kernel/lockdep_proc.c

   1 /*
   2  * kernel/lockdep_proc.c
   3  *
   4  * Runtime locking correctness validator
   5  *
   6  * Started by Ingo Molnar:
   7  *
   8  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
  10  *
  11  * Code for /proc/lockdep and /proc/lockdep_stats:
  12  *
  13  */
  14 #include <linux/module.h>
  15 #include <linux/proc_fs.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/kallsyms.h>
  18 #include <linux/debug_locks.h>
  19 #include <linux/vmalloc.h>
  20 #include <linux/sort.h>
  21 #include <asm/uaccess.h>
  22 #include <asm/div64.h>
  23
  24 #include "lockdep_internals.h"
  25
  26 static void *l_next(struct seq_file *m, void *v, loff_t *pos)
  27 {
  28         return seq_list_next(v, &all_lock_classes, pos);
  29 }
  30
  31 static void *l_start(struct seq_file *m, loff_t *pos)
  32 {
  33         return seq_list_start_head(&all_lock_classes, *pos);
  34 }
  35
  36 static void l_stop(struct seq_file *m, void *v)
  37 {
  38 }
  39
  40 static void print_name(struct seq_file *m, struct lock_class *class)
  41 {
  42         char str[128];
  43         const char *name = class->name;
  44
  45         if (!name) {
  46                 name = __get_key_name(class->key, str);
  47                 seq_printf(m, "%s", name);
  48         } else{
  49                 seq_printf(m, "%s", name);
  50                 if (class->name_version > 1)
  51                         seq_printf(m, "#%d", class->name_version);
  52                 if (class->subclass)
  53                         seq_printf(m, "/%d", class->subclass);
  54         }
  55 }
  56
  57 static int l_show(struct seq_file *m, void *v)
  58 {
  59         struct lock_class *class = list_entry(v, struct lock_class, lock_entry);
  60         struct lock_list *entry;
  61         char usage[LOCK_USAGE_CHARS];
  62
  63         if (v == &all_lock_classes) {
  64                 seq_printf(m, "all lock classes:\n");
  65                 return 0;
  66         }
  67
  68         seq_printf(m, "%p", class->key);
  69 #ifdef CONFIG_DEBUG_LOCKDEP
  70         seq_printf(m, " OPS:%8ld", class->ops);
  71 #endif
  72 #ifdef CONFIG_PROVE_LOCKING
  73         seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class));
  74         seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class));
  75 #endif
  76
  77         get_usage_chars(class, usage);
  78         seq_printf(m, " %s", usage);
  79
  80         seq_printf(m, ": ");
  81         print_name(m, class);
  82         seq_puts(m, "\n");
  83
  84         list_for_each_entry(entry, &class->locks_after, entry) {
  85                 if (entry->distance == 1) {
  86                         seq_printf(m, " -> [%p] ", entry->class->key);
  87                         print_name(m, entry->class);
  88                         seq_puts(m, "\n");
  89                 }
  90         }
  91         seq_puts(m, "\n");
  92
  93         return 0;
  94 }
  95
  96 static const struct seq_operations lockdep_ops = {
  97         .start  = l_start,
  98         .next   = l_next,
  99         .stop   = l_stop,
 100         .show   = l_show,
 101 };
 102
 103 static int lockdep_open(struct inode *inode, struct file *file)
 104 {
 105         return seq_open(file, &lockdep_ops);
 106 }
 107
 108 static const struct file_operations proc_lockdep_operations = {
 109         .open           = lockdep_open,
 110         .read           = seq_read,
 111         .llseek         = seq_lseek,
 112         .release        = seq_release,
 113 };
 114
 115 #ifdef CONFIG_PROVE_LOCKING
 116 static void *lc_start(struct seq_file *m, loff_t *pos)
 117 {
 118         if (*pos == 0)
 119                 return SEQ_START_TOKEN;
 120
 121         if (*pos - 1 < nr_lock_chains)
 122                 return lock_chains + (*pos - 1);
 123
 124         return NULL;
 125 }
 126
 127 static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
 128 {
 129         (*pos)++;
 130         return lc_start(m, pos);
 131 }
 132
 133 static void lc_stop(struct seq_file *m, void *v)
 134 {
 135 }
 136
 137 static int lc_show(struct seq_file *m, void *v)
 138 {
 139         struct lock_chain *chain = v;
 140         struct lock_class *class;
 141         int i;
 142
 143         if (v == SEQ_START_TOKEN) {
