1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  23  */
  24 /*
  25  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  26  */
  27 
  28 #include <sys/cpuvar.h>
  29 #include <sys/types.h>
  30 #include <sys/conf.h>
  31 #include <sys/stat.h>
  32 #include <sys/file.h>
  33 #include <sys/ddi.h>
  34 #include <sys/sunddi.h>
  35 #include <sys/modctl.h>
  36 #include <sys/sysmacros.h>
  37 #include <sys/socket.h>
  38 #include <sys/strsubr.h>
  39 #include <sys/nvpair.h>
  40 
  41 #include <sys/stmf.h>
  42 #include <sys/stmf_ioctl.h>
  43 #include <sys/portif.h>
  44 #include <sys/idm/idm.h>
  45 #include <sys/idm/idm_conn_sm.h>
  46 
  47 #include "iscsit_isns.h"
  48 #include "iscsit.h"
  49 
  50 #define ISCSIT_VERSION          BUILD_DATE "-1.18dev"
  51 #define ISCSIT_NAME_VERSION     "COMSTAR ISCSIT v" ISCSIT_VERSION
  52 
  53 /*
  54  * DDI entry points.
  55  */
  56 static int iscsit_drv_attach(dev_info_t *, ddi_attach_cmd_t);
  57 static int iscsit_drv_detach(dev_info_t *, ddi_detach_cmd_t);
  58 static int iscsit_drv_getinfo(dev_info_t *, ddi_info_cmd_t, void *, void **);
  59 static int iscsit_drv_open(dev_t *, int, int, cred_t *);
  60 static int iscsit_drv_close(dev_t, int, int, cred_t *);
  61 static boolean_t iscsit_drv_busy(void);
  62 static int iscsit_drv_ioctl(dev_t, int, intptr_t, int, cred_t *, int *);
  63 
  64 extern struct mod_ops mod_miscops;
  65 
  66 
  67 static struct cb_ops iscsit_cb_ops = {
  68         iscsit_drv_open,        /* cb_open */
  69         iscsit_drv_close,       /* cb_close */
  70         nodev,                  /* cb_strategy */
  71         nodev,                  /* cb_print */
  72         nodev,                  /* cb_dump */
  73         nodev,                  /* cb_read */
  74         nodev,                  /* cb_write */
  75         iscsit_drv_ioctl,       /* cb_ioctl */
  76         nodev,                  /* cb_devmap */
  77         nodev,                  /* cb_mmap */
  78         nodev,                  /* cb_segmap */
  79         nochpoll,               /* cb_chpoll */
  80         ddi_prop_op,            /* cb_prop_op */
  81         NULL,                   /* cb_streamtab */
  82         D_MP,                   /* cb_flag */
  83         CB_REV,                 /* cb_rev */
  84         nodev,                  /* cb_aread */
  85         nodev,                  /* cb_awrite */
  86 };
  87 
  88 static struct dev_ops iscsit_dev_ops = {
  89         DEVO_REV,               /* devo_rev */
  90         0,                      /* devo_refcnt */
  91         iscsit_drv_getinfo,     /* devo_getinfo */
  92         nulldev,                /* devo_identify */
  93         nulldev,                /* devo_probe */
  94         iscsit_drv_attach,      /* devo_attach */
  95         iscsit_drv_detach,      /* devo_detach */
  96         nodev,                  /* devo_reset */
  97         &iscsit_cb_ops,             /* devo_cb_ops */
  98         NULL,                   /* devo_bus_ops */
  99         NULL,                   /* devo_power */
 100         ddi_quiesce_not_needed, /* quiesce */
 101 };
 102 
 103 static struct modldrv modldrv = {
 104         &mod_driverops,
 105         "iSCSI Target",
 106         &iscsit_dev_ops,
 107 };
 108 
 109 static struct modlinkage modlinkage = {
 110         MODREV_1,
 111         &modldrv,
 112         NULL,
 113 };
 114 
 115 
 116 iscsit_global_t iscsit_global;
 117 
 118 kmem_cache_t    *iscsit_status_pdu_cache;
 119 
 120 boolean_t       iscsit_sm_logging = B_FALSE;
 121 
 122 kmutex_t        login_sm_session_mutex;
 123 
 124 static idm_status_t iscsit_init(dev_info_t *dip);
 125 static idm_status_t iscsit_enable_svc(iscsit_hostinfo_t *hostinfo);
 126 static void iscsit_disable_svc(void);
 127 
 128 static int
 129 iscsit_check_cmdsn_and_queue(idm_pdu_t *rx_pdu);
 130 
 131 static void
 132 iscsit_add_pdu_to_queue(iscsit_sess_t *ist, idm_pdu_t *rx_pdu);
 133 
 134 static idm_pdu_t *
 135 iscsit_remove_pdu_from_queue(iscsit_sess_t *ist, uint32_t cmdsn);
 136 
 137 static void
 138 iscsit_process_pdu_in_queue(iscsit_sess_t *ist);
 139 
 140 static void
 141 iscsit_rxpdu_queue_monitor_session(iscsit_sess_t *ist);
 142 
 143 static void
 144 iscsit_rxpdu_queue_monitor(void *arg);
 145 
 146 static void
 147 iscsit_post_staged_pdu(idm_pdu_t *rx_pdu);
 148 
 149 static void
 150 iscsit_post_scsi_cmd(idm_conn_t *ic, idm_pdu_t *rx_pdu);
 151 
 152 static void
 153 iscsit_op_scsi_task_mgmt(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
 154 
 155 static void
 156 iscsit_pdu_op_noop(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
 157 
 158 static void
 159 iscsit_pdu_op_login_cmd(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
 160 
 161 void
 162 iscsit_pdu_op_text_cmd(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
 163 
 164 static void
 165 iscsit_pdu_op_logout_cmd(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
 166 
 167 int iscsit_cmd_window();
 168 
 169 static  int
 170 iscsit_sna_lt(uint32_t sn1, uint32_t sn2);
 171 
 172 void
 173 iscsit_set_cmdsn(iscsit_conn_t *ict, idm_pdu_t *rx_pdu);
 174 
 175 static void
 176 iscsit_deferred_dispatch(idm_pdu_t *rx_pdu);
 177 
 178 static void
 179 iscsit_deferred(void *rx_pdu_void);
 180 
 181 static idm_status_t
 182 iscsit_conn_accept(idm_conn_t *ic);
 183 
 184 static idm_status_t
 185 iscsit_ffp_enabled(idm_conn_t *ic);
 186 
 187 static idm_status_t
 188 iscsit_ffp_disabled(idm_conn_t *ic, idm_ffp_disable_t disable_class);
 189 
 190 static idm_status_t
 191 iscsit_conn_lost(idm_conn_t *ic);
 192 
 193 static idm_status_t
 194 iscsit_conn_destroy(idm_conn_t *ic);
 195 
 196 static stmf_data_buf_t *
 197 iscsit_dbuf_alloc(scsi_task_t *task, uint32_t size, uint32_t *pminsize,
 198     uint32_t flags);
 199 
 200 static void
 201 iscsit_dbuf_free(stmf_dbuf_store_t *ds, stmf_data_buf_t *dbuf);
 202 
 203 static void
 204 iscsit_buf_xfer_cb(idm_buf_t *idb, idm_status_t status);
 205 
 206 static void
 207 iscsit_send_good_status_done(idm_pdu_t *pdu, idm_status_t status);
 208 
 209 static void
 210 iscsit_send_status_done(idm_pdu_t *pdu, idm_status_t status);
 211 
 212 static stmf_status_t
 213 iscsit_idm_to_stmf(idm_status_t idmrc);
 214 
 215 static iscsit_task_t *
 216 iscsit_task_alloc(iscsit_conn_t *ict);
 217 
 218 static void
 219 iscsit_task_free(iscsit_task_t *itask);
 220 
 221 static iscsit_task_t *
 222 iscsit_tm_task_alloc(iscsit_conn_t *ict);
 223 
 224 static void
 225 iscsit_tm_task_free(iscsit_task_t *itask);
 226 
 227 static idm_status_t
 228 iscsit_task_start(iscsit_task_t *itask);
 229 
 230 static void
 231 iscsit_task_done(iscsit_task_t *itask);
 232 
 233 static int
 234 iscsit_status_pdu_constructor(void *pdu_void, void *arg, int flags);
 235 
 236 static void
 237 iscsit_pp_cb(struct stmf_port_provider *pp, int cmd, void *arg, uint32_t flags);
 238 
 239 static it_cfg_status_t
 240 iscsit_config_merge(it_config_t *cfg);
 241 
 242 static idm_status_t
 243 iscsit_login_fail(idm_conn_t *ic);
 244 
 245 static boolean_t iscsit_cmdsn_in_window(iscsit_conn_t *ict, uint32_t cmdsn);
 246 static void iscsit_send_direct_scsi_resp(iscsit_conn_t *ict, idm_pdu_t *rx_pdu,
 247     uint8_t response, uint8_t cmd_status);
 248 static void iscsit_send_task_mgmt_resp(idm_pdu_t *tm_resp_pdu,
 249     uint8_t tm_status);
 250 
 251 /*
 252  * MC/S: Out-of-order commands are staged on a session-wide wait
 253  * queue until a system-tunable threshold is reached. A separate
 254  * thread is used to scan the staging queue on all the session,
 255  * If a delayed PDU does not arrive within a timeout, the target
 256  * will advance to the staged PDU that is next in sequence, skipping
 257  * over the missing PDU(s) to go past a hole in the sequence.
 258  */
 259 volatile int rxpdu_queue_threshold = ISCSIT_RXPDU_QUEUE_THRESHOLD;
 260 
 261 static kmutex_t         iscsit_rxpdu_queue_monitor_mutex;
 262 kthread_t               *iscsit_rxpdu_queue_monitor_thr_id;
 263 static kt_did_t         iscsit_rxpdu_queue_monitor_thr_did;
 264 static boolean_t        iscsit_rxpdu_queue_monitor_thr_running;
 265 static kcondvar_t       iscsit_rxpdu_queue_monitor_cv;
 266 
 267 int
 268 _init(void)
 269 {
 270         int rc;
 271 
 272         rw_init(&iscsit_global.global_rwlock, NULL, RW_DRIVER, NULL);
 273         mutex_init(&iscsit_global.global_state_mutex, NULL,
 274             MUTEX_DRIVER, NULL);
 275         iscsit_global.global_svc_state = ISE_DETACHED;
 276 
 277         mutex_init(&iscsit_rxpdu_queue_monitor_mutex, NULL,
 278             MUTEX_DRIVER, NULL);
 279         mutex_init(&login_sm_session_mutex, NULL, MUTEX_DRIVER, NULL);
 280         iscsit_rxpdu_queue_monitor_thr_id = NULL;
 281         iscsit_rxpdu_queue_monitor_thr_running = B_FALSE;
 282         cv_init(&iscsit_rxpdu_queue_monitor_cv, NULL, CV_DEFAULT, NULL);
 283 
 284         if ((rc = mod_install(&modlinkage)) != 0) {
 285                 mutex_destroy(&iscsit_global.global_state_mutex);
 286                 rw_destroy(&iscsit_global.global_rwlock);
 287                 return (rc);
 288         }
 289 
 290         return (rc);
 291 }
 292 
 293 int
 294 _info(struct modinfo *modinfop)
 295 {
 296         return (mod_info(&modlinkage, modinfop));
 297 }
 298 
 299 int
 300 _fini(void)
 301 {
 302         int rc;
 303 
 304         rc = mod_remove(&modlinkage);
 305 
 306         if (rc == 0) {
 307                 mutex_destroy(&iscsit_rxpdu_queue_monitor_mutex);
 308                 mutex_destroy(&login_sm_session_mutex);
 309                 cv_destroy(&iscsit_rxpdu_queue_monitor_cv);
 310                 mutex_destroy(&iscsit_global.global_state_mutex);
 311                 rw_destroy(&iscsit_global.global_rwlock);
 312         }
 313 
 314         return (rc);
 315 }
 316 
 317 /*
 318  * DDI entry points.
 319  */
 320 
 321 /* ARGSUSED */
 322 static int
 323 iscsit_drv_getinfo(dev_info_t *dip, ddi_info_cmd_t cmd, void *arg,
 324     void **result)
 325 {
 326         ulong_t instance = getminor((dev_t)arg);
 327 
 328         switch (cmd) {
 329         case DDI_INFO_DEVT2DEVINFO:
 330                 *result = iscsit_global.global_dip;
 331                 return (DDI_SUCCESS);
 332 
 333         case DDI_INFO_DEVT2INSTANCE:
 334                 *result = (void *)instance;
 335                 return (DDI_SUCCESS);
 336 
 337         default:
 338                 break;
 339         }
 340 
 341         return (DDI_FAILURE);
 342 }
 343 
 344 static int
 345 iscsit_drv_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
 346 {
 347         if (cmd != DDI_ATTACH) {
 348                 return (DDI_FAILURE);
 349         }
 350 
 351         if (ddi_get_instance(dip) != 0) {
 352                 /* we only allow instance 0 to attach */
 353                 return (DDI_FAILURE);
 354         }
 355 
 356         /* create the minor node */
 357         if (ddi_create_minor_node(dip, ISCSIT_MODNAME, S_IFCHR, 0,
 358             DDI_PSEUDO, 0) != DDI_SUCCESS) {
 359                 cmn_err(CE_WARN, "iscsit_drv_attach: "
 360                     "failed creating minor node");
 361                 return (DDI_FAILURE);
 362         }
 363 
 364         if (iscsit_init(dip) != IDM_STATUS_SUCCESS) {
 365                 cmn_err(CE_WARN, "iscsit_drv_attach: "
 366                     "failed to initialize");
 367                 ddi_remove_minor_node(dip, NULL);
 368                 return (DDI_FAILURE);
 369         }
 370 
 371         iscsit_global.global_svc_state = ISE_DISABLED;
 372         iscsit_global.global_dip = dip;
 373 
 374         return (DDI_SUCCESS);
 375 }
 376 
 377 /*ARGSUSED*/
 378 static int
 379 iscsit_drv_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
 380 {
 381         if (cmd != DDI_DETACH)
 382                 return (DDI_FAILURE);
 383 
 384         /*
 385          * drv_detach is called in a context that owns the
 386          * device node for the /dev/pseudo device.  If this thread blocks
 387          * for any resource, other threads that need the /dev/pseudo device
 388          * may end up in a deadlock with this thread.Hence, we use a
 389          * separate lock just for the structures that drv_detach needs
 390          * to access.
 391          */
 392         mutex_enter(&iscsit_global.global_state_mutex);
 393         if (iscsit_drv_busy()) {
 394                 mutex_exit(&iscsit_global.global_state_mutex);
 395                 return (EBUSY);
 396         }
 397 
 398         iscsit_global.global_dip = NULL;
 399         ddi_remove_minor_node(dip, NULL);
 400 
 401         ldi_ident_release(iscsit_global.global_li);
 402         iscsit_global.global_svc_state = ISE_DETACHED;
 403 
 404         mutex_exit(&iscsit_global.global_state_mutex);
 405 
 406         return (DDI_SUCCESS);
 407 }
 408 
 409 /*ARGSUSED*/
 410 static int
 411 iscsit_drv_open(dev_t *devp, int flag, int otyp, cred_t *credp)
 412 {
 413         return (0);
 414 }
 415 
 416 /* ARGSUSED */
 417 static int
 418 iscsit_drv_close(dev_t dev, int flag, int otyp, cred_t *credp)
 419 {
 420         return (0);
 421 }
 422 
 423 static boolean_t
 424 iscsit_drv_busy(void)
 425 {
 426         ASSERT(MUTEX_HELD(&iscsit_global.global_state_mutex));
 427 
 428         switch (iscsit_global.global_svc_state) {
 429         case ISE_DISABLED:
 430         case ISE_DETACHED:
 431                 return (B_FALSE);
 432         default:
 433                 return (B_TRUE);
 434         }
 435         /* NOTREACHED */
 436 }
 437 
 438 /* ARGSUSED */
 439 static int
 440 iscsit_drv_ioctl(dev_t drv, int cmd, intptr_t argp, int flag, cred_t *cred,
 441     int *retval)
 442 {
 443         iscsit_ioc_set_config_t         setcfg;
 444         iscsit_ioc_set_config32_t       setcfg32;
 445         char                            *cfg_pnvlist = NULL;
 446         nvlist_t                        *cfg_nvlist = NULL;
 447         it_config_t                     *cfg = NULL;
 448         idm_status_t                    idmrc;
 449         int                             rc = 0;
 450 
 451         if (drv_priv(cred) != 0) {
 452                 return (EPERM);
 453         }
 454 
 455         mutex_enter(&iscsit_global.global_state_mutex);
 456 
 457         /*
 458          * Validate ioctl requests against global service state
 459          */
 460         switch (iscsit_global.global_svc_state) {
 461         case ISE_ENABLED:
 462                 if (cmd == ISCSIT_IOC_DISABLE_SVC) {
 463                         iscsit_global.global_svc_state = ISE_DISABLING;
 464                 } else if (cmd == ISCSIT_IOC_ENABLE_SVC) {
 465                         /* Already enabled */
 466                         mutex_exit(&iscsit_global.global_state_mutex);
 467                         return (0);
 468                 } else {
 469                         iscsit_global.global_svc_state = ISE_BUSY;
 470                 }
 471                 break;
 472         case ISE_DISABLED:
 473                 if (cmd == ISCSIT_IOC_ENABLE_SVC) {
 474                         iscsit_global.global_svc_state = ISE_ENABLING;
 475                 } else if (cmd == ISCSIT_IOC_DISABLE_SVC) {
 476                         /* Already disabled */
 477                         mutex_exit(&iscsit_global.global_state_mutex);
 478                         return (0);
 479                 } else {
 480                         rc = EFAULT;
 481                 }
 482                 break;
 483         case ISE_BUSY:
 484         case ISE_ENABLING:
 485         case ISE_DISABLING:
 486                 rc = EAGAIN;
 487                 break;
 488         case ISE_DETACHED:
 489         default:
 490                 rc = EFAULT;
 491                 break;
 492         }
 493 
 494         mutex_exit(&iscsit_global.global_state_mutex);
 495         if (rc != 0)
 496                 return (rc);
 497 
 498         /* Handle ioctl request (enable/disable have already been handled) */
 499         switch (cmd) {
 500         case ISCSIT_IOC_SET_CONFIG:
 501                 /* Any errors must set state back to ISE_ENABLED */
 502                 switch (ddi_model_convert_from(flag & FMODELS)) {
 503                 case DDI_MODEL_ILP32:
 504                         if (ddi_copyin((void *)argp, &setcfg32,
 505                             sizeof (iscsit_ioc_set_config32_t), flag) != 0) {
 506                                 rc = EFAULT;
 507                                 goto cleanup;
 508                         }
 509 
 510                         setcfg.set_cfg_pnvlist =
 511                             (char *)((uintptr_t)setcfg32.set_cfg_pnvlist);
 512                         setcfg.set_cfg_vers = setcfg32.set_cfg_vers;
 513                         setcfg.set_cfg_pnvlist_len =
 514                             setcfg32.set_cfg_pnvlist_len;
 515                         break;
 516                 case DDI_MODEL_NONE:
 517                         if (ddi_copyin((void *)argp, &setcfg,
 518                             sizeof (iscsit_ioc_set_config_t), flag) != 0) {
 519                                 rc = EFAULT;
 520                                 goto cleanup;
 521                         }
 522                         break;
 523                 default:
 524                         rc = EFAULT;
 525                         goto cleanup;
 526                 }
 527 
 528                 /* Check API version */
 529                 if (setcfg.set_cfg_vers != ISCSIT_API_VERS0) {
 530                         rc = EINVAL;
 531                         goto cleanup;
 532                 }
 533 
 534                 /* Config is in packed nvlist format so unpack it */
 535                 cfg_pnvlist = kmem_alloc(setcfg.set_cfg_pnvlist_len,
 536                     KM_SLEEP);
 537                 ASSERT(cfg_pnvlist != NULL);
 538 
 539                 if (ddi_copyin(setcfg.set_cfg_pnvlist, cfg_pnvlist,
 540                     setcfg.set_cfg_pnvlist_len, flag) != 0) {
 541                         rc = EFAULT;
 542                         goto cleanup;
 543                 }
 544 
 545                 rc = nvlist_unpack(cfg_pnvlist, setcfg.set_cfg_pnvlist_len,
 546                     &cfg_nvlist, KM_SLEEP);
 547                 if (rc != 0) {
 548                         goto cleanup;
 549                 }
 550 
 551                 /* Translate nvlist */
 552                 rc = it_nv_to_config(cfg_nvlist, &cfg);
 553                 if (rc != 0) {
 554                         cmn_err(CE_WARN, "Configuration is invalid");
 555                         goto cleanup;
 556                 }
 557 
 558                 /* Update config */
 559                 rc = iscsit_config_merge(cfg);
 560                 /* FALLTHROUGH */
 561 
 562 cleanup:
 563                 if (cfg)
 564                         it_config_free_cmn(cfg);
 565                 if (cfg_pnvlist)
 566                         kmem_free(cfg_pnvlist, setcfg.set_cfg_pnvlist_len);
 567                 if (cfg_nvlist)
 568                         nvlist_free(cfg_nvlist);
 569 
 570                 /*
 571                  * Now that the reconfig is complete set our state back to
 572                  * enabled.
