Patchwork [net-next,1/1] sip: introduce nf_nat_sip_hooks

login
register
mail settings
Submitter holger@eitzenberger.org
Date Sept. 30, 2013, 1:51 p.m.
Message ID <20130930135559.077109518@eitzenberger.org>
Download mbox | patch
Permalink /patch/279157/
State Superseded
Headers show

Comments

holger@eitzenberger.org - Sept. 30, 2013, 1:51 p.m.
There are currently seven different NAT hooks used in both
nf_conntrack_sip and nf_nat_sip, each of the hooks is exported in
nf_conntrack_sip, then set from the nf_nat_sip NAT helper.

And because each of them is exported there is quite some overhead
introduced due of this.

By introducing nf_nat_sip_hooks I am able to reduce both text/data
somewhat.  For nf_conntrack_sip e. g. I get

        text             data              bss              dec
old    15243             5256               32            20531
new    15010             5192               32            20234

Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>


--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Patrick McHardy - Sept. 30, 2013, 2:03 p.m.
On Mon, Sep 30, 2013 at 03:51:51PM +0200, Holger Eitzenberger wrote:
> There are currently seven different NAT hooks used in both
> nf_conntrack_sip and nf_nat_sip, each of the hooks is exported in
> nf_conntrack_sip, then set from the nf_nat_sip NAT helper.

Thanks Holger, I wanted to do the same for a long time now. It actually
also fixes a minor race condition, when the NAT helper is loaded or
unloaded while a packet is processed the hooks may be invoked only
partially.

Just one request:

> +struct nf_nat_sip_hooks {
> +	unsigned int (* nsh_msg)(struct sk_buff *skb,
> +				 unsigned int protoff,
> +				 unsigned int dataoff,
> +				 const char **dptr,
> +				 unsigned int *datalen);

I really hate unpronouncable abbrevations, it hurts my eyes and IMO makes
it harder to read the code. Please use something nicer or get rid of the
prefix entirely.

Thanks!
--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
holger@eitzenberger.org - Sept. 30, 2013, 2:49 p.m.
> Thanks Holger, I wanted to do the same for a long time now. It actually
> also fixes a minor race condition, when the NAT helper is loaded or
> unloaded while a packet is processed the hooks may be invoked only
> partially.
> 
> Just one request:
> 
> > +struct nf_nat_sip_hooks {
> > +	unsigned int (* nsh_msg)(struct sk_buff *skb,
> > +				 unsigned int protoff,
> > +				 unsigned int dataoff,
> > +				 const char **dptr,
> > +				 unsigned int *datalen);
> 
> I really hate unpronouncable abbrevations, it hurts my eyes and IMO makes
> it harder to read the code. Please use something nicer or get rid of the
> prefix entirely.

Ok, I'll remove the prefix then.

However, personally I think they help grep'ing a lot, like e. g. the
ndo_ prefix with netdevice ops (still usefull even as a 'cscope'
user).

Also the function names are *shorter* with the patch, as I was able
to remove the nf_nat_ prefix.

 /Holger

--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Patrick McHardy - Sept. 30, 2013, 3:13 p.m.
On Mon, Sep 30, 2013 at 04:49:51PM +0200, Holger Eitzenberger wrote:
> 
> > Thanks Holger, I wanted to do the same for a long time now. It actually
> > also fixes a minor race condition, when the NAT helper is loaded or
> > unloaded while a packet is processed the hooks may be invoked only
> > partially.
> > 
> > Just one request:
> > 
> > > +struct nf_nat_sip_hooks {
> > > +	unsigned int (* nsh_msg)(struct sk_buff *skb,
> > > +				 unsigned int protoff,
> > > +				 unsigned int dataoff,
> > > +				 const char **dptr,
> > > +				 unsigned int *datalen);
> > 
> > I really hate unpronouncable abbrevations, it hurts my eyes and IMO makes
> > it harder to read the code. Please use something nicer or get rid of the
> > prefix entirely.
> 
> Ok, I'll remove the prefix then.
> 
> However, personally I think they help grep'ing a lot, like e. g. the
> ndo_ prefix with netdevice ops (still usefull even as a 'cscope'
> user).
> 
> Also the function names are *shorter* with the patch, as I was able
> to remove the nf_nat_ prefix.

