1 // SPDX-License-Identifier: GPL-2.0
3 * kernel/lockdep_proc.c
5 * Runtime locking correctness validator
7 * Started by Ingo Molnar:
9 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
10 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
12 * Code for /proc/lockdep and /proc/lockdep_stats:
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>
25 #include "lockdep_internals.h"
27 static void *l_next(struct seq_file *m, void *v, loff_t *pos)
29 return seq_list_next(v, &all_lock_classes, pos);
32 static void *l_start(struct seq_file *m, loff_t *pos)
34 return seq_list_start_head(&all_lock_classes, *pos);
37 static void l_stop(struct seq_file *m, void *v)
41 static void print_name(struct seq_file *m, struct lock_class *class)
43 char str[KSYM_NAME_LEN];
44 const char *name = class->name;
47 name = __get_key_name(class->key, str);
48 seq_printf(m, "%s", name);
50 seq_printf(m, "%s", name);
51 if (class->name_version > 1)
52 seq_printf(m, "#%d", class->name_version);
54 seq_printf(m, "/%d", class->subclass);
58 static int l_show(struct seq_file *m, void *v)
60 struct lock_class *class = list_entry(v, struct lock_class, lock_entry);
61 struct lock_list *entry;
62 char usage[LOCK_USAGE_CHARS];
64 if (v == &all_lock_classes) {
65 seq_printf(m, "all lock classes:\n");
69 seq_printf(m, "%p", class->key);
70 #ifdef CONFIG_DEBUG_LOCKDEP
71 seq_printf(m, " OPS:%8ld", debug_class_ops_read(class));
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));
78 get_usage_chars(class, usage);
79 seq_printf(m, " %s", usage);
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);
97 static const struct seq_operations lockdep_ops = {
104 #ifdef CONFIG_PROVE_LOCKING
105 static void *lc_start(struct seq_file *m, loff_t *pos)
111 return SEQ_START_TOKEN;
113 return lock_chains + (*pos - 1);
116 static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
118 *pos = lockdep_next_lockchain(*pos - 1) + 1;
119 return lc_start(m, pos);
122 static void lc_stop(struct seq_file *m, void *v)
126 static int lc_show(struct seq_file *m, void *v)
128 struct lock_chain *chain = v;
129 struct lock_class *class;
132 if (v == SEQ_START_TOKEN) {
133 if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)
134 seq_printf(m, "(buggered) ");
135 seq_printf(m, "all lock chains:\n");
139 seq_printf(m, "irq_context: %d\n", chain->irq_context);
141 for (i = 0; i < chain->depth; i++) {
142 class = lock_chain_get_class(chain, i);
146 seq_printf(m, "[%p] ", class->key);
147 print_name(m, class);
155 static const struct seq_operations lockdep_chains_ops = {
161 #endif /* CONFIG_PROVE_LOCKING */
163 static void lockdep_stats_debug_show(struct seq_file *m)
165 #ifdef CONFIG_DEBUG_LOCKDEP
166 unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
167 hi2 = debug_atomic_read(hardirqs_off_events),
168 hr1 = debug_atomic_read(redundant_hardirqs_on),
169 hr2 = debug_atomic_read(redundant_hardirqs_off),
170 si1 = debug_atomic_read(softirqs_on_events),
171 si2 = debug_atomic_read(softirqs_off_events),
172 sr1 = debug_atomic_read(redundant_softirqs_on),
173 sr2 = debug_atomic_read(redundant_softirqs_off);
175 seq_printf(m, " chain lookup misses: %11llu\n",
176 debug_atomic_read(chain_lookup_misses));
177 seq_printf(m, " chain lookup hits: %11llu\n",
178 debug_atomic_read(chain_lookup_hits));
179 seq_printf(m, " cyclic checks: %11llu\n",
180 debug_atomic_read(nr_cyclic_checks));
181 seq_printf(m, " redundant checks: %11llu\n",
182 debug_atomic_read(nr_redundant_checks));
183 seq_printf(m, " redundant links: %11llu\n",
184 debug_atomic_read(nr_redundant));
185 seq_printf(m, " find-mask forwards checks: %11llu\n",
186 debug_atomic_read(nr_find_usage_forwards_checks));
187 seq_printf(m, " find-mask backwards checks: %11llu\n",
188 debug_atomic_read(nr_find_usage_backwards_checks));
190 seq_printf(m, " hardirq on events: %11llu\n", hi1);
191 seq_printf(m, " hardirq off events: %11llu\n", hi2);
192 seq_printf(m, " redundant hardirq ons: %11llu\n", hr1);
193 seq_printf(m, " redundant hardirq offs: %11llu\n", hr2);
194 seq_printf(m, " softirq on events: %11llu\n", si1);
195 seq_printf(m, " softirq off events: %11llu\n", si2);
196 seq_printf(m, " redundant softirq ons: %11llu\n", sr1);
197 seq_printf(m, " redundant softirq offs: %11llu\n", sr2);
201 static int lockdep_stats_show(struct seq_file *m, void *v)
203 struct lock_class *class;
204 unsigned long nr_unused = 0, nr_uncategorized = 0,
205 nr_irq_safe = 0, nr_irq_unsafe = 0,
206 nr_softirq_safe = 0, nr_softirq_unsafe = 0,
207 nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
208 nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
209 nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
210 nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
