Root/kernel/lockdep.c

1/*
2 * kernel/lockdep.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 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
13 *
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
17 *
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
20 *
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
24 *
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
27 */
28#define DISABLE_BRANCH_PROFILING
29#include <linux/mutex.h>
30#include <linux/sched.h>
31#include <linux/delay.h>
32#include <linux/module.h>
33#include <linux/proc_fs.h>
34#include <linux/seq_file.h>
35#include <linux/spinlock.h>
36#include <linux/kallsyms.h>
37#include <linux/interrupt.h>
38#include <linux/stacktrace.h>
39#include <linux/debug_locks.h>
40#include <linux/irqflags.h>
41#include <linux/utsname.h>
42#include <linux/hash.h>
43#include <linux/ftrace.h>
44#include <linux/stringify.h>
45#include <linux/bitops.h>
46#include <linux/gfp.h>
47
48#include <asm/sections.h>
49
50#include "lockdep_internals.h"
51
52#define CREATE_TRACE_POINTS
53#include <trace/events/lock.h>
54
55#ifdef CONFIG_PROVE_LOCKING
56int prove_locking = 1;
57module_param(prove_locking, int, 0644);
58#else
59#define prove_locking 0
60#endif
61
62#ifdef CONFIG_LOCK_STAT
63int lock_stat = 1;
64module_param(lock_stat, int, 0644);
65#else
66#define lock_stat 0
67#endif
68
69/*
70 * lockdep_lock: protects the lockdep graph, the hashes and the
71 * class/list/hash allocators.
72 *
73 * This is one of the rare exceptions where it's justified
74 * to use a raw spinlock - we really dont want the spinlock
75 * code to recurse back into the lockdep code...
76 */
77static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
78
79static int graph_lock(void)
80{
81    arch_spin_lock(&lockdep_lock);
82    /*
83     * Make sure that if another CPU detected a bug while
84     * walking the graph we dont change it (while the other
85     * CPU is busy printing out stuff with the graph lock
86     * dropped already)
87     */
88    if (!debug_locks) {
89        arch_spin_unlock(&lockdep_lock);
90        return 0;
91    }
92    /* prevent any recursions within lockdep from causing deadlocks */
93    current->lockdep_recursion++;
94    return 1;
95}
96
97static inline int graph_unlock(void)
98{
99    if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
100        return DEBUG_LOCKS_WARN_ON(1);
101
102    current->lockdep_recursion--;
103    arch_spin_unlock(&lockdep_lock);
104    return 0;
105}
106
107/*
108 * Turn lock debugging off and return with 0 if it was off already,
109 * and also release the graph lock:
110 */
111static inline int debug_locks_off_graph_unlock(void)
112{
113    int ret = debug_locks_off();
114
115    arch_spin_unlock(&lockdep_lock);
116
117    return ret;
118}
119
120static int lockdep_initialized;
121
122unsigned long nr_list_entries;
123static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
124
125/*
126 * All data structures here are protected by the global debug_lock.
127 *
128 * Mutex key structs only get allocated, once during bootup, and never
129 * get freed - this significantly simplifies the debugging code.
130 */
131unsigned long nr_lock_classes;
132static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133
134static inline struct lock_class *hlock_class(struct held_lock *hlock)
135{
136    if (!hlock->class_idx) {
137        DEBUG_LOCKS_WARN_ON(1);
138        return NULL;
139    }
140    return lock_classes + hlock->class_idx - 1;
141}
142
143#ifdef CONFIG_LOCK_STAT
144static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
145              cpu_lock_stats);
146
147static inline u64 lockstat_clock(void)
148{
149    return local_clock();
150}
151
152static int lock_point(unsigned long points[], unsigned long ip)
153{
154    int i;
155
156    for (i = 0; i < LOCKSTAT_POINTS; i++) {
157        if (points[i] == 0) {
158            points[i] = ip;
159            break;
160        }
161        if (points[i] == ip)
162            break;
163    }
164
165    return i;
166}
167
168static void lock_time_inc(struct lock_time *lt, u64 time)
169{
170    if (time > lt->max)
171        lt->max = time;
172
173    if (time < lt->min || !lt->nr)
174        lt->min = time;
175
176    lt->total += time;
177    lt->nr++;
178}
179
180static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
181{
182    if (!src->nr)
183        return;
184
185    if (src->max > dst->max)
186        dst->max = src->max;
187
188    if (src->min < dst->min || !dst->nr)
189        dst->min = src->min;
190
191    dst->total += src->total;
192    dst->nr += src->nr;
193}
194
195struct lock_class_stats lock_stats(struct lock_class *class)
196{
197    struct lock_class_stats stats;
198    int cpu, i;
199
200    memset(&stats, 0, sizeof(struct lock_class_stats));
201    for_each_possible_cpu(cpu) {
202        struct lock_class_stats *pcs =
203            &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
204
205        for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
206            stats.contention_point[i] += pcs->contention_point[i];
207
208        for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
209            stats.contending_point[i] += pcs->contending_point[i];
210
211        lock_time_add(&pcs->read_waittime, &stats.read_waittime);
212        lock_time_add(&pcs->write_waittime, &stats.write_waittime);
213
214        lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
215        lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
216
217        for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
218            stats.bounces[i] += pcs->bounces[i];
219    }
220
221    return stats;
222}
223
224void clear_lock_stats(struct lock_class *class)
225{
226    int cpu;
227
228    for_each_possible_cpu(cpu) {
229        struct lock_class_stats *cpu_stats =
230            &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
231
232        memset(cpu_stats, 0, sizeof(struct lock_class_stats));
233    }
234    memset(class->contention_point, 0, sizeof(class->contention_point));
235    memset(class->contending_point, 0, sizeof(class->contending_point));
236}
237
238static struct lock_class_stats *get_lock_stats(struct lock_class *class)
239{
240    return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
241}
242
243static void put_lock_stats(struct lock_class_stats *stats)
244{
245    put_cpu_var(cpu_lock_stats);
246}
247
248static void lock_release_holdtime(struct held_lock *hlock)
249{
250    struct lock_class_stats *stats;
251    u64 holdtime;
252
253    if (!lock_stat)
254        return;
255
256    holdtime = lockstat_clock() - hlock->holdtime_stamp;
257
258    stats = get_lock_stats(hlock_class(hlock));
259    if (hlock->read)
260        lock_time_inc(&stats->read_holdtime, holdtime);
261    else
262        lock_time_inc(&stats->write_holdtime, holdtime);
263    put_lock_stats(stats);
264}
265#else
266static inline void lock_release_holdtime(struct held_lock *hlock)
267{
268}
269#endif
270
271/*
272 * We keep a global list of all lock classes. The list only grows,
273 * never shrinks. The list is only accessed with the lockdep
274 * spinlock lock held.
275 */
276LIST_HEAD(all_lock_classes);
277
278/*
279 * The lockdep classes are in a hash-table as well, for fast lookup:
280 */
281#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
282#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
283#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
284#define classhashentry(key) (classhash_table + __classhashfn((key)))
285
286static struct list_head classhash_table[CLASSHASH_SIZE];
287
288/*
289 * We put the lock dependency chains into a hash-table as well, to cache
290 * their existence:
291 */
292#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
293#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
294#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
295#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
296
297static struct list_head chainhash_table[CHAINHASH_SIZE];
298
299/*
300 * The hash key of the lock dependency chains is a hash itself too:
301 * it's a hash of all locks taken up to that lock, including that lock.
302 * It's a 64-bit hash, because it's important for the keys to be
303 * unique.
304 */
305#define iterate_chain_key(key1, key2) \
306    (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
307    ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
308    (key2))
309
310void lockdep_off(void)
311{
312    current->lockdep_recursion++;
313}
314EXPORT_SYMBOL(lockdep_off);
315
316void lockdep_on(void)
317{
318    current->lockdep_recursion--;
319}
320EXPORT_SYMBOL(lockdep_on);
321
322/*
323 * Debugging switches:
324 */
325
326#define VERBOSE 0
327#define VERY_VERBOSE 0
328
329#if VERBOSE
330# define HARDIRQ_VERBOSE 1
331# define SOFTIRQ_VERBOSE 1
332# define RECLAIM_VERBOSE 1
333#else
334# define HARDIRQ_VERBOSE 0
335# define SOFTIRQ_VERBOSE 0
336# define RECLAIM_VERBOSE 0
337#endif
338
339#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
340/*
341 * Quick filtering for interesting events:
342 */
343static int class_filter(struct lock_class *class)
344{
345#if 0
346    /* Example */
347    if (class->name_version == 1 &&
348            !strcmp(class->name, "lockname"))
349        return 1;
350    if (class->name_version == 1 &&
351            !strcmp(class->name, "&struct->lockfield"))
352        return 1;
353#endif
354    /* Filter everything else. 1 would be to allow everything else */
355    return 0;
356}
357#endif
358
359static int verbose(struct lock_class *class)
360{
361#if VERBOSE
362    return class_filter(class);
363#endif
364    return 0;
365}
366
367/*
368 * Stack-trace: tightly packed array of stack backtrace
369 * addresses. Protected by the graph_lock.
370 */
371unsigned long nr_stack_trace_entries;
372static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
373
374static int save_trace(struct stack_trace *trace)
375{
376    trace->nr_entries = 0;
377    trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
378    trace->entries = stack_trace + nr_stack_trace_entries;
379
380    trace->skip = 3;
381
382    save_stack_trace(trace);
383
384    /*
385     * Some daft arches put -1 at the end to indicate its a full trace.
386     *
387     * <rant> this is buggy anyway, since it takes a whole extra entry so a
388     * complete trace that maxes out the entries provided will be reported
389     * as incomplete, friggin useless </rant>
390     */
391    if (trace->nr_entries != 0 &&
392        trace->entries[trace->nr_entries-1] == ULONG_MAX)
393        trace->nr_entries--;
394
395    trace->max_entries = trace->nr_entries;
396
397    nr_stack_trace_entries += trace->nr_entries;
398
399    if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
400        if (!debug_locks_off_graph_unlock())
401            return 0;
402
403        printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
404        printk("turning off the locking correctness validator.\n");
405        dump_stack();
406
407        return 0;
408    }
409
410    return 1;
411}
412
413unsigned int nr_hardirq_chains;
414unsigned int nr_softirq_chains;
415unsigned int nr_process_chains;
416unsigned int max_lockdep_depth;
417
418#ifdef CONFIG_DEBUG_LOCKDEP
419/*
420 * We cannot printk in early bootup code. Not even early_printk()
421 * might work. So we mark any initialization errors and printk
422 * about it later on, in lockdep_info().
423 */
424static int lockdep_init_error;
425static unsigned long lockdep_init_trace_data[20];
426static struct stack_trace lockdep_init_trace = {
427    .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
428    .entries = lockdep_init_trace_data,
429};
430
431/*
432 * Various lockdep statistics:
433 */
434DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
435#endif
436
437/*
438 * Locking printouts:
439 */
440
441#define __USAGE(__STATE) \
442    [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
443    [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
444    [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
445    [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
446
447static const char *usage_str[] =
448{
449#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
450#include "lockdep_states.h"
451#undef LOCKDEP_STATE
452    [LOCK_USED] = "INITIAL USE",
453};
454
455const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
456{
457    return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
458}
459
460static inline unsigned long lock_flag(enum lock_usage_bit bit)
461{
462    return 1UL << bit;
463}
464
465static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
466{
467    char c = '.';
468
469    if (class->usage_mask & lock_flag(bit + 2))
470        c = '+';
471    if (class->usage_mask & lock_flag(bit)) {
472        c = '-';
473        if (class->usage_mask & lock_flag(bit + 2))
474            c = '?';
475    }
476
477    return c;
478}
479
480void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
481{
482    int i = 0;
483
484#define LOCKDEP_STATE(__STATE) \
485    usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
486    usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
487#include "lockdep_states.h"
488#undef LOCKDEP_STATE
489
490    usage[i] = '\0';
491}
492
493static int __print_lock_name(struct lock_class *class)
494{
495    char str[KSYM_NAME_LEN];
496    const char *name;
497
498    name = class->name;
499    if (!name)
500        name = __get_key_name(class->key, str);
501
502    return printk("%s", name);
503}
504
505static void print_lock_name(struct lock_class *class)
506{
507    char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
508    const char *name;
509
510    get_usage_chars(class, usage);
511
512    name = class->name;
513    if (!name) {
514        name = __get_key_name(class->key, str);
515        printk(" (%s", name);
516    } else {
517        printk(" (%s", name);
518        if (class->name_version > 1)
519            printk("#%d", class->name_version);
520        if (class->subclass)
521            printk("/%d", class->subclass);
522    }
523    printk("){%s}", usage);
524}
525
526static void print_lockdep_cache(struct lockdep_map *lock)
527{
528    const char *name;
529    char str[KSYM_NAME_LEN];
530
531    name = lock->name;
532    if (!name)
533        name = __get_key_name(lock->key->subkeys, str);
534
535    printk("%s", name);
536}
537
538static void print_lock(struct held_lock *hlock)
539{
540    print_lock_name(hlock_class(hlock));
541    printk(", at: ");
542    print_ip_sym(hlock->acquire_ip);
543}
544
545static void lockdep_print_held_locks(struct task_struct *curr)
546{
547    int i, depth = curr->lockdep_depth;
548
549    if (!depth) {
550        printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
551        return;
552    }
553    printk("%d lock%s held by %s/%d:\n",
554        depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
555
556    for (i = 0; i < depth; i++) {
557        printk(" #%d: ", i);
558        print_lock(curr->held_locks + i);
559    }
560}
561
562static void print_kernel_version(void)
563{
564    printk("%s %.*s\n", init_utsname()->release,
565        (int)strcspn(init_utsname()->version, " "),
566        init_utsname()->version);
567}
568
569static int very_verbose(struct lock_class *class)
570{
571#if VERY_VERBOSE
572    return class_filter(class);
573#endif
574    return 0;
575}
576
577/*
578 * Is this the address of a static object:
579 */
580static int static_obj(void *obj)
581{
582    unsigned long start = (unsigned long) &_stext,
583              end = (unsigned long) &_end,
584              addr = (unsigned long) obj;
585
586    /*
587     * static variable?
588     */
589    if ((addr >= start) && (addr < end))
590        return 1;
591
592    if (arch_is_kernel_data(addr))
593        return 1;
594
595    /*
596     * in-kernel percpu var?
