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 /*
  28  * Since iteration of lock_classes is done without holding the lockdep lock,
  29  * it is not safe to iterate all_lock_classes list directly as the iteration
  30  * may branch off to free_lock_classes or the zapped list. Iteration is done
  31  * directly on the lock_classes array by checking the lock_classes_in_use
  32  * bitmap and max_lock_class_idx.
  33  */
  34 #define iterate_lock_classes(idx, class)                                \
  35         for (idx = 0, class = lock_classes; idx <= max_lock_class_idx;  \
  36              idx++, class++)
  37
  38 static void *l_next(struct seq_file *m, void *v, loff_t *pos)
  39 {
  40         struct lock_class *class = v;
  41
  42         ++class;
  43         *pos = class - lock_classes;
  44         return (*pos > max_lock_class_idx) ? NULL : class;
  45 }
  46
  47 static void *l_start(struct seq_file *m, loff_t *pos)
  48 {
  49         unsigned long idx = *pos;
  50
  51         if (idx > max_lock_class_idx)
  52                 return NULL;
  53         return lock_classes + idx;
  54 }
  55
  56 static void l_stop(struct seq_file *m, void *v)
  57 {
  58 }
  59
  60 static void print_name(struct seq_file *m, struct lock_class *class)
  61 {
  62         char str[KSYM_NAME_LEN];
  63         const char *name = class->name;
  64
  65         if (!name) {
  66                 name = __get_key_name(class->key, str);
  67                 seq_printf(m, "%s", name);
  68         } else{
  69                 seq_printf(m, "%s", name);
  70                 if (class->name_version > 1)
  71                         seq_printf(m, "#%d", class->name_version);
  72                 if (class->subclass)
  73                         seq_printf(m, "/%d", class->subclass);
  74         }
  75 }
  76
  77 static int l_show(struct seq_file *m, void *v)
  78 {
  79         struct lock_class *class = v;
  80         struct lock_list *entry;
  81         char usage[LOCK_USAGE_CHARS];
  82         int idx = class - lock_classes;
  83
  84         if (v == lock_classes)
  85                 seq_printf(m, "all lock classes:\n");
  86
  87         if (!test_bit(idx, lock_classes_in_use))
  88                 return 0;
  89
  90         seq_printf(m, "%p", class->key);
  91 #ifdef CONFIG_DEBUG_LOCKDEP
  92         seq_printf(m, " OPS:%8ld", debug_class_ops_read(class));
  93 #endif
  94         if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
  95                 seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class));
  96                 seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class));
  97
  98                 get_usage_chars(class, usage);
  99                 seq_printf(m, " %s", usage);
 100         }
 101
 102         seq_printf(m, ": ");
 103         print_name(m, class);
 104         seq_puts(m, "\n");
 105
 106         if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
 107                 list_for_each_entry(entry, &class->locks_after, entry) {
 108                         if (entry->distance == 1) {
 109                                 seq_printf(m, " -> [%p] ", entry->class->key);
 110                                 print_name(m, entry->class);
 111                                 seq_puts(m, "\n");
 112                         }
 113                 }
 114                 seq_puts(m, "\n");
 115         }
 116
 117         return 0;
 118 }
 119
 120 static const struct seq_operations lockdep_ops = {
 121         .start  = l_start,
 122         .next   = l_next,
 123         .stop   = l_stop,
 124         .show   = l_show,
 125 };
 126
 127 #ifdef CONFIG_PROVE_LOCKING
 128 static void *lc_start(struct seq_file *m, loff_t *pos)
 129 {
 130         if (*pos < 0)
 131                 return NULL;
 132
 133         if (*pos == 0)
 134                 return SEQ_START_TOKEN;
 135
 136         return lock_chains + (*pos - 1);
 137 }
 138
 139 static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
 140 {
 141         *pos = lockdep_next_lockchain(*pos - 1) + 1;
 142         return lc_start(m, pos);
 143 }
 144
 145 static void lc_stop(struct seq_file *m, void *v)
 146 {
 147 }
 148
 149 static int lc_show(struct seq_file *m, void *v)
 150 {
 151         struct lock_chain *chain = v;
 152         struct lock_class *class;
 153         int i;
 154         static const char * const irq_strs[] = {
 155                 [0]                          = "0",
 156                 [LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq",
 157                 [LOCK_CHAIN_SOFTIRQ_CONTEXT] = "softirq",
