netdev - [PATCH v2 net] net: microchip: sparx5: correctly free skb in xmit

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Date:   Tue, 29 Nov 2022 16:26:35 +0100
From:   Casper Andersson <casper.casan@...il.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Lars Povlsen <lars.povlsen@...rochip.com>,
        Steen Hegelund <Steen.Hegelund@...rochip.com>,
        Daniel Machon <daniel.machon@...rochip.com>,
        UNGLinuxDriver@...rochip.com,
        Richard Cochran <richardcochran@...il.com>,
        netdev@...r.kernel.org,
        Horatiu Vultur <horatiu.vultur@...rochip.com>
Subject: [PATCH v2 net] net: microchip: sparx5: correctly free skb in xmit

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.

sparx5_fdma_xmit and sparx5_inject returns error code, where -EBUSY
indicates TX_BUSY and any other error code indicates dropped.

Fixes: f3cad2611a77 ("net: sparx5: add hostmode with phylink support")

Signed-off-by: Casper Andersson <casper.casan@...il.com>
---
 .../ethernet/microchip/sparx5/sparx5_fdma.c   |  2 +-
 .../ethernet/microchip/sparx5/sparx5_packet.c | 41 +++++++++++--------
 2 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c b/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
index 66360c8c5a38..141897dfe388 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
@@ -317,7 +317,7 @@ int sparx5_fdma_xmit(struct sparx5 *sparx5, u32 *ifh, struct sk_buff *skb)
 	next_dcb_hw = sparx5_fdma_next_dcb(tx, tx->curr_entry);
 	db_hw = &next_dcb_hw->db[0];
 	if (!(db_hw->status & FDMA_DCB_STATUS_DONE))
-		tx->dropped++;
+		return -EINVAL;
 	db = list_first_entry(&tx->db_list, struct sparx5_db, list);
 	list_move_tail(&db->list, &tx->db_list);
 	next_dcb_hw->nextptr = FDMA_DCB_INVALID_DATA;
diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c b/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c
index 83c16ca5b30f..6db6ac6a3bbc 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c
@@ -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) < 0)
+			return NETDEV_TX_BUSY;
 
 		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 +249,31 @@ 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 == -EBUSY)
+		goto busy;
+	if (ret < 0)
+		goto drop;
 
-		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++;
+	sparx5->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++;
+	sparx5->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