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 /* Names should be in the same order as the enum pstore_type_id */
  63 static const char * const pstore_type_names[] = {
  64         "dmesg",
  65         "mce",
  66         "console",
  67         "ftrace",
  68         "rtas",
  69         "powerpc-ofw",
  70         "powerpc-common",
  71         "pmsg",
  72         "powerpc-opal",
  73 };
  74
  75 static int pstore_new_entry;
  76
  77 static void pstore_timefunc(struct timer_list *);
  78 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
  79
  80 static void pstore_dowork(struct work_struct *);
  81 static DECLARE_WORK(pstore_work, pstore_dowork);
  82
  83 /*
  84  * pstore_lock just protects "psinfo" during
  85  * calls to pstore_register()
  86  */
  87 static DEFINE_SPINLOCK(pstore_lock);
  88 struct pstore_info *psinfo;
  89
  90 static char *backend;
  91 static char *compress =
  92 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
  93                 CONFIG_PSTORE_COMPRESS_DEFAULT;
  94 #else
  95                 NULL;
  96 #endif
  97
  98 /* Compression parameters */
  99 static struct crypto_comp *tfm;
 100
 101 struct pstore_zbackend {
 102         int (*zbufsize)(size_t size);
 103         const char *name;
 104 };
 105
 106 static char *big_oops_buf;
 107 static size_t big_oops_buf_sz;
 108
 109 /* How much of the console log to snapshot */
 110 unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
 111
 112 void pstore_set_kmsg_bytes(int bytes)
 113 {
 114         kmsg_bytes = bytes;
 115 }
 116
 117 /* Tag each group of saved records with a sequence number */
 118 static int      oopscount;
 119
 120 const char *pstore_type_to_name(enum pstore_type_id type)
 121 {
 122         BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
 123
 124         if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
 125                 return "unknown";
 126
 127         return pstore_type_names[type];
 128 }
 129 EXPORT_SYMBOL_GPL(pstore_type_to_name);
 130
 131 enum pstore_type_id pstore_name_to_type(const char *name)
 132 {
 133         int i;
 134
 135         for (i = 0; i < PSTORE_TYPE_MAX; i++) {
 136                 if (!strcmp(pstore_type_names[i], name))
 137                         return i;
 138         }
 139
 140         return PSTORE_TYPE_MAX;
 141 }
 142 EXPORT_SYMBOL_GPL(pstore_name_to_type);
 143
 144 static const char *get_reason_str(enum kmsg_dump_reason reason)
 145 {
 146         switch (reason) {
 147         case KMSG_DUMP_PANIC:
 148                 return "Panic";
 149         case KMSG_DUMP_OOPS:
 150                 return "Oops";
 151         case KMSG_DUMP_EMERG:
 152                 return "Emergency";
 153         case KMSG_DUMP_RESTART:
 154                 return "Restart";
 155         case KMSG_DUMP_HALT:
 156                 return "Halt";
 157         case KMSG_DUMP_POWEROFF:
 158                 return "Poweroff";
 159         default:
 160                 return "Unknown";
 161         }
 162 }
 163
 164 /*
 165  * Should pstore_dump() wait for a concurrent pstore_dump()? If
 166  * not, the current pstore_dump() will report a failure to dump
 167  * and return.
