net: use symbolic values for ndo_start_xmit() return codes

Convert magic values 1 and -1 to NETDEV_TX_BUSY and NETDEV_TX_LOCKED respectively.

0 (NETDEV_TX_OK) is not changed to keep the noise down, except in very few cases
where its in direct proximity to one of the other values.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wan/dlci.c

@@ -205,15 +205,15 @@ static int dlci_transmit(struct sk_buff *skb, struct net_device *dev)
 	{
 		case DLCI_RET_OK:
 			dev->stats.tx_packets++;
-			ret = 0;
+			ret = NETDEV_TX_OK;
 			break;
 			case DLCI_RET_ERR:
 			dev->stats.tx_errors++;
-			ret = 0;
+			ret = NETDEV_TX_OK;
 			break;
 			case DLCI_RET_DROP:
 			dev->stats.tx_dropped++;
-			ret = 1;
+			ret = NETDEV_TX_BUSY;
 			break;
 	}
 	/* Alan Cox recommends always returning 0, and always freeing the packet */

drivers/net/wan/sbni.c

@@ -469,7 +469,7 @@ sbni_start_xmit( struct sk_buff  *skb,  struct net_device  *dev )
 		}
 	}
 
-	return  1;
+	return NETDEV_TX_BUSY;
 }
 
 #else	/* CONFIG_SBNI_MULTILINE */

drivers/net/wan/wanxl.c

@@ -283,7 +283,7 @@ static int wanxl_xmit(struct sk_buff *skb, struct net_device *dev)
 #endif
 		netif_stop_queue(dev);
 		spin_unlock_irq(&port->lock);
-		return 1;       /* request packet to be queued */
+		return NETDEV_TX_BUSY;       /* request packet to be queued */
 	}
 
 #ifdef DEBUG_PKT