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TOMOYO Linux Cross Reference
Linux/kernel/lockdep.c

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  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
 56 int prove_locking = 1;
 57 module_param(prove_locking, int, 0644);
 58 #else
 59 #define prove_locking 0
 60 #endif
 61 
 62 #ifdef CONFIG_LOCK_STAT
 63 int lock_stat = 1;
 64 module_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  */
 77 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 78 
 79 static 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 
 97 static 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  */
111 static 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 
120 static int lockdep_initialized;
121 
122 unsigned long nr_list_entries;
123 static 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  */
131 unsigned long nr_lock_classes;
132 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133 
134 static 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
144 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
145                       cpu_lock_stats);
146 
147 static inline u64 lockstat_clock(void)
148 {
149         return local_clock();
150 }
151 
152 static 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 
168 static 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 
180 static 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 
195 struct 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 
224 void 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 
238 static 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 
243 static void put_lock_stats(struct lock_class_stats *stats)
244 {
245         put_cpu_var(cpu_lock_stats);
246 }
247 
248 static 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
266 static 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  */
276 LIST_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 
286 static 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 
297 static 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 
310 void lockdep_off(void)
311 {
312         current->lockdep_recursion++;
313 }
314 EXPORT_SYMBOL(lockdep_off);
315 
316 void lockdep_on(void)
317 {
318         current->lockdep_recursion--;
319 }
320 EXPORT_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  */
343 static 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 
359 static 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  */
371 unsigned long nr_stack_trace_entries;
372 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
373 
374 static 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 
413 unsigned int nr_hardirq_chains;
414 unsigned int nr_softirq_chains;
415 unsigned int nr_process_chains;
416 unsigned 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  */
424 static int lockdep_init_error;
425 static unsigned long lockdep_init_trace_data[20];
426 static 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  */
434 DEFINE_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 
447 static 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 
455 const 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 
460 static inline unsigned long lock_flag(enum lock_usage_bit bit)
461 {
462         return 1UL << bit;
463 }
464 
465 static 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 
480 void 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 
493 static 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 
505 static 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 
526 static 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 
538 static 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 
545 static 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 
562 static 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 
569 static 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  */
580 static 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  */
611 static 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  */
634 static inline struct lock_class *
635 look_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  */
703 static inline struct lock_class *
704 register_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         }
794 out_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  */
814 static 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  */
831 static 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  */
871 struct circular_queue {
872         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
873         unsigned int  front, rear;
874 };
875 
876 static struct circular_queue lock_cq;
877 
878 unsigned int max_bfs_queue_depth;
879 
880 static unsigned int lockdep_dependency_gen_id;
881 
882 static inline void __cq_init(struct circular_queue *cq)
883 {
884         cq->front = cq->rear = 0;
885         lockdep_dependency_gen_id++;
886 }
887 
888 static inline int __cq_empty(struct circular_queue *cq)
889 {
890         return (cq->front == cq->rear);
891 }
892 
893 static inline int __cq_full(struct circular_queue *cq)
894 {
895         return ((cq->rear + 1) & CQ_MASK) == cq->front;
896 }
897 
898 static 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 
908 static 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 
918 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
919 {
920         return (cq->rear - cq->front) & CQ_MASK;
921 }
922 
923 static 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 
934 static 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 
943 static inline struct lock_list *get_lock_parent(struct lock_list *child)
944 {
945         return child->parent;
946 }
947 
948 static 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 
960 static 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         }
1023 exit:
1024         return ret;
1025 }
1026 
1027 static 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 
1036 static 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  */
1055 static noinline int
1056 print_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 
1068 static void
1069 print_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  */
1122 static noinline int
1123 print_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 
1149 static inline int class_equal(struct lock_list *entry, void *data)
1150 {
1151         return entry->class == data;
1152 }
1153 
1154 static 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 
1194 static 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 
1204 static int noop_count(struct lock_list *entry, void *data)
1205 {
1206         (*(unsigned long *)data)++;
1207         return 0;
1208 }
1209 
1210 unsigned 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 }
1219 unsigned 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 
1236 unsigned 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 
1246 unsigned 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  */
1267 static noinline int
1268 check_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 
1287 static 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  */
1304 static int
1305 find_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  */
1327 static int
1328 find_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 
1340 static 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  */
1367 static void __used
1368 print_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 
1395 static void
1396 print_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 
1451 static int
1452 print_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 
1525 static int
1526 check_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 
1558 static const char *state_names[] = {
1559 #define LOCKDEP_STATE(__STATE) \
1560         __stringify(__STATE),
1561 #include "lockdep_states.h"
1562 #undef LOCKDEP_STATE
1563 };
1564 
1565 static const char *state_rnames[] = {
1566 #define LOCKDEP_STATE(__STATE) \
1567         __stringify(__STATE)"-READ",
1568 #include "lockdep_states.h"
1569 #undef LOCKDEP_STATE
1570 };
1571 
1572 static 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 
1577 static 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 
1599 static 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 
1627 static int
1628 check_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 
1640 static 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 
1654 static inline int
1655 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1656                 struct held_lock *next)
1657 {
1658         return 1;
1659 }
1660 
