fs/pstore/platform.c

   1 /*
   2  * Persistent Storage - platform driver interface parts.
   3  *
   4  * Copyright (C) 2007-2008 Google, Inc.
   5  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #define pr_fmt(fmt) "pstore: " fmt
  22
  23 #include <linux/atomic.h>
  24 #include <linux/types.h>
  25 #include <linux/errno.h>
  26 #include <linux/init.h>
  27 #include <linux/kmsg_dump.h>
  28 #include <linux/console.h>
  29 #include <linux/module.h>
  30 #include <linux/pstore.h>
  31 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
  32 #include <linux/lzo.h>
  33 #endif
  34 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
  35 #include <linux/lz4.h>
  36 #endif
  37 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
  38 #include <linux/zstd.h>
  39 #endif
  40 #include <linux/crypto.h>
  41 #include <linux/string.h>
  42 #include <linux/timer.h>
  43 #include <linux/slab.h>
  44 #include <linux/uaccess.h>
  45 #include <linux/jiffies.h>
  46 #include <linux/workqueue.h>
  47
  48 #include "internal.h"
  49
  50 /*
  51  * We defer making "oops" entries appear in pstore - see
  52  * whether the system is actually still running well enough
  53  * to let someone see the entry
  54  */
  55 static int pstore_update_ms = -1;
  56 module_param_named(update_ms, pstore_update_ms, int, 0600);
  57 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
  58                  "(default is -1, which means runtime updates are disabled; "
  59                  "enabling this option is not safe, it may lead to further "
  60                  "corruption on Oopses)");
  61
  62 static int pstore_new_entry;
  63
  64 static void pstore_timefunc(struct timer_list *);
  65 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
  66
  67 static void pstore_dowork(struct work_struct *);
  68 static DECLARE_WORK(pstore_work, pstore_dowork);
  69
  70 /*
  71  * pstore_lock just protects "psinfo" during
  72  * calls to pstore_register()
  73  */
  74 static DEFINE_SPINLOCK(pstore_lock);
  75 struct pstore_info *psinfo;
  76
  77 static char *backend;
  78 static char *compress =
  79 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
  80                 CONFIG_PSTORE_COMPRESS_DEFAULT;
  81 #else
  82                 NULL;
  83 #endif
  84
  85 /* Compression parameters */
  86 static struct crypto_comp *tfm;
  87
  88 struct pstore_zbackend {
  89         int (*zbufsize)(size_t size);
  90         const char *name;
  91 };
  92
  93 static char *big_oops_buf;
  94 static size_t big_oops_buf_sz;
  95
  96 /* How much of the console log to snapshot */
  97 unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
  98
  99 void pstore_set_kmsg_bytes(int bytes)
 100 {
 101         kmsg_bytes = bytes;
 102 }
 103
 104 /* Tag each group of saved records with a sequence number */
 105 static int      oopscount;
 106
 107 static const char *get_reason_str(enum kmsg_dump_reason reason)
 108 {
 109         switch (reason) {
 110         case KMSG_DUMP_PANIC:
 111                 return "Panic";
 112         case KMSG_DUMP_OOPS:
 113                 return "Oops";
 114         case KMSG_DUMP_EMERG:
 115                 return "Emergency";
 116         case KMSG_DUMP_RESTART:
 117                 return "Restart";
 118         case KMSG_DUMP_HALT:
 119                 return "Halt";
 120         case KMSG_DUMP_POWEROFF:
 121                 return "Poweroff";
 122         default:
 123                 return "Unknown";
 124         }
 125 }
 126
 127 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 128 {
 129         /*
 130          * In case of NMI path, pstore shouldn't be blocked
 131          * regardless of reason.
