*: Convert list_delete(struct list *) to ** to allow nulling

Convert the list_delete(struct list *) function to use
struct list **.  This is to allow the list pointer to be nulled.

I keep running into uses of this list_delete function where we
forget to set the returned pointer to NULL and attempt to use
it and then experience a crash, usually after the developer
has long since left the building.

Let's make the api explicit in it setting the list pointer
to null.

Cynical Prediction:  This code will expose a attempt
to use the NULL'ed list pointer in some obscure bit
of code.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

10 files changed, 30 insertions, 41 deletions

diff --git a/isisd/isis_circuit.c b/isisd/isis_circuit.c
index 1c1385ab7..4179de1c0 100644
--- a/isisd/isis_circuit.c
+++ b/isisd/isis_circuit.c
@@ -453,19 +453,19 @@ void isis_circuit_if_del(struct isis_circuit *circuit, struct interface *ifp)
 
 	if (circuit->ip_addrs) {
 		assert(listcount(circuit->ip_addrs) == 0);
-		list_delete(circuit->ip_addrs);
+		list_delete_and_null(&circuit->ip_addrs);
 		circuit->ip_addrs = NULL;
 	}
 
 	if (circuit->ipv6_link) {
 		assert(listcount(circuit->ipv6_link) == 0);
-		list_delete(circuit->ipv6_link);
+		list_delete_and_null(&circuit->ipv6_link);
 		circuit->ipv6_link = NULL;
 	}
 
 	if (circuit->ipv6_non_link) {
 		assert(listcount(circuit->ipv6_non_link) == 0);
-		list_delete(circuit->ipv6_non_link);
+		list_delete_and_null(&circuit->ipv6_non_link);
 		circuit->ipv6_non_link = NULL;
 	}
 
@@ -692,22 +692,22 @@ void isis_circuit_down(struct isis_circuit *circuit)
 	if (circuit->circ_type == CIRCUIT_T_BROADCAST) {
 		/* destroy neighbour lists */
 		if (circuit->u.bc.lan_neighs[0]) {
-			list_delete(circuit->u.bc.lan_neighs[0]);
+			list_delete_and_null(&circuit->u.bc.lan_neighs[0]);
 			circuit->u.bc.lan_neighs[0] = NULL;
 		}
 		if (circuit->u.bc.lan_neighs[1]) {
-			list_delete(circuit->u.bc.lan_neighs[1]);
+			list_delete_and_null(&circuit->u.bc.lan_neighs[1]);
 			circuit->u.bc.lan_neighs[1] = NULL;
 		}
 		/* destroy adjacency databases */
 		if (circuit->u.bc.adjdb[0]) {
 			circuit->u.bc.adjdb[0]->del = isis_delete_adj;
-			list_delete(circuit->u.bc.adjdb[0]);
+			list_delete_and_null(&circuit->u.bc.adjdb[0]);
 			circuit->u.bc.adjdb[0] = NULL;
 		}
 		if (circuit->u.bc.adjdb[1]) {
 			circuit->u.bc.adjdb[1]->del = isis_delete_adj;
-			list_delete(circuit->u.bc.adjdb[1]);
+			list_delete_and_null(&circuit->u.bc.adjdb[1]);
 			circuit->u.bc.adjdb[1] = NULL;
 		}
 		if (circuit->u.bc.is_dr[0]) {
@@ -745,8 +745,7 @@ void isis_circuit_down(struct isis_circuit *circuit)
 	THREAD_OFF(circuit->t_read);
 
 	if (circuit->lsp_queue) {
-		list_delete(circuit->lsp_queue);
-		circuit->lsp_queue = NULL;
+		list_delete_and_null(&circuit->lsp_queue);
 	}
 
 	if (circuit->lsp_hash) {
diff --git a/isisd/isis_dr.c b/isisd/isis_dr.c
index 2db827191..84b0bb973 100644
--- a/isisd/isis_dr.c
+++ b/isisd/isis_dr.c
@@ -135,7 +135,7 @@ int isis_dr_elect(struct isis_circuit *circuit, int level)
 
 	if (!adjdb) {
 		zlog_warn("isis_dr_elect() adjdb == NULL");
-		list_delete(list);
+		list_delete_and_null(&list);
 		return ISIS_WARNING;
 	}
 	isis_adj_build_up_list(adjdb, list);
@@ -177,7 +177,7 @@ int isis_dr_elect(struct isis_circuit *circuit, int level)
 		 */
 		if (circuit->u.bc.is_dr[level - 1])
 			retval = isis_dr_resign(circuit, level);
-		list_delete(list);
+		list_delete_and_null(&list);
 		return retval;
 	}
 
