~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/kernel/locking/lockdep.c

Version: ~ [ linux-5.3-rc5 ] ~ [ linux-5.2.9 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.67 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.139 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.189 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.189 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.72 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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
 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/sched/clock.h>
 32 #include <linux/sched/task.h>
 33 #include <linux/delay.h>
 34 #include <linux/module.h>
 35 #include <linux/proc_fs.h>
 36 #include <linux/seq_file.h>
 37 #include <linux/spinlock.h>
 38 #include <linux/kallsyms.h>
 39 #include <linux/interrupt.h>
 40 #include <linux/stacktrace.h>
 41 #include <linux/debug_locks.h>
 42 #include <linux/irqflags.h>
 43 #include <linux/utsname.h>
 44 #include <linux/hash.h>
 45 #include <linux/ftrace.h>
 46 #include <linux/stringify.h>
 47 #include <linux/bitops.h>
 48 #include <linux/gfp.h>
 49 #include <linux/kmemcheck.h>
 50 #include <linux/random.h>
 51 #include <linux/jhash.h>
 52 
 53 #include <asm/sections.h>
 54 
 55 #include "lockdep_internals.h"
 56 
 57 #define CREATE_TRACE_POINTS
 58 #include <trace/events/lock.h>
 59 
 60 #ifdef CONFIG_PROVE_LOCKING
 61 int prove_locking = 1;
 62 module_param(prove_locking, int, 0644);
 63 #else
 64 #define prove_locking 0
 65 #endif
 66 
 67 #ifdef CONFIG_LOCK_STAT
 68 int lock_stat = 1;
 69 module_param(lock_stat, int, 0644);
 70 #else
 71 #define lock_stat 0
 72 #endif
 73 
 74 /*
 75  * lockdep_lock: protects the lockdep graph, the hashes and the
 76  *               class/list/hash allocators.
 77  *
 78  * This is one of the rare exceptions where it's justified
 79  * to use a raw spinlock - we really dont want the spinlock
 80  * code to recurse back into the lockdep code...
 81  */
 82 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 83 
 84 static int graph_lock(void)
 85 {
 86         arch_spin_lock(&lockdep_lock);
 87         /*
 88          * Make sure that if another CPU detected a bug while
 89          * walking the graph we dont change it (while the other
 90          * CPU is busy printing out stuff with the graph lock
 91          * dropped already)
 92          */
 93         if (!debug_locks) {
 94                 arch_spin_unlock(&lockdep_lock);
 95                 return 0;
 96         }
 97         /* prevent any recursions within lockdep from causing deadlocks */
 98         current->lockdep_recursion++;
 99         return 1;
100 }
101 
102 static inline int graph_unlock(void)
103 {
104         if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
105                 /*
106                  * The lockdep graph lock isn't locked while we expect it to
107                  * be, we're confused now, bye!
108                  */
109                 return DEBUG_LOCKS_WARN_ON(1);
110         }
111 
112         current->lockdep_recursion--;
113         arch_spin_unlock(&lockdep_lock);
114         return 0;
115 }
116 
117 /*
118  * Turn lock debugging off and return with 0 if it was off already,
119  * and also release the graph lock:
120  */
121 static inline int debug_locks_off_graph_unlock(void)
122 {
123         int ret = debug_locks_off();
124 
125         arch_spin_unlock(&lockdep_lock);
126 
127         return ret;
128 }
129 
130 unsigned long nr_list_entries;
131 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
132 
133 /*
134  * All data structures here are protected by the global debug_lock.
135  *
136  * Mutex key structs only get allocated, once during bootup, and never
137  * get freed - this significantly simplifies the debugging code.
138  */
139 unsigned long nr_lock_classes;
140 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
141 
142 static inline struct lock_class *hlock_class(struct held_lock *hlock)
143 {
144         if (!hlock->class_idx) {
145                 /*
146                  * Someone passed in garbage, we give up.
147                  */
148                 DEBUG_LOCKS_WARN_ON(1);
149                 return NULL;
150         }
151         return lock_classes + hlock->class_idx - 1;
152 }
153 
154 #ifdef CONFIG_LOCK_STAT
155 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
156 
157 static inline u64 lockstat_clock(void)
158 {
159         return local_clock();
160 }
161 
162 static int lock_point(unsigned long points[], unsigned long ip)
163 {
164         int i;
165 
166         for (i = 0; i < LOCKSTAT_POINTS; i++) {
167                 if (points[i] == 0) {
168                         points[i] = ip;
169                         break;
170                 }
171                 if (points[i] == ip)
172                         break;
173         }
174 
175         return i;
176 }
177 
178 static void lock_time_inc(struct lock_time *lt, u64 time)
179 {
180         if (time > lt->max)
181                 lt->max = time;
182 
183         if (time < lt->min || !lt->nr)
184                 lt->min = time;
185 
186         lt->total += time;
187         lt->nr++;
188 }
189 
190 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
191 {
192         if (!src->nr)
193                 return;
194 
195         if (src->max > dst->max)
196                 dst->max = src->max;
197 
198         if (src->min < dst->min || !dst->nr)
199                 dst->min = src->min;
200 
201         dst->total += src->total;
202         dst->nr += src->nr;
203 }
204 
205 struct lock_class_stats lock_stats(struct lock_class *class)
206 {
207         struct lock_class_stats stats;
208         int cpu, i;
209 
210         memset(&stats, 0, sizeof(struct lock_class_stats));
211         for_each_possible_cpu(cpu) {
212                 struct lock_class_stats *pcs =
213                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
214 
215                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
216                         stats.contention_point[i] += pcs->contention_point[i];
217 
218                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
219                         stats.contending_point[i] += pcs->contending_point[i];
220 
221                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
222                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
223 
224                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
225                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
226 
227                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
228                         stats.bounces[i] += pcs->bounces[i];
229         }
230 
231         return stats;
232 }
233 
234 void clear_lock_stats(struct lock_class *class)
235 {
236         int cpu;
237 
238         for_each_possible_cpu(cpu) {
239                 struct lock_class_stats *cpu_stats =
240                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
241 
242                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
243         }
244         memset(class->contention_point, 0, sizeof(class->contention_point));
245         memset(class->contending_point, 0, sizeof(class->contending_point));
246 }
247 
248 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
249 {
250         return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
251 }
252 
253 static void put_lock_stats(struct lock_class_stats *stats)
254 {
255         put_cpu_var(cpu_lock_stats);
256 }
257 
258 static void lock_release_holdtime(struct held_lock *hlock)
259 {
260         struct lock_class_stats *stats;
261         u64 holdtime;
262 
263         if (!lock_stat)
264                 return;
265 
266         holdtime = lockstat_clock() - hlock->holdtime_stamp;
267 
268         stats = get_lock_stats(hlock_class(hlock));
269         if (hlock->read)
270                 lock_time_inc(&stats->read_holdtime, holdtime);
271         else
272                 lock_time_inc(&stats->write_holdtime, holdtime);
273         put_lock_stats(stats);
274 }
275 #else
276 static inline void lock_release_holdtime(struct held_lock *hlock)
277 {
278 }
279 #endif
280 
281 /*
282  * We keep a global list of all lock classes. The list only grows,
283  * never shrinks. The list is only accessed with the lockdep
284  * spinlock lock held.
285  */
286 LIST_HEAD(all_lock_classes);
287 
288 /*
289  * The lockdep classes are in a hash-table as well, for fast lookup:
290  */
291 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
292 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
293 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
294 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
295 
296 static struct hlist_head classhash_table[CLASSHASH_SIZE];
297 
298 /*
299  * We put the lock dependency chains into a hash-table as well, to cache
300  * their existence:
301  */
302 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
303 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
304 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
305 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
306 
307 static struct hlist_head chainhash_table[CHAINHASH_SIZE];
308 
309 /*
310  * The hash key of the lock dependency chains is a hash itself too:
311  * it's a hash of all locks taken up to that lock, including that lock.
312  * It's a 64-bit hash, because it's important for the keys to be
313  * unique.
314  */
315 static inline u64 iterate_chain_key(u64 key, u32 idx)
316 {
317         u32 k0 = key, k1 = key >> 32;
318 
319         __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
320 
321         return k0 | (u64)k1 << 32;
322 }
323 
324 void lockdep_off(void)
325 {
326         current->lockdep_recursion++;
327 }
328 EXPORT_SYMBOL(lockdep_off);
329 
330 void lockdep_on(void)
331 {
332         current->lockdep_recursion--;
333 }
334 EXPORT_SYMBOL(lockdep_on);
335 
336 /*
337  * Debugging switches:
338  */
339 
340 #define VERBOSE                 0
341 #define VERY_VERBOSE            0
342 
343 #if VERBOSE
344 # define HARDIRQ_VERBOSE        1
345 # define SOFTIRQ_VERBOSE        1
346 # define RECLAIM_VERBOSE        1
347 #else
348 # define HARDIRQ_VERBOSE        0
349 # define SOFTIRQ_VERBOSE        0
350 # define RECLAIM_VERBOSE        0
351 #endif
352 
353 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
354 /*
355  * Quick filtering for interesting events:
356  */
357 static int class_filter(struct lock_class *class)
358 {
359 #if 0
360         /* Example */
361         if (class->name_version == 1 &&
362                         !strcmp(class->name, "lockname"))
363                 return 1;
364         if (class->name_version == 1 &&
365                         !strcmp(class->name, "&struct->lockfield"))
366                 return 1;
367 #endif
368         /* Filter everything else. 1 would be to allow everything else */
369         return 0;
370 }
371 #endif
372 
373 static int verbose(struct lock_class *class)
374 {
375 #if VERBOSE
376         return class_filter(class);
377 #endif
378         return 0;
379 }
380 
381 /*
382  * Stack-trace: tightly packed array of stack backtrace
383  * addresses. Protected by the graph_lock.
384  */
385 unsigned long nr_stack_trace_entries;
386 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
387 
388 static void print_lockdep_off(const char *bug_msg)
389 {
390         printk(KERN_DEBUG "%s\n", bug_msg);
391         printk(KERN_DEBUG "turning off the locking correctness validator.\n");
392 #ifdef CONFIG_LOCK_STAT
393         printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
394 #endif
395 }
396 
397 static int save_trace(struct stack_trace *trace)
398 {
399         trace->nr_entries = 0;
400         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
401         trace->entries = stack_trace + nr_stack_trace_entries;
402 
403         trace->skip = 3;
404 
405         save_stack_trace(trace);
406 
407         /*
408          * Some daft arches put -1 at the end to indicate its a full trace.
409          *
410          * <rant> this is buggy anyway, since it takes a whole extra entry so a
411          * complete trace that maxes out the entries provided will be reported
412          * as incomplete, friggin useless </rant>
413          */
414         if (trace->nr_entries != 0 &&
415             trace->entries[trace->nr_entries-1] == ULONG_MAX)
416                 trace->nr_entries--;
417 
418         trace->max_entries = trace->nr_entries;
419 
420         nr_stack_trace_entries += trace->nr_entries;
421 
422         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
423                 if (!debug_locks_off_graph_unlock())
424                         return 0;
425 
426                 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
427                 dump_stack();
428 
429                 return 0;
430         }
431 
432         return 1;
433 }
434 
435 unsigned int nr_hardirq_chains;
436 unsigned int nr_softirq_chains;
437 unsigned int nr_process_chains;
438 unsigned int max_lockdep_depth;
439 
440 #ifdef CONFIG_DEBUG_LOCKDEP
441 /*
442  * Various lockdep statistics:
443  */
444 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
445 #endif
446 
447 /*
448  * Locking printouts:
449  */
450 
451 #define __USAGE(__STATE)                                                \
452         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
453         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
454         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
455         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
456 
457 static const char *usage_str[] =
458 {
459 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
460 #include "lockdep_states.h"
461 #undef LOCKDEP_STATE
462         [LOCK_USED] = "INITIAL USE",
463 };
464 
465 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
466 {
467         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
468 }
469 
470 static inline unsigned long lock_flag(enum lock_usage_bit bit)
471 {
472         return 1UL << bit;
473 }
474 
475 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
476 {
477         char c = '.';
478 
479         if (class->usage_mask & lock_flag(bit + 2))
480                 c = '+';
481         if (class->usage_mask & lock_flag(bit)) {
482                 c = '-';
483                 if (class->usage_mask & lock_flag(bit + 2))
484                         c = '?';
485         }
486 
487         return c;
488 }
489 
490 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
491 {
492         int i = 0;
493 
494 #define LOCKDEP_STATE(__STATE)                                          \
495         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
496         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
497 #include "lockdep_states.h"
498 #undef LOCKDEP_STATE
499 
500         usage[i] = '\0';
501 }
502 
503 static void __print_lock_name(struct lock_class *class)
504 {
505         char str[KSYM_NAME_LEN];
506         const char *name;
507 
508         name = class->name;
509         if (!name) {
510                 name = __get_key_name(class->key, str);
511                 printk(KERN_CONT "%s", name);
512         } else {
513                 printk(KERN_CONT "%s", name);
514                 if (class->name_version > 1)
515                         printk(KERN_CONT "#%d", class->name_version);
516                 if (class->subclass)
517                         printk(KERN_CONT "/%d", class->subclass);
518         }
519 }
520 
521 static void print_lock_name(struct lock_class *class)
522 {
523         char usage[LOCK_USAGE_CHARS];
524 
525         get_usage_chars(class, usage);
526 
527         printk(KERN_CONT " (");
528         __print_lock_name(class);
529         printk(KERN_CONT "){%s}", usage);
530 }
531 
532 static void print_lockdep_cache(struct lockdep_map *lock)
533 {
534         const char *name;
535         char str[KSYM_NAME_LEN];
536 
537         name = lock->name;
538         if (!name)
539                 name = __get_key_name(lock->key->subkeys, str);
540 
541         printk(KERN_CONT "%s", name);
542 }
543 
544 static void print_lock(struct held_lock *hlock)
545 {
546         /*
547          * We can be called locklessly through debug_show_all_locks() so be
548          * extra careful, the hlock might have been released and cleared.
549          */
550         unsigned int class_idx = hlock->class_idx;
551 
552         /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
553         barrier();
554 
555         if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
556                 printk(KERN_CONT "<RELEASED>\n");
557                 return;
558         }
559 
560         print_lock_name(lock_classes + class_idx - 1);
561         printk(KERN_CONT ", at: [<%p>] %pS\n",
562                 (void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
563 }
564 
565 static void lockdep_print_held_locks(struct task_struct *curr)
566 {
567         int i, depth = curr->lockdep_depth;
568 
569         if (!depth) {
570                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
571                 return;
572         }
573         printk("%d lock%s held by %s/%d:\n",
574                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
575 
576         for (i = 0; i < depth; i++) {
577                 printk(" #%d: ", i);
578                 print_lock(curr->held_locks + i);
579         }
580 }
581 
582 static void print_kernel_ident(void)
583 {
584         printk("%s %.*s %s\n", init_utsname()->release,
585                 (int)strcspn(init_utsname()->version, " "),
586                 init_utsname()->version,
587                 print_tainted());
588 }
589 
590 static int very_verbose(struct lock_class *class)
591 {
592 #if VERY_VERBOSE
593         return class_filter(class);
594 #endif
595         return 0;
596 }
597 
598 /*
599  * Is this the address of a static object:
600  */
601 #ifdef __KERNEL__
602 static int static_obj(void *obj)
603 {
604         unsigned long start = (unsigned long) &_stext,
605                       end   = (unsigned long) &_end,
606                       addr  = (unsigned long) obj;
607 
608         /*
609          * static variable?
610          */
611         if ((addr >= start) && (addr < end))
612                 return 1;
613 
614         if (arch_is_kernel_data(addr))
615                 return 1;
616 
617         /*
618          * in-kernel percpu var?
619          */
620         if (is_kernel_percpu_address(addr))
621                 return 1;
622 
623         /*
624          * module static or percpu var?
625          */
626         return is_module_address(addr) || is_module_percpu_address(addr);
627 }
628 #endif
629 
630 /*
631  * To make lock name printouts unique, we calculate a unique
632  * class->name_version generation counter:
633  */
634 static int count_matching_names(struct lock_class *new_class)
635 {
636         struct lock_class *class;
637         int count = 0;
638 
639         if (!new_class->name)
640                 return 0;
641 
642         list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
643                 if (new_class->key - new_class->subclass == class->key)
644                         return class->name_version;
645                 if (class->name && !strcmp(class->name, new_class->name))
646                         count = max(count, class->name_version);
647         }
648 
649         return count + 1;
650 }
651 
652 /*
653  * Register a lock's class in the hash-table, if the class is not present
654  * yet. Otherwise we look it up. We cache the result in the lock object
655  * itself, so actual lookup of the hash should be once per lock object.
