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