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/module.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, factor = 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    /*
287     * Estimated factor between direct and indirect
288     * dependencies:
289     */
290    if (nr_list_entries)
291        factor = sum_forward_deps / nr_list_entries;
292
293#ifdef CONFIG_PROVE_LOCKING
294    seq_printf(m, " dependency chains: %11lu [max: %lu]\n",
295            nr_lock_chains, MAX_LOCKDEP_CHAINS);
296    seq_printf(m, " dependency chain hlocks: %11d [max: %lu]\n",
297            nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
298#endif
299
300#ifdef CONFIG_TRACE_IRQFLAGS
301    seq_printf(m, " in-hardirq chains: %11u\n",
302            nr_hardirq_chains);
303    seq_printf(m, " in-softirq chains: %11u\n",
304            nr_softirq_chains);
305#endif
306    seq_printf(m, " in-process chains: %11u\n",
307            nr_process_chains);
308    seq_printf(m, " stack-trace entries: %11lu [max: %lu]\n",
309            nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
310    seq_printf(m, " combined max dependencies: %11u\n",
311            (nr_hardirq_chains + 1) *
312            (nr_softirq_chains + 1) *
313            (nr_process_chains + 1)
314    );
315    seq_printf(m, " hardirq-safe locks: %11lu\n",
316            nr_hardirq_safe);
317    seq_printf(m, " hardirq-unsafe locks: %11lu\n",
318            nr_hardirq_unsafe);
319    seq_printf(m, " softirq-safe locks: %11lu\n",
320            nr_softirq_safe);
321    seq_printf(m, " softirq-unsafe locks: %11lu\n",
322            nr_softirq_unsafe);
323    seq_printf(m, " irq-safe locks: %11lu\n",
324            nr_irq_safe);
325    seq_printf(m, " irq-unsafe locks: %11lu\n",
326            nr_irq_unsafe);
327
328    seq_printf(m, " hardirq-read-safe locks: %11lu\n",
329            nr_hardirq_read_safe);
330    seq_printf(m, " hardirq-read-unsafe locks: %11lu\n",
331            nr_hardirq_read_unsafe);
332    seq_printf(m, " softirq-read-safe locks: %11lu\n",
333            nr_softirq_read_safe);
334    seq_printf(m, " softirq-read-unsafe locks: %11lu\n",
335            nr_softirq_read_unsafe);
336    seq_printf(m, " irq-read-safe locks: %11lu\n",
337            nr_irq_read_safe);
338    seq_printf(m, " irq-read-unsafe locks: %11lu\n",
339            nr_irq_read_unsafe);
340
341    seq_printf(m, " uncategorized locks: %11lu\n",
342            nr_uncategorized);
343    seq_printf(m, " unused locks: %11lu\n",
344            nr_unused);
345    seq_printf(m, " max locking depth: %11u\n",
346            max_lockdep_depth);
347#ifdef CONFIG_PROVE_LOCKING
348    seq_printf(m, " max bfs queue depth: %11u\n",
349            max_bfs_queue_depth);
350#endif
351    lockdep_stats_debug_show(m);
352    seq_printf(m, " debug_locks: %11u\n",
353            debug_locks);
354
355    return 0;
356}
357
358static int lockdep_stats_open(struct inode *inode, struct file *file)
359{
360    return single_open(file, lockdep_stats_show, NULL);
361}
362
363static const struct file_operations proc_lockdep_stats_operations = {
364    .open = lockdep_stats_open,
365    .read = seq_read,
366    .llseek = seq_lseek,
367    .release = single_release,
368};
369
370#ifdef CONFIG_LOCK_STAT
371
372struct lock_stat_data {
373    struct lock_class *class;
374    struct lock_class_stats stats;
375};
376
377struct lock_stat_seq {
378    struct lock_stat_data *iter_end;
379    struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
380};
381
382/*
383 * sort on absolute number of contentions
384 */
385static int lock_stat_cmp(const void *l, const void *r)
386{
387    const struct lock_stat_data *dl = l, *dr = r;
388    unsigned long nl, nr;
389
390    nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
391    nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
392
393    return nr - nl;
394}
395
396static void seq_line(struct seq_file *m, char c, int offset, int length)
397{
398    int i;
399
400    for (i = 0; i < offset; i++)
401        seq_puts(m, " ");
402    for (i = 0; i < length; i++)
403        seq_printf(m, "%c", c);
404    seq_puts(m, "\n");
405}
406
407static void snprint_time(char *buf, size_t bufsiz, s64 nr)
408{
409    s64 div;
410    s32 rem;
411
412    nr += 5; /* for display rounding */
413    div = div_s64_rem(nr, 1000, &rem);
414    snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
415}
416
417static void seq_time(struct seq_file *m, s64 time)
418{
419    char num[15];
420
421    snprint_time(num, sizeof(num), time);
422    seq_printf(m, " %14s", num);
423}
424
425static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
426{
427    seq_printf(m, "%14lu", lt->nr);
428    seq_time(m, lt->min);
429    seq_time(m, lt->max);
430    seq_time(m, lt->total);
431}
432
433static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
434{
435    char name[39];
436    struct lock_class *class;
437    struct lock_class_stats *stats;
438    int i, namelen;
439
440    class = data->class;
441    stats = &data->stats;
442
443    namelen = 38;
444    if (class->name_version > 1)
445        namelen -= 2; /* XXX truncates versions > 9 */
446    if (class->subclass)
447        namelen -= 2;
448
