kernel/locking/lockdep_proc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * kernel/lockdep_proc.c
   4  *
   5  * Runtime locking correctness validator
   6  *
   7  * Started by Ingo Molnar:
   8  *
   9  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  10  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
  11  *
  12  * Code for /proc/lockdep and /proc/lockdep_stats:
  13  *
  14  */
  15 #include <linux/export.h>
  16 #include <linux/proc_fs.h>
  17 #include <linux/seq_file.h>
  18 #include <linux/kallsyms.h>
  19 #include <linux/debug_locks.h>
  20 #include <linux/vmalloc.h>
  21 #include <linux/sort.h>
  22 #include <linux/uaccess.h>
  23 #include <asm/div64.h>
  24
  25 #include "lockdep_internals.h"
  26
  27 static void *l_next(struct seq_file *m, void *v, loff_t *pos)
  28 {
  29         return seq_list_next(v, &all_lock_classes, pos);
  30 }
  31
  32 static void *l_start(struct seq_file *m, loff_t *pos)
  33 {
  34         return seq_list_start_head(&all_lock_classes, *pos);
  35 }
  36
  37 static void l_stop(struct seq_file *m, void *v)
  38 {
  39 }
  40
  41 static void print_name(struct seq_file *m, struct lock_class *class)
  42 {
  43         char str[KSYM_NAME_LEN];
  44         const char *name = class->name;
  45
  46         if (!name) {
  47                 name = __get_key_name(class->key, str);
  48                 seq_printf(m, "%s", name);
  49         } else{
  50                 seq_printf(m, "%s", name);
  51                 if (class->name_version > 1)
  52                         seq_printf(m, "#%d", class->name_version);
  53                 if (class->subclass)
  54                         seq_printf(m, "/%d", class->subclass);
  55         }
  56 }
  57
  58 static int l_show(struct seq_file *m, void *v)
  59 {
  60         struct lock_class *class = list_entry(v, struct lock_class, lock_entry);
  61         struct lock_list *entry;
  62         char usage[LOCK_USAGE_CHARS];
  63
  64         if (v == &all_lock_classes) {
  65                 seq_printf(m, "all lock classes:\n");
  66                 return 0;
  67         }
  68
  69         seq_printf(m, "%p", class->key);
  70 #ifdef CONFIG_DEBUG_LOCKDEP
  71         seq_printf(m, " OPS:%8ld", debug_class_ops_read(class));
  72 #endif
  73 #ifdef CONFIG_PROVE_LOCKING
  74         seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class));
  75         seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class));
  76 #endif
  77
  78         get_usage_chars(class, usage);
  79         seq_printf(m, " %s", usage);
  80
  81         seq_printf(m, ": ");
  82         print_name(m, class);
  83         seq_puts(m, "\n");
  84
  85         list_for_each_entry(entry, &class->locks_after, entry) {
  86                 if (entry->distance == 1) {
  87                         seq_printf(m, " -> [%p] ", entry->class->key);
  88                         print_name(m, entry->class);
  89                         seq_puts(m, "\n");
  90                 }
  91         }
  92         seq_puts(m, "\n");
  93
  94         return 0;
  95 }
  96
  97 static const struct seq_operations lockdep_ops = {
  98         .start  = l_start,
  99         .next   = l_next,
 100         .stop   = l_stop,
 101         .show   = l_show,
 102 };
 103
 104 #ifdef CONFIG_PROVE_LOCKING
 105 static void *lc_start(struct seq_file *m, loff_t *pos)
 106 {
 107         if (*pos < 0)
 108                 return NULL;
 109
 110         if (*pos == 0)
 111                 return SEQ_START_TOKEN;
 112
 113         return lock_chains + (*pos - 1);
 114 }
 115
 116 static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
 117 {
 118         *pos = lockdep_next_lockchain(*pos - 1) + 1;
 119         return lc_start(m, pos);
 120 }
 121
 122 static void lc_stop(struct seq_file *m, void *v)
 123 {
 124 }
 125
 126 static int lc_show(struct seq_file *m, void *v)
 127 {
 128         struct lock_chain *chain = v;
 129         struct lock_class *class;
 130         int i;
 131
 132         if (v == SEQ_START_TOKEN) {
 133                 if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)
 134                         seq_printf(m, "(buggered) ");
 135                 seq_printf(m, "all lock chains:\n");
 136                 return 0;
 137         }
 138
 139         seq_printf(m, "irq_context: %d\n", chain->irq_context);
 140
 141         for (i = 0; i < chain->depth; i++) {
 142                 class = lock_chain_get_class(chain, i);
 143                 if (!class->key)
 144                         continue;
 145
 146                 seq_printf(m, "[%p] ", class->key);
 147                 print_name(m, class);
 148                 seq_puts(m, "\n");
 149         }
 150         seq_puts(m, "\n");
 151
 152         return 0;
 153 }
 154
 155 static const struct seq_operations lockdep_chains_ops = {
 156         .start  = lc_start,
 157         .next   = lc_next,
 158         .stop   = lc_stop,
 159         .show   = lc_show,
 160 };
 161 #endif /* CONFIG_PROVE_LOCKING */
 162
 163 static void lockdep_stats_debug_show(struct seq_file *m)
