10573 define TASKQID_INVALID as (taskq_id)0

Reviewed by: Andy Stormont <astormont@racktopsystems.com>
Reviewed by: Gergő Doma <domag02@gmail.com>
Approved by: Dan McDonald <danmcd@joyent.com>

69 files changed, 185 insertions, 152 deletions

diff --git a/usr/src/lib/libfakekernel/common/taskq.c b/usr/src/lib/libfakekernel/common/taskq.c
index d38eda549a..76962f5a64 100644
--- a/usr/src/lib/libfakekernel/common/taskq.c
+++ b/usr/src/lib/libfakekernel/common/taskq.c
@@ -162,7 +162,7 @@ taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
 	ASSERT(tq->tq_flags & TASKQ_ACTIVE);
 	if ((t = task_alloc(tq, tqflags)) == NULL) {
 		mutex_exit(&tq->tq_lock);
-		return (0);
+		return (TASKQID_INVALID);
 	}
 	if (tqflags & TQ_FRONT) {
 		t->tqent_next = tq->tq_task.tqent_next;
diff --git a/usr/src/uts/common/crypto/api/kcf_random.c b/usr/src/uts/common/crypto/api/kcf_random.c
index 5f84a4952e..64f9e4e68d 100644
--- a/usr/src/uts/common/crypto/api/kcf_random.c
+++ b/usr/src/uts/common/crypto/api/kcf_random.c
@@ -964,7 +964,8 @@ rnd_handler(void *arg)
 		 * cache becomes empty.
 		 */
 		if (taskq_dispatch(system_taskq, rngprov_task,
-		    (void *)(uintptr_t)len, TQ_NOSLEEP | TQ_NOQUEUE) == 0) {
+		    (void *)(uintptr_t)len, TQ_NOSLEEP | TQ_NOQUEUE) ==
+		    TASKQID_INVALID) {
 			rngprov_task_idle = B_TRUE;
 		}
 	}
diff --git a/usr/src/uts/common/crypto/core/kcf_sched.c b/usr/src/uts/common/crypto/core/kcf_sched.c
index f461fe048c..9e079a079e 100644
--- a/usr/src/uts/common/crypto/core/kcf_sched.c
+++ b/usr/src/uts/common/crypto/core/kcf_sched.c
@@ -563,7 +563,7 @@ kcf_resubmit_request(kcf_areq_node_t *areq)
 		taskq_t *taskq = new_pd->pd_taskq;
 
 		if (taskq_dispatch(taskq, process_req_hwp, areq, TQ_NOSLEEP) ==
-		    (taskqid_t)0) {
+		    TASKQID_INVALID) {
 			error = CRYPTO_HOST_MEMORY;
 		} else {
 			error = CRYPTO_QUEUED;
@@ -782,7 +782,7 @@ kcf_submit_request(kcf_provider_desc_t *pd, crypto_ctx_t *ctx,
 
 			if (taskq_dispatch(taskq,
 			    process_req_hwp, areq, TQ_NOSLEEP) ==
-			    (taskqid_t)0) {
+			    TASKQID_INVALID) {
 				error = CRYPTO_HOST_MEMORY;
 				if (!(crq->cr_flag & CRYPTO_SKIP_REQID))
 					kcf_reqid_delete(areq);
@@ -1882,7 +1882,7 @@ out:
 		 * here as we may be in interrupt context.
 		 */
 		if (taskq_dispatch(taskq, process_req_hwp, areq,
-		    TQ_NOSLEEP) == (taskqid_t)0) {
+		    TQ_NOSLEEP) == TASKQID_INVALID) {
 			error = CRYPTO_HOST_MEMORY;
 		} else {
 			error = CRYPTO_QUEUED;
diff --git a/usr/src/uts/common/crypto/io/dprov.c b/usr/src/uts/common/crypto/io/dprov.c
index 32b3fdb417..3a0ac07cca 100644
--- a/usr/src/uts/common/crypto/io/dprov.c
+++ b/usr/src/uts/common/crypto/io/dprov.c
@@ -5040,7 +5040,7 @@ dprov_taskq_dispatch(dprov_state_t *softc, dprov_req_t *taskq_req,
     task_func_t *func, int kmflag)
 {
 	if (taskq_dispatch(softc->ds_taskq, func, taskq_req,
-	    kmflag == KM_NOSLEEP ? TQ_NOSLEEP : TQ_SLEEP) == (taskqid_t)0) {
+	    kmflag == KM_NOSLEEP ? TQ_NOSLEEP : TQ_SLEEP) == TASKQID_INVALID) {
 		kmem_free(taskq_req, sizeof (dprov_req_t));
 		return (CRYPTO_HOST_MEMORY);
 	} else
diff --git a/usr/src/uts/common/fs/dnlc.c b/usr/src/uts/common/fs/dnlc.c
index 81a5e65ae0..102375dedd 100644
--- a/usr/src/uts/common/fs/dnlc.c
+++ b/usr/src/uts/common/fs/dnlc.c
@@ -954,7 +954,7 @@ dnlc_reduce_cache(void *reduce_percent)
 	if (dnlc_reduce_idle && (dnlc_nentries >= ncsize || reduce_percent)) {
 		dnlc_reduce_idle = 0;
 		if ((taskq_dispatch(system_taskq, do_dnlc_reduce_cache,
-		    reduce_percent, TQ_NOSLEEP)) == (uintptr_t)NULL)
+		    reduce_percent, TQ_NOSLEEP)) == TASKQID_INVALID)
 			dnlc_reduce_idle = 1;
 	}
 }
diff --git a/usr/src/uts/common/fs/smbsrv/smb_server.c b/usr/src/uts/common/fs/smbsrv/smb_server.c
index b2507b6e71..cf6082e477 100644
--- a/usr/src/uts/common/fs/smbsrv/smb_server.c
+++ b/usr/src/uts/common/fs/smbsrv/smb_server.c
@@ -2351,7 +2351,7 @@ smb_server_create_session(smb_listener_daemon_t *ld, ksocket_t s_so)
 	 */
 	tqid = taskq_dispatch(ld->ld_sv->sv_receiver_pool,
 	    smb_server_receiver, rarg, TQ_NOQUEUE | TQ_SLEEP);
-	if (tqid == 0) {
+	if (tqid == TASKQID_INVALID) {
 		smb_mem_free(rarg);
 		smb_session_disconnect(session);
 		smb_server_destroy_session(ld, session);
diff --git a/usr/src/uts/common/fs/vnode.c b/usr/src/uts/common/fs/vnode.c
index 42acf31f3c..6e8f65cacb 100644
--- a/usr/src/uts/common/fs/vnode.c
+++ b/usr/src/uts/common/fs/vnode.c
@@ -915,7 +915,7 @@ vn_rele_async(vnode_t *vp, taskq_t *taskq)
 	if (vp->v_count == 1) {
 		mutex_exit(&vp->v_lock);
 		VERIFY(taskq_dispatch(taskq, (task_func_t *)vn_rele_inactive,
-		    vp, TQ_SLEEP) != (uintptr_t)NULL);
+		    vp, TQ_SLEEP) != TASKQID_INVALID);
 		return;
 	}
 	VN_RELE_LOCKED(vp);
diff --git a/usr/src/uts/common/fs/zfs/dmu_traverse.c b/usr/src/uts/common/fs/zfs/dmu_traverse.c
index d54042b041..a95bf44fef 100644
--- a/usr/src/uts/common/fs/zfs/dmu_traverse.c
+++ b/usr/src/uts/common/fs/zfs/dmu_traverse.c
@@ -598,8 +598,8 @@ traverse_impl(spa_t *spa, dsl_dataset_t *ds, uint64_t objset, blkptr_t *rootbp,
 	}
 
 	if (!(flags & TRAVERSE_PREFETCH_DATA) ||
-	    0 == taskq_dispatch(system_taskq, traverse_prefetch_thread,
-	    &td, TQ_NOQUEUE))
+	    taskq_dispatch(system_taskq, traverse_prefetch_thread,
+	    &td, TQ_NOQUEUE) == TASKQID_INVALID)
 		pd.pd_exited = B_TRUE;
 
 	SET_BOOKMARK(&czb, td.td_objset,
diff --git a/usr/src/uts/common/fs/zfs/metaslab.c b/usr/src/uts/common/fs/zfs/metaslab.c
index 44fc2b0e86..719df55c76 100644
--- a/usr/src/uts/common/fs/zfs/metaslab.c
+++ b/usr/src/uts/common/fs/zfs/metaslab.c
@@ -2247,7 +2247,7 @@ metaslab_group_preload(metaslab_group_t *mg)
 		}
 
 		VERIFY(taskq_dispatch(mg->mg_taskq, metaslab_preload,
-		    msp, TQ_SLEEP) != NULL);
+		    msp, TQ_SLEEP) != TASKQID_INVALID);
 	}
 	mutex_exit(&mg->mg_lock);
 }
diff --git a/usr/src/uts/common/fs/zfs/vdev.c b/usr/src/uts/common/fs/zfs/vdev.c
index 5441c9059d..f5c3ff5d77 100644
--- a/usr/src/uts/common/fs/zfs/vdev.c
+++ b/usr/src/uts/common/fs/zfs/vdev.c
@@ -1352,7 +1352,7 @@ vdev_open_children(vdev_t *vd)
 
 	for (int c = 0; c < children; c++)
 		VERIFY(taskq_dispatch(tq, vdev_open_child, vd->vdev_child[c],
-		    TQ_SLEEP) != NULL);
+		    TQ_SLEEP) != TASKQID_INVALID);
 
 	taskq_destroy(tq);
 }
diff --git a/usr/src/uts/common/fs/zfs/vdev_file.c b/usr/src/uts/common/fs/zfs/vdev_file.c
index 23536ac105..4dbac6321b 100644
--- a/usr/src/uts/common/fs/zfs/vdev_file.c
+++ b/usr/src/uts/common/fs/zfs/vdev_file.c
@@ -245,7 +245,7 @@ vdev_file_io_start(zio_t *zio)
 	bp->b_iodone = vdev_file_io_intr;
 
 	VERIFY3U(taskq_dispatch(system_taskq, vdev_file_io_strategy, bp,
-	    TQ_SLEEP), !=, 0);
+	    TQ_SLEEP), !=, TASKQID_INVALID);
 }
 
