mgcp_ratectr: do not set talloc destructor on library allocated item

The rate counter and stats item groups, which are allocated in
mgcp_ratectr.c are freed using a talloc destructor that is set in the
context of the item we just allocated using the stats / rate counter API
functions. When we do that, we risk overwriting an already existing
talloc destructor. Lets instead implement own free functions and set
those as talloc_destructor from above (trunk and MGCP config)

Change-Id: Ifc5091e9f95cc721e58d1eb2e55b97102c497706
Related: OS#5201

include/osmocom/mgcp/mgcp_ratectr.h

@@ -93,7 +93,9 @@ struct mgcp_config;
 struct mgcp_trunk;
 
 int mgcp_ratectr_global_alloc(struct mgcp_config *cfg);
+void mgcp_ratectr_global_free(struct mgcp_config *cfg);
 int mgcp_ratectr_trunk_alloc(struct mgcp_trunk *trunk);
+void mgcp_ratectr_trunk_free(struct mgcp_trunk *trunk);
 
 /* Trunk-global common stat items */
 enum {
@@ -107,4 +109,4 @@ struct mgcp_stat_trunk {
 };
 
 int mgcp_stat_trunk_alloc(struct mgcp_trunk *trunk);
-
+void mgcp_stat_trunk_free(struct mgcp_trunk *trunk);

src/libosmo-mgcp/mgcp_protocol.c

@@ -1583,6 +1583,13 @@ void mgcp_trunk_set_keepalive(struct mgcp_trunk *trunk, int interval)
 				    trunk->keepalive_interval, 0);
 }
 
+/* Free config, this function is automatically called by talloc_free when the configuration is freed. */
+static int config_free_talloc_destructor(struct mgcp_config *cfg)
+{
+	mgcp_ratectr_global_free(cfg);
+	return 0;
+}
+
 /*! allocate configuration with default values.
  *  (called once at startup by main function) */
 struct mgcp_config *mgcp_config_alloc(void)
@@ -1621,6 +1628,7 @@ struct mgcp_config *mgcp_config_alloc(void)
 	}
 
 	mgcp_ratectr_global_alloc(cfg);
+	talloc_set_destructor(cfg, config_free_talloc_destructor);
 
 	return cfg;
 }

src/libosmo-mgcp/mgcp_ratectr.c

@@ -150,12 +150,6 @@ const static struct rate_ctr_group_desc all_rtp_conn_rate_ctr_group_desc = {
 	.ctr_desc = all_rtp_conn_rate_ctr_desc
 };
 
-static int free_rate_counter_group(struct rate_ctr_group *rate_ctr_group)
-{
-	rate_ctr_group_free(rate_ctr_group);
-	return 0;
-}
-
 /*! allocate global rate counters
  *  (called once at startup).
  *  \param[in] cfg mgw configuration for which the rate counters are allocated.
@@ -173,12 +167,24 @@ int mgcp_ratectr_global_alloc(struct mgcp_config *cfg)
 			return -EINVAL;
 		snprintf(ctr_name, sizeof(ctr_name), "%s:general", cfg->domain);
 		rate_ctr_group_set_name(ratectr->mgcp_general_ctr_group, ctr_name);
-		talloc_set_destructor(ratectr->mgcp_general_ctr_group, free_rate_counter_group);
 		general_rate_ctr_index++;
 	}
 	return 0;
 }
 