@@ -217,7 +217,7 @@ int isis_dr_elect(struct isis_circuit *circuit, int level)
 		if (circuit->u.bc.is_dr[level - 1])
 			retval = isis_dr_resign(circuit, level);
 	}
-	list_delete(list);
+	list_delete_and_null(&list);
 	return retval;
 }
 
diff --git a/isisd/isis_events.c b/isisd/isis_events.c
index 1cc90d031..bc3543992 100644
--- a/isisd/isis_events.c
+++ b/isisd/isis_events.c
@@ -132,10 +132,8 @@ static void circuit_resign_level(struct isis_circuit *circuit, int level)
 		THREAD_TIMER_OFF(circuit->u.bc.t_refresh_pseudo_lsp[idx]);
 		circuit->lsp_regenerate_pending[idx] = 0;
 		circuit->u.bc.run_dr_elect[idx] = 0;
-		if (circuit->u.bc.lan_neighs[idx] != NULL) {
-			list_delete(circuit->u.bc.lan_neighs[idx]);
-			circuit->u.bc.lan_neighs[idx] = NULL;
-		}
+		if (circuit->u.bc.lan_neighs[idx] != NULL)
+			list_delete_and_null(&circuit->u.bc.lan_neighs[idx]);
 	}
 
 	return;
diff --git a/isisd/isis_lsp.c b/isisd/isis_lsp.c
index bee6abfda..07579446a 100644
--- a/isisd/isis_lsp.c
+++ b/isisd/isis_lsp.c
@@ -126,7 +126,7 @@ static void lsp_destroy(struct isis_lsp *lsp)
 	lsp_clear_data(lsp);
 
 	if (LSP_FRAGMENT(lsp->hdr.lsp_id) == 0 && lsp->lspu.frags) {
-		list_delete(lsp->lspu.frags);
+		list_delete_and_null(&lsp->lspu.frags);
 		lsp->lspu.frags = NULL;
 	}
 
@@ -1143,7 +1143,7 @@ static void lsp_build(struct isis_lsp *lsp, struct isis_area *area)
 		frag->tlvs = tlvs;
 	}
 
-	list_delete(fragments);
+	list_delete_and_null(&fragments);
 	lsp_debug("ISIS (%s): LSP construction is complete. Serializing...",
 		  area->area_tag);
 	return;
@@ -1521,7 +1521,7 @@ static void lsp_build_pseudo(struct isis_lsp *lsp, struct isis_circuit *circuit,
 				LSP_PSEUDO_ID(ne_id));
 		}
 	}
-	list_delete(adj_list);
+	list_delete_and_null(&adj_list);
 	return;
 }
 
@@ -1905,7 +1905,7 @@ int lsp_tick(struct thread *thread)
 		}
 	}
 
-	list_delete(lsp_list);
+	list_delete_and_null(&lsp_list);
 
 	return ISIS_OK;
 }
diff --git a/isisd/isis_mt.c b/isisd/isis_mt.c
index 52646c262..d13f2a13f 100644
--- a/isisd/isis_mt.c
+++ b/isisd/isis_mt.c
@@ -151,8 +151,7 @@ void area_mt_init(struct isis_area *area)
 
 void area_mt_finish(struct isis_area *area)
 {
-	list_delete(area->mt_settings);
-	area->mt_settings = NULL;
+	list_delete_and_null(&area->mt_settings);
 }
 
 struct isis_area_mt_setting *area_get_mt_setting(struct isis_area *area,
@@ -275,8 +274,7 @@ void circuit_mt_init(struct isis_circuit *circuit)
 
 void circuit_mt_finish(struct isis_circuit *circuit)
 {
-	list_delete(circuit->mt_settings);
-	circuit->mt_settings = NULL;
+	list_delete_and_null(&circuit->mt_settings);
 }
 
 struct isis_circuit_mt_setting *
diff --git a/isisd/isis_pdu.c b/isisd/isis_pdu.c
index 2f9e3caf1..be989cbab 100644
--- a/isisd/isis_pdu.c
+++ b/isisd/isis_pdu.c
@@ -1292,7 +1292,7 @@ static int process_snp(uint8_t pdu_type, struct isis_circuit *circuit,
 		for (ALL_LIST_ELEMENTS_RO(lsp_list, node, lsp))
 			ISIS_SET_FLAG(lsp->SRMflags, circuit);
 		/* lets free it */
-		list_delete(lsp_list);
+		list_delete_and_null(&lsp_list);
 	}
 
