cache: provide safe variant of nl_cache_mngt_require() and use it

This makes runtime removal of cache operations possible if non-safe
API is not in use by application. The non-safe API will be removed
in the next major version.

Signed-off-by: Thomas Graf <tgraf@suug.ch>

14 files changed, 75 insertions, 26 deletions

diff --git a/include/netlink-local.h b/include/netlink-local.h
index 2bfae3e..b891d8c 100644
--- a/include/netlink-local.h
+++ b/include/netlink-local.h
@@ -117,14 +117,6 @@ extern int __str2flags(const char *, const struct trans_tbl *, size_t);
 
 extern void dump_from_ops(struct nl_object *, struct nl_dump_params *);
 
-static inline struct nl_cache *dp_cache(struct nl_object *obj)
-{
-	if (obj->ce_cache == NULL)
-		return nl_cache_mngt_require(obj->ce_ops->oo_name);
-
-	return obj->ce_cache;
-}
-
 static inline int nl_cb_call(struct nl_cb *cb, int type, struct nl_msg *msg)
 {
 	return cb->cb_set[type](msg, cb->cb_args[type]);
diff --git a/include/netlink/cache.h b/include/netlink/cache.h
index f193c76..ac03842 100644
--- a/include/netlink/cache.h
+++ b/include/netlink/cache.h
@@ -52,6 +52,7 @@ extern struct nl_cache *	nl_cache_clone(struct nl_cache *);
 extern void			nl_cache_clear(struct nl_cache *);
 extern void			nl_cache_get(struct nl_cache *);
 extern void			nl_cache_free(struct nl_cache *);
+extern void			nl_cache_put(struct nl_cache *cache);
 
 /* Cache modification */
 extern int			nl_cache_add(struct nl_cache *,
@@ -118,6 +119,7 @@ extern int			nl_cache_mngt_unregister(struct nl_cache_ops *);
 extern void			nl_cache_mngt_provide(struct nl_cache *);
 extern void			nl_cache_mngt_unprovide(struct nl_cache *);
 extern struct nl_cache *	nl_cache_mngt_require(const char *);
+extern struct nl_cache *	nl_cache_mngt_require_safe(const char *);
 extern struct nl_cache *	__nl_cache_mngt_require(const char *);
 
 struct nl_cache_mngr;
diff --git a/lib/cache.c b/lib/cache.c
index aa17ad8..415e471 100644
--- a/lib/cache.c
+++ b/lib/cache.c
@@ -410,6 +410,11 @@ void nl_cache_free(struct nl_cache *cache)
 		__nl_cache_free(cache);
 }
 
+void nl_cache_put(struct nl_cache *cache)
+{
+	return nl_cache_free(cache);
+}
+
 /** @} */
 
 /**
diff --git a/lib/cache_mngt.c b/lib/cache_mngt.c
index 914ab9b..fbb702f 100644
--- a/lib/cache_mngt.c
+++ b/lib/cache_mngt.c
@@ -390,14 +390,15 @@ struct nl_cache *__nl_cache_mngt_require(const char *name)
 }
 
 /**
- * Demand the use of a global cache
- * @arg name		name of the required object type
+ * Return cache previously provided via nl_cache_mngt_provide()
+ * @arg name		Name of cache to lookup
  *
- * Trys to find a cache of the specified type for global
- * use.
+ * @attention This function is not safe, it does not increment the reference
+ *            counter. Please use nl_cache_mngt_require_safe().
+ *
+ * @see nl_cache_mngt_require_safe()
  *
- * @return A cache provided by another subsystem of the
- *         specified type marked to be available.
+ * @return Pointer to cache or NULL if none registered
  */
 struct nl_cache *nl_cache_mngt_require(const char *name)
 {
@@ -412,6 +413,25 @@ struct nl_cache *nl_cache_mngt_require(const char *name)
 	return cache;
 }
 
