1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
23  */
24 
25 #include <sys/cpuvar.h>
26 #include <sys/types.h>
27 #include <sys/conf.h>
28 #include <sys/stat.h>
29 #include <sys/file.h>
30 #include <sys/ddi.h>
31 #include <sys/sunddi.h>
32 #include <sys/modctl.h>
33 #include <sys/sysmacros.h>
34 #include <sys/socket.h>
35 #include <sys/strsubr.h>
36 #include <sys/nvpair.h>
37 
38 #include <sys/stmf.h>
39 #include <sys/stmf_ioctl.h>
40 #include <sys/portif.h>
41 #include <sys/idm/idm.h>
42 #include <sys/idm/idm_conn_sm.h>
43 #include <iscsit_isns.h>
44 #include <iscsit.h>
45 
46 #define	ISCSIT_VERSION		BUILD_DATE "-1.18dev"
47 #define	ISCSIT_NAME_VERSION	"COMSTAR ISCSIT v" ISCSIT_VERSION
48 
49 /*
50  * DDI entry points.
51  */
52 static int iscsit_drv_attach(dev_info_t *, ddi_attach_cmd_t);
53 static int iscsit_drv_detach(dev_info_t *, ddi_detach_cmd_t);
54 static int iscsit_drv_getinfo(dev_info_t *, ddi_info_cmd_t, void *, void **);
55 static int iscsit_drv_open(dev_t *, int, int, cred_t *);
56 static int iscsit_drv_close(dev_t, int, int, cred_t *);
57 static boolean_t iscsit_drv_busy(void);
58 static int iscsit_drv_ioctl(dev_t, int, intptr_t, int, cred_t *, int *);
59 
60 extern struct mod_ops mod_miscops;
61 
62 
63 static struct cb_ops iscsit_cb_ops = {
64 	iscsit_drv_open,	/* cb_open */
65 	iscsit_drv_close,	/* cb_close */
66 	nodev,			/* cb_strategy */
67 	nodev,			/* cb_print */
68 	nodev,			/* cb_dump */
69 	nodev,			/* cb_read */
70 	nodev,			/* cb_write */
71 	iscsit_drv_ioctl,	/* cb_ioctl */
72 	nodev,			/* cb_devmap */
73 	nodev,			/* cb_mmap */
74 	nodev,			/* cb_segmap */
75 	nochpoll,		/* cb_chpoll */
76 	ddi_prop_op,		/* cb_prop_op */
77 	NULL,			/* cb_streamtab */
78 	D_MP,			/* cb_flag */
79 	CB_REV,			/* cb_rev */
80 	nodev,			/* cb_aread */
81 	nodev,			/* cb_awrite */
82 };
83 
84 static struct dev_ops iscsit_dev_ops = {
85 	DEVO_REV,		/* devo_rev */
86 	0,			/* devo_refcnt */
87 	iscsit_drv_getinfo,	/* devo_getinfo */
88 	nulldev,		/* devo_identify */
89 	nulldev,		/* devo_probe */
90 	iscsit_drv_attach,	/* devo_attach */
91 	iscsit_drv_detach,	/* devo_detach */
92 	nodev,			/* devo_reset */
93 	&iscsit_cb_ops,		/* devo_cb_ops */
94 	NULL,			/* devo_bus_ops */
95 	NULL,			/* devo_power */
96 	ddi_quiesce_not_needed,	/* quiesce */
97 };
98 
99 static struct modldrv modldrv = {
100 	&mod_driverops,
101 	"iSCSI Target",
102 	&iscsit_dev_ops,
103 };
104 
105 static struct modlinkage modlinkage = {
106 	MODREV_1,
107 	&modldrv,
108 	NULL,
109 };
110 
111 
112 iscsit_global_t iscsit_global;
113 
114 kmem_cache_t	*iscsit_status_pdu_cache;
115 
116 boolean_t	iscsit_sm_logging = B_FALSE;
117 
118 static idm_status_t iscsit_init(dev_info_t *dip);
119 static idm_status_t iscsit_enable_svc(iscsit_hostinfo_t *hostinfo);
120 static void iscsit_disable_svc(void);
121 
122 static int
123 iscsit_check_cmdsn_and_queue(idm_pdu_t *rx_pdu);
124 
125 static void
126 iscsit_add_pdu_to_queue(iscsit_sess_t *ist, idm_pdu_t *rx_pdu);
127 
128 static idm_pdu_t *
129 iscsit_remove_pdu_from_queue(iscsit_sess_t *ist, uint32_t cmdsn);
130 
131 static void
132 iscsit_process_pdu_in_queue(iscsit_sess_t *ist);
133 
134 static void
135 iscsit_rxpdu_queue_monitor_session(iscsit_sess_t *ist);
136 
137 static void
138 iscsit_rxpdu_queue_monitor(void *arg);
139 
140 static void
141 iscsit_post_staged_pdu(idm_pdu_t *rx_pdu);
142 
143 static void
144 iscsit_post_scsi_cmd(idm_conn_t *ic, idm_pdu_t *rx_pdu);
145 
146 static void
147 iscsit_op_scsi_task_mgmt(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
148 
149 static void
150 iscsit_pdu_op_noop(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
151 
152 static void
153 iscsit_pdu_op_login_cmd(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
154 
155 void
156 iscsit_pdu_op_text_cmd(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
157 
158 static void
159 iscsit_pdu_op_logout_cmd(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
160 
161 int iscsit_cmd_window();
162 
163 static  int
164 iscsit_sna_lt(uint32_t sn1, uint32_t sn2);
165 
166 void
167 iscsit_set_cmdsn(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
168 
169 static void
170 iscsit_deferred_dispatch(idm_pdu_t *rx_pdu);
171 
172 static void
173 iscsit_deferred(void *rx_pdu_void);
174 
175 static idm_status_t
176 iscsit_conn_accept(idm_conn_t *ic);
177 
178 static idm_status_t
179 iscsit_ffp_enabled(idm_conn_t *ic);
180 
181 static idm_status_t
182 iscsit_ffp_disabled(idm_conn_t *ic, idm_ffp_disable_t disable_class);
183 
184 static idm_status_t
185 iscsit_conn_lost(idm_conn_t *ic);
186 
187 static idm_status_t
188 iscsit_conn_destroy(idm_conn_t *ic);
189 
190 static stmf_data_buf_t *
191 iscsit_dbuf_alloc(scsi_task_t *task, uint32_t size, uint32_t *pminsize,
192     uint32_t flags);
193 
194 static void
195 iscsit_dbuf_free(stmf_dbuf_store_t *ds, stmf_data_buf_t *dbuf);
196 
197 static void
198 iscsit_buf_xfer_cb(idm_buf_t *idb, idm_status_t status);
199 
200 static void
201 iscsit_send_good_status_done(idm_pdu_t *pdu, idm_status_t status);
202 
203 static void
204 iscsit_send_status_done(idm_pdu_t *pdu, idm_status_t status);
205 
206 static stmf_status_t
207 iscsit_idm_to_stmf(idm_status_t idmrc);
208 
209 static iscsit_task_t *
210 iscsit_task_alloc(iscsit_conn_t *ict);
211 
212 static void
213 iscsit_task_free(iscsit_task_t *itask);
214 
215 static iscsit_task_t *
216 iscsit_tm_task_alloc(iscsit_conn_t *ict);
217 
218 static void
219 iscsit_tm_task_free(iscsit_task_t *itask);
220 
221 static idm_status_t
222 iscsit_task_start(iscsit_task_t *itask);
223 
224 static void
225 iscsit_task_done(iscsit_task_t *itask);
226 
227 static int
228 iscsit_status_pdu_constructor(void *pdu_void, void *arg, int flags);
229 
230 static void
231 iscsit_pp_cb(struct stmf_port_provider *pp, int cmd, void *arg, uint32_t flags);
232 
233 static it_cfg_status_t
234 iscsit_config_merge(it_config_t *cfg);
235 
236 static idm_status_t
237 iscsit_login_fail(idm_conn_t *ic);
238 
239 static boolean_t iscsit_cmdsn_in_window(iscsit_conn_t *ict, uint32_t cmdsn);
240 static void iscsit_send_direct_scsi_resp(iscsit_conn_t *ict, idm_pdu_t *rx_pdu,
241     uint8_t response, uint8_t cmd_status);
242 static void iscsit_send_task_mgmt_resp(idm_pdu_t *tm_resp_pdu,
243     uint8_t tm_status);
244 
245 /*
246  * MC/S: Out-of-order commands are staged on a session-wide wait
247  * queue until a system-tunable threshold is reached. A separate
248  * thread is used to scan the staging queue on all the session,
249  * If a delayed PDU does not arrive within a timeout, the target
250  * will advance to the staged PDU that is next in sequence, skipping
251  * over the missing PDU(s) to go past a hole in the sequence.
252  */
253 volatile int rxpdu_queue_threshold = ISCSIT_RXPDU_QUEUE_THRESHOLD;
254 
255 static kmutex_t		iscsit_rxpdu_queue_monitor_mutex;
256 kthread_t		*iscsit_rxpdu_queue_monitor_thr_id;
257 static kt_did_t		iscsit_rxpdu_queue_monitor_thr_did;
258 static boolean_t	iscsit_rxpdu_queue_monitor_thr_running;
259 static kcondvar_t	iscsit_rxpdu_queue_monitor_cv;
260 
261 int
262 _init(void)
263 {
264 	int rc;
265 
266 	rw_init(&iscsit_global.global_rwlock, NULL, RW_DRIVER, NULL);
267 	mutex_init(&iscsit_global.global_state_mutex, NULL,
268 	    MUTEX_DRIVER, NULL);
269 	iscsit_global.global_svc_state = ISE_DETACHED;
270 
271 	mutex_init(&iscsit_rxpdu_queue_monitor_mutex, NULL,
272 	    MUTEX_DRIVER, NULL);
273 	iscsit_rxpdu_queue_monitor_thr_id = NULL;
274 	iscsit_rxpdu_queue_monitor_thr_running = B_FALSE;
275 	cv_init(&iscsit_rxpdu_queue_monitor_cv, NULL, CV_DEFAULT, NULL);
276 
277 	if ((rc = mod_install(&modlinkage)) != 0) {
278 		mutex_destroy(&iscsit_global.global_state_mutex);
279 		rw_destroy(&iscsit_global.global_rwlock);
280 		return (rc);
281 	}
282 
283 	return (rc);
284 }
285 
286 int
287 _info(struct modinfo *modinfop)
288 {
289 	return (mod_info(&modlinkage, modinfop));
290 }
291 
292 int
293 _fini(void)
294 {
295 	int rc;
296 
297 	rc = mod_remove(&modlinkage);
298 
299 	if (rc == 0) {
300 		mutex_destroy(&iscsit_rxpdu_queue_monitor_mutex);
301 		cv_destroy(&iscsit_rxpdu_queue_monitor_cv);
302 		mutex_destroy(&iscsit_global.global_state_mutex);
303 		rw_destroy(&iscsit_global.global_rwlock);
304 	}
305 
306 	return (rc);
307 }
308 
309 /*
310  * DDI entry points.
311  */
312 
313 /* ARGSUSED */
314 static int
315 iscsit_drv_getinfo(dev_info_t *dip, ddi_info_cmd_t cmd, void *arg,
316     void **result)
317 {
318 	ulong_t instance = getminor((dev_t)arg);
319 
320 	switch (cmd) {
321 	case DDI_INFO_DEVT2DEVINFO:
322 		*result = iscsit_global.global_dip;
323 		return (DDI_SUCCESS);
324 
325 	case DDI_INFO_DEVT2INSTANCE:
326 		*result = (void *)instance;
327 		return (DDI_SUCCESS);
328 
329 	default:
330 		break;
331 	}
332 
333 	return (DDI_FAILURE);
334 }
335 
336 static int
337 iscsit_drv_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
338 {
339 	if (cmd != DDI_ATTACH) {
340 		return (DDI_FAILURE);
341 	}
342 
343 	if (ddi_get_instance(dip) != 0) {
344 		/* we only allow instance 0 to attach */
345 		return (DDI_FAILURE);
346 	}
347 
348 	/* create the minor node */
349 	if (ddi_create_minor_node(dip, ISCSIT_MODNAME, S_IFCHR, 0,
350 	    DDI_PSEUDO, 0) != DDI_SUCCESS) {
351 		cmn_err(CE_WARN, "iscsit_drv_attach: "
352 		    "failed creating minor node");
353 		return (DDI_FAILURE);
354 	}
355 
356 	if (iscsit_init(dip) != IDM_STATUS_SUCCESS) {
357 		cmn_err(CE_WARN, "iscsit_drv_attach: "
358 		    "failed to initialize");
359 		ddi_remove_minor_node(dip, NULL);
360 		return (DDI_FAILURE);
361 	}
362 
363 	iscsit_global.global_svc_state = ISE_DISABLED;
364 	iscsit_global.global_dip = dip;
365 
366 	return (DDI_SUCCESS);
367 }
368 
369 /*ARGSUSED*/
370 static int
371 iscsit_drv_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
372 {
373 	if (cmd != DDI_DETACH)
374 		return (DDI_FAILURE);
375 
376 	/*
377 	 * drv_detach is called in a context that owns the
378 	 * device node for the /dev/pseudo device.  If this thread blocks
379 	 * for any resource, other threads that need the /dev/pseudo device
380 	 * may end up in a deadlock with this thread.Hence, we use a
381 	 * separate lock just for the structures that drv_detach needs
382 	 * to access.
383 	 */
384 	mutex_enter(&iscsit_global.global_state_mutex);
385 	if (iscsit_drv_busy()) {
386 		mutex_exit(&iscsit_global.global_state_mutex);
387 		return (EBUSY);
388 	}
389 
390 	iscsit_global.global_dip = NULL;
391 	ddi_remove_minor_node(dip, NULL);
392 
393 	ldi_ident_release(iscsit_global.global_li);
394 	iscsit_global.global_svc_state = ISE_DETACHED;
395 
396 	mutex_exit(&iscsit_global.global_state_mutex);
397 
398 	return (DDI_SUCCESS);
399 }
400 
401 /*ARGSUSED*/
402 static int
403 iscsit_drv_open(dev_t *devp, int flag, int otyp, cred_t *credp)
404 {
405 	return (0);
406 }
407 
408 /* ARGSUSED */
409 static int
410 iscsit_drv_close(dev_t dev, int flag, int otyp, cred_t *credp)
411 {
412 	return (0);
413 }
414 
415 static boolean_t
416 iscsit_drv_busy(void)
417 {
418 	ASSERT(MUTEX_HELD(&iscsit_global.global_state_mutex));
419 
420 	switch (iscsit_global.global_svc_state) {
421 	case ISE_DISABLED:
422 	case ISE_DETACHED:
423 		return (B_FALSE);
424 	default:
425 		return (B_TRUE);
426 	}
427 	/* NOTREACHED */
428 }
429 
430 /* ARGSUSED */
431 static int
432 iscsit_drv_ioctl(dev_t drv, int cmd, intptr_t argp, int flag, cred_t *cred,
433     int *retval)
434 {
435 	iscsit_ioc_set_config_t		setcfg;
436 	iscsit_ioc_set_config32_t	setcfg32;
437 	char				*cfg_pnvlist = NULL;
438 	nvlist_t			*cfg_nvlist = NULL;
439 	it_config_t			*cfg = NULL;
440 	idm_status_t			idmrc;
441 	int				rc = 0;
442 
443 	if (drv_priv(cred) != 0) {
444 		return (EPERM);
445 	}
446 
447 	mutex_enter(&iscsit_global.global_state_mutex);
448 
449 	/*
450 	 * Validate ioctl requests against global service state
451 	 */
452 	switch (iscsit_global.global_svc_state) {
453 	case ISE_ENABLED:
454 		if (cmd == ISCSIT_IOC_DISABLE_SVC) {
455 			iscsit_global.global_svc_state = ISE_DISABLING;
456 		} else if (cmd == ISCSIT_IOC_ENABLE_SVC) {
457 			/* Already enabled */
458 			mutex_exit(&iscsit_global.global_state_mutex);
459 			return (0);
460 		} else {
461 			iscsit_global.global_svc_state = ISE_BUSY;
462 		}
463 		break;
464 	case ISE_DISABLED:
465 		if (cmd == ISCSIT_IOC_ENABLE_SVC) {
466 			iscsit_global.global_svc_state = ISE_ENABLING;
467 		} else if (cmd == ISCSIT_IOC_DISABLE_SVC) {
468 			/* Already disabled */
469 			mutex_exit(&iscsit_global.global_state_mutex);
470 			return (0);
471 		} else {
472 			rc = EFAULT;
473 		}
474 		break;
475 	case ISE_BUSY:
476 	case ISE_ENABLING:
477 	case ISE_DISABLING:
478 		rc = EAGAIN;
479 		break;
480 	case ISE_DETACHED:
481 	default:
482 		rc = EFAULT;
483 		break;
484 	}
485 
486 	mutex_exit(&iscsit_global.global_state_mutex);
487 	if (rc != 0)
488 		return (rc);
489 
490 	/* Handle ioctl request (enable/disable have already been handled) */
491 	switch (cmd) {
492 	case ISCSIT_IOC_SET_CONFIG:
493 		/* Any errors must set state back to ISE_ENABLED */
494 		switch (ddi_model_convert_from(flag & FMODELS)) {
495 		case DDI_MODEL_ILP32:
496 			if (ddi_copyin((void *)argp, &setcfg32,
497 			    sizeof (iscsit_ioc_set_config32_t), flag) != 0) {
498 				rc = EFAULT;
499 				goto cleanup;
500 			}
501 
502 			setcfg.set_cfg_pnvlist =
503 			    (char *)((uintptr_t)setcfg32.set_cfg_pnvlist);
504 			setcfg.set_cfg_vers = setcfg32.set_cfg_vers;
505 			setcfg.set_cfg_pnvlist_len =
506 			    setcfg32.set_cfg_pnvlist_len;
507 			break;
508 		case DDI_MODEL_NONE:
509 			if (ddi_copyin((void *)argp, &setcfg,
510 			    sizeof (iscsit_ioc_set_config_t), flag) != 0) {
511 				rc = EFAULT;
512 				goto cleanup;
513 			}
514 			break;
515 		default:
516 			rc = EFAULT;
517 			goto cleanup;
518 		}
519 
520 		/* Check API version */
521 		if (setcfg.set_cfg_vers != ISCSIT_API_VERS0) {
522 			rc = EINVAL;
523 			goto cleanup;
524 		}
525 
526 		/* Config is in packed nvlist format so unpack it */
527 		cfg_pnvlist = kmem_alloc(setcfg.set_cfg_pnvlist_len,
528 		    KM_SLEEP);
529 		ASSERT(cfg_pnvlist != NULL);
530 
531 		if (ddi_copyin(setcfg.set_cfg_pnvlist, cfg_pnvlist,
532 		    setcfg.set_cfg_pnvlist_len, flag) != 0) {
533 			rc = EFAULT;
534 			goto cleanup;
535 		}
536 
537 		rc = nvlist_unpack(cfg_pnvlist, setcfg.set_cfg_pnvlist_len,
538 		    &cfg_nvlist, KM_SLEEP);
539 		if (rc != 0) {
540 			goto cleanup;
541 		}
542 
543 		/* Translate nvlist */
544 		rc = it_nv_to_config(cfg_nvlist, &cfg);
545 		if (rc != 0) {
546 			cmn_err(CE_WARN, "Configuration is invalid");
547 			goto cleanup;
548 		}
549 
550 		/* Update config */
551 		rc = iscsit_config_merge(cfg);
552 		/* FALLTHROUGH */
553 
554 cleanup:
555 		if (cfg)
556 			it_config_free_cmn(cfg);
557 		if (cfg_pnvlist)
558 			kmem_free(cfg_pnvlist, setcfg.set_cfg_pnvlist_len);
559 		if (cfg_nvlist)
560 			nvlist_free(cfg_nvlist);
561 
562 		/*
563 		 * Now that the reconfig is complete set our state back to
564 		 * enabled.
