netdev - [PATCH net-next 2/8] net: ravb: Simplify GbEth poll & receive functions

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Message-Id: <20240131170523.30048-3-paul.barker.ct@bp.renesas.com>
Date: Wed, 31 Jan 2024 17:05:16 +0000
From: Paul Barker <paul.barker.ct@...renesas.com>
To: Sergey Shtylyov <s.shtylyov@....ru>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: Paul Barker <paul.barker.ct@...renesas.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	netdev@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH net-next 2/8] net: ravb: Simplify GbEth poll & receive functions

We don't need to pass the work budget to ravb_rx_gbeth() by reference,
it's cleaner to pass this by value and return the amount of work done.
This allows us to simplify the ravb_poll_gbeth() function and use the
common `work_done` variable name seen in other network drivers for
consistency and ease of understanding.

In ravb_rx_gbeth(), we can also drop the confusingly named `boguscnt`
variable and use a for loop to iterate through descriptors.

This is a pure refactor and should not affect behaviour.

Signed-off-by: Paul Barker <paul.barker.ct@...renesas.com>
---
 drivers/net/ethernet/renesas/ravb_main.c | 25 ++++++++++--------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index c9464c1731b4..5a6a2a7a9e7a 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -822,7 +822,7 @@ static struct sk_buff *ravb_get_skb_gbeth(struct net_device *ndev, int entry,
 }
 
 /* Packet receive function for Gigabit Ethernet */
-static bool ravb_rx_gbeth(struct net_device *ndev, int *quota, int q)
+static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
 {
 	struct ravb_private *priv = netdev_priv(ndev);
 	const struct ravb_hw_info *info = priv->info;
@@ -831,28 +831,24 @@ static bool ravb_rx_gbeth(struct net_device *ndev, int *quota, int q)
 	struct sk_buff *skb;
 	dma_addr_t dma_addr;
 	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;
+	limit = min(limit, budget);
 	desc = &priv->gbeth_rx_ring[entry];
-	while (desc->die_dt != DT_FEMPTY) {
+	for (i = 0; i < limit && 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;
@@ -949,9 +945,7 @@ static bool ravb_rx_gbeth(struct net_device *ndev, int *quota, int q)
 		desc->die_dt = DT_FEMPTY;
 	}
 
-	*quota -= limit - (++boguscnt);
-
-	return boguscnt <= 0;
+	return i;
 }
 
 /* Packet receive function for Ethernet AVB */
@@ -1344,12 +1338,13 @@ static int ravb_poll_gbeth(struct napi_struct *napi, int budget)
 	unsigned long flags;
 	int q = napi - priv->napi;
 	int mask = BIT(q);
-	int quota = budget;
+	int work_done;
 
 	/* Processing RX Descriptor Ring */
 	/* Clear RX interrupt */
 	ravb_write(ndev, ~(mask | RIS0_RESERVED), RIS0);
-	if (ravb_rx_gbeth(ndev, &quota, q))
+	work_done = ravb_rx_gbeth(ndev, budget, q);
+	if (work_done == budget)
 		goto out;
 
 	/* Processing TX Descriptor Ring */
@@ -1382,7 +1377,7 @@ static int ravb_poll_gbeth(struct napi_struct *napi, int budget)
 	if (priv->rx_fifo_errors != ndev->stats.rx_fifo_errors)
 		ndev->stats.rx_fifo_errors = priv->rx_fifo_errors;
 out:
-	return budget - quota;
+	return work_done;
 }
 
 static int ravb_poll_rcar(struct napi_struct *napi, int budget)
-- 
2.39.2