+/**
+ * Return cache previously provided via nl_cache_mngt_provide()
+ * @arg name		Name of cache to lookup
+ *
+ * @note The reference counter of the returned cache is incremented
+ *       and must be decremented after use with nl_cache_put().
+ *
+ * @return Pointer to cache or NULL if none registered
+ */
+struct nl_cache *nl_cache_mngt_require_safe(const char *name)
+{
+	struct nl_cache *cache;
+
+	if ((cache = nl_cache_mngt_require(name)))
+		nl_cache_get(cache);
+	
+	return cache;
+}
+
 /** @} */
 
 /** @} */
diff --git a/lib/netfilter/log_msg_obj.c b/lib/netfilter/log_msg_obj.c
index d2cde4e..d2ad0ff 100644
--- a/lib/netfilter/log_msg_obj.c
+++ b/lib/netfilter/log_msg_obj.c
@@ -76,7 +76,7 @@ static void log_msg_dump(struct nl_object *a, struct nl_dump_params *p)
 	struct nl_cache *link_cache;
 	char buf[64];
 
-	link_cache = nl_cache_mngt_require("route/link");
+	link_cache = nl_cache_mngt_require_safe("route/link");
 
 	nl_new_line(p);
 
@@ -167,6 +167,9 @@ static void log_msg_dump(struct nl_object *a, struct nl_dump_params *p)
 		nl_dump(p, "SEQGLOBAL=%d ", msg->log_msg_seq_global);
 
 	nl_dump(p, "\n");
+
+	if (link_cache)
+		nl_cache_put(link_cache);
 }
 
 /**
diff --git a/lib/netfilter/queue_msg_obj.c b/lib/netfilter/queue_msg_obj.c
index 33305ed..bfaafc5 100644
--- a/lib/netfilter/queue_msg_obj.c
+++ b/lib/netfilter/queue_msg_obj.c
@@ -66,7 +66,7 @@ static void nfnl_queue_msg_dump(struct nl_object *a, struct nl_dump_params *p)
 	struct nl_cache *link_cache;
 	char buf[64];
 
-	link_cache = nl_cache_mngt_require("route/link");
+	link_cache = nl_cache_mngt_require_safe("route/link");
 
 	nl_new_line(p);
 
@@ -152,6 +152,9 @@ static void nfnl_queue_msg_dump(struct nl_object *a, struct nl_dump_params *p)
 					 buf, sizeof(buf)));
 
 	nl_dump(p, "\n");
+
+	if (link_cache)
+		nl_cache_put(link_cache);
 }
 
 /**
diff --git a/lib/route/addr.c b/lib/route/addr.c
index 7e29529..c5e14bb 100644
--- a/lib/route/addr.c
+++ b/lib/route/addr.c
@@ -332,7 +332,7 @@ static void addr_dump_line(struct nl_object *obj, struct nl_dump_params *p)
 	struct nl_cache *link_cache;
 	char buf[128];
 
-	link_cache = nl_cache_mngt_require("route/link");
+	link_cache = nl_cache_mngt_require_safe("route/link");
 
 	if (addr->ce_mask & ADDR_ATTR_LOCAL)
 		nl_dump_line(p, "%s",
@@ -361,6 +361,9 @@ static void addr_dump_line(struct nl_object *obj, struct nl_dump_params *p)
 		nl_dump(p, " <%s>", buf);
 
 	nl_dump(p, "\n");
+
+	if (link_cache)
+		nl_cache_put(link_cache);
 }
 
 static void addr_dump_details(struct nl_object *obj, struct nl_dump_params *p)
diff --git a/lib/route/link.c b/lib/route/link.c
index b378f30..1cecd54 100644
--- a/lib/route/link.c
+++ b/lib/route/link.c
@@ -581,7 +581,7 @@ static int link_request_update(struct nl_cache *cache, struct nl_sock *sk)
 static void link_dump_line(struct nl_object *obj, struct nl_dump_params *p)
 {
 	char buf[128];
-	struct nl_cache *cache = dp_cache(obj);
+	struct nl_cache *cache = obj->ce_cache;
 	struct rtnl_link *link = (struct rtnl_link *) obj;
 