 158                 [LOCK_CHAIN_SOFTIRQ_CONTEXT|
 159                  LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq|softirq",
 160         };
 161
 162         if (v == SEQ_START_TOKEN) {
 163                 if (!nr_free_chain_hlocks)
 164                         seq_printf(m, "(buggered) ");
 165                 seq_printf(m, "all lock chains:\n");
 166                 return 0;
 167         }
 168
 169         seq_printf(m, "irq_context: %s\n", irq_strs[chain->irq_context]);
 170
 171         for (i = 0; i < chain->depth; i++) {
 172                 class = lock_chain_get_class(chain, i);
 173                 if (!class->key)
 174                         continue;
 175
 176                 seq_printf(m, "[%p] ", class->key);
 177                 print_name(m, class);
 178                 seq_puts(m, "\n");
 179         }
 180         seq_puts(m, "\n");
 181
 182         return 0;
 183 }
 184
 185 static const struct seq_operations lockdep_chains_ops = {
 186         .start  = lc_start,
 187         .next   = lc_next,
 188         .stop   = lc_stop,
 189         .show   = lc_show,
 190 };
 191 #endif /* CONFIG_PROVE_LOCKING */
 192
 193 static void lockdep_stats_debug_show(struct seq_file *m)
 194 {
 195 #ifdef CONFIG_DEBUG_LOCKDEP
 196         unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
 197                            hi2 = debug_atomic_read(hardirqs_off_events),
 198                            hr1 = debug_atomic_read(redundant_hardirqs_on),
 199                            hr2 = debug_atomic_read(redundant_hardirqs_off),
 200                            si1 = debug_atomic_read(softirqs_on_events),
 201                            si2 = debug_atomic_read(softirqs_off_events),
 202                            sr1 = debug_atomic_read(redundant_softirqs_on),
 203                            sr2 = debug_atomic_read(redundant_softirqs_off);
 204
 205         seq_printf(m, " chain lookup misses:           %11llu\n",
 206                 debug_atomic_read(chain_lookup_misses));
 207         seq_printf(m, " chain lookup hits:             %11llu\n",
 208                 debug_atomic_read(chain_lookup_hits));
 209         seq_printf(m, " cyclic checks:                 %11llu\n",
 210                 debug_atomic_read(nr_cyclic_checks));
 211         seq_printf(m, " redundant checks:              %11llu\n",
 212                 debug_atomic_read(nr_redundant_checks));
 213         seq_printf(m, " redundant links:               %11llu\n",
 214                 debug_atomic_read(nr_redundant));
 215         seq_printf(m, " find-mask forwards checks:     %11llu\n",
 216                 debug_atomic_read(nr_find_usage_forwards_checks));
 217         seq_printf(m, " find-mask backwards checks:    %11llu\n",
 218                 debug_atomic_read(nr_find_usage_backwards_checks));
 219
 220         seq_printf(m, " hardirq on events:             %11llu\n", hi1);
 221         seq_printf(m, " hardirq off events:            %11llu\n", hi2);
 222         seq_printf(m, " redundant hardirq ons:         %11llu\n", hr1);
 223         seq_printf(m, " redundant hardirq offs:        %11llu\n", hr2);
 224         seq_printf(m, " softirq on events:             %11llu\n", si1);
 225         seq_printf(m, " softirq off events:            %11llu\n", si2);
 226         seq_printf(m, " redundant softirq ons:         %11llu\n", sr1);
 227         seq_printf(m, " redundant softirq offs:        %11llu\n", sr2);
 228 #endif
 229 }
 230
 231 static int lockdep_stats_show(struct seq_file *m, void *v)
 232 {
 233         unsigned long nr_unused = 0, nr_uncategorized = 0,
 234                       nr_irq_safe = 0, nr_irq_unsafe = 0,
 235                       nr_softirq_safe = 0, nr_softirq_unsafe = 0,
 236                       nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
 237                       nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
 238                       nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
 239                       nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
 240                       sum_forward_deps = 0;
 241
 242 #ifdef CONFIG_PROVE_LOCKING
 243         struct lock_class *class;
 244         unsigned long idx;
 245
 246         iterate_lock_classes(idx, class) {
 247                 if (!test_bit(idx, lock_classes_in_use))
 248                         continue;
 249
 250                 if (class->usage_mask == 0)
 251                         nr_unused++;
 252                 if (class->usage_mask == LOCKF_USED)
 253                         nr_uncategorized++;
