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, cpu, i;
 658
 659         tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
 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         req->se_cmd.map_cpu = cpu;
 669
 670         for (i = 0; i < VSCSI_MAX_GRANTS; i++)
 671                 req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
 672
 673         return req;
 674 }
 675
 676 static struct vscsibk_pend *prepare_pending_reqs(struct vscsibk_info *info,
 677                                 struct vscsiif_back_ring *ring,
 678                                 struct vscsiif_request *ring_req)
 679 {
 680         struct vscsibk_pend *pending_req;
 681         struct v2p_entry *v2p;
 682         struct ids_tuple vir;
 683
 684         /* request range check from frontend */
 685         if ((ring_req->sc_data_direction != DMA_BIDIRECTIONAL) &&
 686                 (ring_req->sc_data_direction != DMA_TO_DEVICE) &&
 687                 (ring_req->sc_data_direction != DMA_FROM_DEVICE) &&
 688                 (ring_req->sc_data_direction != DMA_NONE)) {
 689                 pr_debug("invalid parameter data_dir = %d\n",
 690                         ring_req->sc_data_direction);
 691                 return ERR_PTR(-EINVAL);
 692         }
 693         if (ring_req->cmd_len > VSCSIIF_MAX_COMMAND_SIZE) {
 694                 pr_debug("invalid parameter cmd_len = %d\n",
 695                         ring_req->cmd_len);
 696                 return ERR_PTR(-EINVAL);
 697         }
 698
 699         vir.chn = ring_req->channel;
 700         vir.tgt = ring_req->id;
 701         vir.lun = ring_req->lun;
 702
 703         v2p = scsiback_do_translation(info, &vir);
 704         if (!v2p) {
 705                 pr_debug("the v2p of (chn:%d, tgt:%d, lun:%d) doesn't exist.\n",
 706                          vir.chn, vir.tgt, vir.lun);
 707                 return ERR_PTR(-ENODEV);
 708         }
 709
 710         pending_req = scsiback_get_pend_req(ring, v2p);
 711         if (IS_ERR(pending_req)) {
 712                 kref_put(&v2p->kref, scsiback_free_translation_entry);
 713                 return ERR_PTR(-ENOMEM);
 714         }
 715         pending_req->rqid = ring_req->rqid;
 716         pending_req->info = info;
 717         pending_req->v2p = v2p;
 718         pending_req->sc_data_direction = ring_req->sc_data_direction;
 719         pending_req->cmd_len = ring_req->cmd_len;
 720         memcpy(pending_req->cmnd, ring_req->cmnd, pending_req->cmd_len);
 721
 722         return pending_req;
 723 }
 724
 725 static int scsiback_do_cmd_fn(struct vscsibk_info *info)
 726 {
 727         struct vscsiif_back_ring *ring = &info->ring;
 728         struct vscsiif_request ring_req;
 729         struct vscsibk_pend *pending_req;
 730         RING_IDX rc, rp;
 731         int more_to_do;
 732         uint32_t result;
 733
 734         rc = ring->req_cons;
 735         rp = ring->sring->req_prod;
 736         rmb();  /* guest system is accessing ring, too */
 737
 738         if (RING_REQUEST_PROD_OVERFLOW(ring, rp)) {
 739                 rc = ring->rsp_prod_pvt;
 740                 pr_warn("Dom%d provided bogus ring requests (%#x - %#x = %u). Halting ring processing\n",
 741                            info->domid, rp, rc, rp - rc);
 742                 info->ring_error = 1;
 743                 return 0;
 744         }
 745
 746         while ((rc != rp)) {
 747                 if (RING_REQUEST_CONS_OVERFLOW(ring, rc))
 748                         break;
 749
 750                 RING_COPY_REQUEST(ring, rc, &ring_req);
 751                 ring->req_cons = ++rc;
 752
 753                 pending_req = prepare_pending_reqs(info, ring, &ring_req);
 754                 if (IS_ERR(pending_req)) {
 755                         switch (PTR_ERR(pending_req)) {
 756                         case -ENODEV:
 757                                 result = DID_NO_CONNECT;
 758                                 break;
 759                         default:
 760                                 result = DRIVER_ERROR;
 761                                 break;
 762                         }
 763                         scsiback_send_response(info, NULL, result << 24, 0,
 764                                                ring_req.rqid);
 765                         return 1;
 766                 }