 132          */
 133         if (in_nmi())
 134                 return true;
 135
 136         switch (reason) {
 137         /* In panic case, other cpus are stopped by smp_send_stop(). */
 138         case KMSG_DUMP_PANIC:
 139         /* Emergency restart shouldn't be blocked by spin lock. */
 140         case KMSG_DUMP_EMERG:
 141                 return true;
 142         default:
 143                 return false;
 144         }
 145 }
 146 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
 147
 148 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 149 static int zbufsize_deflate(size_t size)
 150 {
 151         size_t cmpr;
 152
 153         switch (size) {
 154         /* buffer range for efivars */
 155         case 1000 ... 2000:
 156                 cmpr = 56;
 157                 break;
 158         case 2001 ... 3000:
 159                 cmpr = 54;
 160                 break;
 161         case 3001 ... 3999:
 162                 cmpr = 52;
 163                 break;
 164         /* buffer range for nvram, erst */
 165         case 4000 ... 10000:
 166                 cmpr = 45;
 167                 break;
 168         default:
 169                 cmpr = 60;
 170                 break;
 171         }
 172
 173         return (size * 100) / cmpr;
 174 }
 175 #endif
 176
 177 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 178 static int zbufsize_lzo(size_t size)
 179 {
 180         return lzo1x_worst_compress(size);
 181 }
 182 #endif
 183
 184 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 185 static int zbufsize_lz4(size_t size)
 186 {
 187         return LZ4_compressBound(size);
 188 }
 189 #endif
 190
 191 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 192 static int zbufsize_842(size_t size)
 193 {
 194         return size;
 195 }
 196 #endif
 197
 198 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 199 static int zbufsize_zstd(size_t size)
 200 {
 201         return ZSTD_compressBound(size);
 202 }
 203 #endif
 204
 205 static const struct pstore_zbackend *zbackend __ro_after_init;
 206
 207 static const struct pstore_zbackend zbackends[] = {
 208 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 209         {
 210                 .zbufsize       = zbufsize_deflate,
 211                 .name           = "deflate",
 212         },
 213 #endif
 214 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 215         {
 216                 .zbufsize       = zbufsize_lzo,
 217                 .name           = "lzo",
 218         },
 219 #endif
 220 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
 221         {
 222                 .zbufsize       = zbufsize_lz4,
 223                 .name           = "lz4",
 224         },
 225 #endif
 226 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 227         {
 228                 .zbufsize       = zbufsize_lz4,
 229                 .name           = "lz4hc",
 230         },
 231 #endif
 232 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 233         {
 234                 .zbufsize       = zbufsize_842,
 235                 .name           = "842",
 236         },
 237 #endif
 238 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 239         {
 240                 .zbufsize       = zbufsize_zstd,
 241                 .name           = "zstd",
 242         },
 243 #endif
 244         { }
 245 };
 246
 247 static int pstore_compress(const void *in, void *out,
 248                            unsigned int inlen, unsigned int outlen)
 249 {
 250         int ret;
 251
 252         ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
 253         if (ret) {
 254                 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
 255                 return ret;
 256         }
 257
 258         return outlen;
 259 }
 260
 261 static int pstore_decompress(void *in, void *out,
 262                              unsigned int inlen, unsigned int outlen)
 263 {
 264         int ret;
 265
 266         ret = crypto_comp_decompress(tfm, in, inlen, out, &outlen);
 267         if (ret) {
 268                 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
 269                 return ret;
 270         }
 271
 272         return outlen;
 273 }
 274
 275 static void allocate_buf_for_compression(void)
 276 {
 277         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
 278                 return;
 279
 280         if (!crypto_has_comp(zbackend->name, 0, 0)) {
 281                 pr_err("No %s compression\n", zbackend->name);
 282                 return;
 283         }
 284
 285         big_oops_buf_sz = zbackend->zbufsize(psinfo->bufsize);
 286         if (big_oops_buf_sz <= 0)
 287                 return;
 288
 289         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 290         if (!big_oops_buf) {
 291                 pr_err("allocate compression buffer error!\n");
 292                 return;
 293         }
 294
 295         tfm = crypto_alloc_comp(zbackend->name, 0, 0);
 296         if (IS_ERR_OR_NULL(tfm)) {
 297                 kfree(big_oops_buf);
 298                 big_oops_buf = NULL;
 299                 pr_err("crypto_alloc_comp() failed!\n");
 300                 return;
 301         }
 302 }
 303
 304 static void free_buf_for_compression(void)
 305 {
 306         if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && !IS_ERR_OR_NULL(tfm))
 307                 crypto_free_comp(tfm);
 308         kfree(big_oops_buf);
 309         big_oops_buf = NULL;
 310         big_oops_buf_sz = 0;
 311 }
 312
 313 /*
 314  * Called when compression fails, since the printk buffer
 315  * would be fetched for compression calling it again when
 316  * compression fails would have moved the iterator of
 317  * printk buffer which results in fetching old contents.