656  */
657 static inline struct lock_class *
658 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
659 {
660         struct lockdep_subclass_key *key;
661         struct hlist_head *hash_head;
662         struct lock_class *class;
663 
664         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
665                 debug_locks_off();
666                 printk(KERN_ERR
667                         "BUG: looking up invalid subclass: %u\n", subclass);
668                 printk(KERN_ERR
669                         "turning off the locking correctness validator.\n");
670                 dump_stack();
671                 return NULL;
672         }
673 
674         /*
675          * Static locks do not have their class-keys yet - for them the key
676          * is the lock object itself:
677          */
678         if (unlikely(!lock->key))
679                 lock->key = (void *)lock;
680 
681         /*
682          * NOTE: the class-key must be unique. For dynamic locks, a static
683          * lock_class_key variable is passed in through the mutex_init()
684          * (or spin_lock_init()) call - which acts as the key. For static
685          * locks we use the lock object itself as the key.
686          */
687         BUILD_BUG_ON(sizeof(struct lock_class_key) >
688                         sizeof(struct lockdep_map));
689 
690         key = lock->key->subkeys + subclass;
691 
692         hash_head = classhashentry(key);
693 
694         /*
695          * We do an RCU walk of the hash, see lockdep_free_key_range().
696          */
697         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
698                 return NULL;
699 
700         hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
701                 if (class->key == key) {
702                         /*
703                          * Huh! same key, different name? Did someone trample
704                          * on some memory? We're most confused.
705                          */
706                         WARN_ON_ONCE(class->name != lock->name);
707                         return class;
708                 }
709         }
710 
711         return NULL;
712 }
713 
714 /*
715  * Register a lock's class in the hash-table, if the class is not present
716  * yet. Otherwise we look it up. We cache the result in the lock object
717  * itself, so actual lookup of the hash should be once per lock object.
718  */
719 static struct lock_class *
720 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
721 {
722         struct lockdep_subclass_key *key;
723         struct hlist_head *hash_head;
724         struct lock_class *class;
725 
726         DEBUG_LOCKS_WARN_ON(!irqs_disabled());
727 
728         class = look_up_lock_class(lock, subclass);
729         if (likely(class))
730                 goto out_set_class_cache;
731 
732         /*
733          * Debug-check: all keys must be persistent!
734          */
735         if (!static_obj(lock->key)) {
736                 debug_locks_off();
737                 printk("INFO: trying to register non-static key.\n");
738                 printk("the code is fine but needs lockdep annotation.\n");
739                 printk("turning off the locking correctness validator.\n");
740                 dump_stack();
741 
742                 return NULL;
743         }
744 
745         key = lock->key->subkeys + subclass;
746         hash_head = classhashentry(key);
747 
748         if (!graph_lock()) {
749                 return NULL;
750         }
751         /*
752          * We have to do the hash-walk again, to avoid races
753          * with another CPU:
754          */
755         hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
756                 if (class->key == key)
757                         goto out_unlock_set;
758         }
759 
760         /*
761          * Allocate a new key from the static array, and add it to
762          * the hash:
763          */
764         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
765                 if (!debug_locks_off_graph_unlock()) {
766                         return NULL;
767                 }
768 
769                 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
770                 dump_stack();
771                 return NULL;
772         }
773         class = lock_classes + nr_lock_classes++;
774         debug_atomic_inc(nr_unused_locks);
775         class->key = key;
776         class->name = lock->name;
777         class->subclass = subclass;
778         INIT_LIST_HEAD(&class->lock_entry);
779         INIT_LIST_HEAD(&class->locks_before);
780         INIT_LIST_HEAD(&class->locks_after);
781         class->name_version = count_matching_names(class);
782         /*
783          * We use RCU's safe list-add method to make
784          * parallel walking of the hash-list safe:
785          */
786         hlist_add_head_rcu(&class->hash_entry, hash_head);
787         /*
788          * Add it to the global list of classes:
789          */
790         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
791 
792         if (verbose(class)) {
793                 graph_unlock();
794 
795                 printk("\nnew class %p: %s", class->key, class->name);
796                 if (class->name_version > 1)
797                         printk(KERN_CONT "#%d", class->name_version);
798                 printk(KERN_CONT "\n");
799                 dump_stack();
800 
801                 if (!graph_lock()) {
802                         return NULL;
803                 }
804         }
805 out_unlock_set:
806         graph_unlock();
807 
808 out_set_class_cache:
809         if (!subclass || force)
810                 lock->class_cache[0] = class;
811         else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
812                 lock->class_cache[subclass] = class;
813 
814         /*
815          * Hash collision, did we smoke some? We found a class with a matching
816          * hash but the subclass -- which is hashed in -- didn't match.
817          */
818         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
819                 return NULL;
820 
821         return class;
822 }
823 
824 #ifdef CONFIG_PROVE_LOCKING
825 /*
826  * Allocate a lockdep entry. (assumes the graph_lock held, returns
827  * with NULL on failure)
828  */
829 static struct lock_list *alloc_list_entry(void)
830 {
831         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
832                 if (!debug_locks_off_graph_unlock())
833                         return NULL;
834 
835                 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
836                 dump_stack();
837                 return NULL;
838         }
839         return list_entries + nr_list_entries++;
840 }
841 
842 /*
843  * Add a new dependency to the head of the list:
844  */
845 static int add_lock_to_list(struct lock_class *this, struct list_head *head,
846                             unsigned long ip, int distance,
847                             struct stack_trace *trace)
848 {
849         struct lock_list *entry;
850         /*
851          * Lock not present yet - get a new dependency struct and
852          * add it to the list:
853          */
854         entry = alloc_list_entry();
855         if (!entry)
856                 return 0;
857 
858         entry->class = this;
859         entry->distance = distance;
860         entry->trace = *trace;
861         /*
862          * Both allocation and removal are done under the graph lock; but
863          * iteration is under RCU-sched; see look_up_lock_class() and
864          * lockdep_free_key_range().
865          */
866         list_add_tail_rcu(&entry->entry, head);
867 
868         return 1;
869 }
870 
871 /*
872  * For good efficiency of modular, we use power of 2
873  */
874 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
875 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
876 
877 /*
878  * The circular_queue and helpers is used to implement the
879  * breadth-first search(BFS)algorithem, by which we can build
880  * the shortest path from the next lock to be acquired to the
881  * previous held lock if there is a circular between them.
882  */
883 struct circular_queue {
884         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
885         unsigned int  front, rear;
886 };
887 
888 static struct circular_queue lock_cq;
889 
890 unsigned int max_bfs_queue_depth;
891 
892 static unsigned int lockdep_dependency_gen_id;
893 
894 static inline void __cq_init(struct circular_queue *cq)
895 {
896         cq->front = cq->rear = 0;
897         lockdep_dependency_gen_id++;
898 }
899 
900 static inline int __cq_empty(struct circular_queue *cq)
901 {
902         return (cq->front == cq->rear);
903 }
904 
905 static inline int __cq_full(struct circular_queue *cq)
906 {
907         return ((cq->rear + 1) & CQ_MASK) == cq->front;
908 }
909 
910 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
911 {
912         if (__cq_full(cq))
913                 return -1;
914 
915         cq->element[cq->rear] = elem;
916         cq->rear = (cq->rear + 1) & CQ_MASK;
917         return 0;
918 }
919 
920 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
921 {
922         if (__cq_empty(cq))
923                 return -1;
924 
925         *elem = cq->element[cq->front];
926         cq->front = (cq->front + 1) & CQ_MASK;
927         return 0;
928 }
929 
930 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
931 {
932         return (cq->rear - cq->front) & CQ_MASK;
933 }
934 
935 static inline void mark_lock_accessed(struct lock_list *lock,
936                                         struct lock_list *parent)
937 {
938         unsigned long nr;
939 
940         nr = lock - list_entries;
941         WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
942         lock->parent = parent;
943         lock->class->dep_gen_id = lockdep_dependency_gen_id;
944 }
945 
946 static inline unsigned long lock_accessed(struct lock_list *lock)
947 {
948         unsigned long nr;
949 
950         nr = lock - list_entries;
951         WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
952         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
953 }
954 
955 static inline struct lock_list *get_lock_parent(struct lock_list *child)
956 {
957         return child->parent;
958 }
959 
960 static inline int get_lock_depth(struct lock_list *child)
961 {
962         int depth = 0;
963         struct lock_list *parent;
964 
965         while ((parent = get_lock_parent(child))) {
966                 child = parent;
967                 depth++;
968         }
969         return depth;
970 }
971 
972 static int __bfs(struct lock_list *source_entry,
973                  void *data,
974                  int (*match)(struct lock_list *entry, void *data),
975                  struct lock_list **target_entry,
976                  int forward)
977 {
978         struct lock_list *entry;
979         struct list_head *head;
980         struct circular_queue *cq = &lock_cq;
981         int ret = 1;
982 
983         if (match(source_entry, data)) {
984                 *target_entry = source_entry;
985                 ret = 0;
986                 goto exit;
987         }
988 
989         if (forward)
990                 head = &source_entry->class->locks_after;
991         else
992                 head = &source_entry->class->locks_before;
993 
994         if (list_empty(head))
995                 goto exit;
996 
997         __cq_init(cq);
998         __cq_enqueue(cq, (unsigned long)source_entry);
999 
1000         while (!__cq_empty(cq)) {
1001                 struct lock_list *lock;
1002 
1003                 __cq_dequeue(cq, (unsigned long *)&lock);
1004 
1005                 if (!lock->class) {
1006                         ret = -2;
1007                         goto exit;
1008                 }
1009 
1010                 if (forward)
1011                         head = &lock->class->locks_after;
1012                 else
1013                         head = &lock->class->locks_before;
1014 
1015                 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1016 
1017                 list_for_each_entry_rcu(entry, head, entry) {
1018                         if (!lock_accessed(entry)) {
1019                                 unsigned int cq_depth;
1020                                 mark_lock_accessed(entry, lock);
1021                                 if (match(entry, data)) {
1022                                         *target_entry = entry;
1023                                         ret = 0;
1024                                         goto exit;
1025                                 }
1026 
1027                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1028                                         ret = -1;
1029                                         goto exit;
1030                                 }
1031                                 cq_depth = __cq_get_elem_count(cq);
1032                                 if (max_bfs_queue_depth < cq_depth)
1033                                         max_bfs_queue_depth = cq_depth;
1034                         }
1035                 }
1036         }
1037 exit:
1038         return ret;
1039 }
1040 
1041 static inline int __bfs_forwards(struct lock_list *src_entry,
1042                         void *data,
1043                         int (*match)(struct lock_list *entry, void *data),
1044                         struct lock_list **target_entry)
1045 {
1046         return __bfs(src_entry, data, match, target_entry, 1);
1047 
1048 }
1049 
1050 static inline int __bfs_backwards(struct lock_list *src_entry,
1051                         void *data,
1052                         int (*match)(struct lock_list *entry, void *data),
1053                         struct lock_list **target_entry)
1054 {
1055         return __bfs(src_entry, data, match, target_entry, 0);
1056 
1057 }
1058 
1059 /*
1060  * Recursive, forwards-direction lock-dependency checking, used for
1061  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1062  * checking.
1063  */
1064 
1065 /*
1066  * Print a dependency chain entry (this is only done when a deadlock
1067  * has been detected):
1068  */
1069 static noinline int
1070 print_circular_bug_entry(struct lock_list *target, int depth)
1071 {
1072         if (debug_locks_silent)
1073                 return 0;
1074         printk("\n-> #%u", depth);
1075         print_lock_name(target->class);
1076         printk(KERN_CONT ":\n");
1077         print_stack_trace(&target->trace, 6);
1078 
1079         return 0;
1080 }
1081 
1082 static void
1083 print_circular_lock_scenario(struct held_lock *src,
1084                              struct held_lock *tgt,
1085                              struct lock_list *prt)
1086 {
1087         struct lock_class *source = hlock_class(src);
1088         struct lock_class *target = hlock_class(tgt);
1089         struct lock_class *parent = prt->class;
1090 
1091         /*
1092          * A direct locking problem where unsafe_class lock is taken
1093          * directly by safe_class lock, then all we need to show
1094          * is the deadlock scenario, as it is obvious that the
1095          * unsafe lock is taken under the safe lock.
1096          *
1097          * But if there is a chain instead, where the safe lock takes
1098          * an intermediate lock (middle_class) where this lock is
1099          * not the same as the safe lock, then the lock chain is
1100          * used to describe the problem. Otherwise we would need
1101          * to show a different CPU case for each link in the chain
1102          * from the safe_class lock to the unsafe_class lock.
1103          */
1104         if (parent != source) {
1105                 printk("Chain exists of:\n  ");
1106                 __print_lock_name(source);
1107                 printk(KERN_CONT " --> ");
1108                 __print_lock_name(parent);
1109                 printk(KERN_CONT " --> ");
1110                 __print_lock_name(target);
1111                 printk(KERN_CONT "\n\n");
1112         }
1113 
1114         printk(" Possible unsafe locking scenario:\n\n");
1115         printk("       CPU0                    CPU1\n");
1116         printk("       ----                    ----\n");
1117         printk("  lock(");
1118         __print_lock_name(target);
1119         printk(KERN_CONT ");\n");
1120         printk("                               lock(");
1121         __print_lock_name(parent);
1122         printk(KERN_CONT ");\n");
1123         printk("                               lock(");
1124         __print_lock_name(target);
1125         printk(KERN_CONT ");\n");
1126         printk("  lock(");
1127         __print_lock_name(source);
1128         printk(KERN_CONT ");\n");
1129         printk("\n *** DEADLOCK ***\n\n");
1130 }
1131 
1132 /*
1133  * When a circular dependency is detected, print the
1134  * header first:
1135  */
1136 static noinline int
1137 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1138                         struct held_lock *check_src,
1139                         struct held_lock *check_tgt)
1140 {
1141         struct task_struct *curr = current;
1142 
1143         if (debug_locks_silent)
1144                 return 0;
1145 
1146         printk("\n");
1147         printk("======================================================\n");
1148         printk("[ INFO: possible circular locking dependency detected ]\n");
1149         print_kernel_ident();
1150         printk("-------------------------------------------------------\n");
1151         printk("%s/%d is trying to acquire lock:\n",
1152                 curr->comm, task_pid_nr(curr));
1153         print_lock(check_src);
1154         printk("\nbut task is already holding lock:\n");
1155         print_lock(check_tgt);
1156         printk("\nwhich lock already depends on the new lock.\n\n");
1157         printk("\nthe existing dependency chain (in reverse order) is:\n");
1158 
1159         print_circular_bug_entry(entry, depth);
1160 
1161         return 0;
1162 }
1163 
1164 static inline int class_equal(struct lock_list *entry, void *data)
1165 {
1166         return entry->class == data;
1167 }
1168 
1169 static noinline int print_circular_bug(struct lock_list *this,
1170                                 struct lock_list *target,
1171                                 struct held_lock *check_src,
1172                                 struct held_lock *check_tgt)
1173 {
1174         struct task_struct *curr = current;
1175         struct lock_list *parent;
1176         struct lock_list *first_parent;
1177         int depth;
1178 
1179         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1180                 return 0;
1181 
1182         if (!save_trace(&this->trace))
1183                 return 0;
1184 
1185         depth = get_lock_depth(target);
1186 
1187         print_circular_bug_header(target, depth, check_src, check_tgt);
1188 
1189         parent = get_lock_parent(target);
1190         first_parent = parent;
1191 
1192         while (parent) {
1193                 print_circular_bug_entry(parent, --depth);
1194                 parent = get_lock_parent(parent);
1195         }
1196 
1197         printk("\nother info that might help us debug this:\n\n");
1198         print_circular_lock_scenario(check_src, check_tgt,
1199                                      first_parent);
1200 
1201         lockdep_print_held_locks(curr);
1202 
1203         printk("\nstack backtrace:\n");
1204         dump_stack();
1205 
1206         return 0;
1207 }
1208 
1209 static noinline int print_bfs_bug(int ret)
1210 {
1211         if (!debug_locks_off_graph_unlock())
1212                 return 0;
1213 
1214         /*
1215          * Breadth-first-search failed, graph got corrupted?
