net: fec: ensure fec_enet_free_buffers() properly cleans the rings

Ensure that we do not double-free any allocations, and that any transmit
skbuffs are properly freed when we clean up the rings.
Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec_main.c

@@ -2079,8 +2079,13 @@ static void fec_enet_free_buffers(struct net_device *ndev)
 	}
 
 	bdp = fep->tx_bd_base;
-	for (i = 0; i < fep->tx_ring_size; i++)
+	for (i = 0; i < fep->tx_ring_size; i++) {
 		kfree(fep->tx_bounce[i]);
+		fep->tx_bounce[i] = NULL;
+		skb = fep->tx_skbuff[i];
+		fep->tx_skbuff[i] = NULL;
+		dev_kfree_skb(skb);
+	}
 }
 
 static int fec_enet_alloc_buffers(struct net_device *ndev)