597     */
598    if (is_kernel_percpu_address(addr))
599        return 1;
600
601    /*
602     * module static or percpu var?
603     */
604    return is_module_address(addr) || is_module_percpu_address(addr);
605}
606
607/*
608 * To make lock name printouts unique, we calculate a unique
609 * class->name_version generation counter:
610 */
611static int count_matching_names(struct lock_class *new_class)
612{
613    struct lock_class *class;
614    int count = 0;
615
616    if (!new_class->name)
617        return 0;
618
619    list_for_each_entry(class, &all_lock_classes, lock_entry) {
620        if (new_class->key - new_class->subclass == class->key)
621            return class->name_version;
622        if (class->name && !strcmp(class->name, new_class->name))
623            count = max(count, class->name_version);
624    }
625
626    return count + 1;
627}
628
629/*
630 * Register a lock's class in the hash-table, if the class is not present
631 * yet. Otherwise we look it up. We cache the result in the lock object
632 * itself, so actual lookup of the hash should be once per lock object.
633 */
634static inline struct lock_class *
635look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
636{
637    struct lockdep_subclass_key *key;
638    struct list_head *hash_head;
639    struct lock_class *class;
640
641#ifdef CONFIG_DEBUG_LOCKDEP
642    /*
643     * If the architecture calls into lockdep before initializing
644     * the hashes then we'll warn about it later. (we cannot printk
645     * right now)
646     */
647    if (unlikely(!lockdep_initialized)) {
648        lockdep_init();
649        lockdep_init_error = 1;
650        save_stack_trace(&lockdep_init_trace);
651    }
652#endif
653
654    if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
655        debug_locks_off();
656        printk(KERN_ERR
657            "BUG: looking up invalid subclass: %u\n", subclass);
658        printk(KERN_ERR
659            "turning off the locking correctness validator.\n");
660        dump_stack();
661        return NULL;
662    }
663
664    /*
665     * Static locks do not have their class-keys yet - for them the key
666     * is the lock object itself:
667     */
668    if (unlikely(!lock->key))
669        lock->key = (void *)lock;
670
671    /*
672     * NOTE: the class-key must be unique. For dynamic locks, a static
673     * lock_class_key variable is passed in through the mutex_init()
674     * (or spin_lock_init()) call - which acts as the key. For static
675     * locks we use the lock object itself as the key.
676     */
677    BUILD_BUG_ON(sizeof(struct lock_class_key) >
678            sizeof(struct lockdep_map));
679
680    key = lock->key->subkeys + subclass;
681
682    hash_head = classhashentry(key);
683
684    /*
685     * We can walk the hash lockfree, because the hash only
686     * grows, and we are careful when adding entries to the end:
687     */
688    list_for_each_entry(class, hash_head, hash_entry) {
689        if (class->key == key) {
690            WARN_ON_ONCE(class->name != lock->name);
691            return class;
692        }
693    }
694
695    return NULL;
696}
697
698/*
699 * Register a lock's class in the hash-table, if the class is not present
700 * yet. Otherwise we look it up. We cache the result in the lock object
701 * itself, so actual lookup of the hash should be once per lock object.
702 */
703static inline struct lock_class *
704register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
705{
706    struct lockdep_subclass_key *key;
707    struct list_head *hash_head;
708    struct lock_class *class;
709    unsigned long flags;
710
711    class = look_up_lock_class(lock, subclass);
712    if (likely(class))
713        return class;
714
715    /*
716     * Debug-check: all keys must be persistent!
717      */
718    if (!static_obj(lock->key)) {
719        debug_locks_off();
720        printk("INFO: trying to register non-static key.\n");
721        printk("the code is fine but needs lockdep annotation.\n");
722        printk("turning off the locking correctness validator.\n");
723        dump_stack();
724
725        return NULL;
726    }
727
728    key = lock->key->subkeys + subclass;
729    hash_head = classhashentry(key);
730
731    raw_local_irq_save(flags);
732    if (!graph_lock()) {
733        raw_local_irq_restore(flags);
734        return NULL;
735    }
736    /*
737     * We have to do the hash-walk again, to avoid races
738     * with another CPU:
739     */
740    list_for_each_entry(class, hash_head, hash_entry)
741        if (class->key == key)
742            goto out_unlock_set;
743    /*
744     * Allocate a new key from the static array, and add it to
745     * the hash:
746     */
747    if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
748        if (!debug_locks_off_graph_unlock()) {
749            raw_local_irq_restore(flags);
750            return NULL;
751        }
752        raw_local_irq_restore(flags);
753
754        printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
755        printk("turning off the locking correctness validator.\n");
756        dump_stack();
757        return NULL;
758    }
759    class = lock_classes + nr_lock_classes++;
760    debug_atomic_inc(nr_unused_locks);
761    class->key = key;
762    class->name = lock->name;
763    class->subclass = subclass;
764    INIT_LIST_HEAD(&class->lock_entry);
765    INIT_LIST_HEAD(&class->locks_before);
766    INIT_LIST_HEAD(&class->locks_after);
767    class->name_version = count_matching_names(class);
768    /*
769     * We use RCU's safe list-add method to make
770     * parallel walking of the hash-list safe:
771     */
772    list_add_tail_rcu(&class->hash_entry, hash_head);
773    /*
774     * Add it to the global list of classes:
775     */
776    list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
777
778    if (verbose(class)) {
779        graph_unlock();
780        raw_local_irq_restore(flags);
781
782        printk("\nnew class %p: %s", class->key, class->name);
783        if (class->name_version > 1)
784            printk("#%d", class->name_version);
785        printk("\n");
786        dump_stack();
787
788        raw_local_irq_save(flags);
789        if (!graph_lock()) {
790            raw_local_irq_restore(flags);
791            return NULL;
792        }
793    }
794out_unlock_set:
795    graph_unlock();
796    raw_local_irq_restore(flags);
797
798    if (!subclass || force)
799        lock->class_cache[0] = class;
800    else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
801        lock->class_cache[subclass] = class;
802
803    if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
804        return NULL;
805
806    return class;
807}
808
809#ifdef CONFIG_PROVE_LOCKING
810/*
811 * Allocate a lockdep entry. (assumes the graph_lock held, returns
812 * with NULL on failure)
813 */
814static struct lock_list *alloc_list_entry(void)
815{
816    if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
817        if (!debug_locks_off_graph_unlock())
818            return NULL;
819
820        printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
821        printk("turning off the locking correctness validator.\n");
822        dump_stack();
823        return NULL;
824    }
825    return list_entries + nr_list_entries++;
826}
827
828/*
829 * Add a new dependency to the head of the list:
830 */
831static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
832                struct list_head *head, unsigned long ip,
833                int distance, struct stack_trace *trace)
834{
835    struct lock_list *entry;
836    /*
837     * Lock not present yet - get a new dependency struct and
838     * add it to the list:
839     */
840    entry = alloc_list_entry();
841    if (!entry)
842        return 0;
843
844    entry->class = this;
845    entry->distance = distance;
846    entry->trace = *trace;
847    /*
848     * Since we never remove from the dependency list, the list can
849     * be walked lockless by other CPUs, it's only allocation
850     * that must be protected by the spinlock. But this also means
851     * we must make new entries visible only once writes to the
852     * entry become visible - hence the RCU op:
853     */
854    list_add_tail_rcu(&entry->entry, head);
855
856    return 1;
857}
858
859/*
860 * For good efficiency of modular, we use power of 2
861 */
862#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
863#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
864
865/*
866 * The circular_queue and helpers is used to implement the
867 * breadth-first search(BFS)algorithem, by which we can build
868 * the shortest path from the next lock to be acquired to the
869 * previous held lock if there is a circular between them.
870 */
871struct circular_queue {
872    unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
873    unsigned int front, rear;
874};
875
876static struct circular_queue lock_cq;
877
878unsigned int max_bfs_queue_depth;
879
880static unsigned int lockdep_dependency_gen_id;
881
882static inline void __cq_init(struct circular_queue *cq)
883{
884    cq->front = cq->rear = 0;
885    lockdep_dependency_gen_id++;
886}
887
888static inline int __cq_empty(struct circular_queue *cq)
889{
890    return (cq->front == cq->rear);
891}
892
893static inline int __cq_full(struct circular_queue *cq)
894{
895    return ((cq->rear + 1) & CQ_MASK) == cq->front;
896}
897
898static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
899{
900    if (__cq_full(cq))
901        return -1;
902
903    cq->element[cq->rear] = elem;
904    cq->rear = (cq->rear + 1) & CQ_MASK;
905    return 0;
906}
907
908static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
909{
910    if (__cq_empty(cq))
911        return -1;
912
913    *elem = cq->element[cq->front];
914    cq->front = (cq->front + 1) & CQ_MASK;
915    return 0;
916}
917
918static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
919{
920    return (cq->rear - cq->front) & CQ_MASK;
921}
922
923static inline void mark_lock_accessed(struct lock_list *lock,
924                    struct lock_list *parent)
925{
926    unsigned long nr;
927
928    nr = lock - list_entries;
929    WARN_ON(nr >= nr_list_entries);
930    lock->parent = parent;
931    lock->class->dep_gen_id = lockdep_dependency_gen_id;
932}
933
934static inline unsigned long lock_accessed(struct lock_list *lock)
935{
936    unsigned long nr;
937
938    nr = lock - list_entries;
939    WARN_ON(nr >= nr_list_entries);
940    return lock->class->dep_gen_id == lockdep_dependency_gen_id;
941}
942
943static inline struct lock_list *get_lock_parent(struct lock_list *child)
944{
945    return child->parent;
946}
947
948static inline int get_lock_depth(struct lock_list *child)
949{
950    int depth = 0;
951    struct lock_list *parent;
952
953    while ((parent = get_lock_parent(child))) {
954        child = parent;
955        depth++;
956    }
957    return depth;
958}
959
960static int __bfs(struct lock_list *source_entry,
961         void *data,
962         int (*match)(struct lock_list *entry, void *data),
963         struct lock_list **target_entry,
964         int forward)
965{
966    struct lock_list *entry;
967    struct list_head *head;
968    struct circular_queue *cq = &lock_cq;
969    int ret = 1;
970
971    if (match(source_entry, data)) {
972        *target_entry = source_entry;
973        ret = 0;
974        goto exit;
975    }
976
977    if (forward)
978        head = &source_entry->class->locks_after;
979    else
980        head = &source_entry->class->locks_before;
981
982    if (list_empty(head))
983        goto exit;
984
985    __cq_init(cq);
986    __cq_enqueue(cq, (unsigned long)source_entry);
987
988    while (!__cq_empty(cq)) {
989        struct lock_list *lock;
990
991        __cq_dequeue(cq, (unsigned long *)&lock);
992
993        if (!lock->class) {
994            ret = -2;
995            goto exit;
996        }
997
998        if (forward)
999            head = &lock->class->locks_after;
1000        else
1001            head = &lock->class->locks_before;
1002
1003        list_for_each_entry(entry, head, entry) {
1004            if (!lock_accessed(entry)) {
1005                unsigned int cq_depth;
1006                mark_lock_accessed(entry, lock);
1007                if (match(entry, data)) {
1008                    *target_entry = entry;
1009                    ret = 0;
1010                    goto exit;
1011                }
1012
1013                if (__cq_enqueue(cq, (unsigned long)entry)) {
1014                    ret = -1;
1015                    goto exit;
1016                }
1017                cq_depth = __cq_get_elem_count(cq);
1018                if (max_bfs_queue_depth < cq_depth)
1019                    max_bfs_queue_depth = cq_depth;
1020            }
1021        }
1022    }
1023exit:
1024    return ret;
1025}
1026
1027static inline int __bfs_forwards(struct lock_list *src_entry,
1028            void *data,
1029            int (*match)(struct lock_list *entry, void *data),
1030            struct lock_list **target_entry)
1031{
1032    return __bfs(src_entry, data, match, target_entry, 1);
1033
1034}
1035
1036static inline int __bfs_backwards(struct lock_list *src_entry,
1037            void *data,
1038            int (*match)(struct lock_list *entry, void *data),
1039            struct lock_list **target_entry)
1040{
1041    return __bfs(src_entry, data, match, target_entry, 0);
1042
1043}
1044
1045/*
1046 * Recursive, forwards-direction lock-dependency checking, used for
1047 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1048 * checking.
1049 */
1050
1051/*
1052 * Print a dependency chain entry (this is only done when a deadlock
1053 * has been detected):
1054 */
1055static noinline int
1056print_circular_bug_entry(struct lock_list *target, int depth)
1057{
1058    if (debug_locks_silent)
1059        return 0;
1060    printk("\n-> #%u", depth);
1061    print_lock_name(target->class);
1062    printk(":\n");
1063    print_stack_trace(&target->trace, 6);
1064
1065    return 0;
1066}
1067
1068static void
1069print_circular_lock_scenario(struct held_lock *src,
1070                 struct held_lock *tgt,
1071                 struct lock_list *prt)
1072{
1073    struct lock_class *source = hlock_class(src);
1074    struct lock_class *target = hlock_class(tgt);
1075    struct lock_class *parent = prt->class;
1076
1077    /*
1078     * A direct locking problem where unsafe_class lock is taken
1079     * directly by safe_class lock, then all we need to show
1080     * is the deadlock scenario, as it is obvious that the
1081     * unsafe lock is taken under the safe lock.
1082     *
1083     * But if there is a chain instead, where the safe lock takes
1084     * an intermediate lock (middle_class) where this lock is
1085     * not the same as the safe lock, then the lock chain is
1086     * used to describe the problem. Otherwise we would need
1087     * to show a different CPU case for each link in the chain
1088     * from the safe_class lock to the unsafe_class lock.