1216          */
1217         WARN(1, "lockdep bfs error:%d\n", ret);
1218 
1219         return 0;
1220 }
1221 
1222 static int noop_count(struct lock_list *entry, void *data)
1223 {
1224         (*(unsigned long *)data)++;
1225         return 0;
1226 }
1227 
1228 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1229 {
1230         unsigned long  count = 0;
1231         struct lock_list *uninitialized_var(target_entry);
1232 
1233         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1234 
1235         return count;
1236 }
1237 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1238 {
1239         unsigned long ret, flags;
1240         struct lock_list this;
1241 
1242         this.parent = NULL;
1243         this.class = class;
1244 
1245         local_irq_save(flags);
1246         arch_spin_lock(&lockdep_lock);
1247         ret = __lockdep_count_forward_deps(&this);
1248         arch_spin_unlock(&lockdep_lock);
1249         local_irq_restore(flags);
1250 
1251         return ret;
1252 }
1253 
1254 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1255 {
1256         unsigned long  count = 0;
1257         struct lock_list *uninitialized_var(target_entry);
1258 
1259         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1260 
1261         return count;
1262 }
1263 
1264 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1265 {
1266         unsigned long ret, flags;
1267         struct lock_list this;
1268 
1269         this.parent = NULL;
1270         this.class = class;
1271 
1272         local_irq_save(flags);
1273         arch_spin_lock(&lockdep_lock);
1274         ret = __lockdep_count_backward_deps(&this);
1275         arch_spin_unlock(&lockdep_lock);
1276         local_irq_restore(flags);
1277 
1278         return ret;
1279 }
1280 
1281 /*
1282  * Prove that the dependency graph starting at <entry> can not
1283  * lead to <target>. Print an error and return 0 if it does.
1284  */
1285 static noinline int
1286 check_noncircular(struct lock_list *root, struct lock_class *target,
1287                 struct lock_list **target_entry)
1288 {
1289         int result;
1290 
1291         debug_atomic_inc(nr_cyclic_checks);
1292 
1293         result = __bfs_forwards(root, target, class_equal, target_entry);
1294 
1295         return result;
1296 }
1297 
1298 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1299 /*
1300  * Forwards and backwards subgraph searching, for the purposes of
1301  * proving that two subgraphs can be connected by a new dependency
1302  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1303  */
1304 
1305 static inline int usage_match(struct lock_list *entry, void *bit)
1306 {
1307         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1308 }
1309 
1310 
1311 
1312 /*
1313  * Find a node in the forwards-direction dependency sub-graph starting
1314  * at @root->class that matches @bit.
1315  *
1316  * Return 0 if such a node exists in the subgraph, and put that node
1317  * into *@target_entry.
1318  *
1319  * Return 1 otherwise and keep *@target_entry unchanged.
1320  * Return <0 on error.
1321  */
1322 static int
1323 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1324                         struct lock_list **target_entry)
1325 {
1326         int result;
1327 
1328         debug_atomic_inc(nr_find_usage_forwards_checks);
1329 
1330         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1331 
1332         return result;
1333 }
1334 
1335 /*
1336  * Find a node in the backwards-direction dependency sub-graph starting
1337  * at @root->class that matches @bit.
1338  *
1339  * Return 0 if such a node exists in the subgraph, and put that node
1340  * into *@target_entry.
1341  *
1342  * Return 1 otherwise and keep *@target_entry unchanged.
1343  * Return <0 on error.
1344  */
1345 static int
1346 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1347                         struct lock_list **target_entry)
1348 {
1349         int result;
1350 
1351         debug_atomic_inc(nr_find_usage_backwards_checks);
1352 
1353         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1354 
1355         return result;
1356 }
1357 
1358 static void print_lock_class_header(struct lock_class *class, int depth)
1359 {
1360         int bit;
1361 
1362         printk("%*s->", depth, "");
1363         print_lock_name(class);
1364         printk(KERN_CONT " ops: %lu", class->ops);
1365         printk(KERN_CONT " {\n");
1366 
1367         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1368                 if (class->usage_mask & (1 << bit)) {
1369                         int len = depth;
1370 
1371                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1372                         len += printk(KERN_CONT " at:\n");
1373                         print_stack_trace(class->usage_traces + bit, len);
1374                 }
1375         }
1376         printk("%*s }\n", depth, "");
1377 
1378         printk("%*s ... key      at: [<%p>] %pS\n",
1379                 depth, "", class->key, class->key);
1380 }
1381 
1382 /*
1383  * printk the shortest lock dependencies from @start to @end in reverse order:
1384  */
1385 static void __used
1386 print_shortest_lock_dependencies(struct lock_list *leaf,
1387                                 struct lock_list *root)
1388 {
1389         struct lock_list *entry = leaf;
1390         int depth;
1391 
1392         /*compute depth from generated tree by BFS*/
1393         depth = get_lock_depth(leaf);
1394 
1395         do {
1396                 print_lock_class_header(entry->class, depth);
1397                 printk("%*s ... acquired at:\n", depth, "");
1398                 print_stack_trace(&entry->trace, 2);
1399                 printk("\n");
1400 
1401                 if (depth == 0 && (entry != root)) {
1402                         printk("lockdep:%s bad path found in chain graph\n", __func__);
1403                         break;
1404                 }
1405 
1406                 entry = get_lock_parent(entry);
1407                 depth--;
1408         } while (entry && (depth >= 0));
1409 
1410         return;
1411 }
1412 
1413 static void
1414 print_irq_lock_scenario(struct lock_list *safe_entry,
1415                         struct lock_list *unsafe_entry,
1416                         struct lock_class *prev_class,
1417                         struct lock_class *next_class)
1418 {
1419         struct lock_class *safe_class = safe_entry->class;
1420         struct lock_class *unsafe_class = unsafe_entry->class;
1421         struct lock_class *middle_class = prev_class;
1422 
1423         if (middle_class == safe_class)
1424                 middle_class = next_class;
1425 
1426         /*
1427          * A direct locking problem where unsafe_class lock is taken
1428          * directly by safe_class lock, then all we need to show
1429          * is the deadlock scenario, as it is obvious that the
1430          * unsafe lock is taken under the safe lock.
1431          *
1432          * But if there is a chain instead, where the safe lock takes
1433          * an intermediate lock (middle_class) where this lock is
1434          * not the same as the safe lock, then the lock chain is
1435          * used to describe the problem. Otherwise we would need
1436          * to show a different CPU case for each link in the chain
1437          * from the safe_class lock to the unsafe_class lock.
1438          */
1439         if (middle_class != unsafe_class) {
1440                 printk("Chain exists of:\n  ");
1441                 __print_lock_name(safe_class);
1442                 printk(KERN_CONT " --> ");
1443                 __print_lock_name(middle_class);
1444                 printk(KERN_CONT " --> ");
1445                 __print_lock_name(unsafe_class);
1446                 printk(KERN_CONT "\n\n");
1447         }
1448 
1449         printk(" Possible interrupt unsafe locking scenario:\n\n");
1450         printk("       CPU0                    CPU1\n");
1451         printk("       ----                    ----\n");
1452         printk("  lock(");
1453         __print_lock_name(unsafe_class);
1454         printk(KERN_CONT ");\n");
1455         printk("                               local_irq_disable();\n");
1456         printk("                               lock(");
1457         __print_lock_name(safe_class);
1458         printk(KERN_CONT ");\n");
1459         printk("                               lock(");
1460         __print_lock_name(middle_class);
1461         printk(KERN_CONT ");\n");
1462         printk("  <Interrupt>\n");
1463         printk("    lock(");
1464         __print_lock_name(safe_class);
1465         printk(KERN_CONT ");\n");
1466         printk("\n *** DEADLOCK ***\n\n");
1467 }
1468 
1469 static int
1470 print_bad_irq_dependency(struct task_struct *curr,
1471                          struct lock_list *prev_root,
1472                          struct lock_list *next_root,
1473                          struct lock_list *backwards_entry,
1474                          struct lock_list *forwards_entry,
1475                          struct held_lock *prev,
1476                          struct held_lock *next,
1477                          enum lock_usage_bit bit1,
1478                          enum lock_usage_bit bit2,
1479                          const char *irqclass)
1480 {
1481         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1482                 return 0;
1483 
1484         printk("\n");
1485         printk("======================================================\n");
1486         printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1487                 irqclass, irqclass);
1488         print_kernel_ident();
1489         printk("------------------------------------------------------\n");
1490         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1491                 curr->comm, task_pid_nr(curr),
1492                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1493                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1494                 curr->hardirqs_enabled,
1495                 curr->softirqs_enabled);
1496         print_lock(next);
1497 
1498         printk("\nand this task is already holding:\n");
1499         print_lock(prev);
1500         printk("which would create a new lock dependency:\n");
1501         print_lock_name(hlock_class(prev));
1502         printk(KERN_CONT " ->");
1503         print_lock_name(hlock_class(next));
1504         printk(KERN_CONT "\n");
1505 
1506         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1507                 irqclass);
1508         print_lock_name(backwards_entry->class);
1509         printk("\n... which became %s-irq-safe at:\n", irqclass);
1510 
1511         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1512 
1513         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1514         print_lock_name(forwards_entry->class);
1515         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1516         printk("...");
1517 
1518         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1519 
1520         printk("\nother info that might help us debug this:\n\n");
1521         print_irq_lock_scenario(backwards_entry, forwards_entry,
1522                                 hlock_class(prev), hlock_class(next));
1523 
1524         lockdep_print_held_locks(curr);
1525 
1526         printk("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
1527         if (!save_trace(&prev_root->trace))
1528                 return 0;
1529         print_shortest_lock_dependencies(backwards_entry, prev_root);
1530 
1531         printk("\nthe dependencies between the lock to be acquired");
1532         printk(" and %s-irq-unsafe lock:\n", irqclass);
1533         if (!save_trace(&next_root->trace))
1534                 return 0;
1535         print_shortest_lock_dependencies(forwards_entry, next_root);
1536 
1537         printk("\nstack backtrace:\n");
1538         dump_stack();
1539 
1540         return 0;
1541 }
1542 
1543 static int
1544 check_usage(struct task_struct *curr, struct held_lock *prev,
1545             struct held_lock *next, enum lock_usage_bit bit_backwards,
1546             enum lock_usage_bit bit_forwards, const char *irqclass)
1547 {
1548         int ret;
1549         struct lock_list this, that;
1550         struct lock_list *uninitialized_var(target_entry);
1551         struct lock_list *uninitialized_var(target_entry1);
1552 
1553         this.parent = NULL;
1554 
1555         this.class = hlock_class(prev);
1556         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1557         if (ret < 0)
1558                 return print_bfs_bug(ret);
1559         if (ret == 1)
1560                 return ret;
1561 
1562         that.parent = NULL;
1563         that.class = hlock_class(next);
1564         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1565         if (ret < 0)
1566                 return print_bfs_bug(ret);
1567         if (ret == 1)
1568                 return ret;
1569 
1570         return print_bad_irq_dependency(curr, &this, &that,
1571                         target_entry, target_entry1,
1572                         prev, next,
1573                         bit_backwards, bit_forwards, irqclass);
1574 }
1575 
1576 static const char *state_names[] = {
1577 #define LOCKDEP_STATE(__STATE) \
1578         __stringify(__STATE),
1579 #include "lockdep_states.h"
1580 #undef LOCKDEP_STATE
1581 };
1582 
1583 static const char *state_rnames[] = {
1584 #define LOCKDEP_STATE(__STATE) \
1585         __stringify(__STATE)"-READ",
1586 #include "lockdep_states.h"
1587 #undef LOCKDEP_STATE
1588 };
1589 
1590 static inline const char *state_name(enum lock_usage_bit bit)
1591 {
1592         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1593 }
1594 
1595 static int exclusive_bit(int new_bit)
1596 {
1597         /*
1598          * USED_IN
1599          * USED_IN_READ
1600          * ENABLED
1601          * ENABLED_READ
1602          *
1603          * bit 0 - write/read
1604          * bit 1 - used_in/enabled
1605          * bit 2+  state
1606          */
1607 
1608         int state = new_bit & ~3;
1609         int dir = new_bit & 2;
1610 
1611         /*
1612          * keep state, bit flip the direction and strip read.
1613          */
1614         return state | (dir ^ 2);
1615 }
1616 
1617 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1618                            struct held_lock *next, enum lock_usage_bit bit)
1619 {
1620         /*
1621          * Prove that the new dependency does not connect a hardirq-safe
1622          * lock with a hardirq-unsafe lock - to achieve this we search
1623          * the backwards-subgraph starting at <prev>, and the
1624          * forwards-subgraph starting at <next>:
1625          */
1626         if (!check_usage(curr, prev, next, bit,
1627                            exclusive_bit(bit), state_name(bit)))
1628                 return 0;
1629 
1630         bit++; /* _READ */
1631 
1632         /*
1633          * Prove that the new dependency does not connect a hardirq-safe-read
1634          * lock with a hardirq-unsafe lock - to achieve this we search
1635          * the backwards-subgraph starting at <prev>, and the
1636          * forwards-subgraph starting at <next>:
1637          */
1638         if (!check_usage(curr, prev, next, bit,
1639                            exclusive_bit(bit), state_name(bit)))
1640                 return 0;
1641 
1642         return 1;
1643 }
1644 
1645 static int
1646 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1647                 struct held_lock *next)
1648 {
1649 #define LOCKDEP_STATE(__STATE)                                          \
1650         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1651                 return 0;
1652 #include "lockdep_states.h"
1653 #undef LOCKDEP_STATE
1654 
1655         return 1;
1656 }
1657 
1658 static void inc_chains(void)
1659 {
1660         if (current->hardirq_context)
1661                 nr_hardirq_chains++;
1662         else {
1663                 if (current->softirq_context)
1664                         nr_softirq_chains++;
1665                 else
1666                         nr_process_chains++;
1667         }
1668 }
1669 
1670 #else
1671 
1672 static inline int
1673 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1674                 struct held_lock *next)
1675 {
1676         return 1;
1677 }
1678 
1679 static inline void inc_chains(void)
1680 {
1681         nr_process_chains++;
1682 }
1683 
1684 #endif
1685 
1686 static void
1687 print_deadlock_scenario(struct held_lock *nxt,
1688                              struct held_lock *prv)
1689 {
1690         struct lock_class *next = hlock_class(nxt);
1691         struct lock_class *prev = hlock_class(prv);
1692 
1693         printk(" Possible unsafe locking scenario:\n\n");
1694         printk("       CPU0\n");
1695         printk("       ----\n");
1696         printk("  lock(");
1697         __print_lock_name(prev);
1698         printk(KERN_CONT ");\n");
1699         printk("  lock(");
1700         __print_lock_name(next);
1701         printk(KERN_CONT ");\n");
1702         printk("\n *** DEADLOCK ***\n\n");
1703         printk(" May be due to missing lock nesting notation\n\n");
1704 }
1705 
1706 static int
1707 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1708                    struct held_lock *next)
1709 {
1710         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1711                 return 0;
1712 
1713         printk("\n");
1714         printk("=============================================\n");
1715         printk("[ INFO: possible recursive locking detected ]\n");
1716         print_kernel_ident();
1717         printk("---------------------------------------------\n");
1718         printk("%s/%d is trying to acquire lock:\n",
1719                 curr->comm, task_pid_nr(curr));
1720         print_lock(next);
1721         printk("\nbut task is already holding lock:\n");
1722         print_lock(prev);
1723 
1724         printk("\nother info that might help us debug this:\n");
1725         print_deadlock_scenario(next, prev);
1726         lockdep_print_held_locks(curr);
1727 
1728         printk("\nstack backtrace:\n");
1729         dump_stack();
1730 
1731         return 0;
1732 }
1733 
1734 /*
1735  * Check whether we are holding such a class already.
1736  *
1737  * (Note that this has to be done separately, because the graph cannot
1738  * detect such classes of deadlocks.)
1739  *
1740  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1741  */
1742 static int
1743 check_deadlock(struct task_struct *curr, struct held_lock *next,
1744                struct lockdep_map *next_instance, int read)
1745 {
1746         struct held_lock *prev;
1747         struct held_lock *nest = NULL;
1748         int i;
1749 
1750         for (i = 0; i < curr->lockdep_depth; i++) {
1751                 prev = curr->held_locks + i;
1752 
1753                 if (prev->instance == next->nest_lock)
1754                         nest = prev;
1755 
1756                 if (hlock_class(prev) != hlock_class(next))
1757                         continue;
1758 
1759                 /*
1760                  * Allow read-after-read recursion of the same
1761                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1762                  */
1763                 if ((read == 2) && prev->read)
1764                         return 2;
1765 
1766                 /*
1767                  * We're holding the nest_lock, which serializes this lock's
1768                  * nesting behaviour.
