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Commit | Line | Data |
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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 | |
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 | #include <linux/kmemcheck.h> | |
48 | ||
49 | #include <asm/sections.h> | |
50 | ||
51 | #include "lockdep_internals.h" | |
52 | ||
53 | #define CREATE_TRACE_POINTS | |
54 | #include <trace/events/lock.h> | |
55 | ||
56 | #ifdef CONFIG_PROVE_LOCKING | |
57 | int prove_locking = 1; | |
58 | module_param(prove_locking, int, 0644); | |
59 | #else | |
60 | #define prove_locking 0 | |
61 | #endif | |
62 | ||
63 | #ifdef CONFIG_LOCK_STAT | |
64 | int lock_stat = 1; | |
65 | module_param(lock_stat, int, 0644); | |
66 | #else | |
67 | #define lock_stat 0 | |
68 | #endif | |
69 | ||
70 | /* | |
71 | * lockdep_lock: protects the lockdep graph, the hashes and the | |
72 | * class/list/hash allocators. | |
73 | * | |
74 | * This is one of the rare exceptions where it's justified | |
75 | * to use a raw spinlock - we really dont want the spinlock | |
76 | * code to recurse back into the lockdep code... | |
77 | */ | |
78 | static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; | |
79 | ||
80 | static int graph_lock(void) | |
81 | { | |
82 | arch_spin_lock(&lockdep_lock); | |
83 | /* | |
84 | * Make sure that if another CPU detected a bug while | |
85 | * walking the graph we dont change it (while the other | |
86 | * CPU is busy printing out stuff with the graph lock | |
87 | * dropped already) | |
88 | */ | |
89 | if (!debug_locks) { | |
90 | arch_spin_unlock(&lockdep_lock); | |
91 | return 0; | |
92 | } | |
93 | /* prevent any recursions within lockdep from causing deadlocks */ | |
94 | current->lockdep_recursion++; | |
95 | return 1; | |
96 | } | |
97 | ||
98 | static inline int graph_unlock(void) | |
99 | { | |
100 | if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) { | |
101 | /* | |
102 | * The lockdep graph lock isn't locked while we expect it to | |
103 | * be, we're confused now, bye! | |
104 | */ | |
105 | return DEBUG_LOCKS_WARN_ON(1); | |
106 | } | |
107 | ||
108 | current->lockdep_recursion--; | |
109 | arch_spin_unlock(&lockdep_lock); | |
110 | return 0; | |
111 | } | |
112 | ||
113 | /* | |
114 | * Turn lock debugging off and return with 0 if it was off already, | |
115 | * and also release the graph lock: | |
116 | */ | |
117 | static inline int debug_locks_off_graph_unlock(void) | |
118 | { | |
119 | int ret = debug_locks_off(); | |
120 | ||
121 | arch_spin_unlock(&lockdep_lock); | |
122 | ||
123 | return ret; | |
124 | } | |
125 | ||
126 | unsigned long nr_list_entries; | |
127 | static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; | |
128 | ||
129 | /* | |
130 | * All data structures here are protected by the global debug_lock. | |
131 | * | |
132 | * Mutex key structs only get allocated, once during bootup, and never | |
133 | * get freed - this significantly simplifies the debugging code. | |
134 | */ | |
135 | unsigned long nr_lock_classes; | |
136 | static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; | |
137 | ||
138 | static inline struct lock_class *hlock_class(struct held_lock *hlock) | |
139 | { | |
140 | if (!hlock->class_idx) { | |
141 | /* | |
142 | * Someone passed in garbage, we give up. | |
143 | */ | |
144 | DEBUG_LOCKS_WARN_ON(1); | |
145 | return NULL; | |
146 | } | |
147 | return lock_classes + hlock->class_idx - 1; | |
148 | } | |
149 | ||
150 | #ifdef CONFIG_LOCK_STAT | |
151 | static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], | |
152 | cpu_lock_stats); | |
153 | ||
154 | static inline u64 lockstat_clock(void) | |
155 | { | |
156 | return local_clock(); | |
157 | } | |
158 | ||
159 | static int lock_point(unsigned long points[], unsigned long ip) | |
160 | { | |
161 | int i; | |
162 | ||
163 | for (i = 0; i < LOCKSTAT_POINTS; i++) { | |
164 | if (points[i] == 0) { | |
165 | points[i] = ip; | |
166 | break; | |
167 | } | |
168 | if (points[i] == ip) | |
169 | break; | |
170 | } | |
171 | ||
172 | return i; | |
173 | } | |
174 | ||
175 | static void lock_time_inc(struct lock_time *lt, u64 time) | |
176 | { | |
177 | if (time > lt->max) | |
178 | lt->max = time; | |
179 | ||
180 | if (time < lt->min || !lt->nr) | |
181 | lt->min = time; | |
182 | ||
183 | lt->total += time; | |
184 | lt->nr++; | |
185 | } | |
186 | ||
187 | static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) | |
188 | { | |
189 | if (!src->nr) | |
190 | return; | |
191 | ||
192 | if (src->max > dst->max) | |
193 | dst->max = src->max; | |
194 | ||
195 | if (src->min < dst->min || !dst->nr) | |
196 | dst->min = src->min; | |
197 | ||
198 | dst->total += src->total; | |
199 | dst->nr += src->nr; | |
200 | } | |
201 | ||
202 | struct lock_class_stats lock_stats(struct lock_class *class) | |
203 | { | |
204 | struct lock_class_stats stats; | |
205 | int cpu, i; | |
206 | ||
207 | memset(&stats, 0, sizeof(struct lock_class_stats)); | |
208 | for_each_possible_cpu(cpu) { | |
209 | struct lock_class_stats *pcs = | |
210 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; | |
211 | ||
212 | for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) | |
213 | stats.contention_point[i] += pcs->contention_point[i]; | |
214 | ||
215 | for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) | |
216 | stats.contending_point[i] += pcs->contending_point[i]; | |
217 | ||
218 | lock_time_add(&pcs->read_waittime, &stats.read_waittime); | |
219 | lock_time_add(&pcs->write_waittime, &stats.write_waittime); | |
220 | ||
221 | lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); | |
222 | lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); | |
223 | ||
224 | for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) | |
225 | stats.bounces[i] += pcs->bounces[i]; | |
226 | } | |
227 | ||
228 | return stats; | |
229 | } | |
230 | ||
231 | void clear_lock_stats(struct lock_class *class) | |
232 | { | |
233 | int cpu; | |
234 | ||
235 | for_each_possible_cpu(cpu) { | |
236 | struct lock_class_stats *cpu_stats = | |
237 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; | |
238 | ||
239 | memset(cpu_stats, 0, sizeof(struct lock_class_stats)); | |
240 | } | |
241 | memset(class->contention_point, 0, sizeof(class->contention_point)); | |
242 | memset(class->contending_point, 0, sizeof(class->contending_point)); | |
243 | } | |
244 | ||
245 | static struct lock_class_stats *get_lock_stats(struct lock_class *class) | |
246 | { | |
247 | return &get_cpu_var(cpu_lock_stats)[class - lock_classes]; | |
248 | } | |
249 | ||
250 | static void put_lock_stats(struct lock_class_stats *stats) | |
251 | { | |
252 | put_cpu_var(cpu_lock_stats); | |
253 | } | |
254 | ||
255 | static void lock_release_holdtime(struct held_lock *hlock) | |
256 | { | |
257 | struct lock_class_stats *stats; | |
258 | u64 holdtime; | |
259 | ||
260 | if (!lock_stat) | |
261 | return; | |
262 | ||
263 | holdtime = lockstat_clock() - hlock->holdtime_stamp; | |
264 | ||
265 | stats = get_lock_stats(hlock_class(hlock)); | |
266 | if (hlock->read) | |
267 | lock_time_inc(&stats->read_holdtime, holdtime); | |
268 | else | |
269 | lock_time_inc(&stats->write_holdtime, holdtime); | |
270 | put_lock_stats(stats); | |
271 | } | |
272 | #else | |
273 | static inline void lock_release_holdtime(struct held_lock *hlock) | |
274 | { | |
275 | } | |
276 | #endif | |
277 | ||
278 | /* | |
279 | * We keep a global list of all lock classes. The list only grows, | |
280 | * never shrinks. The list is only accessed with the lockdep | |
281 | * spinlock lock held. | |
282 | */ | |
283 | LIST_HEAD(all_lock_classes); | |
284 | ||
285 | /* | |
286 | * The lockdep classes are in a hash-table as well, for fast lookup: | |
287 | */ | |
288 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) | |
289 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) | |
290 | #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) | |
291 | #define classhashentry(key) (classhash_table + __classhashfn((key))) | |
292 | ||
293 | static struct hlist_head classhash_table[CLASSHASH_SIZE]; | |
294 | ||
295 | /* | |
296 | * We put the lock dependency chains into a hash-table as well, to cache | |
297 | * their existence: | |
298 | */ | |
299 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) | |
300 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) | |
301 | #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) | |
302 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) | |
303 | ||
304 | static struct hlist_head chainhash_table[CHAINHASH_SIZE]; | |
305 | ||
306 | /* | |
307 | * The hash key of the lock dependency chains is a hash itself too: | |
308 | * it's a hash of all locks taken up to that lock, including that lock. | |
309 | * It's a 64-bit hash, because it's important for the keys to be | |
310 | * unique. | |
311 | */ | |
312 | #define iterate_chain_key(key1, key2) \ | |
313 | (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \ | |
314 | ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \ | |
315 | (key2)) | |
316 | ||
317 | void lockdep_off(void) | |
318 | { | |
319 | current->lockdep_recursion++; | |
320 | } | |
321 | EXPORT_SYMBOL(lockdep_off); | |
322 | ||
323 | void lockdep_on(void) | |
324 | { | |
325 | current->lockdep_recursion--; | |
326 | } | |
327 | EXPORT_SYMBOL(lockdep_on); | |
328 | ||
329 | /* | |
330 | * Debugging switches: | |
331 | */ | |
332 | ||
333 | #define VERBOSE 0 | |
334 | #define VERY_VERBOSE 0 | |
335 | ||
336 | #if VERBOSE | |
337 | # define HARDIRQ_VERBOSE 1 | |
338 | # define SOFTIRQ_VERBOSE 1 | |
339 | # define RECLAIM_VERBOSE 1 | |
340 | #else | |
341 | # define HARDIRQ_VERBOSE 0 | |
342 | # define SOFTIRQ_VERBOSE 0 | |
343 | # define RECLAIM_VERBOSE 0 | |
344 | #endif | |
345 | ||
346 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE | |
347 | /* | |
348 | * Quick filtering for interesting events: | |
349 | */ | |
350 | static int class_filter(struct lock_class *class) | |
351 | { | |
352 | #if 0 | |
353 | /* Example */ | |
354 | if (class->name_version == 1 && | |
355 | !strcmp(class->name, "lockname")) | |
356 | return 1; | |
357 | if (class->name_version == 1 && | |
358 | !strcmp(class->name, "&struct->lockfield")) | |
359 | return 1; | |
360 | #endif | |
361 | /* Filter everything else. 1 would be to allow everything else */ | |
362 | return 0; | |
363 | } | |
364 | #endif | |
365 | ||
366 | static int verbose(struct lock_class *class) | |
367 | { | |
368 | #if VERBOSE | |
369 | return class_filter(class); | |
370 | #endif | |
371 | return 0; | |
372 | } | |
373 | ||
374 | /* | |
375 | * Stack-trace: tightly packed array of stack backtrace | |
376 | * addresses. Protected by the graph_lock. | |
377 | */ | |
378 | unsigned long nr_stack_trace_entries; | |
379 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; | |
380 | ||
381 | static void print_lockdep_off(const char *bug_msg) | |
382 | { | |
383 | printk(KERN_DEBUG "%s\n", bug_msg); | |
384 | printk(KERN_DEBUG "turning off the locking correctness validator.\n"); | |
385 | #ifdef CONFIG_LOCK_STAT | |
386 | printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n"); | |
387 | #endif | |
388 | } | |
389 | ||
390 | static int save_trace(struct stack_trace *trace) | |
391 | { | |
392 | trace->nr_entries = 0; | |
393 | trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; | |
394 | trace->entries = stack_trace + nr_stack_trace_entries; | |
395 | ||
396 | trace->skip = 3; | |
397 | ||
398 | save_stack_trace(trace); | |
399 | ||
400 | /* | |
401 | * Some daft arches put -1 at the end to indicate its a full trace. | |
402 | * | |
403 | * <rant> this is buggy anyway, since it takes a whole extra entry so a | |
404 | * complete trace that maxes out the entries provided will be reported | |
405 | * as incomplete, friggin useless </rant> | |
406 | */ | |
407 | if (trace->nr_entries != 0 && | |
408 | trace->entries[trace->nr_entries-1] == ULONG_MAX) | |
409 | trace->nr_entries--; | |
410 | ||
411 | trace->max_entries = trace->nr_entries; | |
412 | ||
413 | nr_stack_trace_entries += trace->nr_entries; | |
414 | ||
415 | if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { | |
416 | if (!debug_locks_off_graph_unlock()) | |
417 | return 0; | |
418 | ||
419 | print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); | |
420 | dump_stack(); | |
421 | ||
422 | return 0; | |
423 | } | |
424 | ||
425 | return 1; | |
426 | } | |
427 | ||
428 | unsigned int nr_hardirq_chains; | |
429 | unsigned int nr_softirq_chains; | |
430 | unsigned int nr_process_chains; | |
431 | unsigned int max_lockdep_depth; | |
432 | ||
433 | #ifdef CONFIG_DEBUG_LOCKDEP | |
434 | /* | |
435 | * Various lockdep statistics: | |
436 | */ | |
437 | DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); | |
438 | #endif | |
439 | ||
440 | /* | |
441 | * Locking printouts: | |
442 | */ | |
443 | ||
444 | #define __USAGE(__STATE) \ | |
445 | [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ | |
446 | [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ | |
447 | [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ | |
448 | [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", | |
449 | ||
450 | static const char *usage_str[] = | |
451 | { | |
452 | #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) | |
453 | #include "lockdep_states.h" | |
454 | #undef LOCKDEP_STATE | |
455 | [LOCK_USED] = "INITIAL USE", | |
456 | }; | |
457 | ||
458 | const char * __get_key_name(struct lockdep_subclass_key *key, char *str) | |
459 | { | |
