drivers/xen/xen-scsiback.c

   1 /*
   2  * Xen SCSI backend driver
   3  *
   4  * Copyright (c) 2008, FUJITSU Limited
   5  *
   6  * Based on the blkback driver code.
   7  * Adaption to kernel taget core infrastructure taken from vhost/scsi.c
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License version 2
  11  * as published by the Free Software Foundation; or, when distributed
  12  * separately from the Linux kernel or incorporated into other
  13  * software packages, subject to the following license:
  14  *
  15  * Permission is hereby granted, free of charge, to any person obtaining a copy
  16  * of this source file (the "Software"), to deal in the Software without
  17  * restriction, including without limitation the rights to use, copy, modify,
  18  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  19  * and to permit persons to whom the Software is furnished to do so, subject to
  20  * the following conditions:
  21  *
  22  * The above copyright notice and this permission notice shall be included in
  23  * all copies or substantial portions of the Software.
  24  *
  25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  26  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  27  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  28  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  29  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  30  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  31  * IN THE SOFTWARE.
  32  */
  33
  34 #define pr_fmt(fmt) "xen-pvscsi: " fmt
  35
  36 #include <stdarg.h>
  37
  38 #include <linux/module.h>
  39 #include <linux/utsname.h>
  40 #include <linux/interrupt.h>
  41 #include <linux/slab.h>
  42 #include <linux/wait.h>
  43 #include <linux/sched.h>
  44 #include <linux/list.h>
  45 #include <linux/gfp.h>
  46 #include <linux/delay.h>
  47 #include <linux/spinlock.h>
  48 #include <linux/configfs.h>
  49
  50 #include <generated/utsrelease.h>
  51
  52 #include <scsi/scsi_host.h> /* SG_ALL */
  53
  54 #include <target/target_core_base.h>
  55 #include <target/target_core_fabric.h>
  56
  57 #include <asm/hypervisor.h>
  58
  59 #include <xen/xen.h>
  60 #include <xen/balloon.h>
  61 #include <xen/events.h>
  62 #include <xen/xenbus.h>
  63 #include <xen/grant_table.h>
  64 #include <xen/page.h>
  65
  66 #include <xen/interface/grant_table.h>
  67 #include <xen/interface/io/vscsiif.h>
  68
  69 #define VSCSI_VERSION   "v0.1"
  70 #define VSCSI_NAMELEN   32
  71
  72 struct ids_tuple {
  73         unsigned int hst;               /* host    */
  74         unsigned int chn;               /* channel */
  75         unsigned int tgt;               /* target  */
  76         unsigned int lun;               /* LUN     */
  77 };
  78
  79 struct v2p_entry {
  80         struct ids_tuple v;             /* translate from */
  81         struct scsiback_tpg *tpg;       /* translate to   */
  82         unsigned int lun;
  83         struct kref kref;
  84         struct list_head l;
  85 };
  86
  87 struct vscsibk_info {
  88         struct xenbus_device *dev;
  89
  90         domid_t domid;
  91         unsigned int irq;
  92
  93         struct vscsiif_back_ring ring;
  94         int ring_error;
  95
  96         spinlock_t ring_lock;
  97         atomic_t nr_unreplied_reqs;
  98
  99         spinlock_t v2p_lock;
 100         struct list_head v2p_entry_lists;
 101
 102         wait_queue_head_t waiting_to_free;
 103 };
 104
 105 /* theoretical maximum of grants for one request */
 106 #define VSCSI_MAX_GRANTS        (SG_ALL + VSCSIIF_SG_TABLESIZE)
 107
 108 /*
 109  * VSCSI_GRANT_BATCH is the maximum number of grants to be processed in one
 110  * call to map/unmap grants. Don't choose it too large, as there are arrays
 111  * with VSCSI_GRANT_BATCH elements allocated on the stack.
 112  */
 113 #define VSCSI_GRANT_BATCH       16
 114
 115 struct vscsibk_pend {
 116         uint16_t rqid;
 117
 118         uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE];
 119         uint8_t cmd_len;
 120
 121         uint8_t sc_data_direction;
 122         uint16_t n_sg;          /* real length of SG list */
 123         uint16_t n_grants;      /* SG pages and potentially SG list */
 124         uint32_t data_len;
 125         uint32_t result;
 126
 127         struct vscsibk_info *info;
 128         struct v2p_entry *v2p;
 129         struct scatterlist *sgl;
 130
 131         uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE];
 132
 133         grant_handle_t grant_handles[VSCSI_MAX_GRANTS];
 134         struct page *pages[VSCSI_MAX_GRANTS];
 135
 136         struct se_cmd se_cmd;
 137 };
 138
 139 struct scsiback_tmr {
 140         atomic_t tmr_complete;
 141         wait_queue_head_t tmr_wait;
 142 };
 143
 144 #define VSCSI_DEFAULT_SESSION_TAGS      128
 145
 146 struct scsiback_nexus {
 147         /* Pointer to TCM session for I_T Nexus */
 148         struct se_session *tvn_se_sess;
 149 };
 150
 151 struct scsiback_tport {
 152         /* SCSI protocol the tport is providing */
 153         u8 tport_proto_id;
 154         /* Binary World Wide unique Port Name for pvscsi Target port */
 155         u64 tport_wwpn;
 156         /* ASCII formatted WWPN for pvscsi Target port */
 157         char tport_name[VSCSI_NAMELEN];
 158         /* Returned by scsiback_make_tport() */
 159         struct se_wwn tport_wwn;
 160 };
 161
 162 struct scsiback_tpg {
 163         /* scsiback port target portal group tag for TCM */
 164         u16 tport_tpgt;
 165         /* track number of TPG Port/Lun Links wrt explicit I_T Nexus shutdown */
 166         int tv_tpg_port_count;
 167         /* xen-pvscsi references to tpg_nexus, protected by tv_tpg_mutex */
 168         int tv_tpg_fe_count;
 169         /* list for scsiback_list */
 170         struct list_head tv_tpg_list;
 171         /* Used to protect access for tpg_nexus */
 172         struct mutex tv_tpg_mutex;
 173         /* Pointer to the TCM pvscsi I_T Nexus for this TPG endpoint */
 174         struct scsiback_nexus *tpg_nexus;
 175         /* Pointer back to scsiback_tport */
 176         struct scsiback_tport *tport;
 177         /* Returned by scsiback_make_tpg() */
 178         struct se_portal_group se_tpg;
 179         /* alias used in xenstore */
 180         char param_alias[VSCSI_NAMELEN];
 181         /* list of info structures related to this target portal group */
 182         struct list_head info_list;
 183 };
 184
 185 #define SCSIBACK_INVALID_HANDLE (~0)
 186
 187 static bool log_print_stat;
 188 module_param(log_print_stat, bool, 0644);
 189
 190 static int scsiback_max_buffer_pages = 1024;
 191 module_param_named(max_buffer_pages, scsiback_max_buffer_pages, int, 0644);
 192 MODULE_PARM_DESC(max_buffer_pages,
 193 "Maximum number of free pages to keep in backend buffer");
 194
 195 static DEFINE_SPINLOCK(free_pages_lock);
 196 static int free_pages_num;
 197 static LIST_HEAD(scsiback_free_pages);
 198
 199 /* Global spinlock to protect scsiback TPG list */
 200 static DEFINE_MUTEX(scsiback_mutex);
 201 static LIST_HEAD(scsiback_list);
 202
 203 static void scsiback_get(struct vscsibk_info *info)
 204 {
 205         atomic_inc(&info->nr_unreplied_reqs);
 206 }
 207
 208 static void scsiback_put(struct vscsibk_info *info)
 209 {
 210         if (atomic_dec_and_test(&info->nr_unreplied_reqs))
 211                 wake_up(&info->waiting_to_free);
 212 }
 213
 214 static void put_free_pages(struct page **page, int num)
 215 {
 216         unsigned long flags;
 217         int i = free_pages_num + num, n = num;
 218
 219         if (num == 0)
 220                 return;
 221         if (i > scsiback_max_buffer_pages) {
 222                 n = min(num, i - scsiback_max_buffer_pages);
 223                 gnttab_free_pages(n, page + num - n);
 224                 n = num - n;
 225         }
 226         spin_lock_irqsave(&free_pages_lock, flags);
 227         for (i = 0; i < n; i++)
 228                 list_add(&page[i]->lru, &scsiback_free_pages);
 229         free_pages_num += n;
 230         spin_unlock_irqrestore(&free_pages_lock, flags);
 231 }
 232
 233 static int get_free_page(struct page **page)
 234 {
 235         unsigned long flags;
 236
 237         spin_lock_irqsave(&free_pages_lock, flags);
 238         if (list_empty(&scsiback_free_pages)) {
 239                 spin_unlock_irqrestore(&free_pages_lock, flags);
 240                 return gnttab_alloc_pages(1, page);
 241         }
 242         page[0] = list_first_entry(&scsiback_free_pages, struct page, lru);
 243         list_del(&page[0]->lru);
 244         free_pages_num--;
 245         spin_unlock_irqrestore(&free_pages_lock, flags);
 246         return 0;
 247 }
 248
 249 static unsigned long vaddr_page(struct page *page)
 250 {
 251         unsigned long pfn = page_to_pfn(page);
 252
 253         return (unsigned long)pfn_to_kaddr(pfn);
 254 }
