Commit a2427692 authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

[NETFILTER]: ctnetlink: avoid unneccessary event message generation 



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

Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c4b88513

include/linux/netfilter/nfnetlink.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

net/ipv4/netfilter/ip_conntrack_netlink.c

+4 −3
Original line number Diff line number Diff line
@@ -328,7 +328,8 @@ static int ctnetlink_conntrack_event(struct notifier_block *this, 
	} 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)

net/netfilter/nf_conntrack_netlink.c

+4 −3
Original line number Diff line number Diff line
@@ -339,7 +339,8 @@ static int ctnetlink_conntrack_event(struct notifier_block *this, 
	} 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)

net/netfilter/nfnetlink.c

+6 −0
Original line number Diff line number Diff line
@@ -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;

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