kernel/lockdep_proc.c

   1 /*
   2  * kernel/lockdep_proc.c
   3  *
   4  * Runtime locking correctness validator
   5  *
   6  * Started by Ingo Molnar:
   7  *
   8  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
  10  *
  11  * Code for /proc/lockdep and /proc/lockdep_stats:
  12  *
  13  */
  14 #include <linux/module.h>
  15 #include <linux/proc_fs.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/kallsyms.h>
  18 #include <linux/debug_locks.h>
  19 #include <linux/vmalloc.h>
  20 #include <linux/sort.h>
  21 #include <asm/uaccess.h>
  22 #include <asm/div64.h>
  23
  24 #include "lockdep_internals.h"
  25
  26 static void *l_next(struct seq_file *m, void *v, loff_t *pos)
  27 {
  28         struct lock_class *class;
  29
  30         (*pos)++;
  31
  32         if (v == SEQ_START_TOKEN)
  33                 class = m->private;
  34         else {
  35                 class = v;
  36
  37                 if (class->lock_entry.next != &all_lock_classes)
  38                         class = list_entry(class->lock_entry.next,
  39                                            struct lock_class, lock_entry);
  40                 else
  41                         class = NULL;
  42         }
  43
  44         return class;
  45 }
  46
  47 static void *l_start(struct seq_file *m, loff_t *pos)
  48 {
  49         struct lock_class *class;
  50         loff_t i = 0;
  51
  52         if (*pos == 0)
  53                 return SEQ_START_TOKEN;
  54
  55         list_for_each_entry(class, &all_lock_classes, lock_entry) {
  56                 if (++i == *pos)
  57                 return class;
  58         }
  59         return NULL;
  60 }
  61
  62 static void l_stop(struct seq_file *m, void *v)
  63 {
  64 }
  65
  66 static void print_name(struct seq_file *m, struct lock_class *class)
  67 {
  68         char str[128];
  69         const char *name = class->name;
  70
  71         if (!name) {
  72                 name = __get_key_name(class->key, str);
  73                 seq_printf(m, "%s", name);
  74         } else{
  75                 seq_printf(m, "%s", name);
  76                 if (class->name_version > 1)
  77                         seq_printf(m, "#%d", class->name_version);
  78                 if (class->subclass)
  79                         seq_printf(m, "/%d", class->subclass);
  80         }
  81 }
  82
  83 static int l_show(struct seq_file *m, void *v)
  84 {
  85         struct lock_class *class = v;
  86         struct lock_list *entry;
  87         char usage[LOCK_USAGE_CHARS];
  88
  89         if (v == SEQ_START_TOKEN) {
  90                 seq_printf(m, "all lock classes:\n");
  91                 return 0;
  92         }
  93
  94         seq_printf(m, "%p", class->key);
  95 #ifdef CONFIG_DEBUG_LOCKDEP
  96         seq_printf(m, " OPS:%8ld", class->ops);
  97 #endif
  98 #ifdef CONFIG_PROVE_LOCKING
  99         seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class));
 100         seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class));
 101 #endif
 102
 103         get_usage_chars(class, usage);
 104         seq_printf(m, " %s", usage);
 105
 106         seq_printf(m, ": ");
 107         print_name(m, class);
 108         seq_puts(m, "\n");
 109
 110         list_for_each_entry(entry, &class->locks_after, entry) {
 111                 if (entry->distance == 1) {
 112                         seq_printf(m, " -> [%p] ", entry->class->key);
 113                         print_name(m, entry->class);
 114                         seq_puts(m, "\n");
 115                 }
 116         }
 117         seq_puts(m, "\n");
 118
 119         return 0;
 120 }
 121
 122 static const struct seq_operations lockdep_ops = {
 123         .start  = l_start,
 124         .next   = l_next,
 125         .stop   = l_stop,
 126         .show   = l_show,
 127 };
 128
 129 static int lockdep_open(struct inode *inode, struct file *file)
 130 {
 131         int res = seq_open(file, &lockdep_ops);
 132         if (!res) {
 133                 struct seq_file *m = file->private_data;
 134
 135                 if (!list_empty(&all_lock_classes))
 136                         m->private = list_entry(all_lock_classes.next,
 137                                         struct lock_class, lock_entry);
 138                 else
 139                         m->private = NULL;
 140         }
 141         return res;
 142 }
 143
 144 static const struct file_operations proc_lockdep_operations = {
 145         .open           = lockdep_open,
 146         .read           = seq_read,
 147         .llseek         = seq_lseek,
 148         .release        = seq_release,
 149 };
 150
 151 #ifdef CONFIG_PROVE_LOCKING
 152 static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