 /* ARGSUSED */
diff --git a/usr/src/uts/common/fs/zfs/zil.c b/usr/src/uts/common/fs/zfs/zil.c
index 44df4c96f3..64b2c5944b 100644
--- a/usr/src/uts/common/fs/zfs/zil.c
+++ b/usr/src/uts/common/fs/zfs/zil.c
@@ -1907,7 +1907,8 @@ zil_clean(zilog_t *zilog, uint64_t synced_txg)
 	ASSERT3P(zilog->zl_dmu_pool, !=, NULL);
 	ASSERT3P(zilog->zl_dmu_pool->dp_zil_clean_taskq, !=, NULL);
 	if (taskq_dispatch(zilog->zl_dmu_pool->dp_zil_clean_taskq,
-	    (void (*)(void *))zil_itxg_clean, clean_me, TQ_NOSLEEP) == NULL)
+	    (void (*)(void *))zil_itxg_clean, clean_me, TQ_NOSLEEP) ==
+	    TASKQID_INVALID)
 		zil_itxg_clean(clean_me);
 }
 
diff --git a/usr/src/uts/common/inet/ip/ip_if.c b/usr/src/uts/common/inet/ip/ip_if.c
index d1bc11f361..31789fb8de 100644
--- a/usr/src/uts/common/inet/ip/ip_if.c
+++ b/usr/src/uts/common/inet/ip/ip_if.c
@@ -2246,7 +2246,8 @@ ill_taskq_dispatch(ip_stack_t *ipst)
 			mp->b_next = NULL;
 
 			VERIFY(taskq_dispatch(system_taskq,
-			    ill_capability_ack_thr, mp, TQ_SLEEP) != 0);
+			    ill_capability_ack_thr, mp, TQ_SLEEP) !=
+			    TASKQID_INVALID);
 			mutex_enter(&ipst->ips_capab_taskq_lock);
 			mp = ipst->ips_capab_taskq_head;
 		}
@@ -2353,7 +2354,7 @@ ill_capability_ack(ill_t *ill, mblk_t *mp)
 	ASSERT(mp->b_next == NULL);
 
 	if (taskq_dispatch(system_taskq, ill_capability_ack_thr, mp,
-	    TQ_NOSLEEP) != 0)
+	    TQ_NOSLEEP) != TASKQID_INVALID)
 		return;
 
 	/*
diff --git a/usr/src/uts/common/inet/ip/ip_ndp.c b/usr/src/uts/common/inet/ip/ip_ndp.c
index 3e5d2087a6..69506f77d4 100644
--- a/usr/src/uts/common/inet/ip/ip_ndp.c
+++ b/usr/src/uts/common/inet/ip/ip_ndp.c
@@ -1219,7 +1219,7 @@ nce_graveyard_free(list_t *graveyard)
 	}
 	mutex_exit(&ill->ill_lock);
 	if (!doit || taskq_dispatch(system_taskq, ncec_mcast_reap,
-	    ill, TQ_NOSLEEP) == (taskqid_t)NULL) {
+	    ill, TQ_NOSLEEP) == TASKQID_INVALID) {
 		mutex_enter(&ill->ill_lock);
 		if (doit) {
 			IP_STAT(ill->ill_ipst, ip_nce_mcast_reclaim_tqfail);
diff --git a/usr/src/uts/common/inet/ip/ipsecah.c b/usr/src/uts/common/inet/ip/ipsecah.c
index 455b9af72f..fc19d7f877 100644
--- a/usr/src/uts/common/inet/ip/ipsecah.c
+++ b/usr/src/uts/common/inet/ip/ipsecah.c
@@ -929,8 +929,8 @@ ah_add_sa_finish(mblk_t *mp, sadb_msg_t *samsg, keysock_in_t *ksi,
 		if (rc == 0) {
 			lpkt = sadb_clear_lpkt(larval);
 			if (lpkt != NULL) {
-				rc = !taskq_dispatch(ah_taskq, inbound_task,
-				    lpkt, TQ_NOSLEEP);
+				rc = taskq_dispatch(ah_taskq, inbound_task,
+				    lpkt, TQ_NOSLEEP) == TASKQID_INVALID;
 			}
 		}
 		IPSA_REFRELE(larval);
diff --git a/usr/src/uts/common/inet/ip/ipsecesp.c b/usr/src/uts/common/inet/ip/ipsecesp.c
index 8f6fa27487..b3dc7d350a 100644
--- a/usr/src/uts/common/inet/ip/ipsecesp.c
+++ b/usr/src/uts/common/inet/ip/ipsecesp.c
@@ -2130,7 +2130,7 @@ ipsecesp_send_keepalive(ipsa_t *assoc)
 	mp->b_prev = (mblk_t *)(uintptr_t)ns->netstack_stackid;
 
 	if (taskq_dispatch(esp_taskq, actually_send_keepalive, mp,
-	    TQ_NOSLEEP) == 0) {
+	    TQ_NOSLEEP) == TASKQID_INVALID) {
 		/* Assume no memory if taskq_dispatch() fails. */
 		mp->b_prev = NULL;
 		ip_drop_packet(mp, B_FALSE, NULL,
@@ -3221,8 +3221,8 @@ esp_add_sa_finish(mblk_t *mp, sadb_msg_t *samsg, keysock_in_t *ksi,
 		if (rc == 0) {
 			lpkt = sadb_clear_lpkt(larval);
 			if (lpkt != NULL) {
-				rc = !taskq_dispatch(esp_taskq, inbound_task,
-				    lpkt, TQ_NOSLEEP);
+				rc = taskq_dispatch(esp_taskq, inbound_task,
+				    lpkt, TQ_NOSLEEP) == TASKQID_INVALID;
 			}
 		}
 		IPSA_REFRELE(larval);
diff --git a/usr/src/uts/common/inet/kssl/ksslfilter.c b/usr/src/uts/common/inet/kssl/ksslfilter.c
index 54766561fb..ea9e2f9232 100644
--- a/usr/src/uts/common/inet/kssl/ksslfilter.c
+++ b/usr/src/uts/common/inet/kssl/ksslfilter.c
@@ -563,7 +563,7 @@ kssl_input_callback(void *arg, mblk_t *mp, kssl_cmd_t kssl_cmd)
 	 * block when handling client_finish messages.
 	 */
 	if (taskq_dispatch(system_taskq, kssl_input_asynch, handle,
-	    TQ_NOSLEEP) == NULL) {
+	    TQ_NOSLEEP) == TASKQID_INVALID) {
 		DTRACE_PROBE(kssl_err__taskq_dispatch_failed);
 		kssl_async_done(kssl->ksslf_ctx);
 	}
diff --git a/usr/src/uts/common/inet/sadb.h b/usr/src/uts/common/inet/sadb.h
index 45750fb0c9..30b935495f 100644
--- a/usr/src/uts/common/inet/sadb.h
+++ b/usr/src/uts/common/inet/sadb.h
@@ -794,7 +794,7 @@ void sadb_clear_buf_pkt(void *ipkt);
 {									\
 	if (buf_pkt != NULL) {						\
 		if (taskq_dispatch(taskq, sadb_clear_buf_pkt,		\
-		    (void *) buf_pkt, TQ_NOSLEEP) == 0) {		\
+		    (void *) buf_pkt, TQ_NOSLEEP) == TASKQID_INVALID) {	\
 		    /* Dispatch was unsuccessful drop the packets. */	\
 			mblk_t		*tmp;				\
 			while (buf_pkt != NULL) {			\
diff --git a/usr/src/uts/common/inet/sctp/sctp.c b/usr/src/uts/common/inet/sctp/sctp.c
index 51c68bba0a..b27da7ad4a 100644
--- a/usr/src/uts/common/inet/sctp/sctp.c
+++ b/usr/src/uts/common/inet/sctp/sctp.c
@@ -1788,7 +1788,7 @@ sctp_find_next_tq(sctp_t *sctp)
 	for (try = 0; try < sctps->sctps_recvq_tq_list_cur_sz; try++) {
 		tq = sctps->sctps_recvq_tq_list[next_tq];
 		if (taskq_dispatch(tq, sctp_process_recvq, sctp,
-		    TQ_NOSLEEP) != (uintptr_t)NULL) {
+		    TQ_NOSLEEP) != TASKQID_INVALID) {
 			sctp->sctp_recvq_tq = tq;
 			return (B_TRUE);
 		}
@@ -1804,7 +1804,7 @@ sctp_find_next_tq(sctp_t *sctp)
 	sctp_inc_taskq(sctps);
 	tq = sctps->sctps_recvq_tq_list[sctps->sctps_recvq_tq_list_cur_sz - 1];
 	if (taskq_dispatch(tq, sctp_process_recvq, sctp, TQ_NOSLEEP) !=
-	    (uintptr_t)NULL) {
+	    TASKQID_INVALID) {
 		sctp->sctp_recvq_tq = tq;
 		return (B_TRUE);
 	}
diff --git a/usr/src/uts/common/io/comstar/port/iscsit/iscsit_login.c b/usr/src/uts/common/io/comstar/port/iscsit/iscsit_login.c
index dc7549c9b3..32b1ae3b09 100644
--- a/usr/src/uts/common/io/comstar/port/iscsit/iscsit_login.c
+++ b/usr/src/uts/common/io/comstar/port/iscsit/iscsit_login.c
@@ -382,7 +382,8 @@ iscsit_login_sm_event_locked(iscsit_conn_t *ict, iscsit_login_event_t event,
 		if (lsm->icl_login_complete) {
 			lsm->icl_busy = B_TRUE;
 			if (taskq_dispatch(iscsit_global.global_dispatch_taskq,
-			    login_sm_complete, ict, DDI_SLEEP) == NULL) {
+			    login_sm_complete, ict, DDI_SLEEP) ==
+			    TASKQID_INVALID) {
 				cmn_err(CE_WARN, "iscsit_login_sm_event_locked:"
 				    " Failed to dispatch task");
 			}
diff --git a/usr/src/uts/common/io/comstar/port/iscsit/iscsit_tgt.c b/usr/src/uts/common/io/comstar/port/iscsit/iscsit_tgt.c
index 63e9424484..97a1909ca0 100644
--- a/usr/src/uts/common/io/comstar/port/iscsit/iscsit_tgt.c
+++ b/usr/src/uts/common/io/comstar/port/iscsit/iscsit_tgt.c
@@ -650,7 +650,7 @@ iscsit_tgt_dereg_retry(void *arg)
 	 * If it fails we'll setup another timeout and try again later.
 	 */
 	if (taskq_dispatch(iscsit_global.global_dispatch_taskq,
-	    iscsit_tgt_dereg_task, tgt, DDI_NOSLEEP) == NULL) {
+	    iscsit_tgt_dereg_task, tgt, DDI_NOSLEEP) == TASKQID_INVALID) {
 		/* Dispatch failed, try again later */
 		(void) timeout(iscsit_tgt_dereg_retry, tgt,
 		    drv_usectohz(TGT_DEREG_RETRY_SECONDS * 1000000));
diff --git a/usr/src/uts/common/io/comstar/port/pppt/pppt_tgt.c b/usr/src/uts/common/io/comstar/port/pppt/pppt_tgt.c
index fbf8ad876f..6a6b2ed545 100644
--- a/usr/src/uts/common/io/comstar/port/pppt/pppt_tgt.c
+++ b/usr/src/uts/common/io/comstar/port/pppt/pppt_tgt.c
@@ -802,7 +802,7 @@ pppt_tgt_dereg_retry(void *arg)
 	 * If it fails we'll setup another timeout and try again later.
 	 */
 	if (taskq_dispatch(pppt_global.global_dispatch_taskq,
-	    pppt_tgt_dereg_task, tgt, KM_NOSLEEP) == NULL) {
+	    pppt_tgt_dereg_task, tgt, KM_NOSLEEP) == TASKQID_INVALID) {
 		/* Dispatch failed, try again later */
 		(void) timeout(pppt_tgt_dereg_retry, tgt,
 		    drv_usectohz(TGT_DEREG_RETRY_SECONDS * 1000000));
diff --git a/usr/src/uts/common/io/dld/dld_str.c b/usr/src/uts/common/io/dld/dld_str.c
index 8b9f87403f..9f89165455 100644
--- a/usr/src/uts/common/io/dld/dld_str.c
+++ b/usr/src/uts/common/io/dld/dld_str.c
@@ -1957,7 +1957,7 @@ dld_taskq_dispatch(void)
 			list_remove(&dld_taskq_list, dsp);
 			mutex_exit(&dld_taskq_lock);
 			VERIFY(taskq_dispatch(dld_taskq, dld_wput_nondata_task,
-			    dsp, TQ_SLEEP) != 0);
+			    dsp, TQ_SLEEP) != TASKQID_INVALID);
 			mutex_enter(&dld_taskq_lock);
 			dsp = list_head(&dld_taskq_list);
 		}
@@ -2024,7 +2024,7 @@ dld_wput_nondata(dld_str_t *dsp, mblk_t *mp)
 	mutex_exit(&dsp->ds_lock);
 