 255
 256 static unsigned long vaddr(struct vscsibk_pend *req, int seg)
 257 {
 258         return vaddr_page(req->pages[seg]);
 259 }
 260
 261 static void scsiback_print_status(char *sense_buffer, int errors,
 262                                         struct vscsibk_pend *pending_req)
 263 {
 264         struct scsiback_tpg *tpg = pending_req->v2p->tpg;
 265
 266         pr_err("[%s:%d] cmnd[0]=%02x -> st=%02x msg=%02x host=%02x drv=%02x\n",
 267                tpg->tport->tport_name, pending_req->v2p->lun,
 268                pending_req->cmnd[0], status_byte(errors), msg_byte(errors),
 269                host_byte(errors), driver_byte(errors));
 270 }
 271
 272 static void scsiback_fast_flush_area(struct vscsibk_pend *req)
 273 {
 274         struct gnttab_unmap_grant_ref unmap[VSCSI_GRANT_BATCH];
 275         struct page *pages[VSCSI_GRANT_BATCH];
 276         unsigned int i, invcount = 0;
 277         grant_handle_t handle;
 278         int err;
 279
 280         kfree(req->sgl);
 281         req->sgl = NULL;
 282         req->n_sg = 0;
 283
 284         if (!req->n_grants)
 285                 return;
 286
 287         for (i = 0; i < req->n_grants; i++) {
 288                 handle = req->grant_handles[i];
 289                 if (handle == SCSIBACK_INVALID_HANDLE)
 290                         continue;
 291                 gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
 292                                     GNTMAP_host_map, handle);
 293                 req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
 294                 pages[invcount] = req->pages[i];
 295                 put_page(pages[invcount]);
 296                 invcount++;
 297                 if (invcount < VSCSI_GRANT_BATCH)
 298                         continue;
 299                 err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
 300                 BUG_ON(err);
 301                 invcount = 0;
 302         }
 303
 304         if (invcount) {
 305                 err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
 306                 BUG_ON(err);
 307         }
 308
 309         put_free_pages(req->pages, req->n_grants);
 310         req->n_grants = 0;
 311 }
 312
 313 static void scsiback_free_translation_entry(struct kref *kref)
 314 {
 315         struct v2p_entry *entry = container_of(kref, struct v2p_entry, kref);
 316         struct scsiback_tpg *tpg = entry->tpg;
 317
 318         mutex_lock(&tpg->tv_tpg_mutex);
 319         tpg->tv_tpg_fe_count--;
 320         mutex_unlock(&tpg->tv_tpg_mutex);
 321
 322         kfree(entry);
 323 }
 324
 325 static void scsiback_send_response(struct vscsibk_info *info,
 326                         char *sense_buffer, int32_t result, uint32_t resid,
 327                         uint16_t rqid)
 328 {
 329         struct vscsiif_response *ring_res;
 330         int notify;
 331         struct scsi_sense_hdr sshdr;
 332         unsigned long flags;
 333         unsigned len;
 334
 335         spin_lock_irqsave(&info->ring_lock, flags);
 336
 337         ring_res = RING_GET_RESPONSE(&info->ring, info->ring.rsp_prod_pvt);
 338         info->ring.rsp_prod_pvt++;
 339
 340         ring_res->rslt   = result;
 341         ring_res->rqid   = rqid;
 342
 343         if (sense_buffer != NULL &&
 344             scsi_normalize_sense(sense_buffer, VSCSIIF_SENSE_BUFFERSIZE,
 345                                  &sshdr)) {
 346                 len = min_t(unsigned, 8 + sense_buffer[7],
 347                             VSCSIIF_SENSE_BUFFERSIZE);
 348                 memcpy(ring_res->sense_buffer, sense_buffer, len);
 349                 ring_res->sense_len = len;
 350         } else {
 351                 ring_res->sense_len = 0;
 352         }
 353
 354         ring_res->residual_len = resid;
 355
 356         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&info->ring, notify);
 357         spin_unlock_irqrestore(&info->ring_lock, flags);
 358
 359         if (notify)
 360                 notify_remote_via_irq(info->irq);
 361 }
 362
 363 static void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result,
 364                         uint32_t resid, struct vscsibk_pend *pending_req)
 365 {
 366         scsiback_send_response(pending_req->info, sense_buffer, result,
 367                                resid, pending_req->rqid);
 368
 369         if (pending_req->v2p)
 370                 kref_put(&pending_req->v2p->kref,
 371                          scsiback_free_translation_entry);
 372 }
 373
 374 static void scsiback_cmd_done(struct vscsibk_pend *pending_req)
 375 {
 376         struct vscsibk_info *info = pending_req->info;
 377         unsigned char *sense_buffer;
 378         unsigned int resid;
 379         int errors;
 380
 381         sense_buffer = pending_req->sense_buffer;
 382         resid        = pending_req->se_cmd.residual_count;
 383         errors       = pending_req->result;
 384
 385         if (errors && log_print_stat)
 386                 scsiback_print_status(sense_buffer, errors, pending_req);
 387
 388         scsiback_fast_flush_area(pending_req);
 389         scsiback_do_resp_with_sense(sense_buffer, errors, resid, pending_req);
 390         scsiback_put(info);
 391         /*
 392          * Drop the extra KREF_ACK reference taken by target_submit_cmd_map_sgls()
 393          * ahead of scsiback_check_stop_free() ->  transport_generic_free_cmd()
 394          * final se_cmd->cmd_kref put.
 395          */
 396         target_put_sess_cmd(&pending_req->se_cmd);
 397 }
 398
 399 static void scsiback_cmd_exec(struct vscsibk_pend *pending_req)
 400 {
 401         struct se_cmd *se_cmd = &pending_req->se_cmd;
 402         struct se_session *sess = pending_req->v2p->tpg->tpg_nexus->tvn_se_sess;
 403         int rc;
 404
 405         scsiback_get(pending_req->info);
 406         se_cmd->tag = pending_req->rqid;
 407         rc = target_submit_cmd_map_sgls(se_cmd, sess, pending_req->cmnd,
 408                         pending_req->sense_buffer, pending_req->v2p->lun,
 409                         pending_req->data_len, 0,
 410                         pending_req->sc_data_direction, TARGET_SCF_ACK_KREF,
 411                         pending_req->sgl, pending_req->n_sg,
 412                         NULL, 0, NULL, 0);
 413         if (rc < 0) {
 414                 transport_send_check_condition_and_sense(se_cmd,
 415                                 TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
 416                 transport_generic_free_cmd(se_cmd, 0);
 417         }
 418 }
 419
 420 static int scsiback_gnttab_data_map_batch(struct gnttab_map_grant_ref *map,
 421         struct page **pg, grant_handle_t *grant, int cnt)
 422 {
 423         int err, i;
 424
 425         if (!cnt)
 426                 return 0;
 427
 428         err = gnttab_map_refs(map, NULL, pg, cnt);
 429         BUG_ON(err);
 430         for (i = 0; i < cnt; i++) {
 431                 if (unlikely(map[i].status != GNTST_okay)) {
 432                         pr_err("invalid buffer -- could not remap it\n");
 433                         map[i].handle = SCSIBACK_INVALID_HANDLE;
 434                         err = -ENOMEM;
 435                 } else {
 436                         get_page(pg[i]);
 437                 }
 438                 grant[i] = map[i].handle;
 439         }
 440         return err;
 441 }
 442
 443 static int scsiback_gnttab_data_map_list(struct vscsibk_pend *pending_req,
 444                         struct scsiif_request_segment *seg, struct page **pg,
 445                         grant_handle_t *grant, int cnt, u32 flags)
 446 {
 447         int mapcount = 0, i, err = 0;
 448         struct gnttab_map_grant_ref map[VSCSI_GRANT_BATCH];
 449         struct vscsibk_info *info = pending_req->info;
 450
 451         for (i = 0; i < cnt; i++) {
 452                 if (get_free_page(pg + mapcount)) {
 453                         put_free_pages(pg, mapcount);
 454                         pr_err("no grant page\n");
 455                         return -ENOMEM;
 456                 }
 457                 gnttab_set_map_op(&map[mapcount], vaddr_page(pg[mapcount]),
 458                                   flags, seg[i].gref, info->domid);
 459                 mapcount++;
 460                 if (mapcount < VSCSI_GRANT_BATCH)
 461                         continue;
 462                 err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
 463                 pg += mapcount;
 464                 grant += mapcount;
 465                 pending_req->n_grants += mapcount;
 466                 if (err)
 467                         return err;
 468                 mapcount = 0;
 469         }
 470         err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
 471         pending_req->n_grants += mapcount;
 472         return err;
 473 }
 474
 475 static int scsiback_gnttab_data_map(struct vscsiif_request *ring_req,