 153 {
 154         struct lock_chain *chain;
 155
 156         (*pos)++;
 157
 158         if (v == SEQ_START_TOKEN)
 159                 chain = m->private;
 160         else {
 161                 chain = v;
 162
 163                 if (*pos < nr_lock_chains)
 164                         chain = lock_chains + *pos;
 165                 else
 166                         chain = NULL;
 167         }
 168
 169         return chain;
 170 }
 171
 172 static void *lc_start(struct seq_file *m, loff_t *pos)
 173 {
 174         if (*pos == 0)
 175                 return SEQ_START_TOKEN;
 176
 177         if (*pos < nr_lock_chains)
 178                 return lock_chains + *pos;
 179
 180         return NULL;
 181 }
 182
 183 static void lc_stop(struct seq_file *m, void *v)
 184 {
 185 }
 186
 187 static int lc_show(struct seq_file *m, void *v)
 188 {
 189         struct lock_chain *chain = v;
 190         struct lock_class *class;
 191         int i;
 192
 193         if (v == SEQ_START_TOKEN) {
 194                 seq_printf(m, "all lock chains:\n");
 195                 return 0;
 196         }
 197
 198         seq_printf(m, "irq_context: %d\n", chain->irq_context);
 199
 200         for (i = 0; i < chain->depth; i++) {
 201                 class = lock_chain_get_class(chain, i);
 202                 if (!class->key)
 203                         continue;
 204
 205                 seq_printf(m, "[%p] ", class->key);
 206                 print_name(m, class);
 207                 seq_puts(m, "\n");
 208         }
 209         seq_puts(m, "\n");
 210
 211         return 0;
 212 }
 213
 214 static const struct seq_operations lockdep_chains_ops = {
 215         .start  = lc_start,
 216         .next   = lc_next,
 217         .stop   = lc_stop,
 218         .show   = lc_show,
 219 };
 220
 221 static int lockdep_chains_open(struct inode *inode, struct file *file)
 222 {
 223         int res = seq_open(file, &lockdep_chains_ops);
 224         if (!res) {
 225                 struct seq_file *m = file->private_data;
 226
 227                 if (nr_lock_chains)
 228                         m->private = lock_chains;
 229                 else
 230                         m->private = NULL;
 231         }
 232         return res;
 233 }
 234
 235 static const struct file_operations proc_lockdep_chains_operations = {
 236         .open           = lockdep_chains_open,
 237         .read           = seq_read,
 238         .llseek         = seq_lseek,
 239         .release        = seq_release,
 240 };
 241 #endif /* CONFIG_PROVE_LOCKING */
 242
 243 static void lockdep_stats_debug_show(struct seq_file *m)
 244 {
 245 #ifdef CONFIG_DEBUG_LOCKDEP
 246         unsigned int hi1 = debug_atomic_read(&hardirqs_on_events),
 247                      hi2 = debug_atomic_read(&hardirqs_off_events),
 248                      hr1 = debug_atomic_read(&redundant_hardirqs_on),
 249                      hr2 = debug_atomic_read(&redundant_hardirqs_off),
 250                      si1 = debug_atomic_read(&softirqs_on_events),
 251                      si2 = debug_atomic_read(&softirqs_off_events),
 252                      sr1 = debug_atomic_read(&redundant_softirqs_on),
 253                      sr2 = debug_atomic_read(&redundant_softirqs_off);
 254
 255         seq_printf(m, " chain lookup misses:           %11u\n",
 256                 debug_atomic_read(&chain_lookup_misses));
 257         seq_printf(m, " chain lookup hits:             %11u\n",
 258                 debug_atomic_read(&chain_lookup_hits));
 259         seq_printf(m, " cyclic checks:                 %11u\n",
 260                 debug_atomic_read(&nr_cyclic_checks));
 261         seq_printf(m, " cyclic-check recursions:       %11u\n",
 262                 debug_atomic_read(&nr_cyclic_check_recursions));
 263         seq_printf(m, " find-mask forwards checks:     %11u\n",
 264                 debug_atomic_read(&nr_find_usage_forwards_checks));
 265         seq_printf(m, " find-mask forwards recursions: %11u\n",
 266                 debug_atomic_read(&nr_find_usage_forwards_recursions));
 267         seq_printf(m, " find-mask backwards checks:    %11u\n",
 268                 debug_atomic_read(&nr_find_usage_backwards_checks));
 269         seq_printf(m, " find-mask backwards recursions:%11u\n",
 270                 debug_atomic_read(&nr_find_usage_backwards_recursions));
 271
 272         seq_printf(m, " hardirq on events:             %11u\n", hi1);
 273         seq_printf(m, " hardirq off events:            %11u\n", hi2);
 274         seq_printf(m, " redundant hardirq ons:         %11u\n", hr1);
 275         seq_printf(m, " redundant hardirq offs:        %11u\n", hr2);
 276         seq_printf(m, " softirq on events:             %11u\n", si1);
