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         BUG_ON(err);
 426         for (i = 0; i < cnt; i++) {
 427                 if (unlikely(map[i].status != GNTST_okay)) {
 428                         pr_err("invalid buffer -- could not remap it\n");
 429                         map[i].handle = SCSIBACK_INVALID_HANDLE;
 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;
 862         evtchn_port_t evtchn;
 863         int err;
 864
 865         err = xenbus_gather(XBT_NIL, dev->otherend,
 866                         "ring-ref", "%u", &ring_ref,
 867                         "event-channel", "%u", &evtchn, NULL);
 868         if (err) {
 869                 xenbus_dev_fatal(dev, err, "reading %s ring", dev->otherend);
 870                 return err;
 871         }
 872
 873         return scsiback_init_sring(info, ring_ref, evtchn);
 874 }
 875
 876 /*
 877   Check for a translation entry being present
 878 */
 879 static struct v2p_entry *scsiback_chk_translation_entry(
 880         struct vscsibk_info *info, struct ids_tuple *v)
 881 {
 882         struct list_head *head = &(info->v2p_entry_lists);
 883         struct v2p_entry *entry;
 884
 885         list_for_each_entry(entry, head, l)
 886                 if ((entry->v.chn == v->chn) &&
 887                     (entry->v.tgt == v->tgt) &&
 888                     (entry->v.lun == v->lun))
 889                         return entry;
 890
 891         return NULL;
 892 }
 893
 894 /*
 895   Add a new translation entry
 896 */
 897 static int scsiback_add_translation_entry(struct vscsibk_info *info,
 898                                           char *phy, struct ids_tuple *v)
 899 {
 900         int err = 0;
 901         struct v2p_entry *new;
 902         unsigned long flags;
 903         char *lunp;
 904         unsigned long long unpacked_lun;
 905         struct se_lun *se_lun;
 906         struct scsiback_tpg *tpg_entry, *tpg = NULL;
 907         char *error = "doesn't exist";
 908
 909         lunp = strrchr(phy, ':');
 910         if (!lunp) {
 911                 pr_err("illegal format of physical device %s\n", phy);
 912                 return -EINVAL;
 913         }
 914         *lunp = 0;
 915         lunp++;
 916         err = kstrtoull(lunp, 10, &unpacked_lun);
 917         if (err < 0) {
 918                 pr_err("lun number not valid: %s\n", lunp);
 919                 return err;
 920         }
 921
 922         mutex_lock(&scsiback_mutex);
 923         list_for_each_entry(tpg_entry, &scsiback_list, tv_tpg_list) {
 924                 if (!strcmp(phy, tpg_entry->tport->tport_name) ||
 925                     !strcmp(phy, tpg_entry->param_alias)) {
 926                         mutex_lock(&tpg_entry->se_tpg.tpg_lun_mutex);
 927                         hlist_for_each_entry(se_lun, &tpg_entry->se_tpg.tpg_lun_hlist, link) {
 928                                 if (se_lun->unpacked_lun == unpacked_lun) {
 929                                         if (!tpg_entry->tpg_nexus)
 930                                                 error = "nexus undefined";
 931                                         else
 932                                                 tpg = tpg_entry;
 933                                         break;
 934                                 }
 935                         }
 936                         mutex_unlock(&tpg_entry->se_tpg.tpg_lun_mutex);
 937                         break;
 938                 }
 939         }
 940         if (tpg) {
 941                 mutex_lock(&tpg->tv_tpg_mutex);
 942                 tpg->tv_tpg_fe_count++;
 943                 mutex_unlock(&tpg->tv_tpg_mutex);
 944         }
 945         mutex_unlock(&scsiback_mutex);
 946
 947         if (!tpg) {
 948                 pr_err("%s:%llu %s\n", phy, unpacked_lun, error);
 949                 return -ENODEV;
 950         }
 951
 952         new = kmalloc(sizeof(struct v2p_entry), GFP_KERNEL);
 953         if (new == NULL) {
 954                 err = -ENOMEM;
 955                 goto out_free;
 956         }
 957
 958         spin_lock_irqsave(&info->v2p_lock, flags);
 959
 960         /* Check double assignment to identical virtual ID */
 961         if (scsiback_chk_translation_entry(info, v)) {
 962                 pr_warn("Virtual ID is already used. Assignment was not performed.\n");
 963                 err = -EEXIST;
 964                 goto out;
 965         }
 966
 967         /* Create a new translation entry and add to the list */
 968         kref_init(&new->kref);
 969         new->v = *v;
 970         new->tpg = tpg;
 971         new->lun = unpacked_lun;
 972         list_add_tail(&new->l, &info->v2p_entry_lists);
 973
 974 out:
 975         spin_unlock_irqrestore(&info->v2p_lock, flags);
 976
 977 out_free:
 978         if (err) {
