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  * Copyright 2012 Nexenta Systems, Inc. All rights reserved.
25  */
26 
27 #include <sys/cpuvar.h>
28 #include <sys/types.h>
29 #include <sys/conf.h>
30 #include <sys/stat.h>
31 #include <sys/file.h>
32 #include <sys/ddi.h>
33 #include <sys/sunddi.h>
34 #include <sys/modctl.h>
35 #include <sys/sysmacros.h>
36 #include <sys/socket.h>
37 #include <sys/strsubr.h>
38 #include <sys/nvpair.h>
39 
40 #include <sys/stmf.h>
41 #include <sys/stmf_ioctl.h>
42 #include <sys/portif.h>
43 #include <sys/idm/idm.h>
44 #include <sys/idm/idm_conn_sm.h>
45 
46 #include "iscsit_isns.h"
47 #include "iscsit.h"
48 
49 #define	ISCSIT_VERSION		BUILD_DATE "-1.18dev"
50 #define	ISCSIT_NAME_VERSION	"COMSTAR ISCSIT v" ISCSIT_VERSION
51 
52 /*
53  * DDI entry points.
54  */
55 static int iscsit_drv_attach(dev_info_t *, ddi_attach_cmd_t);
56 static int iscsit_drv_detach(dev_info_t *, ddi_detach_cmd_t);
57 static int iscsit_drv_getinfo(dev_info_t *, ddi_info_cmd_t, void *, void **);
58 static int iscsit_drv_open(dev_t *, int, int, cred_t *);
59 static int iscsit_drv_close(dev_t, int, int, cred_t *);
60 static boolean_t iscsit_drv_busy(void);
61 static int iscsit_drv_ioctl(dev_t, int, intptr_t, int, cred_t *, int *);
62 
63 extern struct mod_ops mod_miscops;
64 
65 
66 static struct cb_ops iscsit_cb_ops = {
67 	iscsit_drv_open,	/* cb_open */
68 	iscsit_drv_close,	/* cb_close */
69 	nodev,			/* cb_strategy */
70 	nodev,			/* cb_print */
71 	nodev,			/* cb_dump */
72 	nodev,			/* cb_read */
73 	nodev,			/* cb_write */
74 	iscsit_drv_ioctl,	/* cb_ioctl */
75 	nodev,			/* cb_devmap */
76 	nodev,			/* cb_mmap */
77 	nodev,			/* cb_segmap */
78 	nochpoll,		/* cb_chpoll */
79 	ddi_prop_op,		/* cb_prop_op */
80 	NULL,			/* cb_streamtab */
81 	D_MP,			/* cb_flag */
82 	CB_REV,			/* cb_rev */
83 	nodev,			/* cb_aread */
84 	nodev,			/* cb_awrite */
85 };
86 
87 static struct dev_ops iscsit_dev_ops = {
88 	DEVO_REV,		/* devo_rev */
89 	0,			/* devo_refcnt */
90 	iscsit_drv_getinfo,	/* devo_getinfo */
91 	nulldev,		/* devo_identify */
92 	nulldev,		/* devo_probe */
93 	iscsit_drv_attach,	/* devo_attach */
94 	iscsit_drv_detach,	/* devo_detach */
95 	nodev,			/* devo_reset */
96 	&iscsit_cb_ops,		/* devo_cb_ops */
97 	NULL,			/* devo_bus_ops */
98 	NULL,			/* devo_power */
99 	ddi_quiesce_not_needed,	/* quiesce */
100 };
101 
102 static struct modldrv modldrv = {
103 	&mod_driverops,
104 	"iSCSI Target",
105 	&iscsit_dev_ops,
106 };
107 
108 static struct modlinkage modlinkage = {
109 	MODREV_1,
110 	&modldrv,
111 	NULL,
112 };
113 
114 
115 iscsit_global_t iscsit_global;
116 
117 kmem_cache_t	*iscsit_status_pdu_cache;
118 
119 boolean_t	iscsit_sm_logging = B_FALSE;
120 
121 kmutex_t	login_sm_session_mutex;
122 
123 static idm_status_t iscsit_init(dev_info_t *dip);
124 static idm_status_t iscsit_enable_svc(iscsit_hostinfo_t *hostinfo);
125 static void iscsit_disable_svc(void);
126 
127 static int
128 iscsit_check_cmdsn_and_queue(idm_pdu_t *rx_pdu);
129 
130 static void
131 iscsit_add_pdu_to_queue(iscsit_sess_t *ist, idm_pdu_t *rx_pdu);
132 
133 static idm_pdu_t *
134 iscsit_remove_pdu_from_queue(iscsit_sess_t *ist, uint32_t cmdsn);
135 
136 static void
137 iscsit_process_pdu_in_queue(iscsit_sess_t *ist);
138 
139 static void
140 iscsit_rxpdu_queue_monitor_session(iscsit_sess_t *ist);
141 
142 static void
143 iscsit_rxpdu_queue_monitor(void *arg);
144 
145 static void
146 iscsit_post_staged_pdu(idm_pdu_t *rx_pdu);
147 
148 static void
149 iscsit_post_scsi_cmd(idm_conn_t *ic, idm_pdu_t *rx_pdu);
150 
151 static void
152 iscsit_op_scsi_task_mgmt(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
153 
154 static void
155 iscsit_pdu_op_noop(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
156 
157 static void
158 iscsit_pdu_op_login_cmd(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
159 
160 void
161 iscsit_pdu_op_text_cmd(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
162 
163 static void
164 iscsit_pdu_op_logout_cmd(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
165 
166 int iscsit_cmd_window();
167 
168 static  int
169 iscsit_sna_lt(uint32_t sn1, uint32_t sn2);
170 
171 void
172 iscsit_set_cmdsn(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
173 
174 static void
175 iscsit_deferred_dispatch(idm_pdu_t *rx_pdu);
176 
177 static void
178 iscsit_deferred(void *rx_pdu_void);
179 
180 static idm_status_t
181 iscsit_conn_accept(idm_conn_t *ic);
182 
183 static idm_status_t
184 iscsit_ffp_enabled(idm_conn_t *ic);
185 
186 static idm_status_t
187 iscsit_ffp_disabled(idm_conn_t *ic, idm_ffp_disable_t disable_class);
188 
189 static idm_status_t
190 iscsit_conn_lost(idm_conn_t *ic);
191 
192 static idm_status_t
193 iscsit_conn_destroy(idm_conn_t *ic);
194 
195 static stmf_data_buf_t *
196 iscsit_dbuf_alloc(scsi_task_t *task, uint32_t size, uint32_t *pminsize,
197     uint32_t flags);
198 
199 static void
200 iscsit_dbuf_free(stmf_dbuf_store_t *ds, stmf_data_buf_t *dbuf);
201 
202 static void
203 iscsit_buf_xfer_cb(idm_buf_t *idb, idm_status_t status);
204 
205 static void
206 iscsit_send_good_status_done(idm_pdu_t *pdu, idm_status_t status);
207 
208 static void
209 iscsit_send_status_done(idm_pdu_t *pdu, idm_status_t status);
210 
211 static stmf_status_t
212 iscsit_idm_to_stmf(idm_status_t idmrc);
213 
214 static iscsit_task_t *
215 iscsit_task_alloc(iscsit_conn_t *ict);
216 
217 static void
218 iscsit_task_free(iscsit_task_t *itask);
219 
220 static iscsit_task_t *
221 iscsit_tm_task_alloc(iscsit_conn_t *ict);
222 
223 static void
224 iscsit_tm_task_free(iscsit_task_t *itask);
225 
226 static idm_status_t
227 iscsit_task_start(iscsit_task_t *itask);
228 
229 static void
230 iscsit_task_done(iscsit_task_t *itask);
231 
232 static int
233 iscsit_status_pdu_constructor(void *pdu_void, void *arg, int flags);
234 
235 static void
236 iscsit_pp_cb(struct stmf_port_provider *pp, int cmd, void *arg, uint32_t flags);
237 
238 static it_cfg_status_t
239 iscsit_config_merge(it_config_t *cfg);
240 
241 static idm_status_t
242 iscsit_login_fail(idm_conn_t *ic);
243 
244 static boolean_t iscsit_cmdsn_in_window(iscsit_conn_t *ict, uint32_t cmdsn);
245 static void iscsit_send_direct_scsi_resp(iscsit_conn_t *ict, idm_pdu_t *rx_pdu,
246     uint8_t response, uint8_t cmd_status);
247 static void iscsit_send_task_mgmt_resp(idm_pdu_t *tm_resp_pdu,
248     uint8_t tm_status);
249 
250 /*
251  * MC/S: Out-of-order commands are staged on a session-wide wait
252  * queue until a system-tunable threshold is reached. A separate
253  * thread is used to scan the staging queue on all the session,
254  * If a delayed PDU does not arrive within a timeout, the target
255  * will advance to the staged PDU that is next in sequence, skipping
256  * over the missing PDU(s) to go past a hole in the sequence.
257  */
258 volatile int rxpdu_queue_threshold = ISCSIT_RXPDU_QUEUE_THRESHOLD;
259 
260 static kmutex_t		iscsit_rxpdu_queue_monitor_mutex;
261 kthread_t		*iscsit_rxpdu_queue_monitor_thr_id;
262 static kt_did_t		iscsit_rxpdu_queue_monitor_thr_did;
263 static boolean_t	iscsit_rxpdu_queue_monitor_thr_running;
264 static kcondvar_t	iscsit_rxpdu_queue_monitor_cv;
265 
266 int
267 _init(void)
268 {
269 	int rc;
270 
271 	rw_init(&iscsit_global.global_rwlock, NULL, RW_DRIVER, NULL);
272 	mutex_init(&iscsit_global.global_state_mutex, NULL,
273 	    MUTEX_DRIVER, NULL);
274 	iscsit_global.global_svc_state = ISE_DETACHED;
275 
276 	mutex_init(&iscsit_rxpdu_queue_monitor_mutex, NULL,
277 	    MUTEX_DRIVER, NULL);
278 	mutex_init(&login_sm_session_mutex, NULL, MUTEX_DRIVER, NULL);
279 	iscsit_rxpdu_queue_monitor_thr_id = NULL;
280 	iscsit_rxpdu_queue_monitor_thr_running = B_FALSE;
281 	cv_init(&iscsit_rxpdu_queue_monitor_cv, NULL, CV_DEFAULT, NULL);
282 
283 	if ((rc = mod_install(&modlinkage)) != 0) {
284 		mutex_destroy(&iscsit_global.global_state_mutex);
285 		rw_destroy(&iscsit_global.global_rwlock);
286 		return (rc);
287 	}
288 
289 	return (rc);
290 }
291 
292 int
293 _info(struct modinfo *modinfop)
294 {
295 	return (mod_info(&modlinkage, modinfop));
296 }
297 
298 int
299 _fini(void)
300 {
301 	int rc;
302 
303 	rc = mod_remove(&modlinkage);
304 
305 	if (rc == 0) {
306 		mutex_destroy(&iscsit_rxpdu_queue_monitor_mutex);
307 		mutex_destroy(&login_sm_session_mutex);
308 		cv_destroy(&iscsit_rxpdu_queue_monitor_cv);
309 		mutex_destroy(&iscsit_global.global_state_mutex);
310 		rw_destroy(&iscsit_global.global_rwlock);
311 	}
312 
313 	return (rc);
314 }
315 
316 /*
317  * DDI entry points.
318  */
319 
320 /* ARGSUSED */
321 static int
322 iscsit_drv_getinfo(dev_info_t *dip, ddi_info_cmd_t cmd, void *arg,
323     void **result)
324 {
325 	ulong_t instance = getminor((dev_t)arg);
326 
327 	switch (cmd) {
328 	case DDI_INFO_DEVT2DEVINFO:
329 		*result = iscsit_global.global_dip;
330 		return (DDI_SUCCESS);
331 
332 	case DDI_INFO_DEVT2INSTANCE:
333 		*result = (void *)instance;
334 		return (DDI_SUCCESS);
335 
336 	default:
337 		break;
338 	}
339 
340 	return (DDI_FAILURE);
341 }
342 
343 static int
344 iscsit_drv_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
345 {
346 	if (cmd != DDI_ATTACH) {
347 		return (DDI_FAILURE);
348 	}
349 
350 	if (ddi_get_instance(dip) != 0) {
351 		/* we only allow instance 0 to attach */
352 		return (DDI_FAILURE);
353 	}
354 
355 	/* create the minor node */
356 	if (ddi_create_minor_node(dip, ISCSIT_MODNAME, S_IFCHR, 0,
357 	    DDI_PSEUDO, 0) != DDI_SUCCESS) {
358 		cmn_err(CE_WARN, "iscsit_drv_attach: "
359 		    "failed creating minor node");
360 		return (DDI_FAILURE);
361 	}
362 
363 	if (iscsit_init(dip) != IDM_STATUS_SUCCESS) {
364 		cmn_err(CE_WARN, "iscsit_drv_attach: "
365 		    "failed to initialize");
366 		ddi_remove_minor_node(dip, NULL);
367 		return (DDI_FAILURE);
368 	}
369 
370 	iscsit_global.global_svc_state = ISE_DISABLED;
371 	iscsit_global.global_dip = dip;
372 
373 	return (DDI_SUCCESS);
374 }
375 
376 /*ARGSUSED*/
377 static int
378 iscsit_drv_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
379 {
380 	if (cmd != DDI_DETACH)
381 		return (DDI_FAILURE);
382 
383 	/*
384 	 * drv_detach is called in a context that owns the
385 	 * device node for the /dev/pseudo device.  If this thread blocks
386 	 * for any resource, other threads that need the /dev/pseudo device
387 	 * may end up in a deadlock with this thread.Hence, we use a
388 	 * separate lock just for the structures that drv_detach needs
389 	 * to access.
390 	 */
391 	mutex_enter(&iscsit_global.global_state_mutex);
392 	if (iscsit_drv_busy()) {
393 		mutex_exit(&iscsit_global.global_state_mutex);
394 		return (EBUSY);
395 	}
396 
397 	iscsit_global.global_dip = NULL;
398 	ddi_remove_minor_node(dip, NULL);
399 
400 	ldi_ident_release(iscsit_global.global_li);
401 	iscsit_global.global_svc_state = ISE_DETACHED;
402 
403 	mutex_exit(&iscsit_global.global_state_mutex);
404 
405 	return (DDI_SUCCESS);
406 }
407 
408 /*ARGSUSED*/
409 static int
410 iscsit_drv_open(dev_t *devp, int flag, int otyp, cred_t *credp)
411 {
412 	return (0);
413 }
414 
415 /* ARGSUSED */
416 static int
417 iscsit_drv_close(dev_t dev, int flag, int otyp, cred_t *credp)
418 {
419 	return (0);
420 }
421 
422 static boolean_t
423 iscsit_drv_busy(void)
424 {
425 	ASSERT(MUTEX_HELD(&iscsit_global.global_state_mutex));
426 
427 	switch (iscsit_global.global_svc_state) {
428 	case ISE_DISABLED:
429 	case ISE_DETACHED:
430 		return (B_FALSE);
431 	default:
432 		return (B_TRUE);
433 	}
434 	/* NOTREACHED */
435 }
436 
437 /* ARGSUSED */
438 static int
439 iscsit_drv_ioctl(dev_t drv, int cmd, intptr_t argp, int flag, cred_t *cred,
440     int *retval)
441 {
442 	iscsit_ioc_set_config_t		setcfg;
443 	iscsit_ioc_set_config32_t	setcfg32;
444 	char				*cfg_pnvlist = NULL;
445 	nvlist_t			*cfg_nvlist = NULL;
446 	it_config_t			*cfg = NULL;
447 	idm_status_t			idmrc;
448 	int				rc = 0;
449 
450 	if (drv_priv(cred) != 0) {
451 		return (EPERM);
452 	}
453 
454 	mutex_enter(&iscsit_global.global_state_mutex);
455 
456 	/*
457 	 * Validate ioctl requests against global service state
458 	 */
459 	switch (iscsit_global.global_svc_state) {
460 	case ISE_ENABLED:
461 		if (cmd == ISCSIT_IOC_DISABLE_SVC) {
462 			iscsit_global.global_svc_state = ISE_DISABLING;
463 		} else if (cmd == ISCSIT_IOC_ENABLE_SVC) {
464 			/* Already enabled */
465 			mutex_exit(&iscsit_global.global_state_mutex);
466 			return (0);
467 		} else {
468 			iscsit_global.global_svc_state = ISE_BUSY;
469 		}
470 		break;
471 	case ISE_DISABLED:
472 		if (cmd == ISCSIT_IOC_ENABLE_SVC) {
473 			iscsit_global.global_svc_state = ISE_ENABLING;
474 		} else if (cmd == ISCSIT_IOC_DISABLE_SVC) {
475 			/* Already disabled */
476 			mutex_exit(&iscsit_global.global_state_mutex);
477 			return (0);
478 		} else {
479 			rc = EFAULT;
480 		}
481 		break;
482 	case ISE_BUSY:
483 	case ISE_ENABLING:
484 	case ISE_DISABLING:
485 		rc = EAGAIN;
486 		break;
487 	case ISE_DETACHED:
488 	default:
489 		rc = EFAULT;
490 		break;
491 	}
492 
493 	mutex_exit(&iscsit_global.global_state_mutex);
494 	if (rc != 0)
495 		return (rc);
496 
497 	/* Handle ioctl request (enable/disable have already been handled) */
498 	switch (cmd) {
499 	case ISCSIT_IOC_SET_CONFIG:
500 		/* Any errors must set state back to ISE_ENABLED */
501 		switch (ddi_model_convert_from(flag & FMODELS)) {
502 		case DDI_MODEL_ILP32:
503 			if (ddi_copyin((void *)argp, &setcfg32,
504 			    sizeof (iscsit_ioc_set_config32_t), flag) != 0) {
505 				rc = EFAULT;
506 				goto cleanup;
507 			}
508 
509 			setcfg.set_cfg_pnvlist =
510 			    (char *)((uintptr_t)setcfg32.set_cfg_pnvlist);
511 			setcfg.set_cfg_vers = setcfg32.set_cfg_vers;
512 			setcfg.set_cfg_pnvlist_len =
513 			    setcfg32.set_cfg_pnvlist_len;
514 			break;
515 		case DDI_MODEL_NONE:
516 			if (ddi_copyin((void *)argp, &setcfg,
517 			    sizeof (iscsit_ioc_set_config_t), flag) != 0) {
518 				rc = EFAULT;
519 				goto cleanup;
520 			}
521 			break;
522 		default:
523 			rc = EFAULT;
524 			goto cleanup;
525 		}
526 
527 		/* Check API version */
528 		if (setcfg.set_cfg_vers != ISCSIT_API_VERS0) {
529 			rc = EINVAL;
530 			goto cleanup;
531 		}
532 
533 		/* Config is in packed nvlist format so unpack it */
534 		cfg_pnvlist = kmem_alloc(setcfg.set_cfg_pnvlist_len,
535 		    KM_SLEEP);
536 		ASSERT(cfg_pnvlist != NULL);
537 
538 		if (ddi_copyin(setcfg.set_cfg_pnvlist, cfg_pnvlist,
539 		    setcfg.set_cfg_pnvlist_len, flag) != 0) {
540 			rc = EFAULT;
541 			goto cleanup;
542 		}
543 
544 		rc = nvlist_unpack(cfg_pnvlist, setcfg.set_cfg_pnvlist_len,
545 		    &cfg_nvlist, KM_SLEEP);
546 		if (rc != 0) {
547 			goto cleanup;
548 		}
549 
550 		/* Translate nvlist */
551 		rc = it_nv_to_config(cfg_nvlist, &cfg);
552 		if (rc != 0) {
553 			cmn_err(CE_WARN, "Configuration is invalid");
554 			goto cleanup;
555 		}
556 
557 		/* Update config */
558 		rc = iscsit_config_merge(cfg);
559 		/* FALLTHROUGH */
560 
561 cleanup:
562 		if (cfg)
563 			it_config_free_cmn(cfg);
564 		if (cfg_pnvlist)
565 			kmem_free(cfg_pnvlist, setcfg.set_cfg_pnvlist_len);
566 		if (cfg_nvlist)
567 			nvlist_free(cfg_nvlist);
568 
569 		/*
570 		 * Now that the reconfig is complete set our state back to
571 		 * enabled.