 254                 if (class->usage_mask & LOCKF_USED_IN_IRQ)
 255                         nr_irq_safe++;
 256                 if (class->usage_mask & LOCKF_ENABLED_IRQ)
 257                         nr_irq_unsafe++;
 258                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
 259                         nr_softirq_safe++;
 260                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
 261                         nr_softirq_unsafe++;
 262                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
 263                         nr_hardirq_safe++;
 264                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
 265                         nr_hardirq_unsafe++;
 266                 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
 267                         nr_irq_read_safe++;
 268                 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
 269                         nr_irq_read_unsafe++;
 270                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
 271                         nr_softirq_read_safe++;
 272                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
 273                         nr_softirq_read_unsafe++;
 274                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
 275                         nr_hardirq_read_safe++;
 276                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
 277                         nr_hardirq_read_unsafe++;
 278
 279                 sum_forward_deps += lockdep_count_forward_deps(class);
 280         }
 281
 282 #ifdef CONFIG_DEBUG_LOCKDEP
 283         DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
 284 #endif
 285
 286 #endif
 287         seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
 288                         nr_lock_classes, MAX_LOCKDEP_KEYS);
 289         seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
 290                         nr_list_entries, MAX_LOCKDEP_ENTRIES);
 291         seq_printf(m, " indirect dependencies:         %11lu\n",
 292                         sum_forward_deps);
 293
 294         /*
 295          * Total number of dependencies:
 296          *
 297          * All irq-safe locks may nest inside irq-unsafe locks,
 298          * plus all the other known dependencies:
 299          */
 300         seq_printf(m, " all direct dependencies:       %11lu\n",
 301                         nr_irq_unsafe * nr_irq_safe +
 302                         nr_hardirq_unsafe * nr_hardirq_safe +
 303                         nr_list_entries);
 304
 305 #ifdef CONFIG_PROVE_LOCKING
 306         seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
 307                         lock_chain_count(), MAX_LOCKDEP_CHAINS);
 308         seq_printf(m, " dependency chain hlocks used:  %11lu [max: %lu]\n",
 309                         MAX_LOCKDEP_CHAIN_HLOCKS -
 310                         (nr_free_chain_hlocks + nr_lost_chain_hlocks),
 311                         MAX_LOCKDEP_CHAIN_HLOCKS);
 312         seq_printf(m, " dependency chain hlocks lost:  %11u\n",
 313                         nr_lost_chain_hlocks);
 314 #endif
 315
 316 #ifdef CONFIG_TRACE_IRQFLAGS
 317         seq_printf(m, " in-hardirq chains:             %11u\n",
 318                         nr_hardirq_chains);
 319         seq_printf(m, " in-softirq chains:             %11u\n",
 320                         nr_softirq_chains);
 321 #endif
 322         seq_printf(m, " in-process chains:             %11u\n",
 323                         nr_process_chains);
 324         seq_printf(m, " stack-trace entries:           %11lu [max: %lu]\n",
 325                         nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
 326 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
 327         seq_printf(m, " number of stack traces:        %11llu\n",
 328                    lockdep_stack_trace_count());
 329         seq_printf(m, " number of stack hash chains:   %11llu\n",
 330                    lockdep_stack_hash_count());
 331 #endif
 332         seq_printf(m, " combined max dependencies:     %11u\n",
 333                         (nr_hardirq_chains + 1) *
 334                         (nr_softirq_chains + 1) *
 335                         (nr_process_chains + 1)
 336         );
 337         seq_printf(m, " hardirq-safe locks:            %11lu\n",
 338                         nr_hardirq_safe);
 339         seq_printf(m, " hardirq-unsafe locks:          %11lu\n",
 340                         nr_hardirq_unsafe);
 341         seq_printf(m, " softirq-safe locks:            %11lu\n",
 342                         nr_softirq_safe);