1089     */
1090    if (parent != source) {
1091        printk("Chain exists of:\n ");
1092        __print_lock_name(source);
1093        printk(" --> ");
1094        __print_lock_name(parent);
1095        printk(" --> ");
1096        __print_lock_name(target);
1097        printk("\n\n");
1098    }
1099
1100    printk(" Possible unsafe locking scenario:\n\n");
1101    printk(" CPU0 CPU1\n");
1102    printk(" ---- ----\n");
1103    printk(" lock(");
1104    __print_lock_name(target);
1105    printk(");\n");
1106    printk(" lock(");
1107    __print_lock_name(parent);
1108    printk(");\n");
1109    printk(" lock(");
1110    __print_lock_name(target);
1111    printk(");\n");
1112    printk(" lock(");
1113    __print_lock_name(source);
1114    printk(");\n");
1115    printk("\n *** DEADLOCK ***\n\n");
1116}
1117
1118/*
1119 * When a circular dependency is detected, print the
1120 * header first:
1121 */
1122static noinline int
1123print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1124            struct held_lock *check_src,
1125            struct held_lock *check_tgt)
1126{
1127    struct task_struct *curr = current;
1128
1129    if (debug_locks_silent)
1130        return 0;
1131
1132    printk("\n=======================================================\n");
1133    printk( "[ INFO: possible circular locking dependency detected ]\n");
1134    print_kernel_version();
1135    printk( "-------------------------------------------------------\n");
1136    printk("%s/%d is trying to acquire lock:\n",
1137        curr->comm, task_pid_nr(curr));
1138    print_lock(check_src);
1139    printk("\nbut task is already holding lock:\n");
1140    print_lock(check_tgt);
1141    printk("\nwhich lock already depends on the new lock.\n\n");
1142    printk("\nthe existing dependency chain (in reverse order) is:\n");
1143
1144    print_circular_bug_entry(entry, depth);
1145
1146    return 0;
1147}
1148
1149static inline int class_equal(struct lock_list *entry, void *data)
1150{
1151    return entry->class == data;
1152}
1153
1154static noinline int print_circular_bug(struct lock_list *this,
1155                struct lock_list *target,
1156                struct held_lock *check_src,
1157                struct held_lock *check_tgt)
1158{
1159    struct task_struct *curr = current;
1160    struct lock_list *parent;
1161    struct lock_list *first_parent;
1162    int depth;
1163
1164    if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1165        return 0;
1166
1167    if (!save_trace(&this->trace))
1168        return 0;
1169
1170    depth = get_lock_depth(target);
1171
1172    print_circular_bug_header(target, depth, check_src, check_tgt);
1173
1174    parent = get_lock_parent(target);
1175    first_parent = parent;
1176
1177    while (parent) {
1178        print_circular_bug_entry(parent, --depth);
1179        parent = get_lock_parent(parent);
1180    }
1181
1182    printk("\nother info that might help us debug this:\n\n");
1183    print_circular_lock_scenario(check_src, check_tgt,
1184                     first_parent);
1185
1186    lockdep_print_held_locks(curr);
1187
1188    printk("\nstack backtrace:\n");
1189    dump_stack();
1190
1191    return 0;
1192}
1193
1194static noinline int print_bfs_bug(int ret)
1195{
1196    if (!debug_locks_off_graph_unlock())
1197        return 0;
1198
1199    WARN(1, "lockdep bfs error:%d\n", ret);
1200
1201    return 0;
1202}
1203
1204static int noop_count(struct lock_list *entry, void *data)
1205{
1206    (*(unsigned long *)data)++;
1207    return 0;
1208}
1209
1210unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1211{
1212    unsigned long count = 0;
1213    struct lock_list *uninitialized_var(target_entry);
1214
1215    __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1216
1217    return count;
1218}
1219unsigned long lockdep_count_forward_deps(struct lock_class *class)
1220{
1221    unsigned long ret, flags;
1222    struct lock_list this;
1223
1224    this.parent = NULL;
1225    this.class = class;
1226
1227    local_irq_save(flags);
1228    arch_spin_lock(&lockdep_lock);
1229    ret = __lockdep_count_forward_deps(&this);
1230    arch_spin_unlock(&lockdep_lock);
1231    local_irq_restore(flags);
1232
1233    return ret;
1234}
1235
1236unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1237{
1238    unsigned long count = 0;
1239    struct lock_list *uninitialized_var(target_entry);
1240
1241    __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1242
1243    return count;
1244}
1245
1246unsigned long lockdep_count_backward_deps(struct lock_class *class)
1247{
1248    unsigned long ret, flags;
1249    struct lock_list this;
1250
1251    this.parent = NULL;
1252    this.class = class;
1253
1254    local_irq_save(flags);
1255    arch_spin_lock(&lockdep_lock);
1256    ret = __lockdep_count_backward_deps(&this);
1257    arch_spin_unlock(&lockdep_lock);
1258    local_irq_restore(flags);
1259
1260    return ret;
1261}
1262
1263/*
1264 * Prove that the dependency graph starting at <entry> can not
1265 * lead to <target>. Print an error and return 0 if it does.
1266 */
1267static noinline int
1268check_noncircular(struct lock_list *root, struct lock_class *target,
1269        struct lock_list **target_entry)
1270{
1271    int result;
1272
1273    debug_atomic_inc(nr_cyclic_checks);
1274
1275    result = __bfs_forwards(root, target, class_equal, target_entry);
1276
1277    return result;
1278}
1279
1280#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1281/*
1282 * Forwards and backwards subgraph searching, for the purposes of
1283 * proving that two subgraphs can be connected by a new dependency
1284 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1285 */
1286
1287static inline int usage_match(struct lock_list *entry, void *bit)
1288{
1289    return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1290}
1291
1292
1293
1294/*
1295 * Find a node in the forwards-direction dependency sub-graph starting
1296 * at @root->class that matches @bit.
1297 *
1298 * Return 0 if such a node exists in the subgraph, and put that node
1299 * into *@target_entry.
1300 *
1301 * Return 1 otherwise and keep *@target_entry unchanged.
1302 * Return <0 on error.
1303 */
1304static int
1305find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1306            struct lock_list **target_entry)
1307{
1308    int result;
1309
1310    debug_atomic_inc(nr_find_usage_forwards_checks);
1311
1312    result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1313
1314    return result;
1315}
1316
1317/*
1318 * Find a node in the backwards-direction dependency sub-graph starting
1319 * at @root->class that matches @bit.
1320 *
1321 * Return 0 if such a node exists in the subgraph, and put that node
1322 * into *@target_entry.
1323 *
1324 * Return 1 otherwise and keep *@target_entry unchanged.
1325 * Return <0 on error.
1326 */
1327static int
1328find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1329            struct lock_list **target_entry)
1330{
1331    int result;
1332
1333    debug_atomic_inc(nr_find_usage_backwards_checks);
1334
1335    result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1336
1337    return result;
1338}
1339
1340static void print_lock_class_header(struct lock_class *class, int depth)
1341{
1342    int bit;
1343
1344    printk("%*s->", depth, "");
1345    print_lock_name(class);
1346    printk(" ops: %lu", class->ops);
1347    printk(" {\n");
1348
1349    for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1350        if (class->usage_mask & (1 << bit)) {
1351            int len = depth;
1352
1353            len += printk("%*s %s", depth, "", usage_str[bit]);
1354            len += printk(" at:\n");
1355            print_stack_trace(class->usage_traces + bit, len);
1356        }
1357    }
1358    printk("%*s }\n", depth, "");
1359
1360    printk("%*s ... key at: ",depth,"");
1361    print_ip_sym((unsigned long)class->key);
1362}
1363
1364/*
1365 * printk the shortest lock dependencies from @start to @end in reverse order:
1366 */
1367static void __used
1368print_shortest_lock_dependencies(struct lock_list *leaf,
1369                struct lock_list *root)
1370{
1371    struct lock_list *entry = leaf;
1372    int depth;
1373
1374    /*compute depth from generated tree by BFS*/
1375    depth = get_lock_depth(leaf);
1376
1377    do {
1378        print_lock_class_header(entry->class, depth);
1379        printk("%*s ... acquired at:\n", depth, "");
1380        print_stack_trace(&entry->trace, 2);
1381        printk("\n");
1382
1383        if (depth == 0 && (entry != root)) {
1384            printk("lockdep:%s bad path found in chain graph\n", __func__);
1385            break;
1386        }
1387
1388        entry = get_lock_parent(entry);
1389        depth--;
1390    } while (entry && (depth >= 0));
1391
1392    return;
1393}
1394
1395static void
1396print_irq_lock_scenario(struct lock_list *safe_entry,
1397            struct lock_list *unsafe_entry,
1398            struct lock_class *prev_class,
1399            struct lock_class *next_class)
1400{
1401    struct lock_class *safe_class = safe_entry->class;
1402    struct lock_class *unsafe_class = unsafe_entry->class;
1403    struct lock_class *middle_class = prev_class;
1404
1405    if (middle_class == safe_class)
1406        middle_class = next_class;
1407
1408    /*
1409     * A direct locking problem where unsafe_class lock is taken
1410     * directly by safe_class lock, then all we need to show
1411     * is the deadlock scenario, as it is obvious that the
1412     * unsafe lock is taken under the safe lock.
1413     *
1414     * But if there is a chain instead, where the safe lock takes
1415     * an intermediate lock (middle_class) where this lock is
1416     * not the same as the safe lock, then the lock chain is
1417     * used to describe the problem. Otherwise we would need
1418     * to show a different CPU case for each link in the chain
1419     * from the safe_class lock to the unsafe_class lock.
1420     */
1421    if (middle_class != unsafe_class) {
1422        printk("Chain exists of:\n ");
1423        __print_lock_name(safe_class);
1424        printk(" --> ");
1425        __print_lock_name(middle_class);
1426        printk(" --> ");
1427        __print_lock_name(unsafe_class);
1428        printk("\n\n");
1429    }
1430
1431    printk(" Possible interrupt unsafe locking scenario:\n\n");
1432    printk(" CPU0 CPU1\n");
1433    printk(" ---- ----\n");
1434    printk(" lock(");
1435    __print_lock_name(unsafe_class);
1436    printk(");\n");
1437    printk(" local_irq_disable();\n");
1438    printk(" lock(");
1439    __print_lock_name(safe_class);
1440    printk(");\n");
1441    printk(" lock(");
1442    __print_lock_name(middle_class);
1443    printk(");\n");
1444    printk(" <Interrupt>\n");
1445    printk(" lock(");
1446    __print_lock_name(safe_class);
1447    printk(");\n");
1448    printk("\n *** DEADLOCK ***\n\n");
1449}
1450
1451static int
1452print_bad_irq_dependency(struct task_struct *curr,
1453             struct lock_list *prev_root,
1454             struct lock_list *next_root,
1455             struct lock_list *backwards_entry,
1456             struct lock_list *forwards_entry,
1457             struct held_lock *prev,
1458             struct held_lock *next,
1459             enum lock_usage_bit bit1,
1460             enum lock_usage_bit bit2,
1461             const char *irqclass)
1462{
1463    if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1464        return 0;
1465
1466    printk("\n======================================================\n");
1467    printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1468        irqclass, irqclass);
1469    print_kernel_version();
1470    printk( "------------------------------------------------------\n");
1471    printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1472        curr->comm, task_pid_nr(curr),
1473        curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1474        curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1475        curr->hardirqs_enabled,
1476        curr->softirqs_enabled);
1477    print_lock(next);
1478
1479    printk("\nand this task is already holding:\n");
1480    print_lock(prev);
1481    printk("which would create a new lock dependency:\n");
1482    print_lock_name(hlock_class(prev));
1483    printk(" ->");
1484    print_lock_name(hlock_class(next));
1485    printk("\n");
1486
1487    printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1488        irqclass);
1489    print_lock_name(backwards_entry->class);
1490    printk("\n... which became %s-irq-safe at:\n", irqclass);
1491
1492    print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1493
1494    printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1495    print_lock_name(forwards_entry->class);
1496    printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1497    printk("...");
1498
1499    print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1500
1501    printk("\nother info that might help us debug this:\n\n");
1502    print_irq_lock_scenario(backwards_entry, forwards_entry,
1503                hlock_class(prev), hlock_class(next));
1504
1505    lockdep_print_held_locks(curr);
1506
1507    printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1508    printk(" and the holding lock:\n");
1509    if (!save_trace(&prev_root->trace))
1510        return 0;
1511    print_shortest_lock_dependencies(backwards_entry, prev_root);
1512
1513    printk("\nthe dependencies between the lock to be acquired");
1514    printk(" and %s-irq-unsafe lock:\n", irqclass);
1515    if (!save_trace(&next_root->trace))
1516        return 0;
1517    print_shortest_lock_dependencies(forwards_entry, next_root);
1518
1519    printk("\nstack backtrace:\n");
1520    dump_stack();
1521
1522    return 0;
1523}
1524
1525static int
1526check_usage(struct task_struct *curr, struct held_lock *prev,
1527        struct held_lock *next, enum lock_usage_bit bit_backwards,
1528        enum lock_usage_bit bit_forwards, const char *irqclass)
1529{
1530    int ret;
1531    struct lock_list this, that;
1532    struct lock_list *uninitialized_var(target_entry);
1533    struct lock_list *uninitialized_var(target_entry1);
1534
1535    this.parent = NULL;
1536
1537    this.class = hlock_class(prev);
1538    ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1539    if (ret < 0)
1540        return print_bfs_bug(ret);
1541    if (ret == 1)
1542        return ret;
1543
1544    that.parent = NULL;
1545    that.class = hlock_class(next);
1546    ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1547    if (ret < 0)
1548        return print_bfs_bug(ret);
1549    if (ret == 1)
1550        return ret;
1551
1552    return print_bad_irq_dependency(curr, &this, &that,
1553            target_entry, target_entry1,
1554            prev, next,
1555            bit_backwards, bit_forwards, irqclass);
1556}
1557
1558static const char *state_names[] = {
1559#define LOCKDEP_STATE(__STATE) \
1560    __stringify(__STATE),
1561#include "lockdep_states.h"
1562#undef LOCKDEP_STATE
1563};
1564
1565static const char *state_rnames[] = {
1566#define LOCKDEP_STATE(__STATE) \
1567    __stringify(__STATE)"-READ",
1568#include "lockdep_states.h"
1569#undef LOCKDEP_STATE
1570};
1571
1572static inline const char *state_name(enum lock_usage_bit bit)
1573{
1574    return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1575}
1576
1577static int exclusive_bit(int new_bit)
1578{
1579    /*
1580     * USED_IN
1581     * USED_IN_READ
1582     * ENABLED
1583     * ENABLED_READ
1584     *
1585     * bit 0 - write/read
1586     * bit 1 - used_in/enabled
1587     * bit 2+ state
1588     */
1589
1590    int state = new_bit & ~3;
1591    int dir = new_bit & 2;
1592
1593    /*
1594     * keep state, bit flip the direction and strip read.
