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lockdep_proc.c
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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 <[email protected]>
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 <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  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[128];
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  seq_printf(m, "all lock chains:\n");
145  return 0;
146  }
147 
148  seq_printf(m, "irq_context: %d\n", chain->irq_context);
149 
150  for (i = 0; i < chain->depth; i++) {
151  class = lock_chain_get_class(chain, i);
152  if (!class->key)
153  continue;
154 
155  seq_printf(m, "[%p] ", class->key);
156  print_name(m, class);
157  seq_puts(m, "\n");
158  }
159  seq_puts(m, "\n");
160 
161  return 0;
162 }
163 
164 static const struct seq_operations lockdep_chains_ops = {
165  .start = lc_start,
166  .next = lc_next,
167  .stop = lc_stop,
168  .show = lc_show,
169 };
170 
171 static int lockdep_chains_open(struct inode *inode, struct file *file)
172 {
173  return seq_open(file, &lockdep_chains_ops);
174 }
175 
176 static const struct file_operations proc_lockdep_chains_operations = {
177  .open = lockdep_chains_open,
178  .read = seq_read,
179  .llseek = seq_lseek,
180  .release = seq_release,
181 };
182 #endif /* CONFIG_PROVE_LOCKING */
183 
184 static void lockdep_stats_debug_show(struct seq_file *m)
185 {
186 #ifdef CONFIG_DEBUG_LOCKDEP
187  unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
188  hi2 = debug_atomic_read(hardirqs_off_events),
189  hr1 = debug_atomic_read(redundant_hardirqs_on),
190  hr2 = debug_atomic_read(redundant_hardirqs_off),
191  si1 = debug_atomic_read(softirqs_on_events),
192  si2 = debug_atomic_read(softirqs_off_events),
193  sr1 = debug_atomic_read(redundant_softirqs_on),
194  sr2 = debug_atomic_read(redundant_softirqs_off);
195 
196  seq_printf(m, " chain lookup misses: %11llu\n",
197  debug_atomic_read(chain_lookup_misses));
198  seq_printf(m, " chain lookup hits: %11llu\n",
199  debug_atomic_read(chain_lookup_hits));
200  seq_printf(m, " cyclic checks: %11llu\n",
201  debug_atomic_read(nr_cyclic_checks));
202  seq_printf(m, " find-mask forwards checks: %11llu\n",
203  debug_atomic_read(nr_find_usage_forwards_checks));
204  seq_printf(m, " find-mask backwards checks: %11llu\n",
205  debug_atomic_read(nr_find_usage_backwards_checks));
206 
207  seq_printf(m, " hardirq on events: %11llu\n", hi1);
208  seq_printf(m, " hardirq off events: %11llu\n", hi2);
209  seq_printf(m, " redundant hardirq ons: %11llu\n", hr1);
210  seq_printf(m, " redundant hardirq offs: %11llu\n", hr2);
211  seq_printf(m, " softirq on events: %11llu\n", si1);
212  seq_printf(m, " softirq off events: %11llu\n", si2);
213  seq_printf(m, " redundant softirq ons: %11llu\n", sr1);
214  seq_printf(m, " redundant softirq offs: %11llu\n", sr2);
215 #endif
216 }
217 
218 static int lockdep_stats_show(struct seq_file *m, void *v)
219 {
220  struct lock_class *class;
221  unsigned long nr_unused = 0, nr_uncategorized = 0,
222  nr_irq_safe = 0, nr_irq_unsafe = 0,
223  nr_softirq_safe = 0, nr_softirq_unsafe = 0,
224  nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
225  nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
226  nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
227  nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
228  sum_forward_deps = 0;
229 
230  list_for_each_entry(class, &all_lock_classes, lock_entry) {
231 
232  if (class->usage_mask == 0)
233  nr_unused++;
234  if (class->usage_mask == LOCKF_USED)
235  nr_uncategorized++;
236  if (class->usage_mask & LOCKF_USED_IN_IRQ)
237  nr_irq_safe++;
238  if (class->usage_mask & LOCKF_ENABLED_IRQ)
239  nr_irq_unsafe++;
240  if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
241  nr_softirq_safe++;
242  if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
243  nr_softirq_unsafe++;
244  if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
245  nr_hardirq_safe++;
