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 #ifdef CONFIG_PSTORE_ZLIB_COMPRESS
  32 #include <linux/zlib.h>
  33 #endif
  34 #ifdef CONFIG_PSTORE_LZO_COMPRESS
  35 #include <linux/lzo.h>
  36 #endif
  37 #ifdef CONFIG_PSTORE_LZ4_COMPRESS
  38 #include <linux/lz4.h>
  39 #endif
  40 #include <linux/string.h>
  41 #include <linux/timer.h>
  42 #include <linux/slab.h>
  43 #include <linux/uaccess.h>
  44 #include <linux/hardirq.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(unsigned long);
  65 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
  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
  79 /* Compression parameters */
  80 #ifdef CONFIG_PSTORE_ZLIB_COMPRESS
  81 #define COMPR_LEVEL 6
  82 #define WINDOW_BITS 12
  83 #define MEM_LEVEL 4
  84 static struct z_stream_s stream;
  85 #else
  86 static unsigned char *workspace;
  87 #endif
  88
  89 struct pstore_zbackend {
  90         int (*compress)(const void *in, void *out, size_t inlen, size_t outlen);
  91         int (*decompress)(void *in, void *out, size_t inlen, size_t outlen);
  92         void (*allocate)(void);
  93         void (*free)(void);
  94
  95         const char *name;
  96 };
  97
  98 static char *big_oops_buf;
  99 static size_t big_oops_buf_sz;
 100
 101 /* How much of the console log to snapshot */
 102 static unsigned long kmsg_bytes = 10240;
 103
 104 void pstore_set_kmsg_bytes(int bytes)
 105 {
 106         kmsg_bytes = bytes;
 107 }
 108
 109 /* Tag each group of saved records with a sequence number */
 110 static int      oopscount;
 111
 112 static const char *get_reason_str(enum kmsg_dump_reason reason)
 113 {
 114         switch (reason) {
 115         case KMSG_DUMP_PANIC:
 116                 return "Panic";
 117         case KMSG_DUMP_OOPS:
 118                 return "Oops";
 119         case KMSG_DUMP_EMERG:
 120                 return "Emergency";
 121         case KMSG_DUMP_RESTART:
 122                 return "Restart";
 123         case KMSG_DUMP_HALT:
 124                 return "Halt";
 125         case KMSG_DUMP_POWEROFF:
 126                 return "Poweroff";
 127         default:
 128                 return "Unknown";
 129         }
 130 }
 131
 132 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 133 {
 134         /*
 135          * In case of NMI path, pstore shouldn't be blocked
 136          * regardless of reason.
 137          */
 138         if (in_nmi())
 139                 return true;
 140
 141         switch (reason) {
 142         /* In panic case, other cpus are stopped by smp_send_stop(). */
 143         case KMSG_DUMP_PANIC:
 144         /* Emergency restart shouldn't be blocked by spin lock. */
 145         case KMSG_DUMP_EMERG:
 146                 return true;
 147         default:
 148                 return false;
 149         }
 150 }
 151 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
 152
 153 #ifdef CONFIG_PSTORE_ZLIB_COMPRESS
 154 /* Derived from logfs_compress() */
 155 static int compress_zlib(const void *in, void *out, size_t inlen, size_t outlen)
 156 {
 157         int err, ret;
 158
 159         ret = -EIO;
 160         err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
 161                                                 MEM_LEVEL, Z_DEFAULT_STRATEGY);
 162         if (err != Z_OK)
 163                 goto error;
 164
 165         stream.next_in = in;
 166         stream.avail_in = inlen;
 167         stream.total_in = 0;
 168         stream.next_out = out;
 169         stream.avail_out = outlen;
 170         stream.total_out = 0;
 171
 172         err = zlib_deflate(&stream, Z_FINISH);
 173         if (err != Z_STREAM_END)
 174                 goto error;
 175
 176         err = zlib_deflateEnd(&stream);
 177         if (err != Z_OK)
 178                 goto error;
 179
 180         if (stream.total_out >= stream.total_in)
 181                 goto error;
 182
 183         ret = stream.total_out;
 184 error:
 185         return ret;
 186 }
 187
 188 /* Derived from logfs_uncompress */
 189 static int decompress_zlib(void *in, void *out, size_t inlen, size_t outlen)
 190 {
 191         int err, ret;
 192
 193         ret = -EIO;
 194         err = zlib_inflateInit2(&stream, WINDOW_BITS);
