xref: /linux-6.15/kernel/locking/lockdep_proc.c (revision 797b82eb)
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", debug_class_ops_read(class));
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 #ifdef CONFIG_PROVE_LOCKING
105 static void *lc_start(struct seq_file *m, loff_t *pos)
106 {
107 	if (*pos < 0)
108 		return NULL;
109 
110 	if (*pos == 0)
111 		return SEQ_START_TOKEN;
112 
113 	return lock_chains + (*pos - 1);
114 }
115 
116 static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
117 {
118 	*pos = lockdep_next_lockchain(*pos - 1) + 1;
119 	return lc_start(m, pos);
120 }
121 
122 static void lc_stop(struct seq_file *m, void *v)
123 {
124 }
125 
126 static int lc_show(struct seq_file *m, void *v)
127 {
128 	struct lock_chain *chain = v;
129 	struct lock_class *class;
130 	int i;
131 	static const char * const irq_strs[] = {
132 		[0]			     = "0",
133 		[LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq",
134 		[LOCK_CHAIN_SOFTIRQ_CONTEXT] = "softirq",
135 		[LOCK_CHAIN_SOFTIRQ_CONTEXT|
136 		 LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq|softirq",
137 	};
138 
139 	if (v == SEQ_START_TOKEN) {
140 		if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)
141 			seq_printf(m, "(buggered) ");
142 		seq_printf(m, "all lock chains:\n");
143 		return 0;
144 	}
145 
146 	seq_printf(m, "irq_context: %s\n", irq_strs[chain->irq_context]);
147 
148 	for (i = 0; i < chain->depth; i++) {
149 		class = lock_chain_get_class(chain, i);
150 		if (!class->key)
151 			continue;
152 
153 		seq_printf(m, "[%p] ", class->key);
154 		print_name(m, class);
155 		seq_puts(m, "\n");
156 	}
157 	seq_puts(m, "\n");
158 
159 	return 0;
160 }
161 
162 static const struct seq_operations lockdep_chains_ops = {
163 	.start	= lc_start,
164 	.next	= lc_next,
165 	.stop	= lc_stop,
166 	.show	= lc_show,
167 };
168 #endif /* CONFIG_PROVE_LOCKING */
169 
170 static void lockdep_stats_debug_show(struct seq_file *m)
171 {
172 #ifdef CONFIG_DEBUG_LOCKDEP
173 	unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
174 			   hi2 = debug_atomic_read(hardirqs_off_events),
175 			   hr1 = debug_atomic_read(redundant_hardirqs_on),
176 			   hr2 = debug_atomic_read(redundant_hardirqs_off),
177 			   si1 = debug_atomic_read(softirqs_on_events),
178 			   si2 = debug_atomic_read(softirqs_off_events),
179 			   sr1 = debug_atomic_read(redundant_softirqs_on),
180 			   sr2 = debug_atomic_read(redundant_softirqs_off);
181 
182 	seq_printf(m, " chain lookup misses:           %11llu\n",
183 		debug_atomic_read(chain_lookup_misses));
184 	seq_printf(m, " chain lookup hits:             %11llu\n",
185 		debug_atomic_read(chain_lookup_hits));
186 	seq_printf(m, " cyclic checks:                 %11llu\n",
187 		debug_atomic_read(nr_cyclic_checks));
188 	seq_printf(m, " redundant checks:              %11llu\n",
189 		debug_atomic_read(nr_redundant_checks));
190 	seq_printf(m, " redundant links:               %11llu\n",
191 		debug_atomic_read(nr_redundant));
192 	seq_printf(m, " find-mask forwards checks:     %11llu\n",
193 		debug_atomic_read(nr_find_usage_forwards_checks));
194 	seq_printf(m, " find-mask backwards checks:    %11llu\n",
195 		debug_atomic_read(nr_find_usage_backwards_checks));
196 
197 	seq_printf(m, " hardirq on events:             %11llu\n", hi1);
198 	seq_printf(m, " hardirq off events:            %11llu\n", hi2);
199 	seq_printf(m, " redundant hardirq ons:         %11llu\n", hr1);
200 	seq_printf(m, " redundant hardirq offs:        %11llu\n", hr2);
201 	seq_printf(m, " softirq on events:             %11llu\n", si1);
