kernel/locking/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 <[email protected]>
   9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
  10  *
  11  * Code for /proc/lockdep and /proc/lockdep_stats:
  12  *
  13  */
  14 #include <linux/export.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 <linux/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[KSYM_NAME_LEN];
  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                 if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)
 145                         seq_printf(m, "(buggered) ");
 146                 seq_printf(m, "all lock chains:\n");
 147                 return 0;
 148         }
 149
 150         seq_printf(m, "irq_context: %d\n", chain->irq_context);
 151
 152         for (i = 0; i < chain->depth; i++) {
 153                 class = lock_chain_get_class(chain, i);
 154                 if (!class->key)
 155                         continue;
 156
 157                 seq_printf(m, "[%p] ", class->key);
 158                 print_name(m, class);
 159                 seq_puts(m, "\n");
 160         }
 161         seq_puts(m, "\n");
 162
 163         return 0;
 164 }
 165
 166 static const struct seq_operations lockdep_chains_ops = {
 167         .start  = lc_start,
 168         .next   = lc_next,
 169         .stop   = lc_stop,
 170         .show   = lc_show,
 171 };
 172
 173 static int lockdep_chains_open(struct inode *inode, struct file *file)
 174 {
 175         return seq_open(file, &lockdep_chains_ops);
 176 }
 177
 178 static const struct file_operations proc_lockdep_chains_operations = {
 179         .open           = lockdep_chains_open,
 180         .read           = seq_read,
 181         .llseek         = seq_lseek,
 182         .release        = seq_release,
 183 };
 184 #endif /* CONFIG_PROVE_LOCKING */
 185
 186 static void lockdep_stats_debug_show(struct seq_file *m)
 187 {
 188 #ifdef CONFIG_DEBUG_LOCKDEP
 189         unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
 190                            hi2 = debug_atomic_read(hardirqs_off_events),
 191                            hr1 = debug_atomic_read(redundant_hardirqs_on),
 192                            hr2 = debug_atomic_read(redundant_hardirqs_off),
 193                            si1 = debug_atomic_read(softirqs_on_events),
 194                            si2 = debug_atomic_read(softirqs_off_events),
 195                            sr1 = debug_atomic_read(redundant_softirqs_on),
 196                            sr2 = debug_atomic_read(redundant_softirqs_off);
 197
 198         seq_printf(m, " chain lookup misses:           %11llu\n",
 199                 debug_atomic_read(chain_lookup_misses));
 200         seq_printf(m, " chain lookup hits:             %11llu\n",
 201                 debug_atomic_read(chain_lookup_hits));
 202         seq_printf(m, " cyclic checks:                 %11llu\n",
 203                 debug_atomic_read(nr_cyclic_checks));
 204         seq_printf(m, " redundant checks:              %11llu\n",
 205                 debug_atomic_read(nr_redundant_checks));
 206         seq_printf(m, " redundant links:               %11llu\n",
 207                 debug_atomic_read(nr_redundant));
 208         seq_printf(m, " find-mask forwards checks:     %11llu\n",
 209                 debug_atomic_read(nr_find_usage_forwards_checks));
 210         seq_printf(m, " find-mask backwards checks:    %11llu\n",
 211                 debug_atomic_read(nr_find_usage_backwards_checks));
 212
 213         seq_printf(m, " hardirq on events:             %11llu\n", hi1);
 214         seq_printf(m, " hardirq off events:            %11llu\n", hi2);
 215         seq_printf(m, " redundant hardirq ons:         %11llu\n", hr1);
 216         seq_printf(m, " redundant hardirq offs:        %11llu\n", hr2);
 217         seq_printf(m, " softirq on events:             %11llu\n", si1);
 218         seq_printf(m, " softirq off events:            %11llu\n", si2);
 219         seq_printf(m, " redundant softirq ons:         %11llu\n", sr1);
 220         seq_printf(m, " redundant softirq offs:        %11llu\n", sr2);
 221 #endif
 222 }
 223
 224 static int lockdep_stats_show(struct seq_file *m, void *v)
 225 {
 226         struct lock_class *class;
 227         unsigned long nr_unused = 0, nr_uncategorized = 0,
 228                       nr_irq_safe = 0, nr_irq_unsafe = 0,
 229                       nr_softirq_safe = 0, nr_softirq_unsafe = 0,
 230                       nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