 	if (taskq_dispatch(dld_taskq, dld_wput_nondata_task, dsp,
-	    TQ_NOSLEEP) != 0)
+	    TQ_NOSLEEP) != TASKQID_INVALID)
 		return;
 
 	mutex_enter(&dld_taskq_lock);
diff --git a/usr/src/uts/common/io/emul64.c b/usr/src/uts/common/io/emul64.c
index e8d18d109f..47383c619b 100644
--- a/usr/src/uts/common/io/emul64.c
+++ b/usr/src/uts/common/io/emul64.c
@@ -1029,7 +1029,7 @@ emul64_scsi_start(struct scsi_address *ap, struct scsi_pkt *pkt)
 	if ((emul64_usetaskq == 0) || (pkt->pkt_flags & FLAG_NOINTR) != 0) {
 		emul64_pkt_comp((caddr_t)pkt);
 	} else {
-		dispatched = NULL;
+		dispatched = TASKQID_INVALID;
 		if (emul64_collect_stats) {
 			/*
 			 * If we are collecting statistics, call
@@ -1042,14 +1042,14 @@ emul64_scsi_start(struct scsi_address *ap, struct scsi_pkt *pkt)
 			 */
 			dispatched = taskq_dispatch(emul64->emul64_taskq,
 			    emul64_pkt_comp, (void *)pkt, TQ_NOSLEEP);
-			if (dispatched == NULL) {
+			if (dispatched == TASKQID_INVALID) {
 				/* Queue was full.  dispatch failed. */
 				mutex_enter(&emul64_stats_mutex);
 				emul64_taskq_max++;
 				mutex_exit(&emul64_stats_mutex);
 			}
 		}
-		if (dispatched == NULL) {
+		if (dispatched == TASKQID_INVALID) {
 			(void) taskq_dispatch(emul64->emul64_taskq,
 			    emul64_pkt_comp, (void *)pkt, TQ_SLEEP);
 		}
diff --git a/usr/src/uts/common/io/fibre-channel/impl/fp.c b/usr/src/uts/common/io/fibre-channel/impl/fp.c
index ca35678c72..f4ad1f6d25 100644
--- a/usr/src/uts/common/io/fibre-channel/impl/fp.c
+++ b/usr/src/uts/common/io/fibre-channel/impl/fp.c
@@ -4839,7 +4839,7 @@ fp_ulp_devc_cb(fc_local_port_t *port, fc_portmap_t *changelist,
 	}
 
 	ret = taskq_dispatch(port->fp_taskq, fctl_ulp_statec_cb, clist, sleep);
-	if (sync && ret) {
+	if (sync && ret != TASKQID_INVALID) {
 		mutex_enter(&clist->clist_mutex);
 		while (clist->clist_wait) {
 			cv_wait(&clist->clist_cv, &clist->clist_mutex);
diff --git a/usr/src/uts/common/io/fibre-channel/ulp/fcip.c b/usr/src/uts/common/io/fibre-channel/ulp/fcip.c
index 5989490929..416bc3cb55 100644
--- a/usr/src/uts/common/io/fibre-channel/ulp/fcip.c
+++ b/usr/src/uts/common/io/fibre-channel/ulp/fcip.c
@@ -4583,7 +4583,7 @@ fcip_handle_topology(struct fcip *fptr)
 		if (!(fptr->fcip_flags & FCIP_REG_INPROGRESS)) {
 			fptr->fcip_flags |= FCIP_REG_INPROGRESS;
 			if (taskq_dispatch(fptr->fcip_tq, fcip_port_ns,
-			    fptr, KM_NOSLEEP) == 0) {
+			    fptr, KM_NOSLEEP) == TASKQID_INVALID) {
 				fptr->fcip_flags &= ~FCIP_REG_INPROGRESS;
 			}
 		}
@@ -7258,7 +7258,7 @@ fcip_timeout(void *arg)
 
 					if (taskq_dispatch(fptr->fcip_tq,
 					    fcip_rte_remove_deferred, fptr,
-					    KM_NOSLEEP) == 0) {
+					    KM_NOSLEEP) == TASKQID_INVALID) {
 						/*
 						 * failed - so mark the entry
 						 * as invalid again.
@@ -7302,7 +7302,7 @@ fcip_timeout(void *arg)
 					mutex_exit(&fdestp->fcipd_mutex);
 					if (taskq_dispatch(fptr->fcip_tq,
 					    fcip_pkt_timeout, fcip_pkt,
-					    KM_NOSLEEP) == 0) {
+					    KM_NOSLEEP) == TASKQID_INVALID) {
 						/*
 						 * timeout immediately
 						 */
diff --git a/usr/src/uts/common/io/fibre-channel/ulp/fcp.c b/usr/src/uts/common/io/fibre-channel/ulp/fcp.c
index 963d3f523b..2bbd8a5a3f 100644
--- a/usr/src/uts/common/io/fibre-channel/ulp/fcp.c
+++ b/usr/src/uts/common/io/fibre-channel/ulp/fcp.c
@@ -14458,7 +14458,7 @@ fcp_pass_to_hp(struct fcp_port *pptr, struct fcp_lun *plun,
 	}
 	mutex_exit(&plun->lun_mutex);
 	if (taskq_dispatch(DEVI(pdip)->devi_taskq, fcp_hp_task,
-	    (void *)elem, KM_NOSLEEP) == NULL) {
+	    (void *)elem, KM_NOSLEEP) == TASKQID_INVALID) {
 		mutex_enter(&plun->lun_mutex);
 		if (elem->what == FCP_ONLINE || elem->what == FCP_OFFLINE) {
 			plun->lun_event_count--;
diff --git a/usr/src/uts/common/io/ib/clients/daplt/daplt.c b/usr/src/uts/common/io/ib/clients/daplt/daplt.c
index a207150d62..7c1849e605 100644
--- a/usr/src/uts/common/io/ib/clients/daplt/daplt.c
+++ b/usr/src/uts/common/io/ib/clients/daplt/daplt.c
@@ -1893,7 +1893,7 @@ daplka_timer_dispatch(void *arg)
 	 * taskq_dispatch succeeds.
 	 */
 	if (taskq_dispatch(daplka_taskq,
-	    daplka_timer_thread, arg, TQ_NOSLEEP) == 0) {
+	    daplka_timer_thread, arg, TQ_NOSLEEP) == TASKQID_INVALID) {
 		DERR("timer_dispatch: taskq_dispatch failed, retrying...\n");
 		(void) timeout(daplka_timer_dispatch, arg, 10);
 	}
diff --git a/usr/src/uts/common/io/ib/clients/of/sol_ofs/sol_cma.c b/usr/src/uts/common/io/ib/clients/of/sol_ofs/sol_cma.c
index 5384be7bd9..127044b3b3 100644
--- a/usr/src/uts/common/io/ib/clients/of/sol_ofs/sol_cma.c
+++ b/usr/src/uts/common/io/ib/clients/of/sol_ofs/sol_cma.c
@@ -1686,7 +1686,7 @@ cma_generate_event(struct rdma_cm_id *idp, enum rdma_cm_event_type event,
 	}
 