202 	seq_printf(m, " softirq off events:            %11llu\n", si2);
203 	seq_printf(m, " redundant softirq ons:         %11llu\n", sr1);
204 	seq_printf(m, " redundant softirq offs:        %11llu\n", sr2);
205 #endif
206 }
207 
208 static int lockdep_stats_show(struct seq_file *m, void *v)
209 {
210 	unsigned long nr_unused = 0, nr_uncategorized = 0,
211 		      nr_irq_safe = 0, nr_irq_unsafe = 0,
212 		      nr_softirq_safe = 0, nr_softirq_unsafe = 0,
213 		      nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
214 		      nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
215 		      nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
216 		      nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
217 		      sum_forward_deps = 0;
218 
219 #ifdef CONFIG_PROVE_LOCKING
220 	struct lock_class *class;
221 
222 	list_for_each_entry(class, &all_lock_classes, lock_entry) {
223 
224 		if (class->usage_mask == 0)
225 			nr_unused++;
226 		if (class->usage_mask == LOCKF_USED)
227 			nr_uncategorized++;
228 		if (class->usage_mask & LOCKF_USED_IN_IRQ)
229 			nr_irq_safe++;
230 		if (class->usage_mask & LOCKF_ENABLED_IRQ)
231 			nr_irq_unsafe++;
232 		if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
233 			nr_softirq_safe++;
234 		if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
235 			nr_softirq_unsafe++;
236 		if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
237 			nr_hardirq_safe++;
238 		if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
239 			nr_hardirq_unsafe++;
240 		if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
241 			nr_irq_read_safe++;
242 		if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
243 			nr_irq_read_unsafe++;
244 		if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
245 			nr_softirq_read_safe++;
246 		if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
247 			nr_softirq_read_unsafe++;
248 		if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
249 			nr_hardirq_read_safe++;
250 		if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
251 			nr_hardirq_read_unsafe++;
252 
253 		sum_forward_deps += lockdep_count_forward_deps(class);
254 	}
255 #ifdef CONFIG_DEBUG_LOCKDEP
256 	DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
257 #endif
258 
259 #endif
260 	seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
261 			nr_lock_classes, MAX_LOCKDEP_KEYS);
262 	seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
263 			nr_list_entries, MAX_LOCKDEP_ENTRIES);
264 	seq_printf(m, " indirect dependencies:         %11lu\n",
265 			sum_forward_deps);
266 
267 	/*
268 	 * Total number of dependencies:
269 	 *
270 	 * All irq-safe locks may nest inside irq-unsafe locks,
271 	 * plus all the other known dependencies:
272 	 */
273 	seq_printf(m, " all direct dependencies:       %11lu\n",
274 			nr_irq_unsafe * nr_irq_safe +
275 			nr_hardirq_unsafe * nr_hardirq_safe +
276 			nr_list_entries);
277 
278 #ifdef CONFIG_PROVE_LOCKING
279 	seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
280 			lock_chain_count(), MAX_LOCKDEP_CHAINS);
281 	seq_printf(m, " dependency chain hlocks:       %11u [max: %lu]\n",
282 			nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
283 #endif
284 
285 #ifdef CONFIG_TRACE_IRQFLAGS
286 	seq_printf(m, " in-hardirq chains:             %11u\n",
287 			nr_hardirq_chains);
288 	seq_printf(m, " in-softirq chains:             %11u\n",
289 			nr_softirq_chains);
290 #endif
291 	seq_printf(m, " in-process chains:             %11u\n",
292 			nr_process_chains);
293 	seq_printf(m, " stack-trace entries:           %11lu [max: %lu]\n",
294 			nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
