* : update signature of thread_cancel api

Change thread_cancel to take a ** to an event, NULL-check
before dereferencing, and NULL the caller's pointer. Update
many callers to use the new signature.

Signed-off-by: Mark Stapp <mjs@voltanet.io>

38 files changed, 144 insertions, 293 deletions

diff --git a/babeld/babeld.c b/babeld/babeld.c
index 09955cfbe..895ede704 100644
--- a/babeld/babeld.c
+++ b/babeld/babeld.c
@@ -317,13 +317,9 @@ babel_clean_routing_process(void)
     flush_all_routes();
     babel_interface_close_all();
 
-    /* cancel threads */
-    if (babel_routing_process->t_read != NULL) {
-        thread_cancel(babel_routing_process->t_read);
-    }
-    if (babel_routing_process->t_update != NULL) {
-        thread_cancel(babel_routing_process->t_update);
-    }
+    /* cancel events */
+    thread_cancel(&babel_routing_process->t_read);
+    thread_cancel(&babel_routing_process->t_update);
 
     distribute_list_delete(&babel_routing_process->distribute_ctx);
     XFREE(MTYPE_BABEL, babel_routing_process);
@@ -503,9 +499,7 @@ static void
 babel_set_timer(struct timeval *timeout)
 {
     long msecs = timeout->tv_sec * 1000 + timeout->tv_usec / 1000;
-    if (babel_routing_process->t_update != NULL) {
-        thread_cancel(babel_routing_process->t_update);
-    }
+    thread_cancel(&(babel_routing_process->t_update));
     thread_add_timer_msec(master, babel_main_loop, NULL, msecs, &babel_routing_process->t_update);
 }
 
diff --git a/bfdd/control.c b/bfdd/control.c
index 3b954c64f..4929bf199 100644
--- a/bfdd/control.c
+++ b/bfdd/control.c
@@ -145,10 +145,7 @@ void control_shutdown(void)
 {
 	struct bfd_control_socket *bcs;
 
-	if (bglobal.bg_csockev) {
-		thread_cancel(bglobal.bg_csockev);
-		bglobal.bg_csockev = NULL;
-	}
+	thread_cancel(&bglobal.bg_csockev);
 
 	socket_close(&bglobal.bg_csock);
 
@@ -204,15 +201,8 @@ static void control_free(struct bfd_control_socket *bcs)
 	struct bfd_control_queue *bcq;
 	struct bfd_notify_peer *bnp;
 
-	if (bcs->bcs_ev) {
-		thread_cancel(bcs->bcs_ev);
-		bcs->bcs_ev = NULL;
-	}
-
-	if (bcs->bcs_outev) {
-		thread_cancel(bcs->bcs_outev);
-		bcs->bcs_outev = NULL;
-	}
+	thread_cancel(&(bcs->bcs_ev));
+	thread_cancel(&(bcs->bcs_outev));
 
 	close(bcs->bcs_sd);
 
@@ -318,10 +308,7 @@ static int control_queue_dequeue(struct bfd_control_socket *bcs)
 	return 1;
 
 empty_list:
-	if (bcs->bcs_outev) {
-		thread_cancel(bcs->bcs_outev);
-		bcs->bcs_outev = NULL;
-	}
+	thread_cancel(&(bcs->bcs_outev));
 	bcs->bcs_bout = NULL;
 	return 0;
 }
diff --git a/bgpd/bgp_damp.c b/bgpd/bgp_damp.c
index 999216818..94a27ead0 100644
--- a/bgpd/bgp_damp.c
+++ b/bgpd/bgp_damp.c
@@ -467,10 +467,8 @@ int bgp_damp_disable(struct bgp *bgp, afi_t afi, safi_t safi)
 	if (!CHECK_FLAG(bgp->af_flags[afi][safi], BGP_CONFIG_DAMPENING))
 		return 0;
 
-	/* Cancel reuse thread. */
-	if (bdc->t_reuse)
-		thread_cancel(bdc->t_reuse);
-	bdc->t_reuse = NULL;
+	/* Cancel reuse event. */
+	thread_cancel(&(bdc->t_reuse));
 
 	/* Clean BGP dampening information.  */
 	bgp_damp_info_clean(afi, safi);
diff --git a/bgpd/bgp_dump.c b/bgpd/bgp_dump.c
index abd349a18..975bba931 100644
--- a/bgpd/bgp_dump.c
+++ b/bgpd/bgp_dump.c
@@ -677,11 +677,8 @@ static int bgp_dump_unset(struct bgp_dump *bgp_dump)
 		bgp_dump->fp = NULL;
 	}
 
-	/* Removing interval thread. */
-	if (bgp_dump->t_interval) {
-		thread_cancel(bgp_dump->t_interval);
-		bgp_dump->t_interval = NULL;
-	}
+	/* Removing interval event. */
+	thread_cancel(&bgp_dump->t_interval);
 
 	bgp_dump->interval = 0;
 
diff --git a/bgpd/bgp_evpn_mh.c b/bgpd/bgp_evpn_mh.c
index 1a58541a7..8f81278de 100644
--- a/bgpd/bgp_evpn_mh.c
+++ b/bgpd/bgp_evpn_mh.c
@@ -2911,7 +2911,7 @@ void bgp_evpn_mh_finish(void)
 			 es_next) {
 		bgp_evpn_es_local_info_clear(es);
 	}
-	thread_cancel(bgp_mh_info->t_cons_check);
+	thread_cancel(&bgp_mh_info->t_cons_check);
 	list_delete(&bgp_mh_info->local_es_list);
 	list_delete(&bgp_mh_info->pend_es_list);
 
diff --git a/bgpd/rfapi/rfapi_import.c b/bgpd/rfapi/rfapi_import.c
index 68d4f622e..e3581adde 100644
--- a/bgpd/rfapi/rfapi_import.c
+++ b/bgpd/rfapi/rfapi_import.c
@@ -858,9 +858,9 @@ static void rfapiBgpInfoChainFree(struct bgp_path_info *bpi)
 		if (CHECK_FLAG(bpi->flags, BGP_PATH_REMOVED)
 		    && bpi->extra->vnc.import.timer) {
 
-			struct thread *t =
-				(struct thread *)bpi->extra->vnc.import.timer;
-			struct rfapi_withdraw *wcb = t->arg;
+			struct thread **t =
+				&(bpi->extra->vnc.import.timer);
+			struct rfapi_withdraw *wcb = (*t)->arg;
 