460 | return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); | |
461 | } | |
462 | ||
463 | static inline unsigned long lock_flag(enum lock_usage_bit bit) | |
464 | { | |
465 | return 1UL << bit; | |
466 | } | |
467 | ||
468 | static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) | |
469 | { | |
470 | char c = '.'; | |
471 | ||
472 | if (class->usage_mask & lock_flag(bit + 2)) | |
473 | c = '+'; | |
474 | if (class->usage_mask & lock_flag(bit)) { | |
475 | c = '-'; | |
476 | if (class->usage_mask & lock_flag(bit + 2)) | |
477 | c = '?'; | |
478 | } | |
479 | ||
480 | return c; | |
481 | } | |
482 | ||
483 | void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) | |
484 | { | |
485 | int i = 0; | |
486 | ||
487 | #define LOCKDEP_STATE(__STATE) \ | |
488 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ | |
489 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); | |
490 | #include "lockdep_states.h" | |
491 | #undef LOCKDEP_STATE | |
492 | ||
493 | usage[i] = '\0'; | |
494 | } | |
495 | ||
496 | static void __print_lock_name(struct lock_class *class) | |
497 | { | |
498 | char str[KSYM_NAME_LEN]; | |
499 | const char *name; | |
500 | ||
501 | name = class->name; | |
502 | if (!name) { | |
503 | name = __get_key_name(class->key, str); | |
504 | printk("%s", name); | |
505 | } else { | |
506 | printk("%s", name); | |
507 | if (class->name_version > 1) | |
508 | printk("#%d", class->name_version); | |
509 | if (class->subclass) | |
510 | printk("/%d", class->subclass); | |
511 | } | |
512 | } | |
513 | ||
514 | static void print_lock_name(struct lock_class *class) | |
515 | { | |
516 | char usage[LOCK_USAGE_CHARS]; | |
517 | ||
518 | get_usage_chars(class, usage); | |
519 | ||
520 | printk(" ("); | |
521 | __print_lock_name(class); | |
522 | printk("){%s}", usage); | |
523 | } | |
524 | ||
525 | static void print_lockdep_cache(struct lockdep_map *lock) | |
526 | { | |
527 | const char *name; | |
528 | char str[KSYM_NAME_LEN]; | |
529 | ||
530 | name = lock->name; | |
531 | if (!name) | |
532 | name = __get_key_name(lock->key->subkeys, str); | |
533 | ||
534 | printk("%s", name); | |
535 | } | |
536 | ||
537 | static void print_lock(struct held_lock *hlock) | |
538 | { | |
539 | /* | |
540 | * We can be called locklessly through debug_show_all_locks() so be | |
541 | * extra careful, the hlock might have been released and cleared. | |
542 | */ | |
543 | unsigned int class_idx = hlock->class_idx; | |
544 | ||
545 | /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */ | |
546 | barrier(); | |
547 | ||
548 | if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) { | |
549 | printk("<RELEASED>\n"); | |
550 | return; | |
551 | } | |
552 | ||
553 | print_lock_name(lock_classes + class_idx - 1); | |
554 | printk(", at: "); | |
555 | print_ip_sym(hlock->acquire_ip); | |
556 | } | |
557 | ||
558 | static void lockdep_print_held_locks(struct task_struct *curr) | |
559 | { | |
560 | int i, depth = curr->lockdep_depth; | |
561 | ||
562 | if (!depth) { | |
563 | printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr)); | |
564 | return; | |
565 | } | |
566 | printk("%d lock%s held by %s/%d:\n", | |
567 | depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr)); | |
568 | ||
569 | for (i = 0; i < depth; i++) { | |
570 | printk(" #%d: ", i); | |
571 | print_lock(curr->held_locks + i); | |
572 | } | |
573 | } | |
574 | ||
575 | static void print_kernel_ident(void) | |
576 | { | |
577 | printk("%s %.*s %s\n", init_utsname()->release, | |
578 | (int)strcspn(init_utsname()->version, " "), | |
579 | init_utsname()->version, | |
580 | print_tainted()); | |
581 | } | |
582 | ||
583 | static int very_verbose(struct lock_class *class) | |
584 | { | |
585 | #if VERY_VERBOSE | |
586 | return class_filter(class); | |
587 | #endif | |
588 | return 0; | |
589 | } | |
590 | ||
591 | /* | |
592 | * Is this the address of a static object: | |
593 | */ | |
594 | #ifdef __KERNEL__ | |
595 | static int static_obj(void *obj) | |
596 | { | |
597 | unsigned long start = (unsigned long) &_stext, | |
598 | end = (unsigned long) &_end, | |
599 | addr = (unsigned long) obj; | |
600 | ||
601 | /* | |
602 | * static variable? | |
603 | */ | |
604 | if ((addr >= start) && (addr < end)) | |
605 | return 1; | |
606 | ||
607 | if (arch_is_kernel_data(addr)) | |
608 | return 1; | |
609 | ||
610 | /* | |
611 | * in-kernel percpu var? | |
612 | */ | |
613 | if (is_kernel_percpu_address(addr)) | |
614 | return 1; | |
615 | ||
616 | /* | |
617 | * module static or percpu var? | |
618 | */ | |
619 | return is_module_address(addr) || is_module_percpu_address(addr); | |
620 | } | |
621 | #endif | |
622 | ||
623 | /* | |
624 | * To make lock name printouts unique, we calculate a unique | |
625 | * class->name_version generation counter: | |
626 | */ | |
627 | static int count_matching_names(struct lock_class *new_class) | |
628 | { | |
629 | struct lock_class *class; | |
630 | int count = 0; | |
631 | ||
632 | if (!new_class->name) | |
633 | return 0; | |
634 | ||
635 | list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) { | |
636 | if (new_class->key - new_class->subclass == class->key) | |
637 | return class->name_version; | |
638 | if (class->name && !strcmp(class->name, new_class->name)) | |
639 | count = max(count, class->name_version); | |
640 | } | |
641 | ||
642 | return count + 1; | |
643 | } | |
644 | ||
645 | /* | |
646 | * Register a lock's class in the hash-table, if the class is not present | |
647 | * yet. Otherwise we look it up. We cache the result in the lock object | |
648 | * itself, so actual lookup of the hash should be once per lock object. | |
649 | */ | |
650 | static inline struct lock_class * | |
651 | look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) | |
652 | { | |
653 | struct lockdep_subclass_key *key; | |
654 | struct hlist_head *hash_head; | |
655 | struct lock_class *class; | |
656 | ||
657 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { | |
658 | debug_locks_off(); | |
659 | printk(KERN_ERR | |
660 | "BUG: looking up invalid subclass: %u\n", subclass); | |
661 | printk(KERN_ERR | |
662 | "turning off the locking correctness validator.\n"); | |
663 | dump_stack(); | |
664 | return NULL; | |
665 | } | |
666 | ||
667 | /* | |
668 | * Static locks do not have their class-keys yet - for them the key | |
669 | * is the lock object itself: | |
670 | */ | |
671 | if (unlikely(!lock->key)) | |
672 | lock->key = (void *)lock; | |
673 | ||
674 | /* | |
675 | * NOTE: the class-key must be unique. For dynamic locks, a static | |
676 | * lock_class_key variable is passed in through the mutex_init() | |
677 | * (or spin_lock_init()) call - which acts as the key. For static | |
678 | * locks we use the lock object itself as the key. | |
679 | */ | |
680 | BUILD_BUG_ON(sizeof(struct lock_class_key) > | |
681 | sizeof(struct lockdep_map)); | |
682 | ||
683 | key = lock->key->subkeys + subclass; | |
684 | ||
685 | hash_head = classhashentry(key); | |
686 | ||
687 | /* | |
688 | * We do an RCU walk of the hash, see lockdep_free_key_range(). | |
689 | */ | |
690 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
691 | return NULL; | |
692 | ||
693 | hlist_for_each_entry_rcu(class, hash_head, hash_entry) { | |
694 | if (class->key == key) { | |
695 | /* | |
696 | * Huh! same key, different name? Did someone trample | |
697 | * on some memory? We're most confused. | |
698 | */ | |
699 | WARN_ON_ONCE(class->name != lock->name); | |
700 | return class; | |
701 | } | |
702 | } | |
703 | ||
704 | return NULL; | |
705 | } | |
706 | ||
707 | /* | |
708 | * Register a lock's class in the hash-table, if the class is not present | |
709 | * yet. Otherwise we look it up. We cache the result in the lock object | |
710 | * itself, so actual lookup of the hash should be once per lock object. | |
711 | */ | |
712 | static inline struct lock_class * | |
713 | register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) | |
714 | { | |
715 | struct lockdep_subclass_key *key; | |
716 | struct hlist_head *hash_head; | |
717 | struct lock_class *class; | |
718 | ||
719 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); | |
720 | ||
721 | class = look_up_lock_class(lock, subclass); | |
722 | if (likely(class)) | |
723 | goto out_set_class_cache; | |
724 | ||
725 | /* | |
726 | * Debug-check: all keys must be persistent! | |
727 | */ | |
728 | if (!static_obj(lock->key)) { | |
729 | debug_locks_off(); | |
730 | printk("INFO: trying to register non-static key.\n"); | |
731 | printk("the code is fine but needs lockdep annotation.\n"); | |
732 | printk("turning off the locking correctness validator.\n"); | |
733 | dump_stack(); | |
734 | ||
735 | return NULL; | |
736 | } | |
737 | ||
738 | key = lock->key->subkeys + subclass; | |
739 | hash_head = classhashentry(key); | |
740 | ||
741 | if (!graph_lock()) { | |
742 | return NULL; | |
743 | } | |
744 | /* | |
745 | * We have to do the hash-walk again, to avoid races | |
746 | * with another CPU: | |
747 | */ | |
748 | hlist_for_each_entry_rcu(class, hash_head, hash_entry) { | |
749 | if (class->key == key) | |
750 | goto out_unlock_set; | |
751 | } | |
752 | ||
753 | /* | |
754 | * Allocate a new key from the static array, and add it to | |
755 | * the hash: | |
756 | */ | |
757 | if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { | |
758 | if (!debug_locks_off_graph_unlock()) { | |
759 | return NULL; | |
760 | } | |
761 | ||
762 | print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!"); | |
763 | dump_stack(); | |
764 | return NULL; | |
765 | } | |
766 | class = lock_classes + nr_lock_classes++; | |
767 | debug_atomic_inc(nr_unused_locks); | |
768 | class->key = key; | |
769 | class->name = lock->name; | |
770 | class->subclass = subclass; | |
771 | INIT_LIST_HEAD(&class->lock_entry); | |
772 | INIT_LIST_HEAD(&class->locks_before); | |
773 | INIT_LIST_HEAD(&class->locks_after); | |
774 | class->name_version = count_matching_names(class); | |
775 | /* | |
776 | * We use RCU's safe list-add method to make | |
777 | * parallel walking of the hash-list safe: | |
778 | */ | |
779 | hlist_add_head_rcu(&class->hash_entry, hash_head); | |
780 | /* | |
781 | * Add it to the global list of classes: | |
782 | */ | |
783 | list_add_tail_rcu(&class->lock_entry, &all_lock_classes); | |
784 | ||
785 | if (verbose(class)) { | |
786 | graph_unlock(); | |
787 | ||
788 | printk("\nnew class %p: %s", class->key, class->name); | |
789 | if (class->name_version > 1) | |
790 | printk("#%d", class->name_version); | |
791 | printk("\n"); | |
792 | dump_stack(); | |
793 | ||
794 | if (!graph_lock()) { | |
795 | return NULL; | |
796 | } | |
797 | } | |
798 | out_unlock_set: | |
799 | graph_unlock(); | |
800 | ||
801 | out_set_class_cache: | |
802 | if (!subclass || force) | |
803 | lock->class_cache[0] = class; | |
804 | else if (subclass < NR_LOCKDEP_CACHING_CLASSES) | |
805 | lock->class_cache[subclass] = class; | |
806 | ||
807 | /* | |
808 | * Hash collision, did we smoke some? We found a class with a matching | |
809 | * hash but the subclass -- which is hashed in -- didn't match. | |
810 | */ | |
811 | if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) | |
812 | return NULL; | |
813 | ||
814 | return class; | |
815 | } | |
816 | ||
817 | #ifdef CONFIG_PROVE_LOCKING | |
818 | /* | |
819 | * Allocate a lockdep entry. (assumes the graph_lock held, returns | |
820 | * with NULL on failure) | |
821 | */ | |
822 | static struct lock_list *alloc_list_entry(void) | |
823 | { | |
824 | if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { | |
825 | if (!debug_locks_off_graph_unlock()) | |
826 | return NULL; | |
827 | ||
828 | print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!"); | |
829 | dump_stack(); | |
830 | return NULL; | |
831 | } | |
832 | return list_entries + nr_list_entries++; | |
833 | } | |
834 | ||
835 | /* | |
836 | * Add a new dependency to the head of the list: | |
837 | */ | |
838 | static int add_lock_to_list(struct lock_class *class, struct lock_class *this, | |
839 | struct list_head *head, unsigned long ip, | |
840 | int distance, struct stack_trace *trace) | |
841 | { | |
842 | struct lock_list *entry; | |
843 | /* | |
844 | * Lock not present yet - get a new dependency struct and | |
845 | * add it to the list: | |
846 | */ | |
847 | entry = alloc_list_entry(); | |
848 | if (!entry) | |
849 | return 0; | |
850 | ||
851 | entry->class = this; | |
852 | entry->distance = distance; | |
853 | entry->trace = *trace; | |
854 | /* | |
855 | * Both allocation and removal are done under the graph lock; but | |
856 | * iteration is under RCU-sched; see look_up_lock_class() and | |
857 | * lockdep_free_key_range(). | |
858 | */ | |
859 | list_add_tail_rcu(&entry->entry, head); | |
860 | ||
861 | return 1; | |
862 | } | |
863 | ||
864 | /* | |
865 | * For good efficiency of modular, we use power of 2 | |
866 | */ | |
867 | #define MAX_CIRCULAR_QUEUE_SIZE 4096UL | |
868 | #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) | |
869 | ||
870 | /* | |
871 | * The circular_queue and helpers is used to implement the | |
872 | * breadth-first search(BFS)algorithem, by which we can build | |
873 | * the shortest path from the next lock to be acquired to the | |
874 | * previous held lock if there is a circular between them. | |
875 | */ | |
876 | struct circular_queue { | |
877 | unsigned long element[MAX_CIRCULAR_QUEUE_SIZE]; | |
878 | unsigned int front, rear; | |
879 | }; | |
880 | ||
881 | static struct circular_queue lock_cq; | |
882 | ||
883 | unsigned int max_bfs_queue_depth; | |
884 | ||