565 		 */
566 		mutex_enter(&iscsit_global.global_state_mutex);
567 		iscsit_global.global_svc_state = ISE_ENABLED;
568 		mutex_exit(&iscsit_global.global_state_mutex);
569 		break;
570 	case ISCSIT_IOC_ENABLE_SVC: {
571 		iscsit_hostinfo_t hostinfo;
572 
573 		if (ddi_copyin((void *)argp, &hostinfo.length,
574 		    sizeof (hostinfo.length), flag) != 0) {
575 			mutex_enter(&iscsit_global.global_state_mutex);
576 			iscsit_global.global_svc_state = ISE_DISABLED;
577 			mutex_exit(&iscsit_global.global_state_mutex);
578 			return (EFAULT);
579 		}
580 
581 		if (hostinfo.length > sizeof (hostinfo.fqhn))
582 			hostinfo.length = sizeof (hostinfo.fqhn);
583 
584 		if (ddi_copyin((void *)((caddr_t)argp +
585 		    sizeof (hostinfo.length)), &hostinfo.fqhn,
586 		    hostinfo.length, flag) != 0) {
587 			mutex_enter(&iscsit_global.global_state_mutex);
588 			iscsit_global.global_svc_state = ISE_DISABLED;
589 			mutex_exit(&iscsit_global.global_state_mutex);
590 			return (EFAULT);
591 		}
592 
593 		idmrc = iscsit_enable_svc(&hostinfo);
594 		mutex_enter(&iscsit_global.global_state_mutex);
595 		if (idmrc == IDM_STATUS_SUCCESS) {
596 			iscsit_global.global_svc_state = ISE_ENABLED;
597 		} else {
598 			rc = EIO;
599 			iscsit_global.global_svc_state = ISE_DISABLED;
600 		}
601 		mutex_exit(&iscsit_global.global_state_mutex);
602 		break;
603 	}
604 	case ISCSIT_IOC_DISABLE_SVC:
605 		iscsit_disable_svc();
606 		mutex_enter(&iscsit_global.global_state_mutex);
607 		iscsit_global.global_svc_state = ISE_DISABLED;
608 		mutex_exit(&iscsit_global.global_state_mutex);
609 		break;
610 
611 	default:
612 		rc = EINVAL;
613 		mutex_enter(&iscsit_global.global_state_mutex);
614 		iscsit_global.global_svc_state = ISE_ENABLED;
615 		mutex_exit(&iscsit_global.global_state_mutex);
616 	}
617 
618 	return (rc);
619 }
620 
621 static idm_status_t
622 iscsit_init(dev_info_t *dip)
623 {
624 	int			rc;
625 
626 	rc = ldi_ident_from_dip(dip, &iscsit_global.global_li);
627 	ASSERT(rc == 0);  /* Failure indicates invalid argument */
628 
629 	iscsit_global.global_svc_state = ISE_DISABLED;
630 
631 	return (IDM_STATUS_SUCCESS);
632 }
633 
634 /*
635  * iscsit_enable_svc
636  *
637  * registers all the configured targets and target portals with STMF
638  */
639 static idm_status_t
640 iscsit_enable_svc(iscsit_hostinfo_t *hostinfo)
641 {
642 	stmf_port_provider_t	*pp;
643 	stmf_dbuf_store_t	*dbuf_store;
644 	boolean_t		did_iscsit_isns_init;
645 	idm_status_t		retval = IDM_STATUS_SUCCESS;
646 
647 	ASSERT(iscsit_global.global_svc_state == ISE_ENABLING);
648 
649 	/*
650 	 * Make sure that can tell if we have partially allocated
651 	 * in case we need to exit and tear down anything allocated.
652 	 */
653 	iscsit_global.global_tsih_pool = NULL;
654 	iscsit_global.global_dbuf_store = NULL;
655 	iscsit_status_pdu_cache = NULL;
656 	pp = NULL;
657 	iscsit_global.global_pp = NULL;
658 	iscsit_global.global_default_tpg = NULL;
659 	did_iscsit_isns_init = B_FALSE;
660 	iscsit_global.global_dispatch_taskq = NULL;
661 
662 	/* Setup remaining fields in iscsit_global_t */
663 	idm_refcnt_init(&iscsit_global.global_refcnt,
664 	    &iscsit_global);
665 
666 	avl_create(&iscsit_global.global_discovery_sessions,
667 	    iscsit_sess_avl_compare, sizeof (iscsit_sess_t),
668 	    offsetof(iscsit_sess_t, ist_tgt_ln));
669 
670 	avl_create(&iscsit_global.global_target_list,
671 	    iscsit_tgt_avl_compare, sizeof (iscsit_tgt_t),
672 	    offsetof(iscsit_tgt_t, target_global_ln));
673 
674 	list_create(&iscsit_global.global_deleted_target_list,
675 	    sizeof (iscsit_tgt_t),
676 	    offsetof(iscsit_tgt_t, target_global_deleted_ln));
677 
678 	avl_create(&iscsit_global.global_tpg_list,
679 	    iscsit_tpg_avl_compare, sizeof (iscsit_tpg_t),
680 	    offsetof(iscsit_tpg_t, tpg_global_ln));
681 
682 	avl_create(&iscsit_global.global_ini_list,
683 	    iscsit_ini_avl_compare, sizeof (iscsit_ini_t),
684 	    offsetof(iscsit_ini_t, ini_global_ln));
685 
686 	iscsit_global.global_tsih_pool = vmem_create("iscsit_tsih_pool",
687 	    (void *)1, ISCSI_MAX_TSIH, 1, NULL, NULL, NULL, 0,
688 	    VM_SLEEP | VMC_IDENTIFIER);
689 
690 	/*
691 	 * Setup STMF dbuf store.  Our buffers are bound to a specific
692 	 * connection so we really can't let STMF cache buffers for us.
693 	 * Consequently we'll just allocate one global buffer store.
694 	 */
695 	dbuf_store = stmf_alloc(STMF_STRUCT_DBUF_STORE, 0, 0);
696 	if (dbuf_store == NULL) {
697 		retval = IDM_STATUS_FAIL;
698 		goto tear_down_and_return;
699 	}
700 	dbuf_store->ds_alloc_data_buf = iscsit_dbuf_alloc;
701 	dbuf_store->ds_free_data_buf = iscsit_dbuf_free;
702 	dbuf_store->ds_port_private = NULL;
703 	iscsit_global.global_dbuf_store = dbuf_store;
704 
705 	/* Status PDU cache */
706 	iscsit_status_pdu_cache = kmem_cache_create("iscsit_status_pdu_cache",
707 	    sizeof (idm_pdu_t) + sizeof (iscsi_scsi_rsp_hdr_t), 8,
708 	    &iscsit_status_pdu_constructor,
709 	    NULL, NULL, NULL, NULL, KM_SLEEP);
710 
711 	/* Default TPG and portal */
712 	iscsit_global.global_default_tpg = iscsit_tpg_createdefault();
713 	if (iscsit_global.global_default_tpg == NULL) {
714 		retval = IDM_STATUS_FAIL;
715 		goto tear_down_and_return;
716 	}
717 
718 	/* initialize isns client */
719 	(void) iscsit_isns_init(hostinfo);
720 	did_iscsit_isns_init = B_TRUE;
721 
722 	/* Register port provider */
723 	pp = stmf_alloc(STMF_STRUCT_PORT_PROVIDER, 0, 0);
724 	if (pp == NULL) {
725 		retval = IDM_STATUS_FAIL;
726 		goto tear_down_and_return;
727 	}
728 
729 	pp->pp_portif_rev = PORTIF_REV_1;
730 	pp->pp_instance = 0;
731 	pp->pp_name = ISCSIT_MODNAME;
732 	pp->pp_cb = iscsit_pp_cb;
733 
734 	iscsit_global.global_pp = pp;
735 
736 
737 	if (stmf_register_port_provider(pp) != STMF_SUCCESS) {
738 		retval = IDM_STATUS_FAIL;
739 		goto tear_down_and_return;
740 	}
741 
742 	iscsit_global.global_dispatch_taskq = taskq_create("iscsit_dispatch",
743 	    1, minclsyspri, 16, 16, TASKQ_PREPOPULATE);
744 
745 	/* Scan staged PDUs, meaningful in MC/S situations */
746 	iscsit_rxpdu_queue_monitor_start();
747 
748 	return (IDM_STATUS_SUCCESS);
749 
750 tear_down_and_return:
751 
752 	if (iscsit_global.global_dispatch_taskq) {
753 		taskq_destroy(iscsit_global.global_dispatch_taskq);
754 		iscsit_global.global_dispatch_taskq = NULL;
755 	}
756 
757 	if (did_iscsit_isns_init)
758 		iscsit_isns_fini();
759 
760 	if (iscsit_global.global_default_tpg) {
761 		iscsit_tpg_destroydefault(iscsit_global.global_default_tpg);
762 		iscsit_global.global_default_tpg = NULL;
763 	}
764 
765 	if (iscsit_global.global_pp)
766 		iscsit_global.global_pp = NULL;
767 
768 	if (pp)
769 		stmf_free(pp);
770 
771 	if (iscsit_status_pdu_cache) {
772 		kmem_cache_destroy(iscsit_status_pdu_cache);
773 		iscsit_status_pdu_cache = NULL;
774 	}
775 
776 	if (iscsit_global.global_dbuf_store) {
777 		stmf_free(iscsit_global.global_dbuf_store);
778 		iscsit_global.global_dbuf_store = NULL;
779 	}
780 
781 	if (iscsit_global.global_tsih_pool) {
782 		vmem_destroy(iscsit_global.global_tsih_pool);
783 		iscsit_global.global_tsih_pool = NULL;
784 	}
785 
786 	avl_destroy(&iscsit_global.global_ini_list);
787 	avl_destroy(&iscsit_global.global_tpg_list);
788 	list_destroy(&iscsit_global.global_deleted_target_list);
789 	avl_destroy(&iscsit_global.global_target_list);
790 	avl_destroy(&iscsit_global.global_discovery_sessions);
791 
792 	idm_refcnt_destroy(&iscsit_global.global_refcnt);
793 
794 	return (retval);
795 }
796 
797 /*
798  * iscsit_disable_svc
799  *
800  * clean up all existing connections and deregister targets from STMF
801  */
802 static void
803 iscsit_disable_svc(void)
804 {
805 	iscsit_sess_t	*sess;
806 
807 	ASSERT(iscsit_global.global_svc_state == ISE_DISABLING);
808 
809 	iscsit_rxpdu_queue_monitor_stop();
810 
811 	/* tear down discovery sessions */
812 	for (sess = avl_first(&iscsit_global.global_discovery_sessions);
813 	    sess != NULL;
814 	    sess = AVL_NEXT(&iscsit_global.global_discovery_sessions, sess))
815 		iscsit_sess_close(sess);
816 
817 	/*
818 	 * Passing NULL to iscsit_config_merge tells it to go to an empty
819 	 * config.
820 	 */
821 	(void) iscsit_config_merge(NULL);
822 
823 	/*
824 	 * Wait until there are no more global references
825 	 */
826 	idm_refcnt_wait_ref(&iscsit_global.global_refcnt);
827 	idm_refcnt_destroy(&iscsit_global.global_refcnt);
828 
829 	/*
830 	 * Default TPG must be destroyed after global_refcnt is 0.
831 	 */
832 	iscsit_tpg_destroydefault(iscsit_global.global_default_tpg);
833 
834 	avl_destroy(&iscsit_global.global_discovery_sessions);
835 	list_destroy(&iscsit_global.global_deleted_target_list);
836 	avl_destroy(&iscsit_global.global_target_list);
837 	avl_destroy(&iscsit_global.global_tpg_list);
838 	avl_destroy(&iscsit_global.global_ini_list);
839 
840 	taskq_destroy(iscsit_global.global_dispatch_taskq);
841 
842 	iscsit_isns_fini();
843 
844 	stmf_free(iscsit_global.global_dbuf_store);
845 	iscsit_global.global_dbuf_store = NULL;
846 
847 	(void) stmf_deregister_port_provider(iscsit_global.global_pp);
848 	stmf_free(iscsit_global.global_pp);
849 	iscsit_global.global_pp = NULL;
850 
851 	kmem_cache_destroy(iscsit_status_pdu_cache);
852 	iscsit_status_pdu_cache = NULL;
853 
854 	vmem_destroy(iscsit_global.global_tsih_pool);
855 	iscsit_global.global_tsih_pool = NULL;
856 }
857 
858 void
859 iscsit_global_hold()
860 {
861 	/*
862 	 * To take out a global hold, we must either own the global
863 	 * state mutex or we must be running inside of an ioctl that
864 	 * has set the global state to ISE_BUSY, ISE_DISABLING, or
865 	 * ISE_ENABLING.  We don't track the "owner" for these flags,
866 	 * so just checking if they are set is enough for now.
867 	 */
868 	ASSERT((iscsit_global.global_svc_state == ISE_ENABLING) ||
869 	    (iscsit_global.global_svc_state == ISE_DISABLING) ||
870 	    (iscsit_global.global_svc_state == ISE_BUSY) ||
871 	    MUTEX_HELD(&iscsit_global.global_state_mutex));
872 
873 	idm_refcnt_hold(&iscsit_global.global_refcnt);
874 }
875 
876 void
877 iscsit_global_rele()
878 {
879 	idm_refcnt_rele(&iscsit_global.global_refcnt);
880 }
881 
882 void
883 iscsit_global_wait_ref()
884 {
885 	idm_refcnt_wait_ref(&iscsit_global.global_refcnt);
886 }
887 
888 /*
889  * IDM callbacks
890  */
891 
892 /*ARGSUSED*/
893 void
894 iscsit_rx_pdu(idm_conn_t *ic, idm_pdu_t *rx_pdu)
895 {
896 	iscsit_conn_t *ict = ic->ic_handle;
897 	switch (IDM_PDU_OPCODE(rx_pdu)) {
898 	case ISCSI_OP_SCSI_CMD:
899 		ASSERT(0); /* Shouldn't happen */
900 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
901 		break;
902 	case ISCSI_OP_SNACK_CMD:
903 		/*
904 		 * We'll need to handle this when we support ERL1/2.  For
905 		 * now we treat it as a protocol error.
906 		 */
907 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
908 		idm_conn_event(ic, CE_TRANSPORT_FAIL, NULL);
909 		break;
910 	case ISCSI_OP_SCSI_TASK_MGT_MSG:
911 		if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
912 			iscsit_set_cmdsn(ict, rx_pdu);
913 			iscsit_op_scsi_task_mgmt(ict, rx_pdu);
914 		}
915 		break;
916 	case ISCSI_OP_NOOP_OUT:
917 	case ISCSI_OP_LOGIN_CMD:
918 	case ISCSI_OP_TEXT_CMD:
919 	case ISCSI_OP_LOGOUT_CMD:
920 		/*
921 		 * If/when we switch to userland processing these PDU's
922 		 * will be handled by iscsitd.
923 		 */
924 		iscsit_deferred_dispatch(rx_pdu);
925 		break;
926 	default:
927 		/* Protocol error */
928 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
929 		idm_conn_event(ic, CE_TRANSPORT_FAIL, NULL);
930 		break;
931 	}
932 }
933 
934 /*ARGSUSED*/
935 void
936 iscsit_rx_pdu_error(idm_conn_t *ic, idm_pdu_t *rx_pdu, idm_status_t status)
937 {
938 	idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
939 }
940 
941 void
942 iscsit_task_aborted(idm_task_t *idt, idm_status_t status)
943 {
944 	iscsit_task_t *itask = idt->idt_private;
945 
946 	switch (status) {
947 	case IDM_STATUS_SUSPENDED:
948 		break;
949 	case IDM_STATUS_ABORTED:
950 		mutex_enter(&itask->it_mutex);
951 		itask->it_aborted = B_TRUE;
952 		/*
953 		 * We rely on the fact that STMF tracks outstanding
954 		 * buffer transfers and will free all of our buffers
955 		 * before freeing the task so we don't need to
956 		 * explicitly free the buffers from iscsit/idm
957 		 */
958 		if (itask->it_stmf_abort) {
959 			mutex_exit(&itask->it_mutex);
960 			/*
961 			 * Task is no longer active
962 			 */
963 			iscsit_task_done(itask);
964 
965 			/*
966 			 * STMF has already asked for this task to be aborted
967 			 *
968 			 * STMF specification is wrong... says to return
969 			 * STMF_ABORTED, the code actually looks for
970 			 * STMF_ABORT_SUCCESS.