Sure, its really just the unpronouncable thing, it makes it harder to
follow the code in your head. If you really want to keep the prefixes,
why not just use nat_sip_?

Cheers,
Patrick
--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

Index: net-next/net/netfilter/nf_conntrack_sip.c
===================================================================
--- net-next.orig/net/netfilter/nf_conntrack_sip.c
+++ net-next/net/netfilter/nf_conntrack_sip.c
@@ -52,66 +52,8 @@  module_param(sip_direct_media, int, 0600
 MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling "
 				   "endpoints only (default 1)");
 
-unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, unsigned int protoff,
-				unsigned int dataoff, const char **dptr,
-				unsigned int *datalen) __read_mostly;
-EXPORT_SYMBOL_GPL(nf_nat_sip_hook);
-
-void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb, unsigned int protoff,
-				   s16 off) __read_mostly;
-EXPORT_SYMBOL_GPL(nf_nat_sip_seq_adjust_hook);
-
-unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
-				       unsigned int protoff,
-				       unsigned int dataoff,
-				       const char **dptr,
-				       unsigned int *datalen,
-				       struct nf_conntrack_expect *exp,
-				       unsigned int matchoff,
-				       unsigned int matchlen) __read_mostly;
-EXPORT_SYMBOL_GPL(nf_nat_sip_expect_hook);
-
-unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb, unsigned int protoff,
-				     unsigned int dataoff,
-				     const char **dptr,
-				     unsigned int *datalen,
-				     unsigned int sdpoff,
-				     enum sdp_header_types type,
-				     enum sdp_header_types term,
-				     const union nf_inet_addr *addr)
-				     __read_mostly;
-EXPORT_SYMBOL_GPL(nf_nat_sdp_addr_hook);
-
-unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb, unsigned int protoff,
-				     unsigned int dataoff,
-				     const char **dptr,
-				     unsigned int *datalen,
-				     unsigned int matchoff,
-				     unsigned int matchlen,
-				     u_int16_t port) __read_mostly;
-EXPORT_SYMBOL_GPL(nf_nat_sdp_port_hook);
-
-unsigned int (*nf_nat_sdp_session_hook)(struct sk_buff *skb,
-					unsigned int protoff,
-					unsigned int dataoff,
-					const char **dptr,
-					unsigned int *datalen,
-					unsigned int sdpoff,
-					const union nf_inet_addr *addr)
-					__read_mostly;
-EXPORT_SYMBOL_GPL(nf_nat_sdp_session_hook);
-
-unsigned int (*nf_nat_sdp_media_hook)(struct sk_buff *skb, unsigned int protoff,
-				      unsigned int dataoff,
-				      const char **dptr,
-				      unsigned int *datalen,
-				      struct nf_conntrack_expect *rtp_exp,
-				      struct nf_conntrack_expect *rtcp_exp,
-				      unsigned int mediaoff,
-				      unsigned int medialen,
-				      union nf_inet_addr *rtp_addr)
-				      __read_mostly;
-EXPORT_SYMBOL_GPL(nf_nat_sdp_media_hook);
+const struct nf_nat_sip_hooks *nf_nat_sip_hooks;
+EXPORT_SYMBOL_GPL(nf_nat_sip_hooks);
 
 static int string_len(const struct nf_conn *ct, const char *dptr,
 		      const char *limit, int *shift)
@@ -914,8 +856,7 @@  static int set_expected_rtp_rtcp(struct
 	int direct_rtp = 0, skip_expect = 0, ret = NF_DROP;
 	u_int16_t base_port;
 	__be16 rtp_port, rtcp_port;
-	typeof(nf_nat_sdp_port_hook) nf_nat_sdp_port;
-	typeof(nf_nat_sdp_media_hook) nf_nat_sdp_media;
+	const struct nf_nat_sip_hooks *hooks;
 