1769                  */
1770                 if (nest)
1771                         return 2;
1772 
1773                 return print_deadlock_bug(curr, prev, next);
1774         }
1775         return 1;
1776 }
1777 
1778 /*
1779  * There was a chain-cache miss, and we are about to add a new dependency
1780  * to a previous lock. We recursively validate the following rules:
1781  *
1782  *  - would the adding of the <prev> -> <next> dependency create a
1783  *    circular dependency in the graph? [== circular deadlock]
1784  *
1785  *  - does the new prev->next dependency connect any hardirq-safe lock
1786  *    (in the full backwards-subgraph starting at <prev>) with any
1787  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1788  *    <next>)? [== illegal lock inversion with hardirq contexts]
1789  *
1790  *  - does the new prev->next dependency connect any softirq-safe lock
1791  *    (in the full backwards-subgraph starting at <prev>) with any
1792  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1793  *    <next>)? [== illegal lock inversion with softirq contexts]
1794  *
1795  * any of these scenarios could lead to a deadlock.
1796  *
1797  * Then if all the validations pass, we add the forwards and backwards
1798  * dependency.
1799  */
1800 static int
1801 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1802                struct held_lock *next, int distance, int *stack_saved)
1803 {
1804         struct lock_list *entry;
1805         int ret;
1806         struct lock_list this;
1807         struct lock_list *uninitialized_var(target_entry);
1808         /*
1809          * Static variable, serialized by the graph_lock().
1810          *
1811          * We use this static variable to save the stack trace in case
1812          * we call into this function multiple times due to encountering
1813          * trylocks in the held lock stack.
1814          */
1815         static struct stack_trace trace;
1816 
1817         /*
1818          * Prove that the new <prev> -> <next> dependency would not
1819          * create a circular dependency in the graph. (We do this by
1820          * forward-recursing into the graph starting at <next>, and
1821          * checking whether we can reach <prev>.)
1822          *
1823          * We are using global variables to control the recursion, to
1824          * keep the stackframe size of the recursive functions low:
1825          */
1826         this.class = hlock_class(next);
1827         this.parent = NULL;
1828         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1829         if (unlikely(!ret))
1830                 return print_circular_bug(&this, target_entry, next, prev);
1831         else if (unlikely(ret < 0))
1832                 return print_bfs_bug(ret);
1833 
1834         if (!check_prev_add_irq(curr, prev, next))
1835                 return 0;
1836 
1837         /*
1838          * For recursive read-locks we do all the dependency checks,
1839          * but we dont store read-triggered dependencies (only
1840          * write-triggered dependencies). This ensures that only the
1841          * write-side dependencies matter, and that if for example a
1842          * write-lock never takes any other locks, then the reads are
1843          * equivalent to a NOP.
1844          */
1845         if (next->read == 2 || prev->read == 2)
1846                 return 1;
1847         /*
1848          * Is the <prev> -> <next> dependency already present?
1849          *
1850          * (this may occur even though this is a new chain: consider
1851          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1852          *  chains - the second one will be new, but L1 already has
1853          *  L2 added to its dependency list, due to the first chain.)
1854          */
1855         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1856                 if (entry->class == hlock_class(next)) {
1857                         if (distance == 1)
1858                                 entry->distance = 1;
1859                         return 2;
1860                 }
1861         }
1862 
1863         if (!*stack_saved) {
1864                 if (!save_trace(&trace))
1865                         return 0;
1866                 *stack_saved = 1;
1867         }
1868 
1869         /*
1870          * Ok, all validations passed, add the new lock
1871          * to the previous lock's dependency list:
1872          */
1873         ret = add_lock_to_list(hlock_class(next),
1874                                &hlock_class(prev)->locks_after,
1875                                next->acquire_ip, distance, &trace);
1876 
1877         if (!ret)
1878                 return 0;
1879 
1880         ret = add_lock_to_list(hlock_class(prev),
1881                                &hlock_class(next)->locks_before,
1882                                next->acquire_ip, distance, &trace);
1883         if (!ret)
1884                 return 0;
1885 
1886         /*
1887          * Debugging printouts:
1888          */
1889         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1890                 /* We drop graph lock, so another thread can overwrite trace. */
1891                 *stack_saved = 0;
1892                 graph_unlock();
1893                 printk("\n new dependency: ");
1894                 print_lock_name(hlock_class(prev));
1895                 printk(KERN_CONT " => ");
1896                 print_lock_name(hlock_class(next));
1897                 printk(KERN_CONT "\n");
1898                 dump_stack();
1899                 return graph_lock();
1900         }
1901         return 1;
1902 }
1903 
1904 /*
1905  * Add the dependency to all directly-previous locks that are 'relevant'.
1906  * The ones that are relevant are (in increasing distance from curr):
1907  * all consecutive trylock entries and the final non-trylock entry - or
1908  * the end of this context's lock-chain - whichever comes first.
1909  */
1910 static int
1911 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1912 {
1913         int depth = curr->lockdep_depth;
1914         int stack_saved = 0;
1915         struct held_lock *hlock;
1916 
1917         /*
1918          * Debugging checks.
1919          *
1920          * Depth must not be zero for a non-head lock:
1921          */
1922         if (!depth)
1923                 goto out_bug;
1924         /*
1925          * At least two relevant locks must exist for this
1926          * to be a head:
1927          */
1928         if (curr->held_locks[depth].irq_context !=
1929                         curr->held_locks[depth-1].irq_context)
1930                 goto out_bug;
1931 
1932         for (;;) {
1933                 int distance = curr->lockdep_depth - depth + 1;
1934                 hlock = curr->held_locks + depth - 1;
1935                 /*
1936                  * Only non-recursive-read entries get new dependencies
1937                  * added:
1938                  */
1939                 if (hlock->read != 2 && hlock->check) {
1940                         if (!check_prev_add(curr, hlock, next,
1941                                                 distance, &stack_saved))
1942                                 return 0;
1943                         /*
1944                          * Stop after the first non-trylock entry,
1945                          * as non-trylock entries have added their
1946                          * own direct dependencies already, so this
1947                          * lock is connected to them indirectly:
1948                          */
1949                         if (!hlock->trylock)
1950                                 break;
1951                 }
1952                 depth--;
1953                 /*
1954                  * End of lock-stack?
1955                  */
1956                 if (!depth)
1957                         break;
1958                 /*
1959                  * Stop the search if we cross into another context:
1960                  */
1961                 if (curr->held_locks[depth].irq_context !=
1962                                 curr->held_locks[depth-1].irq_context)
1963                         break;
1964         }
1965         return 1;
1966 out_bug:
1967         if (!debug_locks_off_graph_unlock())
1968                 return 0;
1969 
1970         /*
1971          * Clearly we all shouldn't be here, but since we made it we
1972          * can reliable say we messed up our state. See the above two
1973          * gotos for reasons why we could possibly end up here.
1974          */
1975         WARN_ON(1);
1976 
1977         return 0;
1978 }
1979 
1980 unsigned long nr_lock_chains;
1981 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1982 int nr_chain_hlocks;
1983 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1984 
1985 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1986 {
1987         return lock_classes + chain_hlocks[chain->base + i];
1988 }
1989 
1990 /*
1991  * Returns the index of the first held_lock of the current chain
1992  */
1993 static inline int get_first_held_lock(struct task_struct *curr,
1994                                         struct held_lock *hlock)
1995 {
1996         int i;
1997         struct held_lock *hlock_curr;
1998 
1999         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2000                 hlock_curr = curr->held_locks + i;
2001                 if (hlock_curr->irq_context != hlock->irq_context)
2002                         break;
2003 
2004         }
2005 
2006         return ++i;
2007 }
2008 
2009 #ifdef CONFIG_DEBUG_LOCKDEP
2010 /*
2011  * Returns the next chain_key iteration
2012  */
2013 static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2014 {
2015         u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2016 
2017         printk(" class_idx:%d -> chain_key:%016Lx",
2018                 class_idx,
2019                 (unsigned long long)new_chain_key);
2020         return new_chain_key;
2021 }
2022 
2023 static void
2024 print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2025 {
2026         struct held_lock *hlock;
2027         u64 chain_key = 0;
2028         int depth = curr->lockdep_depth;
2029         int i;
2030 
2031         printk("depth: %u\n", depth + 1);
2032         for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2033                 hlock = curr->held_locks + i;
2034                 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2035 
2036                 print_lock(hlock);
2037         }
2038 
2039         print_chain_key_iteration(hlock_next->class_idx, chain_key);
2040         print_lock(hlock_next);
2041 }
2042 
2043 static void print_chain_keys_chain(struct lock_chain *chain)
2044 {
2045         int i;
2046         u64 chain_key = 0;
2047         int class_id;
2048 
2049         printk("depth: %u\n", chain->depth);
2050         for (i = 0; i < chain->depth; i++) {
2051                 class_id = chain_hlocks[chain->base + i];
2052                 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2053 
2054                 print_lock_name(lock_classes + class_id);
2055                 printk("\n");
2056         }
2057 }
2058 
2059 static void print_collision(struct task_struct *curr,
2060                         struct held_lock *hlock_next,
2061                         struct lock_chain *chain)
2062 {
2063         printk("\n");
2064         printk("======================\n");
2065         printk("[chain_key collision ]\n");
2066         print_kernel_ident();
2067         printk("----------------------\n");
2068         printk("%s/%d: ", current->comm, task_pid_nr(current));
2069         printk("Hash chain already cached but the contents don't match!\n");
2070 
2071         printk("Held locks:");
2072         print_chain_keys_held_locks(curr, hlock_next);
2073 
2074         printk("Locks in cached chain:");
2075         print_chain_keys_chain(chain);
2076 
2077         printk("\nstack backtrace:\n");
2078         dump_stack();
2079 }
2080 #endif
2081 
2082 /*
2083  * Checks whether the chain and the current held locks are consistent
2084  * in depth and also in content. If they are not it most likely means
2085  * that there was a collision during the calculation of the chain_key.
2086  * Returns: 0 not passed, 1 passed
2087  */
2088 static int check_no_collision(struct task_struct *curr,
2089                         struct held_lock *hlock,
2090                         struct lock_chain *chain)
2091 {
2092 #ifdef CONFIG_DEBUG_LOCKDEP
2093         int i, j, id;
2094 
2095         i = get_first_held_lock(curr, hlock);
2096 
2097         if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2098                 print_collision(curr, hlock, chain);
2099                 return 0;
2100         }
2101 
2102         for (j = 0; j < chain->depth - 1; j++, i++) {
2103                 id = curr->held_locks[i].class_idx - 1;
2104 
2105                 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2106                         print_collision(curr, hlock, chain);
2107                         return 0;
2108                 }
2109         }
2110 #endif
2111         return 1;
2112 }
2113 
2114 /*
2115  * Look up a dependency chain. If the key is not present yet then
2116  * add it and return 1 - in this case the new dependency chain is
2117  * validated. If the key is already hashed, return 0.
2118  * (On return with 1 graph_lock is held.)
2119  */
2120 static inline int lookup_chain_cache(struct task_struct *curr,
2121                                      struct held_lock *hlock,
2122                                      u64 chain_key)
2123 {
2124         struct lock_class *class = hlock_class(hlock);
2125         struct hlist_head *hash_head = chainhashentry(chain_key);
2126         struct lock_chain *chain;
2127         int i, j;
2128 
2129         /*
2130          * We might need to take the graph lock, ensure we've got IRQs
2131          * disabled to make this an IRQ-safe lock.. for recursion reasons
2132          * lockdep won't complain about its own locking errors.
2133          */
2134         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2135                 return 0;
2136         /*
2137          * We can walk it lock-free, because entries only get added
2138          * to the hash:
2139          */
2140         hlist_for_each_entry_rcu(chain, hash_head, entry) {
2141                 if (chain->chain_key == chain_key) {
2142 cache_hit:
2143                         debug_atomic_inc(chain_lookup_hits);
2144                         if (!check_no_collision(curr, hlock, chain))
2145                                 return 0;
2146 
2147                         if (very_verbose(class))
2148                                 printk("\nhash chain already cached, key: "
2149                                         "%016Lx tail class: [%p] %s\n",
2150                                         (unsigned long long)chain_key,
2151                                         class->key, class->name);
2152                         return 0;
2153                 }
2154         }
2155         if (very_verbose(class))
2156                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2157                         (unsigned long long)chain_key, class->key, class->name);
2158         /*
2159          * Allocate a new chain entry from the static array, and add
2160          * it to the hash:
2161          */
2162         if (!graph_lock())
2163                 return 0;
2164         /*
2165          * We have to walk the chain again locked - to avoid duplicates:
2166          */
2167         hlist_for_each_entry(chain, hash_head, entry) {
2168                 if (chain->chain_key == chain_key) {
2169                         graph_unlock();
2170                         goto cache_hit;
2171                 }
2172         }
2173         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2174                 if (!debug_locks_off_graph_unlock())
2175                         return 0;
2176 
2177                 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2178                 dump_stack();
2179                 return 0;
2180         }
2181         chain = lock_chains + nr_lock_chains++;
2182         chain->chain_key = chain_key;
2183         chain->irq_context = hlock->irq_context;
2184         i = get_first_held_lock(curr, hlock);
2185         chain->depth = curr->lockdep_depth + 1 - i;
2186 
2187         BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2188         BUILD_BUG_ON((1UL << 6)  <= ARRAY_SIZE(curr->held_locks));
2189         BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2190 
2191         if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2192                 chain->base = nr_chain_hlocks;
2193                 for (j = 0; j < chain->depth - 1; j++, i++) {
2194                         int lock_id = curr->held_locks[i].class_idx - 1;
2195                         chain_hlocks[chain->base + j] = lock_id;
2196                 }
2197                 chain_hlocks[chain->base + j] = class - lock_classes;
2198         }
2199 
2200         if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2201                 nr_chain_hlocks += chain->depth;
2202 
2203 #ifdef CONFIG_DEBUG_LOCKDEP
2204         /*
2205          * Important for check_no_collision().
2206          */
2207         if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2208                 if (!debug_locks_off_graph_unlock())
2209                         return 0;
2210 
2211                 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2212                 dump_stack();
2213                 return 0;
2214         }
2215 #endif
2216 
2217         hlist_add_head_rcu(&chain->entry, hash_head);
2218         debug_atomic_inc(chain_lookup_misses);
2219         inc_chains();
2220 
2221         return 1;
2222 }
2223 
2224 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2225                 struct held_lock *hlock, int chain_head, u64 chain_key)
2226 {
2227         /*
2228          * Trylock needs to maintain the stack of held locks, but it
2229          * does not add new dependencies, because trylock can be done
2230          * in any order.
2231          *
2232          * We look up the chain_key and do the O(N^2) check and update of
2233          * the dependencies only if this is a new dependency chain.
2234          * (If lookup_chain_cache() returns with 1 it acquires
2235          * graph_lock for us)
2236          */
2237         if (!hlock->trylock && hlock->check &&
2238             lookup_chain_cache(curr, hlock, chain_key)) {
2239                 /*
2240                  * Check whether last held lock:
2241                  *
2242                  * - is irq-safe, if this lock is irq-unsafe
2243                  * - is softirq-safe, if this lock is hardirq-unsafe
2244                  *
2245                  * And check whether the new lock's dependency graph
2246                  * could lead back to the previous lock.
2247                  *
2248                  * any of these scenarios could lead to a deadlock. If
2249                  * All validations
2250                  */
2251                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2252 
2253                 if (!ret)
2254                         return 0;
2255                 /*
2256                  * Mark recursive read, as we jump over it when
2257                  * building dependencies (just like we jump over
2258                  * trylock entries):
2259                  */
2260                 if (ret == 2)
2261                         hlock->read = 2;
2262                 /*
2263                  * Add dependency only if this lock is not the head
2264                  * of the chain, and if it's not a secondary read-lock:
2265                  */
2266                 if (!chain_head && ret != 2)
2267                         if (!check_prevs_add(curr, hlock))
2268                                 return 0;
2269                 graph_unlock();
2270         } else
2271                 /* after lookup_chain_cache(): */
2272                 if (unlikely(!debug_locks))
2273                         return 0;
2274 
2275         return 1;
2276 }
2277 #else
2278 static inline int validate_chain(struct task_struct *curr,
2279                 struct lockdep_map *lock, struct held_lock *hlock,
2280                 int chain_head, u64 chain_key)
2281 {
2282         return 1;
2283 }
2284 #endif
2285 
2286 /*
2287  * We are building curr_chain_key incrementally, so double-check
2288  * it from scratch, to make sure that it's done correctly:
2289  */
2290 static void check_chain_key(struct task_struct *curr)
2291 {
2292 #ifdef CONFIG_DEBUG_LOCKDEP
2293         struct held_lock *hlock, *prev_hlock = NULL;
2294         unsigned int i;
2295         u64 chain_key = 0;
2296 
2297         for (i = 0; i < curr->lockdep_depth; i++) {
2298                 hlock = curr->held_locks + i;
2299                 if (chain_key != hlock->prev_chain_key) {
2300                         debug_locks_off();
2301                         /*
2302                          * We got mighty confused, our chain keys don't match
2303                          * with what we expect, someone trample on our task state?
