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 if (IS_ENABLED(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));
77 get_usage_chars(class, usage
);
78 seq_printf(m
, " %s", usage
);
85 if (IS_ENABLED(CONFIG_PROVE_LOCKING
)) {
86 list_for_each_entry(entry
, &class->locks_after
, entry
) {
87 if (entry
->distance
== 1) {
88 seq_printf(m
, " -> [%p] ", entry
->class->key
);
89 print_name(m
, entry
->class);
99 static const struct seq_operations lockdep_ops
= {
106 #ifdef CONFIG_PROVE_LOCKING
107 static void *lc_start(struct seq_file
*m
, loff_t
*pos
)
113 return SEQ_START_TOKEN
;
115 return lock_chains
+ (*pos
- 1);
118 static void *lc_next(struct seq_file
*m
, void *v
, loff_t
*pos
)
120 *pos
= lockdep_next_lockchain(*pos
- 1) + 1;
121 return lc_start(m
, pos
);
124 static void lc_stop(struct seq_file
*m
, void *v
)
128 static int lc_show(struct seq_file
*m
, void *v
)
130 struct lock_chain
*chain
= v
;
131 struct lock_class
*class;
133 static const char * const irq_strs
[] = {
135 [LOCK_CHAIN_HARDIRQ_CONTEXT
] = "hardirq",
136 [LOCK_CHAIN_SOFTIRQ_CONTEXT
] = "softirq",
137 [LOCK_CHAIN_SOFTIRQ_CONTEXT
|
138 LOCK_CHAIN_HARDIRQ_CONTEXT
] = "hardirq|softirq",
141 if (v
== SEQ_START_TOKEN
) {
142 if (!nr_free_chain_hlocks
)
143 seq_printf(m
, "(buggered) ");
144 seq_printf(m
, "all lock chains:\n");
148 seq_printf(m
, "irq_context: %s\n", irq_strs
[chain
->irq_context
]);
150 for (i
= 0; i
< chain
->depth
; i
++) {
151 class = lock_chain_get_class(chain
, i
);
155 seq_printf(m
, "[%p] ", class->key
);
156 print_name(m
, class);
164 static const struct seq_operations lockdep_chains_ops
= {
170 #endif /* CONFIG_PROVE_LOCKING */
172 static void lockdep_stats_debug_show(struct seq_file
*m
)
174 #ifdef CONFIG_DEBUG_LOCKDEP
175 unsigned long long hi1
= debug_atomic_read(hardirqs_on_events
),
176 hi2
= debug_atomic_read(hardirqs_off_events
),
177 hr1
= debug_atomic_read(redundant_hardirqs_on
),
178 hr2
= debug_atomic_read(redundant_hardirqs_off
),
179 si1
= debug_atomic_read(softirqs_on_events
),
180 si2
= debug_atomic_read(softirqs_off_events
),
181 sr1
= debug_atomic_read(redundant_softirqs_on
),
182 sr2
= debug_atomic_read(redundant_softirqs_off
);
184 seq_printf(m
, " chain lookup misses: %11llu\n",
185 debug_atomic_read(chain_lookup_misses
));
186 seq_printf(m
, " chain lookup hits: %11llu\n",
187 debug_atomic_read(chain_lookup_hits
));
188 seq_printf(m
, " cyclic checks: %11llu\n",
189 debug_atomic_read(nr_cyclic_checks
));
190 seq_printf(m
, " redundant checks: %11llu\n",
191 debug_atomic_read(nr_redundant_checks
));
192 seq_printf(m
, " redundant links: %11llu\n",
193 debug_atomic_read(nr_redundant
));
194 seq_printf(m
, " find-mask forwards checks: %11llu\n",
195 debug_atomic_read(nr_find_usage_forwards_checks
));
196 seq_printf(m
, " find-mask backwards checks: %11llu\n",
197 debug_atomic_read(nr_find_usage_backwards_checks
));
199 seq_printf(m
, " hardirq on events: %11llu\n", hi1
);
200 seq_printf(m
, " hardirq off events: %11llu\n", hi2
);
201 seq_printf(m
, " redundant hardirq ons: %11llu\n", hr1
);
202 seq_printf(m
, " redundant hardirq offs: %11llu\n", hr2
);
203 seq_printf(m
, " softirq on events: %11llu\n", si1
);
204 seq_printf(m
, " softirq off events: %11llu\n", si2
);
205 seq_printf(m
, " redundant softirq ons: %11llu\n", sr1
);
206 seq_printf(m
, " redundant softirq offs: %11llu\n", sr2
);
210 static int lockdep_stats_show(struct seq_file
*m
, void *v
)
212 unsigned long nr_unused
= 0, nr_uncategorized
= 0,
213 nr_irq_safe
= 0, nr_irq_unsafe
= 0,
214 nr_softirq_safe
= 0, nr_softirq_unsafe
= 0,
215 nr_hardirq_safe
= 0, nr_hardirq_unsafe
= 0,
216 nr_irq_read_safe
= 0, nr_irq_read_unsafe
= 0,
217 nr_softirq_read_safe
= 0, nr_softirq_read_unsafe
= 0,
218 nr_hardirq_read_safe
= 0, nr_hardirq_read_unsafe
= 0,
219 sum_forward_deps
= 0;
221 #ifdef CONFIG_PROVE_LOCKING
222 struct lock_class
*class;
