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1 | /* |
2 | * kernel/lockdep.c |
3 | * |
4 | * Runtime locking correctness validator |
5 | * |
6 | * Started by Ingo Molnar: |
7 | * |
8 | * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
9 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
10 | * |
11 | * this code maps all the lock dependencies as they occur in a live kernel |
12 | * and will warn about the following classes of locking bugs: |
13 | * |
14 | * - lock inversion scenarios |
15 | * - circular lock dependencies |
16 | * - hardirq/softirq safe/unsafe locking bugs |
17 | * |
18 | * Bugs are reported even if the current locking scenario does not cause |
19 | * any deadlock at this point. |
20 | * |
21 | * I.e. if anytime in the past two locks were taken in a different order, |
22 | * even if it happened for another task, even if those were different |
23 | * locks (but of the same class as this lock), this code will detect it. |
24 | * |
25 | * Thanks to Arjan van de Ven for coming up with the initial idea of |
26 | * mapping lock dependencies runtime. |
27 | */ |
28 | #define DISABLE_BRANCH_PROFILING |
29 | #include <linux/mutex.h> |
30 | #include <linux/sched.h> |
31 | #include <linux/delay.h> |
32 | #include <linux/module.h> |
33 | #include <linux/proc_fs.h> |
34 | #include <linux/seq_file.h> |
35 | #include <linux/spinlock.h> |
36 | #include <linux/kallsyms.h> |
37 | #include <linux/interrupt.h> |
38 | #include <linux/stacktrace.h> |
39 | #include <linux/debug_locks.h> |
40 | #include <linux/irqflags.h> |
41 | #include <linux/utsname.h> |
42 | #include <linux/hash.h> |
43 | #include <linux/ftrace.h> |
44 | #include <linux/stringify.h> |
45 | #include <linux/bitops.h> |
46 | #include <linux/gfp.h> |
47 | |
48 | #include <asm/sections.h> |
49 | |
50 | #include "lockdep_internals.h" |
51 | |
52 | #define CREATE_TRACE_POINTS |
53 | #include <trace/events/lock.h> |
54 | |
55 | #ifdef CONFIG_PROVE_LOCKING |
56 | int prove_locking = 1; |
57 | module_param(prove_locking, int, 0644); |
58 | #else |
59 | #define prove_locking 0 |
60 | #endif |
61 | |
62 | #ifdef CONFIG_LOCK_STAT |
63 | int lock_stat = 1; |
64 | module_param(lock_stat, int, 0644); |
65 | #else |
66 | #define lock_stat 0 |
67 | #endif |
68 | |
69 | /* |
70 | * lockdep_lock: protects the lockdep graph, the hashes and the |
71 | * class/list/hash allocators. |
72 | * |
73 | * This is one of the rare exceptions where it's justified |
74 | * to use a raw spinlock - we really dont want the spinlock |
75 | * code to recurse back into the lockdep code... |
76 | */ |
77 | static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
78 | |
79 | static int graph_lock(void) |
80 | { |
81 | arch_spin_lock(&lockdep_lock); |
82 | /* |
83 | * Make sure that if another CPU detected a bug while |
84 | * walking the graph we dont change it (while the other |
85 | * CPU is busy printing out stuff with the graph lock |
86 | * dropped already) |
87 | */ |
88 | if (!debug_locks) { |
89 | arch_spin_unlock(&lockdep_lock); |
90 | return 0; |
91 | } |
92 | /* prevent any recursions within lockdep from causing deadlocks */ |
93 | current->lockdep_recursion++; |
94 | return 1; |
95 | } |
96 | |
97 | static inline int graph_unlock(void) |
98 | { |
99 | if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) |
100 | return DEBUG_LOCKS_WARN_ON(1); |
101 | |
102 | current->lockdep_recursion--; |
103 | arch_spin_unlock(&lockdep_lock); |
104 | return 0; |
105 | } |
106 | |
107 | /* |
108 | * Turn lock debugging off and return with 0 if it was off already, |
109 | * and also release the graph lock: |
110 | */ |
111 | static inline int debug_locks_off_graph_unlock(void) |
112 | { |
113 | int ret = debug_locks_off(); |
114 | |
115 | arch_spin_unlock(&lockdep_lock); |
116 | |
117 | return ret; |
118 | } |
119 | |
120 | static int lockdep_initialized; |
121 | |
122 | unsigned long nr_list_entries; |
123 | static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; |
124 | |
125 | /* |
126 | * All data structures here are protected by the global debug_lock. |
127 | * |
128 | * Mutex key structs only get allocated, once during bootup, and never |
129 | * get freed - this significantly simplifies the debugging code. |
130 | */ |
131 | unsigned long nr_lock_classes; |
132 | static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; |
133 | |
134 | static inline struct lock_class *hlock_class(struct held_lock *hlock) |
135 | { |
136 | if (!hlock->class_idx) { |
137 | DEBUG_LOCKS_WARN_ON(1); |
138 | return NULL; |
139 | } |
140 | return lock_classes + hlock->class_idx - 1; |
141 | } |
142 | |
143 | #ifdef CONFIG_LOCK_STAT |
144 | static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], |
145 | cpu_lock_stats); |
146 | |
147 | static inline u64 lockstat_clock(void) |
148 | { |
149 | return local_clock(); |
150 | } |
151 | |
152 | static int lock_point(unsigned long points[], unsigned long ip) |
153 | { |
154 | int i; |
155 | |
156 | for (i = 0; i < LOCKSTAT_POINTS; i++) { |
157 | if (points[i] == 0) { |
158 | points[i] = ip; |
159 | break; |
160 | } |
161 | if (points[i] == ip) |
162 | break; |
163 | } |
164 | |
165 | return i; |
166 | } |
167 | |
168 | static void lock_time_inc(struct lock_time *lt, u64 time) |
169 | { |
170 | if (time > lt->max) |
171 | lt->max = time; |
172 | |
173 | if (time < lt->min || !lt->nr) |
174 | lt->min = time; |
175 | |
176 | lt->total += time; |
177 | lt->nr++; |
178 | } |
179 | |
180 | static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) |
181 | { |
182 | if (!src->nr) |
183 | return; |
184 | |
185 | if (src->max > dst->max) |
186 | dst->max = src->max; |
187 | |
188 | if (src->min < dst->min || !dst->nr) |
189 | dst->min = src->min; |
190 | |
191 | dst->total += src->total; |
192 | dst->nr += src->nr; |
193 | } |
194 | |
195 | struct lock_class_stats lock_stats(struct lock_class *class) |
196 | { |
197 | struct lock_class_stats stats; |
198 | int cpu, i; |
199 | |
200 | memset(&stats, 0, sizeof(struct lock_class_stats)); |
201 | for_each_possible_cpu(cpu) { |
202 | struct lock_class_stats *pcs = |
203 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
204 | |
205 | for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) |
206 | stats.contention_point[i] += pcs->contention_point[i]; |
207 | |
208 | for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) |
209 | stats.contending_point[i] += pcs->contending_point[i]; |
210 | |
211 | lock_time_add(&pcs->read_waittime, &stats.read_waittime); |
212 | lock_time_add(&pcs->write_waittime, &stats.write_waittime); |
213 | |
214 | lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); |
215 | lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); |
216 | |
217 | for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) |
218 | stats.bounces[i] += pcs->bounces[i]; |
219 | } |
220 | |
221 | return stats; |
222 | } |
223 | |
224 | void clear_lock_stats(struct lock_class *class) |
225 | { |
226 | int cpu; |
227 | |
228 | for_each_possible_cpu(cpu) { |
229 | struct lock_class_stats *cpu_stats = |
230 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
231 | |
232 | memset(cpu_stats, 0, sizeof(struct lock_class_stats)); |
233 | } |
234 | memset(class->contention_point, 0, sizeof(class->contention_point)); |
235 | memset(class->contending_point, 0, sizeof(class->contending_point)); |
236 | } |
237 | |
238 | static struct lock_class_stats *get_lock_stats(struct lock_class *class) |
239 | { |
240 | return &get_cpu_var(cpu_lock_stats)[class - lock_classes]; |
241 | } |
242 | |
243 | static void put_lock_stats(struct lock_class_stats *stats) |
244 | { |
245 | put_cpu_var(cpu_lock_stats); |
246 | } |
247 | |
248 | static void lock_release_holdtime(struct held_lock *hlock) |
249 | { |
250 | struct lock_class_stats *stats; |
251 | u64 holdtime; |
252 | |
253 | if (!lock_stat) |
254 | return; |
255 | |
256 | holdtime = lockstat_clock() - hlock->holdtime_stamp; |
257 | |
258 | stats = get_lock_stats(hlock_class(hlock)); |
259 | if (hlock->read) |
260 | lock_time_inc(&stats->read_holdtime, holdtime); |
261 | else |
262 | lock_time_inc(&stats->write_holdtime, holdtime); |
263 | put_lock_stats(stats); |
264 | } |
265 | #else |
266 | static inline void lock_release_holdtime(struct held_lock *hlock) |
267 | { |
268 | } |
269 | #endif |
270 | |
271 | /* |
272 | * We keep a global list of all lock classes. The list only grows, |
273 | * never shrinks. The list is only accessed with the lockdep |
274 | * spinlock lock held. |
275 | */ |
276 | LIST_HEAD(all_lock_classes); |
277 | |
278 | /* |
279 | * The lockdep classes are in a hash-table as well, for fast lookup: |
280 | */ |
281 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) |
282 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) |
283 | #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) |
284 | #define classhashentry(key) (classhash_table + __classhashfn((key))) |
285 | |
286 | static struct list_head classhash_table[CLASSHASH_SIZE]; |
287 | |
288 | /* |
289 | * We put the lock dependency chains into a hash-table as well, to cache |
290 | * their existence: |
291 | */ |
292 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) |
293 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) |
294 | #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) |
295 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) |
296 | |
297 | static struct list_head chainhash_table[CHAINHASH_SIZE]; |
298 | |
299 | /* |
300 | * The hash key of the lock dependency chains is a hash itself too: |
301 | * it's a hash of all locks taken up to that lock, including that lock. |
302 | * It's a 64-bit hash, because it's important for the keys to be |
303 | * unique. |
304 | */ |
305 | #define iterate_chain_key(key1, key2) \ |
306 | (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \ |
307 | ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \ |
308 | (key2)) |
309 | |
310 | void lockdep_off(void) |
311 | { |
312 | current->lockdep_recursion++; |
313 | } |
314 | EXPORT_SYMBOL(lockdep_off); |
315 | |
316 | void lockdep_on(void) |
317 | { |
318 | current->lockdep_recursion--; |
319 | } |
320 | EXPORT_SYMBOL(lockdep_on); |
321 | |
322 | /* |
323 | * Debugging switches: |
324 | */ |
325 | |
326 | #define VERBOSE 0 |
327 | #define VERY_VERBOSE 0 |
328 | |
329 | #if VERBOSE |
330 | # define HARDIRQ_VERBOSE 1 |
331 | # define SOFTIRQ_VERBOSE 1 |
332 | # define RECLAIM_VERBOSE 1 |
333 | #else |
334 | # define HARDIRQ_VERBOSE 0 |
335 | # define SOFTIRQ_VERBOSE 0 |
336 | # define RECLAIM_VERBOSE 0 |
337 | #endif |
338 | |
339 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE |
340 | /* |
341 | * Quick filtering for interesting events: |
342 | */ |
343 | static int class_filter(struct lock_class *class) |
344 | { |
345 | #if 0 |
346 | /* Example */ |
347 | if (class->name_version == 1 && |
348 | !strcmp(class->name, "lockname")) |
349 | return 1; |
350 | if (class->name_version == 1 && |
351 | !strcmp(class->name, "&struct->lockfield")) |
352 | return 1; |
353 | #endif |
354 | /* Filter everything else. 1 would be to allow everything else */ |
355 | return 0; |
356 | } |
357 | #endif |
358 | |
359 | static int verbose(struct lock_class *class) |
360 | { |
361 | #if VERBOSE |
362 | return class_filter(class); |
363 | #endif |
364 | return 0; |
365 | } |
366 | |
367 | /* |
368 | * Stack-trace: tightly packed array of stack backtrace |
369 | * addresses. Protected by the graph_lock. |
370 | */ |
371 | unsigned long nr_stack_trace_entries; |
372 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; |
373 | |
374 | static int save_trace(struct stack_trace *trace) |
375 | { |
376 | trace->nr_entries = 0; |
377 | trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; |
378 | trace->entries = stack_trace + nr_stack_trace_entries; |
379 | |
380 | trace->skip = 3; |
381 | |
382 | save_stack_trace(trace); |
383 | |
384 | /* |
385 | * Some daft arches put -1 at the end to indicate its a full trace. |
386 | * |
387 | * <rant> this is buggy anyway, since it takes a whole extra entry so a |
388 | * complete trace that maxes out the entries provided will be reported |
389 | * as incomplete, friggin useless </rant> |
390 | */ |
391 | if (trace->nr_entries != 0 && |
392 | trace->entries[trace->nr_entries-1] == ULONG_MAX) |
393 | trace->nr_entries--; |
394 | |
395 | trace->max_entries = trace->nr_entries; |
396 | |
397 | nr_stack_trace_entries += trace->nr_entries; |
398 | |
399 | if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { |
400 | if (!debug_locks_off_graph_unlock()) |
401 | return 0; |
402 | |
403 | printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); |
404 | printk("turning off the locking correctness validator.\n"); |
405 | dump_stack(); |
406 | |
407 | return 0; |
408 | } |
409 | |
410 | return 1; |
411 | } |
412 | |
413 | unsigned int nr_hardirq_chains; |
414 | unsigned int nr_softirq_chains; |
415 | unsigned int nr_process_chains; |
416 | unsigned int max_lockdep_depth; |
417 | |
418 | #ifdef CONFIG_DEBUG_LOCKDEP |
419 | /* |
420 | * We cannot printk in early bootup code. Not even early_printk() |
421 | * might work. So we mark any initialization errors and printk |
422 | * about it later on, in lockdep_info(). |
423 | */ |
424 | static int lockdep_init_error; |
425 | static unsigned long lockdep_init_trace_data[20]; |
426 | static struct stack_trace lockdep_init_trace = { |
427 | .max_entries = ARRAY_SIZE(lockdep_init_trace_data), |
428 | .entries = lockdep_init_trace_data, |
429 | }; |
430 | |
431 | /* |
432 | * Various lockdep statistics: |
433 | */ |
434 | DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); |
435 | #endif |
436 | |
437 | /* |
438 | * Locking printouts: |
439 | */ |
440 | |
441 | #define __USAGE(__STATE) \ |
442 | [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ |
443 | [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ |
444 | [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ |
445 | [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", |
446 | |
447 | static const char *usage_str[] = |
448 | { |
449 | #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) |
450 | #include "lockdep_states.h" |
451 | #undef LOCKDEP_STATE |
452 | [LOCK_USED] = "INITIAL USE", |
453 | }; |
454 | |
455 | const char * __get_key_name(struct lockdep_subclass_key *key, char *str) |
456 | { |
457 | return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); |
458 | } |
459 | |
460 | static inline unsigned long lock_flag(enum lock_usage_bit bit) |
461 | { |
462 | return 1UL << bit; |
463 | } |
464 | |
465 | static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) |
466 | { |
467 | char c = '.'; |
468 | |
469 | if (class->usage_mask & lock_flag(bit + 2)) |
470 | c = '+'; |
471 | if (class->usage_mask & lock_flag(bit)) { |
472 | c = '-'; |
473 | if (class->usage_mask & lock_flag(bit + 2)) |
474 | c = '?'; |
475 | } |
476 | |
477 | return c; |
478 | } |
479 | |
480 | void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) |
481 | { |
482 | int i = 0; |
483 | |
484 | #define LOCKDEP_STATE(__STATE) \ |
485 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ |
486 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); |
487 | #include "lockdep_states.h" |
488 | #undef LOCKDEP_STATE |
489 | |
490 | usage[i] = '\0'; |
491 | } |
492 | |
493 | static int __print_lock_name(struct lock_class *class) |
494 | { |
495 | char str[KSYM_NAME_LEN]; |
496 | const char *name; |
497 | |
498 | name = class->name; |
499 | if (!name) |
500 | name = __get_key_name(class->key, str); |
501 | |
502 | return printk("%s", name); |
503 | } |
504 | |
505 | static void print_lock_name(struct lock_class *class) |
506 | { |
507 | char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS]; |
508 | const char *name; |
509 | |
510 | get_usage_chars(class, usage); |
511 | |
512 | name = class->name; |
513 | if (!name) { |
514 | name = __get_key_name(class->key, str); |