 343         seq_printf(m, " softirq-unsafe locks:          %11lu\n",
 344                         nr_softirq_unsafe);
 345         seq_printf(m, " irq-safe locks:                %11lu\n",
 346                         nr_irq_safe);
 347         seq_printf(m, " irq-unsafe locks:              %11lu\n",
 348                         nr_irq_unsafe);
 349
 350         seq_printf(m, " hardirq-read-safe locks:       %11lu\n",
 351                         nr_hardirq_read_safe);
 352         seq_printf(m, " hardirq-read-unsafe locks:     %11lu\n",
 353                         nr_hardirq_read_unsafe);
 354         seq_printf(m, " softirq-read-safe locks:       %11lu\n",
 355                         nr_softirq_read_safe);
 356         seq_printf(m, " softirq-read-unsafe locks:     %11lu\n",
 357                         nr_softirq_read_unsafe);
 358         seq_printf(m, " irq-read-safe locks:           %11lu\n",
 359                         nr_irq_read_safe);
 360         seq_printf(m, " irq-read-unsafe locks:         %11lu\n",
 361                         nr_irq_read_unsafe);
 362
 363         seq_printf(m, " uncategorized locks:           %11lu\n",
 364                         nr_uncategorized);
 365         seq_printf(m, " unused locks:                  %11lu\n",
 366                         nr_unused);
 367         seq_printf(m, " max locking depth:             %11u\n",
 368                         max_lockdep_depth);
 369 #ifdef CONFIG_PROVE_LOCKING
 370         seq_printf(m, " max bfs queue depth:           %11u\n",
 371                         max_bfs_queue_depth);
 372 #endif
 373         seq_printf(m, " max lock class index:          %11lu\n",
 374                         max_lock_class_idx);
 375         lockdep_stats_debug_show(m);
 376         seq_printf(m, " debug_locks:                   %11u\n",
 377                         debug_locks);
 378
 379         /*
 380          * Zapped classes and lockdep data buffers reuse statistics.
 381          */
 382         seq_puts(m, "\n");
 383         seq_printf(m, " zapped classes:                %11lu\n",
 384                         nr_zapped_classes);
 385 #ifdef CONFIG_PROVE_LOCKING
 386         seq_printf(m, " zapped lock chains:            %11lu\n",
 387                         nr_zapped_lock_chains);
 388         seq_printf(m, " large chain blocks:            %11u\n",
 389                         nr_large_chain_blocks);
 390 #endif
 391         return 0;
 392 }
 393
 394 #ifdef CONFIG_LOCK_STAT
 395
 396 struct lock_stat_data {
 397         struct lock_class *class;
 398         struct lock_class_stats stats;
 399 };
 400
 401 struct lock_stat_seq {
 402         struct lock_stat_data *iter_end;
 403         struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
 404 };
 405
 406 /*
 407  * sort on absolute number of contentions
 408  */
 409 static int lock_stat_cmp(const void *l, const void *r)
 410 {
 411         const struct lock_stat_data *dl = l, *dr = r;
 412         unsigned long nl, nr;
 413
 414         nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
 415         nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
 416
 417         return nr - nl;
 418 }
 419
 420 static void seq_line(struct seq_file *m, char c, int offset, int length)
 421 {
 422         int i;
 423
 424         for (i = 0; i < offset; i++)
 425                 seq_puts(m, " ");
 426         for (i = 0; i < length; i++)
 427                 seq_printf(m, "%c", c);
 428         seq_puts(m, "\n");
 429 }
 430
 431 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
 432 {
 433         s64 div;
 434         s32 rem;
 435
 436         nr += 5; /* for display rounding */
 437         div = div_s64_rem(nr, 1000, &rem);
 438         snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
 439 }
 440
 441 static void seq_time(struct seq_file *m, s64 time)
 442 {
 443         char num[22];
 444
 445         snprint_time(num, sizeof(num), time);
 446         seq_printf(m, " %14s", num);
 447 }
 448
 449 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
 450 {
 451         seq_printf(m, "%14lu", lt->nr);
 452         seq_time(m, lt->min);
 453         seq_time(m, lt->max);
 454         seq_time(m, lt->total);
 455         seq_time(m, lt->nr ? div64_u64(lt->total, lt->nr) : 0);
 456 }
 457
 458 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 459 {
 460         const struct lockdep_subclass_key *ckey;
 461         struct lock_class_stats *stats;
 462         struct lock_class *class;
 463         const char *cname;
 464         int i, namelen;
 465         char name[39];
 466
 467         class = data->class;