 	if (taskq_dispatch(system_taskq, cma_generate_event_thr,
-	    (void *)event_arg, TQ_SLEEP) == 0) {
+	    (void *)event_arg, TQ_SLEEP) == TASKQID_INVALID) {
 		SOL_OFS_DPRINTF_L2(sol_rdmacm_dbg_str,
 		    "generate_event_async: taskq_dispatch() failed!!");
 		mutex_enter(&chanp->chan_mutex);
diff --git a/usr/src/uts/common/io/ib/ibnex/ibnex.c b/usr/src/uts/common/io/ib/ibnex/ibnex.c
index d25c6ddf05..765f215458 100644
--- a/usr/src/uts/common/io/ib/ibnex/ibnex.c
+++ b/usr/src/uts/common/io/ib/ibnex/ibnex.c
@@ -867,7 +867,7 @@ ibnex_ibtl_callback(ibtl_ibnex_cb_args_t *cb_args)
 		 * from interrupt context.
 		 */
 		if (taskq_dispatch(system_taskq, ibnex_handle_reprobe_dev,
-		    clnt_dip, TQ_SLEEP) == 0) {
+		    clnt_dip, TQ_SLEEP) == TASKQID_INVALID) {
 			IBTF_DPRINTF_L2("ibnex",
 			    "ibnex_ibtl_callback: taskq_dispatch failed");
 			mutex_enter(&ibnex.ibnex_mutex);
diff --git a/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_path.c b/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_path.c
index 7d1e625863..171a70e7ee 100644
--- a/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_path.c
+++ b/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_path.c
@@ -482,7 +482,7 @@ ibcm_handle_get_path(ibt_path_attr_t *attrp, ibt_path_flags_t flags,
 	if (func != NULL) {		/* Non-Blocking */
 		IBTF_DPRINTF_L3(cmlog, "ibcm_handle_get_path: Non Blocking");
 		if (taskq_dispatch(ibcm_taskq, ibcm_process_async_get_paths,
-		    path_tq, TQ_NOSLEEP) == 0) {
+		    path_tq, TQ_NOSLEEP) == TASKQID_INVALID) {
 			IBTF_DPRINTF_L2(cmlog, "ibcm_handle_get_path: "
 			    "Failed to dispatch the TaskQ");
 			kmem_free(path_tq, len);
@@ -4169,7 +4169,7 @@ ibcm_get_ip_path(ibt_clnt_hdl_t ibt_hdl, ibt_path_flags_t flags,
 	sleep_flag = ((func == NULL) ? TQ_SLEEP : TQ_NOSLEEP);
 	ret = taskq_dispatch(ibcm_taskq, ibcm_process_get_ip_paths, path_tq,
 	    sleep_flag);
-	if (ret == 0) {
+	if (ret == TASKQID_INVALID) {
 		IBTF_DPRINTF_L2(cmlog, "ibcm_get_ip_path: Failed to dispatch "
 		    "the TaskQ");
 		if (func == NULL) {		/* Blocking */
diff --git a/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_sm.c b/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_sm.c
index 24f09e7f0e..1afa236a1e 100644
--- a/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_sm.c
+++ b/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_sm.c
@@ -812,7 +812,7 @@ ibcm_recv_timeout_cb(void *args)
 		ibcm_recv_tasks++;
 		mutex_exit(&ibcm_recv_mutex);
 		if (taskq_dispatch(ibcm_taskq, ibcm_recv_task, tq,
-		    TQ_NOQUEUE | TQ_NOSLEEP) == 0) {
+		    TQ_NOQUEUE | TQ_NOSLEEP) == TASKQID_INVALID) {
 			mutex_enter(&ibcm_recv_mutex);
 			if (--ibcm_recv_tasks == 0) {
 				(void) timeout(ibcm_recv_timeout_cb, tq, 1);
@@ -873,7 +873,8 @@ ibcm_recv_add_one(ibmf_handle_t ibmf_handle, ibmf_msg_t *msgp, void *args)
 		tq->tq_args = args;
 		_NOTE(NOW_VISIBLE_TO_OTHER_THREADS(*tq))
 		if (taskq_dispatch(ibcm_taskq, ibcm_recv_task, tq,
-		    TQ_NOQUEUE | TQ_NOSLEEP) == 0) {	/* dispatch failed */
+		    TQ_NOQUEUE | TQ_NOSLEEP) == TASKQID_INVALID) {
+			/* dispatch failed */
 			mutex_enter(&ibcm_recv_mutex);
 			if (--ibcm_recv_tasks == 0) {
 				/* try the dispatch again, after a tick */
@@ -3490,7 +3491,8 @@ ibcm_timeout_cb(void *arg)
 
 			/* if possible, do not slow down calling recycle func */
 			if (taskq_dispatch(ibcm_taskq, ibcm_process_rc_recycle,
-			    recycle_arg, TQ_NOQUEUE | TQ_NOSLEEP) == 0) {
+			    recycle_arg, TQ_NOQUEUE | TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 
 				_NOTE(NOW_INVISIBLE_TO_OTHER_THREADS(
 				    statep->recycle_arg))
diff --git a/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_ti.c b/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_ti.c
index feb60d22e7..c14900a314 100644
--- a/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_ti.c
+++ b/usr/src/uts/common/io/ib/mgt/ibcm/ibcm_ti.c
@@ -1392,7 +1392,7 @@ ibcm_close_rc_channel(ibt_channel_hdl_t channel, ibcm_state_data_t *statep,
 			if (mode == IBT_NONBLOCKING) {
 				if (taskq_dispatch(ibcm_taskq,
 				    ibcm_process_abort_via_taskq, statep,
-				    TQ_NOSLEEP) == 0) {
+				    TQ_NOSLEEP) == TASKQID_INVALID) {
 
 					IBCM_REF_CNT_DECR(statep);
 					statep->state = old_state;
@@ -4896,7 +4896,7 @@ ibt_join_mcg(ib_gid_t rgid, ibt_mcg_attr_t *mcg_attr,
 	if (func != NULL) {	/* Non-Blocking */
 		IBTF_DPRINTF_L3(cmlog, "ibt_join_mcg: Non-Blocking Call");
 		if (taskq_dispatch(ibcm_taskq, ibcm_process_async_join_mcg,
-		    mcg_tq, TQ_NOSLEEP) == 0) {
+		    mcg_tq, TQ_NOSLEEP) == TASKQID_INVALID) {
 			IBTF_DPRINTF_L2(cmlog, "ibt_join_mcg: Failed to "
 			    "Dispatch the TaskQ");
 			kmem_free(mcg_tq, sizeof (ibcm_join_mcg_tqarg_t));
diff --git a/usr/src/uts/common/io/ib/mgt/ibdm/ibdm.c b/usr/src/uts/common/io/ib/mgt/ibdm/ibdm.c
index c28ce4c429..960f2926bb 100644
--- a/usr/src/uts/common/io/ib/mgt/ibdm/ibdm.c
+++ b/usr/src/uts/common/io/ib/mgt/ibdm/ibdm.c
@@ -1487,7 +1487,7 @@ ibdm_sweep_fabric(int reprobe_flag)
 		IBTF_DPRINTF_L4("ibdm", "\tsweep_fabric: gid_info = %p"
 		    " taskq_id = %x", gid_info, tid);
 		/* taskq failed to dispatch call it directly */
-		if (tid == NULL)
+		if (tid == TASKQID_INVALID)
 			ibdm_probe_gid_thread((void *)gid_info);
 	}
 
@@ -3432,7 +3432,7 @@ ibdm_ibmf_recv_cb(ibmf_handle_t ibmf_hdl, ibmf_msg_t *msg, void *arg)
 	taskq_args->tq_args = arg;
 
 	if (taskq_dispatch(system_taskq, ibdm_recv_incoming_mad, taskq_args,
-	    TQ_NOSLEEP) == 0) {
+	    TQ_NOSLEEP) == TASKQID_INVALID) {
 		IBTF_DPRINTF_L2("ibdm", "ibmf_recv_cb: taskq_dispatch failed");
 		if (ibmf_free_msg(ibmf_hdl, &msg) != IBMF_SUCCESS) {
 			IBTF_DPRINTF_L4("ibmf_recv_cb",
@@ -5849,7 +5849,7 @@ ibdm_saa_event_cb(ibmf_saa_handle_t ibmf_saa_handle,
 		if (node_gid_info == NULL) {
 			if (taskq_dispatch(system_taskq,
 			    ibdm_saa_handle_new_gid, (void *)gid_info,
-			    TQ_NOSLEEP) == NULL) {
+			    TQ_NOSLEEP) == TASKQID_INVALID) {
 				IBTF_DPRINTF_L2("ibdm", "\tsaa_event_cb: "
 				    "new_gid taskq_dispatch failed");
 				return;
@@ -5901,7 +5901,7 @@ ibdm_saa_event_cb(ibmf_saa_handle_t ibmf_saa_handle,
 		event_arg->callback_arg = callback_arg;
 
 		if (taskq_dispatch(system_taskq, ibdm_saa_event_taskq,
-		    (void *)event_arg, TQ_NOSLEEP) == NULL) {
+		    (void *)event_arg, TQ_NOSLEEP) == TASKQID_INVALID) {
 			IBTF_DPRINTF_L2("ibdm", "\tsaa_event_cb: "
 			    "taskq_dispatch failed");
 			ibdm_free_saa_event_arg(event_arg);
diff --git a/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_recv.c b/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_recv.c
index 255298f986..b8c4297c3e 100644
--- a/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_recv.c
+++ b/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_recv.c
@@ -309,7 +309,7 @@ ibmf_i_handle_recv_completion(ibmf_ci_t *cip, ibt_wc_t *wcp)
 			/* Dispatch the taskq thread to do further processing */
 			ret = taskq_dispatch(clientp->ic_recv_taskq,
 			    ibmf_i_do_recv_cb, recv_wqep, TQ_NOSLEEP);
-			if (ret == 0) {
+			if (ret == TASKQID_INVALID) {
 				mutex_enter(&clientp->ic_kstat_mutex);
 				IBMF_SUB32_KSTATS(clientp, recv_cb_active, 1);
 				mutex_exit(&clientp->ic_kstat_mutex);
@@ -391,7 +391,7 @@ ibmf_i_handle_recv_completion(ibmf_ci_t *cip, ibt_wc_t *wcp)
 			modlargsp->ibmf_class	= class;
 			ret = taskq_dispatch(ibmf_statep->ibmf_taskq,
 			    ibmf_module_load, modlargsp, TQ_NOSLEEP);
-			if (ret == 0) {
+			if (ret == TASKQID_INVALID) {
 				kmem_free(modlargsp,
 				    sizeof (ibmf_mod_load_args_t));
 				IBMF_TRACE_0(IBMF_TNF_DEBUG, DPRINT_L4,
diff --git a/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_saa_events.c b/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_saa_events.c
index cacb16fd4c..d5ce8491fd 100644
--- a/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_saa_events.c
+++ b/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_saa_events.c
@@ -970,7 +970,7 @@ ibmf_saa_notify_event_clients(saa_port_t *saa_portp,
 		status = taskq_dispatch(saa_statep->saa_event_taskq,
 		    ibmf_saa_notify_event_client_task, event_taskq_args,
 		    KM_NOSLEEP);
-		if (status == 0) {
+		if (status == TASKQID_INVALID) {
 
