1 /******************************************************************************* 2 * Filename: target_core_rd.c 3 * 4 * This file contains the Storage Engine <-> Ramdisk transport 5 * specific functions. 6 * 7 * (c) Copyright 2003-2013 Datera, Inc. 8 * 9 * Nicholas A. Bellinger <nab@kernel.org> 10 * 11 * This program is free software; you can redistribute it and/or modify 12 * it under the terms of the GNU General Public License as published by 13 * the Free Software Foundation; either version 2 of the License, or 14 * (at your option) any later version. 15 * 16 * This program is distributed in the hope that it will be useful, 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 * GNU General Public License for more details. 20 * 21 * You should have received a copy of the GNU General Public License 22 * along with this program; if not, write to the Free Software 23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 24 * 25 ******************************************************************************/ 26 27 #include <linux/string.h> 28 #include <linux/parser.h> 29 #include <linux/timer.h> 30 #include <linux/slab.h> 31 #include <linux/spinlock.h> 32 #include <scsi/scsi_proto.h> 33 34 #include <target/target_core_base.h> 35 #include <target/target_core_backend.h> 36 37 #include "target_core_rd.h" 38 39 static inline struct rd_dev *RD_DEV(struct se_device *dev) 40 { 41 return container_of(dev, struct rd_dev, dev); 42 } 43 44 static int rd_attach_hba(struct se_hba *hba, u32 host_id) 45 { 46 struct rd_host *rd_host; 47 48 rd_host = kzalloc(sizeof(struct rd_host), GFP_KERNEL); 49 if (!rd_host) { 50 pr_err("Unable to allocate memory for struct rd_host\n"); 51 return -ENOMEM; 52 } 53 54 rd_host->rd_host_id = host_id; 55 56 hba->hba_ptr = rd_host; 57 58 pr_debug("CORE_HBA[%d] - TCM Ramdisk HBA Driver %s on" 59 " Generic Target Core Stack %s\n", hba->hba_id, 60 RD_HBA_VERSION, TARGET_CORE_VERSION); 61 62 return 0; 63 } 64 65 static void rd_detach_hba(struct se_hba *hba) 66 { 67 struct rd_host *rd_host = hba->hba_ptr; 68 69 pr_debug("CORE_HBA[%d] - Detached Ramdisk HBA: %u from" 70 " Generic Target Core\n", hba->hba_id, rd_host->rd_host_id); 71 72 kfree(rd_host); 73 hba->hba_ptr = NULL; 74 } 75 76 static u32 rd_release_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *sg_table, 77 u32 sg_table_count) 78 { 79 struct page *pg; 80 struct scatterlist *sg; 81 u32 i, j, page_count = 0, sg_per_table; 82 83 for (i = 0; i < sg_table_count; i++) { 84 sg = sg_table[i].sg_table; 85 sg_per_table = sg_table[i].rd_sg_count; 86 87 for (j = 0; j < sg_per_table; j++) { 88 pg = sg_page(&sg[j]); 89 if (pg) { 90 __free_page(pg); 91 page_count++; 92 } 93 } 94 kfree(sg); 95 } 96 97 kfree(sg_table); 98 return page_count; 99 } 100 101 static void rd_release_device_space(struct rd_dev *rd_dev) 102 { 103 u32 page_count; 104 105 if (!rd_dev->sg_table_array || !rd_dev->sg_table_count) 106 return; 107 108 page_count = rd_release_sgl_table(rd_dev, rd_dev->sg_table_array, 109 rd_dev->sg_table_count); 110 111 pr_debug("CORE_RD[%u] - Released device space for Ramdisk" 112 " Device ID: %u, pages %u in %u tables total bytes %lu\n", 113 rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count, 114 rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE); 115 116 rd_dev->sg_table_array = NULL; 117 rd_dev->sg_table_count = 0; 118 } 119 120 121 /* rd_build_device_space(): 122 * 123 * 124 */ 125 static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *sg_table, 126 u32 total_sg_needed, unsigned char init_payload) 127 { 128 u32 i = 0, j, page_offset = 0, sg_per_table; 129 u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE / 130 sizeof(struct scatterlist)); 131 struct page *pg; 132 struct scatterlist *sg; 133 unsigned char *p; 134 135 while (total_sg_needed) { 136 unsigned int chain_entry = 0; 137 138 sg_per_table = (total_sg_needed > max_sg_per_table) ? 139 max_sg_per_table : total_sg_needed; 140 141 /* 142 * Reserve extra element for chain entry 143 */ 144 if (sg_per_table < total_sg_needed) 145 chain_entry = 1; 146 147 sg = kcalloc(sg_per_table + chain_entry, sizeof(*sg), 148 GFP_KERNEL); 149 if (!sg) { 150 pr_err("Unable to allocate scatterlist array" 151 " for struct rd_dev\n"); 152 return -ENOMEM; 153 } 154 155 sg_init_table(sg, sg_per_table + chain_entry); 156 157 if (i > 0) { 158 sg_chain(sg_table[i - 1].sg_table, 159 max_sg_per_table + 1, sg); 160 } 161 162 sg_table[i].sg_table = sg; 163 sg_table[i].rd_sg_count = sg_per_table; 164 sg_table[i].page_start_offset = page_offset; 165 sg_table[i++].page_end_offset = (page_offset + sg_per_table) 166 - 1; 167 168 for (j = 0; j < sg_per_table; j++) { 169 pg = alloc_pages(GFP_KERNEL, 0); 170 if (!pg) { 171 pr_err("Unable to allocate scatterlist" 172 " pages for struct rd_dev_sg_table\n"); 173 return -ENOMEM; 174 } 175 sg_assign_page(&sg[j], pg); 176 sg[j].length = PAGE_SIZE; 177 178 p = kmap(pg); 179 memset(p, init_payload, PAGE_SIZE); 180 kunmap(pg); 181 } 182 183 page_offset += sg_per_table; 184 total_sg_needed -= sg_per_table; 185 } 186 187 return 0; 188 } 189 190 static int rd_build_device_space(struct rd_dev *rd_dev) 191 { 192 struct rd_dev_sg_table *sg_table; 193 u32 sg_tables, total_sg_needed; 194 u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE / 195 sizeof(struct scatterlist)); 196 int rc; 197 198 if (rd_dev->rd_page_count <= 0) { 199 pr_err("Illegal page count: %u for Ramdisk device\n", 200 rd_dev->rd_page_count); 201 return -EINVAL; 202 } 203 204 /* Don't need backing pages for NULLIO */ 205 if (rd_dev->rd_flags & RDF_NULLIO) 206 return 0; 207 208 total_sg_needed = rd_dev->rd_page_count; 209 210 sg_tables = (total_sg_needed / max_sg_per_table) + 1; 211 212 sg_table = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL); 213 if (!sg_table) { 214 pr_err("Unable to allocate memory for Ramdisk" 215 " scatterlist tables\n"); 216 return -ENOMEM; 217 } 218 219 rd_dev->sg_table_array = sg_table; 220 rd_dev->sg_table_count = sg_tables; 221 222 rc = rd_allocate_sgl_table(rd_dev, sg_table, total_sg_needed, 0x00); 223 if (rc) 224 return rc; 225 226 pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u space of" 227 " %u pages in %u tables\n", rd_dev->rd_host->rd_host_id, 