885 | static unsigned int lockdep_dependency_gen_id; | |
886 | ||
887 | static inline void __cq_init(struct circular_queue *cq) | |
888 | { | |
889 | cq->front = cq->rear = 0; | |
890 | lockdep_dependency_gen_id++; | |
891 | } | |
892 | ||
893 | static inline int __cq_empty(struct circular_queue *cq) | |
894 | { | |
895 | return (cq->front == cq->rear); | |
896 | } | |
897 | ||
898 | static inline int __cq_full(struct circular_queue *cq) | |
899 | { | |
900 | return ((cq->rear + 1) & CQ_MASK) == cq->front; | |
901 | } | |
902 | ||
903 | static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) | |
904 | { | |
905 | if (__cq_full(cq)) | |
906 | return -1; | |
907 | ||
908 | cq->element[cq->rear] = elem; | |
909 | cq->rear = (cq->rear + 1) & CQ_MASK; | |
910 | return 0; | |
911 | } | |
912 | ||
913 | static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) | |
914 | { | |
915 | if (__cq_empty(cq)) | |
916 | return -1; | |
917 | ||
918 | *elem = cq->element[cq->front]; | |
919 | cq->front = (cq->front + 1) & CQ_MASK; | |
920 | return 0; | |
921 | } | |
922 | ||
923 | static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) | |
924 | { | |
925 | return (cq->rear - cq->front) & CQ_MASK; | |
926 | } | |
927 | ||
928 | static inline void mark_lock_accessed(struct lock_list *lock, | |
929 | struct lock_list *parent) | |
930 | { | |
931 | unsigned long nr; | |
932 | ||
933 | nr = lock - list_entries; | |
934 | WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ | |
935 | lock->parent = parent; | |
936 | lock->class->dep_gen_id = lockdep_dependency_gen_id; | |
937 | } | |
938 | ||
939 | static inline unsigned long lock_accessed(struct lock_list *lock) | |
940 | { | |
941 | unsigned long nr; | |
942 | ||
943 | nr = lock - list_entries; | |
944 | WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ | |
945 | return lock->class->dep_gen_id == lockdep_dependency_gen_id; | |
946 | } | |
947 | ||
948 | static inline struct lock_list *get_lock_parent(struct lock_list *child) | |
949 | { | |
950 | return child->parent; | |
951 | } | |
952 | ||
953 | static inline int get_lock_depth(struct lock_list *child) | |
954 | { | |
955 | int depth = 0; | |
956 | struct lock_list *parent; | |
957 | ||
958 | while ((parent = get_lock_parent(child))) { | |
959 | child = parent; | |
960 | depth++; | |
961 | } | |
962 | return depth; | |
963 | } | |
964 | ||
965 | static int __bfs(struct lock_list *source_entry, | |
966 | void *data, | |
967 | int (*match)(struct lock_list *entry, void *data), | |
968 | struct lock_list **target_entry, | |
969 | int forward) | |
970 | { | |
971 | struct lock_list *entry; | |
972 | struct list_head *head; | |
973 | struct circular_queue *cq = &lock_cq; | |
974 | int ret = 1; | |
975 | ||
976 | if (match(source_entry, data)) { | |
977 | *target_entry = source_entry; | |
978 | ret = 0; | |
979 | goto exit; | |
980 | } | |
981 | ||
982 | if (forward) | |
983 | head = &source_entry->class->locks_after; | |
984 | else | |
985 | head = &source_entry->class->locks_before; | |
986 | ||
987 | if (list_empty(head)) | |
988 | goto exit; | |
989 | ||
990 | __cq_init(cq); | |
991 | __cq_enqueue(cq, (unsigned long)source_entry); | |
992 | ||
993 | while (!__cq_empty(cq)) { | |
994 | struct lock_list *lock; | |
995 | ||
996 | __cq_dequeue(cq, (unsigned long *)&lock); | |
997 | ||
998 | if (!lock->class) { | |
999 | ret = -2; | |
1000 | goto exit; | |
1001 | } | |
1002 | ||
1003 | if (forward) | |
1004 | head = &lock->class->locks_after; | |
1005 | else | |
1006 | head = &lock->class->locks_before; | |
1007 | ||
1008 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); | |
1009 | ||
1010 | list_for_each_entry_rcu(entry, head, entry) { | |
1011 | if (!lock_accessed(entry)) { | |
1012 | unsigned int cq_depth; | |
1013 | mark_lock_accessed(entry, lock); | |
1014 | if (match(entry, data)) { | |
1015 | *target_entry = entry; | |
1016 | ret = 0; | |
1017 | goto exit; | |
1018 | } | |
1019 | ||
1020 | if (__cq_enqueue(cq, (unsigned long)entry)) { | |
1021 | ret = -1; | |
1022 | goto exit; | |
1023 | } | |
1024 | cq_depth = __cq_get_elem_count(cq); | |
1025 | if (max_bfs_queue_depth < cq_depth) | |
1026 | max_bfs_queue_depth = cq_depth; | |
1027 | } | |
1028 | } | |
1029 | } | |
1030 | exit: | |
1031 | return ret; | |
1032 | } | |
1033 | ||
1034 | static inline int __bfs_forwards(struct lock_list *src_entry, | |
1035 | void *data, | |
1036 | int (*match)(struct lock_list *entry, void *data), | |
1037 | struct lock_list **target_entry) | |
1038 | { | |
1039 | return __bfs(src_entry, data, match, target_entry, 1); | |
1040 | ||
1041 | } | |
1042 | ||
1043 | static inline int __bfs_backwards(struct lock_list *src_entry, | |
1044 | void *data, | |
1045 | int (*match)(struct lock_list *entry, void *data), | |
1046 | struct lock_list **target_entry) | |
1047 | { | |
1048 | return __bfs(src_entry, data, match, target_entry, 0); | |
1049 | ||
1050 | } | |
1051 | ||
1052 | /* | |
1053 | * Recursive, forwards-direction lock-dependency checking, used for | |
1054 | * both noncyclic checking and for hardirq-unsafe/softirq-unsafe | |
1055 | * checking. | |
1056 | */ | |
1057 | ||
1058 | /* | |
1059 | * Print a dependency chain entry (this is only done when a deadlock | |
1060 | * has been detected): | |
1061 | */ | |
1062 | static noinline int | |
1063 | print_circular_bug_entry(struct lock_list *target, int depth) | |
1064 | { | |
1065 | if (debug_locks_silent) | |
1066 | return 0; | |
1067 | printk("\n-> #%u", depth); | |
1068 | print_lock_name(target->class); | |
1069 | printk(":\n"); | |
1070 | print_stack_trace(&target->trace, 6); | |
1071 | ||
1072 | return 0; | |
1073 | } | |
1074 | ||
1075 | static void | |
1076 | print_circular_lock_scenario(struct held_lock *src, | |
1077 | struct held_lock *tgt, | |
1078 | struct lock_list *prt) | |
1079 | { | |
1080 | struct lock_class *source = hlock_class(src); | |
1081 | struct lock_class *target = hlock_class(tgt); | |
1082 | struct lock_class *parent = prt->class; | |
1083 | ||
1084 | /* | |
1085 | * A direct locking problem where unsafe_class lock is taken | |
1086 | * directly by safe_class lock, then all we need to show | |
1087 | * is the deadlock scenario, as it is obvious that the | |
1088 | * unsafe lock is taken under the safe lock. | |
1089 | * | |
1090 | * But if there is a chain instead, where the safe lock takes | |
1091 | * an intermediate lock (middle_class) where this lock is | |
1092 | * not the same as the safe lock, then the lock chain is | |
1093 | * used to describe the problem. Otherwise we would need | |
1094 | * to show a different CPU case for each link in the chain | |
1095 | * from the safe_class lock to the unsafe_class lock. | |
1096 | */ | |
1097 | if (parent != source) { | |
1098 | printk("Chain exists of:\n "); | |
1099 | __print_lock_name(source); | |
1100 | printk(" --> "); | |
1101 | __print_lock_name(parent); | |
1102 | printk(" --> "); | |
1103 | __print_lock_name(target); | |
1104 | printk("\n\n"); | |
1105 | } | |
1106 | ||
1107 | printk(" Possible unsafe locking scenario:\n\n"); | |
1108 | printk(" CPU0 CPU1\n"); | |
1109 | printk(" ---- ----\n"); | |
1110 | printk(" lock("); | |
1111 | __print_lock_name(target); | |
1112 | printk(");\n"); | |
1113 | printk(" lock("); | |
1114 | __print_lock_name(parent); | |
1115 | printk(");\n"); | |
1116 | printk(" lock("); | |
1117 | __print_lock_name(target); | |
1118 | printk(");\n"); | |
1119 | printk(" lock("); | |
1120 | __print_lock_name(source); | |
1121 | printk(");\n"); | |
1122 | printk("\n *** DEADLOCK ***\n\n"); | |
1123 | } | |
1124 | ||
1125 | /* | |
1126 | * When a circular dependency is detected, print the | |
1127 | * header first: | |
1128 | */ | |
1129 | static noinline int | |
1130 | print_circular_bug_header(struct lock_list *entry, unsigned int depth, | |
1131 | struct held_lock *check_src, | |
1132 | struct held_lock *check_tgt) | |
1133 | { | |
1134 | struct task_struct *curr = current; | |
1135 | ||
1136 | if (debug_locks_silent) | |
1137 | return 0; | |
1138 | ||
1139 | printk("\n"); | |
1140 | printk("======================================================\n"); | |
1141 | printk("[ INFO: possible circular locking dependency detected ]\n"); | |
1142 | print_kernel_ident(); | |
1143 | printk("-------------------------------------------------------\n"); | |
1144 | printk("%s/%d is trying to acquire lock:\n", | |
1145 | curr->comm, task_pid_nr(curr)); | |
1146 | print_lock(check_src); | |
1147 | printk("\nbut task is already holding lock:\n"); | |
1148 | print_lock(check_tgt); | |
1149 | printk("\nwhich lock already depends on the new lock.\n\n"); | |
1150 | printk("\nthe existing dependency chain (in reverse order) is:\n"); | |
1151 | ||
1152 | print_circular_bug_entry(entry, depth); | |
1153 | ||
1154 | return 0; | |
1155 | } | |
1156 | ||
1157 | static inline int class_equal(struct lock_list *entry, void *data) | |
1158 | { | |
1159 | return entry->class == data; | |
1160 | } | |
1161 | ||
1162 | static noinline int print_circular_bug(struct lock_list *this, | |
1163 | struct lock_list *target, | |
1164 | struct held_lock *check_src, | |
1165 | struct held_lock *check_tgt) | |
1166 | { | |
1167 | struct task_struct *curr = current; | |
1168 | struct lock_list *parent; | |
1169 | struct lock_list *first_parent; | |
1170 | int depth; | |
1171 | ||
1172 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) | |
1173 | return 0; | |
1174 | ||
1175 | if (!save_trace(&this->trace)) | |
1176 | return 0; | |
1177 | ||
1178 | depth = get_lock_depth(target); | |
1179 | ||
1180 | print_circular_bug_header(target, depth, check_src, check_tgt); | |
1181 | ||
1182 | parent = get_lock_parent(target); | |
1183 | first_parent = parent; | |
1184 | ||
1185 | while (parent) { | |
1186 | print_circular_bug_entry(parent, --depth); | |
1187 | parent = get_lock_parent(parent); | |
1188 | } | |
1189 | ||
1190 | printk("\nother info that might help us debug this:\n\n"); | |
1191 | print_circular_lock_scenario(check_src, check_tgt, | |
1192 | first_parent); | |
1193 | ||
1194 | lockdep_print_held_locks(curr); | |
1195 | ||
1196 | printk("\nstack backtrace:\n"); | |
1197 | dump_stack(); | |
1198 | ||
1199 | return 0; | |
1200 | } | |
1201 | ||
1202 | static noinline int print_bfs_bug(int ret) | |
1203 | { | |
1204 | if (!debug_locks_off_graph_unlock()) | |
1205 | return 0; | |
1206 | ||
1207 | /* | |
1208 | * Breadth-first-search failed, graph got corrupted? | |
1209 | */ | |
1210 | WARN(1, "lockdep bfs error:%d\n", ret); | |
1211 | ||
1212 | return 0; | |
1213 | } | |
1214 | ||
1215 | static int noop_count(struct lock_list *entry, void *data) | |
1216 | { | |
1217 | (*(unsigned long *)data)++; | |
1218 | return 0; | |
1219 | } | |
1220 | ||
1221 | static unsigned long __lockdep_count_forward_deps(struct lock_list *this) | |
1222 | { | |
1223 | unsigned long count = 0; | |
1224 | struct lock_list *uninitialized_var(target_entry); | |
1225 | ||
1226 | __bfs_forwards(this, (void *)&count, noop_count, &target_entry); | |
1227 | ||
1228 | return count; | |
1229 | } | |
1230 | unsigned long lockdep_count_forward_deps(struct lock_class *class) | |
1231 | { | |
1232 | unsigned long ret, flags; | |
1233 | struct lock_list this; | |
1234 | ||
1235 | this.parent = NULL; | |
1236 | this.class = class; | |
1237 | ||
1238 | local_irq_save(flags); | |
1239 | arch_spin_lock(&lockdep_lock); | |
1240 | ret = __lockdep_count_forward_deps(&this); | |
1241 | arch_spin_unlock(&lockdep_lock); | |
1242 | local_irq_restore(flags); | |
1243 | ||
1244 | return ret; | |
1245 | } | |
1246 | ||
1247 | static unsigned long __lockdep_count_backward_deps(struct lock_list *this) | |
1248 | { | |
1249 | unsigned long count = 0; | |
1250 | struct lock_list *uninitialized_var(target_entry); | |
1251 | ||
1252 | __bfs_backwards(this, (void *)&count, noop_count, &target_entry); | |
1253 | ||
1254 | return count; | |
1255 | } | |
1256 | ||
1257 | unsigned long lockdep_count_backward_deps(struct lock_class *class) | |
1258 | { | |
1259 | unsigned long ret, flags; | |
1260 | struct lock_list this; | |
1261 | ||
1262 | this.parent = NULL; | |
1263 | this.class = class; | |
1264 | ||
1265 | local_irq_save(flags); | |
1266 | arch_spin_lock(&lockdep_lock); | |
1267 | ret = __lockdep_count_backward_deps(&this); | |
1268 | arch_spin_unlock(&lockdep_lock); | |
1269 | local_irq_restore(flags); | |
1270 | ||
1271 | return ret; | |
1272 | } | |
1273 | ||
1274 | /* | |
1275 | * Prove that the dependency graph starting at <entry> can not | |
1276 | * lead to <target>. Print an error and return 0 if it does. | |
1277 | */ | |
1278 | static noinline int | |
1279 | check_noncircular(struct lock_list *root, struct lock_class *target, | |
1280 | struct lock_list **target_entry) | |
1281 | { | |
1282 | int result; | |
1283 | ||
1284 | debug_atomic_inc(nr_cyclic_checks); | |
1285 | ||
1286 | result = __bfs_forwards(root, target, class_equal, target_entry); | |
1287 | ||
1288 | return result; | |
1289 | } | |
1290 | ||
1291 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) | |
1292 | /* | |
1293 | * Forwards and backwards subgraph searching, for the purposes of | |
1294 | * proving that two subgraphs can be connected by a new dependency | |
1295 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. | |
1296 | */ | |
1297 | ||
1298 | static inline int usage_match(struct lock_list *entry, void *bit) | |
1299 | { | |
1300 | return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); | |
1301 | } | |
1302 | ||
1303 | ||
1304 | ||
1305 | /* | |
1306 | * Find a node in the forwards-direction dependency sub-graph starting | |
