Root/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/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
26static 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
31static void *l_start(struct seq_file *m, loff_t *pos)
32{
33    return seq_list_start_head(&all_lock_classes, *pos);
34}
35
36static void l_stop(struct seq_file *m, void *v)
37{
38}
39
40static 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
57static 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
96static const struct seq_operations lockdep_ops = {
97    .start = l_start,
98    .next = l_next,
99    .stop = l_stop,
100    .show = l_show,
101};
102
103static int lockdep_open(struct inode *inode, struct file *file)
104{
105    return seq_open(file, &lockdep_ops);
106}
107
108static 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
116static 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
127static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
128{
129    (*pos)++;
130    return lc_start(m, pos);
131}
132
133static void lc_stop(struct seq_file *m, void *v)
134{
135}
136
137static 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
164static 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
171static int lockdep_chains_open(struct inode *inode, struct file *file)
172{
173    return seq_open(file, &lockdep_chains_ops);
174}
175
176static 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
184static 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
218static 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
351static int lockdep_stats_open(struct inode *inode, struct file *file)
352{
353    return single_open(file, lockdep_stats_show, NULL);
354}
355
356static 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
365struct lock_stat_data {
366    struct lock_class *class;
367    struct lock_class_stats stats;
368};
369
370struct 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 */
378static 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
389static 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
400static 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
410static 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
418static 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
426static 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
526static 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
551static 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
566static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
567{
568    (*pos)++;
569    return ls_start(m, pos);
570}
571
572static void ls_stop(struct seq_file *m, void *v)
573{
574}
575
576static 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
586static const struct seq_operations lockstat_ops = {
587    .start = ls_start,
588    .next = ls_next,
589    .stop = ls_stop,
590    .show = ls_show,
591};
592
593static 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
625static 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
644static 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
652static 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
661static 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
681

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