 			XFREE(MTYPE_RFAPI_WITHDRAW, wcb);
 			thread_cancel(t);
@@ -3093,10 +3093,9 @@ static void rfapiBgpInfoFilteredImportEncap(
 				if (CHECK_FLAG(bpi->flags, BGP_PATH_REMOVED)
 				    && bpi->extra->vnc.import.timer) {
 
-					struct thread *t =
-						(struct thread *)bpi->extra->vnc
-							.import.timer;
-					struct rfapi_withdraw *wcb = t->arg;
+					struct thread **t =
+						&(bpi->extra->vnc.import.timer);
+					struct rfapi_withdraw *wcb = (*t)->arg;
 
 					XFREE(MTYPE_RFAPI_WITHDRAW, wcb);
 					thread_cancel(t);
@@ -3186,9 +3185,9 @@ static void rfapiBgpInfoFilteredImportEncap(
 			"%s: removing holddown bpi matching NVE of new route",
 			__func__);
 		if (bpi->extra->vnc.import.timer) {
-			struct thread *t =
-				(struct thread *)bpi->extra->vnc.import.timer;
-			struct rfapi_withdraw *wcb = t->arg;
+			struct thread **t =
+				&(bpi->extra->vnc.import.timer);
+			struct rfapi_withdraw *wcb = (*t)->arg;
 
 			XFREE(MTYPE_RFAPI_WITHDRAW, wcb);
 			thread_cancel(t);
@@ -3549,10 +3548,9 @@ void rfapiBgpInfoFilteredImportVPN(
 				if (CHECK_FLAG(bpi->flags, BGP_PATH_REMOVED)
 				    && bpi->extra->vnc.import.timer) {
 
-					struct thread *t =
-						(struct thread *)bpi->extra->vnc
-							.import.timer;
-					struct rfapi_withdraw *wcb = t->arg;
+					struct thread **t =
+						&(bpi->extra->vnc.import.timer);
+					struct rfapi_withdraw *wcb = (*t)->arg;
 
 					XFREE(MTYPE_RFAPI_WITHDRAW, wcb);
 					thread_cancel(t);
@@ -3768,9 +3766,9 @@ void rfapiBgpInfoFilteredImportVPN(
 			"%s: removing holddown bpi matching NVE of new route",
 			__func__);
 		if (bpi->extra->vnc.import.timer) {
-			struct thread *t =
-				(struct thread *)bpi->extra->vnc.import.timer;
-			struct rfapi_withdraw *wcb = t->arg;
+			struct thread **t =
+				&(bpi->extra->vnc.import.timer);
+			struct rfapi_withdraw *wcb = (*t)->arg;
 
 			XFREE(MTYPE_RFAPI_WITHDRAW, wcb);
 			thread_cancel(t);
@@ -4498,12 +4496,11 @@ static void rfapiDeleteRemotePrefixesIt(
 						continue;
 					if (bpi->extra->vnc.import.timer) {
 
-						struct thread *t =
-							(struct thread *)bpi
-								->extra->vnc
-								.import.timer;
+						struct thread **t =
+							&(bpi->extra->vnc
+								.import.timer);
 						struct rfapi_withdraw *wcb =
-							t->arg;
+							(*t)->arg;
 
 						wcb->import_table
 							->holddown_count[afi] -=
diff --git a/bgpd/rfapi/rfapi_monitor.c b/bgpd/rfapi/rfapi_monitor.c
index a4b0eff03..ce916c104 100644
--- a/bgpd/rfapi/rfapi_monitor.c
+++ b/bgpd/rfapi/rfapi_monitor.c
@@ -620,10 +620,7 @@ void rfapiMonitorDel(struct bgp *bgp, struct rfapi_descriptor *rfd,
 		rfapiMonitorDetachImport(m);
 	}
 
-	if (m->timer) {
-		thread_cancel(m->timer);
-		m->timer = NULL;
-	}
+	thread_cancel(&m->timer);
 
 	/*
 	 * remove from rfd list
@@ -660,10 +657,7 @@ int rfapiMonitorDelHd(struct rfapi_descriptor *rfd)
 					rfapiMonitorDetachImport(m);
 				}
 
-				if (m->timer) {
-					thread_cancel(m->timer);
-					m->timer = NULL;
-				}
+				thread_cancel(&m->timer);
 
 				XFREE(MTYPE_RFAPI_MONITOR, m);
 				rn->info = NULL;
@@ -697,10 +691,7 @@ int rfapiMonitorDelHd(struct rfapi_descriptor *rfd)
 #endif
 			}
 
-			if (mon_eth->timer) {
-				thread_cancel(mon_eth->timer);
-				mon_eth->timer = NULL;
-			}
+			thread_cancel(&mon_eth->timer);
 
 			/*
 			 * remove from rfd list
@@ -766,8 +757,7 @@ static void rfapiMonitorTimerRestart(struct rfapi_monitor_vpn *m)
 		if (m->rfd->response_lifetime - remain < 2)
 			return;
 
-		thread_cancel(m->timer);
-		m->timer = NULL;
+		thread_cancel(&m->timer);
 	}
 
 	{
@@ -1078,8 +1068,7 @@ static void rfapiMonitorEthTimerRestart(struct rfapi_monitor_eth *m)
 		if (m->rfd->response_lifetime - remain < 2)
 			return;
 
-		thread_cancel(m->timer);
-		m->timer = NULL;
+		thread_cancel(&m->timer);
 	}
 
 	{
@@ -1418,10 +1407,7 @@ void rfapiMonitorEthDel(struct bgp *bgp, struct rfapi_descriptor *rfd,
 		rfapiMonitorEthDetachImport(bgp, val);
 	}
 
-	if (val->timer) {
-		thread_cancel(val->timer);
-		val->timer = NULL;
-	}
+	thread_cancel(&val->timer);
 
