From: Paul Barker <paul.barker.ct@bp.renesas.com>
Date: Wed, 14 Feb 2024 15:12:04 +0000 (+0000)
Subject: net: ravb: Count packets instead of descriptors in GbEth RX path
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ed4adc07207d9165a4b3b36199231a22e9f51a55;p=linux.git

net: ravb: Count packets instead of descriptors in GbEth RX path

The units of "work done" in the RX path should be packets instead of
descriptors, as large packets can be spread over multiple descriptors.

Fixes: 1c59eb678cbd ("ravb: Fillup ravb_rx_gbeth() stub")
Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/20240214151204.2976-1-paul.barker.ct@bp.renesas.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 0e3731f50fc28..f7566cfa45ca3 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -772,29 +772,25 @@ static bool ravb_rx_gbeth(struct net_device *ndev, int *quota, int q)
 	struct ravb_rx_desc *desc;
 	struct sk_buff *skb;
 	dma_addr_t dma_addr;
+	int rx_packets = 0;
 	u8  desc_status;
-	int boguscnt;
 	u16 pkt_len;
 	u8  die_dt;
 	int entry;
 	int limit;
+	int i;
 
 	entry = priv->cur_rx[q] % priv->num_rx_ring[q];
-	boguscnt = priv->dirty_rx[q] + priv->num_rx_ring[q] - priv->cur_rx[q];
+	limit = priv->dirty_rx[q] + priv->num_rx_ring[q] - priv->cur_rx[q];
 	stats = &priv->stats[q];
 
-	boguscnt = min(boguscnt, *quota);
-	limit = boguscnt;
 	desc = &priv->gbeth_rx_ring[entry];
-	while (desc->die_dt != DT_FEMPTY) {
+	for (i = 0; i < limit && rx_packets < *quota && desc->die_dt != DT_FEMPTY; i++) {
 		/* Descriptor type must be checked before all other reads */
 		dma_rmb();
 		desc_status = desc->msc;
 		pkt_len = le16_to_cpu(desc->ds_cc) & RX_DS;
 
-		if (--boguscnt < 0)
-			break;
-
 		/* We use 0-byte descriptors to mark the DMA mapping errors */
 		if (!pkt_len)
 			continue;
@@ -820,7 +816,7 @@ static bool ravb_rx_gbeth(struct net_device *ndev, int *quota, int q)
 				skb_put(skb, pkt_len);
 				skb->protocol = eth_type_trans(skb, ndev);
 				napi_gro_receive(&priv->napi[q], skb);
-				stats->rx_packets++;
+				rx_packets++;
 				stats->rx_bytes += pkt_len;
 				break;
 			case DT_FSTART:
@@ -848,7 +844,7 @@ static bool ravb_rx_gbeth(struct net_device *ndev, int *quota, int q)
 					eth_type_trans(priv->rx_1st_skb, ndev);
 				napi_gro_receive(&priv->napi[q],
 						 priv->rx_1st_skb);
-				stats->rx_packets++;
+				rx_packets++;
 				stats->rx_bytes += pkt_len;
 				break;
 			}
@@ -887,9 +883,9 @@ static bool ravb_rx_gbeth(struct net_device *ndev, int *quota, int q)
 		desc->die_dt = DT_FEMPTY;
 	}
 
-	*quota -= limit - (++boguscnt);
-
-	return boguscnt <= 0;
+	stats->rx_packets += rx_packets;
+	*quota -= rx_packets;
+	return *quota == 0;
 }
 
 /* Packet receive function for Ethernet AVB */