1307 | * at @root->class that matches @bit. | |
1308 | * | |
1309 | * Return 0 if such a node exists in the subgraph, and put that node | |
1310 | * into *@target_entry. | |
1311 | * | |
1312 | * Return 1 otherwise and keep *@target_entry unchanged. | |
1313 | * Return <0 on error. | |
1314 | */ | |
1315 | static int | |
1316 | find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, | |
1317 | struct lock_list **target_entry) | |
1318 | { | |
1319 | int result; | |
1320 | ||
1321 | debug_atomic_inc(nr_find_usage_forwards_checks); | |
1322 | ||
1323 | result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); | |
1324 | ||
1325 | return result; | |
1326 | } | |
1327 | ||
1328 | /* | |
1329 | * Find a node in the backwards-direction dependency sub-graph starting | |
1330 | * at @root->class that matches @bit. | |
1331 | * | |
1332 | * Return 0 if such a node exists in the subgraph, and put that node | |
1333 | * into *@target_entry. | |
1334 | * | |
1335 | * Return 1 otherwise and keep *@target_entry unchanged. | |
1336 | * Return <0 on error. | |
1337 | */ | |
1338 | static int | |
1339 | find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, | |
1340 | struct lock_list **target_entry) | |
1341 | { | |
1342 | int result; | |
1343 | ||
1344 | debug_atomic_inc(nr_find_usage_backwards_checks); | |
1345 | ||
1346 | result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); | |
1347 | ||
1348 | return result; | |
1349 | } | |
1350 | ||
1351 | static void print_lock_class_header(struct lock_class *class, int depth) | |
1352 | { | |
1353 | int bit; | |
1354 | ||
1355 | printk("%*s->", depth, ""); | |
1356 | print_lock_name(class); | |
1357 | printk(" ops: %lu", class->ops); | |
1358 | printk(" {\n"); | |
1359 | ||
1360 | for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { | |
1361 | if (class->usage_mask & (1 << bit)) { | |
1362 | int len = depth; | |
1363 | ||
1364 | len += printk("%*s %s", depth, "", usage_str[bit]); | |
1365 | len += printk(" at:\n"); | |
1366 | print_stack_trace(class->usage_traces + bit, len); | |
1367 | } | |
1368 | } | |
1369 | printk("%*s }\n", depth, ""); | |
1370 | ||
1371 | printk("%*s ... key at: ",depth,""); | |
1372 | print_ip_sym((unsigned long)class->key); | |
1373 | } | |
1374 | ||
1375 | /* | |
1376 | * printk the shortest lock dependencies from @start to @end in reverse order: | |
1377 | */ | |
1378 | static void __used | |
1379 | print_shortest_lock_dependencies(struct lock_list *leaf, | |
1380 | struct lock_list *root) | |
1381 | { | |
1382 | struct lock_list *entry = leaf; | |
1383 | int depth; | |
1384 | ||
1385 | /*compute depth from generated tree by BFS*/ | |
1386 | depth = get_lock_depth(leaf); | |
1387 | ||
1388 | do { | |
1389 | print_lock_class_header(entry->class, depth); | |
1390 | printk("%*s ... acquired at:\n", depth, ""); | |
1391 | print_stack_trace(&entry->trace, 2); | |
1392 | printk("\n"); | |
1393 | ||
1394 | if (depth == 0 && (entry != root)) { | |
1395 | printk("lockdep:%s bad path found in chain graph\n", __func__); | |
1396 | break; | |
1397 | } | |
1398 | ||
1399 | entry = get_lock_parent(entry); | |
1400 | depth--; | |
1401 | } while (entry && (depth >= 0)); | |
1402 | ||
1403 | return; | |
1404 | } | |
1405 | ||
1406 | static void | |
1407 | print_irq_lock_scenario(struct lock_list *safe_entry, | |
1408 | struct lock_list *unsafe_entry, | |
1409 | struct lock_class *prev_class, | |
1410 | struct lock_class *next_class) | |
1411 | { | |
1412 | struct lock_class *safe_class = safe_entry->class; | |
1413 | struct lock_class *unsafe_class = unsafe_entry->class; | |
1414 | struct lock_class *middle_class = prev_class; | |
1415 | ||
1416 | if (middle_class == safe_class) | |
1417 | middle_class = next_class; | |
1418 | ||
1419 | /* | |
1420 | * A direct locking problem where unsafe_class lock is taken | |
1421 | * directly by safe_class lock, then all we need to show | |
1422 | * is the deadlock scenario, as it is obvious that the | |
1423 | * unsafe lock is taken under the safe lock. | |
1424 | * | |
1425 | * But if there is a chain instead, where the safe lock takes | |
1426 | * an intermediate lock (middle_class) where this lock is | |
1427 | * not the same as the safe lock, then the lock chain is | |
1428 | * used to describe the problem. Otherwise we would need | |
1429 | * to show a different CPU case for each link in the chain | |
1430 | * from the safe_class lock to the unsafe_class lock. | |
1431 | */ | |
1432 | if (middle_class != unsafe_class) { | |
1433 | printk("Chain exists of:\n "); | |
1434 | __print_lock_name(safe_class); | |
1435 | printk(" --> "); | |
1436 | __print_lock_name(middle_class); | |
1437 | printk(" --> "); | |
1438 | __print_lock_name(unsafe_class); | |
1439 | printk("\n\n"); | |
1440 | } | |
1441 | ||
1442 | printk(" Possible interrupt unsafe locking scenario:\n\n"); | |
1443 | printk(" CPU0 CPU1\n"); | |
1444 | printk(" ---- ----\n"); | |
1445 | printk(" lock("); | |
1446 | __print_lock_name(unsafe_class); | |
1447 | printk(");\n"); | |
1448 | printk(" local_irq_disable();\n"); | |
1449 | printk(" lock("); | |
1450 | __print_lock_name(safe_class); | |
1451 | printk(");\n"); | |
1452 | printk(" lock("); | |
1453 | __print_lock_name(middle_class); | |
1454 | printk(");\n"); | |
1455 | printk(" <Interrupt>\n"); | |
1456 | printk(" lock("); | |
1457 | __print_lock_name(safe_class); | |
1458 | printk(");\n"); | |
1459 | printk("\n *** DEADLOCK ***\n\n"); | |
1460 | } | |
1461 | ||
1462 | static int | |
1463 | print_bad_irq_dependency(struct task_struct *curr, | |
1464 | struct lock_list *prev_root, | |
1465 | struct lock_list *next_root, | |
1466 | struct lock_list *backwards_entry, | |
1467 | struct lock_list *forwards_entry, | |
1468 | struct held_lock *prev, | |
1469 | struct held_lock *next, | |
1470 | enum lock_usage_bit bit1, | |
1471 | enum lock_usage_bit bit2, | |
1472 | const char *irqclass) | |
1473 | { | |
1474 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) | |
1475 | return 0; | |
1476 | ||
1477 | printk("\n"); | |
1478 | printk("======================================================\n"); | |
1479 | printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", | |
1480 | irqclass, irqclass); | |
1481 | print_kernel_ident(); | |
1482 | printk("------------------------------------------------------\n"); | |
1483 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", | |
1484 | curr->comm, task_pid_nr(curr), | |
1485 | curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, | |
1486 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, | |
1487 | curr->hardirqs_enabled, | |
1488 | curr->softirqs_enabled); | |
1489 | print_lock(next); | |
1490 | ||
1491 | printk("\nand this task is already holding:\n"); | |
1492 | print_lock(prev); | |
1493 | printk("which would create a new lock dependency:\n"); | |
1494 | print_lock_name(hlock_class(prev)); | |
1495 | printk(" ->"); | |
1496 | print_lock_name(hlock_class(next)); | |
1497 | printk("\n"); | |
1498 | ||
1499 | printk("\nbut this new dependency connects a %s-irq-safe lock:\n", | |
1500 | irqclass); | |
1501 | print_lock_name(backwards_entry->class); | |
1502 | printk("\n... which became %s-irq-safe at:\n", irqclass); | |
1503 | ||
1504 | print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); | |
1505 | ||
1506 | printk("\nto a %s-irq-unsafe lock:\n", irqclass); | |
1507 | print_lock_name(forwards_entry->class); | |
1508 | printk("\n... which became %s-irq-unsafe at:\n", irqclass); | |
1509 | printk("..."); | |
1510 | ||
1511 | print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); | |
1512 | ||
1513 | printk("\nother info that might help us debug this:\n\n"); | |
1514 | print_irq_lock_scenario(backwards_entry, forwards_entry, | |
1515 | hlock_class(prev), hlock_class(next)); | |
1516 | ||
1517 | lockdep_print_held_locks(curr); | |
1518 | ||
1519 | printk("\nthe dependencies between %s-irq-safe lock", irqclass); | |
1520 | printk(" and the holding lock:\n"); | |
1521 | if (!save_trace(&prev_root->trace)) | |
1522 | return 0; | |
1523 | print_shortest_lock_dependencies(backwards_entry, prev_root); | |
1524 | ||
1525 | printk("\nthe dependencies between the lock to be acquired"); | |
1526 | printk(" and %s-irq-unsafe lock:\n", irqclass); | |
1527 | if (!save_trace(&next_root->trace)) | |
1528 | return 0; | |
1529 | print_shortest_lock_dependencies(forwards_entry, next_root); | |
1530 | ||
1531 | printk("\nstack backtrace:\n"); | |
1532 | dump_stack(); | |
1533 | ||
1534 | return 0; | |
1535 | } | |
1536 | ||
1537 | static int | |
1538 | check_usage(struct task_struct *curr, struct held_lock *prev, | |
1539 | struct held_lock *next, enum lock_usage_bit bit_backwards, | |
1540 | enum lock_usage_bit bit_forwards, const char *irqclass) | |
1541 | { | |
1542 | int ret; | |
1543 | struct lock_list this, that; | |
1544 | struct lock_list *uninitialized_var(target_entry); | |
1545 | struct lock_list *uninitialized_var(target_entry1); | |
1546 | ||
1547 | this.parent = NULL; | |
1548 | ||
1549 | this.class = hlock_class(prev); | |
1550 | ret = find_usage_backwards(&this, bit_backwards, &target_entry); | |
1551 | if (ret < 0) | |
1552 | return print_bfs_bug(ret); | |
1553 | if (ret == 1) | |
1554 | return ret; | |
1555 | ||
1556 | that.parent = NULL; | |
1557 | that.class = hlock_class(next); | |
1558 | ret = find_usage_forwards(&that, bit_forwards, &target_entry1); | |
1559 | if (ret < 0) | |
1560 | return print_bfs_bug(ret); | |
1561 | if (ret == 1) | |
1562 | return ret; | |
1563 | ||
1564 | return print_bad_irq_dependency(curr, &this, &that, | |
1565 | target_entry, target_entry1, | |
1566 | prev, next, | |
1567 | bit_backwards, bit_forwards, irqclass); | |
1568 | } | |
1569 | ||
1570 | static const char *state_names[] = { | |
1571 | #define LOCKDEP_STATE(__STATE) \ | |
1572 | __stringify(__STATE), | |
1573 | #include "lockdep_states.h" | |
1574 | #undef LOCKDEP_STATE | |
1575 | }; | |
1576 | ||
1577 | static const char *state_rnames[] = { | |
1578 | #define LOCKDEP_STATE(__STATE) \ | |
1579 | __stringify(__STATE)"-READ", | |
1580 | #include "lockdep_states.h" | |
1581 | #undef LOCKDEP_STATE | |
1582 | }; | |
1583 | ||
1584 | static inline const char *state_name(enum lock_usage_bit bit) | |
1585 | { | |
1586 | return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2]; | |
1587 | } | |
1588 | ||
1589 | static int exclusive_bit(int new_bit) | |
1590 | { | |
1591 | /* | |
1592 | * USED_IN | |
1593 | * USED_IN_READ | |
1594 | * ENABLED | |
1595 | * ENABLED_READ | |
1596 | * | |
1597 | * bit 0 - write/read | |
1598 | * bit 1 - used_in/enabled | |
1599 | * bit 2+ state | |
1600 | */ | |
1601 | ||
1602 | int state = new_bit & ~3; | |
1603 | int dir = new_bit & 2; | |
1604 | ||
1605 | /* | |
1606 | * keep state, bit flip the direction and strip read. | |
1607 | */ | |
1608 | return state | (dir ^ 2); | |
1609 | } | |
1610 | ||
1611 | static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, | |
1612 | struct held_lock *next, enum lock_usage_bit bit) | |
1613 | { | |
1614 | /* | |
1615 | * Prove that the new dependency does not connect a hardirq-safe | |
1616 | * lock with a hardirq-unsafe lock - to achieve this we search | |
1617 | * the backwards-subgraph starting at <prev>, and the | |
1618 | * forwards-subgraph starting at <next>: | |
1619 | */ | |
1620 | if (!check_usage(curr, prev, next, bit, | |
1621 | exclusive_bit(bit), state_name(bit))) | |
1622 | return 0; | |
1623 | ||
1624 | bit++; /* _READ */ | |
1625 | ||
1626 | /* | |
1627 | * Prove that the new dependency does not connect a hardirq-safe-read | |
1628 | * lock with a hardirq-unsafe lock - to achieve this we search | |
1629 | * the backwards-subgraph starting at <prev>, and the | |
1630 | * forwards-subgraph starting at <next>: | |
1631 | */ | |
1632 | if (!check_usage(curr, prev, next, bit, | |
1633 | exclusive_bit(bit), state_name(bit))) | |
1634 | return 0; | |
1635 | ||
1636 | return 1; | |
1637 | } | |
1638 | ||
1639 | static int | |
1640 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, | |
1641 | struct held_lock *next) | |
1642 | { | |
1643 | #define LOCKDEP_STATE(__STATE) \ | |
1644 | if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ | |
1645 | return 0; | |
1646 | #include "lockdep_states.h" | |
1647 | #undef LOCKDEP_STATE | |
1648 | ||
1649 | return 1; | |
1650 | } | |
1651 | ||
1652 | static void inc_chains(void) | |
1653 | { | |
1654 | if (current->hardirq_context) | |
1655 | nr_hardirq_chains++; | |
1656 | else { | |
1657 | if (current->softirq_context) | |
1658 | nr_softirq_chains++; | |
1659 | else | |
1660 | nr_process_chains++; | |
1661 | } | |
1662 | } | |
1663 | ||
1664 | #else | |
1665 | ||
1666 | static inline int | |
1667 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, | |
1668 | struct held_lock *next) | |
1669 | { | |
1670 | return 1; | |
1671 | } | |
1672 | ||
1673 | static inline void inc_chains(void) | |
1674 | { | |
1675 | nr_process_chains++; | |
1676 | } | |
1677 | ||
1678 | #endif | |
1679 | ||
1680 | static void | |
1681 | print_deadlock_scenario(struct held_lock *nxt, | |
1682 | struct held_lock *prv) | |
1683 | { | |
1684 | struct lock_class *next = hlock_class(nxt); | |
1685 | struct lock_class *prev = hlock_class(prv); | |
1686 | ||
1687 | printk(" Possible unsafe locking scenario:\n\n"); | |
1688 | printk(" CPU0\n"); | |
1689 | printk(" ----\n"); | |
1690 | printk(" lock("); | |
1691 | __print_lock_name(prev); | |
1692 | printk(");\n"); | |
1693 | printk(" lock("); | |
1694 | __print_lock_name(next); | |