 767
 768                 switch (ring_req.act) {
 769                 case VSCSIIF_ACT_SCSI_CDB:
 770                         if (scsiback_gnttab_data_map(&ring_req, pending_req)) {
 771                                 scsiback_fast_flush_area(pending_req);
 772                                 scsiback_do_resp_with_sense(NULL,
 773                                                 DRIVER_ERROR << 24, 0, pending_req);
 774                                 transport_generic_free_cmd(&pending_req->se_cmd, 0);
 775                         } else {
 776                                 scsiback_cmd_exec(pending_req);
 777                         }
 778                         break;
 779                 case VSCSIIF_ACT_SCSI_ABORT:
 780                         scsiback_device_action(pending_req, TMR_ABORT_TASK,
 781                                 ring_req.ref_rqid);
 782                         break;
 783                 case VSCSIIF_ACT_SCSI_RESET:
 784                         scsiback_device_action(pending_req, TMR_LUN_RESET, 0);
 785                         break;
 786                 default:
 787                         pr_err_ratelimited("invalid request\n");
 788                         scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24, 0,
 789                                                     pending_req);
 790                         transport_generic_free_cmd(&pending_req->se_cmd, 0);
 791                         break;
 792                 }
 793
 794                 /* Yield point for this unbounded loop. */
 795                 cond_resched();
 796         }
 797
 798         RING_FINAL_CHECK_FOR_REQUESTS(&info->ring, more_to_do);
 799         return more_to_do;
 800 }
 801
 802 static irqreturn_t scsiback_irq_fn(int irq, void *dev_id)
 803 {
 804         struct vscsibk_info *info = dev_id;
 805
 806         if (info->ring_error)
 807                 return IRQ_HANDLED;
 808
 809         while (scsiback_do_cmd_fn(info))
 810                 cond_resched();
 811
 812         return IRQ_HANDLED;
 813 }
 814
 815 static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t ring_ref,
 816                         evtchn_port_t evtchn)
 817 {
 818         void *area;
 819         struct vscsiif_sring *sring;
 820         int err;
 821
 822         if (info->irq)
 823                 return -1;
 824
 825         err = xenbus_map_ring_valloc(info->dev, &ring_ref, 1, &area);
 826         if (err)
 827                 return err;
 828
 829         sring = (struct vscsiif_sring *)area;
 830         BACK_RING_INIT(&info->ring, sring, PAGE_SIZE);
 831
 832         err = bind_interdomain_evtchn_to_irq(info->domid, evtchn);
 833         if (err < 0)
 834                 goto unmap_page;
 835
 836         info->irq = err;
 837
 838         err = request_threaded_irq(info->irq, NULL, scsiback_irq_fn,
 839                                    IRQF_ONESHOT, "vscsiif-backend", info);
 840         if (err)
 841                 goto free_irq;
 842
 843         return 0;
 844
 845 free_irq:
 846         unbind_from_irqhandler(info->irq, info);
 847         info->irq = 0;
 848 unmap_page:
 849         xenbus_unmap_ring_vfree(info->dev, area);
 850
 851         return err;
 852 }
 853
 854 static int scsiback_map(struct vscsibk_info *info)
 855 {
 856         struct xenbus_device *dev = info->dev;
 857         unsigned int ring_ref, evtchn;
 858         int err;
 859
 860         err = xenbus_gather(XBT_NIL, dev->otherend,
 861                         "ring-ref", "%u", &ring_ref,
 862                         "event-channel", "%u", &evtchn, NULL);
 863         if (err) {
 864                 xenbus_dev_fatal(dev, err, "reading %s ring", dev->otherend);
 865                 return err;
 866         }
 867
 868         return scsiback_init_sring(info, ring_ref, evtchn);
 869 }
 870
 871 /*
 872   Check for a translation entry being present
 873 */
 874 static struct v2p_entry *scsiback_chk_translation_entry(
 875         struct vscsibk_info *info, struct ids_tuple *v)
 876 {
 877         struct list_head *head = &(info->v2p_entry_lists);
 878         struct v2p_entry *entry;
 879
 880         list_for_each_entry(entry, head, l)
 881                 if ((entry->v.chn == v->chn) &&
 882                     (entry->v.tgt == v->tgt) &&
 883                     (entry->v.lun == v->lun))