971 			 */
972 			stmf_task_lport_aborted(itask->it_stmf_task,
973 			    STMF_ABORT_SUCCESS, STMF_IOF_LPORT_DONE);
974 			return;
975 		} else {
976 			mutex_exit(&itask->it_mutex);
977 			/*
978 			 * Tell STMF to stop processing the task.
979 			 */
980 			stmf_abort(STMF_QUEUE_TASK_ABORT, itask->it_stmf_task,
981 			    STMF_ABORTED, NULL);
982 			return;
983 		}
984 		/*NOTREACHED*/
985 	default:
986 		ASSERT(0);
987 	}
988 }
989 
990 /*ARGSUSED*/
991 idm_status_t
992 iscsit_client_notify(idm_conn_t *ic, idm_client_notify_t icn,
993     uintptr_t data)
994 {
995 	idm_status_t rc = IDM_STATUS_SUCCESS;
996 
997 	/*
998 	 * IDM client notifications will never occur at interrupt level
999 	 * since they are generated from the connection state machine which
1000 	 * running on taskq threads.
1001 	 *
1002 	 */
1003 	switch (icn) {
1004 	case CN_CONNECT_ACCEPT:
1005 		rc = iscsit_conn_accept(ic); /* No data */
1006 		break;
1007 	case CN_FFP_ENABLED:
1008 		rc = iscsit_ffp_enabled(ic); /* No data */
1009 		break;
1010 	case CN_FFP_DISABLED:
1011 		/*
1012 		 * Data indicates whether this was the result of an
1013 		 * explicit logout request.
1014 		 */
1015 		rc = iscsit_ffp_disabled(ic, (idm_ffp_disable_t)data);
1016 		break;
1017 	case CN_CONNECT_LOST:
1018 		rc = iscsit_conn_lost(ic);
1019 		break;
1020 	case CN_CONNECT_DESTROY:
1021 		rc = iscsit_conn_destroy(ic);
1022 		break;
1023 	case CN_LOGIN_FAIL:
1024 		/*
1025 		 * Force the login state machine to completion
1026 		 */
1027 		rc = iscsit_login_fail(ic);
1028 		break;
1029 	default:
1030 		rc = IDM_STATUS_REJECT;
1031 		break;
1032 	}
1033 
1034 	return (rc);
1035 }
1036 
1037 /*
1038  * iscsit_update_statsn is invoked for all the PDUs which have the StatSN
1039  * field in the header. The StatSN is incremented if the IDM_PDU_ADVANCE_STATSN
1040  * flag is set in the pdu flags field. The StatSN is connection-wide and is
1041  * protected by the mutex ict_statsn_mutex. For Data-In PDUs, if the flag
1042  * IDM_TASK_PHASECOLLAPSE_REQ is set, the status (phase-collapse) is also filled
1043  */
1044 void
1045 iscsit_update_statsn(idm_task_t *idm_task, idm_pdu_t *pdu)
1046 {
1047 	iscsi_scsi_rsp_hdr_t *rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
1048 	iscsit_conn_t *ict = (iscsit_conn_t *)pdu->isp_ic->ic_handle;
1049 	iscsit_task_t *itask = NULL;
1050 	scsi_task_t *task = NULL;
1051 
1052 	mutex_enter(&ict->ict_statsn_mutex);
1053 	rsp->statsn = htonl(ict->ict_statsn);
1054 	if (pdu->isp_flags & IDM_PDU_ADVANCE_STATSN)
1055 		ict->ict_statsn++;
1056 	mutex_exit(&ict->ict_statsn_mutex);
1057 
1058 	/*
1059 	 * The last SCSI Data PDU passed for a command may also contain the
1060 	 * status if the status indicates termination with no expections, i.e.
1061 	 * no sense data or response involved. If the command completes with
1062 	 * an error, then the response and sense data will be sent in a
1063 	 * separate iSCSI Response PDU.
1064 	 */
1065 	if ((idm_task) && (idm_task->idt_flags & IDM_TASK_PHASECOLLAPSE_REQ)) {
1066 		itask = idm_task->idt_private;
1067 		task = itask->it_stmf_task;
1068 
1069 		rsp->cmd_status = task->task_scsi_status;
1070 		rsp->flags	|= ISCSI_FLAG_DATA_STATUS;
1071 		if (task->task_status_ctrl & TASK_SCTRL_OVER) {
1072 			rsp->flags |= ISCSI_FLAG_CMD_OVERFLOW;
1073 		} else if (task->task_status_ctrl & TASK_SCTRL_UNDER) {
1074 			rsp->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
1075 		}
1076 		rsp->residual_count = htonl(task->task_resid);
1077 
1078 		/*
1079 		 * Removing the task from the session task list
1080 		 * just before the status is sent in the last
1081 		 * Data PDU transfer
1082 		 */
1083 		iscsit_task_done(itask);
1084 	}
1085 }
1086 
1087 void
1088 iscsit_build_hdr(idm_task_t *idm_task, idm_pdu_t *pdu, uint8_t opcode)
1089 {
1090 	iscsit_task_t *itask = idm_task->idt_private;
1091 	iscsi_data_rsp_hdr_t *dh = (iscsi_data_rsp_hdr_t *)pdu->isp_hdr;
1092 
1093 	/*
1094 	 * We acquired iscsit_sess_t.ist_sn_mutex in iscsit_xfer_scsi_data
1095 	 */
1096 	ASSERT(MUTEX_HELD(&itask->it_ict->ict_sess->ist_sn_mutex));
1097 	/*
1098 	 * Lun is only required if the opcode == ISCSI_OP_SCSI_DATA_RSP
1099 	 * and the 'A' bit is to be set
1100 	 */
1101 	dh->opcode = opcode;
1102 	dh->itt = itask->it_itt;
1103 	dh->ttt = itask->it_ttt;
1104 
1105 	dh->expcmdsn = htonl(itask->it_ict->ict_sess->ist_expcmdsn);
1106 	dh->maxcmdsn = htonl(itask->it_ict->ict_sess->ist_maxcmdsn);
1107 
1108 	/*
1109 	 * IDM must set:
1110 	 *
1111 	 * data.flags and rtt.flags
1112 	 * data.dlength
1113 	 * data.datasn
1114 	 * data.offset
1115 	 * statsn, residual_count and cmd_status (for phase collapse)
1116 	 * rtt.rttsn
1117 	 * rtt.data_offset
1118 	 * rtt.data_length
1119 	 */
1120 }
1121 
1122 void
1123 iscsit_keepalive(idm_conn_t *ic)
1124 {
1125 	idm_pdu_t		*nop_in_pdu;
1126 	iscsi_nop_in_hdr_t	*nop_in;
1127 	iscsit_conn_t		*ict = ic->ic_handle;
1128 
1129 	/*
1130 	 * IDM noticed the connection has been idle for too long so it's
1131 	 * time to provoke some activity.  Build and transmit an iSCSI
1132 	 * nop-in PDU -- when the initiator responds it will be counted
1133 	 * as "activity" and keep the connection alive.
1134 	 *
1135 	 * We don't actually care about the response here at the iscsit level
1136 	 * so we will just throw it away without looking at it when it arrives.
1137 	 */
1138 	nop_in_pdu = idm_pdu_alloc(sizeof (*nop_in), 0);
1139 	idm_pdu_init(nop_in_pdu, ic, NULL, NULL);
1140 	nop_in = (iscsi_nop_in_hdr_t *)nop_in_pdu->isp_hdr;
1141 	bzero(nop_in, sizeof (*nop_in));
1142 	nop_in->opcode = ISCSI_OP_NOOP_IN;
1143 	nop_in->flags = ISCSI_FLAG_FINAL;
1144 	nop_in->itt = ISCSI_RSVD_TASK_TAG;
1145 	/*
1146 	 * When the target sends a NOP-In as a Ping, the target transfer tag
1147 	 * is set to a valid (not reserved) value and the initiator task tag
1148 	 * is set to ISCSI_RSVD_TASK_TAG (0xffffffff). In this case the StatSN
1149 	 * will always contain the next sequence number but the StatSN for the
1150 	 * connection is not advanced after this PDU is sent.
1151 	 */
1152 	nop_in_pdu->isp_flags |= IDM_PDU_SET_STATSN;
1153 	/*
1154 	 * This works because we don't currently allocate ttt's anywhere else
1155 	 * in iscsit so as long as we stay out of IDM's range we are safe.
1156 	 * If we need to allocate ttt's for other PDU's in the future this will
1157 	 * need to be improved.
1158 	 */
1159 	mutex_enter(&ict->ict_mutex);
1160 	nop_in->ttt = ict->ict_keepalive_ttt;
1161 	ict->ict_keepalive_ttt++;
1162 	if (ict->ict_keepalive_ttt == ISCSI_RSVD_TASK_TAG)
1163 		ict->ict_keepalive_ttt = IDM_TASKIDS_MAX;
1164 	mutex_exit(&ict->ict_mutex);
1165 
1166 	iscsit_pdu_tx(nop_in_pdu);
1167 }
1168 
1169 static idm_status_t
1170 iscsit_conn_accept(idm_conn_t *ic)
1171 {
1172 	iscsit_conn_t *ict;
1173 
1174 	/*
1175 	 * We need to get a global hold here to ensure that the service
1176 	 * doesn't get shutdown prior to establishing a session. This
1177 	 * gets released in iscsit_conn_destroy().
1178 	 */
1179 	mutex_enter(&iscsit_global.global_state_mutex);
1180 	if (iscsit_global.global_svc_state != ISE_ENABLED) {
1181 		mutex_exit(&iscsit_global.global_state_mutex);
1182 		return (IDM_STATUS_FAIL);
1183 	}
1184 	iscsit_global_hold();
1185 	mutex_exit(&iscsit_global.global_state_mutex);
1186 
1187 	/*
1188 	 * Allocate an associated iscsit structure to represent this
1189 	 * connection.  We shouldn't really create a session until we
1190 	 * get the first login PDU.
1191 	 */
1192 	ict = kmem_zalloc(sizeof (*ict), KM_SLEEP);
1193 
1194 	ict->ict_ic = ic;
1195 	ict->ict_statsn = 1;
1196 	ict->ict_keepalive_ttt = IDM_TASKIDS_MAX; /* Avoid IDM TT range */
1197 	ic->ic_handle = ict;
1198 	mutex_init(&ict->ict_mutex, NULL, MUTEX_DRIVER, NULL);
1199 	mutex_init(&ict->ict_statsn_mutex, NULL, MUTEX_DRIVER, NULL);
1200 	idm_refcnt_init(&ict->ict_refcnt, ict);
1201 
1202 	/*
1203 	 * Initialize login state machine
1204 	 */
1205 	if (iscsit_login_sm_init(ict) != IDM_STATUS_SUCCESS) {
1206 		iscsit_global_rele();
1207 		/*
1208 		 * Cleanup the ict after idm notifies us about this failure
1209 		 */
1210 		return (IDM_STATUS_FAIL);
1211 	}
1212 
1213 	return (IDM_STATUS_SUCCESS);
1214 }
1215 
1216 idm_status_t
1217 iscsit_conn_reinstate(iscsit_conn_t *reinstate_ict, iscsit_conn_t *new_ict)
1218 {
1219 	idm_status_t	result;
1220 
1221 	/*
1222 	 * Note in new connection state that this connection is
1223 	 * reinstating an existing connection.
1224 	 */
1225 	new_ict->ict_reinstating = B_TRUE;
1226 	new_ict->ict_reinstate_conn = reinstate_ict;
1227 	new_ict->ict_statsn = reinstate_ict->ict_statsn;
1228 
1229 	/*
1230 	 * Now generate connection state machine event to existing connection
1231 	 * so that it starts the cleanup process.
1232 	 */
1233 	result = idm_conn_reinstate_event(reinstate_ict->ict_ic,
1234 	    new_ict->ict_ic);
1235 
1236 	return (result);
1237 }
1238 
1239 void
1240 iscsit_conn_hold(iscsit_conn_t *ict)
1241 {
1242 	idm_refcnt_hold(&ict->ict_refcnt);
1243 }
1244 
1245 void
1246 iscsit_conn_rele(iscsit_conn_t *ict)
1247 {
1248 	idm_refcnt_rele(&ict->ict_refcnt);
1249 }
1250 
1251 void
1252 iscsit_conn_dispatch_hold(iscsit_conn_t *ict)
1253 {
1254 	idm_refcnt_hold(&ict->ict_dispatch_refcnt);
1255 }
1256 
1257 void
1258 iscsit_conn_dispatch_rele(iscsit_conn_t *ict)
1259 {
1260 	idm_refcnt_rele(&ict->ict_dispatch_refcnt);
1261 }
1262 
1263 static idm_status_t
1264 iscsit_login_fail(idm_conn_t *ic)
1265 {
1266 	iscsit_conn_t *ict = ic->ic_handle;
1267 
1268 	/* Generate login state machine event */
1269 	iscsit_login_sm_event(ict, ILE_LOGIN_CONN_ERROR, NULL);
1270 
1271 	return (IDM_STATUS_SUCCESS);
1272 }
1273 
1274 static idm_status_t
1275 iscsit_ffp_enabled(idm_conn_t *ic)
1276 {
1277 	iscsit_conn_t *ict = ic->ic_handle;
1278 
1279 	/* Generate session state machine event */
1280 	iscsit_sess_sm_event(ict->ict_sess, SE_CONN_LOGGED_IN, ict);
1281 
1282 	return (IDM_STATUS_SUCCESS);
1283 }
1284 
1285 static idm_status_t
1286 iscsit_ffp_disabled(idm_conn_t *ic, idm_ffp_disable_t disable_class)
1287 {
1288 	iscsit_conn_t *ict = ic->ic_handle;
1289 
1290 	/* Generate session state machine event */
1291 	switch (disable_class) {
1292 	case FD_CONN_FAIL:
1293 		iscsit_sess_sm_event(ict->ict_sess, SE_CONN_FFP_FAIL, ict);
1294 		break;
1295 	case FD_CONN_LOGOUT:
1296 		iscsit_sess_sm_event(ict->ict_sess, SE_CONN_FFP_DISABLE, ict);
1297 		break;
1298 	case FD_SESS_LOGOUT:
1299 		iscsit_sess_sm_event(ict->ict_sess, SE_SESSION_CLOSE, ict);
1300 		break;
1301 	default:
1302 		ASSERT(0);
1303 	}
1304 
1305 	return (IDM_STATUS_SUCCESS);
1306 }
1307 
1308 static idm_status_t
1309 iscsit_conn_lost(idm_conn_t *ic)
1310 {
1311 	iscsit_conn_t	*ict	= ic->ic_handle;
1312 	iscsit_sess_t	*ist	= ict->ict_sess;
1313 	iscsit_cbuf_t	*cbuf;
1314 	idm_pdu_t	*rx_pdu;
1315 	int i;
1316 
1317 	mutex_enter(&ict->ict_mutex);
1318 	ict->ict_lost = B_TRUE;
1319 	mutex_exit(&ict->ict_mutex);
1320 	/*
1321 	 * scrub the staging queue for all PDUs on this connection
1322 	 */
1323 	if (ist != NULL) {
1324 		mutex_enter(&ist->ist_sn_mutex);
1325 		for (cbuf = ist->ist_rxpdu_queue, i = 0;
1326 		    ((cbuf->cb_num_elems > 0) && (i < ISCSIT_RXPDU_QUEUE_LEN));
1327 		    i++) {
1328 			if (((rx_pdu = cbuf->cb_buffer[i]) != NULL) &&
1329 			    (rx_pdu->isp_ic == ic)) {
1330 				/* conn is lost, drop the pdu */
1331 				DTRACE_PROBE3(scrubbing__staging__queue,
1332 				    iscsit_sess_t *, ist, idm_conn_t *, ic,
1333 				    idm_pdu_t *, rx_pdu);
1334 				idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
1335 				cbuf->cb_buffer[i] = NULL;
1336 				cbuf->cb_num_elems--;
1337 				iscsit_conn_dispatch_rele(ict);
1338 			}
1339 		}
1340 		mutex_exit(&ist->ist_sn_mutex);
1341 	}
1342 	/*
1343 	 * Make sure there aren't any PDU's transitioning from the receive
1344 	 * handler to the dispatch taskq.
1345 	 */
1346 	idm_refcnt_wait_ref(&ict->ict_dispatch_refcnt);
1347 
1348 	return (IDM_STATUS_SUCCESS);
1349 }
1350 
1351 static idm_status_t
1352 iscsit_conn_destroy(idm_conn_t *ic)
1353 {
1354 	iscsit_conn_t *ict = ic->ic_handle;
1355 
1356 	mutex_enter(&ict->ict_mutex);
1357 	ict->ict_destroyed = B_TRUE;
1358 	mutex_exit(&ict->ict_mutex);
1359 
1360 	/* Generate session state machine event */
1361 	if (ict->ict_sess != NULL) {
1362 		/*
1363 		 * Session state machine will call iscsit_conn_destroy_done()
1364 		 * when it has removed references to this connection.
1365 		 */
1366 		iscsit_sess_sm_event(ict->ict_sess, SE_CONN_FAIL, ict);
1367 	}
1368 
1369 	ict->ict_ic = NULL;
1370 
1371 	idm_refcnt_wait_ref(&ict->ict_refcnt);
1372 
1373 	/* Reap the login state machine */
1374 	iscsit_login_sm_fini(ict);
1375 
1376 	/* Clean up any text command remnants */
1377 	iscsit_text_cmd_fini(ict);
1378 
1379 	mutex_destroy(&ict->ict_mutex);
1380 	idm_refcnt_destroy(&ict->ict_refcnt);
1381 	kmem_free(ict, sizeof (*ict));
1382 
1383 	iscsit_global_rele();
1384 
1385 	return (IDM_STATUS_SUCCESS);
1386 }
1387 
1388 /*
1389  * STMF-related functions
1390  *
1391  * iSCSI to STMF mapping
1392  *
1393  * Session == ?
1394  * Connection == bound to local port but not itself a local port
1395  * Target
1396  * Target portal (group?) == local port (really but we're not going to do this)
1397  *	iscsit needs to map connections to local ports (whatever we decide
1398  * 	they are)
1399  * Target == ?