 	saddr = NULL;
 	if (sip_direct_media) {
@@ -972,10 +913,10 @@  static int set_expected_rtp_rtcp(struct
 	rtcp_port = htons(base_port + 1);
 
 	if (direct_rtp) {
-		nf_nat_sdp_port = rcu_dereference(nf_nat_sdp_port_hook);
-		if (nf_nat_sdp_port &&
-		    !nf_nat_sdp_port(skb, protoff, dataoff, dptr, datalen,
-				     mediaoff, medialen, ntohs(rtp_port)))
+		hooks = rcu_dereference(nf_nat_sip_hooks);
+		if (hooks &&
+		    !hooks->nsh_sdp_port(skb, protoff, dataoff, dptr, datalen,
+					 mediaoff, medialen, ntohs(rtp_port)))
 			goto err1;
 	}
 
@@ -996,11 +937,11 @@  static int set_expected_rtp_rtcp(struct
 	nf_ct_expect_init(rtcp_exp, class, nf_ct_l3num(ct), saddr, daddr,
 			  IPPROTO_UDP, NULL, &rtcp_port);
 
-	nf_nat_sdp_media = rcu_dereference(nf_nat_sdp_media_hook);
-	if (nf_nat_sdp_media && ct->status & IPS_NAT_MASK && !direct_rtp)
-		ret = nf_nat_sdp_media(skb, protoff, dataoff, dptr, datalen,
-				       rtp_exp, rtcp_exp,
-				       mediaoff, medialen, daddr);
+	hooks = rcu_dereference(nf_nat_sip_hooks);
+	if (hooks && ct->status & IPS_NAT_MASK && !direct_rtp)
+		ret = hooks->nsh_sdp_media(skb, protoff, dataoff, dptr,
+					   datalen, rtp_exp, rtcp_exp,
+					   mediaoff, medialen, daddr);
 	else {
 		if (nf_ct_expect_related(rtp_exp) == 0) {
 			if (nf_ct_expect_related(rtcp_exp) != 0)
@@ -1053,13 +994,12 @@  static int process_sdp(struct sk_buff *s
 	unsigned int caddr_len, maddr_len;
 	unsigned int i;
 	union nf_inet_addr caddr, maddr, rtp_addr;
+	const struct nf_nat_sip_hooks *hooks;
 	unsigned int port;
 	const struct sdp_media_type *t;
 	int ret = NF_ACCEPT;
-	typeof(nf_nat_sdp_addr_hook) nf_nat_sdp_addr;
-	typeof(nf_nat_sdp_session_hook) nf_nat_sdp_session;
 
-	nf_nat_sdp_addr = rcu_dereference(nf_nat_sdp_addr_hook);
+	hooks = rcu_dereference(nf_nat_sip_hooks);
 
 	/* Find beginning of session description */
 	if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
@@ -1127,11 +1067,12 @@  static int process_sdp(struct sk_buff *s
 		}
 
 		/* Update media connection address if present */
-		if (maddr_len && nf_nat_sdp_addr && ct->status & IPS_NAT_MASK) {
-			ret = nf_nat_sdp_addr(skb, protoff, dataoff,
-					      dptr, datalen, mediaoff,
-					      SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
-					      &rtp_addr);
+		if (maddr_len && hooks && ct->status & IPS_NAT_MASK) {
+			ret = hooks->nsh_sdp_addr(skb, protoff, dataoff,
+						  dptr, datalen, mediaoff,
+						  SDP_HDR_CONNECTION,
+						  SDP_HDR_MEDIA,
+						  &rtp_addr);
 			if (ret != NF_ACCEPT) {
 				nf_ct_helper_log(skb, ct, "cannot mangle SDP");
 				return ret;
@@ -1141,10 +1082,11 @@  static int process_sdp(struct sk_buff *s
 	}
 
