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         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
 279                 return -EINVAL;
 280
 281         ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
 282         if (ret) {
 283                 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
 284                 return ret;
 285         }
 286
 287         return outlen;
 288 }
 289
 290 static void allocate_buf_for_compression(void)
 291 {
 292         struct crypto_comp *ctx;
 293         int size;
 294         char *buf;
 295
 296         /* Skip if not built-in or compression backend not selected yet. */
 297         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
 298                 return;
 299
 300         /* Skip if no pstore backend yet or compression init already done. */
 301         if (!psinfo || tfm)
 302                 return;
 303
 304         if (!crypto_has_comp(zbackend->name, 0, 0)) {
 305                 pr_err("Unknown compression: %s\n", zbackend->name);
 306                 return;
 307         }
 308
 309         size = zbackend->zbufsize(psinfo->bufsize);
 310         if (size <= 0) {
 311                 pr_err("Invalid compression size for %s: %d\n",
 312                        zbackend->name, size);
 313                 return;
 314         }
 315
 316         buf = kmalloc(size, GFP_KERNEL);
 317         if (!buf) {
 318                 pr_err("Failed %d byte compression buffer allocation for: %s\n",
 319                        size, zbackend->name);
 320                 return;
 321         }
 322
 323         ctx = crypto_alloc_comp(zbackend->name, 0, 0);
 324         if (IS_ERR_OR_NULL(ctx)) {
 325                 kfree(buf);
 326                 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
 327                        PTR_ERR(ctx));
 328                 return;
 329         }
 330
 331         /* A non-NULL big_oops_buf indicates compression is available. */
 332         tfm = ctx;
 333         big_oops_buf_sz = size;
 334         big_oops_buf = buf;
 335
 336         pr_info("Using crash dump compression: %s\n", zbackend->name);
 337 }
 338
 339 static void free_buf_for_compression(void)
 340 {
 341         if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
 342                 crypto_free_comp(tfm);
 343                 tfm = NULL;
 344         }
 345         kfree(big_oops_buf);
 346         big_oops_buf = NULL;
 347         big_oops_buf_sz = 0;
 348 }
 349
 350 /*
 351  * Called when compression fails, since the printk buffer
 352  * would be fetched for compression calling it again when
 353  * compression fails would have moved the iterator of
 354  * printk buffer which results in fetching old contents.
 355  * Copy the recent messages from big_oops_buf to psinfo->buf
 356  */
 357 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 358 {
 359         size_t total_len;
 360         size_t diff;
 361
 362         total_len = hsize + len;
 363
 364         if (total_len > psinfo->bufsize) {
 365                 diff = total_len - psinfo->bufsize + hsize;
 366                 memcpy(psinfo->buf, big_oops_buf, hsize);
 367                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 368                                         psinfo->bufsize - hsize);
 369                 total_len = psinfo->bufsize;
 370         } else
 371                 memcpy(psinfo->buf, big_oops_buf, total_len);
 372
 373         return total_len;
 374 }
 375
 376 void pstore_record_init(struct pstore_record *record,
 377                         struct pstore_info *psinfo)
 378 {
 379         memset(record, 0, sizeof(*record));
 380
 381         record->psi = psinfo;
 382
 383         /* Report zeroed timestamp if called before timekeeping has resumed. */
 384         record->time = ns_to_timespec64(ktime_get_real_fast_ns());
 385 }
 386
 387 /*
 388  * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
 389  * end of the buffer.