2304                          */
2305                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2306                                 curr->lockdep_depth, i,
2307                                 (unsigned long long)chain_key,
2308                                 (unsigned long long)hlock->prev_chain_key);
2309                         return;
2310                 }
2311                 /*
2312                  * Whoops ran out of static storage again?
2313                  */
2314                 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2315                         return;
2316 
2317                 if (prev_hlock && (prev_hlock->irq_context !=
2318                                                         hlock->irq_context))
2319                         chain_key = 0;
2320                 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2321                 prev_hlock = hlock;
2322         }
2323         if (chain_key != curr->curr_chain_key) {
2324                 debug_locks_off();
2325                 /*
2326                  * More smoking hash instead of calculating it, damn see these
2327                  * numbers float.. I bet that a pink elephant stepped on my memory.
2328                  */
2329                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2330                         curr->lockdep_depth, i,
2331                         (unsigned long long)chain_key,
2332                         (unsigned long long)curr->curr_chain_key);
2333         }
2334 #endif
2335 }
2336 
2337 static void
2338 print_usage_bug_scenario(struct held_lock *lock)
2339 {
2340         struct lock_class *class = hlock_class(lock);
2341 
2342         printk(" Possible unsafe locking scenario:\n\n");
2343         printk("       CPU0\n");
2344         printk("       ----\n");
2345         printk("  lock(");
2346         __print_lock_name(class);
2347         printk(KERN_CONT ");\n");
2348         printk("  <Interrupt>\n");
2349         printk("    lock(");
2350         __print_lock_name(class);
2351         printk(KERN_CONT ");\n");
2352         printk("\n *** DEADLOCK ***\n\n");
2353 }
2354 
2355 static int
2356 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2357                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2358 {
2359         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2360                 return 0;
2361 
2362         printk("\n");
2363         printk("=================================\n");
2364         printk("[ INFO: inconsistent lock state ]\n");
2365         print_kernel_ident();
2366         printk("---------------------------------\n");
2367 
2368         printk("inconsistent {%s} -> {%s} usage.\n",
2369                 usage_str[prev_bit], usage_str[new_bit]);
2370 
2371         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2372                 curr->comm, task_pid_nr(curr),
2373                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2374                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2375                 trace_hardirqs_enabled(curr),
2376                 trace_softirqs_enabled(curr));
2377         print_lock(this);
2378 
2379         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2380         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2381 
2382         print_irqtrace_events(curr);
2383         printk("\nother info that might help us debug this:\n");
2384         print_usage_bug_scenario(this);
2385 
2386         lockdep_print_held_locks(curr);
2387 
2388         printk("\nstack backtrace:\n");
2389         dump_stack();
2390 
2391         return 0;
2392 }
2393 
2394 /*
2395  * Print out an error if an invalid bit is set:
2396  */
2397 static inline int
2398 valid_state(struct task_struct *curr, struct held_lock *this,
2399             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2400 {
2401         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2402                 return print_usage_bug(curr, this, bad_bit, new_bit);
2403         return 1;
2404 }
2405 
2406 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2407                      enum lock_usage_bit new_bit);
2408 
2409 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2410 
2411 /*
2412  * print irq inversion bug:
2413  */
2414 static int
2415 print_irq_inversion_bug(struct task_struct *curr,
2416                         struct lock_list *root, struct lock_list *other,
2417                         struct held_lock *this, int forwards,
2418                         const char *irqclass)
2419 {
2420         struct lock_list *entry = other;
2421         struct lock_list *middle = NULL;
2422         int depth;
2423 
2424         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2425                 return 0;
2426 
2427         printk("\n");
2428         printk("=========================================================\n");
2429         printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2430         print_kernel_ident();
2431         printk("---------------------------------------------------------\n");
2432         printk("%s/%d just changed the state of lock:\n",
2433                 curr->comm, task_pid_nr(curr));
2434         print_lock(this);
2435         if (forwards)
2436                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2437         else
2438                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2439         print_lock_name(other->class);
2440         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2441 
2442         printk("\nother info that might help us debug this:\n");
2443 
2444         /* Find a middle lock (if one exists) */
2445         depth = get_lock_depth(other);
2446         do {
2447                 if (depth == 0 && (entry != root)) {
2448                         printk("lockdep:%s bad path found in chain graph\n", __func__);
2449                         break;
2450                 }
2451                 middle = entry;
2452                 entry = get_lock_parent(entry);
2453                 depth--;
2454         } while (entry && entry != root && (depth >= 0));
2455         if (forwards)
2456                 print_irq_lock_scenario(root, other,
2457                         middle ? middle->class : root->class, other->class);
2458         else
2459                 print_irq_lock_scenario(other, root,
2460                         middle ? middle->class : other->class, root->class);
2461 
2462         lockdep_print_held_locks(curr);
2463 
2464         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2465         if (!save_trace(&root->trace))
2466                 return 0;
2467         print_shortest_lock_dependencies(other, root);
2468 
2469         printk("\nstack backtrace:\n");
2470         dump_stack();
2471 
2472         return 0;
2473 }
2474 
2475 /*
2476  * Prove that in the forwards-direction subgraph starting at <this>
2477  * there is no lock matching <mask>:
2478  */
2479 static int
2480 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2481                      enum lock_usage_bit bit, const char *irqclass)
2482 {
2483         int ret;
2484         struct lock_list root;
2485         struct lock_list *uninitialized_var(target_entry);
2486 
2487         root.parent = NULL;
2488         root.class = hlock_class(this);
2489         ret = find_usage_forwards(&root, bit, &target_entry);
2490         if (ret < 0)
2491                 return print_bfs_bug(ret);
2492         if (ret == 1)
2493                 return ret;
2494 
2495         return print_irq_inversion_bug(curr, &root, target_entry,
2496                                         this, 1, irqclass);
2497 }
2498 
2499 /*
2500  * Prove that in the backwards-direction subgraph starting at <this>
2501  * there is no lock matching <mask>:
2502  */
2503 static int
2504 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2505                       enum lock_usage_bit bit, const char *irqclass)
2506 {
2507         int ret;
2508         struct lock_list root;
2509         struct lock_list *uninitialized_var(target_entry);
2510 
2511         root.parent = NULL;
2512         root.class = hlock_class(this);
2513         ret = find_usage_backwards(&root, bit, &target_entry);
2514         if (ret < 0)
2515                 return print_bfs_bug(ret);
2516         if (ret == 1)
2517                 return ret;
2518 
2519         return print_irq_inversion_bug(curr, &root, target_entry,
2520                                         this, 0, irqclass);
2521 }
2522 
2523 void print_irqtrace_events(struct task_struct *curr)
2524 {
2525         printk("irq event stamp: %u\n", curr->irq_events);
2526         printk("hardirqs last  enabled at (%u): [<%p>] %pS\n",
2527                 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
2528                 (void *)curr->hardirq_enable_ip);
2529         printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
2530                 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
2531                 (void *)curr->hardirq_disable_ip);
2532         printk("softirqs last  enabled at (%u): [<%p>] %pS\n",
2533                 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
2534                 (void *)curr->softirq_enable_ip);
2535         printk("softirqs last disabled at (%u): [<%p>] %pS\n",
2536                 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
2537                 (void *)curr->softirq_disable_ip);
2538 }
2539 
2540 static int HARDIRQ_verbose(struct lock_class *class)
2541 {
2542 #if HARDIRQ_VERBOSE
2543         return class_filter(class);
2544 #endif
2545         return 0;
2546 }
2547 
2548 static int SOFTIRQ_verbose(struct lock_class *class)
2549 {
2550 #if SOFTIRQ_VERBOSE
2551         return class_filter(class);
2552 #endif
2553         return 0;
2554 }
2555 
2556 static int RECLAIM_FS_verbose(struct lock_class *class)
2557 {
2558 #if RECLAIM_VERBOSE
2559         return class_filter(class);
2560 #endif
2561         return 0;
2562 }
2563 
2564 #define STRICT_READ_CHECKS      1
2565 
2566 static int (*state_verbose_f[])(struct lock_class *class) = {
2567 #define LOCKDEP_STATE(__STATE) \
2568         __STATE##_verbose,
2569 #include "lockdep_states.h"
2570 #undef LOCKDEP_STATE
2571 };
2572 
2573 static inline int state_verbose(enum lock_usage_bit bit,
2574                                 struct lock_class *class)
2575 {
2576         return state_verbose_f[bit >> 2](class);
2577 }
2578 
2579 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2580                              enum lock_usage_bit bit, const char *name);
2581 
2582 static int
2583 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2584                 enum lock_usage_bit new_bit)
2585 {
2586         int excl_bit = exclusive_bit(new_bit);
2587         int read = new_bit & 1;
2588         int dir = new_bit & 2;
2589 
2590         /*
2591          * mark USED_IN has to look forwards -- to ensure no dependency
2592          * has ENABLED state, which would allow recursion deadlocks.
2593          *
2594          * mark ENABLED has to look backwards -- to ensure no dependee
2595          * has USED_IN state, which, again, would allow  recursion deadlocks.
2596          */
2597         check_usage_f usage = dir ?
2598                 check_usage_backwards : check_usage_forwards;
2599 
2600         /*
2601          * Validate that this particular lock does not have conflicting
2602          * usage states.
2603          */
2604         if (!valid_state(curr, this, new_bit, excl_bit))
2605                 return 0;
2606 
2607         /*
2608          * Validate that the lock dependencies don't have conflicting usage
2609          * states.
2610          */
2611         if ((!read || !dir || STRICT_READ_CHECKS) &&
2612                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2613                 return 0;
2614 
2615         /*
2616          * Check for read in write conflicts
2617          */
2618         if (!read) {
2619                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2620                         return 0;
2621 
2622                 if (STRICT_READ_CHECKS &&
2623                         !usage(curr, this, excl_bit + 1,
2624                                 state_name(new_bit + 1)))
2625                         return 0;
2626         }
2627 
2628         if (state_verbose(new_bit, hlock_class(this)))
2629                 return 2;
2630 
2631         return 1;
2632 }
2633 
2634 enum mark_type {
2635 #define LOCKDEP_STATE(__STATE)  __STATE,
2636 #include "lockdep_states.h"
2637 #undef LOCKDEP_STATE
2638 };
2639 
2640 /*
2641  * Mark all held locks with a usage bit:
2642  */
2643 static int
2644 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2645 {
2646         enum lock_usage_bit usage_bit;
2647         struct held_lock *hlock;
2648         int i;
2649 
2650         for (i = 0; i < curr->lockdep_depth; i++) {
2651                 hlock = curr->held_locks + i;
2652 
2653                 usage_bit = 2 + (mark << 2); /* ENABLED */
2654                 if (hlock->read)
2655                         usage_bit += 1; /* READ */
2656 
2657                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2658 
2659                 if (!hlock->check)
2660                         continue;
2661 
2662                 if (!mark_lock(curr, hlock, usage_bit))
2663                         return 0;
2664         }
2665 
2666         return 1;
2667 }
2668 
2669 /*
2670  * Hardirqs will be enabled:
2671  */
2672 static void __trace_hardirqs_on_caller(unsigned long ip)
2673 {
2674         struct task_struct *curr = current;
2675 
2676         /* we'll do an OFF -> ON transition: */
2677         curr->hardirqs_enabled = 1;
2678 
2679         /*
2680          * We are going to turn hardirqs on, so set the
2681          * usage bit for all held locks:
2682          */
2683         if (!mark_held_locks(curr, HARDIRQ))
2684                 return;
2685         /*
2686          * If we have softirqs enabled, then set the usage
2687          * bit for all held locks. (disabled hardirqs prevented
2688          * this bit from being set before)
2689          */
2690         if (curr->softirqs_enabled)
2691                 if (!mark_held_locks(curr, SOFTIRQ))
2692                         return;
2693 
2694         curr->hardirq_enable_ip = ip;
2695         curr->hardirq_enable_event = ++curr->irq_events;
2696         debug_atomic_inc(hardirqs_on_events);
2697 }
2698 
2699 __visible void trace_hardirqs_on_caller(unsigned long ip)
2700 {
2701         time_hardirqs_on(CALLER_ADDR0, ip);
2702 
2703         if (unlikely(!debug_locks || current->lockdep_recursion))
2704                 return;
2705 
2706         if (unlikely(current->hardirqs_enabled)) {
2707                 /*
2708                  * Neither irq nor preemption are disabled here
2709                  * so this is racy by nature but losing one hit
2710                  * in a stat is not a big deal.
2711                  */
2712                 __debug_atomic_inc(redundant_hardirqs_on);
2713                 return;
2714         }
2715 
2716         /*
2717          * We're enabling irqs and according to our state above irqs weren't
2718          * already enabled, yet we find the hardware thinks they are in fact
2719          * enabled.. someone messed up their IRQ state tracing.
2720          */
2721         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2722                 return;
2723 
2724         /*
2725          * See the fine text that goes along with this variable definition.
2726          */
2727         if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2728                 return;
2729 
2730         /*
2731          * Can't allow enabling interrupts while in an interrupt handler,
2732          * that's general bad form and such. Recursion, limited stack etc..
2733          */
2734         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2735                 return;
2736 
2737         current->lockdep_recursion = 1;
2738         __trace_hardirqs_on_caller(ip);
2739         current->lockdep_recursion = 0;
2740 }
2741 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2742 
2743 void trace_hardirqs_on(void)
2744 {
2745         trace_hardirqs_on_caller(CALLER_ADDR0);
2746 }
2747 EXPORT_SYMBOL(trace_hardirqs_on);
2748 
2749 /*
2750  * Hardirqs were disabled:
2751  */
2752 __visible void trace_hardirqs_off_caller(unsigned long ip)
2753 {
2754         struct task_struct *curr = current;
2755 
2756         time_hardirqs_off(CALLER_ADDR0, ip);
2757 
2758         if (unlikely(!debug_locks || current->lockdep_recursion))
2759                 return;
2760 
2761         /*
2762          * So we're supposed to get called after you mask local IRQs, but for
2763          * some reason the hardware doesn't quite think you did a proper job.
2764          */
2765         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2766                 return;
2767 
2768         if (curr->hardirqs_enabled) {
2769                 /*
2770                  * We have done an ON -> OFF transition:
2771                  */
2772                 curr->hardirqs_enabled = 0;
2773                 curr->hardirq_disable_ip = ip;
2774                 curr->hardirq_disable_event = ++curr->irq_events;
2775                 debug_atomic_inc(hardirqs_off_events);
2776         } else
2777                 debug_atomic_inc(redundant_hardirqs_off);
2778 }
2779 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2780 
2781 void trace_hardirqs_off(void)
2782 {
2783         trace_hardirqs_off_caller(CALLER_ADDR0);
2784 }
2785 EXPORT_SYMBOL(trace_hardirqs_off);
2786 
2787 /*
2788  * Softirqs will be enabled:
2789  */
2790 void trace_softirqs_on(unsigned long ip)
2791 {
2792         struct task_struct *curr = current;
2793 
2794         if (unlikely(!debug_locks || current->lockdep_recursion))
2795                 return;
2796 
2797         /*
2798          * We fancy IRQs being disabled here, see softirq.c, avoids
2799          * funny state and nesting things.
2800          */
2801         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2802                 return;
2803 
2804         if (curr->softirqs_enabled) {
2805                 debug_atomic_inc(redundant_softirqs_on);
2806                 return;
2807         }
2808 
2809         current->lockdep_recursion = 1;
2810         /*
2811          * We'll do an OFF -> ON transition:
2812          */
2813         curr->softirqs_enabled = 1;
2814         curr->softirq_enable_ip = ip;
2815         curr->softirq_enable_event = ++curr->irq_events;
2816         debug_atomic_inc(softirqs_on_events);
2817         /*
2818          * We are going to turn softirqs on, so set the
2819          * usage bit for all held locks, if hardirqs are
2820          * enabled too:
2821          */
2822         if (curr->hardirqs_enabled)
2823                 mark_held_locks(curr, SOFTIRQ);
2824         current->lockdep_recursion = 0;
2825 }
2826 
2827 /*
2828  * Softirqs were disabled:
2829  */
2830 void trace_softirqs_off(unsigned long ip)
2831 {
2832         struct task_struct *curr = current;
2833 
2834         if (unlikely(!debug_locks || current->lockdep_recursion))
2835                 return;
2836 
2837         /*
2838          * We fancy IRQs being disabled here, see softirq.c
2839          */
2840         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2841                 return;
2842 
2843         if (curr->softirqs_enabled) {
2844                 /*
2845                  * We have done an ON -> OFF transition:
2846                  */
2847                 curr->softirqs_enabled = 0;
2848                 curr->softirq_disable_ip = ip;
2849                 curr->softirq_disable_event = ++curr->irq_events;
2850                 debug_atomic_inc(softirqs_off_events);
2851                 /*
2852                  * Whoops, we wanted softirqs off, so why aren't they?