228 rd_dev->rd_dev_id, rd_dev->rd_page_count, 229 rd_dev->sg_table_count); 230 231 return 0; 232 } 233 234 static void rd_release_prot_space(struct rd_dev *rd_dev) 235 { 236 u32 page_count; 237 238 if (!rd_dev->sg_prot_array || !rd_dev->sg_prot_count) 239 return; 240 241 page_count = rd_release_sgl_table(rd_dev, rd_dev->sg_prot_array, 242 rd_dev->sg_prot_count); 243 244 pr_debug("CORE_RD[%u] - Released protection space for Ramdisk" 245 " Device ID: %u, pages %u in %u tables total bytes %lu\n", 246 rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count, 247 rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE); 248 249 rd_dev->sg_prot_array = NULL; 250 rd_dev->sg_prot_count = 0; 251 } 252 253 static int rd_build_prot_space(struct rd_dev *rd_dev, int prot_length, int block_size) 254 { 255 struct rd_dev_sg_table *sg_table; 256 u32 total_sg_needed, sg_tables; 257 u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE / 258 sizeof(struct scatterlist)); 259 int rc; 260 261 if (rd_dev->rd_flags & RDF_NULLIO) 262 return 0; 263 /* 264 * prot_length=8byte dif data 265 * tot sg needed = rd_page_count * (PGSZ/block_size) * 266 * (prot_length/block_size) + pad 267 * PGSZ canceled each other. 268 */ 269 total_sg_needed = (rd_dev->rd_page_count * prot_length / block_size) + 1; 270 271 sg_tables = (total_sg_needed / max_sg_per_table) + 1; 272 273 sg_table = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL); 274 if (!sg_table) { 275 pr_err("Unable to allocate memory for Ramdisk protection" 276 " scatterlist tables\n"); 277 return -ENOMEM; 278 } 279 280 rd_dev->sg_prot_array = sg_table; 281 rd_dev->sg_prot_count = sg_tables; 282 283 rc = rd_allocate_sgl_table(rd_dev, sg_table, total_sg_needed, 0xff); 284 if (rc) 285 return rc; 286 287 pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u prot space of" 288 " %u pages in %u tables\n", rd_dev->rd_host->rd_host_id, 289 rd_dev->rd_dev_id, total_sg_needed, rd_dev->sg_prot_count); 290 291 return 0; 292 } 293 294 static struct se_device *rd_alloc_device(struct se_hba *hba, const char *name) 295 { 296 struct rd_dev *rd_dev; 297 struct rd_host *rd_host = hba->hba_ptr; 298 299 rd_dev = kzalloc(sizeof(struct rd_dev), GFP_KERNEL); 300 if (!rd_dev) { 301 pr_err("Unable to allocate memory for struct rd_dev\n"); 302 return NULL; 303 } 304 305 rd_dev->rd_host = rd_host; 306 307 return &rd_dev->dev; 308 } 309 310 static int rd_configure_device(struct se_device *dev) 311 { 312 struct rd_dev *rd_dev = RD_DEV(dev); 313 struct rd_host *rd_host = dev->se_hba->hba_ptr; 314 int ret; 315 316 if (!(rd_dev->rd_flags & RDF_HAS_PAGE_COUNT)) { 317 pr_debug("Missing rd_pages= parameter\n"); 318 return -EINVAL; 319 } 320 321 ret = rd_build_device_space(rd_dev); 322 if (ret < 0) 323 goto fail; 324 325 dev->dev_attrib.hw_block_size = RD_BLOCKSIZE; 326 dev->dev_attrib.hw_max_sectors = UINT_MAX; 327 dev->dev_attrib.hw_queue_depth = RD_MAX_DEVICE_QUEUE_DEPTH; 328 dev->dev_attrib.is_nonrot = 1; 329 330 rd_dev->rd_dev_id = rd_host->rd_host_dev_id_count++; 331 332 pr_debug("CORE_RD[%u] - Added TCM MEMCPY Ramdisk Device ID: %u of" 333 " %u pages