 573                  */
 574                 mutex_enter(&iscsit_global.global_state_mutex);
 575                 iscsit_global.global_svc_state = ISE_ENABLED;
 576                 mutex_exit(&iscsit_global.global_state_mutex);
 577                 break;
 578         case ISCSIT_IOC_ENABLE_SVC: {
 579                 iscsit_hostinfo_t hostinfo;
 580 
 581                 if (ddi_copyin((void *)argp, &hostinfo.length,
 582                     sizeof (hostinfo.length), flag) != 0) {
 583                         mutex_enter(&iscsit_global.global_state_mutex);
 584                         iscsit_global.global_svc_state = ISE_DISABLED;
 585                         mutex_exit(&iscsit_global.global_state_mutex);
 586                         return (EFAULT);
 587                 }
 588 
 589                 if (hostinfo.length > sizeof (hostinfo.fqhn))
 590                         hostinfo.length = sizeof (hostinfo.fqhn);
 591 
 592                 if (ddi_copyin((void *)((caddr_t)argp +
 593                     sizeof (hostinfo.length)), &hostinfo.fqhn,
 594                     hostinfo.length, flag) != 0) {
 595                         mutex_enter(&iscsit_global.global_state_mutex);
 596                         iscsit_global.global_svc_state = ISE_DISABLED;
 597                         mutex_exit(&iscsit_global.global_state_mutex);
 598                         return (EFAULT);
 599                 }
 600 
 601                 idmrc = iscsit_enable_svc(&hostinfo);
 602                 mutex_enter(&iscsit_global.global_state_mutex);
 603                 if (idmrc == IDM_STATUS_SUCCESS) {
 604                         iscsit_global.global_svc_state = ISE_ENABLED;
 605                 } else {
 606                         rc = EIO;
 607                         iscsit_global.global_svc_state = ISE_DISABLED;
 608                 }
 609                 mutex_exit(&iscsit_global.global_state_mutex);
 610                 break;
 611         }
 612         case ISCSIT_IOC_DISABLE_SVC:
 613                 iscsit_disable_svc();
 614                 mutex_enter(&iscsit_global.global_state_mutex);
 615                 iscsit_global.global_svc_state = ISE_DISABLED;
 616                 mutex_exit(&iscsit_global.global_state_mutex);
 617                 break;
 618 
 619         default:
 620                 rc = EINVAL;
 621                 mutex_enter(&iscsit_global.global_state_mutex);
 622                 iscsit_global.global_svc_state = ISE_ENABLED;
 623                 mutex_exit(&iscsit_global.global_state_mutex);
 624         }
 625 
 626         return (rc);
 627 }
 628 
 629 static idm_status_t
 630 iscsit_init(dev_info_t *dip)
 631 {
 632         int                     rc;
 633 
 634         rc = ldi_ident_from_dip(dip, &iscsit_global.global_li);
 635         ASSERT(rc == 0);  /* Failure indicates invalid argument */
 636 
 637         iscsit_global.global_svc_state = ISE_DISABLED;
 638 
 639         return (IDM_STATUS_SUCCESS);
 640 }
 641 
 642 /*
 643  * iscsit_enable_svc
 644  *
 645  * registers all the configured targets and target portals with STMF
 646  */
 647 static idm_status_t
 648 iscsit_enable_svc(iscsit_hostinfo_t *hostinfo)
 649 {
 650         stmf_port_provider_t    *pp;
 651         stmf_dbuf_store_t       *dbuf_store;
 652         boolean_t               did_iscsit_isns_init;
 653         idm_status_t            retval = IDM_STATUS_SUCCESS;
 654 
 655         ASSERT(iscsit_global.global_svc_state == ISE_ENABLING);
 656 
 657         /*
 658          * Make sure that can tell if we have partially allocated
 659          * in case we need to exit and tear down anything allocated.
 660          */
 661         iscsit_global.global_tsih_pool = NULL;
 662         iscsit_global.global_dbuf_store = NULL;
 663         iscsit_status_pdu_cache = NULL;
 664         pp = NULL;
 665         iscsit_global.global_pp = NULL;
 666         iscsit_global.global_default_tpg = NULL;
 667         did_iscsit_isns_init = B_FALSE;
 668         iscsit_global.global_dispatch_taskq = NULL;
 669 
 670         /* Setup remaining fields in iscsit_global_t */
 671         idm_refcnt_init(&iscsit_global.global_refcnt,
 672             &iscsit_global);
 673 
 674         avl_create(&iscsit_global.global_discovery_sessions,
 675             iscsit_sess_avl_compare, sizeof (iscsit_sess_t),
 676             offsetof(iscsit_sess_t, ist_tgt_ln));
 677 
 678         avl_create(&iscsit_global.global_target_list,
 679             iscsit_tgt_avl_compare, sizeof (iscsit_tgt_t),
 680             offsetof(iscsit_tgt_t, target_global_ln));
 681 
 682         list_create(&iscsit_global.global_deleted_target_list,
 683             sizeof (iscsit_tgt_t),
 684             offsetof(iscsit_tgt_t, target_global_deleted_ln));
 685 
 686         avl_create(&iscsit_global.global_tpg_list,
 687             iscsit_tpg_avl_compare, sizeof (iscsit_tpg_t),
 688             offsetof(iscsit_tpg_t, tpg_global_ln));
 689 
 690         avl_create(&iscsit_global.global_ini_list,
 691             iscsit_ini_avl_compare, sizeof (iscsit_ini_t),
 692             offsetof(iscsit_ini_t, ini_global_ln));
 693 
 694         iscsit_global.global_tsih_pool = vmem_create("iscsit_tsih_pool",
 695             (void *)1, ISCSI_MAX_TSIH, 1, NULL, NULL, NULL, 0,
 696             VM_SLEEP | VMC_IDENTIFIER);
 697 
 698         /*
 699          * Setup STMF dbuf store.  Our buffers are bound to a specific
 700          * connection so we really can't let STMF cache buffers for us.
 701          * Consequently we'll just allocate one global buffer store.
 702          */
 703         dbuf_store = stmf_alloc(STMF_STRUCT_DBUF_STORE, 0, 0);
 704         if (dbuf_store == NULL) {
 705                 retval = IDM_STATUS_FAIL;
 706                 goto tear_down_and_return;
 707         }
 708         dbuf_store->ds_alloc_data_buf = iscsit_dbuf_alloc;
 709         dbuf_store->ds_free_data_buf = iscsit_dbuf_free;
 710         dbuf_store->ds_port_private = NULL;
 711         iscsit_global.global_dbuf_store = dbuf_store;
 712 
 713         /* Status PDU cache */
 714         iscsit_status_pdu_cache = kmem_cache_create("iscsit_status_pdu_cache",
 715             sizeof (idm_pdu_t) + sizeof (iscsi_scsi_rsp_hdr_t), 8,
 716             &iscsit_status_pdu_constructor,
 717             NULL, NULL, NULL, NULL, KM_SLEEP);
 718 
 719         /* Default TPG and portal */
 720         iscsit_global.global_default_tpg = iscsit_tpg_createdefault();
 721         if (iscsit_global.global_default_tpg == NULL) {
 722                 retval = IDM_STATUS_FAIL;
 723                 goto tear_down_and_return;
 724         }
 725 
 726         /* initialize isns client */
 727         (void) iscsit_isns_init(hostinfo);
 728         did_iscsit_isns_init = B_TRUE;
 729 
 730         /* Register port provider */
 731         pp = stmf_alloc(STMF_STRUCT_PORT_PROVIDER, 0, 0);
 732         if (pp == NULL) {
 733                 retval = IDM_STATUS_FAIL;
 734                 goto tear_down_and_return;
 735         }
 736 
 737         pp->pp_portif_rev = PORTIF_REV_1;
 738         pp->pp_instance = 0;
 739         pp->pp_name = ISCSIT_MODNAME;
 740         pp->pp_cb = iscsit_pp_cb;
 741 
 742         iscsit_global.global_pp = pp;
 743 
 744 
 745         if (stmf_register_port_provider(pp) != STMF_SUCCESS) {
 746                 retval = IDM_STATUS_FAIL;
 747                 goto tear_down_and_return;
 748         }
 749 
 750         iscsit_global.global_dispatch_taskq = taskq_create("iscsit_dispatch",
 751             1, minclsyspri, 16, 16, TASKQ_PREPOPULATE);
 752 
 753         /* Scan staged PDUs, meaningful in MC/S situations */
 754         iscsit_rxpdu_queue_monitor_start();
 755 
 756         return (IDM_STATUS_SUCCESS);
 757 
 758 tear_down_and_return:
 759 
 760         if (iscsit_global.global_dispatch_taskq) {
 761                 taskq_destroy(iscsit_global.global_dispatch_taskq);
 762                 iscsit_global.global_dispatch_taskq = NULL;
 763         }
 764 
 765         if (did_iscsit_isns_init)
 766                 iscsit_isns_fini();
 767 
 768         if (iscsit_global.global_default_tpg) {
 769                 iscsit_tpg_destroydefault(iscsit_global.global_default_tpg);
 770                 iscsit_global.global_default_tpg = NULL;
 771         }
 772 
 773         if (iscsit_global.global_pp)
 774                 iscsit_global.global_pp = NULL;
 775 
 776         if (pp)
 777                 stmf_free(pp);
 778 
 779         if (iscsit_status_pdu_cache) {
 780                 kmem_cache_destroy(iscsit_status_pdu_cache);
 781                 iscsit_status_pdu_cache = NULL;
 782         }
 783 
 784         if (iscsit_global.global_dbuf_store) {
 785                 stmf_free(iscsit_global.global_dbuf_store);
 786                 iscsit_global.global_dbuf_store = NULL;
 787         }
 788 
 789         if (iscsit_global.global_tsih_pool) {
 790                 vmem_destroy(iscsit_global.global_tsih_pool);
 791                 iscsit_global.global_tsih_pool = NULL;
 792         }
 793 
 794         avl_destroy(&iscsit_global.global_ini_list);
 795         avl_destroy(&iscsit_global.global_tpg_list);
 796         list_destroy(&iscsit_global.global_deleted_target_list);
 797         avl_destroy(&iscsit_global.global_target_list);
 798         avl_destroy(&iscsit_global.global_discovery_sessions);
 799 
 800         idm_refcnt_destroy(&iscsit_global.global_refcnt);
 801 
 802         return (retval);
 803 }
 804 
 805 /*
 806  * iscsit_disable_svc
 807  *
 808  * clean up all existing connections and deregister targets from STMF
 809  */
 810 static void
 811 iscsit_disable_svc(void)
 812 {
 813         iscsit_sess_t   *sess;
 814 
 815         ASSERT(iscsit_global.global_svc_state == ISE_DISABLING);
 816 
 817         iscsit_rxpdu_queue_monitor_stop();
 818 
 819         /* tear down discovery sessions */
 820         for (sess = avl_first(&iscsit_global.global_discovery_sessions);
 821             sess != NULL;
 822             sess = AVL_NEXT(&iscsit_global.global_discovery_sessions, sess))
 823                 iscsit_sess_close(sess);
 824 
 825         /*
 826          * Passing NULL to iscsit_config_merge tells it to go to an empty
 827          * config.
 828          */
 829         (void) iscsit_config_merge(NULL);
 830 
 831         /*
 832          * Wait until there are no more global references
 833          */
 834         idm_refcnt_wait_ref(&iscsit_global.global_refcnt);
 835         idm_refcnt_destroy(&iscsit_global.global_refcnt);
 836 
 837         /*
 838          * Default TPG must be destroyed after global_refcnt is 0.
 839          */
 840         iscsit_tpg_destroydefault(iscsit_global.global_default_tpg);
 841 
 842         avl_destroy(&iscsit_global.global_discovery_sessions);
 843         list_destroy(&iscsit_global.global_deleted_target_list);
 844         avl_destroy(&iscsit_global.global_target_list);
 845         avl_destroy(&iscsit_global.global_tpg_list);
 846         avl_destroy(&iscsit_global.global_ini_list);
 847 
 848         taskq_destroy(iscsit_global.global_dispatch_taskq);
 849 
 850         iscsit_isns_fini();
 851 
 852         stmf_free(iscsit_global.global_dbuf_store);
 853         iscsit_global.global_dbuf_store = NULL;
 854 
 855         (void) stmf_deregister_port_provider(iscsit_global.global_pp);
 856         stmf_free(iscsit_global.global_pp);
 857         iscsit_global.global_pp = NULL;
 858 
 859         kmem_cache_destroy(iscsit_status_pdu_cache);
 860         iscsit_status_pdu_cache = NULL;
 861 
 862         vmem_destroy(iscsit_global.global_tsih_pool);
 863         iscsit_global.global_tsih_pool = NULL;
 864 }
 865 
 866 void
 867 iscsit_global_hold()
 868 {
 869         /*
 870          * To take out a global hold, we must either own the global
 871          * state mutex or we must be running inside of an ioctl that
 872          * has set the global state to ISE_BUSY, ISE_DISABLING, or
 873          * ISE_ENABLING.  We don't track the "owner" for these flags,
 874          * so just checking if they are set is enough for now.
 875          */
 876         ASSERT((iscsit_global.global_svc_state == ISE_ENABLING) ||
 877             (iscsit_global.global_svc_state == ISE_DISABLING) ||
 878             (iscsit_global.global_svc_state == ISE_BUSY) ||
 879             MUTEX_HELD(&iscsit_global.global_state_mutex));
 880 
 881         idm_refcnt_hold(&iscsit_global.global_refcnt);
 882 }
 883 
 884 void
 885 iscsit_global_rele()
 886 {
 887         idm_refcnt_rele(&iscsit_global.global_refcnt);
 888 }
 889 
 890 void
 891 iscsit_global_wait_ref()
 892 {
 893         idm_refcnt_wait_ref(&iscsit_global.global_refcnt);
 894 }
 895 
 896 /*
 897  * IDM callbacks
 898  */
 899 
 900 /*ARGSUSED*/
 901 void
 902 iscsit_rx_pdu(idm_conn_t *ic, idm_pdu_t *rx_pdu)
 903 {
 904         iscsit_conn_t *ict = ic->ic_handle;
 905         switch (IDM_PDU_OPCODE(rx_pdu)) {
 906         case ISCSI_OP_SCSI_CMD:
 907                 ASSERT(0); /* Shouldn't happen */
 908                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
 909                 break;
 910         case ISCSI_OP_SNACK_CMD:
 911                 /*
 912                  * We'll need to handle this when we support ERL1/2.  For
 913                  * now we treat it as a protocol error.
 914                  */
 915                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
 916                 idm_conn_event(ic, CE_TRANSPORT_FAIL, NULL);
 917                 break;
 918         case ISCSI_OP_SCSI_TASK_MGT_MSG:
 919                 if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
 920                         iscsit_set_cmdsn(ict, rx_pdu);
 921                         iscsit_op_scsi_task_mgmt(ict, rx_pdu);
 922                 }
 923                 break;
 924         case ISCSI_OP_NOOP_OUT:
 925         case ISCSI_OP_LOGIN_CMD:
 926         case ISCSI_OP_TEXT_CMD:
 927         case ISCSI_OP_LOGOUT_CMD:
 928                 /*
 929                  * If/when we switch to userland processing these PDU's
 930                  * will be handled by iscsitd.
