drivers/mtd/ubi/debug.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (c) International Business Machines Corp., 2006
   4  *
   5  * Author: Artem Bityutskiy (Битюцкий Артём)
   6  */
   7
   8 #include "ubi.h"
   9 #include <linux/debugfs.h>
  10 #include <linux/uaccess.h>
  11 #include <linux/module.h>
  12 #include <linux/seq_file.h>
  13
  14
  15 /**
  16  * ubi_dump_flash - dump a region of flash.
  17  * @ubi: UBI device description object
  18  * @pnum: the physical eraseblock number to dump
  19  * @offset: the starting offset within the physical eraseblock to dump
  20  * @len: the length of the region to dump
  21  */
  22 void ubi_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len)
  23 {
  24         int err;
  25         size_t read;
  26         void *buf;
  27         loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
  28
  29         buf = vmalloc(len);
  30         if (!buf)
  31                 return;
  32         err = mtd_read(ubi->mtd, addr, len, &read, buf);
  33         if (err && err != -EUCLEAN) {
  34                 ubi_err(ubi, "err %d while reading %d bytes from PEB %d:%d, read %zd bytes",
  35                         err, len, pnum, offset, read);
  36                 goto out;
  37         }
  38
  39         ubi_msg(ubi, "dumping %d bytes of data from PEB %d, offset %d",
  40                 len, pnum, offset);
  41         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1, buf, len, 1);
  42 out:
  43         vfree(buf);
  44         return;
  45 }
  46
  47 /**
  48  * ubi_dump_ec_hdr - dump an erase counter header.
  49  * @ec_hdr: the erase counter header to dump
  50  */
  51 void ubi_dump_ec_hdr(const struct ubi_ec_hdr *ec_hdr)
  52 {
  53         pr_err("Erase counter header dump:\n");
  54         pr_err("\tmagic          %#08x\n", be32_to_cpu(ec_hdr->magic));
  55         pr_err("\tversion        %d\n", (int)ec_hdr->version);
  56         pr_err("\tec             %llu\n", (long long)be64_to_cpu(ec_hdr->ec));
  57         pr_err("\tvid_hdr_offset %d\n", be32_to_cpu(ec_hdr->vid_hdr_offset));
  58         pr_err("\tdata_offset    %d\n", be32_to_cpu(ec_hdr->data_offset));
  59         pr_err("\timage_seq      %d\n", be32_to_cpu(ec_hdr->image_seq));
  60         pr_err("\thdr_crc        %#08x\n", be32_to_cpu(ec_hdr->hdr_crc));
  61         pr_err("erase counter header hexdump:\n");
  62         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
  63                        ec_hdr, UBI_EC_HDR_SIZE, 1);
  64 }
  65
  66 /**
  67  * ubi_dump_vid_hdr - dump a volume identifier header.
  68  * @vid_hdr: the volume identifier header to dump
  69  */
  70 void ubi_dump_vid_hdr(const struct ubi_vid_hdr *vid_hdr)
  71 {
  72         pr_err("Volume identifier header dump:\n");
  73         pr_err("\tmagic     %08x\n", be32_to_cpu(vid_hdr->magic));
  74         pr_err("\tversion   %d\n",  (int)vid_hdr->version);
  75         pr_err("\tvol_type  %d\n",  (int)vid_hdr->vol_type);
  76         pr_err("\tcopy_flag %d\n",  (int)vid_hdr->copy_flag);
  77         pr_err("\tcompat    %d\n",  (int)vid_hdr->compat);
  78         pr_err("\tvol_id    %d\n",  be32_to_cpu(vid_hdr->vol_id));
  79         pr_err("\tlnum      %d\n",  be32_to_cpu(vid_hdr->lnum));
  80         pr_err("\tdata_size %d\n",  be32_to_cpu(vid_hdr->data_size));
  81         pr_err("\tused_ebs  %d\n",  be32_to_cpu(vid_hdr->used_ebs));
  82         pr_err("\tdata_pad  %d\n",  be32_to_cpu(vid_hdr->data_pad));
  83         pr_err("\tsqnum     %llu\n",
  84                 (unsigned long long)be64_to_cpu(vid_hdr->sqnum));
  85         pr_err("\thdr_crc   %08x\n", be32_to_cpu(vid_hdr->hdr_crc));
  86         pr_err("Volume identifier header hexdump:\n");
  87         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
  88                        vid_hdr, UBI_VID_HDR_SIZE, 1);
  89 }
  90
  91 /**
  92  * ubi_dump_vol_info - dump volume information.