 164 {
 165 #ifdef CONFIG_DEBUG_LOCKDEP
 166         unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
 167                            hi2 = debug_atomic_read(hardirqs_off_events),
 168                            hr1 = debug_atomic_read(redundant_hardirqs_on),
 169                            hr2 = debug_atomic_read(redundant_hardirqs_off),
 170                            si1 = debug_atomic_read(softirqs_on_events),
 171                            si2 = debug_atomic_read(softirqs_off_events),
 172                            sr1 = debug_atomic_read(redundant_softirqs_on),
 173                            sr2 = debug_atomic_read(redundant_softirqs_off);
 174
 175         seq_printf(m, " chain lookup misses:           %11llu\n",
 176                 debug_atomic_read(chain_lookup_misses));
 177         seq_printf(m, " chain lookup hits:             %11llu\n",
 178                 debug_atomic_read(chain_lookup_hits));
 179         seq_printf(m, " cyclic checks:                 %11llu\n",
 180                 debug_atomic_read(nr_cyclic_checks));
 181         seq_printf(m, " redundant checks:              %11llu\n",
 182                 debug_atomic_read(nr_redundant_checks));
 183         seq_printf(m, " redundant links:               %11llu\n",
 184                 debug_atomic_read(nr_redundant));
 185         seq_printf(m, " find-mask forwards checks:     %11llu\n",
 186                 debug_atomic_read(nr_find_usage_forwards_checks));
 187         seq_printf(m, " find-mask backwards checks:    %11llu\n",
 188                 debug_atomic_read(nr_find_usage_backwards_checks));
 189
 190         seq_printf(m, " hardirq on events:             %11llu\n", hi1);
 191         seq_printf(m, " hardirq off events:            %11llu\n", hi2);
 192         seq_printf(m, " redundant hardirq ons:         %11llu\n", hr1);
 193         seq_printf(m, " redundant hardirq offs:        %11llu\n", hr2);
 194         seq_printf(m, " softirq on events:             %11llu\n", si1);
 195         seq_printf(m, " softirq off events:            %11llu\n", si2);
 196         seq_printf(m, " redundant softirq ons:         %11llu\n", sr1);
 197         seq_printf(m, " redundant softirq offs:        %11llu\n", sr2);
 198 #endif
 199 }
 200
 201 static int lockdep_stats_show(struct seq_file *m, void *v)
 202 {
 203         unsigned long nr_unused = 0, nr_uncategorized = 0,
 204                       nr_irq_safe = 0, nr_irq_unsafe = 0,
 205                       nr_softirq_safe = 0, nr_softirq_unsafe = 0,
 206                       nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
 207                       nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
 208                       nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
 209                       nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
 210                       sum_forward_deps = 0;
 211
 212 #ifdef CONFIG_PROVE_LOCKING
 213         struct lock_class *class;
 214
 215         list_for_each_entry(class, &all_lock_classes, lock_entry) {
 216
 217                 if (class->usage_mask == 0)
 218                         nr_unused++;
 219                 if (class->usage_mask == LOCKF_USED)
 220                         nr_uncategorized++;
 221                 if (class->usage_mask & LOCKF_USED_IN_IRQ)
 222                         nr_irq_safe++;
 223                 if (class->usage_mask & LOCKF_ENABLED_IRQ)
 224                         nr_irq_unsafe++;
 225                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
 226                         nr_softirq_safe++;
 227                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
 228                         nr_softirq_unsafe++;
 229                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
 230                         nr_hardirq_safe++;
 231                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
 232                         nr_hardirq_unsafe++;
 233                 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
 234                         nr_irq_read_safe++;
 235                 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
 236                         nr_irq_read_unsafe++;
 237                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
 238                         nr_softirq_read_safe++;
 239                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
 240                         nr_softirq_read_unsafe++;
 241                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
 242                         nr_hardirq_read_safe++;
 243                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
 244                         nr_hardirq_read_unsafe++;
 245
 246                 sum_forward_deps += lockdep_count_forward_deps(class);
 247         }
 248 #ifdef CONFIG_DEBUG_LOCKDEP
 249         DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
 250 #endif
 251
 252 #endif
 253         seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
 254                         nr_lock_classes, MAX_LOCKDEP_KEYS);