1661 static inline void inc_chains(void)
1662 {
1663         nr_process_chains++;
1664 }
1665 
1666 #endif
1667 
1668 static void
1669 print_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 
1688 static int
1689 print_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  */
1723 static int
1724 check_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  */
1781 static int
1782 check_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  */
1886 static int
1887 check_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;
1943 out_bug:
1944         if (!debug_locks_off_graph_unlock())
1945                 return 0;
1946 
1947         WARN_ON(1);
1948 
1949         return 0;
1950 }
1951 
1952 unsigned long nr_lock_chains;
1953 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1954 int nr_chain_hlocks;
1955 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1956 
1957 struct 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  */
1968 static 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) {
1986 cache_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 
2052 static 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
2106 static 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  */
2118 static 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 
2155 static void
2156 print_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 
2173 static int
2174 print_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  */
2214 static inline int
2215 valid_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 
2223 static 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  */
2231 static int
2232 print_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  */
2295 static int
2296 check_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  */
2319 static int
2320 check_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 
2339 void 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 
2352 static int HARDIRQ_verbose(struct lock_class *class)
2353 {
2354 #if HARDIRQ_VERBOSE
2355         return class_filter(class);
2356 #endif
2357         return 0;
2358 }
2359 
2360 static int SOFTIRQ_verbose(struct lock_class *class)
2361 {
2362 #if SOFTIRQ_VERBOSE
2363         return class_filter(class);
2364 #endif
2365         return 0;
2366 }
2367 
2368 static 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 
2378 static 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 
2385 static 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 
2391 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2392                              enum lock_usage_bit bit, const char *name);
2393 
2394 static int
2395 mark_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 
2446 enum 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  */
2455 static int
2456 mark_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  */
2481 void 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 }
2528 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2529 
2530 void trace_hardirqs_on(void)
2531 {
2532         trace_hardirqs_on_caller(CALLER_ADDR0);
2533 }
2534 EXPORT_SYMBOL(trace_hardirqs_on);
2535 
2536 /*
2537  * Hardirqs were disabled:
2538  */
2539 void 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 }
2562 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2563 
2564 void trace_hardirqs_off(void)
2565 {
2566         trace_hardirqs_off_caller(CALLER_ADDR0);
2567 }
2568 EXPORT_SYMBOL(trace_hardirqs_off);
2569 
2570 /*
2571  * Softirqs will be enabled:
2572  */
2573 void 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  */
2607 void 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 
2630 static 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 
2655 static void check_flags(unsigned long flags);
2656 
2657 void 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 
2672 static 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 
2736 static 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 
2763 static inline
2764 int 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 
2771 static inline int mark_irqflags(struct task_struct *curr,
2772                 struct held_lock *hlock)
2773 {
2774         return 1;
2775 }
2776 
2777 static inline int separate_irq_context(struct task_struct *curr,
2778                 struct held_lock *hlock)
2779 {
2780         return 0;
2781 }
2782 
2783 void 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  */
2792 static 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  */
2859 void 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 }
2896 EXPORT_SYMBOL_GPL(lockdep_init_map);
2897 
2898 struct 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  */
2904 static 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 
3047 static int
3048 print_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  */
3077 static 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 
3091 static 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 
3115 static 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 
3144 found_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  */
3173 static int
3174 lock_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 
3203 found_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  */
3249 static 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  */
3290 static 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 
3309 static 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  */
3327 static 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 
3361 void 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 }
3378 EXPORT_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  */
3384 void 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 }
3403 EXPORT_SYMBOL_GPL(lock_acquire);
3404 
3405 void 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 }
3421 EXPORT_SYMBOL_GPL(lock_release);
3422 
3423 int 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 }
3441 EXPORT_SYMBOL_GPL(lock_is_held);
3442 
3443 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3444 {
3445         current->lockdep_reclaim_gfp = gfp_mask;
3446 }
3447 
3448 void lockdep_clear_current_reclaim_state(void)
3449 {
3450         current->lockdep_reclaim_gfp = 0;
3451 }
3452 
3453 #ifdef CONFIG_LOCK_STAT
3454 static int
3455 print_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 
3481 static 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 
3509 found_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 
3529 static 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 
3558 found_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 
3586 void 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 }
3604 EXPORT_SYMBOL_GPL(lock_contended);
3605 
3606 void 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 }
3623 EXPORT_SYMBOL_GPL(lock_acquired);
3624 #endif
3625 
3626 /*
3627  * Used by the testsuite, sanitize the validator state
3628  * after a simulated failure:
3629  */
3630 
3631 void 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 
3650 static 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 
3671 static inline int within(const void *addr, void *start, unsigned long size)
3672 {
3673         return addr >= start && addr < start + size;
3674 }
3675 
3676 void 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 
3707 void 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 
3753 out_restore:
3754         raw_local_irq_restore(flags);
3755 }
3756 
3757 void 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 
3779 void __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 
3815 static void
3816 print_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 
3836 static 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  */
3848 void 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 }
3871 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3872 
3873 static 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 
3891 void 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 
3897 void 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          */
3915 retry:
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 }
3953 EXPORT_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  */
3959 void 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 }
3967 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3968 
3969 void 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 
3985 void 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 }
4005 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);
4006 

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