This one is not that big, but is widely used: saves 1200 bytes 
from net/ipv4/built-in.o

add/remove: 1/0 grow/shrink: 1/12 up/down: 97/-1300 (-1203)
function                                     old     new   delta
inet_twsk_put                                  -      87     +87
__inet_lookup_listener                       274     284     +10
tcp_sacktag_write_queue                     2255    2254      -1
tcp_time_wait                                482     411     -71
__inet_check_established                     796     722     -74
tcp_v4_err                                   973     898     -75
__inet_twsk_kill                             230     154     -76
inet_twsk_deschedule                         180     103     -77
tcp_v4_do_rcv                                462     384     -78
inet_hash_connect                            686     607     -79
inet_twdr_do_twkill_work                     236     150     -86
inet_twdr_twcal_tick                         395     307     -88
tcp_v4_rcv                                  1744    1480    -264
tcp_timewait_state_process                   975     644    -331

Export it for ipv6 module.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---
 include/net/inet_timewait_sock.h |   14 +-------------
 net/ipv4/inet_timewait_sock.c    |   15 +++++++++++++++
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
index abaff05..67e9250 100644
--- a/include/net/inet_timewait_sock.h
+++ b/include/net/inet_timewait_sock.h
@@ -193,19 +193,7 @@ static inline __be32 inet_rcv_saddr(const struct sock *sk)
 		inet_sk(sk)->rcv_saddr : inet_twsk(sk)->tw_rcv_saddr;
 }
 
-static inline void inet_twsk_put(struct inet_timewait_sock *tw)
-{
-	if (atomic_dec_and_test(&tw->tw_refcnt)) {
-		struct module *owner = tw->tw_prot->owner;
-		twsk_destructor((struct sock *)tw);
-#ifdef SOCK_REFCNT_DEBUG
-		printk(KERN_DEBUG "%s timewait_sock %p released\n",
-		       tw->tw_prot->name, tw);
-#endif
-		kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw);
-		module_put(owner);
-	}
-}
+extern void inet_twsk_put(struct inet_timewait_sock *tw);
 
 extern struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,
 						  const int state);
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index d43e787..1b7db42 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -48,6 +48,21 @@ static void __inet_twsk_kill(struct inet_timewait_sock *tw,
 	inet_twsk_put(tw);
 }
 
+void inet_twsk_put(struct inet_timewait_sock *tw)
+{
+	if (atomic_dec_and_test(&tw->tw_refcnt)) {
+		struct module *owner = tw->tw_prot->owner;
+		twsk_destructor((struct sock *)tw);
+#ifdef SOCK_REFCNT_DEBUG
+		printk(KERN_DEBUG "%s timewait_sock %p released\n",
+		       tw->tw_prot->name, tw);
+#endif
+		kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw);
+		module_put(owner);
+	}
+}
+EXPORT_SYMBOL_GPL(inet_twsk_put);
+
 /*
  * Enter the time wait state. This is called with locally disabled BH.
  * Essentially we whip up a timewait bucket, copy the relevant info into it
-- 
1.5.3.4