 476                                         struct vscsibk_pend *pending_req)
 477 {
 478         u32 flags;
 479         int i, err, n_segs, i_seg = 0;
 480         struct page **pg;
 481         struct scsiif_request_segment *seg;
 482         unsigned long end_seg = 0;
 483         unsigned int nr_segments = (unsigned int)ring_req->nr_segments;
 484         unsigned int nr_sgl = 0;
 485         struct scatterlist *sg;
 486         grant_handle_t *grant;
 487
 488         pending_req->n_sg = 0;
 489         pending_req->n_grants = 0;
 490         pending_req->data_len = 0;
 491
 492         nr_segments &= ~VSCSIIF_SG_GRANT;
 493         if (!nr_segments)
 494                 return 0;
 495
 496         if (nr_segments > VSCSIIF_SG_TABLESIZE) {
 497                 pr_debug("invalid parameter nr_seg = %d\n",
 498                         ring_req->nr_segments);
 499                 return -EINVAL;
 500         }
 501
 502         if (ring_req->nr_segments & VSCSIIF_SG_GRANT) {
 503                 err = scsiback_gnttab_data_map_list(pending_req, ring_req->seg,
 504                         pending_req->pages, pending_req->grant_handles,
 505                         nr_segments, GNTMAP_host_map | GNTMAP_readonly);
 506                 if (err)
 507                         return err;
 508                 nr_sgl = nr_segments;
 509                 nr_segments = 0;
 510                 for (i = 0; i < nr_sgl; i++) {
 511                         n_segs = ring_req->seg[i].length /
 512                                  sizeof(struct scsiif_request_segment);
 513                         if ((unsigned)ring_req->seg[i].offset +
 514                             (unsigned)ring_req->seg[i].length > PAGE_SIZE ||
 515                             n_segs * sizeof(struct scsiif_request_segment) !=
 516                             ring_req->seg[i].length)
 517                                 return -EINVAL;
 518                         nr_segments += n_segs;
 519                 }
 520                 if (nr_segments > SG_ALL) {
 521                         pr_debug("invalid nr_seg = %d\n", nr_segments);
 522                         return -EINVAL;
 523                 }
 524         }
 525
 526         /* free of (sgl) in fast_flush_area() */
 527         pending_req->sgl = kmalloc_array(nr_segments,
 528                                         sizeof(struct scatterlist), GFP_KERNEL);
 529         if (!pending_req->sgl)
 530                 return -ENOMEM;
 531
 532         sg_init_table(pending_req->sgl, nr_segments);
 533         pending_req->n_sg = nr_segments;
 534
 535         flags = GNTMAP_host_map;
 536         if (pending_req->sc_data_direction == DMA_TO_DEVICE)
 537                 flags |= GNTMAP_readonly;
 538
 539         pg = pending_req->pages + nr_sgl;
 540         grant = pending_req->grant_handles + nr_sgl;
 541         if (!nr_sgl) {
 542                 seg = ring_req->seg;
 543                 err = scsiback_gnttab_data_map_list(pending_req, seg,
 544                         pg, grant, nr_segments, flags);
 545                 if (err)
 546                         return err;
 547         } else {
 548                 for (i = 0; i < nr_sgl; i++) {
 549                         seg = (struct scsiif_request_segment *)(
 550                               vaddr(pending_req, i) + ring_req->seg[i].offset);
 551                         n_segs = ring_req->seg[i].length /
 552                                  sizeof(struct scsiif_request_segment);
 553                         err = scsiback_gnttab_data_map_list(pending_req, seg,
 554                                 pg, grant, n_segs, flags);
 555                         if (err)
 556                                 return err;
 557                         pg += n_segs;
 558                         grant += n_segs;
 559                 }
 560                 end_seg = vaddr(pending_req, 0) + ring_req->seg[0].offset;
 561                 seg = (struct scsiif_request_segment *)end_seg;
 562                 end_seg += ring_req->seg[0].length;
 563                 pg = pending_req->pages + nr_sgl;
 564         }
 565
 566         for_each_sg(pending_req->sgl, sg, nr_segments, i) {
 567                 sg_set_page(sg, pg[i], seg->length, seg->offset);
 568                 pending_req->data_len += seg->length;
 569                 seg++;
 570                 if (nr_sgl && (unsigned long)seg >= end_seg) {
 571                         i_seg++;
 572                         end_seg = vaddr(pending_req, i_seg) +
 573                                   ring_req->seg[i_seg].offset;
 574                         seg = (struct scsiif_request_segment *)end_seg;
 575                         end_seg += ring_req->seg[i_seg].length;
 576                 }
 577                 if (sg->offset >= PAGE_SIZE ||
 578                     sg->length > PAGE_SIZE ||
 579                     sg->offset + sg->length > PAGE_SIZE)
 580                         return -EINVAL;
 581         }
 582
 583         return 0;
 584 }
 585
 586 static void scsiback_disconnect(struct vscsibk_info *info)
 587 {
 588         wait_event(info->waiting_to_free,
 589                 atomic_read(&info->nr_unreplied_reqs) == 0);
 590
 591         unbind_from_irqhandler(info->irq, info);
 592         info->irq = 0;
 593         xenbus_unmap_ring_vfree(info->dev, info->ring.sring);
 594 }
 595
 596 static void scsiback_device_action(struct vscsibk_pend *pending_req,
 597         enum tcm_tmreq_table act, int tag)
 598 {
 599         struct scsiback_tpg *tpg = pending_req->v2p->tpg;
 600         struct scsiback_nexus *nexus = tpg->tpg_nexus;
 601         struct se_cmd *se_cmd = &pending_req->se_cmd;
 602         struct scsiback_tmr *tmr;
 603         u64 unpacked_lun = pending_req->v2p->lun;
 604         int rc, err = FAILED;
 605
 606         tmr = kzalloc(sizeof(struct scsiback_tmr), GFP_KERNEL);
 607         if (!tmr) {
 608                 target_put_sess_cmd(se_cmd);
 609                 goto err;
 610         }
 611
 612         init_waitqueue_head(&tmr->tmr_wait);
 613
 614         rc = target_submit_tmr(&pending_req->se_cmd, nexus->tvn_se_sess,
 615                                &pending_req->sense_buffer[0],
 616                                unpacked_lun, tmr, act, GFP_KERNEL,
 617                                tag, TARGET_SCF_ACK_KREF);
 618         if (rc)
 619                 goto err;
 620
 621         wait_event(tmr->tmr_wait, atomic_read(&tmr->tmr_complete));
 622
 623         err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ?
 624                 SUCCESS : FAILED;
 625
 626         scsiback_do_resp_with_sense(NULL, err, 0, pending_req);
 627         transport_generic_free_cmd(&pending_req->se_cmd, 1);
 628         return;
 629 err:
 630         if (tmr)
 631                 kfree(tmr);
 632         scsiback_do_resp_with_sense(NULL, err, 0, pending_req);
 633 }
 634
 635 /*
 636   Perform virtual to physical translation
 637 */
 638 static struct v2p_entry *scsiback_do_translation(struct vscsibk_info *info,
 639                         struct ids_tuple *v)
 640 {
 641         struct v2p_entry *entry;
 642         struct list_head *head = &(info->v2p_entry_lists);
 643         unsigned long flags;
 644
 645         spin_lock_irqsave(&info->v2p_lock, flags);
 646         list_for_each_entry(entry, head, l) {
 647                 if ((entry->v.chn == v->chn) &&
 648                     (entry->v.tgt == v->tgt) &&
 649                     (entry->v.lun == v->lun)) {
 650                         kref_get(&entry->kref);
 651                         goto out;
 652                 }
 653         }
 654         entry = NULL;
 655
 656 out:
 657         spin_unlock_irqrestore(&info->v2p_lock, flags);
 658         return entry;
 659 }
 660
 661 static struct vscsibk_pend *scsiback_get_pend_req(struct vscsiif_back_ring *ring,
 662                                 struct v2p_entry *v2p)
 663 {
 664         struct scsiback_tpg *tpg = v2p->tpg;
 665         struct scsiback_nexus *nexus = tpg->tpg_nexus;
 666         struct se_session *se_sess = nexus->tvn_se_sess;
 667         struct vscsibk_pend *req;
 668         int tag, i;
 669
 670         tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
 671         if (tag < 0) {
 672                 pr_err("Unable to obtain tag for vscsiif_request\n");
 673                 return ERR_PTR(-ENOMEM);
 674         }
 675
 676         req = &((struct vscsibk_pend *)se_sess->sess_cmd_map)[tag];
 677         memset(req, 0, sizeof(*req));
 678         req->se_cmd.map_tag = tag;
 679
 680         for (i = 0; i < VSCSI_MAX_GRANTS; i++)
 681                 req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
 682
 683         return req;
 684 }
 685
 686 static struct vscsibk_pend *prepare_pending_reqs(struct vscsibk_info *info,
 687                                 struct vscsiif_back_ring *ring,
 688                                 struct vscsiif_request *ring_req)