 255         seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
 256                         nr_list_entries, MAX_LOCKDEP_ENTRIES);
 257         seq_printf(m, " indirect dependencies:         %11lu\n",
 258                         sum_forward_deps);
 259
 260         /*
 261          * Total number of dependencies:
 262          *
 263          * All irq-safe locks may nest inside irq-unsafe locks,
 264          * plus all the other known dependencies:
 265          */
 266         seq_printf(m, " all direct dependencies:       %11lu\n",
 267                         nr_irq_unsafe * nr_irq_safe +
 268                         nr_hardirq_unsafe * nr_hardirq_safe +
 269                         nr_list_entries);
 270
 271 #ifdef CONFIG_PROVE_LOCKING
 272         seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
 273                         lock_chain_count(), MAX_LOCKDEP_CHAINS);
 274         seq_printf(m, " dependency chain hlocks:       %11d [max: %lu]\n",
 275                         nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
 276 #endif
 277
 278 #ifdef CONFIG_TRACE_IRQFLAGS
 279         seq_printf(m, " in-hardirq chains:             %11u\n",
 280                         nr_hardirq_chains);
 281         seq_printf(m, " in-softirq chains:             %11u\n",
 282                         nr_softirq_chains);
 283 #endif
 284         seq_printf(m, " in-process chains:             %11u\n",
 285                         nr_process_chains);
 286         seq_printf(m, " stack-trace entries:           %11lu [max: %lu]\n",
 287                         nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
 288 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
 289         seq_printf(m, " number of stack traces:        %11llu\n",
 290                    lockdep_stack_trace_count());
 291         seq_printf(m, " number of stack hash chains:   %11llu\n",
 292                    lockdep_stack_hash_count());
 293 #endif
 294         seq_printf(m, " combined max dependencies:     %11u\n",
 295                         (nr_hardirq_chains + 1) *
 296                         (nr_softirq_chains + 1) *
 297                         (nr_process_chains + 1)
 298         );
 299         seq_printf(m, " hardirq-safe locks:            %11lu\n",
 300                         nr_hardirq_safe);
 301         seq_printf(m, " hardirq-unsafe locks:          %11lu\n",
 302                         nr_hardirq_unsafe);
 303         seq_printf(m, " softirq-safe locks:            %11lu\n",
 304                         nr_softirq_safe);
 305         seq_printf(m, " softirq-unsafe locks:          %11lu\n",
 306                         nr_softirq_unsafe);
 307         seq_printf(m, " irq-safe locks:                %11lu\n",
 308                         nr_irq_safe);
 309         seq_printf(m, " irq-unsafe locks:              %11lu\n",
 310                         nr_irq_unsafe);
 311
 312         seq_printf(m, " hardirq-read-safe locks:       %11lu\n",
 313                         nr_hardirq_read_safe);
 314         seq_printf(m, " hardirq-read-unsafe locks:     %11lu\n",
 315                         nr_hardirq_read_unsafe);
 316         seq_printf(m, " softirq-read-safe locks:       %11lu\n",
 317                         nr_softirq_read_safe);
 318         seq_printf(m, " softirq-read-unsafe locks:     %11lu\n",
 319                         nr_softirq_read_unsafe);
 320         seq_printf(m, " irq-read-safe locks:           %11lu\n",
 321                         nr_irq_read_safe);
 322         seq_printf(m, " irq-read-unsafe locks:         %11lu\n",
 323                         nr_irq_read_unsafe);
 324
 325         seq_printf(m, " uncategorized locks:           %11lu\n",
 326                         nr_uncategorized);
 327         seq_printf(m, " unused locks:                  %11lu\n",
 328                         nr_unused);
 329         seq_printf(m, " max locking depth:             %11u\n",
 330                         max_lockdep_depth);
 331 #ifdef CONFIG_PROVE_LOCKING
 332         seq_printf(m, " max bfs queue depth:           %11u\n",
 333                         max_bfs_queue_depth);
 334 #endif
 335         lockdep_stats_debug_show(m);
 336         seq_printf(m, " debug_locks:                   %11u\n",
 337                         debug_locks);
 338
 339         return 0;
 340 }
 341
 342 #ifdef CONFIG_LOCK_STAT
 343
 344 struct lock_stat_data {
 345         struct lock_class *class;
 346         struct lock_class_stats stats;
 347 };
 348
 349 struct lock_stat_seq {
 350         struct lock_stat_data *iter_end;
 351         struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
 352 };
 353
 354 /*
 355  * sort on absolute number of contentions
 356  */
 357 static int lock_stat_cmp(const void *l, const void *r)
 358 {
 359         const struct lock_stat_data *dl = l, *dr = r;
 360         unsigned long nl, nr;
 361
 362         nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
 363         nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
 364
 365         return nr - nl;
 366 }
 367