1595     */
1596    return state | (dir ^ 2);
1597}
1598
1599static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1600               struct held_lock *next, enum lock_usage_bit bit)
1601{
1602    /*
1603     * Prove that the new dependency does not connect a hardirq-safe
1604     * lock with a hardirq-unsafe lock - to achieve this we search
1605     * the backwards-subgraph starting at <prev>, and the
1606     * forwards-subgraph starting at <next>:
1607     */
1608    if (!check_usage(curr, prev, next, bit,
1609               exclusive_bit(bit), state_name(bit)))
1610        return 0;
1611
1612    bit++; /* _READ */
1613
1614    /*
1615     * Prove that the new dependency does not connect a hardirq-safe-read
1616     * lock with a hardirq-unsafe lock - to achieve this we search
1617     * the backwards-subgraph starting at <prev>, and the
1618     * forwards-subgraph starting at <next>:
1619     */
1620    if (!check_usage(curr, prev, next, bit,
1621               exclusive_bit(bit), state_name(bit)))
1622        return 0;
1623
1624    return 1;
1625}
1626
1627static int
1628check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1629        struct held_lock *next)
1630{
1631#define LOCKDEP_STATE(__STATE) \
1632    if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1633        return 0;
1634#include "lockdep_states.h"
1635#undef LOCKDEP_STATE
1636
1637    return 1;
1638}
1639
1640static void inc_chains(void)
1641{
1642    if (current->hardirq_context)
1643        nr_hardirq_chains++;
1644    else {
1645        if (current->softirq_context)
1646            nr_softirq_chains++;
1647        else
1648            nr_process_chains++;
1649    }
1650}
1651
1652#else
1653
1654static inline int
1655check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1656        struct held_lock *next)
1657{
1658    return 1;
1659}
1660
1661static inline void inc_chains(void)
1662{
1663    nr_process_chains++;
1664}
1665
1666#endif
1667
1668static void
1669print_deadlock_scenario(struct held_lock *nxt,
1670                 struct held_lock *prv)
1671{
1672    struct lock_class *next = hlock_class(nxt);
1673    struct lock_class *prev = hlock_class(prv);
1674
1675    printk(" Possible unsafe locking scenario:\n\n");
1676    printk(" CPU0\n");
1677    printk(" ----\n");
1678    printk(" lock(");
1679    __print_lock_name(prev);
1680    printk(");\n");
1681    printk(" lock(");
1682    __print_lock_name(next);
1683    printk(");\n");
1684    printk("\n *** DEADLOCK ***\n\n");
1685    printk(" May be due to missing lock nesting notation\n\n");
1686}
1687
1688static int
1689print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1690           struct held_lock *next)
1691{
1692    if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1693        return 0;
1694
1695    printk("\n=============================================\n");
1696    printk( "[ INFO: possible recursive locking detected ]\n");
1697    print_kernel_version();
1698    printk( "---------------------------------------------\n");
1699    printk("%s/%d is trying to acquire lock:\n",
1700        curr->comm, task_pid_nr(curr));
1701    print_lock(next);
1702    printk("\nbut task is already holding lock:\n");
1703    print_lock(prev);
1704
1705    printk("\nother info that might help us debug this:\n");
1706    print_deadlock_scenario(next, prev);
1707    lockdep_print_held_locks(curr);
1708
1709    printk("\nstack backtrace:\n");
1710    dump_stack();
1711
1712    return 0;
1713}
1714
1715/*
1716 * Check whether we are holding such a class already.
1717 *
1718 * (Note that this has to be done separately, because the graph cannot
1719 * detect such classes of deadlocks.)
1720 *
1721 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1722 */
1723static int
1724check_deadlock(struct task_struct *curr, struct held_lock *next,
1725           struct lockdep_map *next_instance, int read)
1726{
1727    struct held_lock *prev;
1728    struct held_lock *nest = NULL;
1729    int i;
1730
1731    for (i = 0; i < curr->lockdep_depth; i++) {
1732        prev = curr->held_locks + i;
1733
1734        if (prev->instance == next->nest_lock)
1735            nest = prev;
1736
1737        if (hlock_class(prev) != hlock_class(next))
1738            continue;
1739
1740        /*
1741         * Allow read-after-read recursion of the same
1742         * lock class (i.e. read_lock(lock)+read_lock(lock)):
1743         */
1744        if ((read == 2) && prev->read)
1745            return 2;
1746
1747        /*
1748         * We're holding the nest_lock, which serializes this lock's
1749         * nesting behaviour.
1750         */
1751        if (nest)
1752            return 2;
1753
1754        return print_deadlock_bug(curr, prev, next);
1755    }
1756    return 1;
1757}
1758
1759/*
1760 * There was a chain-cache miss, and we are about to add a new dependency
1761 * to a previous lock. We recursively validate the following rules:
1762 *
1763 * - would the adding of the <prev> -> <next> dependency create a
1764 * circular dependency in the graph? [== circular deadlock]
1765 *
1766 * - does the new prev->next dependency connect any hardirq-safe lock
1767 * (in the full backwards-subgraph starting at <prev>) with any
1768 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1769 * <next>)? [== illegal lock inversion with hardirq contexts]
1770 *
1771 * - does the new prev->next dependency connect any softirq-safe lock
1772 * (in the full backwards-subgraph starting at <prev>) with any
1773 * softirq-unsafe lock (in the full forwards-subgraph starting at
1774 * <next>)? [== illegal lock inversion with softirq contexts]
1775 *
1776 * any of these scenarios could lead to a deadlock.
1777 *
1778 * Then if all the validations pass, we add the forwards and backwards
1779 * dependency.
1780 */
1781static int
1782check_prev_add(struct task_struct *curr, struct held_lock *prev,
1783           struct held_lock *next, int distance, int trylock_loop)
1784{
1785    struct lock_list *entry;
1786    int ret;
1787    struct lock_list this;
1788    struct lock_list *uninitialized_var(target_entry);
1789    /*
1790     * Static variable, serialized by the graph_lock().
1791     *
1792     * We use this static variable to save the stack trace in case
1793     * we call into this function multiple times due to encountering
1794     * trylocks in the held lock stack.
1795     */
1796    static struct stack_trace trace;
1797
1798    /*
1799     * Prove that the new <prev> -> <next> dependency would not
1800     * create a circular dependency in the graph. (We do this by
1801     * forward-recursing into the graph starting at <next>, and
1802     * checking whether we can reach <prev>.)
1803     *
1804     * We are using global variables to control the recursion, to
1805     * keep the stackframe size of the recursive functions low:
1806     */
1807    this.class = hlock_class(next);
1808    this.parent = NULL;
1809    ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1810    if (unlikely(!ret))
1811        return print_circular_bug(&this, target_entry, next, prev);
1812    else if (unlikely(ret < 0))
1813        return print_bfs_bug(ret);
1814
1815    if (!check_prev_add_irq(curr, prev, next))
1816        return 0;
1817
1818    /*
1819     * For recursive read-locks we do all the dependency checks,
1820     * but we dont store read-triggered dependencies (only
1821     * write-triggered dependencies). This ensures that only the
1822     * write-side dependencies matter, and that if for example a
1823     * write-lock never takes any other locks, then the reads are
1824     * equivalent to a NOP.
1825     */
1826    if (next->read == 2 || prev->read == 2)
1827        return 1;
1828    /*
1829     * Is the <prev> -> <next> dependency already present?
1830     *
1831     * (this may occur even though this is a new chain: consider
1832     * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1833     * chains - the second one will be new, but L1 already has
1834     * L2 added to its dependency list, due to the first chain.)
1835     */
1836    list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1837        if (entry->class == hlock_class(next)) {
1838            if (distance == 1)
1839                entry->distance = 1;
1840            return 2;
1841        }
1842    }
1843
1844    if (!trylock_loop && !save_trace(&trace))
1845        return 0;
1846
1847    /*
1848     * Ok, all validations passed, add the new lock
1849     * to the previous lock's dependency list:
1850     */
1851    ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1852                   &hlock_class(prev)->locks_after,
1853                   next->acquire_ip, distance, &trace);
1854
1855    if (!ret)
1856        return 0;
1857
1858    ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1859                   &hlock_class(next)->locks_before,
1860                   next->acquire_ip, distance, &trace);
1861    if (!ret)
1862        return 0;
1863
1864    /*
1865     * Debugging printouts:
1866     */
1867    if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1868        graph_unlock();
1869        printk("\n new dependency: ");
1870        print_lock_name(hlock_class(prev));
1871        printk(" => ");
1872        print_lock_name(hlock_class(next));
1873        printk("\n");
1874        dump_stack();
1875        return graph_lock();
1876    }
1877    return 1;
1878}
1879
1880/*
1881 * Add the dependency to all directly-previous locks that are 'relevant'.
1882 * The ones that are relevant are (in increasing distance from curr):
1883 * all consecutive trylock entries and the final non-trylock entry - or
1884 * the end of this context's lock-chain - whichever comes first.
1885 */
1886static int
1887check_prevs_add(struct task_struct *curr, struct held_lock *next)
1888{
1889    int depth = curr->lockdep_depth;
1890    int trylock_loop = 0;
1891    struct held_lock *hlock;
1892
1893    /*
1894     * Debugging checks.
1895     *
1896     * Depth must not be zero for a non-head lock:
1897     */
1898    if (!depth)
1899        goto out_bug;
1900    /*
1901     * At least two relevant locks must exist for this
1902     * to be a head:
1903     */
1904    if (curr->held_locks[depth].irq_context !=
1905            curr->held_locks[depth-1].irq_context)
1906        goto out_bug;
1907
1908    for (;;) {
1909        int distance = curr->lockdep_depth - depth + 1;
1910        hlock = curr->held_locks + depth-1;
1911        /*
1912         * Only non-recursive-read entries get new dependencies
1913         * added:
1914         */
1915        if (hlock->read != 2) {
1916            if (!check_prev_add(curr, hlock, next,
1917                        distance, trylock_loop))
1918                return 0;
1919            /*
1920             * Stop after the first non-trylock entry,
1921             * as non-trylock entries have added their
1922             * own direct dependencies already, so this
1923             * lock is connected to them indirectly:
1924             */
1925            if (!hlock->trylock)
1926                break;
1927        }
1928        depth--;
1929        /*
1930         * End of lock-stack?
1931         */
1932        if (!depth)
1933            break;
1934        /*
1935         * Stop the search if we cross into another context:
1936         */
1937        if (curr->held_locks[depth].irq_context !=
1938                curr->held_locks[depth-1].irq_context)
1939            break;
1940        trylock_loop = 1;
1941    }
1942    return 1;
1943out_bug:
1944    if (!debug_locks_off_graph_unlock())
1945        return 0;
1946
1947    WARN_ON(1);
1948
1949    return 0;
1950}
1951
1952unsigned long nr_lock_chains;
1953struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1954int nr_chain_hlocks;
1955static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1956
1957struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1958{
1959    return lock_classes + chain_hlocks[chain->base + i];
1960}
1961
1962/*
1963 * Look up a dependency chain. If the key is not present yet then
1964 * add it and return 1 - in this case the new dependency chain is
1965 * validated. If the key is already hashed, return 0.
1966 * (On return with 1 graph_lock is held.)
1967 */
1968static inline int lookup_chain_cache(struct task_struct *curr,
1969                     struct held_lock *hlock,
1970                     u64 chain_key)
1971{
1972    struct lock_class *class = hlock_class(hlock);
1973    struct list_head *hash_head = chainhashentry(chain_key);
1974    struct lock_chain *chain;
1975    struct held_lock *hlock_curr, *hlock_next;
1976    int i, j;
1977
1978    if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1979        return 0;
1980    /*
1981     * We can walk it lock-free, because entries only get added
1982     * to the hash:
1983     */
1984    list_for_each_entry(chain, hash_head, entry) {
1985        if (chain->chain_key == chain_key) {
1986cache_hit:
1987            debug_atomic_inc(chain_lookup_hits);
1988            if (very_verbose(class))
1989                printk("\nhash chain already cached, key: "
1990                    "%016Lx tail class: [%p] %s\n",
1991                    (unsigned long long)chain_key,
1992                    class->key, class->name);
1993            return 0;
1994        }
1995    }
1996    if (very_verbose(class))
1997        printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1998            (unsigned long long)chain_key, class->key, class->name);
1999    /*
2000     * Allocate a new chain entry from the static array, and add
2001     * it to the hash:
2002     */
2003    if (!graph_lock())
2004        return 0;
2005    /*
2006     * We have to walk the chain again locked - to avoid duplicates:
2007     */
2008    list_for_each_entry(chain, hash_head, entry) {
2009        if (chain->chain_key == chain_key) {
2010            graph_unlock();
2011            goto cache_hit;
2012        }
2013    }
2014    if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2015        if (!debug_locks_off_graph_unlock())
2016            return 0;
2017
2018        printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2019        printk("turning off the locking correctness validator.\n");
2020        dump_stack();
2021        return 0;
2022    }
2023    chain = lock_chains + nr_lock_chains++;
2024    chain->chain_key = chain_key;
2025    chain->irq_context = hlock->irq_context;
2026    /* Find the first held_lock of current chain */
2027    hlock_next = hlock;
2028    for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2029        hlock_curr = curr->held_locks + i;
2030        if (hlock_curr->irq_context != hlock_next->irq_context)
2031            break;
2032        hlock_next = hlock;
2033    }
2034    i++;
2035    chain->depth = curr->lockdep_depth + 1 - i;
2036    if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2037        chain->base = nr_chain_hlocks;
2038        nr_chain_hlocks += chain->depth;
2039        for (j = 0; j < chain->depth - 1; j++, i++) {
2040            int lock_id = curr->held_locks[i].class_idx - 1;
2041            chain_hlocks[chain->base + j] = lock_id;
2042        }
2043        chain_hlocks[chain->base + j] = class - lock_classes;
2044    }
2045    list_add_tail_rcu(&chain->entry, hash_head);
2046    debug_atomic_inc(chain_lookup_misses);
2047    inc_chains();
2048
2049    return 1;
2050}
2051
2052static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2053        struct held_lock *hlock, int chain_head, u64 chain_key)
2054{
2055    /*
2056     * Trylock needs to maintain the stack of held locks, but it
2057     * does not add new dependencies, because trylock can be done
2058     * in any order.
2059     *
2060     * We look up the chain_key and do the O(N^2) check and update of
2061     * the dependencies only if this is a new dependency chain.