295 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
296 	seq_printf(m, " number of stack traces:        %11llu\n",
297 		   lockdep_stack_trace_count());
298 	seq_printf(m, " number of stack hash chains:   %11llu\n",
299 		   lockdep_stack_hash_count());
300 #endif
301 	seq_printf(m, " combined max dependencies:     %11u\n",
302 			(nr_hardirq_chains + 1) *
303 			(nr_softirq_chains + 1) *
304 			(nr_process_chains + 1)
305 	);
306 	seq_printf(m, " hardirq-safe locks:            %11lu\n",
307 			nr_hardirq_safe);
308 	seq_printf(m, " hardirq-unsafe locks:          %11lu\n",
309 			nr_hardirq_unsafe);
310 	seq_printf(m, " softirq-safe locks:            %11lu\n",
311 			nr_softirq_safe);
312 	seq_printf(m, " softirq-unsafe locks:          %11lu\n",
313 			nr_softirq_unsafe);
314 	seq_printf(m, " irq-safe locks:                %11lu\n",
315 			nr_irq_safe);
316 	seq_printf(m, " irq-unsafe locks:              %11lu\n",
317 			nr_irq_unsafe);
318 
319 	seq_printf(m, " hardirq-read-safe locks:       %11lu\n",
320 			nr_hardirq_read_safe);
321 	seq_printf(m, " hardirq-read-unsafe locks:     %11lu\n",
322 			nr_hardirq_read_unsafe);
323 	seq_printf(m, " softirq-read-safe locks:       %11lu\n",
324 			nr_softirq_read_safe);
325 	seq_printf(m, " softirq-read-unsafe locks:     %11lu\n",
326 			nr_softirq_read_unsafe);
327 	seq_printf(m, " irq-read-safe locks:           %11lu\n",
328 			nr_irq_read_safe);
329 	seq_printf(m, " irq-read-unsafe locks:         %11lu\n",
330 			nr_irq_read_unsafe);
331 
332 	seq_printf(m, " uncategorized locks:           %11lu\n",
333 			nr_uncategorized);
334 	seq_printf(m, " unused locks:                  %11lu\n",
335 			nr_unused);
336 	seq_printf(m, " max locking depth:             %11u\n",
337 			max_lockdep_depth);
338 #ifdef CONFIG_PROVE_LOCKING
339 	seq_printf(m, " max bfs queue depth:           %11u\n",
340 			max_bfs_queue_depth);
341 #endif
342 	lockdep_stats_debug_show(m);
343 	seq_printf(m, " debug_locks:                   %11u\n",
344 			debug_locks);
345 
346 	/*
347 	 * Zappped classes and lockdep data buffers reuse statistics.
348 	 */
349 	seq_puts(m, "\n");
350 	seq_printf(m, " zapped classes:                %11lu\n",
351 			nr_zapped_classes);
352 #ifdef CONFIG_PROVE_LOCKING
353 	seq_printf(m, " zapped lock chains:            %11lu\n",
354 			nr_zapped_lock_chains);
355 #endif
356 	return 0;
357 }
358 
359 #ifdef CONFIG_LOCK_STAT
360 
361 struct lock_stat_data {
362 	struct lock_class *class;
363 	struct lock_class_stats stats;
364 };
365 
366 struct lock_stat_seq {
367 	struct lock_stat_data *iter_end;
368 	struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
369 };
370 
371 /*
372  * sort on absolute number of contentions
373  */
374 static int lock_stat_cmp(const void *l, const void *r)
375 {
376 	const struct lock_stat_data *dl = l, *dr = r;
377 	unsigned long nl, nr;
378 
379 	nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
380 	nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
381 
382 	return nr - nl;
383 }
384 
385 static void seq_line(struct seq_file *m, char c, int offset, int length)
386 {
387 	int i;
388 
389 	for (i = 0; i < offset; i++)
390 		seq_puts(m, " ");
391 	for (i = 0; i < length; i++)
392 		seq_printf(m, "%c", c);
393 	seq_puts(m, "\n");
394 }
395 
396 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
397 {
398 	s64 div;
399 	s32 rem;
400 
401 	nr += 5; /* for display rounding */
402 	div = div_s64_rem(nr, 1000, &rem);
403 	snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
404 }
405 
406 static void seq_time(struct seq_file *m, s64 time)
407 {
408 	char num[15];
