[IPV6]: Some cleanups in include/net/ipv6.h

1) struct ip6_flowlabel : moves 'users' field to avoid two 32bits
   holes for 64bit arches. Shrinks by 8 bytes sizeof(struct
   ip6_flowlabel)

2) ipv6_addr_cmp() and ipv6_addr_copy() dont need (void *) casts :
   Compiler might take into account natural alignement of in6_addr
   structs to emit better code for memcpy()/memcmp() Casts to (void *)
   force byte accesses.

3) ipv6_addr_prefix() optimization :

Better to clear whole struct, as compiler can emit better code for
memset(addr, 0, 16) (2 stores on x86_64), and avoid some conditional
branches.

# size vmlinux.after vmlinux.before
   text    data     bss     dec     hex filename
5262262  647612  557432 6467306  62aeea vmlinux.after
5262550  647612  557432 6467594  62b00a vmlinux.before

thats 288 bytes saved.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 8 deletions

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 2ce3941d8993..4fa5dfe886c4 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -204,9 +204,9 @@ struct ip6_flowlabel
 {
         struct ip6_flowlabel    *next;
         __be32                  label;
+        atomic_t                users;
         struct in6_addr         dst;
         struct ipv6_txoptions   *opt;
-        atomic_t                users;
         unsigned long           linger;
         u8                      share;
         u32                     owner;
@@ -291,7 +291,7 @@ static inline int ipv6_addr_src_scope(const struct in6_addr *addr)
 
 static inline int ipv6_addr_cmp(const struct in6_addr *a1, const struct in6_addr *a2)
 {
-        return memcmp((const void *) a1, (const void *) a2, sizeof(struct in6_addr));
+        return memcmp(a1, a2, sizeof(struct in6_addr));
 }
 
 static inline int
@@ -308,7 +308,7 @@ ipv6_masked_addr_cmp(const struct in6_addr *a1, const struct in6_addr *m,
 
 static inline void ipv6_addr_copy(struct in6_addr *a1, const struct in6_addr *a2)
 {
-        memcpy((void *) a1, (const void *) a2, sizeof(struct in6_addr));
+        memcpy(a1, a2, sizeof(struct in6_addr));
 }
 
 static inline void ipv6_addr_prefix(struct in6_addr *pfx, 
@@ -319,13 +319,10 @@ static inline void ipv6_addr_prefix(struct in6_addr *pfx,
         int o = plen >> 3,
             b = plen & 0x7;
 
+        memset(pfx->s6_addr, 0, sizeof(pfx->s6_addr));
         memcpy(pfx->s6_addr, addr, o);
-        if (b != 0) {
+        if (b != 0)
                 pfx->s6_addr[o] = addr->s6_addr[o] & (0xff00 >> b);
-                o++;
-        }
-        if (o < 16)
-                memset(pfx->s6_addr + o, 0, 16 - o);
 }
 
 static inline void ipv6_addr_set(struct in6_addr *addr,