211 sum_forward_deps = 0;
213 #ifdef CONFIG_PROVE_LOCKING
214 list_for_each_entry(class, &all_lock_classes, lock_entry) {
216 if (class->usage_mask == 0)
218 if (class->usage_mask == LOCKF_USED)
220 if (class->usage_mask & LOCKF_USED_IN_IRQ)
222 if (class->usage_mask & LOCKF_ENABLED_IRQ)
224 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
226 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
228 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
230 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
232 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
234 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
235 nr_irq_read_unsafe++;
236 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
237 nr_softirq_read_safe++;
238 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
239 nr_softirq_read_unsafe++;
240 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
241 nr_hardirq_read_safe++;
242 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
243 nr_hardirq_read_unsafe++;
245 sum_forward_deps += lockdep_count_forward_deps(class);
247 #ifdef CONFIG_DEBUG_LOCKDEP
248 DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
252 seq_printf(m, " lock-classes: %11lu [max: %lu]\n",
253 nr_lock_classes, MAX_LOCKDEP_KEYS);
254 seq_printf(m, " direct dependencies: %11lu [max: %lu]\n",
255 nr_list_entries, MAX_LOCKDEP_ENTRIES);
256 seq_printf(m, " indirect dependencies: %11lu\n",
260 * Total number of dependencies:
262 * All irq-safe locks may nest inside irq-unsafe locks,
263 * plus all the other known dependencies:
265 seq_printf(m, " all direct dependencies: %11lu\n",
266 nr_irq_unsafe * nr_irq_safe +
267 nr_hardirq_unsafe * nr_hardirq_safe +
270 #ifdef CONFIG_PROVE_LOCKING
271 seq_printf(m, " dependency chains: %11lu [max: %lu]\n",
272 lock_chain_count(), MAX_LOCKDEP_CHAINS);
273 seq_printf(m, " dependency chain hlocks: %11d [max: %lu]\n",
274 nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
277 #ifdef CONFIG_TRACE_IRQFLAGS
278 seq_printf(m, " in-hardirq chains: %11u\n",
280 seq_printf(m, " in-softirq chains: %11u\n",
283 seq_printf(m, " in-process chains: %11u\n",
285 seq_printf(m, " stack-trace entries: %11lu [max: %lu]\n",
286 nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
287 seq_printf(m, " combined max dependencies: %11u\n",
288 (nr_hardirq_chains + 1) *
289 (nr_softirq_chains + 1) *
290 (nr_process_chains + 1)
292 seq_printf(m, " hardirq-safe locks: %11lu\n",
294 seq_printf(m, " hardirq-unsafe locks: %11lu\n",
296 seq_printf(m, " softirq-safe locks: %11lu\n",
298 seq_printf(m, " softirq-unsafe locks: %11lu\n",
300 seq_printf(m, " irq-safe locks: %11lu\n",
302 seq_printf(m, " irq-unsafe locks: %11lu\n",
305 seq_printf(m, " hardirq-read-safe locks: %11lu\n",
306 nr_hardirq_read_safe);
307 seq_printf(m, " hardirq-read-unsafe locks: %11lu\n",
308 nr_hardirq_read_unsafe);
309 seq_printf(m, " softirq-read-safe locks: %11lu\n",
310 nr_softirq_read_safe);
311 seq_printf(m, " softirq-read-unsafe locks: %11lu\n",
312 nr_softirq_read_unsafe);
313 seq_printf(m, " irq-read-safe locks: %11lu\n",
315 seq_printf(m, " irq-read-unsafe locks: %11lu\n",
318 seq_printf(m, " uncategorized locks: %11lu\n",
320 seq_printf(m, " unused locks: %11lu\n",
322 seq_printf(m, " max locking depth: %11u\n",
324 #ifdef CONFIG_PROVE_LOCKING
325 seq_printf(m, " max bfs queue depth: %11u\n",
326 max_bfs_queue_depth);
328 lockdep_stats_debug_show(m);
329 seq_printf(m, " debug_locks: %11u\n",
335 #ifdef CONFIG_LOCK_STAT
337 struct lock_stat_data {
338 struct lock_class *class;
339 struct lock_class_stats stats;
342 struct lock_stat_seq {
343 struct lock_stat_data *iter_end;
344 struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
348 * sort on absolute number of contentions
350 static int lock_stat_cmp(const void *l, const void *r)
352 const struct lock_stat_data *dl = l, *dr = r;
353 unsigned long nl, nr;
355 nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
356 nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
361 static void seq_line(struct seq_file *m, char c, int offset, int length)
365 for (i = 0; i < offset; i++)
367 for (i = 0; i < length; i++)
368 seq_printf(m, "%c", c);
372 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
377 nr += 5; /* for display rounding */
378 div = div_s64_rem(nr, 1000, &rem);
379 snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
382 static void seq_time(struct seq_file *m, s64 time)
386 snprint_time(num, sizeof(num), time);
387 seq_printf(m, " %14s", num);
390 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
392 seq_printf(m, "%14lu", lt->nr);
393 seq_time(m, lt->min);
394 seq_time(m, lt->max);
395 seq_time(m, lt->total);
396 seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0);