 	nl_dump_line(p, "%s %s ", link->l_name,
diff --git a/lib/route/neigh.c b/lib/route/neigh.c
index 4b5893a..4a85a85 100644
--- a/lib/route/neigh.c
+++ b/lib/route/neigh.c
@@ -401,7 +401,7 @@ int rtnl_neigh_parse(struct nlmsghdr *n, struct rtnl_neigh **result)
 	 * Get the bridge index for AF_BRIDGE family entries
 	 */
 	if (neigh->n_family == AF_BRIDGE) {
-		struct nl_cache *lcache = nl_cache_mngt_require("route/link");
+		struct nl_cache *lcache = nl_cache_mngt_require_safe("route/link");
 		if (lcache ) {
 			struct rtnl_link *link = rtnl_link_get(lcache,
 							neigh->n_ifindex);
@@ -410,6 +410,8 @@ int rtnl_neigh_parse(struct nlmsghdr *n, struct rtnl_neigh **result)
 				rtnl_link_put(link);
 				neigh->ce_mask |= NEIGH_ATTR_MASTER;
 			}
+
+			nl_cache_put(lcache);
 		}
 	}
 
@@ -436,7 +438,7 @@ static void neigh_dump_line(struct nl_object *a, struct nl_dump_params *p)
 	struct nl_cache *link_cache;
 	char state[128], flags[64];
 
-	link_cache = nl_cache_mngt_require("route/link");
+	link_cache = nl_cache_mngt_require_safe("route/link");
 
 	if (n->n_family != AF_BRIDGE)
 		nl_dump_line(p, "%s ", nl_addr2str(n->n_dst, dst, sizeof(dst)));
@@ -462,6 +464,9 @@ static void neigh_dump_line(struct nl_object *a, struct nl_dump_params *p)
 	if (state[0] || flags[0])
 		nl_dump(p, ">");
 	nl_dump(p, "\n");
+
+	if (link_cache)
+		nl_cache_put(link_cache);
 }
 
 static void neigh_dump_details(struct nl_object *a, struct nl_dump_params *p)
diff --git a/lib/route/neightbl.c b/lib/route/neightbl.c
index 1efa5cb..509617b 100644
--- a/lib/route/neightbl.c
+++ b/lib/route/neightbl.c
@@ -237,7 +237,7 @@ static void neightbl_dump_line(struct nl_object *arg, struct nl_dump_params *p)
 	if (ntbl->nt_parms.ntp_mask & NEIGHTBLPARM_ATTR_IFINDEX) {
 		struct nl_cache *link_cache;
 		
-		link_cache = nl_cache_mngt_require("route/link");
+		link_cache = nl_cache_mngt_require_safe("route/link");
 
 		if (link_cache) {
 			char buf[32];
@@ -245,6 +245,7 @@ static void neightbl_dump_line(struct nl_object *arg, struct nl_dump_params *p)
 				rtnl_link_i2name(link_cache,
 						 ntbl->nt_parms.ntp_ifindex,
 						 buf, sizeof(buf)));
+			nl_cache_put(link_cache);
 		} else
 			nl_dump(p, "<%u> ", ntbl->nt_parms.ntp_ifindex);
 	} else
diff --git a/lib/route/nexthop.c b/lib/route/nexthop.c
index 189bccd..9990c51 100644
--- a/lib/route/nexthop.c
+++ b/lib/route/nexthop.c
@@ -109,7 +109,7 @@ static void nh_dump_line(struct rtnl_nexthop *nh, struct nl_dump_params *dp)
 	struct nl_cache *link_cache;
 	char buf[128];
 
-	link_cache = nl_cache_mngt_require("route/link");
+	link_cache = nl_cache_mngt_require_safe("route/link");
 
 	nl_dump(dp, "via");
 
@@ -128,6 +128,9 @@ static void nh_dump_line(struct rtnl_nexthop *nh, struct nl_dump_params *dp)
 	}
 
 	nl_dump(dp, " ");
+
+	if (link_cache)
+		nl_cache_put(link_cache);
 }
 
 static void nh_dump_details(struct rtnl_nexthop *nh, struct nl_dump_params *dp)
@@ -135,7 +138,7 @@ static void nh_dump_details(struct rtnl_nexthop *nh, struct nl_dump_params *dp)
 	struct nl_cache *link_cache;
 	char buf[128];
 