1400  */
1401 
1402 /*ARGSUSED*/
1403 static stmf_data_buf_t *
1404 iscsit_dbuf_alloc(scsi_task_t *task, uint32_t size, uint32_t *pminsize,
1405     uint32_t flags)
1406 {
1407 	iscsit_task_t *itask = task->task_port_private;
1408 	idm_buf_t *idm_buffer;
1409 	iscsit_buf_t	*ibuf;
1410 	stmf_data_buf_t *result;
1411 	uint32_t	bsize;
1412 
1413 	/*
1414 	 * If the requested size is larger than MaxBurstLength and the
1415 	 * given pminsize is also larger than MaxBurstLength, then the
1416 	 * allocation fails (dbuf = NULL) and pminsize is modified to
1417 	 * be equal to MaxBurstLength. stmf/sbd then should re-invoke
1418 	 * this function with the corrected values for transfer.
1419 	 */
1420 	ASSERT(pminsize);
1421 	if (size <= itask->it_ict->ict_op.op_max_burst_length) {
1422 		bsize = size;
1423 	} else if (*pminsize <= itask->it_ict->ict_op.op_max_burst_length) {
1424 		bsize = itask->it_ict->ict_op.op_max_burst_length;
1425 	} else {
1426 		*pminsize = itask->it_ict->ict_op.op_max_burst_length;
1427 		return (NULL);
1428 	}
1429 
1430 	/* Alloc buffer */
1431 	idm_buffer = idm_buf_alloc(itask->it_ict->ict_ic, NULL, bsize);
1432 	if (idm_buffer != NULL) {
1433 		result = stmf_alloc(STMF_STRUCT_DATA_BUF,
1434 		    sizeof (iscsit_buf_t), 0);
1435 		if (result != NULL) {
1436 			/* Fill in stmf_data_buf_t */
1437 			ibuf = result->db_port_private;
1438 			ibuf->ibuf_idm_buf = idm_buffer;
1439 			ibuf->ibuf_stmf_buf = result;
1440 			ibuf->ibuf_is_immed = B_FALSE;
1441 			result->db_flags = DB_DONT_CACHE;
1442 			result->db_buf_size = bsize;
1443 			result->db_data_size = bsize;
1444 			result->db_sglist_length = 1;
1445 			result->db_sglist[0].seg_addr = idm_buffer->idb_buf;
1446 			result->db_sglist[0].seg_length =
1447 			    idm_buffer->idb_buflen;
1448 			return (result);
1449 		}
1450 
1451 		/* Couldn't get the stmf_data_buf_t so free the buffer */
1452 		idm_buf_free(idm_buffer);
1453 	}
1454 
1455 	return (NULL);
1456 }
1457 
1458 /*ARGSUSED*/
1459 static void
1460 iscsit_dbuf_free(stmf_dbuf_store_t *ds, stmf_data_buf_t *dbuf)
1461 {
1462 	iscsit_buf_t *ibuf = dbuf->db_port_private;
1463 
1464 	if (ibuf->ibuf_is_immed) {
1465 		/*
1466 		 * The iscsit_buf_t structure itself will be freed with its
1467 		 * associated task.  Here we just need to free the PDU that
1468 		 * held the immediate data.
1469 		 */
1470 		idm_pdu_complete(ibuf->ibuf_immed_data_pdu, IDM_STATUS_SUCCESS);
1471 		ibuf->ibuf_immed_data_pdu = 0;
1472 	} else {
1473 		idm_buf_free(ibuf->ibuf_idm_buf);
1474 		stmf_free(dbuf);
1475 	}
1476 }
1477 
1478 /*ARGSUSED*/
1479 stmf_status_t
1480 iscsit_xfer_scsi_data(scsi_task_t *task, stmf_data_buf_t *dbuf,
1481     uint32_t ioflags)
1482 {
1483 	iscsit_task_t *iscsit_task = task->task_port_private;
1484 	iscsit_sess_t *ict_sess = iscsit_task->it_ict->ict_sess;
1485 	iscsit_buf_t *ibuf = dbuf->db_port_private;
1486 	int idm_rc;
1487 
1488 	/*
1489 	 * If we are aborting then we can ignore this request
1490 	 */
1491 	if (iscsit_task->it_stmf_abort) {
1492 		return (STMF_SUCCESS);
1493 	}
1494 
1495 	/*
1496 	 * If it's not immediate data then start the transfer
1497 	 */
1498 	ASSERT(ibuf->ibuf_is_immed == B_FALSE);
1499 	if (dbuf->db_flags & DB_DIRECTION_TO_RPORT) {
1500 		/*
1501 		 * The DB_SEND_STATUS_GOOD flag in the STMF data buffer allows
1502 		 * the port provider to phase-collapse, i.e. send the status
1503 		 * along with the final data PDU for the command. The port
1504 		 * provider passes this request to the transport layer by
1505 		 * setting a flag IDM_TASK_PHASECOLLAPSE_REQ in the task.
1506 		 */
1507 		if (dbuf->db_flags & DB_SEND_STATUS_GOOD)
1508 			iscsit_task->it_idm_task->idt_flags |=
1509 			    IDM_TASK_PHASECOLLAPSE_REQ;
1510 		/*
1511 		 * IDM will call iscsit_build_hdr so lock now to serialize
1512 		 * access to the SN values.  We need to lock here to enforce
1513 		 * lock ordering
1514 		 */
1515 		mutex_enter(&ict_sess->ist_sn_mutex);
1516 		idm_rc = idm_buf_tx_to_ini(iscsit_task->it_idm_task,
1517 		    ibuf->ibuf_idm_buf, dbuf->db_relative_offset,
1518 		    dbuf->db_data_size, &iscsit_buf_xfer_cb, dbuf);
1519 		mutex_exit(&ict_sess->ist_sn_mutex);
1520 
1521 		return (iscsit_idm_to_stmf(idm_rc));
1522 	} else if (dbuf->db_flags & DB_DIRECTION_FROM_RPORT) {
1523 		/* Grab the SN lock (see comment above) */
1524 		mutex_enter(&ict_sess->ist_sn_mutex);
1525 		idm_rc = idm_buf_rx_from_ini(iscsit_task->it_idm_task,
1526 		    ibuf->ibuf_idm_buf, dbuf->db_relative_offset,
1527 		    dbuf->db_data_size, &iscsit_buf_xfer_cb, dbuf);
1528 		mutex_exit(&ict_sess->ist_sn_mutex);
1529 
1530 		return (iscsit_idm_to_stmf(idm_rc));
1531 	}
1532 
1533 	/* What are we supposed to do if there is no direction? */
1534 	return (STMF_INVALID_ARG);
1535 }
1536 
1537 static void
1538 iscsit_buf_xfer_cb(idm_buf_t *idb, idm_status_t status)
1539 {
1540 	iscsit_task_t *itask = idb->idb_task_binding->idt_private;
1541 	stmf_data_buf_t *dbuf = idb->idb_cb_arg;
1542 
1543 	dbuf->db_xfer_status = iscsit_idm_to_stmf(status);
1544 
1545 	/*
1546 	 * If the task has been aborted then we don't need to call STMF
1547 	 */
1548 	if (itask->it_stmf_abort) {
1549 		return;
1550 	}
1551 
1552 	/*
1553 	 * For ISCSI over TCP (not iSER), the last SCSI Data PDU passed
1554 	 * for a successful command contains the status as requested by
1555 	 * by COMSTAR (via the DB_SEND_STATUS_GOOD flag). But the iSER
1556 	 * transport does not support phase-collapse. So pretend we are
1557 	 * COMSTAR and send the status in a separate PDU now.
1558 	 */
1559 	if (idb->idb_task_binding->idt_flags & IDM_TASK_PHASECOLLAPSE_SUCCESS) {
1560 		/*
1561 		 * Mark task complete and notify COMSTAR
1562 		 * that the status has been sent.
1563 		 */
1564 		itask->it_idm_task->idt_state = TASK_COMPLETE;
1565 		stmf_send_status_done(itask->it_stmf_task,
1566 		    iscsit_idm_to_stmf(status), STMF_IOF_LPORT_DONE);
1567 	} else if ((dbuf->db_flags & DB_SEND_STATUS_GOOD) &&
1568 	    status == IDM_STATUS_SUCCESS) {
1569 
1570 		/*
1571 		 * The iscsi target port provider - for iSER, emulates the
1572 		 * DB_SEND_STATUS_GOOD optimization if requested by STMF;
1573 		 * it sends the status in a separate PDU after the data
1574 		 * transfer. In this case the port provider should first
1575 		 * call stmf_data_xfer_done() to mark the transfer complete
1576 		 * and then send the status. Although STMF will free the
1577 		 * buffer at the time the task is freed, even if the transfer
1578 		 * is not marked complete, this behavior makes statistics
1579 		 * gathering and task state tracking more difficult than it
1580 		 * needs to be.
1581 		 */
1582 		stmf_data_xfer_done(itask->it_stmf_task, dbuf, 0);
1583 		if (iscsit_send_scsi_status(itask->it_stmf_task, 0)
1584 		    != STMF_SUCCESS) {
1585 			stmf_send_status_done(itask->it_stmf_task,
1586 			    STMF_FAILURE, STMF_IOF_LPORT_DONE);
1587 		}
1588 	} else {
1589 		stmf_data_xfer_done(itask->it_stmf_task, dbuf, 0);
1590 		/* don't touch dbuf after stmf_data_xfer_done */
1591 	}
1592 }
1593 
1594 
1595 /*ARGSUSED*/
1596 stmf_status_t
1597 iscsit_send_scsi_status(scsi_task_t *task, uint32_t ioflags)
1598 {
1599 	iscsit_task_t *itask = task->task_port_private;
1600 	iscsi_scsi_rsp_hdr_t *rsp;
1601 	idm_pdu_t *pdu;
1602 	int resp_datalen;
1603 
1604 	/*
1605 	 * If this task is aborted then we don't need to respond.
1606 	 */
1607 	if (itask->it_stmf_abort) {
1608 		return (STMF_SUCCESS);
1609 	}
1610 
1611 	/*
1612 	 * If this is a task management status, handle it elsewhere.
1613 	 */
1614 	if (task->task_mgmt_function != TM_NONE) {
1615 		/*
1616 		 * Don't wait for the PDU completion to tell STMF
1617 		 * the task is done -- it doesn't really matter and
1618 		 * it makes life complicated if STMF later asks us to
1619 		 * abort the request and we don't know whether the
1620 		 * status has been sent or not.
1621 		 */
1622 		itask->it_tm_responded = B_TRUE;
1623 		iscsit_send_task_mgmt_resp(itask->it_tm_pdu,
1624 		    (task->task_completion_status == STMF_SUCCESS) ?
1625 		    SCSI_TCP_TM_RESP_COMPLETE : SCSI_TCP_TM_RESP_FUNC_NOT_SUPP);
1626 		stmf_send_status_done(task, STMF_SUCCESS,
1627 		    STMF_IOF_LPORT_DONE);
1628 		return (STMF_SUCCESS);
1629 	}
1630 
1631 	/*
1632 	 * Remove the task from the session task list
1633 	 */
1634 	iscsit_task_done(itask);
1635 
1636 	/*
1637 	 * Send status
1638 	 */
1639 	mutex_enter(&itask->it_idm_task->idt_mutex);
1640 	if ((itask->it_idm_task->idt_state == TASK_ACTIVE) &&
1641 	    (task->task_completion_status == STMF_SUCCESS) &&
1642 	    (task->task_sense_length == 0) &&
1643 	    (task->task_resid == 0)) {
1644 		itask->it_idm_task->idt_state = TASK_COMPLETE;
1645 		/* PDU callback releases task hold */
1646 		idm_task_hold(itask->it_idm_task);
1647 		mutex_exit(&itask->it_idm_task->idt_mutex);
1648 		/*
1649 		 * Fast path.  Cached status PDU's are already
1650 		 * initialized.  We just need to fill in
1651 		 * connection and task information. StatSN is
1652 		 * incremented by 1 for every status sent a
1653 		 * connection.
1654 		 */
1655 		pdu = kmem_cache_alloc(iscsit_status_pdu_cache, KM_SLEEP);
1656 		pdu->isp_ic = itask->it_ict->ict_ic;
1657 		pdu->isp_private = itask;
1658 		pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
1659 
1660 		rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
1661 		rsp->itt = itask->it_itt;
1662 		/*
1663 		 * ExpDataSN is the number of R2T and Data-In (read)
1664 		 * PDUs the target has sent for the SCSI command.
1665 		 *
1666 		 * Since there is no support for bidirectional transfer
1667 		 * yet, either idt_exp_datasn or idt_exp_rttsn, but not
1668 		 * both is valid at any time
1669 		 */
1670 		rsp->expdatasn = (itask->it_idm_task->idt_exp_datasn != 0) ?
1671 		    htonl(itask->it_idm_task->idt_exp_datasn):
1672 		    htonl(itask->it_idm_task->idt_exp_rttsn);
1673 		rsp->cmd_status = task->task_scsi_status;
1674 		iscsit_pdu_tx(pdu);
1675 		return (STMF_SUCCESS);
1676 	} else {
1677 		if (itask->it_idm_task->idt_state != TASK_ACTIVE) {
1678 			mutex_exit(&itask->it_idm_task->idt_mutex);
1679 			return (STMF_FAILURE);
1680 		}
1681 		itask->it_idm_task->idt_state = TASK_COMPLETE;
1682 		/* PDU callback releases task hold */
1683 		idm_task_hold(itask->it_idm_task);
1684 		mutex_exit(&itask->it_idm_task->idt_mutex);
1685 
1686 		resp_datalen = (task->task_sense_length == 0) ? 0 :
1687 		    (task->task_sense_length + sizeof (uint16_t));
1688 
1689 		pdu = idm_pdu_alloc(sizeof (iscsi_hdr_t), resp_datalen);
1690 		idm_pdu_init(pdu, itask->it_ict->ict_ic, itask,
1691 		    iscsit_send_status_done);
1692 		pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
1693 
1694 		rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
1695 		bzero(rsp, sizeof (*rsp));
1696 		rsp->opcode = ISCSI_OP_SCSI_RSP;
1697 
1698 		rsp->flags = ISCSI_FLAG_FINAL;
1699 		if (task->task_status_ctrl & TASK_SCTRL_OVER) {
1700 			rsp->flags |= ISCSI_FLAG_CMD_OVERFLOW;
1701 		} else if (task->task_status_ctrl & TASK_SCTRL_UNDER) {
1702 			rsp->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
1703 		}
1704 
1705 		rsp->bi_residual_count = 0;
1706 		rsp->residual_count = htonl(task->task_resid);
1707 		rsp->itt = itask->it_itt;
1708 		rsp->response = ISCSI_STATUS_CMD_COMPLETED;
1709 		rsp->expdatasn = (itask->it_idm_task->idt_exp_datasn != 0) ?
1710 		    htonl(itask->it_idm_task->idt_exp_datasn):
1711 		    htonl(itask->it_idm_task->idt_exp_rttsn);
1712 		rsp->cmd_status = task->task_scsi_status;
1713 		if (task->task_sense_length != 0) {
1714 			/*
1715 			 * Add a byte to provide the sense length in
1716 			 * the response
1717 			 */
1718 			*(uint16_t *)((void *)pdu->isp_data) =
1719 			    htons(task->task_sense_length);
1720 			bcopy(task->task_sense_data,
1721 			    (uint8_t *)pdu->isp_data +
1722 			    sizeof (uint16_t),
1723 			    task->task_sense_length);
1724 			hton24(rsp->dlength, resp_datalen);
1725 		}
1726 
1727 		DTRACE_PROBE5(iscsi__scsi__response,
1728 		    iscsit_conn_t *, itask->it_ict,
1729 		    uint8_t, rsp->response,
1730 		    uint8_t, rsp->cmd_status,
1731 		    idm_pdu_t *, pdu,
1732 		    scsi_task_t *, task);
1733 
1734 		iscsit_pdu_tx(pdu);
1735 
1736 		return (STMF_SUCCESS);
1737 	}
1738 }
1739 
1740 /*ARGSUSED*/
1741 static void
1742 iscsit_send_good_status_done(idm_pdu_t *pdu, idm_status_t status)
1743 {
1744 	iscsit_task_t	*itask;
1745 	boolean_t	aborted;
1746 
1747 	itask = pdu->isp_private;
1748 	aborted = itask->it_stmf_abort;
1749 
1750 	/*
1751 	 * After releasing the hold the task may be freed at any time so
1752 	 * don't touch it.
1753 	 */
1754 	idm_task_rele(itask->it_idm_task);
1755 	if (!aborted) {
1756 		stmf_send_status_done(itask->it_stmf_task,
1757 		    iscsit_idm_to_stmf(pdu->isp_status), STMF_IOF_LPORT_DONE);
1758 	}
1759 	kmem_cache_free(iscsit_status_pdu_cache, pdu);
1760 }
1761 
1762 /*ARGSUSED*/
1763 static void
1764 iscsit_send_status_done(idm_pdu_t *pdu, idm_status_t status)
1765 {
1766 	iscsit_task_t	 *itask;
1767 	boolean_t	aborted;
1768 
1769 	itask = pdu->isp_private;
1770 	aborted = itask->it_stmf_abort;
1771 
1772 	/*
1773 	 * After releasing the hold the task may be freed at any time so
1774 	 * don't touch it.
1775 	 */
1776 	idm_task_rele(itask->it_idm_task);
1777 	if (!aborted) {
1778 		stmf_send_status_done(itask->it_stmf_task,
1779 		    iscsit_idm_to_stmf(pdu->isp_status), STMF_IOF_LPORT_DONE);
1780 	}
1781 	idm_pdu_free(pdu);
1782 }
1783 
1784 
1785 void
1786 iscsit_lport_task_free(scsi_task_t *task)
1787 {
1788 	iscsit_task_t *itask = task->task_port_private;
1789 
1790 	/* We only call idm_task_start for regular tasks, not task management */
1791 	if (task->task_mgmt_function == TM_NONE) {
1792 		idm_task_done(itask->it_idm_task);
1793 		iscsit_task_free(itask);
1794 		return;
1795 	} else {
1796 		iscsit_tm_task_free(itask);
1797 	}
1798 }
1799 
1800 /*ARGSUSED*/
1801 stmf_status_t
1802 iscsit_abort(stmf_local_port_t *lport, int abort_cmd, void *arg, uint32_t flags)
1803 {
1804 	scsi_task_t	*st = (scsi_task_t *)arg;
1805 	iscsit_task_t	*iscsit_task;
1806 	idm_task_t	*idt;
1807 
1808 	/*
1809 	 * If this is a task management request then there's really not much to
1810 	 * do.