in %u tables, %lu total bytes\n", 334 rd_host->rd_host_id, rd_dev->rd_dev_id, rd_dev->rd_page_count, 335 rd_dev->sg_table_count, 336 (unsigned long)(rd_dev->rd_page_count * PAGE_SIZE)); 337 338 return 0; 339 340 fail: 341 rd_release_device_space(rd_dev); 342 return ret; 343 } 344 345 static void rd_dev_call_rcu(struct rcu_head *p) 346 { 347 struct se_device *dev = container_of(p, struct se_device, rcu_head); 348 struct rd_dev *rd_dev = RD_DEV(dev); 349 350 kfree(rd_dev); 351 } 352 353 static void rd_free_device(struct se_device *dev) 354 { 355 struct rd_dev *rd_dev = RD_DEV(dev); 356 357 rd_release_device_space(rd_dev); 358 call_rcu(&dev->rcu_head, rd_dev_call_rcu); 359 } 360 361 static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page) 362 { 363 struct rd_dev_sg_table *sg_table; 364 u32 i, sg_per_table = (RD_MAX_ALLOCATION_SIZE / 365 sizeof(struct scatterlist)); 366 367 i = page / sg_per_table; 368 if (i < rd_dev->sg_table_count) { 369 sg_table = &rd_dev->sg_table_array[i]; 370 if ((sg_table->page_start_offset <= page) && 371 (sg_table->page_end_offset >= page)) 372 return sg_table; 373 } 374 375 pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n", 376 page); 377 378 return NULL; 379 } 380 381 static struct rd_dev_sg_table *rd_get_prot_table(struct rd_dev *rd_dev, u32 page) 382 { 383 struct rd_dev_sg_table *sg_table; 384 u32 i, sg_per_table = (RD_MAX_ALLOCATION_SIZE / 385 sizeof(struct scatterlist)); 386 387 i = page / sg_per_table; 388 if (i < rd_dev->sg_prot_count) { 389 sg_table = &rd_dev->sg_prot_array[i]; 390 if ((sg_table->page_start_offset <= page) && 391 (sg_table->page_end_offset >= page)) 392 return sg_table; 393 } 394 395 pr_err("Unable to locate struct prot rd_dev_sg_table for page: %u\n", 396 page); 397 398 return NULL; 399 } 400 401 static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, bool is_read) 402 { 403 struct se_device *se_dev = cmd->se_dev; 404 struct rd_dev *dev = RD_DEV(se_dev); 405 struct rd_dev_sg_table *prot_table; 406 bool need_to_release = false; 407 struct scatterlist *prot_sg; 408 u32 sectors = cmd->data_length / se_dev->dev_attrib.block_size; 409 u32 prot_offset, prot_page; 410 u32 prot_npages __maybe_unused; 411 u64 tmp; 412 sense_reason_t rc = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; 413 414 tmp = cmd->t_task_lba * se_dev->prot_length; 415 prot_offset = do_div(tmp, PAGE_SIZE); 416 prot_page = tmp; 417 418 prot_table = rd_get_prot_table(dev, prot_page); 419 if (!prot_table) 420 return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; 421 422 prot_sg = &prot_table->sg_table[prot_page - 423 prot_table->page_start_offset]; 424 425 if (is_read) 426 rc = sbc_dif_verify(cmd, cmd->t_task_lba, sectors, 0, 427 prot_sg, prot_offset); 428 else 429 rc = sbc_dif_verify(cmd, cmd->t_task_lba, sectors, 0, 430 cmd->t_prot_sg, 0); 431 432 if (!rc) 433 sbc_dif_copy_prot(cmd, sectors, is_read, prot_sg, prot_offset); 434 435 if (need_to_release) 436 kfree(prot_sg); 437 438 return rc; 439 } 440 441 static sense_reason_t 442 rd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, 443 enum dma_data_direction