 231                       nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
 232                       nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
 233                       nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
 234                       sum_forward_deps = 0;
 235
 236         list_for_each_entry(class, &all_lock_classes, lock_entry) {
 237
 238                 if (class->usage_mask == 0)
 239                         nr_unused++;
 240                 if (class->usage_mask == LOCKF_USED)
 241                         nr_uncategorized++;
 242                 if (class->usage_mask & LOCKF_USED_IN_IRQ)
 243                         nr_irq_safe++;
 244                 if (class->usage_mask & LOCKF_ENABLED_IRQ)
 245                         nr_irq_unsafe++;
 246                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
 247                         nr_softirq_safe++;
 248                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
 249                         nr_softirq_unsafe++;
 250                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
 251                         nr_hardirq_safe++;
 252                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
 253                         nr_hardirq_unsafe++;
 254                 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
 255                         nr_irq_read_safe++;
 256                 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
 257                         nr_irq_read_unsafe++;
 258                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
 259                         nr_softirq_read_safe++;
 260                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
 261                         nr_softirq_read_unsafe++;
 262                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
 263                         nr_hardirq_read_safe++;
 264                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
 265                         nr_hardirq_read_unsafe++;
 266
 267 #ifdef CONFIG_PROVE_LOCKING
 268                 sum_forward_deps += lockdep_count_forward_deps(class);
 269 #endif
 270         }
 271 #ifdef CONFIG_DEBUG_LOCKDEP
 272         DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
 273 #endif
 274         seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
 275                         nr_lock_classes, MAX_LOCKDEP_KEYS);
 276         seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
 277                         nr_list_entries, MAX_LOCKDEP_ENTRIES);
 278         seq_printf(m, " indirect dependencies:         %11lu\n",
 279                         sum_forward_deps);
 280
 281         /*
 282          * Total number of dependencies:
 283          *
 284          * All irq-safe locks may nest inside irq-unsafe locks,
 285          * plus all the other known dependencies:
 286          */
 287         seq_printf(m, " all direct dependencies:       %11lu\n",
 288                         nr_irq_unsafe * nr_irq_safe +
 289                         nr_hardirq_unsafe * nr_hardirq_safe +
 290                         nr_list_entries);
 291
 292 #ifdef CONFIG_PROVE_LOCKING
 293         seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
 294                         nr_lock_chains, MAX_LOCKDEP_CHAINS);
 295         seq_printf(m, " dependency chain hlocks:       %11d [max: %lu]\n",
 296                         nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
 297 #endif
 298
 299 #ifdef CONFIG_TRACE_IRQFLAGS
 300         seq_printf(m, " in-hardirq chains:             %11u\n",
 301                         nr_hardirq_chains);
 302         seq_printf(m, " in-softirq chains:             %11u\n",
 303                         nr_softirq_chains);
 304 #endif
 305         seq_printf(m, " in-process chains:             %11u\n",
 306                         nr_process_chains);
 307         seq_printf(m, " stack-trace entries:           %11lu [max: %lu]\n",
 308                         nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
 309         seq_printf(m, " combined max dependencies:     %11u\n",
 310                         (nr_hardirq_chains + 1) *
 311                         (nr_softirq_chains + 1) *
 312                         (nr_process_chains + 1)
 313         );
 314         seq_printf(m, " hardirq-safe locks:            %11lu\n",
 315                         nr_hardirq_safe);
 316         seq_printf(m, " hardirq-unsafe locks:          %11lu\n",