399 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
401 struct lockdep_subclass_key *ckey;
402 struct lock_class_stats *stats;
403 struct lock_class *class;
409 stats = &data->stats;
412 if (class->name_version > 1)
413 namelen -= 2; /* XXX truncates versions > 9 */
417 rcu_read_lock_sched();
418 cname = rcu_dereference_sched(class->name);
419 ckey = rcu_dereference_sched(class->key);
421 if (!cname && !ckey) {
422 rcu_read_unlock_sched();
426 char str[KSYM_NAME_LEN];
427 const char *key_name;
429 key_name = __get_key_name(ckey, str);
430 snprintf(name, namelen, "%s", key_name);
432 snprintf(name, namelen, "%s", cname);
434 rcu_read_unlock_sched();
436 namelen = strlen(name);
437 if (class->name_version > 1) {
438 snprintf(name+namelen, 3, "#%d", class->name_version);
441 if (class->subclass) {
442 snprintf(name+namelen, 3, "/%d", class->subclass);
446 if (stats->write_holdtime.nr) {
447 if (stats->read_holdtime.nr)
448 seq_printf(m, "%38s-W:", name);
450 seq_printf(m, "%40s:", name);
452 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
453 seq_lock_time(m, &stats->write_waittime);
454 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
455 seq_lock_time(m, &stats->write_holdtime);
459 if (stats->read_holdtime.nr) {
460 seq_printf(m, "%38s-R:", name);
461 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
462 seq_lock_time(m, &stats->read_waittime);
463 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
464 seq_lock_time(m, &stats->read_holdtime);
468 if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
471 if (stats->read_holdtime.nr)
474 for (i = 0; i < LOCKSTAT_POINTS; i++) {
477 if (class->contention_point[i] == 0)
481 seq_line(m, '-', 40-namelen, namelen);
483 snprintf(ip, sizeof(ip), "[<%p>]",
484 (void *)class->contention_point[i]);
485 seq_printf(m, "%40s %14lu %29s %pS\n",
486 name, stats->contention_point[i],
487 ip, (void *)class->contention_point[i]);
489 for (i = 0; i < LOCKSTAT_POINTS; i++) {
492 if (class->contending_point[i] == 0)
496 seq_line(m, '-', 40-namelen, namelen);
498 snprintf(ip, sizeof(ip), "[<%p>]",
499 (void *)class->contending_point[i]);
500 seq_printf(m, "%40s %14lu %29s %pS\n",
501 name, stats->contending_point[i],
502 ip, (void *)class->contending_point[i]);
506 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
511 static void seq_header(struct seq_file *m)
513 seq_puts(m, "lock_stat version 0.4\n");
515 if (unlikely(!debug_locks))
516 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
518 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
519 seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
534 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
538 static void *ls_start(struct seq_file *m, loff_t *pos)
540 struct lock_stat_seq *data = m->private;
541 struct lock_stat_data *iter;
544 return SEQ_START_TOKEN;
546 iter = data->stats + (*pos - 1);
547 if (iter >= data->iter_end)
553 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
556 return ls_start(m, pos);
559 static void ls_stop(struct seq_file *m, void *v)
563 static int ls_show(struct seq_file *m, void *v)
565 if (v == SEQ_START_TOKEN)
573 static const struct seq_operations lockstat_ops = {
580 static int lock_stat_open(struct inode *inode, struct file *file)
583 struct lock_class *class;
584 struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
589 res = seq_open(file, &lockstat_ops);
591 struct lock_stat_data *iter = data->stats;
592 struct seq_file *m = file->private_data;
594 list_for_each_entry(class, &all_lock_classes, lock_entry) {
596 iter->stats = lock_stats(class);
599 data->iter_end = iter;
601 sort(data->stats, data->iter_end - data->stats,
602 sizeof(struct lock_stat_data),
603 lock_stat_cmp, NULL);
612 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
613 size_t count, loff_t *ppos)
615 struct lock_class *class;
619 if (get_user(c, buf))
625 list_for_each_entry(class, &all_lock_classes, lock_entry)
626 clear_lock_stats(class);
631 static int lock_stat_release(struct inode *inode, struct file *file)
633 struct seq_file *seq = file->private_data;
636 return seq_release(inode, file);
639 static const struct file_operations proc_lock_stat_operations = {
640 .open = lock_stat_open,
641 .write = lock_stat_write,
644 .release = lock_stat_release,
646 #endif /* CONFIG_LOCK_STAT */
648 static int __init lockdep_proc_init(void)
650 proc_create_seq("lockdep", S_IRUSR, NULL, &lockdep_ops);
651 #ifdef CONFIG_PROVE_LOCKING
652 proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops);
654 proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show);
655 #ifdef CONFIG_LOCK_STAT
656 proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
657 &proc_lock_stat_operations);
663 __initcall(lockdep_proc_init);