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