 277         seq_printf(m, " softirq off events:            %11u\n", si2);
 278         seq_printf(m, " redundant softirq ons:         %11u\n", sr1);
 279         seq_printf(m, " redundant softirq offs:        %11u\n", sr2);
 280 #endif
 281 }
 282
 283 static int lockdep_stats_show(struct seq_file *m, void *v)
 284 {
 285         struct lock_class *class;
 286         unsigned long nr_unused = 0, nr_uncategorized = 0,
 287                       nr_irq_safe = 0, nr_irq_unsafe = 0,
 288                       nr_softirq_safe = 0, nr_softirq_unsafe = 0,
 289                       nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
 290                       nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
 291                       nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
 292                       nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
 293                       sum_forward_deps = 0, factor = 0;
 294
 295         list_for_each_entry(class, &all_lock_classes, lock_entry) {
 296
 297                 if (class->usage_mask == 0)
 298                         nr_unused++;
 299                 if (class->usage_mask == LOCKF_USED)
 300                         nr_uncategorized++;
 301                 if (class->usage_mask & LOCKF_USED_IN_IRQ)
 302                         nr_irq_safe++;
 303                 if (class->usage_mask & LOCKF_ENABLED_IRQ)
 304                         nr_irq_unsafe++;
 305                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
 306                         nr_softirq_safe++;
 307                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
 308                         nr_softirq_unsafe++;
 309                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
 310                         nr_hardirq_safe++;
 311                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
 312                         nr_hardirq_unsafe++;
 313                 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
 314                         nr_irq_read_safe++;
 315                 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
 316                         nr_irq_read_unsafe++;
 317                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
 318                         nr_softirq_read_safe++;
 319                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
 320                         nr_softirq_read_unsafe++;
 321                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
 322                         nr_hardirq_read_safe++;
 323                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
 324                         nr_hardirq_read_unsafe++;
 325
 326 #ifdef CONFIG_PROVE_LOCKING
 327                 sum_forward_deps += lockdep_count_forward_deps(class);
 328 #endif
 329         }
 330 #ifdef CONFIG_DEBUG_LOCKDEP
 331         DEBUG_LOCKS_WARN_ON(debug_atomic_read(&nr_unused_locks) != nr_unused);
 332 #endif
 333         seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
 334                         nr_lock_classes, MAX_LOCKDEP_KEYS);
 335         seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
 336                         nr_list_entries, MAX_LOCKDEP_ENTRIES);
 337         seq_printf(m, " indirect dependencies:         %11lu\n",
 338                         sum_forward_deps);
 339
 340         /*
 341          * Total number of dependencies:
 342          *
 343          * All irq-safe locks may nest inside irq-unsafe locks,
 344          * plus all the other known dependencies:
 345          */
 346         seq_printf(m, " all direct dependencies:       %11lu\n",
 347                         nr_irq_unsafe * nr_irq_safe +
 348                         nr_hardirq_unsafe * nr_hardirq_safe +
 349                         nr_list_entries);
 350
 351         /*
 352          * Estimated factor between direct and indirect
 353          * dependencies:
 354          */
 355         if (nr_list_entries)
 356                 factor = sum_forward_deps / nr_list_entries;
 357
 358 #ifdef CONFIG_PROVE_LOCKING
 359         seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
 360                         nr_lock_chains, MAX_LOCKDEP_CHAINS);
 361         seq_printf(m, " dependency chain hlocks:       %11d [max: %lu]\n",
 362                         nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
 363 #endif
 364
 365 #ifdef CONFIG_TRACE_IRQFLAGS
 366         seq_printf(m, " in-hardirq chains:             %11u\n",
 367                         nr_hardirq_chains);
 368         seq_printf(m, " in-softirq chains:             %11u\n",
 369                         nr_softirq_chains);
 370 #endif
 371         seq_printf(m, " in-process chains:             %11u\n",