 317                         nr_hardirq_unsafe);
 318         seq_printf(m, " softirq-safe locks:            %11lu\n",
 319                         nr_softirq_safe);
 320         seq_printf(m, " softirq-unsafe locks:          %11lu\n",
 321                         nr_softirq_unsafe);
 322         seq_printf(m, " irq-safe locks:                %11lu\n",
 323                         nr_irq_safe);
 324         seq_printf(m, " irq-unsafe locks:              %11lu\n",
 325                         nr_irq_unsafe);
 326
 327         seq_printf(m, " hardirq-read-safe locks:       %11lu\n",
 328                         nr_hardirq_read_safe);
 329         seq_printf(m, " hardirq-read-unsafe locks:     %11lu\n",
 330                         nr_hardirq_read_unsafe);
 331         seq_printf(m, " softirq-read-safe locks:       %11lu\n",
 332                         nr_softirq_read_safe);
 333         seq_printf(m, " softirq-read-unsafe locks:     %11lu\n",
 334                         nr_softirq_read_unsafe);
 335         seq_printf(m, " irq-read-safe locks:           %11lu\n",
 336                         nr_irq_read_safe);
 337         seq_printf(m, " irq-read-unsafe locks:         %11lu\n",
 338                         nr_irq_read_unsafe);
 339
 340         seq_printf(m, " uncategorized locks:           %11lu\n",
 341                         nr_uncategorized);
 342         seq_printf(m, " unused locks:                  %11lu\n",
 343                         nr_unused);
 344         seq_printf(m, " max locking depth:             %11u\n",
 345                         max_lockdep_depth);
 346 #ifdef CONFIG_PROVE_LOCKING
 347         seq_printf(m, " max bfs queue depth:           %11u\n",
 348                         max_bfs_queue_depth);
 349 #endif
 350         lockdep_stats_debug_show(m);
 351         seq_printf(m, " debug_locks:                   %11u\n",
 352                         debug_locks);
 353
 354         return 0;
 355 }
 356
 357 static int lockdep_stats_open(struct inode *inode, struct file *file)
 358 {
 359         return single_open(file, lockdep_stats_show, NULL);
 360 }
 361
 362 static const struct file_operations proc_lockdep_stats_operations = {
 363         .open           = lockdep_stats_open,
 364         .read           = seq_read,
 365         .llseek         = seq_lseek,
 366         .release        = single_release,
 367 };
 368
 369 #ifdef CONFIG_LOCK_STAT
 370
 371 struct lock_stat_data {
 372         struct lock_class *class;
 373         struct lock_class_stats stats;
 374 };
 375
 376 struct lock_stat_seq {
 377         struct lock_stat_data *iter_end;
 378         struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
 379 };
 380
 381 /*
 382  * sort on absolute number of contentions
 383  */
 384 static int lock_stat_cmp(const void *l, const void *r)
 385 {
 386         const struct lock_stat_data *dl = l, *dr = r;
 387         unsigned long nl, nr;
 388
 389         nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
 390         nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
 391
 392         return nr - nl;
 393 }
 394
 395 static void seq_line(struct seq_file *m, char c, int offset, int length)
 396 {
 397         int i;
 398
 399         for (i = 0; i < offset; i++)
 400                 seq_puts(m, " ");
 401         for (i = 0; i < length; i++)
 402                 seq_printf(m, "%c", c);
 403         seq_puts(m, "\n");
 404 }
 405
 406 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
 407 {
 408         s64 div;
 409         s32 rem;
 410
 411         nr += 5; /* for display rounding */
 412         div = div_s64_rem(nr, 1000, &rem);
 413         snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
 414 }
 415
 416 static void seq_time(struct seq_file *m, s64 time)
 417 {
 418         char num[15];
 419
 420         snprint_time(num, sizeof(num), time);
 421         seq_printf(m, " %14s", num);
 422 }
 423
 424 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
 425 {
 426         seq_printf(m, "%14lu", lt->nr);
 427         seq_time(m, lt->min);
 428         seq_time(m, lt->max);
 429         seq_time(m, lt->total);
 430         seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0);
 431 }
 432
 433 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 434 {
 435         struct lockdep_subclass_key *ckey;
 436         struct lock_class_stats *stats;
 437         struct lock_class *class;
 438         const char *cname;
 439         int i, namelen;
 440         char name[39];
 441
 442         class = data->class;