2853                  */
2854                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2855         } else
2856                 debug_atomic_inc(redundant_softirqs_off);
2857 }
2858 
2859 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2860 {
2861         struct task_struct *curr = current;
2862 
2863         if (unlikely(!debug_locks))
2864                 return;
2865 
2866         /* no reclaim without waiting on it */
2867         if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2868                 return;
2869 
2870         /* this guy won't enter reclaim */
2871         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2872                 return;
2873 
2874         /* We're only interested __GFP_FS allocations for now */
2875         if (!(gfp_mask & __GFP_FS))
2876                 return;
2877 
2878         /*
2879          * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2880          */
2881         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2882                 return;
2883 
2884         mark_held_locks(curr, RECLAIM_FS);
2885 }
2886 
2887 static void check_flags(unsigned long flags);
2888 
2889 void lockdep_trace_alloc(gfp_t gfp_mask)
2890 {
2891         unsigned long flags;
2892 
2893         if (unlikely(current->lockdep_recursion))
2894                 return;
2895 
2896         raw_local_irq_save(flags);
2897         check_flags(flags);
2898         current->lockdep_recursion = 1;
2899         __lockdep_trace_alloc(gfp_mask, flags);
2900         current->lockdep_recursion = 0;
2901         raw_local_irq_restore(flags);
2902 }
2903 
2904 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2905 {
2906         /*
2907          * If non-trylock use in a hardirq or softirq context, then
2908          * mark the lock as used in these contexts:
2909          */
2910         if (!hlock->trylock) {
2911                 if (hlock->read) {
2912                         if (curr->hardirq_context)
2913                                 if (!mark_lock(curr, hlock,
2914                                                 LOCK_USED_IN_HARDIRQ_READ))
2915                                         return 0;
2916                         if (curr->softirq_context)
2917                                 if (!mark_lock(curr, hlock,
2918                                                 LOCK_USED_IN_SOFTIRQ_READ))
2919                                         return 0;
2920                 } else {
2921                         if (curr->hardirq_context)
2922                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2923                                         return 0;
2924                         if (curr->softirq_context)
2925                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2926                                         return 0;
2927                 }
2928         }
2929         if (!hlock->hardirqs_off) {
2930                 if (hlock->read) {
2931                         if (!mark_lock(curr, hlock,
2932                                         LOCK_ENABLED_HARDIRQ_READ))
2933                                 return 0;
2934                         if (curr->softirqs_enabled)
2935                                 if (!mark_lock(curr, hlock,
2936                                                 LOCK_ENABLED_SOFTIRQ_READ))
2937                                         return 0;
2938                 } else {
2939                         if (!mark_lock(curr, hlock,
2940                                         LOCK_ENABLED_HARDIRQ))
2941                                 return 0;
2942                         if (curr->softirqs_enabled)
2943                                 if (!mark_lock(curr, hlock,
2944                                                 LOCK_ENABLED_SOFTIRQ))
2945                                         return 0;
2946                 }
2947         }
2948 
2949         /*
2950          * We reuse the irq context infrastructure more broadly as a general
2951          * context checking code. This tests GFP_FS recursion (a lock taken
2952          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2953          * allocation).
2954          */
2955         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2956                 if (hlock->read) {
2957                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2958                                         return 0;
2959                 } else {
2960                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2961                                         return 0;
2962                 }
2963         }
2964 
2965         return 1;
2966 }
2967 
2968 static inline unsigned int task_irq_context(struct task_struct *task)
2969 {
2970         return 2 * !!task->hardirq_context + !!task->softirq_context;
2971 }
2972 
2973 static int separate_irq_context(struct task_struct *curr,
2974                 struct held_lock *hlock)
2975 {
2976         unsigned int depth = curr->lockdep_depth;
2977 
2978         /*
2979          * Keep track of points where we cross into an interrupt context:
2980          */
2981         if (depth) {
2982                 struct held_lock *prev_hlock;
2983 
2984                 prev_hlock = curr->held_locks + depth-1;
2985                 /*
2986                  * If we cross into another context, reset the
2987                  * hash key (this also prevents the checking and the
2988                  * adding of the dependency to 'prev'):
2989                  */
2990                 if (prev_hlock->irq_context != hlock->irq_context)
2991                         return 1;
2992         }
2993         return 0;
2994 }
2995 
2996 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2997 
2998 static inline
2999 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
3000                 enum lock_usage_bit new_bit)
3001 {
3002         WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3003         return 1;
3004 }
3005 
3006 static inline int mark_irqflags(struct task_struct *curr,
3007                 struct held_lock *hlock)
3008 {
3009         return 1;
3010 }
3011 
3012 static inline unsigned int task_irq_context(struct task_struct *task)
3013 {
3014         return 0;
3015 }
3016 
3017 static inline int separate_irq_context(struct task_struct *curr,
3018                 struct held_lock *hlock)
3019 {
3020         return 0;
3021 }
3022 
3023 void lockdep_trace_alloc(gfp_t gfp_mask)
3024 {
3025 }
3026 
3027 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3028 
3029 /*
3030  * Mark a lock with a usage bit, and validate the state transition:
3031  */
3032 static int mark_lock(struct task_struct *curr, struct held_lock *this,
3033                              enum lock_usage_bit new_bit)
3034 {
3035         unsigned int new_mask = 1 << new_bit, ret = 1;
3036 
3037         /*
3038          * If already set then do not dirty the cacheline,
3039          * nor do any checks:
3040          */
3041         if (likely(hlock_class(this)->usage_mask & new_mask))
3042                 return 1;
3043 
3044         if (!graph_lock())
3045                 return 0;
3046         /*
3047          * Make sure we didn't race:
3048          */
3049         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3050                 graph_unlock();
3051                 return 1;
3052         }
3053 
3054         hlock_class(this)->usage_mask |= new_mask;
3055 
3056         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3057                 return 0;
3058 
3059         switch (new_bit) {
3060 #define LOCKDEP_STATE(__STATE)                  \
3061         case LOCK_USED_IN_##__STATE:            \
3062         case LOCK_USED_IN_##__STATE##_READ:     \
3063         case LOCK_ENABLED_##__STATE:            \
3064         case LOCK_ENABLED_##__STATE##_READ:
3065 #include "lockdep_states.h"
3066 #undef LOCKDEP_STATE
3067                 ret = mark_lock_irq(curr, this, new_bit);
3068                 if (!ret)
3069                         return 0;
3070                 break;
3071         case LOCK_USED:
3072                 debug_atomic_dec(nr_unused_locks);
3073                 break;
3074         default:
3075                 if (!debug_locks_off_graph_unlock())
3076                         return 0;
3077                 WARN_ON(1);
3078                 return 0;
3079         }
3080 
3081         graph_unlock();
3082 
3083         /*
3084          * We must printk outside of the graph_lock:
3085          */
3086         if (ret == 2) {
3087                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3088                 print_lock(this);
3089                 print_irqtrace_events(curr);
3090                 dump_stack();
3091         }
3092 
3093         return ret;
3094 }
3095 
3096 /*
3097  * Initialize a lock instance's lock-class mapping info:
3098  */
3099 void lockdep_init_map(struct lockdep_map *lock, const char *name,
3100                       struct lock_class_key *key, int subclass)
3101 {
3102         int i;
3103 
3104         kmemcheck_mark_initialized(lock, sizeof(*lock));
3105 
3106         for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3107                 lock->class_cache[i] = NULL;
3108 
3109 #ifdef CONFIG_LOCK_STAT
3110         lock->cpu = raw_smp_processor_id();
3111 #endif
3112 
3113         /*
3114          * Can't be having no nameless bastards around this place!
3115          */
3116         if (DEBUG_LOCKS_WARN_ON(!name)) {
3117                 lock->name = "NULL";
3118                 return;
3119         }
3120 
3121         lock->name = name;
3122 
3123         /*
3124          * No key, no joy, we need to hash something.
3125          */
3126         if (DEBUG_LOCKS_WARN_ON(!key))
3127                 return;
3128         /*
3129          * Sanity check, the lock-class key must be persistent:
3130          */
3131         if (!static_obj(key)) {
3132                 printk("BUG: key %p not in .data!\n", key);
3133                 /*
3134                  * What it says above ^^^^^, I suggest you read it.
3135                  */
3136                 DEBUG_LOCKS_WARN_ON(1);
3137                 return;
3138         }
3139         lock->key = key;
3140 
3141         if (unlikely(!debug_locks))
3142                 return;
3143 
3144         if (subclass) {
3145                 unsigned long flags;
3146 
3147                 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3148                         return;
3149 
3150                 raw_local_irq_save(flags);
3151                 current->lockdep_recursion = 1;
3152                 register_lock_class(lock, subclass, 1);
3153                 current->lockdep_recursion = 0;
3154                 raw_local_irq_restore(flags);
3155         }
3156 }
3157 EXPORT_SYMBOL_GPL(lockdep_init_map);
3158 
3159 struct lock_class_key __lockdep_no_validate__;
3160 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3161 
3162 static int
3163 print_lock_nested_lock_not_held(struct task_struct *curr,
3164                                 struct held_lock *hlock,
3165                                 unsigned long ip)
3166 {
3167         if (!debug_locks_off())
3168                 return 0;
3169         if (debug_locks_silent)
3170                 return 0;
3171 
3172         printk("\n");
3173         printk("==================================\n");
3174         printk("[ BUG: Nested lock was not taken ]\n");
3175         print_kernel_ident();
3176         printk("----------------------------------\n");
3177 
3178         printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3179         print_lock(hlock);
3180 
3181         printk("\nbut this task is not holding:\n");
3182         printk("%s\n", hlock->nest_lock->name);
3183 
3184         printk("\nstack backtrace:\n");
3185         dump_stack();
3186 
3187         printk("\nother info that might help us debug this:\n");
3188         lockdep_print_held_locks(curr);
3189 
3190         printk("\nstack backtrace:\n");
3191         dump_stack();
3192 
3193         return 0;
3194 }
3195 
3196 static int __lock_is_held(struct lockdep_map *lock, int read);
3197 
3198 /*
3199  * This gets called for every mutex_lock*()/spin_lock*() operation.
3200  * We maintain the dependency maps and validate the locking attempt:
3201  */
3202 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3203                           int trylock, int read, int check, int hardirqs_off,
3204                           struct lockdep_map *nest_lock, unsigned long ip,
3205                           int references, int pin_count)
3206 {
3207         struct task_struct *curr = current;
3208         struct lock_class *class = NULL;
3209         struct held_lock *hlock;
3210         unsigned int depth;
3211         int chain_head = 0;
3212         int class_idx;
3213         u64 chain_key;
3214 
3215         if (unlikely(!debug_locks))
3216                 return 0;
3217 
3218         /*
3219          * Lockdep should run with IRQs disabled, otherwise we could
3220          * get an interrupt which would want to take locks, which would
3221          * end up in lockdep and have you got a head-ache already?
3222          */
3223         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3224                 return 0;
3225 
3226         if (!prove_locking || lock->key == &__lockdep_no_validate__)
3227                 check = 0;
3228 
3229         if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3230                 class = lock->class_cache[subclass];
3231         /*
3232          * Not cached?
3233          */
3234         if (unlikely(!class)) {
3235                 class = register_lock_class(lock, subclass, 0);
3236                 if (!class)
3237                         return 0;
3238         }
3239         atomic_inc((atomic_t *)&class->ops);
3240         if (very_verbose(class)) {
3241                 printk("\nacquire class [%p] %s", class->key, class->name);
3242                 if (class->name_version > 1)
3243                         printk(KERN_CONT "#%d", class->name_version);
3244                 printk(KERN_CONT "\n");
3245                 dump_stack();
3246         }
3247 
3248         /*
3249          * Add the lock to the list of currently held locks.
3250          * (we dont increase the depth just yet, up until the
3251          * dependency checks are done)
3252          */
3253         depth = curr->lockdep_depth;
3254         /*
3255          * Ran out of static storage for our per-task lock stack again have we?
3256          */
3257         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3258                 return 0;
3259 
3260         class_idx = class - lock_classes + 1;
3261 
3262         if (depth) {
3263                 hlock = curr->held_locks + depth - 1;
3264                 if (hlock->class_idx == class_idx && nest_lock) {
3265                         if (hlock->references) {
3266                                 /*
3267                                  * Check: unsigned int references:12, overflow.
3268                                  */
3269                                 if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1))
3270                                         return 0;
3271 
3272                                 hlock->references++;
3273                         } else {
3274                                 hlock->references = 2;
3275                         }
3276 
3277                         return 1;
3278                 }
3279         }
3280 
3281         hlock = curr->held_locks + depth;
3282         /*
3283          * Plain impossible, we just registered it and checked it weren't no
3284          * NULL like.. I bet this mushroom I ate was good!
3285          */
3286         if (DEBUG_LOCKS_WARN_ON(!class))
3287                 return 0;
3288         hlock->class_idx = class_idx;
3289         hlock->acquire_ip = ip;
3290         hlock->instance = lock;
3291         hlock->nest_lock = nest_lock;
3292         hlock->irq_context = task_irq_context(curr);
3293         hlock->trylock = trylock;
3294         hlock->read = read;
3295         hlock->check = check;
3296         hlock->hardirqs_off = !!hardirqs_off;
3297         hlock->references = references;
3298 #ifdef CONFIG_LOCK_STAT
3299         hlock->waittime_stamp = 0;
3300         hlock->holdtime_stamp = lockstat_clock();
3301 #endif
3302         hlock->pin_count = pin_count;
3303 
3304         if (check && !mark_irqflags(curr, hlock))
3305                 return 0;
3306 
3307         /* mark it as used: */
3308         if (!mark_lock(curr, hlock, LOCK_USED))
3309                 return 0;
3310 
3311         /*
3312          * Calculate the chain hash: it's the combined hash of all the
3313          * lock keys along the dependency chain. We save the hash value
3314          * at every step so that we can get the current hash easily
3315          * after unlock. The chain hash is then used to cache dependency
3316          * results.
3317          *
3318          * The 'key ID' is what is the most compact key value to drive
3319          * the hash, not class->key.
3320          */
3321         /*
3322          * Whoops, we did it again.. ran straight out of our static allocation.
3323          */
3324         if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3325                 return 0;
3326 
3327         chain_key = curr->curr_chain_key;
3328         if (!depth) {
3329                 /*
3330                  * How can we have a chain hash when we ain't got no keys?!
3331                  */
3332                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3333                         return 0;
3334                 chain_head = 1;
3335         }
3336 
3337         hlock->prev_chain_key = chain_key;
3338         if (separate_irq_context(curr, hlock)) {
3339                 chain_key = 0;
3340                 chain_head = 1;
3341         }
3342         chain_key = iterate_chain_key(chain_key, class_idx);
3343 
3344         if (nest_lock && !__lock_is_held(nest_lock, -1))
3345                 return print_lock_nested_lock_not_held(curr, hlock, ip);
3346 
3347         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3348                 return 0;
3349 
3350         curr->curr_chain_key = chain_key;
3351         curr->lockdep_depth++;
3352         check_chain_key(curr);
3353 #ifdef CONFIG_DEBUG_LOCKDEP
3354         if (unlikely(!debug_locks))
3355                 return 0;
3356 #endif
3357         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3358                 debug_locks_off();
3359                 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3360                 printk(KERN_DEBUG "depth: %i  max: %lu!\n",
3361                        curr->lockdep_depth, MAX_LOCK_DEPTH);
3362 
3363                 lockdep_print_held_locks(current);
3364                 debug_show_all_locks();
3365                 dump_stack();
3366 
3367                 return 0;
3368         }
3369 
3370         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3371                 max_lockdep_depth = curr->lockdep_depth;
3372 
3373         return 1;
3374 }
3375 
3376 static int
3377 print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3378                            unsigned long ip)
3379 {
3380         if (!debug_locks_off())
3381                 return 0;
3382         if (debug_locks_silent)
3383                 return 0;
3384 
3385         printk("\n");
3386         printk("=====================================\n");
3387         printk("[ BUG: bad unlock balance detected! ]\n");
3388         print_kernel_ident();
3389         printk("-------------------------------------\n");
3390         printk("%s/%d is trying to release lock (",
3391                 curr->comm, task_pid_nr(curr));
3392         print_lockdep_cache(lock);
3393         printk(KERN_CONT ") at:\n");
3394         print_ip_sym(ip);
3395         printk("but there are no more locks to release!\n");
3396         printk("\nother info that might help us debug this:\n");
3397         lockdep_print_held_locks(curr);
3398 
3399         printk("\nstack backtrace:\n");
3400         dump_stack();
3401 
3402         return 0;
3403 }
3404 
3405 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3406 {
3407         if (hlock->instance == lock)
3408                 return 1;
3409 
3410         if (hlock->references) {
3411                 struct lock_class *class = lock->class_cache[0];
3412 
3413                 if (!class)
3414                         class = look_up_lock_class(lock, 0);
3415 
3416                 /*
3417                  * If look_up_lock_class() failed to find a class, we're trying
3418                  * to test if we hold a lock that has never yet been acquired.