 689 {
 690         struct vscsibk_pend *pending_req;
 691         struct v2p_entry *v2p;
 692         struct ids_tuple vir;
 693
 694         /* request range check from frontend */
 695         if ((ring_req->sc_data_direction != DMA_BIDIRECTIONAL) &&
 696                 (ring_req->sc_data_direction != DMA_TO_DEVICE) &&
 697                 (ring_req->sc_data_direction != DMA_FROM_DEVICE) &&
 698                 (ring_req->sc_data_direction != DMA_NONE)) {
 699                 pr_debug("invalid parameter data_dir = %d\n",
 700                         ring_req->sc_data_direction);
 701                 return ERR_PTR(-EINVAL);
 702         }
 703         if (ring_req->cmd_len > VSCSIIF_MAX_COMMAND_SIZE) {
 704                 pr_debug("invalid parameter cmd_len = %d\n",
 705                         ring_req->cmd_len);
 706                 return ERR_PTR(-EINVAL);
 707         }
 708
 709         vir.chn = ring_req->channel;
 710         vir.tgt = ring_req->id;
 711         vir.lun = ring_req->lun;
 712
 713         v2p = scsiback_do_translation(info, &vir);
 714         if (!v2p) {
 715                 pr_debug("the v2p of (chn:%d, tgt:%d, lun:%d) doesn't exist.\n",
 716                          vir.chn, vir.tgt, vir.lun);
 717                 return ERR_PTR(-ENODEV);
 718         }
 719
 720         pending_req = scsiback_get_pend_req(ring, v2p);
 721         if (IS_ERR(pending_req)) {
 722                 kref_put(&v2p->kref, scsiback_free_translation_entry);
 723                 return ERR_PTR(-ENOMEM);
 724         }
 725         pending_req->rqid = ring_req->rqid;
 726         pending_req->info = info;
 727         pending_req->v2p = v2p;
 728         pending_req->sc_data_direction = ring_req->sc_data_direction;
 729         pending_req->cmd_len = ring_req->cmd_len;
 730         memcpy(pending_req->cmnd, ring_req->cmnd, pending_req->cmd_len);
 731
 732         return pending_req;
 733 }
 734
 735 static int scsiback_do_cmd_fn(struct vscsibk_info *info)
 736 {
 737         struct vscsiif_back_ring *ring = &info->ring;
 738         struct vscsiif_request ring_req;
 739         struct vscsibk_pend *pending_req;
 740         RING_IDX rc, rp;
 741         int more_to_do;
 742         uint32_t result;
 743
 744         rc = ring->req_cons;
 745         rp = ring->sring->req_prod;
 746         rmb();  /* guest system is accessing ring, too */
 747
 748         if (RING_REQUEST_PROD_OVERFLOW(ring, rp)) {
 749                 rc = ring->rsp_prod_pvt;
 750                 pr_warn("Dom%d provided bogus ring requests (%#x - %#x = %u). Halting ring processing\n",
 751                            info->domid, rp, rc, rp - rc);
 752                 info->ring_error = 1;
 753                 return 0;
 754         }
 755
 756         while ((rc != rp)) {
 757                 if (RING_REQUEST_CONS_OVERFLOW(ring, rc))
 758                         break;
 759
 760                 RING_COPY_REQUEST(ring, rc, &ring_req);
 761                 ring->req_cons = ++rc;
 762
 763                 pending_req = prepare_pending_reqs(info, ring, &ring_req);
 764                 if (IS_ERR(pending_req)) {
 765                         switch (PTR_ERR(pending_req)) {
 766                         case -ENODEV:
 767                                 result = DID_NO_CONNECT;
 768                                 break;
 769                         default:
 770                                 result = DRIVER_ERROR;
 771                                 break;
 772                         }
 773                         scsiback_send_response(info, NULL, result << 24, 0,
 774                                                ring_req.rqid);
 775                         return 1;
 776                 }
 777
 778                 switch (ring_req.act) {
 779                 case VSCSIIF_ACT_SCSI_CDB:
 780                         if (scsiback_gnttab_data_map(&ring_req, pending_req)) {
 781                                 scsiback_fast_flush_area(pending_req);
 782                                 scsiback_do_resp_with_sense(NULL,
 783                                                 DRIVER_ERROR << 24, 0, pending_req);
 784                                 transport_generic_free_cmd(&pending_req->se_cmd, 0);
 785                         } else {
 786                                 scsiback_cmd_exec(pending_req);
 787                         }
 788                         break;
 789                 case VSCSIIF_ACT_SCSI_ABORT:
 790                         scsiback_device_action(pending_req, TMR_ABORT_TASK,
 791                                 ring_req.ref_rqid);
 792                         break;
 793                 case VSCSIIF_ACT_SCSI_RESET:
 794                         scsiback_device_action(pending_req, TMR_LUN_RESET, 0);
 795                         break;
 796                 default:
 797                         pr_err_ratelimited("invalid request\n");
 798                         scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24, 0,
 799                                                     pending_req);
 800                         transport_generic_free_cmd(&pending_req->se_cmd, 0);
 801                         break;
 802                 }
 803
 804                 /* Yield point for this unbounded loop. */
 805                 cond_resched();
 806         }
 807
 808         RING_FINAL_CHECK_FOR_REQUESTS(&info->ring, more_to_do);
 809         return more_to_do;
 810 }
 811
 812 static irqreturn_t scsiback_irq_fn(int irq, void *dev_id)
 813 {
 814         struct vscsibk_info *info = dev_id;
 815
 816         if (info->ring_error)
 817                 return IRQ_HANDLED;
 818
 819         while (scsiback_do_cmd_fn(info))
 820                 cond_resched();
 821
 822         return IRQ_HANDLED;
 823 }
 824
 825 static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t ring_ref,
 826                         evtchn_port_t evtchn)
 827 {
 828         void *area;
 829         struct vscsiif_sring *sring;
 830         int err;
 831
 832         if (info->irq)
 833                 return -1;
 834
 835         err = xenbus_map_ring_valloc(info->dev, &ring_ref, 1, &area);
 836         if (err)
 837                 return err;
 838
 839         sring = (struct vscsiif_sring *)area;
 840         BACK_RING_INIT(&info->ring, sring, PAGE_SIZE);
 841
 842         err = bind_interdomain_evtchn_to_irq(info->domid, evtchn);
 843         if (err < 0)
 844                 goto unmap_page;
 845
 846         info->irq = err;
 847
 848         err = request_threaded_irq(info->irq, NULL, scsiback_irq_fn,
 849                                    IRQF_ONESHOT, "vscsiif-backend", info);
 850         if (err)
 851                 goto free_irq;
 852
 853         return 0;
 854
 855 free_irq:
 856         unbind_from_irqhandler(info->irq, info);
 857         info->irq = 0;
 858 unmap_page:
 859         xenbus_unmap_ring_vfree(info->dev, area);
 860
 861         return err;
 862 }
 863
 864 static int scsiback_map(struct vscsibk_info *info)
 865 {
 866         struct xenbus_device *dev = info->dev;
 867         unsigned int ring_ref, evtchn;
 868         int err;
 869
 870         err = xenbus_gather(XBT_NIL, dev->otherend,
 871                         "ring-ref", "%u", &ring_ref,
 872                         "event-channel", "%u", &evtchn, NULL);
 873         if (err) {
 874                 xenbus_dev_fatal(dev, err, "reading %s ring", dev->otherend);
 875                 return err;
 876         }
 877
 878         return scsiback_init_sring(info, ring_ref, evtchn);
 879 }
 880
 881 /*
 882   Check for a translation entry being present
 883 */
 884 static struct v2p_entry *scsiback_chk_translation_entry(
 885         struct vscsibk_info *info, struct ids_tuple *v)
 886 {
 887         struct list_head *head = &(info->v2p_entry_lists);
 888         struct v2p_entry *entry;
 889
 890         list_for_each_entry(entry, head, l)
 891                 if ((entry->v.chn == v->chn) &&
 892                     (entry->v.tgt == v->tgt) &&
 893                     (entry->v.lun == v->lun))
 894                         return entry;
 895
 896         return NULL;
 897 }
 898
 899 /*
 900   Add a new translation entry
 901 */
 902 static int scsiback_add_translation_entry(struct vscsibk_info *info,
 903                                           char *phy, struct ids_tuple *v)
 904 {
 905         int err = 0;
 906         struct v2p_entry *new;
 907         unsigned long flags;
 908         char *lunp;
 909         unsigned long long unpacked_lun;
 910         struct se_lun *se_lun;
 911         struct scsiback_tpg *tpg_entry, *tpg = NULL;
 912         char *error = "doesn't exist";
 913
 914         lunp = strrchr(phy, ':');
 915         if (!lunp) {
 916                 pr_err("illegal format of physical device %s\n", phy);
 917                 return -EINVAL;
 918         }
 919         *lunp = 0;