409 
410 	snprint_time(num, sizeof(num), time);
411 	seq_printf(m, " %14s", num);
412 }
413 
414 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
415 {
416 	seq_printf(m, "%14lu", lt->nr);
417 	seq_time(m, lt->min);
418 	seq_time(m, lt->max);
419 	seq_time(m, lt->total);
420 	seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0);
421 }
422 
423 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
424 {
425 	const struct lockdep_subclass_key *ckey;
426 	struct lock_class_stats *stats;
427 	struct lock_class *class;
428 	const char *cname;
429 	int i, namelen;
430 	char name[39];
431 
432 	class = data->class;
433 	stats = &data->stats;
434 
435 	namelen = 38;
436 	if (class->name_version > 1)
437 		namelen -= 2; /* XXX truncates versions > 9 */
438 	if (class->subclass)
439 		namelen -= 2;
440 
441 	rcu_read_lock_sched();
442 	cname = rcu_dereference_sched(class->name);
443 	ckey  = rcu_dereference_sched(class->key);
444 
445 	if (!cname && !ckey) {
446 		rcu_read_unlock_sched();
447 		return;
448 
449 	} else if (!cname) {
450 		char str[KSYM_NAME_LEN];
451 		const char *key_name;
452 
453 		key_name = __get_key_name(ckey, str);
454 		snprintf(name, namelen, "%s", key_name);
455 	} else {
456 		snprintf(name, namelen, "%s", cname);
457 	}
458 	rcu_read_unlock_sched();
459 
460 	namelen = strlen(name);
461 	if (class->name_version > 1) {
462 		snprintf(name+namelen, 3, "#%d", class->name_version);
463 		namelen += 2;
464 	}
465 	if (class->subclass) {
466 		snprintf(name+namelen, 3, "/%d", class->subclass);
467 		namelen += 2;
468 	}
469 
470 	if (stats->write_holdtime.nr) {
471 		if (stats->read_holdtime.nr)
472 			seq_printf(m, "%38s-W:", name);
473 		else
474 			seq_printf(m, "%40s:", name);
475 
476 		seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
477 		seq_lock_time(m, &stats->write_waittime);
478 		seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
479 		seq_lock_time(m, &stats->write_holdtime);
480 		seq_puts(m, "\n");
481 	}
482 
483 	if (stats->read_holdtime.nr) {
484 		seq_printf(m, "%38s-R:", name);
485 		seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
486 		seq_lock_time(m, &stats->read_waittime);
487 		seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
488 		seq_lock_time(m, &stats->read_holdtime);
489 		seq_puts(m, "\n");
490 	}
491 
492 	if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
493 		return;
494 
495 	if (stats->read_holdtime.nr)
496 		namelen += 2;
497 
498 	for (i = 0; i < LOCKSTAT_POINTS; i++) {
499 		char ip[32];
500 
501 		if (class->contention_point[i] == 0)
502 			break;
503 
504 		if (!i)
505 			seq_line(m, '-', 40-namelen, namelen);
506 
507 		snprintf(ip, sizeof(ip), "[<%p>]",
508 				(void *)class->contention_point[i]);
509 		seq_printf(m, "%40s %14lu %29s %pS\n",
510 			   name, stats->contention_point[i],
511 			   ip, (void *)class->contention_point[i]);
512 	}
513 	for (i = 0; i < LOCKSTAT_POINTS; i++) {
514 		char ip[32];
515 
516 		if (class->contending_point[i] == 0)
517 			break;
518 
519 		if (!i)
520 			seq_line(m, '-', 40-namelen, namelen);
521 
522 		snprintf(ip, sizeof(ip), "[<%p>]",
523 				(void *)class->contending_point[i]);
524 		seq_printf(m, "%40s %14lu %29s %pS\n",
525 			   name, stats->contending_point[i],
526 			   ip, (void *)class->contending_point[i]);
527 	}
528 	if (i) {
529 		seq_puts(m, "\n");
530 		seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
531 		seq_puts(m, "\n");
532 	}
533 }
534 
535 static void seq_header(struct seq_file *m)
536 {
537 	seq_puts(m, "lock_stat version 0.4\n");
538 
539 	if (unlikely(!debug_locks))