 443         stats = &data->stats;
 444
 445         namelen = 38;
 446         if (class->name_version > 1)
 447                 namelen -= 2; /* XXX truncates versions > 9 */
 448         if (class->subclass)
 449                 namelen -= 2;
 450
 451         rcu_read_lock_sched();
 452         cname = rcu_dereference_sched(class->name);
 453         ckey  = rcu_dereference_sched(class->key);
 454
 455         if (!cname && !ckey) {
 456                 rcu_read_unlock_sched();
 457                 return;
 458
 459         } else if (!cname) {
 460                 char str[KSYM_NAME_LEN];
 461                 const char *key_name;
 462
 463                 key_name = __get_key_name(ckey, str);
 464                 snprintf(name, namelen, "%s", key_name);
 465         } else {
 466                 snprintf(name, namelen, "%s", cname);
 467         }
 468         rcu_read_unlock_sched();
 469
 470         namelen = strlen(name);
 471         if (class->name_version > 1) {
 472                 snprintf(name+namelen, 3, "#%d", class->name_version);
 473                 namelen += 2;
 474         }
 475         if (class->subclass) {
 476                 snprintf(name+namelen, 3, "/%d", class->subclass);
 477                 namelen += 2;
 478         }
 479
 480         if (stats->write_holdtime.nr) {
 481                 if (stats->read_holdtime.nr)
 482                         seq_printf(m, "%38s-W:", name);
 483                 else
 484                         seq_printf(m, "%40s:", name);
 485
 486                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
 487                 seq_lock_time(m, &stats->write_waittime);
 488                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
 489                 seq_lock_time(m, &stats->write_holdtime);
 490                 seq_puts(m, "\n");
 491         }
 492
 493         if (stats->read_holdtime.nr) {
 494                 seq_printf(m, "%38s-R:", name);
 495                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
 496                 seq_lock_time(m, &stats->read_waittime);
 497                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
 498                 seq_lock_time(m, &stats->read_holdtime);
 499                 seq_puts(m, "\n");
 500         }
 501
 502         if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
 503                 return;
 504
 505         if (stats->read_holdtime.nr)
 506                 namelen += 2;
 507
 508         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 509                 char ip[32];
 510
 511                 if (class->contention_point[i] == 0)
 512                         break;
 513
 514                 if (!i)
 515                         seq_line(m, '-', 40-namelen, namelen);
 516
 517                 snprintf(ip, sizeof(ip), "[<%p>]",
 518                                 (void *)class->contention_point[i]);
 519                 seq_printf(m, "%40s %14lu %29s %pS\n",
 520                            name, stats->contention_point[i],
 521                            ip, (void *)class->contention_point[i]);
 522         }
 523         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 524                 char ip[32];
 525
 526                 if (class->contending_point[i] == 0)
 527                         break;
 528
 529                 if (!i)
 530                         seq_line(m, '-', 40-namelen, namelen);
 531
 532                 snprintf(ip, sizeof(ip), "[<%p>]",
 533                                 (void *)class->contending_point[i]);
 534                 seq_printf(m, "%40s %14lu %29s %pS\n",
 535                            name, stats->contending_point[i],
 536                            ip, (void *)class->contending_point[i]);
 537         }
 538         if (i) {
 539                 seq_puts(m, "\n");
 540                 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
 541                 seq_puts(m, "\n");
 542         }
 543 }
 544
 545 static void seq_header(struct seq_file *m)
 546 {
 547         seq_puts(m, "lock_stat version 0.4\n");
 548
 549         if (unlikely(!debug_locks))
 550                 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
 551
 552         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 553         seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
 554                         "%14s %14s\n",
 555                         "class name",
 556                         "con-bounces",
 557                         "contentions",