 884                         return entry;
 885
 886         return NULL;
 887 }
 888
 889 /*
 890   Add a new translation entry
 891 */
 892 static int scsiback_add_translation_entry(struct vscsibk_info *info,
 893                                           char *phy, struct ids_tuple *v)
 894 {
 895         int err = 0;
 896         struct v2p_entry *new;
 897         unsigned long flags;
 898         char *lunp;
 899         unsigned long long unpacked_lun;
 900         struct se_lun *se_lun;
 901         struct scsiback_tpg *tpg_entry, *tpg = NULL;
 902         char *error = "doesn't exist";
 903
 904         lunp = strrchr(phy, ':');
 905         if (!lunp) {
 906                 pr_err("illegal format of physical device %s\n", phy);
 907                 return -EINVAL;
 908         }
 909         *lunp = 0;
 910         lunp++;
 911         err = kstrtoull(lunp, 10, &unpacked_lun);
 912         if (err < 0) {
 913                 pr_err("lun number not valid: %s\n", lunp);
 914                 return err;
 915         }
 916
 917         mutex_lock(&scsiback_mutex);
 918         list_for_each_entry(tpg_entry, &scsiback_list, tv_tpg_list) {
 919                 if (!strcmp(phy, tpg_entry->tport->tport_name) ||
 920                     !strcmp(phy, tpg_entry->param_alias)) {
 921                         mutex_lock(&tpg_entry->se_tpg.tpg_lun_mutex);
 922                         hlist_for_each_entry(se_lun, &tpg_entry->se_tpg.tpg_lun_hlist, link) {
 923                                 if (se_lun->unpacked_lun == unpacked_lun) {
 924                                         if (!tpg_entry->tpg_nexus)
 925                                                 error = "nexus undefined";
 926                                         else
 927                                                 tpg = tpg_entry;
 928                                         break;
 929                                 }
 930                         }
 931                         mutex_unlock(&tpg_entry->se_tpg.tpg_lun_mutex);
 932                         break;
 933                 }
 934         }
 935         if (tpg) {
 936                 mutex_lock(&tpg->tv_tpg_mutex);
 937                 tpg->tv_tpg_fe_count++;
 938                 mutex_unlock(&tpg->tv_tpg_mutex);
 939         }
 940         mutex_unlock(&scsiback_mutex);
 941
 942         if (!tpg) {
 943                 pr_err("%s:%llu %s\n", phy, unpacked_lun, error);
 944                 return -ENODEV;
 945         }
 946
 947         new = kmalloc(sizeof(struct v2p_entry), GFP_KERNEL);
 948         if (new == NULL) {
 949                 err = -ENOMEM;
 950                 goto out_free;
 951         }
 952
 953         spin_lock_irqsave(&info->v2p_lock, flags);
 954
 955         /* Check double assignment to identical virtual ID */
 956         if (scsiback_chk_translation_entry(info, v)) {
 957                 pr_warn("Virtual ID is already used. Assignment was not performed.\n");
 958                 err = -EEXIST;
 959                 goto out;
 960         }
 961
 962         /* Create a new translation entry and add to the list */
 963         kref_init(&new->kref);
 964         new->v = *v;
 965         new->tpg = tpg;
 966         new->lun = unpacked_lun;
 967         list_add_tail(&new->l, &info->v2p_entry_lists);
 968
 969 out:
 970         spin_unlock_irqrestore(&info->v2p_lock, flags);
 971
 972 out_free:
 973         if (err) {
 974                 mutex_lock(&tpg->tv_tpg_mutex);
 975                 tpg->tv_tpg_fe_count--;
 976                 mutex_unlock(&tpg->tv_tpg_mutex);
 977                 kfree(new);
 978         }
 979
 980         return err;
 981 }
 982
 983 static void __scsiback_del_translation_entry(struct v2p_entry *entry)
 984 {
 985         list_del(&entry->l);
 986         kref_put(&entry->kref, scsiback_free_translation_entry);
 987 }
 988
 989 /*
 990   Delete the translation entry specified
 991 */
 992 static int scsiback_del_translation_entry(struct vscsibk_info *info,
 993                                           struct ids_tuple *v)
 994 {
 995         struct v2p_entry *entry;
 996         unsigned long flags;
 997         int ret = 0;
 998
 999         spin_lock_irqsave(&info->v2p_lock, flags);
1000         /* Find out the translation entry specified */
1001         entry = scsiback_chk_translation_entry(info, v);