224 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
226 if (class->usage_mask
== 0)
228 if (class->usage_mask
== LOCKF_USED
)
230 if (class->usage_mask
& LOCKF_USED_IN_IRQ
)
232 if (class->usage_mask
& LOCKF_ENABLED_IRQ
)
234 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
236 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQ
)
238 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
240 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQ
)
242 if (class->usage_mask
& LOCKF_USED_IN_IRQ_READ
)
244 if (class->usage_mask
& LOCKF_ENABLED_IRQ_READ
)
245 nr_irq_read_unsafe
++;
246 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
)
247 nr_softirq_read_safe
++;
248 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQ_READ
)
249 nr_softirq_read_unsafe
++;
250 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
)
251 nr_hardirq_read_safe
++;
252 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQ_READ
)
253 nr_hardirq_read_unsafe
++;
255 sum_forward_deps
+= lockdep_count_forward_deps(class);
257 #ifdef CONFIG_DEBUG_LOCKDEP
258 DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks
) != nr_unused
);
262 seq_printf(m
, " lock-classes: %11lu [max: %lu]\n",
263 nr_lock_classes
, MAX_LOCKDEP_KEYS
);
264 seq_printf(m
, " direct dependencies: %11lu [max: %lu]\n",
265 nr_list_entries
, MAX_LOCKDEP_ENTRIES
);
266 seq_printf(m
, " indirect dependencies: %11lu\n",
270 * Total number of dependencies:
272 * All irq-safe locks may nest inside irq-unsafe locks,
273 * plus all the other known dependencies:
275 seq_printf(m
, " all direct dependencies: %11lu\n",
276 nr_irq_unsafe
* nr_irq_safe
+
277 nr_hardirq_unsafe
* nr_hardirq_safe
+
280 #ifdef CONFIG_PROVE_LOCKING
281 seq_printf(m
, " dependency chains: %11lu [max: %lu]\n",
282 lock_chain_count(), MAX_LOCKDEP_CHAINS
);
283 seq_printf(m
, " dependency chain hlocks used: %11lu [max: %lu]\n",
284 MAX_LOCKDEP_CHAIN_HLOCKS
-
285 (nr_free_chain_hlocks
+ nr_lost_chain_hlocks
),
286 MAX_LOCKDEP_CHAIN_HLOCKS
);
287 seq_printf(m
, " dependency chain hlocks lost: %11u\n",
288 nr_lost_chain_hlocks
);
291 #ifdef CONFIG_TRACE_IRQFLAGS
292 seq_printf(m
, " in-hardirq chains: %11u\n",
294 seq_printf(m
, " in-softirq chains: %11u\n",
297 seq_printf(m
, " in-process chains: %11u\n",
299 seq_printf(m
, " stack-trace entries: %11lu [max: %lu]\n",
300 nr_stack_trace_entries
, MAX_STACK_TRACE_ENTRIES
);
301 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
302 seq_printf(m
, " number of stack traces: %11llu\n",
303 lockdep_stack_trace_count());
304 seq_printf(m
, " number of stack hash chains: %11llu\n",
305 lockdep_stack_hash_count());
307 seq_printf(m
, " combined max dependencies: %11u\n",
308 (nr_hardirq_chains
+ 1) *
309 (nr_softirq_chains
+ 1) *
310 (nr_process_chains
+ 1)
312 seq_printf(m
, " hardirq-safe locks: %11lu\n",
314 seq_printf(m
, " hardirq-unsafe locks: %11lu\n",
316 seq_printf(m
, " softirq-safe locks: %11lu\n",
318 seq_printf(m
, " softirq-unsafe locks: %11lu\n",
320 seq_printf(m
, " irq-safe locks: %11lu\n",
322 seq_printf(m
, " irq-unsafe locks: %11lu\n",
325 seq_printf(m
, " hardirq-read-safe locks: %11lu\n",
326 nr_hardirq_read_safe
);
327 seq_printf(m
, " hardirq-read-unsafe locks: %11lu\n",
328 nr_hardirq_read_unsafe
);
329 seq_printf(m
, " softirq-read-safe locks: %11lu\n",
330 nr_softirq_read_safe
);
331 seq_printf(m
, " softirq-read-unsafe locks: %11lu\n",
332 nr_softirq_read_unsafe
);
333 seq_printf(m
, " irq-read-safe locks: %11lu\n",
335 seq_printf(m
, " irq-read-unsafe locks: %11lu\n",
338 seq_printf(m
, " uncategorized locks: %11lu\n",
340 seq_printf(m
, " unused locks: %11lu\n",
342 seq_printf(m
, " max locking depth: %11u\n",
344 #ifdef CONFIG_PROVE_LOCKING
345 seq_printf(m
, " max bfs queue depth: %11u\n",
346 max_bfs_queue_depth
);
348 lockdep_stats_debug_show(m
);
349 seq_printf(m
, " debug_locks: %11u\n",
353 * Zapped classes and lockdep data buffers reuse statistics.