data_direction) 444 { 445 struct se_device *se_dev = cmd->se_dev; 446 struct rd_dev *dev = RD_DEV(se_dev); 447 struct rd_dev_sg_table *table; 448 struct scatterlist *rd_sg; 449 struct sg_mapping_iter m; 450 u32 rd_offset; 451 u32 rd_size; 452 u32 rd_page; 453 u32 src_len; 454 u64 tmp; 455 sense_reason_t rc; 456 457 if (dev->rd_flags & RDF_NULLIO) { 458 target_complete_cmd(cmd, SAM_STAT_GOOD); 459 return 0; 460 } 461 462 tmp = cmd->t_task_lba * se_dev->dev_attrib.block_size; 463 rd_offset = do_div(tmp, PAGE_SIZE); 464 rd_page = tmp; 465 rd_size = cmd->data_length; 466 467 table = rd_get_sg_table(dev, rd_page); 468 if (!table) 469 return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; 470 471 rd_sg = &table->sg_table[rd_page - table->page_start_offset]; 472 473 pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n", 474 dev->rd_dev_id, 475 data_direction == DMA_FROM_DEVICE ? "Read" : "Write", 476 cmd->t_task_lba, rd_size, rd_page, rd_offset); 477 478 if (cmd->prot_type && se_dev->dev_attrib.pi_prot_type && 479 data_direction == DMA_TO_DEVICE) { 480 rc = rd_do_prot_rw(cmd, false); 481 if (rc) 482 return rc; 483 } 484 485 src_len = PAGE_SIZE - rd_offset; 486 sg_miter_start(&m, sgl, sgl_nents, 487 data_direction == DMA_FROM_DEVICE ? 488 SG_MITER_TO_SG : SG_MITER_FROM_SG); 489 while (rd_size) { 490 u32 len; 491 void *rd_addr; 492 493 sg_miter_next(&m); 494 if (!(u32)m.length) { 495 pr_debug("RD[%u]: invalid sgl %p len %zu\n", 496 dev->rd_dev_id, m.addr, m.length); 497 sg_miter_stop(&m); 498 return TCM_INCORRECT_AMOUNT_OF_DATA; 499 } 500 len = min((u32)m.length, src_len); 501 if (len > rd_size) { 502 pr_debug("RD[%u]: size underrun page %d offset %d " 503 "size %d\n", dev->rd_dev_id, 504 rd_page, rd_offset, rd_size); 505 len = rd_size; 506 } 507 m.consumed = len; 508 509 rd_addr = sg_virt(rd_sg) + rd_offset; 510 511 if (data_direction == DMA_FROM_DEVICE) 512 memcpy(m.addr, rd_addr, len); 513 else 514 memcpy(rd_addr, m.addr, len); 515 516 rd_size -= len; 517 if (!rd_size) 518 continue; 519 520 src_len -= len; 521 if (src_len) { 522 rd_offset += len; 523 continue; 524 } 525 526 /* rd page completed, next one please */ 527 rd_page++; 528 rd_offset = 0; 529 src_len = PAGE_SIZE; 530 if (rd_page <= table->page_end_offset) { 531 rd_sg++; 532 continue; 533 } 534 535 table = rd_get_sg_table(dev, rd_page); 536 if (!table) { 537 sg_miter_stop(&m); 538 return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; 539 } 540 541 /* since we increment, the first sg entry is correct */ 542 rd_sg = table->sg_table; 543 } 544 sg_miter_stop(&m); 545 546 if (cmd->prot_type && se_dev->dev_attrib.pi_prot_type && 547 data_direction == DMA_FROM_DEVICE) { 548 rc = rd_do_prot_rw(cmd, true); 549 if (rc) 550 return rc; 551 } 552 553 target_complete_cmd(cmd, SAM_STAT_GOOD); 554 return 0; 555 } 556 557 enum { 558 Opt_rd_pages, Opt_rd_nullio, Opt_err 559 }; 560 561 static match_table_t tokens = { 562 {Opt_rd_pages, "rd_pages=%d"}, 563 {Opt_rd_nullio, "rd_nullio=%d"}, 564 {Opt_err, NULL} 565 }; 566 567 static ssize_t rd_set_configfs_dev_params(struct se_device *dev, 568 const char *page, ssize_t count) 569 { 570 struct rd_dev *rd_dev = RD_DEV(dev); 571 char *orig, *ptr, *opts; 572 substring_t args[MAX_OPT_ARGS]; 573 int ret = 0, arg, token; 574 575 opts = kstrdup(page, GFP_KERNEL); 576 if (!opts) 577 return -ENOMEM; 578 579 orig = opts; 580 581 while ((ptr = strsep(&opts, ",\n")) != NULL) { 582 if (!