 979                 mutex_lock(&tpg->tv_tpg_mutex);
 980                 tpg->tv_tpg_fe_count--;
 981                 mutex_unlock(&tpg->tv_tpg_mutex);
 982                 kfree(new);
 983         }
 984
 985         return err;
 986 }
 987
 988 static void __scsiback_del_translation_entry(struct v2p_entry *entry)
 989 {
 990         list_del(&entry->l);
 991         kref_put(&entry->kref, scsiback_free_translation_entry);
 992 }
 993
 994 /*
 995   Delete the translation entry specified
 996 */
 997 static int scsiback_del_translation_entry(struct vscsibk_info *info,
 998                                           struct ids_tuple *v)
 999 {
1000         struct v2p_entry *entry;
1001         unsigned long flags;
1002         int ret = 0;
1003
1004         spin_lock_irqsave(&info->v2p_lock, flags);
1005         /* Find out the translation entry specified */
1006         entry = scsiback_chk_translation_entry(info, v);
1007         if (entry)
1008                 __scsiback_del_translation_entry(entry);
1009         else
1010                 ret = -ENOENT;
1011
1012         spin_unlock_irqrestore(&info->v2p_lock, flags);
1013         return ret;
1014 }
1015
1016 static void scsiback_do_add_lun(struct vscsibk_info *info, const char *state,
1017                                 char *phy, struct ids_tuple *vir, int try)
1018 {
1019         struct v2p_entry *entry;
1020         unsigned long flags;
1021         int err;
1022
1023         if (try) {
1024                 spin_lock_irqsave(&info->v2p_lock, flags);
1025                 entry = scsiback_chk_translation_entry(info, vir);
1026                 spin_unlock_irqrestore(&info->v2p_lock, flags);
1027                 if (entry)
1028                         return;
1029         }
1030         if (!scsiback_add_translation_entry(info, phy, vir)) {
1031                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
1032                                   "%d", XenbusStateInitialised)) {
1033                         pr_err("xenbus_printf error %s\n", state);
1034                         scsiback_del_translation_entry(info, vir);
1035                 }
1036         } else if (!try) {
1037                 err = xenbus_printf(XBT_NIL, info->dev->nodename, state,
1038                               "%d", XenbusStateClosed);
1039                 if (err)
1040                         xenbus_dev_error(info->dev, err,
1041                                 "%s: writing %s", __func__, state);
1042         }
1043 }
1044
1045 static void scsiback_do_del_lun(struct vscsibk_info *info, const char *state,
1046                                 struct ids_tuple *vir)
1047 {
1048         if (!scsiback_del_translation_entry(info, vir)) {
1049                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
1050                                   "%d", XenbusStateClosed))
1051                         pr_err("xenbus_printf error %s\n", state);
1052         }
1053 }
1054
1055 #define VSCSIBACK_OP_ADD_OR_DEL_LUN     1
1056 #define VSCSIBACK_OP_UPDATEDEV_STATE    2
1057
1058 static void scsiback_do_1lun_hotplug(struct vscsibk_info *info, int op,
1059                                      char *ent)
1060 {
1061         int err;
1062         struct ids_tuple vir;
1063         char *val;
1064         int device_state;
1065         char phy[VSCSI_NAMELEN];
1066         char str[64];
1067         char state[64];
1068         struct xenbus_device *dev = info->dev;
1069
1070         /* read status */
1071         snprintf(state, sizeof(state), "vscsi-devs/%s/state", ent);
1072         err = xenbus_scanf(XBT_NIL, dev->nodename, state, "%u", &device_state);
1073         if (XENBUS_EXIST_ERR(err))
1074                 return;
1075
1076         /* physical SCSI device */
1077         snprintf(str, sizeof(str), "vscsi-devs/%s/p-dev", ent);
1078         val = xenbus_read(XBT_NIL, dev->nodename, str, NULL);
1079         if (IS_ERR(val)) {
1080                 err = xenbus_printf(XBT_NIL, dev->nodename, state,
1081                               "%d", XenbusStateClosed);
1082                 if (err)
1083                         xenbus_dev_error(info->dev, err,
1084                                 "%s: writing %s", __func__, state);
1085                 return;
1086         }
1087         strlcpy(phy, val, VSCSI_NAMELEN);
1088         kfree(val);
1089
1090         /* virtual SCSI device */
1091         snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", ent);
1092         err = xenbus_scanf(XBT_NIL, dev->nodename, str, "%u:%u:%u:%u",
1093                            &vir.hst, &vir.chn, &vir.tgt, &vir.lun);
1094         if (XENBUS_EXIST_ERR(err)) {
1095                 err = xenbus_printf(XBT_NIL, dev->nodename, state,
1096                               "%d", XenbusStateClosed);
1097                 if (err)
1098                         xenbus_dev_error(info->dev, err,
