netfilter: conntrack: avoid useless indirection during conntrack destruction

nf_ct_put() results in a usesless indirection:

nf_ct_put -> nf_conntrack_put -> nf_conntrack_destroy -> rcu readlock +
indirect call of ct_hooks->destroy().

There are two _put helpers:
nf_ct_put and nf_conntrack_put.  The latter is what should be used in
code that MUST NOT cause a linker dependency on the conntrack module
(e.g. calls from core network stack).

Everyone else should call nf_ct_put() instead.

A followup patch will convert a few nf_conntrack_put() calls to
nf_ct_put(), in particular from modules that already have a conntrack
dependency such as act_ct or even nf_conntrack itself.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index cd3d07e418b5..7a2063abae04 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -558,7 +558,7 @@ static void nf_ct_del_from_dying_or_unconfirmed_list(struct nf_conn *ct)
 
 #define NFCT_ALIGN(len)	(((len) + NFCT_INFOMASK) & ~NFCT_INFOMASK)
 
-/* Released via destroy_conntrack() */
+/* Released via nf_ct_destroy() */
 struct nf_conn *nf_ct_tmpl_alloc(struct net *net,
 				 const struct nf_conntrack_zone *zone,
 				 gfp_t flags)
@@ -612,12 +612,11 @@ static void destroy_gre_conntrack(struct nf_conn *ct)
 #endif
 }
 
-static void
-destroy_conntrack(struct nf_conntrack *nfct)
+void nf_ct_destroy(struct nf_conntrack *nfct)
 {
 	struct nf_conn *ct = (struct nf_conn *)nfct;
 
-	pr_debug("destroy_conntrack(%p)\n", ct);
+	pr_debug("%s(%p)\n", __func__, ct);
 	WARN_ON(refcount_read(&nfct->use) != 0);
 
 	if (unlikely(nf_ct_is_template(ct))) {
@@ -643,9 +642,10 @@ destroy_conntrack(struct nf_conntrack *nfct)
 	if (ct->master)
 		nf_ct_put(ct->master);
 
-	pr_debug("destroy_conntrack: returning ct=%p to slab\n", ct);
+	pr_debug("%s: returning ct=%p to slab\n", __func__, ct);
 	nf_conntrack_free(ct);
 }
+EXPORT_SYMBOL(nf_ct_destroy);
 
 static void nf_ct_delete_from_lists(struct nf_conn *ct)
 {
@@ -2771,7 +2771,7 @@ err_cachep:
 
 static const struct nf_ct_hook nf_conntrack_hook = {
 	.update		= nf_conntrack_update,
-	.destroy	= destroy_conntrack,
+	.destroy	= nf_ct_destroy,
 	.get_tuple_skb  = nf_conntrack_get_tuple_skb,
 	.attach		= nf_conntrack_attach,
 };