 195         if (err != Z_OK)
 196                 goto error;
 197
 198         stream.next_in = in;
 199         stream.avail_in = inlen;
 200         stream.total_in = 0;
 201         stream.next_out = out;
 202         stream.avail_out = outlen;
 203         stream.total_out = 0;
 204
 205         err = zlib_inflate(&stream, Z_FINISH);
 206         if (err != Z_STREAM_END)
 207                 goto error;
 208
 209         err = zlib_inflateEnd(&stream);
 210         if (err != Z_OK)
 211                 goto error;
 212
 213         ret = stream.total_out;
 214 error:
 215         return ret;
 216 }
 217
 218 static void allocate_zlib(void)
 219 {
 220         size_t size;
 221         size_t cmpr;
 222
 223         switch (psinfo->bufsize) {
 224         /* buffer range for efivars */
 225         case 1000 ... 2000:
 226                 cmpr = 56;
 227                 break;
 228         case 2001 ... 3000:
 229                 cmpr = 54;
 230                 break;
 231         case 3001 ... 3999:
 232                 cmpr = 52;
 233                 break;
 234         /* buffer range for nvram, erst */
 235         case 4000 ... 10000:
 236                 cmpr = 45;
 237                 break;
 238         default:
 239                 cmpr = 60;
 240                 break;
 241         }
 242
 243         big_oops_buf_sz = (psinfo->bufsize * 100) / cmpr;
 244         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 245         if (big_oops_buf) {
 246                 size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
 247                         zlib_inflate_workspacesize());
 248                 stream.workspace = kmalloc(size, GFP_KERNEL);
 249                 if (!stream.workspace) {
 250                         pr_err("No memory for compression workspace; skipping compression\n");
 251                         kfree(big_oops_buf);
 252                         big_oops_buf = NULL;
 253                 }
 254         } else {
 255                 pr_err("No memory for uncompressed data; skipping compression\n");
 256                 stream.workspace = NULL;
 257         }
 258
 259 }
 260
 261 static void free_zlib(void)
 262 {
 263         kfree(stream.workspace);
 264         stream.workspace = NULL;
 265         kfree(big_oops_buf);
 266         big_oops_buf = NULL;
 267         big_oops_buf_sz = 0;
 268 }
 269
 270 static const struct pstore_zbackend backend_zlib = {
 271         .compress       = compress_zlib,
 272         .decompress     = decompress_zlib,
 273         .allocate       = allocate_zlib,
 274         .free           = free_zlib,
 275         .name           = "zlib",
 276 };
 277 #endif
 278
 279 #ifdef CONFIG_PSTORE_LZO_COMPRESS
 280 static int compress_lzo(const void *in, void *out, size_t inlen, size_t outlen)
 281 {
 282         int ret;
 283
 284         ret = lzo1x_1_compress(in, inlen, out, &outlen, workspace);
 285         if (ret != LZO_E_OK) {
 286                 pr_err("lzo_compress error, ret = %d!\n", ret);
 287                 return -EIO;
 288         }
 289
 290         return outlen;
 291 }
 292
 293 static int decompress_lzo(void *in, void *out, size_t inlen, size_t outlen)
 294 {
 295         int ret;
 296
 297         ret = lzo1x_decompress_safe(in, inlen, out, &outlen);
 298         if (ret != LZO_E_OK) {
 299                 pr_err("lzo_decompress error, ret = %d!\n", ret);
 300                 return -EIO;
 301         }
 302
 303         return outlen;
 304 }
 305
 306 static void allocate_lzo(void)
 307 {
 308         big_oops_buf_sz = lzo1x_worst_compress(psinfo->bufsize);
 309         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 310         if (big_oops_buf) {
 311                 workspace = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 312                 if (!workspace) {
 313                         pr_err("No memory for compression workspace; skipping compression\n");
 314                         kfree(big_oops_buf);
 315                         big_oops_buf = NULL;
 316                 }
 317         } else {
 318                 pr_err("No memory for uncompressed data; skipping compression\n");
 319                 workspace = NULL;
 320         }
 321 }
 322
 323 static void free_lzo(void)
 324 {
