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