 920         lunp++;
 921         err = kstrtoull(lunp, 10, &unpacked_lun);
 922         if (err < 0) {
 923                 pr_err("lun number not valid: %s\n", lunp);
 924                 return err;
 925         }
 926
 927         mutex_lock(&scsiback_mutex);
 928         list_for_each_entry(tpg_entry, &scsiback_list, tv_tpg_list) {
 929                 if (!strcmp(phy, tpg_entry->tport->tport_name) ||
 930                     !strcmp(phy, tpg_entry->param_alias)) {
 931                         mutex_lock(&tpg_entry->se_tpg.tpg_lun_mutex);
 932                         hlist_for_each_entry(se_lun, &tpg_entry->se_tpg.tpg_lun_hlist, link) {
 933                                 if (se_lun->unpacked_lun == unpacked_lun) {
 934                                         if (!tpg_entry->tpg_nexus)
 935                                                 error = "nexus undefined";
 936                                         else
 937                                                 tpg = tpg_entry;
 938                                         break;
 939                                 }
 940                         }
 941                         mutex_unlock(&tpg_entry->se_tpg.tpg_lun_mutex);
 942                         break;
 943                 }
 944         }
 945         if (tpg) {
 946                 mutex_lock(&tpg->tv_tpg_mutex);
 947                 tpg->tv_tpg_fe_count++;
 948                 mutex_unlock(&tpg->tv_tpg_mutex);
 949         }
 950         mutex_unlock(&scsiback_mutex);
 951
 952         if (!tpg) {
 953                 pr_err("%s:%llu %s\n", phy, unpacked_lun, error);
 954                 return -ENODEV;
 955         }
 956
 957         new = kmalloc(sizeof(struct v2p_entry), GFP_KERNEL);
 958         if (new == NULL) {
 959                 err = -ENOMEM;
 960                 goto out_free;
 961         }
 962
 963         spin_lock_irqsave(&info->v2p_lock, flags);
 964
 965         /* Check double assignment to identical virtual ID */
 966         if (scsiback_chk_translation_entry(info, v)) {
 967                 pr_warn("Virtual ID is already used. Assignment was not performed.\n");
 968                 err = -EEXIST;
 969                 goto out;
 970         }
 971
 972         /* Create a new translation entry and add to the list */
 973         kref_init(&new->kref);
 974         new->v = *v;
 975         new->tpg = tpg;
 976         new->lun = unpacked_lun;
 977         list_add_tail(&new->l, &info->v2p_entry_lists);
 978
 979 out:
 980         spin_unlock_irqrestore(&info->v2p_lock, flags);
 981
 982 out_free:
 983         if (err) {
 984                 mutex_lock(&tpg->tv_tpg_mutex);
 985                 tpg->tv_tpg_fe_count--;
 986                 mutex_unlock(&tpg->tv_tpg_mutex);
 987                 kfree(new);
 988         }
 989
 990         return err;
 991 }
 992
 993 static void __scsiback_del_translation_entry(struct v2p_entry *entry)
 994 {
 995         list_del(&entry->l);
 996         kref_put(&entry->kref, scsiback_free_translation_entry);
 997 }
 998
 999 /*
1000   Delete the translation entry specified
1001 */
1002 static int scsiback_del_translation_entry(struct vscsibk_info *info,
1003                                           struct ids_tuple *v)
1004 {
1005         struct v2p_entry *entry;
1006         unsigned long flags;
1007         int ret = 0;
1008
1009         spin_lock_irqsave(&info->v2p_lock, flags);
1010         /* Find out the translation entry specified */
1011         entry = scsiback_chk_translation_entry(info, v);
1012         if (entry)
1013                 __scsiback_del_translation_entry(entry);
1014         else
1015                 ret = -ENOENT;
1016
1017         spin_unlock_irqrestore(&info->v2p_lock, flags);
1018         return ret;
1019 }
1020
1021 static void scsiback_do_add_lun(struct vscsibk_info *info, const char *state,
1022                                 char *phy, struct ids_tuple *vir, int try)
1023 {
1024         struct v2p_entry *entry;
1025         unsigned long flags;
1026
1027         if (try) {
1028                 spin_lock_irqsave(&info->v2p_lock, flags);
1029                 entry = scsiback_chk_translation_entry(info, vir);
1030                 spin_unlock_irqrestore(&info->v2p_lock, flags);
1031                 if (entry)
1032                         return;
1033         }
1034         if (!scsiback_add_translation_entry(info, phy, vir)) {
1035                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
1036                                   "%d", XenbusStateInitialised)) {
1037                         pr_err("xenbus_printf error %s\n", state);
1038                         scsiback_del_translation_entry(info, vir);
1039                 }
1040         } else if (!try) {
1041                 xenbus_printf(XBT_NIL, info->dev->nodename, state,
1042                               "%d", XenbusStateClosed);
1043         }
1044 }
1045
1046 static void scsiback_do_del_lun(struct vscsibk_info *info, const char *state,
1047                                 struct ids_tuple *vir)
1048 {
1049         if (!scsiback_del_translation_entry(info, vir)) {
1050                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
1051                                   "%d", XenbusStateClosed))
1052                         pr_err("xenbus_printf error %s\n", state);
1053         }
1054 }
1055
1056 #define VSCSIBACK_OP_ADD_OR_DEL_LUN     1
1057 #define VSCSIBACK_OP_UPDATEDEV_STATE    2
1058
1059 static void scsiback_do_1lun_hotplug(struct vscsibk_info *info, int op,
1060                                      char *ent)
1061 {
1062         int err;
1063         struct ids_tuple vir;
1064         char *val;
1065         int device_state;
1066         char phy[VSCSI_NAMELEN];
1067         char str[64];
1068         char state[64];
1069         struct xenbus_device *dev = info->dev;
1070
1071         /* read status */
1072         snprintf(state, sizeof(state), "vscsi-devs/%s/state", ent);
1073         err = xenbus_scanf(XBT_NIL, dev->nodename, state, "%u", &device_state);
1074         if (XENBUS_EXIST_ERR(err))
1075                 return;
1076
1077         /* physical SCSI device */
1078         snprintf(str, sizeof(str), "vscsi-devs/%s/p-dev", ent);
1079         val = xenbus_read(XBT_NIL, dev->nodename, str, NULL);
1080         if (IS_ERR(val)) {
1081                 xenbus_printf(XBT_NIL, dev->nodename, state,
1082                               "%d", XenbusStateClosed);
1083                 return;
1084         }
1085         strlcpy(phy, val, VSCSI_NAMELEN);
1086         kfree(val);
1087
1088         /* virtual SCSI device */
1089         snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", ent);
1090         err = xenbus_scanf(XBT_NIL, dev->nodename, str, "%u:%u:%u:%u",
1091                            &vir.hst, &vir.chn, &vir.tgt, &vir.lun);
1092         if (XENBUS_EXIST_ERR(err)) {
1093                 xenbus_printf(XBT_NIL, dev->nodename, state,
1094                               "%d", XenbusStateClosed);
1095                 return;
1096         }
1097
1098         switch (op) {
1099         case VSCSIBACK_OP_ADD_OR_DEL_LUN:
1100                 switch (device_state) {
1101                 case XenbusStateInitialising:
1102                         scsiback_do_add_lun(info, state, phy, &vir, 0);
1103                         break;
1104                 case XenbusStateConnected:
1105                         scsiback_do_add_lun(info, state, phy, &vir, 1);
1106                         break;
1107                 case XenbusStateClosing:
1108                         scsiback_do_del_lun(info, state, &vir);
1109                         break;
1110                 default:
1111                         break;
1112                 }
1113                 break;
1114
1115         case VSCSIBACK_OP_UPDATEDEV_STATE:
1116                 if (device_state == XenbusStateInitialised) {
1117                         /* modify vscsi-devs/dev-x/state */
1118                         if (xenbus_printf(XBT_NIL, dev->nodename, state,
1119                                           "%d", XenbusStateConnected)) {
1120                                 pr_err("xenbus_printf error %s\n", str);
1121                                 scsiback_del_translation_entry(info, &vir);
1122                                 xenbus_printf(XBT_NIL, dev->nodename, state,
1123                                               "%d", XenbusStateClosed);
1124                         }
1125                 }
1126                 break;
1127         /* When it is necessary, processing is added here. */
1128         default:
1129                 break;
1130         }
1131 }
1132
1133 static void scsiback_do_lun_hotplug(struct vscsibk_info *info, int op)
1134 {
1135         int i;
1136         char **dir;
1137         unsigned int ndir = 0;
1138
1139         dir = xenbus_directory(XBT_NIL, info->dev->nodename, "vscsi-devs",