1811 	 */
1812 	if (st->task_mgmt_function != TM_NONE) {
1813 		return (STMF_ABORT_SUCCESS);
1814 	}
1815 
1816 	/*
1817 	 * Regular task, start cleaning up
1818 	 */
1819 	iscsit_task = st->task_port_private;
1820 	idt = iscsit_task->it_idm_task;
1821 	mutex_enter(&iscsit_task->it_mutex);
1822 	iscsit_task->it_stmf_abort = B_TRUE;
1823 	if (iscsit_task->it_aborted) {
1824 		mutex_exit(&iscsit_task->it_mutex);
1825 		/*
1826 		 * Task is no longer active
1827 		 */
1828 		iscsit_task_done(iscsit_task);
1829 
1830 		/*
1831 		 * STMF specification is wrong... says to return
1832 		 * STMF_ABORTED, the code actually looks for
1833 		 * STMF_ABORT_SUCCESS.
1834 		 */
1835 		return (STMF_ABORT_SUCCESS);
1836 	} else {
1837 		mutex_exit(&iscsit_task->it_mutex);
1838 		/*
1839 		 * Call IDM to abort the task.  Due to a variety of
1840 		 * circumstances the task may already be in the process of
1841 		 * aborting.
1842 		 * We'll let IDM worry about rationalizing all that except
1843 		 * for one particular instance.  If the state of the task
1844 		 * is TASK_COMPLETE, we need to indicate to the framework
1845 		 * that we are in fact done.  This typically happens with
1846 		 * framework-initiated task management type requests
1847 		 * (e.g. abort task).
1848 		 */
1849 		if (idt->idt_state == TASK_COMPLETE) {
1850 			idm_refcnt_wait_ref(&idt->idt_refcnt);
1851 			return (STMF_ABORT_SUCCESS);
1852 		} else {
1853 			idm_task_abort(idt->idt_ic, idt, AT_TASK_MGMT_ABORT);
1854 			return (STMF_SUCCESS);
1855 		}
1856 	}
1857 
1858 	/*NOTREACHED*/
1859 }
1860 
1861 /*ARGSUSED*/
1862 void
1863 iscsit_ctl(stmf_local_port_t *lport, int cmd, void *arg)
1864 {
1865 	iscsit_tgt_t		*iscsit_tgt;
1866 
1867 	ASSERT((cmd == STMF_CMD_LPORT_ONLINE) ||
1868 	    (cmd == STMF_ACK_LPORT_ONLINE_COMPLETE) ||
1869 	    (cmd == STMF_CMD_LPORT_OFFLINE) ||
1870 	    (cmd == STMF_ACK_LPORT_OFFLINE_COMPLETE));
1871 
1872 	iscsit_tgt = (iscsit_tgt_t *)lport->lport_port_private;
1873 
1874 	switch (cmd) {
1875 	case STMF_CMD_LPORT_ONLINE:
1876 		iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_ONLINE_REQ);
1877 		break;
1878 	case STMF_CMD_LPORT_OFFLINE:
1879 		iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_OFFLINE_REQ);
1880 		break;
1881 	case STMF_ACK_LPORT_ONLINE_COMPLETE:
1882 		iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_ONLINE_COMPLETE_ACK);
1883 		break;
1884 	case STMF_ACK_LPORT_OFFLINE_COMPLETE:
1885 		iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_OFFLINE_COMPLETE_ACK);
1886 		break;
1887 
1888 	default:
1889 		break;
1890 	}
1891 }
1892 
1893 static stmf_status_t
1894 iscsit_idm_to_stmf(idm_status_t idmrc)
1895 {
1896 	switch (idmrc) {
1897 	case IDM_STATUS_SUCCESS:
1898 		return (STMF_SUCCESS);
1899 	default:
1900 		return (STMF_FAILURE);
1901 	}
1902 	/*NOTREACHED*/
1903 }
1904 
1905 void
1906 iscsit_op_scsi_cmd(idm_conn_t *ic, idm_pdu_t *rx_pdu)
1907 {
1908 	iscsit_conn_t		*ict = ic->ic_handle;
1909 
1910 	if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
1911 		iscsit_post_scsi_cmd(ic, rx_pdu);
1912 	}
1913 	iscsit_process_pdu_in_queue(ict->ict_sess);
1914 }
1915 
1916 /*
1917  * ISCSI protocol
1918  */
1919 
1920 void
1921 iscsit_post_scsi_cmd(idm_conn_t *ic, idm_pdu_t *rx_pdu)
1922 {
1923 	iscsit_conn_t		*ict;
1924 	iscsit_task_t		*itask;
1925 	scsi_task_t		*task;
1926 	iscsit_buf_t		*ibuf;
1927 	iscsi_scsi_cmd_hdr_t	*iscsi_scsi =
1928 	    (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
1929 	iscsi_addl_hdr_t	*ahs_hdr;
1930 	uint16_t		addl_cdb_len = 0;
1931 
1932 	ict = ic->ic_handle;
1933 
1934 	itask = iscsit_task_alloc(ict);
1935 	if (itask == NULL) {
1936 		/* Finish processing request */
1937 		iscsit_set_cmdsn(ict, rx_pdu);
1938 
1939 		iscsit_send_direct_scsi_resp(ict, rx_pdu,
1940 		    ISCSI_STATUS_CMD_COMPLETED, STATUS_BUSY);
1941 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
1942 		return;
1943 	}
1944 
1945 	/*
1946 	 * Note CmdSN and ITT in task.  IDM will have already validated this
1947 	 * request against the connection state so we don't need to check
1948 	 * that (the connection may have changed state in the meantime but
1949 	 * we will catch that when we try to send a response)
1950 	 */
1951 	itask->it_cmdsn = ntohl(iscsi_scsi->cmdsn);
1952 	itask->it_itt = iscsi_scsi->itt;
1953 
1954 	/*
1955 	 * Check for extended CDB AHS
1956 	 */
1957 	if (iscsi_scsi->hlength > 0) {
1958 		ahs_hdr = (iscsi_addl_hdr_t *)iscsi_scsi;
1959 		addl_cdb_len = ((ahs_hdr->ahs_hlen_hi << 8) |
1960 		    ahs_hdr->ahs_hlen_lo) - 1; /* Adjust for reserved byte */
1961 		if (((addl_cdb_len + 4) / sizeof (uint32_t)) >
1962 		    iscsi_scsi->hlength) {
1963 			/* Mangled header info, drop it */
1964 			idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
1965 			return;
1966 		}
1967 	}
1968 
1969 	ict = rx_pdu->isp_ic->ic_handle; /* IDM client private */
1970 
1971 	/*
1972 	 * Add task to session list.  This function will also check to
1973 	 * ensure that the task does not already exist.
1974 	 */
1975 	if (iscsit_task_start(itask) != IDM_STATUS_SUCCESS) {
1976 		/*
1977 		 * Task exists, free all resources and reject.  Don't
1978 		 * update expcmdsn in this case because RFC 3720 says
1979 		 * "The CmdSN of the rejected command PDU (if it is a
1980 		 * non-immediate command) MUST NOT be considered received
1981 		 * by the target (i.e., a command sequence gap must be
1982 		 * assumed for the CmdSN), even though the CmdSN of the
1983 		 * rejected command PDU may be reliably ascertained.  Upon
1984 		 * receiving the Reject, the initiator MUST plug the CmdSN
1985 		 * gap in order to continue to use the session.  The gap
1986 		 * may be plugged either by transmitting a command PDU
1987 		 * with the same CmdSN, or by aborting the task (see section
1988 		 * 6.9 on how an abort may plug a CmdSN gap)." (Section 6.3)
1989 		 */
1990 		iscsit_task_free(itask);
1991 		iscsit_send_reject(ict, rx_pdu, ISCSI_REJECT_TASK_IN_PROGRESS);
1992 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
1993 		return;
1994 	}
1995 
1996 	/* Update sequence numbers */
1997 	iscsit_set_cmdsn(ict, rx_pdu);
1998 
1999 	/*
2000 	 * Allocate STMF task
2001 	 */
2002 	itask->it_stmf_task = stmf_task_alloc(
2003 	    itask->it_ict->ict_sess->ist_lport,
2004 	    itask->it_ict->ict_sess->ist_stmf_sess, iscsi_scsi->lun,
2005 	    16 + addl_cdb_len, 0);
2006 	if (itask->it_stmf_task == NULL) {
2007 		/*
2008 		 * Either stmf really couldn't get memory for a task or,
2009 		 * more likely, the LU is currently in reset.  Either way
2010 		 * we have no choice but to fail the request.
2011 		 */
2012 		iscsit_task_done(itask);
2013 		iscsit_task_free(itask);
2014 		iscsit_send_direct_scsi_resp(ict, rx_pdu,
2015 		    ISCSI_STATUS_CMD_COMPLETED, STATUS_BUSY);
2016 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2017 		return;
2018 	}
2019 
2020 	task = itask->it_stmf_task;
2021 	task->task_port_private = itask;
2022 
2023 	bcopy(iscsi_scsi->lun, task->task_lun_no, sizeof (task->task_lun_no));
2024 
2025 	/*
2026 	 * iSCSI and Comstar use the same values.  Should we rely on this
2027 	 * or translate them bit-wise?
2028 	 */
2029 
2030 	task->task_flags =
2031 	    (((iscsi_scsi->flags & ISCSI_FLAG_CMD_READ) ? TF_READ_DATA : 0) |
2032 	    ((iscsi_scsi->flags & ISCSI_FLAG_CMD_WRITE) ? TF_WRITE_DATA : 0) |
2033 	    ((rx_pdu->isp_datalen == 0) ? 0 : TF_INITIAL_BURST));
2034 
2035 	switch (iscsi_scsi->flags & ISCSI_FLAG_CMD_ATTR_MASK) {
2036 	case ISCSI_ATTR_UNTAGGED:
2037 		break;
2038 	case ISCSI_ATTR_SIMPLE:
2039 		task->task_additional_flags |= TF_ATTR_SIMPLE_QUEUE;
2040 		break;
2041 	case ISCSI_ATTR_ORDERED:
2042 		task->task_additional_flags |= TF_ATTR_ORDERED_QUEUE;
2043 		break;
2044 	case ISCSI_ATTR_HEAD_OF_QUEUE:
2045 		task->task_additional_flags |= TF_ATTR_HEAD_OF_QUEUE;
2046 		break;
2047 	case ISCSI_ATTR_ACA:
2048 		task->task_additional_flags |= TF_ATTR_ACA;
2049 		break;
2050 	default:
2051 		/* Protocol error but just take it, treat as untagged */
2052 		break;
2053 	}
2054 
2055 
2056 	task->task_additional_flags = 0;
2057 	task->task_priority = 0;
2058 	task->task_mgmt_function = TM_NONE;
2059 
2060 	/*
2061 	 * This "task_max_nbufs" doesn't map well to BIDI.  We probably need
2062 	 * parameter for each direction.  "MaxOutstandingR2T" may very well
2063 	 * be set to one which could prevent us from doing simultaneous
2064 	 * transfers in each direction.
2065 	 */
2066 	task->task_max_nbufs = (iscsi_scsi->flags & ISCSI_FLAG_CMD_WRITE) ?
2067 	    ict->ict_op.op_max_outstanding_r2t : STMF_BUFS_MAX;
2068 	task->task_cmd_seq_no = ntohl(iscsi_scsi->itt);
2069 	task->task_expected_xfer_length = ntohl(iscsi_scsi->data_length);
2070 
2071 	/* Copy CDB */
2072 	bcopy(iscsi_scsi->scb, task->task_cdb, 16);
2073 	if (addl_cdb_len > 0) {
2074 		bcopy(ahs_hdr->ahs_extscb, task->task_cdb + 16, addl_cdb_len);
2075 	}
2076 
2077 	DTRACE_ISCSI_3(scsi__command, idm_conn_t *, ic,
2078 	    iscsi_scsi_cmd_hdr_t *, (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr,
2079 	    scsi_task_t *, task);
2080 
2081 	/*
2082 	 * Copy the transport header into the task handle from the PDU
2083 	 * handle. The transport header describes this task's remote tagged
2084 	 * buffer.
2085 	 */
2086 	if (rx_pdu->isp_transport_hdrlen != 0) {
2087 		bcopy(rx_pdu->isp_transport_hdr,
2088 		    itask->it_idm_task->idt_transport_hdr,
2089 		    rx_pdu->isp_transport_hdrlen);
2090 	}
2091 
2092 	/*
2093 	 * Tell IDM about our new active task
2094 	 */
2095 	idm_task_start(itask->it_idm_task, (uintptr_t)itask->it_itt);
2096 
2097 	/*
2098 	 * If we have any immediate data then setup the immediate buffer
2099 	 * context that comes with the task
2100 	 */
2101 	if (rx_pdu->isp_datalen) {
2102 		ibuf = itask->it_immed_data;
2103 		ibuf->ibuf_immed_data_pdu = rx_pdu;
2104 		ibuf->ibuf_stmf_buf->db_data_size = rx_pdu->isp_datalen;
2105 		ibuf->ibuf_stmf_buf->db_buf_size = rx_pdu->isp_datalen;
2106 		ibuf->ibuf_stmf_buf->db_relative_offset = 0;
2107 		ibuf->ibuf_stmf_buf->db_sglist[0].seg_length =
2108 		    rx_pdu->isp_datalen;
2109 		ibuf->ibuf_stmf_buf->db_sglist[0].seg_addr = rx_pdu->isp_data;
2110 
2111 		DTRACE_ISCSI_8(xfer__start, idm_conn_t *, ic,
2112 		    uintptr_t, ibuf->ibuf_stmf_buf->db_sglist[0].seg_addr,
2113 		    uint32_t, ibuf->ibuf_stmf_buf->db_relative_offset,
2114 		    uint64_t, 0, uint32_t, 0, uint32_t, 0, /* no raddr */
2115 		    uint32_t, rx_pdu->isp_datalen, int, XFER_BUF_TX_TO_INI);
2116 
2117 		/*
2118 		 * For immediate data transfer, there is no callback from
2119 		 * stmf to indicate that the initial burst of data is
2120 		 * transferred successfully. In some cases, the task can
2121 		 * get freed before execution returns from stmf_post_task.
2122 		 * Although this xfer-start/done probe accurately tracks
2123 		 * the size of the transfer, it does only provide a best
2124 		 * effort on the timing of the transfer.
2125 		 */
2126 		DTRACE_ISCSI_8(xfer__done, idm_conn_t *, ic,
2127 		    uintptr_t, ibuf->ibuf_stmf_buf->db_sglist[0].seg_addr,
2128 		    uint32_t, ibuf->ibuf_stmf_buf->db_relative_offset,
2129 		    uint64_t, 0, uint32_t, 0, uint32_t, 0, /* no raddr */
2130 		    uint32_t, rx_pdu->isp_datalen, int, XFER_BUF_TX_TO_INI);
2131 		stmf_post_task(task, ibuf->ibuf_stmf_buf);
2132 	} else {
2133 
2134 		stmf_post_task(task, NULL);
2135 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2136 	}
2137 }
2138 
2139 /*ARGSUSED*/
2140 void
2141 iscsit_deferred_dispatch(idm_pdu_t *rx_pdu)
2142 {
2143 	iscsit_conn_t *ict = rx_pdu->isp_ic->ic_handle;
2144 
2145 	/*
2146 	 * If the connection has been lost then ignore new PDU's
2147 	 */
2148 	mutex_enter(&ict->ict_mutex);
2149 	if (ict->ict_lost) {
2150 		mutex_exit(&ict->ict_mutex);
2151 		idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
2152 		return;
2153 	}
2154 
2155 	/*
2156 	 * Grab a hold on the connection to prevent it from going away
2157 	 * between now and when the taskq function is called.
2158 	 */
2159 	iscsit_conn_dispatch_hold(ict);
2160 	mutex_exit(&ict->ict_mutex);
2161 
2162 	if (taskq_dispatch(iscsit_global.global_dispatch_taskq,
2163 	    iscsit_deferred, rx_pdu, DDI_NOSLEEP) == NULL) {
2164 		/*
2165 		 * In the unlikely scenario that we couldn't get the resources
2166 		 * to dispatch the PDU then just drop it.
2167 		 */
2168 		idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
2169 		idm_conn_event(ict->ict_ic, CE_TRANSPORT_FAIL, NULL);
2170 		iscsit_conn_dispatch_rele(ict);
2171 	}
2172 }
2173 
2174 static void
2175 iscsit_deferred(void *rx_pdu_void)
2176 {
2177 	idm_pdu_t		*rx_pdu = rx_pdu_void;
2178 	idm_conn_t		*ic = rx_pdu->isp_ic;
2179 	iscsit_conn_t		*ict = ic->ic_handle;
2180 
2181 	/*
2182 	 * NOP and Task Management Commands can be marked for immediate
2183 	 * delivery. Commands marked as 'Immediate' are to be considered
2184 	 * for execution as soon as they arrive on the target. So these
2185 	 * should not be checked for sequence order and put in a queue.
2186 	 * The CmdSN is not advanced for Immediate Commands.
2187 	 */
2188 	switch (IDM_PDU_OPCODE(rx_pdu)) {
2189 	case ISCSI_OP_NOOP_OUT:
2190 		if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
2191 			iscsit_set_cmdsn(ict, rx_pdu);
2192 			iscsit_pdu_op_noop(ict, rx_pdu);
2193 		}
2194 		break;
2195 	case ISCSI_OP_LOGIN_CMD:
2196 		iscsit_pdu_op_login_cmd(ict, rx_pdu);
2197 		iscsit_conn_dispatch_rele(ict);
2198 		return;
2199 	case ISCSI_OP_TEXT_CMD:
2200 		if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
2201 			iscsit_set_cmdsn(ict, rx_pdu);
2202 			iscsit_pdu_op_text_cmd(ict, rx_pdu);
2203 		}
2204 		break;
2205 	case ISCSI_OP_LOGOUT_CMD:
2206 		if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
2207 			iscsit_set_cmdsn(ict, rx_pdu);
2208 			iscsit_pdu_op_logout_cmd(ict, rx_pdu);
2209 		}
2210 		break;
2211 	default:
2212 		/* Protocol error.  IDM should have caught this */
2213 		idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
2214 		ASSERT(0);
2215 		break;
2216 	}
2217 	/*
2218 	 * Check if there are other PDUs in the session staging queue
2219 	 * waiting to be posted to SCSI layer.