 318  * Copy the recent messages from big_oops_buf to psinfo->buf
 319  */
 320 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 321 {
 322         size_t total_len;
 323         size_t diff;
 324
 325         total_len = hsize + len;
 326
 327         if (total_len > psinfo->bufsize) {
 328                 diff = total_len - psinfo->bufsize + hsize;
 329                 memcpy(psinfo->buf, big_oops_buf, hsize);
 330                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 331                                         psinfo->bufsize - hsize);
 332                 total_len = psinfo->bufsize;
 333         } else
 334                 memcpy(psinfo->buf, big_oops_buf, total_len);
 335
 336         return total_len;
 337 }
 338
 339 void pstore_record_init(struct pstore_record *record,
 340                         struct pstore_info *psinfo)
 341 {
 342         memset(record, 0, sizeof(*record));
 343
 344         record->psi = psinfo;
 345
 346         /* Report zeroed timestamp if called before timekeeping has resumed. */
 347         record->time = ns_to_timespec64(ktime_get_real_fast_ns());
 348 }
 349
 350 /*
 351  * callback from kmsg_dump. (s2,l2) has the most recently
 352  * written bytes, older bytes are in (s1,l1). Save as much
 353  * as we can from the end of the buffer.
 354  */
 355 static void pstore_dump(struct kmsg_dumper *dumper,
 356                         enum kmsg_dump_reason reason)
 357 {
 358         unsigned long   total = 0;
 359         const char      *why;
 360         unsigned int    part = 1;
 361         unsigned long   flags = 0;
 362         int             is_locked;
 363         int             ret;
 364
 365         why = get_reason_str(reason);
 366
 367         if (pstore_cannot_block_path(reason)) {
 368                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 369                 if (!is_locked) {
 370                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 371                                        , in_nmi() ? "NMI" : why);
 372                         return;
 373                 }
 374         } else {
 375                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 376                 is_locked = 1;
 377         }
 378         oopscount++;
 379         while (total < kmsg_bytes) {
 380                 char *dst;
 381                 size_t dst_size;
 382                 int header_size;
 383                 int zipped_len = -1;
 384                 size_t dump_size;
 385                 struct pstore_record record;
 386
 387                 pstore_record_init(&record, psinfo);
 388                 record.type = PSTORE_TYPE_DMESG;
 389                 record.count = oopscount;
 390                 record.reason = reason;
 391                 record.part = part;
 392                 record.buf = psinfo->buf;
 393
 394                 if (big_oops_buf && is_locked) {
 395                         dst = big_oops_buf;
 396                         dst_size = big_oops_buf_sz;
 397                 } else {
 398                         dst = psinfo->buf;
 399                         dst_size = psinfo->bufsize;
 400                 }
 401
 402                 /* Write dump header. */
 403                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 404                                  oopscount, part);
 405                 dst_size -= header_size;
 406
 407                 /* Write dump contents. */
 408                 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
 409                                           dst_size, &dump_size))
 410                         break;
 411
 412                 if (big_oops_buf && is_locked) {
 413                         zipped_len = pstore_compress(dst, psinfo->buf,
 414                                                 header_size + dump_size,
 415                                                 psinfo->bufsize);
 416
 417                         if (zipped_len > 0) {
 418                                 record.compressed = true;
 419                                 record.size = zipped_len;
 420                         } else {
 421                                 record.size = copy_kmsg_to_buffer(header_size,
 422                                                                   dump_size);
 423                         }
 424                 } else {
 425                         record.size = header_size + dump_size;
 426                 }
 427
 428                 ret = psinfo->write(&record);
 429                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 430                         pstore_new_entry = 1;
 431
 432                 total += record.size;
 433                 part++;
 434         }
 435         if (is_locked)
 436                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 437 }
 438
 439 static struct kmsg_dumper pstore_dumper = {
 440         .dump = pstore_dump,
 441 };
 442
 443 /*
 444  * Register with kmsg_dump to save last part of console log on panic.