246  if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
247  nr_hardirq_unsafe++;
248  if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
249  nr_irq_read_safe++;
250  if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
251  nr_irq_read_unsafe++;
252  if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
253  nr_softirq_read_safe++;
254  if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
255  nr_softirq_read_unsafe++;
256  if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
257  nr_hardirq_read_safe++;
258  if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
259  nr_hardirq_read_unsafe++;
260 
261 #ifdef CONFIG_PROVE_LOCKING
262  sum_forward_deps += lockdep_count_forward_deps(class);
263 #endif
264  }
265 #ifdef CONFIG_DEBUG_LOCKDEP
266  DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
267 #endif
268  seq_printf(m, " lock-classes: %11lu [max: %lu]\n",
269  nr_lock_classes, MAX_LOCKDEP_KEYS);
270  seq_printf(m, " direct dependencies: %11lu [max: %lu]\n",
271  nr_list_entries, MAX_LOCKDEP_ENTRIES);
272  seq_printf(m, " indirect dependencies: %11lu\n",
273  sum_forward_deps);
274 
275  /*
276  * Total number of dependencies:
277  *
278  * All irq-safe locks may nest inside irq-unsafe locks,
279  * plus all the other known dependencies:
280  */
281  seq_printf(m, " all direct dependencies: %11lu\n",
282  nr_irq_unsafe * nr_irq_safe +
283  nr_hardirq_unsafe * nr_hardirq_safe +
284  nr_list_entries);
285 
286 #ifdef CONFIG_PROVE_LOCKING
287  seq_printf(m, " dependency chains: %11lu [max: %lu]\n",
288  nr_lock_chains, MAX_LOCKDEP_CHAINS);
289  seq_printf(m, " dependency chain hlocks: %11d [max: %lu]\n",
290  nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
291 #endif
292 
293 #ifdef CONFIG_TRACE_IRQFLAGS
294  seq_printf(m, " in-hardirq chains: %11u\n",
295  nr_hardirq_chains);
296  seq_printf(m, " in-softirq chains: %11u\n",
297  nr_softirq_chains);
298 #endif
299  seq_printf(m, " in-process chains: %11u\n",
300  nr_process_chains);
301  seq_printf(m, " stack-trace entries: %11lu [max: %lu]\n",
302  nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
303  seq_printf(m, " combined max dependencies: %11u\n",
304  (nr_hardirq_chains + 1) *
305  (nr_softirq_chains + 1) *
306  (nr_process_chains + 1)
307  );
308  seq_printf(m, " hardirq-safe locks: %11lu\n",
309  nr_hardirq_safe);
310  seq_printf(m, " hardirq-unsafe locks: %11lu\n",
311  nr_hardirq_unsafe);
312  seq_printf(m, " softirq-safe locks: %11lu\n",
313  nr_softirq_safe);
314  seq_printf(m, " softirq-unsafe locks: %11lu\n",
315  nr_softirq_unsafe);
316  seq_printf(m, " irq-safe locks: %11lu\n",
317  nr_irq_safe);
318  seq_printf(m, " irq-unsafe locks: %11lu\n",
319  nr_irq_unsafe);
320 
321  seq_printf(m, " hardirq-read-safe locks: %11lu\n",
322  nr_hardirq_read_safe);
323  seq_printf(m, " hardirq-read-unsafe locks: %11lu\n",
324  nr_hardirq_read_unsafe);
325  seq_printf(m, " softirq-read-safe locks: %11lu\n",
326  nr_softirq_read_safe);
327  seq_printf(m, " softirq-read-unsafe locks: %11lu\n",
328  nr_softirq_read_unsafe);
329  seq_printf(m, " irq-read-safe locks: %11lu\n",
330  nr_irq_read_safe);
331  seq_printf(m, " irq-read-unsafe locks: %11lu\n",
332  nr_irq_read_unsafe);
333 
334  seq_printf(m, " uncategorized locks: %11lu\n",
335  nr_uncategorized);
336  seq_printf(m, " unused locks: %11lu\n",
337  nr_unused);
338  seq_printf(m, " max locking depth: %11u\n",
339  max_lockdep_depth);
340 #ifdef CONFIG_PROVE_LOCKING
341  seq_printf(m, " max bfs queue depth: %11u\n",
342  max_bfs_queue_depth);
343 #endif
344  lockdep_stats_debug_show(m);
345  seq_printf(m, " debug_locks: %11u\n",
346  debug_locks);
347 
348  return 0;
349 }
350 
351 static int lockdep_stats_open(struct inode *inode, struct file *file)
352 {
353  return single_open(file, lockdep_stats_show, NULL);
354 }
355 
356 static const struct file_operations proc_lockdep_stats_operations = {
357  .open = lockdep_stats_open,
358  .read = seq_read,
359  .llseek = seq_lseek,