 			IBMF_TRACE_2(IBMF_TNF_NODEBUG, DPRINT_L1,
 			    ibmf_saa_notify_event_clients_err, IBMF_TNF_ERROR,
diff --git a/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_send.c b/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_send.c
index dcdba756b2..7265dd018e 100644
--- a/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_send.c
+++ b/usr/src/uts/common/io/ib/mgt/ibmf/ibmf_send.c
@@ -364,7 +364,7 @@ ibmf_i_handle_send_completion(ibmf_ci_t *cip, ibt_wc_t *wcp)
 	if ((clientp->ic_reg_flags & IBMF_REG_FLAG_NO_OFFLOAD) == 0) {
 		ret = taskq_dispatch(cclientp->ic_send_taskq, ibmf_i_do_send_cb,
 		    send_wqep, TQ_NOSLEEP);
-		if (ret == 0) {
+		if (ret == TASKQID_INVALID) {
 			IBMF_TRACE_1(IBMF_TNF_DEBUG, DPRINT_L4,
 			    ibmf_i_handle_send_err, IBMF_TNF_ERROR, "",
 			    "ibmf_i_handle_send_completion(): %s\n",
diff --git a/usr/src/uts/common/io/idm/idm.c b/usr/src/uts/common/io/idm/idm.c
index 23bdb1c44a..9951a74684 100644
--- a/usr/src/uts/common/io/idm/idm.c
+++ b/usr/src/uts/common/io/idm/idm.c
@@ -256,7 +256,7 @@ idm_ini_conn_destroy(idm_conn_t *ic)
 	mutex_exit(&idm.idm_global_mutex);
 
 	if (taskq_dispatch(idm.idm_global_taskq,
-	    &idm_ini_conn_destroy_task, ic, TQ_SLEEP) == NULL) {
+	    &idm_ini_conn_destroy_task, ic, TQ_SLEEP) == TASKQID_INVALID) {
 		cmn_err(CE_WARN,
 		    "idm_ini_conn_destroy: Couldn't dispatch task");
 	}
@@ -2180,7 +2180,8 @@ idm_refcnt_rele(idm_refcnt_t *refcnt)
 	if (refcnt->ir_refcnt == 0) {
 		if (refcnt->ir_waiting == REF_WAIT_ASYNC) {
 			if (taskq_dispatch(idm.idm_global_taskq,
-			    &idm_refcnt_unref_task, refcnt, TQ_SLEEP) == NULL) {
+			    &idm_refcnt_unref_task, refcnt, TQ_SLEEP) ==
+			    TASKQID_INVALID) {
 				cmn_err(CE_WARN,
 				    "idm_refcnt_rele: Couldn't dispatch task");
 			}
@@ -2208,7 +2209,7 @@ idm_refcnt_rele_and_destroy(idm_refcnt_t *refcnt, idm_refcnt_cb_t *cb_func)
 		refcnt->ir_cb = cb_func;
 		refcnt->ir_waiting = REF_WAIT_ASYNC;
 		if (taskq_dispatch(idm.idm_global_taskq,
-		    &idm_refcnt_unref_task, refcnt, TQ_SLEEP) == NULL) {
+		    &idm_refcnt_unref_task, refcnt, TQ_SLEEP) == TASKQID_INVALID) {
 			cmn_err(CE_WARN,
 			    "idm_refcnt_rele: Couldn't dispatch task");
 		}
@@ -2241,7 +2242,8 @@ idm_refcnt_async_wait_ref(idm_refcnt_t *refcnt, idm_refcnt_cb_t *cb_func)
 	 */
 	if (refcnt->ir_refcnt == 0) {
 		if (taskq_dispatch(idm.idm_global_taskq,
-		    &idm_refcnt_unref_task, refcnt, TQ_SLEEP) == NULL) {
+		    &idm_refcnt_unref_task, refcnt, TQ_SLEEP) ==
+		    TASKQID_INVALID) {
 			cmn_err(CE_WARN,
 			    "idm_refcnt_async_wait_ref: "
 			    "Couldn't dispatch task");
diff --git a/usr/src/uts/common/io/pciex/hotplug/pciehpc.c b/usr/src/uts/common/io/pciex/hotplug/pciehpc.c
index 2100646260..94a32abf1b 100644
--- a/usr/src/uts/common/io/pciex/hotplug/pciehpc.c
+++ b/usr/src/uts/common/io/pciex/hotplug/pciehpc.c
@@ -2225,8 +2225,8 @@ pciehpc_handle_power_fault(dev_info_t *dip)
 	 */
 	ndi_hold_devi(dip);
 
-	if (!taskq_dispatch(system_taskq, pciehpc_power_fault_handler, dip,
-	    TQ_NOSLEEP)) {
+	if (taskq_dispatch(system_taskq, pciehpc_power_fault_handler, dip,
+	    TQ_NOSLEEP) == TASKQID_INVALID) {
 		ndi_rele_devi(dip);
 		PCIE_DBG("pciehpc_intr(): "
 		    "Failed to dispatch power fault handler, dip %p\n", dip);
diff --git a/usr/src/uts/common/io/sata/impl/sata.c b/usr/src/uts/common/io/sata/impl/sata.c
index 29b7cf2005..55da099035 100644
--- a/usr/src/uts/common/io/sata/impl/sata.c
+++ b/usr/src/uts/common/io/sata/impl/sata.c
@@ -2533,12 +2533,12 @@ sata_scsi_start(struct scsi_address *ap, struct scsi_pkt *pkt)
 				if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 				    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
 				    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
-				    NULL) {
+				    TASKQID_INVALID) {
 					return (TRAN_BUSY);
 				}
 			} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+			    spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 				/* Scheduling the callback failed */
 				return (TRAN_BUSY);
 			}
@@ -3259,12 +3259,12 @@ sata_txlt_generic_pkt_info(sata_pkt_txlate_t *spx, int *reason, int flag)
 				if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 				    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
 				    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
-				    NULL) {
+				    TASKQID_INVALID) {
 					return (TRAN_BUSY);
 				}
 			} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+			    spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 				/* Scheduling the callback failed */
 				return (TRAN_BUSY);
 			}
@@ -3485,12 +3485,13 @@ sata_txlt_invalid_command(sata_pkt_txlate_t *spx)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -3534,12 +3535,13 @@ sata_txlt_check_condition(sata_pkt_txlate_t *spx, uchar_t key, uchar_t code)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -3584,12 +3586,13 @@ sata_txlt_nodata_cmd_immediate(sata_pkt_txlate_t *spx)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -3911,12 +3914,13 @@ done:
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -4061,12 +4065,13 @@ sata_txlt_request_sense(sata_pkt_txlate_t *spx)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -4154,12 +4159,13 @@ sata_txlt_test_unit_ready(sata_pkt_txlate_t *spx)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -4488,12 +4494,13 @@ err_out:
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -4603,12 +4610,13 @@ sata_txlt_read_capacity(sata_pkt_txlate_t *spx)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -4785,12 +4793,13 @@ sata_txlt_read_capacity16(sata_pkt_txlate_t *spx)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -5234,12 +5243,13 @@ done:
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -5563,12 +5573,13 @@ done:
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -6065,12 +6076,13 @@ done:
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -6799,12 +6811,13 @@ bad_param:
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -7226,12 +7239,13 @@ sata_txlt_lba_out_of_range(sata_pkt_txlate_t *spx)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -7368,12 +7382,13 @@ sata_txlt_ata_pass_thru_illegal_cmd(sata_pkt_txlate_t *spx)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -7402,7 +7417,7 @@ sata_txlt_unmap_nodata_cmd(sata_pkt_txlate_t *spx)
 		/* scsi callback required */
 		if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
@@ -7431,12 +7446,13 @@ sata_emul_rw_completion(sata_pkt_txlate_t *spx)
 		if (servicing_interrupt()) {
 			if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 			    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) == NULL) {
+			    (void *)spx->txlt_scsi_pkt, TQ_NOSLEEP) ==
+			    TASKQID_INVALID) {
 				return (TRAN_BUSY);
 			}
 		} else if (taskq_dispatch(SATA_TXLT_TASKQ(spx),
 		    (task_func_t *)spx->txlt_scsi_pkt->pkt_comp,
-		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == NULL) {
+		    (void *)spx->txlt_scsi_pkt, TQ_SLEEP) == TASKQID_INVALID) {
 			/* Scheduling the callback failed */
 			return (TRAN_BUSY);
 		}
diff --git a/usr/src/uts/common/io/scsi/adapters/scsi_vhci/scsi_vhci.c b/usr/src/uts/common/io/scsi/adapters/scsi_vhci/scsi_vhci.c
index d996c5f867..32417c2e4e 100644
--- a/usr/src/uts/common/io/scsi/adapters/scsi_vhci/scsi_vhci.c
+++ b/usr/src/uts/common/io/scsi/adapters/scsi_vhci/scsi_vhci.c
@@ -1164,7 +1164,7 @@ vhci_scsi_start(struct scsi_address *ap, struct scsi_pkt *pkt)
 		if (!(vpkt->vpkt_state & VHCI_PKT_THRU_TASKQ)) {
 			if (taskq_dispatch(vhci->vhci_taskq,
 			    vhci_dispatch_scsi_start, (void *) vpkt,
-			    KM_NOSLEEP)) {
+			    KM_NOSLEEP) != TASKQID_INVALID) {
 				return (TRAN_ACCEPT);
 			} else {
 				return (TRAN_BUSY);
@@ -2964,7 +2964,7 @@ vhci_do_prin(struct vhci_pkt **intr_vpkt)
 		 * Dispatch the retry command
 		 */
 		if (taskq_dispatch(vhci->vhci_taskq, vhci_dispatch_scsi_start,
-		    (void *) new_vpkt, KM_NOSLEEP) == NULL) {
+		    (void *) new_vpkt, KM_NOSLEEP) == TASKQID_INVALID) {
 			if (path_holder) {
 				vpkt->vpkt_path = path_holder;
 				mdi_hold_path(path_holder);
diff --git a/usr/src/uts/common/io/scsi/targets/sd.c b/usr/src/uts/common/io/scsi/targets/sd.c
index d29362d125..539a7895c6 100644
--- a/usr/src/uts/common/io/scsi/targets/sd.c
+++ b/usr/src/uts/common/io/scsi/targets/sd.c
@@ -13389,7 +13389,7 @@ sd_mapblocksize_iodone(int index, struct sd_lun *un, struct buf *bp)
 		 * with the shadow buf at that point.
 		 */
 		if (taskq_dispatch(sd_wmr_tq, sd_read_modify_write_task, bp,
-		    KM_NOSLEEP) != 0) {
+		    KM_NOSLEEP) != TASKQID_INVALID) {
 			/*
 			 * Dispatch was successful so we are done. Return
 			 * without going any higher up the iodone chain. Do
@@ -18716,7 +18716,7 @@ sd_sense_key_unit_attention(struct sd_lun *un, 	uint8_t *sense_datap,
 #ifdef _LP64
 		if (un->un_blockcount + 1 > SD_GROUP1_MAX_ADDRESS) {
 			if (taskq_dispatch(sd_tq, sd_reenable_dsense_task,
-			    un, KM_NOSLEEP) == 0) {
+			    un, KM_NOSLEEP) == TASKQID_INVALID) {
 				/*
 				 * If we can't dispatch the task we'll just
 				 * live without descriptor sense.  We can
@@ -18747,7 +18747,7 @@ sd_sense_key_unit_attention(struct sd_lun *un, 	uint8_t *sense_datap,
 		 * encountered at a later time.)
 		 */
 		if (taskq_dispatch(sd_tq, sd_media_change_task, pktp,
-		    KM_NOSLEEP) == 0) {
+		    KM_NOSLEEP) == TASKQID_INVALID) {
 			/*
 			 * Cannot dispatch the request so fail the command.
 			 */
@@ -18793,7 +18793,7 @@ sd_sense_key_unit_attention(struct sd_lun *un, 	uint8_t *sense_datap,
 	    ((asc == 0x2a) && (ascq == 0x01)) ||
 	    ((asc == 0x3f) && (ascq == 0x0e))) {
 		if (taskq_dispatch(sd_tq, sd_target_change_task, un,
-		    KM_NOSLEEP) == 0) {
+		    KM_NOSLEEP) == TASKQID_INVALID) {
 			SD_ERROR(SD_LOG_ERROR, un,
 			    "sd_sense_key_unit_attention: "
 			    "Could not dispatch sd_target_change_task\n");
diff --git a/usr/src/uts/common/io/scsi/targets/sd_xbuf.c b/usr/src/uts/common/io/scsi/targets/sd_xbuf.c
index be464d657c..9e9d1f283d 100644
--- a/usr/src/uts/common/io/scsi/targets/sd_xbuf.c
+++ b/usr/src/uts/common/io/scsi/targets/sd_xbuf.c
@@ -566,7 +566,8 @@ xbuf_dispatch(ddi_xbuf_attr_t xap)
 		 * schedule a timeout(9F) callback to try again later.
 		 */
 		if (taskq_dispatch(xap->xa_tq,
-		    (void (*)(void *)) xbuf_iostart, xap, KM_NOSLEEP) == 0) {
+		    (void (*)(void *)) xbuf_iostart, xap, KM_NOSLEEP) ==
+		    TASKQID_INVALID) {
 			/*
 			 * Unable to enqueue the request for the taskq thread,
 			 * try again later.  Note that this will keep re-trying
diff --git a/usr/src/uts/common/io/softmac/softmac_fp.c b/usr/src/uts/common/io/softmac/softmac_fp.c
index 2fc66e9bd3..44f7e94bee 100644
--- a/usr/src/uts/common/io/softmac/softmac_fp.c
+++ b/usr/src/uts/common/io/softmac/softmac_fp.c
@@ -852,7 +852,8 @@ softmac_taskq_dispatch(void)
 			sup->su_taskq_scheduled = B_FALSE;
 			mutex_exit(&softmac_taskq_lock);
 			VERIFY(taskq_dispatch(system_taskq,
-			    softmac_wput_nondata_task, sup, TQ_SLEEP) != NULL);
+			    softmac_wput_nondata_task, sup, TQ_SLEEP) !=
+			    TASKQID_INVALID);
 			mutex_enter(&softmac_taskq_lock);
 			sup = list_head(&softmac_taskq_list);
 		}
@@ -893,7 +894,7 @@ softmac_wput_nondata(softmac_upper_t *sup, mblk_t *mp)
 	mutex_exit(&sup->su_disp_mutex);
 