515 | printk(" (%s", name); |
516 | } else { |
517 | printk(" (%s", name); |
518 | if (class->name_version > 1) |
519 | printk("#%d", class->name_version); |
520 | if (class->subclass) |
521 | printk("/%d", class->subclass); |
522 | } |
523 | printk("){%s}", usage); |
524 | } |
525 | |
526 | static void print_lockdep_cache(struct lockdep_map *lock) |
527 | { |
528 | const char *name; |
529 | char str[KSYM_NAME_LEN]; |
530 | |
531 | name = lock->name; |
532 | if (!name) |
533 | name = __get_key_name(lock->key->subkeys, str); |
534 | |
535 | printk("%s", name); |
536 | } |
537 | |
538 | static void print_lock(struct held_lock *hlock) |
539 | { |
540 | print_lock_name(hlock_class(hlock)); |
541 | printk(", at: "); |
542 | print_ip_sym(hlock->acquire_ip); |
543 | } |
544 | |
545 | static void lockdep_print_held_locks(struct task_struct *curr) |
546 | { |
547 | int i, depth = curr->lockdep_depth; |
548 | |
549 | if (!depth) { |
550 | printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr)); |
551 | return; |
552 | } |
553 | printk("%d lock%s held by %s/%d:\n", |
554 | depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr)); |
555 | |
556 | for (i = 0; i < depth; i++) { |
557 | printk(" #%d: ", i); |
558 | print_lock(curr->held_locks + i); |
559 | } |
560 | } |
561 | |
562 | static void print_kernel_version(void) |
563 | { |
564 | printk("%s %.*s\n", init_utsname()->release, |
565 | (int)strcspn(init_utsname()->version, " "), |
566 | init_utsname()->version); |
567 | } |
568 | |
569 | static int very_verbose(struct lock_class *class) |
570 | { |
571 | #if VERY_VERBOSE |
572 | return class_filter(class); |
573 | #endif |
574 | return 0; |
575 | } |
576 | |
577 | /* |
578 | * Is this the address of a static object: |
579 | */ |
580 | static int static_obj(void *obj) |
581 | { |
582 | unsigned long start = (unsigned long) &_stext, |
583 | end = (unsigned long) &_end, |
584 | addr = (unsigned long) obj; |
585 | |
586 | /* |
587 | * static variable? |
588 | */ |
589 | if ((addr >= start) && (addr < end)) |
590 | return 1; |
591 | |
592 | if (arch_is_kernel_data(addr)) |
593 | return 1; |
594 | |
595 | /* |
596 | * in-kernel percpu var? |
597 | */ |
598 | if (is_kernel_percpu_address(addr)) |
599 | return 1; |
600 | |
601 | /* |
602 | * module static or percpu var? |
603 | */ |
604 | return is_module_address(addr) || is_module_percpu_address(addr); |
605 | } |
606 | |
607 | /* |
608 | * To make lock name printouts unique, we calculate a unique |
609 | * class->name_version generation counter: |
610 | */ |
611 | static int count_matching_names(struct lock_class *new_class) |
612 | { |
613 | struct lock_class *class; |
614 | int count = 0; |
615 | |
616 | if (!new_class->name) |
617 | return 0; |
618 | |
619 | list_for_each_entry(class, &all_lock_classes, lock_entry) { |
620 | if (new_class->key - new_class->subclass == class->key) |
621 | return class->name_version; |
622 | if (class->name && !strcmp(class->name, new_class->name)) |
623 | count = max(count, class->name_version); |
624 | } |
625 | |
626 | return count + 1; |
627 | } |
628 | |
629 | /* |
630 | * Register a lock's class in the hash-table, if the class is not present |
631 | * yet. Otherwise we look it up. We cache the result in the lock object |
632 | * itself, so actual lookup of the hash should be once per lock object. |
633 | */ |
634 | static inline struct lock_class * |
635 | look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) |
636 | { |
637 | struct lockdep_subclass_key *key; |
638 | struct list_head *hash_head; |
639 | struct lock_class *class; |
640 | |
641 | #ifdef CONFIG_DEBUG_LOCKDEP |
642 | /* |
643 | * If the architecture calls into lockdep before initializing |
644 | * the hashes then we'll warn about it later. (we cannot printk |
645 | * right now) |
646 | */ |
647 | if (unlikely(!lockdep_initialized)) { |
648 | lockdep_init(); |
649 | lockdep_init_error = 1; |
650 | save_stack_trace(&lockdep_init_trace); |
651 | } |
652 | #endif |
653 | |
654 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { |
655 | debug_locks_off(); |
656 | printk(KERN_ERR |
657 | "BUG: looking up invalid subclass: %u\n", subclass); |
658 | printk(KERN_ERR |
659 | "turning off the locking correctness validator.\n"); |
660 | dump_stack(); |
661 | return NULL; |
662 | } |
663 | |
664 | /* |
665 | * Static locks do not have their class-keys yet - for them the key |
666 | * is the lock object itself: |
667 | */ |
668 | if (unlikely(!lock->key)) |
669 | lock->key = (void *)lock; |
670 | |
671 | /* |
672 | * NOTE: the class-key must be unique. For dynamic locks, a static |
673 | * lock_class_key variable is passed in through the mutex_init() |
674 | * (or spin_lock_init()) call - which acts as the key. For static |
675 | * locks we use the lock object itself as the key. |
676 | */ |
677 | BUILD_BUG_ON(sizeof(struct lock_class_key) > |
678 | sizeof(struct lockdep_map)); |
679 | |
680 | key = lock->key->subkeys + subclass; |
681 | |
682 | hash_head = classhashentry(key); |
683 | |
684 | /* |
685 | * We can walk the hash lockfree, because the hash only |
686 | * grows, and we are careful when adding entries to the end: |
687 | */ |
688 | list_for_each_entry(class, hash_head, hash_entry) { |
689 | if (class->key == key) { |
690 | WARN_ON_ONCE(class->name != lock->name); |
691 | return class; |
692 | } |
693 | } |
694 | |
695 | return NULL; |
696 | } |
697 | |
698 | /* |
699 | * Register a lock's class in the hash-table, if the class is not present |
700 | * yet. Otherwise we look it up. We cache the result in the lock object |
701 | * itself, so actual lookup of the hash should be once per lock object. |
702 | */ |
703 | static inline struct lock_class * |
704 | register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) |
705 | { |
706 | struct lockdep_subclass_key *key; |
707 | struct list_head *hash_head; |
708 | struct lock_class *class; |
709 | unsigned long flags; |
710 | |
711 | class = look_up_lock_class(lock, subclass); |
712 | if (likely(class)) |
713 | return class; |
714 | |
715 | /* |
716 | * Debug-check: all keys must be persistent! |
717 | */ |
718 | if (!static_obj(lock->key)) { |
719 | debug_locks_off(); |
720 | printk("INFO: trying to register non-static key.\n"); |
721 | printk("the code is fine but needs lockdep annotation.\n"); |
722 | printk("turning off the locking correctness validator.\n"); |
723 | dump_stack(); |
724 | |
725 | return NULL; |
726 | } |
727 | |
728 | key = lock->key->subkeys + subclass; |
729 | hash_head = classhashentry(key); |
730 | |
731 | raw_local_irq_save(flags); |
732 | if (!graph_lock()) { |
733 | raw_local_irq_restore(flags); |
734 | return NULL; |
735 | } |
736 | /* |
737 | * We have to do the hash-walk again, to avoid races |
738 | * with another CPU: |
739 | */ |
740 | list_for_each_entry(class, hash_head, hash_entry) |
741 | if (class->key == key) |
742 | goto out_unlock_set; |
743 | /* |
744 | * Allocate a new key from the static array, and add it to |
745 | * the hash: |
746 | */ |
747 | if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { |
748 | if (!debug_locks_off_graph_unlock()) { |
749 | raw_local_irq_restore(flags); |
750 | return NULL; |
751 | } |
752 | raw_local_irq_restore(flags); |
753 | |
754 | printk("BUG: MAX_LOCKDEP_KEYS too low!\n"); |
755 | printk("turning off the locking correctness validator.\n"); |
756 | dump_stack(); |
757 | return NULL; |
758 | } |
759 | class = lock_classes + nr_lock_classes++; |
760 | debug_atomic_inc(nr_unused_locks); |
761 | class->key = key; |
762 | class->name = lock->name; |
763 | class->subclass = subclass; |
764 | INIT_LIST_HEAD(&class->lock_entry); |
765 | INIT_LIST_HEAD(&class->locks_before); |
766 | INIT_LIST_HEAD(&class->locks_after); |
767 | class->name_version = count_matching_names(class); |
768 | /* |
769 | * We use RCU's safe list-add method to make |
770 | * parallel walking of the hash-list safe: |
771 | */ |
772 | list_add_tail_rcu(&class->hash_entry, hash_head); |
773 | /* |
774 | * Add it to the global list of classes: |
775 | */ |
776 | list_add_tail_rcu(&class->lock_entry, &all_lock_classes); |
777 | |
778 | if (verbose(class)) { |
779 | graph_unlock(); |
780 | raw_local_irq_restore(flags); |
781 | |
782 | printk("\nnew class %p: %s", class->key, class->name); |
783 | if (class->name_version > 1) |
784 | printk("#%d", class->name_version); |
785 | printk("\n"); |
786 | dump_stack(); |
787 | |
788 | raw_local_irq_save(flags); |
789 | if (!graph_lock()) { |
790 | raw_local_irq_restore(flags); |
791 | return NULL; |
792 | } |
793 | } |
794 | out_unlock_set: |
795 | graph_unlock(); |
796 | raw_local_irq_restore(flags); |
797 | |
798 | if (!subclass || force) |
799 | lock->class_cache[0] = class; |
800 | else if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
801 | lock->class_cache[subclass] = class; |
802 | |
803 | if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) |
804 | return NULL; |
805 | |
806 | return class; |
807 | } |
808 | |
809 | #ifdef CONFIG_PROVE_LOCKING |
810 | /* |
811 | * Allocate a lockdep entry. (assumes the graph_lock held, returns |
812 | * with NULL on failure) |
813 | */ |
814 | static struct lock_list *alloc_list_entry(void) |
815 | { |
816 | if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { |
817 | if (!debug_locks_off_graph_unlock()) |
818 | return NULL; |
819 | |
820 | printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n"); |
821 | printk("turning off the locking correctness validator.\n"); |
822 | dump_stack(); |
823 | return NULL; |
824 | } |
825 | return list_entries + nr_list_entries++; |
826 | } |
827 | |
828 | /* |
829 | * Add a new dependency to the head of the list: |
830 | */ |
831 | static int add_lock_to_list(struct lock_class *class, struct lock_class *this, |
832 | struct list_head *head, unsigned long ip, |
833 | int distance, struct stack_trace *trace) |
834 | { |
835 | struct lock_list *entry; |
836 | /* |
837 | * Lock not present yet - get a new dependency struct and |
838 | * add it to the list: |
839 | */ |
840 | entry = alloc_list_entry(); |
841 | if (!entry) |
842 | return 0; |
843 | |
844 | entry->class = this; |
845 | entry->distance = distance; |
846 | entry->trace = *trace; |
847 | /* |
848 | * Since we never remove from the dependency list, the list can |
849 | * be walked lockless by other CPUs, it's only allocation |
850 | * that must be protected by the spinlock. But this also means |
851 | * we must make new entries visible only once writes to the |
852 | * entry become visible - hence the RCU op: |
853 | */ |
854 | list_add_tail_rcu(&entry->entry, head); |
855 | |
856 | return 1; |
857 | } |
858 | |
859 | /* |
860 | * For good efficiency of modular, we use power of 2 |
861 | */ |
862 | #define MAX_CIRCULAR_QUEUE_SIZE 4096UL |
863 | #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) |
864 | |
865 | /* |
866 | * The circular_queue and helpers is used to implement the |
867 | * breadth-first search(BFS)algorithem, by which we can build |
868 | * the shortest path from the next lock to be acquired to the |
869 | * previous held lock if there is a circular between them. |
870 | */ |
871 | struct circular_queue { |
872 | unsigned long element[MAX_CIRCULAR_QUEUE_SIZE]; |
873 | unsigned int front, rear; |
874 | }; |
875 | |
876 | static struct circular_queue lock_cq; |
877 | |
878 | unsigned int max_bfs_queue_depth; |
879 | |
880 | static unsigned int lockdep_dependency_gen_id; |
881 | |
882 | static inline void __cq_init(struct circular_queue *cq) |
883 | { |
884 | cq->front = cq->rear = 0; |
885 | lockdep_dependency_gen_id++; |
886 | } |
887 | |
888 | static inline int __cq_empty(struct circular_queue *cq) |
889 | { |
890 | return (cq->front == cq->rear); |
891 | } |
892 | |
893 | static inline int __cq_full(struct circular_queue *cq) |
894 | { |
895 | return ((cq->rear + 1) & CQ_MASK) == cq->front; |
896 | } |
897 | |
898 | static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) |
899 | { |
900 | if (__cq_full(cq)) |
901 | return -1; |
902 | |
903 | cq->element[cq->rear] = elem; |
904 | cq->rear = (cq->rear + 1) & CQ_MASK; |
905 | return 0; |
906 | } |
907 | |
908 | static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) |
909 | { |
910 | if (__cq_empty(cq)) |
911 | return -1; |
912 | |
913 | *elem = cq->element[cq->front]; |
914 | cq->front = (cq->front + 1) & CQ_MASK; |
915 | return 0; |
916 | } |
917 | |
918 | static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) |
919 | { |
920 | return (cq->rear - cq->front) & CQ_MASK; |
921 | } |
922 | |
923 | static inline void mark_lock_accessed(struct lock_list *lock, |
924 | struct lock_list *parent) |
925 | { |
926 | unsigned long nr; |
927 | |
928 | nr = lock - list_entries; |
929 | WARN_ON(nr >= nr_list_entries); |
930 | lock->parent = parent; |
931 | lock->class->dep_gen_id = lockdep_dependency_gen_id; |
932 | } |
933 | |
934 | static inline unsigned long lock_accessed(struct lock_list *lock) |
935 | { |
936 | unsigned long nr; |
937 | |
938 | nr = lock - list_entries; |
939 | WARN_ON(nr >= nr_list_entries); |
940 | return lock->class->dep_gen_id == lockdep_dependency_gen_id; |
941 | } |
942 | |
943 | static inline struct lock_list *get_lock_parent(struct lock_list *child) |
944 | { |
945 | return child->parent; |
946 | } |
947 | |
948 | static inline int get_lock_depth(struct lock_list *child) |
949 | { |
950 | int depth = 0; |
951 | struct lock_list *parent; |
952 | |
953 | while ((parent = get_lock_parent(child))) { |
954 | child = parent; |
955 | depth++; |
956 | } |
957 | return depth; |
958 | } |
959 | |
960 | static int __bfs(struct lock_list *source_entry, |
961 | void *data, |
962 | int (*match)(struct lock_list *entry, void *data), |
963 | struct lock_list **target_entry, |
964 | int forward) |
965 | { |
966 | struct lock_list *entry; |
967 | struct list_head *head; |
968 | struct circular_queue *cq = &lock_cq; |
969 | int ret = 1; |
970 | |
971 | if (match(source_entry, data)) { |
972 | *target_entry = source_entry; |
973 | ret = 0; |
974 | goto exit; |
975 | } |
976 | |
977 | if (forward) |
978 | head = &source_entry->class->locks_after; |
979 | else |
980 | head = &source_entry->class->locks_before; |
981 | |
982 | if (list_empty(head)) |
983 | goto exit; |
984 | |
985 | __cq_init(cq); |
986 | __cq_enqueue(cq, (unsigned long)source_entry); |
987 | |
988 | while (!__cq_empty(cq)) { |
989 | struct lock_list *lock; |
990 | |
991 | __cq_dequeue(cq, (unsigned long *)&lock); |
992 | |
993 | if (!lock->class) { |
994 | ret = -2; |
995 | goto exit; |
996 | } |
997 | |
998 | if (forward) |
999 | head = &lock->class->locks_after; |
1000 | else |
1001 | head = &lock->class->locks_before; |
1002 | |
1003 | list_for_each_entry(entry, head, entry) { |
1004 | if (!lock_accessed(entry)) { |
1005 | unsigned int cq_depth; |
1006 | mark_lock_accessed(entry, lock); |
1007 | if (match(entry, data)) { |
1008 | *target_entry = entry; |
1009 | ret = 0; |
1010 | goto exit; |
1011 | } |
1012 | |
1013 | if (__cq_enqueue(cq, (unsigned long)entry)) { |
1014 | ret = -1; |
1015 | goto exit; |
1016 | } |
1017 | cq_depth = __cq_get_elem_count(cq); |
1018 | if (max_bfs_queue_depth < cq_depth) |
1019 | max_bfs_queue_depth = cq_depth; |
1020 | } |
1021 | } |
1022 | } |
1023 | exit: |
1024 | return ret; |
1025 | } |
1026 | |
1027 | static inline int __bfs_forwards(struct lock_list *src_entry, |
1028 | void *data, |
1029 | int (*match)(struct lock_list *entry, void *data), |
1030 | struct lock_list **target_entry) |
1031 | { |
1032 | return __bfs(src_entry, data, match, target_entry, 1); |
1033 | |
1034 | } |
1035 | |
1036 | static inline int __bfs_backwards(struct lock_list *src_entry, |
1037 | void *data, |
1038 | int (*match)(struct lock_list *entry, void *data), |
1039 | struct lock_list **target_entry) |
1040 | { |
1041 | return __bfs(src_entry, data, match, target_entry, 0); |
1042 | |
1043 | } |
1044 | |
1045 | /* |