572 		 */
573 		mutex_enter(&iscsit_global.global_state_mutex);
574 		iscsit_global.global_svc_state = ISE_ENABLED;
575 		mutex_exit(&iscsit_global.global_state_mutex);
576 		break;
577 	case ISCSIT_IOC_ENABLE_SVC: {
578 		iscsit_hostinfo_t hostinfo;
579 
580 		if (ddi_copyin((void *)argp, &hostinfo.length,
581 		    sizeof (hostinfo.length), flag) != 0) {
582 			mutex_enter(&iscsit_global.global_state_mutex);
583 			iscsit_global.global_svc_state = ISE_DISABLED;
584 			mutex_exit(&iscsit_global.global_state_mutex);
585 			return (EFAULT);
586 		}
587 
588 		if (hostinfo.length > sizeof (hostinfo.fqhn))
589 			hostinfo.length = sizeof (hostinfo.fqhn);
590 
591 		if (ddi_copyin((void *)((caddr_t)argp +
592 		    sizeof (hostinfo.length)), &hostinfo.fqhn,
593 		    hostinfo.length, flag) != 0) {
594 			mutex_enter(&iscsit_global.global_state_mutex);
595 			iscsit_global.global_svc_state = ISE_DISABLED;
596 			mutex_exit(&iscsit_global.global_state_mutex);
597 			return (EFAULT);
598 		}
599 
600 		idmrc = iscsit_enable_svc(&hostinfo);
601 		mutex_enter(&iscsit_global.global_state_mutex);
602 		if (idmrc == IDM_STATUS_SUCCESS) {
603 			iscsit_global.global_svc_state = ISE_ENABLED;
604 		} else {
605 			rc = EIO;
606 			iscsit_global.global_svc_state = ISE_DISABLED;
607 		}
608 		mutex_exit(&iscsit_global.global_state_mutex);
609 		break;
610 	}
611 	case ISCSIT_IOC_DISABLE_SVC:
612 		iscsit_disable_svc();
613 		mutex_enter(&iscsit_global.global_state_mutex);
614 		iscsit_global.global_svc_state = ISE_DISABLED;
615 		mutex_exit(&iscsit_global.global_state_mutex);
616 		break;
617 
618 	default:
619 		rc = EINVAL;
620 		mutex_enter(&iscsit_global.global_state_mutex);
621 		iscsit_global.global_svc_state = ISE_ENABLED;
622 		mutex_exit(&iscsit_global.global_state_mutex);
623 	}
624 
625 	return (rc);
626 }
627 
628 static idm_status_t
629 iscsit_init(dev_info_t *dip)
630 {
631 	int			rc;
632 
633 	rc = ldi_ident_from_dip(dip, &iscsit_global.global_li);
634 	ASSERT(rc == 0);  /* Failure indicates invalid argument */
635 
636 	iscsit_global.global_svc_state = ISE_DISABLED;
637 
638 	return (IDM_STATUS_SUCCESS);
639 }
640 
641 /*
642  * iscsit_enable_svc
643  *
644  * registers all the configured targets and target portals with STMF
645  */
646 static idm_status_t
647 iscsit_enable_svc(iscsit_hostinfo_t *hostinfo)
648 {
649 	stmf_port_provider_t	*pp;
650 	stmf_dbuf_store_t	*dbuf_store;
651 	boolean_t		did_iscsit_isns_init;
652 	idm_status_t		retval = IDM_STATUS_SUCCESS;
653 
654 	ASSERT(iscsit_global.global_svc_state == ISE_ENABLING);
655 
656 	/*
657 	 * Make sure that can tell if we have partially allocated
658 	 * in case we need to exit and tear down anything allocated.
659 	 */
660 	iscsit_global.global_tsih_pool = NULL;
661 	iscsit_global.global_dbuf_store = NULL;
662 	iscsit_status_pdu_cache = NULL;
663 	pp = NULL;
664 	iscsit_global.global_pp = NULL;
665 	iscsit_global.global_default_tpg = NULL;
666 	did_iscsit_isns_init = B_FALSE;
667 	iscsit_global.global_dispatch_taskq = NULL;
668 
669 	/* Setup remaining fields in iscsit_global_t */
670 	idm_refcnt_init(&iscsit_global.global_refcnt,
671 	    &iscsit_global);
672 
673 	avl_create(&iscsit_global.global_discovery_sessions,
674 	    iscsit_sess_avl_compare, sizeof (iscsit_sess_t),
675 	    offsetof(iscsit_sess_t, ist_tgt_ln));
676 
677 	avl_create(&iscsit_global.global_target_list,
678 	    iscsit_tgt_avl_compare, sizeof (iscsit_tgt_t),
679 	    offsetof(iscsit_tgt_t, target_global_ln));
680 
681 	list_create(&iscsit_global.global_deleted_target_list,
682 	    sizeof (iscsit_tgt_t),
683 	    offsetof(iscsit_tgt_t, target_global_deleted_ln));
684 
685 	avl_create(&iscsit_global.global_tpg_list,
686 	    iscsit_tpg_avl_compare, sizeof (iscsit_tpg_t),
687 	    offsetof(iscsit_tpg_t, tpg_global_ln));
688 
689 	avl_create(&iscsit_global.global_ini_list,
690 	    iscsit_ini_avl_compare, sizeof (iscsit_ini_t),
691 	    offsetof(iscsit_ini_t, ini_global_ln));
692 
693 	iscsit_global.global_tsih_pool = vmem_create("iscsit_tsih_pool",
694 	    (void *)1, ISCSI_MAX_TSIH, 1, NULL, NULL, NULL, 0,
695 	    VM_SLEEP | VMC_IDENTIFIER);
696 
697 	/*
698 	 * Setup STMF dbuf store.  Our buffers are bound to a specific
699 	 * connection so we really can't let STMF cache buffers for us.
700 	 * Consequently we'll just allocate one global buffer store.
701 	 */
702 	dbuf_store = stmf_alloc(STMF_STRUCT_DBUF_STORE, 0, 0);
703 	if (dbuf_store == NULL) {
704 		retval = IDM_STATUS_FAIL;
705 		goto tear_down_and_return;
706 	}
707 	dbuf_store->ds_alloc_data_buf = iscsit_dbuf_alloc;
708 	dbuf_store->ds_free_data_buf = iscsit_dbuf_free;
709 	dbuf_store->ds_port_private = NULL;
710 	iscsit_global.global_dbuf_store = dbuf_store;
711 
712 	/* Status PDU cache */
713 	iscsit_status_pdu_cache = kmem_cache_create("iscsit_status_pdu_cache",
714 	    sizeof (idm_pdu_t) + sizeof (iscsi_scsi_rsp_hdr_t), 8,
715 	    &iscsit_status_pdu_constructor,
716 	    NULL, NULL, NULL, NULL, KM_SLEEP);
717 
718 	/* Default TPG and portal */
719 	iscsit_global.global_default_tpg = iscsit_tpg_createdefault();
720 	if (iscsit_global.global_default_tpg == NULL) {
721 		retval = IDM_STATUS_FAIL;
722 		goto tear_down_and_return;
723 	}
724 
725 	/* initialize isns client */
726 	(void) iscsit_isns_init(hostinfo);
727 	did_iscsit_isns_init = B_TRUE;
728 
729 	/* Register port provider */
730 	pp = stmf_alloc(STMF_STRUCT_PORT_PROVIDER, 0, 0);
731 	if (pp == NULL) {
732 		retval = IDM_STATUS_FAIL;
733 		goto tear_down_and_return;
734 	}
735 
736 	pp->pp_portif_rev = PORTIF_REV_1;
737 	pp->pp_instance = 0;
738 	pp->pp_name = ISCSIT_MODNAME;
739 	pp->pp_cb = iscsit_pp_cb;
740 
741 	iscsit_global.global_pp = pp;
742 
743 
744 	if (stmf_register_port_provider(pp) != STMF_SUCCESS) {
745 		retval = IDM_STATUS_FAIL;
746 		goto tear_down_and_return;
747 	}
748 
749 	iscsit_global.global_dispatch_taskq = taskq_create("iscsit_dispatch",
750 	    1, minclsyspri, 16, 16, TASKQ_PREPOPULATE);
751 
752 	/* Scan staged PDUs, meaningful in MC/S situations */
753 	iscsit_rxpdu_queue_monitor_start();
754 
755 	return (IDM_STATUS_SUCCESS);
756 
757 tear_down_and_return:
758 
759 	if (iscsit_global.global_dispatch_taskq) {
760 		taskq_destroy(iscsit_global.global_dispatch_taskq);
761 		iscsit_global.global_dispatch_taskq = NULL;
762 	}
763 
764 	if (did_iscsit_isns_init)
765 		iscsit_isns_fini();
766 
767 	if (iscsit_global.global_default_tpg) {
768 		iscsit_tpg_destroydefault(iscsit_global.global_default_tpg);
769 		iscsit_global.global_default_tpg = NULL;
770 	}
771 
772 	if (iscsit_global.global_pp)
773 		iscsit_global.global_pp = NULL;
774 
775 	if (pp)
776 		stmf_free(pp);
777 
778 	if (iscsit_status_pdu_cache) {
779 		kmem_cache_destroy(iscsit_status_pdu_cache);
780 		iscsit_status_pdu_cache = NULL;
781 	}
782 
783 	if (iscsit_global.global_dbuf_store) {
784 		stmf_free(iscsit_global.global_dbuf_store);
785 		iscsit_global.global_dbuf_store = NULL;
786 	}
787 
788 	if (iscsit_global.global_tsih_pool) {
789 		vmem_destroy(iscsit_global.global_tsih_pool);
790 		iscsit_global.global_tsih_pool = NULL;
791 	}
792 
793 	avl_destroy(&iscsit_global.global_ini_list);
794 	avl_destroy(&iscsit_global.global_tpg_list);
795 	list_destroy(&iscsit_global.global_deleted_target_list);
796 	avl_destroy(&iscsit_global.global_target_list);
797 	avl_destroy(&iscsit_global.global_discovery_sessions);
798 
799 	idm_refcnt_destroy(&iscsit_global.global_refcnt);
800 
801 	return (retval);
802 }
803 
804 /*
805  * iscsit_disable_svc
806  *
807  * clean up all existing connections and deregister targets from STMF
808  */
809 static void
810 iscsit_disable_svc(void)
811 {
812 	iscsit_sess_t	*sess;
813 
814 	ASSERT(iscsit_global.global_svc_state == ISE_DISABLING);
815 
816 	iscsit_rxpdu_queue_monitor_stop();
817 
818 	/* tear down discovery sessions */
819 	for (sess = avl_first(&iscsit_global.global_discovery_sessions);
820 	    sess != NULL;
821 	    sess = AVL_NEXT(&iscsit_global.global_discovery_sessions, sess))
822 		iscsit_sess_close(sess);
823 
824 	/*
825 	 * Passing NULL to iscsit_config_merge tells it to go to an empty
826 	 * config.
827 	 */
828 	(void) iscsit_config_merge(NULL);
829 
830 	/*
831 	 * Wait until there are no more global references
832 	 */
833 	idm_refcnt_wait_ref(&iscsit_global.global_refcnt);
834 	idm_refcnt_destroy(&iscsit_global.global_refcnt);
835 
836 	/*
837 	 * Default TPG must be destroyed after global_refcnt is 0.
838 	 */
839 	iscsit_tpg_destroydefault(iscsit_global.global_default_tpg);
840 
841 	avl_destroy(&iscsit_global.global_discovery_sessions);
842 	list_destroy(&iscsit_global.global_deleted_target_list);
843 	avl_destroy(&iscsit_global.global_target_list);
844 	avl_destroy(&iscsit_global.global_tpg_list);
845 	avl_destroy(&iscsit_global.global_ini_list);
846 
847 	taskq_destroy(iscsit_global.global_dispatch_taskq);
848 
849 	iscsit_isns_fini();
850 
851 	stmf_free(iscsit_global.global_dbuf_store);
852 	iscsit_global.global_dbuf_store = NULL;
853 
854 	(void) stmf_deregister_port_provider(iscsit_global.global_pp);
855 	stmf_free(iscsit_global.global_pp);
856 	iscsit_global.global_pp = NULL;
857 
858 	kmem_cache_destroy(iscsit_status_pdu_cache);
859 	iscsit_status_pdu_cache = NULL;
860 
861 	vmem_destroy(iscsit_global.global_tsih_pool);
862 	iscsit_global.global_tsih_pool = NULL;
863 }
864 
865 void
866 iscsit_global_hold()
867 {
868 	/*
869 	 * To take out a global hold, we must either own the global
870 	 * state mutex or we must be running inside of an ioctl that
871 	 * has set the global state to ISE_BUSY, ISE_DISABLING, or
872 	 * ISE_ENABLING.  We don't track the "owner" for these flags,
873 	 * so just checking if they are set is enough for now.
874 	 */
875 	ASSERT((iscsit_global.global_svc_state == ISE_ENABLING) ||
876 	    (iscsit_global.global_svc_state == ISE_DISABLING) ||
877 	    (iscsit_global.global_svc_state == ISE_BUSY) ||
878 	    MUTEX_HELD(&iscsit_global.global_state_mutex));
879 
880 	idm_refcnt_hold(&iscsit_global.global_refcnt);
881 }
882 
883 void
884 iscsit_global_rele()
885 {
886 	idm_refcnt_rele(&iscsit_global.global_refcnt);
887 }
888 
889 void
890 iscsit_global_wait_ref()
891 {
892 	idm_refcnt_wait_ref(&iscsit_global.global_refcnt);
893 }
894 
895 /*
896  * IDM callbacks
897  */
898 
899 /*ARGSUSED*/
900 void
901 iscsit_rx_pdu(idm_conn_t *ic, idm_pdu_t *rx_pdu)
902 {
903 	iscsit_conn_t *ict = ic->ic_handle;
904 	switch (IDM_PDU_OPCODE(rx_pdu)) {
905 	case ISCSI_OP_SCSI_CMD:
906 		ASSERT(0); /* Shouldn't happen */
907 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
908 		break;
909 	case ISCSI_OP_SNACK_CMD:
910 		/*
911 		 * We'll need to handle this when we support ERL1/2.  For
912 		 * now we treat it as a protocol error.
913 		 */
914 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
915 		idm_conn_event(ic, CE_TRANSPORT_FAIL, NULL);
916 		break;
917 	case ISCSI_OP_SCSI_TASK_MGT_MSG:
918 		if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
919 			iscsit_set_cmdsn(ict, rx_pdu);
920 			iscsit_op_scsi_task_mgmt(ict, rx_pdu);
921 		}
922 		break;
923 	case ISCSI_OP_NOOP_OUT:
924 	case ISCSI_OP_LOGIN_CMD:
925 	case ISCSI_OP_TEXT_CMD:
926 	case ISCSI_OP_LOGOUT_CMD:
927 		/*
928 		 * If/when we switch to userland processing these PDU's
929 		 * will be handled by iscsitd.
930 		 */
931 		iscsit_deferred_dispatch(rx_pdu);
932 		break;
933 	default:
934 		/* Protocol error */
935 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
936 		idm_conn_event(ic, CE_TRANSPORT_FAIL, NULL);
937 		break;
938 	}
939 }
940 
941 /*ARGSUSED*/
942 void
943 iscsit_rx_pdu_error(idm_conn_t *ic, idm_pdu_t *rx_pdu, idm_status_t status)
944 {
945 	idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
946 }
947 
948 void
949 iscsit_task_aborted(idm_task_t *idt, idm_status_t status)
950 {
951 	iscsit_task_t *itask = idt->idt_private;
952 
953 	switch (status) {
954 	case IDM_STATUS_SUSPENDED:
955 		break;
956 	case IDM_STATUS_ABORTED:
957 		mutex_enter(&itask->it_mutex);
958 		itask->it_aborted = B_TRUE;
959 		/*
960 		 * We rely on the fact that STMF tracks outstanding
961 		 * buffer transfers and will free all of our buffers
962 		 * before freeing the task so we don't need to
963 		 * explicitly free the buffers from iscsit/idm
964 		 */
965 		if (itask->it_stmf_abort) {
966 			mutex_exit(&itask->it_mutex);
967 			/*
968 			 * Task is no longer active
969 			 */
970 			iscsit_task_done(itask);
971 
972 			/*
973 			 * STMF has already asked for this task to be aborted
974 			 *
975 			 * STMF specification is wrong... says to return
976 			 * STMF_ABORTED, the code actually looks for
977 			 * STMF_ABORT_SUCCESS.