  93  * @vol: UBI volume description object
  94  */
  95 void ubi_dump_vol_info(const struct ubi_volume *vol)
  96 {
  97         pr_err("Volume information dump:\n");
  98         pr_err("\tvol_id          %d\n", vol->vol_id);
  99         pr_err("\treserved_pebs   %d\n", vol->reserved_pebs);
 100         pr_err("\talignment       %d\n", vol->alignment);
 101         pr_err("\tdata_pad        %d\n", vol->data_pad);
 102         pr_err("\tvol_type        %d\n", vol->vol_type);
 103         pr_err("\tname_len        %d\n", vol->name_len);
 104         pr_err("\tusable_leb_size %d\n", vol->usable_leb_size);
 105         pr_err("\tused_ebs        %d\n", vol->used_ebs);
 106         pr_err("\tused_bytes      %lld\n", vol->used_bytes);
 107         pr_err("\tlast_eb_bytes   %d\n", vol->last_eb_bytes);
 108         pr_err("\tcorrupted       %d\n", vol->corrupted);
 109         pr_err("\tupd_marker      %d\n", vol->upd_marker);
 110         pr_err("\tskip_check      %d\n", vol->skip_check);
 111
 112         if (vol->name_len <= UBI_VOL_NAME_MAX &&
 113             strnlen(vol->name, vol->name_len + 1) == vol->name_len) {
 114                 pr_err("\tname            %s\n", vol->name);
 115         } else {
 116                 pr_err("\t1st 5 characters of name: %c%c%c%c%c\n",
 117                        vol->name[0], vol->name[1], vol->name[2],
 118                        vol->name[3], vol->name[4]);
 119         }
 120 }
 121
 122 /**
 123  * ubi_dump_vtbl_record - dump a &struct ubi_vtbl_record object.
 124  * @r: the object to dump
 125  * @idx: volume table index
 126  */
 127 void ubi_dump_vtbl_record(const struct ubi_vtbl_record *r, int idx)
 128 {
 129         int name_len = be16_to_cpu(r->name_len);
 130
 131         pr_err("Volume table record %d dump:\n", idx);
 132         pr_err("\treserved_pebs   %d\n", be32_to_cpu(r->reserved_pebs));
 133         pr_err("\talignment       %d\n", be32_to_cpu(r->alignment));
 134         pr_err("\tdata_pad        %d\n", be32_to_cpu(r->data_pad));
 135         pr_err("\tvol_type        %d\n", (int)r->vol_type);
 136         pr_err("\tupd_marker      %d\n", (int)r->upd_marker);
 137         pr_err("\tname_len        %d\n", name_len);
 138
 139         if (r->name[0] == '\0') {
 140                 pr_err("\tname            NULL\n");
 141                 return;
 142         }
 143
 144         if (name_len <= UBI_VOL_NAME_MAX &&
 145             strnlen(&r->name[0], name_len + 1) == name_len) {
 146                 pr_err("\tname            %s\n", &r->name[0]);
 147         } else {
 148                 pr_err("\t1st 5 characters of name: %c%c%c%c%c\n",
 149                         r->name[0], r->name[1], r->name[2], r->name[3],
 150                         r->name[4]);
 151         }
 152         pr_err("\tcrc             %#08x\n", be32_to_cpu(r->crc));
 153 }
 154
 155 /**
 156  * ubi_dump_av - dump a &struct ubi_ainf_volume object.
 157  * @av: the object to dump
 158  */
 159 void ubi_dump_av(const struct ubi_ainf_volume *av)
 160 {
 161         pr_err("Volume attaching information dump:\n");
 162         pr_err("\tvol_id         %d\n", av->vol_id);
 163         pr_err("\thighest_lnum   %d\n", av->highest_lnum);
 164         pr_err("\tleb_count      %d\n", av->leb_count);
 165         pr_err("\tcompat         %d\n", av->compat);
 166         pr_err("\tvol_type       %d\n", av->vol_type);
 167         pr_err("\tused_ebs       %d\n", av->used_ebs);
 168         pr_err("\tlast_data_size %d\n", av->last_data_size);
 169         pr_err("\tdata_pad       %d\n", av->data_pad);
 170 }
 171
 172 /**
 173  * ubi_dump_aeb - dump a &struct ubi_ainf_peb object.