1002         if (entry)
1003                 __scsiback_del_translation_entry(entry);
1004         else
1005                 ret = -ENOENT;
1006
1007         spin_unlock_irqrestore(&info->v2p_lock, flags);
1008         return ret;
1009 }
1010
1011 static void scsiback_do_add_lun(struct vscsibk_info *info, const char *state,
1012                                 char *phy, struct ids_tuple *vir, int try)
1013 {
1014         struct v2p_entry *entry;
1015         unsigned long flags;
1016         int err;
1017
1018         if (try) {
1019                 spin_lock_irqsave(&info->v2p_lock, flags);
1020                 entry = scsiback_chk_translation_entry(info, vir);
1021                 spin_unlock_irqrestore(&info->v2p_lock, flags);
1022                 if (entry)
1023                         return;
1024         }
1025         if (!scsiback_add_translation_entry(info, phy, vir)) {
1026                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
1027                                   "%d", XenbusStateInitialised)) {
1028                         pr_err("xenbus_printf error %s\n", state);
1029                         scsiback_del_translation_entry(info, vir);
1030                 }
1031         } else if (!try) {
1032                 err = xenbus_printf(XBT_NIL, info->dev->nodename, state,
1033                               "%d", XenbusStateClosed);
1034                 if (err)
1035                         xenbus_dev_error(info->dev, err,
1036                                 "%s: writing %s", __func__, state);
1037         }
1038 }
1039
1040 static void scsiback_do_del_lun(struct vscsibk_info *info, const char *state,
1041                                 struct ids_tuple *vir)
1042 {
1043         if (!scsiback_del_translation_entry(info, vir)) {
1044                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
1045                                   "%d", XenbusStateClosed))
1046                         pr_err("xenbus_printf error %s\n", state);
1047         }
1048 }
1049
1050 #define VSCSIBACK_OP_ADD_OR_DEL_LUN     1
1051 #define VSCSIBACK_OP_UPDATEDEV_STATE    2
1052
1053 static void scsiback_do_1lun_hotplug(struct vscsibk_info *info, int op,
1054                                      char *ent)
1055 {
1056         int err;
1057         struct ids_tuple vir;
1058         char *val;
1059         int device_state;
1060         char phy[VSCSI_NAMELEN];
1061         char str[64];
1062         char state[64];
1063         struct xenbus_device *dev = info->dev;
1064
1065         /* read status */
1066         snprintf(state, sizeof(state), "vscsi-devs/%s/state", ent);
1067         err = xenbus_scanf(XBT_NIL, dev->nodename, state, "%u", &device_state);
1068         if (XENBUS_EXIST_ERR(err))
1069                 return;
1070
1071         /* physical SCSI device */
1072         snprintf(str, sizeof(str), "vscsi-devs/%s/p-dev", ent);
1073         val = xenbus_read(XBT_NIL, dev->nodename, str, NULL);
1074         if (IS_ERR(val)) {
1075                 err = xenbus_printf(XBT_NIL, dev->nodename, state,
1076                               "%d", XenbusStateClosed);
1077                 if (err)
1078                         xenbus_dev_error(info->dev, err,
1079                                 "%s: writing %s", __func__, state);
1080                 return;
1081         }
1082         strlcpy(phy, val, VSCSI_NAMELEN);
1083         kfree(val);
1084
1085         /* virtual SCSI device */
1086         snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", ent);
1087         err = xenbus_scanf(XBT_NIL, dev->nodename, str, "%u:%u:%u:%u",
1088                            &vir.hst, &vir.chn, &vir.tgt, &vir.lun);
1089         if (XENBUS_EXIST_ERR(err)) {
1090                 err = xenbus_printf(XBT_NIL, dev->nodename, state,
1091                               "%d", XenbusStateClosed);
1092                 if (err)
1093                         xenbus_dev_error(info->dev, err,
1094                                 "%s: writing %s", __func__, state);
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         target_free_tag(se_cmd->se_sess, se_cmd);
1392 }
1393
1394 static u32 scsiback_sess_get_index(struct se_session *se_sess)
1395 {
1396         return 0;
1397 }
1398
1399 static int scsiback_write_pending(struct se_cmd *se_cmd)
1400 {