978 			 */
979 			stmf_task_lport_aborted(itask->it_stmf_task,
980 			    STMF_ABORT_SUCCESS, STMF_IOF_LPORT_DONE);
981 			return;
982 		} else {
983 			mutex_exit(&itask->it_mutex);
984 			/*
985 			 * Tell STMF to stop processing the task.
986 			 */
987 			stmf_abort(STMF_QUEUE_TASK_ABORT, itask->it_stmf_task,
988 			    STMF_ABORTED, NULL);
989 			return;
990 		}
991 		/*NOTREACHED*/
992 	default:
993 		ASSERT(0);
994 	}
995 }
996 
997 /*ARGSUSED*/
998 idm_status_t
999 iscsit_client_notify(idm_conn_t *ic, idm_client_notify_t icn,
1000     uintptr_t data)
1001 {
1002 	idm_status_t rc = IDM_STATUS_SUCCESS;
1003 
1004 	/*
1005 	 * IDM client notifications will never occur at interrupt level
1006 	 * since they are generated from the connection state machine which
1007 	 * running on taskq threads.
1008 	 *
1009 	 */
1010 	switch (icn) {
1011 	case CN_CONNECT_ACCEPT:
1012 		rc = iscsit_conn_accept(ic); /* No data */
1013 		break;
1014 	case CN_FFP_ENABLED:
1015 		rc = iscsit_ffp_enabled(ic); /* No data */
1016 		break;
1017 	case CN_FFP_DISABLED:
1018 		/*
1019 		 * Data indicates whether this was the result of an
1020 		 * explicit logout request.
1021 		 */
1022 		rc = iscsit_ffp_disabled(ic, (idm_ffp_disable_t)data);
1023 		break;
1024 	case CN_CONNECT_LOST:
1025 		rc = iscsit_conn_lost(ic);
1026 		break;
1027 	case CN_CONNECT_DESTROY:
1028 		rc = iscsit_conn_destroy(ic);
1029 		break;
1030 	case CN_LOGIN_FAIL:
1031 		/*
1032 		 * Force the login state machine to completion
1033 		 */
1034 		rc = iscsit_login_fail(ic);
1035 		break;
1036 	default:
1037 		rc = IDM_STATUS_REJECT;
1038 		break;
1039 	}
1040 
1041 	return (rc);
1042 }
1043 
1044 /*
1045  * iscsit_update_statsn is invoked for all the PDUs which have the StatSN
1046  * field in the header. The StatSN is incremented if the IDM_PDU_ADVANCE_STATSN
1047  * flag is set in the pdu flags field. The StatSN is connection-wide and is
1048  * protected by the mutex ict_statsn_mutex. For Data-In PDUs, if the flag
1049  * IDM_TASK_PHASECOLLAPSE_REQ is set, the status (phase-collapse) is also filled
1050  */
1051 void
1052 iscsit_update_statsn(idm_task_t *idm_task, idm_pdu_t *pdu)
1053 {
1054 	iscsi_scsi_rsp_hdr_t *rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
1055 	iscsit_conn_t *ict = (iscsit_conn_t *)pdu->isp_ic->ic_handle;
1056 	iscsit_task_t *itask = NULL;
1057 	scsi_task_t *task = NULL;
1058 
1059 	mutex_enter(&ict->ict_statsn_mutex);
1060 	rsp->statsn = htonl(ict->ict_statsn);
1061 	if (pdu->isp_flags & IDM_PDU_ADVANCE_STATSN)
1062 		ict->ict_statsn++;
1063 	mutex_exit(&ict->ict_statsn_mutex);
1064 
1065 	/*
1066 	 * The last SCSI Data PDU passed for a command may also contain the
1067 	 * status if the status indicates termination with no expections, i.e.
1068 	 * no sense data or response involved. If the command completes with
1069 	 * an error, then the response and sense data will be sent in a
1070 	 * separate iSCSI Response PDU.
1071 	 */
1072 	if ((idm_task) && (idm_task->idt_flags & IDM_TASK_PHASECOLLAPSE_REQ)) {
1073 		itask = idm_task->idt_private;
1074 		task = itask->it_stmf_task;
1075 
1076 		rsp->cmd_status = task->task_scsi_status;
1077 		rsp->flags	|= ISCSI_FLAG_DATA_STATUS;
1078 		if (task->task_status_ctrl & TASK_SCTRL_OVER) {
1079 			rsp->flags |= ISCSI_FLAG_CMD_OVERFLOW;
1080 		} else if (task->task_status_ctrl & TASK_SCTRL_UNDER) {
1081 			rsp->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
1082 		}
1083 		rsp->residual_count = htonl(task->task_resid);
1084 
1085 		/*
1086 		 * Removing the task from the session task list
1087 		 * just before the status is sent in the last
1088 		 * Data PDU transfer
1089 		 */
1090 		iscsit_task_done(itask);
1091 	}
1092 }
1093 
1094 void
1095 iscsit_build_hdr(idm_task_t *idm_task, idm_pdu_t *pdu, uint8_t opcode)
1096 {
1097 	iscsit_task_t *itask = idm_task->idt_private;
1098 	iscsi_data_rsp_hdr_t *dh = (iscsi_data_rsp_hdr_t *)pdu->isp_hdr;
1099 
1100 	/*
1101 	 * We acquired iscsit_sess_t.ist_sn_mutex in iscsit_xfer_scsi_data
1102 	 */
1103 	ASSERT(MUTEX_HELD(&itask->it_ict->ict_sess->ist_sn_mutex));
1104 	/*
1105 	 * On incoming data, the target transfer tag and Lun is only
1106 	 * provided by the target if the A bit is set, Since the target
1107 	 * does not currently support Error Recovery Level 1, the A
1108 	 * bit is never set.
1109 	 */
1110 	dh->opcode = opcode;
1111 	dh->itt = itask->it_itt;
1112 	dh->ttt = ((opcode & ISCSI_OPCODE_MASK) == ISCSI_OP_SCSI_DATA_RSP) ?
1113 	    ISCSI_RSVD_TASK_TAG : itask->it_ttt;
1114 
1115 	dh->expcmdsn = htonl(itask->it_ict->ict_sess->ist_expcmdsn);
1116 	dh->maxcmdsn = htonl(itask->it_ict->ict_sess->ist_maxcmdsn);
1117 
1118 	/*
1119 	 * IDM must set:
1120 	 *
1121 	 * data.flags and rtt.flags
1122 	 * data.dlength
1123 	 * data.datasn
1124 	 * data.offset
1125 	 * statsn, residual_count and cmd_status (for phase collapse)
1126 	 * rtt.rttsn
1127 	 * rtt.data_offset
1128 	 * rtt.data_length
1129 	 */
1130 }
1131 
1132 void
1133 iscsit_keepalive(idm_conn_t *ic)
1134 {
1135 	idm_pdu_t		*nop_in_pdu;
1136 	iscsi_nop_in_hdr_t	*nop_in;
1137 	iscsit_conn_t		*ict = ic->ic_handle;
1138 
1139 	/*
1140 	 * IDM noticed the connection has been idle for too long so it's
1141 	 * time to provoke some activity.  Build and transmit an iSCSI
1142 	 * nop-in PDU -- when the initiator responds it will be counted
1143 	 * as "activity" and keep the connection alive.
1144 	 *
1145 	 * We don't actually care about the response here at the iscsit level
1146 	 * so we will just throw it away without looking at it when it arrives.
1147 	 */
1148 	nop_in_pdu = idm_pdu_alloc(sizeof (*nop_in), 0);
1149 	idm_pdu_init(nop_in_pdu, ic, NULL, NULL);
1150 	nop_in = (iscsi_nop_in_hdr_t *)nop_in_pdu->isp_hdr;
1151 	bzero(nop_in, sizeof (*nop_in));
1152 	nop_in->opcode = ISCSI_OP_NOOP_IN;
1153 	nop_in->flags = ISCSI_FLAG_FINAL;
1154 	nop_in->itt = ISCSI_RSVD_TASK_TAG;
1155 	/*
1156 	 * When the target sends a NOP-In as a Ping, the target transfer tag
1157 	 * is set to a valid (not reserved) value and the initiator task tag
1158 	 * is set to ISCSI_RSVD_TASK_TAG (0xffffffff). In this case the StatSN
1159 	 * will always contain the next sequence number but the StatSN for the
1160 	 * connection is not advanced after this PDU is sent.
1161 	 */
1162 	nop_in_pdu->isp_flags |= IDM_PDU_SET_STATSN;
1163 	/*
1164 	 * This works because we don't currently allocate ttt's anywhere else
1165 	 * in iscsit so as long as we stay out of IDM's range we are safe.
1166 	 * If we need to allocate ttt's for other PDU's in the future this will
1167 	 * need to be improved.
1168 	 */
1169 	mutex_enter(&ict->ict_mutex);
1170 	nop_in->ttt = ict->ict_keepalive_ttt;
1171 	ict->ict_keepalive_ttt++;
1172 	if (ict->ict_keepalive_ttt == ISCSI_RSVD_TASK_TAG)
1173 		ict->ict_keepalive_ttt = IDM_TASKIDS_MAX;
1174 	mutex_exit(&ict->ict_mutex);
1175 
1176 	iscsit_pdu_tx(nop_in_pdu);
1177 }
1178 
1179 static idm_status_t
1180 iscsit_conn_accept(idm_conn_t *ic)
1181 {
1182 	iscsit_conn_t *ict;
1183 
1184 	/*
1185 	 * We need to get a global hold here to ensure that the service
1186 	 * doesn't get shutdown prior to establishing a session. This
1187 	 * gets released in iscsit_conn_destroy().
1188 	 */
1189 	mutex_enter(&iscsit_global.global_state_mutex);
1190 	if (iscsit_global.global_svc_state != ISE_ENABLED) {
1191 		mutex_exit(&iscsit_global.global_state_mutex);
1192 		return (IDM_STATUS_FAIL);
1193 	}
1194 	iscsit_global_hold();
1195 	mutex_exit(&iscsit_global.global_state_mutex);
1196 
1197 	/*
1198 	 * Allocate an associated iscsit structure to represent this
1199 	 * connection.  We shouldn't really create a session until we
1200 	 * get the first login PDU.
1201 	 */
1202 	ict = kmem_zalloc(sizeof (*ict), KM_SLEEP);
1203 
1204 	ict->ict_ic = ic;
1205 	ict->ict_statsn = 1;
1206 	ict->ict_keepalive_ttt = IDM_TASKIDS_MAX; /* Avoid IDM TT range */
1207 	ic->ic_handle = ict;
1208 	mutex_init(&ict->ict_mutex, NULL, MUTEX_DRIVER, NULL);
1209 	mutex_init(&ict->ict_statsn_mutex, NULL, MUTEX_DRIVER, NULL);
1210 	idm_refcnt_init(&ict->ict_refcnt, ict);
1211 
1212 	/*
1213 	 * Initialize login state machine
1214 	 */
1215 	if (iscsit_login_sm_init(ict) != IDM_STATUS_SUCCESS) {
1216 		iscsit_global_rele();
1217 		/*
1218 		 * Cleanup the ict after idm notifies us about this failure
1219 		 */
1220 		return (IDM_STATUS_FAIL);
1221 	}
1222 
1223 	return (IDM_STATUS_SUCCESS);
1224 }
1225 
1226 idm_status_t
1227 iscsit_conn_reinstate(iscsit_conn_t *reinstate_ict, iscsit_conn_t *new_ict)
1228 {
1229 	idm_status_t	result;
1230 
1231 	/*
1232 	 * Note in new connection state that this connection is
1233 	 * reinstating an existing connection.
1234 	 */
1235 	new_ict->ict_reinstating = B_TRUE;
1236 	new_ict->ict_reinstate_conn = reinstate_ict;
1237 	new_ict->ict_statsn = reinstate_ict->ict_statsn;
1238 
1239 	/*
1240 	 * Now generate connection state machine event to existing connection
1241 	 * so that it starts the cleanup process.
1242 	 */
1243 	result = idm_conn_reinstate_event(reinstate_ict->ict_ic,
1244 	    new_ict->ict_ic);
1245 
1246 	return (result);
1247 }
1248 
1249 void
1250 iscsit_conn_hold(iscsit_conn_t *ict)
1251 {
1252 	idm_refcnt_hold(&ict->ict_refcnt);
1253 }
1254 
1255 void
1256 iscsit_conn_rele(iscsit_conn_t *ict)
1257 {
1258 	idm_refcnt_rele(&ict->ict_refcnt);
1259 }
1260 
1261 void
1262 iscsit_conn_dispatch_hold(iscsit_conn_t *ict)
1263 {
1264 	idm_refcnt_hold(&ict->ict_dispatch_refcnt);
1265 }
1266 
1267 void
1268 iscsit_conn_dispatch_rele(iscsit_conn_t *ict)
1269 {
1270 	idm_refcnt_rele(&ict->ict_dispatch_refcnt);
1271 }
1272 
1273 static idm_status_t
1274 iscsit_login_fail(idm_conn_t *ic)
1275 {
1276 	iscsit_conn_t *ict = ic->ic_handle;
1277 
1278 	/* Generate login state machine event */
1279 	iscsit_login_sm_event(ict, ILE_LOGIN_CONN_ERROR, NULL);
1280 
1281 	return (IDM_STATUS_SUCCESS);
1282 }
1283 
1284 static idm_status_t
1285 iscsit_ffp_enabled(idm_conn_t *ic)
1286 {
1287 	iscsit_conn_t *ict = ic->ic_handle;
1288 
1289 	/* Generate session state machine event */
1290 	iscsit_sess_sm_event(ict->ict_sess, SE_CONN_LOGGED_IN, ict);
1291 
1292 	return (IDM_STATUS_SUCCESS);
1293 }
1294 
1295 static idm_status_t
1296 iscsit_ffp_disabled(idm_conn_t *ic, idm_ffp_disable_t disable_class)
1297 {
1298 	iscsit_conn_t *ict = ic->ic_handle;
1299 
1300 	/* Generate session state machine event */
1301 	switch (disable_class) {
1302 	case FD_CONN_FAIL:
1303 		iscsit_sess_sm_event(ict->ict_sess, SE_CONN_FFP_FAIL, ict);
1304 		break;
1305 	case FD_CONN_LOGOUT:
1306 		iscsit_sess_sm_event(ict->ict_sess, SE_CONN_FFP_DISABLE, ict);
1307 		break;
1308 	case FD_SESS_LOGOUT:
1309 		iscsit_sess_sm_event(ict->ict_sess, SE_SESSION_CLOSE, ict);
1310 		break;
1311 	default:
1312 		ASSERT(0);
1313 	}
1314 
1315 	return (IDM_STATUS_SUCCESS);
1316 }
1317 
1318 static idm_status_t
1319 iscsit_conn_lost(idm_conn_t *ic)
1320 {
1321 	iscsit_conn_t	*ict	= ic->ic_handle;
1322 	iscsit_sess_t	*ist	= ict->ict_sess;
1323 	iscsit_cbuf_t	*cbuf;
1324 	idm_pdu_t	*rx_pdu;
1325 	int i;
1326 
1327 	mutex_enter(&ict->ict_mutex);
1328 	ict->ict_lost = B_TRUE;
1329 	mutex_exit(&ict->ict_mutex);
1330 	/*
1331 	 * scrub the staging queue for all PDUs on this connection
1332 	 */
1333 	if (ist != NULL) {
1334 		mutex_enter(&ist->ist_sn_mutex);
1335 		for (cbuf = ist->ist_rxpdu_queue, i = 0;
1336 		    ((cbuf->cb_num_elems > 0) && (i < ISCSIT_RXPDU_QUEUE_LEN));
1337 		    i++) {
1338 			if (((rx_pdu = cbuf->cb_buffer[i]) != NULL) &&
1339 			    (rx_pdu->isp_ic == ic)) {
1340 				/* conn is lost, drop the pdu */
1341 				DTRACE_PROBE3(scrubbing__staging__queue,
1342 				    iscsit_sess_t *, ist, idm_conn_t *, ic,
1343 				    idm_pdu_t *, rx_pdu);
1344 				idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
1345 				cbuf->cb_buffer[i] = NULL;
1346 				cbuf->cb_num_elems--;
1347 				iscsit_conn_dispatch_rele(ict);
1348 			}
1349 		}
1350 		mutex_exit(&ist->ist_sn_mutex);
1351 	}
1352 	/*
1353 	 * Make sure there aren't any PDU's transitioning from the receive
1354 	 * handler to the dispatch taskq.
1355 	 */
1356 	idm_refcnt_wait_ref(&ict->ict_dispatch_refcnt);
1357 
1358 	return (IDM_STATUS_SUCCESS);
1359 }
1360 
1361 static idm_status_t
1362 iscsit_conn_destroy(idm_conn_t *ic)
1363 {
1364 	iscsit_conn_t *ict = ic->ic_handle;
1365 
1366 	mutex_enter(&ict->ict_mutex);
1367 	ict->ict_destroyed = B_TRUE;
1368 	mutex_exit(&ict->ict_mutex);
1369 
1370 	/* Generate session state machine event */
1371 	if (ict->ict_sess != NULL) {
1372 		/*
1373 		 * Session state machine will call iscsit_conn_destroy_done()
1374 		 * when it has removed references to this connection.
1375 		 */
1376 		iscsit_sess_sm_event(ict->ict_sess, SE_CONN_FAIL, ict);
1377 	}
1378 
1379 	idm_refcnt_wait_ref(&ict->ict_refcnt);
1380 	/*
1381 	 * The session state machine does not need to post
1382 	 * events to IDM any longer, so it is safe to set
1383 	 * the idm connection reference to NULL
1384 	 */
1385 	ict->ict_ic = NULL;
1386 
1387 	/* Reap the login state machine */
1388 	iscsit_login_sm_fini(ict);
1389 
1390 	/* Clean up any text command remnants */
1391 	iscsit_text_cmd_fini(ict);
1392 
1393 	mutex_destroy(&ict->ict_mutex);
1394 	idm_refcnt_destroy(&ict->ict_refcnt);
1395 	kmem_free(ict, sizeof (*ict));
1396 
1397 	iscsit_global_rele();
1398 
1399 	return (IDM_STATUS_SUCCESS);
1400 }
1401 
1402 void
1403 iscsit_conn_logout(iscsit_conn_t *ict)
1404 {
1405 	/*
1406 	 * If the iscsi connection is active, then
1407 	 * logout the IDM connection by sending a
1408 	 * CE_LOGOUT_SESSION_SUCCESS, else, no action
1409 	 * needs to be taken because the connection
1410 	 * is already in the teardown process.