356 seq_printf(m
, " zapped classes: %11lu\n",
358 #ifdef CONFIG_PROVE_LOCKING
359 seq_printf(m
, " zapped lock chains: %11lu\n",
360 nr_zapped_lock_chains
);
361 seq_printf(m
, " large chain blocks: %11u\n",
362 nr_large_chain_blocks
);
367 #ifdef CONFIG_LOCK_STAT
369 struct lock_stat_data
{
370 struct lock_class
*class;
371 struct lock_class_stats stats
;
374 struct lock_stat_seq
{
375 struct lock_stat_data
*iter_end
;
376 struct lock_stat_data stats
[MAX_LOCKDEP_KEYS
];
380 * sort on absolute number of contentions
382 static int lock_stat_cmp(const void *l
, const void *r
)
384 const struct lock_stat_data
*dl
= l
, *dr
= r
;
385 unsigned long nl
, nr
;
387 nl
= dl
->stats
.read_waittime
.nr
+ dl
->stats
.write_waittime
.nr
;
388 nr
= dr
->stats
.read_waittime
.nr
+ dr
->stats
.write_waittime
.nr
;
393 static void seq_line(struct seq_file
*m
, char c
, int offset
, int length
)
397 for (i
= 0; i
< offset
; i
++)
399 for (i
= 0; i
< length
; i
++)
400 seq_printf(m
, "%c", c
);
404 static void snprint_time(char *buf
, size_t bufsiz
, s64 nr
)
409 nr
+= 5; /* for display rounding */
410 div
= div_s64_rem(nr
, 1000, &rem
);
411 snprintf(buf
, bufsiz
, "%lld.%02d", (long long)div
, (int)rem
/10);
414 static void seq_time(struct seq_file
*m
, s64 time
)
418 snprint_time(num
, sizeof(num
), time
);
419 seq_printf(m
, " %14s", num
);
422 static void seq_lock_time(struct seq_file
*m
, struct lock_time
*lt
)
424 seq_printf(m
, "%14lu", lt
->nr
);
425 seq_time(m
, lt
->min
);
426 seq_time(m
, lt
->max
);
427 seq_time(m
, lt
->total
);
428 seq_time(m
, lt
->nr
? div64_u64(lt
->total
, lt
->nr
) : 0);
431 static void seq_stats(struct seq_file
*m
, struct lock_stat_data
*data
)
433 const struct lockdep_subclass_key
*ckey
;
434 struct lock_class_stats
*stats
;
435 struct lock_class
*class;
441 stats
= &data
->stats
;
444 if (class->name_version
> 1)
445 namelen
-= 2; /* XXX truncates versions > 9 */
449 rcu_read_lock_sched();
450 cname
= rcu_dereference_sched(class->name
);
451 ckey
= rcu_dereference_sched(class->key
);
453 if (!cname
&& !ckey
) {
454 rcu_read_unlock_sched();
458 char str
[KSYM_NAME_LEN
];
459 const char *key_name
;
461 key_name
= __get_key_name(ckey
, str
);
462 snprintf(name
, namelen
, "%s", key_name
);
464 snprintf(name
, namelen
, "%s", cname
);
466 rcu_read_unlock_sched();
468 namelen
= strlen(name
);
469 if (class->name_version
> 1) {
470 snprintf(name
+namelen
, 3, "#%d", class->name_version
);
473 if (class->subclass
) {
474 snprintf(name
+namelen
, 3, "/%d", class->subclass
);
478 if (stats
->write_holdtime
.nr
) {
479 if (stats
->read_holdtime
.nr
)
480 seq_printf(m
, "%38s-W:", name
);
482 seq_printf(m
, "%40s:", name
);
484 seq_printf(m
, "%14lu ", stats
->bounces
[bounce_contended_write
]);
485 seq_lock_time(m
, &stats
->write_waittime
);
486 seq_printf(m
, " %14lu ", stats
->bounces
[bounce_acquired_write
]);
487 seq_lock_time(m
, &stats
->write_holdtime
);
491 if (stats
->read_holdtime
.nr
) {
492 seq_printf(m
, "%38s-R:", name
);
493 seq_printf(m
, "%14lu ", stats
->bounces
[bounce_contended_read
]);
494 seq_lock_time(m
, &stats
->read_waittime
);
495 seq_printf(m
, " %14lu ", stats
->bounces
[bounce_acquired_read
]);
496 seq_lock_time(m
, &stats
->read_holdtime
);
500 if (stats
->read_waittime
.nr
+ stats
->write_waittime
.nr
== 0)
503 if (stats
->read_holdtime
.nr
)
