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         struct crypto_comp *ctx;
 278         int size;
 279         char *buf;
 280
 281         /* Skip if not built-in or compression backend not selected yet. */
 282         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
 283                 return;
 284
 285         /* Skip if no pstore backend yet or compression init already done. */
 286         if (!psinfo || tfm)
 287                 return;
 288
 289         if (!crypto_has_comp(zbackend->name, 0, 0)) {
 290                 pr_err("Unknown compression: %s\n", zbackend->name);
 291                 return;
 292         }
 293
 294         size = zbackend->zbufsize(psinfo->bufsize);
 295         if (size <= 0) {
 296                 pr_err("Invalid compression size for %s: %d\n",
 297                        zbackend->name, size);
 298                 return;
 299         }
 300
 301         buf = kmalloc(size, GFP_KERNEL);
 302         if (!buf) {
 303                 pr_err("Failed %d byte compression buffer allocation for: %s\n",
 304                        size, zbackend->name);
 305                 return;
 306         }
 307
 308         ctx = crypto_alloc_comp(zbackend->name, 0, 0);
 309         if (IS_ERR_OR_NULL(ctx)) {
 310                 kfree(buf);
 311                 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
 312                        PTR_ERR(ctx));
 313                 return;
 314         }
 315
 316         /* A non-NULL big_oops_buf indicates compression is available. */
 317         tfm = ctx;
 318         big_oops_buf_sz = size;
 319         big_oops_buf = buf;
 320
 321         pr_info("Using compression: %s\n", zbackend->name);
 322 }
 323
 324 static void free_buf_for_compression(void)
 325 {
 326         if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm)
 327                 crypto_free_comp(tfm);
 328         kfree(big_oops_buf);
 329         big_oops_buf = NULL;
 330         big_oops_buf_sz = 0;
 331 }
 332
 333 /*
 334  * Called when compression fails, since the printk buffer
 335  * would be fetched for compression calling it again when
 336  * compression fails would have moved the iterator of
 337  * printk buffer which results in fetching old contents.
 338  * Copy the recent messages from big_oops_buf to psinfo->buf
 339  */
 340 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 341 {
 342         size_t total_len;
 343         size_t diff;
 344
 345         total_len = hsize + len;
 346
 347         if (total_len > psinfo->bufsize) {
 348                 diff = total_len - psinfo->bufsize + hsize;
 349                 memcpy(psinfo->buf, big_oops_buf, hsize);
 350                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 351                                         psinfo->bufsize - hsize);
 352                 total_len = psinfo->bufsize;
 353         } else
 354                 memcpy(psinfo->buf, big_oops_buf, total_len);
 355
 356         return total_len;
 357 }
 358
 359 void pstore_record_init(struct pstore_record *record,
 360                         struct pstore_info *psinfo)
 361 {
 362         memset(record, 0, sizeof(*record));
 363
 364         record->psi = psinfo;
 365
 366         /* Report zeroed timestamp if called before timekeeping has resumed. */
 367         record->time = ns_to_timespec64(ktime_get_real_fast_ns());
 368 }
 369
 370 /*
 371  * callback from kmsg_dump. (s2,l2) has the most recently
 372  * written bytes, older bytes are in (s1,l1). Save as much
 373  * as we can from the end of the buffer.
 374  */
 375 static void pstore_dump(struct kmsg_dumper *dumper,
 376                         enum kmsg_dump_reason reason)
 377 {
 378         unsigned long   total = 0;
 379         const char      *why;
 380         unsigned int    part = 1;
 381         unsigned long   flags = 0;
 382         int             is_locked;
 383         int             ret;
 384
 385         why = get_reason_str(reason);
 386
 387         if (pstore_cannot_block_path(reason)) {
 388                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 389                 if (!is_locked) {
 390                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 391                                        , in_nmi() ? "NMI" : why);
 392                         return;
 393                 }
 394         } else {
 395                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 396                 is_locked = 1;
 397         }
 398         oopscount++;
 399         while (total < kmsg_bytes) {
 400                 char *dst;
 401                 size_t dst_size;
 402                 int header_size;
 403                 int zipped_len = -1;
 404                 size_t dump_size;
 405                 struct pstore_record record;
 406
 407                 pstore_record_init(&record, psinfo);
 408                 record.type = PSTORE_TYPE_DMESG;
 409                 record.count = oopscount;
 410                 record.reason = reason;
 411                 record.part = part;
 412                 record.buf = psinfo->buf;
 413
 414                 if (big_oops_buf && is_locked) {
 415                         dst = big_oops_buf;
 416                         dst_size = big_oops_buf_sz;
 417                 } else {
 418                         dst = psinfo->buf;
 419                         dst_size = psinfo->bufsize;
 420                 }
 421
 422                 /* Write dump header. */
 423                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 424                                  oopscount, part);
 425                 dst_size -= header_size;
 426
 427                 /* Write dump contents. */
 428                 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
 429                                           dst_size, &dump_size))
 430                         break;
 431
 432                 if (big_oops_buf && is_locked) {
 433                         zipped_len = pstore_compress(dst, psinfo->buf,
 434                                                 header_size + dump_size,
 435                                                 psinfo->bufsize);
 436
 437                         if (zipped_len > 0) {
 438                                 record.compressed = true;
 439                                 record.size = zipped_len;
 440                         } else {
 441                                 record.size = copy_kmsg_to_buffer(header_size,
 442                                                                   dump_size);
 443                         }
 444                 } else {
 445                         record.size = header_size + dump_size;
 446                 }
 447
 448                 ret = psinfo->write(&record);
 449                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 450                         pstore_new_entry = 1;
 451
 452                 total += record.size;
 453                 part++;
 454         }
 455         if (is_locked)
 456                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 457 }
 458
 459 static struct kmsg_dumper pstore_dumper = {
 460         .dump = pstore_dump,
 461 };
 462
 463 /*
 464  * Register with kmsg_dump to save last part of console log on panic.
 465  */
 466 static void pstore_register_kmsg(void)
 467 {
 468         kmsg_dump_register(&pstore_dumper);
 469 }
 470
 471 static void pstore_unregister_kmsg(void)
 472 {
 473         kmsg_dump_unregister(&pstore_dumper);
 474 }
 475
 476 #ifdef CONFIG_PSTORE_CONSOLE
 477 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 478 {
 479         const char *e = s + c;
 480
 481         while (s < e) {
 482                 struct pstore_record record;
 483                 unsigned long flags;
 484
 485                 pstore_record_init(&record, psinfo);
 486                 record.type = PSTORE_TYPE_CONSOLE;
 487
 488                 if (c > psinfo->bufsize)
 489                         c = psinfo->bufsize;
 490
 491                 if (oops_in_progress) {
 492                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 493                                 break;
 494                 } else {
 495                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 496                 }
 497                 record.buf = (char *)s;
 498                 record.size = c;
 499                 psinfo->write(&record);
 500                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 501                 s += c;
 502                 c = e - s;
 503         }
 504 }
 505
 506 static struct console pstore_console = {
 507         .name   = "pstore",
 508         .write  = pstore_console_write,
 509         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 510         .index  = -1,
 511 };
 512
 513 static void pstore_register_console(void)
 514 {
 515         register_console(&pstore_console);
 516 }
 517
 518 static void pstore_unregister_console(void)
 519 {
 520         unregister_console(&pstore_console);
 521 }
 522 #else
 523 static void pstore_register_console(void) {}
 524 static void pstore_unregister_console(void) {}
 525 #endif
 526
 527 static int pstore_write_user_compat(struct pstore_record *record,
 528                                     const char __user *buf)
 529 {
 530         int ret = 0;
 531
 532         if (record->buf)
 533                 return -EINVAL;
 534
 535         record->buf = memdup_user(buf, record->size);
 536         if (IS_ERR(record->buf)) {
 537                 ret = PTR_ERR(record->buf);
 538                 goto out;
 539         }
 540
 541         ret = record->psi->write(record);
 542
 543         kfree(record->buf);
 544 out:
 545         record->buf = NULL;
 546
 547         return unlikely(ret < 0) ? ret : record->size;
 548 }
 549
 550 /*
 551  * platform specific persistent storage driver registers with
 552  * us here. If pstore is already mounted, call the platform
 553  * read function right away to populate the file system. If not
 554  * then the pstore mount code will call us later to fill out
 555  * the file system.
 556  */
 557 int pstore_register(struct pstore_info *psi)
 558 {
 559         struct module *owner = psi->owner;
 560
 561         if (backend && strcmp(backend, psi->name)) {
 562                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 563                 return -EPERM;
 564         }
 565
 566         /* Sanity check flags. */
 567         if (!psi->flags) {
 568                 pr_warn("backend '%s' must support at least one frontend\n",
 569                         psi->name);
 570                 return -EINVAL;
 571         }
 572
 573         /* Check for required functions. */
 574         if (!psi->read || !psi->write) {
 575                 pr_warn("backend '%s' must implement read() and write()\n",
 576                         psi->name);
 577                 return -EINVAL;
 578         }
 579
 580         spin_lock(&pstore_lock);
 581         if (psinfo) {
 582                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 583                         psinfo->name, psi->name);
 584                 spin_unlock(&pstore_lock);
 585                 return -EBUSY;
 586         }
 587
 588         if (!psi->write_user)
 589                 psi->write_user = pstore_write_user_compat;
 590         psinfo = psi;
 591         mutex_init(&psinfo->read_mutex);
 592         spin_unlock(&pstore_lock);
 593
 594         if (owner && !try_module_get(owner)) {
 595                 psinfo = NULL;
 596                 return -EINVAL;
 597         }
 598
 599         allocate_buf_for_compression();
 600
 601         if (pstore_is_mounted())
 602                 pstore_get_records(0);
 603
 604         if (psi->flags & PSTORE_FLAGS_DMESG)
 605                 pstore_register_kmsg();
 606         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 607                 pstore_register_console();
 608         if (psi->flags & PSTORE_FLAGS_FTRACE)
 609                 pstore_register_ftrace();
 610         if (psi->flags & PSTORE_FLAGS_PMSG)
 611                 pstore_register_pmsg();
 612
 613         /* Start watching for new records, if desired. */
 614         if (pstore_update_ms >= 0) {
 615                 pstore_timer.expires = jiffies +
 616                         msecs_to_jiffies(pstore_update_ms);
 617                 add_timer(&pstore_timer);
 618         }
 619
 620         /*
 621          * Update the module parameter backend, so it is visible
 622          * through /sys/module/pstore/parameters/backend
 623          */
 624         backend = psi->name;
 625
 626         pr_info("Registered %s as persistent store backend\n", psi->name);
 627
 628         module_put(owner);
 629
 630         return 0;
 631 }
 632 EXPORT_SYMBOL_GPL(pstore_register);
 633
 634 void pstore_unregister(struct pstore_info *psi)
 635 {
 636         /* Stop timer and make sure all work has finished. */
 637         pstore_update_ms = -1;
 638         del_timer_sync(&pstore_timer);
 639         flush_work(&pstore_work);
 640
 641         if (psi->flags & PSTORE_FLAGS_PMSG)
 642                 pstore_unregister_pmsg();
 643         if (psi->flags & PSTORE_FLAGS_FTRACE)
 644                 pstore_unregister_ftrace();
 645         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 646                 pstore_unregister_console();
 647         if (psi->flags & PSTORE_FLAGS_DMESG)
 648                 pstore_unregister_kmsg();
 649
 650         free_buf_for_compression();
 651
 652         psinfo = NULL;
 653         backend = NULL;
 654 }
 655 EXPORT_SYMBOL_GPL(pstore_unregister);
 656
 657 static void decompress_record(struct pstore_record *record)
 658 {
 659         int unzipped_len;
 660         char *decompressed;
 661
 662         if (!record->compressed)
 663                 return;
 664
 665         /* Only PSTORE_TYPE_DMESG support compression. */
 666         if (record->type != PSTORE_TYPE_DMESG) {
 667                 pr_warn("ignored compressed record type %d\n", record->type);
 668                 return;
 669         }
 670
 671         /* No compression method has created the common buffer. */
 672         if (!big_oops_buf) {
 673                 pr_warn("no decompression buffer allocated\n");
 674                 return;
 675         }
 676
 677         unzipped_len = pstore_decompress(record->buf, big_oops_buf,
 678                                          record->size, big_oops_buf_sz);
 679         if (unzipped_len <= 0) {
 680                 pr_err("decompression failed: %d\n", unzipped_len);
 681                 return;
 682         }
 683
 684         /* Build new buffer for decompressed contents. */
 685         decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
 686                                GFP_KERNEL);
 687         if (!decompressed) {
 688                 pr_err("decompression ran out of memory\n");
 689                 return;
 690         }
 691         memcpy(decompressed, big_oops_buf, unzipped_len);
 692
 693         /* Append ECC notice to decompressed buffer. */
 694         memcpy(decompressed + unzipped_len, record->buf + record->size,
 695                record->ecc_notice_size);
 696
 697         /* Swap out compresed contents with decompressed contents. */
 698         kfree(record->buf);
 699         record->buf = decompressed;
 700         record->size = unzipped_len;
 701         record->compressed = false;
 702 }
 703
 704 /*
 705  * Read all the records from one persistent store backend. Create
 706  * files in our filesystem.  Don't warn about -EEXIST errors
 707  * when we are re-scanning the backing store looking to add new
 708  * error records.
 709  */
 710 void pstore_get_backend_records(struct pstore_info *psi,
 711                                 struct dentry *root, int quiet)
 712 {
 713         int failed = 0;
 714         unsigned int stop_loop = 65536;
 715
 716         if (!psi || !root)
 717                 return;
 718
 719         mutex_lock(&psi->read_mutex);
 720         if (psi->open && psi->open(psi))
 721                 goto out;
 722
 723         /*
 724          * Backend callback read() allocates record.buf. decompress_record()
 725          * may reallocate record.buf. On success, pstore_mkfile() will keep
 726          * the record.buf, so free it only on failure.
 727          */
 728         for (; stop_loop; stop_loop--) {
 729                 struct pstore_record *record;
 730                 int rc;
 731
 732                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 733                 if (!record) {
 734                         pr_err("out of memory creating record\n");
 735                         break;
 736                 }
 737                 pstore_record_init(record, psi);
 738
 739                 record->size = psi->read(record);
 740
 741                 /* No more records left in backend? */
 742                 if (record->size <= 0) {
 743                         kfree(record);
 744                         break;
 745                 }
 746
 747                 decompress_record(record);
 748                 rc = pstore_mkfile(root, record);
 749                 if (rc) {
 750                         /* pstore_mkfile() did not take record, so free it. */
 751                         kfree(record->buf);
 752                         kfree(record);
 753                         if (rc != -EEXIST || !quiet)
 754                                 failed++;
 755                 }
 756         }
 757         if (psi->close)
 758                 psi->close(psi);
 759 out:
 760         mutex_unlock(&psi->read_mutex);
 761
 762         if (failed)
 763                 pr_warn("failed to create %d record(s) from '%s'\n",
 764                         failed, psi->name);
 765         if (!stop_loop)
 766                 pr_err("looping? Too many records seen from '%s'\n",
 767                         psi->name);
 768 }
 769
 770 static void pstore_dowork(struct work_struct *work)
 771 {
 772         pstore_get_records(1);
 773 }
 774
 775 static void pstore_timefunc(struct timer_list *unused)
 776 {
 777         if (pstore_new_entry) {
 778                 pstore_new_entry = 0;
 779                 schedule_work(&pstore_work);
 780         }
 781
 782         if (pstore_update_ms >= 0)
 783                 mod_timer(&pstore_timer,
 784                           jiffies + msecs_to_jiffies(pstore_update_ms));
 785 }
 786
 787 void __init pstore_choose_compression(void)
 788 {
 789         const struct pstore_zbackend *step;
 790
 791         if (!compress)
 792                 return;
 793
 794         for (step = zbackends; step->name; step++) {
 795                 if (!strcmp(compress, step->name)) {
 796                         zbackend = step;
 797                         return;
 798                 }
 799         }
 800 }
 801
 802 static int __init pstore_init(void)
 803 {
 804         int ret;
 805
 806         pstore_choose_compression();
 807
 808         /*
 809          * Check if any pstore backends registered earlier but did not
 810          * initialize compression because crypto was not ready. If so,
 811          * initialize compression now.
 812          */
 813         allocate_buf_for_compression();
 814
 815         ret = pstore_init_fs();
 816         if (ret)
 817                 return ret;
 818
 819         return 0;
 820 }
 821 late_initcall(pstore_init);
 822
 823 static void __exit pstore_exit(void)
 824 {
 825         pstore_exit_fs();
 826 }
 827 module_exit(pstore_exit)
 828
 829 module_param(compress, charp, 0444);
 830 MODULE_PARM_DESC(compress, "Pstore compression to use");
 831
 832 module_param(backend, charp, 0444);
 833 MODULE_PARM_DESC(backend, "Pstore backend to use");
 834
 835 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 836 MODULE_LICENSE("GPL");