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 <[email protected]>
  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", class->ops);
  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 static int lockdep_open(struct inode *inode, struct file *file)
 105 {
 106         return seq_open(file, &lockdep_ops);
 107 }
 108
 109 static const struct file_operations proc_lockdep_operations = {
 110         .open           = lockdep_open,
 111         .read           = seq_read,
 112         .llseek         = seq_lseek,
 113         .release        = seq_release,
 114 };
 115
 116 #ifdef CONFIG_PROVE_LOCKING
 117 static void *lc_start(struct seq_file *m, loff_t *pos)
 118 {
 119         if (*pos == 0)
 120                 return SEQ_START_TOKEN;
 121
 122         if (*pos - 1 < nr_lock_chains)
 123                 return lock_chains + (*pos - 1);
 124
 125         return NULL;
 126 }
 127
 128 static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
 129 {
 130         (*pos)++;
 131         return lc_start(m, pos);
 132 }
 133
 134 static void lc_stop(struct seq_file *m, void *v)
 135 {
 136 }
 137
 138 static int lc_show(struct seq_file *m, void *v)
 139 {
 140         struct lock_chain *chain = v;
 141         struct lock_class *class;
 142         int i;
 143
 144         if (v == SEQ_START_TOKEN) {
 145                 if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)
 146                         seq_printf(m, "(buggered) ");
 147                 seq_printf(m, "all lock chains:\n");
 148                 return 0;
 149         }
 150
 151         seq_printf(m, "irq_context: %d\n", chain->irq_context);
 152
 153         for (i = 0; i < chain->depth; i++) {
 154                 class = lock_chain_get_class(chain, i);
 155                 if (!class->key)
 156                         continue;
 157
 158                 seq_printf(m, "[%p] ", class->key);
 159                 print_name(m, class);
 160                 seq_puts(m, "\n");
 161         }
 162         seq_puts(m, "\n");
 163
 164         return 0;
 165 }
 166
 167 static const struct seq_operations lockdep_chains_ops = {
 168         .start  = lc_start,
 169         .next   = lc_next,
 170         .stop   = lc_stop,
 171         .show   = lc_show,
 172 };
 173
 174 static int lockdep_chains_open(struct inode *inode, struct file *file)
 175 {
 176         return seq_open(file, &lockdep_chains_ops);
 177 }
 178
 179 static const struct file_operations proc_lockdep_chains_operations = {
 180         .open           = lockdep_chains_open,
 181         .read           = seq_read,
 182         .llseek         = seq_lseek,
 183         .release        = seq_release,
 184 };
 185 #endif /* CONFIG_PROVE_LOCKING */
 186
 187 static void lockdep_stats_debug_show(struct seq_file *m)
 188 {
 189 #ifdef CONFIG_DEBUG_LOCKDEP
 190         unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
 191                            hi2 = debug_atomic_read(hardirqs_off_events),
 192                            hr1 = debug_atomic_read(redundant_hardirqs_on),
 193                            hr2 = debug_atomic_read(redundant_hardirqs_off),
 194                            si1 = debug_atomic_read(softirqs_on_events),
 195                            si2 = debug_atomic_read(softirqs_off_events),
 196                            sr1 = debug_atomic_read(redundant_softirqs_on),
 197                            sr2 = debug_atomic_read(redundant_softirqs_off);
 198
 199         seq_printf(m, " chain lookup misses:           %11llu\n",
 200                 debug_atomic_read(chain_lookup_misses));
 201         seq_printf(m, " chain lookup hits:             %11llu\n",
 202                 debug_atomic_read(chain_lookup_hits));
 203         seq_printf(m, " cyclic checks:                 %11llu\n",
 204                 debug_atomic_read(nr_cyclic_checks));
 205         seq_printf(m, " redundant checks:              %11llu\n",
 206                 debug_atomic_read(nr_redundant_checks));
 207         seq_printf(m, " redundant links:               %11llu\n",
 208                 debug_atomic_read(nr_redundant));
 209         seq_printf(m, " find-mask forwards checks:     %11llu\n",
 210                 debug_atomic_read(nr_find_usage_forwards_checks));
 211         seq_printf(m, " find-mask backwards checks:    %11llu\n",
 212                 debug_atomic_read(nr_find_usage_backwards_checks));
 213
 214         seq_printf(m, " hardirq on events:             %11llu\n", hi1);
 215         seq_printf(m, " hardirq off events:            %11llu\n", hi2);