 	if (taskq_dispatch(system_taskq, softmac_wput_nondata_task,
-	    sup, TQ_NOSLEEP) != NULL) {
+	    sup, TQ_NOSLEEP) != TASKQID_INVALID) {
 		return;
 	}
 
diff --git a/usr/src/uts/common/io/usb/usba/hcdi.c b/usr/src/uts/common/io/usb/usba/hcdi.c
index f6cbf0b212..385dfcaccc 100644
--- a/usr/src/uts/common/io/usb/usba/hcdi.c
+++ b/usr/src/uts/common/io/usb/usba/hcdi.c
@@ -564,7 +564,7 @@ usba_hcdi_cb(usba_pipe_handle_data_t *ph_data, usb_opaque_t req,
 		}
 		if (taskq_dispatch(usba_device->usb_shared_taskq[iface],
 		    hcdi_shared_cb_thread, req_wrp, TQ_NOSLEEP) ==
-		    NULL) {
+		    TASKQID_INVALID) {
 			usba_req_exc_cb(req_wrp,
 			    USB_CR_NO_RESOURCES, USB_CB_ASYNC_REQ_FAILED);
 		}
diff --git a/usr/src/uts/common/io/usb/usba/usbai_util.c b/usr/src/uts/common/io/usb/usba/usbai_util.c
index 17711e0d7b..dd942e35f2 100644
--- a/usr/src/uts/common/io/usb/usba/usbai_util.c
+++ b/usr/src/uts/common/io/usb/usba/usbai_util.c
@@ -1691,8 +1691,8 @@ usb_async_req(dev_info_t *dip,
 		tq_flag |= TQ_NOQUEUE;
 	}
 
-	if (!taskq_dispatch(system_taskq, func, (void *)arg,
-	    tq_flag)) {
+	if (taskq_dispatch(system_taskq, func, arg,
+	    tq_flag) == TASKQID_INVALID) {
 		USB_DPRINTF_L2(DPRINT_MASK_USBA, usbai_log_handle,
 		    "usb_async_req: failure");
 
@@ -1747,7 +1747,7 @@ usba_async_ph_req(usba_pipe_handle_data_t *ph_data,
 		tq_flag |= TQ_NOQUEUE;
 	}
 
-	if (!taskq_dispatch(taskq, func, (void *)arg, tq_flag)) {
+	if (taskq_dispatch(taskq, func, arg, tq_flag) == TASKQID_INVALID) {
 		USB_DPRINTF_L2(DPRINT_MASK_USBA, usbai_log_handle,
 		    "usba_async_ph_req: failure");
 
diff --git a/usr/src/uts/common/os/console.c b/usr/src/uts/common/os/console.c
index 9145eaf808..e268b71a7c 100644
--- a/usr/src/uts/common/os/console.c
+++ b/usr/src/uts/common/os/console.c
@@ -288,7 +288,7 @@ console_vprintf(const char *fmt, va_list adx)
 		cm->cm_size = sizeof (*cm) + len;
 		(void) vsnprintf(cm->cm_text, len + 1, fmt, adx);
 		if (taskq_dispatch(console_taskq, (task_func_t *)console_putmsg,
-		    cm, TQ_NOSLEEP) != 0)
+		    cm, TQ_NOSLEEP) != TASKQID_INVALID)
 			return;
 		kmem_free(cm, cm->cm_size);
 	}
diff --git a/usr/src/uts/common/os/damap.c b/usr/src/uts/common/os/damap.c
index dc219318c6..d23f54de8d 100644
--- a/usr/src/uts/common/os/damap.c
+++ b/usr/src/uts/common/os/damap.c
@@ -1454,7 +1454,7 @@ dam_addr_stable_cb(void *arg)
 	 */
 	if (spend) {
 		if (taskq_dispatch(system_taskq, dam_stabilize_map,
-		    mapp, TQ_NOSLEEP | TQ_NOQUEUE)) {
+		    mapp, TQ_NOSLEEP | TQ_NOQUEUE) != TASKQID_INVALID) {
 			DTRACE_PROBE2(damap__map__addr__stable__start,
 			    char *, mapp->dam_name, dam_t *, mapp);
 
@@ -1546,7 +1546,7 @@ dam_addrset_stable_cb(void *arg)
 	 */
 	if ((mapp->dam_flags & DAM_SPEND) ||
 	    (taskq_dispatch(system_taskq, dam_stabilize_map, mapp,
-	    TQ_NOSLEEP | TQ_NOQUEUE) == (uintptr_t)NULL)) {
+	    TQ_NOSLEEP | TQ_NOQUEUE) == TASKQID_INVALID)) {
 		DAM_INCR_STAT(mapp, dam_overrun);
 		mapp->dam_stable_overrun++;
 		dam_sched_timeout(dam_addrset_stable_cb, mapp,
diff --git a/usr/src/uts/common/os/ddi_hp_ndi.c b/usr/src/uts/common/os/ddi_hp_ndi.c
index d8cb0de3a2..a41a12fc74 100644
--- a/usr/src/uts/common/os/ddi_hp_ndi.c
+++ b/usr/src/uts/common/os/ddi_hp_ndi.c
@@ -252,8 +252,8 @@ ndi_hp_state_change_req(dev_info_t *dip, char *cn_name,
 	 */
 	ndi_hold_devi(dip);
 
-	if (!taskq_dispatch(system_taskq, ddihp_cn_run_event, eventp,
-	    TQ_NOSLEEP)) {
+	if (taskq_dispatch(system_taskq, ddihp_cn_run_event, eventp,
+	    TQ_NOSLEEP) == TASKQID_INVALID) {
 		ndi_rele_devi(dip);
 		DDI_HP_NEXDBG((CE_CONT, "ndi_hp_state_change_req: "
 		    "taskq_dispatch failed! dip %p "
diff --git a/usr/src/uts/common/os/kmem.c b/usr/src/uts/common/os/kmem.c
index 5f85f396ec..bc0cda418b 100644
--- a/usr/src/uts/common/os/kmem.c
+++ b/usr/src/uts/common/os/kmem.c
@@ -3084,7 +3084,8 @@ kmem_reap_start(void *flag)
 	 * we won't reap again until the current reap completes *and*
 	 * at least kmem_reap_interval ticks have elapsed.
 	 */
-	if (!taskq_dispatch(kmem_taskq, kmem_reap_done, flag, TQ_NOSLEEP))
+	if (taskq_dispatch(kmem_taskq, kmem_reap_done, flag, TQ_NOSLEEP) ==
+	    TASKQID_INVALID)
 		kmem_reap_done(flag);
 }
 
@@ -3103,7 +3104,8 @@ kmem_reap_common(void *flag_arg)
 	 * start the reap going with a TQ_NOALLOC dispatch.  If the dispatch
 	 * fails, we reset the flag, and the next reap will try again.
 	 */
-	if (!taskq_dispatch(kmem_taskq, kmem_reap_start, flag, TQ_NOALLOC))
+	if (taskq_dispatch(kmem_taskq, kmem_reap_start, flag, TQ_NOALLOC) ==
+	    TASKQID_INVALID)
 		*flag = 0;
 }
 
