linux-kernel - [PATCH net-next 12/15] net: macb: drop `entry` local variable in macb_tx

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Message-Id: <20251014-macb-cleanup-v1-12-31cd266e22cd@bootlin.com>
Date: Tue, 14 Oct 2025 17:25:13 +0200
From: Théo Lebrun <theo.lebrun@...tlin.com>
To: Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Nicolas Ferre <nicolas.ferre@...rochip.com>, 
 Claudiu Beznea <claudiu.beznea@...on.dev>, 
 Richard Cochran <richardcochran@...il.com>, 
 Russell King <linux@...linux.org.uk>
Cc: netdev@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>, 
 Tawfik Bayouk <tawfik.bayouk@...ileye.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Grégory Clement <gregory.clement@...tlin.com>, 
 Benoît Monin <benoit.monin@...tlin.com>, 
 Maxime Chevallier <maxime.chevallier@...tlin.com>, 
 Théo Lebrun <theo.lebrun@...tlin.com>
Subject: [PATCH net-next 12/15] net: macb: drop `entry` local variable in
 macb_tx_map()

The pattern:
   entry = macb_tx_ring_wrap(bp, i);
   tx_skb = &queue->tx_skb[entry];
is the exact definition of:
   macb_tx_skb(queue, i);

The pattern:
   entry = macb_tx_ring_wrap(bp, i);
   desc = macb_tx_desc(queue, entry);
is redundant because macb_tx_desc() calls macb_tx_ring_wrap().

One explicit call to macb_tx_ring_wrap() is still required for checking
if it is the last buffer (TX_WRAP case).

Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 6c6bc6aa23c718772b95b398e807f193a38e141a..08e541d8f8e68e38442a538ce352508c5db63f52 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -1989,7 +1989,7 @@ static unsigned int macb_tx_map(struct macb *bp,
 				unsigned int hdrlen)
 {
 	dma_addr_t mapping;
-	unsigned int len, entry, i, tx_head = queue->tx_head;
+	unsigned int len, i, tx_head = queue->tx_head;
 	struct macb_tx_skb *tx_skb = NULL;
 	struct macb_dma_desc *desc;
 	unsigned int offset, size, count = 0;
@@ -2015,8 +2015,7 @@ static unsigned int macb_tx_map(struct macb *bp,

 	offset = 0;
 	while (len) {
-		entry = macb_tx_ring_wrap(bp, tx_head);
-		tx_skb = &queue->tx_skb[entry];
+		tx_skb = macb_tx_skb(queue, tx_head);

 		mapping = dma_map_single(&bp->pdev->dev,
 					 skb->data + offset,
@@ -2046,8 +2045,7 @@ static unsigned int macb_tx_map(struct macb *bp,
 		offset = 0;
 		while (len) {
 			size = umin(len, bp->max_tx_length);
-			entry = macb_tx_ring_wrap(bp, tx_head);
-			tx_skb = &queue->tx_skb[entry];
+			tx_skb = macb_tx_skb(queue, tx_head);

 			mapping = skb_frag_dma_map(&bp->pdev->dev, frag,
 						   offset, size, DMA_TO_DEVICE);
@@ -2084,9 +2082,8 @@ static unsigned int macb_tx_map(struct macb *bp,
 	 * to set the end of TX queue
 	 */
 	i = tx_head;
-	entry = macb_tx_ring_wrap(bp, i);
 	ctrl = MACB_BIT(TX_USED);
-	desc = macb_tx_desc(queue, entry);
+	desc = macb_tx_desc(queue, i);
 	desc->ctrl = ctrl;

 	if (lso_ctrl) {
@@ -2106,16 +2103,15 @@ static unsigned int macb_tx_map(struct macb *bp,

 	do {
 		i--;
-		entry = macb_tx_ring_wrap(bp, i);
-		tx_skb = &queue->tx_skb[entry];
-		desc = macb_tx_desc(queue, entry);
+		tx_skb = macb_tx_skb(queue, i);
+		desc = macb_tx_desc(queue, i);

 		ctrl = (u32)tx_skb->size;
 		if (eof) {
 			ctrl |= MACB_BIT(TX_LAST);
 			eof = 0;
 		}
-		if (unlikely(entry == (bp->tx_ring_size - 1)))
+		if (unlikely(macb_tx_ring_wrap(bp, i) == bp->tx_ring_size - 1))
 			ctrl |= MACB_BIT(TX_WRAP);

 		/* First descriptor is header descriptor */

-- 
2.51.0