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authorFlorian Westphal <fw@strlen.de>2022-01-07 07:03:25 +0300
committerPablo Neira Ayuso <pablo@netfilter.org>2022-01-10 01:30:13 +0300
commit6ae7989c9af0d98ab64196f4f4c6f6499454bd23 (patch)
treee351c62322a77c4fe66cb8382070fb5d69db0b63 /include/net
parent285c8a7a58158cb1805c97ff03875df2ba2ea1fe (diff)
downloadlinux-6ae7989c9af0d98ab64196f4f4c6f6499454bd23.tar.xz
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>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/netfilter/nf_conntrack.h8
1 files changed, 6 insertions, 2 deletions
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index a4a14f3a5e38..8731d5bcb47d 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -76,6 +76,8 @@ struct nf_conn {
* Hint, SKB address this struct and refcnt via skb->_nfct and
* helpers nf_conntrack_get() and nf_conntrack_put().
* Helper nf_ct_put() equals nf_conntrack_put() by dec refcnt,
+ * except that the latter uses internal indirection and does not
+ * result in a conntrack module dependency.
* beware nf_ct_get() is different and don't inc refcnt.
*/
struct nf_conntrack ct_general;
@@ -170,11 +172,13 @@ nf_ct_get(const struct sk_buff *skb, enum ip_conntrack_info *ctinfo)
return (struct nf_conn *)(nfct & NFCT_PTRMASK);
}
+void nf_ct_destroy(struct nf_conntrack *nfct);
+
/* decrement reference count on a conntrack */
static inline void nf_ct_put(struct nf_conn *ct)
{
- WARN_ON(!ct);
- nf_conntrack_put(&ct->ct_general);
+ if (ct && refcount_dec_and_test(&ct->ct_general.use))
+ nf_ct_destroy(&ct->ct_general);
}
/* Protocol module loading */