 931                  */
 932                 iscsit_deferred_dispatch(rx_pdu);
 933                 break;
 934         default:
 935                 /* Protocol error */
 936                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
 937                 idm_conn_event(ic, CE_TRANSPORT_FAIL, NULL);
 938                 break;
 939         }
 940 }
 941 
 942 /*ARGSUSED*/
 943 void
 944 iscsit_rx_pdu_error(idm_conn_t *ic, idm_pdu_t *rx_pdu, idm_status_t status)
 945 {
 946         idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
 947 }
 948 
 949 void
 950 iscsit_task_aborted(idm_task_t *idt, idm_status_t status)
 951 {
 952         iscsit_task_t *itask = idt->idt_private;
 953 
 954         switch (status) {
 955         case IDM_STATUS_SUSPENDED:
 956                 break;
 957         case IDM_STATUS_ABORTED:
 958                 mutex_enter(&itask->it_mutex);
 959                 itask->it_aborted = B_TRUE;
 960                 /*
 961                  * We rely on the fact that STMF tracks outstanding
 962                  * buffer transfers and will free all of our buffers
 963                  * before freeing the task so we don't need to
 964                  * explicitly free the buffers from iscsit/idm
 965                  */
 966                 if (itask->it_stmf_abort) {
 967                         mutex_exit(&itask->it_mutex);
 968                         /*
 969                          * Task is no longer active
 970                          */
 971                         iscsit_task_done(itask);
 972 
 973                         /*
 974                          * STMF has already asked for this task to be aborted
 975                          *
 976                          * STMF specification is wrong... says to return
 977                          * STMF_ABORTED, the code actually looks for
 978                          * STMF_ABORT_SUCCESS.
 979                          */
 980                         stmf_task_lport_aborted(itask->it_stmf_task,
 981                             STMF_ABORT_SUCCESS, STMF_IOF_LPORT_DONE);
 982                         return;
 983                 } else {
 984                         mutex_exit(&itask->it_mutex);
 985                         /*
 986                          * Tell STMF to stop processing the task.
 987                          */
 988                         stmf_abort(STMF_QUEUE_TASK_ABORT, itask->it_stmf_task,
 989                             STMF_ABORTED, NULL);
 990                         return;
 991                 }
 992                 /*NOTREACHED*/
 993         default:
 994                 ASSERT(0);
 995         }
 996 }
 997 
 998 /*ARGSUSED*/
 999 idm_status_t
1000 iscsit_client_notify(idm_conn_t *ic, idm_client_notify_t icn,
1001     uintptr_t data)
1002 {
1003         idm_status_t rc = IDM_STATUS_SUCCESS;
1004 
1005         /*
1006          * IDM client notifications will never occur at interrupt level
1007          * since they are generated from the connection state machine which
1008          * running on taskq threads.
1009          *
1010          */
1011         switch (icn) {
1012         case CN_CONNECT_ACCEPT:
1013                 rc = iscsit_conn_accept(ic); /* No data */
1014                 break;
1015         case CN_FFP_ENABLED:
1016                 rc = iscsit_ffp_enabled(ic); /* No data */
1017                 break;
1018         case CN_FFP_DISABLED:
1019                 /*
1020                  * Data indicates whether this was the result of an
1021                  * explicit logout request.
1022                  */
1023                 rc = iscsit_ffp_disabled(ic, (idm_ffp_disable_t)data);
1024                 break;
1025         case CN_CONNECT_LOST:
1026                 rc = iscsit_conn_lost(ic);
1027                 break;
1028         case CN_CONNECT_DESTROY:
1029                 rc = iscsit_conn_destroy(ic);
1030                 break;
1031         case CN_LOGIN_FAIL:
1032                 /*
1033                  * Force the login state machine to completion
1034                  */
1035                 rc = iscsit_login_fail(ic);
1036                 break;
1037         default:
1038                 rc = IDM_STATUS_REJECT;
1039                 break;
1040         }
1041 
1042         return (rc);
1043 }
1044 
1045 /*
1046  * iscsit_update_statsn is invoked for all the PDUs which have the StatSN
1047  * field in the header. The StatSN is incremented if the IDM_PDU_ADVANCE_STATSN
1048  * flag is set in the pdu flags field. The StatSN is connection-wide and is
1049  * protected by the mutex ict_statsn_mutex. For Data-In PDUs, if the flag
1050  * IDM_TASK_PHASECOLLAPSE_REQ is set, the status (phase-collapse) is also filled
1051  */
1052 void
1053 iscsit_update_statsn(idm_task_t *idm_task, idm_pdu_t *pdu)
1054 {
1055         iscsi_scsi_rsp_hdr_t *rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
1056         iscsit_conn_t *ict = (iscsit_conn_t *)pdu->isp_ic->ic_handle;
1057         iscsit_task_t *itask = NULL;
1058         scsi_task_t *task = NULL;
1059 
1060         mutex_enter(&ict->ict_statsn_mutex);
1061         rsp->statsn = htonl(ict->ict_statsn);
1062         if (pdu->isp_flags & IDM_PDU_ADVANCE_STATSN)
1063                 ict->ict_statsn++;
1064         mutex_exit(&ict->ict_statsn_mutex);
1065 
1066         /*
1067          * The last SCSI Data PDU passed for a command may also contain the
1068          * status if the status indicates termination with no expections, i.e.
1069          * no sense data or response involved. If the command completes with
1070          * an error, then the response and sense data will be sent in a
1071          * separate iSCSI Response PDU.
1072          */
1073         if ((idm_task) && (idm_task->idt_flags & IDM_TASK_PHASECOLLAPSE_REQ)) {
1074                 itask = idm_task->idt_private;
1075                 task = itask->it_stmf_task;
1076 
1077                 rsp->cmd_status = task->task_scsi_status;
1078                 rsp->flags   |= ISCSI_FLAG_DATA_STATUS;
1079                 if (task->task_status_ctrl & TASK_SCTRL_OVER) {
1080                         rsp->flags |= ISCSI_FLAG_CMD_OVERFLOW;
1081                 } else if (task->task_status_ctrl & TASK_SCTRL_UNDER) {
1082                         rsp->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
1083                 }
1084                 rsp->residual_count = htonl(task->task_resid);
1085 
1086                 /*
1087                  * Removing the task from the session task list
1088                  * just before the status is sent in the last
1089                  * Data PDU transfer
1090                  */
1091                 iscsit_task_done(itask);
1092         }
1093 }
1094 
1095 void
1096 iscsit_build_hdr(idm_task_t *idm_task, idm_pdu_t *pdu, uint8_t opcode)
1097 {
1098         iscsit_task_t *itask = idm_task->idt_private;
1099         iscsi_data_rsp_hdr_t *dh = (iscsi_data_rsp_hdr_t *)pdu->isp_hdr;
1100 
1101         /*
1102          * We acquired iscsit_sess_t.ist_sn_mutex in iscsit_xfer_scsi_data
1103          */
1104         ASSERT(MUTEX_HELD(&itask->it_ict->ict_sess->ist_sn_mutex));
1105         /*
1106          * On incoming data, the target transfer tag and Lun is only
1107          * provided by the target if the A bit is set, Since the target
1108          * does not currently support Error Recovery Level 1, the A
1109          * bit is never set.
1110          */
1111         dh->opcode = opcode;
1112         dh->itt = itask->it_itt;
1113         dh->ttt = ((opcode & ISCSI_OPCODE_MASK) == ISCSI_OP_SCSI_DATA_RSP) ?
1114             ISCSI_RSVD_TASK_TAG : itask->it_ttt;
1115 
1116         dh->expcmdsn = htonl(itask->it_ict->ict_sess->ist_expcmdsn);
1117         dh->maxcmdsn = htonl(itask->it_ict->ict_sess->ist_maxcmdsn);
1118 
1119         /*
1120          * IDM must set:
1121          *
1122          * data.flags and rtt.flags
1123          * data.dlength
1124          * data.datasn
1125          * data.offset
1126          * statsn, residual_count and cmd_status (for phase collapse)
1127          * rtt.rttsn
1128          * rtt.data_offset
1129          * rtt.data_length
1130          */
1131 }
1132 
1133 void
1134 iscsit_keepalive(idm_conn_t *ic)
1135 {
1136         idm_pdu_t               *nop_in_pdu;
1137         iscsi_nop_in_hdr_t      *nop_in;
1138         iscsit_conn_t           *ict = ic->ic_handle;
1139 
1140         /*
1141          * IDM noticed the connection has been idle for too long so it's
1142          * time to provoke some activity.  Build and transmit an iSCSI
1143          * nop-in PDU -- when the initiator responds it will be counted
1144          * as "activity" and keep the connection alive.
1145          *
1146          * We don't actually care about the response here at the iscsit level
1147          * so we will just throw it away without looking at it when it arrives.
1148          */
1149         nop_in_pdu = idm_pdu_alloc(sizeof (*nop_in), 0);
1150         idm_pdu_init(nop_in_pdu, ic, NULL, NULL);
1151         nop_in = (iscsi_nop_in_hdr_t *)nop_in_pdu->isp_hdr;
1152         bzero(nop_in, sizeof (*nop_in));
1153         nop_in->opcode = ISCSI_OP_NOOP_IN;
1154         nop_in->flags = ISCSI_FLAG_FINAL;
1155         nop_in->itt = ISCSI_RSVD_TASK_TAG;
1156         /*
1157          * When the target sends a NOP-In as a Ping, the target transfer tag
1158          * is set to a valid (not reserved) value and the initiator task tag
1159          * is set to ISCSI_RSVD_TASK_TAG (0xffffffff). In this case the StatSN
1160          * will always contain the next sequence number but the StatSN for the
1161          * connection is not advanced after this PDU is sent.
1162          */
1163         nop_in_pdu->isp_flags |= IDM_PDU_SET_STATSN;
1164         /*
1165          * This works because we don't currently allocate ttt's anywhere else
1166          * in iscsit so as long as we stay out of IDM's range we are safe.
1167          * If we need to allocate ttt's for other PDU's in the future this will
1168          * need to be improved.
1169          */
1170         mutex_enter(&ict->ict_mutex);
1171         nop_in->ttt = ict->ict_keepalive_ttt;
1172         ict->ict_keepalive_ttt++;
1173         if (ict->ict_keepalive_ttt == ISCSI_RSVD_TASK_TAG)
1174                 ict->ict_keepalive_ttt = IDM_TASKIDS_MAX;
1175         mutex_exit(&ict->ict_mutex);
1176 
1177         iscsit_pdu_tx(nop_in_pdu);
1178 }
1179 
1180 static idm_status_t
1181 iscsit_conn_accept(idm_conn_t *ic)
1182 {
1183         iscsit_conn_t *ict;
1184 
1185         /*
1186          * We need to get a global hold here to ensure that the service
1187          * doesn't get shutdown prior to establishing a session. This
1188          * gets released in iscsit_conn_destroy().
1189          */
1190         mutex_enter(&iscsit_global.global_state_mutex);
1191         if (iscsit_global.global_svc_state != ISE_ENABLED) {
1192                 mutex_exit(&iscsit_global.global_state_mutex);
1193                 return (IDM_STATUS_FAIL);
1194         }
1195         iscsit_global_hold();
1196         mutex_exit(&iscsit_global.global_state_mutex);
1197 
1198         /*
1199          * Allocate an associated iscsit structure to represent this
1200          * connection.  We shouldn't really create a session until we
1201          * get the first login PDU.
1202          */
1203         ict = kmem_zalloc(sizeof (*ict), KM_SLEEP);
1204 
1205         ict->ict_ic = ic;
1206         ict->ict_statsn = 1;
1207         ict->ict_keepalive_ttt = IDM_TASKIDS_MAX; /* Avoid IDM TT range */
1208         ic->ic_handle = ict;
1209         mutex_init(&ict->ict_mutex, NULL, MUTEX_DRIVER, NULL);
1210         mutex_init(&ict->ict_statsn_mutex, NULL, MUTEX_DRIVER, NULL);
1211         idm_refcnt_init(&ict->ict_refcnt, ict);
1212 
1213         /*
1214          * Initialize login state machine
1215          */
1216         if (iscsit_login_sm_init(ict) != IDM_STATUS_SUCCESS) {
1217                 iscsit_global_rele();
1218                 /*
1219                  * Cleanup the ict after idm notifies us about this failure
1220                  */
1221                 return (IDM_STATUS_FAIL);
1222         }
1223 
1224         return (IDM_STATUS_SUCCESS);
1225 }
1226 
1227 idm_status_t
1228 iscsit_conn_reinstate(iscsit_conn_t *reinstate_ict, iscsit_conn_t *new_ict)
1229 {
1230         idm_status_t    result;
1231 
1232         /*
1233          * Note in new connection state that this connection is
1234          * reinstating an existing connection.
1235          */
1236         new_ict->ict_reinstating = B_TRUE;
1237         new_ict->ict_reinstate_conn = reinstate_ict;
1238         new_ict->ict_statsn = reinstate_ict->ict_statsn;
1239 
1240         /*
1241          * Now generate connection state machine event to existing connection
1242          * so that it starts the cleanup process.
1243          */
1244         result = idm_conn_reinstate_event(reinstate_ict->ict_ic,
1245             new_ict->ict_ic);
1246 
1247         return (result);
1248 }
1249 
1250 void
1251 iscsit_conn_hold(iscsit_conn_t *ict)
1252 {
1253         idm_refcnt_hold(&ict->ict_refcnt);
1254 }
1255 
1256 void
1257 iscsit_conn_rele(iscsit_conn_t *ict)
1258 {
1259         idm_refcnt_rele(&ict->ict_refcnt);
1260 }
1261 
1262 void
1263 iscsit_conn_dispatch_hold(iscsit_conn_t *ict)
1264 {
1265         idm_refcnt_hold(&ict->ict_dispatch_refcnt);
1266 }
1267 
1268 void
1269 iscsit_conn_dispatch_rele(iscsit_conn_t *ict)
1270 {
1271         idm_refcnt_rele(&ict->ict_dispatch_refcnt);
1272 }
1273 
1274 static idm_status_t
1275 iscsit_login_fail(idm_conn_t *ic)
1276 {
1277         iscsit_conn_t *ict = ic->ic_handle;
1278 
1279         /* Generate login state machine event */
1280         iscsit_login_sm_event(ict, ILE_LOGIN_CONN_ERROR, NULL);
1281 
1282         return (IDM_STATUS_SUCCESS);
1283 }
1284 
1285 static idm_status_t
1286 iscsit_ffp_enabled(idm_conn_t *ic)
1287 {
1288         iscsit_conn_t *ict = ic->ic_handle;
1289 
1290         /* Generate session state machine event */
1291         iscsit_sess_sm_event(ict->ict_sess, SE_CONN_LOGGED_IN, ict);
1292 
1293         return (IDM_STATUS_SUCCESS);
1294 }
1295 
1296 static idm_status_t
1297 iscsit_ffp_disabled(idm_conn_t *ic, idm_ffp_disable_t disable_class)
1298 {
1299         iscsit_conn_t *ict = ic->ic_handle;
1300 
1301         /* Generate session state machine event */
1302         switch (disable_class) {
1303         case FD_CONN_FAIL:
1304                 iscsit_sess_sm_event(ict->ict_sess, SE_CONN_FFP_FAIL, ict);
1305                 break;
1306         case FD_CONN_LOGOUT:
1307                 iscsit_sess_sm_event(ict->ict_sess, SE_CONN_FFP_DISABLE, ict);
1308                 break;
1309         case FD_SESS_LOGOUT:
1310                 iscsit_sess_sm_event(ict->ict_sess, SE_SESSION_CLOSE, ict);
1311                 break;
1312         default:
1313                 ASSERT(0);
1314         }
1315 
1316         return (IDM_STATUS_SUCCESS);
1317 }
1318 
1319 static idm_status_t
1320 iscsit_conn_lost(idm_conn_t *ic)
1321 {
1322         iscsit_conn_t   *ict    = ic->ic_handle;
1323         iscsit_sess_t   *ist    = ict->ict_sess;
1324         iscsit_cbuf_t   *cbuf;
1325         idm_pdu_t       *rx_pdu;
1326         int i;
1327 
1328         mutex_enter(&ict->ict_mutex);
1329         ict->ict_lost = B_TRUE;
1330         mutex_exit(&ict->ict_mutex);
1331         /*
1332          * scrub the staging queue for all PDUs on this connection
1333          */
1334         if (ist != NULL) {
1335                 mutex_enter(&ist->ist_sn_mutex);
1336                 for (cbuf = ist->ist_rxpdu_queue, i = 0;
1337                     ((cbuf->cb_num_elems > 0) && (i < ISCSIT_RXPDU_QUEUE_LEN));
1338                     i++) {
1339                         if (((rx_pdu = cbuf->cb_buffer[i]) != NULL) &&
1340                             (rx_pdu->isp_ic == ic)) {
1341                                 /* conn is lost, drop the pdu */
1342                                 DTRACE_PROBE3(scrubbing__staging__queue,
1343                                     iscsit_sess_t *, ist, idm_conn_t *, ic,
1344                                     idm_pdu_t *, rx_pdu);
1345                                 idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
1346                                 cbuf->cb_buffer[i] = NULL;
1347                                 cbuf->cb_num_elems--;
1348                                 iscsit_conn_dispatch_rele(ict);
1349                         }
1350                 }
1351                 mutex_exit(&ist->ist_sn_mutex);
1352         }
1353         /*
1354          * Make sure there aren't any PDU's transitioning from the receive
1355          * handler to the dispatch taskq.