 168  */
 169 static bool pstore_cannot_wait(enum kmsg_dump_reason reason)
 170 {
 171         /* In NMI path, pstore shouldn't block regardless of reason. */
 172         if (in_nmi())
 173                 return true;
 174
 175         switch (reason) {
 176         /* In panic case, other cpus are stopped by smp_send_stop(). */
 177         case KMSG_DUMP_PANIC:
 178         /* Emergency restart shouldn't be blocked. */
 179         case KMSG_DUMP_EMERG:
 180                 return true;
 181         default:
 182                 return false;
 183         }
 184 }
 185
 186 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 187 static int zbufsize_deflate(size_t size)
 188 {
 189         size_t cmpr;
 190
 191         switch (size) {
 192         /* buffer range for efivars */
 193         case 1000 ... 2000:
 194                 cmpr = 56;
 195                 break;
 196         case 2001 ... 3000:
 197                 cmpr = 54;
 198                 break;
 199         case 3001 ... 3999:
 200                 cmpr = 52;
 201                 break;
 202         /* buffer range for nvram, erst */
 203         case 4000 ... 10000:
 204                 cmpr = 45;
 205                 break;
 206         default:
 207                 cmpr = 60;
 208                 break;
 209         }
 210
 211         return (size * 100) / cmpr;
 212 }
 213 #endif
 214
 215 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 216 static int zbufsize_lzo(size_t size)
 217 {
 218         return lzo1x_worst_compress(size);
 219 }
 220 #endif
 221
 222 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 223 static int zbufsize_lz4(size_t size)
 224 {
 225         return LZ4_compressBound(size);
 226 }
 227 #endif
 228
 229 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 230 static int zbufsize_842(size_t size)
 231 {
 232         return size;
 233 }
 234 #endif
 235
 236 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 237 static int zbufsize_zstd(size_t size)
 238 {
 239         return ZSTD_compressBound(size);
 240 }
 241 #endif
 242
 243 static const struct pstore_zbackend *zbackend __ro_after_init;
 244
 245 static const struct pstore_zbackend zbackends[] = {
 246 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
 247         {
 248                 .zbufsize       = zbufsize_deflate,
 249                 .name           = "deflate",
 250         },
 251 #endif
 252 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
 253         {
 254                 .zbufsize       = zbufsize_lzo,
 255                 .name           = "lzo",
 256         },
 257 #endif
 258 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
 259         {
 260                 .zbufsize       = zbufsize_lz4,
 261                 .name           = "lz4",
 262         },
 263 #endif
 264 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 265         {
 266                 .zbufsize       = zbufsize_lz4,
 267                 .name           = "lz4hc",
 268         },
 269 #endif
 270 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
 271         {
 272                 .zbufsize       = zbufsize_842,
 273                 .name           = "842",
 274         },
 275 #endif
 276 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 277         {
 278                 .zbufsize       = zbufsize_zstd,
 279                 .name           = "zstd",
 280         },
 281 #endif
 282         { }
 283 };
 284
 285 static int pstore_compress(const void *in, void *out,
 286                            unsigned int inlen, unsigned int outlen)
 287 {
 288         int ret;
 289
 290         ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
 291         if (ret) {
 292                 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
 293                 return ret;
 294         }
 295
 296         return outlen;
 297 }
 298
 299 static void allocate_buf_for_compression(void)
 300 {
 301         struct crypto_comp *ctx;
 302         int size;
 303         char *buf;
 304
 305         /* Skip if not built-in or compression backend not selected yet. */
 306         if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
 307                 return;
 308
 309         /* Skip if no pstore backend yet or compression init already done. */
 310         if (!psinfo || tfm)
 311                 return;
 312
 313         if (!crypto_has_comp(zbackend->name, 0, 0)) {
 314                 pr_err("Unknown compression: %s\n", zbackend->name);
 315                 return;
 316         }
 317
 318         size = zbackend->zbufsize(psinfo->bufsize);
 319         if (size <= 0) {
 320                 pr_err("Invalid compression size for %s: %d\n",
 321                        zbackend->name, size);
 322                 return;
 323         }
 324
 325         buf = kmalloc(size, GFP_KERNEL);
 326         if (!buf) {
 327                 pr_err("Failed %d byte compression buffer allocation for: %s\n",
 328                        size, zbackend->name);
 329                 return;
 330         }
 331
 332         ctx = crypto_alloc_comp(zbackend->name, 0, 0);
 333         if (IS_ERR_OR_NULL(ctx)) {
 334                 kfree(buf);
 335                 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
 336                        PTR_ERR(ctx));
 337                 return;
 338         }
 339
 340         /* A non-NULL big_oops_buf indicates compression is available. */
 341         tfm = ctx;
 342         big_oops_buf_sz = size;
 343         big_oops_buf = buf;
 344
 345         pr_info("Using crash dump compression: %s\n", zbackend->name);
 346 }
 347
 348 static void free_buf_for_compression(void)
 349 {
 350         if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm)
 351                 crypto_free_comp(tfm);
 352         kfree(big_oops_buf);
 353         big_oops_buf = NULL;
 354         big_oops_buf_sz = 0;
 355 }
 356
 357 /*
 358  * Called when compression fails, since the printk buffer
 359  * would be fetched for compression calling it again when
 360  * compression fails would have moved the iterator of
 361  * printk buffer which results in fetching old contents.