 445  */
 446 static void pstore_register_kmsg(void)
 447 {
 448         kmsg_dump_register(&pstore_dumper);
 449 }
 450
 451 static void pstore_unregister_kmsg(void)
 452 {
 453         kmsg_dump_unregister(&pstore_dumper);
 454 }
 455
 456 #ifdef CONFIG_PSTORE_CONSOLE
 457 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 458 {
 459         const char *e = s + c;
 460
 461         while (s < e) {
 462                 struct pstore_record record;
 463                 unsigned long flags;
 464
 465                 pstore_record_init(&record, psinfo);
 466                 record.type = PSTORE_TYPE_CONSOLE;
 467
 468                 if (c > psinfo->bufsize)
 469                         c = psinfo->bufsize;
 470
 471                 if (oops_in_progress) {
 472                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 473                                 break;
 474                 } else {
 475                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 476                 }
 477                 record.buf = (char *)s;
 478                 record.size = c;
 479                 psinfo->write(&record);
 480                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 481                 s += c;
 482                 c = e - s;
 483         }
 484 }
 485
 486 static struct console pstore_console = {
 487         .name   = "pstore",
 488         .write  = pstore_console_write,
 489         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 490         .index  = -1,
 491 };
 492
 493 static void pstore_register_console(void)
 494 {
 495         register_console(&pstore_console);
 496 }
 497
 498 static void pstore_unregister_console(void)
 499 {
 500         unregister_console(&pstore_console);
 501 }
 502 #else
 503 static void pstore_register_console(void) {}
 504 static void pstore_unregister_console(void) {}
 505 #endif
 506
 507 static int pstore_write_user_compat(struct pstore_record *record,
 508                                     const char __user *buf)
 509 {
 510         int ret = 0;
 511
 512         if (record->buf)
 513                 return -EINVAL;
 514
 515         record->buf = memdup_user(buf, record->size);
 516         if (IS_ERR(record->buf)) {
 517                 ret = PTR_ERR(record->buf);
 518                 goto out;
 519         }
 520
 521         ret = record->psi->write(record);
 522
 523         kfree(record->buf);
 524 out:
 525         record->buf = NULL;
 526
 527         return unlikely(ret < 0) ? ret : record->size;
 528 }
 529
 530 /*
 531  * platform specific persistent storage driver registers with
 532  * us here. If pstore is already mounted, call the platform
 533  * read function right away to populate the file system. If not
 534  * then the pstore mount code will call us later to fill out
 535  * the file system.