540 		seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
541 
542 	seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
543 	seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
544 			"%14s %14s\n",
545 			"class name",
546 			"con-bounces",
547 			"contentions",
548 			"waittime-min",
549 			"waittime-max",
550 			"waittime-total",
551 			"waittime-avg",
552 			"acq-bounces",
553 			"acquisitions",
554 			"holdtime-min",
555 			"holdtime-max",
556 			"holdtime-total",
557 			"holdtime-avg");
558 	seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
559 	seq_printf(m, "\n");
560 }
561 
562 static void *ls_start(struct seq_file *m, loff_t *pos)
563 {
564 	struct lock_stat_seq *data = m->private;
565 	struct lock_stat_data *iter;
566 
567 	if (*pos == 0)
568 		return SEQ_START_TOKEN;
569 
570 	iter = data->stats + (*pos - 1);
571 	if (iter >= data->iter_end)
572 		iter = NULL;
573 
574 	return iter;
575 }
576 
577 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
578 {
579 	(*pos)++;
580 	return ls_start(m, pos);
581 }
582 
583 static void ls_stop(struct seq_file *m, void *v)
584 {
585 }
586 
587 static int ls_show(struct seq_file *m, void *v)
588 {
589 	if (v == SEQ_START_TOKEN)
590 		seq_header(m);
591 	else
592 		seq_stats(m, v);
593 
594 	return 0;
595 }
596 
597 static const struct seq_operations lockstat_ops = {
598 	.start	= ls_start,
599 	.next	= ls_next,
600 	.stop	= ls_stop,
601 	.show	= ls_show,
602 };
603 
604 static int lock_stat_open(struct inode *inode, struct file *file)
605 {
606 	int res;
607 	struct lock_class *class;
608 	struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
609 
610 	if (!data)
611 		return -ENOMEM;
612 
613 	res = seq_open(file, &lockstat_ops);
614 	if (!res) {
615 		struct lock_stat_data *iter = data->stats;
616 		struct seq_file *m = file->private_data;
617 
618 		list_for_each_entry(class, &all_lock_classes, lock_entry) {
619 			iter->class = class;
620 			iter->stats = lock_stats(class);
621 			iter++;
622 		}
623 		data->iter_end = iter;
624 
625 		sort(data->stats, data->iter_end - data->stats,
626 				sizeof(struct lock_stat_data),
627 				lock_stat_cmp, NULL);
628 
629 		m->private = data;
630 	} else
631 		vfree(data);
632 
633 	return res;
634 }
635 
636 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
637 			       size_t count, loff_t *ppos)
638 {
639 	struct lock_class *class;
640 	char c;
641 
642 	if (count) {
643 		if (get_user(c, buf))
644 			return -EFAULT;
645 
646 		if (c != '0')
647 			return count;
648 
649 		list_for_each_entry(class, &all_lock_classes, lock_entry)
650 			clear_lock_stats(class);
651 	}
652 	return count;
653 }
654 
655 static int lock_stat_release(struct inode *inode, struct file *file)
656 {
657 	struct seq_file *seq = file->private_data;
658 
659 	vfree(seq->private);
660 	return seq_release(inode, file);
661 }
662 
663 static const struct proc_ops lock_stat_proc_ops = {
664 	.proc_open	= lock_stat_open,
665 	.proc_write	= lock_stat_write,
666 	.proc_read	= seq_read,
667 	.proc_lseek	= seq_lseek,
668 	.proc_release	= lock_stat_release,
669 };
670 #endif /* CONFIG_LOCK_STAT */
671 
672 static int __init lockdep_proc_init(void)
673 {
674 	proc_create_seq("lockdep", S_IRUSR, NULL, &lockdep_ops);
675 #ifdef CONFIG_PROVE_LOCKING
676 	proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops);
677 #endif
678 	proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show);
679 #ifdef CONFIG_LOCK_STAT
680 	proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL, &lock_stat_proc_ops);
681 #endif
682 
683 	return 0;
684 }
685 
686 __initcall(lockdep_proc_init);
687 
688