1695 | printk(");\n"); | |
1696 | printk("\n *** DEADLOCK ***\n\n"); | |
1697 | printk(" May be due to missing lock nesting notation\n\n"); | |
1698 | } | |
1699 | ||
1700 | static int | |
1701 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, | |
1702 | struct held_lock *next) | |
1703 | { | |
1704 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) | |
1705 | return 0; | |
1706 | ||
1707 | printk("\n"); | |
1708 | printk("=============================================\n"); | |
1709 | printk("[ INFO: possible recursive locking detected ]\n"); | |
1710 | print_kernel_ident(); | |
1711 | printk("---------------------------------------------\n"); | |
1712 | printk("%s/%d is trying to acquire lock:\n", | |
1713 | curr->comm, task_pid_nr(curr)); | |
1714 | print_lock(next); | |
1715 | printk("\nbut task is already holding lock:\n"); | |
1716 | print_lock(prev); | |
1717 | ||
1718 | printk("\nother info that might help us debug this:\n"); | |
1719 | print_deadlock_scenario(next, prev); | |
1720 | lockdep_print_held_locks(curr); | |
1721 | ||
1722 | printk("\nstack backtrace:\n"); | |
1723 | dump_stack(); | |
1724 | ||
1725 | return 0; | |
1726 | } | |
1727 | ||
1728 | /* | |
1729 | * Check whether we are holding such a class already. | |
1730 | * | |
1731 | * (Note that this has to be done separately, because the graph cannot | |
1732 | * detect such classes of deadlocks.) | |
1733 | * | |
1734 | * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read | |
1735 | */ | |
1736 | static int | |
1737 | check_deadlock(struct task_struct *curr, struct held_lock *next, | |
1738 | struct lockdep_map *next_instance, int read) | |
1739 | { | |
1740 | struct held_lock *prev; | |
1741 | struct held_lock *nest = NULL; | |
1742 | int i; | |
1743 | ||
1744 | for (i = 0; i < curr->lockdep_depth; i++) { | |
1745 | prev = curr->held_locks + i; | |
1746 | ||
1747 | if (prev->instance == next->nest_lock) | |
1748 | nest = prev; | |
1749 | ||
1750 | if (hlock_class(prev) != hlock_class(next)) | |
1751 | continue; | |
1752 | ||
1753 | /* | |
1754 | * Allow read-after-read recursion of the same | |
1755 | * lock class (i.e. read_lock(lock)+read_lock(lock)): | |
1756 | */ | |
1757 | if ((read == 2) && prev->read) | |
1758 | return 2; | |
1759 | ||
1760 | /* | |
1761 | * We're holding the nest_lock, which serializes this lock's | |
1762 | * nesting behaviour. | |
1763 | */ | |
1764 | if (nest) | |
1765 | return 2; | |
1766 | ||
1767 | return print_deadlock_bug(curr, prev, next); | |
1768 | } | |
1769 | return 1; | |
1770 | } | |
1771 | ||
1772 | /* | |
1773 | * There was a chain-cache miss, and we are about to add a new dependency | |
1774 | * to a previous lock. We recursively validate the following rules: | |
1775 | * | |
1776 | * - would the adding of the <prev> -> <next> dependency create a | |
1777 | * circular dependency in the graph? [== circular deadlock] | |
1778 | * | |
1779 | * - does the new prev->next dependency connect any hardirq-safe lock | |
1780 | * (in the full backwards-subgraph starting at <prev>) with any | |
1781 | * hardirq-unsafe lock (in the full forwards-subgraph starting at | |
1782 | * <next>)? [== illegal lock inversion with hardirq contexts] | |
1783 | * | |
1784 | * - does the new prev->next dependency connect any softirq-safe lock | |
1785 | * (in the full backwards-subgraph starting at <prev>) with any | |
1786 | * softirq-unsafe lock (in the full forwards-subgraph starting at | |
1787 | * <next>)? [== illegal lock inversion with softirq contexts] | |
1788 | * | |
1789 | * any of these scenarios could lead to a deadlock. | |
1790 | * | |
1791 | * Then if all the validations pass, we add the forwards and backwards | |
1792 | * dependency. | |
1793 | */ | |
1794 | static int | |
1795 | check_prev_add(struct task_struct *curr, struct held_lock *prev, | |
1796 | struct held_lock *next, int distance, int *stack_saved) | |
1797 | { | |
1798 | struct lock_list *entry; | |
1799 | int ret; | |
1800 | struct lock_list this; | |
1801 | struct lock_list *uninitialized_var(target_entry); | |
1802 | /* | |
1803 | * Static variable, serialized by the graph_lock(). | |
1804 | * | |
1805 | * We use this static variable to save the stack trace in case | |
1806 | * we call into this function multiple times due to encountering | |
1807 | * trylocks in the held lock stack. | |
1808 | */ | |
1809 | static struct stack_trace trace; | |
1810 | ||
1811 | /* | |
1812 | * Prove that the new <prev> -> <next> dependency would not | |
1813 | * create a circular dependency in the graph. (We do this by | |
1814 | * forward-recursing into the graph starting at <next>, and | |
1815 | * checking whether we can reach <prev>.) | |
1816 | * | |
1817 | * We are using global variables to control the recursion, to | |
1818 | * keep the stackframe size of the recursive functions low: | |
1819 | */ | |
1820 | this.class = hlock_class(next); | |
1821 | this.parent = NULL; | |
1822 | ret = check_noncircular(&this, hlock_class(prev), &target_entry); | |
1823 | if (unlikely(!ret)) | |
1824 | return print_circular_bug(&this, target_entry, next, prev); | |
1825 | else if (unlikely(ret < 0)) | |
1826 | return print_bfs_bug(ret); | |
1827 | ||
1828 | if (!check_prev_add_irq(curr, prev, next)) | |
1829 | return 0; | |
1830 | ||
1831 | /* | |
1832 | * For recursive read-locks we do all the dependency checks, | |
1833 | * but we dont store read-triggered dependencies (only | |
1834 | * write-triggered dependencies). This ensures that only the | |
1835 | * write-side dependencies matter, and that if for example a | |
1836 | * write-lock never takes any other locks, then the reads are | |
1837 | * equivalent to a NOP. | |
1838 | */ | |
1839 | if (next->read == 2 || prev->read == 2) | |
1840 | return 1; | |
1841 | /* | |
1842 | * Is the <prev> -> <next> dependency already present? | |
1843 | * | |
1844 | * (this may occur even though this is a new chain: consider | |
1845 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 | |
1846 | * chains - the second one will be new, but L1 already has | |
1847 | * L2 added to its dependency list, due to the first chain.) | |
1848 | */ | |
1849 | list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { | |
1850 | if (entry->class == hlock_class(next)) { | |
1851 | if (distance == 1) | |
1852 | entry->distance = 1; | |
1853 | return 2; | |
1854 | } | |
1855 | } | |
1856 | ||
1857 | if (!*stack_saved) { | |
1858 | if (!save_trace(&trace)) | |
1859 | return 0; | |
1860 | *stack_saved = 1; | |
1861 | } | |
1862 | ||
1863 | /* | |
1864 | * Ok, all validations passed, add the new lock | |
1865 | * to the previous lock's dependency list: | |
1866 | */ | |
1867 | ret = add_lock_to_list(hlock_class(prev), hlock_class(next), | |
1868 | &hlock_class(prev)->locks_after, | |
1869 | next->acquire_ip, distance, &trace); | |
1870 | ||
1871 | if (!ret) | |
1872 | return 0; | |
1873 | ||
1874 | ret = add_lock_to_list(hlock_class(next), hlock_class(prev), | |
1875 | &hlock_class(next)->locks_before, | |
1876 | next->acquire_ip, distance, &trace); | |
1877 | if (!ret) | |
1878 | return 0; | |
1879 | ||
1880 | /* | |
1881 | * Debugging printouts: | |
1882 | */ | |
1883 | if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) { | |
1884 | /* We drop graph lock, so another thread can overwrite trace. */ | |
1885 | *stack_saved = 0; | |
1886 | graph_unlock(); | |
1887 | printk("\n new dependency: "); | |
1888 | print_lock_name(hlock_class(prev)); | |
1889 | printk(" => "); | |
1890 | print_lock_name(hlock_class(next)); | |
1891 | printk("\n"); | |
1892 | dump_stack(); | |
1893 | return graph_lock(); | |
1894 | } | |
1895 | return 1; | |
1896 | } | |
1897 | ||
1898 | /* | |
1899 | * Add the dependency to all directly-previous locks that are 'relevant'. | |
1900 | * The ones that are relevant are (in increasing distance from curr): | |
1901 | * all consecutive trylock entries and the final non-trylock entry - or | |
1902 | * the end of this context's lock-chain - whichever comes first. | |
1903 | */ | |
1904 | static int | |
1905 | check_prevs_add(struct task_struct *curr, struct held_lock *next) | |
1906 | { | |
1907 | int depth = curr->lockdep_depth; | |
1908 | int stack_saved = 0; | |
1909 | struct held_lock *hlock; | |
1910 | ||
1911 | /* | |
1912 | * Debugging checks. | |
1913 | * | |
1914 | * Depth must not be zero for a non-head lock: | |
1915 | */ | |
1916 | if (!depth) | |
1917 | goto out_bug; | |
1918 | /* | |
1919 | * At least two relevant locks must exist for this | |
1920 | * to be a head: | |
1921 | */ | |
1922 | if (curr->held_locks[depth].irq_context != | |
1923 | curr->held_locks[depth-1].irq_context) | |
1924 | goto out_bug; | |
1925 | ||
1926 | for (;;) { | |
1927 | int distance = curr->lockdep_depth - depth + 1; | |
1928 | hlock = curr->held_locks + depth - 1; | |
1929 | /* | |
1930 | * Only non-recursive-read entries get new dependencies | |
1931 | * added: | |
1932 | */ | |
1933 | if (hlock->read != 2 && hlock->check) { | |
1934 | if (!check_prev_add(curr, hlock, next, | |
1935 | distance, &stack_saved)) | |
1936 | return 0; | |
1937 | /* | |
1938 | * Stop after the first non-trylock entry, | |
1939 | * as non-trylock entries have added their | |
1940 | * own direct dependencies already, so this | |
1941 | * lock is connected to them indirectly: | |
1942 | */ | |
1943 | if (!hlock->trylock) | |
1944 | break; | |
1945 | } | |
1946 | depth--; | |
1947 | /* | |
1948 | * End of lock-stack? | |
1949 | */ | |
1950 | if (!depth) | |
1951 | break; | |
1952 | /* | |
1953 | * Stop the search if we cross into another context: | |
1954 | */ | |
1955 | if (curr->held_locks[depth].irq_context != | |
1956 | curr->held_locks[depth-1].irq_context) | |
1957 | break; | |
1958 | } | |
1959 | return 1; | |
1960 | out_bug: | |
1961 | if (!debug_locks_off_graph_unlock()) | |
1962 | return 0; | |
1963 | ||
1964 | /* | |
1965 | * Clearly we all shouldn't be here, but since we made it we | |
1966 | * can reliable say we messed up our state. See the above two | |
1967 | * gotos for reasons why we could possibly end up here. | |
1968 | */ | |
1969 | WARN_ON(1); | |
1970 | ||
1971 | return 0; | |
1972 | } | |
1973 | ||
1974 | unsigned long nr_lock_chains; | |
1975 | struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; | |
1976 | int nr_chain_hlocks; | |
1977 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; | |
1978 | ||
1979 | struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) | |
1980 | { | |
1981 | return lock_classes + chain_hlocks[chain->base + i]; | |
1982 | } | |
1983 | ||
1984 | /* | |
1985 | * Look up a dependency chain. If the key is not present yet then | |
1986 | * add it and return 1 - in this case the new dependency chain is | |
1987 | * validated. If the key is already hashed, return 0. | |
1988 | * (On return with 1 graph_lock is held.) | |
1989 | */ | |
1990 | static inline int lookup_chain_cache(struct task_struct *curr, | |
1991 | struct held_lock *hlock, | |
1992 | u64 chain_key) | |
1993 | { | |
1994 | struct lock_class *class = hlock_class(hlock); | |
1995 | struct hlist_head *hash_head = chainhashentry(chain_key); | |
1996 | struct lock_chain *chain; | |
1997 | struct held_lock *hlock_curr; | |
1998 | int i, j; | |
1999 | ||
2000 | /* | |
2001 | * We might need to take the graph lock, ensure we've got IRQs | |
2002 | * disabled to make this an IRQ-safe lock.. for recursion reasons | |
2003 | * lockdep won't complain about its own locking errors. | |
2004 | */ | |
2005 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
2006 | return 0; | |
2007 | /* | |
2008 | * We can walk it lock-free, because entries only get added | |
2009 | * to the hash: | |
2010 | */ | |
2011 | hlist_for_each_entry_rcu(chain, hash_head, entry) { | |
2012 | if (chain->chain_key == chain_key) { | |
2013 | cache_hit: | |
2014 | debug_atomic_inc(chain_lookup_hits); | |
2015 | if (very_verbose(class)) | |
2016 | printk("\nhash chain already cached, key: " | |
2017 | "%016Lx tail class: [%p] %s\n", | |
2018 | (unsigned long long)chain_key, | |
2019 | class->key, class->name); | |
2020 | return 0; | |
2021 | } | |
2022 | } | |
2023 | if (very_verbose(class)) | |
2024 | printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", | |
2025 | (unsigned long long)chain_key, class->key, class->name); | |
2026 | /* | |
2027 | * Allocate a new chain entry from the static array, and add | |
2028 | * it to the hash: | |
2029 | */ | |
2030 | if (!graph_lock()) | |
2031 | return 0; | |
2032 | /* | |
2033 | * We have to walk the chain again locked - to avoid duplicates: | |
2034 | */ | |
2035 | hlist_for_each_entry(chain, hash_head, entry) { | |
2036 | if (chain->chain_key == chain_key) { | |
2037 | graph_unlock(); | |
2038 | goto cache_hit; | |
2039 | } | |
2040 | } | |
2041 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { | |
2042 | if (!debug_locks_off_graph_unlock()) | |
2043 | return 0; | |
2044 | ||
2045 | print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); | |
2046 | dump_stack(); | |
2047 | return 0; | |
2048 | } | |
2049 | chain = lock_chains + nr_lock_chains++; | |
2050 | chain->chain_key = chain_key; | |
2051 | chain->irq_context = hlock->irq_context; | |
2052 | /* Find the first held_lock of current chain */ | |
2053 | for (i = curr->lockdep_depth - 1; i >= 0; i--) { | |
2054 | hlock_curr = curr->held_locks + i; | |
2055 | if (hlock_curr->irq_context != hlock->irq_context) | |
2056 | break; | |
2057 | } | |
2058 | i++; | |
2059 | chain->depth = curr->lockdep_depth + 1 - i; | |
2060 | if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { | |
2061 | chain->base = nr_chain_hlocks; | |
2062 | nr_chain_hlocks += chain->depth; | |
2063 | for (j = 0; j < chain->depth - 1; j++, i++) { | |
2064 | int lock_id = curr->held_locks[i].class_idx - 1; | |
2065 | chain_hlocks[chain->base + j] = lock_id; | |
2066 | } | |
2067 | chain_hlocks[chain->base + j] = class - lock_classes; | |
2068 | } | |
2069 | hlist_add_head_rcu(&chain->entry, hash_head); | |
2070 | debug_atomic_inc(chain_lookup_misses); | |
2071 | inc_chains(); | |
2072 | ||
2073 | return 1; | |
2074 | } | |
2075 | ||
2076 | static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, | |
2077 | struct held_lock *hlock, int chain_head, u64 chain_key) | |
2078 | { | |
2079 | /* | |
2080 | * Trylock needs to maintain the stack of held locks, but it | |
2081 | * does not add new dependencies, because trylock can be done | |
2082 | * in any order. | |
2083 | * | |
2084 | * We look up the chain_key and do the O(N^2) check and update of | |
2085 | * the dependencies only if this is a new dependency chain. | |
2086 | * (If lookup_chain_cache() returns with 1 it acquires | |
2087 | * graph_lock for us) | |
2088 | */ | |
2089 | if (!hlock->trylock && hlock->check && | |
2090 | lookup_chain_cache(curr, hlock, chain_key)) { | |
2091 | /* | |
2092 | * Check whether last held lock: | |
2093 | * | |
2094 | * - is irq-safe, if this lock is irq-unsafe | |
2095 | * - is softirq-safe, if this lock is hardirq-unsafe | |
2096 | * | |
2097 | * And check whether the new lock's dependency graph | |
2098 | * could lead back to the previous lock. | |
2099 | * | |
2100 | * any of these scenarios could lead to a deadlock. If | |
2101 | * All validations | |
2102 | */ | |
2103 | int ret = check_deadlock(curr, hlock, lock, hlock->read); | |
2104 | ||
2105 | if (!ret) | |
2106 | return 0; | |
2107 | /* | |
2108 | * Mark recursive read, as we jump over it when | |
2109 | * building dependencies (just like we jump over | |
2110 | * trylock entries): | |
2111 | */ | |
2112 | if (ret == 2) | |
2113 | hlock->read = 2; | |
2114 | /* | |
2115 | * Add dependency only if this lock is not the head | |
2116 | * of the chain, and if it's not a secondary read-lock: | |
2117 | */ | |
2118 | if (!chain_head && ret != 2) | |
2119 | if (!check_prevs_add(curr, hlock)) | |
2120 | return 0; | |
2121 | graph_unlock(); | |
2122 | } else | |
2123 | /* after lookup_chain_cache(): */ | |
2124 | if (unlikely(!debug_locks)) | |
2125 | return 0; | |
2126 | ||
2127 | return 1; | |
2128 | } | |
2129 | #else | |
2130 | static inline int validate_chain(struct task_struct *curr, | |
2131 | struct lockdep_map *lock, struct held_lock *hlock, | |
2132 | int chain_head, u64 chain_key) | |
2133 | { | |
2134 | return 1; | |
2135 | } | |
2136 | #endif | |
2137 | ||
2138 | /* | |
2139 | * We are building curr_chain_key incrementally, so double-check | |
2140 | * it from scratch, to make sure that it's done correctly: | |
2141 | */ | |
2142 | static void check_chain_key(struct task_struct *curr) | |
2143 | { | |
2144 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2145 | struct held_lock *hlock, *prev_hlock = NULL; | |
2146 | unsigned int i, id; | |
2147 | u64 chain_key = 0; | |
2148 | ||
2149 | for (i = 0; i < curr->lockdep_depth; i++) { | |
2150 | hlock = curr->held_locks + i; | |
2151 | if (chain_key != hlock->prev_chain_key) { | |
2152 | debug_locks_off(); | |
2153 | /* | |
2154 | * We got mighty confused, our chain keys don't match | |
2155 | * with what we expect, someone trample on our task state? | |
2156 | */ | |
2157 | WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", | |
2158 | curr->lockdep_depth, i, | |
2159 | (unsigned long long)chain_key, | |
2160 | (unsigned long long)hlock->prev_chain_key); | |
2161 | return; | |
2162 | } | |
2163 | id = hlock->class_idx - 1; | |
2164 | /* | |
2165 | * Whoops ran out of static storage again? | |
2166 | */ | |
2167 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) | |
2168 | return; | |
2169 | ||
2170 | if (prev_hlock && (prev_hlock->irq_context != | |
2171 | hlock->irq_context)) | |
2172 | chain_key = 0; | |
2173 | chain_key = iterate_chain_key(chain_key, id); | |
2174 | prev_hlock = hlock; | |
2175 | } | |
2176 | if (chain_key != curr->curr_chain_key) { | |
2177 | debug_locks_off(); | |
2178 | /* | |
2179 | * More smoking hash instead of calculating it, damn see these | |
2180 | * numbers float.. I bet that a pink elephant stepped on my memory. | |
2181 | */ | |
2182 | WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", | |
2183 | curr->lockdep_depth, i, | |
2184 | (unsigned long long)chain_key, | |
2185 | (unsigned long long)curr->curr_chain_key); | |
2186 | } | |
2187 | #endif | |
2188 | } | |
2189 | ||
2190 | static void | |
2191 | print_usage_bug_scenario(struct held_lock *lock) | |
2192 | { | |
2193 | struct lock_class *class = hlock_class(lock); | |
2194 | ||
2195 | printk(" Possible unsafe locking scenario:\n\n"); | |
2196 | printk(" CPU0\n"); | |
2197 | printk(" ----\n"); | |
2198 | printk(" lock("); | |
2199 | __print_lock_name(class); | |
2200 | printk(");\n"); | |
2201 | printk(" <Interrupt>\n"); | |
2202 | printk(" lock("); | |
2203 | __print_lock_name(class); | |
2204 | printk(");\n"); | |
2205 | printk("\n *** DEADLOCK ***\n\n"); | |
2206 | } | |
2207 | ||
2208 | static int | |
2209 | print_usage_bug(struct task_struct *curr, struct held_lock *this, | |
2210 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) | |
2211 | { | |
2212 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) | |
2213 | return 0; | |
2214 | ||
2215 | printk("\n"); | |
2216 | printk("=================================\n"); | |
2217 | printk("[ INFO: inconsistent lock state ]\n"); | |
2218 | print_kernel_ident(); | |
2219 | printk("---------------------------------\n"); | |
2220 | ||
2221 | printk("inconsistent {%s} -> {%s} usage.\n", | |
2222 | usage_str[prev_bit], usage_str[new_bit]); | |
2223 | ||
2224 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", | |
2225 | curr->comm, task_pid_nr(curr), | |
2226 | trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, | |
2227 | trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, | |
2228 | trace_hardirqs_enabled(curr), | |
2229 | trace_softirqs_enabled(curr)); | |
2230 | print_lock(this); | |
2231 | ||
2232 | printk("{%s} state was registered at:\n", usage_str[prev_bit]); | |
2233 | print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1); | |
2234 | ||
2235 | print_irqtrace_events(curr); | |
2236 | printk("\nother info that might help us debug this:\n"); | |
2237 | print_usage_bug_scenario(this); | |
2238 | ||
2239 | lockdep_print_held_locks(curr); | |
2240 | ||
2241 | printk("\nstack backtrace:\n"); | |
2242 | dump_stack(); | |
2243 | ||
2244 | return 0; | |
2245 | } | |
2246 | ||
2247 | /* | |
2248 | * Print out an error if an invalid bit is set: | |
2249 | */ | |
2250 | static inline int | |
2251 | valid_state(struct task_struct *curr, struct held_lock *this, | |
2252 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) | |
2253 | { | |
2254 | if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) | |
2255 | return print_usage_bug(curr, this, bad_bit, new_bit); | |
2256 | return 1; | |
2257 | } | |
2258 | ||
2259 | static int mark_lock(struct task_struct *curr, struct held_lock *this, | |
2260 | enum lock_usage_bit new_bit); | |
2261 | ||
2262 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) | |
2263 | ||
2264 | /* | |
2265 | * print irq inversion bug: | |
2266 | */ | |
2267 | static int | |
2268 | print_irq_inversion_bug(struct task_struct *curr, | |
2269 | struct lock_list *root, struct lock_list *other, | |
2270 | struct held_lock *this, int forwards, | |
2271 | const char *irqclass) | |
2272 | { | |
2273 | struct lock_list *entry = other; | |
2274 | struct lock_list *middle = NULL; | |
2275 | int depth; | |
2276 | ||
2277 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) | |
2278 | return 0; | |
2279 | ||
2280 | printk("\n"); | |
2281 | printk("=========================================================\n"); | |
2282 | printk("[ INFO: possible irq lock inversion dependency detected ]\n"); | |
2283 | print_kernel_ident(); | |
2284 | printk("---------------------------------------------------------\n"); | |
2285 | printk("%s/%d just changed the state of lock:\n", | |
2286 | curr->comm, task_pid_nr(curr)); | |
2287 | print_lock(this); | |
2288 | if (forwards) | |
2289 | printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass); | |
2290 | else | |
2291 | printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); | |
2292 | print_lock_name(other->class); | |
2293 | printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); | |
2294 | ||
2295 | printk("\nother info that might help us debug this:\n"); | |
2296 | ||
2297 | /* Find a middle lock (if one exists) */ | |
2298 | depth = get_lock_depth(other); | |
2299 | do { | |
2300 | if (depth == 0 && (entry != root)) { | |
2301 | printk("lockdep:%s bad path found in chain graph\n", __func__); | |
2302 | break; | |
2303 | } | |
2304 | middle = entry; | |
2305 | entry = get_lock_parent(entry); | |
2306 | depth--; | |
2307 | } while (entry && entry != root && (depth >= 0)); | |
2308 | if (forwards) | |
2309 | print_irq_lock_scenario(root, other, | |
2310 | middle ? middle->class : root->class, other->class); | |
2311 | else | |
2312 | print_irq_lock_scenario(other, root, | |
2313 | middle ? middle->class : other->class, root->class); | |
2314 | ||
2315 | lockdep_print_held_locks(curr); | |
2316 | ||
2317 | printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); | |
2318 | if (!save_trace(&root->trace)) | |
2319 | return 0; | |
2320 | print_shortest_lock_dependencies(other, root); | |
2321 | ||
2322 | printk("\nstack backtrace:\n"); | |
2323 | dump_stack(); | |
2324 | ||
2325 | return 0; | |
2326 | } | |
2327 | ||
2328 | /* | |
2329 | * Prove that in the forwards-direction subgraph starting at <this> | |
2330 | * there is no lock matching <mask>: | |
2331 | */ | |
2332 | static int | |
2333 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, | |
2334 | enum lock_usage_bit bit, const char *irqclass) | |
2335 | { | |
2336 | int ret; | |
2337 | struct lock_list root; | |
2338 | struct lock_list *uninitialized_var(target_entry); | |
2339 | ||
2340 | root.parent = NULL; | |
2341 | root.class = hlock_class(this); | |
2342 | ret = find_usage_forwards(&root, bit, &target_entry); | |
2343 | if (ret < 0) | |
2344 | return print_bfs_bug(ret); | |
2345 | if (ret == 1) | |
2346 | return ret; | |
2347 | ||
2348 | return print_irq_inversion_bug(curr, &root, target_entry, | |
2349 | this, 1, irqclass); | |
2350 | } | |
2351 | ||
2352 | /* | |
2353 | * Prove that in the backwards-direction subgraph starting at <this> | |
2354 | * there is no lock matching <mask>: | |
2355 | */ | |
2356 | static int | |
2357 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, | |
2358 | enum lock_usage_bit bit, const char *irqclass) | |
2359 | { | |
2360 | int ret; | |
2361 | struct lock_list root; | |
2362 | struct lock_list *uninitialized_var(target_entry); | |
2363 | ||
2364 | root.parent = NULL; | |
2365 | root.class = hlock_class(this); | |
2366 | ret = find_usage_backwards(&root, bit, &target_entry); | |
2367 | if (ret < 0) | |
2368 | return print_bfs_bug(ret); | |
2369 | if (ret == 1) | |
2370 | return ret; | |
2371 | ||
2372 | return print_irq_inversion_bug(curr, &root, target_entry, | |
2373 | this, 0, irqclass); | |
2374 | } | |
2375 | ||
2376 | void print_irqtrace_events(struct task_struct *curr) | |
2377 | { | |
2378 | printk("irq event stamp: %u\n", curr->irq_events); | |
2379 | printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event); | |
2380 | print_ip_sym(curr->hardirq_enable_ip); | |
2381 | printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event); | |
2382 | print_ip_sym(curr->hardirq_disable_ip); | |
2383 | printk("softirqs last enabled at (%u): ", curr->softirq_enable_event); | |
2384 | print_ip_sym(curr->softirq_enable_ip); | |
2385 | printk("softirqs last disabled at (%u): ", curr->softirq_disable_event); | |
2386 | print_ip_sym(curr->softirq_disable_ip); | |
2387 | } | |
2388 | ||
2389 | static int HARDIRQ_verbose(struct lock_class *class) | |
2390 | { | |
2391 | #if HARDIRQ_VERBOSE | |
2392 | return class_filter(class); | |
2393 | #endif | |
2394 | return 0; | |
2395 | } | |
2396 | ||
2397 | static int SOFTIRQ_verbose(struct lock_class *class) | |
2398 | { | |
2399 | #if SOFTIRQ_VERBOSE | |
2400 | return class_filter(class); | |
2401 | #endif | |
2402 | return 0; | |
2403 | } | |
2404 | ||
2405 | static int RECLAIM_FS_verbose(struct lock_class *class) | |
2406 | { | |
2407 | #if RECLAIM_VERBOSE | |
2408 | return class_filter(class); | |
2409 | #endif | |
2410 | return 0; | |
2411 | } | |
2412 | ||
2413 | #define STRICT_READ_CHECKS 1 | |
2414 | ||
2415 | static int (*state_verbose_f[])(struct lock_class *class) = { | |
2416 | #define LOCKDEP_STATE(__STATE) \ | |
2417 | __STATE##_verbose, | |
2418 | #include "lockdep_states.h" | |
2419 | #undef LOCKDEP_STATE | |
2420 | }; | |
2421 | ||
2422 | static inline int state_verbose(enum lock_usage_bit bit, | |
2423 | struct lock_class *class) | |
2424 | { | |
2425 | return state_verbose_f[bit >> 2](class); | |
2426 | } | |
2427 | ||
2428 | typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, | |
2429 | enum lock_usage_bit bit, const char *name); | |
2430 | ||
2431 | static int | |
2432 | mark_lock_irq(struct task_struct *curr, struct held_lock *this, | |
2433 | enum lock_usage_bit new_bit) | |
2434 | { | |
2435 | int excl_bit = exclusive_bit(new_bit); | |