 325         kfree(workspace);
 326         kfree(big_oops_buf);
 327         big_oops_buf = NULL;
 328         big_oops_buf_sz = 0;
 329 }
 330
 331 static const struct pstore_zbackend backend_lzo = {
 332         .compress       = compress_lzo,
 333         .decompress     = decompress_lzo,
 334         .allocate       = allocate_lzo,
 335         .free           = free_lzo,
 336         .name           = "lzo",
 337 };
 338 #endif
 339
 340 #ifdef CONFIG_PSTORE_LZ4_COMPRESS
 341 static int compress_lz4(const void *in, void *out, size_t inlen, size_t outlen)
 342 {
 343         int ret;
 344
 345         ret = LZ4_compress_default(in, out, inlen, outlen, workspace);
 346         if (!ret) {
 347                 pr_err("LZ4_compress_default error; compression failed!\n");
 348                 return -EIO;
 349         }
 350
 351         return ret;
 352 }
 353
 354 static int decompress_lz4(void *in, void *out, size_t inlen, size_t outlen)
 355 {
 356         int ret;
 357
 358         ret = LZ4_decompress_safe(in, out, inlen, outlen);
 359         if (ret < 0) {
 360                 /*
 361                  * LZ4_decompress_safe will return an error code
 362                  * (< 0) if decompression failed
 363                  */
 364                 pr_err("LZ4_decompress_safe error, ret = %d!\n", ret);
 365                 return -EIO;
 366         }
 367
 368         return ret;
 369 }
 370
 371 static void allocate_lz4(void)
 372 {
 373         big_oops_buf_sz = LZ4_compressBound(psinfo->bufsize);
 374         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 375         if (big_oops_buf) {
 376                 workspace = kmalloc(LZ4_MEM_COMPRESS, GFP_KERNEL);
 377                 if (!workspace) {
 378                         pr_err("No memory for compression workspace; skipping compression\n");
 379                         kfree(big_oops_buf);
 380                         big_oops_buf = NULL;
 381                 }
 382         } else {
 383                 pr_err("No memory for uncompressed data; skipping compression\n");
 384                 workspace = NULL;
 385         }
 386 }
 387
 388 static void free_lz4(void)
 389 {
 390         kfree(workspace);
 391         kfree(big_oops_buf);
 392         big_oops_buf = NULL;
 393         big_oops_buf_sz = 0;
 394 }
 395
 396 static const struct pstore_zbackend backend_lz4 = {
 397         .compress       = compress_lz4,
 398         .decompress     = decompress_lz4,
 399         .allocate       = allocate_lz4,
 400         .free           = free_lz4,
 401         .name           = "lz4",
 402 };
 403 #endif
 404
 405 static const struct pstore_zbackend *zbackend =
 406 #if defined(CONFIG_PSTORE_ZLIB_COMPRESS)
 407         &backend_zlib;
 408 #elif defined(CONFIG_PSTORE_LZO_COMPRESS)
 409         &backend_lzo;
 410 #elif defined(CONFIG_PSTORE_LZ4_COMPRESS)
 411         &backend_lz4;
 412 #else
 413         NULL;
 414 #endif
 415
 416 static int pstore_compress(const void *in, void *out,
 417                            size_t inlen, size_t outlen)
 418 {
 419         if (zbackend)
 420                 return zbackend->compress(in, out, inlen, outlen);
 421         else
 422                 return -EIO;
 423 }
 424
 425 static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
 426 {
 427         if (zbackend)
 428                 return zbackend->decompress(in, out, inlen, outlen);
 429         else
 430                 return -EIO;
 431 }
 432
 433 static void allocate_buf_for_compression(void)
 434 {
 435         if (zbackend) {
 436                 pr_info("using %s compression\n", zbackend->name);
 437                 zbackend->allocate();
 438         } else {
 439                 pr_err("allocate compression buffer error!\n");
 440         }
 441 }
 442
 443 static void free_buf_for_compression(void)
 444 {
 445         if (zbackend)
 446                 zbackend->free();
 447         else
 448                 pr_err("free compression buffer error!\n");
 449 }
 450
 451 /*
 452  * Called when compression fails, since the printk buffer
 453  * would be fetched for compression calling it again when
 454  * compression fails would have moved the iterator of
 455  * printk buffer which results in fetching old contents.