1099                                 "%s: writing %s", __func__, state);
1100                 return;
1101         }
1102
1103         switch (op) {
1104         case VSCSIBACK_OP_ADD_OR_DEL_LUN:
1105                 switch (device_state) {
1106                 case XenbusStateInitialising:
1107                         scsiback_do_add_lun(info, state, phy, &vir, 0);
1108                         break;
1109                 case XenbusStateConnected:
1110                         scsiback_do_add_lun(info, state, phy, &vir, 1);
1111                         break;
1112                 case XenbusStateClosing:
1113                         scsiback_do_del_lun(info, state, &vir);
1114                         break;
1115                 default:
1116                         break;
1117                 }
1118                 break;
1119
1120         case VSCSIBACK_OP_UPDATEDEV_STATE:
1121                 if (device_state == XenbusStateInitialised) {
1122                         /* modify vscsi-devs/dev-x/state */
1123                         if (xenbus_printf(XBT_NIL, dev->nodename, state,
1124                                           "%d", XenbusStateConnected)) {
1125                                 pr_err("xenbus_printf error %s\n", str);
1126                                 scsiback_del_translation_entry(info, &vir);
1127                                 xenbus_printf(XBT_NIL, dev->nodename, state,
1128                                               "%d", XenbusStateClosed);
1129                         }
1130                 }
1131                 break;
1132         /* When it is necessary, processing is added here. */
1133         default:
1134                 break;
1135         }
1136 }
1137
1138 static void scsiback_do_lun_hotplug(struct vscsibk_info *info, int op)
1139 {
1140         int i;
1141         char **dir;
1142         unsigned int ndir = 0;
1143
1144         dir = xenbus_directory(XBT_NIL, info->dev->nodename, "vscsi-devs",
1145                                &ndir);
1146         if (IS_ERR(dir))
1147                 return;
1148
1149         for (i = 0; i < ndir; i++)
1150                 scsiback_do_1lun_hotplug(info, op, dir[i]);
1151
1152         kfree(dir);
1153 }
1154
1155 static void scsiback_frontend_changed(struct xenbus_device *dev,
1156                                         enum xenbus_state frontend_state)
1157 {
1158         struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
1159
1160         switch (frontend_state) {
1161         case XenbusStateInitialising:
1162                 break;
1163
1164         case XenbusStateInitialised:
1165                 if (scsiback_map(info))
1166                         break;
1167
1168                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
1169                 xenbus_switch_state(dev, XenbusStateConnected);
1170                 break;
1171
1172         case XenbusStateConnected:
1173                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_UPDATEDEV_STATE);
1174
1175                 if (dev->state == XenbusStateConnected)
1176                         break;
1177
1178                 xenbus_switch_state(dev, XenbusStateConnected);
1179                 break;
1180
1181         case XenbusStateClosing:
1182                 if (info->irq)
1183                         scsiback_disconnect(info);
1184
1185                 xenbus_switch_state(dev, XenbusStateClosing);
1186                 break;
1187
1188         case XenbusStateClosed:
1189                 xenbus_switch_state(dev, XenbusStateClosed);
1190                 if (xenbus_dev_is_online(dev))
1191                         break;
1192                 fallthrough;    /* if not online */
1193         case XenbusStateUnknown:
1194                 device_unregister(&dev->dev);
1195                 break;
1196
1197         case XenbusStateReconfiguring:
1198                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
1199                 xenbus_switch_state(dev, XenbusStateReconfigured);
1200
1201                 break;
1202
1203         default:
1204                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
1205                                         frontend_state);
1206                 break;
1207         }
1208 }
1209
1210 /*
1211   Release the translation entry specfied
1212 */
1213 static void scsiback_release_translation_entry(struct vscsibk_info *info)
1214 {
1215         struct v2p_entry *entry, *tmp;
1216         struct list_head *head = &(info->v2p_entry_lists);
1217         unsigned long flags;
1218
1219         spin_lock_irqsave(&info->v2p_lock, flags);
1220
1221         list_for_each_entry_safe(entry, tmp, head, l)
1222                 __scsiback_del_translation_entry(entry);
1223
1224         spin_unlock_irqrestore(&info->v2p_lock, flags);
1225 }
1226