 468         stats = &data->stats;
 469
 470         namelen = 38;
 471         if (class->name_version > 1)
 472                 namelen -= 2; /* XXX truncates versions > 9 */
 473         if (class->subclass)
 474                 namelen -= 2;
 475
 476         rcu_read_lock_sched();
 477         cname = rcu_dereference_sched(class->name);
 478         ckey  = rcu_dereference_sched(class->key);
 479
 480         if (!cname && !ckey) {
 481                 rcu_read_unlock_sched();
 482                 return;
 483
 484         } else if (!cname) {
 485                 char str[KSYM_NAME_LEN];
 486                 const char *key_name;
 487
 488                 key_name = __get_key_name(ckey, str);
 489                 snprintf(name, namelen, "%s", key_name);
 490         } else {
 491                 snprintf(name, namelen, "%s", cname);
 492         }
 493         rcu_read_unlock_sched();
 494
 495         namelen = strlen(name);
 496         if (class->name_version > 1) {
 497                 snprintf(name+namelen, 3, "#%d", class->name_version);
 498                 namelen += 2;
 499         }
 500         if (class->subclass) {
 501                 snprintf(name+namelen, 3, "/%d", class->subclass);
 502                 namelen += 2;
 503         }
 504
 505         if (stats->write_holdtime.nr) {
 506                 if (stats->read_holdtime.nr)
 507                         seq_printf(m, "%38s-W:", name);
 508                 else
 509                         seq_printf(m, "%40s:", name);
 510
 511                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
 512                 seq_lock_time(m, &stats->write_waittime);
 513                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
 514                 seq_lock_time(m, &stats->write_holdtime);
 515                 seq_puts(m, "\n");
 516         }
 517
 518         if (stats->read_holdtime.nr) {
 519                 seq_printf(m, "%38s-R:", name);
 520                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
 521                 seq_lock_time(m, &stats->read_waittime);
 522                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
 523                 seq_lock_time(m, &stats->read_holdtime);
 524                 seq_puts(m, "\n");
 525         }
 526
 527         if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
 528                 return;
 529
 530         if (stats->read_holdtime.nr)
 531                 namelen += 2;
 532
 533         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 534                 char ip[32];
 535
 536                 if (class->contention_point[i] == 0)
 537                         break;
 538
 539                 if (!i)
 540                         seq_line(m, '-', 40-namelen, namelen);
 541
 542                 snprintf(ip, sizeof(ip), "[<%p>]",
 543                                 (void *)class->contention_point[i]);
 544                 seq_printf(m, "%40s %14lu %29s %pS\n",
 545                            name, stats->contention_point[i],
 546                            ip, (void *)class->contention_point[i]);
 547         }
 548         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 549                 char ip[32];
 550
 551                 if (class->contending_point[i] == 0)
 552                         break;
 553
 554                 if (!i)
 555                         seq_line(m, '-', 40-namelen, namelen);
 556
 557                 snprintf(ip, sizeof(ip), "[<%p>]",
 558                                 (void *)class->contending_point[i]);
 559                 seq_printf(m, "%40s %14lu %29s %pS\n",
 560                            name, stats->contending_point[i],
 561                            ip, (void *)class->contending_point[i]);
 562         }
 563         if (i) {
 564                 seq_puts(m, "\n");
 565                 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
 566                 seq_puts(m, "\n");
 567         }
 568 }
 569
 570 static void seq_header(struct seq_file *m)
 571 {
 572         seq_puts(m, "lock_stat version 0.4\n");
 573
 574         if (unlikely(!debug_locks))
 575                 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
 576
 577         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 578         seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
 579                         "%14s %14s\n",
 580                         "class name",
 581                         "con-bounces",
 582                         "contentions",
 583                         "waittime-min",
 584                         "waittime-max",