 	/*
 	 * remove from rfd list
diff --git a/bgpd/rfapi/rfapi_rib.c b/bgpd/rfapi/rfapi_rib.c
index 09832b32a..630a379ec 100644
--- a/bgpd/rfapi/rfapi_rib.c
+++ b/bgpd/rfapi/rfapi_rib.c
@@ -269,9 +269,8 @@ static void rfapi_info_free(struct rfapi_info *goner)
 			struct rfapi_rib_tcb *tcb;
 
 			tcb = goner->timer->arg;
-			thread_cancel(goner->timer);
+			thread_cancel(&goner->timer);
 			XFREE(MTYPE_RFAPI_RECENT_DELETE, tcb);
-			goner->timer = NULL;
 		}
 		XFREE(MTYPE_RFAPI_INFO, goner);
 	}
@@ -338,13 +337,11 @@ static void rfapiRibStartTimer(struct rfapi_descriptor *rfd,
 			       struct agg_node *rn, /* route node attached to */
 			       int deleted)
 {
-	struct thread *t = ri->timer;
 	struct rfapi_rib_tcb *tcb = NULL;
 
-	if (t) {
-		tcb = t->arg;
-		thread_cancel(t);
-		ri->timer = NULL;
+	if (ri->timer) {
+		tcb = ri->timer->arg;
+		thread_cancel(&ri->timer);
 	} else {
 		tcb = XCALLOC(MTYPE_RFAPI_RECENT_DELETE,
 			      sizeof(struct rfapi_rib_tcb));
@@ -917,10 +914,9 @@ static void process_pending_node(struct bgp *bgp, struct rfapi_descriptor *rfd,
 				if (ri->timer) {
 					struct rfapi_rib_tcb *tcb;
 
-					tcb = ((struct thread *)ri->timer)->arg;
-					thread_cancel(ri->timer);
+					tcb = ri->timer->arg;
+					thread_cancel(&ri->timer);
 					XFREE(MTYPE_RFAPI_RECENT_DELETE, tcb);
-					ri->timer = NULL;
 				}
 
 				vnc_zlog_debug_verbose(
@@ -1003,11 +999,9 @@ static void process_pending_node(struct bgp *bgp, struct rfapi_descriptor *rfd,
 				if (ori->timer) {
 					struct rfapi_rib_tcb *tcb;
 
-					tcb = ((struct thread *)ori->timer)
-						      ->arg;
-					thread_cancel(ori->timer);
+					tcb = ori->timer->arg;
+					thread_cancel(&ori->timer);
 					XFREE(MTYPE_RFAPI_RECENT_DELETE, tcb);
-					ori->timer = NULL;
 				}
 
 #if DEBUG_PROCESS_PENDING_NODE
@@ -1351,11 +1345,9 @@ callback:
 				if (ri->timer) {
 					struct rfapi_rib_tcb *tcb;
 
-					tcb = ((struct thread *)ri->timer)->arg;
-					thread_cancel(
-						(struct thread *)ri->timer);
+					tcb = ri->timer->arg;
+					thread_cancel(&ri->timer);
 					XFREE(MTYPE_RFAPI_RECENT_DELETE, tcb);
-					ri->timer = NULL;
 				}
 				RFAPI_RIB_CHECK_COUNTS(0, delete_list->count);
 
diff --git a/bgpd/rfapi/vnc_export_bgp.c b/bgpd/rfapi/vnc_export_bgp.c
index b56261669..11f39b2b8 100644
--- a/bgpd/rfapi/vnc_export_bgp.c
+++ b/bgpd/rfapi/vnc_export_bgp.c
@@ -1711,14 +1711,11 @@ void vnc_direct_bgp_rh_add_route(struct bgp *bgp, afi_t afi,
 	rfapiGetVncLifetime(attr, &eti->lifetime);
 	eti->lifetime = rfapiGetHolddownFromLifetime(eti->lifetime);
 
-	if (eti->timer) {
-		/*
-		 * export expiration timer is already running on
-		 * this route: cancel it
-		 */
-		thread_cancel(eti->timer);
-		eti->timer = NULL;
-	}
+	/*
+	 * export expiration timer is already running on
+	 * this route: cancel it
+	 */
+	thread_cancel(&eti->timer);
 
 	bgp_update(peer, prefix, /* prefix */
 		   0,		 /* addpath_id */
@@ -1947,15 +1944,12 @@ void vnc_direct_bgp_rh_vpn_enable(struct bgp *bgp, afi_t afi)
 					rfapiGetVncLifetime(ri->attr,
 							    &eti->lifetime);
 
-					if (eti->timer) {
-						/*
-						 * export expiration timer is
-						 * already running on
-						 * this route: cancel it
-						 */
-						thread_cancel(eti->timer);
-						eti->timer = NULL;
-					}
+					/*
+					 * export expiration timer is
+					 * already running on
+					 * this route: cancel it
+					 */
+					thread_cancel(&eti->timer);
 
 					vnc_zlog_debug_verbose(
 						"%s: calling bgp_update",
@@ -2024,8 +2018,7 @@ void vnc_direct_bgp_rh_vpn_disable(struct bgp *bgp, afi_t afi)
 					ZEBRA_ROUTE_VNC_DIRECT_RH,
 					BGP_ROUTE_REDISTRIBUTE);
 				if (eti) {
-					if (eti->timer)
-						thread_cancel(eti->timer);
+					thread_cancel(&eti->timer);
 					vnc_eti_delete(eti);
 				}
 
diff --git a/eigrpd/eigrp_filter.c b/eigrpd/eigrp_filter.c
index 9d5d45ca5..010fd2d3a 100644
--- a/eigrpd/eigrp_filter.c
+++ b/eigrpd/eigrp_filter.c
@@ -159,13 +159,10 @@ void eigrp_distribute_update(struct distribute_ctx *ctx,
 #endif
 		// TODO: check Graceful restart after 10sec
 
-		/* check if there is already GR scheduled */
-		if (e->t_distribute != NULL) {
-			/* if is, cancel schedule */
-			thread_cancel(e->t_distribute);
-		}
+      		/* cancel GR scheduled */
+      		thread_cancel(&(e->t_distribute));
+
 		/* schedule Graceful restart for whole process in 10sec */
-		e->t_distribute = NULL;
 		thread_add_timer(master, eigrp_distribute_timer_process, e,
 				 (10), &e->t_distribute);
 
@@ -267,11 +264,8 @@ void eigrp_distribute_update(struct distribute_ctx *ctx,
 #endif
 	// TODO: check Graceful restart after 10sec
 
