From: Patrick McHardy <kaber@trash.net>
Date: Tue, 21 Mar 2006 02:03:59 +0000 (-0800)
Subject: [NETFILTER]: ctnetlink: avoid unneccessary event message generation
X-Git-Tag: v2.6.17-rc1~1175^2~158
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a24276924875802853b5bdc12c56d29f1c1bbc79;p=linux-2.6

[NETFILTER]: ctnetlink: avoid unneccessary event message generation

Avoid unneccessary event message generation by checking for netlink
listeners before building a message.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
index 934a2479f1..9f5b12cf48 100644
--- a/include/linux/netfilter/nfnetlink.h
+++ b/include/linux/netfilter/nfnetlink.h
@@ -164,6 +164,7 @@ extern void nfattr_parse(struct nfattr *tb[], int maxattr,
  	__res;								\
 })
 
+extern int nfnetlink_has_listeners(unsigned int group);
 extern int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, 
 			  int echo);
 extern int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags);
diff --git a/net/ipv4/netfilter/ip_conntrack_netlink.c b/net/ipv4/netfilter/ip_conntrack_netlink.c
index e0b5926c76..5ce2e3fc2c 100644
--- a/net/ipv4/netfilter/ip_conntrack_netlink.c
+++ b/net/ipv4/netfilter/ip_conntrack_netlink.c
@@ -327,9 +327,10 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
 		group = NFNLGRP_CONNTRACK_UPDATE;
 	} else 
 		return NOTIFY_DONE;
-	
-  /* FIXME: Check if there are any listeners before, don't hurt performance */
-	
+
+	if (!nfnetlink_has_listeners(group))
+		return NOTIFY_DONE;
+
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
 	if (!skb)
 		return NOTIFY_DONE;
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index aef3cb4113..5eadf009bb 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -338,9 +338,10 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
 		group = NFNLGRP_CONNTRACK_UPDATE;
 	} else
 		return NOTIFY_DONE;
-	
-  /* FIXME: Check if there are any listeners before, don't hurt performance */
-	
+
+	if (!nfnetlink_has_listeners(group))
+		return NOTIFY_DONE;
+
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
 	if (!skb)
 		return NOTIFY_DONE;
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index f6063e8f00..b88e82a1a9 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -191,6 +191,12 @@ nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
         return 0;
 }
 
+int nfnetlink_has_listeners(unsigned int group)
+{
+	return netlink_has_listeners(nfnl, group);
+}
+EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
+
 int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
 {
 	gfp_t allocation = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;