 362  * Copy the recent messages from big_oops_buf to psinfo->buf
 363  */
 364 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 365 {
 366         size_t total_len;
 367         size_t diff;
 368
 369         total_len = hsize + len;
 370
 371         if (total_len > psinfo->bufsize) {
 372                 diff = total_len - psinfo->bufsize + hsize;
 373                 memcpy(psinfo->buf, big_oops_buf, hsize);
 374                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 375                                         psinfo->bufsize - hsize);
 376                 total_len = psinfo->bufsize;
 377         } else
 378                 memcpy(psinfo->buf, big_oops_buf, total_len);
 379
 380         return total_len;
 381 }
 382
 383 void pstore_record_init(struct pstore_record *record,
 384                         struct pstore_info *psinfo)
 385 {
 386         memset(record, 0, sizeof(*record));
 387
 388         record->psi = psinfo;
 389
 390         /* Report zeroed timestamp if called before timekeeping has resumed. */
 391         record->time = ns_to_timespec64(ktime_get_real_fast_ns());
 392 }
 393
 394 /*
 395  * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
 396  * end of the buffer.
 397  */
 398 static void pstore_dump(struct kmsg_dumper *dumper,
 399                         enum kmsg_dump_reason reason)
 400 {
 401         unsigned long   total = 0;
 402         const char      *why;
 403         unsigned int    part = 1;
 404         int             ret;
 405
 406         why = get_reason_str(reason);
 407
 408         if (down_trylock(&psinfo->buf_lock)) {
 409                 /* Failed to acquire lock: give up if we cannot wait. */
 410                 if (pstore_cannot_wait(reason)) {
 411                         pr_err("dump skipped in %s path: may corrupt error record\n",
 412                                 in_nmi() ? "NMI" : why);
 413                         return;
 414                 }
 415                 if (down_interruptible(&psinfo->buf_lock)) {
 416                         pr_err("could not grab semaphore?!\n");
 417                         return;
 418                 }
 419         }
 420
 421         oopscount++;
 422         while (total < kmsg_bytes) {
 423                 char *dst;
 424                 size_t dst_size;
 425                 int header_size;
 426                 int zipped_len = -1;
 427                 size_t dump_size;
 428                 struct pstore_record record;
 429
 430                 pstore_record_init(&record, psinfo);
 431                 record.type = PSTORE_TYPE_DMESG;
 432                 record.count = oopscount;
 433                 record.reason = reason;
 434                 record.part = part;
 435                 record.buf = psinfo->buf;
 436
 437                 if (big_oops_buf) {
 438                         dst = big_oops_buf;
 439                         dst_size = big_oops_buf_sz;
 440                 } else {
 441                         dst = psinfo->buf;
 442                         dst_size = psinfo->bufsize;
 443                 }
 444
 445                 /* Write dump header. */
 446                 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
 447                                  oopscount, part);
 448                 dst_size -= header_size;
 449
 450                 /* Write dump contents. */
 451                 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
 452                                           dst_size, &dump_size))
 453                         break;
 454
 455                 if (big_oops_buf) {
 456                         zipped_len = pstore_compress(dst, psinfo->buf,
 457                                                 header_size + dump_size,
 458                                                 psinfo->bufsize);
 459
 460                         if (zipped_len > 0) {
 461                                 record.compressed = true;
 462                                 record.size = zipped_len;
 463                         } else {
 464                                 record.size = copy_kmsg_to_buffer(header_size,
 465                                                                   dump_size);
 466                         }
 467                 } else {
 468                         record.size = header_size + dump_size;
 469                 }
 470
 471                 ret = psinfo->write(&record);
 472                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 473                         pstore_new_entry = 1;
 474
 475                 total += record.size;
 476                 part++;
 477         }
 478
 479         up(&psinfo->buf_lock);
 480 }
 481
 482 static struct kmsg_dumper pstore_dumper = {
 483         .dump = pstore_dump,
 484 };
 485
 486 /*
 487  * Register with kmsg_dump to save last part of console log on panic.