1140                                &ndir);
1141         if (IS_ERR(dir))
1142                 return;
1143
1144         for (i = 0; i < ndir; i++)
1145                 scsiback_do_1lun_hotplug(info, op, dir[i]);
1146
1147         kfree(dir);
1148 }
1149
1150 static void scsiback_frontend_changed(struct xenbus_device *dev,
1151                                         enum xenbus_state frontend_state)
1152 {
1153         struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
1154
1155         switch (frontend_state) {
1156         case XenbusStateInitialising:
1157                 break;
1158
1159         case XenbusStateInitialised:
1160                 if (scsiback_map(info))
1161                         break;
1162
1163                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
1164                 xenbus_switch_state(dev, XenbusStateConnected);
1165                 break;
1166
1167         case XenbusStateConnected:
1168                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_UPDATEDEV_STATE);
1169
1170                 if (dev->state == XenbusStateConnected)
1171                         break;
1172
1173                 xenbus_switch_state(dev, XenbusStateConnected);
1174                 break;
1175
1176         case XenbusStateClosing:
1177                 if (info->irq)
1178                         scsiback_disconnect(info);
1179
1180                 xenbus_switch_state(dev, XenbusStateClosing);
1181                 break;
1182
1183         case XenbusStateClosed:
1184                 xenbus_switch_state(dev, XenbusStateClosed);
1185                 if (xenbus_dev_is_online(dev))
1186                         break;
1187                 /* fall through if not online */
1188         case XenbusStateUnknown:
1189                 device_unregister(&dev->dev);
1190                 break;
1191
1192         case XenbusStateReconfiguring:
1193                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
1194                 xenbus_switch_state(dev, XenbusStateReconfigured);
1195
1196                 break;
1197
1198         default:
1199                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
1200                                         frontend_state);
1201                 break;
1202         }
1203 }
1204
1205 /*
1206   Release the translation entry specfied
1207 */
1208 static void scsiback_release_translation_entry(struct vscsibk_info *info)
1209 {
1210         struct v2p_entry *entry, *tmp;
1211         struct list_head *head = &(info->v2p_entry_lists);
1212         unsigned long flags;
1213
1214         spin_lock_irqsave(&info->v2p_lock, flags);
1215
1216         list_for_each_entry_safe(entry, tmp, head, l)
1217                 __scsiback_del_translation_entry(entry);
1218
1219         spin_unlock_irqrestore(&info->v2p_lock, flags);
1220 }
1221
1222 static int scsiback_remove(struct xenbus_device *dev)
1223 {
1224         struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
1225
1226         if (info->irq)
1227                 scsiback_disconnect(info);
1228
1229         scsiback_release_translation_entry(info);
1230
1231         dev_set_drvdata(&dev->dev, NULL);
1232
1233         return 0;
1234 }
1235
1236 static int scsiback_probe(struct xenbus_device *dev,
1237                            const struct xenbus_device_id *id)
1238 {
1239         int err;
1240
1241         struct vscsibk_info *info = kzalloc(sizeof(struct vscsibk_info),
1242                                             GFP_KERNEL);
1243
1244         pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
1245
1246         if (!info) {
1247                 xenbus_dev_fatal(dev, -ENOMEM, "allocating backend structure");
1248                 return -ENOMEM;
1249         }
1250         info->dev = dev;
1251         dev_set_drvdata(&dev->dev, info);
1252
1253         info->domid = dev->otherend_id;
1254         spin_lock_init(&info->ring_lock);
1255         info->ring_error = 0;
1256         atomic_set(&info->nr_unreplied_reqs, 0);
1257         init_waitqueue_head(&info->waiting_to_free);
1258         info->dev = dev;
1259         info->irq = 0;
1260         INIT_LIST_HEAD(&info->v2p_entry_lists);
1261         spin_lock_init(&info->v2p_lock);
1262
1263         err = xenbus_printf(XBT_NIL, dev->nodename, "feature-sg-grant", "%u",
1264                             SG_ALL);
1265         if (err)
1266                 xenbus_dev_error(dev, err, "writing feature-sg-grant");
1267
1268         err = xenbus_switch_state(dev, XenbusStateInitWait);
1269         if (err)
1270                 goto fail;
1271
1272         return 0;
1273
1274 fail:
1275         pr_warn("%s failed\n", __func__);
1276         scsiback_remove(dev);
1277
1278         return err;
1279 }
1280
1281 static char *scsiback_dump_proto_id(struct scsiback_tport *tport)
1282 {
1283         switch (tport->tport_proto_id) {
1284         case SCSI_PROTOCOL_SAS:
1285                 return "SAS";
1286         case SCSI_PROTOCOL_FCP:
1287                 return "FCP";
1288         case SCSI_PROTOCOL_ISCSI:
1289                 return "iSCSI";
1290         default:
1291                 break;
1292         }
1293
1294         return "Unknown";
1295 }
1296
1297 static char *scsiback_get_fabric_wwn(struct se_portal_group *se_tpg)
1298 {
1299         struct scsiback_tpg *tpg = container_of(se_tpg,
1300                                 struct scsiback_tpg, se_tpg);
1301         struct scsiback_tport *tport = tpg->tport;
1302
1303         return &tport->tport_name[0];
1304 }
1305
1306 static u16 scsiback_get_tag(struct se_portal_group *se_tpg)
1307 {
1308         struct scsiback_tpg *tpg = container_of(se_tpg,
1309                                 struct scsiback_tpg, se_tpg);
1310         return tpg->tport_tpgt;
1311 }
1312
1313 static struct se_wwn *
1314 scsiback_make_tport(struct target_fabric_configfs *tf,
1315                      struct config_group *group,
1316                      const char *name)
1317 {
1318         struct scsiback_tport *tport;
1319         char *ptr;
1320         u64 wwpn = 0;
1321         int off = 0;
1322
1323         tport = kzalloc(sizeof(struct scsiback_tport), GFP_KERNEL);
1324         if (!tport)
1325                 return ERR_PTR(-ENOMEM);
1326
1327         tport->tport_wwpn = wwpn;
1328         /*
1329          * Determine the emulated Protocol Identifier and Target Port Name
1330          * based on the incoming configfs directory name.
1331          */
1332         ptr = strstr(name, "naa.");
1333         if (ptr) {
1334                 tport->tport_proto_id = SCSI_PROTOCOL_SAS;
1335                 goto check_len;
1336         }
1337         ptr = strstr(name, "fc.");
1338         if (ptr) {
1339                 tport->tport_proto_id = SCSI_PROTOCOL_FCP;
1340                 off = 3; /* Skip over "fc." */
1341                 goto check_len;
1342         }
1343         ptr = strstr(name, "iqn.");
1344         if (ptr) {
1345                 tport->tport_proto_id = SCSI_PROTOCOL_ISCSI;
1346                 goto check_len;
1347         }
1348
1349         pr_err("Unable to locate prefix for emulated Target Port: %s\n", name);
1350         kfree(tport);
1351         return ERR_PTR(-EINVAL);
1352
1353 check_len:
1354         if (strlen(name) >= VSCSI_NAMELEN) {
1355                 pr_err("Emulated %s Address: %s, exceeds max: %d\n", name,
1356                         scsiback_dump_proto_id(tport), VSCSI_NAMELEN);
1357                 kfree(tport);
1358                 return ERR_PTR(-EINVAL);
1359         }
1360         snprintf(&tport->tport_name[0], VSCSI_NAMELEN, "%s", &name[off]);
1361
1362         pr_debug("Allocated emulated Target %s Address: %s\n",
1363                  scsiback_dump_proto_id(tport), name);
1364
1365         return &tport->tport_wwn;
1366 }
1367
1368 static void scsiback_drop_tport(struct se_wwn *wwn)
1369 {
1370         struct scsiback_tport *tport = container_of(wwn,
1371                                 struct scsiback_tport, tport_wwn);
1372
1373         pr_debug("Deallocating emulated Target %s Address: %s\n",
1374                  scsiback_dump_proto_id(tport), tport->tport_name);
1375
1376         kfree(tport);
1377 }
1378
1379 static u32 scsiback_tpg_get_inst_index(struct se_portal_group *se_tpg)
1380 {
1381         return 1;
1382 }
1383
1384 static int scsiback_check_stop_free(struct se_cmd *se_cmd)
1385 {
1386         return transport_generic_free_cmd(se_cmd, 0);
1387 }
1388
1389 static void scsiback_release_cmd(struct se_cmd *se_cmd)
1390 {
1391         struct se_session *se_sess = se_cmd->se_sess;
1392         struct se_tmr_req *se_tmr = se_cmd->se_tmr_req;
1393
1394         if (se_tmr && se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) {
1395                 struct scsiback_tmr *tmr = se_tmr->fabric_tmr_ptr;
1396                 kfree(tmr);
1397         }
1398
1399         percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);
1400 }
1401