 174  * @aeb: the object to dump
 175  * @type: object type: 0 - not corrupted, 1 - corrupted
 176  */
 177 void ubi_dump_aeb(const struct ubi_ainf_peb *aeb, int type)
 178 {
 179         pr_err("eraseblock attaching information dump:\n");
 180         pr_err("\tec       %d\n", aeb->ec);
 181         pr_err("\tpnum     %d\n", aeb->pnum);
 182         if (type == 0) {
 183                 pr_err("\tlnum     %d\n", aeb->lnum);
 184                 pr_err("\tscrub    %d\n", aeb->scrub);
 185                 pr_err("\tsqnum    %llu\n", aeb->sqnum);
 186         }
 187 }
 188
 189 /**
 190  * ubi_dump_mkvol_req - dump a &struct ubi_mkvol_req object.
 191  * @req: the object to dump
 192  */
 193 void ubi_dump_mkvol_req(const struct ubi_mkvol_req *req)
 194 {
 195         char nm[17];
 196
 197         pr_err("Volume creation request dump:\n");
 198         pr_err("\tvol_id    %d\n",   req->vol_id);
 199         pr_err("\talignment %d\n",   req->alignment);
 200         pr_err("\tbytes     %lld\n", (long long)req->bytes);
 201         pr_err("\tvol_type  %d\n",   req->vol_type);
 202         pr_err("\tname_len  %d\n",   req->name_len);
 203
 204         memcpy(nm, req->name, 16);
 205         nm[16] = 0;
 206         pr_err("\t1st 16 characters of name: %s\n", nm);
 207 }
 208
 209 /*
 210  * Root directory for UBI stuff in debugfs. Contains sub-directories which
 211  * contain the stuff specific to particular UBI devices.
 212  */
 213 static struct dentry *dfs_rootdir;
 214
 215 /**
 216  * ubi_debugfs_init - create UBI debugfs directory.
 217  *
 218  * Create UBI debugfs directory. Returns zero in case of success and a negative
 219  * error code in case of failure.
 220  */
 221 int ubi_debugfs_init(void)
 222 {
 223         if (!IS_ENABLED(CONFIG_DEBUG_FS))
 224                 return 0;
 225
 226         dfs_rootdir = debugfs_create_dir("ubi", NULL);
 227         if (IS_ERR_OR_NULL(dfs_rootdir)) {
 228                 int err = dfs_rootdir ? PTR_ERR(dfs_rootdir) : -ENODEV;
 229
 230                 pr_err("UBI error: cannot create \"ubi\" debugfs directory, error %d\n",
 231                        err);
 232                 return err;
 233         }
 234
 235         return 0;
 236 }
 237
 238 /**
 239  * ubi_debugfs_exit - remove UBI debugfs directory.
 240  */
 241 void ubi_debugfs_exit(void)
 242 {
 243         if (IS_ENABLED(CONFIG_DEBUG_FS))
 244                 debugfs_remove(dfs_rootdir);
 245 }
 246
 247 /* Read an UBI debugfs file */
 248 static ssize_t dfs_file_read(struct file *file, char __user *user_buf,
 249                              size_t count, loff_t *ppos)
 250 {
 251         unsigned long ubi_num = (unsigned long)file->private_data;
 252         struct dentry *dent = file->f_path.dentry;
 253         struct ubi_device *ubi;
 254         struct ubi_debug_info *d;
 255         char buf[8];
 256         int val;
 257
 258         ubi = ubi_get_device(ubi_num);
 259         if (!ubi)
 260                 return -ENODEV;
 261         d = &ubi->dbg;
 262
 263         if (dent == d->dfs_chk_gen)
 264                 val = d->chk_gen;
 265         else if (dent == d->dfs_chk_io)
 266                 val = d->chk_io;
 267         else if (dent == d->dfs_chk_fastmap)
 268                 val = d->chk_fastmap;
 269         else if (dent == d->dfs_disable_bgt)
 270                 val = d->disable_bgt;
 271         else if (dent == d->dfs_emulate_bitflips)
 272                 val = d->emulate_bitflips;
 273         else if (dent == d->dfs_emulate_io_failures)
 274                 val = d->emulate_io_failures;
 275         else if (dent == d->dfs_emulate_power_cut) {
 276                 snprintf(buf, sizeof(buf), "%u\n", d->emulate_power_cut);
 277                 count = simple_read_from_buffer(user_buf, count, ppos,
 278                                                 buf, strlen(buf));
 279                 goto out;
 280         } else if (dent == d->dfs_power_cut_min) {