1227 static int scsiback_remove(struct xenbus_device *dev)
1228 {
1229         struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
1230
1231         if (info->irq)
1232                 scsiback_disconnect(info);
1233
1234         scsiback_release_translation_entry(info);
1235
1236         dev_set_drvdata(&dev->dev, NULL);
1237
1238         return 0;
1239 }
1240
1241 static int scsiback_probe(struct xenbus_device *dev,
1242                            const struct xenbus_device_id *id)
1243 {
1244         int err;
1245
1246         struct vscsibk_info *info = kzalloc(sizeof(struct vscsibk_info),
1247                                             GFP_KERNEL);
1248
1249         pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
1250
1251         if (!info) {
1252                 xenbus_dev_fatal(dev, -ENOMEM, "allocating backend structure");
1253                 return -ENOMEM;
1254         }
1255         info->dev = dev;
1256         dev_set_drvdata(&dev->dev, info);
1257
1258         info->domid = dev->otherend_id;
1259         spin_lock_init(&info->ring_lock);
1260         atomic_set(&info->nr_unreplied_reqs, 0);
1261         init_waitqueue_head(&info->waiting_to_free);
1262         info->dev = dev;
1263         info->irq = 0;
1264         INIT_LIST_HEAD(&info->v2p_entry_lists);
1265         spin_lock_init(&info->v2p_lock);
1266
1267         err = xenbus_printf(XBT_NIL, dev->nodename, "feature-sg-grant", "%u",
1268                             SG_ALL);
1269         if (err)
1270                 xenbus_dev_error(dev, err, "writing feature-sg-grant");
1271
1272         err = xenbus_switch_state(dev, XenbusStateInitWait);
1273         if (err)
1274                 goto fail;
1275
1276         return 0;
1277
1278 fail:
1279         pr_warn("%s failed\n", __func__);
1280         scsiback_remove(dev);
1281
1282         return err;
1283 }
1284
1285 static char *scsiback_dump_proto_id(struct scsiback_tport *tport)
1286 {
1287         switch (tport->tport_proto_id) {
1288         case SCSI_PROTOCOL_SAS:
1289                 return "SAS";
1290         case SCSI_PROTOCOL_FCP:
1291                 return "FCP";
1292         case SCSI_PROTOCOL_ISCSI:
1293                 return "iSCSI";
1294         default:
1295                 break;
1296         }
1297
1298         return "Unknown";
1299 }
1300
1301 static char *scsiback_get_fabric_wwn(struct se_portal_group *se_tpg)
1302 {
1303         struct scsiback_tpg *tpg = container_of(se_tpg,
1304                                 struct scsiback_tpg, se_tpg);
1305         struct scsiback_tport *tport = tpg->tport;
1306
1307         return &tport->tport_name[0];
1308 }
1309
1310 static u16 scsiback_get_tag(struct se_portal_group *se_tpg)
1311 {
1312         struct scsiback_tpg *tpg = container_of(se_tpg,
1313                                 struct scsiback_tpg, se_tpg);
1314         return tpg->tport_tpgt;
1315 }
1316
1317 static struct se_wwn *
1318 scsiback_make_tport(struct target_fabric_configfs *tf,
1319                      struct config_group *group,
1320                      const char *name)
1321 {
1322         struct scsiback_tport *tport;
1323         char *ptr;
1324         u64 wwpn = 0;
1325         int off = 0;
1326
1327         tport = kzalloc(sizeof(struct scsiback_tport), GFP_KERNEL);
1328         if (!tport)
1329                 return ERR_PTR(-ENOMEM);
1330
1331         tport->tport_wwpn = wwpn;
1332         /*
1333          * Determine the emulated Protocol Identifier and Target Port Name
1334          * based on the incoming configfs directory name.
1335          */
1336         ptr = strstr(name, "naa.");
1337         if (ptr) {
1338                 tport->tport_proto_id = SCSI_PROTOCOL_SAS;
1339                 goto check_len;
1340         }
1341         ptr = strstr(name, "fc.");
1342         if (ptr) {
1343                 tport->tport_proto_id = SCSI_PROTOCOL_FCP;
1344                 off = 3; /* Skip over "fc." */
1345                 goto check_len;
1346         }
1347         ptr = strstr(name, "iqn.");
1348         if (ptr) {
1349                 tport->tport_proto_id = SCSI_PROTOCOL_ISCSI;
1350                 goto check_len;
1351         }
1352
1353         pr_err("Unable to locate prefix for emulated Target Port: %s\n", name);
1354         kfree(tport);
1355         return ERR_PTR(-EINVAL);
1356
1357 check_len:
1358         if (strlen(name) >= VSCSI_NAMELEN) {
1359                 pr_err("Emulated %s Address: %s, exceeds max: %d\n", name,
1360                         scsiback_dump_proto_id(tport), VSCSI_NAMELEN);
1361                 kfree(tport);
1362                 return ERR_PTR(-EINVAL);
1363         }
1364         snprintf(&tport->tport_name[0], VSCSI_NAMELEN, "%s", &name[off]);
1365
1366         pr_debug("Allocated emulated Target %s Address: %s\n",