360  .release = single_release,
361 };
362 
363 #ifdef CONFIG_LOCK_STAT
364 
365 struct lock_stat_data {
366  struct lock_class *class;
367  struct lock_class_stats stats;
368 };
369 
370 struct lock_stat_seq {
371  struct lock_stat_data *iter_end;
372  struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
373 };
374 
375 /*
376  * sort on absolute number of contentions
377  */
378 static int lock_stat_cmp(const void *l, const void *r)
379 {
380  const struct lock_stat_data *dl = l, *dr = r;
381  unsigned long nl, nr;
382 
383  nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
384  nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
385 
386  return nr - nl;
387 }
388 
389 static void seq_line(struct seq_file *m, char c, int offset, int length)
390 {
391  int i;
392 
393  for (i = 0; i < offset; i++)
394  seq_puts(m, " ");
395  for (i = 0; i < length; i++)
396  seq_printf(m, "%c", c);
397  seq_puts(m, "\n");
398 }
399 
400 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
401 {
402  s64 div;
403  s32 rem;
404 
405  nr += 5; /* for display rounding */
406  div = div_s64_rem(nr, 1000, &rem);
407  snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
408 }
409 
410 static void seq_time(struct seq_file *m, s64 time)
411 {
412  char num[15];
413 
414  snprint_time(num, sizeof(num), time);
415  seq_printf(m, " %14s", num);
416 }
417 
418 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
419 {
420  seq_printf(m, "%14lu", lt->nr);
421  seq_time(m, lt->min);
422  seq_time(m, lt->max);
423  seq_time(m, lt->total);
424 }
425 
426 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
427 {
428  char name[39];
429  struct lock_class *class;
430  struct lock_class_stats *stats;
431  int i, namelen;
432 
433  class = data->class;
434  stats = &data->stats;
435 
436  namelen = 38;
437  if (class->name_version > 1)
438  namelen -= 2; /* XXX truncates versions > 9 */
439  if (class->subclass)
440  namelen -= 2;
441 
442  if (!class->name) {
443  char str[KSYM_NAME_LEN];
444  const char *key_name;
445 
446  key_name = __get_key_name(class->key, str);
447  snprintf(name, namelen, "%s", key_name);
448  } else {
449  snprintf(name, namelen, "%s", class->name);
450  }
451  namelen = strlen(name);
452  if (class->name_version > 1) {
453  snprintf(name+namelen, 3, "#%d", class->name_version);
454  namelen += 2;
455  }
456  if (class->subclass) {
457  snprintf(name+namelen, 3, "/%d", class->subclass);
458  namelen += 2;
459  }
460 
461  if (stats->write_holdtime.nr) {
462  if (stats->read_holdtime.nr)
463  seq_printf(m, "%38s-W:", name);
464  else
465  seq_printf(m, "%40s:", name);
466 
467  seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
468  seq_lock_time(m, &stats->write_waittime);
469  seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
470  seq_lock_time(m, &stats->write_holdtime);
471  seq_puts(m, "\n");
472  }
473 
474  if (stats->read_holdtime.nr) {
475  seq_printf(m, "%38s-R:", name);
476  seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
477  seq_lock_time(m, &stats->read_waittime);
478  seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
479  seq_lock_time(m, &stats->read_holdtime);
480  seq_puts(m, "\n");
481  }
482 
483  if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
484  return;
485 
486  if (stats->read_holdtime.nr)
487  namelen += 2;
488 
489  for (i = 0; i < LOCKSTAT_POINTS; i++) {
490  char ip[32];
491 
492  if (class->contention_point[i] == 0)
493  break;
494 
495  if (!i)
496  seq_line(m, '-', 40-namelen, namelen);
497 
498  snprintf(ip, sizeof(ip), "[<%p>]",
499  (void *)class->contention_point[i]);
500  seq_printf(m, "%40s %14lu %29s %pS\n",
501  name, stats->contention_point[i],
502  ip, (void *)class->contention_point[i]);
503  }
504  for (i = 0; i < LOCKSTAT_POINTS; i++) {
505  char ip[32];
506 
507  if (class->contending_point[i] == 0)
508  break;
509 
510  if (!i)
511  seq_line(m, '-', 40-namelen, namelen);
512 
513  snprintf(ip, sizeof(ip), "[<%p>]",
514  (void *)class->contending_point[i]);