3419                  * Clearly if the lock hasn't been acquired _ever_, we're not
3420                  * holding it either, so report failure.
3421                  */
3422                 if (!class)
3423                         return 0;
3424 
3425                 /*
3426                  * References, but not a lock we're actually ref-counting?
3427                  * State got messed up, follow the sites that change ->references
3428                  * and try to make sense of it.
3429                  */
3430                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3431                         return 0;
3432 
3433                 if (hlock->class_idx == class - lock_classes + 1)
3434                         return 1;
3435         }
3436 
3437         return 0;
3438 }
3439 
3440 static int
3441 __lock_set_class(struct lockdep_map *lock, const char *name,
3442                  struct lock_class_key *key, unsigned int subclass,
3443                  unsigned long ip)
3444 {
3445         struct task_struct *curr = current;
3446         struct held_lock *hlock, *prev_hlock;
3447         struct lock_class *class;
3448         unsigned int depth;
3449         int i;
3450 
3451         depth = curr->lockdep_depth;
3452         /*
3453          * This function is about (re)setting the class of a held lock,
3454          * yet we're not actually holding any locks. Naughty user!
3455          */
3456         if (DEBUG_LOCKS_WARN_ON(!depth))
3457                 return 0;
3458 
3459         prev_hlock = NULL;
3460         for (i = depth-1; i >= 0; i--) {
3461                 hlock = curr->held_locks + i;
3462                 /*
3463                  * We must not cross into another context:
3464                  */
3465                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3466                         break;
3467                 if (match_held_lock(hlock, lock))
3468                         goto found_it;
3469                 prev_hlock = hlock;
3470         }
3471         return print_unlock_imbalance_bug(curr, lock, ip);
3472 
3473 found_it:
3474         lockdep_init_map(lock, name, key, 0);
3475         class = register_lock_class(lock, subclass, 0);
3476         hlock->class_idx = class - lock_classes + 1;
3477 
3478         curr->lockdep_depth = i;
3479         curr->curr_chain_key = hlock->prev_chain_key;
3480 
3481         for (; i < depth; i++) {
3482                 hlock = curr->held_locks + i;
3483                 if (!__lock_acquire(hlock->instance,
3484                         hlock_class(hlock)->subclass, hlock->trylock,
3485                                 hlock->read, hlock->check, hlock->hardirqs_off,
3486                                 hlock->nest_lock, hlock->acquire_ip,
3487                                 hlock->references, hlock->pin_count))
3488                         return 0;
3489         }
3490 
3491         /*
3492          * I took it apart and put it back together again, except now I have
3493          * these 'spare' parts.. where shall I put them.
3494          */
3495         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3496                 return 0;
3497         return 1;
3498 }
3499 
3500 /*
3501  * Remove the lock to the list of currently held locks - this gets
3502  * called on mutex_unlock()/spin_unlock*() (or on a failed
3503  * mutex_lock_interruptible()).
3504  *
3505  * @nested is an hysterical artifact, needs a tree wide cleanup.
3506  */
3507 static int
3508 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3509 {
3510         struct task_struct *curr = current;
3511         struct held_lock *hlock, *prev_hlock;
3512         unsigned int depth;
3513         int i;
3514 
3515         if (unlikely(!debug_locks))
3516                 return 0;
3517 
3518         depth = curr->lockdep_depth;
3519         /*
3520          * So we're all set to release this lock.. wait what lock? We don't
3521          * own any locks, you've been drinking again?
3522          */
3523         if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3524                  return print_unlock_imbalance_bug(curr, lock, ip);
3525 
3526         /*
3527          * Check whether the lock exists in the current stack
3528          * of held locks:
3529          */
3530         prev_hlock = NULL;
3531         for (i = depth-1; i >= 0; i--) {
3532                 hlock = curr->held_locks + i;
3533                 /*
3534                  * We must not cross into another context:
3535                  */
3536                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3537                         break;
3538                 if (match_held_lock(hlock, lock))
3539                         goto found_it;
3540                 prev_hlock = hlock;
3541         }
3542         return print_unlock_imbalance_bug(curr, lock, ip);
3543 
3544 found_it:
3545         if (hlock->instance == lock)
3546                 lock_release_holdtime(hlock);
3547 
3548         WARN(hlock->pin_count, "releasing a pinned lock\n");
3549 
3550         if (hlock->references) {
3551                 hlock->references--;
3552                 if (hlock->references) {
3553                         /*
3554                          * We had, and after removing one, still have
3555                          * references, the current lock stack is still
3556                          * valid. We're done!
3557                          */
3558                         return 1;
3559                 }
3560         }
3561 
3562         /*
3563          * We have the right lock to unlock, 'hlock' points to it.
3564          * Now we remove it from the stack, and add back the other
3565          * entries (if any), recalculating the hash along the way:
3566          */
3567 
3568         curr->lockdep_depth = i;
3569         curr->curr_chain_key = hlock->prev_chain_key;
3570 
3571         for (i++; i < depth; i++) {
3572                 hlock = curr->held_locks + i;
3573                 if (!__lock_acquire(hlock->instance,
3574                         hlock_class(hlock)->subclass, hlock->trylock,
3575                                 hlock->read, hlock->check, hlock->hardirqs_off,
3576                                 hlock->nest_lock, hlock->acquire_ip,
3577                                 hlock->references, hlock->pin_count))
3578                         return 0;
3579         }
3580 
3581         /*
3582          * We had N bottles of beer on the wall, we drank one, but now
3583          * there's not N-1 bottles of beer left on the wall...
3584          */
3585         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3586                 return 0;
3587 
3588         return 1;
3589 }
3590 
3591 static int __lock_is_held(struct lockdep_map *lock, int read)
3592 {
3593         struct task_struct *curr = current;
3594         int i;
3595 
3596         for (i = 0; i < curr->lockdep_depth; i++) {
3597                 struct held_lock *hlock = curr->held_locks + i;
3598 
3599                 if (match_held_lock(hlock, lock)) {
3600                         if (read == -1 || hlock->read == read)
3601                                 return 1;
3602 
3603                         return 0;
3604                 }
3605         }
3606 
3607         return 0;
3608 }
3609 
3610 static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
3611 {
3612         struct pin_cookie cookie = NIL_COOKIE;
3613         struct task_struct *curr = current;
3614         int i;
3615 
3616         if (unlikely(!debug_locks))
3617                 return cookie;
3618 
3619         for (i = 0; i < curr->lockdep_depth; i++) {
3620                 struct held_lock *hlock = curr->held_locks + i;
3621 
3622                 if (match_held_lock(hlock, lock)) {
3623                         /*
3624                          * Grab 16bits of randomness; this is sufficient to not
3625                          * be guessable and still allows some pin nesting in
3626                          * our u32 pin_count.
3627                          */
3628                         cookie.val = 1 + (prandom_u32() >> 16);
3629                         hlock->pin_count += cookie.val;
3630                         return cookie;
3631                 }
3632         }
3633 
3634         WARN(1, "pinning an unheld lock\n");
3635         return cookie;
3636 }
3637 
3638 static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3639 {
3640         struct task_struct *curr = current;
3641         int i;
3642 
3643         if (unlikely(!debug_locks))
3644                 return;
3645 
3646         for (i = 0; i < curr->lockdep_depth; i++) {
3647                 struct held_lock *hlock = curr->held_locks + i;
3648 
3649                 if (match_held_lock(hlock, lock)) {
3650                         hlock->pin_count += cookie.val;
3651                         return;
3652                 }
3653         }
3654 
3655         WARN(1, "pinning an unheld lock\n");
3656 }
3657 
3658 static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3659 {
3660         struct task_struct *curr = current;
3661         int i;
3662 
3663         if (unlikely(!debug_locks))
3664                 return;
3665 
3666         for (i = 0; i < curr->lockdep_depth; i++) {
3667                 struct held_lock *hlock = curr->held_locks + i;
3668 
3669                 if (match_held_lock(hlock, lock)) {
3670                         if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3671                                 return;
3672 
3673                         hlock->pin_count -= cookie.val;
3674 
3675                         if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
3676                                 hlock->pin_count = 0;
3677 
3678                         return;
3679                 }
3680         }
3681 
3682         WARN(1, "unpinning an unheld lock\n");
3683 }
3684 
3685 /*
3686  * Check whether we follow the irq-flags state precisely:
3687  */
3688 static void check_flags(unsigned long flags)
3689 {
3690 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3691     defined(CONFIG_TRACE_IRQFLAGS)
3692         if (!debug_locks)
3693                 return;
3694 
3695         if (irqs_disabled_flags(flags)) {
3696                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3697                         printk("possible reason: unannotated irqs-off.\n");
3698                 }
3699         } else {
3700                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3701                         printk("possible reason: unannotated irqs-on.\n");
3702                 }
3703         }
3704 
3705         /*
3706          * We dont accurately track softirq state in e.g.
3707          * hardirq contexts (such as on 4KSTACKS), so only
3708          * check if not in hardirq contexts:
3709          */
3710         if (!hardirq_count()) {
3711                 if (softirq_count()) {
3712                         /* like the above, but with softirqs */
3713                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3714                 } else {
3715                         /* lick the above, does it taste good? */
3716                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3717                 }
3718         }
3719 
3720         if (!debug_locks)
3721                 print_irqtrace_events(current);
3722 #endif
3723 }
3724 
3725 void lock_set_class(struct lockdep_map *lock, const char *name,
3726                     struct lock_class_key *key, unsigned int subclass,
3727                     unsigned long ip)
3728 {
3729         unsigned long flags;
3730 
3731         if (unlikely(current->lockdep_recursion))
3732                 return;
3733 
3734         raw_local_irq_save(flags);
3735         current->lockdep_recursion = 1;
3736         check_flags(flags);
3737         if (__lock_set_class(lock, name, key, subclass, ip))
3738                 check_chain_key(current);
3739         current->lockdep_recursion = 0;
3740         raw_local_irq_restore(flags);
3741 }
3742 EXPORT_SYMBOL_GPL(lock_set_class);
3743 
3744 /*
3745  * We are not always called with irqs disabled - do that here,
3746  * and also avoid lockdep recursion:
3747  */
3748 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3749                           int trylock, int read, int check,
3750                           struct lockdep_map *nest_lock, unsigned long ip)
3751 {
3752         unsigned long flags;
3753 
3754         if (unlikely(current->lockdep_recursion))
3755                 return;
3756 
3757         raw_local_irq_save(flags);
3758         check_flags(flags);
3759 
3760         current->lockdep_recursion = 1;
3761         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3762         __lock_acquire(lock, subclass, trylock, read, check,
3763                        irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3764         current->lockdep_recursion = 0;
3765         raw_local_irq_restore(flags);
3766 }
3767 EXPORT_SYMBOL_GPL(lock_acquire);
3768 
3769 void lock_release(struct lockdep_map *lock, int nested,
3770                           unsigned long ip)
3771 {
3772         unsigned long flags;
3773 
3774         if (unlikely(current->lockdep_recursion))
3775                 return;
3776 
3777         raw_local_irq_save(flags);
3778         check_flags(flags);
3779         current->lockdep_recursion = 1;
3780         trace_lock_release(lock, ip);
3781         if (__lock_release(lock, nested, ip))
3782                 check_chain_key(current);
3783         current->lockdep_recursion = 0;
3784         raw_local_irq_restore(flags);
3785 }
3786 EXPORT_SYMBOL_GPL(lock_release);
3787 
3788 int lock_is_held_type(struct lockdep_map *lock, int read)
3789 {
3790         unsigned long flags;
3791         int ret = 0;
3792 
3793         if (unlikely(current->lockdep_recursion))
3794                 return 1; /* avoid false negative lockdep_assert_held() */
3795 
3796         raw_local_irq_save(flags);
3797         check_flags(flags);
3798 
3799         current->lockdep_recursion = 1;
3800         ret = __lock_is_held(lock, read);
3801         current->lockdep_recursion = 0;
3802         raw_local_irq_restore(flags);
3803 
3804         return ret;
3805 }
3806 EXPORT_SYMBOL_GPL(lock_is_held_type);
3807 
3808 struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
3809 {
3810         struct pin_cookie cookie = NIL_COOKIE;
3811         unsigned long flags;
3812 
3813         if (unlikely(current->lockdep_recursion))
3814                 return cookie;
3815 
3816         raw_local_irq_save(flags);
3817         check_flags(flags);
3818 
3819         current->lockdep_recursion = 1;
3820         cookie = __lock_pin_lock(lock);
3821         current->lockdep_recursion = 0;
3822         raw_local_irq_restore(flags);
3823 
3824         return cookie;
3825 }
3826 EXPORT_SYMBOL_GPL(lock_pin_lock);
3827 
3828 void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3829 {
3830         unsigned long flags;
3831 
3832         if (unlikely(current->lockdep_recursion))
3833                 return;
3834 
3835         raw_local_irq_save(flags);
3836         check_flags(flags);
3837 
3838         current->lockdep_recursion = 1;
3839         __lock_repin_lock(lock, cookie);
3840         current->lockdep_recursion = 0;
3841         raw_local_irq_restore(flags);
3842 }
3843 EXPORT_SYMBOL_GPL(lock_repin_lock);
3844 
3845 void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3846 {
3847         unsigned long flags;
3848 
3849         if (unlikely(current->lockdep_recursion))
3850                 return;
3851 
3852         raw_local_irq_save(flags);
3853         check_flags(flags);
3854 
3855         current->lockdep_recursion = 1;
3856         __lock_unpin_lock(lock, cookie);
3857         current->lockdep_recursion = 0;
3858         raw_local_irq_restore(flags);
3859 }
3860 EXPORT_SYMBOL_GPL(lock_unpin_lock);
3861 
3862 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3863 {
3864         current->lockdep_reclaim_gfp = gfp_mask;
3865 }
3866 
3867 void lockdep_clear_current_reclaim_state(void)
3868 {
3869         current->lockdep_reclaim_gfp = 0;
3870 }
3871 
3872 #ifdef CONFIG_LOCK_STAT
3873 static int
3874 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3875                            unsigned long ip)
3876 {
3877         if (!debug_locks_off())
3878                 return 0;
3879         if (debug_locks_silent)
3880                 return 0;
3881 
3882         printk("\n");
3883         printk("=================================\n");
3884         printk("[ BUG: bad contention detected! ]\n");
3885         print_kernel_ident();
3886         printk("---------------------------------\n");
3887         printk("%s/%d is trying to contend lock (",
3888                 curr->comm, task_pid_nr(curr));
3889         print_lockdep_cache(lock);
3890         printk(KERN_CONT ") at:\n");
3891         print_ip_sym(ip);
3892         printk("but there are no locks held!\n");
3893         printk("\nother info that might help us debug this:\n");
3894         lockdep_print_held_locks(curr);
3895 
3896         printk("\nstack backtrace:\n");
3897         dump_stack();
3898 
3899         return 0;
3900 }
3901 
3902 static void
3903 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3904 {
3905         struct task_struct *curr = current;
3906         struct held_lock *hlock, *prev_hlock;
3907         struct lock_class_stats *stats;
3908         unsigned int depth;
3909         int i, contention_point, contending_point;
3910 
3911         depth = curr->lockdep_depth;
3912         /*
3913          * Whee, we contended on this lock, except it seems we're not
3914          * actually trying to acquire anything much at all..