 390  */
 391 static void pstore_dump(struct kmsg_dumper *dumper,
 392                         enum kmsg_dump_reason reason)
 393 {
 394         unsigned long   total = 0;
 395         const char      *why;
 396         unsigned int    part = 1;
 397         int             ret;
 398
 399         why = get_reason_str(reason);
 400
 401         if (down_trylock(&psinfo->buf_lock)) {
 402                 /* Failed to acquire lock: give up if we cannot wait. */
 403                 if (pstore_cannot_wait(reason)) {
 404                         pr_err("dump skipped in %s path: may corrupt error record\n",
 405                                 in_nmi() ? "NMI" : why);
 406                         return;
 407                 }
 408                 if (down_interruptible(&psinfo->buf_lock)) {
 409                         pr_err("could not grab semaphore?!\n");
 410                         return;
 411                 }
 412         }
 413
 414         oopscount++;
 415         while (total < kmsg_bytes) {
 416                 char *dst;
 417                 size_t dst_size;
 418                 int header_size;
 419                 int zipped_len = -1;
 420                 size_t dump_size;
 421                 struct pstore_record record;
 422
 423                 pstore_record_init(&record, psinfo);
 424                 record.type = PSTORE_TYPE_DMESG;
 425                 record.count = oopscount;
 426                 record.reason = reason;
 427                 record.part = part;
 428                 record.buf = psinfo->buf;
 429
 430                 if (big_oops_buf) {
 431                         dst = big_oops_buf;
 432                         dst_size = big_oops_buf_sz;
 433                 } else {
 434                         dst = psinfo->buf;
 435                         dst_size = psinfo->bufsize;
 436                 }
 437
 438                 /* Write dump header. */
 439                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 440                                  oopscount, part);
 441                 dst_size -= header_size;
 442
 443                 /* Write dump contents. */
 444                 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
 445                                           dst_size, &dump_size))
 446                         break;
 447
 448                 if (big_oops_buf) {
 449                         zipped_len = pstore_compress(dst, psinfo->buf,
 450                                                 header_size + dump_size,
 451                                                 psinfo->bufsize);
 452
 453                         if (zipped_len > 0) {
 454                                 record.compressed = true;
 455                                 record.size = zipped_len;
 456                         } else {
 457                                 record.size = copy_kmsg_to_buffer(header_size,
 458                                                                   dump_size);
 459                         }
 460                 } else {
 461                         record.size = header_size + dump_size;
 462                 }
 463
 464                 ret = psinfo->write(&record);
 465                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 466                         pstore_new_entry = 1;
 467
 468                 total += record.size;
 469                 part++;
 470         }
 471
 472         up(&psinfo->buf_lock);
 473 }
 474
 475 static struct kmsg_dumper pstore_dumper = {
 476         .dump = pstore_dump,
 477 };
 478
 479 /*
 480  * Register with kmsg_dump to save last part of console log on panic.
 481  */
 482 static void pstore_register_kmsg(void)
 483 {
 484         kmsg_dump_register(&pstore_dumper);
 485 }
 486
 487 static void pstore_unregister_kmsg(void)
 488 {
 489         kmsg_dump_unregister(&pstore_dumper);
 490 }
 491
 492 #ifdef CONFIG_PSTORE_CONSOLE
 493 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 494 {
 495         struct pstore_record record;
 496
 497         if (!c)
 498                 return;
 499
 500         pstore_record_init(&record, psinfo);
 501         record.type = PSTORE_TYPE_CONSOLE;
 502
 503         record.buf = (char *)s;
 504         record.size = c;
 505         psinfo->write(&record);
 506 }
 507
 508 static struct console pstore_console = {
 509         .name   = "pstore",
 510         .write  = pstore_console_write,
 511         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 512         .index  = -1,
 513 };
 514
 515 static void pstore_register_console(void)
 516 {
 517         register_console(&pstore_console);
 518 }
 519
 520 static void pstore_unregister_console(void)
 521 {
 522         unregister_console(&pstore_console);
 523 }
 524 #else
 525 static void pstore_register_console(void) {}
 526 static void pstore_unregister_console(void) {}
 527 #endif
 528
 529 static int pstore_write_user_compat(struct pstore_record *record,
 530                                     const char __user *buf)
 531 {
 532         int ret = 0;
 533
 534         if (record->buf)
 535                 return -EINVAL;
 536
 537         record->buf = memdup_user(buf, record->size);
 538         if (IS_ERR(record->buf)) {
 539                 ret = PTR_ERR(record->buf);
 540                 goto out;
 541         }
 542
 543         ret = record->psi->write(record);
 544
 545         kfree(record->buf);
 546 out:
 547         record->buf = NULL;
 548
 549         return unlikely(ret < 0) ? ret : record->size;
 550 }
 551
 552 /*
 553  * platform specific persistent storage driver registers with
 554  * us here. If pstore is already mounted, call the platform
 555  * read function right away to populate the file system. If not
 556  * then the pstore mount code will call us later to fill out
 557  * the file system.