1401         /* Go ahead and process the write immediately */
1402         target_execute_cmd(se_cmd);
1403
1404         return 0;
1405 }
1406
1407 static int scsiback_write_pending_status(struct se_cmd *se_cmd)
1408 {
1409         return 0;
1410 }
1411
1412 static void scsiback_set_default_node_attrs(struct se_node_acl *nacl)
1413 {
1414 }
1415
1416 static int scsiback_get_cmd_state(struct se_cmd *se_cmd)
1417 {
1418         return 0;
1419 }
1420
1421 static int scsiback_queue_data_in(struct se_cmd *se_cmd)
1422 {
1423         struct vscsibk_pend *pending_req = container_of(se_cmd,
1424                                 struct vscsibk_pend, se_cmd);
1425
1426         pending_req->result = SAM_STAT_GOOD;
1427         scsiback_cmd_done(pending_req);
1428         return 0;
1429 }
1430
1431 static int scsiback_queue_status(struct se_cmd *se_cmd)
1432 {
1433         struct vscsibk_pend *pending_req = container_of(se_cmd,
1434                                 struct vscsibk_pend, se_cmd);
1435
1436         if (se_cmd->sense_buffer &&
1437             ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
1438              (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE)))
1439                 pending_req->result = (DRIVER_SENSE << 24) |
1440                                       SAM_STAT_CHECK_CONDITION;
1441         else
1442                 pending_req->result = se_cmd->scsi_status;
1443
1444         scsiback_cmd_done(pending_req);
1445         return 0;
1446 }
1447
1448 static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd)
1449 {
1450         struct vscsibk_pend *pending_req = container_of(se_cmd,
1451                                 struct vscsibk_pend, se_cmd);
1452
1453         complete(&pending_req->tmr_done);
1454 }
1455
1456 static void scsiback_aborted_task(struct se_cmd *se_cmd)
1457 {
1458 }
1459
1460 static ssize_t scsiback_tpg_param_alias_show(struct config_item *item,
1461                                              char *page)
1462 {
1463         struct se_portal_group *se_tpg = param_to_tpg(item);
1464         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1465                                                 se_tpg);
1466         ssize_t rb;
1467
1468         mutex_lock(&tpg->tv_tpg_mutex);
1469         rb = snprintf(page, PAGE_SIZE, "%s\n", tpg->param_alias);
1470         mutex_unlock(&tpg->tv_tpg_mutex);
1471
1472         return rb;
1473 }
1474
1475 static ssize_t scsiback_tpg_param_alias_store(struct config_item *item,
1476                                               const char *page, size_t count)
1477 {
1478         struct se_portal_group *se_tpg = param_to_tpg(item);
1479         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1480                                                 se_tpg);
1481         int len;
1482
1483         if (strlen(page) >= VSCSI_NAMELEN) {
1484                 pr_err("param alias: %s, exceeds max: %d\n", page,
1485                         VSCSI_NAMELEN);
1486                 return -EINVAL;
1487         }
1488
1489         mutex_lock(&tpg->tv_tpg_mutex);
1490         len = snprintf(tpg->param_alias, VSCSI_NAMELEN, "%s", page);
1491         if (tpg->param_alias[len - 1] == '\n')
1492                 tpg->param_alias[len - 1] = '\0';
1493         mutex_unlock(&tpg->tv_tpg_mutex);
1494
1495         return count;
1496 }
1497
1498 CONFIGFS_ATTR(scsiback_tpg_param_, alias);
1499
1500 static struct configfs_attribute *scsiback_param_attrs[] = {
1501         &scsiback_tpg_param_attr_alias,
1502         NULL,
1503 };
1504
1505 static int scsiback_alloc_sess_cb(struct se_portal_group *se_tpg,
1506                                   struct se_session *se_sess, void *p)
1507 {
1508         struct scsiback_tpg *tpg = container_of(se_tpg,
1509                                 struct scsiback_tpg, se_tpg);
1510
1511         tpg->tpg_nexus = p;
1512         return 0;
1513 }
1514
1515 static int scsiback_make_nexus(struct scsiback_tpg *tpg,
1516                                 const char *name)
1517 {
1518         struct scsiback_nexus *tv_nexus;
1519         int ret = 0;
1520
1521         mutex_lock(&tpg->tv_tpg_mutex);
1522         if (tpg->tpg_nexus) {
1523                 pr_debug("tpg->tpg_nexus already exists\n");
1524                 ret = -EEXIST;
1525                 goto out_unlock;
1526         }
1527