1367                  scsiback_dump_proto_id(tport), name);
1368
1369         return &tport->tport_wwn;
1370 }
1371
1372 static void scsiback_drop_tport(struct se_wwn *wwn)
1373 {
1374         struct scsiback_tport *tport = container_of(wwn,
1375                                 struct scsiback_tport, tport_wwn);
1376
1377         pr_debug("Deallocating emulated Target %s Address: %s\n",
1378                  scsiback_dump_proto_id(tport), tport->tport_name);
1379
1380         kfree(tport);
1381 }
1382
1383 static u32 scsiback_tpg_get_inst_index(struct se_portal_group *se_tpg)
1384 {
1385         return 1;
1386 }
1387
1388 static int scsiback_check_stop_free(struct se_cmd *se_cmd)
1389 {
1390         return transport_generic_free_cmd(se_cmd, 0);
1391 }
1392
1393 static void scsiback_release_cmd(struct se_cmd *se_cmd)
1394 {
1395         target_free_tag(se_cmd->se_sess, se_cmd);
1396 }
1397
1398 static u32 scsiback_sess_get_index(struct se_session *se_sess)
1399 {
1400         return 0;
1401 }
1402
1403 static int scsiback_write_pending(struct se_cmd *se_cmd)
1404 {
1405         /* Go ahead and process the write immediately */
1406         target_execute_cmd(se_cmd);
1407
1408         return 0;
1409 }
1410
1411 static void scsiback_set_default_node_attrs(struct se_node_acl *nacl)
1412 {
1413 }
1414
1415 static int scsiback_get_cmd_state(struct se_cmd *se_cmd)
1416 {
1417         return 0;
1418 }
1419
1420 static int scsiback_queue_data_in(struct se_cmd *se_cmd)
1421 {
1422         struct vscsibk_pend *pending_req = container_of(se_cmd,
1423                                 struct vscsibk_pend, se_cmd);
1424
1425         pending_req->result = SAM_STAT_GOOD;
1426         scsiback_cmd_done(pending_req);
1427         return 0;
1428 }
1429
1430 static int scsiback_queue_status(struct se_cmd *se_cmd)
1431 {
1432         struct vscsibk_pend *pending_req = container_of(se_cmd,
1433                                 struct vscsibk_pend, se_cmd);
1434
1435         if (se_cmd->sense_buffer &&
1436             ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
1437              (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE)))
1438                 pending_req->result = (DRIVER_SENSE << 24) |
1439                                       SAM_STAT_CHECK_CONDITION;
1440         else
1441                 pending_req->result = se_cmd->scsi_status;
1442
1443         scsiback_cmd_done(pending_req);
1444         return 0;
1445 }
1446
1447 static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd)
1448 {
1449         struct vscsibk_pend *pending_req = container_of(se_cmd,
1450                                 struct vscsibk_pend, se_cmd);
1451
1452         complete(&pending_req->tmr_done);
1453 }
1454
1455 static void scsiback_aborted_task(struct se_cmd *se_cmd)
1456 {
1457 }
1458
1459 static ssize_t scsiback_tpg_param_alias_show(struct config_item *item,
1460                                              char *page)
1461 {
1462         struct se_portal_group *se_tpg = param_to_tpg(item);
1463         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1464                                                 se_tpg);
1465         ssize_t rb;
1466
1467         mutex_lock(&tpg->tv_tpg_mutex);
1468         rb = snprintf(page, PAGE_SIZE, "%s\n", tpg->param_alias);
1469         mutex_unlock(&tpg->tv_tpg_mutex);
1470
1471         return rb;
1472 }
1473
1474 static ssize_t scsiback_tpg_param_alias_store(struct config_item *item,
1475                                               const char *page, size_t count)
1476 {
1477         struct se_portal_group *se_tpg = param_to_tpg(item);
1478         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1479                                                 se_tpg);
1480         int len;
1481
1482         if (strlen(page) >= VSCSI_NAMELEN) {
1483                 pr_err("param alias: %s, exceeds max: %d\n", page,
1484                         VSCSI_NAMELEN);
1485                 return -EINVAL;
1486         }
1487
1488         mutex_lock(&tpg->tv_tpg_mutex);
1489         len = snprintf(tpg->param_alias, VSCSI_NAMELEN, "%s", page);
1490         if (tpg->param_alias[len - 1] == '\n')
1491                 tpg->param_alias[len - 1] = '\0';
1492         mutex_unlock(&tpg->tv_tpg_mutex);
1493
1494         return count;
1495 }
1496
1497 CONFIGFS_ATTR(scsiback_tpg_param_, alias);
1498
1499 static struct configfs_attribute *scsiback_param_attrs[] = {
1500         &scsiback_tpg_param_attr_alias,
1501         NULL,
1502 };
1503
1504 static int scsiback_alloc_sess_cb(struct se_portal_group *se_tpg,
1505                                   struct se_session *se_sess, void *p)
1506 {
1507         struct scsiback_tpg *tpg = container_of(se_tpg,
1508                                 struct scsiback_tpg, se_tpg);
1509
1510         tpg->tpg_nexus = p;
1511         return 0;