3915          */
3916         if (DEBUG_LOCKS_WARN_ON(!depth))
3917                 return;
3918 
3919         prev_hlock = NULL;
3920         for (i = depth-1; i >= 0; i--) {
3921                 hlock = curr->held_locks + i;
3922                 /*
3923                  * We must not cross into another context:
3924                  */
3925                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3926                         break;
3927                 if (match_held_lock(hlock, lock))
3928                         goto found_it;
3929                 prev_hlock = hlock;
3930         }
3931         print_lock_contention_bug(curr, lock, ip);
3932         return;
3933 
3934 found_it:
3935         if (hlock->instance != lock)
3936                 return;
3937 
3938         hlock->waittime_stamp = lockstat_clock();
3939 
3940         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3941         contending_point = lock_point(hlock_class(hlock)->contending_point,
3942                                       lock->ip);
3943 
3944         stats = get_lock_stats(hlock_class(hlock));
3945         if (contention_point < LOCKSTAT_POINTS)
3946                 stats->contention_point[contention_point]++;
3947         if (contending_point < LOCKSTAT_POINTS)
3948                 stats->contending_point[contending_point]++;
3949         if (lock->cpu != smp_processor_id())
3950                 stats->bounces[bounce_contended + !!hlock->read]++;
3951         put_lock_stats(stats);
3952 }
3953 
3954 static void
3955 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3956 {
3957         struct task_struct *curr = current;
3958         struct held_lock *hlock, *prev_hlock;
3959         struct lock_class_stats *stats;
3960         unsigned int depth;
3961         u64 now, waittime = 0;
3962         int i, cpu;
3963 
3964         depth = curr->lockdep_depth;
3965         /*
3966          * Yay, we acquired ownership of this lock we didn't try to
3967          * acquire, how the heck did that happen?
3968          */
3969         if (DEBUG_LOCKS_WARN_ON(!depth))
3970                 return;
3971 
3972         prev_hlock = NULL;
3973         for (i = depth-1; i >= 0; i--) {
3974                 hlock = curr->held_locks + i;
3975                 /*
3976                  * We must not cross into another context:
3977                  */
3978                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3979                         break;
3980                 if (match_held_lock(hlock, lock))
3981                         goto found_it;
3982                 prev_hlock = hlock;
3983         }
3984         print_lock_contention_bug(curr, lock, _RET_IP_);
3985         return;
3986 
3987 found_it:
3988         if (hlock->instance != lock)
3989                 return;
3990 
3991         cpu = smp_processor_id();
3992         if (hlock->waittime_stamp) {
3993                 now = lockstat_clock();
3994                 waittime = now - hlock->waittime_stamp;
3995                 hlock->holdtime_stamp = now;
3996         }
3997 
3998         trace_lock_acquired(lock, ip);
3999 
4000         stats = get_lock_stats(hlock_class(hlock));
4001         if (waittime) {
4002                 if (hlock->read)
4003                         lock_time_inc(&stats->read_waittime, waittime);
4004                 else
4005                         lock_time_inc(&stats->write_waittime, waittime);
4006         }
4007         if (lock->cpu != cpu)
4008                 stats->bounces[bounce_acquired + !!hlock->read]++;
4009         put_lock_stats(stats);
4010 
4011         lock->cpu = cpu;
4012         lock->ip = ip;
4013 }
4014 
4015 void lock_contended(struct lockdep_map *lock, unsigned long ip)
4016 {
4017         unsigned long flags;
4018 
4019         if (unlikely(!lock_stat))
4020                 return;
4021 
4022         if (unlikely(current->lockdep_recursion))
4023                 return;
4024 
4025         raw_local_irq_save(flags);
4026         check_flags(flags);
4027         current->lockdep_recursion = 1;
4028         trace_lock_contended(lock, ip);
4029         __lock_contended(lock, ip);
4030         current->lockdep_recursion = 0;
4031         raw_local_irq_restore(flags);
4032 }
4033 EXPORT_SYMBOL_GPL(lock_contended);
4034 
4035 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
4036 {
4037         unsigned long flags;
4038 
4039         if (unlikely(!lock_stat))
4040                 return;
4041 
4042         if (unlikely(current->lockdep_recursion))
4043                 return;
4044 
4045         raw_local_irq_save(flags);
4046         check_flags(flags);
4047         current->lockdep_recursion = 1;
4048         __lock_acquired(lock, ip);
4049         current->lockdep_recursion = 0;
4050         raw_local_irq_restore(flags);
4051 }
4052 EXPORT_SYMBOL_GPL(lock_acquired);
4053 #endif
4054 
4055 /*
4056  * Used by the testsuite, sanitize the validator state
4057  * after a simulated failure:
4058  */
4059 
4060 void lockdep_reset(void)
4061 {
4062         unsigned long flags;
4063         int i;
4064 
4065         raw_local_irq_save(flags);
4066         current->curr_chain_key = 0;
4067         current->lockdep_depth = 0;
4068         current->lockdep_recursion = 0;
4069         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
4070         nr_hardirq_chains = 0;
4071         nr_softirq_chains = 0;
4072         nr_process_chains = 0;
4073         debug_locks = 1;
4074         for (i = 0; i < CHAINHASH_SIZE; i++)
4075                 INIT_HLIST_HEAD(chainhash_table + i);
4076         raw_local_irq_restore(flags);
4077 }
4078 
4079 static void zap_class(struct lock_class *class)
4080 {
4081         int i;
4082 
4083         /*
4084          * Remove all dependencies this lock is
4085          * involved in:
4086          */
4087         for (i = 0; i < nr_list_entries; i++) {
4088                 if (list_entries[i].class == class)
4089                         list_del_rcu(&list_entries[i].entry);
4090         }
4091         /*
4092          * Unhash the class and remove it from the all_lock_classes list:
4093          */
4094         hlist_del_rcu(&class->hash_entry);
4095         list_del_rcu(&class->lock_entry);
4096 
4097         RCU_INIT_POINTER(class->key, NULL);
4098         RCU_INIT_POINTER(class->name, NULL);
4099 }
4100 
4101 static inline int within(const void *addr, void *start, unsigned long size)
4102 {
4103         return addr >= start && addr < start + size;
4104 }
4105 
4106 /*
4107  * Used in module.c to remove lock classes from memory that is going to be
4108  * freed; and possibly re-used by other modules.
4109  *
4110  * We will have had one sync_sched() before getting here, so we're guaranteed
4111  * nobody will look up these exact classes -- they're properly dead but still
4112  * allocated.
4113  */
4114 void lockdep_free_key_range(void *start, unsigned long size)
4115 {
4116         struct lock_class *class;
4117         struct hlist_head *head;
4118         unsigned long flags;
4119         int i;
4120         int locked;
4121 
4122         raw_local_irq_save(flags);
4123         locked = graph_lock();
4124 
4125         /*
4126          * Unhash all classes that were created by this module:
4127          */
4128         for (i = 0; i < CLASSHASH_SIZE; i++) {
4129                 head = classhash_table + i;
4130                 hlist_for_each_entry_rcu(class, head, hash_entry) {
4131                         if (within(class->key, start, size))
4132                                 zap_class(class);
4133                         else if (within(class->name, start, size))
4134                                 zap_class(class);
4135                 }
4136         }
4137 
4138         if (locked)
4139                 graph_unlock();
4140         raw_local_irq_restore(flags);
4141 
4142         /*
4143          * Wait for any possible iterators from look_up_lock_class() to pass
4144          * before continuing to free the memory they refer to.
4145          *
4146          * sync_sched() is sufficient because the read-side is IRQ disable.
4147          */
4148         synchronize_sched();
4149 
4150         /*
4151          * XXX at this point we could return the resources to the pool;
4152          * instead we leak them. We would need to change to bitmap allocators
4153          * instead of the linear allocators we have now.
4154          */
4155 }
4156 
4157 void lockdep_reset_lock(struct lockdep_map *lock)
4158 {
4159         struct lock_class *class;
4160         struct hlist_head *head;
4161         unsigned long flags;
4162         int i, j;
4163         int locked;
4164 
4165         raw_local_irq_save(flags);
4166 
4167         /*
4168          * Remove all classes this lock might have:
4169          */
4170         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4171                 /*
4172                  * If the class exists we look it up and zap it:
4173                  */
4174                 class = look_up_lock_class(lock, j);
4175                 if (class)
4176                         zap_class(class);
4177         }
4178         /*
4179          * Debug check: in the end all mapped classes should
4180          * be gone.
4181          */
4182         locked = graph_lock();
4183         for (i = 0; i < CLASSHASH_SIZE; i++) {
4184                 head = classhash_table + i;
4185                 hlist_for_each_entry_rcu(class, head, hash_entry) {
4186                         int match = 0;
4187 
4188                         for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4189                                 match |= class == lock->class_cache[j];
4190 
4191                         if (unlikely(match)) {
4192                                 if (debug_locks_off_graph_unlock()) {
4193                                         /*
4194                                          * We all just reset everything, how did it match?
4195                                          */
4196                                         WARN_ON(1);
4197                                 }
4198                                 goto out_restore;
4199                         }
4200                 }
4201         }
4202         if (locked)
4203                 graph_unlock();
4204 
4205 out_restore:
4206         raw_local_irq_restore(flags);
4207 }
4208 
4209 void __init lockdep_info(void)
4210 {
4211         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4212 
4213         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
4214         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
4215         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
4216         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
4217         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
4218         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
4219         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
4220 
4221         printk(" memory used by lock dependency info: %lu kB\n",
4222                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4223                 sizeof(struct list_head) * CLASSHASH_SIZE +
4224                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4225                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4226                 sizeof(struct list_head) * CHAINHASH_SIZE
4227 #ifdef CONFIG_PROVE_LOCKING
4228                 + sizeof(struct circular_queue)
4229 #endif
4230                 ) / 1024
4231                 );
4232 
4233         printk(" per task-struct memory footprint: %lu bytes\n",
4234                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4235 }
4236 
4237 static void
4238 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4239                      const void *mem_to, struct held_lock *hlock)
4240 {
4241         if (!debug_locks_off())
4242                 return;
4243         if (debug_locks_silent)
4244                 return;
4245 
4246         printk("\n");
4247         printk("=========================\n");
4248         printk("[ BUG: held lock freed! ]\n");
4249         print_kernel_ident();
4250         printk("-------------------------\n");
4251         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4252                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4253         print_lock(hlock);
4254         lockdep_print_held_locks(curr);
4255 
4256         printk("\nstack backtrace:\n");
4257         dump_stack();
4258 }
4259 
4260 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4261                                 const void* lock_from, unsigned long lock_len)
4262 {
4263         return lock_from + lock_len <= mem_from ||
4264                 mem_from + mem_len <= lock_from;
4265 }
4266 
4267 /*
4268  * Called when kernel memory is freed (or unmapped), or if a lock
4269  * is destroyed or reinitialized - this code checks whether there is
4270  * any held lock in the memory range of <from> to <to>:
4271  */
4272 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4273 {
4274         struct task_struct *curr = current;
4275         struct held_lock *hlock;
4276         unsigned long flags;
4277         int i;
4278 
4279         if (unlikely(!debug_locks))
4280                 return;
4281 
4282         local_irq_save(flags);
4283         for (i = 0; i < curr->lockdep_depth; i++) {
4284                 hlock = curr->held_locks + i;
4285 
4286                 if (not_in_range(mem_from, mem_len, hlock->instance,
4287                                         sizeof(*hlock->instance)))
4288                         continue;
4289 
4290                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4291                 break;
4292         }
4293         local_irq_restore(flags);
4294 }
4295 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4296 
4297 static void print_held_locks_bug(void)
4298 {
4299         if (!debug_locks_off())
4300                 return;
4301         if (debug_locks_silent)
4302                 return;
4303 
4304         printk("\n");
4305         printk("=====================================\n");
4306         printk("[ BUG: %s/%d still has locks held! ]\n",
4307                current->comm, task_pid_nr(current));
4308         print_kernel_ident();
4309         printk("-------------------------------------\n");
4310         lockdep_print_held_locks(current);
4311         printk("\nstack backtrace:\n");
4312         dump_stack();
4313 }
4314 
4315 void debug_check_no_locks_held(void)
4316 {
4317         if (unlikely(current->lockdep_depth > 0))
4318                 print_held_locks_bug();
4319 }
4320 EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4321 
4322 #ifdef __KERNEL__
4323 void debug_show_all_locks(void)
4324 {
4325         struct task_struct *g, *p;
4326         int count = 10;
4327         int unlock = 1;
4328 
4329         if (unlikely(!debug_locks)) {
4330                 printk("INFO: lockdep is turned off.\n");
4331                 return;
4332         }
4333         printk("\nShowing all locks held in the system:\n");
4334 
4335         /*
4336          * Here we try to get the tasklist_lock as hard as possible,
4337          * if not successful after 2 seconds we ignore it (but keep
4338          * trying). This is to enable a debug printout even if a
4339          * tasklist_lock-holding task deadlocks or crashes.
4340          */
4341 retry:
4342         if (!read_trylock(&tasklist_lock)) {
4343                 if (count == 10)
4344                         printk("hm, tasklist_lock locked, retrying... ");
4345                 if (count) {
4346                         count--;
4347                         printk(" #%d", 10-count);
4348                         mdelay(200);
4349                         goto retry;
4350                 }
4351                 printk(" ignoring it.\n");
4352                 unlock = 0;
4353         } else {
4354                 if (count != 10)
4355                         printk(KERN_CONT " locked it.\n");
4356         }
4357 
4358         do_each_thread(g, p) {
4359                 /*
4360                  * It's not reliable to print a task's held locks
4361                  * if it's not sleeping (or if it's not the current
4362                  * task):
4363                  */
4364                 if (p->state == TASK_RUNNING && p != current)
4365                         continue;
4366                 if (p->lockdep_depth)
4367                         lockdep_print_held_locks(p);
4368                 if (!unlock)
4369                         if (read_trylock(&tasklist_lock))
4370                                 unlock = 1;
4371         } while_each_thread(g, p);
4372 
4373         printk("\n");
4374         printk("=============================================\n\n");
4375 
4376         if (unlock)
4377                 read_unlock(&tasklist_lock);
4378 }
4379 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4380 #endif
4381 
4382 /*
4383  * Careful: only use this function if you are sure that
4384  * the task cannot run in parallel!
4385  */
4386 void debug_show_held_locks(struct task_struct *task)
4387 {
4388         if (unlikely(!debug_locks)) {
4389                 printk("INFO: lockdep is turned off.\n");
4390                 return;
4391         }
4392         lockdep_print_held_locks(task);
4393 }
4394 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4395 
4396 asmlinkage __visible void lockdep_sys_exit(void)
4397 {
4398         struct task_struct *curr = current;
4399 
4400         if (unlikely(curr->lockdep_depth)) {
4401                 if (!debug_locks_off())
4402                         return;
4403                 printk("\n");
4404                 printk("================================================\n");
4405                 printk("[ BUG: lock held when returning to user space! ]\n");
4406                 print_kernel_ident();
4407                 printk("------------------------------------------------\n");
4408                 printk("%s/%d is leaving the kernel with locks still held!\n",
4409                                 curr->comm, curr->pid);
4410                 lockdep_print_held_locks(curr);
4411         }
4412 }
4413 
4414 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4415 {
4416         struct task_struct *curr = current;
4417 
4418 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4419         if (!debug_locks_off())
4420                 return;
4421 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4422         /* Note: the following can be executed concurrently, so be careful. */
4423         printk("\n");
4424         pr_err("===============================\n");
4425         pr_err("[ ERR: suspicious RCU usage.  ]\n");
4426         print_kernel_ident();
4427         pr_err("-------------------------------\n");
4428         pr_err("%s:%d %s!\n", file, line, s);
4429         pr_err("\nother info that might help us debug this:\n\n");
4430         pr_err("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4431                !rcu_lockdep_current_cpu_online()
4432                         ? "RCU used illegally from offline CPU!\n"
4433                         : !rcu_is_watching()
4434                                 ? "RCU used illegally from idle CPU!\n"
4435                                 : "",
4436                rcu_scheduler_active, debug_locks);
4437 
4438         /*
4439          * If a CPU is in the RCU-free window in idle (ie: in the section
4440          * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4441          * considers that CPU to be in an "extended quiescent state",
4442          * which means that RCU will be completely ignoring that CPU.
4443          * Therefore, rcu_read_lock() and friends have absolutely no
4444          * effect on a CPU running in that state. In other words, even if
4445          * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4446          * delete data structures out from under it.  RCU really has no
4447          * choice here: we need to keep an RCU-free window in idle where
4448          * the CPU may possibly enter into low power mode. This way we can
4449          * notice an extended quiescent state to other CPUs that started a grace
4450          * period. Otherwise we would delay any grace period as long as we run
4451          * in the idle task.
4452          *
4453          * So complain bitterly if someone does call rcu_read_lock(),
4454          * rcu_read_lock_bh() and so on from extended quiescent states.
4455          */
4456         if (!rcu_is_watching())
4457                 printk("RCU used illegally from extended quiescent state!\n");
4458 
4459         lockdep_print_held_locks(curr);
4460         printk("\nstack backtrace:\n");
4461         dump_stack();
4462 }
4463 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
4464 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp