fs/pstore/platform.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Persistent Storage - platform driver interface parts.
   4  *
   5  * Copyright (C) 2007-2008 Google, Inc.
   6  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   7  */
   8
   9 #define pr_fmt(fmt) "pstore: " fmt
  10
  11 #include <linux/atomic.h>
  12 #include <linux/types.h>
  13 #include <linux/errno.h>
  14 #include <linux/init.h>
  15 #include <linux/kmsg_dump.h>
  16 #include <linux/console.h>
  17 #include <linux/module.h>
  18 #include <linux/pstore.h>
  19 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
  20 #include <linux/lzo.h>
  21 #endif
  22 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
  23 #include <linux/lz4.h>
  24 #endif
  25 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
  26 #include <linux/zstd.h>
  27 #endif
  28 #include <linux/crypto.h>
  29 #include <linux/string.h>
  30 #include <linux/timer.h>
  31 #include <linux/slab.h>
  32 #include <linux/uaccess.h>
  33 #include <linux/jiffies.h>
  34 #include <linux/workqueue.h>
  35
  36 #include "internal.h"
  37
  38 /*
  39  * We defer making "oops" entries appear in pstore - see
  40  * whether the system is actually still running well enough
  41  * to let someone see the entry
  42  */
  43 static int pstore_update_ms = -1;
  44 module_param_named(update_ms, pstore_update_ms, int, 0600);
  45 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
  46                  "(default is -1, which means runtime updates are disabled; "
  47                  "enabling this option is not safe, it may lead to further "
  48                  "corruption on Oopses)");
  49
  50 /* Names should be in the same order as the enum pstore_type_id */
  51 static const char * const pstore_type_names[] = {
  52         "dmesg",
  53         "mce",
  54         "console",
  55         "ftrace",
  56         "rtas",
  57         "powerpc-ofw",
  58         "powerpc-common",
  59         "pmsg",
  60         "powerpc-opal",
  61 };
  62
  63 static int pstore_new_entry;
  64
  65 static void pstore_timefunc(struct timer_list *);
  66 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
  67
  68 static void pstore_dowork(struct work_struct *);
  69 static DECLARE_WORK(pstore_work, pstore_dowork);
  70
  71 /*
  72  * pstore_lock just protects "psinfo" during
  73  * calls to pstore_register()
  74  */
  75 static DEFINE_SPINLOCK(pstore_lock);
  76 struct pstore_info *psinfo;
  77
  78 static char *backend;
  79 static char *compress =
  80 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
  81                 CONFIG_PSTORE_COMPRESS_DEFAULT;
  82 #else
  83                 NULL;
  84 #endif
  85
  86 /* Compression parameters */
  87 static struct crypto_comp *tfm;
  88
  89 struct pstore_zbackend {
  90         int (*zbufsize)(size_t size);
  91         const char *name;
  92 };
  93
  94 static char *big_oops_buf;
  95 static size_t big_oops_buf_sz;
  96
  97 /* How much of the console log to snapshot */
  98 unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
  99
 100 void pstore_set_kmsg_bytes(int bytes)
 101 {
 102         kmsg_bytes = bytes;
 103 }
 104
 105 /* Tag each group of saved records with a sequence number */
 106 static int      oopscount;
 107
 108 const char *pstore_type_to_name(enum pstore_type_id type)
 109 {
 110         BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
 111
 112         if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
 113                 return "unknown";
 114
 115         return pstore_type_names[type];
 116 }
 117 EXPORT_SYMBOL_GPL(pstore_type_to_name);
 118
 119 enum pstore_type_id pstore_name_to_type(const char *name)
 120 {
 121         int i;
 122
 123         for (i = 0; i < PSTORE_TYPE_MAX; i++) {
 124                 if (!strcmp(pstore_type_names[i], name))
 125                         return i;
 126         }
 127
 128         return PSTORE_TYPE_MAX;
 129 }
 130 EXPORT_SYMBOL_GPL(pstore_name_to_type);
 131
 132 static const char *get_reason_str(enum kmsg_dump_reason reason)
 133 {
 134         switch (reason) {
 135         case KMSG_DUMP_PANIC:
 136                 return "Panic";
 137         case KMSG_DUMP_OOPS:
 138                 return "Oops";
 139         case KMSG_DUMP_EMERG:
 140                 return "Emergency";
 141         case KMSG_DUMP_RESTART:
 142                 return "Restart";
 143         case KMSG_DUMP_HALT:
 144                 return "Halt";
 145         case KMSG_DUMP_POWEROFF:
 146                 return "Poweroff";
 147         default:
 148                 return "Unknown";
 149         }
 150 }
 151
 152 /*
 153  * Should pstore_dump() wait for a concurrent pstore_dump()? If
 154  * not, the current pstore_dump() will report a failure to dump
 155  * and return.