 488  */
 489 static void pstore_register_kmsg(void)
 490 {
 491         kmsg_dump_register(&pstore_dumper);
 492 }
 493
 494 static void pstore_unregister_kmsg(void)
 495 {
 496         kmsg_dump_unregister(&pstore_dumper);
 497 }
 498
 499 #ifdef CONFIG_PSTORE_CONSOLE
 500 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 501 {
 502         struct pstore_record record;
 503
 504         if (!c)
 505                 return;
 506
 507         pstore_record_init(&record, psinfo);
 508         record.type = PSTORE_TYPE_CONSOLE;
 509
 510         record.buf = (char *)s;
 511         record.size = c;
 512         psinfo->write(&record);
 513 }
 514
 515 static struct console pstore_console = {
 516         .name   = "pstore",
 517         .write  = pstore_console_write,
 518         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 519         .index  = -1,
 520 };
 521
 522 static void pstore_register_console(void)
 523 {
 524         register_console(&pstore_console);
 525 }
 526
 527 static void pstore_unregister_console(void)
 528 {
 529         unregister_console(&pstore_console);
 530 }
 531 #else
 532 static void pstore_register_console(void) {}
 533 static void pstore_unregister_console(void) {}
 534 #endif
 535
 536 static int pstore_write_user_compat(struct pstore_record *record,
 537                                     const char __user *buf)
 538 {
 539         int ret = 0;
 540
 541         if (record->buf)
 542                 return -EINVAL;
 543
 544         record->buf = memdup_user(buf, record->size);
 545         if (IS_ERR(record->buf)) {
 546                 ret = PTR_ERR(record->buf);
 547                 goto out;
 548         }
 549
 550         ret = record->psi->write(record);
 551
 552         kfree(record->buf);
 553 out:
 554         record->buf = NULL;
 555
 556         return unlikely(ret < 0) ? ret : record->size;
 557 }
 558
 559 /*
 560  * platform specific persistent storage driver registers with
 561  * us here. If pstore is already mounted, call the platform
 562  * read function right away to populate the file system. If not
 563  * then the pstore mount code will call us later to fill out
 564  * the file system.
 565  */
 566 int pstore_register(struct pstore_info *psi)
 567 {
 568         struct module *owner = psi->owner;
 569
 570         if (backend && strcmp(backend, psi->name)) {
 571                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 572                 return -EPERM;
 573         }
 574
 575         /* Sanity check flags. */
 576         if (!psi->flags) {
 577                 pr_warn("backend '%s' must support at least one frontend\n",
 578                         psi->name);
 579                 return -EINVAL;
 580         }
 581
 582         /* Check for required functions. */
 583         if (!psi->read || !psi->write) {
 584                 pr_warn("backend '%s' must implement read() and write()\n",
 585                         psi->name);
 586                 return -EINVAL;
 587         }
 588
 589         spin_lock(&pstore_lock);
 590         if (psinfo) {
 591                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 592                         psinfo->name, psi->name);
 593                 spin_unlock(&pstore_lock);
 594                 return -EBUSY;
 595         }
 596
 597         if (!psi->write_user)
 598                 psi->write_user = pstore_write_user_compat;
 599         psinfo = psi;
 600         mutex_init(&psinfo->read_mutex);
 601         sema_init(&psinfo->buf_lock, 1);
 602         spin_unlock(&pstore_lock);
 603
 604         if (owner && !try_module_get(owner)) {
 605                 psinfo = NULL;
 606                 return -EINVAL;
 607         }
 608
 609         allocate_buf_for_compression();
 610
 611         if (pstore_is_mounted())
 612                 pstore_get_records(0);
 613
 614         if (psi->flags & PSTORE_FLAGS_DMESG)
 615                 pstore_register_kmsg();
 616         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 617                 pstore_register_console();