 144                 seq_printf(m, "all lock chains:\n");
 145                 return 0;
 146         }
 147
 148         seq_printf(m, "irq_context: %d\n", chain->irq_context);
 149
 150         for (i = 0; i < chain->depth; i++) {
 151                 class = lock_chain_get_class(chain, i);
 152                 if (!class->key)
 153                         continue;
 154
 155                 seq_printf(m, "[%p] ", class->key);
 156                 print_name(m, class);
 157                 seq_puts(m, "\n");
 158         }
 159         seq_puts(m, "\n");
 160
 161         return 0;
 162 }
 163
 164 static const struct seq_operations lockdep_chains_ops = {
 165         .start  = lc_start,
 166         .next   = lc_next,
 167         .stop   = lc_stop,
 168         .show   = lc_show,
 169 };
 170
 171 static int lockdep_chains_open(struct inode *inode, struct file *file)
 172 {
 173         return seq_open(file, &lockdep_chains_ops);
 174 }
 175
 176 static const struct file_operations proc_lockdep_chains_operations = {
 177         .open           = lockdep_chains_open,
 178         .read           = seq_read,
 179         .llseek         = seq_lseek,
 180         .release        = seq_release,
 181 };
 182 #endif /* CONFIG_PROVE_LOCKING */
 183
 184 static void lockdep_stats_debug_show(struct seq_file *m)
 185 {
 186 #ifdef CONFIG_DEBUG_LOCKDEP
 187         unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
 188                            hi2 = debug_atomic_read(hardirqs_off_events),
 189                            hr1 = debug_atomic_read(redundant_hardirqs_on),
 190                            hr2 = debug_atomic_read(redundant_hardirqs_off),
 191                            si1 = debug_atomic_read(softirqs_on_events),
 192                            si2 = debug_atomic_read(softirqs_off_events),
 193                            sr1 = debug_atomic_read(redundant_softirqs_on),
 194                            sr2 = debug_atomic_read(redundant_softirqs_off);
 195
 196         seq_printf(m, " chain lookup misses:           %11llu\n",
 197                 debug_atomic_read(chain_lookup_misses));
 198         seq_printf(m, " chain lookup hits:             %11llu\n",
 199                 debug_atomic_read(chain_lookup_hits));
 200         seq_printf(m, " cyclic checks:                 %11llu\n",
 201                 debug_atomic_read(nr_cyclic_checks));
 202         seq_printf(m, " find-mask forwards checks:     %11llu\n",
 203                 debug_atomic_read(nr_find_usage_forwards_checks));
 204         seq_printf(m, " find-mask backwards checks:    %11llu\n",
 205                 debug_atomic_read(nr_find_usage_backwards_checks));
 206
 207         seq_printf(m, " hardirq on events:             %11llu\n", hi1);
 208         seq_printf(m, " hardirq off events:            %11llu\n", hi2);
 209         seq_printf(m, " redundant hardirq ons:         %11llu\n", hr1);
 210         seq_printf(m, " redundant hardirq offs:        %11llu\n", hr2);
 211         seq_printf(m, " softirq on events:             %11llu\n", si1);
 212         seq_printf(m, " softirq off events:            %11llu\n", si2);
 213         seq_printf(m, " redundant softirq ons:         %11llu\n", sr1);
 214         seq_printf(m, " redundant softirq offs:        %11llu\n", sr2);
 215 #endif
 216 }
 217
 218 static int lockdep_stats_show(struct seq_file *m, void *v)
 219 {
 220         struct lock_class *class;
 221         unsigned long nr_unused = 0, nr_uncategorized = 0,
 222                       nr_irq_safe = 0, nr_irq_unsafe = 0,
 223                       nr_softirq_safe = 0, nr_softirq_unsafe = 0,
 224                       nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
 225                       nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
 226                       nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
 227                       nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
 228                       sum_forward_deps = 0, factor = 0;
 229
 230         list_for_each_entry(class, &all_lock_classes, lock_entry) {
 231
 232                 if (class->usage_mask == 0)
 233                         nr_unused++;
 234                 if (class->usage_mask == LOCKF_USED)
 235                         nr_uncategorized++;
