[IPV6]: Use bitfields for hop_limit and mcast_hops.

Save some bits for future extensions.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 9b59e37afad94f466b7348c3b2eb2dfb231696e4..87ae4e389ce1eee4d132a0311b446c9da597474a 100644 (file)
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -274,8 +274,29 @@ struct ipv6_pinfo {
 
        __be32                  flow_label;
        __u32                   frag_size;
-       __s16                   hop_limit;
-       __s16                   mcast_hops;
+
+       /*
+        * Packed in 16bits.
+        * Omit one shift by by putting the signed field at MSB.
+        */
+#if defined(__BIG_ENDIAN_BITFIELD)
+       __s16                   hop_limit:9;
+       __u16                   __unused_1:7;
+#else
+       __u16                   __unused_1:7;
+       __s16                   hop_limit:9;
+#endif
+
+#if defined(__BIG_ENDIAN_BITFIELD)
+       /* Packed in 16bits. */
+       __s16                   mcast_hops:9;
+       __u16                   __unused_2:6,
+                               mc_loop:1;
+#else
+       __u16                   mc_loop:1,
+                               __unused_2:6;
+       __s16                   mcast_hops:9;
+#endif
        int                     mcast_oif;
 
        /* pktoption flags */
@@ -298,8 +319,7 @@ struct ipv6_pinfo {
        } rxopt;
 
        /* sockopt flags */
-       __u8                    mc_loop:1,
-                               recverr:1,
+       __u8                    recverr:1,
                                sndflow:1,
                                pmtudisc:2,
                                ipv6only:1;