2220 	 */
2221 	iscsit_process_pdu_in_queue(ict->ict_sess);
2222 
2223 	iscsit_conn_dispatch_rele(ict);
2224 }
2225 
2226 static void
2227 iscsit_send_direct_scsi_resp(iscsit_conn_t *ict, idm_pdu_t *rx_pdu,
2228     uint8_t response, uint8_t cmd_status)
2229 {
2230 	idm_pdu_t			*rsp_pdu;
2231 	idm_conn_t			*ic;
2232 	iscsi_scsi_rsp_hdr_t		*resp;
2233 	iscsi_scsi_cmd_hdr_t		*req =
2234 	    (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
2235 
2236 	ic = ict->ict_ic;
2237 
2238 	rsp_pdu = idm_pdu_alloc(sizeof (iscsi_scsi_rsp_hdr_t), 0);
2239 	idm_pdu_init(rsp_pdu, ic, NULL, NULL);
2240 	/*
2241 	 * StatSN is incremented by 1 for every response sent on
2242 	 * a connection except for responses sent as a result of
2243 	 * a retry or SNACK
2244 	 */
2245 	rsp_pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2246 
2247 	resp = (iscsi_scsi_rsp_hdr_t *)rsp_pdu->isp_hdr;
2248 
2249 	resp->opcode = ISCSI_OP_SCSI_RSP;
2250 	resp->flags = ISCSI_FLAG_FINAL;
2251 	resp->response = response;
2252 	resp->cmd_status = cmd_status;
2253 	resp->itt = req->itt;
2254 	if ((response == ISCSI_STATUS_CMD_COMPLETED) &&
2255 	    (req->data_length != 0) &&
2256 	    ((req->flags & ISCSI_FLAG_CMD_READ) ||
2257 	    (req->flags & ISCSI_FLAG_CMD_WRITE))) {
2258 		resp->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
2259 		resp->residual_count = req->data_length;
2260 	}
2261 
2262 	DTRACE_PROBE4(iscsi__scsi__direct__response,
2263 	    iscsit_conn_t *, ict,
2264 	    uint8_t, resp->response,
2265 	    uint8_t, resp->cmd_status,
2266 	    idm_pdu_t *, rsp_pdu);
2267 
2268 	iscsit_pdu_tx(rsp_pdu);
2269 }
2270 
2271 void
2272 iscsit_send_task_mgmt_resp(idm_pdu_t *tm_resp_pdu, uint8_t tm_status)
2273 {
2274 	iscsi_scsi_task_mgt_rsp_hdr_t	*tm_resp;
2275 
2276 	/*
2277 	 * The target must take note of the last-sent StatSN.
2278 	 * The StatSN is to be incremented after sending a
2279 	 * task management response. Digest recovery can only
2280 	 * work if StatSN is incremented.
2281 	 */
2282 	tm_resp_pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2283 	tm_resp = (iscsi_scsi_task_mgt_rsp_hdr_t *)tm_resp_pdu->isp_hdr;
2284 	tm_resp->response = tm_status;
2285 
2286 	DTRACE_PROBE3(iscsi__scsi__tm__response,
2287 	    iscsit_conn_t *, tm_resp_pdu->isp_ic->ic_handle,
2288 	    uint8_t, tm_resp->response,
2289 	    idm_pdu_t *, tm_resp_pdu);
2290 	iscsit_pdu_tx(tm_resp_pdu);
2291 }
2292 
2293 void
2294 iscsit_op_scsi_task_mgmt(iscsit_conn_t *ict, idm_pdu_t *rx_pdu)
2295 {
2296 	idm_pdu_t			*tm_resp_pdu;
2297 	iscsit_task_t			*itask;
2298 	iscsit_task_t			*tm_itask;
2299 	scsi_task_t			*task;
2300 	iscsi_scsi_task_mgt_hdr_t 	*iscsi_tm =
2301 	    (iscsi_scsi_task_mgt_hdr_t *)rx_pdu->isp_hdr;
2302 	iscsi_scsi_task_mgt_rsp_hdr_t 	*iscsi_tm_rsp =
2303 	    (iscsi_scsi_task_mgt_rsp_hdr_t *)rx_pdu->isp_hdr;
2304 	uint32_t			rtt, cmdsn, refcmdsn;
2305 	uint8_t				tm_func;
2306 
2307 	/*
2308 	 * Setup response PDU (response field will get filled in later)
2309 	 */
2310 	tm_resp_pdu = idm_pdu_alloc(sizeof (iscsi_scsi_task_mgt_rsp_hdr_t), 0);
2311 	if (tm_resp_pdu == NULL) {
2312 		/* Can't respond, just drop it */
2313 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2314 		return;
2315 	}
2316 	idm_pdu_init(tm_resp_pdu, ict->ict_ic, NULL, NULL);
2317 	iscsi_tm_rsp = (iscsi_scsi_task_mgt_rsp_hdr_t *)tm_resp_pdu->isp_hdr;
2318 	bzero(iscsi_tm_rsp, sizeof (iscsi_scsi_task_mgt_rsp_hdr_t));
2319 	iscsi_tm_rsp->opcode = ISCSI_OP_SCSI_TASK_MGT_RSP;
2320 	iscsi_tm_rsp->flags = ISCSI_FLAG_FINAL;
2321 	iscsi_tm_rsp->itt = rx_pdu->isp_hdr->itt;
2322 
2323 	/*
2324 	 * Figure out what we're being asked to do.
2325 	 */
2326 	DTRACE_PROBE4(iscsi__scsi__tm__request,
2327 	    iscsit_conn_t *, ict,
2328 	    uint8_t, (iscsi_tm->function & ISCSI_FLAG_TASK_MGMT_FUNCTION_MASK),
2329 	    uint32_t, iscsi_tm->rtt,
2330 	    idm_pdu_t *, rx_pdu);
2331 	switch (iscsi_tm->function & ISCSI_FLAG_TASK_MGMT_FUNCTION_MASK) {
2332 	case ISCSI_TM_FUNC_ABORT_TASK:
2333 		/*
2334 		 * STMF doesn't currently support the "abort task" task
2335 		 * management command although it does support aborting
2336 		 * an individual task.  We'll get STMF to abort the task
2337 		 * for us but handle the details of the task management
2338 		 * command ourselves.
2339 		 *
2340 		 * Find the task associated with the referenced task tag.
2341 		 */
2342 		rtt = iscsi_tm->rtt;
2343 		itask = (iscsit_task_t *)idm_task_find_by_handle(ict->ict_ic,
2344 		    (uintptr_t)rtt);
2345 
2346 		if (itask == NULL) {
2347 			cmdsn = ntohl(iscsi_tm->cmdsn);
2348 			refcmdsn = ntohl(iscsi_tm->refcmdsn);
2349 
2350 			/*
2351 			 * Task was not found. But the SCSI command could be
2352 			 * on the rxpdu wait queue. If RefCmdSN is within
2353 			 * the CmdSN window and less than CmdSN of the TM
2354 			 * function, return "Function Complete". Otherwise,
2355 			 * return "Task Does Not Exist".
2356 			 */
2357 
2358 			if (iscsit_cmdsn_in_window(ict, refcmdsn) &&
2359 			    iscsit_sna_lt(refcmdsn, cmdsn)) {
2360 				mutex_enter(&ict->ict_sess->ist_sn_mutex);
2361 				(void) iscsit_remove_pdu_from_queue(
2362 				    ict->ict_sess, refcmdsn);
2363 				iscsit_conn_dispatch_rele(ict);
2364 				mutex_exit(&ict->ict_sess->ist_sn_mutex);
2365 				iscsit_send_task_mgmt_resp(tm_resp_pdu,
2366 				    SCSI_TCP_TM_RESP_COMPLETE);
2367 			} else {
2368 				iscsit_send_task_mgmt_resp(tm_resp_pdu,
2369 				    SCSI_TCP_TM_RESP_NO_TASK);
2370 			}
2371 		} else {
2372 
2373 			/*
2374 			 * Tell STMF to abort the task.  This will do no harm
2375 			 * if the task is already complete.
2376 			 */
2377 			stmf_abort(STMF_QUEUE_TASK_ABORT, itask->it_stmf_task,
2378 			    STMF_ABORTED, NULL);
2379 
2380 			/*
2381 			 * Make sure the task hasn't already completed
2382 			 */
2383 			mutex_enter(&itask->it_idm_task->idt_mutex);
2384 			if ((itask->it_idm_task->idt_state == TASK_COMPLETE) ||
2385 			    (itask->it_idm_task->idt_state == TASK_IDLE)) {
2386 				/*
2387 				 * Task is complete, return "Task Does Not
2388 				 * Exist"
2389 				 */
2390 				mutex_exit(&itask->it_idm_task->idt_mutex);
2391 				iscsit_send_task_mgmt_resp(tm_resp_pdu,
2392 				    SCSI_TCP_TM_RESP_NO_TASK);
2393 			} else {
2394 				/*
2395 				 * STMF is now aborting the task, return
2396 				 * "Function Complete"
2397 				 */
2398 				mutex_exit(&itask->it_idm_task->idt_mutex);
2399 				iscsit_send_task_mgmt_resp(tm_resp_pdu,
2400 				    SCSI_TCP_TM_RESP_COMPLETE);
2401 			}
2402 			idm_task_rele(itask->it_idm_task);
2403 		}
2404 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2405 		return;
2406 
2407 	case ISCSI_TM_FUNC_ABORT_TASK_SET:
2408 		tm_func = TM_ABORT_TASK_SET;
2409 		break;
2410 
2411 	case ISCSI_TM_FUNC_CLEAR_ACA:
2412 		tm_func = TM_CLEAR_ACA;
2413 		break;
2414 
2415 	case ISCSI_TM_FUNC_CLEAR_TASK_SET:
2416 		tm_func = TM_CLEAR_TASK_SET;
2417 		break;
2418 
2419 	case ISCSI_TM_FUNC_LOGICAL_UNIT_RESET:
2420 		tm_func = TM_LUN_RESET;
2421 		break;
2422 
2423 	case ISCSI_TM_FUNC_TARGET_WARM_RESET:
2424 		tm_func = TM_TARGET_WARM_RESET;
2425 		break;
2426 
2427 	case ISCSI_TM_FUNC_TARGET_COLD_RESET:
2428 		tm_func = TM_TARGET_COLD_RESET;
2429 		break;
2430 
2431 	case ISCSI_TM_FUNC_TASK_REASSIGN:
2432 		/*
2433 		 * We do not currently support allegiance reassignment.  When
2434 		 * we start supporting ERL1+, we will need to.
2435 		 */
2436 		iscsit_send_task_mgmt_resp(tm_resp_pdu,
2437 		    SCSI_TCP_TM_RESP_NO_ALLG_REASSN);
2438 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2439 		return;
2440 
2441 	default:
2442 		iscsit_send_task_mgmt_resp(tm_resp_pdu,
2443 		    SCSI_TCP_TM_RESP_REJECTED);
2444 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2445 		return;
2446 	}
2447 
2448 	tm_itask = iscsit_tm_task_alloc(ict);
2449 	if (tm_itask == NULL) {
2450 		iscsit_send_task_mgmt_resp(tm_resp_pdu,
2451 		    SCSI_TCP_TM_RESP_REJECTED);
2452 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2453 		return;
2454 	}
2455 
2456 
2457 	task = stmf_task_alloc(ict->ict_sess->ist_lport,
2458 	    ict->ict_sess->ist_stmf_sess, iscsi_tm->lun,
2459 	    0, STMF_TASK_EXT_NONE);
2460 	if (task == NULL) {
2461 		/*
2462 		 * If this happens, either the LU is in reset, couldn't
2463 		 * get memory, or some other condition in which we simply
2464 		 * can't complete this request.  It would be nice to return
2465 		 * an error code like "busy" but the closest we have is
2466 		 * "rejected".
2467 		 */
2468 		iscsit_send_task_mgmt_resp(tm_resp_pdu,
2469 		    SCSI_TCP_TM_RESP_REJECTED);
2470 		iscsit_tm_task_free(tm_itask);
2471 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2472 		return;
2473 	}
2474 
2475 	tm_itask->it_tm_pdu = tm_resp_pdu;
2476 	tm_itask->it_stmf_task = task;
2477 	task->task_port_private = tm_itask;
2478 	task->task_mgmt_function = tm_func;
2479 	task->task_additional_flags = TASK_AF_NO_EXPECTED_XFER_LENGTH;
2480 	task->task_priority = 0;
2481 	task->task_max_nbufs = STMF_BUFS_MAX;
2482 	task->task_cmd_seq_no = iscsi_tm->itt;
2483 	task->task_expected_xfer_length = 0;
2484 
2485 	stmf_post_task(task, NULL);
2486 	idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2487 }
2488 
2489 static void
2490 iscsit_pdu_op_noop(iscsit_conn_t *ict, idm_pdu_t *rx_pdu)
2491 {
2492 	iscsi_nop_out_hdr_t *out = (iscsi_nop_out_hdr_t *)rx_pdu->isp_hdr;
2493 	iscsi_nop_in_hdr_t *in;
2494 	int resp_datalen;
2495 	idm_pdu_t *resp;
2496 
2497 	/* Ignore the response from initiator */
2498 	if ((out->itt == ISCSI_RSVD_TASK_TAG) ||
2499 	    (out->ttt != ISCSI_RSVD_TASK_TAG)) {
2500 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2501 		return;
2502 	}
2503 
2504 	/* Allocate a PDU to respond */
2505 	resp_datalen = ntoh24(out->dlength);
2506 	resp = idm_pdu_alloc(sizeof (iscsi_hdr_t), resp_datalen);
2507 	idm_pdu_init(resp, ict->ict_ic, NULL, NULL);
2508 	if (resp_datalen > 0) {
2509 		bcopy(rx_pdu->isp_data, resp->isp_data, resp_datalen);
2510 	}
2511 
2512 	/*
2513 	 * When sending a NOP-In as a response to a NOP-Out from the initiator,
2514 	 * the target must respond with the same initiator task tag that was
2515 	 * provided in the NOP-Out request, the target transfer tag must be
2516 	 * ISCSI_RSVD_TASK_TAG (0xffffffff) and StatSN will contain the next
2517 	 * status sequence number. The StatSN for the connection is advanced
2518 	 * after this PDU is sent.
2519 	 */
2520 	in = (iscsi_nop_in_hdr_t *)resp->isp_hdr;
2521 	bzero(in, sizeof (*in));
2522 	in->opcode = ISCSI_OP_NOOP_IN;
2523 	in->flags = ISCSI_FLAG_FINAL;
2524 	bcopy(out->lun, in->lun, 8);
2525 	in->itt		= out->itt;
2526 	in->ttt		= ISCSI_RSVD_TASK_TAG;
2527 	hton24(in->dlength, resp_datalen);
2528 	resp->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2529 	/* Any other field in resp to be set? */
2530 	iscsit_pdu_tx(resp);
2531 	idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2532 }
2533 
2534 static void
2535 iscsit_pdu_op_login_cmd(iscsit_conn_t	*ict, idm_pdu_t *rx_pdu)
2536 {
2537 
2538 	/*
2539 	 * Submit PDU to login state machine.  State machine will free the
2540 	 * PDU.
2541 	 */
2542 	iscsit_login_sm_event(ict, ILE_LOGIN_RCV, rx_pdu);
2543 }
2544 
2545 void
2546 iscsit_pdu_op_logout_cmd(iscsit_conn_t	*ict, idm_pdu_t *rx_pdu)
2547 {
2548 	iscsi_logout_hdr_t 	*logout_req =
2549 	    (iscsi_logout_hdr_t *)rx_pdu->isp_hdr;
2550 	iscsi_logout_rsp_hdr_t	*logout_rsp;
2551 	idm_pdu_t *resp;
2552 
2553 	/* Allocate a PDU to respond */
2554 	resp = idm_pdu_alloc(sizeof (iscsi_hdr_t), 0);
2555 	idm_pdu_init(resp, ict->ict_ic, NULL, NULL);
2556 	/*
2557 	 * The StatSN is to be sent to the initiator,
2558 	 * it is not required to increment the number
2559 	 * as the connection is terminating.
2560 	 */
2561 	resp->isp_flags |= IDM_PDU_SET_STATSN;
2562 	/*
2563 	 * Logout results in the immediate termination of all tasks except
2564 	 * if the logout reason is ISCSI_LOGOUT_REASON_RECOVERY.  The
2565 	 * connection state machine will drive this task cleanup automatically
2566 	 * so we don't need to handle that here.
2567 	 */
2568 	logout_rsp = (iscsi_logout_rsp_hdr_t *)resp->isp_hdr;
2569 	bzero(logout_rsp, sizeof (*logout_rsp));
2570 	logout_rsp->opcode = ISCSI_OP_LOGOUT_RSP;
2571 	logout_rsp->flags = ISCSI_FLAG_FINAL;
2572 	logout_rsp->itt = logout_req->itt;
2573 	if ((logout_req->flags & ISCSI_FLAG_LOGOUT_REASON_MASK) >
2574 	    ISCSI_LOGOUT_REASON_RECOVERY) {
2575 		logout_rsp->response = ISCSI_LOGOUT_RECOVERY_UNSUPPORTED;
2576 	} else {
2577 		logout_rsp->response = ISCSI_LOGOUT_SUCCESS;
2578 	}
2579 
2580 	iscsit_pdu_tx(resp);
2581 	idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2582 }
2583 
2584 /*
2585  * Calculate the number of outstanding commands we can process
2586  */
2587 int
2588 iscsit_cmd_window()
2589 {
2590 	/*
2591 	 * Instead of using a pre-defined constant for the command window,
2592 	 * it should be made confiurable and dynamic. With MC/S, sequence
2593 	 * numbers will be used up at a much faster rate than with SC/S.