1046 | * Recursive, forwards-direction lock-dependency checking, used for |
1047 | * both noncyclic checking and for hardirq-unsafe/softirq-unsafe |
1048 | * checking. |
1049 | */ |
1050 | |
1051 | /* |
1052 | * Print a dependency chain entry (this is only done when a deadlock |
1053 | * has been detected): |
1054 | */ |
1055 | static noinline int |
1056 | print_circular_bug_entry(struct lock_list *target, int depth) |
1057 | { |
1058 | if (debug_locks_silent) |
1059 | return 0; |
1060 | printk("\n-> #%u", depth); |
1061 | print_lock_name(target->class); |
1062 | printk(":\n"); |
1063 | print_stack_trace(&target->trace, 6); |
1064 | |
1065 | return 0; |
1066 | } |
1067 | |
1068 | static void |
1069 | print_circular_lock_scenario(struct held_lock *src, |
1070 | struct held_lock *tgt, |
1071 | struct lock_list *prt) |
1072 | { |
1073 | struct lock_class *source = hlock_class(src); |
1074 | struct lock_class *target = hlock_class(tgt); |
1075 | struct lock_class *parent = prt->class; |
1076 | |
1077 | /* |
1078 | * A direct locking problem where unsafe_class lock is taken |
1079 | * directly by safe_class lock, then all we need to show |
1080 | * is the deadlock scenario, as it is obvious that the |
1081 | * unsafe lock is taken under the safe lock. |
1082 | * |
1083 | * But if there is a chain instead, where the safe lock takes |
1084 | * an intermediate lock (middle_class) where this lock is |
1085 | * not the same as the safe lock, then the lock chain is |
1086 | * used to describe the problem. Otherwise we would need |
1087 | * to show a different CPU case for each link in the chain |
1088 | * from the safe_class lock to the unsafe_class lock. |
1089 | */ |
1090 | if (parent != source) { |
1091 | printk("Chain exists of:\n "); |
1092 | __print_lock_name(source); |
1093 | printk(" --> "); |
1094 | __print_lock_name(parent); |
1095 | printk(" --> "); |
1096 | __print_lock_name(target); |
1097 | printk("\n\n"); |
1098 | } |
1099 | |
1100 | printk(" Possible unsafe locking scenario:\n\n"); |
1101 | printk(" CPU0 CPU1\n"); |
1102 | printk(" ---- ----\n"); |
1103 | printk(" lock("); |
1104 | __print_lock_name(target); |
1105 | printk(");\n"); |
1106 | printk(" lock("); |
1107 | __print_lock_name(parent); |
1108 | printk(");\n"); |
1109 | printk(" lock("); |
1110 | __print_lock_name(target); |
1111 | printk(");\n"); |
1112 | printk(" lock("); |
1113 | __print_lock_name(source); |
1114 | printk(");\n"); |
1115 | printk("\n *** DEADLOCK ***\n\n"); |
1116 | } |
1117 | |
1118 | /* |
1119 | * When a circular dependency is detected, print the |
1120 | * header first: |
1121 | */ |
1122 | static noinline int |
1123 | print_circular_bug_header(struct lock_list *entry, unsigned int depth, |
1124 | struct held_lock *check_src, |
1125 | struct held_lock *check_tgt) |
1126 | { |
1127 | struct task_struct *curr = current; |
1128 | |
1129 | if (debug_locks_silent) |
1130 | return 0; |
1131 | |
1132 | printk("\n=======================================================\n"); |
1133 | printk( "[ INFO: possible circular locking dependency detected ]\n"); |
1134 | print_kernel_version(); |
1135 | printk( "-------------------------------------------------------\n"); |
1136 | printk("%s/%d is trying to acquire lock:\n", |
1137 | curr->comm, task_pid_nr(curr)); |
1138 | print_lock(check_src); |
1139 | printk("\nbut task is already holding lock:\n"); |
1140 | print_lock(check_tgt); |
1141 | printk("\nwhich lock already depends on the new lock.\n\n"); |
1142 | printk("\nthe existing dependency chain (in reverse order) is:\n"); |
1143 | |
1144 | print_circular_bug_entry(entry, depth); |
1145 | |
1146 | return 0; |
1147 | } |
1148 | |
1149 | static inline int class_equal(struct lock_list *entry, void *data) |
1150 | { |
1151 | return entry->class == data; |
1152 | } |
1153 | |
1154 | static noinline int print_circular_bug(struct lock_list *this, |
1155 | struct lock_list *target, |
1156 | struct held_lock *check_src, |
1157 | struct held_lock *check_tgt) |
1158 | { |
1159 | struct task_struct *curr = current; |
1160 | struct lock_list *parent; |
1161 | struct lock_list *first_parent; |
1162 | int depth; |
1163 | |
1164 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
1165 | return 0; |
1166 | |
1167 | if (!save_trace(&this->trace)) |
1168 | return 0; |
1169 | |
1170 | depth = get_lock_depth(target); |
1171 | |
1172 | print_circular_bug_header(target, depth, check_src, check_tgt); |
1173 | |
1174 | parent = get_lock_parent(target); |
1175 | first_parent = parent; |
1176 | |
1177 | while (parent) { |
1178 | print_circular_bug_entry(parent, --depth); |
1179 | parent = get_lock_parent(parent); |
1180 | } |
1181 | |
1182 | printk("\nother info that might help us debug this:\n\n"); |
1183 | print_circular_lock_scenario(check_src, check_tgt, |
1184 | first_parent); |
1185 | |
1186 | lockdep_print_held_locks(curr); |
1187 | |
1188 | printk("\nstack backtrace:\n"); |
1189 | dump_stack(); |
1190 | |
1191 | return 0; |
1192 | } |
1193 | |
1194 | static noinline int print_bfs_bug(int ret) |
1195 | { |
1196 | if (!debug_locks_off_graph_unlock()) |
1197 | return 0; |
1198 | |
1199 | WARN(1, "lockdep bfs error:%d\n", ret); |
1200 | |
1201 | return 0; |
1202 | } |
1203 | |
1204 | static int noop_count(struct lock_list *entry, void *data) |
1205 | { |
1206 | (*(unsigned long *)data)++; |
1207 | return 0; |
1208 | } |
1209 | |
1210 | unsigned long __lockdep_count_forward_deps(struct lock_list *this) |
1211 | { |
1212 | unsigned long count = 0; |
1213 | struct lock_list *uninitialized_var(target_entry); |
1214 | |
1215 | __bfs_forwards(this, (void *)&count, noop_count, &target_entry); |
1216 | |
1217 | return count; |
1218 | } |
1219 | unsigned long lockdep_count_forward_deps(struct lock_class *class) |
1220 | { |
1221 | unsigned long ret, flags; |
1222 | struct lock_list this; |
1223 | |
1224 | this.parent = NULL; |
1225 | this.class = class; |
1226 | |
1227 | local_irq_save(flags); |
1228 | arch_spin_lock(&lockdep_lock); |
1229 | ret = __lockdep_count_forward_deps(&this); |
1230 | arch_spin_unlock(&lockdep_lock); |
1231 | local_irq_restore(flags); |
1232 | |
1233 | return ret; |
1234 | } |
1235 | |
1236 | unsigned long __lockdep_count_backward_deps(struct lock_list *this) |
1237 | { |
1238 | unsigned long count = 0; |
1239 | struct lock_list *uninitialized_var(target_entry); |
1240 | |
1241 | __bfs_backwards(this, (void *)&count, noop_count, &target_entry); |
1242 | |
1243 | return count; |
1244 | } |
1245 | |
1246 | unsigned long lockdep_count_backward_deps(struct lock_class *class) |
1247 | { |
1248 | unsigned long ret, flags; |
1249 | struct lock_list this; |
1250 | |
1251 | this.parent = NULL; |
1252 | this.class = class; |
1253 | |
1254 | local_irq_save(flags); |
1255 | arch_spin_lock(&lockdep_lock); |
1256 | ret = __lockdep_count_backward_deps(&this); |
1257 | arch_spin_unlock(&lockdep_lock); |
1258 | local_irq_restore(flags); |
1259 | |
1260 | return ret; |
1261 | } |
1262 | |
1263 | /* |
1264 | * Prove that the dependency graph starting at <entry> can not |
1265 | * lead to <target>. Print an error and return 0 if it does. |
1266 | */ |
1267 | static noinline int |
1268 | check_noncircular(struct lock_list *root, struct lock_class *target, |
1269 | struct lock_list **target_entry) |
1270 | { |
1271 | int result; |
1272 | |
1273 | debug_atomic_inc(nr_cyclic_checks); |
1274 | |
1275 | result = __bfs_forwards(root, target, class_equal, target_entry); |
1276 | |
1277 | return result; |
1278 | } |
1279 | |
1280 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
1281 | /* |
1282 | * Forwards and backwards subgraph searching, for the purposes of |
1283 | * proving that two subgraphs can be connected by a new dependency |
1284 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. |
1285 | */ |
1286 | |
1287 | static inline int usage_match(struct lock_list *entry, void *bit) |
1288 | { |
1289 | return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); |
1290 | } |
1291 | |
1292 | |
1293 | |
1294 | /* |
1295 | * Find a node in the forwards-direction dependency sub-graph starting |
1296 | * at @root->class that matches @bit. |
1297 | * |
1298 | * Return 0 if such a node exists in the subgraph, and put that node |
1299 | * into *@target_entry. |
1300 | * |
1301 | * Return 1 otherwise and keep *@target_entry unchanged. |
1302 | * Return <0 on error. |
1303 | */ |
1304 | static int |
1305 | find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, |
1306 | struct lock_list **target_entry) |
1307 | { |
1308 | int result; |
1309 | |
1310 | debug_atomic_inc(nr_find_usage_forwards_checks); |
1311 | |
1312 | result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); |
1313 | |
1314 | return result; |
1315 | } |
1316 | |
1317 | /* |
1318 | * Find a node in the backwards-direction dependency sub-graph starting |
1319 | * at @root->class that matches @bit. |
1320 | * |
1321 | * Return 0 if such a node exists in the subgraph, and put that node |
1322 | * into *@target_entry. |
1323 | * |
1324 | * Return 1 otherwise and keep *@target_entry unchanged. |
1325 | * Return <0 on error. |
1326 | */ |
1327 | static int |
1328 | find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, |
1329 | struct lock_list **target_entry) |
1330 | { |
1331 | int result; |
1332 | |
1333 | debug_atomic_inc(nr_find_usage_backwards_checks); |
1334 | |
1335 | result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); |
1336 | |
1337 | return result; |
1338 | } |
1339 | |
1340 | static void print_lock_class_header(struct lock_class *class, int depth) |
1341 | { |
1342 | int bit; |
1343 | |
1344 | printk("%*s->", depth, ""); |
1345 | print_lock_name(class); |
1346 | printk(" ops: %lu", class->ops); |
1347 | printk(" {\n"); |
1348 | |
1349 | for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { |
1350 | if (class->usage_mask & (1 << bit)) { |
1351 | int len = depth; |
1352 | |
1353 | len += printk("%*s %s", depth, "", usage_str[bit]); |
1354 | len += printk(" at:\n"); |
1355 | print_stack_trace(class->usage_traces + bit, len); |
1356 | } |
1357 | } |
1358 | printk("%*s }\n", depth, ""); |
1359 | |
1360 | printk("%*s ... key at: ",depth,""); |
1361 | print_ip_sym((unsigned long)class->key); |
1362 | } |
1363 | |
1364 | /* |
1365 | * printk the shortest lock dependencies from @start to @end in reverse order: |
1366 | */ |
1367 | static void __used |
1368 | print_shortest_lock_dependencies(struct lock_list *leaf, |
1369 | struct lock_list *root) |
1370 | { |
1371 | struct lock_list *entry = leaf; |
1372 | int depth; |
1373 | |
1374 | /*compute depth from generated tree by BFS*/ |
1375 | depth = get_lock_depth(leaf); |
1376 | |
1377 | do { |
1378 | print_lock_class_header(entry->class, depth); |
1379 | printk("%*s ... acquired at:\n", depth, ""); |
1380 | print_stack_trace(&entry->trace, 2); |
1381 | printk("\n"); |
1382 | |
1383 | if (depth == 0 && (entry != root)) { |
1384 | printk("lockdep:%s bad path found in chain graph\n", __func__); |
1385 | break; |
1386 | } |
1387 | |
1388 | entry = get_lock_parent(entry); |
1389 | depth--; |
1390 | } while (entry && (depth >= 0)); |
1391 | |
1392 | return; |
1393 | } |
1394 | |
1395 | static void |
1396 | print_irq_lock_scenario(struct lock_list *safe_entry, |
1397 | struct lock_list *unsafe_entry, |
1398 | struct lock_class *prev_class, |
1399 | struct lock_class *next_class) |
1400 | { |
1401 | struct lock_class *safe_class = safe_entry->class; |
1402 | struct lock_class *unsafe_class = unsafe_entry->class; |
1403 | struct lock_class *middle_class = prev_class; |
1404 | |
1405 | if (middle_class == safe_class) |
1406 | middle_class = next_class; |
1407 | |
1408 | /* |
1409 | * A direct locking problem where unsafe_class lock is taken |
1410 | * directly by safe_class lock, then all we need to show |
1411 | * is the deadlock scenario, as it is obvious that the |
1412 | * unsafe lock is taken under the safe lock. |
1413 | * |
1414 | * But if there is a chain instead, where the safe lock takes |
1415 | * an intermediate lock (middle_class) where this lock is |
1416 | * not the same as the safe lock, then the lock chain is |
1417 | * used to describe the problem. Otherwise we would need |
1418 | * to show a different CPU case for each link in the chain |
1419 | * from the safe_class lock to the unsafe_class lock. |
1420 | */ |
1421 | if (middle_class != unsafe_class) { |
1422 | printk("Chain exists of:\n "); |
1423 | __print_lock_name(safe_class); |
1424 | printk(" --> "); |
1425 | __print_lock_name(middle_class); |
1426 | printk(" --> "); |
1427 | __print_lock_name(unsafe_class); |
1428 | printk("\n\n"); |
1429 | } |
1430 | |
1431 | printk(" Possible interrupt unsafe locking scenario:\n\n"); |
1432 | printk(" CPU0 CPU1\n"); |
1433 | printk(" ---- ----\n"); |
1434 | printk(" lock("); |
1435 | __print_lock_name(unsafe_class); |
1436 | printk(");\n"); |
1437 | printk(" local_irq_disable();\n"); |
1438 | printk(" lock("); |
1439 | __print_lock_name(safe_class); |
1440 | printk(");\n"); |
1441 | printk(" lock("); |
1442 | __print_lock_name(middle_class); |
1443 | printk(");\n"); |
1444 | printk(" <Interrupt>\n"); |
1445 | printk(" lock("); |
1446 | __print_lock_name(safe_class); |
1447 | printk(");\n"); |
1448 | printk("\n *** DEADLOCK ***\n\n"); |
1449 | } |
1450 | |
1451 | static int |
1452 | print_bad_irq_dependency(struct task_struct *curr, |
1453 | struct lock_list *prev_root, |
1454 | struct lock_list *next_root, |
1455 | struct lock_list *backwards_entry, |
1456 | struct lock_list *forwards_entry, |
1457 | struct held_lock *prev, |
1458 | struct held_lock *next, |
1459 | enum lock_usage_bit bit1, |
1460 | enum lock_usage_bit bit2, |
1461 | const char *irqclass) |
1462 | { |
1463 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
1464 | return 0; |
1465 | |
1466 | printk("\n======================================================\n"); |
1467 | printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", |
1468 | irqclass, irqclass); |
1469 | print_kernel_version(); |
1470 | printk( "------------------------------------------------------\n"); |
1471 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", |
1472 | curr->comm, task_pid_nr(curr), |
1473 | curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, |
1474 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, |
1475 | curr->hardirqs_enabled, |
1476 | curr->softirqs_enabled); |
1477 | print_lock(next); |
1478 | |
1479 | printk("\nand this task is already holding:\n"); |
1480 | print_lock(prev); |
1481 | printk("which would create a new lock dependency:\n"); |
1482 | print_lock_name(hlock_class(prev)); |
1483 | printk(" ->"); |
1484 | print_lock_name(hlock_class(next)); |
1485 | printk("\n"); |
1486 | |
1487 | printk("\nbut this new dependency connects a %s-irq-safe lock:\n", |
1488 | irqclass); |
1489 | print_lock_name(backwards_entry->class); |
1490 | printk("\n... which became %s-irq-safe at:\n", irqclass); |
1491 | |
1492 | print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); |
1493 | |
1494 | printk("\nto a %s-irq-unsafe lock:\n", irqclass); |
1495 | print_lock_name(forwards_entry->class); |
1496 | printk("\n... which became %s-irq-unsafe at:\n", irqclass); |
1497 | printk("..."); |
1498 | |
1499 | print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); |
1500 | |
1501 | printk("\nother info that might help us debug this:\n\n"); |
1502 | print_irq_lock_scenario(backwards_entry, forwards_entry, |
1503 | hlock_class(prev), hlock_class(next)); |
1504 | |
1505 | lockdep_print_held_locks(curr); |
1506 | |
1507 | printk("\nthe dependencies between %s-irq-safe lock", irqclass); |
1508 | printk(" and the holding lock:\n"); |
1509 | if (!save_trace(&prev_root->trace)) |
1510 | return 0; |
1511 | print_shortest_lock_dependencies(backwards_entry, prev_root); |
1512 | |
1513 | printk("\nthe dependencies between the lock to be acquired"); |
1514 | printk(" and %s-irq-unsafe lock:\n", irqclass); |