 	/* Update session connection and owner addresses */
-	nf_nat_sdp_session = rcu_dereference(nf_nat_sdp_session_hook);
-	if (nf_nat_sdp_session && ct->status & IPS_NAT_MASK)
-		ret = nf_nat_sdp_session(skb, protoff, dataoff,
-					 dptr, datalen, sdpoff, &rtp_addr);
+	hooks = rcu_dereference(nf_nat_sip_hooks);
+	if (hooks && ct->status & IPS_NAT_MASK)
+		ret = hooks->nsh_sdp_session(skb, protoff, dataoff,
+					     dptr, datalen, sdpoff,
+					     &rtp_addr);
 
 	return ret;
 }
@@ -1244,11 +1186,11 @@  static int process_register_request(stru
 	unsigned int matchoff, matchlen;
 	struct nf_conntrack_expect *exp;
 	union nf_inet_addr *saddr, daddr;
+	const struct nf_nat_sip_hooks *hooks;
 	__be16 port;
 	u8 proto;
 	unsigned int expires = 0;
 	int ret;
-	typeof(nf_nat_sip_expect_hook) nf_nat_sip_expect;
 
 	/* Expected connections can not register again. */
 	if (ct->status & IPS_EXPECTED)
@@ -1311,9 +1253,9 @@  static int process_register_request(stru
 	exp->helper = nfct_help(ct)->helper;
 	exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
 
-	nf_nat_sip_expect = rcu_dereference(nf_nat_sip_expect_hook);
-	if (nf_nat_sip_expect && ct->status & IPS_NAT_MASK)
-		ret = nf_nat_sip_expect(skb, protoff, dataoff, dptr, datalen,
+	hooks = rcu_dereference(nf_nat_sip_hooks);
+	if (hooks && ct->status & IPS_NAT_MASK)
+		ret = hooks->nsh_expect(skb, protoff, dataoff, dptr, datalen,
 					exp, matchoff, matchlen);
 	else {
 		if (nf_ct_expect_related(exp) != 0) {
@@ -1517,7 +1459,7 @@  static int process_sip_msg(struct sk_buf
 			   unsigned int protoff, unsigned int dataoff,
 			   const char **dptr, unsigned int *datalen)
 {
-	typeof(nf_nat_sip_hook) nf_nat_sip;
+	const struct nf_nat_sip_hooks *hooks;
 	int ret;
 
 	if (strnicmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
@@ -1526,9 +1468,9 @@  static int process_sip_msg(struct sk_buf
 		ret = process_sip_response(skb, protoff, dataoff, dptr, datalen);
 
 	if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
-		nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
-		if (nf_nat_sip && !nf_nat_sip(skb, protoff, dataoff,
-					      dptr, datalen)) {
+		hooks = rcu_dereference(nf_nat_sip_hooks);
+		if (hooks && !hooks->nsh_msg(skb, protoff, dataoff,
+									dptr, datalen)) {
 			nf_ct_helper_log(skb, ct, "cannot NAT SIP message");
 			ret = NF_DROP;
 		}
@@ -1548,7 +1490,6 @@  static int sip_help_tcp(struct sk_buff *
 	s16 diff, tdiff = 0;
 	int ret = NF_ACCEPT;
 	bool term;
-	typeof(nf_nat_sip_seq_adjust_hook) nf_nat_sip_seq_adjust;
 
 	if (ctinfo != IP_CT_ESTABLISHED &&
 	    ctinfo != IP_CT_ESTABLISHED_REPLY)
@@ -1612,9 +1553,11 @@  static int sip_help_tcp(struct sk_buff *
 	}
 