 618         if (psi->flags & PSTORE_FLAGS_FTRACE)
 619                 pstore_register_ftrace();
 620         if (psi->flags & PSTORE_FLAGS_PMSG)
 621                 pstore_register_pmsg();
 622
 623         /* Start watching for new records, if desired. */
 624         if (pstore_update_ms >= 0) {
 625                 pstore_timer.expires = jiffies +
 626                         msecs_to_jiffies(pstore_update_ms);
 627                 add_timer(&pstore_timer);
 628         }
 629
 630         /*
 631          * Update the module parameter backend, so it is visible
 632          * through /sys/module/pstore/parameters/backend
 633          */
 634         backend = psi->name;
 635
 636         pr_info("Registered %s as persistent store backend\n", psi->name);
 637
 638         module_put(owner);
 639
 640         return 0;
 641 }
 642 EXPORT_SYMBOL_GPL(pstore_register);
 643
 644 void pstore_unregister(struct pstore_info *psi)
 645 {
 646         /* Stop timer and make sure all work has finished. */
 647         pstore_update_ms = -1;
 648         del_timer_sync(&pstore_timer);
 649         flush_work(&pstore_work);
 650
 651         if (psi->flags & PSTORE_FLAGS_PMSG)
 652                 pstore_unregister_pmsg();
 653         if (psi->flags & PSTORE_FLAGS_FTRACE)
 654                 pstore_unregister_ftrace();
 655         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 656                 pstore_unregister_console();
 657         if (psi->flags & PSTORE_FLAGS_DMESG)
 658                 pstore_unregister_kmsg();
 659
 660         free_buf_for_compression();
 661
 662         psinfo = NULL;
 663         backend = NULL;
 664 }
 665 EXPORT_SYMBOL_GPL(pstore_unregister);
 666
 667 static void decompress_record(struct pstore_record *record)
 668 {
 669         int ret;
 670         int unzipped_len;
 671         char *unzipped, *workspace;
 672
 673         if (!record->compressed)
 674                 return;
 675
 676         /* Only PSTORE_TYPE_DMESG support compression. */
 677         if (record->type != PSTORE_TYPE_DMESG) {
 678                 pr_warn("ignored compressed record type %d\n", record->type);
 679                 return;
 680         }
 681
 682         /* Missing compression buffer means compression was not initialized. */
 683         if (!big_oops_buf) {
 684                 pr_warn("no decompression method initialized!\n");
 685                 return;
 686         }
 687
 688         /* Allocate enough space to hold max decompression and ECC. */
 689         unzipped_len = big_oops_buf_sz;
 690         workspace = kmalloc(unzipped_len + record->ecc_notice_size,
 691                             GFP_KERNEL);
 692         if (!workspace)
 693                 return;
 694
 695         /* After decompression "unzipped_len" is almost certainly smaller. */
 696         ret = crypto_comp_decompress(tfm, record->buf, record->size,
 697                                           workspace, &unzipped_len);
 698         if (ret) {
 699                 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
 700                 kfree(workspace);
 701                 return;
 702         }
 703
 704         /* Append ECC notice to decompressed buffer. */
 705         memcpy(workspace + unzipped_len, record->buf + record->size,
 706                record->ecc_notice_size);
 707
 708         /* Copy decompressed contents into an minimum-sized allocation. */
 709         unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
 710                            GFP_KERNEL);
 711         kfree(workspace);
 712         if (!unzipped)
 713                 return;
 714
 715         /* Swap out compressed contents with decompressed contents. */
 716         kfree(record->buf);
 717         record->buf = unzipped;
 718         record->size = unzipped_len;
 719         record->compressed = false;
 720 }
 721
 722 /*
 723  * Read all the records from one persistent store backend. Create
 724  * files in our filesystem.  Don't warn about -EEXIST errors
 725  * when we are re-scanning the backing store looking to add new
 726  * error records.