 236                 if (class->usage_mask & LOCKF_USED_IN_IRQ)
 237                         nr_irq_safe++;
 238                 if (class->usage_mask & LOCKF_ENABLED_IRQ)
 239                         nr_irq_unsafe++;
 240                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
 241                         nr_softirq_safe++;
 242                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
 243                         nr_softirq_unsafe++;
 244                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
 245                         nr_hardirq_safe++;
 246                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
 247                         nr_hardirq_unsafe++;
 248                 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
 249                         nr_irq_read_safe++;
 250                 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
 251                         nr_irq_read_unsafe++;
 252                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
 253                         nr_softirq_read_safe++;
 254                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
 255                         nr_softirq_read_unsafe++;
 256                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
 257                         nr_hardirq_read_safe++;
 258                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
 259                         nr_hardirq_read_unsafe++;
 260
 261 #ifdef CONFIG_PROVE_LOCKING
 262                 sum_forward_deps += lockdep_count_forward_deps(class);
 263 #endif
 264         }
 265 #ifdef CONFIG_DEBUG_LOCKDEP
 266         DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
 267 #endif
 268         seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
 269                         nr_lock_classes, MAX_LOCKDEP_KEYS);
 270         seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
 271                         nr_list_entries, MAX_LOCKDEP_ENTRIES);
 272         seq_printf(m, " indirect dependencies:         %11lu\n",
 273                         sum_forward_deps);
 274
 275         /*
 276          * Total number of dependencies:
 277          *
 278          * All irq-safe locks may nest inside irq-unsafe locks,
 279          * plus all the other known dependencies:
 280          */
 281         seq_printf(m, " all direct dependencies:       %11lu\n",
 282                         nr_irq_unsafe * nr_irq_safe +
 283                         nr_hardirq_unsafe * nr_hardirq_safe +
 284                         nr_list_entries);
 285
 286         /*
 287          * Estimated factor between direct and indirect
 288          * dependencies:
 289          */
 290         if (nr_list_entries)
 291                 factor = sum_forward_deps / nr_list_entries;
 292
 293 #ifdef CONFIG_PROVE_LOCKING
 294         seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
 295                         nr_lock_chains, MAX_LOCKDEP_CHAINS);
 296         seq_printf(m, " dependency chain hlocks:       %11d [max: %lu]\n",
 297                         nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
 298 #endif
 299
 300 #ifdef CONFIG_TRACE_IRQFLAGS
 301         seq_printf(m, " in-hardirq chains:             %11u\n",
 302                         nr_hardirq_chains);
 303         seq_printf(m, " in-softirq chains:             %11u\n",
 304                         nr_softirq_chains);
 305 #endif
 306         seq_printf(m, " in-process chains:             %11u\n",
 307                         nr_process_chains);
 308         seq_printf(m, " stack-trace entries:           %11lu [max: %lu]\n",
 309                         nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
 310         seq_printf(m, " combined max dependencies:     %11u\n",
 311                         (nr_hardirq_chains + 1) *
 312                         (nr_softirq_chains + 1) *
 313                         (nr_process_chains + 1)
 314         );
 315         seq_printf(m, " hardirq-safe locks:            %11lu\n",
 316                         nr_hardirq_safe);
 317         seq_printf(m, " hardirq-unsafe locks:          %11lu\n",
 318                         nr_hardirq_unsafe);
 319         seq_printf(m, " softirq-safe locks:            %11lu\n",
 320                         nr_softirq_safe);
