To support upcoming changes change internal API for source node handling:

- Removed pf_remove_src_node().
- Introduce pf_unlink_src_node() and pf_unlink_src_node_locked().
  These function do not proceed with freeing of a node, just disconnect
  it from storage.
- New function pf_free_src_nodes() works on a list of previously
  disconnected nodes and frees them.
- Utilize new API in pf_purge_expired_src_nodes().

In collaboration with:	Kajetan Staszkiewicz <kajetan.staszkiewicz innogames.de>

Sponsored by:	InnoGames GmbH
Sponsored by:	Nginx, Inc.

sys/net/pfvar.h

@@ -1467,8 +1467,9 @@ struct pf_ifspeed {
 #define	DIOCGIFSPEED	_IOWR('D', 92, struct pf_ifspeed)
 
 #ifdef _KERNEL
+LIST_HEAD(pf_src_node_list, pf_src_node);
 struct pf_srchash {
-	LIST_HEAD(, pf_src_node)	nodes;
+	struct pf_src_node_list		nodes;
 	struct mtx			lock;
 };
 
@@ -1576,6 +1577,9 @@ extern struct pf_state		*pf_find_state_all(struct pf_state_key_cmp *,
 				    u_int, int *);
 extern struct pf_src_node	*pf_find_src_node(struct pf_addr *,
 				    struct pf_rule *, sa_family_t, int);
+extern void			 pf_unlink_src_node(struct pf_src_node *);
+extern void			 pf_unlink_src_node_locked(struct pf_src_node *);
+extern u_int			 pf_free_src_nodes(struct pf_src_node_list *);
 extern void			 pf_print_state(struct pf_state *);
 extern void			 pf_print_flags(u_int8_t);
 extern u_int16_t		 pf_cksum_fixup(u_int16_t, u_int16_t, u_int16_t,

sys/netpfil/pf/pf.c

@@ -681,20 +681,54 @@ pf_insert_src_node(struct pf_src_node **sn, struct pf_rule *rule,
 	return (0);
 }
 
-static void
+void
-pf_remove_src_node(struct pf_src_node *src)
+pf_unlink_src_node_locked(struct pf_src_node *src)
+{
+#ifdef INVARIANTS
+	struct pf_srchash *sh;
+
+	sh = &V_pf_srchash[pf_hashsrc(&src->addr, src->af)];
+	PF_HASHROW_ASSERT(sh);
+#endif
+	LIST_REMOVE(src, entry);
+	if (src->rule.ptr)
+		src->rule.ptr->src_nodes--;
+	V_pf_status.scounters[SCNT_SRC_NODE_REMOVALS]++;
+	V_pf_status.src_nodes--;
+}
+
+void
+pf_unlink_src_node(struct pf_src_node *src)
 {
 	struct pf_srchash *sh;
 
 	sh = &V_pf_srchash[pf_hashsrc(&src->addr, src->af)];
 	PF_HASHROW_LOCK(sh);
-	LIST_REMOVE(src, entry);
+	pf_unlink_src_node_locked(src);
 	PF_HASHROW_UNLOCK(sh);
+}
 
-	V_pf_status.scounters[SCNT_SRC_NODE_REMOVALS]++;
+static void
-	V_pf_status.src_nodes--;
+pf_free_src_node(struct pf_src_node *sn)
+{
 
-	uma_zfree(V_pf_sources_z, src);
+	KASSERT(sn->states == 0, ("%s: %p has refs", __func__, sn));
+	LIST_REMOVE(sn, entry);
+	uma_zfree(V_pf_sources_z, sn);
+}
+
+u_int
+pf_free_src_nodes(struct pf_src_node_list *head)
+{
+	struct pf_src_node *sn, *tmp;
+	u_int count = 0;
+
+	LIST_FOREACH_SAFE(sn, head, entry, tmp) {
+		pf_free_src_node(sn);
+		count++;
+	}
+
+	return (count);
 }
 
 /* Data storage structures initialization. */
@@ -1464,24 +1498,24 @@ pf_state_expires(const struct pf_state *state)
 void
 pf_purge_expired_src_nodes()
 {
+	struct pf_src_node_list	 freelist;
 	struct pf_srchash	*sh;
 	struct pf_src_node	*cur, *next;
 	int i;
 
+	LIST_INIT(&freelist);
 	for (i = 0, sh = V_pf_srchash; i <= V_pf_srchashmask; i++, sh++) {
 	    PF_HASHROW_LOCK(sh);
 	    LIST_FOREACH_SAFE(cur, &sh->nodes, entry, next)
 		if (cur->states == 0 && cur->expire <= time_uptime) {
-			if (cur->rule.ptr != NULL)
+			pf_unlink_src_node_locked(cur);
-				cur->rule.ptr->src_nodes--;
+			LIST_INSERT_HEAD(&freelist, cur, entry);
-			LIST_REMOVE(cur, entry);
-			V_pf_status.scounters[SCNT_SRC_NODE_REMOVALS]++;
-			V_pf_status.src_nodes--;
-			uma_zfree(V_pf_sources_z, cur);
 		} else if (cur->rule.ptr != NULL)
 			cur->rule.ptr->rule_flag |= PFRULE_REFS;
 	    PF_HASHROW_UNLOCK(sh);
 	}
+
+	pf_free_src_nodes(&freelist);
 }
 
 static void
@@ -3771,11 +3805,15 @@ pf_create_state(struct pf_rule *r, struct pf_rule *nr, struct pf_rule *a,
 	if (nk != NULL)
 		uma_zfree(V_pf_state_key_z, nk);
 
-	if (sn != NULL && sn->states == 0 && sn->expire == 0)
+	if (sn != NULL && sn->states == 0 && sn->expire == 0) {
-		pf_remove_src_node(sn);
+		pf_unlink_src_node(sn);
+		pf_free_src_node(sn);
+	}
 
-	if (nsn != sn && nsn != NULL && nsn->states == 0 && nsn->expire == 0)
+	if (nsn != sn && nsn != NULL && nsn->states == 0 && nsn->expire == 0) {
-		pf_remove_src_node(nsn);
+		pf_unlink_src_node(nsn);
+		pf_free_src_node(nsn);
+	}
 
 	return (PF_DROP);
 }