 216         seq_printf(m, " redundant hardirq ons:         %11llu\n", hr1);
 217         seq_printf(m, " redundant hardirq offs:        %11llu\n", hr2);
 218         seq_printf(m, " softirq on events:             %11llu\n", si1);
 219         seq_printf(m, " softirq off events:            %11llu\n", si2);
 220         seq_printf(m, " redundant softirq ons:         %11llu\n", sr1);
 221         seq_printf(m, " redundant softirq offs:        %11llu\n", sr2);
 222 #endif
 223 }
 224
 225 static int lockdep_stats_show(struct seq_file *m, void *v)
 226 {
 227         struct lock_class *class;
 228         unsigned long nr_unused = 0, nr_uncategorized = 0,
 229                       nr_irq_safe = 0, nr_irq_unsafe = 0,
 230                       nr_softirq_safe = 0, nr_softirq_unsafe = 0,
 231                       nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
 232                       nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
 233                       nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
 234                       nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
 235                       sum_forward_deps = 0;
 236
 237         list_for_each_entry(class, &all_lock_classes, lock_entry) {
 238
 239                 if (class->usage_mask == 0)
 240                         nr_unused++;
 241                 if (class->usage_mask == LOCKF_USED)
 242                         nr_uncategorized++;
 243                 if (class->usage_mask & LOCKF_USED_IN_IRQ)
 244                         nr_irq_safe++;
 245                 if (class->usage_mask & LOCKF_ENABLED_IRQ)
 246                         nr_irq_unsafe++;
 247                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
 248                         nr_softirq_safe++;
 249                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
 250                         nr_softirq_unsafe++;
 251                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
 252                         nr_hardirq_safe++;
 253                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
 254                         nr_hardirq_unsafe++;
 255                 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
 256                         nr_irq_read_safe++;
 257                 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
 258                         nr_irq_read_unsafe++;
 259                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
 260                         nr_softirq_read_safe++;
 261                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
 262                         nr_softirq_read_unsafe++;
 263                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
 264                         nr_hardirq_read_safe++;
 265                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
 266                         nr_hardirq_read_unsafe++;
 267
 268 #ifdef CONFIG_PROVE_LOCKING
 269                 sum_forward_deps += lockdep_count_forward_deps(class);
 270 #endif
 271         }
 272 #ifdef CONFIG_DEBUG_LOCKDEP
 273         DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
 274 #endif
 275         seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
 276                         nr_lock_classes, MAX_LOCKDEP_KEYS);
 277         seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
 278                         nr_list_entries, MAX_LOCKDEP_ENTRIES);
 279         seq_printf(m, " indirect dependencies:         %11lu\n",
 280                         sum_forward_deps);
 281
 282         /*
 283          * Total number of dependencies:
 284          *
 285          * All irq-safe locks may nest inside irq-unsafe locks,
 286          * plus all the other known dependencies:
 287          */
 288         seq_printf(m, " all direct dependencies:       %11lu\n",
 289                         nr_irq_unsafe * nr_irq_safe +
 290                         nr_hardirq_unsafe * nr_hardirq_safe +
 291                         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         seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0);
 432 }
 433
 434 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 435 {
 436         struct lockdep_subclass_key *ckey;
 437         struct lock_class_stats *stats;
 438         struct lock_class *class;
 439         const char *cname;
 440         int i, namelen;
 441         char name[39];
 442
 443         class = data->class;
 444         stats = &data->stats;