 156  */
 157 static bool pstore_cannot_wait(enum kmsg_dump_reason reason)
 158 {
 159         /* In NMI path, pstore shouldn't block regardless of reason. */
 160         if (in_nmi())
 161                 return true;
 162
 163         switch (reason) {
 164         /* In panic case, other cpus are stopped by smp_send_stop(). */
 165         case KMSG_DUMP_PANIC:
 166         /* Emergency restart shouldn't be blocked. */
 167         case KMSG_DUMP_EMERG:
 168                 return true;
 169         default:
 170                 return false;
 171         }
 172 }
 173
 174 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 175 static int zbufsize_deflate(size_t size)
 176 {
 177         size_t cmpr;
 178
 179         switch (size) {
 180         /* buffer range for efivars */
 181         case 1000 ... 2000:
 182                 cmpr = 56;
 183                 break;
 184         case 2001 ... 3000:
 185                 cmpr = 54;
 186                 break;
 187         case 3001 ... 3999:
 188                 cmpr = 52;
 189                 break;
 190         /* buffer range for nvram, erst */
 191         case 4000 ... 10000:
 192                 cmpr = 45;
 193                 break;
 194         default:
 195                 cmpr = 60;
 196                 break;
 197         }
 198
 199         return (size * 100) / cmpr;
 200 }
 201 #endif
 202
 203 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 204 static int zbufsize_lzo(size_t size)
 205 {
 206         return lzo1x_worst_compress(size);
 207 }
 208 #endif
 209
 210 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 211 static int zbufsize_lz4(size_t size)
 212 {
 213         return LZ4_compressBound(size);
 214 }
 215 #endif
 216
 217 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 218 static int zbufsize_842(size_t size)
 219 {
 220         return size;
 221 }
 222 #endif
 223
 224 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 225 static int zbufsize_zstd(size_t size)
 226 {
 227         return ZSTD_compressBound(size);
 228 }
 229 #endif
 230
 231 static const struct pstore_zbackend *zbackend __ro_after_init;
 232
 233 static const struct pstore_zbackend zbackends[] = {
 234 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 235         {
 236                 .zbufsize       = zbufsize_deflate,
 237                 .name           = "deflate",
 238         },
 239 #endif
 240 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 241         {
 242                 .zbufsize       = zbufsize_lzo,
 243                 .name           = "lzo",
 244         },
 245 #endif
 246 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
 247         {
 248                 .zbufsize       = zbufsize_lz4,
 249                 .name           = "lz4",
 250         },
 251 #endif
 252 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 253         {
 254                 .zbufsize       = zbufsize_lz4,
 255                 .name           = "lz4hc",
 256         },
 257 #endif
 258 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 259         {
 260                 .zbufsize       = zbufsize_842,
 261                 .name           = "842",
 262         },
 263 #endif
 264 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 265         {
 266                 .zbufsize       = zbufsize_zstd,
 267                 .name           = "zstd",
 268         },
 269 #endif
 270         { }
 271 };
 272
 273 static int pstore_compress(const void *in, void *out,
 274                            unsigned int inlen, unsigned int outlen)
 275 {
 276         int ret;
 277
 278         ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
 279         if (ret) {
 280                 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
 281                 return ret;
 282         }
 283
 284         return outlen;
 285 }
 286
 287 static void allocate_buf_for_compression(void)
 288 {
 289         struct crypto_comp *ctx;
 290         int size;
 291         char *buf;
 292
 293         /* Skip if not built-in or compression backend not selected yet. */
 294         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
 295                 return;
 296
 297         /* Skip if no pstore backend yet or compression init already done. */
 298         if (!psinfo || tfm)
 299                 return;
 300
 301         if (!crypto_has_comp(zbackend->name, 0, 0)) {
 302                 pr_err("Unknown compression: %s\n", zbackend->name);
 303                 return;
 304         }
 305
 306         size = zbackend->zbufsize(psinfo->bufsize);
 307         if (size <= 0) {
 308                 pr_err("Invalid compression size for %s: %d\n",
 309                        zbackend->name, size);
 310                 return;
 311         }
 312
 313         buf = kmalloc(size, GFP_KERNEL);
 314         if (!buf) {
 315                 pr_err("Failed %d byte compression buffer allocation for: %s\n",
 316                        size, zbackend->name);
 317                 return;
 318         }
 319
 320         ctx = crypto_alloc_comp(zbackend->name, 0, 0);
 321         if (IS_ERR_OR_NULL(ctx)) {
 322                 kfree(buf);
 323                 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
 324                        PTR_ERR(ctx));
 325                 return;
 326         }
 327
 328         /* A non-NULL big_oops_buf indicates compression is available. */
 329         tfm = ctx;
 330         big_oops_buf_sz = size;
 331         big_oops_buf = buf;
 332
 333         pr_info("Using crash dump compression: %s\n", zbackend->name);
 334 }
 335
 336 static void free_buf_for_compression(void)
 337 {
 338         if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
 339                 crypto_free_comp(tfm);
 340                 tfm = NULL;
 341         }
 342         kfree(big_oops_buf);
 343         big_oops_buf = NULL;
 344         big_oops_buf_sz = 0;
 345 }
 346
 347 /*
 348  * Called when compression fails, since the printk buffer
 349  * would be fetched for compression calling it again when
 350  * compression fails would have moved the iterator of
 351  * printk buffer which results in fetching old contents.
 352  * Copy the recent messages from big_oops_buf to psinfo->buf
 353  */
 354 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 355 {
 356         size_t total_len;
 357         size_t diff;
 358
 359         total_len = hsize + len;
 360
 361         if (total_len > psinfo->bufsize) {
 362                 diff = total_len - psinfo->bufsize + hsize;
 363                 memcpy(psinfo->buf, big_oops_buf, hsize);
 364                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 365                                         psinfo->bufsize - hsize);
 366                 total_len = psinfo->bufsize;
 367         } else
 368                 memcpy(psinfo->buf, big_oops_buf, total_len);
 369
 370         return total_len;
 371 }
 372
 373 void pstore_record_init(struct pstore_record *record,
 374                         struct pstore_info *psinfo)
 375 {
 376         memset(record, 0, sizeof(*record));
 377
 378         record->psi = psinfo;
 379
 380         /* Report zeroed timestamp if called before timekeeping has resumed. */
 381         record->time = ns_to_timespec64(ktime_get_real_fast_ns());
 382 }
 383
 384 /*
 385  * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
 386  * end of the buffer.
 387  */
 388 static void pstore_dump(struct kmsg_dumper *dumper,
 389                         enum kmsg_dump_reason reason)
 390 {
 391         unsigned long   total = 0;
 392         const char      *why;
 393         unsigned int    part = 1;
 394         int             ret;
 395
 396         why = get_reason_str(reason);
 397
 398         if (down_trylock(&psinfo->buf_lock)) {
 399                 /* Failed to acquire lock: give up if we cannot wait. */
 400                 if (pstore_cannot_wait(reason)) {
 401                         pr_err("dump skipped in %s path: may corrupt error record\n",
 402                                 in_nmi() ? "NMI" : why);
 403                         return;
 404                 }
 405                 if (down_interruptible(&psinfo->buf_lock)) {
 406                         pr_err("could not grab semaphore?!\n");
 407                         return;
 408                 }
 409         }
 410
 411         oopscount++;
 412         while (total < kmsg_bytes) {
 413                 char *dst;
 414                 size_t dst_size;
 415                 int header_size;
 416                 int zipped_len = -1;
 417                 size_t dump_size;
 418                 struct pstore_record record;
 419
 420                 pstore_record_init(&record, psinfo);
 421                 record.type = PSTORE_TYPE_DMESG;
 422                 record.count = oopscount;
 423                 record.reason = reason;
 424                 record.part = part;
 425                 record.buf = psinfo->buf;
 426
 427                 if (big_oops_buf) {
 428                         dst = big_oops_buf;
 429                         dst_size = big_oops_buf_sz;
 430                 } else {
 431                         dst = psinfo->buf;
 432                         dst_size = psinfo->bufsize;
 433                 }
 434
 435                 /* Write dump header. */
 436                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 437                                  oopscount, part);
 438                 dst_size -= header_size;
 439
 440                 /* Write dump contents. */
 441                 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
 442                                           dst_size, &dump_size))
 443                         break;
 444
 445                 if (big_oops_buf) {
 446                         zipped_len = pstore_compress(dst, psinfo->buf,
 447                                                 header_size + dump_size,
 448                                                 psinfo->bufsize);
 449
 450                         if (zipped_len > 0) {
 451                                 record.compressed = true;
 452                                 record.size = zipped_len;
 453                         } else {
 454                                 record.size = copy_kmsg_to_buffer(header_size,
 455                                                                   dump_size);
 456                         }
 457                 } else {
 458                         record.size = header_size + dump_size;
 459                 }
 460
 461                 ret = psinfo->write(&record);
 462                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 463                         pstore_new_entry = 1;
 464
 465                 total += record.size;
 466                 part++;
 467         }
 468
 469         up(&psinfo->buf_lock);
 470 }
 471
 472 static struct kmsg_dumper pstore_dumper = {
 473         .dump = pstore_dump,
 474 };
 475
 476 /*
 477  * Register with kmsg_dump to save last part of console log on panic.
 478  */
 479 static void pstore_register_kmsg(void)
 480 {
 481         kmsg_dump_register(&pstore_dumper);
 482 }
 483
 484 static void pstore_unregister_kmsg(void)
 485 {
 486         kmsg_dump_unregister(&pstore_dumper);
 487 }
 488
 489 #ifdef CONFIG_PSTORE_CONSOLE
 490 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 491 {
 492         struct pstore_record record;
 493
 494         if (!c)
 495                 return;
 496
 497         pstore_record_init(&record, psinfo);
 498         record.type = PSTORE_TYPE_CONSOLE;
 499
 500         record.buf = (char *)s;
 501         record.size = c;
 502         psinfo->write(&record);
 503 }
 504
 505 static struct console pstore_console = {
 506         .name   = "pstore",
 507         .write  = pstore_console_write,
 508         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 509         .index  = -1,
 510 };
 511
 512 static void pstore_register_console(void)
 513 {
 514         register_console(&pstore_console);
 515 }
 516
 517 static void pstore_unregister_console(void)
 518 {
 519         unregister_console(&pstore_console);
 520 }
 521 #else
 522 static void pstore_register_console(void) {}
 523 static void pstore_unregister_console(void) {}
 524 #endif
 525
 526 static int pstore_write_user_compat(struct pstore_record *record,
 527                                     const char __user *buf)
 528 {
 529         int ret = 0;
 530
 531         if (record->buf)
 532                 return -EINVAL;
 533
 534         record->buf = memdup_user(buf, record->size);
 535         if (IS_ERR(record->buf)) {
 536                 ret = PTR_ERR(record->buf);
 537                 goto out;
 538         }
 539
 540         ret = record->psi->write(record);
 541
 542         kfree(record->buf);
 543 out:
 544         record->buf = NULL;
 545
 546         return unlikely(ret < 0) ? ret : record->size;
 547 }
 548
 549 /*
 550  * platform specific persistent storage driver registers with
 551  * us here. If pstore is already mounted, call the platform
 552  * read function right away to populate the file system. If not
 553  * then the pstore mount code will call us later to fill out
 554  * the file system.