2062     * (If lookup_chain_cache() returns with 1 it acquires
2063     * graph_lock for us)
2064     */
2065    if (!hlock->trylock && (hlock->check == 2) &&
2066        lookup_chain_cache(curr, hlock, chain_key)) {
2067        /*
2068         * Check whether last held lock:
2069         *
2070         * - is irq-safe, if this lock is irq-unsafe
2071         * - is softirq-safe, if this lock is hardirq-unsafe
2072         *
2073         * And check whether the new lock's dependency graph
2074         * could lead back to the previous lock.
2075         *
2076         * any of these scenarios could lead to a deadlock. If
2077         * All validations
2078         */
2079        int ret = check_deadlock(curr, hlock, lock, hlock->read);
2080
2081        if (!ret)
2082            return 0;
2083        /*
2084         * Mark recursive read, as we jump over it when
2085         * building dependencies (just like we jump over
2086         * trylock entries):
2087         */
2088        if (ret == 2)
2089            hlock->read = 2;
2090        /*
2091         * Add dependency only if this lock is not the head
2092         * of the chain, and if it's not a secondary read-lock:
2093         */
2094        if (!chain_head && ret != 2)
2095            if (!check_prevs_add(curr, hlock))
2096                return 0;
2097        graph_unlock();
2098    } else
2099        /* after lookup_chain_cache(): */
2100        if (unlikely(!debug_locks))
2101            return 0;
2102
2103    return 1;
2104}
2105#else
2106static inline int validate_chain(struct task_struct *curr,
2107               struct lockdep_map *lock, struct held_lock *hlock,
2108        int chain_head, u64 chain_key)
2109{
2110    return 1;
2111}
2112#endif
2113
2114/*
2115 * We are building curr_chain_key incrementally, so double-check
2116 * it from scratch, to make sure that it's done correctly:
2117 */
2118static void check_chain_key(struct task_struct *curr)
2119{
2120#ifdef CONFIG_DEBUG_LOCKDEP
2121    struct held_lock *hlock, *prev_hlock = NULL;
2122    unsigned int i, id;
2123    u64 chain_key = 0;
2124
2125    for (i = 0; i < curr->lockdep_depth; i++) {
2126        hlock = curr->held_locks + i;
2127        if (chain_key != hlock->prev_chain_key) {
2128            debug_locks_off();
2129            WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2130                curr->lockdep_depth, i,
2131                (unsigned long long)chain_key,
2132                (unsigned long long)hlock->prev_chain_key);
2133            return;
2134        }
2135        id = hlock->class_idx - 1;
2136        if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2137            return;
2138
2139        if (prev_hlock && (prev_hlock->irq_context !=
2140                            hlock->irq_context))
2141            chain_key = 0;
2142        chain_key = iterate_chain_key(chain_key, id);
2143        prev_hlock = hlock;
2144    }
2145    if (chain_key != curr->curr_chain_key) {
2146        debug_locks_off();
2147        WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2148            curr->lockdep_depth, i,
2149            (unsigned long long)chain_key,
2150            (unsigned long long)curr->curr_chain_key);
2151    }
2152#endif
2153}
2154
2155static void
2156print_usage_bug_scenario(struct held_lock *lock)
2157{
2158    struct lock_class *class = hlock_class(lock);
2159
2160    printk(" Possible unsafe locking scenario:\n\n");
2161    printk(" CPU0\n");
2162    printk(" ----\n");
2163    printk(" lock(");
2164    __print_lock_name(class);
2165    printk(");\n");
2166    printk(" <Interrupt>\n");
2167    printk(" lock(");
2168    __print_lock_name(class);
2169    printk(");\n");
2170    printk("\n *** DEADLOCK ***\n\n");
2171}
2172
2173static int
2174print_usage_bug(struct task_struct *curr, struct held_lock *this,
2175        enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2176{
2177    if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2178        return 0;
2179
2180    printk("\n=================================\n");
2181    printk( "[ INFO: inconsistent lock state ]\n");
2182    print_kernel_version();
2183    printk( "---------------------------------\n");
2184
2185    printk("inconsistent {%s} -> {%s} usage.\n",
2186        usage_str[prev_bit], usage_str[new_bit]);
2187
2188    printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2189        curr->comm, task_pid_nr(curr),
2190        trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2191        trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2192        trace_hardirqs_enabled(curr),
2193        trace_softirqs_enabled(curr));
2194    print_lock(this);
2195
2196    printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2197    print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2198
2199    print_irqtrace_events(curr);
2200    printk("\nother info that might help us debug this:\n");
2201    print_usage_bug_scenario(this);
2202
2203    lockdep_print_held_locks(curr);
2204
2205    printk("\nstack backtrace:\n");
2206    dump_stack();
2207
2208    return 0;
2209}
2210
2211/*
2212 * Print out an error if an invalid bit is set:
2213 */
2214static inline int
2215valid_state(struct task_struct *curr, struct held_lock *this,
2216        enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2217{
2218    if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2219        return print_usage_bug(curr, this, bad_bit, new_bit);
2220    return 1;
2221}
2222
2223static int mark_lock(struct task_struct *curr, struct held_lock *this,
2224             enum lock_usage_bit new_bit);
2225
2226#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2227
2228/*
2229 * print irq inversion bug:
2230 */
2231static int
2232print_irq_inversion_bug(struct task_struct *curr,
2233            struct lock_list *root, struct lock_list *other,
2234            struct held_lock *this, int forwards,
2235            const char *irqclass)
2236{
2237    struct lock_list *entry = other;
2238    struct lock_list *middle = NULL;
2239    int depth;
2240
2241    if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2242        return 0;
2243
2244    printk("\n=========================================================\n");
2245    printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2246    print_kernel_version();
2247    printk( "---------------------------------------------------------\n");
2248    printk("%s/%d just changed the state of lock:\n",
2249        curr->comm, task_pid_nr(curr));
2250    print_lock(this);
2251    if (forwards)
2252        printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2253    else
2254        printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2255    print_lock_name(other->class);
2256    printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2257
2258    printk("\nother info that might help us debug this:\n");
2259
2260    /* Find a middle lock (if one exists) */
2261    depth = get_lock_depth(other);
2262    do {
2263        if (depth == 0 && (entry != root)) {
2264            printk("lockdep:%s bad path found in chain graph\n", __func__);
2265            break;
2266        }
2267        middle = entry;
2268        entry = get_lock_parent(entry);
2269        depth--;
2270    } while (entry && entry != root && (depth >= 0));
2271    if (forwards)
2272        print_irq_lock_scenario(root, other,
2273            middle ? middle->class : root->class, other->class);
2274    else
2275        print_irq_lock_scenario(other, root,
2276            middle ? middle->class : other->class, root->class);
2277
2278    lockdep_print_held_locks(curr);
2279
2280    printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2281    if (!save_trace(&root->trace))
2282        return 0;
2283    print_shortest_lock_dependencies(other, root);
2284
2285    printk("\nstack backtrace:\n");
2286    dump_stack();
2287
2288    return 0;
2289}
2290
2291/*
2292 * Prove that in the forwards-direction subgraph starting at <this>
2293 * there is no lock matching <mask>:
2294 */
2295static int
2296check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2297             enum lock_usage_bit bit, const char *irqclass)
2298{
2299    int ret;
2300    struct lock_list root;
2301    struct lock_list *uninitialized_var(target_entry);
2302
2303    root.parent = NULL;
2304    root.class = hlock_class(this);
2305    ret = find_usage_forwards(&root, bit, &target_entry);
2306    if (ret < 0)
2307        return print_bfs_bug(ret);
2308    if (ret == 1)
2309        return ret;
2310
2311    return print_irq_inversion_bug(curr, &root, target_entry,
2312                    this, 1, irqclass);
2313}
2314
2315/*
2316 * Prove that in the backwards-direction subgraph starting at <this>
2317 * there is no lock matching <mask>:
2318 */
2319static int
2320check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2321              enum lock_usage_bit bit, const char *irqclass)
2322{
2323    int ret;
2324    struct lock_list root;
2325    struct lock_list *uninitialized_var(target_entry);
2326
2327    root.parent = NULL;
2328    root.class = hlock_class(this);
2329    ret = find_usage_backwards(&root, bit, &target_entry);
2330    if (ret < 0)
2331        return print_bfs_bug(ret);
2332    if (ret == 1)
2333        return ret;
2334
2335    return print_irq_inversion_bug(curr, &root, target_entry,
2336                    this, 0, irqclass);
2337}
2338
2339void print_irqtrace_events(struct task_struct *curr)
2340{
2341    printk("irq event stamp: %u\n", curr->irq_events);
2342    printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2343    print_ip_sym(curr->hardirq_enable_ip);
2344    printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2345    print_ip_sym(curr->hardirq_disable_ip);
2346    printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2347    print_ip_sym(curr->softirq_enable_ip);
2348    printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2349    print_ip_sym(curr->softirq_disable_ip);
2350}
2351
2352static int HARDIRQ_verbose(struct lock_class *class)
2353{
2354#if HARDIRQ_VERBOSE
2355    return class_filter(class);
2356#endif
2357    return 0;
2358}
2359
2360static int SOFTIRQ_verbose(struct lock_class *class)
2361{
2362#if SOFTIRQ_VERBOSE
2363    return class_filter(class);
2364#endif
2365    return 0;
2366}
2367
2368static int RECLAIM_FS_verbose(struct lock_class *class)
2369{
2370#if RECLAIM_VERBOSE
2371    return class_filter(class);
2372#endif
2373    return 0;
2374}
2375
2376#define STRICT_READ_CHECKS 1
2377
2378static int (*state_verbose_f[])(struct lock_class *class) = {
2379#define LOCKDEP_STATE(__STATE) \
2380    __STATE##_verbose,
2381#include "lockdep_states.h"
2382#undef LOCKDEP_STATE
2383};
2384
2385static inline int state_verbose(enum lock_usage_bit bit,
2386                struct lock_class *class)
2387{
2388    return state_verbose_f[bit >> 2](class);
2389}
2390
2391typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2392                 enum lock_usage_bit bit, const char *name);
2393
2394static int
2395mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2396        enum lock_usage_bit new_bit)
2397{
2398    int excl_bit = exclusive_bit(new_bit);
2399    int read = new_bit & 1;
2400    int dir = new_bit & 2;
2401
2402    /*
2403     * mark USED_IN has to look forwards -- to ensure no dependency
2404     * has ENABLED state, which would allow recursion deadlocks.
2405     *
2406     * mark ENABLED has to look backwards -- to ensure no dependee
2407     * has USED_IN state, which, again, would allow recursion deadlocks.
2408     */
2409    check_usage_f usage = dir ?
2410        check_usage_backwards : check_usage_forwards;
2411
2412    /*
2413     * Validate that this particular lock does not have conflicting
2414     * usage states.
2415     */
2416    if (!valid_state(curr, this, new_bit, excl_bit))
2417        return 0;
2418
2419    /*
2420     * Validate that the lock dependencies don't have conflicting usage
2421     * states.
2422     */
2423    if ((!read || !dir || STRICT_READ_CHECKS) &&
2424            !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2425        return 0;
2426
2427    /*
2428     * Check for read in write conflicts
2429     */
2430    if (!read) {
2431        if (!valid_state(curr, this, new_bit, excl_bit + 1))
2432            return 0;
2433
2434        if (STRICT_READ_CHECKS &&
2435            !usage(curr, this, excl_bit + 1,
2436                state_name(new_bit + 1)))
2437            return 0;
2438    }
2439
2440    if (state_verbose(new_bit, hlock_class(this)))
2441        return 2;
2442
2443    return 1;
2444}
2445
2446enum mark_type {
2447#define LOCKDEP_STATE(__STATE) __STATE,
2448#include "lockdep_states.h"
2449#undef LOCKDEP_STATE
2450};
2451
2452/*
2453 * Mark all held locks with a usage bit:
2454 */
2455static int
2456mark_held_locks(struct task_struct *curr, enum mark_type mark)
2457{
2458    enum lock_usage_bit usage_bit;
2459    struct held_lock *hlock;
2460    int i;
2461
2462    for (i = 0; i < curr->lockdep_depth; i++) {
2463        hlock = curr->held_locks + i;
2464
2465        usage_bit = 2 + (mark << 2); /* ENABLED */
2466        if (hlock->read)
2467            usage_bit += 1; /* READ */
2468
2469        BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2470
2471        if (!mark_lock(curr, hlock, usage_bit))
2472            return 0;
2473    }
2474
2475    return 1;
2476}
2477
2478/*
2479 * Hardirqs will be enabled:
2480 */
2481void trace_hardirqs_on_caller(unsigned long ip)
2482{
2483    struct task_struct *curr = current;
2484
2485    time_hardirqs_on(CALLER_ADDR0, ip);
2486
2487    if (unlikely(!debug_locks || current->lockdep_recursion))
2488        return;
2489
2490    if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2491        return;
2492
2493    if (unlikely(curr->hardirqs_enabled)) {
2494        /*
2495         * Neither irq nor preemption are disabled here
2496         * so this is racy by nature but losing one hit
2497         * in a stat is not a big deal.