1515 | if (!save_trace(&next_root->trace)) |
1516 | return 0; |
1517 | print_shortest_lock_dependencies(forwards_entry, next_root); |
1518 | |
1519 | printk("\nstack backtrace:\n"); |
1520 | dump_stack(); |
1521 | |
1522 | return 0; |
1523 | } |
1524 | |
1525 | static int |
1526 | check_usage(struct task_struct *curr, struct held_lock *prev, |
1527 | struct held_lock *next, enum lock_usage_bit bit_backwards, |
1528 | enum lock_usage_bit bit_forwards, const char *irqclass) |
1529 | { |
1530 | int ret; |
1531 | struct lock_list this, that; |
1532 | struct lock_list *uninitialized_var(target_entry); |
1533 | struct lock_list *uninitialized_var(target_entry1); |
1534 | |
1535 | this.parent = NULL; |
1536 | |
1537 | this.class = hlock_class(prev); |
1538 | ret = find_usage_backwards(&this, bit_backwards, &target_entry); |
1539 | if (ret < 0) |
1540 | return print_bfs_bug(ret); |
1541 | if (ret == 1) |
1542 | return ret; |
1543 | |
1544 | that.parent = NULL; |
1545 | that.class = hlock_class(next); |
1546 | ret = find_usage_forwards(&that, bit_forwards, &target_entry1); |
1547 | if (ret < 0) |
1548 | return print_bfs_bug(ret); |
1549 | if (ret == 1) |
1550 | return ret; |
1551 | |
1552 | return print_bad_irq_dependency(curr, &this, &that, |
1553 | target_entry, target_entry1, |
1554 | prev, next, |
1555 | bit_backwards, bit_forwards, irqclass); |
1556 | } |
1557 | |
1558 | static const char *state_names[] = { |
1559 | #define LOCKDEP_STATE(__STATE) \ |
1560 | __stringify(__STATE), |
1561 | #include "lockdep_states.h" |
1562 | #undef LOCKDEP_STATE |
1563 | }; |
1564 | |
1565 | static const char *state_rnames[] = { |
1566 | #define LOCKDEP_STATE(__STATE) \ |
1567 | __stringify(__STATE)"-READ", |
1568 | #include "lockdep_states.h" |
1569 | #undef LOCKDEP_STATE |
1570 | }; |
1571 | |
1572 | static inline const char *state_name(enum lock_usage_bit bit) |
1573 | { |
1574 | return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2]; |
1575 | } |
1576 | |
1577 | static int exclusive_bit(int new_bit) |
1578 | { |
1579 | /* |
1580 | * USED_IN |
1581 | * USED_IN_READ |
1582 | * ENABLED |
1583 | * ENABLED_READ |
1584 | * |
1585 | * bit 0 - write/read |
1586 | * bit 1 - used_in/enabled |
1587 | * bit 2+ state |
1588 | */ |
1589 | |
1590 | int state = new_bit & ~3; |
1591 | int dir = new_bit & 2; |
1592 | |
1593 | /* |
1594 | * keep state, bit flip the direction and strip read. |
1595 | */ |
1596 | return state | (dir ^ 2); |
1597 | } |
1598 | |
1599 | static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, |
1600 | struct held_lock *next, enum lock_usage_bit bit) |
1601 | { |
1602 | /* |
1603 | * Prove that the new dependency does not connect a hardirq-safe |
1604 | * lock with a hardirq-unsafe lock - to achieve this we search |
1605 | * the backwards-subgraph starting at <prev>, and the |
1606 | * forwards-subgraph starting at <next>: |
1607 | */ |
1608 | if (!check_usage(curr, prev, next, bit, |
1609 | exclusive_bit(bit), state_name(bit))) |
1610 | return 0; |
1611 | |
1612 | bit++; /* _READ */ |
1613 | |
1614 | /* |
1615 | * Prove that the new dependency does not connect a hardirq-safe-read |
1616 | * lock with a hardirq-unsafe lock - to achieve this we search |
1617 | * the backwards-subgraph starting at <prev>, and the |
1618 | * forwards-subgraph starting at <next>: |
1619 | */ |
1620 | if (!check_usage(curr, prev, next, bit, |
1621 | exclusive_bit(bit), state_name(bit))) |
1622 | return 0; |
1623 | |
1624 | return 1; |
1625 | } |
1626 | |
1627 | static int |
1628 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, |
1629 | struct held_lock *next) |
1630 | { |
1631 | #define LOCKDEP_STATE(__STATE) \ |
1632 | if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ |
1633 | return 0; |
1634 | #include "lockdep_states.h" |
1635 | #undef LOCKDEP_STATE |
1636 | |
1637 | return 1; |
1638 | } |
1639 | |
1640 | static void inc_chains(void) |
1641 | { |
1642 | if (current->hardirq_context) |
1643 | nr_hardirq_chains++; |
1644 | else { |
1645 | if (current->softirq_context) |
1646 | nr_softirq_chains++; |
1647 | else |
1648 | nr_process_chains++; |
1649 | } |
1650 | } |
1651 | |
1652 | #else |
1653 | |
1654 | static inline int |
1655 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, |
1656 | struct held_lock *next) |
1657 | { |
1658 | return 1; |
1659 | } |
1660 | |
1661 | static inline void inc_chains(void) |
1662 | { |
1663 | nr_process_chains++; |
1664 | } |
1665 | |
1666 | #endif |
1667 | |
1668 | static void |
1669 | print_deadlock_scenario(struct held_lock *nxt, |
1670 | struct held_lock *prv) |
1671 | { |
1672 | struct lock_class *next = hlock_class(nxt); |
1673 | struct lock_class *prev = hlock_class(prv); |
1674 | |
1675 | printk(" Possible unsafe locking scenario:\n\n"); |
1676 | printk(" CPU0\n"); |
1677 | printk(" ----\n"); |
1678 | printk(" lock("); |
1679 | __print_lock_name(prev); |
1680 | printk(");\n"); |
1681 | printk(" lock("); |
1682 | __print_lock_name(next); |
1683 | printk(");\n"); |
1684 | printk("\n *** DEADLOCK ***\n\n"); |
1685 | printk(" May be due to missing lock nesting notation\n\n"); |
1686 | } |
1687 | |
1688 | static int |
1689 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, |
1690 | struct held_lock *next) |
1691 | { |
1692 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
1693 | return 0; |
1694 | |
1695 | printk("\n=============================================\n"); |
1696 | printk( "[ INFO: possible recursive locking detected ]\n"); |
1697 | print_kernel_version(); |
1698 | printk( "---------------------------------------------\n"); |
1699 | printk("%s/%d is trying to acquire lock:\n", |
1700 | curr->comm, task_pid_nr(curr)); |
1701 | print_lock(next); |
1702 | printk("\nbut task is already holding lock:\n"); |
1703 | print_lock(prev); |
1704 | |
1705 | printk("\nother info that might help us debug this:\n"); |
1706 | print_deadlock_scenario(next, prev); |
1707 | lockdep_print_held_locks(curr); |
1708 | |
1709 | printk("\nstack backtrace:\n"); |
1710 | dump_stack(); |
1711 | |
1712 | return 0; |
1713 | } |
1714 | |
1715 | /* |
1716 | * Check whether we are holding such a class already. |
1717 | * |
1718 | * (Note that this has to be done separately, because the graph cannot |
1719 | * detect such classes of deadlocks.) |
1720 | * |
1721 | * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read |
1722 | */ |
1723 | static int |
1724 | check_deadlock(struct task_struct *curr, struct held_lock *next, |
1725 | struct lockdep_map *next_instance, int read) |
1726 | { |
1727 | struct held_lock *prev; |
1728 | struct held_lock *nest = NULL; |
1729 | int i; |
1730 | |
1731 | for (i = 0; i < curr->lockdep_depth; i++) { |
1732 | prev = curr->held_locks + i; |
1733 | |
1734 | if (prev->instance == next->nest_lock) |
1735 | nest = prev; |
1736 | |
1737 | if (hlock_class(prev) != hlock_class(next)) |
1738 | continue; |
1739 | |
1740 | /* |
1741 | * Allow read-after-read recursion of the same |
1742 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
1743 | */ |
1744 | if ((read == 2) && prev->read) |
1745 | return 2; |
1746 | |
1747 | /* |
1748 | * We're holding the nest_lock, which serializes this lock's |
1749 | * nesting behaviour. |
1750 | */ |
1751 | if (nest) |
1752 | return 2; |
1753 | |
1754 | return print_deadlock_bug(curr, prev, next); |
1755 | } |
1756 | return 1; |
1757 | } |
1758 | |
1759 | /* |
1760 | * There was a chain-cache miss, and we are about to add a new dependency |
1761 | * to a previous lock. We recursively validate the following rules: |
1762 | * |
1763 | * - would the adding of the <prev> -> <next> dependency create a |
1764 | * circular dependency in the graph? [== circular deadlock] |
1765 | * |
1766 | * - does the new prev->next dependency connect any hardirq-safe lock |
1767 | * (in the full backwards-subgraph starting at <prev>) with any |
1768 | * hardirq-unsafe lock (in the full forwards-subgraph starting at |
1769 | * <next>)? [== illegal lock inversion with hardirq contexts] |
1770 | * |
1771 | * - does the new prev->next dependency connect any softirq-safe lock |
1772 | * (in the full backwards-subgraph starting at <prev>) with any |
1773 | * softirq-unsafe lock (in the full forwards-subgraph starting at |
1774 | * <next>)? [== illegal lock inversion with softirq contexts] |
1775 | * |
1776 | * any of these scenarios could lead to a deadlock. |
1777 | * |
1778 | * Then if all the validations pass, we add the forwards and backwards |
1779 | * dependency. |
1780 | */ |
1781 | static int |
1782 | check_prev_add(struct task_struct *curr, struct held_lock *prev, |
1783 | struct held_lock *next, int distance, int trylock_loop) |
1784 | { |
1785 | struct lock_list *entry; |
1786 | int ret; |
1787 | struct lock_list this; |
1788 | struct lock_list *uninitialized_var(target_entry); |
1789 | /* |
1790 | * Static variable, serialized by the graph_lock(). |
1791 | * |
1792 | * We use this static variable to save the stack trace in case |
1793 | * we call into this function multiple times due to encountering |
1794 | * trylocks in the held lock stack. |
1795 | */ |
1796 | static struct stack_trace trace; |
1797 | |
1798 | /* |
1799 | * Prove that the new <prev> -> <next> dependency would not |
1800 | * create a circular dependency in the graph. (We do this by |
1801 | * forward-recursing into the graph starting at <next>, and |
1802 | * checking whether we can reach <prev>.) |
1803 | * |
1804 | * We are using global variables to control the recursion, to |
1805 | * keep the stackframe size of the recursive functions low: |
1806 | */ |
1807 | this.class = hlock_class(next); |
1808 | this.parent = NULL; |
1809 | ret = check_noncircular(&this, hlock_class(prev), &target_entry); |
1810 | if (unlikely(!ret)) |
1811 | return print_circular_bug(&this, target_entry, next, prev); |
1812 | else if (unlikely(ret < 0)) |
1813 | return print_bfs_bug(ret); |
1814 | |
1815 | if (!check_prev_add_irq(curr, prev, next)) |
1816 | return 0; |
1817 | |
1818 | /* |
1819 | * For recursive read-locks we do all the dependency checks, |
1820 | * but we dont store read-triggered dependencies (only |
1821 | * write-triggered dependencies). This ensures that only the |
1822 | * write-side dependencies matter, and that if for example a |
1823 | * write-lock never takes any other locks, then the reads are |
1824 | * equivalent to a NOP. |
1825 | */ |
1826 | if (next->read == 2 || prev->read == 2) |
1827 | return 1; |
1828 | /* |
1829 | * Is the <prev> -> <next> dependency already present? |
1830 | * |
1831 | * (this may occur even though this is a new chain: consider |
1832 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 |
1833 | * chains - the second one will be new, but L1 already has |
1834 | * L2 added to its dependency list, due to the first chain.) |
1835 | */ |
1836 | list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { |
1837 | if (entry->class == hlock_class(next)) { |
1838 | if (distance == 1) |
1839 | entry->distance = 1; |
1840 | return 2; |
1841 | } |
1842 | } |
1843 | |
1844 | if (!trylock_loop && !save_trace(&trace)) |
1845 | return 0; |
1846 | |
1847 | /* |
1848 | * Ok, all validations passed, add the new lock |
1849 | * to the previous lock's dependency list: |
1850 | */ |
1851 | ret = add_lock_to_list(hlock_class(prev), hlock_class(next), |
1852 | &hlock_class(prev)->locks_after, |
1853 | next->acquire_ip, distance, &trace); |
1854 | |
1855 | if (!ret) |
1856 | return 0; |
1857 | |
1858 | ret = add_lock_to_list(hlock_class(next), hlock_class(prev), |
1859 | &hlock_class(next)->locks_before, |
1860 | next->acquire_ip, distance, &trace); |
1861 | if (!ret) |
1862 | return 0; |
1863 | |
1864 | /* |
1865 | * Debugging printouts: |
1866 | */ |
1867 | if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) { |
1868 | graph_unlock(); |
1869 | printk("\n new dependency: "); |
1870 | print_lock_name(hlock_class(prev)); |
1871 | printk(" => "); |
1872 | print_lock_name(hlock_class(next)); |
1873 | printk("\n"); |
1874 | dump_stack(); |
1875 | return graph_lock(); |
1876 | } |
1877 | return 1; |
1878 | } |
1879 | |
1880 | /* |
1881 | * Add the dependency to all directly-previous locks that are 'relevant'. |
1882 | * The ones that are relevant are (in increasing distance from curr): |
1883 | * all consecutive trylock entries and the final non-trylock entry - or |
1884 | * the end of this context's lock-chain - whichever comes first. |
1885 | */ |
1886 | static int |
1887 | check_prevs_add(struct task_struct *curr, struct held_lock *next) |
1888 | { |
1889 | int depth = curr->lockdep_depth; |
1890 | int trylock_loop = 0; |
1891 | struct held_lock *hlock; |
1892 | |
1893 | /* |
1894 | * Debugging checks. |
1895 | * |
1896 | * Depth must not be zero for a non-head lock: |
1897 | */ |
1898 | if (!depth) |
1899 | goto out_bug; |
1900 | /* |
1901 | * At least two relevant locks must exist for this |
1902 | * to be a head: |
1903 | */ |
1904 | if (curr->held_locks[depth].irq_context != |
1905 | curr->held_locks[depth-1].irq_context) |
1906 | goto out_bug; |
1907 | |
1908 | for (;;) { |
1909 | int distance = curr->lockdep_depth - depth + 1; |
1910 | hlock = curr->held_locks + depth-1; |
1911 | /* |
1912 | * Only non-recursive-read entries get new dependencies |
1913 | * added: |
1914 | */ |
1915 | if (hlock->read != 2) { |
1916 | if (!check_prev_add(curr, hlock, next, |
1917 | distance, trylock_loop)) |
1918 | return 0; |
1919 | /* |
1920 | * Stop after the first non-trylock entry, |
1921 | * as non-trylock entries have added their |
1922 | * own direct dependencies already, so this |
1923 | * lock is connected to them indirectly: |
1924 | */ |
1925 | if (!hlock->trylock) |
1926 | break; |
1927 | } |
1928 | depth--; |
1929 | /* |
1930 | * End of lock-stack? |
1931 | */ |
1932 | if (!depth) |
1933 | break; |
1934 | /* |
1935 | * Stop the search if we cross into another context: |
1936 | */ |
1937 | if (curr->held_locks[depth].irq_context != |
1938 | curr->held_locks[depth-1].irq_context) |
1939 | break; |
1940 | trylock_loop = 1; |
1941 | } |
1942 | return 1; |
1943 | out_bug: |
1944 | if (!debug_locks_off_graph_unlock()) |
1945 | return 0; |
1946 | |
1947 | WARN_ON(1); |
1948 | |
1949 | return 0; |
1950 | } |
1951 | |
1952 | unsigned long nr_lock_chains; |
1953 | struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; |
1954 | int nr_chain_hlocks; |
1955 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; |
1956 | |
1957 | struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) |
1958 | { |
1959 | return lock_classes + chain_hlocks[chain->base + i]; |
1960 | } |
1961 | |
1962 | /* |
1963 | * Look up a dependency chain. If the key is not present yet then |
1964 | * add it and return 1 - in this case the new dependency chain is |
1965 | * validated. If the key is already hashed, return 0. |
1966 | * (On return with 1 graph_lock is held.) |
1967 | */ |
1968 | static inline int lookup_chain_cache(struct task_struct *curr, |
1969 | struct held_lock *hlock, |
1970 | u64 chain_key) |
1971 | { |
1972 | struct lock_class *class = hlock_class(hlock); |
1973 | struct list_head *hash_head = chainhashentry(chain_key); |
1974 | struct lock_chain *chain; |
1975 | struct held_lock *hlock_curr, *hlock_next; |
1976 | int i, j; |
1977 | |
1978 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
1979 | return 0; |
1980 | /* |
1981 | * We can walk it lock-free, because entries only get added |
1982 | * to the hash: |
1983 | */ |
1984 | list_for_each_entry(chain, hash_head, entry) { |
1985 | if (chain->chain_key == chain_key) { |
1986 | cache_hit: |
1987 | debug_atomic_inc(chain_lookup_hits); |
1988 | if (very_verbose(class)) |
1989 | printk("\nhash chain already cached, key: " |
1990 | "%016Lx tail class: [%p] %s\n", |
1991 | (unsigned long long)chain_key, |
1992 | class->key, class->name); |
1993 | return 0; |
1994 | } |
1995 | } |
1996 | if (very_verbose(class)) |