-	link_cache = nl_cache_mngt_require("route/link");
+	link_cache = nl_cache_mngt_require_safe("route/link");
 
 	nl_dump(dp, "nexthop");
 
@@ -164,6 +167,9 @@ static void nh_dump_details(struct rtnl_nexthop *nh, struct nl_dump_params *dp)
 	if (nh->ce_mask & NH_ATTR_FLAGS)
 		nl_dump(dp, " <%s>", rtnl_route_nh_flags2str(nh->rtnh_flags,
 							buf, sizeof(buf)));
+
+	if (link_cache)
+		nl_cache_put(link_cache);
 }
 
 void rtnl_route_nh_dump(struct rtnl_nexthop *nh, struct nl_dump_params *dp)
diff --git a/lib/route/route_obj.c b/lib/route/route_obj.c
index 0ee9ca0..cc29746 100644
--- a/lib/route/route_obj.c
+++ b/lib/route/route_obj.c
@@ -210,7 +210,7 @@ static void route_dump_details(struct nl_object *a, struct nl_dump_params *p)
 	char buf[128];
 	int i;
 
-	link_cache = nl_cache_mngt_require("route/link");
+	link_cache = nl_cache_mngt_require_safe("route/link");
 
 	route_dump_line(a, p);
 	nl_dump_line(p, "    ");
@@ -271,6 +271,9 @@ static void route_dump_details(struct nl_object *a, struct nl_dump_params *p)
 					r->rt_metrics[i]);
 		nl_dump(p, "]\n");
 	}
+
+	if (link_cache)
+		nl_cache_put(link_cache);
 }
 
 static void route_dump_stats(struct nl_object *obj, struct nl_dump_params *p)
diff --git a/lib/route/tc.c b/lib/route/tc.c
index 6c72c15..5a0b783 100644
--- a/lib/route/tc.c
+++ b/lib/route/tc.c
@@ -822,7 +822,7 @@ void rtnl_tc_dump_line(struct nl_object *obj, struct nl_dump_params *p)
 
 	nl_dump(p, "%s ", tc->tc_kind);
 
-	if ((link_cache = nl_cache_mngt_require("route/link"))) {
+	if ((link_cache = nl_cache_mngt_require_safe("route/link"))) {
 		nl_dump(p, "dev %s ",
 			rtnl_link_i2name(link_cache, tc->tc_ifindex,
 					 buf, sizeof(buf)));
@@ -837,6 +837,9 @@ void rtnl_tc_dump_line(struct nl_object *obj, struct nl_dump_params *p)
 
 	tc_dump(tc, NL_DUMP_LINE, p);
 	nl_dump(p, "\n");
+
+	if (link_cache)
+		nl_cache_put(link_cache);
 }
 
 void rtnl_tc_dump_details(struct nl_object *obj, struct nl_dump_params *p)
diff --git a/src/nl-addr-list.c b/src/nl-addr-list.c
index 5044d5c..20995a8 100644
--- a/src/nl-addr-list.c
+++ b/src/nl-addr-list.c
@@ -65,7 +65,7 @@ static void env_dump(struct nl_object *obj, void *arg)
 		     nl_addr2str(rtnl_addr_get_local(addr), buf, sizeof(buf)));
 
 	nl_dump_line(p, "%s_IFINDEX=%u\n", pfx, rtnl_addr_get_ifindex(addr));
-	link_cache = nl_cache_mngt_require("route/link");
+	link_cache = nl_cache_mngt_require_safe("route/link");
 	if (link_cache)
 		nl_dump_line(p, "%s_IFNAME=%s\n", pfx,
 			     rtnl_link_i2name(link_cache,
@@ -94,6 +94,9 @@ static void env_dump(struct nl_object *obj, void *arg)
 	nl_dump_line(p, "%s_CACHEINFO_VALID=%u\n", pfx,
 		     rtnl_addr_get_valid_lifetime(addr));
 
+	if (link_cache)
+		nl_cache_put(link_cache);
+
 #if 0
 	if (addr->ce_mask & ADDR_ATTR_CACHEINFO) {
 		struct rtnl_addr_cacheinfo *ci = &addr->a_cacheinfo;