449    if (!class->name) {
450        char str[KSYM_NAME_LEN];
451        const char *key_name;
452
453        key_name = __get_key_name(class->key, str);
454        snprintf(name, namelen, "%s", key_name);
455    } else {
456        snprintf(name, namelen, "%s", class->name);
457    }
458    namelen = strlen(name);
459    if (class->name_version > 1) {
460        snprintf(name+namelen, 3, "#%d", class->name_version);
461        namelen += 2;
462    }
463    if (class->subclass) {
464        snprintf(name+namelen, 3, "/%d", class->subclass);
465        namelen += 2;
466    }
467
468    if (stats->write_holdtime.nr) {
469        if (stats->read_holdtime.nr)
470            seq_printf(m, "%38s-W:", name);
471        else
472            seq_printf(m, "%40s:", name);
473
474        seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
475        seq_lock_time(m, &stats->write_waittime);
476        seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
477        seq_lock_time(m, &stats->write_holdtime);
478        seq_puts(m, "\n");
479    }
480
481    if (stats->read_holdtime.nr) {
482        seq_printf(m, "%38s-R:", name);
483        seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
484        seq_lock_time(m, &stats->read_waittime);
485        seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
486        seq_lock_time(m, &stats->read_holdtime);
487        seq_puts(m, "\n");
488    }
489
490    if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
491        return;
492
493    if (stats->read_holdtime.nr)
494        namelen += 2;
495
496    for (i = 0; i < LOCKSTAT_POINTS; i++) {
497        char sym[KSYM_SYMBOL_LEN];
498        char ip[32];
499
500        if (class->contention_point[i] == 0)
501            break;
502
503        if (!i)
504            seq_line(m, '-', 40-namelen, namelen);
505
506        sprint_symbol(sym, class->contention_point[i]);
507        snprintf(ip, sizeof(ip), "[<%p>]",
508                (void *)class->contention_point[i]);
509        seq_printf(m, "%40s %14lu %29s %s\n", name,
510                stats->contention_point[i],
511                ip, sym);
512    }
513    for (i = 0; i < LOCKSTAT_POINTS; i++) {
514        char sym[KSYM_SYMBOL_LEN];
515        char ip[32];
516
517        if (class->contending_point[i] == 0)
518            break;
519
520        if (!i)
521            seq_line(m, '-', 40-namelen, namelen);
522
523        sprint_symbol(sym, class->contending_point[i]);
524        snprintf(ip, sizeof(ip), "[<%p>]",
525                (void *)class->contending_point[i]);
526        seq_printf(m, "%40s %14lu %29s %s\n", name,
527                stats->contending_point[i],
528                ip, sym);
529    }
530    if (i) {
531        seq_puts(m, "\n");
532        seq_line(m, '.', 0, 40 + 1 + 10 * (14 + 1));
533        seq_puts(m, "\n");
534    }
535}
536
537static void seq_header(struct seq_file *m)
538{
539    seq_printf(m, "lock_stat version 0.3\n");
540
541    if (unlikely(!debug_locks))
542        seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
543
544    seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
545    seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
546            "%14s %14s\n",
547            "class name",
548            "con-bounces",
549            "contentions",
550            "waittime-min",
551            "waittime-max",
552            "waittime-total",
553            "acq-bounces",
554            "acquisitions",
555            "holdtime-min",
556            "holdtime-max",
557            "holdtime-total");
558    seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
559    seq_printf(m, "\n");
560}
561
562static 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
577static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
578{
579    (*pos)++;
580    return ls_start(m, pos);
581}
582
583static void ls_stop(struct seq_file *m, void *v)
584{
585}
586
587static 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
597static const struct seq_operations lockstat_ops = {
598    .start = ls_start,
599    .next = ls_next,
600    .stop = ls_stop,
601    .show = ls_show,
602};
603
604static 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
636static 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
655static 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
663static const struct file_operations proc_lock_stat_operations = {
664    .open = lock_stat_open,
665    .write = lock_stat_write,
666    .read = seq_read,
667    .llseek = seq_lseek,
668    .release = lock_stat_release,
669};
670#endif /* CONFIG_LOCK_STAT */
671
672static int __init lockdep_proc_init(void)
673{
674    proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
675#ifdef CONFIG_PROVE_LOCKING
676    proc_create("lockdep_chains", S_IRUSR, NULL,
677            &proc_lockdep_chains_operations);
678#endif
679    proc_create("lockdep_stats", S_IRUSR, NULL,
680            &proc_lockdep_stats_operations);
681
682#ifdef CONFIG_LOCK_STAT
683    proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
684            &proc_lock_stat_operations);
685#endif
686
687    return 0;
688}
689
690__initcall(lockdep_proc_init);
691
692

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