1997 | printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", |
1998 | (unsigned long long)chain_key, class->key, class->name); |
1999 | /* |
2000 | * Allocate a new chain entry from the static array, and add |
2001 | * it to the hash: |
2002 | */ |
2003 | if (!graph_lock()) |
2004 | return 0; |
2005 | /* |
2006 | * We have to walk the chain again locked - to avoid duplicates: |
2007 | */ |
2008 | list_for_each_entry(chain, hash_head, entry) { |
2009 | if (chain->chain_key == chain_key) { |
2010 | graph_unlock(); |
2011 | goto cache_hit; |
2012 | } |
2013 | } |
2014 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { |
2015 | if (!debug_locks_off_graph_unlock()) |
2016 | return 0; |
2017 | |
2018 | printk("BUG: MAX_LOCKDEP_CHAINS too low!\n"); |
2019 | printk("turning off the locking correctness validator.\n"); |
2020 | dump_stack(); |
2021 | return 0; |
2022 | } |
2023 | chain = lock_chains + nr_lock_chains++; |
2024 | chain->chain_key = chain_key; |
2025 | chain->irq_context = hlock->irq_context; |
2026 | /* Find the first held_lock of current chain */ |
2027 | hlock_next = hlock; |
2028 | for (i = curr->lockdep_depth - 1; i >= 0; i--) { |
2029 | hlock_curr = curr->held_locks + i; |
2030 | if (hlock_curr->irq_context != hlock_next->irq_context) |
2031 | break; |
2032 | hlock_next = hlock; |
2033 | } |
2034 | i++; |
2035 | chain->depth = curr->lockdep_depth + 1 - i; |
2036 | if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { |
2037 | chain->base = nr_chain_hlocks; |
2038 | nr_chain_hlocks += chain->depth; |
2039 | for (j = 0; j < chain->depth - 1; j++, i++) { |
2040 | int lock_id = curr->held_locks[i].class_idx - 1; |
2041 | chain_hlocks[chain->base + j] = lock_id; |
2042 | } |
2043 | chain_hlocks[chain->base + j] = class - lock_classes; |
2044 | } |
2045 | list_add_tail_rcu(&chain->entry, hash_head); |
2046 | debug_atomic_inc(chain_lookup_misses); |
2047 | inc_chains(); |
2048 | |
2049 | return 1; |
2050 | } |
2051 | |
2052 | static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, |
2053 | struct held_lock *hlock, int chain_head, u64 chain_key) |
2054 | { |
2055 | /* |
2056 | * Trylock needs to maintain the stack of held locks, but it |
2057 | * does not add new dependencies, because trylock can be done |
2058 | * in any order. |
2059 | * |
2060 | * We look up the chain_key and do the O(N^2) check and update of |
2061 | * the dependencies only if this is a new dependency chain. |
2062 | * (If lookup_chain_cache() returns with 1 it acquires |
2063 | * graph_lock for us) |
2064 | */ |
2065 | if (!hlock->trylock && (hlock->check == 2) && |
2066 | lookup_chain_cache(curr, hlock, chain_key)) { |
2067 | /* |
2068 | * Check whether last held lock: |
2069 | * |
2070 | * - is irq-safe, if this lock is irq-unsafe |
2071 | * - is softirq-safe, if this lock is hardirq-unsafe |
2072 | * |
2073 | * And check whether the new lock's dependency graph |
2074 | * could lead back to the previous lock. |
2075 | * |
2076 | * any of these scenarios could lead to a deadlock. If |
2077 | * All validations |
2078 | */ |
2079 | int ret = check_deadlock(curr, hlock, lock, hlock->read); |
2080 | |
2081 | if (!ret) |
2082 | return 0; |
2083 | /* |
2084 | * Mark recursive read, as we jump over it when |
2085 | * building dependencies (just like we jump over |
2086 | * trylock entries): |
2087 | */ |
2088 | if (ret == 2) |
2089 | hlock->read = 2; |
2090 | /* |
2091 | * Add dependency only if this lock is not the head |
2092 | * of the chain, and if it's not a secondary read-lock: |
2093 | */ |
2094 | if (!chain_head && ret != 2) |
2095 | if (!check_prevs_add(curr, hlock)) |
2096 | return 0; |
2097 | graph_unlock(); |
2098 | } else |
2099 | /* after lookup_chain_cache(): */ |
2100 | if (unlikely(!debug_locks)) |
2101 | return 0; |
2102 | |
2103 | return 1; |
2104 | } |
2105 | #else |
2106 | static inline int validate_chain(struct task_struct *curr, |
2107 | struct lockdep_map *lock, struct held_lock *hlock, |
2108 | int chain_head, u64 chain_key) |
2109 | { |
2110 | return 1; |
2111 | } |
2112 | #endif |
2113 | |
2114 | /* |
2115 | * We are building curr_chain_key incrementally, so double-check |
2116 | * it from scratch, to make sure that it's done correctly: |
2117 | */ |
2118 | static void check_chain_key(struct task_struct *curr) |
2119 | { |
2120 | #ifdef CONFIG_DEBUG_LOCKDEP |
2121 | struct held_lock *hlock, *prev_hlock = NULL; |
2122 | unsigned int i, id; |
2123 | u64 chain_key = 0; |
2124 | |
2125 | for (i = 0; i < curr->lockdep_depth; i++) { |
2126 | hlock = curr->held_locks + i; |
2127 | if (chain_key != hlock->prev_chain_key) { |
2128 | debug_locks_off(); |
2129 | WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", |
2130 | curr->lockdep_depth, i, |
2131 | (unsigned long long)chain_key, |
2132 | (unsigned long long)hlock->prev_chain_key); |
2133 | return; |
2134 | } |
2135 | id = hlock->class_idx - 1; |
2136 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) |
2137 | return; |
2138 | |
2139 | if (prev_hlock && (prev_hlock->irq_context != |
2140 | hlock->irq_context)) |
2141 | chain_key = 0; |
2142 | chain_key = iterate_chain_key(chain_key, id); |
2143 | prev_hlock = hlock; |
2144 | } |
2145 | if (chain_key != curr->curr_chain_key) { |
2146 | debug_locks_off(); |
2147 | WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", |
2148 | curr->lockdep_depth, i, |
2149 | (unsigned long long)chain_key, |
2150 | (unsigned long long)curr->curr_chain_key); |
2151 | } |
2152 | #endif |
2153 | } |
2154 | |
2155 | static void |
2156 | print_usage_bug_scenario(struct held_lock *lock) |
2157 | { |
2158 | struct lock_class *class = hlock_class(lock); |
2159 | |
2160 | printk(" Possible unsafe locking scenario:\n\n"); |
2161 | printk(" CPU0\n"); |
2162 | printk(" ----\n"); |
2163 | printk(" lock("); |
2164 | __print_lock_name(class); |
2165 | printk(");\n"); |
2166 | printk(" <Interrupt>\n"); |
2167 | printk(" lock("); |
2168 | __print_lock_name(class); |
2169 | printk(");\n"); |
2170 | printk("\n *** DEADLOCK ***\n\n"); |
2171 | } |
2172 | |
2173 | static int |
2174 | print_usage_bug(struct task_struct *curr, struct held_lock *this, |
2175 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) |
2176 | { |
2177 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
2178 | return 0; |
2179 | |
2180 | printk("\n=================================\n"); |
2181 | printk( "[ INFO: inconsistent lock state ]\n"); |
2182 | print_kernel_version(); |
2183 | printk( "---------------------------------\n"); |
2184 | |
2185 | printk("inconsistent {%s} -> {%s} usage.\n", |
2186 | usage_str[prev_bit], usage_str[new_bit]); |
2187 | |
2188 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", |
2189 | curr->comm, task_pid_nr(curr), |
2190 | trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, |
2191 | trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, |
2192 | trace_hardirqs_enabled(curr), |
2193 | trace_softirqs_enabled(curr)); |
2194 | print_lock(this); |
2195 | |
2196 | printk("{%s} state was registered at:\n", usage_str[prev_bit]); |
2197 | print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1); |
2198 | |
2199 | print_irqtrace_events(curr); |
2200 | printk("\nother info that might help us debug this:\n"); |
2201 | print_usage_bug_scenario(this); |
2202 | |
2203 | lockdep_print_held_locks(curr); |
2204 | |
2205 | printk("\nstack backtrace:\n"); |
2206 | dump_stack(); |
2207 | |
2208 | return 0; |
2209 | } |
2210 | |
2211 | /* |
2212 | * Print out an error if an invalid bit is set: |
2213 | */ |
2214 | static inline int |
2215 | valid_state(struct task_struct *curr, struct held_lock *this, |
2216 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) |
2217 | { |
2218 | if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) |
2219 | return print_usage_bug(curr, this, bad_bit, new_bit); |
2220 | return 1; |
2221 | } |
2222 | |
2223 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
2224 | enum lock_usage_bit new_bit); |
2225 | |
2226 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
2227 | |
2228 | /* |
2229 | * print irq inversion bug: |
2230 | */ |
2231 | static int |
2232 | print_irq_inversion_bug(struct task_struct *curr, |
2233 | struct lock_list *root, struct lock_list *other, |
2234 | struct held_lock *this, int forwards, |
2235 | const char *irqclass) |
2236 | { |
2237 | struct lock_list *entry = other; |
2238 | struct lock_list *middle = NULL; |
2239 | int depth; |
2240 | |
2241 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
2242 | return 0; |
2243 | |
2244 | printk("\n=========================================================\n"); |
2245 | printk( "[ INFO: possible irq lock inversion dependency detected ]\n"); |
2246 | print_kernel_version(); |
2247 | printk( "---------------------------------------------------------\n"); |
2248 | printk("%s/%d just changed the state of lock:\n", |
2249 | curr->comm, task_pid_nr(curr)); |
2250 | print_lock(this); |
2251 | if (forwards) |
2252 | printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass); |
2253 | else |
2254 | printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); |
2255 | print_lock_name(other->class); |
2256 | printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); |
2257 | |
2258 | printk("\nother info that might help us debug this:\n"); |
2259 | |
2260 | /* Find a middle lock (if one exists) */ |
2261 | depth = get_lock_depth(other); |
2262 | do { |
2263 | if (depth == 0 && (entry != root)) { |
2264 | printk("lockdep:%s bad path found in chain graph\n", __func__); |
2265 | break; |
2266 | } |
2267 | middle = entry; |
2268 | entry = get_lock_parent(entry); |
2269 | depth--; |
2270 | } while (entry && entry != root && (depth >= 0)); |
2271 | if (forwards) |
2272 | print_irq_lock_scenario(root, other, |
2273 | middle ? middle->class : root->class, other->class); |
2274 | else |
2275 | print_irq_lock_scenario(other, root, |
2276 | middle ? middle->class : other->class, root->class); |
2277 | |
2278 | lockdep_print_held_locks(curr); |
2279 | |
2280 | printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); |
2281 | if (!save_trace(&root->trace)) |
2282 | return 0; |
2283 | print_shortest_lock_dependencies(other, root); |
2284 | |
2285 | printk("\nstack backtrace:\n"); |
2286 | dump_stack(); |
2287 | |
2288 | return 0; |
2289 | } |
2290 | |
2291 | /* |
2292 | * Prove that in the forwards-direction subgraph starting at <this> |
2293 | * there is no lock matching <mask>: |
2294 | */ |
2295 | static int |
2296 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, |
2297 | enum lock_usage_bit bit, const char *irqclass) |
2298 | { |
2299 | int ret; |
2300 | struct lock_list root; |
2301 | struct lock_list *uninitialized_var(target_entry); |
2302 | |
2303 | root.parent = NULL; |
2304 | root.class = hlock_class(this); |
2305 | ret = find_usage_forwards(&root, bit, &target_entry); |
2306 | if (ret < 0) |
2307 | return print_bfs_bug(ret); |
2308 | if (ret == 1) |
2309 | return ret; |
2310 | |
2311 | return print_irq_inversion_bug(curr, &root, target_entry, |
2312 | this, 1, irqclass); |
2313 | } |
2314 | |
2315 | /* |
2316 | * Prove that in the backwards-direction subgraph starting at <this> |
2317 | * there is no lock matching <mask>: |
2318 | */ |
2319 | static int |
2320 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, |
2321 | enum lock_usage_bit bit, const char *irqclass) |
2322 | { |
2323 | int ret; |
2324 | struct lock_list root; |
2325 | struct lock_list *uninitialized_var(target_entry); |
2326 | |
2327 | root.parent = NULL; |
2328 | root.class = hlock_class(this); |
2329 | ret = find_usage_backwards(&root, bit, &target_entry); |
2330 | if (ret < 0) |
2331 | return print_bfs_bug(ret); |
2332 | if (ret == 1) |
2333 | return ret; |
2334 | |
2335 | return print_irq_inversion_bug(curr, &root, target_entry, |
2336 | this, 0, irqclass); |
2337 | } |
2338 | |
2339 | void print_irqtrace_events(struct task_struct *curr) |
2340 | { |
2341 | printk("irq event stamp: %u\n", curr->irq_events); |
2342 | printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event); |
2343 | print_ip_sym(curr->hardirq_enable_ip); |
2344 | printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event); |
2345 | print_ip_sym(curr->hardirq_disable_ip); |
2346 | printk("softirqs last enabled at (%u): ", curr->softirq_enable_event); |
2347 | print_ip_sym(curr->softirq_enable_ip); |
2348 | printk("softirqs last disabled at (%u): ", curr->softirq_disable_event); |
2349 | print_ip_sym(curr->softirq_disable_ip); |
2350 | } |
2351 | |
2352 | static int HARDIRQ_verbose(struct lock_class *class) |
2353 | { |
2354 | #if HARDIRQ_VERBOSE |
2355 | return class_filter(class); |
2356 | #endif |
2357 | return 0; |
2358 | } |
2359 | |
2360 | static int SOFTIRQ_verbose(struct lock_class *class) |
2361 | { |
2362 | #if SOFTIRQ_VERBOSE |
2363 | return class_filter(class); |
2364 | #endif |
2365 | return 0; |
2366 | } |
2367 | |
2368 | static int RECLAIM_FS_verbose(struct lock_class *class) |
2369 | { |
2370 | #if RECLAIM_VERBOSE |
2371 | return class_filter(class); |
2372 | #endif |
2373 | return 0; |
2374 | } |
2375 | |
2376 | #define STRICT_READ_CHECKS 1 |
2377 | |
2378 | static int (*state_verbose_f[])(struct lock_class *class) = { |
2379 | #define LOCKDEP_STATE(__STATE) \ |
2380 | __STATE##_verbose, |
2381 | #include "lockdep_states.h" |
2382 | #undef LOCKDEP_STATE |
2383 | }; |
2384 | |
2385 | static inline int state_verbose(enum lock_usage_bit bit, |
2386 | struct lock_class *class) |
2387 | { |
2388 | return state_verbose_f[bit >> 2](class); |
2389 | } |
2390 | |
2391 | typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, |
2392 | enum lock_usage_bit bit, const char *name); |
2393 | |
2394 | static int |
2395 | mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
2396 | enum lock_usage_bit new_bit) |
2397 | { |
2398 | int excl_bit = exclusive_bit(new_bit); |
2399 | int read = new_bit & 1; |
2400 | int dir = new_bit & 2; |
2401 | |
2402 | /* |
2403 | * mark USED_IN has to look forwards -- to ensure no dependency |
2404 | * has ENABLED state, which would allow recursion deadlocks. |
2405 | * |
2406 | * mark ENABLED has to look backwards -- to ensure no dependee |
2407 | * has USED_IN state, which, again, would allow recursion deadlocks. |
2408 | */ |
2409 | check_usage_f usage = dir ? |
2410 | check_usage_backwards : check_usage_forwards; |
2411 | |
2412 | /* |
2413 | * Validate that this particular lock does not have conflicting |
2414 | * usage states. |
2415 | */ |
2416 | if (!valid_state(curr, this, new_bit, excl_bit)) |
2417 | return 0; |
2418 | |
2419 | /* |
2420 | * Validate that the lock dependencies don't have conflicting usage |
2421 | * states. |
2422 | */ |
2423 | if ((!read || !dir || STRICT_READ_CHECKS) && |
2424 | !usage(curr, this, excl_bit, state_name(new_bit & ~1))) |
2425 | return 0; |
2426 | |
2427 | /* |
2428 | * Check for read in write conflicts |
2429 | */ |
2430 | if (!read) { |
2431 | if (!valid_state(curr, this, new_bit, excl_bit + 1)) |
2432 | return 0; |
2433 | |
2434 | if (STRICT_READ_CHECKS && |
2435 | !usage(curr, this, excl_bit + 1, |
2436 | state_name(new_bit + 1))) |
2437 | return 0; |
2438 | } |
2439 | |
2440 | if (state_verbose(new_bit, hlock_class(this))) |
2441 | return 2; |
2442 | |
2443 | return 1; |
2444 | } |
2445 | |
2446 | enum mark_type { |
2447 | #define LOCKDEP_STATE(__STATE) __STATE, |
2448 | #include "lockdep_states.h" |
2449 | #undef LOCKDEP_STATE |
2450 | }; |
2451 | |
2452 | /* |
2453 | * Mark all held locks with a usage bit: |
2454 | */ |
2455 | static int |
2456 | mark_held_locks(struct task_struct *curr, enum mark_type mark) |
2457 | { |
2458 | enum lock_usage_bit usage_bit; |
2459 | struct held_lock *hlock; |
2460 | int i; |
2461 | |
2462 | for (i = 0; i < curr->lockdep_depth; i++) { |
2463 | hlock = curr->held_locks + i; |
2464 | |
2465 | usage_bit = 2 + (mark << 2); /* ENABLED */ |
2466 | if (hlock->read) |
2467 | usage_bit += 1; /* READ */ |