*ptr) 583 continue; 584 585 token = match_token(ptr, tokens, args); 586 switch (token) { 587 case Opt_rd_pages: 588 match_int(args, &arg); 589 rd_dev->rd_page_count = arg; 590 pr_debug("RAMDISK: Referencing Page" 591 " Count: %u\n", rd_dev->rd_page_count); 592 rd_dev->rd_flags |= RDF_HAS_PAGE_COUNT; 593 break; 594 case Opt_rd_nullio: 595 match_int(args, &arg); 596 if (arg != 1) 597 break; 598 599 pr_debug("RAMDISK: Setting NULLIO flag: %d\n", arg); 600 rd_dev->rd_flags |= RDF_NULLIO; 601 break; 602 default: 603 break; 604 } 605 } 606 607 kfree(orig); 608 return (!ret) ? count : ret; 609 } 610 611 static ssize_t rd_show_configfs_dev_params(struct se_device *dev, char *b) 612 { 613 struct rd_dev *rd_dev = RD_DEV(dev); 614 615 ssize_t bl = sprintf(b, "TCM RamDisk ID: %u RamDisk Makeup: rd_mcp\n", 616 rd_dev->rd_dev_id); 617 bl += sprintf(b + bl, " PAGES/PAGE_SIZE: %u*%lu" 618 " SG_table_count: %u nullio: %d\n", rd_dev->rd_page_count, 619 PAGE_SIZE, rd_dev->sg_table_count, 620 !!(rd_dev->rd_flags & RDF_NULLIO)); 621 return bl; 622 } 623 624 static sector_t rd_get_blocks(struct se_device *dev) 625 { 626 struct rd_dev *rd_dev = RD_DEV(dev); 627 628 unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) / 629 dev->dev_attrib.block_size) - 1; 630 631 return blocks_long; 632 } 633 634 static int rd_init_prot(struct se_device *dev) 635 { 636 struct rd_dev *rd_dev = RD_DEV(dev); 637 638 if (!dev->dev_attrib.pi_prot_type) 639 return 0; 640 641 return rd_build_prot_space(rd_dev, dev->prot_length, 642 dev->dev_attrib.block_size); 643 } 644 645 static void rd_free_prot(struct se_device *dev) 646 { 647 struct rd_dev *rd_dev = RD_DEV(dev); 648 649 rd_release_prot_space(rd_dev); 650 } 651 652 static struct sbc_ops rd_sbc_ops = { 653 .execute_rw = rd_execute_rw, 654 }; 655 656 static sense_reason_t 657 rd_parse_cdb(struct se_cmd *cmd) 658 { 659 return sbc_parse_cdb(cmd, &rd_sbc_ops); 660 } 661 662 static const struct target_backend_ops rd_mcp_ops = { 663 .name = "rd_mcp", 664 .inquiry_prod = "RAMDISK-MCP", 665 .inquiry_rev = RD_MCP_VERSION, 666 .attach_hba = rd_attach_hba, 667 .detach_hba = rd_detach_hba, 668 .alloc_device = rd_alloc_device, 669 .configure_device = rd_configure_device, 670 .free_device = rd_free_device, 671 .parse_cdb = rd_parse_cdb, 672 .set_configfs_dev_params = rd_set_configfs_dev_params, 673 .show_configfs_dev_params = rd_show_configfs_dev_params, 674 .get_device_type = sbc_get_device_type, 675 .get_blocks = rd_get_blocks, 676 .init_prot = rd_init_prot, 677 .free_prot = rd_free_prot, 678 .tb_dev_attrib_attrs = sbc_attrib_attrs, 679 }; 680 681 int __init rd_module_init(void) 682 { 683 return transport_backend_register(&rd_mcp_ops); 684 } 685 686 void rd_module_exit(void) 687 { 688 target_backend_unregister(&rd_mcp_ops); 689 } 690