-	/* check if there is already GR scheduled */
-	if (ei->t_distribute != NULL) {
-		/* if is, cancel schedule */
-		thread_cancel(ei->t_distribute);
-	}
+  	/* Cancel GR scheduled */
+	thread_cancel(&(ei->t_distribute));
 	/* schedule Graceful restart for interface in 10sec */
 	e->t_distribute = NULL;
 	thread_add_timer(master, eigrp_distribute_timer_interface, ei, 10,
diff --git a/eigrpd/eigrp_interface.c b/eigrpd/eigrp_interface.c
index 2f3f34742..e7c6b2e07 100644
--- a/eigrpd/eigrp_interface.c
+++ b/eigrpd/eigrp_interface.c
@@ -358,7 +358,7 @@ void eigrp_if_stream_unset(struct eigrp_interface *ei)
 	if (ei->on_write_q) {
 		listnode_delete(eigrp->oi_write_q, ei);
 		if (list_isempty(eigrp->oi_write_q))
-			thread_cancel(eigrp->t_write);
+			thread_cancel(&(eigrp->t_write));
 		ei->on_write_q = 0;
 	}
 }
diff --git a/isisd/fabricd.c b/isisd/fabricd.c
index 1a081bbea..57e9e91c1 100644
--- a/isisd/fabricd.c
+++ b/isisd/fabricd.c
@@ -239,14 +239,11 @@ struct fabricd *fabricd_new(struct isis_area *area)
 
 void fabricd_finish(struct fabricd *f)
 {
-	if (f->initial_sync_timeout)
-		thread_cancel(f->initial_sync_timeout);
+	thread_cancel(&(f->initial_sync_timeout));
 
-	if (f->tier_calculation_timer)
-		thread_cancel(f->tier_calculation_timer);
+	thread_cancel(&(f->tier_calculation_timer));
 
-	if (f->tier_set_timer)
-		thread_cancel(f->tier_set_timer);
+	thread_cancel(&(f->tier_set_timer));
 
 	isis_spftree_del(f->spftree);
 	neighbor_lists_clear(f);
@@ -340,8 +337,7 @@ void fabricd_initial_sync_finish(struct isis_area *area)
 		  f->initial_sync_circuit->interface->name);
 	f->initial_sync_state = FABRICD_SYNC_COMPLETE;
 	f->initial_sync_circuit = NULL;
-	thread_cancel(f->initial_sync_timeout);
-	f->initial_sync_timeout = NULL;
+	thread_cancel(&(f->initial_sync_timeout));
 }
 
 static void fabricd_bump_tier_calculation_timer(struct fabricd *f);
@@ -437,22 +433,15 @@ static int fabricd_tier_calculation_cb(struct thread *thread)
 static void fabricd_bump_tier_calculation_timer(struct fabricd *f)
 {
 	/* Cancel timer if we already know our tier */
-	if (f->tier != ISIS_TIER_UNDEFINED
-	    || f->tier_set_timer) {
-		if (f->tier_calculation_timer) {
-			thread_cancel(f->tier_calculation_timer);
-			f->tier_calculation_timer = NULL;
-		}
+	if (f->tier != ISIS_TIER_UNDEFINED || f->tier_set_timer) {
+		thread_cancel(&(f->tier_calculation_timer));
 		return;
 	}
 
 	/* If we need to calculate the tier, wait some
 	 * time for the topology to settle before running
 	 * the calculation */
-	if (f->tier_calculation_timer) {
-		thread_cancel(f->tier_calculation_timer);
-		f->tier_calculation_timer = NULL;
-	}
+	thread_cancel(&(f->tier_calculation_timer));
 
 	thread_add_timer(master, fabricd_tier_calculation_cb, f,
 			 2 * f->area->lsp_gen_interval[ISIS_LEVEL2 - 1],
@@ -737,7 +726,7 @@ void fabricd_trigger_csnp(struct isis_area *area, bool circuit_scoped)
 		if (!circuit->t_send_csnp[1])
 			continue;
 
-		thread_cancel(circuit->t_send_csnp[ISIS_LEVEL2 - 1]);
+		thread_cancel(&(circuit->t_send_csnp[ISIS_LEVEL2 - 1]));
 		thread_add_timer_msec(master, send_l2_csnp, circuit,
 				      isis_jitter(f->csnp_delay, CSNP_JITTER),
 				      &circuit->t_send_csnp[ISIS_LEVEL2 - 1]);
diff --git a/isisd/isis_pdu.c b/isisd/isis_pdu.c
index d6f257117..63be8841c 100644
--- a/isisd/isis_pdu.c
+++ b/isisd/isis_pdu.c
@@ -1987,7 +1987,7 @@ static void _send_hello_sched(struct isis_circuit *circuit,
 		if (thread_timer_remain_msec(*threadp) < (unsigned long)delay)
 			return;
 
-		thread_cancel(*threadp);
+		thread_cancel(threadp);
 	}
 
 	thread_add_timer_msec(master, send_hello_cb,
diff --git a/isisd/isis_tx_queue.c b/isisd/isis_tx_queue.c
index 1424b55bd..5c87e3915 100644
--- a/isisd/isis_tx_queue.c
+++ b/isisd/isis_tx_queue.c
@@ -93,8 +93,7 @@ static void tx_queue_element_free(void *element)
 {
 	struct isis_tx_queue_entry *e = element;
 
-	if (e->retry)
-		thread_cancel(e->retry);
+	thread_cancel(&(e->retry));
 
 	XFREE(MTYPE_TX_QUEUE_ENTRY, e);
 }
@@ -166,8 +165,7 @@ void _isis_tx_queue_add(struct isis_tx_queue *queue,
 
 	e->type = type;
 
-	if (e->retry)
-		thread_cancel(e->retry);
+	thread_cancel(&(e->retry));
 	thread_add_event(master, tx_queue_send_event, e, 0, &e->retry);
 
 	e->is_retry = false;
@@ -190,8 +188,7 @@ void _isis_tx_queue_del(struct isis_tx_queue *queue, struct isis_lsp *lsp,
 			   func, file, line);
 	}
 