 585                         "waittime-total",
 586                         "waittime-avg",
 587                         "acq-bounces",
 588                         "acquisitions",
 589                         "holdtime-min",
 590                         "holdtime-max",
 591                         "holdtime-total",
 592                         "holdtime-avg");
 593         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 594         seq_printf(m, "\n");
 595 }
 596
 597 static void *ls_start(struct seq_file *m, loff_t *pos)
 598 {
 599         struct lock_stat_seq *data = m->private;
 600         struct lock_stat_data *iter;
 601
 602         if (*pos == 0)
 603                 return SEQ_START_TOKEN;
 604
 605         iter = data->stats + (*pos - 1);
 606         if (iter >= data->iter_end)
 607                 iter = NULL;
 608
 609         return iter;
 610 }
 611
 612 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
 613 {
 614         (*pos)++;
 615         return ls_start(m, pos);
 616 }
 617
 618 static void ls_stop(struct seq_file *m, void *v)
 619 {
 620 }
 621
 622 static int ls_show(struct seq_file *m, void *v)
 623 {
 624         if (v == SEQ_START_TOKEN)
 625                 seq_header(m);
 626         else
 627                 seq_stats(m, v);
 628
 629         return 0;
 630 }
 631
 632 static const struct seq_operations lockstat_ops = {
 633         .start  = ls_start,
 634         .next   = ls_next,
 635         .stop   = ls_stop,
 636         .show   = ls_show,
 637 };
 638
 639 static int lock_stat_open(struct inode *inode, struct file *file)
 640 {
 641         int res;
 642         struct lock_class *class;
 643         struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
 644
 645         if (!data)
 646                 return -ENOMEM;
 647
 648         res = seq_open(file, &lockstat_ops);
 649         if (!res) {
 650                 struct lock_stat_data *iter = data->stats;
 651                 struct seq_file *m = file->private_data;
 652                 unsigned long idx;
 653
 654                 iterate_lock_classes(idx, class) {
 655                         if (!test_bit(idx, lock_classes_in_use))
 656                                 continue;
 657                         iter->class = class;
 658                         iter->stats = lock_stats(class);
 659                         iter++;
 660                 }
 661
 662                 data->iter_end = iter;
 663
 664                 sort(data->stats, data->iter_end - data->stats,
 665                                 sizeof(struct lock_stat_data),
 666                                 lock_stat_cmp, NULL);
 667
 668                 m->private = data;
 669         } else
 670                 vfree(data);
 671
 672         return res;
 673 }
 674
 675 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
 676                                size_t count, loff_t *ppos)
 677 {
 678         struct lock_class *class;
 679         unsigned long idx;
 680         char c;
 681
 682         if (count) {
 683                 if (get_user(c, buf))
 684                         return -EFAULT;
 685
 686                 if (c != '0')
 687                         return count;
 688
 689                 iterate_lock_classes(idx, class) {
 690                         if (!test_bit(idx, lock_classes_in_use))
 691                                 continue;
 692                         clear_lock_stats(class);
 693                 }
 694         }
 695         return count;
 696 }
 697
 698 static int lock_stat_release(struct inode *inode, struct file *file)
 699 {
 700         struct seq_file *seq = file->private_data;
 701
 702         vfree(seq->private);
 703         return seq_release(inode, file);
 704 }
 705
 706 static const struct proc_ops lock_stat_proc_ops = {
 707         .proc_open      = lock_stat_open,
 708         .proc_write     = lock_stat_write,
 709         .proc_read      = seq_read,
 710         .proc_lseek     = seq_lseek,
 711         .proc_release   = lock_stat_release,
 712 };
 713 #endif /* CONFIG_LOCK_STAT */
 714
 715 static int __init lockdep_proc_init(void)
 716 {
 717         proc_create_seq("lockdep", S_IRUSR, NULL, &lockdep_ops);
 718 #ifdef CONFIG_PROVE_LOCKING
 719         proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops);
 720 #endif
 721         proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show);
 722 #ifdef CONFIG_LOCK_STAT
 723         proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL, &lock_stat_proc_ops);
 724 #endif
 725
 726         return 0;
 727 }
 728
 729 __initcall(lockdep_proc_init);
 730