1356          */
1357         idm_refcnt_wait_ref(&ict->ict_dispatch_refcnt);
1358 
1359         return (IDM_STATUS_SUCCESS);
1360 }
1361 
1362 static idm_status_t
1363 iscsit_conn_destroy(idm_conn_t *ic)
1364 {
1365         iscsit_conn_t *ict = ic->ic_handle;
1366 
1367         mutex_enter(&ict->ict_mutex);
1368         ict->ict_destroyed = B_TRUE;
1369         mutex_exit(&ict->ict_mutex);
1370 
1371         /* Generate session state machine event */
1372         if (ict->ict_sess != NULL) {
1373                 /*
1374                  * Session state machine will call iscsit_conn_destroy_done()
1375                  * when it has removed references to this connection.
1376                  */
1377                 iscsit_sess_sm_event(ict->ict_sess, SE_CONN_FAIL, ict);
1378         }
1379 
1380         idm_refcnt_wait_ref(&ict->ict_refcnt);
1381         /*
1382          * The session state machine does not need to post
1383          * events to IDM any longer, so it is safe to set
1384          * the idm connection reference to NULL
1385          */
1386         ict->ict_ic = NULL;
1387 
1388         /* Reap the login state machine */
1389         iscsit_login_sm_fini(ict);
1390 
1391         /* Clean up any text command remnants */
1392         iscsit_text_cmd_fini(ict);
1393 
1394         mutex_destroy(&ict->ict_mutex);
1395         idm_refcnt_destroy(&ict->ict_refcnt);
1396         kmem_free(ict, sizeof (*ict));
1397 
1398         iscsit_global_rele();
1399 
1400         return (IDM_STATUS_SUCCESS);
1401 }
1402 
1403 void
1404 iscsit_conn_logout(iscsit_conn_t *ict)
1405 {
1406         /*
1407          * If the iscsi connection is active, then
1408          * logout the IDM connection by sending a
1409          * CE_LOGOUT_SESSION_SUCCESS, else, no action
1410          * needs to be taken because the connection
1411          * is already in the teardown process.
1412          */
1413         mutex_enter(&ict->ict_mutex);
1414         if (ict->ict_lost == B_FALSE && ict->ict_destroyed == B_FALSE) {
1415                 idm_conn_event(ict->ict_ic, CE_LOGOUT_SESSION_SUCCESS, NULL);
1416         }
1417         mutex_exit(&ict->ict_mutex);
1418 }
1419 
1420 /*
1421  * STMF-related functions
1422  *
1423  * iSCSI to STMF mapping
1424  *
1425  * Session == ?
1426  * Connection == bound to local port but not itself a local port
1427  * Target
1428  * Target portal (group?) == local port (really but we're not going to do this)
1429  *      iscsit needs to map connections to local ports (whatever we decide
1430  *      they are)
1431  * Target == ?
1432  */
1433 
1434 /*ARGSUSED*/
1435 static stmf_data_buf_t *
1436 iscsit_dbuf_alloc(scsi_task_t *task, uint32_t size, uint32_t *pminsize,
1437     uint32_t flags)
1438 {
1439         iscsit_task_t *itask = task->task_port_private;
1440         idm_buf_t *idm_buffer;
1441         iscsit_buf_t    *ibuf;
1442         stmf_data_buf_t *result;
1443         uint32_t        bsize;
1444 
1445         /*
1446          * If the requested size is larger than MaxBurstLength and the
1447          * given pminsize is also larger than MaxBurstLength, then the
1448          * allocation fails (dbuf = NULL) and pminsize is modified to
1449          * be equal to MaxBurstLength. stmf/sbd then should re-invoke
1450          * this function with the corrected values for transfer.
1451          */
1452         ASSERT(pminsize);
1453         if (size <= itask->it_ict->ict_op.op_max_burst_length) {
1454                 bsize = size;
1455         } else if (*pminsize <= itask->it_ict->ict_op.op_max_burst_length) {
1456                 bsize = itask->it_ict->ict_op.op_max_burst_length;
1457         } else {
1458                 *pminsize = itask->it_ict->ict_op.op_max_burst_length;
1459                 return (NULL);
1460         }
1461 
1462         /* Alloc buffer */
1463         idm_buffer = idm_buf_alloc(itask->it_ict->ict_ic, NULL, bsize);
1464         if (idm_buffer != NULL) {
1465                 result = stmf_alloc(STMF_STRUCT_DATA_BUF,
1466                     sizeof (iscsit_buf_t), 0);
1467                 if (result != NULL) {
1468                         /* Fill in stmf_data_buf_t */
1469                         ibuf = result->db_port_private;
1470                         ibuf->ibuf_idm_buf = idm_buffer;
1471                         ibuf->ibuf_stmf_buf = result;
1472                         ibuf->ibuf_is_immed = B_FALSE;
1473                         result->db_flags = DB_DONT_CACHE;
1474                         result->db_buf_size = bsize;
1475                         result->db_data_size = bsize;
1476                         result->db_sglist_length = 1;
1477                         result->db_sglist[0].seg_addr = idm_buffer->idb_buf;
1478                         result->db_sglist[0].seg_length =
1479                             idm_buffer->idb_buflen;
1480                         return (result);
1481                 }
1482 
1483                 /* Couldn't get the stmf_data_buf_t so free the buffer */
1484                 idm_buf_free(idm_buffer);
1485         }
1486 
1487         return (NULL);
1488 }
1489 
1490 /*ARGSUSED*/
1491 static void
1492 iscsit_dbuf_free(stmf_dbuf_store_t *ds, stmf_data_buf_t *dbuf)
1493 {
1494         iscsit_buf_t *ibuf = dbuf->db_port_private;
1495 
1496         if (ibuf->ibuf_is_immed) {
1497                 /*
1498                  * The iscsit_buf_t structure itself will be freed with its
1499                  * associated task.  Here we just need to free the PDU that
1500                  * held the immediate data.
1501                  */
1502                 idm_pdu_complete(ibuf->ibuf_immed_data_pdu, IDM_STATUS_SUCCESS);
1503                 ibuf->ibuf_immed_data_pdu = 0;
1504         } else {
1505                 idm_buf_free(ibuf->ibuf_idm_buf);
1506                 stmf_free(dbuf);
1507         }
1508 }
1509 
1510 /*ARGSUSED*/
1511 stmf_status_t
1512 iscsit_xfer_scsi_data(scsi_task_t *task, stmf_data_buf_t *dbuf,
1513     uint32_t ioflags)
1514 {
1515         iscsit_task_t *iscsit_task = task->task_port_private;
1516         iscsit_sess_t *ict_sess = iscsit_task->it_ict->ict_sess;
1517         iscsit_buf_t *ibuf = dbuf->db_port_private;
1518         int idm_rc;
1519 
1520         /*
1521          * If we are aborting then we can ignore this request
1522          */
1523         if (iscsit_task->it_stmf_abort) {
1524                 return (STMF_SUCCESS);
1525         }
1526 
1527         /*
1528          * If it's not immediate data then start the transfer
1529          */
1530         ASSERT(ibuf->ibuf_is_immed == B_FALSE);
1531         if (dbuf->db_flags & DB_DIRECTION_TO_RPORT) {
1532                 /*
1533                  * The DB_SEND_STATUS_GOOD flag in the STMF data buffer allows
1534                  * the port provider to phase-collapse, i.e. send the status
1535                  * along with the final data PDU for the command. The port
1536                  * provider passes this request to the transport layer by
1537                  * setting a flag IDM_TASK_PHASECOLLAPSE_REQ in the task.
1538                  */
1539                 if (dbuf->db_flags & DB_SEND_STATUS_GOOD)
1540                         iscsit_task->it_idm_task->idt_flags |=
1541                             IDM_TASK_PHASECOLLAPSE_REQ;
1542                 /*
1543                  * IDM will call iscsit_build_hdr so lock now to serialize
1544                  * access to the SN values.  We need to lock here to enforce
1545                  * lock ordering
1546                  */
1547                 mutex_enter(&ict_sess->ist_sn_mutex);
1548                 idm_rc = idm_buf_tx_to_ini(iscsit_task->it_idm_task,
1549                     ibuf->ibuf_idm_buf, dbuf->db_relative_offset,
1550                     dbuf->db_data_size, &iscsit_buf_xfer_cb, dbuf);
1551                 mutex_exit(&ict_sess->ist_sn_mutex);
1552 
1553                 return (iscsit_idm_to_stmf(idm_rc));
1554         } else if (dbuf->db_flags & DB_DIRECTION_FROM_RPORT) {
1555                 /* Grab the SN lock (see comment above) */
1556                 mutex_enter(&ict_sess->ist_sn_mutex);
1557                 idm_rc = idm_buf_rx_from_ini(iscsit_task->it_idm_task,
1558                     ibuf->ibuf_idm_buf, dbuf->db_relative_offset,
1559                     dbuf->db_data_size, &iscsit_buf_xfer_cb, dbuf);
1560                 mutex_exit(&ict_sess->ist_sn_mutex);
1561 
1562                 return (iscsit_idm_to_stmf(idm_rc));
1563         }
1564 
1565         /* What are we supposed to do if there is no direction? */
1566         return (STMF_INVALID_ARG);
1567 }
1568 
1569 static void
1570 iscsit_buf_xfer_cb(idm_buf_t *idb, idm_status_t status)
1571 {
1572         iscsit_task_t *itask = idb->idb_task_binding->idt_private;
1573         stmf_data_buf_t *dbuf = idb->idb_cb_arg;
1574 
1575         dbuf->db_xfer_status = iscsit_idm_to_stmf(status);
1576 
1577         /*
1578          * If the task has been aborted then we don't need to call STMF
1579          */
1580         if (itask->it_stmf_abort) {
1581                 return;
1582         }
1583 
1584         /*
1585          * For ISCSI over TCP (not iSER), the last SCSI Data PDU passed
1586          * for a successful command contains the status as requested by
1587          * by COMSTAR (via the DB_SEND_STATUS_GOOD flag). But the iSER
1588          * transport does not support phase-collapse. So pretend we are
1589          * COMSTAR and send the status in a separate PDU now.
1590          */
1591         if (idb->idb_task_binding->idt_flags & IDM_TASK_PHASECOLLAPSE_SUCCESS) {
1592                 /*
1593                  * Mark task complete and notify COMSTAR
1594                  * that the status has been sent.
1595                  */
1596                 itask->it_idm_task->idt_state = TASK_COMPLETE;
1597                 stmf_send_status_done(itask->it_stmf_task,
1598                     iscsit_idm_to_stmf(status), STMF_IOF_LPORT_DONE);
1599         } else if ((dbuf->db_flags & DB_SEND_STATUS_GOOD) &&
1600             status == IDM_STATUS_SUCCESS) {
1601 
1602                 /*
1603                  * The iscsi target port provider - for iSER, emulates the
1604                  * DB_SEND_STATUS_GOOD optimization if requested by STMF;
1605                  * it sends the status in a separate PDU after the data
1606                  * transfer. In this case the port provider should first
1607                  * call stmf_data_xfer_done() to mark the transfer complete
1608                  * and then send the status. Although STMF will free the
1609                  * buffer at the time the task is freed, even if the transfer
1610                  * is not marked complete, this behavior makes statistics
1611                  * gathering and task state tracking more difficult than it
1612                  * needs to be.
1613                  */
1614                 stmf_data_xfer_done(itask->it_stmf_task, dbuf, 0);
1615                 if (iscsit_send_scsi_status(itask->it_stmf_task, 0)
1616                     != STMF_SUCCESS) {
1617                         stmf_send_status_done(itask->it_stmf_task,
1618                             STMF_FAILURE, STMF_IOF_LPORT_DONE);
1619                 }
1620         } else {
1621                 stmf_data_xfer_done(itask->it_stmf_task, dbuf, 0);
1622                 /* don't touch dbuf after stmf_data_xfer_done */
1623         }
1624 }
1625 
1626 
1627 /*ARGSUSED*/
1628 stmf_status_t
1629 iscsit_send_scsi_status(scsi_task_t *task, uint32_t ioflags)
1630 {
1631         iscsit_task_t *itask = task->task_port_private;
1632         iscsi_scsi_rsp_hdr_t *rsp;
1633         idm_pdu_t *pdu;
1634         int resp_datalen;
1635 
1636         /*
1637          * If this task is aborted then we don't need to respond.
1638          */
1639         if (itask->it_stmf_abort) {
1640                 return (STMF_SUCCESS);
1641         }
1642 
1643         /*
1644          * If this is a task management status, handle it elsewhere.
1645          */
1646         if (task->task_mgmt_function != TM_NONE) {
1647                 /*
1648                  * Don't wait for the PDU completion to tell STMF
1649                  * the task is done -- it doesn't really matter and
1650                  * it makes life complicated if STMF later asks us to
1651                  * abort the request and we don't know whether the
1652                  * status has been sent or not.
1653                  */
1654                 itask->it_tm_responded = B_TRUE;
1655                 iscsit_send_task_mgmt_resp(itask->it_tm_pdu,
1656                     (task->task_completion_status == STMF_SUCCESS) ?
1657                     SCSI_TCP_TM_RESP_COMPLETE : SCSI_TCP_TM_RESP_FUNC_NOT_SUPP);
1658                 stmf_send_status_done(task, STMF_SUCCESS,
1659                     STMF_IOF_LPORT_DONE);
1660                 return (STMF_SUCCESS);
1661         }
1662 
1663         /*
1664          * Remove the task from the session task list
1665          */
1666         iscsit_task_done(itask);
1667 
1668         /*
1669          * Send status
1670          */
1671         mutex_enter(&itask->it_idm_task->idt_mutex);
1672         if ((itask->it_idm_task->idt_state == TASK_ACTIVE) &&
1673             (task->task_completion_status == STMF_SUCCESS) &&
1674             (task->task_sense_length == 0) &&
1675             (task->task_resid == 0)) {
1676                 itask->it_idm_task->idt_state = TASK_COMPLETE;
1677                 /* PDU callback releases task hold */
1678                 idm_task_hold(itask->it_idm_task);
1679                 mutex_exit(&itask->it_idm_task->idt_mutex);
1680                 /*
1681                  * Fast path.  Cached status PDU's are already
1682                  * initialized.  We just need to fill in
1683                  * connection and task information. StatSN is
1684                  * incremented by 1 for every status sent a
1685                  * connection.
1686                  */
1687                 pdu = kmem_cache_alloc(iscsit_status_pdu_cache, KM_SLEEP);
1688                 pdu->isp_ic = itask->it_ict->ict_ic;
1689                 pdu->isp_private = itask;
1690                 pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
1691 
1692                 rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
1693                 rsp->itt = itask->it_itt;
1694                 /*
1695                  * ExpDataSN is the number of R2T and Data-In (read)
1696                  * PDUs the target has sent for the SCSI command.
1697                  *
1698                  * Since there is no support for bidirectional transfer
1699                  * yet, either idt_exp_datasn or idt_exp_rttsn, but not
1700                  * both is valid at any time
1701                  */
1702                 rsp->expdatasn = (itask->it_idm_task->idt_exp_datasn != 0) ?
1703                     htonl(itask->it_idm_task->idt_exp_datasn):
1704                     htonl(itask->it_idm_task->idt_exp_rttsn);
1705                 rsp->cmd_status = task->task_scsi_status;
1706                 iscsit_pdu_tx(pdu);
1707                 return (STMF_SUCCESS);
1708         } else {
1709                 if (itask->it_idm_task->idt_state != TASK_ACTIVE) {
1710                         mutex_exit(&itask->it_idm_task->idt_mutex);
1711                         return (STMF_FAILURE);
1712                 }
1713                 itask->it_idm_task->idt_state = TASK_COMPLETE;
1714                 /* PDU callback releases task hold */
1715                 idm_task_hold(itask->it_idm_task);
1716                 mutex_exit(&itask->it_idm_task->idt_mutex);
1717 
1718                 resp_datalen = (task->task_sense_length == 0) ? 0 :
1719                     (task->task_sense_length + sizeof (uint16_t));
1720 
1721                 pdu = idm_pdu_alloc(sizeof (iscsi_hdr_t), resp_datalen);
1722                 idm_pdu_init(pdu, itask->it_ict->ict_ic, itask,
1723                     iscsit_send_status_done);
1724                 pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
1725 
1726                 rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
1727                 bzero(rsp, sizeof (*rsp));
1728                 rsp->opcode = ISCSI_OP_SCSI_RSP;
1729 
1730                 rsp->flags = ISCSI_FLAG_FINAL;
1731                 if (task->task_status_ctrl & TASK_SCTRL_OVER) {
1732                         rsp->flags |= ISCSI_FLAG_CMD_OVERFLOW;
1733                 } else if (task->task_status_ctrl & TASK_SCTRL_UNDER) {
1734                         rsp->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
1735                 }
1736 
1737                 rsp->bi_residual_count = 0;
1738                 rsp->residual_count = htonl(task->task_resid);
1739                 rsp->itt = itask->it_itt;
1740                 rsp->response = ISCSI_STATUS_CMD_COMPLETED;
1741                 rsp->expdatasn = (itask->it_idm_task->idt_exp_datasn != 0) ?
1742                     htonl(itask->it_idm_task->idt_exp_datasn):
1743                     htonl(itask->it_idm_task->idt_exp_rttsn);
1744                 rsp->cmd_status = task->task_scsi_status;
1745                 if (task->task_sense_length != 0) {
1746                         /*
1747                          * Add a byte to provide the sense length in
1748                          * the response
1749                          */
1750                         *(uint16_t *)((void *)pdu->isp_data) =
1751                             htons(task->task_sense_length);
1752                         bcopy(task->task_sense_data,
1753                             (uint8_t *)pdu->isp_data +
1754                             sizeof (uint16_t),
1755                             task->task_sense_length);
1756                         hton24(rsp->dlength, resp_datalen);
1757                 }
1758 
1759                 DTRACE_PROBE5(iscsi__scsi__response,
1760                     iscsit_conn_t *, itask->it_ict,
1761                     uint8_t, rsp->response,
1762                     uint8_t, rsp->cmd_status,
1763                     idm_pdu_t *, pdu,
1764                     scsi_task_t *, task);
1765 
1766                 iscsit_pdu_tx(pdu);
1767 
1768                 return (STMF_SUCCESS);
1769         }
1770 }
1771 
1772 /*ARGSUSED*/
1773 static void
1774 iscsit_send_good_status_done(idm_pdu_t *pdu, idm_status_t status)
1775 {
1776         iscsit_task_t   *itask;
1777         boolean_t       aborted;
1778 
1779         itask = pdu->isp_private;
1780         aborted = itask->it_stmf_abort;
1781 
1782         /*
1783          * After releasing the hold the task may be freed at any time so
1784          * don't touch it.