2594 	 */
2595 	return	(ISCSIT_MAX_WINDOW);
2596 }
2597 
2598 /*
2599  * Set local registers based on incoming PDU
2600  */
2601 void
2602 iscsit_set_cmdsn(iscsit_conn_t *ict, idm_pdu_t *rx_pdu)
2603 {
2604 	iscsit_sess_t *ist;
2605 	iscsi_scsi_cmd_hdr_t *req;
2606 
2607 	ist = ict->ict_sess;
2608 
2609 	req = (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
2610 	if (req->opcode & ISCSI_OP_IMMEDIATE) {
2611 		/* no cmdsn increment for immediate PDUs */
2612 		return;
2613 	}
2614 
2615 	/* Ensure that the ExpCmdSN advances in an orderly manner */
2616 	mutex_enter(&ist->ist_sn_mutex);
2617 	ist->ist_expcmdsn = ntohl(req->cmdsn) + 1;
2618 	ist->ist_maxcmdsn = ntohl(req->cmdsn) + iscsit_cmd_window();
2619 	mutex_exit(&ist->ist_sn_mutex);
2620 }
2621 
2622 /*
2623  * Wrapper funtion, calls iscsi_calc_rspsn and idm_pdu_tx
2624  */
2625 void
2626 iscsit_pdu_tx(idm_pdu_t *pdu)
2627 {
2628 	iscsit_conn_t *ict = pdu->isp_ic->ic_handle;
2629 	iscsi_scsi_rsp_hdr_t *rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
2630 	iscsit_sess_t *ist = ict->ict_sess;
2631 
2632 	/*
2633 	 * The command sequence numbers are session-wide and must stay
2634 	 * consistent across the transfer, so protect the cmdsn with a
2635 	 * mutex lock on the session. The status sequence number will
2636 	 * be updated just before the transport layer transmits the PDU.
2637 	 */
2638 
2639 	mutex_enter(&ict->ict_sess->ist_sn_mutex);
2640 	/* Set ExpCmdSN and MaxCmdSN */
2641 	rsp->maxcmdsn = htonl(ist->ist_maxcmdsn);
2642 	rsp->expcmdsn = htonl(ist->ist_expcmdsn);
2643 	idm_pdu_tx(pdu);
2644 	mutex_exit(&ict->ict_sess->ist_sn_mutex);
2645 }
2646 
2647 /*
2648  * Internal functions
2649  */
2650 
2651 void
2652 iscsit_send_async_event(iscsit_conn_t *ict, uint8_t event)
2653 {
2654 	idm_pdu_t		*abt;
2655 	iscsi_async_evt_hdr_t	*async_abt;
2656 
2657 	/*
2658 	 * Get a PDU to build the abort request.
2659 	 */
2660 	abt = idm_pdu_alloc(sizeof (iscsi_hdr_t), 0);
2661 	if (abt == NULL) {
2662 		idm_conn_event(ict->ict_ic, CE_TRANSPORT_FAIL, NULL);
2663 		return;
2664 	}
2665 
2666 	/*
2667 	 * A asynchronous message is sent by the target to request a logout.
2668 	 * The StatSN for the connection is advanced after the PDU is sent
2669 	 * to allow for initiator and target state synchronization.
2670 	 */
2671 	idm_pdu_init(abt, ict->ict_ic, NULL, NULL);
2672 	abt->isp_datalen = 0;
2673 	abt->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2674 
2675 	async_abt = (iscsi_async_evt_hdr_t *)abt->isp_hdr;
2676 	bzero(async_abt, sizeof (*async_abt));
2677 	async_abt->opcode = ISCSI_OP_ASYNC_EVENT;
2678 	async_abt->async_event = event;
2679 	async_abt->flags = ISCSI_FLAG_FINAL;
2680 	async_abt->rsvd4[0] = 0xff;
2681 	async_abt->rsvd4[1] = 0xff;
2682 	async_abt->rsvd4[2] = 0xff;
2683 	async_abt->rsvd4[3] = 0xff;
2684 
2685 	switch (event) {
2686 	case ISCSI_ASYNC_EVENT_REQUEST_LOGOUT:
2687 		async_abt->param3 = htons(IDM_LOGOUT_SECONDS);
2688 		break;
2689 	case ISCSI_ASYNC_EVENT_SCSI_EVENT:
2690 	case ISCSI_ASYNC_EVENT_DROPPING_CONNECTION:
2691 	case ISCSI_ASYNC_EVENT_DROPPING_ALL_CONNECTIONS:
2692 	case ISCSI_ASYNC_EVENT_PARAM_NEGOTIATION:
2693 	default:
2694 		ASSERT(0);
2695 	}
2696 
2697 	iscsit_pdu_tx(abt);
2698 }
2699 
2700 void
2701 iscsit_send_reject(iscsit_conn_t *ict, idm_pdu_t *rejected_pdu, uint8_t reason)
2702 {
2703 	idm_pdu_t		*reject_pdu;
2704 	iscsi_reject_rsp_hdr_t	*reject;
2705 
2706 	/*
2707 	 * Get a PDU to build the abort request.
2708 	 */
2709 	reject_pdu = idm_pdu_alloc(sizeof (iscsi_hdr_t),
2710 	    rejected_pdu->isp_hdrlen);
2711 	if (reject_pdu == NULL) {
2712 		idm_conn_event(ict->ict_ic, CE_TRANSPORT_FAIL, NULL);
2713 		return;
2714 	}
2715 	idm_pdu_init(reject_pdu, ict->ict_ic, NULL, NULL);
2716 	/* StatSN is advanced after a Reject PDU */
2717 	reject_pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2718 	reject_pdu->isp_datalen = rejected_pdu->isp_hdrlen;
2719 	bcopy(rejected_pdu->isp_hdr, reject_pdu->isp_data,
2720 	    rejected_pdu->isp_hdrlen);
2721 
2722 	reject = (iscsi_reject_rsp_hdr_t *)reject_pdu->isp_hdr;
2723 	bzero(reject, sizeof (*reject));
2724 	reject->opcode = ISCSI_OP_REJECT_MSG;
2725 	reject->reason = reason;
2726 	reject->flags = ISCSI_FLAG_FINAL;
2727 	hton24(reject->dlength, rejected_pdu->isp_hdrlen);
2728 	reject->must_be_ff[0] = 0xff;
2729 	reject->must_be_ff[1] = 0xff;
2730 	reject->must_be_ff[2] = 0xff;
2731 	reject->must_be_ff[3] = 0xff;
2732 
2733 	iscsit_pdu_tx(reject_pdu);
2734 }
2735 
2736 
2737 static iscsit_task_t *
2738 iscsit_task_alloc(iscsit_conn_t *ict)
2739 {
2740 	iscsit_task_t *itask;
2741 	iscsit_buf_t *immed_ibuf;
2742 
2743 	/*
2744 	 * Possible items to pre-alloc if we cache iscsit_task_t's:
2745 	 *
2746 	 * Status PDU w/ sense buffer
2747 	 * stmf_data_buf_t for immediate data
2748 	 */
2749 	itask = kmem_alloc(sizeof (iscsit_task_t) + sizeof (iscsit_buf_t) +
2750 	    sizeof (stmf_data_buf_t), KM_NOSLEEP);
2751 	if (itask != NULL) {
2752 		mutex_init(&itask->it_mutex, NULL, MUTEX_DRIVER, NULL);
2753 		itask->it_aborted = itask->it_stmf_abort =
2754 		    itask->it_tm_task = 0;
2755 
2756 		immed_ibuf = (iscsit_buf_t *)(itask + 1);
2757 		bzero(immed_ibuf, sizeof (*immed_ibuf));
2758 		immed_ibuf->ibuf_is_immed = B_TRUE;
2759 		immed_ibuf->ibuf_stmf_buf = (stmf_data_buf_t *)(immed_ibuf + 1);
2760 
2761 		bzero(immed_ibuf->ibuf_stmf_buf, sizeof (stmf_data_buf_t));
2762 		immed_ibuf->ibuf_stmf_buf->db_port_private = immed_ibuf;
2763 		immed_ibuf->ibuf_stmf_buf->db_sglist_length = 1;
2764 		immed_ibuf->ibuf_stmf_buf->db_flags = DB_DIRECTION_FROM_RPORT |
2765 		    DB_DONT_CACHE;
2766 		itask->it_immed_data = immed_ibuf;
2767 		itask->it_idm_task = idm_task_alloc(ict->ict_ic);
2768 		if (itask->it_idm_task != NULL) {
2769 			itask->it_idm_task->idt_private = itask;
2770 			itask->it_ict = ict;
2771 			itask->it_ttt = itask->it_idm_task->idt_tt;
2772 			return (itask);
2773 		} else {
2774 			kmem_free(itask, sizeof (iscsit_task_t) +
2775 			    sizeof (iscsit_buf_t) + sizeof (stmf_data_buf_t));
2776 		}
2777 	}
2778 
2779 	return (NULL);
2780 }
2781 
2782 static void
2783 iscsit_task_free(iscsit_task_t *itask)
2784 {
2785 	idm_task_free(itask->it_idm_task);
2786 	mutex_destroy(&itask->it_mutex);
2787 	kmem_free(itask, sizeof (iscsit_task_t) +
2788 	    sizeof (iscsit_buf_t) + sizeof (stmf_data_buf_t));
2789 }
2790 
2791 static iscsit_task_t *
2792 iscsit_tm_task_alloc(iscsit_conn_t *ict)
2793 {
2794 	iscsit_task_t *itask;
2795 
2796 	itask = kmem_zalloc(sizeof (iscsit_task_t), KM_NOSLEEP);
2797 	if (itask != NULL) {
2798 		idm_conn_hold(ict->ict_ic);
2799 		mutex_init(&itask->it_mutex, NULL, MUTEX_DRIVER, NULL);
2800 		itask->it_aborted = itask->it_stmf_abort =
2801 		    itask->it_tm_responded = 0;
2802 		itask->it_tm_pdu = NULL;
2803 		itask->it_tm_task = 1;
2804 		itask->it_ict = ict;
2805 	}
2806 
2807 	return (itask);
2808 }
2809 
2810 static void
2811 iscsit_tm_task_free(iscsit_task_t *itask)
2812 {
2813 	/*
2814 	 * If we responded then the call to idm_pdu_complete will free the
2815 	 * PDU.  Otherwise we got aborted before the TM function could
2816 	 * complete and we need to free the PDU explicitly.
2817 	 */
2818 	if (itask->it_tm_pdu != NULL && !itask->it_tm_responded)
2819 		idm_pdu_free(itask->it_tm_pdu);
2820 	idm_conn_rele(itask->it_ict->ict_ic);
2821 	mutex_destroy(&itask->it_mutex);
2822 	kmem_free(itask, sizeof (iscsit_task_t));
2823 }
2824 
2825 static idm_status_t
2826 iscsit_task_start(iscsit_task_t *itask)
2827 {
2828 	iscsit_sess_t *ist = itask->it_ict->ict_sess;
2829 	avl_index_t		where;
2830 
2831 	/*
2832 	 * Sanity check the ITT and ensure that this task does not already
2833 	 * exist.  If not then add the task to the session task list.
2834 	 */
2835 	mutex_enter(&ist->ist_mutex);
2836 	mutex_enter(&itask->it_mutex);
2837 	itask->it_active = 1;
2838 	if (avl_find(&ist->ist_task_list, itask, &where) == NULL) {
2839 		/* New task, add to AVL */
2840 		avl_insert(&ist->ist_task_list, itask, where);
2841 		mutex_exit(&itask->it_mutex);
2842 		mutex_exit(&ist->ist_mutex);
2843 		return (IDM_STATUS_SUCCESS);
2844 	}
2845 	mutex_exit(&itask->it_mutex);
2846 	mutex_exit(&ist->ist_mutex);
2847 
2848 	return (IDM_STATUS_REJECT);
2849 }
2850 
2851 static void
2852 iscsit_task_done(iscsit_task_t *itask)
2853 {
2854 	iscsit_sess_t *ist = itask->it_ict->ict_sess;
2855 
2856 	mutex_enter(&ist->ist_mutex);
2857 	mutex_enter(&itask->it_mutex);
2858 	if (itask->it_active) {
2859 		avl_remove(&ist->ist_task_list, itask);
2860 		itask->it_active = 0;
2861 	}
2862 	mutex_exit(&itask->it_mutex);
2863 	mutex_exit(&ist->ist_mutex);
2864 }
2865 
2866 /*
2867  * iscsit status PDU cache
2868  */
2869 
2870 /*ARGSUSED*/
2871 static int
2872 iscsit_status_pdu_constructor(void *pdu_void, void *arg, int flags)
2873 {
2874 	idm_pdu_t *pdu = pdu_void;
2875 	iscsi_scsi_rsp_hdr_t *rsp;
2876 
2877 	bzero(pdu, sizeof (idm_pdu_t));
2878 	pdu->isp_callback = iscsit_send_good_status_done;
2879 	pdu->isp_magic = IDM_PDU_MAGIC;
2880 	pdu->isp_hdr = (iscsi_hdr_t *)(pdu + 1); /* Ptr arithmetic */
2881 	pdu->isp_hdrlen = sizeof (iscsi_hdr_t);
2882 
2883 	/* Setup status response */
2884 	rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
2885 	bzero(rsp, sizeof (*rsp));
2886 	rsp->opcode = ISCSI_OP_SCSI_RSP;
2887 	rsp->flags = ISCSI_FLAG_FINAL;
2888 	rsp->response = ISCSI_STATUS_CMD_COMPLETED;
2889 
2890 	return (0);
2891 }
2892 
2893 /*
2894  * iscsit private data handler
2895  */
2896 
2897 /*ARGSUSED*/
2898 static void
2899 iscsit_pp_cb(struct stmf_port_provider *pp, int cmd, void *arg, uint32_t flags)
2900 {
2901 	it_config_t		*cfg;
2902 	nvlist_t		*nvl;
2903 	iscsit_service_enabled_t	old_state;
2904 
2905 	if ((cmd != STMF_PROVIDER_DATA_UPDATED) || (arg == NULL)) {
2906 		return;
2907 	}
2908 
2909 	nvl = (nvlist_t *)arg;
2910 
2911 	/* Translate nvlist */
2912 	if (it_nv_to_config(nvl, &cfg) != 0) {
2913 		cmn_err(CE_WARN, "Configuration is invalid");
2914 		return;
2915 	}
2916 
2917 	/* Check that no iSCSI ioctl is currently running */
2918 	mutex_enter(&iscsit_global.global_state_mutex);
2919 	old_state = iscsit_global.global_svc_state;
2920 	switch (iscsit_global.global_svc_state) {
2921 	case ISE_ENABLED:
2922 	case ISE_DISABLED:
2923 		iscsit_global.global_svc_state = ISE_BUSY;
2924 		break;
2925 	case ISE_ENABLING:
2926 		/*
2927 		 * It is OK for the iscsit_pp_cb to be called from inside of
2928 		 * an iSCSI ioctl only if we are currently executing inside
2929 		 * of stmf_register_port_provider.
2930 		 */
2931 		ASSERT((flags & STMF_PCB_PREG_COMPLETE) != 0);
2932 		break;
2933 	default:
2934 		cmn_err(CE_WARN, "iscsit_pp_cb called when global_svc_state"
2935 		    " is not ENABLED(0x%x) -- ignoring",
2936 		    iscsit_global.global_svc_state);
2937 		mutex_exit(&iscsit_global.global_state_mutex);
2938 		it_config_free_cmn(cfg);
2939 		return;
2940 	}
2941 	mutex_exit(&iscsit_global.global_state_mutex);
2942 
2943 	/* Update config */
2944 	(void) iscsit_config_merge(cfg);
2945 
2946 	it_config_free_cmn(cfg);
2947 
2948 	/* Restore old iSCSI driver global state */
2949 	mutex_enter(&iscsit_global.global_state_mutex);
2950 	ASSERT(iscsit_global.global_svc_state == ISE_BUSY ||
2951 	    iscsit_global.global_svc_state == ISE_ENABLING);
2952 	iscsit_global.global_svc_state = old_state;
2953 	mutex_exit(&iscsit_global.global_state_mutex);
2954 }
2955 
2956 
2957 static it_cfg_status_t
2958 iscsit_config_merge(it_config_t *in_cfg)
2959 {
2960 	it_cfg_status_t	status;
2961 	it_config_t	*cfg;
2962 	it_config_t	tmp_cfg;
2963 	list_t		tpg_del_list;
2964 
2965 	if (in_cfg) {
2966 		cfg = in_cfg;
2967 	} else {
2968 		/* Make empty config */
2969 		bzero(&tmp_cfg, sizeof (tmp_cfg));
2970 		cfg = &tmp_cfg;
2971 	}
2972 
2973 	list_create(&tpg_del_list,  sizeof (iscsit_tpg_t),
2974 	    offsetof(iscsit_tpg_t, tpg_delete_ln));
2975 
2976 	/*
2977 	 * Update targets, initiator contexts, target portal groups,
2978 	 * and iSNS client
2979 	 */
2980 	ISCSIT_GLOBAL_LOCK(RW_WRITER);
2981 	if (((status = iscsit_config_merge_tpg(cfg, &tpg_del_list))
2982 	    != 0) ||
2983 	    ((status = iscsit_config_merge_tgt(cfg)) != 0) ||
2984 	    ((status = iscsit_config_merge_ini(cfg)) != 0) ||
2985 	    ((status = isnst_config_merge(cfg)) != 0)) {
2986 		ISCSIT_GLOBAL_UNLOCK();
2987 		return (status);
2988 	}
2989 
2990 	/* Update other global config parameters */
2991 	if (iscsit_global.global_props) {
2992 		nvlist_free(iscsit_global.global_props);
2993 		iscsit_global.global_props = NULL;
2994 	}
2995 	if (in_cfg) {
2996 		(void) nvlist_dup(cfg->config_global_properties,
2997 		    &iscsit_global.global_props, KM_SLEEP);
2998 	}
2999 	ISCSIT_GLOBAL_UNLOCK();
3000 
3001 	iscsit_config_destroy_tpgs(&tpg_del_list);
3002 
3003 	list_destroy(&tpg_del_list);
3004 
3005 	return (ITCFG_SUCCESS);
3006 }
3007 
3008 /*
3009  * iscsit_sna_lt[e]
3010  *
3011  * Compare serial numbers using serial number arithmetic as defined in
3012  * RFC 1982.
