net: systemport: fix bcm_sysport_insert_tsb()

[ Upstream commit e87474a6 ]

Similar to commit bc23333b ("net:
bcmgenet: fix bcmgenet_put_tx_csum()"), we need to return the skb
pointer in case we had to reallocate the SKB headroom.

Fixes: 80105bef ("net: systemport: add Broadcom SYSTEMPORT Ethernet MAC driver")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/broadcom/bcmsysport.c

@@ -757,7 +757,8 @@ static irqreturn_t bcm_sysport_tx_isr(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static int bcm_sysport_insert_tsb(struct sk_buff *skb, struct net_device *dev)
+static struct sk_buff *bcm_sysport_insert_tsb(struct sk_buff *skb,
+					      struct net_device *dev)
 {
 	struct sk_buff *nskb;
 	struct bcm_tsb *tsb;
@@ -773,7 +774,7 @@ static int bcm_sysport_insert_tsb(struct sk_buff *skb, struct net_device *dev)
 		if (!nskb) {
 			dev->stats.tx_errors++;
 			dev->stats.tx_dropped++;
-			return -ENOMEM;
+			return NULL;
 		}
 		skb = nskb;
 	}
@@ -792,7 +793,7 @@ static int bcm_sysport_insert_tsb(struct sk_buff *skb, struct net_device *dev)
 			ip_proto = ipv6_hdr(skb)->nexthdr;
 			break;
 		default:
-			return 0;
+			return skb;
 		}
 
 		/* Get the checksum offset and the L4 (transport) offset */
@@ -810,7 +811,7 @@ static int bcm_sysport_insert_tsb(struct sk_buff *skb, struct net_device *dev)
 		tsb->l4_ptr_dest_map = csum_info;
 	}
 
-	return 0;
+	return skb;
 }
 
 static netdev_tx_t bcm_sysport_xmit(struct sk_buff *skb,
@@ -844,8 +845,8 @@ static netdev_tx_t bcm_sysport_xmit(struct sk_buff *skb,
 
 	/* Insert TSB and checksum infos */
 	if (priv->tsb_en) {
-		ret = bcm_sysport_insert_tsb(skb, dev);
-		if (ret) {
+		skb = bcm_sysport_insert_tsb(skb, dev);
+		if (!skb) {
 			ret = NETDEV_TX_OK;
 			goto out;
 		}