2468 | |
2469 | BUG_ON(usage_bit >= LOCK_USAGE_STATES); |
2470 | |
2471 | if (!mark_lock(curr, hlock, usage_bit)) |
2472 | return 0; |
2473 | } |
2474 | |
2475 | return 1; |
2476 | } |
2477 | |
2478 | /* |
2479 | * Hardirqs will be enabled: |
2480 | */ |
2481 | void trace_hardirqs_on_caller(unsigned long ip) |
2482 | { |
2483 | struct task_struct *curr = current; |
2484 | |
2485 | time_hardirqs_on(CALLER_ADDR0, ip); |
2486 | |
2487 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2488 | return; |
2489 | |
2490 | if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) |
2491 | return; |
2492 | |
2493 | if (unlikely(curr->hardirqs_enabled)) { |
2494 | /* |
2495 | * Neither irq nor preemption are disabled here |
2496 | * so this is racy by nature but losing one hit |
2497 | * in a stat is not a big deal. |
2498 | */ |
2499 | __debug_atomic_inc(redundant_hardirqs_on); |
2500 | return; |
2501 | } |
2502 | /* we'll do an OFF -> ON transition: */ |
2503 | curr->hardirqs_enabled = 1; |
2504 | |
2505 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2506 | return; |
2507 | if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) |
2508 | return; |
2509 | /* |
2510 | * We are going to turn hardirqs on, so set the |
2511 | * usage bit for all held locks: |
2512 | */ |
2513 | if (!mark_held_locks(curr, HARDIRQ)) |
2514 | return; |
2515 | /* |
2516 | * If we have softirqs enabled, then set the usage |
2517 | * bit for all held locks. (disabled hardirqs prevented |
2518 | * this bit from being set before) |
2519 | */ |
2520 | if (curr->softirqs_enabled) |
2521 | if (!mark_held_locks(curr, SOFTIRQ)) |
2522 | return; |
2523 | |
2524 | curr->hardirq_enable_ip = ip; |
2525 | curr->hardirq_enable_event = ++curr->irq_events; |
2526 | debug_atomic_inc(hardirqs_on_events); |
2527 | } |
2528 | EXPORT_SYMBOL(trace_hardirqs_on_caller); |
2529 | |
2530 | void trace_hardirqs_on(void) |
2531 | { |
2532 | trace_hardirqs_on_caller(CALLER_ADDR0); |
2533 | } |
2534 | EXPORT_SYMBOL(trace_hardirqs_on); |
2535 | |
2536 | /* |
2537 | * Hardirqs were disabled: |
2538 | */ |
2539 | void trace_hardirqs_off_caller(unsigned long ip) |
2540 | { |
2541 | struct task_struct *curr = current; |
2542 | |
2543 | time_hardirqs_off(CALLER_ADDR0, ip); |
2544 | |
2545 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2546 | return; |
2547 | |
2548 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2549 | return; |
2550 | |
2551 | if (curr->hardirqs_enabled) { |
2552 | /* |
2553 | * We have done an ON -> OFF transition: |
2554 | */ |
2555 | curr->hardirqs_enabled = 0; |
2556 | curr->hardirq_disable_ip = ip; |
2557 | curr->hardirq_disable_event = ++curr->irq_events; |
2558 | debug_atomic_inc(hardirqs_off_events); |
2559 | } else |
2560 | debug_atomic_inc(redundant_hardirqs_off); |
2561 | } |
2562 | EXPORT_SYMBOL(trace_hardirqs_off_caller); |
2563 | |
2564 | void trace_hardirqs_off(void) |
2565 | { |
2566 | trace_hardirqs_off_caller(CALLER_ADDR0); |
2567 | } |
2568 | EXPORT_SYMBOL(trace_hardirqs_off); |
2569 | |
2570 | /* |
2571 | * Softirqs will be enabled: |
2572 | */ |
2573 | void trace_softirqs_on(unsigned long ip) |
2574 | { |
2575 | struct task_struct *curr = current; |
2576 | |
2577 | if (unlikely(!debug_locks)) |
2578 | return; |
2579 | |
2580 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2581 | return; |
2582 | |
2583 | if (curr->softirqs_enabled) { |
2584 | debug_atomic_inc(redundant_softirqs_on); |
2585 | return; |
2586 | } |
2587 | |
2588 | /* |
2589 | * We'll do an OFF -> ON transition: |
2590 | */ |
2591 | curr->softirqs_enabled = 1; |
2592 | curr->softirq_enable_ip = ip; |
2593 | curr->softirq_enable_event = ++curr->irq_events; |
2594 | debug_atomic_inc(softirqs_on_events); |
2595 | /* |
2596 | * We are going to turn softirqs on, so set the |
2597 | * usage bit for all held locks, if hardirqs are |
2598 | * enabled too: |
2599 | */ |
2600 | if (curr->hardirqs_enabled) |
2601 | mark_held_locks(curr, SOFTIRQ); |
2602 | } |
2603 | |
2604 | /* |
2605 | * Softirqs were disabled: |
2606 | */ |
2607 | void trace_softirqs_off(unsigned long ip) |
2608 | { |
2609 | struct task_struct *curr = current; |
2610 | |
2611 | if (unlikely(!debug_locks)) |
2612 | return; |
2613 | |
2614 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2615 | return; |
2616 | |
2617 | if (curr->softirqs_enabled) { |
2618 | /* |
2619 | * We have done an ON -> OFF transition: |
2620 | */ |
2621 | curr->softirqs_enabled = 0; |
2622 | curr->softirq_disable_ip = ip; |
2623 | curr->softirq_disable_event = ++curr->irq_events; |
2624 | debug_atomic_inc(softirqs_off_events); |
2625 | DEBUG_LOCKS_WARN_ON(!softirq_count()); |
2626 | } else |
2627 | debug_atomic_inc(redundant_softirqs_off); |
2628 | } |
2629 | |
2630 | static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags) |
2631 | { |
2632 | struct task_struct *curr = current; |
2633 | |
2634 | if (unlikely(!debug_locks)) |
2635 | return; |
2636 | |
2637 | /* no reclaim without waiting on it */ |
2638 | if (!(gfp_mask & __GFP_WAIT)) |
2639 | return; |
2640 | |
2641 | /* this guy won't enter reclaim */ |
2642 | if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC)) |
2643 | return; |
2644 | |
2645 | /* We're only interested __GFP_FS allocations for now */ |
2646 | if (!(gfp_mask & __GFP_FS)) |
2647 | return; |
2648 | |
2649 | if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))) |
2650 | return; |
2651 | |
2652 | mark_held_locks(curr, RECLAIM_FS); |
2653 | } |
2654 | |
2655 | static void check_flags(unsigned long flags); |
2656 | |
2657 | void lockdep_trace_alloc(gfp_t gfp_mask) |
2658 | { |
2659 | unsigned long flags; |
2660 | |
2661 | if (unlikely(current->lockdep_recursion)) |
2662 | return; |
2663 | |
2664 | raw_local_irq_save(flags); |
2665 | check_flags(flags); |
2666 | current->lockdep_recursion = 1; |
2667 | __lockdep_trace_alloc(gfp_mask, flags); |
2668 | current->lockdep_recursion = 0; |
2669 | raw_local_irq_restore(flags); |
2670 | } |
2671 | |
2672 | static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) |
2673 | { |
2674 | /* |
2675 | * If non-trylock use in a hardirq or softirq context, then |
2676 | * mark the lock as used in these contexts: |
2677 | */ |
2678 | if (!hlock->trylock) { |
2679 | if (hlock->read) { |
2680 | if (curr->hardirq_context) |
2681 | if (!mark_lock(curr, hlock, |
2682 | LOCK_USED_IN_HARDIRQ_READ)) |
2683 | return 0; |
2684 | if (curr->softirq_context) |
2685 | if (!mark_lock(curr, hlock, |
2686 | LOCK_USED_IN_SOFTIRQ_READ)) |
2687 | return 0; |
2688 | } else { |
2689 | if (curr->hardirq_context) |
2690 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) |
2691 | return 0; |
2692 | if (curr->softirq_context) |
2693 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) |
2694 | return 0; |
2695 | } |
2696 | } |
2697 | if (!hlock->hardirqs_off) { |
2698 | if (hlock->read) { |
2699 | if (!mark_lock(curr, hlock, |
2700 | LOCK_ENABLED_HARDIRQ_READ)) |
2701 | return 0; |
2702 | if (curr->softirqs_enabled) |
2703 | if (!mark_lock(curr, hlock, |
2704 | LOCK_ENABLED_SOFTIRQ_READ)) |
2705 | return 0; |
2706 | } else { |
2707 | if (!mark_lock(curr, hlock, |
2708 | LOCK_ENABLED_HARDIRQ)) |
2709 | return 0; |
2710 | if (curr->softirqs_enabled) |
2711 | if (!mark_lock(curr, hlock, |
2712 | LOCK_ENABLED_SOFTIRQ)) |
2713 | return 0; |
2714 | } |
2715 | } |
2716 | |
2717 | /* |
2718 | * We reuse the irq context infrastructure more broadly as a general |
2719 | * context checking code. This tests GFP_FS recursion (a lock taken |
2720 | * during reclaim for a GFP_FS allocation is held over a GFP_FS |
2721 | * allocation). |
2722 | */ |
2723 | if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) { |
2724 | if (hlock->read) { |
2725 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ)) |
2726 | return 0; |
2727 | } else { |
2728 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS)) |
2729 | return 0; |
2730 | } |
2731 | } |
2732 | |
2733 | return 1; |
2734 | } |
2735 | |
2736 | static int separate_irq_context(struct task_struct *curr, |
2737 | struct held_lock *hlock) |
2738 | { |
2739 | unsigned int depth = curr->lockdep_depth; |
2740 | |
2741 | /* |
2742 | * Keep track of points where we cross into an interrupt context: |
2743 | */ |
2744 | hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) + |
2745 | curr->softirq_context; |
2746 | if (depth) { |
2747 | struct held_lock *prev_hlock; |
2748 | |
2749 | prev_hlock = curr->held_locks + depth-1; |
2750 | /* |
2751 | * If we cross into another context, reset the |
2752 | * hash key (this also prevents the checking and the |
2753 | * adding of the dependency to 'prev'): |
2754 | */ |
2755 | if (prev_hlock->irq_context != hlock->irq_context) |
2756 | return 1; |
2757 | } |
2758 | return 0; |
2759 | } |
2760 | |
2761 | #else |
2762 | |
2763 | static inline |
2764 | int mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
2765 | enum lock_usage_bit new_bit) |
2766 | { |
2767 | WARN_ON(1); |
2768 | return 1; |
2769 | } |
2770 | |
2771 | static inline int mark_irqflags(struct task_struct *curr, |
2772 | struct held_lock *hlock) |
2773 | { |
2774 | return 1; |
2775 | } |
2776 | |
2777 | static inline int separate_irq_context(struct task_struct *curr, |
2778 | struct held_lock *hlock) |
2779 | { |
2780 | return 0; |
2781 | } |
2782 | |
2783 | void lockdep_trace_alloc(gfp_t gfp_mask) |
2784 | { |
2785 | } |
2786 | |
2787 | #endif |
2788 | |
2789 | /* |
2790 | * Mark a lock with a usage bit, and validate the state transition: |
2791 | */ |
2792 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
2793 | enum lock_usage_bit new_bit) |
2794 | { |
2795 | unsigned int new_mask = 1 << new_bit, ret = 1; |
2796 | |
2797 | /* |
2798 | * If already set then do not dirty the cacheline, |
2799 | * nor do any checks: |
2800 | */ |
2801 | if (likely(hlock_class(this)->usage_mask & new_mask)) |
2802 | return 1; |
2803 | |
2804 | if (!graph_lock()) |
2805 | return 0; |
2806 | /* |
2807 | * Make sure we didn't race: |
2808 | */ |
2809 | if (unlikely(hlock_class(this)->usage_mask & new_mask)) { |
2810 | graph_unlock(); |
2811 | return 1; |
2812 | } |
2813 | |
2814 | hlock_class(this)->usage_mask |= new_mask; |
2815 | |
2816 | if (!save_trace(hlock_class(this)->usage_traces + new_bit)) |
2817 | return 0; |
2818 | |
2819 | switch (new_bit) { |
2820 | #define LOCKDEP_STATE(__STATE) \ |
2821 | case LOCK_USED_IN_##__STATE: \ |
2822 | case LOCK_USED_IN_##__STATE##_READ: \ |
2823 | case LOCK_ENABLED_##__STATE: \ |
2824 | case LOCK_ENABLED_##__STATE##_READ: |
2825 | #include "lockdep_states.h" |
2826 | #undef LOCKDEP_STATE |
2827 | ret = mark_lock_irq(curr, this, new_bit); |
2828 | if (!ret) |
2829 | return 0; |
2830 | break; |
2831 | case LOCK_USED: |
2832 | debug_atomic_dec(nr_unused_locks); |
2833 | break; |
2834 | default: |
2835 | if (!debug_locks_off_graph_unlock()) |
2836 | return 0; |
2837 | WARN_ON(1); |
2838 | return 0; |
2839 | } |
2840 | |
2841 | graph_unlock(); |
2842 | |
2843 | /* |
2844 | * We must printk outside of the graph_lock: |
2845 | */ |
2846 | if (ret == 2) { |
2847 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); |
2848 | print_lock(this); |
2849 | print_irqtrace_events(curr); |
2850 | dump_stack(); |
2851 | } |
2852 | |
2853 | return ret; |
2854 | } |
2855 | |
2856 | /* |
2857 | * Initialize a lock instance's lock-class mapping info: |
2858 | */ |
2859 | void lockdep_init_map(struct lockdep_map *lock, const char *name, |
2860 | struct lock_class_key *key, int subclass) |
2861 | { |
2862 | int i; |
2863 | |
2864 | for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) |
2865 | lock->class_cache[i] = NULL; |
2866 | |
2867 | #ifdef CONFIG_LOCK_STAT |
2868 | lock->cpu = raw_smp_processor_id(); |
2869 | #endif |
2870 | |
2871 | if (DEBUG_LOCKS_WARN_ON(!name)) { |
2872 | lock->name = "NULL"; |
2873 | return; |
2874 | } |
2875 | |
2876 | lock->name = name; |
2877 | |
2878 | if (DEBUG_LOCKS_WARN_ON(!key)) |
2879 | return; |
2880 | /* |
2881 | * Sanity check, the lock-class key must be persistent: |
2882 | */ |
2883 | if (!static_obj(key)) { |
2884 | printk("BUG: key %p not in .data!\n", key); |
2885 | DEBUG_LOCKS_WARN_ON(1); |
2886 | return; |
2887 | } |
2888 | lock->key = key; |
2889 | |
2890 | if (unlikely(!debug_locks)) |
2891 | return; |
2892 | |
2893 | if (subclass) |
2894 | register_lock_class(lock, subclass, 1); |
2895 | } |
2896 | EXPORT_SYMBOL_GPL(lockdep_init_map); |
2897 | |
2898 | struct lock_class_key __lockdep_no_validate__; |
2899 | |
2900 | /* |
2901 | * This gets called for every mutex_lock*()/spin_lock*() operation. |
2902 | * We maintain the dependency maps and validate the locking attempt: |
2903 | */ |
2904 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
2905 | int trylock, int read, int check, int hardirqs_off, |
2906 | struct lockdep_map *nest_lock, unsigned long ip, |
2907 | int references) |
2908 | { |
2909 | struct task_struct *curr = current; |
2910 | struct lock_class *class = NULL; |
2911 | struct held_lock *hlock; |
2912 | unsigned int depth, id; |
2913 | int chain_head = 0; |
2914 | int class_idx; |
2915 | u64 chain_key; |
2916 | |
2917 | if (!prove_locking) |
2918 | check = 1; |
2919 | |
2920 | if (unlikely(!debug_locks)) |
2921 | return 0; |
2922 | |
2923 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2924 | return 0; |
2925 | |
2926 | if (lock->key == &__lockdep_no_validate__) |
2927 | check = 1; |
2928 | |
2929 | if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
2930 | class = lock->class_cache[subclass]; |
2931 | /* |
2932 | * Not cached? |
2933 | */ |
2934 | if (unlikely(!class)) { |
2935 | class = register_lock_class(lock, subclass, 0); |
2936 | if (!class) |
2937 | return 0; |
2938 | } |
2939 | atomic_inc((atomic_t *)&class->ops); |
2940 | if (very_verbose(class)) { |
2941 | printk("\nacquire class [%p] %s", class->key, class->name); |
2942 | if (class->name_version > 1) |
2943 | printk("#%d", class->name_version); |
2944 | printk("\n"); |
2945 | dump_stack(); |
2946 | } |
2947 | |
2948 | /* |
2949 | * Add the lock to the list of currently held locks. |
2950 | * (we dont increase the depth just yet, up until the |
2951 | * dependency checks are done) |
2952 | */ |
2953 | depth = curr->lockdep_depth; |
2954 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) |
2955 | return 0; |
2956 | |
2957 | class_idx = class - lock_classes + 1; |
2958 | |
2959 | if (depth) { |
2960 | hlock = curr->held_locks + depth - 1; |
2961 | if (hlock->class_idx == class_idx && nest_lock) { |
2962 | if (hlock->references) |
2963 | hlock->references++; |
2964 | else |
2965 | hlock->references = 2; |
2966 | |
2967 | return 1; |
2968 | } |
2969 | } |
2970 | |
2971 | hlock = curr->held_locks + depth; |
2972 | if (DEBUG_LOCKS_WARN_ON(!class)) |
2973 | return 0; |
2974 | hlock->class_idx = class_idx; |
2975 | hlock->acquire_ip = ip; |
2976 | hlock->instance = lock; |
2977 | hlock->nest_lock = nest_lock; |
2978 | hlock->trylock = trylock; |
2979 | hlock->read = read; |
2980 | hlock->check = check; |
2981 | hlock->hardirqs_off = !!hardirqs_off; |
2982 | hlock->references = references; |
2983 | #ifdef CONFIG_LOCK_STAT |
2984 | hlock->waittime_stamp = 0; |
2985 | hlock->holdtime_stamp = lockstat_clock(); |
2986 | #endif |
2987 | |
2988 | if (check == 2 && !mark_irqflags(curr, hlock)) |
2989 | return 0; |
2990 | |
2991 | /* mark it as used: */ |
2992 | if (!mark_lock(curr, hlock, LOCK_USED)) |
2993 | return 0; |
2994 | |
2995 | /* |
2996 | * Calculate the chain hash: it's the combined hash of all the |
2997 | * lock keys along the dependency chain. We save the hash value |
2998 | * at every step so that we can get the current hash easily |
2999 | * after unlock. The chain hash is then used to cache dependency |
3000 | * results. |
3001 | * |
3002 | * The 'key ID' is what is the most compact key value to drive |
3003 | * the hash, not class->key. |
3004 | */ |
3005 | id = class - lock_classes; |