-	if (e->retry)
-		thread_cancel(e->retry);
+	thread_cancel(&(e->retry));
 
 	hash_release(queue->hash, e);
 	XFREE(MTYPE_TX_QUEUE_ENTRY, e);
diff --git a/lib/agentx.c b/lib/agentx.c
index 7c4bdcbe2..07f146bae 100644
--- a/lib/agentx.c
+++ b/lib/agentx.c
@@ -130,7 +130,7 @@ static void agentx_events_update(void)
 		if (thr_fd == fd) {
 			struct listnode *nextln = listnextnode(ln);
 			if (!FD_ISSET(fd, &fds)) {
-				thread_cancel(thr);
+				thread_cancel(&thr);
 				list_delete_node(events, ln);
 			}
 			ln = nextln;
@@ -151,7 +151,8 @@ static void agentx_events_update(void)
 	 */
 	while (ln) {
 		struct listnode *nextln = listnextnode(ln);
-		thread_cancel(listgetdata(ln));
+		thr = listgetdata(ln);
+		thread_cancel(&thr);
 		list_delete_node(events, ln);
 		ln = nextln;
 	}
diff --git a/lib/frr_zmq.c b/lib/frr_zmq.c
index 565936a41..cc11d7670 100644
--- a/lib/frr_zmq.c
+++ b/lib/frr_zmq.c
@@ -190,10 +190,8 @@ int funcname_frrzmq_thread_add_read(struct thread_master *master,
 	cb->read.cancelled = false;
 
 	if (events & ZMQ_POLLIN) {
-		if (cb->read.thread) {
-			thread_cancel(cb->read.thread);
-			cb->read.thread = NULL;
-		}
+		thread_cancel(&cb->read.thread);
+
 		funcname_thread_add_event(master, frrzmq_read_msg, cbp, fd,
 					  &cb->read.thread, funcname, schedfrom,
 					  fromln);
@@ -298,10 +296,8 @@ int funcname_frrzmq_thread_add_write(struct thread_master *master,
 	cb->write.cancelled = false;
 
 	if (events & ZMQ_POLLOUT) {
-		if (cb->write.thread) {
-			thread_cancel(cb->write.thread);
-			cb->write.thread = NULL;
-		}
+		thread_cancel(&cb->write.thread);
+
 		funcname_thread_add_event(master, frrzmq_write_msg, cbp, fd,
 					  &cb->write.thread, funcname,
 					  schedfrom, fromln);
@@ -317,10 +313,8 @@ void frrzmq_thread_cancel(struct frrzmq_cb **cb, struct cb_core *core)
 	if (!cb || !*cb)
 		return;
 	core->cancelled = true;
-	if (core->thread) {
-		thread_cancel(core->thread);
-		core->thread = NULL;
-	}
+	thread_cancel(&core->thread);
+
 	if ((*cb)->read.cancelled && !(*cb)->read.thread
 	    && (*cb)->write.cancelled && (*cb)->write.thread)
 		XFREE(MTYPE_ZEROMQ_CB, *cb);
@@ -344,8 +338,8 @@ void frrzmq_check_events(struct frrzmq_cb **cbp, struct cb_core *core,
 		return;
 	if (events & event && core->thread && !core->cancelled) {
 		struct thread_master *tm = core->thread->master;
-		thread_cancel(core->thread);
-		core->thread = NULL;
+		thread_cancel(&core->thread);
+
 		thread_add_event(tm, (event == ZMQ_POLLIN ? frrzmq_read_msg
 							  : frrzmq_write_msg),
 				 cbp, cb->fd, &core->thread);
diff --git a/lib/thread.c b/lib/thread.c
index db35a3f03..90c6c6f0a 100644
--- a/lib/thread.c
+++ b/lib/thread.c
@@ -1163,19 +1163,26 @@ void thread_cancel_event(struct thread_master *master, void *arg)
  *
  * @param thread task to cancel
  */
-void thread_cancel(struct thread *thread)
+void thread_cancel(struct thread **thread)
 {
-	struct thread_master *master = thread->master;
+	struct thread_master *master;
+
+	if (thread == NULL || *thread == NULL)
+		return;
+
+	master = (*thread)->master;
 
 	assert(master->owner == pthread_self());
 
 	frr_with_mutex(&master->mtx) {
 		struct cancel_req *cr =
 			XCALLOC(MTYPE_TMP, sizeof(struct cancel_req));
-		cr->thread = thread;
+		cr->thread = *thread;
 		listnode_add(master->cancel_req, cr);
 		do_thread_cancel(master);
 	}
+
+	*thread = NULL;
 }
 
 /**
diff --git a/lib/thread.h b/lib/thread.h
index c22b2105c..a581796d3 100644
--- a/lib/thread.h
+++ b/lib/thread.h
@@ -89,6 +89,8 @@ struct thread_master {
 	pthread_t owner;
 };
 
+typedef struct thread_master event_master;
+
 /* Thread itself. */
 struct thread {
 	uint8_t type;		  /* thread type */
@@ -147,17 +149,10 @@ struct cpu_thread_history {
 #define THREAD_FD(X)  ((X)->u.fd)
 #define THREAD_VAL(X) ((X)->u.val)
 
-#define THREAD_OFF(thread)                                                     \
-	do {                                                                   \
-		if (thread) {                                                  \
-			thread_cancel(thread);                                 \
-			thread = NULL;                                         \
-		}                                                              \
-	} while (0)
-
-#define THREAD_READ_OFF(thread)  THREAD_OFF(thread)
-#define THREAD_WRITE_OFF(thread)  THREAD_OFF(thread)
-#define THREAD_TIMER_OFF(thread)  THREAD_OFF(thread)
+#define THREAD_OFF(thread) thread_cancel(&(thread))
+#define THREAD_READ_OFF(thread)  thread_cancel(&(thread))
+#define THREAD_WRITE_OFF(thread)  thread_cancel(&(thread))
+#define THREAD_TIMER_OFF(thread)  thread_cancel(&(thread))
 
 #define debugargdef  const char *funcname, const char *schedfrom, int fromln
 
@@ -207,7 +202,7 @@ extern void funcname_thread_execute(struct thread_master *,
 				    debugargdef);
 #undef debugargdef
 
