05bbbaf260ce..01b4299dc34b 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -1548,6 +1548,7 @@ 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;
@@ -1595,8 +1596,7 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
 		if (unlikely(!buff_head)) {
 			netdev_err(bp->dev,
 				   "inconsistent Rx descriptor chain\n");
-			bp->dev->stats.rx_dropped++;
-			queue->stats.rx_dropped++;
+			dropped++;
 			break;
 		}
 
@@ -1613,10 +1613,21 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
 
 		if (first_frame && last_frame) {
 			ret = gem_xdp_run(queue, buff_head, data_len, addr);
-			if (ret == XDP_REDIRECT)
-				xdp_flush = true;
 
-			if (ret != XDP_PASS) {
+			switch (ret) {
+			case XDP_PASS:
+				break; /* fallthrough to SKB handling */
+			case XDP_ABORTED:
+			case XDP_DROP:
+				dropped++;
+				queue->rx_buff[entry] = NULL;
+				continue;
+			case XDP_REDIRECT:
+				xdp_flush = true;
+				fallthrough;
+			case XDP_TX:
+				packets++;
+				bytes += data_len;
 				queue->rx_buff[entry] = NULL;
 				continue;
 			}
@@ -1672,10 +1683,8 @@ 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;
 
 			gem_ptp_do_rxstamp(bp, queue->skb, desc);
 #if defined(DEBUG) && defined(VERBOSE_DEBUG)
@@ -1704,11 +1713,17 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
 						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