1402 static u32 scsiback_sess_get_index(struct se_session *se_sess)
1403 {
1404         return 0;
1405 }
1406
1407 static int scsiback_write_pending(struct se_cmd *se_cmd)
1408 {
1409         /* Go ahead and process the write immediately */
1410         target_execute_cmd(se_cmd);
1411
1412         return 0;
1413 }
1414
1415 static int scsiback_write_pending_status(struct se_cmd *se_cmd)
1416 {
1417         return 0;
1418 }
1419
1420 static void scsiback_set_default_node_attrs(struct se_node_acl *nacl)
1421 {
1422 }
1423
1424 static int scsiback_get_cmd_state(struct se_cmd *se_cmd)
1425 {
1426         return 0;
1427 }
1428
1429 static int scsiback_queue_data_in(struct se_cmd *se_cmd)
1430 {
1431         struct vscsibk_pend *pending_req = container_of(se_cmd,
1432                                 struct vscsibk_pend, se_cmd);
1433
1434         pending_req->result = SAM_STAT_GOOD;
1435         scsiback_cmd_done(pending_req);
1436         return 0;
1437 }
1438
1439 static int scsiback_queue_status(struct se_cmd *se_cmd)
1440 {
1441         struct vscsibk_pend *pending_req = container_of(se_cmd,
1442                                 struct vscsibk_pend, se_cmd);
1443
1444         if (se_cmd->sense_buffer &&
1445             ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
1446              (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE)))
1447                 pending_req->result = (DRIVER_SENSE << 24) |
1448                                       SAM_STAT_CHECK_CONDITION;
1449         else
1450                 pending_req->result = se_cmd->scsi_status;
1451
1452         scsiback_cmd_done(pending_req);
1453         return 0;
1454 }
1455
1456 static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd)
1457 {
1458         struct se_tmr_req *se_tmr = se_cmd->se_tmr_req;
1459         struct scsiback_tmr *tmr = se_tmr->fabric_tmr_ptr;
1460
1461         atomic_set(&tmr->tmr_complete, 1);
1462         wake_up(&tmr->tmr_wait);
1463 }
1464
1465 static void scsiback_aborted_task(struct se_cmd *se_cmd)
1466 {
1467 }
1468
1469 static ssize_t scsiback_tpg_param_alias_show(struct config_item *item,
1470                                              char *page)
1471 {
1472         struct se_portal_group *se_tpg = param_to_tpg(item);
1473         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1474                                                 se_tpg);
1475         ssize_t rb;
1476
1477         mutex_lock(&tpg->tv_tpg_mutex);
1478         rb = snprintf(page, PAGE_SIZE, "%s\n", tpg->param_alias);
1479         mutex_unlock(&tpg->tv_tpg_mutex);
1480
1481         return rb;
1482 }
1483
1484 static ssize_t scsiback_tpg_param_alias_store(struct config_item *item,
1485                                               const char *page, size_t count)
1486 {
1487         struct se_portal_group *se_tpg = param_to_tpg(item);
1488         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1489                                                 se_tpg);
1490         int len;
1491
1492         if (strlen(page) >= VSCSI_NAMELEN) {
1493                 pr_err("param alias: %s, exceeds max: %d\n", page,
1494                         VSCSI_NAMELEN);
1495                 return -EINVAL;
1496         }
1497
1498         mutex_lock(&tpg->tv_tpg_mutex);
1499         len = snprintf(tpg->param_alias, VSCSI_NAMELEN, "%s", page);
1500         if (tpg->param_alias[len - 1] == '\n')
1501                 tpg->param_alias[len - 1] = '\0';
1502         mutex_unlock(&tpg->tv_tpg_mutex);
1503
1504         return count;
1505 }
1506
1507 CONFIGFS_ATTR(scsiback_tpg_param_, alias);
1508
1509 static struct configfs_attribute *scsiback_param_attrs[] = {
1510         &scsiback_tpg_param_attr_alias,
1511         NULL,
1512 };
1513
1514 static int scsiback_alloc_sess_cb(struct se_portal_group *se_tpg,
1515                                   struct se_session *se_sess, void *p)
1516 {
1517         struct scsiback_tpg *tpg = container_of(se_tpg,
1518                                 struct scsiback_tpg, se_tpg);
1519
1520         tpg->tpg_nexus = p;
1521         return 0;
1522 }
1523
1524 static int scsiback_make_nexus(struct scsiback_tpg *tpg,
1525                                 const char *name)
1526 {
1527         struct scsiback_nexus *tv_nexus;
1528         int ret = 0;
1529
1530         mutex_lock(&tpg->tv_tpg_mutex);
1531         if (tpg->tpg_nexus) {
1532                 pr_debug("tpg->tpg_nexus already exists\n");
1533                 ret = -EEXIST;
1534                 goto out_unlock;
1535         }
1536
1537         tv_nexus = kzalloc(sizeof(struct scsiback_nexus), GFP_KERNEL);
1538         if (!tv_nexus) {
1539                 ret = -ENOMEM;
1540                 goto out_unlock;
1541         }
1542
1543         tv_nexus->tvn_se_sess = target_alloc_session(&tpg->se_tpg,
1544                                                      VSCSI_DEFAULT_SESSION_TAGS,
1545                                                      sizeof(struct vscsibk_pend),
1546                                                      TARGET_PROT_NORMAL, name,
1547                                                      tv_nexus, scsiback_alloc_sess_cb);
1548         if (IS_ERR(tv_nexus->tvn_se_sess)) {
1549                 kfree(tv_nexus);
1550                 ret = -ENOMEM;
1551                 goto out_unlock;
1552         }
1553
1554 out_unlock:
1555         mutex_unlock(&tpg->tv_tpg_mutex);
1556         return ret;
1557 }
1558
1559 static int scsiback_drop_nexus(struct scsiback_tpg *tpg)
1560 {
1561         struct se_session *se_sess;
1562         struct scsiback_nexus *tv_nexus;
1563
1564         mutex_lock(&tpg->tv_tpg_mutex);
1565         tv_nexus = tpg->tpg_nexus;
1566         if (!tv_nexus) {
1567                 mutex_unlock(&tpg->tv_tpg_mutex);
1568                 return -ENODEV;
1569         }
1570
1571         se_sess = tv_nexus->tvn_se_sess;
1572         if (!se_sess) {
1573                 mutex_unlock(&tpg->tv_tpg_mutex);
1574                 return -ENODEV;
1575         }
1576
1577         if (tpg->tv_tpg_port_count != 0) {
1578                 mutex_unlock(&tpg->tv_tpg_mutex);
1579                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG port count: %d\n",
1580                         tpg->tv_tpg_port_count);
1581                 return -EBUSY;
1582         }
1583
1584         if (tpg->tv_tpg_fe_count != 0) {
1585                 mutex_unlock(&tpg->tv_tpg_mutex);
1586                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG frontend count: %d\n",
1587                         tpg->tv_tpg_fe_count);
1588                 return -EBUSY;
1589         }
1590
1591         pr_debug("Removing I_T Nexus to emulated %s Initiator Port: %s\n",
1592                 scsiback_dump_proto_id(tpg->tport),
1593                 tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1594
1595         /*
1596          * Release the SCSI I_T Nexus to the emulated xen-pvscsi Target Port
1597          */
1598         transport_deregister_session(tv_nexus->tvn_se_sess);
1599         tpg->tpg_nexus = NULL;
1600         mutex_unlock(&tpg->tv_tpg_mutex);
1601
1602         kfree(tv_nexus);
1603         return 0;
1604 }
1605
1606 static ssize_t scsiback_tpg_nexus_show(struct config_item *item, char *page)
1607 {
1608         struct se_portal_group *se_tpg = to_tpg(item);
1609         struct scsiback_tpg *tpg = container_of(se_tpg,
1610                                 struct scsiback_tpg, se_tpg);
1611         struct scsiback_nexus *tv_nexus;
1612         ssize_t ret;
1613
1614         mutex_lock(&tpg->tv_tpg_mutex);
1615         tv_nexus = tpg->tpg_nexus;
1616         if (!tv_nexus) {
1617                 mutex_unlock(&tpg->tv_tpg_mutex);
1618                 return -ENODEV;
1619         }
1620         ret = snprintf(page, PAGE_SIZE, "%s\n",
1621                         tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1622         mutex_unlock(&tpg->tv_tpg_mutex);
1623
1624         return ret;
1625 }
1626
1627 static ssize_t scsiback_tpg_nexus_store(struct config_item *item,
1628                 const char *page, size_t count)
1629 {
1630         struct se_portal_group *se_tpg = to_tpg(item);
1631         struct scsiback_tpg *tpg = container_of(se_tpg,
1632                                 struct scsiback_tpg, se_tpg);
1633         struct scsiback_tport *tport_wwn = tpg->tport;
1634         unsigned char i_port[VSCSI_NAMELEN], *ptr, *port_ptr;
1635         int ret;
1636         /*
1637          * Shutdown the active I_T nexus if 'NULL' is passed.
1638          */
1639         if (!strncmp(page, "NULL", 4)) {
1640                 ret = scsiback_drop_nexus(tpg);
1641                 return (!ret) ? count : ret;
1642         }
1643         /*
1644          * Otherwise make sure the passed virtual Initiator port WWN matches
1645          * the fabric protocol_id set in scsiback_make_tport(), and call
1646          * scsiback_make_nexus().