-extern void thread_cancel(struct thread *);
+extern void thread_cancel(struct thread **event);
 extern void thread_cancel_async(struct thread_master *, struct thread **,
 				void *);
 extern void thread_cancel_event(struct thread_master *, void *);
diff --git a/lib/workqueue.c b/lib/workqueue.c
index 54090d0d0..f8e467722 100644
--- a/lib/workqueue.c
+++ b/lib/workqueue.c
@@ -104,7 +104,7 @@ void work_queue_free_and_null(struct work_queue **wqp)
 	struct work_queue *wq = *wqp;
 
 	if (wq->thread != NULL)
-		thread_cancel(wq->thread);
+		thread_cancel(&(wq->thread));
 
 	while (!work_queue_empty(wq)) {
 		struct work_queue_item *item = work_queue_last_item(wq);
@@ -215,7 +215,7 @@ void workqueue_cmd_init(void)
 void work_queue_plug(struct work_queue *wq)
 {
 	if (wq->thread)
-		thread_cancel(wq->thread);
+		thread_cancel(&(wq->thread));
 
 	wq->thread = NULL;
 
diff --git a/ospfd/ospf_apiserver.c b/ospfd/ospf_apiserver.c
index 9d3493e91..c01ecdd1d 100644
--- a/ospfd/ospf_apiserver.c
+++ b/ospfd/ospf_apiserver.c
@@ -317,21 +317,12 @@ void ospf_apiserver_free(struct ospf_apiserver *apiserv)
 	struct listnode *node;
 
 	/* Cancel read and write threads. */
-	if (apiserv->t_sync_read) {
-		thread_cancel(apiserv->t_sync_read);
-	}
+	thread_cancel(&apiserv->t_sync_read);
 #ifdef USE_ASYNC_READ
-	if (apiserv->t_async_read) {
-		thread_cancel(apiserv->t_async_read);
-	}
+	thread_cancel(&apiserv->t_async_read);
 #endif /* USE_ASYNC_READ */
-	if (apiserv->t_sync_write) {
-		thread_cancel(apiserv->t_sync_write);
-	}
-
-	if (apiserv->t_async_write) {
-		thread_cancel(apiserv->t_async_write);
-	}
+	thread_cancel(&apiserv->t_sync_write);
+	thread_cancel(&apiserv->t_async_write);
 
 	/* Unregister all opaque types that application registered
 	   and flush opaque LSAs if still in LSDB. */
diff --git a/ospfd/ospf_ism.h b/ospfd/ospf_ism.h
index 67ea4c468..6c0df9a1e 100644
--- a/ospfd/ospf_ism.h
+++ b/ospfd/ospf_ism.h
@@ -79,13 +79,7 @@
 	} while (0)
 
 /* Macro for OSPF ISM timer turn off. */
-#define OSPF_ISM_TIMER_OFF(X)                                                  \
-	do {                                                                   \
-		if (X) {                                                       \
-			thread_cancel(X);                                      \
-			(X) = NULL;                                            \
-		}                                                              \
-	} while (0)
+#define OSPF_ISM_TIMER_OFF(X) thread_cancel(&(X));
 
 /* Macro for OSPF schedule event. */
 #define OSPF_ISM_EVENT_SCHEDULE(I, E)                                          \
diff --git a/ospfd/ospf_nsm.h b/ospfd/ospf_nsm.h
index c219ba738..24cf05009 100644
--- a/ospfd/ospf_nsm.h
+++ b/ospfd/ospf_nsm.h
@@ -59,13 +59,7 @@
 #define OSPF_NSM_TIMER_ON(T,F,V) thread_add_timer (master, (F), nbr, (V), &(T))
 
 /* Macro for OSPF NSM timer turn off. */
-#define OSPF_NSM_TIMER_OFF(X)                                                  \
-	do {                                                                   \
-		if (X) {                                                       \
-			thread_cancel(X);                                      \
-			(X) = NULL;                                            \
-		}                                                              \
-	} while (0)
+#define OSPF_NSM_TIMER_OFF(X) thread_cancel(&(X))
 
 /* Macro for OSPF NSM schedule event. */
 #define OSPF_NSM_EVENT_SCHEDULE(N, E)                                          \
diff --git a/ospfd/ospf_packet.c b/ospfd/ospf_packet.c
index 8cb0062ea..ef39b6c2f 100644
--- a/ospfd/ospf_packet.c
+++ b/ospfd/ospf_packet.c
@@ -468,11 +468,7 @@ static int ospf_ls_req_timer(struct thread *thread)
 
 void ospf_ls_req_event(struct ospf_neighbor *nbr)
 {
-	if (nbr->t_ls_req) {
-		thread_cancel(nbr->t_ls_req);
-		nbr->t_ls_req = NULL;
-	}
-	nbr->t_ls_req = NULL;
+	thread_cancel(&nbr->t_ls_req);
 	thread_add_event(master, ospf_ls_req_timer, nbr, 0, &nbr->t_ls_req);
 }
 
diff --git a/ospfd/ospfd.c b/ospfd/ospfd.c
index ce3bc33c1..3718f82c0 100644
--- a/ospfd/ospfd.c
+++ b/ospfd/ospfd.c
@@ -1324,10 +1324,7 @@ void ospf_ls_upd_queue_empty(struct ospf_interface *oi)
 		}
 
 	/* remove update event */
-	if (oi->t_ls_upd_event) {
-		thread_cancel(oi->t_ls_upd_event);
-		oi->t_ls_upd_event = NULL;
-	}
+	thread_cancel(&oi->t_ls_upd_event);
 }
 
 void ospf_if_update(struct ospf *ospf, struct interface *ifp)
@@ -2158,7 +2155,7 @@ static int ospf_vrf_disable(struct vrf *vrf)
 		if (IS_DEBUG_OSPF_EVENT)
 			zlog_debug("%s: ospf old_vrf_id %d unlinked", __func__,
 				   old_vrf_id);
-		thread_cancel(ospf->t_read);
+		thread_cancel(&ospf->t_read);
 		close(ospf->fd);
 		ospf->fd = -1;
 	}
diff --git a/ospfd/ospfd.h b/ospfd/ospfd.h
index 5009355d4..5535cb40a 100644
--- a/ospfd/ospfd.h
+++ b/ospfd/ospfd.h
@@ -535,13 +535,7 @@ struct ospf_nbr_nbma {
 #define OSPF_AREA_TIMER_ON(T,F,V) thread_add_timer (master, (F), area, (V), &(T))
 #define OSPF_POLL_TIMER_ON(T,F,V) thread_add_timer (master, (F), nbr_nbma, (V), &(T))
 #define OSPF_POLL_TIMER_OFF(X) OSPF_TIMER_OFF((X))
-#define OSPF_TIMER_OFF(X)                                                      \
-	do {                                                                   \
-		if (X) {                                                       \
-			thread_cancel(X);                                      \
-			(X) = NULL;                                            \
-		}                                                              \
-	} while (0)
+#define OSPF_TIMER_OFF(X) thread_cancel(&(X))
 