1785          */
1786         idm_task_rele(itask->it_idm_task);
1787         if (!aborted) {
1788                 stmf_send_status_done(itask->it_stmf_task,
1789                     iscsit_idm_to_stmf(pdu->isp_status), STMF_IOF_LPORT_DONE);
1790         }
1791         kmem_cache_free(iscsit_status_pdu_cache, pdu);
1792 }
1793 
1794 /*ARGSUSED*/
1795 static void
1796 iscsit_send_status_done(idm_pdu_t *pdu, idm_status_t status)
1797 {
1798         iscsit_task_t    *itask;
1799         boolean_t       aborted;
1800 
1801         itask = pdu->isp_private;
1802         aborted = itask->it_stmf_abort;
1803 
1804         /*
1805          * After releasing the hold the task may be freed at any time so
1806          * don't touch it.
1807          */
1808         idm_task_rele(itask->it_idm_task);
1809         if (!aborted) {
1810                 stmf_send_status_done(itask->it_stmf_task,
1811                     iscsit_idm_to_stmf(pdu->isp_status), STMF_IOF_LPORT_DONE);
1812         }
1813         idm_pdu_free(pdu);
1814 }
1815 
1816 
1817 void
1818 iscsit_lport_task_free(scsi_task_t *task)
1819 {
1820         iscsit_task_t *itask = task->task_port_private;
1821 
1822         /* We only call idm_task_start for regular tasks, not task management */
1823         if (task->task_mgmt_function == TM_NONE) {
1824                 idm_task_done(itask->it_idm_task);
1825                 iscsit_task_free(itask);
1826                 return;
1827         } else {
1828                 iscsit_tm_task_free(itask);
1829         }
1830 }
1831 
1832 /*ARGSUSED*/
1833 stmf_status_t
1834 iscsit_abort(stmf_local_port_t *lport, int abort_cmd, void *arg, uint32_t flags)
1835 {
1836         scsi_task_t     *st = (scsi_task_t *)arg;
1837         iscsit_task_t   *iscsit_task;
1838         idm_task_t      *idt;
1839 
1840         /*
1841          * If this is a task management request then there's really not much to
1842          * do.
1843          */
1844         if (st->task_mgmt_function != TM_NONE) {
1845                 return (STMF_ABORT_SUCCESS);
1846         }
1847 
1848         /*
1849          * Regular task, start cleaning up
1850          */
1851         iscsit_task = st->task_port_private;
1852         idt = iscsit_task->it_idm_task;
1853         mutex_enter(&iscsit_task->it_mutex);
1854         iscsit_task->it_stmf_abort = B_TRUE;
1855         if (iscsit_task->it_aborted) {
1856                 mutex_exit(&iscsit_task->it_mutex);
1857                 /*
1858                  * Task is no longer active
1859                  */
1860                 iscsit_task_done(iscsit_task);
1861 
1862                 /*
1863                  * STMF specification is wrong... says to return
1864                  * STMF_ABORTED, the code actually looks for
1865                  * STMF_ABORT_SUCCESS.
1866                  */
1867                 return (STMF_ABORT_SUCCESS);
1868         } else {
1869                 mutex_exit(&iscsit_task->it_mutex);
1870                 /*
1871                  * Call IDM to abort the task.  Due to a variety of
1872                  * circumstances the task may already be in the process of
1873                  * aborting.
1874                  * We'll let IDM worry about rationalizing all that except
1875                  * for one particular instance.  If the state of the task
1876                  * is TASK_COMPLETE, we need to indicate to the framework
1877                  * that we are in fact done.  This typically happens with
1878                  * framework-initiated task management type requests
1879                  * (e.g. abort task).
1880                  */
1881                 if (idt->idt_state == TASK_COMPLETE) {
1882                         idm_refcnt_wait_ref(&idt->idt_refcnt);
1883                         return (STMF_ABORT_SUCCESS);
1884                 } else {
1885                         idm_task_abort(idt->idt_ic, idt, AT_TASK_MGMT_ABORT);
1886                         return (STMF_SUCCESS);
1887                 }
1888         }
1889 
1890         /*NOTREACHED*/
1891 }
1892 
1893 /*ARGSUSED*/
1894 void
1895 iscsit_ctl(stmf_local_port_t *lport, int cmd, void *arg)
1896 {
1897         iscsit_tgt_t            *iscsit_tgt;
1898 
1899         ASSERT((cmd == STMF_CMD_LPORT_ONLINE) ||
1900             (cmd == STMF_ACK_LPORT_ONLINE_COMPLETE) ||
1901             (cmd == STMF_CMD_LPORT_OFFLINE) ||
1902             (cmd == STMF_ACK_LPORT_OFFLINE_COMPLETE));
1903 
1904         iscsit_tgt = (iscsit_tgt_t *)lport->lport_port_private;
1905 
1906         switch (cmd) {
1907         case STMF_CMD_LPORT_ONLINE:
1908                 iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_ONLINE_REQ);
1909                 break;
1910         case STMF_CMD_LPORT_OFFLINE:
1911                 iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_OFFLINE_REQ);
1912                 break;
1913         case STMF_ACK_LPORT_ONLINE_COMPLETE:
1914                 iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_ONLINE_COMPLETE_ACK);
1915                 break;
1916         case STMF_ACK_LPORT_OFFLINE_COMPLETE:
1917                 iscsit_tgt_sm_event(iscsit_tgt, TE_STMF_OFFLINE_COMPLETE_ACK);
1918                 break;
1919 
1920         default:
1921                 break;
1922         }
1923 }
1924 
1925 static stmf_status_t
1926 iscsit_idm_to_stmf(idm_status_t idmrc)
1927 {
1928         switch (idmrc) {
1929         case IDM_STATUS_SUCCESS:
1930                 return (STMF_SUCCESS);
1931         default:
1932                 return (STMF_FAILURE);
1933         }
1934         /*NOTREACHED*/
1935 }
1936 
1937 void
1938 iscsit_op_scsi_cmd(idm_conn_t *ic, idm_pdu_t *rx_pdu)
1939 {
1940         iscsit_conn_t           *ict = ic->ic_handle;
1941 
1942         if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
1943                 iscsit_post_scsi_cmd(ic, rx_pdu);
1944         }
1945         iscsit_process_pdu_in_queue(ict->ict_sess);
1946 }
1947 
1948 /*
1949  * ISCSI protocol
1950  */
1951 
1952 void
1953 iscsit_post_scsi_cmd(idm_conn_t *ic, idm_pdu_t *rx_pdu)
1954 {
1955         iscsit_conn_t           *ict;
1956         iscsit_task_t           *itask;
1957         scsi_task_t             *task;
1958         iscsit_buf_t            *ibuf;
1959         iscsi_scsi_cmd_hdr_t    *iscsi_scsi =
1960             (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
1961         iscsi_addl_hdr_t        *ahs_hdr;
1962         uint16_t                addl_cdb_len = 0;
1963 
1964         ict = ic->ic_handle;
1965 
1966         itask = iscsit_task_alloc(ict);
1967         if (itask == NULL) {
1968                 /* Finish processing request */
1969                 iscsit_set_cmdsn(ict, rx_pdu);
1970 
1971                 iscsit_send_direct_scsi_resp(ict, rx_pdu,
1972                     ISCSI_STATUS_CMD_COMPLETED, STATUS_BUSY);
1973                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
1974                 return;
1975         }
1976 
1977         /*
1978          * Note CmdSN and ITT in task.  IDM will have already validated this
1979          * request against the connection state so we don't need to check
1980          * that (the connection may have changed state in the meantime but
1981          * we will catch that when we try to send a response)
1982          */
1983         itask->it_cmdsn = ntohl(iscsi_scsi->cmdsn);
1984         itask->it_itt = iscsi_scsi->itt;
1985 
1986         /*
1987          * Check for extended CDB AHS
1988          */
1989         if (iscsi_scsi->hlength > 0) {
1990                 ahs_hdr = (iscsi_addl_hdr_t *)iscsi_scsi;
1991                 addl_cdb_len = ((ahs_hdr->ahs_hlen_hi << 8) |
1992                     ahs_hdr->ahs_hlen_lo) - 1; /* Adjust for reserved byte */
1993                 if (((addl_cdb_len + 4) / sizeof (uint32_t)) >
1994                     iscsi_scsi->hlength) {
1995                         /* Mangled header info, drop it */
1996                         idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
1997                         return;
1998                 }
1999         }
2000 
2001         ict = rx_pdu->isp_ic->ic_handle; /* IDM client private */
2002 
2003         /*
2004          * Add task to session list.  This function will also check to
2005          * ensure that the task does not already exist.
2006          */
2007         if (iscsit_task_start(itask) != IDM_STATUS_SUCCESS) {
2008                 /*
2009                  * Task exists, free all resources and reject.  Don't
2010                  * update expcmdsn in this case because RFC 3720 says
2011                  * "The CmdSN of the rejected command PDU (if it is a
2012                  * non-immediate command) MUST NOT be considered received
2013                  * by the target (i.e., a command sequence gap must be
2014                  * assumed for the CmdSN), even though the CmdSN of the
2015                  * rejected command PDU may be reliably ascertained.  Upon
2016                  * receiving the Reject, the initiator MUST plug the CmdSN
2017                  * gap in order to continue to use the session.  The gap
2018                  * may be plugged either by transmitting a command PDU
2019                  * with the same CmdSN, or by aborting the task (see section
2020                  * 6.9 on how an abort may plug a CmdSN gap)." (Section 6.3)
2021                  */
2022                 iscsit_task_free(itask);
2023                 iscsit_send_reject(ict, rx_pdu, ISCSI_REJECT_TASK_IN_PROGRESS);
2024                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2025                 return;
2026         }
2027 
2028         /* Update sequence numbers */
2029         iscsit_set_cmdsn(ict, rx_pdu);
2030 
2031         /*
2032          * Allocate STMF task
2033          */
2034         itask->it_stmf_task = stmf_task_alloc(
2035             itask->it_ict->ict_sess->ist_lport,
2036             itask->it_ict->ict_sess->ist_stmf_sess, iscsi_scsi->lun,
2037             16 + addl_cdb_len, 0);
2038         if (itask->it_stmf_task == NULL) {
2039                 /*
2040                  * Either stmf really couldn't get memory for a task or,
2041                  * more likely, the LU is currently in reset.  Either way
2042                  * we have no choice but to fail the request.
2043                  */
2044                 iscsit_task_done(itask);
2045                 iscsit_task_free(itask);
2046                 iscsit_send_direct_scsi_resp(ict, rx_pdu,
2047                     ISCSI_STATUS_CMD_COMPLETED, STATUS_BUSY);
2048                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2049                 return;
2050         }
2051 
2052         task = itask->it_stmf_task;
2053         task->task_port_private = itask;
2054 
2055         bcopy(iscsi_scsi->lun, task->task_lun_no, sizeof (task->task_lun_no));
2056 
2057         /*
2058          * iSCSI and Comstar use the same values.  Should we rely on this
2059          * or translate them bit-wise?
2060          */
2061 
2062         task->task_flags =
2063             (((iscsi_scsi->flags & ISCSI_FLAG_CMD_READ) ? TF_READ_DATA : 0) |
2064             ((iscsi_scsi->flags & ISCSI_FLAG_CMD_WRITE) ? TF_WRITE_DATA : 0) |
2065             ((rx_pdu->isp_datalen == 0) ? 0 : TF_INITIAL_BURST));
2066 
2067         switch (iscsi_scsi->flags & ISCSI_FLAG_CMD_ATTR_MASK) {
2068         case ISCSI_ATTR_UNTAGGED:
2069                 break;
2070         case ISCSI_ATTR_SIMPLE:
2071                 task->task_additional_flags |= TF_ATTR_SIMPLE_QUEUE;
2072                 break;
2073         case ISCSI_ATTR_ORDERED:
2074                 task->task_additional_flags |= TF_ATTR_ORDERED_QUEUE;
2075                 break;
2076         case ISCSI_ATTR_HEAD_OF_QUEUE:
2077                 task->task_additional_flags |= TF_ATTR_HEAD_OF_QUEUE;
2078                 break;
2079         case ISCSI_ATTR_ACA:
2080                 task->task_additional_flags |= TF_ATTR_ACA;
2081                 break;
2082         default:
2083                 /* Protocol error but just take it, treat as untagged */
2084                 break;
2085         }
2086 
2087 
2088         task->task_additional_flags = 0;
2089         task->task_priority = 0;
2090         task->task_mgmt_function = TM_NONE;
2091 
2092         /*
2093          * This "task_max_nbufs" doesn't map well to BIDI.  We probably need
2094          * parameter for each direction.  "MaxOutstandingR2T" may very well
2095          * be set to one which could prevent us from doing simultaneous
2096          * transfers in each direction.
2097          */
2098         task->task_max_nbufs = (iscsi_scsi->flags & ISCSI_FLAG_CMD_WRITE) ?
2099             ict->ict_op.op_max_outstanding_r2t : STMF_BUFS_MAX;
2100         task->task_cmd_seq_no = ntohl(iscsi_scsi->itt);
2101         task->task_expected_xfer_length = ntohl(iscsi_scsi->data_length);
2102 
2103         /* Copy CDB */
2104         bcopy(iscsi_scsi->scb, task->task_cdb, 16);
2105         if (addl_cdb_len > 0) {
2106                 bcopy(ahs_hdr->ahs_extscb, task->task_cdb + 16, addl_cdb_len);
2107         }
2108 
2109         DTRACE_ISCSI_3(scsi__command, idm_conn_t *, ic,
2110             iscsi_scsi_cmd_hdr_t *, (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr,
2111             scsi_task_t *, task);
2112 
2113         /*
2114          * Copy the transport header into the task handle from the PDU
2115          * handle. The transport header describes this task's remote tagged
2116          * buffer.
2117          */
2118         if (rx_pdu->isp_transport_hdrlen != 0) {
2119                 bcopy(rx_pdu->isp_transport_hdr,
2120                     itask->it_idm_task->idt_transport_hdr,
2121                     rx_pdu->isp_transport_hdrlen);
2122         }
2123 
2124         /*
2125          * Tell IDM about our new active task
2126          */
2127         idm_task_start(itask->it_idm_task, (uintptr_t)itask->it_itt);
2128 
2129         /*
2130          * If we have any immediate data then setup the immediate buffer
2131          * context that comes with the task
2132          */
2133         if (rx_pdu->isp_datalen) {
2134                 ibuf = itask->it_immed_data;
2135                 ibuf->ibuf_immed_data_pdu = rx_pdu;
2136                 ibuf->ibuf_stmf_buf->db_data_size = rx_pdu->isp_datalen;
2137                 ibuf->ibuf_stmf_buf->db_buf_size = rx_pdu->isp_datalen;
2138                 ibuf->ibuf_stmf_buf->db_relative_offset = 0;
2139                 ibuf->ibuf_stmf_buf->db_sglist[0].seg_length =
2140                     rx_pdu->isp_datalen;
2141                 ibuf->ibuf_stmf_buf->db_sglist[0].seg_addr = rx_pdu->isp_data;
2142 
2143                 DTRACE_ISCSI_8(xfer__start, idm_conn_t *, ic,
2144                     uintptr_t, ibuf->ibuf_stmf_buf->db_sglist[0].seg_addr,
2145                     uint32_t, ibuf->ibuf_stmf_buf->db_relative_offset,
2146                     uint64_t, 0, uint32_t, 0, uint32_t, 0, /* no raddr */
2147                     uint32_t, rx_pdu->isp_datalen, int, XFER_BUF_TX_TO_INI);
2148 
2149                 /*
2150                  * For immediate data transfer, there is no callback from
2151                  * stmf to indicate that the initial burst of data is
2152                  * transferred successfully. In some cases, the task can
2153                  * get freed before execution returns from stmf_post_task.
2154                  * Although this xfer-start/done probe accurately tracks
2155                  * the size of the transfer, it does only provide a best
2156                  * effort on the timing of the transfer.
2157                  */
2158                 DTRACE_ISCSI_8(xfer__done, idm_conn_t *, ic,
2159                     uintptr_t, ibuf->ibuf_stmf_buf->db_sglist[0].seg_addr,
2160                     uint32_t, ibuf->ibuf_stmf_buf->db_relative_offset,
2161                     uint64_t, 0, uint32_t, 0, uint32_t, 0, /* no raddr */
2162                     uint32_t, rx_pdu->isp_datalen, int, XFER_BUF_TX_TO_INI);
2163                 stmf_post_task(task, ibuf->ibuf_stmf_buf);
2164         } else {
2165 
2166                 stmf_post_task(task, NULL);
2167                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2168         }
2169 }
2170 
2171 void
2172 iscsit_deferred_dispatch(idm_pdu_t *rx_pdu)
2173 {
2174         iscsit_conn_t *ict = rx_pdu->isp_ic->ic_handle;
2175 
2176         /*
2177          * If the connection has been lost then ignore new PDU's
2178          */
2179         mutex_enter(&ict->ict_mutex);
2180         if (ict->ict_lost) {
2181                 mutex_exit(&ict->ict_mutex);
2182                 idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
2183                 return;
2184         }
2185 
2186         /*
2187          * Grab a hold on the connection to prevent it from going away
2188          * between now and when the taskq function is called.
2189          */
2190         iscsit_conn_dispatch_hold(ict);
2191         mutex_exit(&ict->ict_mutex);
2192 
2193         taskq_dispatch_ent(iscsit_global.global_dispatch_taskq,
2194             iscsit_deferred, rx_pdu, 0, &rx_pdu->isp_tqent);
2195 }
2196 
2197 static void
2198 iscsit_deferred(void *rx_pdu_void)
2199 {
2200         idm_pdu_t               *rx_pdu = rx_pdu_void;
2201         idm_conn_t              *ic = rx_pdu->isp_ic;
2202         iscsit_conn_t           *ict = ic->ic_handle;
2203 
2204         /*
2205          * NOP and Task Management Commands can be marked for immediate
2206          * delivery. Commands marked as 'Immediate' are to be considered
2207          * for execution as soon as they arrive on the target. So these
2208          * should not be checked for sequence order and put in a queue.
