[PATCH net] net: microchip: sparx5: correctly free skb in xmit

[Casper Andersson <casper.casan@gmail.com>]

consume_skb on transmitted, kfree_skb on dropped, do not free on TX_BUSY.

Previously the xmit function could return -EBUSY without freeing, which
supposedly is interpreted as a drop. And was using kfree on successfully
transmitted packets.
https://lore.kernel.org/netdev/20220920072948.33c25dd2@kernel.org/t/#mdb821eb507a207dd5e27683239ffa7ec7199421a

Fixes: 10615907e9b5 ("net: sparx5: switchdev: adding frame DMA functionality")
Signed-off-by: Casper Andersson <casper.casan@gmail.com>
---
I am not entirely sure about the following construct which is present in
both sparx5 and lan966x drivers and returns before consuming the skb. Is
there any reason it does not free the skb?

if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP &&
    SPARX5_SKB_CB(skb)->rew_op == IFH_REW_OP_TWO_STEP_PTP)
	return NETDEV_TX_OK;




 .../ethernet/microchip/sparx5/sparx5_fdma.c   |  2 +-
 .../ethernet/microchip/sparx5/sparx5_main.h   |  2 +-
 .../ethernet/microchip/sparx5/sparx5_packet.c | 47 ++++++++++---------
 3 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c b/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
index 66360c8c5a38..302e7ff55585 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
@@ -306,7 +306,7 @@ static struct sparx5_tx_dcb_hw *sparx5_fdma_next_dcb(struct sparx5_tx *tx,
 	return next_dcb;
 }
 
-int sparx5_fdma_xmit(struct sparx5 *sparx5, u32 *ifh, struct sk_buff *skb)
+netdev_tx_t sparx5_fdma_xmit(struct sparx5 *sparx5, u32 *ifh, struct sk_buff *skb)
 {
 	struct sparx5_tx_dcb_hw *next_dcb_hw;
 	struct sparx5_tx *tx = &sparx5->tx;
diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_main.h b/drivers/net/ethernet/microchip/sparx5/sparx5_main.h
index 7a83222caa73..34b8d11f76df 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_main.h
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_main.h
@@ -312,7 +312,7 @@ void sparx5_port_inj_timer_setup(struct sparx5_port *port);
 /* sparx5_fdma.c */
 int sparx5_fdma_start(struct sparx5 *sparx5);
 int sparx5_fdma_stop(struct sparx5 *sparx5);
-int sparx5_fdma_xmit(struct sparx5 *sparx5, u32 *ifh, struct sk_buff *skb);
+netdev_tx_t sparx5_fdma_xmit(struct sparx5 *sparx5, u32 *ifh, struct sk_buff *skb);
 irqreturn_t sparx5_fdma_handler(int irq, void *args);
 
 /* sparx5_mactable.c */
diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c b/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c
index 83c16ca5b30f..6fc1c1e410f6 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c
@@ -159,10 +159,10 @@ static void sparx5_xtr_grp(struct sparx5 *sparx5, u8 grp, bool byte_swap)
 	netif_rx(skb);
 }
 
-static int sparx5_inject(struct sparx5 *sparx5,
-			 u32 *ifh,
-			 struct sk_buff *skb,
-			 struct net_device *ndev)
+static netdev_tx_t sparx5_inject(struct sparx5 *sparx5,
+				 u32 *ifh,
+				 struct sk_buff *skb,
+				 struct net_device *ndev)
 {
 	int grp = INJ_QUEUE;
 	u32 val, w, count;
@@ -172,7 +172,7 @@ static int sparx5_inject(struct sparx5 *sparx5,
 	if (!(QS_INJ_STATUS_FIFO_RDY_GET(val) & BIT(grp))) {
 		pr_err_ratelimited("Injection: Queue not ready: 0x%lx\n",
 				   QS_INJ_STATUS_FIFO_RDY_GET(val));
-		return -EBUSY;
+		return NETDEV_TX_BUSY;
 	}
 
 	/* Indicate SOF */
@@ -234,9 +234,8 @@ netdev_tx_t sparx5_port_xmit_impl(struct sk_buff *skb, struct net_device *dev)
 	sparx5_set_port_ifh(ifh, port->portno);
 
 	if (sparx5->ptp && skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) {
-		ret = sparx5_ptp_txtstamp_request(port, skb);
-		if (ret)
-			return ret;
+		if (sparx5_ptp_txtstamp_request(port, skb))
+			goto drop;
 
 		sparx5_set_port_ifh_rew_op(ifh, SPARX5_SKB_CB(skb)->rew_op);
 		sparx5_set_port_ifh_pdu_type(ifh, SPARX5_SKB_CB(skb)->pdu_type);
@@ -250,23 +249,27 @@ netdev_tx_t sparx5_port_xmit_impl(struct sk_buff *skb, struct net_device *dev)
 	else
 		ret = sparx5_inject(sparx5, ifh, skb, dev);
 
-	if (ret == NETDEV_TX_OK) {
-		stats->tx_bytes += skb->len;
-		stats->tx_packets++;
+	if (ret == NETDEV_TX_BUSY)
+		goto busy;
 
-		if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP &&
-		    SPARX5_SKB_CB(skb)->rew_op == IFH_REW_OP_TWO_STEP_PTP)
-			return ret;
+	stats->tx_bytes += skb->len;
+	stats->tx_packets++;
 
-		dev_kfree_skb_any(skb);
-	} else {
-		stats->tx_dropped++;
+	if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP &&
+	    SPARX5_SKB_CB(skb)->rew_op == IFH_REW_OP_TWO_STEP_PTP)
+		return NETDEV_TX_OK;
 
-		if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP &&
-		    SPARX5_SKB_CB(skb)->rew_op == IFH_REW_OP_TWO_STEP_PTP)
-			sparx5_ptp_txtstamp_release(port, skb);
-	}
-	return ret;
+	dev_consume_skb_any(skb);
+	return NETDEV_TX_OK;
+drop:
+	stats->tx_dropped++;
+	dev_kfree_skb_any(skb);
+	return NETDEV_TX_OK;
+busy:
+	if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP &&
+	    SPARX5_SKB_CB(skb)->rew_op == IFH_REW_OP_TWO_STEP_PTP)
+		sparx5_ptp_txtstamp_release(port, skb);
+	return NETDEV_TX_BUSY;
 }
 
 static enum hrtimer_restart sparx5_injection_timeout(struct hrtimer *tmr)
-- 
2.34.1