 368 static void seq_line(struct seq_file *m, char c, int offset, int length)
 369 {
 370         int i;
 371
 372         for (i = 0; i < offset; i++)
 373                 seq_puts(m, " ");
 374         for (i = 0; i < length; i++)
 375                 seq_printf(m, "%c", c);
 376         seq_puts(m, "\n");
 377 }
 378
 379 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
 380 {
 381         s64 div;
 382         s32 rem;
 383
 384         nr += 5; /* for display rounding */
 385         div = div_s64_rem(nr, 1000, &rem);
 386         snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
 387 }
 388
 389 static void seq_time(struct seq_file *m, s64 time)
 390 {
 391         char num[15];
 392
 393         snprint_time(num, sizeof(num), time);
 394         seq_printf(m, " %14s", num);
 395 }
 396
 397 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
 398 {
 399         seq_printf(m, "%14lu", lt->nr);
 400         seq_time(m, lt->min);
 401         seq_time(m, lt->max);
 402         seq_time(m, lt->total);
 403         seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0);
 404 }
 405
 406 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 407 {
 408         const struct lockdep_subclass_key *ckey;
 409         struct lock_class_stats *stats;
 410         struct lock_class *class;
 411         const char *cname;
 412         int i, namelen;
 413         char name[39];
 414
 415         class = data->class;
 416         stats = &data->stats;
 417
 418         namelen = 38;
 419         if (class->name_version > 1)
 420                 namelen -= 2; /* XXX truncates versions > 9 */
 421         if (class->subclass)
 422                 namelen -= 2;
 423
 424         rcu_read_lock_sched();
 425         cname = rcu_dereference_sched(class->name);
 426         ckey  = rcu_dereference_sched(class->key);
 427
 428         if (!cname && !ckey) {
 429                 rcu_read_unlock_sched();
 430                 return;
 431
 432         } else if (!cname) {
 433                 char str[KSYM_NAME_LEN];
 434                 const char *key_name;
 435
 436                 key_name = __get_key_name(ckey, str);
 437                 snprintf(name, namelen, "%s", key_name);
 438         } else {
 439                 snprintf(name, namelen, "%s", cname);
 440         }
 441         rcu_read_unlock_sched();
 442
 443         namelen = strlen(name);
 444         if (class->name_version > 1) {
 445                 snprintf(name+namelen, 3, "#%d", class->name_version);
 446                 namelen += 2;
 447         }
 448         if (class->subclass) {
 449                 snprintf(name+namelen, 3, "/%d", class->subclass);
 450                 namelen += 2;
 451         }
 452
 453         if (stats->write_holdtime.nr) {
 454                 if (stats->read_holdtime.nr)
 455                         seq_printf(m, "%38s-W:", name);
 456                 else
 457                         seq_printf(m, "%40s:", name);
 458
 459                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
 460                 seq_lock_time(m, &stats->write_waittime);
 461                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
 462                 seq_lock_time(m, &stats->write_holdtime);
 463                 seq_puts(m, "\n");
 464         }
 465
 466         if (stats->read_holdtime.nr) {
 467                 seq_printf(m, "%38s-R:", name);
 468                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
 469                 seq_lock_time(m, &stats->read_waittime);
 470                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
 471                 seq_lock_time(m, &stats->read_holdtime);
 472                 seq_puts(m, "\n");
 473         }
 474
 475         if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
 476                 return;
 477
 478         if (stats->read_holdtime.nr)
 479                 namelen += 2;
 480
 481         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 482                 char ip[32];
 483
 484                 if (class->contention_point[i] == 0)
 485                         break;
 486
 487                 if (!i)
 488                         seq_line(m, '-', 40-namelen, namelen);
 489
 490                 snprintf(ip, sizeof(ip), "[<%p>]",
 491                                 (void *)class->contention_point[i]);
 492                 seq_printf(m, "%40s %14lu %29s %pS\n",
 493                            name, stats->contention_point[i],
 494                            ip, (void *)class->contention_point[i]);
 495         }
 496         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 497                 char ip[32];
 498
 499                 if (class->contending_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->contending_point[i]);
 507                 seq_printf(m, "%40s %14lu %29s %pS\n",
 508                            name, stats->contending_point[i],
 509                            ip, (void *)class->contending_point[i]);
 510         }
 511         if (i) {
 512                 seq_puts(m, "\n");