1528         tv_nexus = kzalloc(sizeof(struct scsiback_nexus), GFP_KERNEL);
1529         if (!tv_nexus) {
1530                 ret = -ENOMEM;
1531                 goto out_unlock;
1532         }
1533
1534         tv_nexus->tvn_se_sess = target_setup_session(&tpg->se_tpg,
1535                                                      VSCSI_DEFAULT_SESSION_TAGS,
1536                                                      sizeof(struct vscsibk_pend),
1537                                                      TARGET_PROT_NORMAL, name,
1538                                                      tv_nexus, scsiback_alloc_sess_cb);
1539         if (IS_ERR(tv_nexus->tvn_se_sess)) {
1540                 kfree(tv_nexus);
1541                 ret = -ENOMEM;
1542                 goto out_unlock;
1543         }
1544
1545 out_unlock:
1546         mutex_unlock(&tpg->tv_tpg_mutex);
1547         return ret;
1548 }
1549
1550 static int scsiback_drop_nexus(struct scsiback_tpg *tpg)
1551 {
1552         struct se_session *se_sess;
1553         struct scsiback_nexus *tv_nexus;
1554
1555         mutex_lock(&tpg->tv_tpg_mutex);
1556         tv_nexus = tpg->tpg_nexus;
1557         if (!tv_nexus) {
1558                 mutex_unlock(&tpg->tv_tpg_mutex);
1559                 return -ENODEV;
1560         }
1561
1562         se_sess = tv_nexus->tvn_se_sess;
1563         if (!se_sess) {
1564                 mutex_unlock(&tpg->tv_tpg_mutex);
1565                 return -ENODEV;
1566         }
1567
1568         if (tpg->tv_tpg_port_count != 0) {
1569                 mutex_unlock(&tpg->tv_tpg_mutex);
1570                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG port count: %d\n",
1571                         tpg->tv_tpg_port_count);
1572                 return -EBUSY;
1573         }
1574
1575         if (tpg->tv_tpg_fe_count != 0) {
1576                 mutex_unlock(&tpg->tv_tpg_mutex);
1577                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG frontend count: %d\n",
1578                         tpg->tv_tpg_fe_count);
1579                 return -EBUSY;
1580         }
1581
1582         pr_debug("Removing I_T Nexus to emulated %s Initiator Port: %s\n",
1583                 scsiback_dump_proto_id(tpg->tport),
1584                 tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1585
1586         /*
1587          * Release the SCSI I_T Nexus to the emulated xen-pvscsi Target Port
1588          */
1589         target_remove_session(se_sess);
1590         tpg->tpg_nexus = NULL;
1591         mutex_unlock(&tpg->tv_tpg_mutex);
1592
1593         kfree(tv_nexus);
1594         return 0;
1595 }
1596
1597 static ssize_t scsiback_tpg_nexus_show(struct config_item *item, char *page)
1598 {
1599         struct se_portal_group *se_tpg = to_tpg(item);
1600         struct scsiback_tpg *tpg = container_of(se_tpg,
1601                                 struct scsiback_tpg, se_tpg);
1602         struct scsiback_nexus *tv_nexus;
1603         ssize_t ret;
1604
1605         mutex_lock(&tpg->tv_tpg_mutex);
1606         tv_nexus = tpg->tpg_nexus;
1607         if (!tv_nexus) {
1608                 mutex_unlock(&tpg->tv_tpg_mutex);
1609                 return -ENODEV;
1610         }
1611         ret = snprintf(page, PAGE_SIZE, "%s\n",
1612                         tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1613         mutex_unlock(&tpg->tv_tpg_mutex);
1614
1615         return ret;
1616 }
1617
1618 static ssize_t scsiback_tpg_nexus_store(struct config_item *item,
1619                 const char *page, size_t count)
1620 {
1621         struct se_portal_group *se_tpg = to_tpg(item);
1622         struct scsiback_tpg *tpg = container_of(se_tpg,
1623                                 struct scsiback_tpg, se_tpg);
1624         struct scsiback_tport *tport_wwn = tpg->tport;
1625         unsigned char i_port[VSCSI_NAMELEN], *ptr, *port_ptr;
1626         int ret;
1627         /*
1628          * Shutdown the active I_T nexus if 'NULL' is passed.
1629          */
1630         if (!strncmp(page, "NULL", 4)) {
1631                 ret = scsiback_drop_nexus(tpg);
1632                 return (!ret) ? count : ret;
1633         }
1634         /*
1635          * Otherwise make sure the passed virtual Initiator port WWN matches
1636          * the fabric protocol_id set in scsiback_make_tport(), and call
1637          * scsiback_make_nexus().