1512 }
1513
1514 static int scsiback_make_nexus(struct scsiback_tpg *tpg,
1515                                 const char *name)
1516 {
1517         struct scsiback_nexus *tv_nexus;
1518         int ret = 0;
1519
1520         mutex_lock(&tpg->tv_tpg_mutex);
1521         if (tpg->tpg_nexus) {
1522                 pr_debug("tpg->tpg_nexus already exists\n");
1523                 ret = -EEXIST;
1524                 goto out_unlock;
1525         }
1526
1527         tv_nexus = kzalloc(sizeof(struct scsiback_nexus), GFP_KERNEL);
1528         if (!tv_nexus) {
1529                 ret = -ENOMEM;
1530                 goto out_unlock;
1531         }
1532
1533         tv_nexus->tvn_se_sess = target_setup_session(&tpg->se_tpg,
1534                                                      VSCSI_DEFAULT_SESSION_TAGS,
1535                                                      sizeof(struct vscsibk_pend),
1536                                                      TARGET_PROT_NORMAL, name,
1537                                                      tv_nexus, scsiback_alloc_sess_cb);
1538         if (IS_ERR(tv_nexus->tvn_se_sess)) {
1539                 kfree(tv_nexus);
1540                 ret = -ENOMEM;
1541                 goto out_unlock;
1542         }
1543
1544 out_unlock:
1545         mutex_unlock(&tpg->tv_tpg_mutex);
1546         return ret;
1547 }
1548
1549 static int scsiback_drop_nexus(struct scsiback_tpg *tpg)
1550 {
1551         struct se_session *se_sess;
1552         struct scsiback_nexus *tv_nexus;
1553
1554         mutex_lock(&tpg->tv_tpg_mutex);
1555         tv_nexus = tpg->tpg_nexus;
1556         if (!tv_nexus) {
1557                 mutex_unlock(&tpg->tv_tpg_mutex);
1558                 return -ENODEV;
1559         }
1560
1561         se_sess = tv_nexus->tvn_se_sess;
1562         if (!se_sess) {
1563                 mutex_unlock(&tpg->tv_tpg_mutex);
1564                 return -ENODEV;
1565         }
1566
1567         if (tpg->tv_tpg_port_count != 0) {
1568                 mutex_unlock(&tpg->tv_tpg_mutex);
1569                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG port count: %d\n",
1570                         tpg->tv_tpg_port_count);
1571                 return -EBUSY;
1572         }
1573
1574         if (tpg->tv_tpg_fe_count != 0) {
1575                 mutex_unlock(&tpg->tv_tpg_mutex);
1576                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG frontend count: %d\n",
1577                         tpg->tv_tpg_fe_count);
1578                 return -EBUSY;
1579         }
1580
1581         pr_debug("Removing I_T Nexus to emulated %s Initiator Port: %s\n",
1582                 scsiback_dump_proto_id(tpg->tport),
1583                 tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1584
1585         /*
1586          * Release the SCSI I_T Nexus to the emulated xen-pvscsi Target Port
1587          */
1588         target_remove_session(se_sess);
1589         tpg->tpg_nexus = NULL;
1590         mutex_unlock(&tpg->tv_tpg_mutex);
1591
1592         kfree(tv_nexus);
1593         return 0;
1594 }
1595
1596 static ssize_t scsiback_tpg_nexus_show(struct config_item *item, char *page)
1597 {
1598         struct se_portal_group *se_tpg = to_tpg(item);
1599         struct scsiback_tpg *tpg = container_of(se_tpg,
1600                                 struct scsiback_tpg, se_tpg);
1601         struct scsiback_nexus *tv_nexus;
1602         ssize_t ret;
1603
1604         mutex_lock(&tpg->tv_tpg_mutex);
1605         tv_nexus = tpg->tpg_nexus;
1606         if (!tv_nexus) {
1607                 mutex_unlock(&tpg->tv_tpg_mutex);
1608                 return -ENODEV;
1609         }
1610         ret = snprintf(page, PAGE_SIZE, "%s\n",
1611                         tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1612         mutex_unlock(&tpg->tv_tpg_mutex);
1613
1614         return ret;
1615 }
1616
1617 static ssize_t scsiback_tpg_nexus_store(struct config_item *item,
1618                 const char *page, size_t count)
1619 {
1620         struct se_portal_group *se_tpg = to_tpg(item);
1621         struct scsiback_tpg *tpg = container_of(se_tpg,
1622                                 struct scsiback_tpg, se_tpg);
1623         struct scsiback_tport *tport_wwn = tpg->tport;
1624         unsigned char i_port[VSCSI_NAMELEN], *ptr, *port_ptr;
1625         int ret;
1626         /*
1627          * Shutdown the active I_T nexus if 'NULL' is passed.
1628          */
1629         if (!strncmp(page, "NULL", 4)) {
1630                 ret = scsiback_drop_nexus(tpg);
1631                 return (!ret) ? count : ret;
1632         }
1633         /*
1634          * Otherwise make sure the passed virtual Initiator port WWN matches
1635          * the fabric protocol_id set in scsiback_make_tport(), and call
1636          * scsiback_make_nexus().