1411 	 */
1412 	mutex_enter(&ict->ict_mutex);
1413 	if (ict->ict_lost == B_FALSE && ict->ict_destroyed == B_FALSE) {
1414 		idm_conn_event(ict->ict_ic, CE_LOGOUT_SESSION_SUCCESS, NULL);
1415 	}
1416 	mutex_exit(&ict->ict_mutex);
1417 }
1418 
1419 /*
1420  * STMF-related functions
1421  *
1422  * iSCSI to STMF mapping
1423  *
1424  * Session == ?
1425  * Connection == bound to local port but not itself a local port
1426  * Target
1427  * Target portal (group?) == local port (really but we're not going to do this)
1428  *	iscsit needs to map connections to local ports (whatever we decide
1429  * 	they are)
1430  * Target == ?
1431  */
1432 
1433 /*ARGSUSED*/
1434 static stmf_data_buf_t *
1435 iscsit_dbuf_alloc(scsi_task_t *task, uint32_t size, uint32_t *pminsize,
1436     uint32_t flags)
1437 {
1438 	iscsit_task_t *itask = task->task_port_private;
1439 	idm_buf_t *idm_buffer;
1440 	iscsit_buf_t	*ibuf;
1441 	stmf_data_buf_t *result;
1442 	uint32_t	bsize;
1443 
1444 	/*
1445 	 * If the requested size is larger than MaxBurstLength and the
1446 	 * given pminsize is also larger than MaxBurstLength, then the
1447 	 * allocation fails (dbuf = NULL) and pminsize is modified to
1448 	 * be equal to MaxBurstLength. stmf/sbd then should re-invoke
1449 	 * this function with the corrected values for transfer.
1450 	 */
1451 	ASSERT(pminsize);
1452 	if (size <= itask->it_ict->ict_op.op_max_burst_length) {
1453 		bsize = size;
1454 	} else if (*pminsize <= itask->it_ict->ict_op.op_max_burst_length) {
1455 		bsize = itask->it_ict->ict_op.op_max_burst_length;
1456 	} else {
1457 		*pminsize = itask->it_ict->ict_op.op_max_burst_length;
1458 		return (NULL);
1459 	}
1460 
1461 	/* Alloc buffer */
1462 	idm_buffer = idm_buf_alloc(itask->it_ict->ict_ic, NULL, bsize);
1463 	if (idm_buffer != NULL) {
1464 		result = stmf_alloc(STMF_STRUCT_DATA_BUF,
1465 		    sizeof (iscsit_buf_t), 0);
1466 		if (result != NULL) {
1467 			/* Fill in stmf_data_buf_t */
1468 			ibuf = result->db_port_private;
1469 			ibuf->ibuf_idm_buf = idm_buffer;
1470 			ibuf->ibuf_stmf_buf = result;
1471 			ibuf->ibuf_is_immed = B_FALSE;
1472 			result->db_flags = DB_DONT_CACHE;
1473 			result->db_buf_size = bsize;
1474 			result->db_data_size = bsize;
1475 			result->db_sglist_length = 1;
1476 			result->db_sglist[0].seg_addr = idm_buffer->idb_buf;
1477 			result->db_sglist[0].seg_length =
1478 			    idm_buffer->idb_buflen;
1479 			return (result);
1480 		}
1481 
1482 		/* Couldn't get the stmf_data_buf_t so free the buffer */
1483 		idm_buf_free(idm_buffer);
1484 	}
1485 
1486 	return (NULL);
1487 }
1488 
1489 /*ARGSUSED*/
1490 static void
1491 iscsit_dbuf_free(stmf_dbuf_store_t *ds, stmf_data_buf_t *dbuf)
1492 {
1493 	iscsit_buf_t *ibuf = dbuf->db_port_private;
1494 
1495 	if (ibuf->ibuf_is_immed) {
1496 		/*
1497 		 * The iscsit_buf_t structure itself will be freed with its
1498 		 * associated task.  Here we just need to free the PDU that
1499 		 * held the immediate data.
1500 		 */
1501 		idm_pdu_complete(ibuf->ibuf_immed_data_pdu, IDM_STATUS_SUCCESS);
1502 		ibuf->ibuf_immed_data_pdu = 0;
1503 	} else {
1504 		idm_buf_free(ibuf->ibuf_idm_buf);
1505 		stmf_free(dbuf);
1506 	}
1507 }
1508 
1509 /*ARGSUSED*/
1510 stmf_status_t
1511 iscsit_xfer_scsi_data(scsi_task_t *task, stmf_data_buf_t *dbuf,
1512     uint32_t ioflags)
1513 {
1514 	iscsit_task_t *iscsit_task = task->task_port_private;
1515 	iscsit_sess_t *ict_sess = iscsit_task->it_ict->ict_sess;
1516 	iscsit_buf_t *ibuf = dbuf->db_port_private;
1517 	int idm_rc;
1518 
1519 	/*
1520 	 * If we are aborting then we can ignore this request
1521 	 */
1522 	if (iscsit_task->it_stmf_abort) {
1523 		return (STMF_SUCCESS);
1524 	}
1525 
1526 	/*
1527 	 * If it's not immediate data then start the transfer
1528 	 */
1529 	ASSERT(ibuf->ibuf_is_immed == B_FALSE);
1530 	if (dbuf->db_flags & DB_DIRECTION_TO_RPORT) {
1531 		/*
1532 		 * The DB_SEND_STATUS_GOOD flag in the STMF data buffer allows
1533 		 * the port provider to phase-collapse, i.e. send the status
1534 		 * along with the final data PDU for the command. The port
1535 		 * provider passes this request to the transport layer by
1536 		 * setting a flag IDM_TASK_PHASECOLLAPSE_REQ in the task.
1537 		 */
1538 		if (dbuf->db_flags & DB_SEND_STATUS_GOOD)
1539 			iscsit_task->it_idm_task->idt_flags |=
1540 			    IDM_TASK_PHASECOLLAPSE_REQ;
1541 		/*
1542 		 * IDM will call iscsit_build_hdr so lock now to serialize
1543 		 * access to the SN values.  We need to lock here to enforce
1544 		 * lock ordering
1545 		 */
1546 		mutex_enter(&ict_sess->ist_sn_mutex);
1547 		idm_rc = idm_buf_tx_to_ini(iscsit_task->it_idm_task,
1548 		    ibuf->ibuf_idm_buf, dbuf->db_relative_offset,
1549 		    dbuf->db_data_size, &iscsit_buf_xfer_cb, dbuf);
1550 		mutex_exit(&ict_sess->ist_sn_mutex);
1551 
1552 		return (iscsit_idm_to_stmf(idm_rc));
1553 	} else if (dbuf->db_flags & DB_DIRECTION_FROM_RPORT) {
1554 		/* Grab the SN lock (see comment above) */
1555 		mutex_enter(&ict_sess->ist_sn_mutex);
1556 		idm_rc = idm_buf_rx_from_ini(iscsit_task->it_idm_task,
1557 		    ibuf->ibuf_idm_buf, dbuf->db_relative_offset,
1558 		    dbuf->db_data_size, &iscsit_buf_xfer_cb, dbuf);
1559 		mutex_exit(&ict_sess->ist_sn_mutex);
1560 
1561 		return (iscsit_idm_to_stmf(idm_rc));
1562 	}
1563 
1564 	/* What are we supposed to do if there is no direction? */
1565 	return (STMF_INVALID_ARG);
1566 }
1567 
1568 static void
1569 iscsit_buf_xfer_cb(idm_buf_t *idb, idm_status_t status)
1570 {
1571 	iscsit_task_t *itask = idb->idb_task_binding->idt_private;
1572 	stmf_data_buf_t *dbuf = idb->idb_cb_arg;
1573 
1574 	dbuf->db_xfer_status = iscsit_idm_to_stmf(status);
1575 
1576 	/*
1577 	 * If the task has been aborted then we don't need to call STMF
1578 	 */
1579 	if (itask->it_stmf_abort) {
1580 		return;
1581 	}
1582 
1583 	/*
1584 	 * For ISCSI over TCP (not iSER), the last SCSI Data PDU passed
1585 	 * for a successful command contains the status as requested by
1586 	 * by COMSTAR (via the DB_SEND_STATUS_GOOD flag). But the iSER
1587 	 * transport does not support phase-collapse. So pretend we are
1588 	 * COMSTAR and send the status in a separate PDU now.
1589 	 */
1590 	if (idb->idb_task_binding->idt_flags & IDM_TASK_PHASECOLLAPSE_SUCCESS) {
1591 		/*
1592 		 * Mark task complete and notify COMSTAR
1593 		 * that the status has been sent.
1594 		 */
1595 		itask->it_idm_task->idt_state = TASK_COMPLETE;
1596 		stmf_send_status_done(itask->it_stmf_task,
1597 		    iscsit_idm_to_stmf(status), STMF_IOF_LPORT_DONE);
1598 	} else if ((dbuf->db_flags & DB_SEND_STATUS_GOOD) &&
1599 	    status == IDM_STATUS_SUCCESS) {
1600 
1601 		/*
1602 		 * The iscsi target port provider - for iSER, emulates the
1603 		 * DB_SEND_STATUS_GOOD optimization if requested by STMF;
1604 		 * it sends the status in a separate PDU after the data
1605 		 * transfer. In this case the port provider should first
1606 		 * call stmf_data_xfer_done() to mark the transfer complete
1607 		 * and then send the status. Although STMF will free the
1608 		 * buffer at the time the task is freed, even if the transfer
1609 		 * is not marked complete, this behavior makes statistics
1610 		 * gathering and task state tracking more difficult than it
1611 		 * needs to be.
1612 		 */
1613 		stmf_data_xfer_done(itask->it_stmf_task, dbuf, 0);
1614 		if (iscsit_send_scsi_status(itask->it_stmf_task, 0)
1615 		    != STMF_SUCCESS) {
1616 			stmf_send_status_done(itask->it_stmf_task,
1617 			    STMF_FAILURE, STMF_IOF_LPORT_DONE);
1618 		}
1619 	} else {
1620 		stmf_data_xfer_done(itask->it_stmf_task, dbuf, 0);
1621 		/* don't touch dbuf after stmf_data_xfer_done */
1622 	}
1623 }
1624 
1625 
1626 /*ARGSUSED*/
1627 stmf_status_t
1628 iscsit_send_scsi_status(scsi_task_t *task, uint32_t ioflags)
1629 {
1630 	iscsit_task_t *itask = task->task_port_private;
1631 	iscsi_scsi_rsp_hdr_t *rsp;
1632 	idm_pdu_t *pdu;
1633 	int resp_datalen;
1634 
1635 	/*
1636 	 * If this task is aborted then we don't need to respond.
1637 	 */
1638 	if (itask->it_stmf_abort) {
1639 		return (STMF_SUCCESS);
1640 	}
1641 
1642 	/*
1643 	 * If this is a task management status, handle it elsewhere.
1644 	 */
1645 	if (task->task_mgmt_function != TM_NONE) {
1646 		/*
1647 		 * Don't wait for the PDU completion to tell STMF
1648 		 * the task is done -- it doesn't really matter and
1649 		 * it makes life complicated if STMF later asks us to
1650 		 * abort the request and we don't know whether the
1651 		 * status has been sent or not.
1652 		 */
1653 		itask->it_tm_responded = B_TRUE;
1654 		iscsit_send_task_mgmt_resp(itask->it_tm_pdu,
1655 		    (task->task_completion_status == STMF_SUCCESS) ?
1656 		    SCSI_TCP_TM_RESP_COMPLETE : SCSI_TCP_TM_RESP_FUNC_NOT_SUPP);
1657 		stmf_send_status_done(task, STMF_SUCCESS,
1658 		    STMF_IOF_LPORT_DONE);
1659 		return (STMF_SUCCESS);
1660 	}
1661 
1662 	/*
1663 	 * Remove the task from the session task list
1664 	 */
1665 	iscsit_task_done(itask);
1666 
1667 	/*
1668 	 * Send status
1669 	 */
1670 	mutex_enter(&itask->it_idm_task->idt_mutex);
1671 	if ((itask->it_idm_task->idt_state == TASK_ACTIVE) &&
1672 	    (task->task_completion_status == STMF_SUCCESS) &&
1673 	    (task->task_sense_length == 0) &&
1674 	    (task->task_resid == 0)) {
1675 		itask->it_idm_task->idt_state = TASK_COMPLETE;
1676 		/* PDU callback releases task hold */
1677 		idm_task_hold(itask->it_idm_task);
1678 		mutex_exit(&itask->it_idm_task->idt_mutex);
1679 		/*
1680 		 * Fast path.  Cached status PDU's are already
1681 		 * initialized.  We just need to fill in
1682 		 * connection and task information. StatSN is
1683 		 * incremented by 1 for every status sent a
1684 		 * connection.
1685 		 */
1686 		pdu = kmem_cache_alloc(iscsit_status_pdu_cache, KM_SLEEP);
1687 		pdu->isp_ic = itask->it_ict->ict_ic;
1688 		pdu->isp_private = itask;
1689 		pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
1690 
1691 		rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
1692 		rsp->itt = itask->it_itt;
1693 		/*
1694 		 * ExpDataSN is the number of R2T and Data-In (read)
1695 		 * PDUs the target has sent for the SCSI command.
1696 		 *
1697 		 * Since there is no support for bidirectional transfer
1698 		 * yet, either idt_exp_datasn or idt_exp_rttsn, but not
1699 		 * both is valid at any time
1700 		 */
1701 		rsp->expdatasn = (itask->it_idm_task->idt_exp_datasn != 0) ?
1702 		    htonl(itask->it_idm_task->idt_exp_datasn):
1703 		    htonl(itask->it_idm_task->idt_exp_rttsn);
1704 		rsp->cmd_status = task->task_scsi_status;
1705 		iscsit_pdu_tx(pdu);
1706 		return (STMF_SUCCESS);
1707 	} else {
1708 		if (itask->it_idm_task->idt_state != TASK_ACTIVE) {
1709 			mutex_exit(&itask->it_idm_task->idt_mutex);
1710 			return (STMF_FAILURE);
1711 		}
1712 		itask->it_idm_task->idt_state = TASK_COMPLETE;
1713 		/* PDU callback releases task hold */
1714 		idm_task_hold(itask->it_idm_task);
1715 		mutex_exit(&itask->it_idm_task->idt_mutex);
1716 
1717 		resp_datalen = (task->task_sense_length == 0) ? 0 :
1718 		    (task->task_sense_length + sizeof (uint16_t));
1719 
1720 		pdu = idm_pdu_alloc(sizeof (iscsi_hdr_t), resp_datalen);
1721 		idm_pdu_init(pdu, itask->it_ict->ict_ic, itask,
1722 		    iscsit_send_status_done);
1723 		pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
1724 
1725 		rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
1726 		bzero(rsp, sizeof (*rsp));
1727 		rsp->opcode = ISCSI_OP_SCSI_RSP;
1728 
1729 		rsp->flags = ISCSI_FLAG_FINAL;
1730 		if (task->task_status_ctrl & TASK_SCTRL_OVER) {
1731 			rsp->flags |= ISCSI_FLAG_CMD_OVERFLOW;
1732 		} else if (task->task_status_ctrl & TASK_SCTRL_UNDER) {
1733 			rsp->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
1734 		}
1735 
1736 		rsp->bi_residual_count = 0;
1737 		rsp->residual_count = htonl(task->task_resid);
1738 		rsp->itt = itask->it_itt;
1739 		rsp->response = ISCSI_STATUS_CMD_COMPLETED;
1740 		rsp->expdatasn = (itask->it_idm_task->idt_exp_datasn != 0) ?
1741 		    htonl(itask->it_idm_task->idt_exp_datasn):
1742 		    htonl(itask->it_idm_task->idt_exp_rttsn);
1743 		rsp->cmd_status = task->task_scsi_status;
1744 		if (task->task_sense_length != 0) {
1745 			/*
1746 			 * Add a byte to provide the sense length in
1747 			 * the response
1748 			 */
1749 			*(uint16_t *)((void *)pdu->isp_data) =
1750 			    htons(task->task_sense_length);
1751 			bcopy(task->task_sense_data,
1752 			    (uint8_t *)pdu->isp_data +
1753 			    sizeof (uint16_t),
1754 			    task->task_sense_length);
1755 			hton24(rsp->dlength, resp_datalen);
1756 		}
1757 
1758 		DTRACE_PROBE5(iscsi__scsi__response,
1759 		    iscsit_conn_t *, itask->it_ict,
1760 		    uint8_t, rsp->response,
1761 		    uint8_t, rsp->cmd_status,
1762 		    idm_pdu_t *, pdu,
1763 		    scsi_task_t *, task);
1764 
1765 		iscsit_pdu_tx(pdu);
1766 
1767 		return (STMF_SUCCESS);
1768 	}
1769 }
1770 
1771 /*ARGSUSED*/
1772 static void
1773 iscsit_send_good_status_done(idm_pdu_t *pdu, idm_status_t status)
1774 {
1775 	iscsit_task_t	*itask;
1776 	boolean_t	aborted;
1777 
1778 	itask = pdu->isp_private;
1779 	aborted = itask->it_stmf_abort;
1780 
1781 	/*
1782 	 * After releasing the hold the task may be freed at any time so
1783 	 * don't touch it.
1784 	 */
1785 	idm_task_rele(itask->it_idm_task);
1786 	if (!aborted) {
1787 		stmf_send_status_done(itask->it_stmf_task,
1788 		    iscsit_idm_to_stmf(pdu->isp_status), STMF_IOF_LPORT_DONE);
1789 	}
1790 	kmem_cache_free(iscsit_status_pdu_cache, pdu);
1791 }
1792 
1793 /*ARGSUSED*/
1794 static void
1795 iscsit_send_status_done(idm_pdu_t *pdu, idm_status_t status)
1796 {
1797 	iscsit_task_t	 *itask;
1798 	boolean_t	aborted;
1799 
1800 	itask = pdu->isp_private;
1801 	aborted = itask->it_stmf_abort;
1802 
1803 	/*
1804 	 * After releasing the hold the task may be freed at any time so
1805 	 * don't touch it.