1638          */
1639         if (strlen(page) >= VSCSI_NAMELEN) {
1640                 pr_err("Emulated NAA Sas Address: %s, exceeds max: %d\n",
1641                         page, VSCSI_NAMELEN);
1642                 return -EINVAL;
1643         }
1644         snprintf(&i_port[0], VSCSI_NAMELEN, "%s", page);
1645
1646         ptr = strstr(i_port, "naa.");
1647         if (ptr) {
1648                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
1649                         pr_err("Passed SAS Initiator Port %s does not match target port protoid: %s\n",
1650                                 i_port, scsiback_dump_proto_id(tport_wwn));
1651                         return -EINVAL;
1652                 }
1653                 port_ptr = &i_port[0];
1654                 goto check_newline;
1655         }
1656         ptr = strstr(i_port, "fc.");
1657         if (ptr) {
1658                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
1659                         pr_err("Passed FCP Initiator Port %s does not match target port protoid: %s\n",
1660                                 i_port, scsiback_dump_proto_id(tport_wwn));
1661                         return -EINVAL;
1662                 }
1663                 port_ptr = &i_port[3]; /* Skip over "fc." */
1664                 goto check_newline;
1665         }
1666         ptr = strstr(i_port, "iqn.");
1667         if (ptr) {
1668                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
1669                         pr_err("Passed iSCSI Initiator Port %s does not match target port protoid: %s\n",
1670                                 i_port, scsiback_dump_proto_id(tport_wwn));
1671                         return -EINVAL;
1672                 }
1673                 port_ptr = &i_port[0];
1674                 goto check_newline;
1675         }
1676         pr_err("Unable to locate prefix for emulated Initiator Port: %s\n",
1677                 i_port);
1678         return -EINVAL;
1679         /*
1680          * Clear any trailing newline for the NAA WWN
1681          */
1682 check_newline:
1683         if (i_port[strlen(i_port) - 1] == '\n')
1684                 i_port[strlen(i_port) - 1] = '\0';
1685
1686         ret = scsiback_make_nexus(tpg, port_ptr);
1687         if (ret < 0)
1688                 return ret;
1689
1690         return count;
1691 }
1692
1693 CONFIGFS_ATTR(scsiback_tpg_, nexus);
1694
1695 static struct configfs_attribute *scsiback_tpg_attrs[] = {
1696         &scsiback_tpg_attr_nexus,
1697         NULL,
1698 };
1699
1700 static ssize_t
1701 scsiback_wwn_version_show(struct config_item *item, char *page)
1702 {
1703         return sprintf(page, "xen-pvscsi fabric module %s on %s/%s on "
1704                 UTS_RELEASE"\n",
1705                 VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1706 }
1707
1708 CONFIGFS_ATTR_RO(scsiback_wwn_, version);
1709
1710 static struct configfs_attribute *scsiback_wwn_attrs[] = {
1711         &scsiback_wwn_attr_version,
1712         NULL,
1713 };
1714
1715 static int scsiback_port_link(struct se_portal_group *se_tpg,
1716                                struct se_lun *lun)
1717 {
1718         struct scsiback_tpg *tpg = container_of(se_tpg,
1719                                 struct scsiback_tpg, se_tpg);
1720
1721         mutex_lock(&tpg->tv_tpg_mutex);
1722         tpg->tv_tpg_port_count++;
1723         mutex_unlock(&tpg->tv_tpg_mutex);
1724
1725         return 0;
1726 }
1727
1728 static void scsiback_port_unlink(struct se_portal_group *se_tpg,
1729                                   struct se_lun *lun)
1730 {
1731         struct scsiback_tpg *tpg = container_of(se_tpg,
1732                                 struct scsiback_tpg, se_tpg);
1733
1734         mutex_lock(&tpg->tv_tpg_mutex);
1735         tpg->tv_tpg_port_count--;
1736         mutex_unlock(&tpg->tv_tpg_mutex);
1737 }
1738
1739 static struct se_portal_group *
1740 scsiback_make_tpg(struct se_wwn *wwn, const char *name)
1741 {
1742         struct scsiback_tport *tport = container_of(wwn,
1743                         struct scsiback_tport, tport_wwn);
1744
1745         struct scsiback_tpg *tpg;
1746         u16 tpgt;
1747         int ret;
1748
1749         if (strstr(name, "tpgt_") != name)
1750                 return ERR_PTR(-EINVAL);
1751         ret = kstrtou16(name + 5, 10, &tpgt);
1752         if (ret)
1753                 return ERR_PTR(ret);
1754
1755         tpg = kzalloc(sizeof(struct scsiback_tpg), GFP_KERNEL);
1756         if (!tpg)
1757                 return ERR_PTR(-ENOMEM);
1758
1759         mutex_init(&tpg->tv_tpg_mutex);
1760         INIT_LIST_HEAD(&tpg->tv_tpg_list);
1761         INIT_LIST_HEAD(&tpg->info_list);
1762         tpg->tport = tport;
1763         tpg->tport_tpgt = tpgt;
1764
1765         ret = core_tpg_register(wwn, &tpg->se_tpg, tport->tport_proto_id);
1766         if (ret < 0) {
1767                 kfree(tpg);
1768                 return NULL;
1769         }
1770         mutex_lock(&scsiback_mutex);
1771         list_add_tail(&tpg->tv_tpg_list, &scsiback_list);
1772         mutex_unlock(&scsiback_mutex);
1773
1774         return &tpg->se_tpg;
1775 }
1776
1777 static void scsiback_drop_tpg(struct se_portal_group *se_tpg)
1778 {
1779         struct scsiback_tpg *tpg = container_of(se_tpg,
1780                                 struct scsiback_tpg, se_tpg);
1781
1782         mutex_lock(&scsiback_mutex);
1783         list_del(&tpg->tv_tpg_list);
1784         mutex_unlock(&scsiback_mutex);
1785         /*
1786          * Release the virtual I_T Nexus for this xen-pvscsi TPG
1787          */
1788         scsiback_drop_nexus(tpg);
1789         /*
1790          * Deregister the se_tpg from TCM.