 	if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
-		nf_nat_sip_seq_adjust = rcu_dereference(nf_nat_sip_seq_adjust_hook);
-		if (nf_nat_sip_seq_adjust)
-			nf_nat_sip_seq_adjust(skb, protoff, tdiff);
+		const struct nf_nat_sip_hooks *hooks;
+
+		hooks = rcu_dereference(nf_nat_sip_hooks);
+		if (hooks)
+			hooks->nsh_seq_adjust(skb, protoff, tdiff);
 	}
 
 	return ret;
Index: net-next/include/linux/netfilter/nf_conntrack_sip.h
===================================================================
--- net-next.orig/include/linux/netfilter/nf_conntrack_sip.h
+++ net-next/include/linux/netfilter/nf_conntrack_sip.h
@@ -107,55 +107,65 @@  enum sdp_header_types {
 	SDP_HDR_MEDIA,
 };
 
-extern unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
+struct nf_nat_sip_hooks {
+	unsigned int (* nsh_msg)(struct sk_buff *skb,
+				 unsigned int protoff,
+				 unsigned int dataoff,
+				 const char **dptr,
+				 unsigned int *datalen);
+
+	void (* nsh_seq_adjust)(struct sk_buff *skb,
+				unsigned int protoff, s16 off);
+
+	unsigned int (* nsh_expect)(struct sk_buff *skb,
+				    unsigned int protoff,
+				    unsigned int dataoff,
+				    const char **dptr,
+				    unsigned int *datalen,
+				    struct nf_conntrack_expect *exp,
+				    unsigned int matchoff,
+				    unsigned int matchlen);
+
+	unsigned int (* nsh_sdp_addr)(struct sk_buff *skb,
+				      unsigned int protoff,
+				      unsigned int dataoff,
+				      const char **dptr,
+				      unsigned int *datalen,
+				      unsigned int sdpoff,
+				      enum sdp_header_types type,
+				      enum sdp_header_types term,
+				      const union nf_inet_addr *addr);
+
+	unsigned int (* nsh_sdp_port)(struct sk_buff *skb,
+				      unsigned int protoff,
+				      unsigned int dataoff,
+				      const char **dptr,
+				      unsigned int *datalen,
+				      unsigned int matchoff,
+				      unsigned int matchlen,
+				      u_int16_t port);
+
+	unsigned int (* nsh_sdp_session)(struct sk_buff *skb,
+					 unsigned int protoff,
+					 unsigned int dataoff,
+					 const char **dptr,
+					 unsigned int *datalen,
+					 unsigned int sdpoff,
+					 const union nf_inet_addr *addr);
+
+	unsigned int (* nsh_sdp_media)(struct sk_buff *skb,
 				       unsigned int protoff,
 				       unsigned int dataoff,
 				       const char **dptr,
-				       unsigned int *datalen);
-extern void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb,
-					  unsigned int protoff, s16 off);
-extern unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
-					      unsigned int protoff,
-					      unsigned int dataoff,
-					      const char **dptr,
-					      unsigned int *datalen,
-					      struct nf_conntrack_expect *exp,
-					      unsigned int matchoff,
-					      unsigned int matchlen);
-extern unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb,
-					    unsigned int protoff,
-					    unsigned int dataoff,
-					    const char **dptr,
-					    unsigned int *datalen,
-					    unsigned int sdpoff,
-					    enum sdp_header_types type,
-					    enum sdp_header_types term,
-					    const union nf_inet_addr *addr);
-extern unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb,
-					    unsigned int protoff,
-					    unsigned int dataoff,
-					    const char **dptr,
-					    unsigned int *datalen,
-					    unsigned int matchoff,
-					    unsigned int matchlen,
-					    u_int16_t port);
-extern unsigned int (*nf_nat_sdp_session_hook)(struct sk_buff *skb,
-					       unsigned int protoff,
-					       unsigned int dataoff,
-					       const char **dptr,
-					       unsigned int *datalen,
-					       unsigned int sdpoff,
-					       const union nf_inet_addr *addr);
-extern unsigned int (*nf_nat_sdp_media_hook)(struct sk_buff *skb,
-					     unsigned int protoff,
-					     unsigned int dataoff,
-					     const char **dptr,
-					     unsigned int *datalen,
-					     struct nf_conntrack_expect *rtp_exp,
-					     struct nf_conntrack_expect *rtcp_exp,
-					     unsigned int mediaoff,
-					     unsigned int medialen,
-					     union nf_inet_addr *rtp_addr);
+				       unsigned int *datalen,
+				       struct nf_conntrack_expect *rtp_exp,
+				       struct nf_conntrack_expect *rtcp_exp,
+				       unsigned int mediaoff,
+				       unsigned int medialen,
+				       union nf_inet_addr *rtp_addr);
+};
+extern const struct nf_nat_sip_hooks *nf_nat_sip_hooks;
+
 