2498         */
2499        __debug_atomic_inc(redundant_hardirqs_on);
2500        return;
2501    }
2502    /* we'll do an OFF -> ON transition: */
2503    curr->hardirqs_enabled = 1;
2504
2505    if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2506        return;
2507    if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2508        return;
2509    /*
2510     * We are going to turn hardirqs on, so set the
2511     * usage bit for all held locks:
2512     */
2513    if (!mark_held_locks(curr, HARDIRQ))
2514        return;
2515    /*
2516     * If we have softirqs enabled, then set the usage
2517     * bit for all held locks. (disabled hardirqs prevented
2518     * this bit from being set before)
2519     */
2520    if (curr->softirqs_enabled)
2521        if (!mark_held_locks(curr, SOFTIRQ))
2522            return;
2523
2524    curr->hardirq_enable_ip = ip;
2525    curr->hardirq_enable_event = ++curr->irq_events;
2526    debug_atomic_inc(hardirqs_on_events);
2527}
2528EXPORT_SYMBOL(trace_hardirqs_on_caller);
2529
2530void trace_hardirqs_on(void)
2531{
2532    trace_hardirqs_on_caller(CALLER_ADDR0);
2533}
2534EXPORT_SYMBOL(trace_hardirqs_on);
2535
2536/*
2537 * Hardirqs were disabled:
2538 */
2539void trace_hardirqs_off_caller(unsigned long ip)
2540{
2541    struct task_struct *curr = current;
2542
2543    time_hardirqs_off(CALLER_ADDR0, ip);
2544
2545    if (unlikely(!debug_locks || current->lockdep_recursion))
2546        return;
2547
2548    if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2549        return;
2550
2551    if (curr->hardirqs_enabled) {
2552        /*
2553         * We have done an ON -> OFF transition:
2554         */
2555        curr->hardirqs_enabled = 0;
2556        curr->hardirq_disable_ip = ip;
2557        curr->hardirq_disable_event = ++curr->irq_events;
2558        debug_atomic_inc(hardirqs_off_events);
2559    } else
2560        debug_atomic_inc(redundant_hardirqs_off);
2561}
2562EXPORT_SYMBOL(trace_hardirqs_off_caller);
2563
2564void trace_hardirqs_off(void)
2565{
2566    trace_hardirqs_off_caller(CALLER_ADDR0);
2567}
2568EXPORT_SYMBOL(trace_hardirqs_off);
2569
2570/*
2571 * Softirqs will be enabled:
2572 */
2573void trace_softirqs_on(unsigned long ip)
2574{
2575    struct task_struct *curr = current;
2576
2577    if (unlikely(!debug_locks))
2578        return;
2579
2580    if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2581        return;
2582
2583    if (curr->softirqs_enabled) {
2584        debug_atomic_inc(redundant_softirqs_on);
2585        return;
2586    }
2587
2588    /*
2589     * We'll do an OFF -> ON transition:
2590     */
2591    curr->softirqs_enabled = 1;
2592    curr->softirq_enable_ip = ip;
2593    curr->softirq_enable_event = ++curr->irq_events;
2594    debug_atomic_inc(softirqs_on_events);
2595    /*
2596     * We are going to turn softirqs on, so set the
2597     * usage bit for all held locks, if hardirqs are
2598     * enabled too:
2599     */
2600    if (curr->hardirqs_enabled)
2601        mark_held_locks(curr, SOFTIRQ);
2602}
2603
2604/*
2605 * Softirqs were disabled:
2606 */
2607void trace_softirqs_off(unsigned long ip)
2608{
2609    struct task_struct *curr = current;
2610
2611    if (unlikely(!debug_locks))
2612        return;
2613
2614    if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2615        return;
2616
2617    if (curr->softirqs_enabled) {
2618        /*
2619         * We have done an ON -> OFF transition:
2620         */
2621        curr->softirqs_enabled = 0;
2622        curr->softirq_disable_ip = ip;
2623        curr->softirq_disable_event = ++curr->irq_events;
2624        debug_atomic_inc(softirqs_off_events);
2625        DEBUG_LOCKS_WARN_ON(!softirq_count());
2626    } else
2627        debug_atomic_inc(redundant_softirqs_off);
2628}
2629
2630static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2631{
2632    struct task_struct *curr = current;
2633
2634    if (unlikely(!debug_locks))
2635        return;
2636
2637    /* no reclaim without waiting on it */
2638    if (!(gfp_mask & __GFP_WAIT))
2639        return;
2640
2641    /* this guy won't enter reclaim */
2642    if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2643        return;
2644
2645    /* We're only interested __GFP_FS allocations for now */
2646    if (!(gfp_mask & __GFP_FS))
2647        return;
2648
2649    if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2650        return;
2651
2652    mark_held_locks(curr, RECLAIM_FS);
2653}
2654
2655static void check_flags(unsigned long flags);
2656
2657void lockdep_trace_alloc(gfp_t gfp_mask)
2658{
2659    unsigned long flags;
2660
2661    if (unlikely(current->lockdep_recursion))
2662        return;
2663
2664    raw_local_irq_save(flags);
2665    check_flags(flags);
2666    current->lockdep_recursion = 1;
2667    __lockdep_trace_alloc(gfp_mask, flags);
2668    current->lockdep_recursion = 0;
2669    raw_local_irq_restore(flags);
2670}
2671
2672static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2673{
2674    /*
2675     * If non-trylock use in a hardirq or softirq context, then
2676     * mark the lock as used in these contexts:
2677     */
2678    if (!hlock->trylock) {
2679        if (hlock->read) {
2680            if (curr->hardirq_context)
2681                if (!mark_lock(curr, hlock,
2682                        LOCK_USED_IN_HARDIRQ_READ))
2683                    return 0;
2684            if (curr->softirq_context)
2685                if (!mark_lock(curr, hlock,
2686                        LOCK_USED_IN_SOFTIRQ_READ))
2687                    return 0;
2688        } else {
2689            if (curr->hardirq_context)
2690                if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2691                    return 0;
2692            if (curr->softirq_context)
2693                if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2694                    return 0;
2695        }
2696    }
2697    if (!hlock->hardirqs_off) {
2698        if (hlock->read) {
2699            if (!mark_lock(curr, hlock,
2700                    LOCK_ENABLED_HARDIRQ_READ))
2701                return 0;
2702            if (curr->softirqs_enabled)
2703                if (!mark_lock(curr, hlock,
2704                        LOCK_ENABLED_SOFTIRQ_READ))
2705                    return 0;
2706        } else {
2707            if (!mark_lock(curr, hlock,
2708                    LOCK_ENABLED_HARDIRQ))
2709                return 0;
2710            if (curr->softirqs_enabled)
2711                if (!mark_lock(curr, hlock,
2712                        LOCK_ENABLED_SOFTIRQ))
2713                    return 0;
2714        }
2715    }
2716
2717    /*
2718     * We reuse the irq context infrastructure more broadly as a general
2719     * context checking code. This tests GFP_FS recursion (a lock taken
2720     * during reclaim for a GFP_FS allocation is held over a GFP_FS
2721     * allocation).
2722     */
2723    if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2724        if (hlock->read) {
2725            if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2726                    return 0;
2727        } else {
2728            if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2729                    return 0;
2730        }
2731    }
2732
2733    return 1;
2734}
2735
2736static int separate_irq_context(struct task_struct *curr,
2737        struct held_lock *hlock)
2738{
2739    unsigned int depth = curr->lockdep_depth;
2740
2741    /*
2742     * Keep track of points where we cross into an interrupt context:
2743     */
2744    hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2745                curr->softirq_context;
2746    if (depth) {
2747        struct held_lock *prev_hlock;
2748
2749        prev_hlock = curr->held_locks + depth-1;
2750        /*
2751         * If we cross into another context, reset the
2752         * hash key (this also prevents the checking and the
2753         * adding of the dependency to 'prev'):
2754         */
2755        if (prev_hlock->irq_context != hlock->irq_context)
2756            return 1;
2757    }
2758    return 0;
2759}
2760
2761#else
2762
2763static inline
2764int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2765        enum lock_usage_bit new_bit)
2766{
2767    WARN_ON(1);
2768    return 1;
2769}
2770
2771static inline int mark_irqflags(struct task_struct *curr,
2772        struct held_lock *hlock)
2773{
2774    return 1;
2775}
2776
2777static inline int separate_irq_context(struct task_struct *curr,
2778        struct held_lock *hlock)
2779{
2780    return 0;
2781}
2782
2783void lockdep_trace_alloc(gfp_t gfp_mask)
2784{
2785}
2786
2787#endif
2788
2789/*
2790 * Mark a lock with a usage bit, and validate the state transition:
2791 */
2792static int mark_lock(struct task_struct *curr, struct held_lock *this,
2793                 enum lock_usage_bit new_bit)
2794{
2795    unsigned int new_mask = 1 << new_bit, ret = 1;
2796
2797    /*
2798     * If already set then do not dirty the cacheline,
2799     * nor do any checks:
2800     */
2801    if (likely(hlock_class(this)->usage_mask & new_mask))
2802        return 1;
2803
2804    if (!graph_lock())
2805        return 0;
2806    /*
2807     * Make sure we didn't race:
2808     */
2809    if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2810        graph_unlock();
2811        return 1;
2812    }
2813
2814    hlock_class(this)->usage_mask |= new_mask;
2815
2816    if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2817        return 0;
2818
2819    switch (new_bit) {
2820#define LOCKDEP_STATE(__STATE) \
2821    case LOCK_USED_IN_##__STATE: \
2822    case LOCK_USED_IN_##__STATE##_READ: \
2823    case LOCK_ENABLED_##__STATE: \
2824    case LOCK_ENABLED_##__STATE##_READ:
2825#include "lockdep_states.h"
2826#undef LOCKDEP_STATE
2827        ret = mark_lock_irq(curr, this, new_bit);
2828        if (!ret)
2829            return 0;
2830        break;
2831    case LOCK_USED:
2832        debug_atomic_dec(nr_unused_locks);
2833        break;
2834    default:
2835        if (!debug_locks_off_graph_unlock())
2836            return 0;
2837        WARN_ON(1);
2838        return 0;
2839    }
2840
2841    graph_unlock();
2842
2843    /*
2844     * We must printk outside of the graph_lock:
2845     */
2846    if (ret == 2) {
2847        printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2848        print_lock(this);
2849        print_irqtrace_events(curr);
2850        dump_stack();
2851    }
2852
2853    return ret;
2854}
2855
2856/*
2857 * Initialize a lock instance's lock-class mapping info:
2858 */
2859void lockdep_init_map(struct lockdep_map *lock, const char *name,
2860              struct lock_class_key *key, int subclass)
2861{
2862    int i;
2863
2864    for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2865        lock->class_cache[i] = NULL;
2866
2867#ifdef CONFIG_LOCK_STAT
2868    lock->cpu = raw_smp_processor_id();
2869#endif
2870
2871    if (DEBUG_LOCKS_WARN_ON(!name)) {
2872        lock->name = "NULL";
2873        return;
2874    }
2875
2876    lock->name = name;
2877
2878    if (DEBUG_LOCKS_WARN_ON(!key))
2879        return;
2880    /*
2881     * Sanity check, the lock-class key must be persistent:
2882     */
2883    if (!static_obj(key)) {
2884        printk("BUG: key %p not in .data!\n", key);
2885        DEBUG_LOCKS_WARN_ON(1);
2886        return;
2887    }
2888    lock->key = key;
2889
2890    if (unlikely(!debug_locks))
2891        return;
2892
2893    if (subclass)
2894        register_lock_class(lock, subclass, 1);
2895}
2896EXPORT_SYMBOL_GPL(lockdep_init_map);
2897
2898struct lock_class_key __lockdep_no_validate__;
2899
2900/*
2901 * This gets called for every mutex_lock*()/spin_lock*() operation.
2902 * We maintain the dependency maps and validate the locking attempt:
2903 */
2904static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2905              int trylock, int read, int check, int hardirqs_off,
2906              struct lockdep_map *nest_lock, unsigned long ip,
2907              int references)
2908{
2909    struct task_struct *curr = current;
2910    struct lock_class *class = NULL;
2911    struct held_lock *hlock;
2912    unsigned int depth, id;
2913    int chain_head = 0;
2914    int class_idx;
2915    u64 chain_key;
2916
2917    if (!prove_locking)
2918        check = 1;
2919
2920    if (unlikely(!debug_locks))
2921        return 0;
2922
2923    if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2924        return 0;
2925
2926    if (lock->key == &__lockdep_no_validate__)
2927        check = 1;
2928
2929    if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2930        class = lock->class_cache[subclass];
2931    /*
2932     * Not cached?
2933     */
2934    if (unlikely(!class)) {
2935        class = register_lock_class(lock, subclass, 0);
2936        if (!class)
2937            return 0;
2938    }
2939    atomic_inc((atomic_t *)&class->ops);
2940    if (very_verbose(class)) {
2941        printk("\nacquire class [%p] %s", class->key, class->name);
2942        if (class->name_version > 1)
2943            printk("#%d", class->name_version);
2944        printk("\n");
2945        dump_stack();
2946    }
2947
2948    /*
2949     * Add the lock to the list of currently held locks.
2950     * (we dont increase the depth just yet, up until the
2951     * dependency checks are done)
2952     */
2953    depth = curr->lockdep_depth;
2954    if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2955        return 0;
2956
2957    class_idx = class - lock_classes + 1;
2958
2959    if (depth) {
2960        hlock = curr->held_locks + depth - 1;
2961        if (hlock->class_idx == class_idx && nest_lock) {
2962            if (hlock->references)
2963                hlock->references++;
2964            else
2965                hlock->references = 2;
2966
2967            return 1;
2968        }
2969    }
2970
2971    hlock = curr->held_locks + depth;
2972    if (DEBUG_LOCKS_WARN_ON(!class))
2973        return 0;
2974    hlock->class_idx = class_idx;
2975    hlock->acquire_ip = ip;
2976    hlock->instance = lock;
2977    hlock->nest_lock = nest_lock;
2978    hlock->trylock = trylock;
2979    hlock->read = read;
2980    hlock->check = check;
2981    hlock->hardirqs_off = !!hardirqs_off;
2982    hlock->references = references;
2983#ifdef CONFIG_LOCK_STAT
2984    hlock->waittime_stamp = 0;
2985    hlock->holdtime_stamp = lockstat_clock();
2986#endif
2987
2988    if (check == 2 && !mark_irqflags(curr, hlock))
2989        return 0;
2990
2991    /* mark it as used: */
2992    if (!mark_lock(curr, hlock, LOCK_USED))
2993        return 0;
2994
2995    /*
2996     * Calculate the chain hash: it's the combined hash of all the
2997     * lock keys along the dependency chain. We save the hash value
2998     * at every step so that we can get the current hash easily
2999     * after unlock. The chain hash is then used to cache dependency
3000     * results.
3001     *
3002     * The 'key ID' is what is the most compact key value to drive
3003     * the hash, not class->key.