3006 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) |
3007 | return 0; |
3008 | |
3009 | chain_key = curr->curr_chain_key; |
3010 | if (!depth) { |
3011 | if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) |
3012 | return 0; |
3013 | chain_head = 1; |
3014 | } |
3015 | |
3016 | hlock->prev_chain_key = chain_key; |
3017 | if (separate_irq_context(curr, hlock)) { |
3018 | chain_key = 0; |
3019 | chain_head = 1; |
3020 | } |
3021 | chain_key = iterate_chain_key(chain_key, id); |
3022 | |
3023 | if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) |
3024 | return 0; |
3025 | |
3026 | curr->curr_chain_key = chain_key; |
3027 | curr->lockdep_depth++; |
3028 | check_chain_key(curr); |
3029 | #ifdef CONFIG_DEBUG_LOCKDEP |
3030 | if (unlikely(!debug_locks)) |
3031 | return 0; |
3032 | #endif |
3033 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { |
3034 | debug_locks_off(); |
3035 | printk("BUG: MAX_LOCK_DEPTH too low!\n"); |
3036 | printk("turning off the locking correctness validator.\n"); |
3037 | dump_stack(); |
3038 | return 0; |
3039 | } |
3040 | |
3041 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) |
3042 | max_lockdep_depth = curr->lockdep_depth; |
3043 | |
3044 | return 1; |
3045 | } |
3046 | |
3047 | static int |
3048 | print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock, |
3049 | unsigned long ip) |
3050 | { |
3051 | if (!debug_locks_off()) |
3052 | return 0; |
3053 | if (debug_locks_silent) |
3054 | return 0; |
3055 | |
3056 | printk("\n=====================================\n"); |
3057 | printk( "[ BUG: bad unlock balance detected! ]\n"); |
3058 | printk( "-------------------------------------\n"); |
3059 | printk("%s/%d is trying to release lock (", |
3060 | curr->comm, task_pid_nr(curr)); |
3061 | print_lockdep_cache(lock); |
3062 | printk(") at:\n"); |
3063 | print_ip_sym(ip); |
3064 | printk("but there are no more locks to release!\n"); |
3065 | printk("\nother info that might help us debug this:\n"); |
3066 | lockdep_print_held_locks(curr); |
3067 | |
3068 | printk("\nstack backtrace:\n"); |
3069 | dump_stack(); |
3070 | |
3071 | return 0; |
3072 | } |
3073 | |
3074 | /* |
3075 | * Common debugging checks for both nested and non-nested unlock: |
3076 | */ |
3077 | static int check_unlock(struct task_struct *curr, struct lockdep_map *lock, |
3078 | unsigned long ip) |
3079 | { |
3080 | if (unlikely(!debug_locks)) |
3081 | return 0; |
3082 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
3083 | return 0; |
3084 | |
3085 | if (curr->lockdep_depth <= 0) |
3086 | return print_unlock_inbalance_bug(curr, lock, ip); |
3087 | |
3088 | return 1; |
3089 | } |
3090 | |
3091 | static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) |
3092 | { |
3093 | if (hlock->instance == lock) |
3094 | return 1; |
3095 | |
3096 | if (hlock->references) { |
3097 | struct lock_class *class = lock->class_cache[0]; |
3098 | |
3099 | if (!class) |
3100 | class = look_up_lock_class(lock, 0); |
3101 | |
3102 | if (DEBUG_LOCKS_WARN_ON(!class)) |
3103 | return 0; |
3104 | |
3105 | if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) |
3106 | return 0; |
3107 | |
3108 | if (hlock->class_idx == class - lock_classes + 1) |
3109 | return 1; |
3110 | } |
3111 | |
3112 | return 0; |
3113 | } |
3114 | |
3115 | static int |
3116 | __lock_set_class(struct lockdep_map *lock, const char *name, |
3117 | struct lock_class_key *key, unsigned int subclass, |
3118 | unsigned long ip) |
3119 | { |
3120 | struct task_struct *curr = current; |
3121 | struct held_lock *hlock, *prev_hlock; |
3122 | struct lock_class *class; |
3123 | unsigned int depth; |
3124 | int i; |
3125 | |
3126 | depth = curr->lockdep_depth; |
3127 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3128 | return 0; |
3129 | |
3130 | prev_hlock = NULL; |
3131 | for (i = depth-1; i >= 0; i--) { |
3132 | hlock = curr->held_locks + i; |
3133 | /* |
3134 | * We must not cross into another context: |
3135 | */ |
3136 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3137 | break; |
3138 | if (match_held_lock(hlock, lock)) |
3139 | goto found_it; |
3140 | prev_hlock = hlock; |
3141 | } |
3142 | return print_unlock_inbalance_bug(curr, lock, ip); |
3143 | |
3144 | found_it: |
3145 | lockdep_init_map(lock, name, key, 0); |
3146 | class = register_lock_class(lock, subclass, 0); |
3147 | hlock->class_idx = class - lock_classes + 1; |
3148 | |
3149 | curr->lockdep_depth = i; |
3150 | curr->curr_chain_key = hlock->prev_chain_key; |
3151 | |
3152 | for (; i < depth; i++) { |
3153 | hlock = curr->held_locks + i; |
3154 | if (!__lock_acquire(hlock->instance, |
3155 | hlock_class(hlock)->subclass, hlock->trylock, |
3156 | hlock->read, hlock->check, hlock->hardirqs_off, |
3157 | hlock->nest_lock, hlock->acquire_ip, |
3158 | hlock->references)) |
3159 | return 0; |
3160 | } |
3161 | |
3162 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) |
3163 | return 0; |
3164 | return 1; |
3165 | } |
3166 | |
3167 | /* |
3168 | * Remove the lock to the list of currently held locks in a |
3169 | * potentially non-nested (out of order) manner. This is a |
3170 | * relatively rare operation, as all the unlock APIs default |
3171 | * to nested mode (which uses lock_release()): |
3172 | */ |
3173 | static int |
3174 | lock_release_non_nested(struct task_struct *curr, |
3175 | struct lockdep_map *lock, unsigned long ip) |
3176 | { |
3177 | struct held_lock *hlock, *prev_hlock; |
3178 | unsigned int depth; |
3179 | int i; |
3180 | |
3181 | /* |
3182 | * Check whether the lock exists in the current stack |
3183 | * of held locks: |
3184 | */ |
3185 | depth = curr->lockdep_depth; |
3186 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3187 | return 0; |
3188 | |
3189 | prev_hlock = NULL; |
3190 | for (i = depth-1; i >= 0; i--) { |
3191 | hlock = curr->held_locks + i; |
3192 | /* |
3193 | * We must not cross into another context: |
3194 | */ |
3195 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3196 | break; |
3197 | if (match_held_lock(hlock, lock)) |
3198 | goto found_it; |
3199 | prev_hlock = hlock; |
3200 | } |
3201 | return print_unlock_inbalance_bug(curr, lock, ip); |
3202 | |
3203 | found_it: |
3204 | if (hlock->instance == lock) |
3205 | lock_release_holdtime(hlock); |
3206 | |
3207 | if (hlock->references) { |
3208 | hlock->references--; |
3209 | if (hlock->references) { |
3210 | /* |
3211 | * We had, and after removing one, still have |
3212 | * references, the current lock stack is still |
3213 | * valid. We're done! |
3214 | */ |
3215 | return 1; |
3216 | } |
3217 | } |
3218 | |
3219 | /* |
3220 | * We have the right lock to unlock, 'hlock' points to it. |
3221 | * Now we remove it from the stack, and add back the other |
3222 | * entries (if any), recalculating the hash along the way: |
3223 | */ |
3224 | |
3225 | curr->lockdep_depth = i; |
3226 | curr->curr_chain_key = hlock->prev_chain_key; |
3227 | |
3228 | for (i++; i < depth; i++) { |
3229 | hlock = curr->held_locks + i; |
3230 | if (!__lock_acquire(hlock->instance, |
3231 | hlock_class(hlock)->subclass, hlock->trylock, |
3232 | hlock->read, hlock->check, hlock->hardirqs_off, |
3233 | hlock->nest_lock, hlock->acquire_ip, |
3234 | hlock->references)) |
3235 | return 0; |
3236 | } |
3237 | |
3238 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) |
3239 | return 0; |
3240 | return 1; |
3241 | } |
3242 | |
3243 | /* |
3244 | * Remove the lock to the list of currently held locks - this gets |
3245 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
3246 | * mutex_lock_interruptible()). This is done for unlocks that nest |
3247 | * perfectly. (i.e. the current top of the lock-stack is unlocked) |
3248 | */ |
3249 | static int lock_release_nested(struct task_struct *curr, |
3250 | struct lockdep_map *lock, unsigned long ip) |
3251 | { |
3252 | struct held_lock *hlock; |
3253 | unsigned int depth; |
3254 | |
3255 | /* |
3256 | * Pop off the top of the lock stack: |
3257 | */ |
3258 | depth = curr->lockdep_depth - 1; |
3259 | hlock = curr->held_locks + depth; |
3260 | |
3261 | /* |
3262 | * Is the unlock non-nested: |
3263 | */ |
3264 | if (hlock->instance != lock || hlock->references) |
3265 | return lock_release_non_nested(curr, lock, ip); |
3266 | curr->lockdep_depth--; |
3267 | |
3268 | if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0))) |
3269 | return 0; |
3270 | |
3271 | curr->curr_chain_key = hlock->prev_chain_key; |
3272 | |
3273 | lock_release_holdtime(hlock); |
3274 | |
3275 | #ifdef CONFIG_DEBUG_LOCKDEP |
3276 | hlock->prev_chain_key = 0; |
3277 | hlock->class_idx = 0; |
3278 | hlock->acquire_ip = 0; |
3279 | hlock->irq_context = 0; |
3280 | #endif |
3281 | return 1; |
3282 | } |
3283 | |
3284 | /* |
3285 | * Remove the lock to the list of currently held locks - this gets |
3286 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
3287 | * mutex_lock_interruptible()). This is done for unlocks that nest |
3288 | * perfectly. (i.e. the current top of the lock-stack is unlocked) |
3289 | */ |
3290 | static void |
3291 | __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) |
3292 | { |
3293 | struct task_struct *curr = current; |
3294 | |
3295 | if (!check_unlock(curr, lock, ip)) |
3296 | return; |
3297 | |
3298 | if (nested) { |
3299 | if (!lock_release_nested(curr, lock, ip)) |
3300 | return; |
3301 | } else { |
3302 | if (!lock_release_non_nested(curr, lock, ip)) |
3303 | return; |
3304 | } |
3305 | |
3306 | check_chain_key(curr); |
3307 | } |
3308 | |
3309 | static int __lock_is_held(struct lockdep_map *lock) |
3310 | { |
3311 | struct task_struct *curr = current; |
3312 | int i; |
3313 | |
3314 | for (i = 0; i < curr->lockdep_depth; i++) { |
3315 | struct held_lock *hlock = curr->held_locks + i; |
3316 | |
3317 | if (match_held_lock(hlock, lock)) |
3318 | return 1; |
3319 | } |
3320 | |
3321 | return 0; |
3322 | } |
3323 | |
3324 | /* |
3325 | * Check whether we follow the irq-flags state precisely: |
3326 | */ |
3327 | static void check_flags(unsigned long flags) |
3328 | { |
3329 | #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \ |
3330 | defined(CONFIG_TRACE_IRQFLAGS) |
3331 | if (!debug_locks) |
3332 | return; |
3333 | |
3334 | if (irqs_disabled_flags(flags)) { |
3335 | if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { |
3336 | printk("possible reason: unannotated irqs-off.\n"); |
3337 | } |
3338 | } else { |
3339 | if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { |
3340 | printk("possible reason: unannotated irqs-on.\n"); |
3341 | } |
3342 | } |
3343 | |
3344 | /* |
3345 | * We dont accurately track softirq state in e.g. |
3346 | * hardirq contexts (such as on 4KSTACKS), so only |
3347 | * check if not in hardirq contexts: |
3348 | */ |
3349 | if (!hardirq_count()) { |
3350 | if (softirq_count()) |
3351 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); |
3352 | else |
3353 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); |
3354 | } |
3355 | |
3356 | if (!debug_locks) |
3357 | print_irqtrace_events(current); |
3358 | #endif |
3359 | } |
3360 | |
3361 | void lock_set_class(struct lockdep_map *lock, const char *name, |
3362 | struct lock_class_key *key, unsigned int subclass, |
3363 | unsigned long ip) |
3364 | { |
3365 | unsigned long flags; |
3366 | |
3367 | if (unlikely(current->lockdep_recursion)) |
3368 | return; |
3369 | |
3370 | raw_local_irq_save(flags); |
3371 | current->lockdep_recursion = 1; |
3372 | check_flags(flags); |
3373 | if (__lock_set_class(lock, name, key, subclass, ip)) |
3374 | check_chain_key(current); |
3375 | current->lockdep_recursion = 0; |
3376 | raw_local_irq_restore(flags); |
3377 | } |
3378 | EXPORT_SYMBOL_GPL(lock_set_class); |
3379 | |
3380 | /* |
3381 | * We are not always called with irqs disabled - do that here, |
3382 | * and also avoid lockdep recursion: |
3383 | */ |
3384 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
3385 | int trylock, int read, int check, |
3386 | struct lockdep_map *nest_lock, unsigned long ip) |
3387 | { |
3388 | unsigned long flags; |
3389 | |
3390 | if (unlikely(current->lockdep_recursion)) |
3391 | return; |
3392 | |
3393 | raw_local_irq_save(flags); |
3394 | check_flags(flags); |
3395 | |
3396 | current->lockdep_recursion = 1; |
3397 | trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); |
3398 | __lock_acquire(lock, subclass, trylock, read, check, |
3399 | irqs_disabled_flags(flags), nest_lock, ip, 0); |
3400 | current->lockdep_recursion = 0; |
3401 | raw_local_irq_restore(flags); |
3402 | } |
3403 | EXPORT_SYMBOL_GPL(lock_acquire); |
3404 | |
3405 | void lock_release(struct lockdep_map *lock, int nested, |
3406 | unsigned long ip) |
3407 | { |
3408 | unsigned long flags; |
3409 | |
3410 | if (unlikely(current->lockdep_recursion)) |
3411 | return; |
3412 | |
3413 | raw_local_irq_save(flags); |
3414 | check_flags(flags); |
3415 | current->lockdep_recursion = 1; |
3416 | trace_lock_release(lock, ip); |
3417 | __lock_release(lock, nested, ip); |
3418 | current->lockdep_recursion = 0; |
3419 | raw_local_irq_restore(flags); |
3420 | } |
3421 | EXPORT_SYMBOL_GPL(lock_release); |
3422 | |
3423 | int lock_is_held(struct lockdep_map *lock) |
3424 | { |
3425 | unsigned long flags; |
3426 | int ret = 0; |
3427 | |
3428 | if (unlikely(current->lockdep_recursion)) |
3429 | return 1; /* avoid false negative lockdep_assert_held() */ |
3430 | |
3431 | raw_local_irq_save(flags); |
3432 | check_flags(flags); |
3433 | |
3434 | current->lockdep_recursion = 1; |
3435 | ret = __lock_is_held(lock); |
3436 | current->lockdep_recursion = 0; |
3437 | raw_local_irq_restore(flags); |
3438 | |
3439 | return ret; |
3440 | } |
3441 | EXPORT_SYMBOL_GPL(lock_is_held); |
3442 | |
3443 | void lockdep_set_current_reclaim_state(gfp_t gfp_mask) |
3444 | { |
3445 | current->lockdep_reclaim_gfp = gfp_mask; |
3446 | } |
3447 | |
3448 | void lockdep_clear_current_reclaim_state(void) |
3449 | { |
3450 | current->lockdep_reclaim_gfp = 0; |
3451 | } |
3452 | |
3453 | #ifdef CONFIG_LOCK_STAT |
3454 | static int |
3455 | print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, |
3456 | unsigned long ip) |
3457 | { |
3458 | if (!debug_locks_off()) |
3459 | return 0; |
3460 | if (debug_locks_silent) |
3461 | return 0; |
3462 | |
3463 | printk("\n=================================\n"); |
3464 | printk( "[ BUG: bad contention detected! ]\n"); |
3465 | printk( "---------------------------------\n"); |
3466 | printk("%s/%d is trying to contend lock (", |
3467 | curr->comm, task_pid_nr(curr)); |
3468 | print_lockdep_cache(lock); |
3469 | printk(") at:\n"); |
3470 | print_ip_sym(ip); |
3471 | printk("but there are no locks held!\n"); |
3472 | printk("\nother info that might help us debug this:\n"); |
3473 | lockdep_print_held_locks(curr); |
3474 | |
3475 | printk("\nstack backtrace:\n"); |
3476 | dump_stack(); |
3477 | |
3478 | return 0; |
3479 | } |
3480 | |
3481 | static void |
3482 | __lock_contended(struct lockdep_map *lock, unsigned long ip) |
3483 | { |
3484 | struct task_struct *curr = current; |
3485 | struct held_lock *hlock, *prev_hlock; |
3486 | struct lock_class_stats *stats; |
3487 | unsigned int depth; |
3488 | int i, contention_point, contending_point; |
3489 | |
3490 | depth = curr->lockdep_depth; |
3491 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3492 | return; |
3493 | |
3494 | prev_hlock = NULL; |
3495 | for (i = depth-1; i >= 0; i--) { |
3496 | hlock = curr->held_locks + i; |
3497 | /* |
3498 | * We must not cross into another context: |
3499 | */ |
3500 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3501 | break; |
3502 | if (match_held_lock(hlock, lock)) |
3503 | goto found_it; |
3504 | prev_hlock = hlock; |
3505 | } |
3506 | print_lock_contention_bug(curr, lock, ip); |
3507 | return; |
3508 | |
3509 | found_it: |
3510 | if (hlock->instance != lock) |
3511 | return; |
3512 | |
3513 | hlock->waittime_stamp = lockstat_clock(); |
3514 | |