+/*! free global rate counters
+ *  (called once at process shutdown).
+ *  \param[in] cfg mgw configuration for which the rate counters are allocated. */
+void mgcp_ratectr_global_free(struct mgcp_config *cfg)
+{
+	struct mgcp_ratectr_global *ratectr = &cfg->ratectr;
+
+	if (ratectr->mgcp_general_ctr_group) {
+		rate_ctr_group_free(ratectr->mgcp_general_ctr_group);
+		ratectr->mgcp_general_ctr_group = NULL;
+	}
+}
+
 /*! allocate trunk specific rate counters
  *  (called once on trunk initialization).
  *  \param[in] trunk mgw trunk for which the rate counters are allocated.
@@ -200,7 +206,6 @@ int mgcp_ratectr_trunk_alloc(struct mgcp_trunk *trunk)
 		snprintf(ctr_name, sizeof(ctr_name), "%s-%u:crcx", mgcp_trunk_type_strs_str(trunk->trunk_type),
 			 trunk->trunk_nr);
 		rate_ctr_group_set_name(ratectr->mgcp_crcx_ctr_group, ctr_name);
-		talloc_set_destructor(ratectr->mgcp_crcx_ctr_group, free_rate_counter_group);
 		crcx_rate_ctr_index++;
 	}
 	if (ratectr->mgcp_mdcx_ctr_group == NULL) {
@@ -211,7 +216,6 @@ int mgcp_ratectr_trunk_alloc(struct mgcp_trunk *trunk)
 		snprintf(ctr_name, sizeof(ctr_name), "%s-%u:mdcx", mgcp_trunk_type_strs_str(trunk->trunk_type),
 			 trunk->trunk_nr);
 		rate_ctr_group_set_name(ratectr->mgcp_mdcx_ctr_group, ctr_name);
-		talloc_set_destructor(ratectr->mgcp_mdcx_ctr_group, free_rate_counter_group);
 		mdcx_rate_ctr_index++;
 	}
 	if (ratectr->mgcp_dlcx_ctr_group == NULL) {
@@ -222,7 +226,6 @@ int mgcp_ratectr_trunk_alloc(struct mgcp_trunk *trunk)
 		snprintf(ctr_name, sizeof(ctr_name), "%s-%u:dlcx", mgcp_trunk_type_strs_str(trunk->trunk_type),
 			 trunk->trunk_nr);
 		rate_ctr_group_set_name(ratectr->mgcp_dlcx_ctr_group, ctr_name);
-		talloc_set_destructor(ratectr->mgcp_dlcx_ctr_group, free_rate_counter_group);
 		dlcx_rate_ctr_index++;
 	}
 	if (ratectr->all_rtp_conn_stats == NULL) {
@@ -233,7 +236,6 @@ int mgcp_ratectr_trunk_alloc(struct mgcp_trunk *trunk)
 		snprintf(ctr_name, sizeof(ctr_name), "%s-%u:rtp_conn", mgcp_trunk_type_strs_str(trunk->trunk_type),
 			 trunk->trunk_nr);
 		rate_ctr_group_set_name(ratectr->all_rtp_conn_stats, ctr_name);
-		talloc_set_destructor(ratectr->all_rtp_conn_stats, free_rate_counter_group);
 		all_rtp_conn_rate_ctr_index++;
 	}
 
@@ -245,12 +247,42 @@ int mgcp_ratectr_trunk_alloc(struct mgcp_trunk *trunk)
 		snprintf(ctr_name, sizeof(ctr_name), "%s-%u:e1", mgcp_trunk_type_strs_str(trunk->trunk_type),
 			 trunk->trunk_nr);
 		rate_ctr_group_set_name(ratectr->e1_stats, ctr_name);
-		talloc_set_destructor(ratectr->e1_stats, free_rate_counter_group);
 		mdcx_rate_ctr_index++;
 	}
 	return 0;
 }
 