 456  * Copy the recent messages from big_oops_buf to psinfo->buf
 457  */
 458 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 459 {
 460         size_t total_len;
 461         size_t diff;
 462
 463         total_len = hsize + len;
 464
 465         if (total_len > psinfo->bufsize) {
 466                 diff = total_len - psinfo->bufsize + hsize;
 467                 memcpy(psinfo->buf, big_oops_buf, hsize);
 468                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 469                                         psinfo->bufsize - hsize);
 470                 total_len = psinfo->bufsize;
 471         } else
 472                 memcpy(psinfo->buf, big_oops_buf, total_len);
 473
 474         return total_len;
 475 }
 476
 477 /*
 478  * callback from kmsg_dump. (s2,l2) has the most recently
 479  * written bytes, older bytes are in (s1,l1). Save as much
 480  * as we can from the end of the buffer.
 481  */
 482 static void pstore_dump(struct kmsg_dumper *dumper,
 483                         enum kmsg_dump_reason reason)
 484 {
 485         unsigned long   total = 0;
 486         const char      *why;
 487         u64             id;
 488         unsigned int    part = 1;
 489         unsigned long   flags = 0;
 490         int             is_locked;
 491         int             ret;
 492
 493         why = get_reason_str(reason);
 494
 495         if (pstore_cannot_block_path(reason)) {
 496                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 497                 if (!is_locked) {
 498                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 499                                        , in_nmi() ? "NMI" : why);
 500                         return;
 501                 }
 502         } else {
 503                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 504                 is_locked = 1;
 505         }
 506         oopscount++;
 507         while (total < kmsg_bytes) {
 508                 char *dst;
 509                 unsigned long size;
 510                 int hsize;
 511                 int zipped_len = -1;
 512                 size_t len;
 513                 bool compressed = false;
 514                 size_t total_len;
 515
 516                 if (big_oops_buf && is_locked) {
 517                         dst = big_oops_buf;
 518                         size = big_oops_buf_sz;
 519                 } else {
 520                         dst = psinfo->buf;
 521                         size = psinfo->bufsize;
 522                 }
 523
 524                 hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount, part);
 525                 size -= hsize;
 526
 527                 if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
 528                                           size, &len))
 529                         break;
 530
 531                 if (big_oops_buf && is_locked) {
 532                         zipped_len = pstore_compress(dst, psinfo->buf,
 533                                                 hsize + len, psinfo->bufsize);
 534
 535                         if (zipped_len > 0) {
 536                                 compressed = true;
 537                                 total_len = zipped_len;
 538                         } else {
 539                                 total_len = copy_kmsg_to_buffer(hsize, len);
 540                         }
 541                 } else {
 542                         total_len = hsize + len;
 543                 }
 544
 545                 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
 546                                     oopscount, compressed, total_len, psinfo);
 547                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 548                         pstore_new_entry = 1;
 549
 550                 total += total_len;
 551                 part++;
 552         }
 553         if (is_locked)
 554                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 555 }
 556
 557 static struct kmsg_dumper pstore_dumper = {
 558         .dump = pstore_dump,
 559 };
 560
 561 /*
 562  * Register with kmsg_dump to save last part of console log on panic.