1647          */
1648         if (strlen(page) >= VSCSI_NAMELEN) {
1649                 pr_err("Emulated NAA Sas Address: %s, exceeds max: %d\n",
1650                         page, VSCSI_NAMELEN);
1651                 return -EINVAL;
1652         }
1653         snprintf(&i_port[0], VSCSI_NAMELEN, "%s", page);
1654
1655         ptr = strstr(i_port, "naa.");
1656         if (ptr) {
1657                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
1658                         pr_err("Passed SAS Initiator Port %s does not match target port protoid: %s\n",
1659                                 i_port, scsiback_dump_proto_id(tport_wwn));
1660                         return -EINVAL;
1661                 }
1662                 port_ptr = &i_port[0];
1663                 goto check_newline;
1664         }
1665         ptr = strstr(i_port, "fc.");
1666         if (ptr) {
1667                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
1668                         pr_err("Passed FCP Initiator Port %s does not match target port protoid: %s\n",
1669                                 i_port, scsiback_dump_proto_id(tport_wwn));
1670                         return -EINVAL;
1671                 }
1672                 port_ptr = &i_port[3]; /* Skip over "fc." */
1673                 goto check_newline;
1674         }
1675         ptr = strstr(i_port, "iqn.");
1676         if (ptr) {
1677                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
1678                         pr_err("Passed iSCSI Initiator Port %s does not match target port protoid: %s\n",
1679                                 i_port, scsiback_dump_proto_id(tport_wwn));
1680                         return -EINVAL;
1681                 }
1682                 port_ptr = &i_port[0];
1683                 goto check_newline;
1684         }
1685         pr_err("Unable to locate prefix for emulated Initiator Port: %s\n",
1686                 i_port);
1687         return -EINVAL;
1688         /*
1689          * Clear any trailing newline for the NAA WWN
1690          */
1691 check_newline:
1692         if (i_port[strlen(i_port) - 1] == '\n')
1693                 i_port[strlen(i_port) - 1] = '\0';
1694
1695         ret = scsiback_make_nexus(tpg, port_ptr);
1696         if (ret < 0)
1697                 return ret;
1698
1699         return count;
1700 }
1701
1702 CONFIGFS_ATTR(scsiback_tpg_, nexus);
1703
1704 static struct configfs_attribute *scsiback_tpg_attrs[] = {
1705         &scsiback_tpg_attr_nexus,
1706         NULL,
1707 };
1708
1709 static ssize_t
1710 scsiback_wwn_version_show(struct config_item *item, char *page)
1711 {
1712         return sprintf(page, "xen-pvscsi fabric module %s on %s/%s on "
1713                 UTS_RELEASE"\n",
1714                 VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1715 }
1716
1717 CONFIGFS_ATTR_RO(scsiback_wwn_, version);
1718
1719 static struct configfs_attribute *scsiback_wwn_attrs[] = {
1720         &scsiback_wwn_attr_version,
1721         NULL,
1722 };
1723
1724 static char *scsiback_get_fabric_name(void)
1725 {
1726         return "xen-pvscsi";
1727 }
1728
1729 static int scsiback_port_link(struct se_portal_group *se_tpg,
1730                                struct se_lun *lun)
1731 {
1732         struct scsiback_tpg *tpg = container_of(se_tpg,
1733                                 struct scsiback_tpg, se_tpg);
1734
1735         mutex_lock(&tpg->tv_tpg_mutex);
1736         tpg->tv_tpg_port_count++;
1737         mutex_unlock(&tpg->tv_tpg_mutex);
1738
1739         return 0;
1740 }
1741
1742 static void scsiback_port_unlink(struct se_portal_group *se_tpg,
1743                                   struct se_lun *lun)
1744 {
1745         struct scsiback_tpg *tpg = container_of(se_tpg,
1746                                 struct scsiback_tpg, se_tpg);
1747
1748         mutex_lock(&tpg->tv_tpg_mutex);
1749         tpg->tv_tpg_port_count--;
1750         mutex_unlock(&tpg->tv_tpg_mutex);
1751 }
1752
1753 static struct se_portal_group *
1754 scsiback_make_tpg(struct se_wwn *wwn,
1755                    struct config_group *group,
1756                    const char *name)
1757 {
1758         struct scsiback_tport *tport = container_of(wwn,
1759                         struct scsiback_tport, tport_wwn);
1760
1761         struct scsiback_tpg *tpg;
1762         u16 tpgt;
1763         int ret;
1764
1765         if (strstr(name, "tpgt_") != name)
1766                 return ERR_PTR(-EINVAL);
1767         ret = kstrtou16(name + 5, 10, &tpgt);
1768         if (ret)
1769                 return ERR_PTR(ret);
1770
1771         tpg = kzalloc(sizeof(struct scsiback_tpg), GFP_KERNEL);
1772         if (!tpg)
1773                 return ERR_PTR(-ENOMEM);
1774
1775         mutex_init(&tpg->tv_tpg_mutex);
1776         INIT_LIST_HEAD(&tpg->tv_tpg_list);
1777         INIT_LIST_HEAD(&tpg->info_list);
1778         tpg->tport = tport;
1779         tpg->tport_tpgt = tpgt;
1780
1781         ret = core_tpg_register(wwn, &tpg->se_tpg, tport->tport_proto_id);
1782         if (ret < 0) {
1783                 kfree(tpg);
1784                 return NULL;
1785         }
1786         mutex_lock(&scsiback_mutex);
1787         list_add_tail(&tpg->tv_tpg_list, &scsiback_list);
1788         mutex_unlock(&scsiback_mutex);
1789
1790         return &tpg->se_tpg;
1791 }
1792
1793 static void scsiback_drop_tpg(struct se_portal_group *se_tpg)
1794 {
1795         struct scsiback_tpg *tpg = container_of(se_tpg,
1796                                 struct scsiback_tpg, se_tpg);
1797
1798         mutex_lock(&scsiback_mutex);
1799         list_del(&tpg->tv_tpg_list);
1800         mutex_unlock(&scsiback_mutex);
1801         /*
1802          * Release the virtual I_T Nexus for this xen-pvscsi TPG
1803          */
1804         scsiback_drop_nexus(tpg);
1805         /*
1806          * Deregister the se_tpg from TCM.
1807          */
1808         core_tpg_deregister(se_tpg);
1809         kfree(tpg);
1810 }
1811
1812 static int scsiback_check_true(struct se_portal_group *se_tpg)
1813 {
1814         return 1;
1815 }
1816
1817 static int scsiback_check_false(struct se_portal_group *se_tpg)
1818 {
1819         return 0;
1820 }
1821
1822 static const struct target_core_fabric_ops scsiback_ops = {
1823         .module                         = THIS_MODULE,
1824         .name                           = "xen-pvscsi",
1825         .get_fabric_name                = scsiback_get_fabric_name,
1826         .tpg_get_wwn                    = scsiback_get_fabric_wwn,
1827         .tpg_get_tag                    = scsiback_get_tag,
1828         .tpg_check_demo_mode            = scsiback_check_true,
1829         .tpg_check_demo_mode_cache      = scsiback_check_true,
1830         .tpg_check_demo_mode_write_protect = scsiback_check_false,
1831         .tpg_check_prod_mode_write_protect = scsiback_check_false,
1832         .tpg_get_inst_index             = scsiback_tpg_get_inst_index,
1833         .check_stop_free                = scsiback_check_stop_free,
1834         .release_cmd                    = scsiback_release_cmd,
1835         .sess_get_index                 = scsiback_sess_get_index,
1836         .sess_get_initiator_sid         = NULL,
1837         .write_pending                  = scsiback_write_pending,
1838         .write_pending_status           = scsiback_write_pending_status,
1839         .set_default_node_attributes    = scsiback_set_default_node_attrs,
1840         .get_cmd_state                  = scsiback_get_cmd_state,
1841         .queue_data_in                  = scsiback_queue_data_in,
1842         .queue_status                   = scsiback_queue_status,
1843         .queue_tm_rsp                   = scsiback_queue_tm_rsp,
1844         .aborted_task                   = scsiback_aborted_task,
1845         /*
1846          * Setup callers for generic logic in target_core_fabric_configfs.c
1847          */
1848         .fabric_make_wwn                = scsiback_make_tport,
1849         .fabric_drop_wwn                = scsiback_drop_tport,
1850         .fabric_make_tpg                = scsiback_make_tpg,
1851         .fabric_drop_tpg                = scsiback_drop_tpg,
1852         .fabric_post_link               = scsiback_port_link,
1853         .fabric_pre_unlink              = scsiback_port_unlink,
1854
1855         .tfc_wwn_attrs                  = scsiback_wwn_attrs,
1856         .tfc_tpg_base_attrs             = scsiback_tpg_attrs,
1857         .tfc_tpg_param_attrs            = scsiback_param_attrs,
1858 };
1859
1860 static const struct xenbus_device_id scsiback_ids[] = {
1861         { "vscsi" },
1862         { "" }
1863 };
1864
1865 static struct xenbus_driver scsiback_driver = {
1866         .ids                    = scsiback_ids,
1867         .probe                  = scsiback_probe,
1868         .remove                 = scsiback_remove,
1869         .otherend_changed       = scsiback_frontend_changed
1870 };
1871
1872 static int __init scsiback_init(void)
1873 {
1874         int ret;
1875
1876         if (!xen_domain())
1877                 return -ENODEV;
1878
1879         pr_debug("xen-pvscsi: fabric module %s on %s/%s on "UTS_RELEASE"\n",
1880                  VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1881
1882         ret = xenbus_register_backend(&scsiback_driver);
1883         if (ret)
1884                 goto out;
1885
1886         ret = target_register_template(&scsiback_ops);
1887         if (ret)
1888                 goto out_unregister_xenbus;
1889
1890         return 0;
1891
1892 out_unregister_xenbus:
1893         xenbus_unregister_driver(&scsiback_driver);
1894 out:
1895         pr_err("%s: error %d\n", __func__, ret);
1896         return ret;
1897 }
1898
1899 static void __exit scsiback_exit(void)
1900 {
1901         struct page *page;
1902
1903         while (free_pages_num) {
1904                 if (get_free_page(&page))
1905                         BUG();
1906                 gnttab_free_pages(1, &page);
1907         }
1908         target_unregister_template(&scsiback_ops);
1909         xenbus_unregister_driver(&scsiback_driver);
1910 }
1911
1912 module_init(scsiback_init);
1913 module_exit(scsiback_exit);
1914
1915 MODULE_DESCRIPTION("Xen SCSI backend driver");
1916 MODULE_LICENSE("Dual BSD/GPL");
1917 MODULE_ALIAS("xen-backend:vscsi");
1918 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");