+/*! free trunk specific rate counters
+ *  (called once when trunk is freed).
+ *  \param[in] trunk mgw trunk on which the rate counters are allocated. */
+void mgcp_ratectr_trunk_free(struct mgcp_trunk *trunk)
+{
+	struct mgcp_ratectr_trunk *ratectr = &trunk->ratectr;
+
+	if (ratectr->mgcp_crcx_ctr_group) {
+		rate_ctr_group_free(ratectr->mgcp_crcx_ctr_group);
+		ratectr->mgcp_crcx_ctr_group = NULL;
+	}
+	if (ratectr->mgcp_mdcx_ctr_group) {
+		rate_ctr_group_free(ratectr->mgcp_mdcx_ctr_group);
+		ratectr->mgcp_mdcx_ctr_group = NULL;
+	}
+	if (ratectr->mgcp_dlcx_ctr_group) {
+		rate_ctr_group_free(ratectr->mgcp_dlcx_ctr_group);
+		ratectr->mgcp_dlcx_ctr_group = NULL;
+	}
+	if (ratectr->all_rtp_conn_stats) {
+		rate_ctr_group_free(ratectr->all_rtp_conn_stats);
+		ratectr->all_rtp_conn_stats = NULL;
+	}
+
+	/* E1 specific */
+	if (ratectr->e1_stats) {
+		rate_ctr_group_free(ratectr->e1_stats);
+		ratectr->e1_stats = NULL;
+	}
+}
+
 const struct osmo_stat_item_desc trunk_stat_desc[] = {
 	[TRUNK_STAT_ENDPOINTS_TOTAL] = { "endpoints:total",
 					 "Number of endpoints that exist on the trunk",
@@ -268,12 +300,6 @@ const struct osmo_stat_item_group_desc trunk_statg_desc = {
 	.item_desc = trunk_stat_desc,
 };
 
-static int free_stat_item_group(struct osmo_stat_item_group *stat_item_group)
-{
-	osmo_stat_item_group_free(stat_item_group);
-	return 0;
-}
-
 /*! allocate trunk specific stat items
  *  (called once on trunk initialization).
  *  \param[in] trunk for which the stat items are allocated.
@@ -290,8 +316,20 @@ int mgcp_stat_trunk_alloc(struct mgcp_trunk *trunk)
 	snprintf(stat_name, sizeof(stat_name), "%s-%u:common", mgcp_trunk_type_strs_str(trunk->trunk_type),
 		 trunk->trunk_nr);
 	osmo_stat_item_group_set_name(stats->common, stat_name);
-	talloc_set_destructor(stats->common, free_stat_item_group);
 	common_stat_index++;
 
 	return 0;
 }
+
+/*! free trunk specific stat items
+ *  (called once when trunk is freed).
+ *  \param[in] trunk on which the stat items are allocated. */
+void mgcp_stat_trunk_free(struct mgcp_trunk *trunk)
+{
+	struct mgcp_stat_trunk *stats = &trunk->stats;
+
+	if (stats->common) {
+		osmo_stat_item_group_free(stats->common);
+		stats->common = NULL;
+	}
+}

src/libosmo-mgcp/mgcp_trunk.c

@@ -35,7 +35,17 @@ const struct value_string mgcp_trunk_type_strs[] = {
 	{ 0, NULL }
 };
 
-/*! allocate trunk and add it (if required) to the trunk list.
+/* Free trunk, this function is automatically called by talloc_free when the trunk is freed. It does not free the
+ * endpoints on the trunk, this must be done separately before freeing the trunk. */
+static int trunk_free_talloc_destructor(struct mgcp_trunk *trunk)
+{
+	llist_del(&trunk->entry);
+	mgcp_ratectr_trunk_free(trunk);
+	mgcp_stat_trunk_free(trunk);
+	return 0;
+}
+
+/*! allocate trunk and add it to the trunk list.
  *  (called once at startup by VTY).
  *  \param[in] cfg mgcp configuration.
  *  \param[in] ttype trunk type.
@@ -66,6 +76,7 @@ struct mgcp_trunk *mgcp_trunk_alloc(struct mgcp_config *cfg, enum mgcp_trunk_typ
 
 	mgcp_ratectr_trunk_alloc(trunk);
 	mgcp_stat_trunk_alloc(trunk);
+	talloc_set_destructor(trunk, trunk_free_talloc_destructor);
 
 	return trunk;
 }