 727  */
 728 void pstore_get_backend_records(struct pstore_info *psi,
 729                                 struct dentry *root, int quiet)
 730 {
 731         int failed = 0;
 732         unsigned int stop_loop = 65536;
 733
 734         if (!psi || !root)
 735                 return;
 736
 737         mutex_lock(&psi->read_mutex);
 738         if (psi->open && psi->open(psi))
 739                 goto out;
 740
 741         /*
 742          * Backend callback read() allocates record.buf. decompress_record()
 743          * may reallocate record.buf. On success, pstore_mkfile() will keep
 744          * the record.buf, so free it only on failure.
 745          */
 746         for (; stop_loop; stop_loop--) {
 747                 struct pstore_record *record;
 748                 int rc;
 749
 750                 record = kzalloc(sizeof(*record), GFP_KERNEL);
 751                 if (!record) {
 752                         pr_err("out of memory creating record\n");
 753                         break;
 754                 }
 755                 pstore_record_init(record, psi);
 756
 757                 record->size = psi->read(record);
 758
 759                 /* No more records left in backend? */
 760                 if (record->size <= 0) {
 761                         kfree(record);
 762                         break;
 763                 }
 764
 765                 decompress_record(record);
 766                 rc = pstore_mkfile(root, record);
 767                 if (rc) {
 768                         /* pstore_mkfile() did not take record, so free it. */
 769                         kfree(record->buf);
 770                         kfree(record);
 771                         if (rc != -EEXIST || !quiet)
 772                                 failed++;
 773                 }
 774         }
 775         if (psi->close)
 776                 psi->close(psi);
 777 out:
 778         mutex_unlock(&psi->read_mutex);
 779
 780         if (failed)
 781                 pr_warn("failed to create %d record(s) from '%s'\n",
 782                         failed, psi->name);
 783         if (!stop_loop)
 784                 pr_err("looping? Too many records seen from '%s'\n",
 785                         psi->name);
 786 }
 787
 788 static void pstore_dowork(struct work_struct *work)
 789 {
 790         pstore_get_records(1);
 791 }
 792
 793 static void pstore_timefunc(struct timer_list *unused)
 794 {
 795         if (pstore_new_entry) {
 796                 pstore_new_entry = 0;
 797                 schedule_work(&pstore_work);
 798         }
 799
 800         if (pstore_update_ms >= 0)
 801                 mod_timer(&pstore_timer,
 802                           jiffies + msecs_to_jiffies(pstore_update_ms));
 803 }
 804
 805 void __init pstore_choose_compression(void)
 806 {
 807         const struct pstore_zbackend *step;
 808
 809         if (!compress)
 810                 return;
 811
 812         for (step = zbackends; step->name; step++) {
 813                 if (!strcmp(compress, step->name)) {
 814                         zbackend = step;
 815                         return;
 816                 }
 817         }
 818 }
 819
 820 static int __init pstore_init(void)
 821 {
 822         int ret;
 823
 824         pstore_choose_compression();
 825
 826         /*
 827          * Check if any pstore backends registered earlier but did not
 828          * initialize compression because crypto was not ready. If so,
 829          * initialize compression now.
 830          */
 831         allocate_buf_for_compression();
 832
 833         ret = pstore_init_fs();
 834         if (ret)
 835                 return ret;
 836
 837         return 0;
 838 }
 839 late_initcall(pstore_init);
 840
 841 static void __exit pstore_exit(void)
 842 {
 843         pstore_exit_fs();
 844 }
 845 module_exit(pstore_exit)
 846
 847 module_param(compress, charp, 0444);
 848 MODULE_PARM_DESC(compress, "Pstore compression to use");
 849
 850 module_param(backend, charp, 0444);
 851 MODULE_PARM_DESC(backend, "Pstore backend to use");
 852
 853 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 854 MODULE_LICENSE("GPL");