1806 	 */
1807 	idm_task_rele(itask->it_idm_task);
1808 	if (!aborted) {
1809 		stmf_send_status_done(itask->it_stmf_task,
1810 		    iscsit_idm_to_stmf(pdu->isp_status), STMF_IOF_LPORT_DONE);
1811 	}
1812 	idm_pdu_free(pdu);
1813 }
1814 
1815 
1816 void
1817 iscsit_lport_task_free(scsi_task_t *task)
1818 {
1819 	iscsit_task_t *itask = task->task_port_private;
1820 
1821 	/* We only call idm_task_start for regular tasks, not task management */
1822 	if (task->task_mgmt_function == TM_NONE) {
1823 		idm_task_done(itask->it_idm_task);
1824 		iscsit_task_free(itask);
1825 		return;
1826 	} else {
1827 		iscsit_tm_task_free(itask);
1828 	}
1829 }
1830 
1831 /*ARGSUSED*/
1832 stmf_status_t
1833 iscsit_abort(stmf_local_port_t *lport, int abort_cmd, void *arg, uint32_t flags)
1834 {
1835 	scsi_task_t	*st = (scsi_task_t *)arg;
1836 	iscsit_task_t	*iscsit_task;
1837 	idm_task_t	*idt;
1838 
1839 	/*
1840 	 * If this is a task management request then there's really not much to
1841 	 * do.
1842 	 */
1843 	if (st->task_mgmt_function != TM_NONE) {
1844 		return (STMF_ABORT_SUCCESS);
1845 	}
1846 
1847 	/*
1848 	 * Regular task, start cleaning up
1849 	 */
1850 	iscsit_task = st->task_port_private;
1851 	idt = iscsit_task->it_idm_task;
1852 	mutex_enter(&iscsit_task->it_mutex);
1853 	iscsit_task->it_stmf_abort = B_TRUE;
1854 	if (iscsit_task->it_aborted) {
1855 		mutex_exit(&iscsit_task->it_mutex);
1856 		/*
1857 		 * Task is no longer active
1858 		 */
1859 		iscsit_task_done(iscsit_task);
1860 
1861 		/*
1862 		 * STMF specification is wrong... says to return
1863 		 * STMF_ABORTED, the code actually looks for
1864 		 * STMF_ABORT_SUCCESS.
1865 		 */
1866 		return (STMF_ABORT_SUCCESS);
1867 	} else {
1868 		mutex_exit(&iscsit_task->it_mutex);
1869 		/*
1870 		 * Call IDM to abort the task.  Due to a variety of
1871 		 * circumstances the task may already be in the process of
1872 		 * aborting.
1873 		 * We'll let IDM worry about rationalizing all that except
1874 		 * for one particular instance.  If the state of the task
1875 		 * is TASK_COMPLETE, we need to indicate to the framework
1876 		 * that we are in fact done.  This typically happens with
1877 		 * framework-initiated task management type requests
1878 		 * (e.g. abort task).
1879 		 */
1880 		if (idt->idt_state == TASK_COMPLETE) {
1881 			idm_refcnt_wait_ref(&idt->idt_refcnt);
1882 			return (STMF_ABORT_SUCCESS);
1883 		} else {
1884 			idm_task_abort(idt->idt_ic, idt, AT_TASK_MGMT_ABORT);
1885 			return (STMF_SUCCESS);
1886 		}
1887 	}
1888 
1889 	/*NOTREACHED*/
1890 }
1891 
1892 /*ARGSUSED*/
1893 void
1894 iscsit_ctl(stmf_local_port_t *lport, int cmd, void *arg)
1895 {
1896 	iscsit_tgt_t		*iscsit_tgt;
1897 
1898 	ASSERT((cmd == STMF_CMD_LPORT_ONLINE) ||
1899 	    (cmd == STMF_ACK_LPORT_ONLINE_COMPLETE) ||
1900 	    (cmd == STMF_CMD_LPORT_OFFLINE) ||
1901 	    (cmd == STMF_ACK_LPORT_OFFLINE_COMPLETE));
1902 
1903 	iscsit_tgt = (iscsit_tgt_t *)lport->lport_port_private;
1904 
1905 	switch (cmd) {
1906 	case STMF_CMD_LPORT_ONLINE:
1907 		iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_ONLINE_REQ);
1908 		break;
1909 	case STMF_CMD_LPORT_OFFLINE:
1910 		iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_OFFLINE_REQ);
1911 		break;
1912 	case STMF_ACK_LPORT_ONLINE_COMPLETE:
1913 		iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_ONLINE_COMPLETE_ACK);
1914 		break;
1915 	case STMF_ACK_LPORT_OFFLINE_COMPLETE:
1916 		iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_OFFLINE_COMPLETE_ACK);
1917 		break;
1918 
1919 	default:
1920 		break;
1921 	}
1922 }
1923 
1924 static stmf_status_t
1925 iscsit_idm_to_stmf(idm_status_t idmrc)
1926 {
1927 	switch (idmrc) {
1928 	case IDM_STATUS_SUCCESS:
1929 		return (STMF_SUCCESS);
1930 	default:
1931 		return (STMF_FAILURE);
1932 	}
1933 	/*NOTREACHED*/
1934 }
1935 
1936 void
1937 iscsit_op_scsi_cmd(idm_conn_t *ic, idm_pdu_t *rx_pdu)
1938 {
1939 	iscsit_conn_t		*ict = ic->ic_handle;
1940 
1941 	if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
1942 		iscsit_post_scsi_cmd(ic, rx_pdu);
1943 	}
1944 	iscsit_process_pdu_in_queue(ict->ict_sess);
1945 }
1946 
1947 /*
1948  * ISCSI protocol
1949  */
1950 
1951 void
1952 iscsit_post_scsi_cmd(idm_conn_t *ic, idm_pdu_t *rx_pdu)
1953 {
1954 	iscsit_conn_t		*ict;
1955 	iscsit_task_t		*itask;
1956 	scsi_task_t		*task;
1957 	iscsit_buf_t		*ibuf;
1958 	iscsi_scsi_cmd_hdr_t	*iscsi_scsi =
1959 	    (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
1960 	iscsi_addl_hdr_t	*ahs_hdr;
1961 	uint16_t		addl_cdb_len = 0;
1962 
1963 	ict = ic->ic_handle;
1964 
1965 	itask = iscsit_task_alloc(ict);
1966 	if (itask == NULL) {
1967 		/* Finish processing request */
1968 		iscsit_set_cmdsn(ict, rx_pdu);
1969 
1970 		iscsit_send_direct_scsi_resp(ict, rx_pdu,
1971 		    ISCSI_STATUS_CMD_COMPLETED, STATUS_BUSY);
1972 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
1973 		return;
1974 	}
1975 
1976 	/*
1977 	 * Note CmdSN and ITT in task.  IDM will have already validated this
1978 	 * request against the connection state so we don't need to check
1979 	 * that (the connection may have changed state in the meantime but
1980 	 * we will catch that when we try to send a response)
1981 	 */
1982 	itask->it_cmdsn = ntohl(iscsi_scsi->cmdsn);
1983 	itask->it_itt = iscsi_scsi->itt;
1984 
1985 	/*
1986 	 * Check for extended CDB AHS
1987 	 */
1988 	if (iscsi_scsi->hlength > 0) {
1989 		ahs_hdr = (iscsi_addl_hdr_t *)iscsi_scsi;
1990 		addl_cdb_len = ((ahs_hdr->ahs_hlen_hi << 8) |
1991 		    ahs_hdr->ahs_hlen_lo) - 1; /* Adjust for reserved byte */
1992 		if (((addl_cdb_len + 4) / sizeof (uint32_t)) >
1993 		    iscsi_scsi->hlength) {
1994 			/* Mangled header info, drop it */
1995 			idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
1996 			return;
1997 		}
1998 	}
1999 
2000 	ict = rx_pdu->isp_ic->ic_handle; /* IDM client private */
2001 
2002 	/*
2003 	 * Add task to session list.  This function will also check to
2004 	 * ensure that the task does not already exist.
2005 	 */
2006 	if (iscsit_task_start(itask) != IDM_STATUS_SUCCESS) {
2007 		/*
2008 		 * Task exists, free all resources and reject.  Don't
2009 		 * update expcmdsn in this case because RFC 3720 says
2010 		 * "The CmdSN of the rejected command PDU (if it is a
2011 		 * non-immediate command) MUST NOT be considered received
2012 		 * by the target (i.e., a command sequence gap must be
2013 		 * assumed for the CmdSN), even though the CmdSN of the
2014 		 * rejected command PDU may be reliably ascertained.  Upon
2015 		 * receiving the Reject, the initiator MUST plug the CmdSN
2016 		 * gap in order to continue to use the session.  The gap
2017 		 * may be plugged either by transmitting a command PDU
2018 		 * with the same CmdSN, or by aborting the task (see section
2019 		 * 6.9 on how an abort may plug a CmdSN gap)." (Section 6.3)
2020 		 */
2021 		iscsit_task_free(itask);
2022 		iscsit_send_reject(ict, rx_pdu, ISCSI_REJECT_TASK_IN_PROGRESS);
2023 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2024 		return;
2025 	}
2026 
2027 	/* Update sequence numbers */
2028 	iscsit_set_cmdsn(ict, rx_pdu);
2029 
2030 	/*
2031 	 * Allocate STMF task
2032 	 */
2033 	itask->it_stmf_task = stmf_task_alloc(
2034 	    itask->it_ict->ict_sess->ist_lport,
2035 	    itask->it_ict->ict_sess->ist_stmf_sess, iscsi_scsi->lun,
2036 	    16 + addl_cdb_len, 0);
2037 	if (itask->it_stmf_task == NULL) {
2038 		/*
2039 		 * Either stmf really couldn't get memory for a task or,
2040 		 * more likely, the LU is currently in reset.  Either way
2041 		 * we have no choice but to fail the request.
2042 		 */
2043 		iscsit_task_done(itask);
2044 		iscsit_task_free(itask);
2045 		iscsit_send_direct_scsi_resp(ict, rx_pdu,
2046 		    ISCSI_STATUS_CMD_COMPLETED, STATUS_BUSY);
2047 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2048 		return;
2049 	}
2050 
2051 	task = itask->it_stmf_task;
2052 	task->task_port_private = itask;
2053 
2054 	bcopy(iscsi_scsi->lun, task->task_lun_no, sizeof (task->task_lun_no));
2055 
2056 	/*
2057 	 * iSCSI and Comstar use the same values.  Should we rely on this
2058 	 * or translate them bit-wise?
2059 	 */
2060 
2061 	task->task_flags =
2062 	    (((iscsi_scsi->flags & ISCSI_FLAG_CMD_READ) ? TF_READ_DATA : 0) |
2063 	    ((iscsi_scsi->flags & ISCSI_FLAG_CMD_WRITE) ? TF_WRITE_DATA : 0) |
2064 	    ((rx_pdu->isp_datalen == 0) ? 0 : TF_INITIAL_BURST));
2065 
2066 	switch (iscsi_scsi->flags & ISCSI_FLAG_CMD_ATTR_MASK) {
2067 	case ISCSI_ATTR_UNTAGGED:
2068 		break;
2069 	case ISCSI_ATTR_SIMPLE:
2070 		task->task_additional_flags |= TF_ATTR_SIMPLE_QUEUE;
2071 		break;
2072 	case ISCSI_ATTR_ORDERED:
2073 		task->task_additional_flags |= TF_ATTR_ORDERED_QUEUE;
2074 		break;
2075 	case ISCSI_ATTR_HEAD_OF_QUEUE:
2076 		task->task_additional_flags |= TF_ATTR_HEAD_OF_QUEUE;
2077 		break;
2078 	case ISCSI_ATTR_ACA:
2079 		task->task_additional_flags |= TF_ATTR_ACA;
2080 		break;
2081 	default:
2082 		/* Protocol error but just take it, treat as untagged */
2083 		break;
2084 	}
2085 
2086 
2087 	task->task_additional_flags = 0;
2088 	task->task_priority = 0;
2089 	task->task_mgmt_function = TM_NONE;
2090 
2091 	/*
2092 	 * This "task_max_nbufs" doesn't map well to BIDI.  We probably need
2093 	 * parameter for each direction.  "MaxOutstandingR2T" may very well
2094 	 * be set to one which could prevent us from doing simultaneous
2095 	 * transfers in each direction.
2096 	 */
2097 	task->task_max_nbufs = (iscsi_scsi->flags & ISCSI_FLAG_CMD_WRITE) ?
2098 	    ict->ict_op.op_max_outstanding_r2t : STMF_BUFS_MAX;
2099 	task->task_cmd_seq_no = ntohl(iscsi_scsi->itt);
2100 	task->task_expected_xfer_length = ntohl(iscsi_scsi->data_length);
2101 
2102 	/* Copy CDB */
2103 	bcopy(iscsi_scsi->scb, task->task_cdb, 16);
2104 	if (addl_cdb_len > 0) {
2105 		bcopy(ahs_hdr->ahs_extscb, task->task_cdb + 16, addl_cdb_len);
2106 	}
2107 
2108 	DTRACE_ISCSI_3(scsi__command, idm_conn_t *, ic,
2109 	    iscsi_scsi_cmd_hdr_t *, (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr,
2110 	    scsi_task_t *, task);
2111 
2112 	/*
2113 	 * Copy the transport header into the task handle from the PDU
2114 	 * handle. The transport header describes this task's remote tagged
2115 	 * buffer.
2116 	 */
2117 	if (rx_pdu->isp_transport_hdrlen != 0) {
2118 		bcopy(rx_pdu->isp_transport_hdr,
2119 		    itask->it_idm_task->idt_transport_hdr,
2120 		    rx_pdu->isp_transport_hdrlen);
2121 	}
2122 
2123 	/*
2124 	 * Tell IDM about our new active task
2125 	 */
2126 	idm_task_start(itask->it_idm_task, (uintptr_t)itask->it_itt);
2127 
2128 	/*
2129 	 * If we have any immediate data then setup the immediate buffer
2130 	 * context that comes with the task
2131 	 */
2132 	if (rx_pdu->isp_datalen) {
2133 		ibuf = itask->it_immed_data;
2134 		ibuf->ibuf_immed_data_pdu = rx_pdu;
2135 		ibuf->ibuf_stmf_buf->db_data_size = rx_pdu->isp_datalen;
2136 		ibuf->ibuf_stmf_buf->db_buf_size = rx_pdu->isp_datalen;
2137 		ibuf->ibuf_stmf_buf->db_relative_offset = 0;
2138 		ibuf->ibuf_stmf_buf->db_sglist[0].seg_length =
2139 		    rx_pdu->isp_datalen;
2140 		ibuf->ibuf_stmf_buf->db_sglist[0].seg_addr = rx_pdu->isp_data;
2141 
2142 		DTRACE_ISCSI_8(xfer__start, idm_conn_t *, ic,
2143 		    uintptr_t, ibuf->ibuf_stmf_buf->db_sglist[0].seg_addr,
2144 		    uint32_t, ibuf->ibuf_stmf_buf->db_relative_offset,
2145 		    uint64_t, 0, uint32_t, 0, uint32_t, 0, /* no raddr */
2146 		    uint32_t, rx_pdu->isp_datalen, int, XFER_BUF_TX_TO_INI);
2147 
2148 		/*
2149 		 * For immediate data transfer, there is no callback from
2150 		 * stmf to indicate that the initial burst of data is
2151 		 * transferred successfully. In some cases, the task can
2152 		 * get freed before execution returns from stmf_post_task.
2153 		 * Although this xfer-start/done probe accurately tracks
2154 		 * the size of the transfer, it does only provide a best
2155 		 * effort on the timing of the transfer.
2156 		 */
2157 		DTRACE_ISCSI_8(xfer__done, idm_conn_t *, ic,
2158 		    uintptr_t, ibuf->ibuf_stmf_buf->db_sglist[0].seg_addr,
2159 		    uint32_t, ibuf->ibuf_stmf_buf->db_relative_offset,
2160 		    uint64_t, 0, uint32_t, 0, uint32_t, 0, /* no raddr */
2161 		    uint32_t, rx_pdu->isp_datalen, int, XFER_BUF_TX_TO_INI);
2162 		stmf_post_task(task, ibuf->ibuf_stmf_buf);
2163 	} else {
2164 
2165 		stmf_post_task(task, NULL);
2166 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2167 	}
2168 }
2169 
2170 void
2171 iscsit_deferred_dispatch(idm_pdu_t *rx_pdu)
2172 {
2173 	iscsit_conn_t *ict = rx_pdu->isp_ic->ic_handle;
2174 
2175 	/*
2176 	 * If the connection has been lost then ignore new PDU's
2177 	 */
2178 	mutex_enter(&ict->ict_mutex);
2179 	if (ict->ict_lost) {
2180 		mutex_exit(&ict->ict_mutex);
2181 		idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
2182 		return;
2183 	}
2184 
2185 	/*
2186 	 * Grab a hold on the connection to prevent it from going away
2187 	 * between now and when the taskq function is called.
2188 	 */
2189 	iscsit_conn_dispatch_hold(ict);
2190 	mutex_exit(&ict->ict_mutex);
2191 
2192 	taskq_dispatch_ent(iscsit_global.global_dispatch_taskq,
2193 	    iscsit_deferred, rx_pdu, 0, &rx_pdu->isp_tqent);
2194 }
2195 
2196 static void
2197 iscsit_deferred(void *rx_pdu_void)
2198 {
2199 	idm_pdu_t		*rx_pdu = rx_pdu_void;
2200 	idm_conn_t		*ic = rx_pdu->isp_ic;
2201 	iscsit_conn_t		*ict = ic->ic_handle;
2202 
2203 	/*
2204 	 * NOP and Task Management Commands can be marked for immediate
2205 	 * delivery. Commands marked as 'Immediate' are to be considered
2206 	 * for execution as soon as they arrive on the target. So these
2207 	 * should not be checked for sequence order and put in a queue.
2208 	 * The CmdSN is not advanced for Immediate Commands.
2209 	 */
2210 	switch (IDM_PDU_OPCODE(rx_pdu)) {
2211 	case ISCSI_OP_NOOP_OUT:
2212 		if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
2213 			iscsit_set_cmdsn(ict, rx_pdu);
2214 			iscsit_pdu_op_noop(ict, rx_pdu);
2215 		}
2216 		break;
2217 	case ISCSI_OP_LOGIN_CMD:
2218 		iscsit_pdu_op_login_cmd(ict, rx_pdu);
2219 		iscsit_conn_dispatch_rele(ict);
2220 		return;
2221 	case ISCSI_OP_TEXT_CMD:
2222 		if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
2223 			iscsit_set_cmdsn(ict, rx_pdu);
2224 			iscsit_pdu_op_text_cmd(ict, rx_pdu);
2225 		}
2226 		break;
2227 	case ISCSI_OP_LOGOUT_CMD:
2228 		if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
2229 			iscsit_set_cmdsn(ict, rx_pdu);
2230 			iscsit_pdu_op_logout_cmd(ict, rx_pdu);
2231 		}
2232 		break;
2233 	default:
2234 		/* Protocol error.  IDM should have caught this */
2235 		idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
2236 		ASSERT(0);
2237 		break;
2238 	}
2239 	/*
2240 	 * Check if there are other PDUs in the session staging queue
2241 	 * waiting to be posted to SCSI layer.