 321         seq_printf(m, " softirq-unsafe locks:          %11lu\n",
 322                         nr_softirq_unsafe);
 323         seq_printf(m, " irq-safe locks:                %11lu\n",
 324                         nr_irq_safe);
 325         seq_printf(m, " irq-unsafe locks:              %11lu\n",
 326                         nr_irq_unsafe);
 327
 328         seq_printf(m, " hardirq-read-safe locks:       %11lu\n",
 329                         nr_hardirq_read_safe);
 330         seq_printf(m, " hardirq-read-unsafe locks:     %11lu\n",
 331                         nr_hardirq_read_unsafe);
 332         seq_printf(m, " softirq-read-safe locks:       %11lu\n",
 333                         nr_softirq_read_safe);
 334         seq_printf(m, " softirq-read-unsafe locks:     %11lu\n",
 335                         nr_softirq_read_unsafe);
 336         seq_printf(m, " irq-read-safe locks:           %11lu\n",
 337                         nr_irq_read_safe);
 338         seq_printf(m, " irq-read-unsafe locks:         %11lu\n",
 339                         nr_irq_read_unsafe);
 340
 341         seq_printf(m, " uncategorized locks:           %11lu\n",
 342                         nr_uncategorized);
 343         seq_printf(m, " unused locks:                  %11lu\n",
 344                         nr_unused);
 345         seq_printf(m, " max locking depth:             %11u\n",
 346                         max_lockdep_depth);
 347 #ifdef CONFIG_PROVE_LOCKING
 348         seq_printf(m, " max bfs queue depth:           %11u\n",
 349                         max_bfs_queue_depth);
 350 #endif
 351         lockdep_stats_debug_show(m);
 352         seq_printf(m, " debug_locks:                   %11u\n",
 353                         debug_locks);
 354
 355         return 0;
 356 }
 357
 358 static int lockdep_stats_open(struct inode *inode, struct file *file)
 359 {
 360         return single_open(file, lockdep_stats_show, NULL);
 361 }
 362
 363 static const struct file_operations proc_lockdep_stats_operations = {
 364         .open           = lockdep_stats_open,
 365         .read           = seq_read,
 366         .llseek         = seq_lseek,
 367         .release        = single_release,
 368 };
 369
 370 #ifdef CONFIG_LOCK_STAT
 371
 372 struct lock_stat_data {
 373         struct lock_class *class;
 374         struct lock_class_stats stats;
 375 };
 376
 377 struct lock_stat_seq {
 378         struct lock_stat_data *iter_end;
 379         struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
 380 };
 381
 382 /*
 383  * sort on absolute number of contentions
 384  */
 385 static int lock_stat_cmp(const void *l, const void *r)
 386 {
 387         const struct lock_stat_data *dl = l, *dr = r;
 388         unsigned long nl, nr;
 389
 390         nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
 391         nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
 392
 393         return nr - nl;
 394 }
 395
 396 static void seq_line(struct seq_file *m, char c, int offset, int length)
 397 {
 398         int i;
 399
 400         for (i = 0; i < offset; i++)
 401                 seq_puts(m, " ");
 402         for (i = 0; i < length; i++)
 403                 seq_printf(m, "%c", c);
 404         seq_puts(m, "\n");
 405 }
 406
 407 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
 408 {
 409         s64 div;
 410         s32 rem;
 411
 412         nr += 5; /* for display rounding */
 413         div = div_s64_rem(nr, 1000, &rem);
 414         snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
 415 }
 416
 417 static void seq_time(struct seq_file *m, s64 time)
 418 {
 419         char num[15];
 420
 421         snprint_time(num, sizeof(num), time);
 422         seq_printf(m, " %14s", num);
 423 }
 424
 425 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
 426 {
 427         seq_printf(m, "%14lu", lt->nr);
 428         seq_time(m, lt->min);
 429         seq_time(m, lt->max);
 430         seq_time(m, lt->total);
 431 }
 432
 433 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 434 {
 435         char name[39];
 436         struct lock_class *class;
 437         struct lock_class_stats *stats;
 438         int i, namelen;
 439
 440         class = data->class;
 441         stats = &data->stats;
 442
 443         namelen = 38;