 /* Extern variables. */
 extern struct ospf_master *om;
diff --git a/ripd/rip_interface.c b/ripd/rip_interface.c
index c2cee4d69..c601ab404 100644
--- a/ripd/rip_interface.c
+++ b/ripd/rip_interface.c
@@ -468,10 +468,7 @@ static void rip_interface_clean(struct rip_interface *ri)
 	ri->enable_interface = 0;
 	ri->running = 0;
 
-	if (ri->t_wakeup) {
-		thread_cancel(ri->t_wakeup);
-		ri->t_wakeup = NULL;
-	}
+	thread_cancel(&ri->t_wakeup);
 }
 
 void rip_interfaces_clean(struct rip *rip)
diff --git a/ripd/rip_peer.c b/ripd/rip_peer.c
index 4c5233c82..23599f087 100644
--- a/ripd/rip_peer.c
+++ b/ripd/rip_peer.c
@@ -86,8 +86,7 @@ static struct rip_peer *rip_peer_get(struct rip *rip, struct in_addr *addr)
 	peer = rip_peer_lookup(rip, addr);
 
 	if (peer) {
-		if (peer->t_timeout)
-			thread_cancel(peer->t_timeout);
+		thread_cancel(&peer->t_timeout);
 	} else {
 		peer = rip_peer_new();
 		peer->rip = rip;
diff --git a/ripngd/ripng_interface.c b/ripngd/ripng_interface.c
index 16859c2d2..115d7a6b9 100644
--- a/ripngd/ripng_interface.c
+++ b/ripngd/ripng_interface.c
@@ -321,10 +321,7 @@ void ripng_interface_clean(struct ripng *ripng)
 		ri->enable_interface = 0;
 		ri->running = 0;
 
-		if (ri->t_wakeup) {
-			thread_cancel(ri->t_wakeup);
-			ri->t_wakeup = NULL;
-		}
+		thread_cancel(&ri->t_wakeup);
 	}
 }
 
diff --git a/ripngd/ripng_peer.c b/ripngd/ripng_peer.c
index e6ff58dd0..0ac489c67 100644
--- a/ripngd/ripng_peer.c
+++ b/ripngd/ripng_peer.c
@@ -95,8 +95,7 @@ static struct ripng_peer *ripng_peer_get(struct ripng *ripng,
 	peer = ripng_peer_lookup(ripng, addr);
 
 	if (peer) {
-		if (peer->t_timeout)
-			thread_cancel(peer->t_timeout);
+		thread_cancel(&peer->t_timeout);
 	} else {
 		peer = ripng_peer_new();
 		peer->ripng = ripng;
@@ -105,7 +104,6 @@ static struct ripng_peer *ripng_peer_get(struct ripng *ripng,
 	}
 
 	/* Update timeout thread. */
-	peer->t_timeout = NULL;
 	thread_add_timer(master, ripng_peer_timeout, peer,
 			 RIPNG_PEER_TIMER_DEFAULT, &peer->t_timeout);
 
diff --git a/ripngd/ripngd.c b/ripngd/ripngd.c
index 060477010..8d9249e4a 100644
--- a/ripngd/ripngd.c
+++ b/ripngd/ripngd.c
@@ -1463,10 +1463,7 @@ static int ripng_update(struct thread *t)
 
 	/* Triggered updates may be suppressed if a regular update is due by
 	   the time the triggered update would be sent. */
-	if (ripng->t_triggered_interval) {
-		thread_cancel(ripng->t_triggered_interval);
-		ripng->t_triggered_interval = NULL;
-	}
+	thread_cancel(&ripng->t_triggered_interval);
 	ripng->trigger = 0;
 
 	/* Reset flush event. */
@@ -1500,10 +1497,7 @@ int ripng_triggered_update(struct thread *t)
 	ripng->t_triggered_update = NULL;
 
 	/* Cancel interval timer. */
-	if (ripng->t_triggered_interval) {
-		thread_cancel(ripng->t_triggered_interval);
-		ripng->t_triggered_interval = NULL;
-	}
+	thread_cancel(&ripng->t_triggered_interval);
 	ripng->trigger = 0;
 
 	/* Logging triggered update. */
@@ -1952,10 +1946,8 @@ void ripng_event(struct ripng *ripng, enum ripng_event event, int sock)
 				&ripng->t_read);
 		break;
 	case RIPNG_UPDATE_EVENT:
-		if (ripng->t_update) {
-			thread_cancel(ripng->t_update);
-			ripng->t_update = NULL;
-		}
+		thread_cancel(&ripng->t_update);
+
 		/* Update timer jitter. */
 		jitter = ripng_update_jitter(ripng->update_time);
 
@@ -2719,10 +2711,7 @@ static void ripng_instance_disable(struct ripng *ripng)
 	RIPNG_TIMER_OFF(ripng->t_triggered_interval);
 
 	/* Cancel the read thread */
-	if (ripng->t_read) {
-		thread_cancel(ripng->t_read);
-		ripng->t_read = NULL;
-	}
+	thread_cancel(&ripng->t_read);
 
 	/* Close the RIPng socket */
 	if (ripng->sock >= 0) {
diff --git a/ripngd/ripngd.h b/ripngd/ripngd.h
index 70508d5cb..97291829b 100644
--- a/ripngd/ripngd.h
+++ b/ripngd/ripngd.h
@@ -351,13 +351,7 @@ enum ripng_event {
 /* RIPng timer on/off macro. */
 #define RIPNG_TIMER_ON(T,F,V) thread_add_timer (master, (F), rinfo, (V), &(T))
 
-#define RIPNG_TIMER_OFF(T)                                                     \
-	do {                                                                   \
-		if (T) {                                                       \
-			thread_cancel(T);                                      \
-			(T) = NULL;                                            \
-		}                                                              \
-	} while (0)
+#define RIPNG_TIMER_OFF(T)  thread_cancel(&(T));
 
 #define RIPNG_OFFSET_LIST_IN  0
 #define RIPNG_OFFSET_LIST_OUT 1
diff --git a/tests/lib/test_timer_correctness.c b/tests/lib/test_timer_correctness.c
index cbf9b0554..416ea3977 100644
--- a/tests/lib/test_timer_correctness.c
+++ b/tests/lib/test_timer_correctness.c
@@ -153,7 +153,7 @@ int main(int argc, char **argv)
 			continue;
 