2436 | int read = new_bit & 1; | |
2437 | int dir = new_bit & 2; | |
2438 | ||
2439 | /* | |
2440 | * mark USED_IN has to look forwards -- to ensure no dependency | |
2441 | * has ENABLED state, which would allow recursion deadlocks. | |
2442 | * | |
2443 | * mark ENABLED has to look backwards -- to ensure no dependee | |
2444 | * has USED_IN state, which, again, would allow recursion deadlocks. | |
2445 | */ | |
2446 | check_usage_f usage = dir ? | |
2447 | check_usage_backwards : check_usage_forwards; | |
2448 | ||
2449 | /* | |
2450 | * Validate that this particular lock does not have conflicting | |
2451 | * usage states. | |
2452 | */ | |
2453 | if (!valid_state(curr, this, new_bit, excl_bit)) | |
2454 | return 0; | |
2455 | ||
2456 | /* | |
2457 | * Validate that the lock dependencies don't have conflicting usage | |
2458 | * states. | |
2459 | */ | |
2460 | if ((!read || !dir || STRICT_READ_CHECKS) && | |
2461 | !usage(curr, this, excl_bit, state_name(new_bit & ~1))) | |
2462 | return 0; | |
2463 | ||
2464 | /* | |
2465 | * Check for read in write conflicts | |
2466 | */ | |
2467 | if (!read) { | |
2468 | if (!valid_state(curr, this, new_bit, excl_bit + 1)) | |
2469 | return 0; | |
2470 | ||
2471 | if (STRICT_READ_CHECKS && | |
2472 | !usage(curr, this, excl_bit + 1, | |
2473 | state_name(new_bit + 1))) | |
2474 | return 0; | |
2475 | } | |
2476 | ||
2477 | if (state_verbose(new_bit, hlock_class(this))) | |
2478 | return 2; | |
2479 | ||
2480 | return 1; | |
2481 | } | |
2482 | ||
2483 | enum mark_type { | |
2484 | #define LOCKDEP_STATE(__STATE) __STATE, | |
2485 | #include "lockdep_states.h" | |
2486 | #undef LOCKDEP_STATE | |
2487 | }; | |
2488 | ||
2489 | /* | |
2490 | * Mark all held locks with a usage bit: | |
2491 | */ | |
2492 | static int | |
2493 | mark_held_locks(struct task_struct *curr, enum mark_type mark) | |
2494 | { | |
2495 | enum lock_usage_bit usage_bit; | |
2496 | struct held_lock *hlock; | |
2497 | int i; | |
2498 | ||
2499 | for (i = 0; i < curr->lockdep_depth; i++) { | |
2500 | hlock = curr->held_locks + i; | |
2501 | ||
2502 | usage_bit = 2 + (mark << 2); /* ENABLED */ | |
2503 | if (hlock->read) | |
2504 | usage_bit += 1; /* READ */ | |
2505 | ||
2506 | BUG_ON(usage_bit >= LOCK_USAGE_STATES); | |
2507 | ||
2508 | if (!hlock->check) | |
2509 | continue; | |
2510 | ||
2511 | if (!mark_lock(curr, hlock, usage_bit)) | |
2512 | return 0; | |
2513 | } | |
2514 | ||
2515 | return 1; | |
2516 | } | |
2517 | ||
2518 | /* | |
2519 | * Hardirqs will be enabled: | |
2520 | */ | |
2521 | static void __trace_hardirqs_on_caller(unsigned long ip) | |
2522 | { | |
2523 | struct task_struct *curr = current; | |
2524 | ||
2525 | /* we'll do an OFF -> ON transition: */ | |
2526 | curr->hardirqs_enabled = 1; | |
2527 | ||
2528 | /* | |
2529 | * We are going to turn hardirqs on, so set the | |
2530 | * usage bit for all held locks: | |
2531 | */ | |
2532 | if (!mark_held_locks(curr, HARDIRQ)) | |
2533 | return; | |
2534 | /* | |
2535 | * If we have softirqs enabled, then set the usage | |
2536 | * bit for all held locks. (disabled hardirqs prevented | |
2537 | * this bit from being set before) | |
2538 | */ | |
2539 | if (curr->softirqs_enabled) | |
2540 | if (!mark_held_locks(curr, SOFTIRQ)) | |
2541 | return; | |
2542 | ||
2543 | curr->hardirq_enable_ip = ip; | |
2544 | curr->hardirq_enable_event = ++curr->irq_events; | |
2545 | debug_atomic_inc(hardirqs_on_events); | |
2546 | } | |
2547 | ||
2548 | __visible void trace_hardirqs_on_caller(unsigned long ip) | |
2549 | { | |
2550 | time_hardirqs_on(CALLER_ADDR0, ip); | |
2551 | ||
2552 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
2553 | return; | |
2554 | ||
2555 | if (unlikely(current->hardirqs_enabled)) { | |
2556 | /* | |
2557 | * Neither irq nor preemption are disabled here | |
2558 | * so this is racy by nature but losing one hit | |
2559 | * in a stat is not a big deal. | |
2560 | */ | |
2561 | __debug_atomic_inc(redundant_hardirqs_on); | |
2562 | return; | |
2563 | } | |
2564 | ||
2565 | /* | |
2566 | * We're enabling irqs and according to our state above irqs weren't | |
2567 | * already enabled, yet we find the hardware thinks they are in fact | |
2568 | * enabled.. someone messed up their IRQ state tracing. | |
2569 | */ | |
2570 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
2571 | return; | |
2572 | ||
2573 | /* | |
2574 | * See the fine text that goes along with this variable definition. | |
2575 | */ | |
2576 | if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) | |
2577 | return; | |
2578 | ||
2579 | /* | |
2580 | * Can't allow enabling interrupts while in an interrupt handler, | |
2581 | * that's general bad form and such. Recursion, limited stack etc.. | |
2582 | */ | |
2583 | if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) | |
2584 | return; | |
2585 | ||
2586 | current->lockdep_recursion = 1; | |
2587 | __trace_hardirqs_on_caller(ip); | |
2588 | current->lockdep_recursion = 0; | |
2589 | } | |
2590 | EXPORT_SYMBOL(trace_hardirqs_on_caller); | |
2591 | ||
2592 | void trace_hardirqs_on(void) | |
2593 | { | |
2594 | trace_hardirqs_on_caller(CALLER_ADDR0); | |
2595 | } | |
2596 | EXPORT_SYMBOL(trace_hardirqs_on); | |
2597 | ||
2598 | /* | |
2599 | * Hardirqs were disabled: | |
2600 | */ | |
2601 | __visible void trace_hardirqs_off_caller(unsigned long ip) | |
2602 | { | |
2603 | struct task_struct *curr = current; | |
2604 | ||
2605 | time_hardirqs_off(CALLER_ADDR0, ip); | |
2606 | ||
2607 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
2608 | return; | |
2609 | ||
2610 | /* | |
2611 | * So we're supposed to get called after you mask local IRQs, but for | |
2612 | * some reason the hardware doesn't quite think you did a proper job. | |
2613 | */ | |
2614 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
2615 | return; | |
2616 | ||
2617 | if (curr->hardirqs_enabled) { | |
2618 | /* | |
2619 | * We have done an ON -> OFF transition: | |
2620 | */ | |
2621 | curr->hardirqs_enabled = 0; | |
2622 | curr->hardirq_disable_ip = ip; | |
2623 | curr->hardirq_disable_event = ++curr->irq_events; | |
2624 | debug_atomic_inc(hardirqs_off_events); | |
2625 | } else | |
2626 | debug_atomic_inc(redundant_hardirqs_off); | |
2627 | } | |
2628 | EXPORT_SYMBOL(trace_hardirqs_off_caller); | |
2629 | ||
2630 | void trace_hardirqs_off(void) | |
2631 | { | |
2632 | trace_hardirqs_off_caller(CALLER_ADDR0); | |
2633 | } | |
2634 | EXPORT_SYMBOL(trace_hardirqs_off); | |
2635 | ||
2636 | /* | |
2637 | * Softirqs will be enabled: | |
2638 | */ | |
2639 | void trace_softirqs_on(unsigned long ip) | |
2640 | { | |
2641 | struct task_struct *curr = current; | |
2642 | ||
2643 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
2644 | return; | |
2645 | ||
2646 | /* | |
2647 | * We fancy IRQs being disabled here, see softirq.c, avoids | |
2648 | * funny state and nesting things. | |
2649 | */ | |
2650 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
2651 | return; | |
2652 | ||
2653 | if (curr->softirqs_enabled) { | |
2654 | debug_atomic_inc(redundant_softirqs_on); | |
2655 | return; | |
2656 | } | |
2657 | ||
2658 | current->lockdep_recursion = 1; | |
2659 | /* | |
2660 | * We'll do an OFF -> ON transition: | |
2661 | */ | |
2662 | curr->softirqs_enabled = 1; | |
2663 | curr->softirq_enable_ip = ip; | |
2664 | curr->softirq_enable_event = ++curr->irq_events; | |
2665 | debug_atomic_inc(softirqs_on_events); | |
2666 | /* | |
2667 | * We are going to turn softirqs on, so set the | |
2668 | * usage bit for all held locks, if hardirqs are | |
2669 | * enabled too: | |
2670 | */ | |
2671 | if (curr->hardirqs_enabled) | |
2672 | mark_held_locks(curr, SOFTIRQ); | |
2673 | current->lockdep_recursion = 0; | |
2674 | } | |
2675 | ||
2676 | /* | |
2677 | * Softirqs were disabled: | |
2678 | */ | |
2679 | void trace_softirqs_off(unsigned long ip) | |
2680 | { | |
2681 | struct task_struct *curr = current; | |
2682 | ||
2683 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
2684 | return; | |
2685 | ||
2686 | /* | |
2687 | * We fancy IRQs being disabled here, see softirq.c | |
2688 | */ | |
2689 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
2690 | return; | |
2691 | ||
2692 | if (curr->softirqs_enabled) { | |
2693 | /* | |
2694 | * We have done an ON -> OFF transition: | |
2695 | */ | |
2696 | curr->softirqs_enabled = 0; | |
2697 | curr->softirq_disable_ip = ip; | |
2698 | curr->softirq_disable_event = ++curr->irq_events; | |
2699 | debug_atomic_inc(softirqs_off_events); | |
2700 | /* | |
2701 | * Whoops, we wanted softirqs off, so why aren't they? | |
2702 | */ | |
2703 | DEBUG_LOCKS_WARN_ON(!softirq_count()); | |
2704 | } else | |
2705 | debug_atomic_inc(redundant_softirqs_off); | |
2706 | } | |
2707 | ||
2708 | static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags) | |
2709 | { | |
2710 | struct task_struct *curr = current; | |
2711 | ||
2712 | if (unlikely(!debug_locks)) | |
2713 | return; | |
2714 | ||
2715 | /* no reclaim without waiting on it */ | |
2716 | if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) | |
2717 | return; | |
2718 | ||
2719 | /* this guy won't enter reclaim */ | |
2720 | if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC)) | |
2721 | return; | |
2722 | ||
2723 | /* We're only interested __GFP_FS allocations for now */ | |
2724 | if (!(gfp_mask & __GFP_FS)) | |
2725 | return; | |
2726 | ||
2727 | /* | |
2728 | * Oi! Can't be having __GFP_FS allocations with IRQs disabled. | |
2729 | */ | |
2730 | if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))) | |
2731 | return; | |
2732 | ||
2733 | mark_held_locks(curr, RECLAIM_FS); | |
2734 | } | |
2735 | ||
2736 | static void check_flags(unsigned long flags); | |
2737 | ||
2738 | void lockdep_trace_alloc(gfp_t gfp_mask) | |
2739 | { | |
2740 | unsigned long flags; | |
2741 | ||
2742 | if (unlikely(current->lockdep_recursion)) | |
2743 | return; | |
2744 | ||
2745 | raw_local_irq_save(flags); | |
2746 | check_flags(flags); | |
2747 | current->lockdep_recursion = 1; | |
2748 | __lockdep_trace_alloc(gfp_mask, flags); | |
2749 | current->lockdep_recursion = 0; | |
2750 | raw_local_irq_restore(flags); | |
2751 | } | |
2752 | ||
2753 | static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) | |
2754 | { | |
2755 | /* | |
2756 | * If non-trylock use in a hardirq or softirq context, then | |
2757 | * mark the lock as used in these contexts: | |
2758 | */ | |
2759 | if (!hlock->trylock) { | |
2760 | if (hlock->read) { | |
2761 | if (curr->hardirq_context) | |
2762 | if (!mark_lock(curr, hlock, | |
2763 | LOCK_USED_IN_HARDIRQ_READ)) | |
2764 | return 0; | |
2765 | if (curr->softirq_context) | |
2766 | if (!mark_lock(curr, hlock, | |
2767 | LOCK_USED_IN_SOFTIRQ_READ)) | |
2768 | return 0; | |
2769 | } else { | |
2770 | if (curr->hardirq_context) | |
2771 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) | |
2772 | return 0; | |
2773 | if (curr->softirq_context) | |
2774 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) | |
2775 | return 0; | |
2776 | } | |
2777 | } | |
2778 | if (!hlock->hardirqs_off) { | |
2779 | if (hlock->read) { | |
2780 | if (!mark_lock(curr, hlock, | |
2781 | LOCK_ENABLED_HARDIRQ_READ)) | |
2782 | return 0; | |
2783 | if (curr->softirqs_enabled) | |
2784 | if (!mark_lock(curr, hlock, | |
2785 | LOCK_ENABLED_SOFTIRQ_READ)) | |
2786 | return 0; | |
2787 | } else { | |
2788 | if (!mark_lock(curr, hlock, | |
2789 | LOCK_ENABLED_HARDIRQ)) | |
2790 | return 0; | |
2791 | if (curr->softirqs_enabled) | |
2792 | if (!mark_lock(curr, hlock, | |
2793 | LOCK_ENABLED_SOFTIRQ)) | |
2794 | return 0; | |
2795 | } | |
2796 | } | |
2797 | ||
2798 | /* | |
2799 | * We reuse the irq context infrastructure more broadly as a general | |
2800 | * context checking code. This tests GFP_FS recursion (a lock taken | |
2801 | * during reclaim for a GFP_FS allocation is held over a GFP_FS | |
2802 | * allocation). | |
2803 | */ | |
2804 | if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) { | |
2805 | if (hlock->read) { | |
2806 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ)) | |
2807 | return 0; | |
2808 | } else { | |
2809 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS)) | |
2810 | return 0; | |
2811 | } | |
2812 | } | |
2813 | ||
2814 | return 1; | |
2815 | } | |
2816 | ||
2817 | static int separate_irq_context(struct task_struct *curr, | |
2818 | struct held_lock *hlock) | |
2819 | { | |
2820 | unsigned int depth = curr->lockdep_depth; | |
2821 | ||
2822 | /* | |
2823 | * Keep track of points where we cross into an interrupt context: | |
2824 | */ | |
2825 | hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) + | |
2826 | curr->softirq_context; | |
2827 | if (depth) { | |
2828 | struct held_lock *prev_hlock; | |
2829 | ||
2830 | prev_hlock = curr->held_locks + depth-1; | |
2831 | /* | |
2832 | * If we cross into another context, reset the | |
2833 | * hash key (this also prevents the checking and the | |
2834 | * adding of the dependency to 'prev'): | |
2835 | */ | |
2836 | if (prev_hlock->irq_context != hlock->irq_context) | |
2837 | return 1; | |
2838 | } | |
2839 | return 0; | |
2840 | } | |
2841 | ||
2842 | #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ | |
2843 | ||
2844 | static inline | |
2845 | int mark_lock_irq(struct task_struct *curr, struct held_lock *this, | |
2846 | enum lock_usage_bit new_bit) | |
2847 | { | |
2848 | WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */ | |
2849 | return 1; | |
2850 | } | |
2851 | ||
2852 | static inline int mark_irqflags(struct task_struct *curr, | |