2209          * The CmdSN is not advanced for Immediate Commands.
2210          */
2211         switch (IDM_PDU_OPCODE(rx_pdu)) {
2212         case ISCSI_OP_NOOP_OUT:
2213                 if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
2214                         iscsit_set_cmdsn(ict, rx_pdu);
2215                         iscsit_pdu_op_noop(ict, rx_pdu);
2216                 }
2217                 break;
2218         case ISCSI_OP_LOGIN_CMD:
2219                 iscsit_pdu_op_login_cmd(ict, rx_pdu);
2220                 iscsit_conn_dispatch_rele(ict);
2221                 return;
2222         case ISCSI_OP_TEXT_CMD:
2223                 if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
2224                         iscsit_set_cmdsn(ict, rx_pdu);
2225                         iscsit_pdu_op_text_cmd(ict, rx_pdu);
2226                 }
2227                 break;
2228         case ISCSI_OP_LOGOUT_CMD:
2229                 if (iscsit_check_cmdsn_and_queue(rx_pdu)) {
2230                         iscsit_set_cmdsn(ict, rx_pdu);
2231                         iscsit_pdu_op_logout_cmd(ict, rx_pdu);
2232                 }
2233                 break;
2234         default:
2235                 /* Protocol error.  IDM should have caught this */
2236                 idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
2237                 ASSERT(0);
2238                 break;
2239         }
2240         /*
2241          * Check if there are other PDUs in the session staging queue
2242          * waiting to be posted to SCSI layer.
2243          */
2244         iscsit_process_pdu_in_queue(ict->ict_sess);
2245 
2246         iscsit_conn_dispatch_rele(ict);
2247 }
2248 
2249 static void
2250 iscsit_send_direct_scsi_resp(iscsit_conn_t *ict, idm_pdu_t *rx_pdu,
2251     uint8_t response, uint8_t cmd_status)
2252 {
2253         idm_pdu_t                       *rsp_pdu;
2254         idm_conn_t                      *ic;
2255         iscsi_scsi_rsp_hdr_t            *resp;
2256         iscsi_scsi_cmd_hdr_t            *req =
2257             (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
2258 
2259         ic = ict->ict_ic;
2260 
2261         rsp_pdu = idm_pdu_alloc(sizeof (iscsi_scsi_rsp_hdr_t), 0);
2262         idm_pdu_init(rsp_pdu, ic, NULL, NULL);
2263         /*
2264          * StatSN is incremented by 1 for every response sent on
2265          * a connection except for responses sent as a result of
2266          * a retry or SNACK
2267          */
2268         rsp_pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2269 
2270         resp = (iscsi_scsi_rsp_hdr_t *)rsp_pdu->isp_hdr;
2271 
2272         resp->opcode = ISCSI_OP_SCSI_RSP;
2273         resp->flags = ISCSI_FLAG_FINAL;
2274         resp->response = response;
2275         resp->cmd_status = cmd_status;
2276         resp->itt = req->itt;
2277         if ((response == ISCSI_STATUS_CMD_COMPLETED) &&
2278             (req->data_length != 0) &&
2279             ((req->flags & ISCSI_FLAG_CMD_READ) ||
2280             (req->flags & ISCSI_FLAG_CMD_WRITE))) {
2281                 resp->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
2282                 resp->residual_count = req->data_length;
2283         }
2284 
2285         DTRACE_PROBE4(iscsi__scsi__direct__response,
2286             iscsit_conn_t *, ict,
2287             uint8_t, resp->response,
2288             uint8_t, resp->cmd_status,
2289             idm_pdu_t *, rsp_pdu);
2290 
2291         iscsit_pdu_tx(rsp_pdu);
2292 }
2293 
2294 void
2295 iscsit_send_task_mgmt_resp(idm_pdu_t *tm_resp_pdu, uint8_t tm_status)
2296 {
2297         iscsi_scsi_task_mgt_rsp_hdr_t   *tm_resp;
2298 
2299         /*
2300          * The target must take note of the last-sent StatSN.
2301          * The StatSN is to be incremented after sending a
2302          * task management response. Digest recovery can only
2303          * work if StatSN is incremented.
2304          */
2305         tm_resp_pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2306         tm_resp = (iscsi_scsi_task_mgt_rsp_hdr_t *)tm_resp_pdu->isp_hdr;
2307         tm_resp->response = tm_status;
2308 
2309         DTRACE_PROBE3(iscsi__scsi__tm__response,
2310             iscsit_conn_t *, tm_resp_pdu->isp_ic->ic_handle,
2311             uint8_t, tm_resp->response,
2312             idm_pdu_t *, tm_resp_pdu);
2313         iscsit_pdu_tx(tm_resp_pdu);
2314 }
2315 
2316 void
2317 iscsit_op_scsi_task_mgmt(iscsit_conn_t *ict, idm_pdu_t *rx_pdu)
2318 {
2319         idm_pdu_t                       *tm_resp_pdu;
2320         iscsit_task_t                   *itask;
2321         iscsit_task_t                   *tm_itask;
2322         scsi_task_t                     *task;
2323         iscsi_scsi_task_mgt_hdr_t       *iscsi_tm =
2324             (iscsi_scsi_task_mgt_hdr_t *)rx_pdu->isp_hdr;
2325         iscsi_scsi_task_mgt_rsp_hdr_t   *iscsi_tm_rsp =
2326             (iscsi_scsi_task_mgt_rsp_hdr_t *)rx_pdu->isp_hdr;
2327         uint32_t                        rtt, cmdsn, refcmdsn;
2328         uint8_t                         tm_func;
2329 
2330         /*
2331          * Setup response PDU (response field will get filled in later)
2332          */
2333         tm_resp_pdu = idm_pdu_alloc(sizeof (iscsi_scsi_task_mgt_rsp_hdr_t), 0);
2334         if (tm_resp_pdu == NULL) {
2335                 /* Can't respond, just drop it */
2336                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2337                 return;
2338         }
2339         idm_pdu_init(tm_resp_pdu, ict->ict_ic, NULL, NULL);
2340         iscsi_tm_rsp = (iscsi_scsi_task_mgt_rsp_hdr_t *)tm_resp_pdu->isp_hdr;
2341         bzero(iscsi_tm_rsp, sizeof (iscsi_scsi_task_mgt_rsp_hdr_t));
2342         iscsi_tm_rsp->opcode = ISCSI_OP_SCSI_TASK_MGT_RSP;
2343         iscsi_tm_rsp->flags = ISCSI_FLAG_FINAL;
2344         iscsi_tm_rsp->itt = rx_pdu->isp_hdr->itt;
2345 
2346         /*
2347          * Figure out what we're being asked to do.
2348          */
2349         DTRACE_PROBE4(iscsi__scsi__tm__request,
2350             iscsit_conn_t *, ict,
2351             uint8_t, (iscsi_tm->function & ISCSI_FLAG_TASK_MGMT_FUNCTION_MASK),
2352             uint32_t, iscsi_tm->rtt,
2353             idm_pdu_t *, rx_pdu);
2354         switch (iscsi_tm->function & ISCSI_FLAG_TASK_MGMT_FUNCTION_MASK) {
2355         case ISCSI_TM_FUNC_ABORT_TASK:
2356                 /*
2357                  * STMF doesn't currently support the "abort task" task
2358                  * management command although it does support aborting
2359                  * an individual task.  We'll get STMF to abort the task
2360                  * for us but handle the details of the task management
2361                  * command ourselves.
2362                  *
2363                  * Find the task associated with the referenced task tag.
2364                  */
2365                 rtt = iscsi_tm->rtt;
2366                 itask = (iscsit_task_t *)idm_task_find_by_handle(ict->ict_ic,
2367                     (uintptr_t)rtt);
2368 
2369                 if (itask == NULL) {
2370                         cmdsn = ntohl(iscsi_tm->cmdsn);
2371                         refcmdsn = ntohl(iscsi_tm->refcmdsn);
2372 
2373                         /*
2374                          * Task was not found. But the SCSI command could be
2375                          * on the rxpdu wait queue. If RefCmdSN is within
2376                          * the CmdSN window and less than CmdSN of the TM
2377                          * function, return "Function Complete". Otherwise,
2378                          * return "Task Does Not Exist".
2379                          */
2380 
2381                         if (iscsit_cmdsn_in_window(ict, refcmdsn) &&
2382                             iscsit_sna_lt(refcmdsn, cmdsn)) {
2383                                 mutex_enter(&ict->ict_sess->ist_sn_mutex);
2384                                 (void) iscsit_remove_pdu_from_queue(
2385                                     ict->ict_sess, refcmdsn);
2386                                 iscsit_conn_dispatch_rele(ict);
2387                                 mutex_exit(&ict->ict_sess->ist_sn_mutex);
2388                                 iscsit_send_task_mgmt_resp(tm_resp_pdu,
2389                                     SCSI_TCP_TM_RESP_COMPLETE);
2390                         } else {
2391                                 iscsit_send_task_mgmt_resp(tm_resp_pdu,
2392                                     SCSI_TCP_TM_RESP_NO_TASK);
2393                         }
2394                 } else {
2395 
2396                         /*
2397                          * Tell STMF to abort the task.  This will do no harm
2398                          * if the task is already complete.
2399                          */
2400                         stmf_abort(STMF_QUEUE_TASK_ABORT, itask->it_stmf_task,
2401                             STMF_ABORTED, NULL);
2402 
2403                         /*
2404                          * Make sure the task hasn't already completed
2405                          */
2406                         mutex_enter(&itask->it_idm_task->idt_mutex);
2407                         if ((itask->it_idm_task->idt_state == TASK_COMPLETE) ||
2408                             (itask->it_idm_task->idt_state == TASK_IDLE)) {
2409                                 /*
2410                                  * Task is complete, return "Task Does Not
2411                                  * Exist"
2412                                  */
2413                                 mutex_exit(&itask->it_idm_task->idt_mutex);
2414                                 iscsit_send_task_mgmt_resp(tm_resp_pdu,
2415                                     SCSI_TCP_TM_RESP_NO_TASK);
2416                         } else {
2417                                 /*
2418                                  * STMF is now aborting the task, return
2419                                  * "Function Complete"
2420                                  */
2421                                 mutex_exit(&itask->it_idm_task->idt_mutex);
2422                                 iscsit_send_task_mgmt_resp(tm_resp_pdu,
2423                                     SCSI_TCP_TM_RESP_COMPLETE);
2424                         }
2425                         idm_task_rele(itask->it_idm_task);
2426                 }
2427                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2428                 return;
2429 
2430         case ISCSI_TM_FUNC_ABORT_TASK_SET:
2431                 tm_func = TM_ABORT_TASK_SET;
2432                 break;
2433 
2434         case ISCSI_TM_FUNC_CLEAR_ACA:
2435                 tm_func = TM_CLEAR_ACA;
2436                 break;
2437 
2438         case ISCSI_TM_FUNC_CLEAR_TASK_SET:
2439                 tm_func = TM_CLEAR_TASK_SET;
2440                 break;
2441 
2442         case ISCSI_TM_FUNC_LOGICAL_UNIT_RESET:
2443                 tm_func = TM_LUN_RESET;
2444                 break;
2445 
2446         case ISCSI_TM_FUNC_TARGET_WARM_RESET:
2447                 tm_func = TM_TARGET_WARM_RESET;
2448                 break;
2449 
2450         case ISCSI_TM_FUNC_TARGET_COLD_RESET:
2451                 tm_func = TM_TARGET_COLD_RESET;
2452                 break;
2453 
2454         case ISCSI_TM_FUNC_TASK_REASSIGN:
2455                 /*
2456                  * We do not currently support allegiance reassignment.  When
2457                  * we start supporting ERL1+, we will need to.
2458                  */
2459                 iscsit_send_task_mgmt_resp(tm_resp_pdu,
2460                     SCSI_TCP_TM_RESP_NO_ALLG_REASSN);
2461                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2462                 return;
2463 
2464         default:
2465                 iscsit_send_task_mgmt_resp(tm_resp_pdu,
2466                     SCSI_TCP_TM_RESP_REJECTED);
2467                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2468                 return;
2469         }
2470 
2471         tm_itask = iscsit_tm_task_alloc(ict);
2472         if (tm_itask == NULL) {
2473                 iscsit_send_task_mgmt_resp(tm_resp_pdu,
2474                     SCSI_TCP_TM_RESP_REJECTED);
2475                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2476                 return;
2477         }
2478 
2479 
2480         task = stmf_task_alloc(ict->ict_sess->ist_lport,
2481             ict->ict_sess->ist_stmf_sess, iscsi_tm->lun,
2482             0, STMF_TASK_EXT_NONE);
2483         if (task == NULL) {
2484                 /*
2485                  * If this happens, either the LU is in reset, couldn't
2486                  * get memory, or some other condition in which we simply
2487                  * can't complete this request.  It would be nice to return
2488                  * an error code like "busy" but the closest we have is
2489                  * "rejected".
2490                  */
2491                 iscsit_send_task_mgmt_resp(tm_resp_pdu,
2492                     SCSI_TCP_TM_RESP_REJECTED);
2493                 iscsit_tm_task_free(tm_itask);
2494                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2495                 return;
2496         }
2497 
2498         tm_itask->it_tm_pdu = tm_resp_pdu;
2499         tm_itask->it_stmf_task = task;
2500         task->task_port_private = tm_itask;
2501         task->task_mgmt_function = tm_func;
2502         task->task_additional_flags = TASK_AF_NO_EXPECTED_XFER_LENGTH;
2503         task->task_priority = 0;
2504         task->task_max_nbufs = STMF_BUFS_MAX;
2505         task->task_cmd_seq_no = iscsi_tm->itt;
2506         task->task_expected_xfer_length = 0;
2507 
2508         stmf_post_task(task, NULL);
2509         idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2510 }
2511 
2512 static void
2513 iscsit_pdu_op_noop(iscsit_conn_t *ict, idm_pdu_t *rx_pdu)
2514 {
2515         iscsi_nop_out_hdr_t *out = (iscsi_nop_out_hdr_t *)rx_pdu->isp_hdr;
2516         iscsi_nop_in_hdr_t *in;
2517         int resp_datalen;
2518         idm_pdu_t *resp;
2519 
2520         /* Ignore the response from initiator */
2521         if ((out->itt == ISCSI_RSVD_TASK_TAG) ||
2522             (out->ttt != ISCSI_RSVD_TASK_TAG)) {
2523                 idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2524                 return;
2525         }
2526 
2527         /* Allocate a PDU to respond */
2528         resp_datalen = ntoh24(out->dlength);
2529         resp = idm_pdu_alloc(sizeof (iscsi_hdr_t), resp_datalen);
2530         idm_pdu_init(resp, ict->ict_ic, NULL, NULL);
2531         if (resp_datalen > 0) {
2532                 bcopy(rx_pdu->isp_data, resp->isp_data, resp_datalen);
2533         }
2534 
2535         /*
2536          * When sending a NOP-In as a response to a NOP-Out from the initiator,
2537          * the target must respond with the same initiator task tag that was
2538          * provided in the NOP-Out request, the target transfer tag must be
2539          * ISCSI_RSVD_TASK_TAG (0xffffffff) and StatSN will contain the next
2540          * status sequence number. The StatSN for the connection is advanced
2541          * after this PDU is sent.
2542          */
2543         in = (iscsi_nop_in_hdr_t *)resp->isp_hdr;
2544         bzero(in, sizeof (*in));
2545         in->opcode = ISCSI_OP_NOOP_IN;
2546         in->flags = ISCSI_FLAG_FINAL;
2547         bcopy(out->lun, in->lun, 8);
2548         in->itt              = out->itt;
2549         in->ttt              = ISCSI_RSVD_TASK_TAG;
2550         hton24(in->dlength, resp_datalen);
2551         resp->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2552         /* Any other field in resp to be set? */
2553         iscsit_pdu_tx(resp);
2554         idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2555 }
2556 
2557 static void
2558 iscsit_pdu_op_login_cmd(iscsit_conn_t   *ict, idm_pdu_t *rx_pdu)
2559 {
2560 
2561         /*
2562          * Submit PDU to login state machine.  State machine will free the
2563          * PDU.
2564          */
2565         iscsit_login_sm_event(ict, ILE_LOGIN_RCV, rx_pdu);
2566 }
2567 
2568 void
2569 iscsit_pdu_op_logout_cmd(iscsit_conn_t  *ict, idm_pdu_t *rx_pdu)
2570 {
2571         iscsi_logout_hdr_t      *logout_req =
2572             (iscsi_logout_hdr_t *)rx_pdu->isp_hdr;
2573         iscsi_logout_rsp_hdr_t  *logout_rsp;
2574         idm_pdu_t *resp;
2575 
2576         /* Allocate a PDU to respond */
2577         resp = idm_pdu_alloc(sizeof (iscsi_hdr_t), 0);
2578         idm_pdu_init(resp, ict->ict_ic, NULL, NULL);
2579         /*
2580          * The StatSN is to be sent to the initiator,
2581          * it is not required to increment the number
2582          * as the connection is terminating.
2583          */
2584         resp->isp_flags |= IDM_PDU_SET_STATSN;
2585         /*
2586          * Logout results in the immediate termination of all tasks except
2587          * if the logout reason is ISCSI_LOGOUT_REASON_RECOVERY.  The
2588          * connection state machine will drive this task cleanup automatically
2589          * so we don't need to handle that here.
2590          */
2591         logout_rsp = (iscsi_logout_rsp_hdr_t *)resp->isp_hdr;
2592         bzero(logout_rsp, sizeof (*logout_rsp));
2593         logout_rsp->opcode = ISCSI_OP_LOGOUT_RSP;
2594         logout_rsp->flags = ISCSI_FLAG_FINAL;
2595         logout_rsp->itt = logout_req->itt;
2596         if ((logout_req->flags & ISCSI_FLAG_LOGOUT_REASON_MASK) >
2597             ISCSI_LOGOUT_REASON_RECOVERY) {
2598                 logout_rsp->response = ISCSI_LOGOUT_RECOVERY_UNSUPPORTED;
2599         } else {
2600                 logout_rsp->response = ISCSI_LOGOUT_SUCCESS;
2601         }
2602 
2603         iscsit_pdu_tx(resp);
2604         idm_pdu_complete(rx_pdu, IDM_STATUS_SUCCESS);
2605 }
2606 
2607 /*
2608  * Calculate the number of outstanding commands we can process
2609  */
2610 int
2611 iscsit_cmd_window()
2612 {
2613         /*
2614          * Instead of using a pre-defined constant for the command window,
2615          * it should be made confiurable and dynamic. With MC/S, sequence
2616          * numbers will be used up at a much faster rate than with SC/S.
