[SK_BUFF]: Introduce skb_copy_from_linear_data{_offset}

To clearly state the intent of copying from linear sk_buffs, _offset being a
overly long variant but interesting for the sake of saving some bytes.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/drivers/net/hamradio/dmascc.c b/drivers/net/hamradio/dmascc.c
index 0fbb414..3be8c50 100644
--- a/drivers/net/hamradio/dmascc.c
+++ b/drivers/net/hamradio/dmascc.c
@@ -930,7 +930,7 @@
 
 	/* Transfer data to DMA buffer */
 	i = priv->tx_head;
-	memcpy(priv->tx_buf[i], skb->data + 1, skb->len - 1);
+	skb_copy_from_linear_data_offset(skb, 1, priv->tx_buf[i], skb->len - 1);
 	priv->tx_len[i] = skb->len - 1;
 
 	/* Clear interrupts while we touch our circular buffers */
diff --git a/drivers/net/hamradio/hdlcdrv.c b/drivers/net/hamradio/hdlcdrv.c
index f5a17ad..b33adc6 100644
--- a/drivers/net/hamradio/hdlcdrv.c
+++ b/drivers/net/hamradio/hdlcdrv.c
@@ -317,7 +317,9 @@
 				dev_kfree_skb_irq(skb);
 				break;
 			}
-			memcpy(s->hdlctx.buffer, skb->data+1, pkt_len);
+			skb_copy_from_linear_data_offset(skb, 1,
+							 s->hdlctx.buffer,
+							 pkt_len);
 			dev_kfree_skb_irq(skb);
 			s->hdlctx.bp = s->hdlctx.buffer;
 			append_crc_ccitt(s->hdlctx.buffer, pkt_len);
diff --git a/drivers/net/hamradio/yam.c b/drivers/net/hamradio/yam.c
index ee3ea4f..ac2d6dd 100644
--- a/drivers/net/hamradio/yam.c
+++ b/drivers/net/hamradio/yam.c
@@ -638,7 +638,9 @@
         			dev_kfree_skb_any(skb);
 				break;
 			}
-			memcpy(yp->tx_buf, skb->data + 1, yp->tx_len);
+			skb_copy_from_linear_data_offset(skb->data, 1,
+							 yp->tx_buf,
+							 yp->tx_len);
 			dev_kfree_skb_any(skb);
 			yp->tx_count = 0;
 			yp->tx_crcl = 0x21;