3004     */
3005    id = class - lock_classes;
3006    if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3007        return 0;
3008
3009    chain_key = curr->curr_chain_key;
3010    if (!depth) {
3011        if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3012            return 0;
3013        chain_head = 1;
3014    }
3015
3016    hlock->prev_chain_key = chain_key;
3017    if (separate_irq_context(curr, hlock)) {
3018        chain_key = 0;
3019        chain_head = 1;
3020    }
3021    chain_key = iterate_chain_key(chain_key, id);
3022
3023    if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3024        return 0;
3025
3026    curr->curr_chain_key = chain_key;
3027    curr->lockdep_depth++;
3028    check_chain_key(curr);
3029#ifdef CONFIG_DEBUG_LOCKDEP
3030    if (unlikely(!debug_locks))
3031        return 0;
3032#endif
3033    if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3034        debug_locks_off();
3035        printk("BUG: MAX_LOCK_DEPTH too low!\n");
3036        printk("turning off the locking correctness validator.\n");
3037        dump_stack();
3038        return 0;
3039    }
3040
3041    if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3042        max_lockdep_depth = curr->lockdep_depth;
3043
3044    return 1;
3045}
3046
3047static int
3048print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3049               unsigned long ip)
3050{
3051    if (!debug_locks_off())
3052        return 0;
3053    if (debug_locks_silent)
3054        return 0;
3055
3056    printk("\n=====================================\n");
3057    printk( "[ BUG: bad unlock balance detected! ]\n");
3058    printk( "-------------------------------------\n");
3059    printk("%s/%d is trying to release lock (",
3060        curr->comm, task_pid_nr(curr));
3061    print_lockdep_cache(lock);
3062    printk(") at:\n");
3063    print_ip_sym(ip);
3064    printk("but there are no more locks to release!\n");
3065    printk("\nother info that might help us debug this:\n");
3066    lockdep_print_held_locks(curr);
3067
3068    printk("\nstack backtrace:\n");
3069    dump_stack();
3070
3071    return 0;
3072}
3073
3074/*
3075 * Common debugging checks for both nested and non-nested unlock:
3076 */
3077static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3078            unsigned long ip)
3079{
3080    if (unlikely(!debug_locks))
3081        return 0;
3082    if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3083        return 0;
3084
3085    if (curr->lockdep_depth <= 0)
3086        return print_unlock_inbalance_bug(curr, lock, ip);
3087
3088    return 1;
3089}
3090
3091static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3092{
3093    if (hlock->instance == lock)
3094        return 1;
3095
3096    if (hlock->references) {
3097        struct lock_class *class = lock->class_cache[0];
3098
3099        if (!class)
3100            class = look_up_lock_class(lock, 0);
3101
3102        if (DEBUG_LOCKS_WARN_ON(!class))
3103            return 0;
3104
3105        if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3106            return 0;
3107
3108        if (hlock->class_idx == class - lock_classes + 1)
3109            return 1;
3110    }
3111
3112    return 0;
3113}
3114
3115static int
3116__lock_set_class(struct lockdep_map *lock, const char *name,
3117         struct lock_class_key *key, unsigned int subclass,
3118         unsigned long ip)
3119{
3120    struct task_struct *curr = current;
3121    struct held_lock *hlock, *prev_hlock;
3122    struct lock_class *class;
3123    unsigned int depth;
3124    int i;
3125
3126    depth = curr->lockdep_depth;
3127    if (DEBUG_LOCKS_WARN_ON(!depth))
3128        return 0;
3129
3130    prev_hlock = NULL;
3131    for (i = depth-1; i >= 0; i--) {
3132        hlock = curr->held_locks + i;
3133        /*
3134         * We must not cross into another context:
3135         */
3136        if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3137            break;
3138        if (match_held_lock(hlock, lock))
3139            goto found_it;
3140        prev_hlock = hlock;
3141    }
3142    return print_unlock_inbalance_bug(curr, lock, ip);
3143
3144found_it:
3145    lockdep_init_map(lock, name, key, 0);
3146    class = register_lock_class(lock, subclass, 0);
3147    hlock->class_idx = class - lock_classes + 1;
3148
3149    curr->lockdep_depth = i;
3150    curr->curr_chain_key = hlock->prev_chain_key;
3151
3152    for (; i < depth; i++) {
3153        hlock = curr->held_locks + i;
3154        if (!__lock_acquire(hlock->instance,
3155            hlock_class(hlock)->subclass, hlock->trylock,
3156                hlock->read, hlock->check, hlock->hardirqs_off,
3157                hlock->nest_lock, hlock->acquire_ip,
3158                hlock->references))
3159            return 0;
3160    }
3161
3162    if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3163        return 0;
3164    return 1;
3165}
3166
3167/*
3168 * Remove the lock to the list of currently held locks in a
3169 * potentially non-nested (out of order) manner. This is a
3170 * relatively rare operation, as all the unlock APIs default
3171 * to nested mode (which uses lock_release()):
3172 */
3173static int
3174lock_release_non_nested(struct task_struct *curr,
3175            struct lockdep_map *lock, unsigned long ip)
3176{
3177    struct held_lock *hlock, *prev_hlock;
3178    unsigned int depth;
3179    int i;
3180
3181    /*
3182     * Check whether the lock exists in the current stack
3183     * of held locks:
3184     */
3185    depth = curr->lockdep_depth;
3186    if (DEBUG_LOCKS_WARN_ON(!depth))
3187        return 0;
3188
3189    prev_hlock = NULL;
3190    for (i = depth-1; i >= 0; i--) {
3191        hlock = curr->held_locks + i;
3192        /*
3193         * We must not cross into another context:
3194         */
3195        if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3196            break;
3197        if (match_held_lock(hlock, lock))
3198            goto found_it;
3199        prev_hlock = hlock;
3200    }
3201    return print_unlock_inbalance_bug(curr, lock, ip);
3202
3203found_it:
3204    if (hlock->instance == lock)
3205        lock_release_holdtime(hlock);
3206
3207    if (hlock->references) {
3208        hlock->references--;
3209        if (hlock->references) {
3210            /*
3211             * We had, and after removing one, still have
3212             * references, the current lock stack is still
3213             * valid. We're done!
3214             */
3215            return 1;
3216        }
3217    }
3218
3219    /*
3220     * We have the right lock to unlock, 'hlock' points to it.
3221     * Now we remove it from the stack, and add back the other
3222     * entries (if any), recalculating the hash along the way:
3223     */
3224
3225    curr->lockdep_depth = i;
3226    curr->curr_chain_key = hlock->prev_chain_key;
3227
3228    for (i++; i < depth; i++) {
3229        hlock = curr->held_locks + i;
3230        if (!__lock_acquire(hlock->instance,
3231            hlock_class(hlock)->subclass, hlock->trylock,
3232                hlock->read, hlock->check, hlock->hardirqs_off,
3233                hlock->nest_lock, hlock->acquire_ip,
3234                hlock->references))
3235            return 0;
3236    }
3237
3238    if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3239        return 0;
3240    return 1;
3241}
3242
3243/*
3244 * Remove the lock to the list of currently held locks - this gets
3245 * called on mutex_unlock()/spin_unlock*() (or on a failed
3246 * mutex_lock_interruptible()). This is done for unlocks that nest
3247 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3248 */
3249static int lock_release_nested(struct task_struct *curr,
3250                   struct lockdep_map *lock, unsigned long ip)
3251{
3252    struct held_lock *hlock;
3253    unsigned int depth;
3254
3255    /*
3256     * Pop off the top of the lock stack:
3257     */
3258    depth = curr->lockdep_depth - 1;
3259    hlock = curr->held_locks + depth;
3260
3261    /*
3262     * Is the unlock non-nested:
3263     */
3264    if (hlock->instance != lock || hlock->references)
3265        return lock_release_non_nested(curr, lock, ip);
3266    curr->lockdep_depth--;
3267
3268    if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3269        return 0;
3270
3271    curr->curr_chain_key = hlock->prev_chain_key;
3272
3273    lock_release_holdtime(hlock);
3274
3275#ifdef CONFIG_DEBUG_LOCKDEP
3276    hlock->prev_chain_key = 0;
3277    hlock->class_idx = 0;
3278    hlock->acquire_ip = 0;
3279    hlock->irq_context = 0;
3280#endif
3281    return 1;
3282}
3283
3284/*
3285 * Remove the lock to the list of currently held locks - this gets
3286 * called on mutex_unlock()/spin_unlock*() (or on a failed
3287 * mutex_lock_interruptible()). This is done for unlocks that nest
3288 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3289 */
3290static void
3291__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3292{
3293    struct task_struct *curr = current;
3294
3295    if (!check_unlock(curr, lock, ip))
3296        return;
3297
3298    if (nested) {
3299        if (!lock_release_nested(curr, lock, ip))
3300            return;
3301    } else {
3302        if (!lock_release_non_nested(curr, lock, ip))
3303            return;
3304    }
3305
3306    check_chain_key(curr);
3307}
3308
3309static int __lock_is_held(struct lockdep_map *lock)
3310{
3311    struct task_struct *curr = current;
3312    int i;
3313
3314    for (i = 0; i < curr->lockdep_depth; i++) {
3315        struct held_lock *hlock = curr->held_locks + i;
3316
3317        if (match_held_lock(hlock, lock))
3318            return 1;
3319    }
3320
3321    return 0;
3322}
3323
3324/*
3325 * Check whether we follow the irq-flags state precisely:
3326 */
3327static void check_flags(unsigned long flags)
3328{
3329#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3330    defined(CONFIG_TRACE_IRQFLAGS)
3331    if (!debug_locks)
3332        return;
3333
3334    if (irqs_disabled_flags(flags)) {
3335        if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3336            printk("possible reason: unannotated irqs-off.\n");
3337        }
3338    } else {
3339        if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3340            printk("possible reason: unannotated irqs-on.\n");
3341        }
3342    }
3343
3344    /*
3345     * We dont accurately track softirq state in e.g.
3346     * hardirq contexts (such as on 4KSTACKS), so only
3347     * check if not in hardirq contexts:
3348     */
3349    if (!hardirq_count()) {
3350        if (softirq_count())
3351            DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3352        else
3353            DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3354    }
3355
3356    if (!debug_locks)
3357        print_irqtrace_events(current);
3358#endif
3359}
3360
3361void lock_set_class(struct lockdep_map *lock, const char *name,
3362            struct lock_class_key *key, unsigned int subclass,
3363            unsigned long ip)
3364{
3365    unsigned long flags;
3366
3367    if (unlikely(current->lockdep_recursion))
3368        return;
3369
3370    raw_local_irq_save(flags);
3371    current->lockdep_recursion = 1;
3372    check_flags(flags);
3373    if (__lock_set_class(lock, name, key, subclass, ip))
3374        check_chain_key(current);
3375    current->lockdep_recursion = 0;
3376    raw_local_irq_restore(flags);
3377}
3378EXPORT_SYMBOL_GPL(lock_set_class);
3379
3380/*
3381 * We are not always called with irqs disabled - do that here,
3382 * and also avoid lockdep recursion:
3383 */
3384void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3385              int trylock, int read, int check,
3386              struct lockdep_map *nest_lock, unsigned long ip)
3387{
3388    unsigned long flags;
3389
3390    if (unlikely(current->lockdep_recursion))
3391        return;
3392
3393    raw_local_irq_save(flags);
3394    check_flags(flags);
3395
3396    current->lockdep_recursion = 1;
3397    trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3398    __lock_acquire(lock, subclass, trylock, read, check,
3399               irqs_disabled_flags(flags), nest_lock, ip, 0);
3400    current->lockdep_recursion = 0;
3401    raw_local_irq_restore(flags);
3402}
3403EXPORT_SYMBOL_GPL(lock_acquire);
3404
3405void lock_release(struct lockdep_map *lock, int nested,
3406              unsigned long ip)
3407{
3408    unsigned long flags;
3409
3410    if (unlikely(current->lockdep_recursion))
3411        return;
3412
3413    raw_local_irq_save(flags);
3414    check_flags(flags);
3415    current->lockdep_recursion = 1;
3416    trace_lock_release(lock, ip);
3417    __lock_release(lock, nested, ip);
3418    current->lockdep_recursion = 0;
3419    raw_local_irq_restore(flags);
3420}
3421EXPORT_SYMBOL_GPL(lock_release);
3422
3423int lock_is_held(struct lockdep_map *lock)
3424{
3425    unsigned long flags;
3426    int ret = 0;
3427
3428    if (unlikely(current->lockdep_recursion))
3429        return 1; /* avoid false negative lockdep_assert_held() */
3430
3431    raw_local_irq_save(flags);
3432    check_flags(flags);
3433
3434    current->lockdep_recursion = 1;
3435    ret = __lock_is_held(lock);
3436    current->lockdep_recursion = 0;
3437    raw_local_irq_restore(flags);
3438
3439    return ret;
3440}
3441EXPORT_SYMBOL_GPL(lock_is_held);
3442
3443void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3444{
3445    current->lockdep_reclaim_gfp = gfp_mask;
3446}
3447
3448void lockdep_clear_current_reclaim_state(void)
3449{
3450    current->lockdep_reclaim_gfp = 0;
3451}
3452
3453#ifdef CONFIG_LOCK_STAT
3454static int
3455print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3456               unsigned long ip)
3457{
3458    if (!debug_locks_off())
3459        return 0;
3460    if (debug_locks_silent)
3461        return 0;
3462
3463    printk("\n=================================\n");
3464    printk( "[ BUG: bad contention detected! ]\n");
3465    printk( "---------------------------------\n");
3466    printk("%s/%d is trying to contend lock (",
3467        curr->comm, task_pid_nr(curr));
3468    print_lockdep_cache(lock);
3469    printk(") at:\n");
3470    print_ip_sym(ip);
3471    printk("but there are no locks held!\n");
3472    printk("\nother info that might help us debug this:\n");
3473    lockdep_print_held_locks(curr);
3474
3475    printk("\nstack backtrace:\n");
3476    dump_stack();
3477
3478    return 0;
3479}
3480
3481static void
3482__lock_contended(struct lockdep_map *lock, unsigned long ip)
3483{
3484    struct task_struct *curr = current;
3485    struct held_lock *hlock, *prev_hlock;
3486    struct lock_class_stats *stats;
3487    unsigned int depth;
3488    int i, contention_point, contending_point;
3489
3490    depth = curr->lockdep_depth;
3491    if (DEBUG_LOCKS_WARN_ON(!depth))
3492        return;
3493
3494    prev_hlock = NULL;
3495    for (i = depth-1; i >= 0; i--) {
3496        hlock = curr->held_locks + i;
3497        /*
3498         * We must not cross into another context:
3499         */
3500        if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3501            break;
3502        if (match_held_lock(hlock, lock))
3503            goto found_it;
3504        prev_hlock = hlock;
3505    }
3506    print_lock_contention_bug(curr, lock, ip);
3507    return;
3508
3509found_it:
3510    if (hlock->instance != lock)
3511        return;
3512
3513    hlock->waittime_stamp = lockstat_clock();
3514