 555  */
 556 int pstore_register(struct pstore_info *psi)
 557 {
 558         if (backend && strcmp(backend, psi->name)) {
 559                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 560                 return -EPERM;
 561         }
 562
 563         /* Sanity check flags. */
 564         if (!psi->flags) {
 565                 pr_warn("backend '%s' must support at least one frontend\n",
 566                         psi->name);
 567                 return -EINVAL;
 568         }
 569
 570         /* Check for required functions. */
 571         if (!psi->read || !psi->write) {
 572                 pr_warn("backend '%s' must implement read() and write()\n",
 573                         psi->name);
 574                 return -EINVAL;
 575         }
 576
 577         spin_lock(&pstore_lock);
 578         if (psinfo) {
 579                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 580                         psinfo->name, psi->name);
 581                 spin_unlock(&pstore_lock);
 582                 return -EBUSY;
 583         }
 584
 585         if (!psi->write_user)
 586                 psi->write_user = pstore_write_user_compat;
 587         psinfo = psi;
 588         mutex_init(&psinfo->read_mutex);
 589         sema_init(&psinfo->buf_lock, 1);
 590         spin_unlock(&pstore_lock);
 591
 592
 593         if (psi->flags & PSTORE_FLAGS_DMESG)
 594                 allocate_buf_for_compression();
 595
 596         if (pstore_is_mounted())
 597                 pstore_get_records(0);
 598
 599         if (psi->flags & PSTORE_FLAGS_DMESG)
 600                 pstore_register_kmsg();
 601         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 602                 pstore_register_console();
 603         if (psi->flags & PSTORE_FLAGS_FTRACE)
 604                 pstore_register_ftrace();
 605         if (psi->flags & PSTORE_FLAGS_PMSG)
 606                 pstore_register_pmsg();
 607
 608         /* Start watching for new records, if desired. */
 609         if (pstore_update_ms >= 0) {
 610                 pstore_timer.expires = jiffies +
 611                         msecs_to_jiffies(pstore_update_ms);
 612                 add_timer(&pstore_timer);
 613         }
 614
 615         /*
 616          * Update the module parameter backend, so it is visible
 617          * through /sys/module/pstore/parameters/backend
 618          */
 619         backend = psi->name;
 620
 621         pr_info("Registered %s as persistent store backend\n", psi->name);
 622
 623         return 0;
 624 }
 625 EXPORT_SYMBOL_GPL(pstore_register);
 626
 627 void pstore_unregister(struct pstore_info *psi)
 628 {
 629         /* Stop timer and make sure all work has finished. */
 630         pstore_update_ms = -1;
 631         del_timer_sync(&pstore_timer);
 632         flush_work(&pstore_work);
 633
 634         if (psi->flags & PSTORE_FLAGS_PMSG)
 635                 pstore_unregister_pmsg();
 636         if (psi->flags & PSTORE_FLAGS_FTRACE)
 637                 pstore_unregister_ftrace();
 638         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 639                 pstore_unregister_console();
 640         if (psi->flags & PSTORE_FLAGS_DMESG)
 641                 pstore_unregister_kmsg();
 642
 643         free_buf_for_compression();
 644
 645         psinfo = NULL;
 646         backend = NULL;
 647 }
 648 EXPORT_SYMBOL_GPL(pstore_unregister);
 649
 650 static void decompress_record(struct pstore_record *record)
 651 {
 652         int ret;
 653         int unzipped_len;
 654         char *unzipped, *workspace;
 655
 656         if (!record->compressed)
 657                 return;
 658
 659         /* Only PSTORE_TYPE_DMESG support compression. */
 660         if (record->type != PSTORE_TYPE_DMESG) {
 661                 pr_warn("ignored compressed record type %d\n", record->type);
 662                 return;
 663         }
 664
 665         /* Missing compression buffer means compression was not initialized. */
 666         if (!big_oops_buf) {
 667                 pr_warn("no decompression method initialized!\n");
 668                 return;
 669         }
 670
 671         /* Allocate enough space to hold max decompression and ECC. */
 672         unzipped_len = big_oops_buf_sz;
 673         workspace = kmalloc(unzipped_len + record->ecc_notice_size,
 674                             GFP_KERNEL);
 675         if (!workspace)
 676                 return;
 677
 678         /* After decompression "unzipped_len" is almost certainly smaller. */
 679         ret = crypto_comp_decompress(tfm, record->buf, record->size,
 680                                           workspace, &unzipped_len);
 681         if (ret) {
 682                 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
 683                 kfree(workspace);
 684                 return;
 685         }
 686
 687         /* Append ECC notice to decompressed buffer. */
 688         memcpy(workspace + unzipped_len, record->buf + record->size,
 689                record->ecc_notice_size);
 690
 691         /* Copy decompressed contents into an minimum-sized allocation. */
 692         unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
 693                            GFP_KERNEL);
 694         kfree(workspace);
 695         if (!unzipped)
 696                 return;
 697
 698         /* Swap out compressed contents with decompressed contents. */
 699         kfree(record->buf);
 700         record->buf = unzipped;
 701         record->size = unzipped_len;
 702         record->compressed = false;
 703 }
 704
 705 /*
 706  * Read all the records from one persistent store backend. Create
 707  * files in our filesystem.  Don't warn about -EEXIST errors
 708  * when we are re-scanning the backing store looking to add new
 709  * error records.