3515 | contention_point = lock_point(hlock_class(hlock)->contention_point, ip); |
3516 | contending_point = lock_point(hlock_class(hlock)->contending_point, |
3517 | lock->ip); |
3518 | |
3519 | stats = get_lock_stats(hlock_class(hlock)); |
3520 | if (contention_point < LOCKSTAT_POINTS) |
3521 | stats->contention_point[contention_point]++; |
3522 | if (contending_point < LOCKSTAT_POINTS) |
3523 | stats->contending_point[contending_point]++; |
3524 | if (lock->cpu != smp_processor_id()) |
3525 | stats->bounces[bounce_contended + !!hlock->read]++; |
3526 | put_lock_stats(stats); |
3527 | } |
3528 | |
3529 | static void |
3530 | __lock_acquired(struct lockdep_map *lock, unsigned long ip) |
3531 | { |
3532 | struct task_struct *curr = current; |
3533 | struct held_lock *hlock, *prev_hlock; |
3534 | struct lock_class_stats *stats; |
3535 | unsigned int depth; |
3536 | u64 now, waittime = 0; |
3537 | int i, cpu; |
3538 | |
3539 | depth = curr->lockdep_depth; |
3540 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3541 | return; |
3542 | |
3543 | prev_hlock = NULL; |
3544 | for (i = depth-1; i >= 0; i--) { |
3545 | hlock = curr->held_locks + i; |
3546 | /* |
3547 | * We must not cross into another context: |
3548 | */ |
3549 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3550 | break; |
3551 | if (match_held_lock(hlock, lock)) |
3552 | goto found_it; |
3553 | prev_hlock = hlock; |
3554 | } |
3555 | print_lock_contention_bug(curr, lock, _RET_IP_); |
3556 | return; |
3557 | |
3558 | found_it: |
3559 | if (hlock->instance != lock) |
3560 | return; |
3561 | |
3562 | cpu = smp_processor_id(); |
3563 | if (hlock->waittime_stamp) { |
3564 | now = lockstat_clock(); |
3565 | waittime = now - hlock->waittime_stamp; |
3566 | hlock->holdtime_stamp = now; |
3567 | } |
3568 | |
3569 | trace_lock_acquired(lock, ip); |
3570 | |
3571 | stats = get_lock_stats(hlock_class(hlock)); |
3572 | if (waittime) { |
3573 | if (hlock->read) |
3574 | lock_time_inc(&stats->read_waittime, waittime); |
3575 | else |
3576 | lock_time_inc(&stats->write_waittime, waittime); |
3577 | } |
3578 | if (lock->cpu != cpu) |
3579 | stats->bounces[bounce_acquired + !!hlock->read]++; |
3580 | put_lock_stats(stats); |
3581 | |
3582 | lock->cpu = cpu; |
3583 | lock->ip = ip; |
3584 | } |
3585 | |
3586 | void lock_contended(struct lockdep_map *lock, unsigned long ip) |
3587 | { |
3588 | unsigned long flags; |
3589 | |
3590 | if (unlikely(!lock_stat)) |
3591 | return; |
3592 | |
3593 | if (unlikely(current->lockdep_recursion)) |
3594 | return; |
3595 | |
3596 | raw_local_irq_save(flags); |
3597 | check_flags(flags); |
3598 | current->lockdep_recursion = 1; |
3599 | trace_lock_contended(lock, ip); |
3600 | __lock_contended(lock, ip); |
3601 | current->lockdep_recursion = 0; |
3602 | raw_local_irq_restore(flags); |
3603 | } |
3604 | EXPORT_SYMBOL_GPL(lock_contended); |
3605 | |
3606 | void lock_acquired(struct lockdep_map *lock, unsigned long ip) |
3607 | { |
3608 | unsigned long flags; |
3609 | |
3610 | if (unlikely(!lock_stat)) |
3611 | return; |
3612 | |
3613 | if (unlikely(current->lockdep_recursion)) |
3614 | return; |
3615 | |
3616 | raw_local_irq_save(flags); |
3617 | check_flags(flags); |
3618 | current->lockdep_recursion = 1; |
3619 | __lock_acquired(lock, ip); |
3620 | current->lockdep_recursion = 0; |
3621 | raw_local_irq_restore(flags); |
3622 | } |
3623 | EXPORT_SYMBOL_GPL(lock_acquired); |
3624 | #endif |
3625 | |
3626 | /* |
3627 | * Used by the testsuite, sanitize the validator state |
3628 | * after a simulated failure: |
3629 | */ |
3630 | |
3631 | void lockdep_reset(void) |
3632 | { |
3633 | unsigned long flags; |
3634 | int i; |
3635 | |
3636 | raw_local_irq_save(flags); |
3637 | current->curr_chain_key = 0; |
3638 | current->lockdep_depth = 0; |
3639 | current->lockdep_recursion = 0; |
3640 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); |
3641 | nr_hardirq_chains = 0; |
3642 | nr_softirq_chains = 0; |
3643 | nr_process_chains = 0; |
3644 | debug_locks = 1; |
3645 | for (i = 0; i < CHAINHASH_SIZE; i++) |
3646 | INIT_LIST_HEAD(chainhash_table + i); |
3647 | raw_local_irq_restore(flags); |
3648 | } |
3649 | |
3650 | static void zap_class(struct lock_class *class) |
3651 | { |
3652 | int i; |
3653 | |
3654 | /* |
3655 | * Remove all dependencies this lock is |
3656 | * involved in: |
3657 | */ |
3658 | for (i = 0; i < nr_list_entries; i++) { |
3659 | if (list_entries[i].class == class) |
3660 | list_del_rcu(&list_entries[i].entry); |
3661 | } |
3662 | /* |
3663 | * Unhash the class and remove it from the all_lock_classes list: |
3664 | */ |
3665 | list_del_rcu(&class->hash_entry); |
3666 | list_del_rcu(&class->lock_entry); |
3667 | |
3668 | class->key = NULL; |
3669 | } |
3670 | |
3671 | static inline int within(const void *addr, void *start, unsigned long size) |
3672 | { |
3673 | return addr >= start && addr < start + size; |
3674 | } |
3675 | |
3676 | void lockdep_free_key_range(void *start, unsigned long size) |
3677 | { |
3678 | struct lock_class *class, *next; |
3679 | struct list_head *head; |
3680 | unsigned long flags; |
3681 | int i; |
3682 | int locked; |
3683 | |
3684 | raw_local_irq_save(flags); |
3685 | locked = graph_lock(); |
3686 | |
3687 | /* |
3688 | * Unhash all classes that were created by this module: |
3689 | */ |
3690 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
3691 | head = classhash_table + i; |
3692 | if (list_empty(head)) |
3693 | continue; |
3694 | list_for_each_entry_safe(class, next, head, hash_entry) { |
3695 | if (within(class->key, start, size)) |
3696 | zap_class(class); |
3697 | else if (within(class->name, start, size)) |
3698 | zap_class(class); |
3699 | } |
3700 | } |
3701 | |
3702 | if (locked) |
3703 | graph_unlock(); |
3704 | raw_local_irq_restore(flags); |
3705 | } |
3706 | |
3707 | void lockdep_reset_lock(struct lockdep_map *lock) |
3708 | { |
3709 | struct lock_class *class, *next; |
3710 | struct list_head *head; |
3711 | unsigned long flags; |
3712 | int i, j; |
3713 | int locked; |
3714 | |
3715 | raw_local_irq_save(flags); |
3716 | |
3717 | /* |
3718 | * Remove all classes this lock might have: |
3719 | */ |
3720 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { |
3721 | /* |
3722 | * If the class exists we look it up and zap it: |
3723 | */ |
3724 | class = look_up_lock_class(lock, j); |
3725 | if (class) |
3726 | zap_class(class); |
3727 | } |
3728 | /* |
3729 | * Debug check: in the end all mapped classes should |
3730 | * be gone. |
3731 | */ |
3732 | locked = graph_lock(); |
3733 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
3734 | head = classhash_table + i; |
3735 | if (list_empty(head)) |
3736 | continue; |
3737 | list_for_each_entry_safe(class, next, head, hash_entry) { |
3738 | int match = 0; |
3739 | |
3740 | for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) |
3741 | match |= class == lock->class_cache[j]; |
3742 | |
3743 | if (unlikely(match)) { |
3744 | if (debug_locks_off_graph_unlock()) |
3745 | WARN_ON(1); |
3746 | goto out_restore; |
3747 | } |
3748 | } |
3749 | } |
3750 | if (locked) |
3751 | graph_unlock(); |
3752 | |
3753 | out_restore: |
3754 | raw_local_irq_restore(flags); |
3755 | } |
3756 | |
3757 | void lockdep_init(void) |
3758 | { |
3759 | int i; |
3760 | |
3761 | /* |
3762 | * Some architectures have their own start_kernel() |
3763 | * code which calls lockdep_init(), while we also |
3764 | * call lockdep_init() from the start_kernel() itself, |
3765 | * and we want to initialize the hashes only once: |
3766 | */ |
3767 | if (lockdep_initialized) |
3768 | return; |
3769 | |
3770 | for (i = 0; i < CLASSHASH_SIZE; i++) |
3771 | INIT_LIST_HEAD(classhash_table + i); |
3772 | |
3773 | for (i = 0; i < CHAINHASH_SIZE; i++) |
3774 | INIT_LIST_HEAD(chainhash_table + i); |
3775 | |
3776 | lockdep_initialized = 1; |
3777 | } |
3778 | |
3779 | void __init lockdep_info(void) |
3780 | { |
3781 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); |
3782 | |
3783 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); |
3784 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); |
3785 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); |
3786 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); |
3787 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); |
3788 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); |
3789 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); |
3790 | |
3791 | printk(" memory used by lock dependency info: %lu kB\n", |
3792 | (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + |
3793 | sizeof(struct list_head) * CLASSHASH_SIZE + |
3794 | sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + |
3795 | sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + |
3796 | sizeof(struct list_head) * CHAINHASH_SIZE |
3797 | #ifdef CONFIG_PROVE_LOCKING |
3798 | + sizeof(struct circular_queue) |
3799 | #endif |
3800 | ) / 1024 |
3801 | ); |
3802 | |
3803 | printk(" per task-struct memory footprint: %lu bytes\n", |
3804 | sizeof(struct held_lock) * MAX_LOCK_DEPTH); |
3805 | |
3806 | #ifdef CONFIG_DEBUG_LOCKDEP |
3807 | if (lockdep_init_error) { |
3808 | printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n"); |
3809 | printk("Call stack leading to lockdep invocation was:\n"); |
3810 | print_stack_trace(&lockdep_init_trace, 0); |
3811 | } |
3812 | #endif |
3813 | } |
3814 | |
3815 | static void |
3816 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, |
3817 | const void *mem_to, struct held_lock *hlock) |
3818 | { |
3819 | if (!debug_locks_off()) |
3820 | return; |
3821 | if (debug_locks_silent) |
3822 | return; |
3823 | |
3824 | printk("\n=========================\n"); |
3825 | printk( "[ BUG: held lock freed! ]\n"); |
3826 | printk( "-------------------------\n"); |
3827 | printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", |
3828 | curr->comm, task_pid_nr(curr), mem_from, mem_to-1); |
3829 | print_lock(hlock); |
3830 | lockdep_print_held_locks(curr); |
3831 | |
3832 | printk("\nstack backtrace:\n"); |
3833 | dump_stack(); |
3834 | } |
3835 | |
3836 | static inline int not_in_range(const void* mem_from, unsigned long mem_len, |
3837 | const void* lock_from, unsigned long lock_len) |
3838 | { |
3839 | return lock_from + lock_len <= mem_from || |
3840 | mem_from + mem_len <= lock_from; |
3841 | } |
3842 | |
3843 | /* |
3844 | * Called when kernel memory is freed (or unmapped), or if a lock |
3845 | * is destroyed or reinitialized - this code checks whether there is |
3846 | * any held lock in the memory range of <from> to <to>: |
3847 | */ |
3848 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) |
3849 | { |
3850 | struct task_struct *curr = current; |
3851 | struct held_lock *hlock; |
3852 | unsigned long flags; |
3853 | int i; |
3854 | |
3855 | if (unlikely(!debug_locks)) |
3856 | return; |
3857 | |
3858 | local_irq_save(flags); |
3859 | for (i = 0; i < curr->lockdep_depth; i++) { |
3860 | hlock = curr->held_locks + i; |
3861 | |
3862 | if (not_in_range(mem_from, mem_len, hlock->instance, |
3863 | sizeof(*hlock->instance))) |
3864 | continue; |
3865 | |
3866 | print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); |
3867 | break; |
3868 | } |
3869 | local_irq_restore(flags); |
3870 | } |
3871 | EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); |
3872 | |
3873 | static void print_held_locks_bug(struct task_struct *curr) |
3874 | { |
3875 | if (!debug_locks_off()) |
3876 | return; |
3877 | if (debug_locks_silent) |
3878 | return; |
3879 | |
3880 | printk("\n=====================================\n"); |
3881 | printk( "[ BUG: lock held at task exit time! ]\n"); |
3882 | printk( "-------------------------------------\n"); |
3883 | printk("%s/%d is exiting with locks still held!\n", |
3884 | curr->comm, task_pid_nr(curr)); |
3885 | lockdep_print_held_locks(curr); |
3886 | |
3887 | printk("\nstack backtrace:\n"); |
3888 | dump_stack(); |
3889 | } |
3890 | |
3891 | void debug_check_no_locks_held(struct task_struct *task) |
3892 | { |
3893 | if (unlikely(task->lockdep_depth > 0)) |
3894 | print_held_locks_bug(task); |
3895 | } |
3896 | |
3897 | void debug_show_all_locks(void) |
3898 | { |
3899 | struct task_struct *g, *p; |
3900 | int count = 10; |
3901 | int unlock = 1; |
3902 | |
3903 | if (unlikely(!debug_locks)) { |
3904 | printk("INFO: lockdep is turned off.\n"); |
3905 | return; |
3906 | } |
3907 | printk("\nShowing all locks held in the system:\n"); |
3908 | |
3909 | /* |
3910 | * Here we try to get the tasklist_lock as hard as possible, |
3911 | * if not successful after 2 seconds we ignore it (but keep |
3912 | * trying). This is to enable a debug printout even if a |
3913 | * tasklist_lock-holding task deadlocks or crashes. |
3914 | */ |
3915 | retry: |
3916 | if (!read_trylock(&tasklist_lock)) { |
3917 | if (count == 10) |
3918 | printk("hm, tasklist_lock locked, retrying... "); |
3919 | if (count) { |
3920 | count--; |
3921 | printk(" #%d", 10-count); |
3922 | mdelay(200); |
3923 | goto retry; |
3924 | } |
3925 | printk(" ignoring it.\n"); |
3926 | unlock = 0; |
3927 | } else { |
3928 | if (count != 10) |
3929 | printk(KERN_CONT " locked it.\n"); |
3930 | } |
3931 | |
3932 | do_each_thread(g, p) { |
3933 | /* |
3934 | * It's not reliable to print a task's held locks |
3935 | * if it's not sleeping (or if it's not the current |
3936 | * task): |
3937 | */ |
3938 | if (p->state == TASK_RUNNING && p != current) |
3939 | continue; |
3940 | if (p->lockdep_depth) |
3941 | lockdep_print_held_locks(p); |
3942 | if (!unlock) |
3943 | if (read_trylock(&tasklist_lock)) |
3944 | unlock = 1; |
3945 | } while_each_thread(g, p); |
3946 | |
3947 | printk("\n"); |
3948 | printk("=============================================\n\n"); |
3949 | |
3950 | if (unlock) |
3951 | read_unlock(&tasklist_lock); |
3952 | } |
3953 | EXPORT_SYMBOL_GPL(debug_show_all_locks); |
3954 | |
3955 | /* |
3956 | * Careful: only use this function if you are sure that |
3957 | * the task cannot run in parallel! |
3958 | */ |
3959 | void debug_show_held_locks(struct task_struct *task) |
3960 | { |
3961 | if (unlikely(!debug_locks)) { |
3962 | printk("INFO: lockdep is turned off.\n"); |
3963 | return; |
3964 | } |
3965 | lockdep_print_held_locks(task); |
3966 | } |
3967 | EXPORT_SYMBOL_GPL(debug_show_held_locks); |
3968 | |
3969 | void lockdep_sys_exit(void) |
3970 | { |
3971 | struct task_struct *curr = current; |
3972 | |
3973 | if (unlikely(curr->lockdep_depth)) { |
3974 | if (!debug_locks_off()) |
3975 | return; |
3976 | printk("\n================================================\n"); |
3977 | printk( "[ BUG: lock held when returning to user space! ]\n"); |
3978 | printk( "------------------------------------------------\n"); |
3979 | printk("%s/%d is leaving the kernel with locks still held!\n", |
3980 | curr->comm, curr->pid); |
3981 | lockdep_print_held_locks(curr); |
3982 | } |
3983 | } |
3984 | |
3985 | void lockdep_rcu_dereference(const char *file, const int line) |
3986 | { |
3987 | struct task_struct *curr = current; |
3988 | |
3989 | #ifndef CONFIG_PROVE_RCU_REPEATEDLY |
3990 | if (!debug_locks_off()) |
3991 | return; |
3992 | #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */ |
3993 | /* Note: the following can be executed concurrently, so be careful. */ |
3994 | printk("\n===================================================\n"); |
3995 | printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n"); |
3996 | printk( "---------------------------------------------------\n"); |
3997 | printk("%s:%d invoked rcu_dereference_check() without protection!\n", |
3998 | file, line); |
3999 | printk("\nother info that might help us debug this:\n\n"); |
4000 | printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks); |
4001 | lockdep_print_held_locks(curr); |
4002 | printk("\nstack backtrace:\n"); |
4003 | dump_stack(); |
4004 | } |
4005 | EXPORT_SYMBOL_GPL(lockdep_rcu_dereference); |
4006 |
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