nefilter: eache: reduce struct size from 32 to 24 byte

Only "cache" needs to use ulong (its used with set_bit()), missed can use
u16.  Also add build-time assertion to ensure event bits fit.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_conntrack_ecache.h

@@ -20,11 +20,11 @@ enum nf_ct_ecache_state {
 
 struct nf_conntrack_ecache {
 	unsigned long cache;		/* bitops want long */
-	unsigned long missed;		/* missed events */
+	u16 missed;			/* missed events */
 	u16 ctmask;			/* bitmask of ct events to be delivered */
 	u16 expmask;			/* bitmask of expect events to be delivered */
+	enum nf_ct_ecache_state state:8;/* ecache state */
 	u32 portid;			/* netlink portid of destroyer */
-	enum nf_ct_ecache_state state;	/* ecache state */
 };
 
 static inline struct nf_conntrack_ecache *

include/uapi/linux/netfilter/nf_conntrack_common.h

@@ -119,6 +119,9 @@ enum ip_conntrack_events {
 	IPCT_NATSEQADJ = IPCT_SEQADJ,
 	IPCT_SECMARK,		/* new security mark has been set */
 	IPCT_LABEL,		/* new connlabel has been set */
+#ifdef __KERNEL__
+	__IPCT_MAX
+#endif
 };
 
 enum ip_conntrack_expect_events {

net/netfilter/nf_conntrack_ecache.c

@@ -420,6 +420,9 @@ int nf_conntrack_ecache_init(void)
 	int ret = nf_ct_extend_register(&event_extend);
 	if (ret < 0)
 		pr_err("nf_ct_event: Unable to register event extension.\n");
+
+	BUILD_BUG_ON(__IPCT_MAX >= 16);	/* ctmask, missed use u16 */
+
 	return ret;
 }