 281                 snprintf(buf, sizeof(buf), "%u\n", d->power_cut_min);
 282                 count = simple_read_from_buffer(user_buf, count, ppos,
 283                                                 buf, strlen(buf));
 284                 goto out;
 285         } else if (dent == d->dfs_power_cut_max) {
 286                 snprintf(buf, sizeof(buf), "%u\n", d->power_cut_max);
 287                 count = simple_read_from_buffer(user_buf, count, ppos,
 288                                                 buf, strlen(buf));
 289                 goto out;
 290         }
 291         else {
 292                 count = -EINVAL;
 293                 goto out;
 294         }
 295
 296         if (val)
 297                 buf[0] = '1';
 298         else
 299                 buf[0] = '0';
 300         buf[1] = '\n';
 301         buf[2] = 0x00;
 302
 303         count = simple_read_from_buffer(user_buf, count, ppos, buf, 2);
 304
 305 out:
 306         ubi_put_device(ubi);
 307         return count;
 308 }
 309
 310 /* Write an UBI debugfs file */
 311 static ssize_t dfs_file_write(struct file *file, const char __user *user_buf,
 312                               size_t count, loff_t *ppos)
 313 {
 314         unsigned long ubi_num = (unsigned long)file->private_data;
 315         struct dentry *dent = file->f_path.dentry;
 316         struct ubi_device *ubi;
 317         struct ubi_debug_info *d;
 318         size_t buf_size;
 319         char buf[8] = {0};
 320         int val;
 321
 322         ubi = ubi_get_device(ubi_num);
 323         if (!ubi)
 324                 return -ENODEV;
 325         d = &ubi->dbg;
 326
 327         buf_size = min_t(size_t, count, (sizeof(buf) - 1));
 328         if (copy_from_user(buf, user_buf, buf_size)) {
 329                 count = -EFAULT;
 330                 goto out;
 331         }
 332
 333         if (dent == d->dfs_power_cut_min) {
 334                 if (kstrtouint(buf, 0, &d->power_cut_min) != 0)
 335                         count = -EINVAL;
 336                 goto out;
 337         } else if (dent == d->dfs_power_cut_max) {
 338                 if (kstrtouint(buf, 0, &d->power_cut_max) != 0)
 339                         count = -EINVAL;
 340                 goto out;
 341         } else if (dent == d->dfs_emulate_power_cut) {
 342                 if (kstrtoint(buf, 0, &val) != 0)
 343                         count = -EINVAL;
 344                 else
 345                         d->emulate_power_cut = val;
 346                 goto out;
 347         }
 348
 349         if (buf[0] == '1')
 350                 val = 1;
 351         else if (buf[0] == '0')
 352                 val = 0;
 353         else {
 354                 count = -EINVAL;
 355                 goto out;
 356         }
 357
 358         if (dent == d->dfs_chk_gen)
 359                 d->chk_gen = val;
 360         else if (dent == d->dfs_chk_io)
 361                 d->chk_io = val;
 362         else if (dent == d->dfs_chk_fastmap)
 363                 d->chk_fastmap = val;
 364         else if (dent == d->dfs_disable_bgt)
 365                 d->disable_bgt = val;
 366         else if (dent == d->dfs_emulate_bitflips)
 367                 d->emulate_bitflips = val;
 368         else if (dent == d->dfs_emulate_io_failures)
 369                 d->emulate_io_failures = val;
 370         else
 371                 count = -EINVAL;
 372
 373 out:
 374         ubi_put_device(ubi);
 375         return count;
 376 }
 377
 378 /* File operations for all UBI debugfs files except
 379  * detailed_erase_block_info
 380  */
 381 static const struct file_operations dfs_fops = {
 382         .read   = dfs_file_read,
 383         .write  = dfs_file_write,
 384         .open   = simple_open,
 385         .llseek = no_llseek,
 386         .owner  = THIS_MODULE,
 387 };
 388
 389 /* As long as the position is less then that total number of erase blocks,
 390  * we still have more to print.