@@ -3378,7 +3380,8 @@ kmem_update(void *dummy)
 	 * kmem_update() becomes self-throttling: it won't schedule
 	 * new tasks until all previous tasks have completed.
 	 */
-	if (!taskq_dispatch(kmem_taskq, kmem_update_timeout, dummy, TQ_NOSLEEP))
+	if (taskq_dispatch(kmem_taskq, kmem_update_timeout, dummy, TQ_NOSLEEP)
+	    == TASKQID_INVALID)
 		kmem_update_timeout(NULL);
 }
 
@@ -4857,8 +4860,8 @@ kmem_move_begin(kmem_cache_t *cp, kmem_slab_t *sp, void *buf, int flags)
 
 	mutex_exit(&cp->cache_lock);
 
-	if (!taskq_dispatch(kmem_move_taskq, (task_func_t *)kmem_move_buffer,
-	    callback, TQ_NOSLEEP)) {
+	if (taskq_dispatch(kmem_move_taskq, (task_func_t *)kmem_move_buffer,
+	    callback, TQ_NOSLEEP) == TASKQID_INVALID) {
 		mutex_enter(&cp->cache_lock);
 		avl_remove(&cp->cache_defrag->kmd_moves_pending, callback);
 		mutex_exit(&cp->cache_lock);
@@ -5205,9 +5208,9 @@ kmem_cache_move_notify(kmem_cache_t *cp, void *buf)
 	if (args != NULL) {
 		args->kmna_cache = cp;
 		args->kmna_buf = buf;
-		if (!taskq_dispatch(kmem_taskq,
+		if (taskq_dispatch(kmem_taskq,
 		    (task_func_t *)kmem_cache_move_notify_task, args,
-		    TQ_NOSLEEP))
+		    TQ_NOSLEEP) == TASKQID_INVALID)
 			kmem_free(args, sizeof (kmem_move_notify_args_t));
 	}
 }
diff --git a/usr/src/uts/common/os/serializer.c b/usr/src/uts/common/os/serializer.c
index e5f11fe8b1..aca6ff4b01 100644
--- a/usr/src/uts/common/os/serializer.c
+++ b/usr/src/uts/common/os/serializer.c
@@ -267,7 +267,7 @@ serializer_enter(serializer_t *s, srproc_t proc, mblk_t *mp, void *arg)
 		 */
 		serializer_enqueue(s, proc, mp, arg);
 	} else {
-		taskqid_t tid = 0;
+		taskqid_t tid = TASKQID_INVALID;
 
 		/*
 		 * If the request list is empty, can process right away,
@@ -314,7 +314,7 @@ serializer_enter(serializer_t *s, srproc_t proc, mblk_t *mp, void *arg)
 					    (task_func_t *)
 					    serializer_drain_completely,
 					    s, TQ_NOSLEEP | TQ_NOQUEUE);
-					if (tid != 0)
+					if (tid != TASKQID_INVALID)
 						s->ser_taskq = B_TRUE;
 				}
 			}
diff --git a/usr/src/uts/common/os/strsubr.c b/usr/src/uts/common/os/strsubr.c
index c19f7cefb7..1ffb561428 100644
--- a/usr/src/uts/common/os/strsubr.c
+++ b/usr/src/uts/common/os/strsubr.c
@@ -4034,7 +4034,7 @@ esballoc_enqueue_mblk(mblk_t *mp)
 {
 
 	if (taskq_dispatch(system_taskq, (task_func_t *)esballoc_mblk_free, mp,
-	    TQ_NOSLEEP) == (uintptr_t)NULL) {
+	    TQ_NOSLEEP) == TASKQID_INVALID) {
 		mblk_t *first_mp = mp;
 		/*
 		 * System is low on resources and can't perform a non-sleeping
diff --git a/usr/src/uts/common/os/sunddi.c b/usr/src/uts/common/os/sunddi.c
index ede7da413b..c39819156d 100644
--- a/usr/src/uts/common/os/sunddi.c
+++ b/usr/src/uts/common/os/sunddi.c
@@ -8906,7 +8906,7 @@ ddi_taskq_dispatch(ddi_taskq_t *tq, void (* func)(void *),
 	taskqid_t id = taskq_dispatch((taskq_t *)tq, func, arg,
 	    dflags == DDI_SLEEP ? TQ_SLEEP : TQ_NOSLEEP);
 
-	return (id != 0 ? DDI_SUCCESS : DDI_FAILURE);
+	return (id != TASKQID_INVALID ? DDI_SUCCESS : DDI_FAILURE);
 }
 
 void
diff --git a/usr/src/uts/common/os/sunpm.c b/usr/src/uts/common/os/sunpm.c
index 80acb8c8f0..2fde5dfd89 100644
--- a/usr/src/uts/common/os/sunpm.c
+++ b/usr/src/uts/common/os/sunpm.c
@@ -995,7 +995,8 @@ pm_rescan(void *arg)
 	 */
 	if (DEVI_IS_ATTACHING(dip) ||
 	    (scanp->ps_scan_flags & PM_SCAN_DISPATCHED) ||
-	    !taskq_dispatch(system_taskq, pm_scan, (void *)dip, TQ_NOSLEEP)) {
+	    taskq_dispatch(system_taskq, pm_scan, (void *)dip, TQ_NOSLEEP) ==
+	    TASKQID_INVALID) {
 		PMD(PMD_SCAN, ("%s: %s@%s(%s#%d): attaching, pm_scan already "
 		    "dispatched or dispatching failed\n", pmf, PM_DEVICE(dip)))
 		if (scanp->ps_scan_id) {
diff --git a/usr/src/uts/common/os/task.c b/usr/src/uts/common/os/task.c
index 91325429a3..c2729f26d1 100644
--- a/usr/src/uts/common/os/task.c
+++ b/usr/src/uts/common/os/task.c
@@ -456,7 +456,7 @@ task_rele(task_t *tk)
 	 * the task fails.
 	 */
 	if (taskq_dispatch(exacct_queue, exacct_commit_task, tk,
-	    TQ_NOSLEEP | TQ_NOQUEUE) == (uintptr_t)NULL) {
+	    TQ_NOSLEEP | TQ_NOQUEUE) == TASKQID_INVALID) {
 		mutex_enter(&task_commit_lock);
 		if (task_commit_head == NULL) {
 			task_commit_head = task_commit_tail = tk;
diff --git a/usr/src/uts/common/os/taskq.c b/usr/src/uts/common/os/taskq.c
index 9a7697d16a..d9fa450c99 100644
--- a/usr/src/uts/common/os/taskq.c
+++ b/usr/src/uts/common/os/taskq.c
@@ -160,7 +160,7 @@
  *	the caller is willing to block for memory.  The function returns an
  *	opaque value which is zero iff dispatch fails.  If flags is TQ_NOSLEEP
  *	or TQ_NOALLOC and the task can't be dispatched, taskq_dispatch() fails
- *	and returns (taskqid_t)0.
+ *	and returns TASKQID_INVALID.
  *
  *	ASSUMES: func != NULL.
  *
@@ -700,7 +700,7 @@ uint_t taskq_smtbf = UINT_MAX;    /* mean time between injected failures */
 	taskq_random = (taskq_random * 2416 + 374441) % 1771875;\
 	if ((flag & TQ_NOSLEEP) &&				\
 	    taskq_random < 1771875 / taskq_dmtbf) {		\
-		return ((taskqid_t)NULL);			\
+		return (TASKQID_INVALID);			\
 	}
 
 #define	TASKQ_S_RANDOM_DISPATCH_FAILURE(tq, flag)		\
@@ -710,7 +710,7 @@ uint_t taskq_smtbf = UINT_MAX;    /* mean time between injected failures */
 	    (tq->tq_nalloc > tq->tq_minalloc)) &&		\
 	    (taskq_random < (1771875 / taskq_smtbf))) {		\
 		mutex_exit(&tq->tq_lock);			\
-		return ((taskqid_t)NULL);			\
+		return (TASKQID_INVALID);			\
 	}
 #else
 #define	TASKQ_S_RANDOM_DISPATCH_FAILURE(tq, flag)
diff --git a/usr/src/uts/common/rpc/clnt_clts.c b/usr/src/uts/common/rpc/clnt_clts.c
index beab2b6a4b..8a90857172 100644
--- a/usr/src/uts/common/rpc/clnt_clts.c
+++ b/usr/src/uts/common/rpc/clnt_clts.c
@@ -1784,7 +1784,7 @@ endpnt_reap_dispatch(void *a)
 	 * endpoint.
 	 */
 	if (taskq_dispatch(endpnt_taskq, (task_func_t *)endpnt_reap, etp,
-	    TQ_NOSLEEP) == NULL)
+	    TQ_NOSLEEP) == TASKQID_INVALID)
 		return;
 	mutex_enter(&etp->e_ilock);
 	etp->e_async_count++;
diff --git a/usr/src/uts/common/sys/taskq.h b/usr/src/uts/common/sys/taskq.h
index 87c68d22f6..0fd72bd891 100644
--- a/usr/src/uts/common/sys/taskq.h
+++ b/usr/src/uts/common/sys/taskq.h
@@ -63,6 +63,8 @@ struct proc;
 #define	TQ_NOALLOC	0x04	/* cannot allocate memory; may fail */
 #define	TQ_FRONT	0x08	/* Put task at the front of the queue */
 
