ndisc: add __ndisc_fill_addr_option function

This patch adds __ndisc_fill_addr_option as low-level function for
ndisc_fill_addr_option which doesn't depend on net_device parameter.

Cc: David S. Miller <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: Alexander Aring <aar@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ndisc.c

@@ -150,11 +150,10 @@ struct neigh_table nd_tbl = {
 };
 EXPORT_SYMBOL_GPL(nd_tbl);
 
-static void ndisc_fill_addr_option(struct sk_buff *skb, int type, void *data)
+static void __ndisc_fill_addr_option(struct sk_buff *skb, int type, void *data,
+				     int data_len, int pad)
 {
-	int pad   = ndisc_addr_option_pad(skb->dev->type);
-	int data_len = skb->dev->addr_len;
-	int space = ndisc_opt_addr_space(skb->dev);
+	int space = __ndisc_opt_addr_space(data_len, pad);
 	u8 *opt = skb_put(skb, space);
 
 	opt[0] = type;
@@ -172,6 +171,13 @@ static void ndisc_fill_addr_option(struct sk_buff *skb, int type, void *data)
 		memset(opt, 0, space);
 }
 
+static inline void ndisc_fill_addr_option(struct sk_buff *skb, int type,
+					  void *data)
+{
+	__ndisc_fill_addr_option(skb, type, data, skb->dev->addr_len,
+				 ndisc_addr_option_pad(skb->dev->type));
+}
+
 static struct nd_opt_hdr *ndisc_next_option(struct nd_opt_hdr *cur,
 					    struct nd_opt_hdr *end)
 {