kernel: 5.10: simplify logic in packet mangling patch

I had quite a hard time to understand what the change to net/core/dev.c
is supposed to do.

Simplify the change by returning NETDEV_TX_OK in case a eth_mangle_tx
callback was set but returned NULL instead of setting the return value
in the else branch.

Signed-off-by: Mathias Kresin <[email protected]>

target/linux/generic/hack-5.10/721-net-add-packet-mangeling.patch

@@ -105,33 +105,18 @@ Signed-off-by: Felix Fietkau <[email protected]>
  	help
 --- a/net/core/dev.c
 +++ b/net/core/dev.c
-@@ -3638,11 +3638,21 @@ static int xmit_one(struct sk_buff *skb,
+@@ -3638,6 +3638,11 @@ static int xmit_one(struct sk_buff *skb,
  	if (dev_nit_active(dev))
  		dev_queue_xmit_nit(skb, dev);
  
--	len = skb->len;
--	PRANDOM_ADD_NOISE(skb, dev, txq, len + jiffies);
--	trace_net_dev_start_xmit(skb, dev);
--	rc = netdev_start_xmit(skb, dev, txq, more);
--	trace_net_dev_xmit(skb, rc, dev, len);
 +#ifdef CONFIG_ETHERNET_PACKET_MANGLE
-+	if (!dev->eth_mangle_tx ||
-+	    (skb = dev->eth_mangle_tx(dev, skb)) != NULL)
-+#else
-+	if (1)
++	if (dev->eth_mangle_tx && !(skb = dev->eth_mangle_tx(dev, skb)))
++		return NETDEV_TX_OK;
 +#endif
-+	{
-+		len = skb->len;
-+		PRANDOM_ADD_NOISE(skb, dev, txq, len + jiffies);
-+		trace_net_dev_start_xmit(skb, dev);
-+		rc = netdev_start_xmit(skb, dev, txq, more);
-+		trace_net_dev_xmit(skb, rc, dev, len);
-+	} else {
-+		rc = NETDEV_TX_OK;
-+	}
- 
- 	return rc;
- }
++
+ 	len = skb->len;
+ 	PRANDOM_ADD_NOISE(skb, dev, txq, len + jiffies);
+ 	trace_net_dev_start_xmit(skb, dev);
 --- a/net/core/skbuff.c
 +++ b/net/core/skbuff.c
 @@ -60,6 +60,7 @@