 		XFREE(MTYPE_TMP, timers[index]->arg);
-		thread_cancel(timers[index]);
+		thread_cancel(&timers[index]);
 		timers[index] = NULL;
 		timers_pending--;
 	}
diff --git a/tests/lib/test_timer_performance.c b/tests/lib/test_timer_performance.c
index 2960e0d81..45b29b92b 100644
--- a/tests/lib/test_timer_performance.c
+++ b/tests/lib/test_timer_performance.c
@@ -59,7 +59,7 @@ int main(int argc, char **argv)
 		thread_add_timer_msec(master, dummy_func, NULL, 0, &timers[i]);
 	}
 	for (i = 0; i < SCHEDULE_TIMERS; i++)
-		thread_cancel(timers[i]);
+		thread_cancel(&timers[i]);
 
 	monotime(&tv_start);
 
@@ -78,8 +78,7 @@ int main(int argc, char **argv)
 		int index;
 
 		index = prng_rand(prng) % SCHEDULE_TIMERS;
-		if (timers[index])
-			thread_cancel(timers[index]);
+		thread_cancel(&timers[index]);
 		timers[index] = NULL;
 	}
 
diff --git a/watchfrr/watchfrr.c b/watchfrr/watchfrr.c
index af243f7ca..cd5ec6725 100644
--- a/watchfrr/watchfrr.c
+++ b/watchfrr/watchfrr.c
@@ -409,8 +409,8 @@ static void sigchild(void)
 		what = restart->what;
 		restart->pid = 0;
 		gs.numpids--;
-		thread_cancel(restart->t_kill);
-		restart->t_kill = NULL;
+		thread_cancel(&restart->t_kill);
+
 		/* Update restart time to reflect the time the command
 		 * completed. */
 		gettimeofday(&restart->time, NULL);
@@ -678,8 +678,7 @@ static int handle_read(struct thread *t_read)
 			   dmn->name, (long)delay.tv_sec, (long)delay.tv_usec);
 
 	SET_READ_HANDLER(dmn);
-	if (dmn->t_wakeup)
-		thread_cancel(dmn->t_wakeup);
+	thread_cancel(&dmn->t_wakeup);
 	SET_WAKEUP_ECHO(dmn);
 
 	return 0;
@@ -866,9 +865,8 @@ static int phase_hanging(struct thread *t_hanging)
 static void set_phase(restart_phase_t new_phase)
 {
 	gs.phase = new_phase;
-	if (gs.t_phase_hanging)
-		thread_cancel(gs.t_phase_hanging);
-	gs.t_phase_hanging = NULL;
+	thread_cancel(&gs.t_phase_hanging);
+
 	thread_add_timer(master, phase_hanging, NULL, PHASE_TIMEOUT,
 			 &gs.t_phase_hanging);
 }
diff --git a/zebra/irdp_main.c b/zebra/irdp_main.c
index 710a32c45..936206641 100644
--- a/zebra/irdp_main.c
+++ b/zebra/irdp_main.c
@@ -263,9 +263,7 @@ void irdp_advert_off(struct interface *ifp)
 	if (!irdp)
 		return;
 
-	if (irdp->t_advertise)
-		thread_cancel(irdp->t_advertise);
-	irdp->t_advertise = NULL;
+	thread_cancel(&irdp->t_advertise);
 
 	if (ifp->connected)
 		for (ALL_LIST_ELEMENTS(ifp->connected, node, nnode, ifc)) {
@@ -300,9 +298,7 @@ void process_solicit(struct interface *ifp)
 		return;
 
 	irdp->flags |= IF_SOLICIT;
-	if (irdp->t_advertise)
-		thread_cancel(irdp->t_advertise);
-	irdp->t_advertise = NULL;
+	thread_cancel(&irdp->t_advertise);
 
 	timer = (frr_weak_random() % MAX_RESPONSE_DELAY) + 1;
 
diff --git a/zebra/zebra_netns_notify.c b/zebra/zebra_netns_notify.c
index 995fa6fb5..ee2dc7a0e 100644
--- a/zebra/zebra_netns_notify.c
+++ b/zebra/zebra_netns_notify.c
@@ -378,7 +378,7 @@ void zebra_ns_notify_close(void)
 		fd = zebra_netns_notify_current->u.fd;
 
 	if (zebra_netns_notify_current->master != NULL)
-		thread_cancel(zebra_netns_notify_current);
+		thread_cancel(&zebra_netns_notify_current);
 
 	/* auto-removal of notify items */
 	if (fd > 0)
diff --git a/zebra/zebra_ptm.c b/zebra/zebra_ptm.c
index 9a3b567b5..013cb6449 100644
--- a/zebra/zebra_ptm.c
+++ b/zebra/zebra_ptm.c
@@ -156,13 +156,10 @@ void zebra_ptm_finish(void)
 	if (ptm_cb.in_data)
 		free(ptm_cb.in_data);
 
-	/* Release threads. */
-	if (ptm_cb.t_read)
-		thread_cancel(ptm_cb.t_read);
-	if (ptm_cb.t_write)
-		thread_cancel(ptm_cb.t_write);
-	if (ptm_cb.t_timer)
-		thread_cancel(ptm_cb.t_timer);
+	/* Cancel events. */
+	thread_cancel(&ptm_cb.t_read);
+	thread_cancel(&ptm_cb.t_write);
+	thread_cancel(&ptm_cb.t_timer);
 
 	if (ptm_cb.wb)
 		buffer_free(ptm_cb.wb);
diff --git a/zebra/zebra_routemap.c b/zebra/zebra_routemap.c
index 8155f9acf..cf8cd0639 100644
--- a/zebra/zebra_routemap.c
+++ b/zebra/zebra_routemap.c
@@ -1695,7 +1695,7 @@ static void zebra_route_map_set_delay_timer(uint32_t value)
 	if (!value && zebra_t_rmap_update) {
 		/* Event driven route map updates is being disabled */
 		/* But there's a pending timer. Fire it off now */
-		thread_cancel(zebra_t_rmap_update);
+		thread_cancel(&zebra_t_rmap_update);
 		zebra_route_map_update_timer(zebra_t_rmap_update);
 	}
 }