 558  */
 559 int pstore_register(struct pstore_info *psi)
 560 {
 561         struct module *owner = psi->owner;
 562
 563         if (backend && strcmp(backend, psi->name)) {
 564                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 565                 return -EPERM;
 566         }
 567
 568         /* Sanity check flags. */
 569         if (!psi->flags) {
 570                 pr_warn("backend '%s' must support at least one frontend\n",
 571                         psi->name);
 572                 return -EINVAL;
 573         }
 574
 575         /* Check for required functions. */
 576         if (!psi->read || !psi->write) {
 577                 pr_warn("backend '%s' must implement read() and write()\n",
 578                         psi->name);
 579                 return -EINVAL;
 580         }
 581
 582         spin_lock(&pstore_lock);
 583         if (psinfo) {
 584                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 585                         psinfo->name, psi->name);
 586                 spin_unlock(&pstore_lock);
 587                 return -EBUSY;
 588         }
 589
 590         if (!psi->write_user)
 591                 psi->write_user = pstore_write_user_compat;
 592         psinfo = psi;
 593         mutex_init(&psinfo->read_mutex);
 594         sema_init(&psinfo->buf_lock, 1);
 595         spin_unlock(&pstore_lock);
 596
 597         if (owner && !try_module_get(owner)) {
 598                 psinfo = NULL;
 599                 return -EINVAL;
 600         }
 601
 602         if (psi->flags & PSTORE_FLAGS_DMESG)
 603                 allocate_buf_for_compression();
 604
 605         if (pstore_is_mounted())
 606                 pstore_get_records(0);
 607
 608         if (psi->flags & PSTORE_FLAGS_DMESG)
 609                 pstore_register_kmsg();
 610         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 611                 pstore_register_console();
 612         if (psi->flags & PSTORE_FLAGS_FTRACE)
 613                 pstore_register_ftrace();
 614         if (psi->flags & PSTORE_FLAGS_PMSG)
 615                 pstore_register_pmsg();
 616
 617         /* Start watching for new records, if desired. */
 618         if (pstore_update_ms >= 0) {
 619                 pstore_timer.expires = jiffies +
 620                         msecs_to_jiffies(pstore_update_ms);
 621                 add_timer(&pstore_timer);
 622         }
 623
 624         /*
 625          * Update the module parameter backend, so it is visible
 626          * through /sys/module/pstore/parameters/backend
 627          */
 628         backend = psi->name;
 629
 630         pr_info("Registered %s as persistent store backend\n", psi->name);
 631
 632         module_put(owner);
 633
 634         return 0;
 635 }
 636 EXPORT_SYMBOL_GPL(pstore_register);
 637
 638 void pstore_unregister(struct pstore_info *psi)
 639 {
 640         /* Stop timer and make sure all work has finished. */
 641         pstore_update_ms = -1;
 642         del_timer_sync(&pstore_timer);
 643         flush_work(&pstore_work);
 644
 645         if (psi->flags & PSTORE_FLAGS_PMSG)
 646                 pstore_unregister_pmsg();
 647         if (psi->flags & PSTORE_FLAGS_FTRACE)
 648                 pstore_unregister_ftrace();
 649         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 650                 pstore_unregister_console();
 651         if (psi->flags & PSTORE_FLAGS_DMESG)
 652                 pstore_unregister_kmsg();
 653
 654         free_buf_for_compression();
 655
 656         psinfo = NULL;
 657         backend = NULL;
 658 }
 659 EXPORT_SYMBOL_GPL(pstore_unregister);
 660
 661 static void decompress_record(struct pstore_record *record)
 662 {
 663         int ret;
 664         int unzipped_len;
 665         char *unzipped, *workspace;
 666
 667         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
 668                 return;
 669
 670         /* Only PSTORE_TYPE_DMESG support compression. */
 671         if (record->type != PSTORE_TYPE_DMESG) {
 672                 pr_warn("ignored compressed record type %d\n", record->type);
 673                 return;
 674         }
 675
 676         /* Missing compression buffer means compression was not initialized. */
 677         if (!big_oops_buf) {
 678                 pr_warn("no decompression method initialized!\n");
 679                 return;
 680         }
 681
 682         /* Allocate enough space to hold max decompression and ECC. */
 683         unzipped_len = big_oops_buf_sz;
 684         workspace = kmalloc(unzipped_len + record->ecc_notice_size,
 685                             GFP_KERNEL);
 686         if (!workspace)
 687                 return;
 688
 689         /* After decompression "unzipped_len" is almost certainly smaller. */
 690         ret = crypto_comp_decompress(tfm, record->buf, record->size,
 691                                           workspace, &unzipped_len);
 692         if (ret) {
 693                 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
 694                 kfree(workspace);
 695                 return;
 696         }
 697
 698         /* Append ECC notice to decompressed buffer. */
 699         memcpy(workspace + unzipped_len, record->buf + record->size,
 700                record->ecc_notice_size);
 701
 702         /* Copy decompressed contents into an minimum-sized allocation. */
 703         unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
 704                            GFP_KERNEL);
 705         kfree(workspace);
 706         if (!unzipped)
 707                 return;
 708
 709         /* Swap out compressed contents with decompressed contents. */
 710         kfree(record->buf);
 711         record->buf = unzipped;
 712         record->size = unzipped_len;
 713         record->compressed = false;
 714 }
 715
 716 /*
 717  * Read all the records from one persistent store backend. Create
 718  * files in our filesystem.  Don't warn about -EEXIST errors
 719  * when we are re-scanning the backing store looking to add new
 720  * error records.