 513                 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
 514                 seq_puts(m, "\n");
 515         }
 516 }
 517
 518 static void seq_header(struct seq_file *m)
 519 {
 520         seq_puts(m, "lock_stat version 0.4\n");
 521
 522         if (unlikely(!debug_locks))
 523                 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
 524
 525         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 526         seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
 527                         "%14s %14s\n",
 528                         "class name",
 529                         "con-bounces",
 530                         "contentions",
 531                         "waittime-min",
 532                         "waittime-max",
 533                         "waittime-total",
 534                         "waittime-avg",
 535                         "acq-bounces",
 536                         "acquisitions",
 537                         "holdtime-min",
 538                         "holdtime-max",
 539                         "holdtime-total",
 540                         "holdtime-avg");
 541         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 542         seq_printf(m, "\n");
 543 }
 544
 545 static void *ls_start(struct seq_file *m, loff_t *pos)
 546 {
 547         struct lock_stat_seq *data = m->private;
 548         struct lock_stat_data *iter;
 549
 550         if (*pos == 0)
 551                 return SEQ_START_TOKEN;
 552
 553         iter = data->stats + (*pos - 1);
 554         if (iter >= data->iter_end)
 555                 iter = NULL;
 556
 557         return iter;
 558 }
 559
 560 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
 561 {
 562         (*pos)++;
 563         return ls_start(m, pos);
 564 }
 565
 566 static void ls_stop(struct seq_file *m, void *v)
 567 {
 568 }
 569
 570 static int ls_show(struct seq_file *m, void *v)
 571 {
 572         if (v == SEQ_START_TOKEN)
 573                 seq_header(m);
 574         else
 575                 seq_stats(m, v);
 576
 577         return 0;
 578 }
 579
 580 static const struct seq_operations lockstat_ops = {
 581         .start  = ls_start,
 582         .next   = ls_next,
 583         .stop   = ls_stop,
 584         .show   = ls_show,
 585 };
 586
 587 static int lock_stat_open(struct inode *inode, struct file *file)
 588 {
 589         int res;
 590         struct lock_class *class;
 591         struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
 592
 593         if (!data)
 594                 return -ENOMEM;
 595
 596         res = seq_open(file, &lockstat_ops);
 597         if (!res) {
 598                 struct lock_stat_data *iter = data->stats;
 599                 struct seq_file *m = file->private_data;
 600
 601                 list_for_each_entry(class, &all_lock_classes, lock_entry) {
 602                         iter->class = class;
 603                         iter->stats = lock_stats(class);
 604                         iter++;
 605                 }
 606                 data->iter_end = iter;
 607
 608                 sort(data->stats, data->iter_end - data->stats,
 609                                 sizeof(struct lock_stat_data),
 610                                 lock_stat_cmp, NULL);
 611
 612                 m->private = data;
 613         } else
 614                 vfree(data);
 615
 616         return res;
 617 }
 618
 619 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
 620                                size_t count, loff_t *ppos)
 621 {
 622         struct lock_class *class;
 623         char c;
 624
 625         if (count) {
 626                 if (get_user(c, buf))
 627                         return -EFAULT;
 628
 629                 if (c != '0')
 630                         return count;
 631
 632                 list_for_each_entry(class, &all_lock_classes, lock_entry)
 633                         clear_lock_stats(class);
 634         }
 635         return count;
 636 }
 637
 638 static int lock_stat_release(struct inode *inode, struct file *file)
 639 {
 640         struct seq_file *seq = file->private_data;
 641
 642         vfree(seq->private);
 643         return seq_release(inode, file);
 644 }
 645
 646 static const struct proc_ops lock_stat_proc_ops = {
 647         .proc_open      = lock_stat_open,
 648         .proc_write     = lock_stat_write,
 649         .proc_read      = seq_read,
 650         .proc_lseek     = seq_lseek,
 651         .proc_release   = lock_stat_release,
 652 };
 653 #endif /* CONFIG_LOCK_STAT */
 654
 655 static int __init lockdep_proc_init(void)
 656 {
 657         proc_create_seq("lockdep", S_IRUSR, NULL, &lockdep_ops);
 658 #ifdef CONFIG_PROVE_LOCKING
 659         proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops);
 660 #endif
 661         proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show);
 662 #ifdef CONFIG_LOCK_STAT
 663         proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL, &lock_stat_proc_ops);
 664 #endif
 665
 666         return 0;
 667 }
 668
 669 __initcall(lockdep_proc_init);
 670