3013  *
3014  * NOTE: This code is duplicated in the isns server. It ought to be common.
3015  */
3016 
3017 static int
3018 iscsit_sna_lt(uint32_t sn1, uint32_t sn2)
3019 {
3020 	return ((sn1 != sn2) &&
3021 	    (((sn1 < sn2) && ((sn2 - sn1) < ISCSIT_SNA32_CHECK)) ||
3022 	    ((sn1 > sn2) && ((sn1 - sn2) > ISCSIT_SNA32_CHECK))));
3023 }
3024 
3025 static int
3026 iscsit_sna_lte(uint32_t sn1, uint32_t sn2)
3027 {
3028 	return ((sn1 == sn2) ||
3029 	    (((sn1 < sn2) && ((sn2 - sn1) < ISCSIT_SNA32_CHECK)) ||
3030 	    ((sn1 > sn2) && ((sn1 - sn2) > ISCSIT_SNA32_CHECK))));
3031 }
3032 
3033 
3034 static boolean_t
3035 iscsit_cmdsn_in_window(iscsit_conn_t *ict, uint32_t cmdsn)
3036 {
3037 	iscsit_sess_t	*ist = ict->ict_sess;
3038 	int		rval = B_TRUE;
3039 
3040 	ist = ict->ict_sess;
3041 
3042 	mutex_enter(&ist->ist_sn_mutex);
3043 
3044 	/*
3045 	 * If cmdsn is less than ist_expcmdsn - iscsit_cmd_window() or
3046 	 * greater than ist_expcmdsn, it's not in the window.
3047 	 */
3048 
3049 	if (iscsit_sna_lt(cmdsn, (ist->ist_expcmdsn - iscsit_cmd_window())) ||
3050 	    !iscsit_sna_lte(cmdsn, ist->ist_expcmdsn)) {
3051 		rval = B_FALSE;
3052 	}
3053 
3054 	mutex_exit(&ist->ist_sn_mutex);
3055 
3056 	return (rval);
3057 }
3058 
3059 /*
3060  * iscsit_check_cmdsn_and_queue
3061  *
3062  * Independent of the order in which the iSCSI target receives non-immediate
3063  * command PDU across the entire session and any multiple connections within
3064  * the session, the target must deliver the commands to the SCSI layer in
3065  * CmdSN order. So out-of-order non-immediate commands are queued up on a
3066  * session-wide wait queue. Duplicate commands are ignored.
3067  *
3068  */
3069 static int
3070 iscsit_check_cmdsn_and_queue(idm_pdu_t *rx_pdu)
3071 {
3072 	idm_conn_t		*ic = rx_pdu->isp_ic;
3073 	iscsit_conn_t		*ict = ic->ic_handle;
3074 	iscsit_sess_t		*ist = ict->ict_sess;
3075 	iscsi_scsi_cmd_hdr_t	*hdr = (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
3076 
3077 	mutex_enter(&ist->ist_sn_mutex);
3078 	if (hdr->opcode & ISCSI_OP_IMMEDIATE) {
3079 		/* do not queue, handle it immediately */
3080 		DTRACE_PROBE2(immediate__cmd, iscsit_sess_t *, ist,
3081 		    idm_pdu_t *, rx_pdu);
3082 		mutex_exit(&ist->ist_sn_mutex);
3083 		return (ISCSIT_CMDSN_EQ_EXPCMDSN);
3084 	}
3085 	if (iscsit_sna_lt(ist->ist_expcmdsn, ntohl(hdr->cmdsn))) {
3086 		/*
3087 		 * Out-of-order commands (cmdSN higher than ExpCmdSN)
3088 		 * are staged on a fixed-size circular buffer until
3089 		 * the missing command is delivered to the SCSI layer.
3090 		 * Irrespective of the order of insertion into the
3091 		 * staging queue, the commands are processed out of the
3092 		 * queue in cmdSN order only.
3093 		 */
3094 		rx_pdu->isp_queue_time = ddi_get_time();
3095 		iscsit_add_pdu_to_queue(ist, rx_pdu);
3096 		mutex_exit(&ist->ist_sn_mutex);
3097 		return (ISCSIT_CMDSN_GT_EXPCMDSN);
3098 	} else if (iscsit_sna_lt(ntohl(hdr->cmdsn), ist->ist_expcmdsn)) {
3099 		DTRACE_PROBE3(cmdsn__lt__expcmdsn, iscsit_sess_t *, ist,
3100 		    iscsit_conn_t *, ict, idm_pdu_t *, rx_pdu);
3101 		mutex_exit(&ist->ist_sn_mutex);
3102 		return (ISCSIT_CMDSN_LT_EXPCMDSN);
3103 	} else {
3104 		mutex_exit(&ist->ist_sn_mutex);
3105 		return (ISCSIT_CMDSN_EQ_EXPCMDSN);
3106 	}
3107 }
3108 
3109 /*
3110  * iscsit_add_pdu_to_queue() adds PDUs into the array indexed by
3111  * their cmdsn value. The length of the array is kept above the
3112  * maximum window size. The window keeps the cmdsn within a range
3113  * such that there are no collisons. e.g. the assumption is that
3114  * the windowing checks make it impossible to receive PDUs that
3115  * index into the same location in the array.
3116  */
3117 static void
3118 iscsit_add_pdu_to_queue(iscsit_sess_t *ist, idm_pdu_t *rx_pdu)
3119 {
3120 	iscsit_cbuf_t	*cbuf	= ist->ist_rxpdu_queue;
3121 	iscsit_conn_t	*ict 	= rx_pdu->isp_ic->ic_handle;
3122 	uint32_t	cmdsn	=
3123 	    ((iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr)->cmdsn;
3124 	uint32_t	index;
3125 
3126 	ASSERT(MUTEX_HELD(&ist->ist_sn_mutex));
3127 	/*
3128 	 * If the connection is being torn down, then
3129 	 * don't add the PDU to the staging queue
3130 	 */
3131 	mutex_enter(&ict->ict_mutex);
3132 	if (ict->ict_lost) {
3133 		mutex_exit(&ict->ict_mutex);
3134 		idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
3135 		return;
3136 	}
3137 	iscsit_conn_dispatch_hold(ict);
3138 	mutex_exit(&ict->ict_mutex);
3139 
3140 	index = ntohl(cmdsn) % ISCSIT_RXPDU_QUEUE_LEN;
3141 	ASSERT(cbuf->cb_buffer[index] == NULL);
3142 	cbuf->cb_buffer[index] = rx_pdu;
3143 	cbuf->cb_num_elems++;
3144 }
3145 
3146 static idm_pdu_t *
3147 iscsit_remove_pdu_from_queue(iscsit_sess_t *ist, uint32_t cmdsn)
3148 {
3149 	iscsit_cbuf_t	*cbuf	= ist->ist_rxpdu_queue;
3150 	idm_pdu_t	*pdu	= NULL;
3151 	uint32_t	index;
3152 
3153 	ASSERT(MUTEX_HELD(&ist->ist_sn_mutex));
3154 	index = cmdsn % ISCSIT_RXPDU_QUEUE_LEN;
3155 	if ((pdu = cbuf->cb_buffer[index]) != NULL) {
3156 		ASSERT(cmdsn ==
3157 		    ntohl(((iscsi_scsi_cmd_hdr_t *)pdu->isp_hdr)->cmdsn));
3158 		cbuf->cb_buffer[index] = NULL;
3159 		cbuf->cb_num_elems--;
3160 		return (pdu);
3161 	}
3162 	return (NULL);
3163 }
3164 
3165 /*
3166  * iscsit_process_pdu_in_queue() finds the next pdu in sequence
3167  * and posts it to the SCSI layer
3168  */
3169 static void
3170 iscsit_process_pdu_in_queue(iscsit_sess_t *ist)
3171 {
3172 	iscsit_cbuf_t	*cbuf	= ist->ist_rxpdu_queue;
3173 	idm_pdu_t	*pdu = NULL;
3174 	uint32_t	expcmdsn;
3175 
3176 	for (;;) {
3177 		mutex_enter(&ist->ist_sn_mutex);
3178 		if (cbuf->cb_num_elems == 0) {
3179 			mutex_exit(&ist->ist_sn_mutex);
3180 			break;
3181 		}
3182 		expcmdsn = ist->ist_expcmdsn;
3183 		if ((pdu = iscsit_remove_pdu_from_queue(ist, expcmdsn))
3184 		    == NULL) {
3185 			mutex_exit(&ist->ist_sn_mutex);
3186 			break;
3187 		}
3188 		mutex_exit(&ist->ist_sn_mutex);
3189 		iscsit_post_staged_pdu(pdu);
3190 	}
3191 }
3192 
3193 static void
3194 iscsit_post_staged_pdu(idm_pdu_t *rx_pdu)
3195 {
3196 	iscsit_conn_t	*ict	= rx_pdu->isp_ic->ic_handle;
3197 
3198 	/* Post the PDU to the SCSI layer */
3199 	switch (IDM_PDU_OPCODE(rx_pdu)) {
3200 	case ISCSI_OP_NOOP_OUT:
3201 		iscsit_set_cmdsn(ict, rx_pdu);
3202 		iscsit_pdu_op_noop(ict, rx_pdu);
3203 		break;
3204 	case ISCSI_OP_TEXT_CMD:
3205 		iscsit_set_cmdsn(ict, rx_pdu);
3206 		iscsit_pdu_op_text_cmd(ict, rx_pdu);
3207 		break;
3208 	case ISCSI_OP_SCSI_TASK_MGT_MSG:
3209 		iscsit_set_cmdsn(ict, rx_pdu);
3210 		iscsit_op_scsi_task_mgmt(ict, rx_pdu);
3211 		break;
3212 	case ISCSI_OP_SCSI_CMD:
3213 		/* cmdSN will be incremented after creating itask */
3214 		iscsit_post_scsi_cmd(rx_pdu->isp_ic, rx_pdu);
3215 		break;
3216 	case ISCSI_OP_LOGOUT_CMD:
3217 		iscsit_set_cmdsn(ict, rx_pdu);
3218 		iscsit_pdu_op_logout_cmd(ict, rx_pdu);
3219 		break;
3220 	default:
3221 		/* No other PDUs should be placed on the queue */
3222 		ASSERT(0);
3223 	}
3224 	iscsit_conn_dispatch_rele(ict); /* release hold on the conn */
3225 }
3226 
3227 /* ARGSUSED */
3228 void
3229 iscsit_rxpdu_queue_monitor_start(void)
3230 {
3231 	mutex_enter(&iscsit_rxpdu_queue_monitor_mutex);
3232 	if (iscsit_rxpdu_queue_monitor_thr_running) {
3233 		mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3234 		return;
3235 	}
3236 	iscsit_rxpdu_queue_monitor_thr_id =
3237 	    thread_create(NULL, 0, iscsit_rxpdu_queue_monitor, NULL,
3238 	    0, &p0, TS_RUN, minclsyspri);
3239 	while (!iscsit_rxpdu_queue_monitor_thr_running) {
3240 		cv_wait(&iscsit_rxpdu_queue_monitor_cv,
3241 		    &iscsit_rxpdu_queue_monitor_mutex);
3242 	}
3243 	mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3244 
3245 }
3246 
3247 /* ARGSUSED */
3248 void
3249 iscsit_rxpdu_queue_monitor_stop(void)
3250 {
3251 	mutex_enter(&iscsit_rxpdu_queue_monitor_mutex);
3252 	if (iscsit_rxpdu_queue_monitor_thr_running) {
3253 		iscsit_rxpdu_queue_monitor_thr_running = B_FALSE;
3254 		cv_signal(&iscsit_rxpdu_queue_monitor_cv);
3255 		mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3256 
3257 		thread_join(iscsit_rxpdu_queue_monitor_thr_did);
3258 		return;
3259 	}
3260 	mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3261 }
3262 
3263 /*
3264  * A separate thread is used to scan the staging queue on all the
3265  * sessions, If a delayed PDU does not arrive within a timeout, the
3266  * target will advance to the staged PDU that is next in sequence
3267  * and exceeded the threshold wait time. It is up to the initiator
3268  * to note that the target has not acknowledged a particular cmdsn
3269  * and take appropriate action.
3270  */
3271 /* ARGSUSED */
3272 static void
3273 iscsit_rxpdu_queue_monitor(void *arg)
3274 {
3275 	iscsit_tgt_t	*tgt;
3276 	iscsit_sess_t	*ist;
3277 
3278 	mutex_enter(&iscsit_rxpdu_queue_monitor_mutex);
3279 	iscsit_rxpdu_queue_monitor_thr_did = curthread->t_did;
3280 	iscsit_rxpdu_queue_monitor_thr_running = B_TRUE;
3281 	cv_signal(&iscsit_rxpdu_queue_monitor_cv);
3282 
3283 	while (iscsit_rxpdu_queue_monitor_thr_running) {
3284 		ISCSIT_GLOBAL_LOCK(RW_READER);
3285 		for (tgt = avl_first(&iscsit_global.global_target_list);
3286 		    tgt != NULL;
3287 		    tgt = AVL_NEXT(&iscsit_global.global_target_list, tgt)) {
3288 			mutex_enter(&tgt->target_mutex);
3289 			for (ist = avl_first(&tgt->target_sess_list);
3290 			    ist != NULL;
3291 			    ist = AVL_NEXT(&tgt->target_sess_list, ist)) {
3292 
3293 				iscsit_rxpdu_queue_monitor_session(ist);
3294 			}
3295 			mutex_exit(&tgt->target_mutex);
3296 		}
3297 		ISCSIT_GLOBAL_UNLOCK();
3298 		if (iscsit_rxpdu_queue_monitor_thr_running == B_FALSE) {
3299 			break;
3300 		}
3301 		(void) cv_reltimedwait(&iscsit_rxpdu_queue_monitor_cv,
3302 		    &iscsit_rxpdu_queue_monitor_mutex,
3303 		    ISCSIT_RXPDU_QUEUE_MONITOR_INTERVAL * drv_usectohz(1000000),
3304 		    TR_CLOCK_TICK);
3305 	}
3306 	mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3307 	thread_exit();
3308 }
3309 
3310 static void
3311 iscsit_rxpdu_queue_monitor_session(iscsit_sess_t *ist)
3312 {
3313 	iscsit_cbuf_t	*cbuf	= ist->ist_rxpdu_queue;
3314 	idm_pdu_t	*next_pdu = NULL;
3315 	uint32_t	index, next_cmdsn, i;
3316 
3317 	/*
3318 	 * Assume that all PDUs in the staging queue have a cmdsn >= expcmdsn.
3319 	 * Starting with the expcmdsn, iterate over the staged PDUs to find
3320 	 * the next PDU with a wait time greater than the threshold. If found
3321 	 * advance the staged PDU to the SCSI layer, skipping over the missing
3322 	 * PDU(s) to get past the hole in the command sequence. It is up to
3323 	 * the initiator to note that the target has not acknowledged a cmdsn
3324 	 * and take appropriate action.
3325 	 *
3326 	 * Since the PDU(s) arrive in any random order, it is possible that
3327 	 * that the actual wait time for a particular PDU is much longer than
3328 	 * the defined threshold. e.g. Consider a case where commands are sent
3329 	 * over 4 different connections, and cmdsn = 1004 arrives first, then
3330 	 * 1003, and 1002 and 1001 are lost due to a connection failure.
3331 	 * So now 1003 is waiting for 1002 to be delivered, and although the
3332 	 * wait time of 1004 > wait time of 1003, only 1003 will be considered
3333 	 * by the monitor thread. 1004 will be automatically processed by
3334 	 * iscsit_process_pdu_in_queue() once the scan is complete and the
3335 	 * expcmdsn becomes current.
3336 	 */
3337 	mutex_enter(&ist->ist_sn_mutex);
3338 	cbuf = ist->ist_rxpdu_queue;
3339 	if (cbuf->cb_num_elems == 0) {
3340 		mutex_exit(&ist->ist_sn_mutex);
3341 		return;
3342 	}
3343 	for (next_pdu = NULL, i = 0; ; i++) {
3344 		next_cmdsn = ist->ist_expcmdsn + i; /* start at expcmdsn */
3345 		index = next_cmdsn % ISCSIT_RXPDU_QUEUE_LEN;
3346 		if ((next_pdu = cbuf->cb_buffer[index]) != NULL) {
3347 			/*
3348 			 * If the PDU wait time has not exceeded threshold
3349 			 * stop scanning the staging queue until the timer
3350 			 * fires again
3351 			 */
3352 			if ((ddi_get_time() - next_pdu->isp_queue_time)
3353 			    < rxpdu_queue_threshold) {
3354 				mutex_exit(&ist->ist_sn_mutex);
3355 				return;
3356 			}
3357 			/*
3358 			 * Remove the next PDU from the queue and post it
3359 			 * to the SCSI layer, skipping over the missing
3360 			 * PDU. Stop scanning the staging queue until
3361 			 * the monitor timer fires again
3362 			 */
3363 			(void) iscsit_remove_pdu_from_queue(ist, next_cmdsn);
3364 			mutex_exit(&ist->ist_sn_mutex);
3365 			DTRACE_PROBE3(advanced__to__blocked__cmdsn,
3366 			    iscsit_sess_t *, ist, idm_pdu_t *, next_pdu,
3367 			    uint32_t, next_cmdsn);
3368 			iscsit_post_staged_pdu(next_pdu);
3369 			/* Deliver any subsequent PDUs immediately */
3370 			iscsit_process_pdu_in_queue(ist);
3371 			return;
3372 		}
3373 		/*
3374 		 * Skipping over i PDUs, e.g. a case where commands 1001 and
3375 		 * 1002 are lost in the network, skip over both and post 1003
3376 		 * expcmdsn then becomes 1004 at the end of the scan.
3377 		 */
3378 		DTRACE_PROBE2(skipping__over__cmdsn, iscsit_sess_t *, ist,
3379 		    uint32_t, next_cmdsn);
3380 	}
3381 	/*
3382 	 * following the assumption, staged cmdsn >= expcmdsn, this statement
3383 	 * is never reached.
3384 	 */
3385 }
3386