 extern int ct_sip_parse_request(const struct nf_conn *ct,
 				const char *dptr, unsigned int datalen,
Index: net-next/net/netfilter/nf_nat_sip.c
===================================================================
--- net-next.orig/net/netfilter/nf_nat_sip.c
+++ net-next/net/netfilter/nf_nat_sip.c
@@ -625,33 +625,26 @@  static struct nf_ct_helper_expectfn sip_
 
 static void __exit nf_nat_sip_fini(void)
 {
-	RCU_INIT_POINTER(nf_nat_sip_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sip_seq_adjust_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sip_expect_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sdp_addr_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sdp_port_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sdp_session_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sdp_media_hook, NULL);
+	RCU_INIT_POINTER(nf_nat_sip_hooks, NULL);
+
 	nf_ct_helper_expectfn_unregister(&sip_nat);
 	synchronize_rcu();
 }
 
+static const struct nf_nat_sip_hooks sip_hooks = {
+	.nsh_msg = nf_nat_sip,
+	.nsh_seq_adjust = nf_nat_sip_seq_adjust,
+	.nsh_expect = nf_nat_sip_expect,
+	.nsh_sdp_addr = nf_nat_sdp_addr,
+	.nsh_sdp_port = nf_nat_sdp_port,
+	.nsh_sdp_session = nf_nat_sdp_session,
+	.nsh_sdp_media = nf_nat_sdp_media,
+};
+
 static int __init nf_nat_sip_init(void)
 {
-	BUG_ON(nf_nat_sip_hook != NULL);
-	BUG_ON(nf_nat_sip_seq_adjust_hook != NULL);
-	BUG_ON(nf_nat_sip_expect_hook != NULL);
-	BUG_ON(nf_nat_sdp_addr_hook != NULL);
-	BUG_ON(nf_nat_sdp_port_hook != NULL);
-	BUG_ON(nf_nat_sdp_session_hook != NULL);
-	BUG_ON(nf_nat_sdp_media_hook != NULL);
-	RCU_INIT_POINTER(nf_nat_sip_hook, nf_nat_sip);
-	RCU_INIT_POINTER(nf_nat_sip_seq_adjust_hook, nf_nat_sip_seq_adjust);
-	RCU_INIT_POINTER(nf_nat_sip_expect_hook, nf_nat_sip_expect);
-	RCU_INIT_POINTER(nf_nat_sdp_addr_hook, nf_nat_sdp_addr);
-	RCU_INIT_POINTER(nf_nat_sdp_port_hook, nf_nat_sdp_port);
-	RCU_INIT_POINTER(nf_nat_sdp_session_hook, nf_nat_sdp_session);
-	RCU_INIT_POINTER(nf_nat_sdp_media_hook, nf_nat_sdp_media);
+	BUG_ON(nf_nat_sip_hooks != NULL);
+	RCU_INIT_POINTER(nf_nat_sip_hooks, &sip_hooks);
 	nf_ct_helper_expectfn_register(&sip_nat);
 	return 0;
 }