3515    contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3516    contending_point = lock_point(hlock_class(hlock)->contending_point,
3517                      lock->ip);
3518
3519    stats = get_lock_stats(hlock_class(hlock));
3520    if (contention_point < LOCKSTAT_POINTS)
3521        stats->contention_point[contention_point]++;
3522    if (contending_point < LOCKSTAT_POINTS)
3523        stats->contending_point[contending_point]++;
3524    if (lock->cpu != smp_processor_id())
3525        stats->bounces[bounce_contended + !!hlock->read]++;
3526    put_lock_stats(stats);
3527}
3528
3529static void
3530__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3531{
3532    struct task_struct *curr = current;
3533    struct held_lock *hlock, *prev_hlock;
3534    struct lock_class_stats *stats;
3535    unsigned int depth;
3536    u64 now, waittime = 0;
3537    int i, cpu;
3538
3539    depth = curr->lockdep_depth;
3540    if (DEBUG_LOCKS_WARN_ON(!depth))
3541        return;
3542
3543    prev_hlock = NULL;
3544    for (i = depth-1; i >= 0; i--) {
3545        hlock = curr->held_locks + i;
3546        /*
3547         * We must not cross into another context:
3548         */
3549        if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3550            break;
3551        if (match_held_lock(hlock, lock))
3552            goto found_it;
3553        prev_hlock = hlock;
3554    }
3555    print_lock_contention_bug(curr, lock, _RET_IP_);
3556    return;
3557
3558found_it:
3559    if (hlock->instance != lock)
3560        return;
3561
3562    cpu = smp_processor_id();
3563    if (hlock->waittime_stamp) {
3564        now = lockstat_clock();
3565        waittime = now - hlock->waittime_stamp;
3566        hlock->holdtime_stamp = now;
3567    }
3568
3569    trace_lock_acquired(lock, ip);
3570
3571    stats = get_lock_stats(hlock_class(hlock));
3572    if (waittime) {
3573        if (hlock->read)
3574            lock_time_inc(&stats->read_waittime, waittime);
3575        else
3576            lock_time_inc(&stats->write_waittime, waittime);
3577    }
3578    if (lock->cpu != cpu)
3579        stats->bounces[bounce_acquired + !!hlock->read]++;
3580    put_lock_stats(stats);
3581
3582    lock->cpu = cpu;
3583    lock->ip = ip;
3584}
3585
3586void lock_contended(struct lockdep_map *lock, unsigned long ip)
3587{
3588    unsigned long flags;
3589
3590    if (unlikely(!lock_stat))
3591        return;
3592
3593    if (unlikely(current->lockdep_recursion))
3594        return;
3595
3596    raw_local_irq_save(flags);
3597    check_flags(flags);
3598    current->lockdep_recursion = 1;
3599    trace_lock_contended(lock, ip);
3600    __lock_contended(lock, ip);
3601    current->lockdep_recursion = 0;
3602    raw_local_irq_restore(flags);
3603}
3604EXPORT_SYMBOL_GPL(lock_contended);
3605
3606void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3607{
3608    unsigned long flags;
3609
3610    if (unlikely(!lock_stat))
3611        return;
3612
3613    if (unlikely(current->lockdep_recursion))
3614        return;
3615
3616    raw_local_irq_save(flags);
3617    check_flags(flags);
3618    current->lockdep_recursion = 1;
3619    __lock_acquired(lock, ip);
3620    current->lockdep_recursion = 0;
3621    raw_local_irq_restore(flags);
3622}
3623EXPORT_SYMBOL_GPL(lock_acquired);
3624#endif
3625
3626/*
3627 * Used by the testsuite, sanitize the validator state
3628 * after a simulated failure:
3629 */
3630
3631void lockdep_reset(void)
3632{
3633    unsigned long flags;
3634    int i;
3635
3636    raw_local_irq_save(flags);
3637    current->curr_chain_key = 0;
3638    current->lockdep_depth = 0;
3639    current->lockdep_recursion = 0;
3640    memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3641    nr_hardirq_chains = 0;
3642    nr_softirq_chains = 0;
3643    nr_process_chains = 0;
3644    debug_locks = 1;
3645    for (i = 0; i < CHAINHASH_SIZE; i++)
3646        INIT_LIST_HEAD(chainhash_table + i);
3647    raw_local_irq_restore(flags);
3648}
3649
3650static void zap_class(struct lock_class *class)
3651{
3652    int i;
3653
3654    /*
3655     * Remove all dependencies this lock is
3656     * involved in:
3657     */
3658    for (i = 0; i < nr_list_entries; i++) {
3659        if (list_entries[i].class == class)
3660            list_del_rcu(&list_entries[i].entry);
3661    }
3662    /*
3663     * Unhash the class and remove it from the all_lock_classes list:
3664     */
3665    list_del_rcu(&class->hash_entry);
3666    list_del_rcu(&class->lock_entry);
3667
3668    class->key = NULL;
3669}
3670
3671static inline int within(const void *addr, void *start, unsigned long size)
3672{
3673    return addr >= start && addr < start + size;
3674}
3675
3676void lockdep_free_key_range(void *start, unsigned long size)
3677{
3678    struct lock_class *class, *next;
3679    struct list_head *head;
3680    unsigned long flags;
3681    int i;
3682    int locked;
3683
3684    raw_local_irq_save(flags);
3685    locked = graph_lock();
3686
3687    /*
3688     * Unhash all classes that were created by this module:
3689     */
3690    for (i = 0; i < CLASSHASH_SIZE; i++) {
3691        head = classhash_table + i;
3692        if (list_empty(head))
3693            continue;
3694        list_for_each_entry_safe(class, next, head, hash_entry) {
3695            if (within(class->key, start, size))
3696                zap_class(class);
3697            else if (within(class->name, start, size))
3698                zap_class(class);
3699        }
3700    }
3701
3702    if (locked)
3703        graph_unlock();
3704    raw_local_irq_restore(flags);
3705}
3706
3707void lockdep_reset_lock(struct lockdep_map *lock)
3708{
3709    struct lock_class *class, *next;
3710    struct list_head *head;
3711    unsigned long flags;
3712    int i, j;
3713    int locked;
3714
3715    raw_local_irq_save(flags);
3716
3717    /*
3718     * Remove all classes this lock might have:
3719     */
3720    for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3721        /*
3722         * If the class exists we look it up and zap it:
3723         */
3724        class = look_up_lock_class(lock, j);
3725        if (class)
3726            zap_class(class);
3727    }
3728    /*
3729     * Debug check: in the end all mapped classes should
3730     * be gone.
3731     */
3732    locked = graph_lock();
3733    for (i = 0; i < CLASSHASH_SIZE; i++) {
3734        head = classhash_table + i;
3735        if (list_empty(head))
3736            continue;
3737        list_for_each_entry_safe(class, next, head, hash_entry) {
3738            int match = 0;
3739
3740            for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3741                match |= class == lock->class_cache[j];
3742
3743            if (unlikely(match)) {
3744                if (debug_locks_off_graph_unlock())
3745                    WARN_ON(1);
3746                goto out_restore;
3747            }
3748        }
3749    }
3750    if (locked)
3751        graph_unlock();
3752
3753out_restore:
3754    raw_local_irq_restore(flags);
3755}
3756
3757void lockdep_init(void)
3758{
3759    int i;
3760
3761    /*
3762     * Some architectures have their own start_kernel()
3763     * code which calls lockdep_init(), while we also
3764     * call lockdep_init() from the start_kernel() itself,
3765     * and we want to initialize the hashes only once:
3766     */
3767    if (lockdep_initialized)
3768        return;
3769
3770    for (i = 0; i < CLASSHASH_SIZE; i++)
3771        INIT_LIST_HEAD(classhash_table + i);
3772
3773    for (i = 0; i < CHAINHASH_SIZE; i++)
3774        INIT_LIST_HEAD(chainhash_table + i);
3775
3776    lockdep_initialized = 1;
3777}
3778
3779void __init lockdep_info(void)
3780{
3781    printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3782
3783    printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3784    printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3785    printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3786    printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3787    printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3788    printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3789    printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3790
3791    printk(" memory used by lock dependency info: %lu kB\n",
3792        (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3793        sizeof(struct list_head) * CLASSHASH_SIZE +
3794        sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3795        sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3796        sizeof(struct list_head) * CHAINHASH_SIZE
3797#ifdef CONFIG_PROVE_LOCKING
3798        + sizeof(struct circular_queue)
3799#endif
3800        ) / 1024
3801        );
3802
3803    printk(" per task-struct memory footprint: %lu bytes\n",
3804        sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3805
3806#ifdef CONFIG_DEBUG_LOCKDEP
3807    if (lockdep_init_error) {
3808        printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3809        printk("Call stack leading to lockdep invocation was:\n");
3810        print_stack_trace(&lockdep_init_trace, 0);
3811    }
3812#endif
3813}
3814
3815static void
3816print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3817             const void *mem_to, struct held_lock *hlock)
3818{
3819    if (!debug_locks_off())
3820        return;
3821    if (debug_locks_silent)
3822        return;
3823
3824    printk("\n=========================\n");
3825    printk( "[ BUG: held lock freed! ]\n");
3826    printk( "-------------------------\n");
3827    printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3828        curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3829    print_lock(hlock);
3830    lockdep_print_held_locks(curr);
3831
3832    printk("\nstack backtrace:\n");
3833    dump_stack();
3834}
3835
3836static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3837                const void* lock_from, unsigned long lock_len)
3838{
3839    return lock_from + lock_len <= mem_from ||
3840        mem_from + mem_len <= lock_from;
3841}
3842
3843/*
3844 * Called when kernel memory is freed (or unmapped), or if a lock
3845 * is destroyed or reinitialized - this code checks whether there is
3846 * any held lock in the memory range of <from> to <to>:
3847 */
3848void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3849{
3850    struct task_struct *curr = current;
3851    struct held_lock *hlock;
3852    unsigned long flags;
3853    int i;
3854
3855    if (unlikely(!debug_locks))
3856        return;
3857
3858    local_irq_save(flags);
3859    for (i = 0; i < curr->lockdep_depth; i++) {
3860        hlock = curr->held_locks + i;
3861
3862        if (not_in_range(mem_from, mem_len, hlock->instance,
3863                    sizeof(*hlock->instance)))
3864            continue;
3865
3866        print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3867        break;
3868    }
3869    local_irq_restore(flags);
3870}
3871EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3872
3873static void print_held_locks_bug(struct task_struct *curr)
3874{
3875    if (!debug_locks_off())
3876        return;
3877    if (debug_locks_silent)
3878        return;
3879
3880    printk("\n=====================================\n");
3881    printk( "[ BUG: lock held at task exit time! ]\n");
3882    printk( "-------------------------------------\n");
3883    printk("%s/%d is exiting with locks still held!\n",
3884        curr->comm, task_pid_nr(curr));
3885    lockdep_print_held_locks(curr);
3886
3887    printk("\nstack backtrace:\n");
3888    dump_stack();
3889}
3890
3891void debug_check_no_locks_held(struct task_struct *task)
3892{
3893    if (unlikely(task->lockdep_depth > 0))
3894        print_held_locks_bug(task);
3895}
3896
3897void debug_show_all_locks(void)
3898{
3899    struct task_struct *g, *p;
3900    int count = 10;
3901    int unlock = 1;
3902
3903    if (unlikely(!debug_locks)) {
3904        printk("INFO: lockdep is turned off.\n");
3905        return;
3906    }
3907    printk("\nShowing all locks held in the system:\n");
3908
3909    /*
3910     * Here we try to get the tasklist_lock as hard as possible,
3911     * if not successful after 2 seconds we ignore it (but keep
3912     * trying). This is to enable a debug printout even if a
3913     * tasklist_lock-holding task deadlocks or crashes.
3914     */
3915retry:
3916    if (!read_trylock(&tasklist_lock)) {
3917        if (count == 10)
3918            printk("hm, tasklist_lock locked, retrying... ");
3919        if (count) {
3920            count--;
3921            printk(" #%d", 10-count);
3922            mdelay(200);
3923            goto retry;
3924        }
3925        printk(" ignoring it.\n");
3926        unlock = 0;
3927    } else {
3928        if (count != 10)
3929            printk(KERN_CONT " locked it.\n");
3930    }
3931
3932    do_each_thread(g, p) {
3933        /*
3934         * It's not reliable to print a task's held locks
3935         * if it's not sleeping (or if it's not the current
3936         * task):
3937         */
3938        if (p->state == TASK_RUNNING && p != current)
3939            continue;
3940        if (p->lockdep_depth)
3941            lockdep_print_held_locks(p);
3942        if (!unlock)
3943            if (read_trylock(&tasklist_lock))
3944                unlock = 1;
3945    } while_each_thread(g, p);
3946
3947    printk("\n");
3948    printk("=============================================\n\n");
3949
3950    if (unlock)
3951        read_unlock(&tasklist_lock);
3952}
3953EXPORT_SYMBOL_GPL(debug_show_all_locks);
3954
3955/*
3956 * Careful: only use this function if you are sure that
3957 * the task cannot run in parallel!
3958 */
3959void debug_show_held_locks(struct task_struct *task)
3960{
3961    if (unlikely(!debug_locks)) {
3962        printk("INFO: lockdep is turned off.\n");
3963        return;
3964    }
3965    lockdep_print_held_locks(task);
3966}
3967EXPORT_SYMBOL_GPL(debug_show_held_locks);
3968
3969void lockdep_sys_exit(void)
3970{
3971    struct task_struct *curr = current;
3972
3973    if (unlikely(curr->lockdep_depth)) {
3974        if (!debug_locks_off())
3975            return;
3976        printk("\n================================================\n");
3977        printk( "[ BUG: lock held when returning to user space! ]\n");
3978        printk( "------------------------------------------------\n");
3979        printk("%s/%d is leaving the kernel with locks still held!\n",
3980                curr->comm, curr->pid);
3981        lockdep_print_held_locks(curr);
3982    }
3983}
3984
3985void lockdep_rcu_dereference(const char *file, const int line)
3986{
3987    struct task_struct *curr = current;
3988
3989#ifndef CONFIG_PROVE_RCU_REPEATEDLY
3990    if (!debug_locks_off())
3991        return;
3992#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
3993    /* Note: the following can be executed concurrently, so be careful. */
3994    printk("\n===================================================\n");
3995    printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3996    printk( "---------------------------------------------------\n");
3997    printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3998            file, line);
3999    printk("\nother info that might help us debug this:\n\n");
4000    printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
4001    lockdep_print_held_locks(curr);
4002    printk("\nstack backtrace:\n");
4003    dump_stack();
4004}
4005EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);
4006

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