2242 	 */
2243 	iscsit_process_pdu_in_queue(ict->ict_sess);
2244 
2245 	iscsit_conn_dispatch_rele(ict);
2246 }
2247 
2248 static void
2249 iscsit_send_direct_scsi_resp(iscsit_conn_t *ict, idm_pdu_t *rx_pdu,
2250     uint8_t response, uint8_t cmd_status)
2251 {
2252 	idm_pdu_t			*rsp_pdu;
2253 	idm_conn_t			*ic;
2254 	iscsi_scsi_rsp_hdr_t		*resp;
2255 	iscsi_scsi_cmd_hdr_t		*req =
2256 	    (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
2257 
2258 	ic = ict->ict_ic;
2259 
2260 	rsp_pdu = idm_pdu_alloc(sizeof (iscsi_scsi_rsp_hdr_t), 0);
2261 	idm_pdu_init(rsp_pdu, ic, NULL, NULL);
2262 	/*
2263 	 * StatSN is incremented by 1 for every response sent on
2264 	 * a connection except for responses sent as a result of
2265 	 * a retry or SNACK
2266 	 */
2267 	rsp_pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2268 
2269 	resp = (iscsi_scsi_rsp_hdr_t *)rsp_pdu->isp_hdr;
2270 
2271 	resp->opcode = ISCSI_OP_SCSI_RSP;
2272 	resp->flags = ISCSI_FLAG_FINAL;
2273 	resp->response = response;
2274 	resp->cmd_status = cmd_status;
2275 	resp->itt = req->itt;
2276 	if ((response == ISCSI_STATUS_CMD_COMPLETED) &&
2277 	    (req->data_length != 0) &&
2278 	    ((req->flags & ISCSI_FLAG_CMD_READ) ||
2279 	    (req->flags & ISCSI_FLAG_CMD_WRITE))) {
2280 		resp->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
2281 		resp->residual_count = req->data_length;
2282 	}
2283 
2284 	DTRACE_PROBE4(iscsi__scsi__direct__response,
2285 	    iscsit_conn_t *, ict,
2286 	    uint8_t, resp->response,
2287 	    uint8_t, resp->cmd_status,
2288 	    idm_pdu_t *, rsp_pdu);
2289 
2290 	iscsit_pdu_tx(rsp_pdu);
2291 }
2292 
2293 void
2294 iscsit_send_task_mgmt_resp(idm_pdu_t *tm_resp_pdu, uint8_t tm_status)
2295 {
2296 	iscsi_scsi_task_mgt_rsp_hdr_t	*tm_resp;
2297 
2298 	/*
2299 	 * The target must take note of the last-sent StatSN.
2300 	 * The StatSN is to be incremented after sending a
2301 	 * task management response. Digest recovery can only
2302 	 * work if StatSN is incremented.
2303 	 */
2304 	tm_resp_pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2305 	tm_resp = (iscsi_scsi_task_mgt_rsp_hdr_t *)tm_resp_pdu->isp_hdr;
2306 	tm_resp->response = tm_status;
2307 
2308 	DTRACE_PROBE3(iscsi__scsi__tm__response,
2309 	    iscsit_conn_t *, tm_resp_pdu->isp_ic->ic_handle,
2310 	    uint8_t, tm_resp->response,
2311 	    idm_pdu_t *, tm_resp_pdu);
2312 	iscsit_pdu_tx(tm_resp_pdu);
2313 }
2314 
2315 void
2316 iscsit_op_scsi_task_mgmt(iscsit_conn_t *ict, idm_pdu_t *rx_pdu)
2317 {
2318 	idm_pdu_t			*tm_resp_pdu;
2319 	iscsit_task_t			*itask;
2320 	iscsit_task_t			*tm_itask;
2321 	scsi_task_t			*task;
2322 	iscsi_scsi_task_mgt_hdr_t 	*iscsi_tm =
2323 	    (iscsi_scsi_task_mgt_hdr_t *)rx_pdu->isp_hdr;
2324 	iscsi_scsi_task_mgt_rsp_hdr_t 	*iscsi_tm_rsp =
2325 	    (iscsi_scsi_task_mgt_rsp_hdr_t *)rx_pdu->isp_hdr;
2326 	uint32_t			rtt, cmdsn, refcmdsn;
2327 	uint8_t				tm_func;
2328 
2329 	/*
2330 	 * Setup response PDU (response field will get filled in later)
2331 	 */
2332 	tm_resp_pdu = idm_pdu_alloc(sizeof (iscsi_scsi_task_mgt_rsp_hdr_t), 0);
2333 	if (tm_resp_pdu == NULL) {
2334 		/* Can't respond, just drop it */
2335 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2336 		return;
2337 	}
2338 	idm_pdu_init(tm_resp_pdu, ict->ict_ic, NULL, NULL);
2339 	iscsi_tm_rsp = (iscsi_scsi_task_mgt_rsp_hdr_t *)tm_resp_pdu->isp_hdr;
2340 	bzero(iscsi_tm_rsp, sizeof (iscsi_scsi_task_mgt_rsp_hdr_t));
2341 	iscsi_tm_rsp->opcode = ISCSI_OP_SCSI_TASK_MGT_RSP;
2342 	iscsi_tm_rsp->flags = ISCSI_FLAG_FINAL;
2343 	iscsi_tm_rsp->itt = rx_pdu->isp_hdr->itt;
2344 
2345 	/*
2346 	 * Figure out what we're being asked to do.
2347 	 */
2348 	DTRACE_PROBE4(iscsi__scsi__tm__request,
2349 	    iscsit_conn_t *, ict,
2350 	    uint8_t, (iscsi_tm->function & ISCSI_FLAG_TASK_MGMT_FUNCTION_MASK),
2351 	    uint32_t, iscsi_tm->rtt,
2352 	    idm_pdu_t *, rx_pdu);
2353 	switch (iscsi_tm->function & ISCSI_FLAG_TASK_MGMT_FUNCTION_MASK) {
2354 	case ISCSI_TM_FUNC_ABORT_TASK:
2355 		/*
2356 		 * STMF doesn't currently support the "abort task" task
2357 		 * management command although it does support aborting
2358 		 * an individual task.  We'll get STMF to abort the task
2359 		 * for us but handle the details of the task management
2360 		 * command ourselves.
2361 		 *
2362 		 * Find the task associated with the referenced task tag.
2363 		 */
2364 		rtt = iscsi_tm->rtt;
2365 		itask = (iscsit_task_t *)idm_task_find_by_handle(ict->ict_ic,
2366 		    (uintptr_t)rtt);
2367 
2368 		if (itask == NULL) {
2369 			cmdsn = ntohl(iscsi_tm->cmdsn);
2370 			refcmdsn = ntohl(iscsi_tm->refcmdsn);
2371 
2372 			/*
2373 			 * Task was not found. But the SCSI command could be
2374 			 * on the rxpdu wait queue. If RefCmdSN is within
2375 			 * the CmdSN window and less than CmdSN of the TM
2376 			 * function, return "Function Complete". Otherwise,
2377 			 * return "Task Does Not Exist".
2378 			 */
2379 
2380 			if (iscsit_cmdsn_in_window(ict, refcmdsn) &&
2381 			    iscsit_sna_lt(refcmdsn, cmdsn)) {
2382 				mutex_enter(&ict->ict_sess->ist_sn_mutex);
2383 				(void) iscsit_remove_pdu_from_queue(
2384 				    ict->ict_sess, refcmdsn);
2385 				iscsit_conn_dispatch_rele(ict);
2386 				mutex_exit(&ict->ict_sess->ist_sn_mutex);
2387 				iscsit_send_task_mgmt_resp(tm_resp_pdu,
2388 				    SCSI_TCP_TM_RESP_COMPLETE);
2389 			} else {
2390 				iscsit_send_task_mgmt_resp(tm_resp_pdu,
2391 				    SCSI_TCP_TM_RESP_NO_TASK);
2392 			}
2393 		} else {
2394 
2395 			/*
2396 			 * Tell STMF to abort the task.  This will do no harm
2397 			 * if the task is already complete.
2398 			 */
2399 			stmf_abort(STMF_QUEUE_TASK_ABORT, itask->it_stmf_task,
2400 			    STMF_ABORTED, NULL);
2401 
2402 			/*
2403 			 * Make sure the task hasn't already completed
2404 			 */
2405 			mutex_enter(&itask->it_idm_task->idt_mutex);
2406 			if ((itask->it_idm_task->idt_state == TASK_COMPLETE) ||
2407 			    (itask->it_idm_task->idt_state == TASK_IDLE)) {
2408 				/*
2409 				 * Task is complete, return "Task Does Not
2410 				 * Exist"
2411 				 */
2412 				mutex_exit(&itask->it_idm_task->idt_mutex);
2413 				iscsit_send_task_mgmt_resp(tm_resp_pdu,
2414 				    SCSI_TCP_TM_RESP_NO_TASK);
2415 			} else {
2416 				/*
2417 				 * STMF is now aborting the task, return
2418 				 * "Function Complete"
2419 				 */
2420 				mutex_exit(&itask->it_idm_task->idt_mutex);
2421 				iscsit_send_task_mgmt_resp(tm_resp_pdu,
2422 				    SCSI_TCP_TM_RESP_COMPLETE);
2423 			}
2424 			idm_task_rele(itask->it_idm_task);
2425 		}
2426 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2427 		return;
2428 
2429 	case ISCSI_TM_FUNC_ABORT_TASK_SET:
2430 		tm_func = TM_ABORT_TASK_SET;
2431 		break;
2432 
2433 	case ISCSI_TM_FUNC_CLEAR_ACA:
2434 		tm_func = TM_CLEAR_ACA;
2435 		break;
2436 
2437 	case ISCSI_TM_FUNC_CLEAR_TASK_SET:
2438 		tm_func = TM_CLEAR_TASK_SET;
2439 		break;
2440 
2441 	case ISCSI_TM_FUNC_LOGICAL_UNIT_RESET:
2442 		tm_func = TM_LUN_RESET;
2443 		break;
2444 
2445 	case ISCSI_TM_FUNC_TARGET_WARM_RESET:
2446 		tm_func = TM_TARGET_WARM_RESET;
2447 		break;
2448 
2449 	case ISCSI_TM_FUNC_TARGET_COLD_RESET:
2450 		tm_func = TM_TARGET_COLD_RESET;
2451 		break;
2452 
2453 	case ISCSI_TM_FUNC_TASK_REASSIGN:
2454 		/*
2455 		 * We do not currently support allegiance reassignment.  When
2456 		 * we start supporting ERL1+, we will need to.
2457 		 */
2458 		iscsit_send_task_mgmt_resp(tm_resp_pdu,
2459 		    SCSI_TCP_TM_RESP_NO_ALLG_REASSN);
2460 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2461 		return;
2462 
2463 	default:
2464 		iscsit_send_task_mgmt_resp(tm_resp_pdu,
2465 		    SCSI_TCP_TM_RESP_REJECTED);
2466 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2467 		return;
2468 	}
2469 
2470 	tm_itask = iscsit_tm_task_alloc(ict);
2471 	if (tm_itask == NULL) {
2472 		iscsit_send_task_mgmt_resp(tm_resp_pdu,
2473 		    SCSI_TCP_TM_RESP_REJECTED);
2474 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2475 		return;
2476 	}
2477 
2478 
2479 	task = stmf_task_alloc(ict->ict_sess->ist_lport,
2480 	    ict->ict_sess->ist_stmf_sess, iscsi_tm->lun,
2481 	    0, STMF_TASK_EXT_NONE);
2482 	if (task == NULL) {
2483 		/*
2484 		 * If this happens, either the LU is in reset, couldn't
2485 		 * get memory, or some other condition in which we simply
2486 		 * can't complete this request.  It would be nice to return
2487 		 * an error code like "busy" but the closest we have is
2488 		 * "rejected".
2489 		 */
2490 		iscsit_send_task_mgmt_resp(tm_resp_pdu,
2491 		    SCSI_TCP_TM_RESP_REJECTED);
2492 		iscsit_tm_task_free(tm_itask);
2493 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2494 		return;
2495 	}
2496 
2497 	tm_itask->it_tm_pdu = tm_resp_pdu;
2498 	tm_itask->it_stmf_task = task;
2499 	task->task_port_private = tm_itask;
2500 	task->task_mgmt_function = tm_func;
2501 	task->task_additional_flags = TASK_AF_NO_EXPECTED_XFER_LENGTH;
2502 	task->task_priority = 0;
2503 	task->task_max_nbufs = STMF_BUFS_MAX;
2504 	task->task_cmd_seq_no = iscsi_tm->itt;
2505 	task->task_expected_xfer_length = 0;
2506 
2507 	stmf_post_task(task, NULL);
2508 	idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2509 }
2510 
2511 static void
2512 iscsit_pdu_op_noop(iscsit_conn_t *ict, idm_pdu_t *rx_pdu)
2513 {
2514 	iscsi_nop_out_hdr_t *out = (iscsi_nop_out_hdr_t *)rx_pdu->isp_hdr;
2515 	iscsi_nop_in_hdr_t *in;
2516 	int resp_datalen;
2517 	idm_pdu_t *resp;
2518 
2519 	/* Ignore the response from initiator */
2520 	if ((out->itt == ISCSI_RSVD_TASK_TAG) ||
2521 	    (out->ttt != ISCSI_RSVD_TASK_TAG)) {
2522 		idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2523 		return;
2524 	}
2525 
2526 	/* Allocate a PDU to respond */
2527 	resp_datalen = ntoh24(out->dlength);
2528 	resp = idm_pdu_alloc(sizeof (iscsi_hdr_t), resp_datalen);
2529 	idm_pdu_init(resp, ict->ict_ic, NULL, NULL);
2530 	if (resp_datalen > 0) {
2531 		bcopy(rx_pdu->isp_data, resp->isp_data, resp_datalen);
2532 	}
2533 
2534 	/*
2535 	 * When sending a NOP-In as a response to a NOP-Out from the initiator,
2536 	 * the target must respond with the same initiator task tag that was
2537 	 * provided in the NOP-Out request, the target transfer tag must be
2538 	 * ISCSI_RSVD_TASK_TAG (0xffffffff) and StatSN will contain the next
2539 	 * status sequence number. The StatSN for the connection is advanced
2540 	 * after this PDU is sent.
2541 	 */
2542 	in = (iscsi_nop_in_hdr_t *)resp->isp_hdr;
2543 	bzero(in, sizeof (*in));
2544 	in->opcode = ISCSI_OP_NOOP_IN;
2545 	in->flags = ISCSI_FLAG_FINAL;
2546 	bcopy(out->lun, in->lun, 8);
2547 	in->itt		= out->itt;
2548 	in->ttt		= ISCSI_RSVD_TASK_TAG;
2549 	hton24(in->dlength, resp_datalen);
2550 	resp->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2551 	/* Any other field in resp to be set? */
2552 	iscsit_pdu_tx(resp);
2553 	idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2554 }
2555 
2556 static void
2557 iscsit_pdu_op_login_cmd(iscsit_conn_t	*ict, idm_pdu_t *rx_pdu)
2558 {
2559 
2560 	/*
2561 	 * Submit PDU to login state machine.  State machine will free the
2562 	 * PDU.
2563 	 */
2564 	iscsit_login_sm_event(ict, ILE_LOGIN_RCV, rx_pdu);
2565 }
2566 
2567 void
2568 iscsit_pdu_op_logout_cmd(iscsit_conn_t	*ict, idm_pdu_t *rx_pdu)
2569 {
2570 	iscsi_logout_hdr_t 	*logout_req =
2571 	    (iscsi_logout_hdr_t *)rx_pdu->isp_hdr;
2572 	iscsi_logout_rsp_hdr_t	*logout_rsp;
2573 	idm_pdu_t *resp;
2574 
2575 	/* Allocate a PDU to respond */
2576 	resp = idm_pdu_alloc(sizeof (iscsi_hdr_t), 0);
2577 	idm_pdu_init(resp, ict->ict_ic, NULL, NULL);
2578 	/*
2579 	 * The StatSN is to be sent to the initiator,
2580 	 * it is not required to increment the number
2581 	 * as the connection is terminating.
2582 	 */
2583 	resp->isp_flags |= IDM_PDU_SET_STATSN;
2584 	/*
2585 	 * Logout results in the immediate termination of all tasks except
2586 	 * if the logout reason is ISCSI_LOGOUT_REASON_RECOVERY.  The
2587 	 * connection state machine will drive this task cleanup automatically
2588 	 * so we don't need to handle that here.
2589 	 */
2590 	logout_rsp = (iscsi_logout_rsp_hdr_t *)resp->isp_hdr;
2591 	bzero(logout_rsp, sizeof (*logout_rsp));
2592 	logout_rsp->opcode = ISCSI_OP_LOGOUT_RSP;
2593 	logout_rsp->flags = ISCSI_FLAG_FINAL;
2594 	logout_rsp->itt = logout_req->itt;
2595 	if ((logout_req->flags & ISCSI_FLAG_LOGOUT_REASON_MASK) >
2596 	    ISCSI_LOGOUT_REASON_RECOVERY) {
2597 		logout_rsp->response = ISCSI_LOGOUT_RECOVERY_UNSUPPORTED;
2598 	} else {
2599 		logout_rsp->response = ISCSI_LOGOUT_SUCCESS;
2600 	}
2601 
2602 	iscsit_pdu_tx(resp);
2603 	idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2604 }
2605 
2606 /*
2607  * Calculate the number of outstanding commands we can process
2608  */
2609 int
2610 iscsit_cmd_window()
2611 {
2612 	/*
2613 	 * Instead of using a pre-defined constant for the command window,
2614 	 * it should be made confiurable and dynamic. With MC/S, sequence
2615 	 * numbers will be used up at a much faster rate than with SC/S.