1637          */
1638         if (strlen(page) >= VSCSI_NAMELEN) {
1639                 pr_err("Emulated NAA Sas Address: %s, exceeds max: %d\n",
1640                         page, VSCSI_NAMELEN);
1641                 return -EINVAL;
1642         }
1643         snprintf(&i_port[0], VSCSI_NAMELEN, "%s", page);
1644
1645         ptr = strstr(i_port, "naa.");
1646         if (ptr) {
1647                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
1648                         pr_err("Passed SAS Initiator Port %s does not match target port protoid: %s\n",
1649                                 i_port, scsiback_dump_proto_id(tport_wwn));
1650                         return -EINVAL;
1651                 }
1652                 port_ptr = &i_port[0];
1653                 goto check_newline;
1654         }
1655         ptr = strstr(i_port, "fc.");
1656         if (ptr) {
1657                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
1658                         pr_err("Passed FCP Initiator Port %s does not match target port protoid: %s\n",
1659                                 i_port, scsiback_dump_proto_id(tport_wwn));
1660                         return -EINVAL;
1661                 }
1662                 port_ptr = &i_port[3]; /* Skip over "fc." */
1663                 goto check_newline;
1664         }
1665         ptr = strstr(i_port, "iqn.");
1666         if (ptr) {
1667                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
1668                         pr_err("Passed iSCSI Initiator Port %s does not match target port protoid: %s\n",
1669                                 i_port, scsiback_dump_proto_id(tport_wwn));
1670                         return -EINVAL;
1671                 }
1672                 port_ptr = &i_port[0];
1673                 goto check_newline;
1674         }
1675         pr_err("Unable to locate prefix for emulated Initiator Port: %s\n",
1676                 i_port);
1677         return -EINVAL;
1678         /*
1679          * Clear any trailing newline for the NAA WWN
1680          */
1681 check_newline:
1682         if (i_port[strlen(i_port) - 1] == '\n')
1683                 i_port[strlen(i_port) - 1] = '\0';
1684
1685         ret = scsiback_make_nexus(tpg, port_ptr);
1686         if (ret < 0)
1687                 return ret;
1688
1689         return count;
1690 }
1691
1692 CONFIGFS_ATTR(scsiback_tpg_, nexus);
1693
1694 static struct configfs_attribute *scsiback_tpg_attrs[] = {
1695         &scsiback_tpg_attr_nexus,
1696         NULL,
1697 };
1698
1699 static ssize_t
1700 scsiback_wwn_version_show(struct config_item *item, char *page)
1701 {
1702         return sprintf(page, "xen-pvscsi fabric module %s on %s/%s on "
1703                 UTS_RELEASE"\n",
1704                 VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1705 }
1706
1707 CONFIGFS_ATTR_RO(scsiback_wwn_, version);
1708
1709 static struct configfs_attribute *scsiback_wwn_attrs[] = {
1710         &scsiback_wwn_attr_version,
1711         NULL,
1712 };
1713
1714 static int scsiback_port_link(struct se_portal_group *se_tpg,
1715                                struct se_lun *lun)
1716 {
1717         struct scsiback_tpg *tpg = container_of(se_tpg,
1718                                 struct scsiback_tpg, se_tpg);
1719
1720         mutex_lock(&tpg->tv_tpg_mutex);
1721         tpg->tv_tpg_port_count++;
1722         mutex_unlock(&tpg->tv_tpg_mutex);
1723
1724         return 0;
1725 }
1726
1727 static void scsiback_port_unlink(struct se_portal_group *se_tpg,
1728                                   struct se_lun *lun)
1729 {
1730         struct scsiback_tpg *tpg = container_of(se_tpg,
1731                                 struct scsiback_tpg, se_tpg);
1732
1733         mutex_lock(&tpg->tv_tpg_mutex);
1734         tpg->tv_tpg_port_count--;
1735         mutex_unlock(&tpg->tv_tpg_mutex);
1736 }
1737
1738 static struct se_portal_group *
1739 scsiback_make_tpg(struct se_wwn *wwn, const char *name)
1740 {
1741         struct scsiback_tport *tport = container_of(wwn,
1742                         struct scsiback_tport, tport_wwn);
1743
1744         struct scsiback_tpg *tpg;
1745         u16 tpgt;
1746         int ret;
1747
1748         if (strstr(name, "tpgt_") != name)
1749                 return ERR_PTR(-EINVAL);
1750         ret = kstrtou16(name + 5, 10, &tpgt);
1751         if (ret)
1752                 return ERR_PTR(ret);
1753
1754         tpg = kzalloc(sizeof(struct scsiback_tpg), GFP_KERNEL);
1755         if (!tpg)
1756                 return ERR_PTR(-ENOMEM);
1757
1758         mutex_init(&tpg->tv_tpg_mutex);
1759         INIT_LIST_HEAD(&tpg->tv_tpg_list);
1760         INIT_LIST_HEAD(&tpg->info_list);
1761         tpg->tport = tport;
1762         tpg->tport_tpgt = tpgt;
1763
1764         ret = core_tpg_register(wwn, &tpg->se_tpg, tport->tport_proto_id);
1765         if (ret < 0) {
1766                 kfree(tpg);
1767                 return NULL;
1768         }
1769         mutex_lock(&scsiback_mutex);
1770         list_add_tail(&tpg->tv_tpg_list, &scsiback_list);
1771         mutex_unlock(&scsiback_mutex);
1772
1773         return &tpg->se_tpg;
1774 }
1775
1776 static void scsiback_drop_tpg(struct se_portal_group *se_tpg)
1777 {
1778         struct scsiback_tpg *tpg = container_of(se_tpg,
1779                                 struct scsiback_tpg, se_tpg);
1780
1781         mutex_lock(&scsiback_mutex);
1782         list_del(&tpg->tv_tpg_list);
1783         mutex_unlock(&scsiback_mutex);
1784         /*
1785          * Release the virtual I_T Nexus for this xen-pvscsi TPG
1786          */
1787         scsiback_drop_nexus(tpg);
1788         /*
1789          * Deregister the se_tpg from TCM.
