[IPV6] NDISC: Save space for ndisc_options{}.

Pointed out by Krishna Kumar <kumarkr@us.ibm.com>.

Also, size of structure is now adjusted automatically.
Signed-off-by: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>

include/net/ndisc.h

@@ -15,11 +15,15 @@
  *	ndisc options
  */
 
-#define ND_OPT_SOURCE_LL_ADDR		1
-#define ND_OPT_TARGET_LL_ADDR		2
-#define ND_OPT_PREFIX_INFO		3
-#define ND_OPT_REDIRECT_HDR		4
-#define ND_OPT_MTU			5
+enum {
+	__ND_OPT_PREFIX_INFO_END = 0,
+	ND_OPT_SOURCE_LL_ADDR = 1,	/* RFC2461 */
+	ND_OPT_TARGET_LL_ADDR = 2,	/* RFC2461 */
+	ND_OPT_PREFIX_INFO = 3,		/* RFC2461 */
+	ND_OPT_REDIRECT_HDR = 4,	/* RFC2461 */
+	ND_OPT_MTU = 5,			/* RFC2461 */
+	__ND_OPT_MAX
+};
 
 #define MAX_RTR_SOLICITATION_DELAY	HZ
 

net/ipv6/ndisc.c

@@ -156,14 +156,13 @@ struct neigh_table nd_tbl = {
 
 /* ND options */
 struct ndisc_options {
-	struct nd_opt_hdr *nd_opt_array[7];
-	struct nd_opt_hdr *nd_opt_piend;
+	struct nd_opt_hdr *nd_opt_array[__ND_OPT_MAX];
 };
 
 #define nd_opts_src_lladdr	nd_opt_array[ND_OPT_SOURCE_LL_ADDR]
 #define nd_opts_tgt_lladdr	nd_opt_array[ND_OPT_TARGET_LL_ADDR]
 #define nd_opts_pi		nd_opt_array[ND_OPT_PREFIX_INFO]
-#define nd_opts_pi_end		nd_opt_piend
+#define nd_opts_pi_end		nd_opt_array[__ND_OPT_PREFIX_INFO_END]
 #define nd_opts_rh		nd_opt_array[ND_OPT_REDIRECT_HDR]
 #define nd_opts_mtu		nd_opt_array[ND_OPT_MTU]