 563  */
 564 static void pstore_register_kmsg(void)
 565 {
 566         kmsg_dump_register(&pstore_dumper);
 567 }
 568
 569 static void pstore_unregister_kmsg(void)
 570 {
 571         kmsg_dump_unregister(&pstore_dumper);
 572 }
 573
 574 #ifdef CONFIG_PSTORE_CONSOLE
 575 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 576 {
 577         const char *e = s + c;
 578
 579         while (s < e) {
 580                 unsigned long flags;
 581                 u64 id;
 582
 583                 if (c > psinfo->bufsize)
 584                         c = psinfo->bufsize;
 585
 586                 if (oops_in_progress) {
 587                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 588                                 break;
 589                 } else {
 590                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 591                 }
 592                 psinfo->write_buf(PSTORE_TYPE_CONSOLE, 0, &id, 0,
 593                                   s, 0, c, psinfo);
 594                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 595                 s += c;
 596                 c = e - s;
 597         }
 598 }
 599
 600 static struct console pstore_console = {
 601         .name   = "pstore",
 602         .write  = pstore_console_write,
 603         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 604         .index  = -1,
 605 };
 606
 607 static void pstore_register_console(void)
 608 {
 609         register_console(&pstore_console);
 610 }
 611
 612 static void pstore_unregister_console(void)
 613 {
 614         unregister_console(&pstore_console);
 615 }
 616 #else
 617 static void pstore_register_console(void) {}
 618 static void pstore_unregister_console(void) {}
 619 #endif
 620
 621 static int pstore_write_compat(enum pstore_type_id type,
 622                                enum kmsg_dump_reason reason,
 623                                u64 *id, unsigned int part, int count,
 624                                bool compressed, size_t size,
 625                                struct pstore_info *psi)
 626 {
 627         return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
 628                              size, psi);
 629 }
 630
 631 static int pstore_write_buf_user_compat(enum pstore_type_id type,
 632                                enum kmsg_dump_reason reason,
 633                                u64 *id, unsigned int part,
 634                                const char __user *buf,
 635                                bool compressed, size_t size,
 636                                struct pstore_info *psi)
 637 {
 638         unsigned long flags = 0;
 639         size_t i, bufsize = size;
 640         long ret = 0;
 641
 642         if (unlikely(!access_ok(VERIFY_READ, buf, size)))
 643                 return -EFAULT;
 644         if (bufsize > psinfo->bufsize)
 645                 bufsize = psinfo->bufsize;
 646         spin_lock_irqsave(&psinfo->buf_lock, flags);
 647         for (i = 0; i < size; ) {
 648                 size_t c = min(size - i, bufsize);
 649
 650                 ret = __copy_from_user(psinfo->buf, buf + i, c);
 651                 if (unlikely(ret != 0)) {
 652                         ret = -EFAULT;
 653                         break;
 654                 }
 655                 ret = psi->write_buf(type, reason, id, part, psinfo->buf,
 656                                      compressed, c, psi);
 657                 if (unlikely(ret < 0))
 658                         break;
 659                 i += c;
 660         }
 661         spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 662         return unlikely(ret < 0) ? ret : size;
 663 }
 664
 665 /*
 666  * platform specific persistent storage driver registers with
 667  * us here. If pstore is already mounted, call the platform
 668  * read function right away to populate the file system. If not
 669  * then the pstore mount code will call us later to fill out
 670  * the file system.
 671  */
 672 int pstore_register(struct pstore_info *psi)
 673 {
 674         struct module *owner = psi->owner;
 675
 676         if (backend && strcmp(backend, psi->name)) {
 677                 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 678                 return -EPERM;
 679         }
 680
 681         spin_lock(&pstore_lock);
 682         if (psinfo) {
 683                 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 684                         psinfo->name, psi->name);
 685                 spin_unlock(&pstore_lock);
 686                 return -EBUSY;
 687         }
 688
 689         if (!psi->write)
 690                 psi->write = pstore_write_compat;
 691         if (!psi->write_buf_user)
 692                 psi->write_buf_user = pstore_write_buf_user_compat;
 693         psinfo = psi;
 694         mutex_init(&psinfo->read_mutex);
 695         spin_unlock(&pstore_lock);
 696
 697         if (owner && !try_module_get(owner)) {
 698                 psinfo = NULL;
 699                 return -EINVAL;
 700         }
 701
 702         allocate_buf_for_compression();
 703
 704         if (pstore_is_mounted())
 705                 pstore_get_records(0);
 706
 707         if (psi->flags & PSTORE_FLAGS_DMESG)