 391  */
 392 static void *eraseblk_count_seq_start(struct seq_file *s, loff_t *pos)
 393 {
 394         struct ubi_device *ubi = s->private;
 395
 396         if (*pos < ubi->peb_count)
 397                 return pos;
 398
 399         return NULL;
 400 }
 401
 402 /* Since we are using the position as the iterator, we just need to check if we
 403  * are done and increment the position.
 404  */
 405 static void *eraseblk_count_seq_next(struct seq_file *s, void *v, loff_t *pos)
 406 {
 407         struct ubi_device *ubi = s->private;
 408
 409         (*pos)++;
 410
 411         if (*pos < ubi->peb_count)
 412                 return pos;
 413
 414         return NULL;
 415 }
 416
 417 static void eraseblk_count_seq_stop(struct seq_file *s, void *v)
 418 {
 419 }
 420
 421 static int eraseblk_count_seq_show(struct seq_file *s, void *iter)
 422 {
 423         struct ubi_device *ubi = s->private;
 424         struct ubi_wl_entry *wl;
 425         int *block_number = iter;
 426         int erase_count = -1;
 427         int err;
 428
 429         /* If this is the start, print a header */
 430         if (*block_number == 0)
 431                 seq_puts(s, "physical_block_number\terase_count\n");
 432
 433         err = ubi_io_is_bad(ubi, *block_number);
 434         if (err)
 435                 return err;
 436
 437         spin_lock(&ubi->wl_lock);
 438
 439         wl = ubi->lookuptbl[*block_number];
 440         if (wl)
 441                 erase_count = wl->ec;
 442
 443         spin_unlock(&ubi->wl_lock);
 444
 445         if (erase_count < 0)
 446                 return 0;
 447
 448         seq_printf(s, "%-22d\t%-11d\n", *block_number, erase_count);
 449
 450         return 0;
 451 }
 452
 453 static const struct seq_operations eraseblk_count_seq_ops = {
 454         .start = eraseblk_count_seq_start,
 455         .next = eraseblk_count_seq_next,
 456         .stop = eraseblk_count_seq_stop,
 457         .show = eraseblk_count_seq_show
 458 };
 459
 460 static int eraseblk_count_open(struct inode *inode, struct file *f)
 461 {
 462         struct seq_file *s;
 463         int err;
 464
 465         err = seq_open(f, &eraseblk_count_seq_ops);
 466         if (err)
 467                 return err;
 468
 469         s = f->private_data;
 470         s->private = ubi_get_device((unsigned long)inode->i_private);
 471
 472         if (!s->private)
 473                 return -ENODEV;
 474         else
 475                 return 0;
 476 }
 477
 478 static int eraseblk_count_release(struct inode *inode, struct file *f)
 479 {
 480         struct seq_file *s = f->private_data;
 481         struct ubi_device *ubi = s->private;
 482
 483         ubi_put_device(ubi);
 484
 485         return seq_release(inode, f);
 486 }
 487
 488 static const struct file_operations eraseblk_count_fops = {
 489         .owner = THIS_MODULE,
 490         .open = eraseblk_count_open,
 491         .read = seq_read,
 492         .llseek = seq_lseek,
 493         .release = eraseblk_count_release,
 494 };
 495
 496 /**
 497  * ubi_debugfs_init_dev - initialize debugfs for an UBI device.
 498  * @ubi: UBI device description object
 499  *
 500  * This function creates all debugfs files for UBI device @ubi. Returns zero in
 501  * case of success and a negative error code in case of failure.