 372                         nr_process_chains);
 373         seq_printf(m, " stack-trace entries:           %11lu [max: %lu]\n",
 374                         nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
 375         seq_printf(m, " combined max dependencies:     %11u\n",
 376                         (nr_hardirq_chains + 1) *
 377                         (nr_softirq_chains + 1) *
 378                         (nr_process_chains + 1)
 379         );
 380         seq_printf(m, " hardirq-safe locks:            %11lu\n",
 381                         nr_hardirq_safe);
 382         seq_printf(m, " hardirq-unsafe locks:          %11lu\n",
 383                         nr_hardirq_unsafe);
 384         seq_printf(m, " softirq-safe locks:            %11lu\n",
 385                         nr_softirq_safe);
 386         seq_printf(m, " softirq-unsafe locks:          %11lu\n",
 387                         nr_softirq_unsafe);
 388         seq_printf(m, " irq-safe locks:                %11lu\n",
 389                         nr_irq_safe);
 390         seq_printf(m, " irq-unsafe locks:              %11lu\n",
 391                         nr_irq_unsafe);
 392
 393         seq_printf(m, " hardirq-read-safe locks:       %11lu\n",
 394                         nr_hardirq_read_safe);
 395         seq_printf(m, " hardirq-read-unsafe locks:     %11lu\n",
 396                         nr_hardirq_read_unsafe);
 397         seq_printf(m, " softirq-read-safe locks:       %11lu\n",
 398                         nr_softirq_read_safe);
 399         seq_printf(m, " softirq-read-unsafe locks:     %11lu\n",
 400                         nr_softirq_read_unsafe);
 401         seq_printf(m, " irq-read-safe locks:           %11lu\n",
 402                         nr_irq_read_safe);
 403         seq_printf(m, " irq-read-unsafe locks:         %11lu\n",
 404                         nr_irq_read_unsafe);
 405
 406         seq_printf(m, " uncategorized locks:           %11lu\n",
 407                         nr_uncategorized);
 408         seq_printf(m, " unused locks:                  %11lu\n",
 409                         nr_unused);
 410         seq_printf(m, " max locking depth:             %11u\n",
 411                         max_lockdep_depth);
 412         seq_printf(m, " max recursion depth:           %11u\n",
 413                         max_recursion_depth);
 414         lockdep_stats_debug_show(m);
 415         seq_printf(m, " debug_locks:                   %11u\n",
 416                         debug_locks);
 417
 418         return 0;
 419 }
 420
 421 static int lockdep_stats_open(struct inode *inode, struct file *file)
 422 {
 423         return single_open(file, lockdep_stats_show, NULL);
 424 }
 425
 426 static const struct file_operations proc_lockdep_stats_operations = {
 427         .open           = lockdep_stats_open,
 428         .read           = seq_read,
 429         .llseek         = seq_lseek,
 430         .release        = single_release,
 431 };
 432
 433 #ifdef CONFIG_LOCK_STAT
 434
 435 struct lock_stat_data {
 436         struct lock_class *class;
 437         struct lock_class_stats stats;
 438 };
 439
 440 struct lock_stat_seq {
 441         struct lock_stat_data *iter;
 442         struct lock_stat_data *iter_end;
 443         struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
 444 };
 445
 446 /*
 447  * sort on absolute number of contentions
 448  */
 449 static int lock_stat_cmp(const void *l, const void *r)
 450 {
 451         const struct lock_stat_data *dl = l, *dr = r;
 452         unsigned long nl, nr;
 453
 454         nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
 455         nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
 456
 457         return nr - nl;
 458 }
 459
 460 static void seq_line(struct seq_file *m, char c, int offset, int length)
 461 {
 462         int i;
 463
 464         for (i = 0; i < offset; i++)
 465                 seq_puts(m, " ");
 466         for (i = 0; i < length; i++)
 467                 seq_printf(m, "%c", c);
 468         seq_puts(m, "\n");
 469 }
 470
 471 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
 472 {
 473         s64 div;
 474         s32 rem;
 475
 476         nr += 5; /* for display rounding */
 477         div = div_s64_rem(nr, 1000, &rem);
 478         snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
 479 }
 480
 481 static void seq_time(struct seq_file *m, s64 time)
 482 {
 483         char num[15];
 484
 485         snprint_time(num, sizeof(num), time);
 486         seq_printf(m, " %14s", num);
 487 }
 488
 489 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
 490 {
 491         seq_printf(m, "%14lu", lt->nr);
 492         seq_time(m, lt->min);
 493         seq_time(m, lt->max);
