[PATCH] USB: ethernet "gadget", rx overflows happen

I tightened up rx overflow logic in the net2280 driver
a while back, and it broke MTU size packets in this
driver (host pads them out).  This patch accomodates it
by allocating a slightly larger buffer (almost 3*512).

drivers/usb/gadget/ether.c

@@ -76,6 +76,7 @@ static const char data_name [] = "CDC Ethernet Data";
 
 #define MIN_PACKET	sizeof(struct ethhdr)
 #define	MAX_PACKET	ETH_DATA_LEN	/* biggest packet we'll rx/tx */
+#define RX_EXTRA	20		/* guard against rx overflows */
 
 /* FIXME allow high speed jumbograms */
 
@@ -1226,7 +1227,7 @@ rx_submit (struct eth_dev *dev, struct usb_request *req, int gfp_flags)
 	int			retval = 0;
 	size_t			size;
 
-	size = (sizeof (struct ethhdr) + dev->net.mtu);
+	size = (sizeof (struct ethhdr) + dev->net.mtu + RX_EXTRA);
 
 	if ((skb = alloc_skb (size, gfp_flags)) == 0) {
 		DEBUG (dev, "no rx skb\n");