 721  */
 722 void pstore_get_backend_records(struct pstore_info *psi,
 723                                 struct dentry *root, int quiet)
 724 {
 725         int failed = 0;
 726         unsigned int stop_loop = 65536;
 727
 728         if (!psi || !root)
 729                 return;
 730
 731         mutex_lock(&psi->read_mutex);
 732         if (psi->open && psi->open(psi))
 733                 goto out;
 734
 735         /*
 736          * Backend callback read() allocates record.buf. decompress_record()
 737          * may reallocate record.buf. On success, pstore_mkfile() will keep
 738          * the record.buf, so free it only on failure.
 739          */
 740         for (; stop_loop; stop_loop--) {
 741                 struct pstore_record *record;
 742                 int rc;
 743
 744                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 745                 if (!record) {
 746                         pr_err("out of memory creating record\n");
 747                         break;
 748                 }
 749                 pstore_record_init(record, psi);
 750
 751                 record->size = psi->read(record);
 752
 753                 /* No more records left in backend? */
 754                 if (record->size <= 0) {
 755                         kfree(record);
 756                         break;
 757                 }
 758
 759                 decompress_record(record);
 760                 rc = pstore_mkfile(root, record);
 761                 if (rc) {
 762                         /* pstore_mkfile() did not take record, so free it. */
 763                         kfree(record->buf);
 764                         kfree(record);
 765                         if (rc != -EEXIST || !quiet)
 766                                 failed++;
 767                 }
 768         }
 769         if (psi->close)
 770                 psi->close(psi);
 771 out:
 772         mutex_unlock(&psi->read_mutex);
 773
 774         if (failed)
 775                 pr_warn("failed to create %d record(s) from '%s'\n",
 776                         failed, psi->name);
 777         if (!stop_loop)
 778                 pr_err("looping? Too many records seen from '%s'\n",
 779                         psi->name);
 780 }
 781
 782 static void pstore_dowork(struct work_struct *work)
 783 {
 784         pstore_get_records(1);
 785 }
 786
 787 static void pstore_timefunc(struct timer_list *unused)
 788 {
 789         if (pstore_new_entry) {
 790                 pstore_new_entry = 0;
 791                 schedule_work(&pstore_work);
 792         }
 793
 794         if (pstore_update_ms >= 0)
 795                 mod_timer(&pstore_timer,
 796                           jiffies + msecs_to_jiffies(pstore_update_ms));
 797 }
 798
 799 void __init pstore_choose_compression(void)
 800 {
 801         const struct pstore_zbackend *step;
 802
 803         if (!compress)
 804                 return;
 805
 806         for (step = zbackends; step->name; step++) {
 807                 if (!strcmp(compress, step->name)) {
 808                         zbackend = step;
 809                         return;
 810                 }
 811         }
 812 }
 813
 814 static int __init pstore_init(void)
 815 {
 816         int ret;
 817
 818         pstore_choose_compression();
 819
 820         /*
 821          * Check if any pstore backends registered earlier but did not
 822          * initialize compression because crypto was not ready. If so,
 823          * initialize compression now.
 824          */
 825         allocate_buf_for_compression();
 826
 827         ret = pstore_init_fs();
 828         if (ret)
 829                 free_buf_for_compression();
 830
 831         return ret;
 832 }
 833 late_initcall(pstore_init);
 834
 835 static void __exit pstore_exit(void)
 836 {
 837         pstore_exit_fs();
 838 }
 839 module_exit(pstore_exit)
 840
 841 module_param(compress, charp, 0444);
 842 MODULE_PARM_DESC(compress, "Pstore compression to use");
 843
 844 module_param(backend, charp, 0444);
 845 MODULE_PARM_DESC(backend, "Pstore backend to use");
 846
 847 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 848 MODULE_LICENSE("GPL");