 494         seq_time(m, lt->total);
 495 }
 496
 497 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 498 {
 499         char name[39];
 500         struct lock_class *class;
 501         struct lock_class_stats *stats;
 502         int i, namelen;
 503
 504         class = data->class;
 505         stats = &data->stats;
 506
 507         namelen = 38;
 508         if (class->name_version > 1)
 509                 namelen -= 2; /* XXX truncates versions > 9 */
 510         if (class->subclass)
 511                 namelen -= 2;
 512
 513         if (!class->name) {
 514                 char str[KSYM_NAME_LEN];
 515                 const char *key_name;
 516
 517                 key_name = __get_key_name(class->key, str);
 518                 snprintf(name, namelen, "%s", key_name);
 519         } else {
 520                 snprintf(name, namelen, "%s", class->name);
 521         }
 522         namelen = strlen(name);
 523         if (class->name_version > 1) {
 524                 snprintf(name+namelen, 3, "#%d", class->name_version);
 525                 namelen += 2;
 526         }
 527         if (class->subclass) {
 528                 snprintf(name+namelen, 3, "/%d", class->subclass);
 529                 namelen += 2;
 530         }
 531
 532         if (stats->write_holdtime.nr) {
 533                 if (stats->read_holdtime.nr)
 534                         seq_printf(m, "%38s-W:", name);
 535                 else
 536                         seq_printf(m, "%40s:", name);
 537
 538                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
 539                 seq_lock_time(m, &stats->write_waittime);
 540                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
 541                 seq_lock_time(m, &stats->write_holdtime);
 542                 seq_puts(m, "\n");
 543         }
 544
 545         if (stats->read_holdtime.nr) {
 546                 seq_printf(m, "%38s-R:", name);
 547                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
 548                 seq_lock_time(m, &stats->read_waittime);
 549                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
 550                 seq_lock_time(m, &stats->read_holdtime);
 551                 seq_puts(m, "\n");
 552         }
 553
 554         if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
 555                 return;
 556
 557         if (stats->read_holdtime.nr)
 558                 namelen += 2;
 559
 560         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 561                 char sym[KSYM_SYMBOL_LEN];
 562                 char ip[32];
 563
 564                 if (class->contention_point[i] == 0)
 565                         break;
 566
 567                 if (!i)
 568                         seq_line(m, '-', 40-namelen, namelen);
 569
 570                 sprint_symbol(sym, class->contention_point[i]);
 571                 snprintf(ip, sizeof(ip), "[<%p>]",
 572                                 (void *)class->contention_point[i]);
 573                 seq_printf(m, "%40s %14lu %29s %s\n", name,
 574                                 stats->contention_point[i],
 575                                 ip, sym);
 576         }
 577         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 578                 char sym[KSYM_SYMBOL_LEN];
 579                 char ip[32];
 580
 581                 if (class->contending_point[i] == 0)
 582                         break;
 583
 584                 if (!i)
 585                         seq_line(m, '-', 40-namelen, namelen);
 586
 587                 sprint_symbol(sym, class->contending_point[i]);
 588                 snprintf(ip, sizeof(ip), "[<%p>]",
 589                                 (void *)class->contending_point[i]);
 590                 seq_printf(m, "%40s %14lu %29s %s\n", name,
 591                                 stats->contending_point[i],
 592                                 ip, sym);
 593         }
 594         if (i) {
 595                 seq_puts(m, "\n");
 596                 seq_line(m, '.', 0, 40 + 1 + 10 * (14 + 1));
 597                 seq_puts(m, "\n");
 598         }
 599 }
 600
 601 static void seq_header(struct seq_file *m)
 602 {
 603         seq_printf(m, "lock_stat version 0.3\n");
 604
 605         if (unlikely(!debug_locks))
 606                 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
 607
 608         seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
 609         seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
 610                         "%14s %14s\n",
 611                         "class name",
 612                         "con-bounces",
 613                         "contentions",
 614                         "waittime-min",
