[NET]: Store skb->timestamp as offset to a base timestamp

Reduces skb size by 8 bytes on 64-bit.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index eed9090..32ef797 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -332,8 +332,12 @@
 		put_cmsg(msg, SOL_HCI, HCI_CMSG_DIR, sizeof(incoming), &incoming);
 	}
 
-	if (mask & HCI_CMSG_TSTAMP)
-		put_cmsg(msg, SOL_HCI, HCI_CMSG_TSTAMP, sizeof(skb->stamp), &skb->stamp);
+	if (mask & HCI_CMSG_TSTAMP) {
+		struct timeval tv;
+
+		skb_get_timestamp(skb, &tv);
+		put_cmsg(msg, SOL_HCI, HCI_CMSG_TSTAMP, sizeof(tv), &tv);
+	}
 }
  
 static int hci_sock_recvmsg(struct kiocb *iocb, struct socket *sock,