2617          */
2618         return  (ISCSIT_MAX_WINDOW);
2619 }
2620 
2621 /*
2622  * Set local registers based on incoming PDU
2623  */
2624 void
2625 iscsit_set_cmdsn(iscsit_conn_t *ict, idm_pdu_t *rx_pdu)
2626 {
2627         iscsit_sess_t *ist;
2628         iscsi_scsi_cmd_hdr_t *req;
2629 
2630         ist = ict->ict_sess;
2631 
2632         req = (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
2633         if (req->opcode & ISCSI_OP_IMMEDIATE) {
2634                 /* no cmdsn increment for immediate PDUs */
2635                 return;
2636         }
2637 
2638         /* Ensure that the ExpCmdSN advances in an orderly manner */
2639         mutex_enter(&ist->ist_sn_mutex);
2640         ist->ist_expcmdsn = ntohl(req->cmdsn) + 1;
2641         ist->ist_maxcmdsn = ntohl(req->cmdsn) + iscsit_cmd_window();
2642         mutex_exit(&ist->ist_sn_mutex);
2643 }
2644 
2645 /*
2646  * Wrapper funtion, calls iscsi_calc_rspsn and idm_pdu_tx
2647  */
2648 void
2649 iscsit_pdu_tx(idm_pdu_t *pdu)
2650 {
2651         iscsit_conn_t *ict = pdu->isp_ic->ic_handle;
2652         iscsi_scsi_rsp_hdr_t *rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
2653         iscsit_sess_t *ist = ict->ict_sess;
2654 
2655         /*
2656          * The command sequence numbers are session-wide and must stay
2657          * consistent across the transfer, so protect the cmdsn with a
2658          * mutex lock on the session. The status sequence number will
2659          * be updated just before the transport layer transmits the PDU.
2660          */
2661 
2662         mutex_enter(&ict->ict_sess->ist_sn_mutex);
2663         /* Set ExpCmdSN and MaxCmdSN */
2664         rsp->maxcmdsn = htonl(ist->ist_maxcmdsn);
2665         rsp->expcmdsn = htonl(ist->ist_expcmdsn);
2666         idm_pdu_tx(pdu);
2667         mutex_exit(&ict->ict_sess->ist_sn_mutex);
2668 }
2669 
2670 /*
2671  * Internal functions
2672  */
2673 
2674 void
2675 iscsit_send_async_event(iscsit_conn_t *ict, uint8_t event)
2676 {
2677         idm_pdu_t               *abt;
2678         iscsi_async_evt_hdr_t   *async_abt;
2679 
2680         /*
2681          * Get a PDU to build the abort request.
2682          */
2683         abt = idm_pdu_alloc(sizeof (iscsi_hdr_t), 0);
2684         if (abt == NULL) {
2685                 idm_conn_event(ict->ict_ic, CE_TRANSPORT_FAIL, NULL);
2686                 return;
2687         }
2688 
2689         /*
2690          * A asynchronous message is sent by the target to request a logout.
2691          * The StatSN for the connection is advanced after the PDU is sent
2692          * to allow for initiator and target state synchronization.
2693          */
2694         idm_pdu_init(abt, ict->ict_ic, NULL, NULL);
2695         abt->isp_datalen = 0;
2696         abt->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2697 
2698         async_abt = (iscsi_async_evt_hdr_t *)abt->isp_hdr;
2699         bzero(async_abt, sizeof (*async_abt));
2700         async_abt->opcode = ISCSI_OP_ASYNC_EVENT;
2701         async_abt->async_event = event;
2702         async_abt->flags = ISCSI_FLAG_FINAL;
2703         async_abt->rsvd4[0] = 0xff;
2704         async_abt->rsvd4[1] = 0xff;
2705         async_abt->rsvd4[2] = 0xff;
2706         async_abt->rsvd4[3] = 0xff;
2707 
2708         switch (event) {
2709         case ISCSI_ASYNC_EVENT_REQUEST_LOGOUT:
2710                 async_abt->param3 = htons(IDM_LOGOUT_SECONDS);
2711                 break;
2712         case ISCSI_ASYNC_EVENT_SCSI_EVENT:
2713         case ISCSI_ASYNC_EVENT_DROPPING_CONNECTION:
2714         case ISCSI_ASYNC_EVENT_DROPPING_ALL_CONNECTIONS:
2715         case ISCSI_ASYNC_EVENT_PARAM_NEGOTIATION:
2716         default:
2717                 ASSERT(0);
2718         }
2719 
2720         iscsit_pdu_tx(abt);
2721 }
2722 
2723 void
2724 iscsit_send_reject(iscsit_conn_t *ict, idm_pdu_t *rejected_pdu, uint8_t reason)
2725 {
2726         idm_pdu_t               *reject_pdu;
2727         iscsi_reject_rsp_hdr_t  *reject;
2728 
2729         /*
2730          * Get a PDU to build the abort request.
2731          */
2732         reject_pdu = idm_pdu_alloc(sizeof (iscsi_hdr_t),
2733             rejected_pdu->isp_hdrlen);
2734         if (reject_pdu == NULL) {
2735                 idm_conn_event(ict->ict_ic, CE_TRANSPORT_FAIL, NULL);
2736                 return;
2737         }
2738         idm_pdu_init(reject_pdu, ict->ict_ic, NULL, NULL);
2739         /* StatSN is advanced after a Reject PDU */
2740         reject_pdu->isp_flags |= IDM_PDU_SET_STATSN | IDM_PDU_ADVANCE_STATSN;
2741         reject_pdu->isp_datalen = rejected_pdu->isp_hdrlen;
2742         bcopy(rejected_pdu->isp_hdr, reject_pdu->isp_data,
2743             rejected_pdu->isp_hdrlen);
2744 
2745         reject = (iscsi_reject_rsp_hdr_t *)reject_pdu->isp_hdr;
2746         bzero(reject, sizeof (*reject));
2747         reject->opcode = ISCSI_OP_REJECT_MSG;
2748         reject->reason = reason;
2749         reject->flags = ISCSI_FLAG_FINAL;
2750         hton24(reject->dlength, rejected_pdu->isp_hdrlen);
2751         reject->must_be_ff[0] = 0xff;
2752         reject->must_be_ff[1] = 0xff;
2753         reject->must_be_ff[2] = 0xff;
2754         reject->must_be_ff[3] = 0xff;
2755 
2756         iscsit_pdu_tx(reject_pdu);
2757 }
2758 
2759 
2760 static iscsit_task_t *
2761 iscsit_task_alloc(iscsit_conn_t *ict)
2762 {
2763         iscsit_task_t *itask;
2764         iscsit_buf_t *immed_ibuf;
2765 
2766         /*
2767          * Possible items to pre-alloc if we cache iscsit_task_t's:
2768          *
2769          * Status PDU w/ sense buffer
2770          * stmf_data_buf_t for immediate data
2771          */
2772         itask = kmem_alloc(sizeof (iscsit_task_t) + sizeof (iscsit_buf_t) +
2773             sizeof (stmf_data_buf_t), KM_NOSLEEP);
2774         if (itask != NULL) {
2775                 mutex_init(&itask->it_mutex, NULL, MUTEX_DRIVER, NULL);
2776                 itask->it_aborted = itask->it_stmf_abort =
2777                     itask->it_tm_task = 0;
2778 
2779                 immed_ibuf = (iscsit_buf_t *)(itask + 1);
2780                 bzero(immed_ibuf, sizeof (*immed_ibuf));
2781                 immed_ibuf->ibuf_is_immed = B_TRUE;
2782                 immed_ibuf->ibuf_stmf_buf = (stmf_data_buf_t *)(immed_ibuf + 1);
2783 
2784                 bzero(immed_ibuf->ibuf_stmf_buf, sizeof (stmf_data_buf_t));
2785                 immed_ibuf->ibuf_stmf_buf->db_port_private = immed_ibuf;
2786                 immed_ibuf->ibuf_stmf_buf->db_sglist_length = 1;
2787                 immed_ibuf->ibuf_stmf_buf->db_flags = DB_DIRECTION_FROM_RPORT |
2788                     DB_DONT_CACHE;
2789                 itask->it_immed_data = immed_ibuf;
2790                 itask->it_idm_task = idm_task_alloc(ict->ict_ic);
2791                 if (itask->it_idm_task != NULL) {
2792                         itask->it_idm_task->idt_private = itask;
2793                         itask->it_ict = ict;
2794                         itask->it_ttt = itask->it_idm_task->idt_tt;
2795                         return (itask);
2796                 } else {
2797                         kmem_free(itask, sizeof (iscsit_task_t) +
2798                             sizeof (iscsit_buf_t) + sizeof (stmf_data_buf_t));
2799                 }
2800         }
2801 
2802         return (NULL);
2803 }
2804 
2805 static void
2806 iscsit_task_free(iscsit_task_t *itask)
2807 {
2808         idm_task_free(itask->it_idm_task);
2809         mutex_destroy(&itask->it_mutex);
2810         kmem_free(itask, sizeof (iscsit_task_t) +
2811             sizeof (iscsit_buf_t) + sizeof (stmf_data_buf_t));
2812 }
2813 
2814 static iscsit_task_t *
2815 iscsit_tm_task_alloc(iscsit_conn_t *ict)
2816 {
2817         iscsit_task_t *itask;
2818 
2819         itask = kmem_zalloc(sizeof (iscsit_task_t), KM_NOSLEEP);
2820         if (itask != NULL) {
2821                 idm_conn_hold(ict->ict_ic);
2822                 mutex_init(&itask->it_mutex, NULL, MUTEX_DRIVER, NULL);
2823                 itask->it_aborted = itask->it_stmf_abort =
2824                     itask->it_tm_responded = 0;
2825                 itask->it_tm_pdu = NULL;
2826                 itask->it_tm_task = 1;
2827                 itask->it_ict = ict;
2828         }
2829 
2830         return (itask);
2831 }
2832 
2833 static void
2834 iscsit_tm_task_free(iscsit_task_t *itask)
2835 {
2836         /*
2837          * If we responded then the call to idm_pdu_complete will free the
2838          * PDU.  Otherwise we got aborted before the TM function could
2839          * complete and we need to free the PDU explicitly.
2840          */
2841         if (itask->it_tm_pdu != NULL && !itask->it_tm_responded)
2842                 idm_pdu_free(itask->it_tm_pdu);
2843         idm_conn_rele(itask->it_ict->ict_ic);
2844         mutex_destroy(&itask->it_mutex);
2845         kmem_free(itask, sizeof (iscsit_task_t));
2846 }
2847 
2848 static idm_status_t
2849 iscsit_task_start(iscsit_task_t *itask)
2850 {
2851         iscsit_sess_t *ist = itask->it_ict->ict_sess;
2852         avl_index_t             where;
2853 
2854         /*
2855          * Sanity check the ITT and ensure that this task does not already
2856          * exist.  If not then add the task to the session task list.
2857          */
2858         mutex_enter(&ist->ist_mutex);
2859         mutex_enter(&itask->it_mutex);
2860         itask->it_active = 1;
2861         if (avl_find(&ist->ist_task_list, itask, &where) == NULL) {
2862                 /* New task, add to AVL */
2863                 avl_insert(&ist->ist_task_list, itask, where);
2864                 mutex_exit(&itask->it_mutex);
2865                 mutex_exit(&ist->ist_mutex);
2866                 return (IDM_STATUS_SUCCESS);
2867         }
2868         mutex_exit(&itask->it_mutex);
2869         mutex_exit(&ist->ist_mutex);
2870 
2871         return (IDM_STATUS_REJECT);
2872 }
2873 
2874 static void
2875 iscsit_task_done(iscsit_task_t *itask)
2876 {
2877         iscsit_sess_t *ist = itask->it_ict->ict_sess;
2878 
2879         mutex_enter(&ist->ist_mutex);
2880         mutex_enter(&itask->it_mutex);
2881         if (itask->it_active) {
2882                 avl_remove(&ist->ist_task_list, itask);
2883                 itask->it_active = 0;
2884         }
2885         mutex_exit(&itask->it_mutex);
2886         mutex_exit(&ist->ist_mutex);
2887 }
2888 
2889 /*
2890  * iscsit status PDU cache
2891  */
2892 
2893 /*ARGSUSED*/
2894 static int
2895 iscsit_status_pdu_constructor(void *pdu_void, void *arg, int flags)
2896 {
2897         idm_pdu_t *pdu = pdu_void;
2898         iscsi_scsi_rsp_hdr_t *rsp;
2899 
2900         bzero(pdu, sizeof (idm_pdu_t));
2901         pdu->isp_callback = iscsit_send_good_status_done;
2902         pdu->isp_magic = IDM_PDU_MAGIC;
2903         pdu->isp_hdr = (iscsi_hdr_t *)(pdu + 1); /* Ptr arithmetic */
2904         pdu->isp_hdrlen = sizeof (iscsi_hdr_t);
2905 
2906         /* Setup status response */
2907         rsp = (iscsi_scsi_rsp_hdr_t *)pdu->isp_hdr;
2908         bzero(rsp, sizeof (*rsp));
2909         rsp->opcode = ISCSI_OP_SCSI_RSP;
2910         rsp->flags = ISCSI_FLAG_FINAL;
2911         rsp->response = ISCSI_STATUS_CMD_COMPLETED;
2912 
2913         return (0);
2914 }
2915 
2916 /*
2917  * iscsit private data handler
2918  */
2919 
2920 /*ARGSUSED*/
2921 static void
2922 iscsit_pp_cb(struct stmf_port_provider *pp, int cmd, void *arg, uint32_t flags)
2923 {
2924         it_config_t             *cfg;
2925         nvlist_t                *nvl;
2926         iscsit_service_enabled_t        old_state;
2927 
2928         if ((cmd != STMF_PROVIDER_DATA_UPDATED) || (arg == NULL)) {
2929                 return;
2930         }
2931 
2932         nvl = (nvlist_t *)arg;
2933 
2934         /* Translate nvlist */
2935         if (it_nv_to_config(nvl, &cfg) != 0) {
2936                 cmn_err(CE_WARN, "Configuration is invalid");
2937                 return;
2938         }
2939 
2940         /* Check that no iSCSI ioctl is currently running */
2941         mutex_enter(&iscsit_global.global_state_mutex);
2942         old_state = iscsit_global.global_svc_state;
2943         switch (iscsit_global.global_svc_state) {
2944         case ISE_ENABLED:
2945         case ISE_DISABLED:
2946                 iscsit_global.global_svc_state = ISE_BUSY;
2947                 break;
2948         case ISE_ENABLING:
2949                 /*
2950                  * It is OK for the iscsit_pp_cb to be called from inside of
2951                  * an iSCSI ioctl only if we are currently executing inside
2952                  * of stmf_register_port_provider.
2953                  */
2954                 ASSERT((flags & STMF_PCB_PREG_COMPLETE) != 0);
2955                 break;
2956         default:
2957                 cmn_err(CE_WARN, "iscsit_pp_cb called when global_svc_state"
2958                     " is not ENABLED(0x%x) -- ignoring",
2959                     iscsit_global.global_svc_state);
2960                 mutex_exit(&iscsit_global.global_state_mutex);
2961                 it_config_free_cmn(cfg);
2962                 return;
2963         }
2964         mutex_exit(&iscsit_global.global_state_mutex);
2965 
2966         /* Update config */
2967         (void) iscsit_config_merge(cfg);
2968 
2969         it_config_free_cmn(cfg);
2970 
2971         /* Restore old iSCSI driver global state */
2972         mutex_enter(&iscsit_global.global_state_mutex);
2973         ASSERT(iscsit_global.global_svc_state == ISE_BUSY ||
2974             iscsit_global.global_svc_state == ISE_ENABLING);
2975         iscsit_global.global_svc_state = old_state;
2976         mutex_exit(&iscsit_global.global_state_mutex);
2977 }
2978 
2979 
2980 static it_cfg_status_t
2981 iscsit_config_merge(it_config_t *in_cfg)
2982 {
2983         it_cfg_status_t status;
2984         it_config_t     *cfg;
2985         it_config_t     tmp_cfg;
2986         list_t          tpg_del_list;
2987 
2988         if (in_cfg) {
2989                 cfg = in_cfg;
2990         } else {
2991                 /* Make empty config */
2992                 bzero(&tmp_cfg, sizeof (tmp_cfg));
2993                 cfg = &tmp_cfg;
2994         }
2995 
2996         list_create(&tpg_del_list,  sizeof (iscsit_tpg_t),
2997             offsetof(iscsit_tpg_t, tpg_delete_ln));
2998 
2999         /*
3000          * Update targets, initiator contexts, target portal groups,
3001          * and iSNS client
3002          */
3003         ISCSIT_GLOBAL_LOCK(RW_WRITER);
3004         if (((status = iscsit_config_merge_tpg(cfg, &tpg_del_list))
3005             != 0) ||
3006             ((status = iscsit_config_merge_tgt(cfg)) != 0) ||
3007             ((status = iscsit_config_merge_ini(cfg)) != 0) ||
3008             ((status = isnst_config_merge(cfg)) != 0)) {
3009                 ISCSIT_GLOBAL_UNLOCK();
3010                 return (status);
3011         }
3012 
3013         /* Update other global config parameters */
3014         if (iscsit_global.global_props) {
3015                 nvlist_free(iscsit_global.global_props);
3016                 iscsit_global.global_props = NULL;
3017         }
3018         if (in_cfg) {
3019                 (void) nvlist_dup(cfg->config_global_properties,
3020                     &iscsit_global.global_props, KM_SLEEP);
3021         }
3022         ISCSIT_GLOBAL_UNLOCK();
3023 
3024         iscsit_config_destroy_tpgs(&tpg_del_list);
3025 
3026         list_destroy(&tpg_del_list);
3027 
3028         return (ITCFG_SUCCESS);
3029 }
3030 
3031 /*
3032  * iscsit_sna_lt[e]
3033  *
3034  * Compare serial numbers using serial number arithmetic as defined in
3035  * RFC 1982.