 444         if (class->name_version > 1)
 445                 namelen -= 2; /* XXX truncates versions > 9 */
 446         if (class->subclass)
 447                 namelen -= 2;
 448
 449         if (!class->name) {
 450                 char str[KSYM_NAME_LEN];
 451                 const char *key_name;
 452
 453                 key_name = __get_key_name(class->key, str);
 454                 snprintf(name, namelen, "%s", key_name);
 455         } else {
 456                 snprintf(name, namelen, "%s", class->name);
 457         }
 458         namelen = strlen(name);
 459         if (class->name_version > 1) {
 460                 snprintf(name+namelen, 3, "#%d", class->name_version);
 461                 namelen += 2;
 462         }
 463         if (class->subclass) {
 464                 snprintf(name+namelen, 3, "/%d", class->subclass);
 465                 namelen += 2;
 466         }
 467
 468         if (stats->write_holdtime.nr) {
 469                 if (stats->read_holdtime.nr)
 470                         seq_printf(m, "%38s-W:", name);
 471                 else
 472                         seq_printf(m, "%40s:", name);
 473
 474                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
 475                 seq_lock_time(m, &stats->write_waittime);
 476                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
 477                 seq_lock_time(m, &stats->write_holdtime);
 478                 seq_puts(m, "\n");
 479         }
 480
 481         if (stats->read_holdtime.nr) {
 482                 seq_printf(m, "%38s-R:", name);
 483                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
 484                 seq_lock_time(m, &stats->read_waittime);
 485                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
 486                 seq_lock_time(m, &stats->read_holdtime);
 487                 seq_puts(m, "\n");
 488         }
 489
 490         if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
 491                 return;
 492
 493         if (stats->read_holdtime.nr)
 494                 namelen += 2;
 495
 496         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 497                 char ip[32];
 498
 499                 if (class->contention_point[i] == 0)
 500                         break;
 501
 502                 if (!i)
 503                         seq_line(m, '-', 40-namelen, namelen);
 504
 505                 snprintf(ip, sizeof(ip), "[<%p>]",
 506                                 (void *)class->contention_point[i]);
 507                 seq_printf(m, "%40s %14lu %29s %pS\n",
 508                            name, stats->contention_point[i],
 509                            ip, (void *)class->contention_point[i]);
 510         }
 511         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 512                 char ip[32];
 513
 514                 if (class->contending_point[i] == 0)
 515                         break;
 516
 517                 if (!i)
 518                         seq_line(m, '-', 40-namelen, namelen);
 519
 520                 snprintf(ip, sizeof(ip), "[<%p>]",
 521                                 (void *)class->contending_point[i]);
 522                 seq_printf(m, "%40s %14lu %29s %pS\n",
 523                            name, stats->contending_point[i],
 524                            ip, (void *)class->contending_point[i]);
 525         }
 526         if (i) {
 527                 seq_puts(m, "\n");
 528                 seq_line(m, '.', 0, 40 + 1 + 10 * (14 + 1));
 529                 seq_puts(m, "\n");
 530         }
 531 }
 532
 533 static void seq_header(struct seq_file *m)
 534 {
 535         seq_printf(m, "lock_stat version 0.3\n");
 536
 537         if (unlikely(!debug_locks))
 538                 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
 539
 540         seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
 541         seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
 542                         "%14s %14s\n",
 543                         "class name",
 544                         "con-bounces",
 545                         "contentions",
 546                         "waittime-min",
 547                         "waittime-max",
 548                         "waittime-total",
 549                         "acq-bounces",