1791          */
1792         core_tpg_deregister(se_tpg);
1793         kfree(tpg);
1794 }
1795
1796 static int scsiback_check_true(struct se_portal_group *se_tpg)
1797 {
1798         return 1;
1799 }
1800
1801 static int scsiback_check_false(struct se_portal_group *se_tpg)
1802 {
1803         return 0;
1804 }
1805
1806 static const struct target_core_fabric_ops scsiback_ops = {
1807         .module                         = THIS_MODULE,
1808         .fabric_name                    = "xen-pvscsi",
1809         .tpg_get_wwn                    = scsiback_get_fabric_wwn,
1810         .tpg_get_tag                    = scsiback_get_tag,
1811         .tpg_check_demo_mode            = scsiback_check_true,
1812         .tpg_check_demo_mode_cache      = scsiback_check_true,
1813         .tpg_check_demo_mode_write_protect = scsiback_check_false,
1814         .tpg_check_prod_mode_write_protect = scsiback_check_false,
1815         .tpg_get_inst_index             = scsiback_tpg_get_inst_index,
1816         .check_stop_free                = scsiback_check_stop_free,
1817         .release_cmd                    = scsiback_release_cmd,
1818         .sess_get_index                 = scsiback_sess_get_index,
1819         .sess_get_initiator_sid         = NULL,
1820         .write_pending                  = scsiback_write_pending,
1821         .write_pending_status           = scsiback_write_pending_status,
1822         .set_default_node_attributes    = scsiback_set_default_node_attrs,
1823         .get_cmd_state                  = scsiback_get_cmd_state,
1824         .queue_data_in                  = scsiback_queue_data_in,
1825         .queue_status                   = scsiback_queue_status,
1826         .queue_tm_rsp                   = scsiback_queue_tm_rsp,
1827         .aborted_task                   = scsiback_aborted_task,
1828         /*
1829          * Setup callers for generic logic in target_core_fabric_configfs.c
1830          */
1831         .fabric_make_wwn                = scsiback_make_tport,
1832         .fabric_drop_wwn                = scsiback_drop_tport,
1833         .fabric_make_tpg                = scsiback_make_tpg,
1834         .fabric_drop_tpg                = scsiback_drop_tpg,
1835         .fabric_post_link               = scsiback_port_link,
1836         .fabric_pre_unlink              = scsiback_port_unlink,
1837
1838         .tfc_wwn_attrs                  = scsiback_wwn_attrs,
1839         .tfc_tpg_base_attrs             = scsiback_tpg_attrs,
1840         .tfc_tpg_param_attrs            = scsiback_param_attrs,
1841 };
1842
1843 static const struct xenbus_device_id scsiback_ids[] = {
1844         { "vscsi" },
1845         { "" }
1846 };
1847
1848 static struct xenbus_driver scsiback_driver = {
1849         .ids                    = scsiback_ids,
1850         .probe                  = scsiback_probe,
1851         .remove                 = scsiback_remove,
1852         .otherend_changed       = scsiback_frontend_changed
1853 };
1854
1855 static int __init scsiback_init(void)
1856 {
1857         int ret;
1858
1859         if (!xen_domain())
1860                 return -ENODEV;
1861
1862         pr_debug("xen-pvscsi: fabric module %s on %s/%s on "UTS_RELEASE"\n",
1863                  VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1864
1865         ret = xenbus_register_backend(&scsiback_driver);
1866         if (ret)
1867                 goto out;
1868
1869         ret = target_register_template(&scsiback_ops);
1870         if (ret)
1871                 goto out_unregister_xenbus;
1872
1873         return 0;
1874
1875 out_unregister_xenbus:
1876         xenbus_unregister_driver(&scsiback_driver);
1877 out:
1878         pr_err("%s: error %d\n", __func__, ret);
1879         return ret;
1880 }
1881
1882 static void __exit scsiback_exit(void)
1883 {
1884         struct page *page;
1885
1886         while (free_pages_num) {
1887                 if (get_free_page(&page))
1888                         BUG();
1889                 gnttab_free_pages(1, &page);
1890         }
1891         target_unregister_template(&scsiback_ops);
1892         xenbus_unregister_driver(&scsiback_driver);
1893 }
1894
1895 module_init(scsiback_init);
1896 module_exit(scsiback_exit);
1897
1898 MODULE_DESCRIPTION("Xen SCSI backend driver");
1899 MODULE_LICENSE("Dual BSD/GPL");
1900 MODULE_ALIAS("xen-backend:vscsi");
1901 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");