 445
 446         namelen = 38;
 447         if (class->name_version > 1)
 448                 namelen -= 2; /* XXX truncates versions > 9 */
 449         if (class->subclass)
 450                 namelen -= 2;
 451
 452         rcu_read_lock_sched();
 453         cname = rcu_dereference_sched(class->name);
 454         ckey  = rcu_dereference_sched(class->key);
 455
 456         if (!cname && !ckey) {
 457                 rcu_read_unlock_sched();
 458                 return;
 459
 460         } else if (!cname) {
 461                 char str[KSYM_NAME_LEN];
 462                 const char *key_name;
 463
 464                 key_name = __get_key_name(ckey, str);
 465                 snprintf(name, namelen, "%s", key_name);
 466         } else {
 467                 snprintf(name, namelen, "%s", cname);
 468         }
 469         rcu_read_unlock_sched();
 470
 471         namelen = strlen(name);
 472         if (class->name_version > 1) {
 473                 snprintf(name+namelen, 3, "#%d", class->name_version);
 474                 namelen += 2;
 475         }
 476         if (class->subclass) {
 477                 snprintf(name+namelen, 3, "/%d", class->subclass);
 478                 namelen += 2;
 479         }
 480
 481         if (stats->write_holdtime.nr) {
 482                 if (stats->read_holdtime.nr)
 483                         seq_printf(m, "%38s-W:", name);
 484                 else
 485                         seq_printf(m, "%40s:", name);
 486
 487                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
 488                 seq_lock_time(m, &stats->write_waittime);
 489                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
 490                 seq_lock_time(m, &stats->write_holdtime);
 491                 seq_puts(m, "\n");
 492         }
 493
 494         if (stats->read_holdtime.nr) {
 495                 seq_printf(m, "%38s-R:", name);
 496                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
 497                 seq_lock_time(m, &stats->read_waittime);
 498                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
 499                 seq_lock_time(m, &stats->read_holdtime);
 500                 seq_puts(m, "\n");
 501         }
 502
 503         if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
 504                 return;
 505
 506         if (stats->read_holdtime.nr)
 507                 namelen += 2;
 508
 509         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 510                 char ip[32];
 511
 512                 if (class->contention_point[i] == 0)
 513                         break;
 514
 515                 if (!i)
 516                         seq_line(m, '-', 40-namelen, namelen);
 517
 518                 snprintf(ip, sizeof(ip), "[<%p>]",
 519                                 (void *)class->contention_point[i]);
 520                 seq_printf(m, "%40s %14lu %29s %pS\n",
 521                            name, stats->contention_point[i],
 522                            ip, (void *)class->contention_point[i]);
 523         }
 524         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 525                 char ip[32];
 526
 527                 if (class->contending_point[i] == 0)
 528                         break;
 529
 530                 if (!i)
 531                         seq_line(m, '-', 40-namelen, namelen);
 532
 533                 snprintf(ip, sizeof(ip), "[<%p>]",
 534                                 (void *)class->contending_point[i]);
 535                 seq_printf(m, "%40s %14lu %29s %pS\n",
 536                            name, stats->contending_point[i],
 537                            ip, (void *)class->contending_point[i]);
 538         }
 539         if (i) {
 540                 seq_puts(m, "\n");
 541                 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
 542                 seq_puts(m, "\n");
 543         }
 544 }
 545
 546 static void seq_header(struct seq_file *m)
 547 {
 548         seq_puts(m, "lock_stat version 0.4\n");
 549
 550         if (unlikely(!debug_locks))
 551                 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
 552
 553         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 554         seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
 555                         "%14s %14s\n",
 556                         "class name",
 557                         "con-bounces",
 558                         "contentions",
 559                         "waittime-min",