3036  *
3037  * NOTE: This code is duplicated in the isns server. It ought to be common.
3038  */
3039 
3040 static int
3041 iscsit_sna_lt(uint32_t sn1, uint32_t sn2)
3042 {
3043         return ((sn1 != sn2) &&
3044             (((sn1 < sn2) && ((sn2 - sn1) < ISCSIT_SNA32_CHECK)) ||
3045             ((sn1 > sn2) && ((sn1 - sn2) > ISCSIT_SNA32_CHECK))));
3046 }
3047 
3048 static int
3049 iscsit_sna_lte(uint32_t sn1, uint32_t sn2)
3050 {
3051         return ((sn1 == sn2) ||
3052             (((sn1 < sn2) && ((sn2 - sn1) < ISCSIT_SNA32_CHECK)) ||
3053             ((sn1 > sn2) && ((sn1 - sn2) > ISCSIT_SNA32_CHECK))));
3054 }
3055 
3056 
3057 static boolean_t
3058 iscsit_cmdsn_in_window(iscsit_conn_t *ict, uint32_t cmdsn)
3059 {
3060         iscsit_sess_t   *ist = ict->ict_sess;
3061         int             rval = B_TRUE;
3062 
3063         ist = ict->ict_sess;
3064 
3065         mutex_enter(&ist->ist_sn_mutex);
3066 
3067         /*
3068          * If cmdsn is less than ist_expcmdsn - iscsit_cmd_window() or
3069          * greater than ist_expcmdsn, it's not in the window.
3070          */
3071 
3072         if (iscsit_sna_lt(cmdsn, (ist->ist_expcmdsn - iscsit_cmd_window())) ||
3073             !iscsit_sna_lte(cmdsn, ist->ist_expcmdsn)) {
3074                 rval = B_FALSE;
3075         }
3076 
3077         mutex_exit(&ist->ist_sn_mutex);
3078 
3079         return (rval);
3080 }
3081 
3082 /*
3083  * iscsit_check_cmdsn_and_queue
3084  *
3085  * Independent of the order in which the iSCSI target receives non-immediate
3086  * command PDU across the entire session and any multiple connections within
3087  * the session, the target must deliver the commands to the SCSI layer in
3088  * CmdSN order. So out-of-order non-immediate commands are queued up on a
3089  * session-wide wait queue. Duplicate commands are ignored.
3090  *
3091  */
3092 static int
3093 iscsit_check_cmdsn_and_queue(idm_pdu_t *rx_pdu)
3094 {
3095         idm_conn_t              *ic = rx_pdu->isp_ic;
3096         iscsit_conn_t           *ict = ic->ic_handle;
3097         iscsit_sess_t           *ist = ict->ict_sess;
3098         iscsi_scsi_cmd_hdr_t    *hdr = (iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr;
3099 
3100         mutex_enter(&ist->ist_sn_mutex);
3101         if (hdr->opcode & ISCSI_OP_IMMEDIATE) {
3102                 /* do not queue, handle it immediately */
3103                 DTRACE_PROBE2(immediate__cmd, iscsit_sess_t *, ist,
3104                     idm_pdu_t *, rx_pdu);
3105                 mutex_exit(&ist->ist_sn_mutex);
3106                 return (ISCSIT_CMDSN_EQ_EXPCMDSN);
3107         }
3108         if (iscsit_sna_lt(ist->ist_expcmdsn, ntohl(hdr->cmdsn))) {
3109                 /*
3110                  * Out-of-order commands (cmdSN higher than ExpCmdSN)
3111                  * are staged on a fixed-size circular buffer until
3112                  * the missing command is delivered to the SCSI layer.
3113                  * Irrespective of the order of insertion into the
3114                  * staging queue, the commands are processed out of the
3115                  * queue in cmdSN order only.
3116                  */
3117                 rx_pdu->isp_queue_time = ddi_get_time();
3118                 iscsit_add_pdu_to_queue(ist, rx_pdu);
3119                 mutex_exit(&ist->ist_sn_mutex);
3120                 return (ISCSIT_CMDSN_GT_EXPCMDSN);
3121         } else if (iscsit_sna_lt(ntohl(hdr->cmdsn), ist->ist_expcmdsn)) {
3122                 DTRACE_PROBE3(cmdsn__lt__expcmdsn, iscsit_sess_t *, ist,
3123                     iscsit_conn_t *, ict, idm_pdu_t *, rx_pdu);
3124                 mutex_exit(&ist->ist_sn_mutex);
3125                 return (ISCSIT_CMDSN_LT_EXPCMDSN);
3126         } else {
3127                 mutex_exit(&ist->ist_sn_mutex);
3128                 return (ISCSIT_CMDSN_EQ_EXPCMDSN);
3129         }
3130 }
3131 
3132 /*
3133  * iscsit_add_pdu_to_queue() adds PDUs into the array indexed by
3134  * their cmdsn value. The length of the array is kept above the
3135  * maximum window size. The window keeps the cmdsn within a range
3136  * such that there are no collisons. e.g. the assumption is that
3137  * the windowing checks make it impossible to receive PDUs that
3138  * index into the same location in the array.
3139  */
3140 static void
3141 iscsit_add_pdu_to_queue(iscsit_sess_t *ist, idm_pdu_t *rx_pdu)
3142 {
3143         iscsit_cbuf_t   *cbuf   = ist->ist_rxpdu_queue;
3144         iscsit_conn_t   *ict    = rx_pdu->isp_ic->ic_handle;
3145         uint32_t        cmdsn   =
3146             ((iscsi_scsi_cmd_hdr_t *)rx_pdu->isp_hdr)->cmdsn;
3147         uint32_t        index;
3148 
3149         ASSERT(MUTEX_HELD(&ist->ist_sn_mutex));
3150         /*
3151          * If the connection is being torn down, then
3152          * don't add the PDU to the staging queue
3153          */
3154         mutex_enter(&ict->ict_mutex);
3155         if (ict->ict_lost) {
3156                 mutex_exit(&ict->ict_mutex);
3157                 idm_pdu_complete(rx_pdu, IDM_STATUS_FAIL);
3158                 return;
3159         }
3160         iscsit_conn_dispatch_hold(ict);
3161         mutex_exit(&ict->ict_mutex);
3162 
3163         index = ntohl(cmdsn) % ISCSIT_RXPDU_QUEUE_LEN;
3164         ASSERT(cbuf->cb_buffer[index] == NULL);
3165         cbuf->cb_buffer[index] = rx_pdu;
3166         cbuf->cb_num_elems++;
3167 }
3168 
3169 static idm_pdu_t *
3170 iscsit_remove_pdu_from_queue(iscsit_sess_t *ist, uint32_t cmdsn)
3171 {
3172         iscsit_cbuf_t   *cbuf   = ist->ist_rxpdu_queue;
3173         idm_pdu_t       *pdu    = NULL;
3174         uint32_t        index;
3175 
3176         ASSERT(MUTEX_HELD(&ist->ist_sn_mutex));
3177         index = cmdsn % ISCSIT_RXPDU_QUEUE_LEN;
3178         if ((pdu = cbuf->cb_buffer[index]) != NULL) {
3179                 ASSERT(cmdsn ==
3180                     ntohl(((iscsi_scsi_cmd_hdr_t *)pdu->isp_hdr)->cmdsn));
3181                 cbuf->cb_buffer[index] = NULL;
3182                 cbuf->cb_num_elems--;
3183                 return (pdu);
3184         }
3185         return (NULL);
3186 }
3187 
3188 /*
3189  * iscsit_process_pdu_in_queue() finds the next pdu in sequence
3190  * and posts it to the SCSI layer
3191  */
3192 static void
3193 iscsit_process_pdu_in_queue(iscsit_sess_t *ist)
3194 {
3195         iscsit_cbuf_t   *cbuf   = ist->ist_rxpdu_queue;
3196         idm_pdu_t       *pdu = NULL;
3197         uint32_t        expcmdsn;
3198 
3199         for (;;) {
3200                 mutex_enter(&ist->ist_sn_mutex);
3201                 if (cbuf->cb_num_elems == 0) {
3202                         mutex_exit(&ist->ist_sn_mutex);
3203                         break;
3204                 }
3205                 expcmdsn = ist->ist_expcmdsn;
3206                 if ((pdu = iscsit_remove_pdu_from_queue(ist, expcmdsn))
3207                     == NULL) {
3208                         mutex_exit(&ist->ist_sn_mutex);
3209                         break;
3210                 }
3211                 mutex_exit(&ist->ist_sn_mutex);
3212                 iscsit_post_staged_pdu(pdu);
3213         }
3214 }
3215 
3216 static void
3217 iscsit_post_staged_pdu(idm_pdu_t *rx_pdu)
3218 {
3219         iscsit_conn_t   *ict    = rx_pdu->isp_ic->ic_handle;
3220 
3221         /* Post the PDU to the SCSI layer */
3222         switch (IDM_PDU_OPCODE(rx_pdu)) {
3223         case ISCSI_OP_NOOP_OUT:
3224                 iscsit_set_cmdsn(ict, rx_pdu);
3225                 iscsit_pdu_op_noop(ict, rx_pdu);
3226                 break;
3227         case ISCSI_OP_TEXT_CMD:
3228                 iscsit_set_cmdsn(ict, rx_pdu);
3229                 iscsit_pdu_op_text_cmd(ict, rx_pdu);
3230                 break;
3231         case ISCSI_OP_SCSI_TASK_MGT_MSG:
3232                 iscsit_set_cmdsn(ict, rx_pdu);
3233                 iscsit_op_scsi_task_mgmt(ict, rx_pdu);
3234                 break;
3235         case ISCSI_OP_SCSI_CMD:
3236                 /* cmdSN will be incremented after creating itask */
3237                 iscsit_post_scsi_cmd(rx_pdu->isp_ic, rx_pdu);
3238                 break;
3239         case ISCSI_OP_LOGOUT_CMD:
3240                 iscsit_set_cmdsn(ict, rx_pdu);
3241                 iscsit_pdu_op_logout_cmd(ict, rx_pdu);
3242                 break;
3243         default:
3244                 /* No other PDUs should be placed on the queue */
3245                 ASSERT(0);
3246         }
3247         iscsit_conn_dispatch_rele(ict); /* release hold on the conn */
3248 }
3249 
3250 /* ARGSUSED */
3251 void
3252 iscsit_rxpdu_queue_monitor_start(void)
3253 {
3254         mutex_enter(&iscsit_rxpdu_queue_monitor_mutex);
3255         if (iscsit_rxpdu_queue_monitor_thr_running) {
3256                 mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3257                 return;
3258         }
3259         iscsit_rxpdu_queue_monitor_thr_id =
3260             thread_create(NULL, 0, iscsit_rxpdu_queue_monitor, NULL,
3261             0, &p0, TS_RUN, minclsyspri);
3262         while (!iscsit_rxpdu_queue_monitor_thr_running) {
3263                 cv_wait(&iscsit_rxpdu_queue_monitor_cv,
3264                     &iscsit_rxpdu_queue_monitor_mutex);
3265         }
3266         mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3267 
3268 }
3269 
3270 /* ARGSUSED */
3271 void
3272 iscsit_rxpdu_queue_monitor_stop(void)
3273 {
3274         mutex_enter(&iscsit_rxpdu_queue_monitor_mutex);
3275         if (iscsit_rxpdu_queue_monitor_thr_running) {
3276                 iscsit_rxpdu_queue_monitor_thr_running = B_FALSE;
3277                 cv_signal(&iscsit_rxpdu_queue_monitor_cv);
3278                 mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3279 
3280                 thread_join(iscsit_rxpdu_queue_monitor_thr_did);
3281                 return;
3282         }
3283         mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3284 }
3285 
3286 /*
3287  * A separate thread is used to scan the staging queue on all the
3288  * sessions, If a delayed PDU does not arrive within a timeout, the
3289  * target will advance to the staged PDU that is next in sequence
3290  * and exceeded the threshold wait time. It is up to the initiator
3291  * to note that the target has not acknowledged a particular cmdsn
3292  * and take appropriate action.
3293  */
3294 /* ARGSUSED */
3295 static void
3296 iscsit_rxpdu_queue_monitor(void *arg)
3297 {
3298         iscsit_tgt_t    *tgt;
3299         iscsit_sess_t   *ist;
3300 
3301         mutex_enter(&iscsit_rxpdu_queue_monitor_mutex);
3302         iscsit_rxpdu_queue_monitor_thr_did = curthread->t_did;
3303         iscsit_rxpdu_queue_monitor_thr_running = B_TRUE;
3304         cv_signal(&iscsit_rxpdu_queue_monitor_cv);
3305 
3306         while (iscsit_rxpdu_queue_monitor_thr_running) {
3307                 ISCSIT_GLOBAL_LOCK(RW_READER);
3308                 for (tgt = avl_first(&iscsit_global.global_target_list);
3309                     tgt != NULL;
3310                     tgt = AVL_NEXT(&iscsit_global.global_target_list, tgt)) {
3311                         mutex_enter(&tgt->target_mutex);
3312                         for (ist = avl_first(&tgt->target_sess_list);
3313                             ist != NULL;
3314                             ist = AVL_NEXT(&tgt->target_sess_list, ist)) {
3315 
3316                                 iscsit_rxpdu_queue_monitor_session(ist);
3317                         }
3318                         mutex_exit(&tgt->target_mutex);
3319                 }
3320                 ISCSIT_GLOBAL_UNLOCK();
3321                 if (iscsit_rxpdu_queue_monitor_thr_running == B_FALSE) {
3322                         break;
3323                 }
3324                 (void) cv_reltimedwait(&iscsit_rxpdu_queue_monitor_cv,
3325                     &iscsit_rxpdu_queue_monitor_mutex,
3326                     ISCSIT_RXPDU_QUEUE_MONITOR_INTERVAL * drv_usectohz(1000000),
3327                     TR_CLOCK_TICK);
3328         }
3329         mutex_exit(&iscsit_rxpdu_queue_monitor_mutex);
3330         thread_exit();
3331 }
3332 
3333 static void
3334 iscsit_rxpdu_queue_monitor_session(iscsit_sess_t *ist)
3335 {
3336         iscsit_cbuf_t   *cbuf   = ist->ist_rxpdu_queue;
3337         idm_pdu_t       *next_pdu = NULL;
3338         uint32_t        index, next_cmdsn, i;
3339 
3340         /*
3341          * Assume that all PDUs in the staging queue have a cmdsn >= expcmdsn.
3342          * Starting with the expcmdsn, iterate over the staged PDUs to find
3343          * the next PDU with a wait time greater than the threshold. If found
3344          * advance the staged PDU to the SCSI layer, skipping over the missing
3345          * PDU(s) to get past the hole in the command sequence. It is up to
3346          * the initiator to note that the target has not acknowledged a cmdsn
3347          * and take appropriate action.
3348          *
3349          * Since the PDU(s) arrive in any random order, it is possible that
3350          * that the actual wait time for a particular PDU is much longer than
3351          * the defined threshold. e.g. Consider a case where commands are sent
3352          * over 4 different connections, and cmdsn = 1004 arrives first, then
3353          * 1003, and 1002 and 1001 are lost due to a connection failure.
3354          * So now 1003 is waiting for 1002 to be delivered, and although the
3355          * wait time of 1004 > wait time of 1003, only 1003 will be considered
3356          * by the monitor thread. 1004 will be automatically processed by
3357          * iscsit_process_pdu_in_queue() once the scan is complete and the
3358          * expcmdsn becomes current.
3359          */
3360         mutex_enter(&ist->ist_sn_mutex);
3361         cbuf = ist->ist_rxpdu_queue;
3362         if (cbuf->cb_num_elems == 0) {
3363                 mutex_exit(&ist->ist_sn_mutex);
3364                 return;
3365         }
3366         for (next_pdu = NULL, i = 0; ; i++) {
3367                 next_cmdsn = ist->ist_expcmdsn + i; /* start at expcmdsn */
3368                 index = next_cmdsn % ISCSIT_RXPDU_QUEUE_LEN;
3369                 if ((next_pdu = cbuf->cb_buffer[index]) != NULL) {
3370                         /*
3371                          * If the PDU wait time has not exceeded threshold
3372                          * stop scanning the staging queue until the timer
3373                          * fires again
3374                          */
3375                         if ((ddi_get_time() - next_pdu->isp_queue_time)
3376                             < rxpdu_queue_threshold) {
3377                                 mutex_exit(&ist->ist_sn_mutex);
3378                                 return;
3379                         }
3380                         /*
3381                          * Remove the next PDU from the queue and post it
3382                          * to the SCSI layer, skipping over the missing
3383                          * PDU. Stop scanning the staging queue until
3384                          * the monitor timer fires again
3385                          */
3386                         (void) iscsit_remove_pdu_from_queue(ist, next_cmdsn);
3387                         mutex_exit(&ist->ist_sn_mutex);
3388                         DTRACE_PROBE3(advanced__to__blocked__cmdsn,
3389                             iscsit_sess_t *, ist, idm_pdu_t *, next_pdu,
3390                             uint32_t, next_cmdsn);
3391                         iscsit_post_staged_pdu(next_pdu);
3392                         /* Deliver any subsequent PDUs immediately */
3393                         iscsit_process_pdu_in_queue(ist);
3394                         return;
3395                 }
3396                 /*
3397                  * Skipping over i PDUs, e.g. a case where commands 1001 and
3398                  * 1002 are lost in the network, skip over both and post 1003
3399                  * expcmdsn then becomes 1004 at the end of the scan.
3400                  */
3401                 DTRACE_PROBE2(skipping__over__cmdsn, iscsit_sess_t *, ist,
3402                     uint32_t, next_cmdsn);
3403         }
3404         /*
3405          * following the assumption, staged cmdsn >= expcmdsn, this statement
3406          * is never reached.
3407          */
3408 }