 558                         "waittime-min",
 559                         "waittime-max",
 560                         "waittime-total",
 561                         "waittime-avg",
 562                         "acq-bounces",
 563                         "acquisitions",
 564                         "holdtime-min",
 565                         "holdtime-max",
 566                         "holdtime-total",
 567                         "holdtime-avg");
 568         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 569         seq_printf(m, "\n");
 570 }
 571
 572 static void *ls_start(struct seq_file *m, loff_t *pos)
 573 {
 574         struct lock_stat_seq *data = m->private;
 575         struct lock_stat_data *iter;
 576
 577         if (*pos == 0)
 578                 return SEQ_START_TOKEN;
 579
 580         iter = data->stats + (*pos - 1);
 581         if (iter >= data->iter_end)
 582                 iter = NULL;
 583
 584         return iter;
 585 }
 586
 587 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
 588 {
 589         (*pos)++;
 590         return ls_start(m, pos);
 591 }
 592
 593 static void ls_stop(struct seq_file *m, void *v)
 594 {
 595 }
 596
 597 static int ls_show(struct seq_file *m, void *v)
 598 {
 599         if (v == SEQ_START_TOKEN)
 600                 seq_header(m);
 601         else
 602                 seq_stats(m, v);
 603
 604         return 0;
 605 }
 606
 607 static const struct seq_operations lockstat_ops = {
 608         .start  = ls_start,
 609         .next   = ls_next,
 610         .stop   = ls_stop,
 611         .show   = ls_show,
 612 };
 613
 614 static int lock_stat_open(struct inode *inode, struct file *file)
 615 {
 616         int res;
 617         struct lock_class *class;
 618         struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
 619
 620         if (!data)
 621                 return -ENOMEM;
 622
 623         res = seq_open(file, &lockstat_ops);
 624         if (!res) {
 625                 struct lock_stat_data *iter = data->stats;
 626                 struct seq_file *m = file->private_data;
 627
 628                 list_for_each_entry(class, &all_lock_classes, lock_entry) {
 629                         iter->class = class;
 630                         iter->stats = lock_stats(class);
 631                         iter++;
 632                 }
 633                 data->iter_end = iter;
 634
 635                 sort(data->stats, data->iter_end - data->stats,
 636                                 sizeof(struct lock_stat_data),
 637                                 lock_stat_cmp, NULL);
 638
 639                 m->private = data;
 640         } else
 641                 vfree(data);
 642
 643         return res;
 644 }
 645
 646 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
 647                                size_t count, loff_t *ppos)
 648 {
 649         struct lock_class *class;
 650         char c;
 651
 652         if (count) {
 653                 if (get_user(c, buf))
 654                         return -EFAULT;
 655
 656                 if (c != '0')
 657                         return count;
 658
 659                 list_for_each_entry(class, &all_lock_classes, lock_entry)
 660                         clear_lock_stats(class);
 661         }
 662         return count;
 663 }
 664
 665 static int lock_stat_release(struct inode *inode, struct file *file)
 666 {
 667         struct seq_file *seq = file->private_data;
 668
 669         vfree(seq->private);
 670         return seq_release(inode, file);
 671 }
 672
 673 static const struct file_operations proc_lock_stat_operations = {
 674         .open           = lock_stat_open,
 675         .write          = lock_stat_write,
 676         .read           = seq_read,
 677         .llseek         = seq_lseek,
 678         .release        = lock_stat_release,
 679 };
 680 #endif /* CONFIG_LOCK_STAT */
 681
 682 static int __init lockdep_proc_init(void)
 683 {
 684         proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
 685 #ifdef CONFIG_PROVE_LOCKING
 686         proc_create("lockdep_chains", S_IRUSR, NULL,
 687                     &proc_lockdep_chains_operations);
 688 #endif
 689         proc_create("lockdep_stats", S_IRUSR, NULL,
 690                     &proc_lockdep_stats_operations);
 691
 692 #ifdef CONFIG_LOCK_STAT
 693         proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
 694                     &proc_lock_stat_operations);
 695 #endif
 696
 697         return 0;
 698 }
 699
 700 __initcall(lockdep_proc_init);
 701