From: Florian Westphal fw@strlen.de
commit 6ae7989c9af0d98ab64196f4f4c6f6499454bd23 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/netfilter/nf_conntrack_common.h | 2 ++ include/net/netfilter/nf_conntrack.h | 8 ++++++-- net/netfilter/nf_conntrack_core.c | 12 ++++++------ 3 files changed, 14 insertions(+), 8 deletions(-)
--- a/include/linux/netfilter/nf_conntrack_common.h +++ b/include/linux/netfilter/nf_conntrack_common.h @@ -29,6 +29,8 @@ struct nf_conntrack { };
void nf_conntrack_destroy(struct nf_conntrack *nfct); + +/* like nf_ct_put, but without module dependency on nf_conntrack */ static inline void nf_conntrack_put(struct nf_conntrack *nfct) { if (nfct && refcount_dec_and_test(&nfct->use)) --- 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; @@ -169,11 +171,13 @@ nf_ct_get(const struct sk_buff *skb, enu 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 */ --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -571,7 +571,7 @@ static void nf_ct_del_from_dying_or_unco
#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) @@ -625,12 +625,11 @@ static void destroy_gre_conntrack(struct #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))) { @@ -656,9 +655,10 @@ destroy_conntrack(struct nf_conntrack *n 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) { @@ -2825,7 +2825,7 @@ err_cachep:
static 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, };