 560                         "waittime-max",
 561                         "waittime-total",
 562                         "waittime-avg",
 563                         "acq-bounces",
 564                         "acquisitions",
 565                         "holdtime-min",
 566                         "holdtime-max",
 567                         "holdtime-total",
 568                         "holdtime-avg");
 569         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 570         seq_printf(m, "\n");
 571 }
 572
 573 static void *ls_start(struct seq_file *m, loff_t *pos)
 574 {
 575         struct lock_stat_seq *data = m->private;
 576         struct lock_stat_data *iter;
 577
 578         if (*pos == 0)
 579                 return SEQ_START_TOKEN;
 580
 581         iter = data->stats + (*pos - 1);
 582         if (iter >= data->iter_end)
 583                 iter = NULL;
 584
 585         return iter;
 586 }
 587
 588 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
 589 {
 590         (*pos)++;
 591         return ls_start(m, pos);
 592 }
 593
 594 static void ls_stop(struct seq_file *m, void *v)
 595 {
 596 }
 597
 598 static int ls_show(struct seq_file *m, void *v)
 599 {
 600         if (v == SEQ_START_TOKEN)
 601                 seq_header(m);
 602         else
 603                 seq_stats(m, v);
 604
 605         return 0;
 606 }
 607
 608 static const struct seq_operations lockstat_ops = {
 609         .start  = ls_start,
 610         .next   = ls_next,
 611         .stop   = ls_stop,
 612         .show   = ls_show,
 613 };
 614
 615 static int lock_stat_open(struct inode *inode, struct file *file)
 616 {
 617         int res;
 618         struct lock_class *class;
 619         struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
 620
 621         if (!data)
 622                 return -ENOMEM;
 623
 624         res = seq_open(file, &lockstat_ops);
 625         if (!res) {
 626                 struct lock_stat_data *iter = data->stats;
 627                 struct seq_file *m = file->private_data;
 628
 629                 list_for_each_entry(class, &all_lock_classes, lock_entry) {
 630                         iter->class = class;
 631                         iter->stats = lock_stats(class);
 632                         iter++;
 633                 }
 634                 data->iter_end = iter;
 635
 636                 sort(data->stats, data->iter_end - data->stats,
 637                                 sizeof(struct lock_stat_data),
 638                                 lock_stat_cmp, NULL);
 639
 640                 m->private = data;
 641         } else
 642                 vfree(data);
 643
 644         return res;
 645 }
 646
 647 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
 648                                size_t count, loff_t *ppos)
 649 {
 650         struct lock_class *class;
 651         char c;
 652
 653         if (count) {
 654                 if (get_user(c, buf))
 655                         return -EFAULT;
 656
 657                 if (c != '0')
 658                         return count;
 659
 660                 list_for_each_entry(class, &all_lock_classes, lock_entry)
 661                         clear_lock_stats(class);
 662         }
 663         return count;
 664 }
 665
 666 static int lock_stat_release(struct inode *inode, struct file *file)
 667 {
 668         struct seq_file *seq = file->private_data;
 669
 670         vfree(seq->private);
 671         return seq_release(inode, file);
 672 }
 673
 674 static const struct file_operations proc_lock_stat_operations = {
 675         .open           = lock_stat_open,
 676         .write          = lock_stat_write,
 677         .read           = seq_read,
 678         .llseek         = seq_lseek,
 679         .release        = lock_stat_release,
 680 };
 681 #endif /* CONFIG_LOCK_STAT */
 682
 683 static int __init lockdep_proc_init(void)
 684 {
 685         proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
 686 #ifdef CONFIG_PROVE_LOCKING
 687         proc_create("lockdep_chains", S_IRUSR, NULL,
 688                     &proc_lockdep_chains_operations);
 689 #endif
 690         proc_create("lockdep_stats", S_IRUSR, NULL,
 691                     &proc_lockdep_stats_operations);
 692
 693 #ifdef CONFIG_LOCK_STAT
 694         proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
 695                     &proc_lock_stat_operations);
 696 #endif
 697
 698         return 0;
 699 }
 700
 701 __initcall(lockdep_proc_init);
 702