506 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
509 if (class->contention_point
[i
] == 0)
513 seq_line(m
, '-', 40-namelen
, namelen
);
515 snprintf(ip
, sizeof(ip
), "[<%p>]",
516 (void *)class->contention_point
[i
]);
517 seq_printf(m
, "%40s %14lu %29s %pS\n",
518 name
, stats
->contention_point
[i
],
519 ip
, (void *)class->contention_point
[i
]);
521 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
524 if (class->contending_point
[i
] == 0)
528 seq_line(m
, '-', 40-namelen
, namelen
);
530 snprintf(ip
, sizeof(ip
), "[<%p>]",
531 (void *)class->contending_point
[i
]);
532 seq_printf(m
, "%40s %14lu %29s %pS\n",
533 name
, stats
->contending_point
[i
],
534 ip
, (void *)class->contending_point
[i
]);
538 seq_line(m
, '.', 0, 40 + 1 + 12 * (14 + 1));
543 static void seq_header(struct seq_file
*m
)
545 seq_puts(m
, "lock_stat version 0.4\n");
547 if (unlikely(!debug_locks
))
548 seq_printf(m
, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
550 seq_line(m
, '-', 0, 40 + 1 + 12 * (14 + 1));
551 seq_printf(m
, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
566 seq_line(m
, '-', 0, 40 + 1 + 12 * (14 + 1));
570 static void *ls_start(struct seq_file
*m
, loff_t
*pos
)
572 struct lock_stat_seq
*data
= m
->private;
573 struct lock_stat_data
*iter
;
576 return SEQ_START_TOKEN
;
578 iter
= data
->stats
+ (*pos
- 1);
579 if (iter
>= data
->iter_end
)
585 static void *ls_next(struct seq_file
*m
, void *v
, loff_t
*pos
)
588 return ls_start(m
, pos
);
591 static void ls_stop(struct seq_file
*m
, void *v
)
595 static int ls_show(struct seq_file
*m
, void *v
)
597 if (v
== SEQ_START_TOKEN
)
605 static const struct seq_operations lockstat_ops
= {
612 static int lock_stat_open(struct inode
*inode
, struct file
*file
)
615 struct lock_class
*class;
616 struct lock_stat_seq
*data
= vmalloc(sizeof(struct lock_stat_seq
));
621 res
= seq_open(file
, &lockstat_ops
);
623 struct lock_stat_data
*iter
= data
->stats
;
624 struct seq_file
*m
= file
->private_data
;
626 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
628 iter
->stats
= lock_stats(class);
631 data
->iter_end
= iter
;
633 sort(data
->stats
, data
->iter_end
- data
->stats
,
634 sizeof(struct lock_stat_data
),
635 lock_stat_cmp
, NULL
);
644 static ssize_t
lock_stat_write(struct file
*file
, const char __user
*buf
,
645 size_t count
, loff_t
*ppos
)
647 struct lock_class
*class;
651 if (get_user(c
, buf
))
657 list_for_each_entry(class, &all_lock_classes
, lock_entry
)
658 clear_lock_stats(class);
663 static int lock_stat_release(struct inode
*inode
, struct file
*file
)
665 struct seq_file
*seq
= file
->private_data
;
668 return seq_release(inode
, file
);
671 static const struct proc_ops lock_stat_proc_ops
= {
672 .proc_open
= lock_stat_open
,
673 .proc_write
= lock_stat_write
,
674 .proc_read
= seq_read
,
675 .proc_lseek
= seq_lseek
,
676 .proc_release
= lock_stat_release
,
678 #endif /* CONFIG_LOCK_STAT */
680 static int __init
lockdep_proc_init(void)
682 proc_create_seq("lockdep", S_IRUSR
, NULL
, &lockdep_ops
);
683 #ifdef CONFIG_PROVE_LOCKING
684 proc_create_seq("lockdep_chains", S_IRUSR
, NULL
, &lockdep_chains_ops
);
686 proc_create_single("lockdep_stats", S_IRUSR
, NULL
, lockdep_stats_show
);
687 #ifdef CONFIG_LOCK_STAT
688 proc_create("lock_stat", S_IRUSR
| S_IWUSR
, NULL
, &lock_stat_proc_ops
);
694 __initcall(lockdep_proc_init
);