+#define	TASKQID_INVALID	((taskqid_t)0)
+
 #if defined(_KERNEL) || defined(_FAKE_KERNEL)
 
 extern taskq_t *system_taskq;
diff --git a/usr/src/uts/i86pc/vm/vm_machdep.c b/usr/src/uts/i86pc/vm/vm_machdep.c
index cb46bba853..8af60a1d15 100644
--- a/usr/src/uts/i86pc/vm/vm_machdep.c
+++ b/usr/src/uts/i86pc/vm/vm_machdep.c
@@ -2285,7 +2285,7 @@ create_contig_pfnlist(uint_t flags)
 		 */
 		if (!create_contig_pending) {
 			if (taskq_dispatch(system_taskq, call_create_contiglist,
-			    NULL, TQ_NOSLEEP) != NULL)
+			    NULL, TQ_NOSLEEP) != TASKQID_INVALID)
 				create_contig_pending = 1;
 		}
 		contig_pfnlist_buildfailed++;	/* count list build failures */
diff --git a/usr/src/uts/intel/io/ipmi/ipmi_kcs.c b/usr/src/uts/intel/io/ipmi/ipmi_kcs.c
index 08302639b8..58040768ca 100644
--- a/usr/src/uts/intel/io/ipmi/ipmi_kcs.c
+++ b/usr/src/uts/intel/io/ipmi/ipmi_kcs.c
@@ -474,7 +474,7 @@ kcs_startup(struct ipmi_softc *sc)
 	    curzone->zone_zsched, TASKQ_PREPOPULATE);
 
 	if (taskq_dispatch(sc->ipmi_kthread, kcs_loop, (void *) sc,
-	    TQ_SLEEP) == NULL) {
+	    TQ_SLEEP) == TASKQID_INVALID) {
 		taskq_destroy(sc->ipmi_kthread);
 		return (1);
 	}
diff --git a/usr/src/uts/sun4u/cpu/us3_common.c b/usr/src/uts/sun4u/cpu/us3_common.c
index 00e8e39483..22477e2a4c 100644
--- a/usr/src/uts/sun4u/cpu/us3_common.c
+++ b/usr/src/uts/sun4u/cpu/us3_common.c
@@ -6069,8 +6069,8 @@ scrub_ecache_line_intr(caddr_t arg1, caddr_t arg2)
 static void
 cpu_delayed_check_ce_errors(void *arg)
 {
-	if (!taskq_dispatch(ch_check_ce_tq, cpu_check_ce_errors, arg,
-	    TQ_NOSLEEP)) {
+	if (taskq_dispatch(ch_check_ce_tq, cpu_check_ce_errors, arg,
+	    TQ_NOSLEEP) == TASKQID_INVALID) {
 		(void) timeout(cpu_delayed_check_ce_errors, arg,
 		    drv_usectohz((clock_t)cpu_ceen_delay_secs * MICROSEC));
 	}
diff --git a/usr/src/uts/sun4u/os/plat_ecc_unum.c b/usr/src/uts/sun4u/os/plat_ecc_unum.c
index 8f694f7d6f..e13e121086 100644
--- a/usr/src/uts/sun4u/os/plat_ecc_unum.c
+++ b/usr/src/uts/sun4u/os/plat_ecc_unum.c
@@ -1044,7 +1044,7 @@ plat_ecc_dispatch_task(plat_ecc_message_t *msg)
 	ASSERT(plat_ecc_taskq != NULL);
 
 	if (taskq_dispatch(plat_ecc_taskq, plat_ecc_send_msg,
-	    (void *)msg, TQ_NOSLEEP) == NULL) {
+	    (void *)msg, TQ_NOSLEEP) == TASKQID_INVALID) {
 		kmem_free(msg->ecc_msg_data, msg->ecc_msg_len);
 		kmem_free(msg, sizeof (plat_ecc_message_t));
 		return (ENOMEM);
diff --git a/usr/src/uts/sun4u/serengeti/io/sgsbbc_mailbox.c b/usr/src/uts/sun4u/serengeti/io/sgsbbc_mailbox.c
index 63ff8515a2..efe2841c1e 100644
--- a/usr/src/uts/sun4u/serengeti/io/sgsbbc_mailbox.c
+++ b/usr/src/uts/sun4u/serengeti/io/sgsbbc_mailbox.c
@@ -2817,7 +2817,7 @@ sbbc_mbox_queue_ecc_event(sbbc_ecc_mbox_t *sbbc_ecc_msgp)
 
 	if (taskq_dispatch(sbbc_ecc_mbox_taskq,
 	    (task_func_t *)sbbc_mbox_ecc_output, sbbc_ecc_msgp,
-	    TQ_NOSLEEP) == NULL) {
+	    TQ_NOSLEEP) == TASKQID_INVALID) {
 
 		if (sbbc_ecc_mbox_taskq_errs == 0) {
 			cmn_err(CE_NOTE, "Unable to send ECC event "
diff --git a/usr/src/uts/sun4u/starcat/io/drmach.c b/usr/src/uts/sun4u/starcat/io/drmach.c
index a5966aa4ab..addcd5ce4d 100644
--- a/usr/src/uts/sun4u/starcat/io/drmach.c
+++ b/usr/src/uts/sun4u/starcat/io/drmach.c
@@ -1700,7 +1700,7 @@ drmach_mbox_event(void)
 		/* schedule a reinit handshake if one isn't pending */
 		if (!drmach_mbox_ipending) {
 			if (taskq_dispatch(system_taskq, drmach_mbox_reinit,
-			    NULL, TQ_NOSLEEP) != NULL) {
+			    NULL, TQ_NOSLEEP) != TASKQID_INVALID) {
 				drmach_mbox_ipending = 1;
 			} else {
 				cmn_err(CE_WARN,
@@ -1727,7 +1727,7 @@ drmach_mbox_event(void)
 			if (!drmach_mbox_ipending) {
 				if (taskq_dispatch(system_taskq,
 				    drmach_mbox_reinit, NULL, TQ_NOSLEEP)
-				    != NULL) {
+				    != TASKQID_INVALID) {
 					drmach_mbox_ipending = 1;
 				} else {
 					cmn_err(CE_WARN, "failed to schedule "
@@ -1889,7 +1889,7 @@ drmach_mbox_getmsg()
 			if (!drmach_mbox_ipending) {
 				if (taskq_dispatch(system_taskq,
 				    drmach_mbox_reinit, NULL, TQ_NOSLEEP)
-				    != NULL) {
+				    != TASKQID_INVALID) {
 					drmach_mbox_ipending = 1;
 				} else {
 					cmn_err(CE_WARN, "failed to schedule "
diff --git a/usr/src/uts/sun4u/starcat/io/schpc.c b/usr/src/uts/sun4u/starcat/io/schpc.c
index 921012693d..6b22e06a71 100644
--- a/usr/src/uts/sun4u/starcat/io/schpc.c
+++ b/usr/src/uts/sun4u/starcat/io/schpc.c
@@ -2699,7 +2699,7 @@ schpc_event_filter(pcimsg_t *pmsg)
 		    "event alloc'd");
 
 		if (taskq_dispatch(schpc_event_taskq, schpc_event_handler,
-		    (void *)pevent, TQ_SLEEP) == NULL) {
+		    (void *)pevent, TQ_SLEEP) == TASKQID_INVALID) {
 			cmn_err(CE_WARN, "schpc: schpc_event_filter - "
 			    "taskq_dispatch failed to enqueue event");
 			kmem_free(pevent, sizeof (pcimsg_t));
diff --git a/usr/src/uts/sun4u/starcat/io/sckmdrv.c b/usr/src/uts/sun4u/starcat/io/sckmdrv.c
index 392d961ea2..4882ece935 100644
--- a/usr/src/uts/sun4u/starcat/io/sckmdrv.c
+++ b/usr/src/uts/sun4u/starcat/io/sckmdrv.c
@@ -650,7 +650,8 @@ sckm_mbox_callback(void)
 		return;
 	}
 
-	if (!taskq_dispatch(sckm_taskq, sckm_mbox_task, NULL, KM_NOSLEEP)) {
+	if (taskq_dispatch(sckm_taskq, sckm_mbox_task, NULL, KM_NOSLEEP) ==
+	    TASKQID_INVALID) {
 		/*
 		 * Too many tasks already pending. Do not queue a new
 		 * request.
diff --git a/usr/src/uts/sun4u/starcat/io/scosmb.c b/usr/src/uts/sun4u/starcat/io/scosmb.c
index 93b99de999..597f3d91e4 100644
--- a/usr/src/uts/sun4u/starcat/io/scosmb.c
+++ b/usr/src/uts/sun4u/starcat/io/scosmb.c
@@ -1242,7 +1242,7 @@ scosmb_log_ecc_error(plat_ecc_message_type_t msg_type, void *datap)
 		 */
 		if (taskq_dispatch(scosmb_output_taskq,
 		    (task_func_t *)scosmb_process_output,
-		    (void *)msg_header_ptr, TQ_NOSLEEP) == 0) {
+		    (void *)msg_header_ptr, TQ_NOSLEEP) == TASKQID_INVALID) {
 #ifdef DEBUG
 			cmn_err(CE_WARN, "failed to dispatch a task to send "
 			    "ECC mailbox message.");
diff --git a/usr/src/uts/sun4v/io/ds_drv.c b/usr/src/uts/sun4v/io/ds_drv.c
index 34caf542d0..2b2ba29e52 100644
--- a/usr/src/uts/sun4v/io/ds_drv.c
+++ b/usr/src/uts/sun4v/io/ds_drv.c
@@ -408,7 +408,7 @@ ds_init()
 int
 ds_sys_dispatch_func(void (func)(void *), void *arg)
 {
-	return (DS_DISPATCH(func, arg) == NULL);
+	return (DS_DISPATCH(func, arg) == TASKQID_INVALID);
 }
 
 /*
@@ -758,7 +758,7 @@ ds_log_add_msg(int32_t dest, uint8_t *msg, size_t sz)
 		DS_DBG_LOG(CE_NOTE, "%s: log exceeded %d bytes, scheduling"
 		    " a purge...", __func__, DS_LOG_LIMIT);
 
-		if (DS_DISPATCH(ds_log_purge, NULL) == NULL) {
+		if (DS_DISPATCH(ds_log_purge, NULL) == TASKQID_INVALID) {
 			cmn_err(CE_NOTE, "%s: purge thread failed to start",
 			    __func__);
 		}
diff --git a/usr/src/uts/sun4v/io/vdc.c b/usr/src/uts/sun4v/io/vdc.c
index 77619e38fe..ccea7403ea 100644
--- a/usr/src/uts/sun4v/io/vdc.c
+++ b/usr/src/uts/sun4v/io/vdc.c
@@ -1342,7 +1342,7 @@ vdc_open(dev_t *dev, int flag, int otyp, cred_t *cred)
 
 		/* call vdc_validate() asynchronously to avoid blocking */
 		if (taskq_dispatch(system_taskq, vdc_validate_task,
-		    (void *)vdc, TQ_NOSLEEP) == NULL) {
+		    (void *)vdc, TQ_NOSLEEP) == TASKQID_INVALID) {
 			vdc_mark_closed(vdc, slice, flag, otyp);
 			mutex_exit(&vdc->lock);
 			return (ENXIO);
@@ -7572,7 +7572,7 @@ vd_process_ioctl(dev_t dev, int cmd, caddr_t arg, int mode, int *rvalp)
 			/* put the request on a task queue */
 			rv = taskq_dispatch(system_taskq, vdc_dkio_flush_cb,
 			    (void *)dkarg, DDI_SLEEP);
-			if (rv == NULL) {
+			if (rv == TASKQID_INVALID) {
 				/* clean up if dispatch fails */
 				mutex_enter(&vdc->lock);
 				vdc->dkio_flush_pending--;