515  seq_printf(m, "%40s %14lu %29s %pS\n",
516  name, stats->contending_point[i],
517  ip, (void *)class->contending_point[i]);
518  }
519  if (i) {
520  seq_puts(m, "\n");
521  seq_line(m, '.', 0, 40 + 1 + 10 * (14 + 1));
522  seq_puts(m, "\n");
523  }
524 }
525 
526 static void seq_header(struct seq_file *m)
527 {
528  seq_printf(m, "lock_stat version 0.3\n");
529 
530  if (unlikely(!debug_locks))
531  seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
532 
533  seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
534  seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
535  "%14s %14s\n",
536  "class name",
537  "con-bounces",
538  "contentions",
539  "waittime-min",
540  "waittime-max",
541  "waittime-total",
542  "acq-bounces",
543  "acquisitions",
544  "holdtime-min",
545  "holdtime-max",
546  "holdtime-total");
547  seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
548  seq_printf(m, "\n");
549 }
550 
551 static void *ls_start(struct seq_file *m, loff_t *pos)
552 {
553  struct lock_stat_seq *data = m->private;
554  struct lock_stat_data *iter;
555 
556  if (*pos == 0)
557  return SEQ_START_TOKEN;
558 
559  iter = data->stats + (*pos - 1);
560  if (iter >= data->iter_end)
561  iter = NULL;
562 
563  return iter;
564 }
565 
566 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
567 {
568  (*pos)++;
569  return ls_start(m, pos);
570 }
571 
572 static void ls_stop(struct seq_file *m, void *v)
573 {
574 }
575 
576 static int ls_show(struct seq_file *m, void *v)
577 {
578  if (v == SEQ_START_TOKEN)
579  seq_header(m);
580  else
581  seq_stats(m, v);
582 
583  return 0;
584 }
585 
586 static const struct seq_operations lockstat_ops = {
587  .start = ls_start,
588  .next = ls_next,
589  .stop = ls_stop,
590  .show = ls_show,
591 };
592 
593 static int lock_stat_open(struct inode *inode, struct file *file)
594 {
595  int res;
596  struct lock_class *class;
597  struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
598 
599  if (!data)
600  return -ENOMEM;
601 
602  res = seq_open(file, &lockstat_ops);
603  if (!res) {
604  struct lock_stat_data *iter = data->stats;
605  struct seq_file *m = file->private_data;
606 
607  list_for_each_entry(class, &all_lock_classes, lock_entry) {
608  iter->class = class;
609  iter->stats = lock_stats(class);
610  iter++;
611  }
612  data->iter_end = iter;
613 
614  sort(data->stats, data->iter_end - data->stats,
615  sizeof(struct lock_stat_data),
616  lock_stat_cmp, NULL);
617 
618  m->private = data;
619  } else
620  vfree(data);
621 
622  return res;
623 }
624 
625 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
626  size_t count, loff_t *ppos)
627 {
628  struct lock_class *class;
629  char c;
630 
631  if (count) {
632  if (get_user(c, buf))
633  return -EFAULT;
634 
635  if (c != '0')
636  return count;
637 
638  list_for_each_entry(class, &all_lock_classes, lock_entry)
639  clear_lock_stats(class);
640  }
641  return count;
642 }
643 
644 static int lock_stat_release(struct inode *inode, struct file *file)
645 {
646  struct seq_file *seq = file->private_data;
647 
648  vfree(seq->private);
649  return seq_release(inode, file);
650 }
651 
652 static const struct file_operations proc_lock_stat_operations = {
653  .open = lock_stat_open,
654  .write = lock_stat_write,
655  .read = seq_read,
656  .llseek = seq_lseek,
657  .release = lock_stat_release,
658 };
659 #endif /* CONFIG_LOCK_STAT */
660 
661 static int __init lockdep_proc_init(void)
662 {
663  proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
664 #ifdef CONFIG_PROVE_LOCKING
665  proc_create("lockdep_chains", S_IRUSR, NULL,
666  &proc_lockdep_chains_operations);
667 #endif
668  proc_create("lockdep_stats", S_IRUSR, NULL,
669  &proc_lockdep_stats_operations);
670 
671 #ifdef CONFIG_LOCK_STAT
672  proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
673  &proc_lock_stat_operations);
674 #endif
675 
676  return 0;
677 }
678 
679 __initcall(lockdep_proc_init);
680 
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