1790          */
1791         core_tpg_deregister(se_tpg);
1792         kfree(tpg);
1793 }
1794
1795 static int scsiback_check_true(struct se_portal_group *se_tpg)
1796 {
1797         return 1;
1798 }
1799
1800 static int scsiback_check_false(struct se_portal_group *se_tpg)
1801 {
1802         return 0;
1803 }
1804
1805 static const struct target_core_fabric_ops scsiback_ops = {
1806         .module                         = THIS_MODULE,
1807         .fabric_name                    = "xen-pvscsi",
1808         .tpg_get_wwn                    = scsiback_get_fabric_wwn,
1809         .tpg_get_tag                    = scsiback_get_tag,
1810         .tpg_check_demo_mode            = scsiback_check_true,
1811         .tpg_check_demo_mode_cache      = scsiback_check_true,
1812         .tpg_check_demo_mode_write_protect = scsiback_check_false,
1813         .tpg_check_prod_mode_write_protect = scsiback_check_false,
1814         .tpg_get_inst_index             = scsiback_tpg_get_inst_index,
1815         .check_stop_free                = scsiback_check_stop_free,
1816         .release_cmd                    = scsiback_release_cmd,
1817         .sess_get_index                 = scsiback_sess_get_index,
1818         .sess_get_initiator_sid         = NULL,
1819         .write_pending                  = scsiback_write_pending,
1820         .set_default_node_attributes    = scsiback_set_default_node_attrs,
1821         .get_cmd_state                  = scsiback_get_cmd_state,
1822         .queue_data_in                  = scsiback_queue_data_in,
1823         .queue_status                   = scsiback_queue_status,
1824         .queue_tm_rsp                   = scsiback_queue_tm_rsp,
1825         .aborted_task                   = scsiback_aborted_task,
1826         /*
1827          * Setup callers for generic logic in target_core_fabric_configfs.c
1828          */
1829         .fabric_make_wwn                = scsiback_make_tport,
1830         .fabric_drop_wwn                = scsiback_drop_tport,
1831         .fabric_make_tpg                = scsiback_make_tpg,
1832         .fabric_drop_tpg                = scsiback_drop_tpg,
1833         .fabric_post_link               = scsiback_port_link,
1834         .fabric_pre_unlink              = scsiback_port_unlink,
1835
1836         .tfc_wwn_attrs                  = scsiback_wwn_attrs,
1837         .tfc_tpg_base_attrs             = scsiback_tpg_attrs,
1838         .tfc_tpg_param_attrs            = scsiback_param_attrs,
1839 };
1840
1841 static const struct xenbus_device_id scsiback_ids[] = {
1842         { "vscsi" },
1843         { "" }
1844 };
1845
1846 static struct xenbus_driver scsiback_driver = {
1847         .ids                    = scsiback_ids,
1848         .probe                  = scsiback_probe,
1849         .remove                 = scsiback_remove,
1850         .otherend_changed       = scsiback_frontend_changed
1851 };
1852
1853 static int __init scsiback_init(void)
1854 {
1855         int ret;
1856
1857         if (!xen_domain())
1858                 return -ENODEV;
1859
1860         pr_debug("xen-pvscsi: fabric module %s on %s/%s on "UTS_RELEASE"\n",
1861                  VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1862
1863         ret = xenbus_register_backend(&scsiback_driver);
1864         if (ret)
1865                 goto out;
1866
1867         ret = target_register_template(&scsiback_ops);
1868         if (ret)
1869                 goto out_unregister_xenbus;
1870
1871         return 0;
1872
1873 out_unregister_xenbus:
1874         xenbus_unregister_driver(&scsiback_driver);
1875 out:
1876         pr_err("%s: error %d\n", __func__, ret);
1877         return ret;
1878 }
1879
1880 static void __exit scsiback_exit(void)
1881 {
1882         struct page *page;
1883
1884         while (free_pages_num) {
1885                 if (get_free_page(&page))
1886                         BUG();
1887                 gnttab_free_pages(1, &page);
1888         }
1889         target_unregister_template(&scsiback_ops);
1890         xenbus_unregister_driver(&scsiback_driver);
1891 }
1892
1893 module_init(scsiback_init);
1894 module_exit(scsiback_exit);
1895
1896 MODULE_DESCRIPTION("Xen SCSI backend driver");
1897 MODULE_LICENSE("Dual BSD/GPL");
1898 MODULE_ALIAS("xen-backend:vscsi");
1899 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");