2616 	 */
2617 	return	(ISCSIT_MAX_WINDOW);
2618 }
2619 
2620 /*
2621  * Set local registers based on incoming PDU
2622  */
2623 void
2624 iscsit_set_cmdsn(iscsit_conn_t *ict, idm_pdu_t *rx_pdu)
2625 {
2626 	iscsit_sess_t *ist;
2627 	iscsi_scsi_cmd_hdr_t *req;
2628 
2629 	ist = ict->ict_sess;
2630 
2631 	req = (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
2632 	if (req->opcode & ISCSI_OP_IMMEDIATE) {
2633 		/* no cmdsn increment for immediate PDUs */
2634 		return;
2635 	}
2636 
2637 	/* Ensure that the ExpCmdSN advances in an orderly manner */
2638 	mutex_enter(&ist->ist_sn_mutex);
2639 	ist->ist_expcmdsn = ntohl(req->cmdsn) + 1;
2640 	ist->ist_maxcmdsn = ntohl(req->cmdsn) + iscsit_cmd_window();
2641 	mutex_exit(&ist->ist_sn_mutex);
2642 }
2643 
2644 /*
2645  * Wrapper funtion, calls iscsi_calc_rspsn and idm_pdu_tx
2646  */
2647 void
2648 iscsit_pdu_tx(idm_pdu_t *pdu)
2649 {
2650 	iscsit_conn_t *ict = pdu->isp_ic->ic_handle;
2651 	iscsi_scsi_rsp_hdr_t *rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
2652 	iscsit_sess_t *ist = ict->ict_sess;
2653 
2654 	/*
2655 	 * The command sequence numbers are session-wide and must stay
2656 	 * consistent across the transfer, so protect the cmdsn with a
2657 	 * mutex lock on the session. The status sequence number will
2658 	 * be updated just before the transport layer transmits the PDU.
2659 	 */
2660 
2661 	mutex_enter(&ict->ict_sess->ist_sn_mutex);
2662 	/* Set ExpCmdSN and MaxCmdSN */
2663 	rsp->maxcmdsn = htonl(ist->ist_maxcmdsn);
2664 	rsp->expcmdsn = htonl(ist->ist_expcmdsn);
2665 	idm_pdu_tx(pdu);
2666 	mutex_exit(&ict->ict_sess->ist_sn_mutex);
2667 }
2668 
2669 /*
2670  * Internal functions
2671  */
2672 
2673 void
2674 iscsit_send_async_event(iscsit_conn_t *ict, uint8_t event)
2675 {
2676 	idm_pdu_t		*abt;
2677 	iscsi_async_evt_hdr_t	*async_abt;
2678 
2679 	/*
2680 	 * Get a PDU to build the abort request.
2681 	 */
2682 	abt = idm_pdu_alloc(sizeof (iscsi_hdr_t), 0);
2683 	if (abt == NULL) {
2684 		idm_conn_event(ict->ict_ic, CE_TRANSPORT_FAIL, NULL);
2685 		return;
2686 	}
2687 
2688 	/*
2689 	 * A asynchronous message is sent by the target to request a logout.
2690 	 * The StatSN for the connection is advanced after the PDU is sent
2691 	 * to allow for initiator and target state synchronization.
2692 	 */
2693 	idm_pdu_init(abt, ict->ict_ic, NULL, NULL);
2694 	abt->isp_datalen = 0;
2695 	abt->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2696 
2697 	async_abt = (iscsi_async_evt_hdr_t *)abt->isp_hdr;
2698 	bzero(async_abt, sizeof (*async_abt));
2699 	async_abt->opcode = ISCSI_OP_ASYNC_EVENT;
2700 	async_abt->async_event = event;
2701 	async_abt->flags = ISCSI_FLAG_FINAL;
2702 	async_abt->rsvd4[0] = 0xff;
2703 	async_abt->rsvd4[1] = 0xff;
2704 	async_abt->rsvd4[2] = 0xff;
2705 	async_abt->rsvd4[3] = 0xff;
2706 
2707 	switch (event) {
2708 	case ISCSI_ASYNC_EVENT_REQUEST_LOGOUT:
2709 		async_abt->param3 = htons(IDM_LOGOUT_SECONDS);
2710 		break;
2711 	case ISCSI_ASYNC_EVENT_SCSI_EVENT:
2712 	case ISCSI_ASYNC_EVENT_DROPPING_CONNECTION:
2713 	case ISCSI_ASYNC_EVENT_DROPPING_ALL_CONNECTIONS:
2714 	case ISCSI_ASYNC_EVENT_PARAM_NEGOTIATION:
2715 	default:
2716 		ASSERT(0);
2717 	}
2718 
2719 	iscsit_pdu_tx(abt);
2720 }
2721 
2722 void
2723 iscsit_send_reject(iscsit_conn_t *ict, idm_pdu_t *rejected_pdu, uint8_t reason)
2724 {
2725 	idm_pdu_t		*reject_pdu;
2726 	iscsi_reject_rsp_hdr_t	*reject;
2727 
2728 	/*
2729 	 * Get a PDU to build the abort request.
2730 	 */
2731 	reject_pdu = idm_pdu_alloc(sizeof (iscsi_hdr_t),
2732 	    rejected_pdu->isp_hdrlen);
2733 	if (reject_pdu == NULL) {
2734 		idm_conn_event(ict->ict_ic, CE_TRANSPORT_FAIL, NULL);
2735 		return;
2736 	}
2737 	idm_pdu_init(reject_pdu, ict->ict_ic, NULL, NULL);
2738 	/* StatSN is advanced after a Reject PDU */
2739 	reject_pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2740 	reject_pdu->isp_datalen = rejected_pdu->isp_hdrlen;
2741 	bcopy(rejected_pdu->isp_hdr, reject_pdu->isp_data,
2742 	    rejected_pdu->isp_hdrlen);
2743 
2744 	reject = (iscsi_reject_rsp_hdr_t *)reject_pdu->isp_hdr;
2745 	bzero(reject, sizeof (*reject));
2746 	reject->opcode = ISCSI_OP_REJECT_MSG;
2747 	reject->reason = reason;
2748 	reject->flags = ISCSI_FLAG_FINAL;
2749 	hton24(reject->dlength, rejected_pdu->isp_hdrlen);
2750 	reject->must_be_ff[0] = 0xff;
2751 	reject->must_be_ff[1] = 0xff;
2752 	reject->must_be_ff[2] = 0xff;
2753 	reject->must_be_ff[3] = 0xff;
2754 
2755 	iscsit_pdu_tx(reject_pdu);
2756 }
2757 
2758 
2759 static iscsit_task_t *
2760 iscsit_task_alloc(iscsit_conn_t *ict)
2761 {
2762 	iscsit_task_t *itask;
2763 	iscsit_buf_t *immed_ibuf;
2764 
2765 	/*
2766 	 * Possible items to pre-alloc if we cache iscsit_task_t's:
2767 	 *
2768 	 * Status PDU w/ sense buffer
2769 	 * stmf_data_buf_t for immediate data
2770 	 */
2771 	itask = kmem_alloc(sizeof (iscsit_task_t) + sizeof (iscsit_buf_t) +
2772 	    sizeof (stmf_data_buf_t), KM_NOSLEEP);
2773 	if (itask != NULL) {
2774 		mutex_init(&itask->it_mutex, NULL, MUTEX_DRIVER, NULL);
2775 		itask->it_aborted = itask->it_stmf_abort =
2776 		    itask->it_tm_task = 0;
2777 
2778 		immed_ibuf = (iscsit_buf_t *)(itask + 1);
2779 		bzero(immed_ibuf, sizeof (*immed_ibuf));
2780 		immed_ibuf->ibuf_is_immed = B_TRUE;
2781 		immed_ibuf->ibuf_stmf_buf = (stmf_data_buf_t *)(immed_ibuf + 1);
2782 
2783 		bzero(immed_ibuf->ibuf_stmf_buf, sizeof (stmf_data_buf_t));
2784 		immed_ibuf->ibuf_stmf_buf->db_port_private = immed_ibuf;
2785 		immed_ibuf->ibuf_stmf_buf->db_sglist_length = 1;
2786 		immed_ibuf->ibuf_stmf_buf->db_flags = DB_DIRECTION_FROM_RPORT |
2787 		    DB_DONT_CACHE;
2788 		itask->it_immed_data = immed_ibuf;
2789 		itask->it_idm_task = idm_task_alloc(ict->ict_ic);
2790 		if (itask->it_idm_task != NULL) {
2791 			itask->it_idm_task->idt_private = itask;
2792 			itask->it_ict = ict;
2793 			itask->it_ttt = itask->it_idm_task->idt_tt;
2794 			return (itask);
2795 		} else {
2796 			kmem_free(itask, sizeof (iscsit_task_t) +
2797 			    sizeof (iscsit_buf_t) + sizeof (stmf_data_buf_t));
2798 		}
2799 	}
2800 
2801 	return (NULL);
2802 }
2803 
2804 static void
2805 iscsit_task_free(iscsit_task_t *itask)
2806 {
2807 	idm_task_free(itask->it_idm_task);
2808 	mutex_destroy(&itask->it_mutex);
2809 	kmem_free(itask, sizeof (iscsit_task_t) +
2810 	    sizeof (iscsit_buf_t) + sizeof (stmf_data_buf_t));
2811 }
2812 
2813 static iscsit_task_t *
2814 iscsit_tm_task_alloc(iscsit_conn_t *ict)
2815 {
2816 	iscsit_task_t *itask;
2817 
2818 	itask = kmem_zalloc(sizeof (iscsit_task_t), KM_NOSLEEP);
2819 	if (itask != NULL) {
2820 		idm_conn_hold(ict->ict_ic);
2821 		mutex_init(&itask->it_mutex, NULL, MUTEX_DRIVER, NULL);
2822 		itask->it_aborted = itask->it_stmf_abort =
2823 		    itask->it_tm_responded = 0;
2824 		itask->it_tm_pdu = NULL;
2825 		itask->it_tm_task = 1;
2826 		itask->it_ict = ict;
2827 	}
2828 
2829 	return (itask);
2830 }
2831 
2832 static void
2833 iscsit_tm_task_free(iscsit_task_t *itask)
2834 {
2835 	/*
2836 	 * If we responded then the call to idm_pdu_complete will free the
2837 	 * PDU.  Otherwise we got aborted before the TM function could
2838 	 * complete and we need to free the PDU explicitly.
2839 	 */
2840 	if (itask->it_tm_pdu != NULL && !itask->it_tm_responded)
2841 		idm_pdu_free(itask->it_tm_pdu);
2842 	idm_conn_rele(itask->it_ict->ict_ic);
2843 	mutex_destroy(&itask->it_mutex);
2844 	kmem_free(itask, sizeof (iscsit_task_t));
2845 }
2846 
2847 static idm_status_t
2848 iscsit_task_start(iscsit_task_t *itask)
2849 {
2850 	iscsit_sess_t *ist = itask->it_ict->ict_sess;
2851 	avl_index_t		where;
2852 
2853 	/*
2854 	 * Sanity check the ITT and ensure that this task does not already
2855 	 * exist.  If not then add the task to the session task list.
2856 	 */
2857 	mutex_enter(&ist->ist_mutex);
2858 	mutex_enter(&itask->it_mutex);
2859 	itask->it_active = 1;
2860 	if (avl_find(&ist->ist_task_list, itask, &where) == NULL) {
2861 		/* New task, add to AVL */
2862 		avl_insert(&ist->ist_task_list, itask, where);
2863 		mutex_exit(&itask->it_mutex);
2864 		mutex_exit(&ist->ist_mutex);
2865 		return (IDM_STATUS_SUCCESS);
2866 	}
2867 	mutex_exit(&itask->it_mutex);
2868 	mutex_exit(&ist->ist_mutex);
2869 
2870 	return (IDM_STATUS_REJECT);
2871 }
2872 
2873 static void
2874 iscsit_task_done(iscsit_task_t *itask)
2875 {
2876 	iscsit_sess_t *ist = itask->it_ict->ict_sess;
2877 
2878 	mutex_enter(&ist->ist_mutex);
2879 	mutex_enter(&itask->it_mutex);
2880 	if (itask->it_active) {
2881 		avl_remove(&ist->ist_task_list, itask);
2882 		itask->it_active = 0;
2883 	}
2884 	mutex_exit(&itask->it_mutex);
2885 	mutex_exit(&ist->ist_mutex);
2886 }
2887 
2888 /*
2889  * iscsit status PDU cache
2890  */
2891 
2892 /*ARGSUSED*/
2893 static int
2894 iscsit_status_pdu_constructor(void *pdu_void, void *arg, int flags)
2895 {
2896 	idm_pdu_t *pdu = pdu_void;
2897 	iscsi_scsi_rsp_hdr_t *rsp;
2898 
2899 	bzero(pdu, sizeof (idm_pdu_t));
2900 	pdu->isp_callback = iscsit_send_good_status_done;
2901 	pdu->isp_magic = IDM_PDU_MAGIC;
2902 	pdu->isp_hdr = (iscsi_hdr_t *)(pdu + 1); /* Ptr arithmetic */
2903 	pdu->isp_hdrlen = sizeof (iscsi_hdr_t);
2904 
2905 	/* Setup status response */
2906 	rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
2907 	bzero(rsp, sizeof (*rsp));
2908 	rsp->opcode = ISCSI_OP_SCSI_RSP;
2909 	rsp->flags = ISCSI_FLAG_FINAL;
2910 	rsp->response = ISCSI_STATUS_CMD_COMPLETED;
2911 
2912 	return (0);
2913 }
2914 
2915 /*
2916  * iscsit private data handler
2917  */
2918 
2919 /*ARGSUSED*/
2920 static void
2921 iscsit_pp_cb(struct stmf_port_provider *pp, int cmd, void *arg, uint32_t flags)
2922 {
2923 	it_config_t		*cfg;
2924 	nvlist_t		*nvl;
2925 	iscsit_service_enabled_t	old_state;
2926 
2927 	if ((cmd != STMF_PROVIDER_DATA_UPDATED) || (arg == NULL)) {
2928 		return;
2929 	}
2930 
2931 	nvl = (nvlist_t *)arg;
2932 
2933 	/* Translate nvlist */
2934 	if (it_nv_to_config(nvl, &cfg) != 0) {
2935 		cmn_err(CE_WARN, "Configuration is invalid");
2936 		return;
2937 	}
2938 
2939 	/* Check that no iSCSI ioctl is currently running */
2940 	mutex_enter(&iscsit_global.global_state_mutex);
2941 	old_state = iscsit_global.global_svc_state;
2942 	switch (iscsit_global.global_svc_state) {
2943 	case ISE_ENABLED:
2944 	case ISE_DISABLED:
2945 		iscsit_global.global_svc_state = ISE_BUSY;
2946 		break;
2947 	case ISE_ENABLING:
2948 		/*
2949 		 * It is OK for the iscsit_pp_cb to be called from inside of
2950 		 * an iSCSI ioctl only if we are currently executing inside
2951 		 * of stmf_register_port_provider.
2952 		 */
2953 		ASSERT((flags & STMF_PCB_PREG_COMPLETE) != 0);
2954 		break;
2955 	default:
2956 		cmn_err(CE_WARN, "iscsit_pp_cb called when global_svc_state"
2957 		    " is not ENABLED(0x%x) -- ignoring",
2958 		    iscsit_global.global_svc_state);
2959 		mutex_exit(&iscsit_global.global_state_mutex);
2960 		it_config_free_cmn(cfg);
2961 		return;
2962 	}
2963 	mutex_exit(&iscsit_global.global_state_mutex);
2964 
2965 	/* Update config */
2966 	(void) iscsit_config_merge(cfg);
2967 
2968 	it_config_free_cmn(cfg);
2969 
2970 	/* Restore old iSCSI driver global state */
2971 	mutex_enter(&iscsit_global.global_state_mutex);
2972 	ASSERT(iscsit_global.global_svc_state == ISE_BUSY ||
2973 	    iscsit_global.global_svc_state == ISE_ENABLING);
2974 	iscsit_global.global_svc_state = old_state;
2975 	mutex_exit(&iscsit_global.global_state_mutex);
2976 }
2977 
2978 
2979 static it_cfg_status_t
2980 iscsit_config_merge(it_config_t *in_cfg)
2981 {
2982 	it_cfg_status_t	status;
2983 	it_config_t	*cfg;
2984 	it_config_t	tmp_cfg;
2985 	list_t		tpg_del_list;
2986 
2987 	if (in_cfg) {
2988 		cfg = in_cfg;
2989 	} else {
2990 		/* Make empty config */
2991 		bzero(&tmp_cfg, sizeof (tmp_cfg));
2992 		cfg = &tmp_cfg;
2993 	}
2994 
2995 	list_create(&tpg_del_list,  sizeof (iscsit_tpg_t),
2996 	    offsetof(iscsit_tpg_t, tpg_delete_ln));
2997 
2998 	/*
2999 	 * Update targets, initiator contexts, target portal groups,
3000 	 * and iSNS client
3001 	 */
3002 	ISCSIT_GLOBAL_LOCK(RW_WRITER);
3003 	if (((status = iscsit_config_merge_tpg(cfg, &tpg_del_list))
3004 	    != 0) ||
3005 	    ((status = iscsit_config_merge_tgt(cfg)) != 0) ||
3006 	    ((status = iscsit_config_merge_ini(cfg)) != 0) ||
3007 	    ((status = isnst_config_merge(cfg)) != 0)) {
3008 		ISCSIT_GLOBAL_UNLOCK();
3009 		return (status);
3010 	}
3011 
3012 	/* Update other global config parameters */
3013 	if (iscsit_global.global_props) {
3014 		nvlist_free(iscsit_global.global_props);
3015 		iscsit_global.global_props = NULL;
3016 	}
3017 	if (in_cfg) {
3018 		(void) nvlist_dup(cfg->config_global_properties,
3019 		    &iscsit_global.global_props, KM_SLEEP);
3020 	}
3021 	ISCSIT_GLOBAL_UNLOCK();
3022 
3023 	iscsit_config_destroy_tpgs(&tpg_del_list);
3024 
3025 	list_destroy(&tpg_del_list);
3026 
3027 	return (ITCFG_SUCCESS);
3028 }
3029 
3030 /*
3031  * iscsit_sna_lt[e]
3032  *
3033  * Compare serial numbers using serial number arithmetic as defined in
3034  * RFC 1982.
3035  *
3036  * NOTE: This code is duplicated in the isns server. It ought to be common.