 	retval = ISIS_OK;
diff --git a/isisd/isis_route.c b/isisd/isis_route.c
index ff17572ef..b9605018e 100644
--- a/isisd/isis_route.c
+++ b/isisd/isis_route.c
@@ -289,13 +289,13 @@ static void isis_route_info_delete(struct isis_route_info *route_info)
 	if (route_info->nexthops) {
 		route_info->nexthops->del =
 			(void (*)(void *))isis_nexthop_delete;
-		list_delete(route_info->nexthops);
+		list_delete_and_null(&route_info->nexthops);
 	}
 
 	if (route_info->nexthops6) {
 		route_info->nexthops6->del =
 			(void (*)(void *))isis_nexthop6_delete;
-		list_delete(route_info->nexthops6);
+		list_delete_and_null(&route_info->nexthops6);
 	}
 
 	XFREE(MTYPE_ISIS_ROUTE_INFO, route_info);
diff --git a/isisd/isis_spf.c b/isisd/isis_spf.c
index cd9a0f89b..3008fb6a1 100644
--- a/isisd/isis_spf.c
+++ b/isisd/isis_spf.c
@@ -205,10 +205,8 @@ static void isis_vertex_queue_free(struct isis_vertex_queue *queue)
 	if (queue->insert_counter) {
 		skiplist_free(queue->l.slist);
 		queue->l.slist = NULL;
-	} else {
-		list_delete(queue->l.list);
-		queue->l.list = NULL;
-	}
+	} else
+		list_delete_and_null(&queue->l.list);
 }
 
 static unsigned int isis_vertex_queue_count(struct isis_vertex_queue *queue)
@@ -437,10 +435,8 @@ static struct isis_vertex *isis_vertex_new(void *id, enum vertextype vtype)
 
 static void isis_vertex_del(struct isis_vertex *vertex)
 {
-	list_delete(vertex->Adj_N);
-	vertex->Adj_N = NULL;
-	list_delete(vertex->parents);
-	vertex->parents = NULL;
+	list_delete_and_null(&vertex->Adj_N);
+	list_delete_and_null(&vertex->parents);
 
 	memset(vertex, 0, sizeof(struct isis_vertex));
 	XFREE(MTYPE_ISIS_VERTEX, vertex);
@@ -1038,7 +1034,7 @@ static int isis_spf_preload_tent(struct isis_spftree *spftree,
 			adjdb = circuit->u.bc.adjdb[spftree->level - 1];
 			isis_adj_build_up_list(adjdb, adj_list);
 			if (listcount(adj_list) == 0) {
-				list_delete(adj_list);
+				list_delete_and_null(&adj_list);
 				if (isis->debugs & DEBUG_SPF_EVENTS)
 					zlog_debug(
 						"ISIS-Spf: no L%d adjacencies on circuit %s",
@@ -1102,7 +1098,7 @@ static int isis_spf_preload_tent(struct isis_spftree *spftree,
 						"isis_spf_preload_tent unknow adj type");
 				}
 			}
-			list_delete(adj_list);
+			list_delete_and_null(&adj_list);
 			/*
 			 * Add the pseudonode
 			 */
diff --git a/isisd/isis_tlvs.c b/isisd/isis_tlvs.c
index 25a10e91e..b7389947b 100644
--- a/isisd/isis_tlvs.c
+++ b/isisd/isis_tlvs.c
@@ -2397,8 +2397,7 @@ struct list *isis_fragment_tlvs(struct isis_tlvs *tlvs, size_t size)
 		struct listnode *node;
 		for (ALL_LIST_ELEMENTS_RO(rv, node, fragment_tlvs))
 			isis_free_tlvs(fragment_tlvs);
-		list_delete(rv);
-		rv = NULL;
+		list_delete_and_null(&rv);
 	}
 
 	stream_free(dummy_stream);
diff --git a/isisd/isisd.c b/isisd/isisd.c
index bdc1d836d..5dd348089 100644
--- a/isisd/isisd.c
+++ b/isisd/isisd.c
@@ -220,8 +220,7 @@ int isis_area_destroy(struct vty *vty, const char *area_tag)
 			circuit->ipv6_router = 0;
 			isis_csm_state_change(ISIS_DISABLE, circuit, area);
 		}
-		list_delete(area->circuit_list);
-		area->circuit_list = NULL;
+		list_delete_and_null(&area->circuit_list);
 	}
 
 	if (area->lspdb[0] != NULL) {