[NETFILTER]: nf_conntrack_helper: use hashtable for conntrack helpers

Eliminate the last global list searched for every new connection.

Signed-off-by: Patrick McHardy <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/netfilter/nf_conntrack_helper.h

···
 struct module;
 
 struct nf_conntrack_helper
-{	
-	struct list_head list; 		/* Internal use. */
+{
+	struct hlist_node hnode;	/* Internal use. */
 
 	const char *name;		/* name of the module */
 	struct module *me;		/* pointer to self */

net/netfilter/nf_conntrack_helper.c

···
 #include <net/netfilter/nf_conntrack_core.h>
 #include <net/netfilter/nf_conntrack_extend.h>
 
-static __read_mostly LIST_HEAD(helpers);
+static struct hlist_head *nf_ct_helper_hash __read_mostly;
+static unsigned int nf_ct_helper_hsize __read_mostly;
+static unsigned int nf_ct_helper_count __read_mostly;
+static int nf_ct_helper_vmalloc;
+
+
+/* Stupid hash, but collision free for the default registrations of the
+ * helpers currently in the kernel. */
+static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
+{
+	return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
+		tuple->src.u.all) % nf_ct_helper_hsize;
+}
 
 struct nf_conntrack_helper *
 __nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
 {
-	struct nf_conntrack_helper *h;
+	struct nf_conntrack_helper *helper;
 	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
+	struct hlist_node *n;
+	unsigned int h;
 
-	list_for_each_entry(h, &helpers, list) {
-		if (nf_ct_tuple_src_mask_cmp(tuple, &h->tuple, &mask))
-			return h;
+	if (!nf_ct_helper_count)
+		return NULL;
+
+	h = helper_hash(tuple);
+	hlist_for_each_entry(helper, n, &nf_ct_helper_hash[h], hnode) {
+		if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
+			return helper;
 	}
 	return NULL;
 }
 
 struct nf_conntrack_helper *
-nf_ct_helper_find_get( const struct nf_conntrack_tuple *tuple)
+nf_ct_helper_find_get(const struct nf_conntrack_tuple *tuple)
 {
 	struct nf_conntrack_helper *helper;
 
···
 __nf_conntrack_helper_find_byname(const char *name)
 {
 	struct nf_conntrack_helper *h;
+	struct hlist_node *n;
+	unsigned int i;
 
-	list_for_each_entry(h, &helpers, list) {
-		if (!strcmp(h->name, name))
-			return h;
+	for (i = 0; i < nf_ct_helper_hsize; i++) {
+		hlist_for_each_entry(h, n, &nf_ct_helper_hash[i], hnode) {
+			if (!strcmp(h->name, name))
+				return h;
+		}
 	}
-
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find_byname);
···
 
 int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
 {
+	unsigned int h = helper_hash(&me->tuple);
+
 	BUG_ON(me->timeout == 0);
 
 	write_lock_bh(&nf_conntrack_lock);
-	list_add(&me->list, &helpers);
+	hlist_add_head(&me->hnode, &nf_ct_helper_hash[h]);
+	nf_ct_helper_count++;
 	write_unlock_bh(&nf_conntrack_lock);
 
 	return 0;
···
 
 	/* Need write lock here, to delete helper. */
 	write_lock_bh(&nf_conntrack_lock);
-	list_del(&me->list);
+	hlist_del(&me->hnode);
+	nf_ct_helper_count--;
 
 	/* Get rid of expectations */
 	for (i = 0; i < nf_ct_expect_hsize; i++) {
···
 
 int nf_conntrack_helper_init()
 {
-	return nf_ct_extend_register(&helper_extend);
+	int err;
+
+	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
+	nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize,
+						  &nf_ct_helper_vmalloc);
+	if (!nf_ct_helper_hash)
+		return -ENOMEM;
+
+	err = nf_ct_extend_register(&helper_extend);
+	if (err < 0)
+		goto err1;
+
+	return 0;
+
+err1:
+	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc,
+			     nf_ct_helper_hsize);
+	return err;
 }
 
 void nf_conntrack_helper_fini()
 {
 	nf_ct_extend_unregister(&helper_extend);
+	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc,
+			     nf_ct_helper_hsize);
 }