 502  */
 503 int ubi_debugfs_init_dev(struct ubi_device *ubi)
 504 {
 505         unsigned long ubi_num = ubi->ubi_num;
 506         struct ubi_debug_info *d = &ubi->dbg;
 507         int n;
 508
 509         if (!IS_ENABLED(CONFIG_DEBUG_FS))
 510                 return 0;
 511
 512         n = snprintf(d->dfs_dir_name, UBI_DFS_DIR_LEN + 1, UBI_DFS_DIR_NAME,
 513                      ubi->ubi_num);
 514         if (n > UBI_DFS_DIR_LEN) {
 515                 /* The array size is too small */
 516                 return -EINVAL;
 517         }
 518
 519         d->dfs_dir = debugfs_create_dir(d->dfs_dir_name, dfs_rootdir);
 520
 521         d->dfs_chk_gen = debugfs_create_file("chk_gen", S_IWUSR, d->dfs_dir,
 522                                              (void *)ubi_num, &dfs_fops);
 523
 524         d->dfs_chk_io = debugfs_create_file("chk_io", S_IWUSR, d->dfs_dir,
 525                                             (void *)ubi_num, &dfs_fops);
 526
 527         d->dfs_chk_fastmap = debugfs_create_file("chk_fastmap", S_IWUSR,
 528                                                  d->dfs_dir, (void *)ubi_num,
 529                                                  &dfs_fops);
 530
 531         d->dfs_disable_bgt = debugfs_create_file("tst_disable_bgt", S_IWUSR,
 532                                                  d->dfs_dir, (void *)ubi_num,
 533                                                  &dfs_fops);
 534
 535         d->dfs_emulate_bitflips = debugfs_create_file("tst_emulate_bitflips",
 536                                                       S_IWUSR, d->dfs_dir,
 537                                                       (void *)ubi_num,
 538                                                       &dfs_fops);
 539
 540         d->dfs_emulate_io_failures = debugfs_create_file("tst_emulate_io_failures",
 541                                                          S_IWUSR, d->dfs_dir,
 542                                                          (void *)ubi_num,
 543                                                          &dfs_fops);
 544
 545         d->dfs_emulate_power_cut = debugfs_create_file("tst_emulate_power_cut",
 546                                                        S_IWUSR, d->dfs_dir,
 547                                                        (void *)ubi_num,
 548                                                        &dfs_fops);
 549
 550         d->dfs_power_cut_min = debugfs_create_file("tst_emulate_power_cut_min",
 551                                                    S_IWUSR, d->dfs_dir,
 552                                                    (void *)ubi_num, &dfs_fops);
 553
 554         d->dfs_power_cut_max = debugfs_create_file("tst_emulate_power_cut_max",
 555                                                    S_IWUSR, d->dfs_dir,
 556                                                    (void *)ubi_num, &dfs_fops);
 557
 558         debugfs_create_file("detailed_erase_block_info", S_IRUSR, d->dfs_dir,
 559                             (void *)ubi_num, &eraseblk_count_fops);
 560
 561         return 0;
 562 }
 563
 564 /**
 565  * ubi_debugfs_exit_dev - free all debugfs files corresponding to device @ubi
 566  * @ubi: UBI device description object
 567  */
 568 void ubi_debugfs_exit_dev(struct ubi_device *ubi)
 569 {
 570         if (IS_ENABLED(CONFIG_DEBUG_FS))
 571                 debugfs_remove_recursive(ubi->dbg.dfs_dir);
 572 }
 573
 574 /**
 575  * ubi_dbg_power_cut - emulate a power cut if it is time to do so
 576  * @ubi: UBI device description object
 577  * @caller: Flags set to indicate from where the function is being called
 578  *
 579  * Returns non-zero if a power cut was emulated, zero if not.
 580  */
 581 int ubi_dbg_power_cut(struct ubi_device *ubi, int caller)
 582 {
 583         unsigned int range;
 584
 585         if ((ubi->dbg.emulate_power_cut & caller) == 0)
 586                 return 0;
 587
 588         if (ubi->dbg.power_cut_counter == 0) {
 589                 ubi->dbg.power_cut_counter = ubi->dbg.power_cut_min;
 590
 591                 if (ubi->dbg.power_cut_max > ubi->dbg.power_cut_min) {
 592                         range = ubi->dbg.power_cut_max - ubi->dbg.power_cut_min;
 593                         ubi->dbg.power_cut_counter += get_random_u32_below(range);
 594                 }
 595                 return 0;
 596         }
 597
 598         ubi->dbg.power_cut_counter--;
 599         if (ubi->dbg.power_cut_counter)
 600                 return 0;
 601
 602         ubi_msg(ubi, "XXXXXXXXXXXXXXX emulating a power cut XXXXXXXXXXXXXXXX");
 603         ubi_ro_mode(ubi);
 604         return 1;
 605 }