networking: introduce and use skb_put_data()

A common pattern with skb_put() is to just want to memcpy()
some data into the new space, introduce skb_put_data() for
this.

An spatch similar to the one for skb_put_zero() converts many
of the places using it:

    @@
    identifier p, p2;
    expression len, skb, data;
    type t, t2;
    @@
    (
    -p = skb_put(skb, len);
    +p = skb_put_data(skb, data, len);
    |
    -p = (t)skb_put(skb, len);
    +p = skb_put_data(skb, data, len);
    )
    (
    p2 = (t2)p;
    -memcpy(p2, data, len);
    |
    -memcpy(p, data, len);
    )

    @@
    type t, t2;
    identifier p, p2;
    expression skb, data;
    @@
    t *p;
    ...
    (
    -p = skb_put(skb, sizeof(t));
    +p = skb_put_data(skb, data, sizeof(t));
    |
    -p = (t *)skb_put(skb, sizeof(t));
    +p = skb_put_data(skb, data, sizeof(t));
    )
    (
    p2 = (t2)p;
    -memcpy(p2, data, sizeof(*p));
    |
    -memcpy(p, data, sizeof(*p));
    )

    @@
    expression skb, len, data;
    @@
    -memcpy(skb_put(skb, len), data, len);
    +skb_put_data(skb, data, len);

(again, manually post-processed to retain some comments)

Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/silan/sc92031.c

@@ -795,12 +795,12 @@ static void _sc92031_rx_tasklet(struct net_device *dev)
 		}
 
 		if ((rx_ring_offset + pkt_size) > RX_BUF_LEN) {
-			memcpy(skb_put(skb, RX_BUF_LEN - rx_ring_offset),
-				rx_ring + rx_ring_offset, RX_BUF_LEN - rx_ring_offset);
-			memcpy(skb_put(skb, pkt_size - (RX_BUF_LEN - rx_ring_offset)),
-				rx_ring, pkt_size - (RX_BUF_LEN - rx_ring_offset));
+			skb_put_data(skb, rx_ring + rx_ring_offset,
+				     RX_BUF_LEN - rx_ring_offset);
+			skb_put_data(skb, rx_ring,
+				     pkt_size - (RX_BUF_LEN - rx_ring_offset));
 		} else {
-			memcpy(skb_put(skb, pkt_size), rx_ring + rx_ring_offset, pkt_size);
+			skb_put_data(skb, rx_ring + rx_ring_offset, pkt_size);
 		}
 
 		skb->protocol = eth_type_trans(skb, dev);