3037  */
3038 
3039 static int
3040 iscsit_sna_lt(uint32_t sn1, uint32_t sn2)
3041 {
3042 	return ((sn1 != sn2) &&
3043 	    (((sn1 < sn2) && ((sn2 - sn1) < ISCSIT_SNA32_CHECK)) ||
3044 	    ((sn1 > sn2) && ((sn1 - sn2) > ISCSIT_SNA32_CHECK))));
3045 }
3046 
3047 static int
3048 iscsit_sna_lte(uint32_t sn1, uint32_t sn2)
3049 {
3050 	return ((sn1 == sn2) ||
3051 	    (((sn1 < sn2) && ((sn2 - sn1) < ISCSIT_SNA32_CHECK)) ||
3052 	    ((sn1 > sn2) && ((sn1 - sn2) > ISCSIT_SNA32_CHECK))));
3053 }
3054 
3055 
3056 static boolean_t
3057 iscsit_cmdsn_in_window(iscsit_conn_t *ict, uint32_t cmdsn)
3058 {
3059 	iscsit_sess_t	*ist = ict->ict_sess;
3060 	int		rval = B_TRUE;
3061 
3062 	ist = ict->ict_sess;
3063 
3064 	mutex_enter(&ist->ist_sn_mutex);
3065 
3066 	/*
3067 	 * If cmdsn is less than ist_expcmdsn - iscsit_cmd_window() or
3068 	 * greater than ist_expcmdsn, it's not in the window.
3069 	 */
3070 
3071 	if (iscsit_sna_lt(cmdsn, (ist->ist_expcmdsn - iscsit_cmd_window())) ||
3072 	    !iscsit_sna_lte(cmdsn, ist->ist_expcmdsn)) {
3073 		rval = B_FALSE;
3074 	}
3075 
3076 	mutex_exit(&ist->ist_sn_mutex);
3077 
3078 	return (rval);
3079 }
3080 
3081 /*
3082  * iscsit_check_cmdsn_and_queue
3083  *
3084  * Independent of the order in which the iSCSI target receives non-immediate
3085  * command PDU across the entire session and any multiple connections within
3086  * the session, the target must deliver the commands to the SCSI layer in
3087  * CmdSN order. So out-of-order non-immediate commands are queued up on a
3088  * session-wide wait queue. Duplicate commands are ignored.
3089  *
3090  */
3091 static int
3092 iscsit_check_cmdsn_and_queue(idm_pdu_t *rx_pdu)
3093 {
3094 	idm_conn_t		*ic = rx_pdu->isp_ic;
3095 	iscsit_conn_t		*ict = ic->ic_handle;
3096 	iscsit_sess_t		*ist = ict->ict_sess;
3097 	iscsi_scsi_cmd_hdr_t	*hdr = (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
3098 
3099 	mutex_enter(&ist->ist_sn_mutex);
3100 	if (hdr->opcode & ISCSI_OP_IMMEDIATE) {
3101 		/* do not queue, handle it immediately */
3102 		DTRACE_PROBE2(immediate__cmd, iscsit_sess_t *, ist,
3103 		    idm_pdu_t *, rx_pdu);
3104 		mutex_exit(&ist->ist_sn_mutex);
3105 		return (ISCSIT_CMDSN_EQ_EXPCMDSN);
3106 	}
3107 	if (iscsit_sna_lt(ist->ist_expcmdsn, ntohl(hdr->cmdsn))) {
3108 		/*
3109 		 * Out-of-order commands (cmdSN higher than ExpCmdSN)
3110 		 * are staged on a fixed-size circular buffer until
3111 		 * the missing command is delivered to the SCSI layer.
3112 		 * Irrespective of the order of insertion into the
3113 		 * staging queue, the commands are processed out of the
3114 		 * queue in cmdSN order only.
3115 		 */
3116 		rx_pdu->isp_queue_time = ddi_get_time();
3117 		iscsit_add_pdu_to_queue(ist, rx_pdu);
3118 		mutex_exit(&ist->ist_sn_mutex);
3119 		return (ISCSIT_CMDSN_GT_EXPCMDSN);
3120 	} else if (iscsit_sna_lt(ntohl(hdr->cmdsn), ist->ist_expcmdsn)) {
3121 		DTRACE_PROBE3(cmdsn__lt__expcmdsn, iscsit_sess_t *, ist,
3122 		    iscsit_conn_t *, ict, idm_pdu_t *, rx_pdu);
3123 		mutex_exit(&ist->ist_sn_mutex);
3124 		return (ISCSIT_CMDSN_LT_EXPCMDSN);
3125 	} else {
3126 		mutex_exit(&ist->ist_sn_mutex);
3127 		return (ISCSIT_CMDSN_EQ_EXPCMDSN);
3128 	}
3129 }
3130 
3131 /*
3132  * iscsit_add_pdu_to_queue() adds PDUs into the array indexed by
3133  * their cmdsn value. The length of the array is kept above the
3134  * maximum window size. The window keeps the cmdsn within a range
3135  * such that there are no collisons. e.g. the assumption is that
3136  * the windowing checks make it impossible to receive PDUs that
3137  * index into the same location in the array.
3138  */
3139 static void
3140 iscsit_add_pdu_to_queue(iscsit_sess_t *ist, idm_pdu_t *rx_pdu)
3141 {
3142 	iscsit_cbuf_t	*cbuf	= ist->ist_rxpdu_queue;
3143 	iscsit_conn_t	*ict 	= rx_pdu->isp_ic->ic_handle;
3144 	uint32_t	cmdsn	=
3145 	    ((iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr)->cmdsn;
3146 	uint32_t	index;
3147 
3148 	ASSERT(MUTEX_HELD(&ist->ist_sn_mutex));
3149 	/*
3150 	 * If the connection is being torn down, then
3151 	 * don't add the PDU to the staging queue
3152 	 */
3153 	mutex_enter(&ict->ict_mutex);
3154 	if (ict->ict_lost) {
3155 		mutex_exit(&ict->ict_mutex);
3156 		idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
3157 		return;
3158 	}
3159 	iscsit_conn_dispatch_hold(ict);
3160 	mutex_exit(&ict->ict_mutex);
3161 
3162 	index = ntohl(cmdsn) % ISCSIT_RXPDU_QUEUE_LEN;
3163 	/*
3164 	 * In the normal case, assuming that the Initiator is not
3165 	 * buggy and that we don't have packet duplication occuring,
3166 	 * the entry in the array will be NULL.  However, we may have
3167 	 * received a duplicate PDU with cmdsn > expsn , and in that
3168 	 * case we just ignore this PDU -- the previously received one
3169 	 * remains queued for processing.  We need to be careful not
3170 	 * to leak this one however.
3171 	 */
3172 	if (cbuf->cb_buffer[index] != NULL) {
3173 		idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
3174 	} else {
3175 		cbuf->cb_buffer[index] = rx_pdu;
3176 		cbuf->cb_num_elems++;
3177 	}
3178 }
3179 
3180 static idm_pdu_t *
3181 iscsit_remove_pdu_from_queue(iscsit_sess_t *ist, uint32_t cmdsn)
3182 {
3183 	iscsit_cbuf_t	*cbuf	= ist->ist_rxpdu_queue;
3184 	idm_pdu_t	*pdu	= NULL;
3185 	uint32_t	index;
3186 
3187 	ASSERT(MUTEX_HELD(&ist->ist_sn_mutex));
3188 	index = cmdsn % ISCSIT_RXPDU_QUEUE_LEN;
3189 	if ((pdu = cbuf->cb_buffer[index]) != NULL) {
3190 		ASSERT(cmdsn ==
3191 		    ntohl(((iscsi_scsi_cmd_hdr_t *)pdu->isp_hdr)->cmdsn));
3192 		cbuf->cb_buffer[index] = NULL;
3193 		cbuf->cb_num_elems--;
3194 		return (pdu);
3195 	}
3196 	return (NULL);
3197 }
3198 
3199 /*
3200  * iscsit_process_pdu_in_queue() finds the next pdu in sequence
3201  * and posts it to the SCSI layer
3202  */
3203 static void
3204 iscsit_process_pdu_in_queue(iscsit_sess_t *ist)
3205 {
3206 	iscsit_cbuf_t	*cbuf	= ist->ist_rxpdu_queue;
3207 	idm_pdu_t	*pdu = NULL;
3208 	uint32_t	expcmdsn;
3209 
3210 	for (;;) {
3211 		mutex_enter(&ist->ist_sn_mutex);
3212 		if (cbuf->cb_num_elems == 0) {
3213 			mutex_exit(&ist->ist_sn_mutex);
3214 			break;
3215 		}
3216 		expcmdsn = ist->ist_expcmdsn;
3217 		if ((pdu = iscsit_remove_pdu_from_queue(ist, expcmdsn))
3218 		    == NULL) {
3219 			mutex_exit(&ist->ist_sn_mutex);
3220 			break;
3221 		}
3222 		mutex_exit(&ist->ist_sn_mutex);
3223 		iscsit_post_staged_pdu(pdu);
3224 	}
3225 }
3226 
3227 static void
3228 iscsit_post_staged_pdu(idm_pdu_t *rx_pdu)
3229 {
3230 	iscsit_conn_t	*ict	= rx_pdu->isp_ic->ic_handle;
3231 
3232 	/* Post the PDU to the SCSI layer */
3233 	switch (IDM_PDU_OPCODE(rx_pdu)) {
3234 	case ISCSI_OP_NOOP_OUT:
3235 		iscsit_set_cmdsn(ict, rx_pdu);
3236 		iscsit_pdu_op_noop(ict, rx_pdu);
3237 		break;
3238 	case ISCSI_OP_TEXT_CMD:
3239 		iscsit_set_cmdsn(ict, rx_pdu);
3240 		iscsit_pdu_op_text_cmd(ict, rx_pdu);
3241 		break;
3242 	case ISCSI_OP_SCSI_TASK_MGT_MSG:
3243 		iscsit_set_cmdsn(ict, rx_pdu);
3244 		iscsit_op_scsi_task_mgmt(ict, rx_pdu);
3245 		break;
3246 	case ISCSI_OP_SCSI_CMD:
3247 		/* cmdSN will be incremented after creating itask */
3248 		iscsit_post_scsi_cmd(rx_pdu->isp_ic, rx_pdu);
3249 		break;
3250 	case ISCSI_OP_LOGOUT_CMD:
3251 		iscsit_set_cmdsn(ict, rx_pdu);
3252 		iscsit_pdu_op_logout_cmd(ict, rx_pdu);
3253 		break;
3254 	default:
3255 		/* No other PDUs should be placed on the queue */
3256 		ASSERT(0);
3257 	}
3258 	iscsit_conn_dispatch_rele(ict); /* release hold on the conn */
3259 }
3260 
3261 /* ARGSUSED */
3262 void
3263 iscsit_rxpdu_queue_monitor_start(void)
3264 {
3265 	mutex_enter(&iscsit_rxpdu_queue_monitor_mutex);
3266 	if (iscsit_rxpdu_queue_monitor_thr_running) {
3267 		mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3268 		return;
3269 	}
3270 	iscsit_rxpdu_queue_monitor_thr_id =
3271 	    thread_create(NULL, 0, iscsit_rxpdu_queue_monitor, NULL,
3272 	    0, &p0, TS_RUN, minclsyspri);
3273 	while (!iscsit_rxpdu_queue_monitor_thr_running) {
3274 		cv_wait(&iscsit_rxpdu_queue_monitor_cv,
3275 		    &iscsit_rxpdu_queue_monitor_mutex);
3276 	}
3277 	mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3278 
3279 }
3280 
3281 /* ARGSUSED */
3282 void
3283 iscsit_rxpdu_queue_monitor_stop(void)
3284 {
3285 	mutex_enter(&iscsit_rxpdu_queue_monitor_mutex);
3286 	if (iscsit_rxpdu_queue_monitor_thr_running) {
3287 		iscsit_rxpdu_queue_monitor_thr_running = B_FALSE;
3288 		cv_signal(&iscsit_rxpdu_queue_monitor_cv);
3289 		mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3290 
3291 		thread_join(iscsit_rxpdu_queue_monitor_thr_did);
3292 		return;
3293 	}
3294 	mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3295 }
3296 
3297 /*
3298  * A separate thread is used to scan the staging queue on all the
3299  * sessions, If a delayed PDU does not arrive within a timeout, the
3300  * target will advance to the staged PDU that is next in sequence
3301  * and exceeded the threshold wait time. It is up to the initiator
3302  * to note that the target has not acknowledged a particular cmdsn
3303  * and take appropriate action.
3304  */
3305 /* ARGSUSED */
3306 static void
3307 iscsit_rxpdu_queue_monitor(void *arg)
3308 {
3309 	iscsit_tgt_t	*tgt;
3310 	iscsit_sess_t	*ist;
3311 
3312 	mutex_enter(&iscsit_rxpdu_queue_monitor_mutex);
3313 	iscsit_rxpdu_queue_monitor_thr_did = curthread->t_did;
3314 	iscsit_rxpdu_queue_monitor_thr_running = B_TRUE;
3315 	cv_signal(&iscsit_rxpdu_queue_monitor_cv);
3316 
3317 	while (iscsit_rxpdu_queue_monitor_thr_running) {
3318 		ISCSIT_GLOBAL_LOCK(RW_READER);
3319 		for (tgt = avl_first(&iscsit_global.global_target_list);
3320 		    tgt != NULL;
3321 		    tgt = AVL_NEXT(&iscsit_global.global_target_list, tgt)) {
3322 			mutex_enter(&tgt->target_mutex);
3323 			for (ist = avl_first(&tgt->target_sess_list);
3324 			    ist != NULL;
3325 			    ist = AVL_NEXT(&tgt->target_sess_list, ist)) {
3326 
3327 				iscsit_rxpdu_queue_monitor_session(ist);
3328 			}
3329 			mutex_exit(&tgt->target_mutex);
3330 		}
3331 		ISCSIT_GLOBAL_UNLOCK();
3332 		if (iscsit_rxpdu_queue_monitor_thr_running == B_FALSE) {
3333 			break;
3334 		}
3335 		(void) cv_reltimedwait(&iscsit_rxpdu_queue_monitor_cv,
3336 		    &iscsit_rxpdu_queue_monitor_mutex,
3337 		    ISCSIT_RXPDU_QUEUE_MONITOR_INTERVAL * drv_usectohz(1000000),
3338 		    TR_CLOCK_TICK);
3339 	}
3340 	mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3341 	thread_exit();
3342 }
3343 
3344 static void
3345 iscsit_rxpdu_queue_monitor_session(iscsit_sess_t *ist)
3346 {
3347 	iscsit_cbuf_t	*cbuf	= ist->ist_rxpdu_queue;
3348 	idm_pdu_t	*next_pdu = NULL;
3349 	uint32_t	index, next_cmdsn, i;
3350 
3351 	/*
3352 	 * Assume that all PDUs in the staging queue have a cmdsn >= expcmdsn.
3353 	 * Starting with the expcmdsn, iterate over the staged PDUs to find
3354 	 * the next PDU with a wait time greater than the threshold. If found
3355 	 * advance the staged PDU to the SCSI layer, skipping over the missing
3356 	 * PDU(s) to get past the hole in the command sequence. It is up to
3357 	 * the initiator to note that the target has not acknowledged a cmdsn
3358 	 * and take appropriate action.
3359 	 *
3360 	 * Since the PDU(s) arrive in any random order, it is possible that
3361 	 * that the actual wait time for a particular PDU is much longer than
3362 	 * the defined threshold. e.g. Consider a case where commands are sent
3363 	 * over 4 different connections, and cmdsn = 1004 arrives first, then
3364 	 * 1003, and 1002 and 1001 are lost due to a connection failure.
3365 	 * So now 1003 is waiting for 1002 to be delivered, and although the
3366 	 * wait time of 1004 > wait time of 1003, only 1003 will be considered
3367 	 * by the monitor thread. 1004 will be automatically processed by
3368 	 * iscsit_process_pdu_in_queue() once the scan is complete and the
3369 	 * expcmdsn becomes current.
3370 	 */
3371 	mutex_enter(&ist->ist_sn_mutex);
3372 	cbuf = ist->ist_rxpdu_queue;
3373 	if (cbuf->cb_num_elems == 0) {
3374 		mutex_exit(&ist->ist_sn_mutex);
3375 		return;
3376 	}
3377 	for (next_pdu = NULL, i = 0; ; i++) {
3378 		next_cmdsn = ist->ist_expcmdsn + i; /* start at expcmdsn */
3379 		index = next_cmdsn % ISCSIT_RXPDU_QUEUE_LEN;
3380 		if ((next_pdu = cbuf->cb_buffer[index]) != NULL) {
3381 			/*
3382 			 * If the PDU wait time has not exceeded threshold
3383 			 * stop scanning the staging queue until the timer
3384 			 * fires again
3385 			 */
3386 			if ((ddi_get_time() - next_pdu->isp_queue_time)
3387 			    < rxpdu_queue_threshold) {
3388 				mutex_exit(&ist->ist_sn_mutex);
3389 				return;
3390 			}
3391 			/*
3392 			 * Remove the next PDU from the queue and post it
3393 			 * to the SCSI layer, skipping over the missing
3394 			 * PDU. Stop scanning the staging queue until
3395 			 * the monitor timer fires again
3396 			 */
3397 			(void) iscsit_remove_pdu_from_queue(ist, next_cmdsn);
3398 			mutex_exit(&ist->ist_sn_mutex);
3399 			DTRACE_PROBE3(advanced__to__blocked__cmdsn,
3400 			    iscsit_sess_t *, ist, idm_pdu_t *, next_pdu,
3401 			    uint32_t, next_cmdsn);
3402 			iscsit_post_staged_pdu(next_pdu);
3403 			/* Deliver any subsequent PDUs immediately */
3404 			iscsit_process_pdu_in_queue(ist);
3405 			return;
3406 		}
3407 		/*
3408 		 * Skipping over i PDUs, e.g. a case where commands 1001 and
3409 		 * 1002 are lost in the network, skip over both and post 1003
3410 		 * expcmdsn then becomes 1004 at the end of the scan.
3411 		 */
3412 		DTRACE_PROBE2(skipping__over__cmdsn, iscsit_sess_t *, ist,
3413 		    uint32_t, next_cmdsn);
3414 	}
3415 	/*
3416 	 * following the assumption, staged cmdsn >= expcmdsn, this statement
3417 	 * is never reached.
3418 	 */
3419 }
3420