 536  */
 537 int pstore_register(struct pstore_info *psi)
 538 {
 539         struct module *owner = psi->owner;
 540
 541         if (backend && strcmp(backend, psi->name)) {
 542                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 543                 return -EPERM;
 544         }
 545
 546         /* Sanity check flags. */
 547         if (!psi->flags) {
 548                 pr_warn("backend '%s' must support at least one frontend\n",
 549                         psi->name);
 550                 return -EINVAL;
 551         }
 552
 553         /* Check for required functions. */
 554         if (!psi->read || !psi->write) {
 555                 pr_warn("backend '%s' must implement read() and write()\n",
 556                         psi->name);
 557                 return -EINVAL;
 558         }
 559
 560         spin_lock(&pstore_lock);
 561         if (psinfo) {
 562                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 563                         psinfo->name, psi->name);
 564                 spin_unlock(&pstore_lock);
 565                 return -EBUSY;
 566         }
 567
 568         if (!psi->write_user)
 569                 psi->write_user = pstore_write_user_compat;
 570         psinfo = psi;
 571         mutex_init(&psinfo->read_mutex);
 572         spin_unlock(&pstore_lock);
 573
 574         if (owner && !try_module_get(owner)) {
 575                 psinfo = NULL;
 576                 return -EINVAL;
 577         }
 578
 579         allocate_buf_for_compression();
 580
 581         if (pstore_is_mounted())
 582                 pstore_get_records(0);
 583
 584         if (psi->flags & PSTORE_FLAGS_DMESG)
 585                 pstore_register_kmsg();
 586         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 587                 pstore_register_console();
 588         if (psi->flags & PSTORE_FLAGS_FTRACE)
 589                 pstore_register_ftrace();
 590         if (psi->flags & PSTORE_FLAGS_PMSG)
 591                 pstore_register_pmsg();
 592
 593         /* Start watching for new records, if desired. */
 594         if (pstore_update_ms >= 0) {
 595                 pstore_timer.expires = jiffies +
 596                         msecs_to_jiffies(pstore_update_ms);
 597                 add_timer(&pstore_timer);
 598         }
 599
 600         /*
 601          * Update the module parameter backend, so it is visible
 602          * through /sys/module/pstore/parameters/backend
 603          */
 604         backend = psi->name;
 605
 606         pr_info("Registered %s as persistent store backend\n", psi->name);
 607
 608         module_put(owner);
 609
 610         return 0;
 611 }
 612 EXPORT_SYMBOL_GPL(pstore_register);
 613
 614 void pstore_unregister(struct pstore_info *psi)
 615 {
 616         /* Stop timer and make sure all work has finished. */
 617         pstore_update_ms = -1;
 618         del_timer_sync(&pstore_timer);
 619         flush_work(&pstore_work);
 620
 621         if (psi->flags & PSTORE_FLAGS_PMSG)
 622                 pstore_unregister_pmsg();
 623         if (psi->flags & PSTORE_FLAGS_FTRACE)
 624                 pstore_unregister_ftrace();
 625         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 626                 pstore_unregister_console();
 627         if (psi->flags & PSTORE_FLAGS_DMESG)
 628                 pstore_unregister_kmsg();
 629
 630         free_buf_for_compression();
 631
 632         psinfo = NULL;
 633         backend = NULL;
 634 }
 635 EXPORT_SYMBOL_GPL(pstore_unregister);
 636
 637 static void decompress_record(struct pstore_record *record)
 638 {
 639         int unzipped_len;
 640         char *decompressed;
 641
 642         if (!record->compressed)
 643                 return;
 644
 645         /* Only PSTORE_TYPE_DMESG support compression. */
 646         if (record->type != PSTORE_TYPE_DMESG) {
 647                 pr_warn("ignored compressed record type %d\n", record->type);
 648                 return;
 649         }
 650
 651         /* No compression method has created the common buffer. */
 652         if (!big_oops_buf) {
 653                 pr_warn("no decompression buffer allocated\n");
 654                 return;
 655         }
 656
 657         unzipped_len = pstore_decompress(record->buf, big_oops_buf,
 658                                          record->size, big_oops_buf_sz);
 659         if (unzipped_len <= 0) {
 660                 pr_err("decompression failed: %d\n", unzipped_len);
 661                 return;
 662         }
 663
 664         /* Build new buffer for decompressed contents. */
 665         decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
 666                                GFP_KERNEL);
 667         if (!decompressed) {
 668                 pr_err("decompression ran out of memory\n");
 669                 return;
 670         }
 671         memcpy(decompressed, big_oops_buf, unzipped_len);
 672
 673         /* Append ECC notice to decompressed buffer. */
 674         memcpy(decompressed + unzipped_len, record->buf + record->size,
 675                record->ecc_notice_size);
 676
 677         /* Swap out compresed contents with decompressed contents. */
 678         kfree(record->buf);
 679         record->buf = decompressed;
 680         record->size = unzipped_len;
 681         record->compressed = false;
 682 }
 683
 684 /*
 685  * Read all the records from one persistent store backend. Create
 686  * files in our filesystem.  Don't warn about -EEXIST errors
 687  * when we are re-scanning the backing store looking to add new
 688  * error records.