 708                 pstore_register_kmsg();
 709         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 710                 pstore_register_console();
 711         if (psi->flags & PSTORE_FLAGS_FTRACE)
 712                 pstore_register_ftrace();
 713         if (psi->flags & PSTORE_FLAGS_PMSG)
 714                 pstore_register_pmsg();
 715
 716         /* Start watching for new records, if desired. */
 717         if (pstore_update_ms >= 0) {
 718                 pstore_timer.expires = jiffies +
 719                         msecs_to_jiffies(pstore_update_ms);
 720                 add_timer(&pstore_timer);
 721         }
 722
 723         /*
 724          * Update the module parameter backend, so it is visible
 725          * through /sys/module/pstore/parameters/backend
 726          */
 727         backend = psi->name;
 728
 729         pr_info("Registered %s as persistent store backend\n", psi->name);
 730
 731         module_put(owner);
 732
 733         return 0;
 734 }
 735 EXPORT_SYMBOL_GPL(pstore_register);
 736
 737 void pstore_unregister(struct pstore_info *psi)
 738 {
 739         /* Stop timer and make sure all work has finished. */
 740         pstore_update_ms = -1;
 741         del_timer_sync(&pstore_timer);
 742         flush_work(&pstore_work);
 743
 744         if (psi->flags & PSTORE_FLAGS_PMSG)
 745                 pstore_unregister_pmsg();
 746         if (psi->flags & PSTORE_FLAGS_FTRACE)
 747                 pstore_unregister_ftrace();
 748         if (psi->flags & PSTORE_FLAGS_CONSOLE)
 749                 pstore_unregister_console();
 750         if (psi->flags & PSTORE_FLAGS_DMESG)
 751                 pstore_unregister_kmsg();
 752
 753         free_buf_for_compression();
 754
 755         psinfo = NULL;
 756         backend = NULL;
 757 }
 758 EXPORT_SYMBOL_GPL(pstore_unregister);
 759
 760 static void decompress_record(struct pstore_record *record)
 761 {
 762         int unzipped_len;
 763
 764         /* Only PSTORE_TYPE_DMESG support compression. */
 765         if (!record->compressed || record->type != PSTORE_TYPE_DMESG) {
 766                 pr_warn("ignored compressed record type %d\n", record->type);
 767                 return;
 768         }
 769
 770         /* No compression method has created the common buffer. */
 771         if (!big_oops_buf) {
 772                 pr_warn("no decompression buffer allocated\n");
 773                 return;
 774         }
 775
 776         unzipped_len = pstore_decompress(record->buf, big_oops_buf,
 777                                          record->size, big_oops_buf_sz);
 778         if (unzipped_len > 0) {
 779                 if (record->ecc_notice_size)
 780                         memcpy(big_oops_buf + unzipped_len,
 781                                record->buf + record->size,
 782                                record->ecc_notice_size);
 783                 kfree(record->buf);
 784                 record->buf = big_oops_buf;
 785                 record->size = unzipped_len;
 786                 record->compressed = false;
 787         } else
 788                 pr_err("decompression failed: %d\n", unzipped_len);
 789 }
 790
 791 /*
 792  * Read all the records from the persistent store. Create
 793  * files in our filesystem.  Don't warn about -EEXIST errors
 794  * when we are re-scanning the backing store looking to add new
 795  * error records.
 796  */
 797 void pstore_get_records(int quiet)
 798 {
 799         struct pstore_info *psi = psinfo;
 800         struct pstore_record    record = { .psi = psi, };
 801         int                     failed = 0, rc;
 802
 803         if (!psi)
 804                 return;
 805
 806         mutex_lock(&psi->read_mutex);
 807         if (psi->open && psi->open(psi))
 808                 goto out;
 809
 810         while ((record.size = psi->read(&record)) > 0) {
 811                 decompress_record(&record);
 812                 rc = pstore_mkfile(&record);
 813
 814                 /* Free buffer other than big oops */
 815                 if (record.buf != big_oops_buf)
 816                         kfree(record.buf);
 817
 818                 if (rc && (rc != -EEXIST || !quiet))
 819                         failed++;
 820
 821                 memset(&record, 0, sizeof(record));
 822                 record.psi = psi;
 823         }
 824         if (psi->close)
 825                 psi->close(psi);
 826 out:
 827         mutex_unlock(&psi->read_mutex);
 828
 829         if (failed)
 830                 pr_warn("failed to load %d record(s) from '%s'\n",
 831                         failed, psi->name);
 832 }
 833
 834 static void pstore_dowork(struct work_struct *work)
 835 {
 836         pstore_get_records(1);
 837 }
 838
 839 static void pstore_timefunc(unsigned long dummy)
 840 {
 841         if (pstore_new_entry) {
 842                 pstore_new_entry = 0;
 843                 schedule_work(&pstore_work);
 844         }
 845
 846         if (pstore_update_ms >= 0)
 847                 mod_timer(&pstore_timer,
 848                           jiffies + msecs_to_jiffies(pstore_update_ms));
 849 }
 850
 851 module_param(backend, charp, 0444);
 852 MODULE_PARM_DESC(backend, "Pstore backend to use");