 710  */
 711 void pstore_get_backend_records(struct pstore_info *psi,
 712                                 struct dentry *root, int quiet)
 713 {
 714         int failed = 0;
 715         unsigned int stop_loop = 65536;
 716
 717         if (!psi || !root)
 718                 return;
 719
 720         mutex_lock(&psi->read_mutex);
 721         if (psi->open && psi->open(psi))
 722                 goto out;
 723
 724         /*
 725          * Backend callback read() allocates record.buf. decompress_record()
 726          * may reallocate record.buf. On success, pstore_mkfile() will keep
 727          * the record.buf, so free it only on failure.
 728          */
 729         for (; stop_loop; stop_loop--) {
 730                 struct pstore_record *record;
 731                 int rc;
 732
 733                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 734                 if (!record) {
 735                         pr_err("out of memory creating record\n");
 736                         break;
 737                 }
 738                 pstore_record_init(record, psi);
 739
 740                 record->size = psi->read(record);
 741
 742                 /* No more records left in backend? */
 743                 if (record->size <= 0) {
 744                         kfree(record);
 745                         break;
 746                 }
 747
 748                 decompress_record(record);
 749                 rc = pstore_mkfile(root, record);
 750                 if (rc) {
 751                         /* pstore_mkfile() did not take record, so free it. */
 752                         kfree(record->buf);
 753                         kfree(record);
 754                         if (rc != -EEXIST || !quiet)
 755                                 failed++;
 756                 }
 757         }
 758         if (psi->close)
 759                 psi->close(psi);
 760 out:
 761         mutex_unlock(&psi->read_mutex);
 762
 763         if (failed)
 764                 pr_warn("failed to create %d record(s) from '%s'\n",
 765                         failed, psi->name);
 766         if (!stop_loop)
 767                 pr_err("looping? Too many records seen from '%s'\n",
 768                         psi->name);
 769 }
 770
 771 static void pstore_dowork(struct work_struct *work)
 772 {
 773         pstore_get_records(1);
 774 }
 775
 776 static void pstore_timefunc(struct timer_list *unused)
 777 {
 778         if (pstore_new_entry) {
 779                 pstore_new_entry = 0;
 780                 schedule_work(&pstore_work);
 781         }
 782
 783         if (pstore_update_ms >= 0)
 784                 mod_timer(&pstore_timer,
 785                           jiffies + msecs_to_jiffies(pstore_update_ms));
 786 }
 787
 788 static void __init pstore_choose_compression(void)
 789 {
 790         const struct pstore_zbackend *step;
 791
 792         if (!compress)
 793                 return;
 794
 795         for (step = zbackends; step->name; step++) {
 796                 if (!strcmp(compress, step->name)) {
 797                         zbackend = step;
 798                         return;
 799                 }
 800         }
 801 }
 802
 803 static int __init pstore_init(void)
 804 {
 805         int ret;
 806
 807         pstore_choose_compression();
 808
 809         /*
 810          * Check if any pstore backends registered earlier but did not
 811          * initialize compression because crypto was not ready. If so,
 812          * initialize compression now.
 813          */
 814         allocate_buf_for_compression();
 815
 816         ret = pstore_init_fs();
 817         if (ret)
 818                 free_buf_for_compression();
 819
 820         return ret;
 821 }
 822 late_initcall(pstore_init);
 823
 824 static void __exit pstore_exit(void)
 825 {
 826         pstore_exit_fs();
 827 }
 828 module_exit(pstore_exit)
 829
 830 module_param(compress, charp, 0444);
 831 MODULE_PARM_DESC(compress, "Pstore compression to use");
 832
 833 module_param(backend, charp, 0444);
 834 MODULE_PARM_DESC(backend, "Pstore backend to use");
 835
 836 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 837 MODULE_LICENSE("GPL");