 689  */
 690 void pstore_get_backend_records(struct pstore_info *psi,
 691                                 struct dentry *root, int quiet)
 692 {
 693         int failed = 0;
 694         unsigned int stop_loop = 65536;
 695
 696         if (!psi || !root)
 697                 return;
 698
 699         mutex_lock(&psi->read_mutex);
 700         if (psi->open && psi->open(psi))
 701                 goto out;
 702
 703         /*
 704          * Backend callback read() allocates record.buf. decompress_record()
 705          * may reallocate record.buf. On success, pstore_mkfile() will keep
 706          * the record.buf, so free it only on failure.
 707          */
 708         for (; stop_loop; stop_loop--) {
 709                 struct pstore_record *record;
 710                 int rc;
 711
 712                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 713                 if (!record) {
 714                         pr_err("out of memory creating record\n");
 715                         break;
 716                 }
 717                 pstore_record_init(record, psi);
 718
 719                 record->size = psi->read(record);
 720
 721                 /* No more records left in backend? */
 722                 if (record->size <= 0) {
 723                         kfree(record);
 724                         break;
 725                 }
 726
 727                 decompress_record(record);
 728                 rc = pstore_mkfile(root, record);
 729                 if (rc) {
 730                         /* pstore_mkfile() did not take record, so free it. */
 731                         kfree(record->buf);
 732                         kfree(record);
 733                         if (rc != -EEXIST || !quiet)
 734                                 failed++;
 735                 }
 736         }
 737         if (psi->close)
 738                 psi->close(psi);
 739 out:
 740         mutex_unlock(&psi->read_mutex);
 741
 742         if (failed)
 743                 pr_warn("failed to create %d record(s) from '%s'\n",
 744                         failed, psi->name);
 745         if (!stop_loop)
 746                 pr_err("looping? Too many records seen from '%s'\n",
 747                         psi->name);
 748 }
 749
 750 static void pstore_dowork(struct work_struct *work)
 751 {
 752         pstore_get_records(1);
 753 }
 754
 755 static void pstore_timefunc(struct timer_list *unused)
 756 {
 757         if (pstore_new_entry) {
 758                 pstore_new_entry = 0;
 759                 schedule_work(&pstore_work);
 760         }
 761
 762         if (pstore_update_ms >= 0)
 763                 mod_timer(&pstore_timer,
 764                           jiffies + msecs_to_jiffies(pstore_update_ms));
 765 }
 766
 767 void __init pstore_choose_compression(void)
 768 {
 769         const struct pstore_zbackend *step;
 770
 771         if (!compress)
 772                 return;
 773
 774         for (step = zbackends; step->name; step++) {
 775                 if (!strcmp(compress, step->name)) {
 776                         zbackend = step;
 777                         pr_info("using %s compression\n", zbackend->name);
 778                         return;
 779                 }
 780         }
 781 }
 782
 783 module_param(compress, charp, 0444);
 784 MODULE_PARM_DESC(compress, "Pstore compression to use");
 785
 786 module_param(backend, charp, 0444);
 787 MODULE_PARM_DESC(backend, "Pstore backend to use");