 615                         "waittime-max",
 616                         "waittime-total",
 617                         "acq-bounces",
 618                         "acquisitions",
 619                         "holdtime-min",
 620                         "holdtime-max",
 621                         "holdtime-total");
 622         seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
 623         seq_printf(m, "\n");
 624 }
 625
 626 static void *ls_start(struct seq_file *m, loff_t *pos)
 627 {
 628         struct lock_stat_seq *data = m->private;
 629
 630         if (*pos == 0)
 631                 return SEQ_START_TOKEN;
 632
 633         data->iter = data->stats + *pos;
 634         if (data->iter >= data->iter_end)
 635                 data->iter = NULL;
 636
 637         return data->iter;
 638 }
 639
 640 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
 641 {
 642         struct lock_stat_seq *data = m->private;
 643
 644         (*pos)++;
 645
 646         if (v == SEQ_START_TOKEN)
 647                 data->iter = data->stats;
 648         else {
 649                 data->iter = v;
 650                 data->iter++;
 651         }
 652
 653         if (data->iter == data->iter_end)
 654                 data->iter = NULL;
 655
 656         return data->iter;
 657 }
 658
 659 static void ls_stop(struct seq_file *m, void *v)
 660 {
 661 }
 662
 663 static int ls_show(struct seq_file *m, void *v)
 664 {
 665         if (v == SEQ_START_TOKEN)
 666                 seq_header(m);
 667         else
 668                 seq_stats(m, v);
 669
 670         return 0;
 671 }
 672
 673 static struct seq_operations lockstat_ops = {
 674         .start  = ls_start,
 675         .next   = ls_next,
 676         .stop   = ls_stop,
 677         .show   = ls_show,
 678 };
 679
 680 static int lock_stat_open(struct inode *inode, struct file *file)
 681 {
 682         int res;
 683         struct lock_class *class;
 684         struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
 685
 686         if (!data)
 687                 return -ENOMEM;
 688
 689         res = seq_open(file, &lockstat_ops);
 690         if (!res) {
 691                 struct lock_stat_data *iter = data->stats;
 692                 struct seq_file *m = file->private_data;
 693
 694                 data->iter = iter;
 695                 list_for_each_entry(class, &all_lock_classes, lock_entry) {
 696                         iter->class = class;
 697                         iter->stats = lock_stats(class);
 698                         iter++;
 699                 }
 700                 data->iter_end = iter;
 701
 702                 sort(data->stats, data->iter_end - data->iter,
 703                                 sizeof(struct lock_stat_data),
 704                                 lock_stat_cmp, NULL);
 705
 706                 m->private = data;
 707         } else
 708                 vfree(data);
 709
 710         return res;
 711 }
 712
 713 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
 714                                size_t count, loff_t *ppos)
 715 {
 716         struct lock_class *class;
 717         char c;
 718
 719         if (count) {
 720                 if (get_user(c, buf))
 721                         return -EFAULT;
 722
 723                 if (c != '0')
 724                         return count;
 725
 726                 list_for_each_entry(class, &all_lock_classes, lock_entry)
 727                         clear_lock_stats(class);
 728         }
 729         return count;
 730 }
 731
 732 static int lock_stat_release(struct inode *inode, struct file *file)
 733 {
 734         struct seq_file *seq = file->private_data;
 735
 736         vfree(seq->private);
 737         seq->private = NULL;
 738         return seq_release(inode, file);
 739 }
 740
 741 static const struct file_operations proc_lock_stat_operations = {
 742         .open           = lock_stat_open,
 743         .write          = lock_stat_write,
 744         .read           = seq_read,
 745         .llseek         = seq_lseek,
 746         .release        = lock_stat_release,
 747 };
 748 #endif /* CONFIG_LOCK_STAT */
 749
 750 static int __init lockdep_proc_init(void)
 751 {
 752         proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
 753 #ifdef CONFIG_PROVE_LOCKING
 754         proc_create("lockdep_chains", S_IRUSR, NULL,
 755                     &proc_lockdep_chains_operations);
 756 #endif
 757         proc_create("lockdep_stats", S_IRUSR, NULL,
 758                     &proc_lockdep_stats_operations);
 759
 760 #ifdef CONFIG_LOCK_STAT
 761         proc_create("lock_stat", S_IRUSR, NULL, &proc_lock_stat_operations);
 762 #endif
 763
 764         return 0;
 765 }
 766
 767 __initcall(lockdep_proc_init);
 768