 550                         "acquisitions",
 551                         "holdtime-min",
 552                         "holdtime-max",
 553                         "holdtime-total");
 554         seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
 555         seq_printf(m, "\n");
 556 }
 557
 558 static void *ls_start(struct seq_file *m, loff_t *pos)
 559 {
 560         struct lock_stat_seq *data = m->private;
 561         struct lock_stat_data *iter;
 562
 563         if (*pos == 0)
 564                 return SEQ_START_TOKEN;
 565
 566         iter = data->stats + (*pos - 1);
 567         if (iter >= data->iter_end)
 568                 iter = NULL;
 569
 570         return iter;
 571 }
 572
 573 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
 574 {
 575         (*pos)++;
 576         return ls_start(m, pos);
 577 }
 578
 579 static void ls_stop(struct seq_file *m, void *v)
 580 {
 581 }
 582
 583 static int ls_show(struct seq_file *m, void *v)
 584 {
 585         if (v == SEQ_START_TOKEN)
 586                 seq_header(m);
 587         else
 588                 seq_stats(m, v);
 589
 590         return 0;
 591 }
 592
 593 static const struct seq_operations lockstat_ops = {
 594         .start  = ls_start,
 595         .next   = ls_next,
 596         .stop   = ls_stop,
 597         .show   = ls_show,
 598 };
 599
 600 static int lock_stat_open(struct inode *inode, struct file *file)
 601 {
 602         int res;
 603         struct lock_class *class;
 604         struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
 605
 606         if (!data)
 607                 return -ENOMEM;
 608
 609         res = seq_open(file, &lockstat_ops);
 610         if (!res) {
 611                 struct lock_stat_data *iter = data->stats;
 612                 struct seq_file *m = file->private_data;
 613
 614                 list_for_each_entry(class, &all_lock_classes, lock_entry) {
 615                         iter->class = class;
 616                         iter->stats = lock_stats(class);
 617                         iter++;
 618                 }
 619                 data->iter_end = iter;
 620
 621                 sort(data->stats, data->iter_end - data->stats,
 622                                 sizeof(struct lock_stat_data),
 623                                 lock_stat_cmp, NULL);
 624
 625                 m->private = data;
 626         } else
 627                 vfree(data);
 628
 629         return res;
 630 }
 631
 632 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
 633                                size_t count, loff_t *ppos)
 634 {
 635         struct lock_class *class;
 636         char c;
 637
 638         if (count) {
 639                 if (get_user(c, buf))
 640                         return -EFAULT;
 641
 642                 if (c != '0')
 643                         return count;
 644
 645                 list_for_each_entry(class, &all_lock_classes, lock_entry)
 646                         clear_lock_stats(class);
 647         }
 648         return count;
 649 }
 650
 651 static int lock_stat_release(struct inode *inode, struct file *file)
 652 {
 653         struct seq_file *seq = file->private_data;
 654
 655         vfree(seq->private);
 656         return seq_release(inode, file);
 657 }
 658
 659 static const struct file_operations proc_lock_stat_operations = {
 660         .open           = lock_stat_open,
 661         .write          = lock_stat_write,
 662         .read           = seq_read,
 663         .llseek         = seq_lseek,
 664         .release        = lock_stat_release,
 665 };
 666 #endif /* CONFIG_LOCK_STAT */
 667
 668 static int __init lockdep_proc_init(void)
 669 {
 670         proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
 671 #ifdef CONFIG_PROVE_LOCKING
 672         proc_create("lockdep_chains", S_IRUSR, NULL,
 673                     &proc_lockdep_chains_operations);
 674 #endif
 675         proc_create("lockdep_stats", S_IRUSR, NULL,
 676                     &proc_lockdep_stats_operations);
 677
 678 #ifdef CONFIG_LOCK_STAT
 679         proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
 680                     &proc_lock_stat_operations);
 681 #endif
 682
 683         return 0;
 684 }
 685
 686 __initcall(lockdep_proc_init);
 687