2853 | struct held_lock *hlock) | |
2854 | { | |
2855 | return 1; | |
2856 | } | |
2857 | ||
2858 | static inline int separate_irq_context(struct task_struct *curr, | |
2859 | struct held_lock *hlock) | |
2860 | { | |
2861 | return 0; | |
2862 | } | |
2863 | ||
2864 | void lockdep_trace_alloc(gfp_t gfp_mask) | |
2865 | { | |
2866 | } | |
2867 | ||
2868 | #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ | |
2869 | ||
2870 | /* | |
2871 | * Mark a lock with a usage bit, and validate the state transition: | |
2872 | */ | |
2873 | static int mark_lock(struct task_struct *curr, struct held_lock *this, | |
2874 | enum lock_usage_bit new_bit) | |
2875 | { | |
2876 | unsigned int new_mask = 1 << new_bit, ret = 1; | |
2877 | ||
2878 | /* | |
2879 | * If already set then do not dirty the cacheline, | |
2880 | * nor do any checks: | |
2881 | */ | |
2882 | if (likely(hlock_class(this)->usage_mask & new_mask)) | |
2883 | return 1; | |
2884 | ||
2885 | if (!graph_lock()) | |
2886 | return 0; | |
2887 | /* | |
2888 | * Make sure we didn't race: | |
2889 | */ | |
2890 | if (unlikely(hlock_class(this)->usage_mask & new_mask)) { | |
2891 | graph_unlock(); | |
2892 | return 1; | |
2893 | } | |
2894 | ||
2895 | hlock_class(this)->usage_mask |= new_mask; | |
2896 | ||
2897 | if (!save_trace(hlock_class(this)->usage_traces + new_bit)) | |
2898 | return 0; | |
2899 | ||
2900 | switch (new_bit) { | |
2901 | #define LOCKDEP_STATE(__STATE) \ | |
2902 | case LOCK_USED_IN_##__STATE: \ | |
2903 | case LOCK_USED_IN_##__STATE##_READ: \ | |
2904 | case LOCK_ENABLED_##__STATE: \ | |
2905 | case LOCK_ENABLED_##__STATE##_READ: | |
2906 | #include "lockdep_states.h" | |
2907 | #undef LOCKDEP_STATE | |
2908 | ret = mark_lock_irq(curr, this, new_bit); | |
2909 | if (!ret) | |
2910 | return 0; | |
2911 | break; | |
2912 | case LOCK_USED: | |
2913 | debug_atomic_dec(nr_unused_locks); | |
2914 | break; | |
2915 | default: | |
2916 | if (!debug_locks_off_graph_unlock()) | |
2917 | return 0; | |
2918 | WARN_ON(1); | |
2919 | return 0; | |
2920 | } | |
2921 | ||
2922 | graph_unlock(); | |
2923 | ||
2924 | /* | |
2925 | * We must printk outside of the graph_lock: | |
2926 | */ | |
2927 | if (ret == 2) { | |
2928 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); | |
2929 | print_lock(this); | |
2930 | print_irqtrace_events(curr); | |
2931 | dump_stack(); | |
2932 | } | |
2933 | ||
2934 | return ret; | |
2935 | } | |
2936 | ||
2937 | /* | |
2938 | * Initialize a lock instance's lock-class mapping info: | |
2939 | */ | |
2940 | void lockdep_init_map(struct lockdep_map *lock, const char *name, | |
2941 | struct lock_class_key *key, int subclass) | |
2942 | { | |
2943 | int i; | |
2944 | ||
2945 | kmemcheck_mark_initialized(lock, sizeof(*lock)); | |
2946 | ||
2947 | for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) | |
2948 | lock->class_cache[i] = NULL; | |
2949 | ||
2950 | #ifdef CONFIG_LOCK_STAT | |
2951 | lock->cpu = raw_smp_processor_id(); | |
2952 | #endif | |
2953 | ||
2954 | /* | |
2955 | * Can't be having no nameless bastards around this place! | |
2956 | */ | |
2957 | if (DEBUG_LOCKS_WARN_ON(!name)) { | |
2958 | lock->name = "NULL"; | |
2959 | return; | |
2960 | } | |
2961 | ||
2962 | lock->name = name; | |
2963 | ||
2964 | /* | |
2965 | * No key, no joy, we need to hash something. | |
2966 | */ | |
2967 | if (DEBUG_LOCKS_WARN_ON(!key)) | |
2968 | return; | |
2969 | /* | |
2970 | * Sanity check, the lock-class key must be persistent: | |
2971 | */ | |
2972 | if (!static_obj(key)) { | |
2973 | printk("BUG: key %p not in .data!\n", key); | |
2974 | /* | |
2975 | * What it says above ^^^^^, I suggest you read it. | |
2976 | */ | |
2977 | DEBUG_LOCKS_WARN_ON(1); | |
2978 | return; | |
2979 | } | |
2980 | lock->key = key; | |
2981 | ||
2982 | if (unlikely(!debug_locks)) | |
2983 | return; | |
2984 | ||
2985 | if (subclass) { | |
2986 | unsigned long flags; | |
2987 | ||
2988 | if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion)) | |
2989 | return; | |
2990 | ||
2991 | raw_local_irq_save(flags); | |
2992 | current->lockdep_recursion = 1; | |
2993 | register_lock_class(lock, subclass, 1); | |
2994 | current->lockdep_recursion = 0; | |
2995 | raw_local_irq_restore(flags); | |
2996 | } | |
2997 | } | |
2998 | EXPORT_SYMBOL_GPL(lockdep_init_map); | |
2999 | ||
3000 | struct lock_class_key __lockdep_no_validate__; | |
3001 | EXPORT_SYMBOL_GPL(__lockdep_no_validate__); | |
3002 | ||
3003 | static int | |
3004 | print_lock_nested_lock_not_held(struct task_struct *curr, | |
3005 | struct held_lock *hlock, | |
3006 | unsigned long ip) | |
3007 | { | |
3008 | if (!debug_locks_off()) | |
3009 | return 0; | |
3010 | if (debug_locks_silent) | |
3011 | return 0; | |
3012 | ||
3013 | printk("\n"); | |
3014 | printk("==================================\n"); | |
3015 | printk("[ BUG: Nested lock was not taken ]\n"); | |
3016 | print_kernel_ident(); | |
3017 | printk("----------------------------------\n"); | |
3018 | ||
3019 | printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr)); | |
3020 | print_lock(hlock); | |
3021 | ||
3022 | printk("\nbut this task is not holding:\n"); | |
3023 | printk("%s\n", hlock->nest_lock->name); | |
3024 | ||
3025 | printk("\nstack backtrace:\n"); | |
3026 | dump_stack(); | |
3027 | ||
3028 | printk("\nother info that might help us debug this:\n"); | |
3029 | lockdep_print_held_locks(curr); | |
3030 | ||
3031 | printk("\nstack backtrace:\n"); | |
3032 | dump_stack(); | |
3033 | ||
3034 | return 0; | |
3035 | } | |
3036 | ||
3037 | static int __lock_is_held(struct lockdep_map *lock); | |
3038 | ||
3039 | /* | |
3040 | * This gets called for every mutex_lock*()/spin_lock*() operation. | |
3041 | * We maintain the dependency maps and validate the locking attempt: | |
3042 | */ | |
3043 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
3044 | int trylock, int read, int check, int hardirqs_off, | |
3045 | struct lockdep_map *nest_lock, unsigned long ip, | |
3046 | int references, int pin_count) | |
3047 | { | |
3048 | struct task_struct *curr = current; | |
3049 | struct lock_class *class = NULL; | |
3050 | struct held_lock *hlock; | |
3051 | unsigned int depth, id; | |
3052 | int chain_head = 0; | |
3053 | int class_idx; | |
3054 | u64 chain_key; | |
3055 | ||
3056 | if (unlikely(!debug_locks)) | |
3057 | return 0; | |
3058 | ||
3059 | /* | |
3060 | * Lockdep should run with IRQs disabled, otherwise we could | |
3061 | * get an interrupt which would want to take locks, which would | |
3062 | * end up in lockdep and have you got a head-ache already? | |
3063 | */ | |
3064 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
3065 | return 0; | |
3066 | ||
3067 | if (!prove_locking || lock->key == &__lockdep_no_validate__) | |
3068 | check = 0; | |
3069 | ||
3070 | if (subclass < NR_LOCKDEP_CACHING_CLASSES) | |
3071 | class = lock->class_cache[subclass]; | |
3072 | /* | |
3073 | * Not cached? | |
3074 | */ | |
3075 | if (unlikely(!class)) { | |
3076 | class = register_lock_class(lock, subclass, 0); | |
3077 | if (!class) | |
3078 | return 0; | |
3079 | } | |
3080 | atomic_inc((atomic_t *)&class->ops); | |
3081 | if (very_verbose(class)) { | |
3082 | printk("\nacquire class [%p] %s", class->key, class->name); | |
3083 | if (class->name_version > 1) | |
3084 | printk("#%d", class->name_version); | |
3085 | printk("\n"); | |
3086 | dump_stack(); | |
3087 | } | |
3088 | ||
3089 | /* | |
3090 | * Add the lock to the list of currently held locks. | |
3091 | * (we dont increase the depth just yet, up until the | |
3092 | * dependency checks are done) | |
3093 | */ | |
3094 | depth = curr->lockdep_depth; | |
3095 | /* | |
3096 | * Ran out of static storage for our per-task lock stack again have we? | |
3097 | */ | |
3098 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) | |
3099 | return 0; | |
3100 | ||
3101 | class_idx = class - lock_classes + 1; | |
3102 | ||
3103 | if (depth) { | |
3104 | hlock = curr->held_locks + depth - 1; | |
3105 | if (hlock->class_idx == class_idx && nest_lock) { | |
3106 | if (hlock->references) | |
3107 | hlock->references++; | |
3108 | else | |
3109 | hlock->references = 2; | |
3110 | ||
3111 | return 1; | |
3112 | } | |
3113 | } | |
3114 | ||
3115 | hlock = curr->held_locks + depth; | |
3116 | /* | |
3117 | * Plain impossible, we just registered it and checked it weren't no | |
3118 | * NULL like.. I bet this mushroom I ate was good! | |
3119 | */ | |
3120 | if (DEBUG_LOCKS_WARN_ON(!class)) | |
3121 | return 0; | |
3122 | hlock->class_idx = class_idx; | |
3123 | hlock->acquire_ip = ip; | |
3124 | hlock->instance = lock; | |
3125 | hlock->nest_lock = nest_lock; | |
3126 | hlock->trylock = trylock; | |
3127 | hlock->read = read; | |
3128 | hlock->check = check; | |
3129 | hlock->hardirqs_off = !!hardirqs_off; | |
3130 | hlock->references = references; | |
3131 | #ifdef CONFIG_LOCK_STAT | |
3132 | hlock->waittime_stamp = 0; | |
3133 | hlock->holdtime_stamp = lockstat_clock(); | |
3134 | #endif | |
3135 | hlock->pin_count = pin_count; | |
3136 | ||
3137 | if (check && !mark_irqflags(curr, hlock)) | |
3138 | return 0; | |
3139 | ||
3140 | /* mark it as used: */ | |
3141 | if (!mark_lock(curr, hlock, LOCK_USED)) | |
3142 | return 0; | |
3143 | ||
3144 | /* | |
3145 | * Calculate the chain hash: it's the combined hash of all the | |
3146 | * lock keys along the dependency chain. We save the hash value | |
3147 | * at every step so that we can get the current hash easily | |
3148 | * after unlock. The chain hash is then used to cache dependency | |
3149 | * results. | |
3150 | * | |
3151 | * The 'key ID' is what is the most compact key value to drive | |
3152 | * the hash, not class->key. | |
3153 | */ | |
3154 | id = class - lock_classes; | |
3155 | /* | |
3156 | * Whoops, we did it again.. ran straight out of our static allocation. | |
3157 | */ | |
3158 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) | |
3159 | return 0; | |
3160 | ||
3161 | chain_key = curr->curr_chain_key; | |
3162 | if (!depth) { | |
3163 | /* | |
3164 | * How can we have a chain hash when we ain't got no keys?! | |
3165 | */ | |
3166 | if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) | |
3167 | return 0; | |
3168 | chain_head = 1; | |
3169 | } | |
3170 | ||
3171 | hlock->prev_chain_key = chain_key; | |
3172 | if (separate_irq_context(curr, hlock)) { | |
3173 | chain_key = 0; | |
3174 | chain_head = 1; | |
3175 | } | |
3176 | chain_key = iterate_chain_key(chain_key, id); | |
3177 | ||
3178 | if (nest_lock && !__lock_is_held(nest_lock)) | |
3179 | return print_lock_nested_lock_not_held(curr, hlock, ip); | |
3180 | ||
3181 | if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) | |
3182 | return 0; | |
3183 | ||
3184 | curr->curr_chain_key = chain_key; | |
3185 | curr->lockdep_depth++; | |
3186 | check_chain_key(curr); | |
3187 | #ifdef CONFIG_DEBUG_LOCKDEP | |
3188 | if (unlikely(!debug_locks)) | |
3189 | return 0; | |
3190 | #endif | |
3191 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { | |
3192 | debug_locks_off(); | |
3193 | print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!"); | |
3194 | printk(KERN_DEBUG "depth: %i max: %lu!\n", | |
3195 | curr->lockdep_depth, MAX_LOCK_DEPTH); | |
3196 | ||
3197 | lockdep_print_held_locks(current); | |
3198 | debug_show_all_locks(); | |
3199 | dump_stack(); | |
3200 | ||
3201 | return 0; | |
3202 | } | |
3203 | ||
3204 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) | |
3205 | max_lockdep_depth = curr->lockdep_depth; | |
3206 | ||
3207 | return 1; | |
3208 | } | |
3209 | ||
3210 | static int | |
3211 | print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock, | |
3212 | unsigned long ip) | |
3213 | { | |
3214 | if (!debug_locks_off()) | |
3215 | return 0; | |
3216 | if (debug_locks_silent) | |
3217 | return 0; | |
3218 | ||
3219 | printk("\n"); | |
3220 | printk("=====================================\n"); | |
3221 | printk("[ BUG: bad unlock balance detected! ]\n"); | |
3222 | print_kernel_ident(); | |
3223 | printk("-------------------------------------\n"); | |
3224 | printk("%s/%d is trying to release lock (", | |
3225 | curr->comm, task_pid_nr(curr)); | |
3226 | print_lockdep_cache(lock); | |
3227 | printk(") at:\n"); | |
3228 | print_ip_sym(ip); | |
3229 | printk("but there are no more locks to release!\n"); | |
3230 | printk("\nother info that might help us debug this:\n"); | |
3231 | lockdep_print_held_locks(curr); | |
3232 | ||
3233 | printk("\nstack backtrace:\n"); | |
3234 | dump_stack(); | |
3235 | ||
3236 | return 0; | |
3237 | } | |
3238 | ||
3239 | static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) | |
3240 | { | |
3241 | if (hlock->instance == lock) | |
3242 | return 1; | |
3243 | ||
3244 | if (hlock->references) { | |
3245 | struct lock_class *class = lock->class_cache[0]; | |
3246 | ||
3247 | if (!class) | |
3248 | class = look_up_lock_class(lock, 0); | |
3249 | ||
3250 | /* | |
3251 | * If look_up_lock_class() failed to find a class, we're trying | |
3252 | * to test if we hold a lock that has never yet been acquired. | |
3253 | * Clearly if the lock hasn't been acquired _ever_, we're not | |
3254 | * holding it either, so report failure. | |
3255 | */ | |
3256 | if (!class) | |
3257 | return 0; | |
3258 | ||
3259 | /* | |
3260 | * References, but not a lock we're actually ref-counting? | |
3261 | * State got messed up, follow the sites that change ->references | |
3262 | * and try to make sense of it. | |
3263 | */ | |
3264 | if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) | |
3265 | return 0; | |
3266 | ||
3267 | if (hlock->class_idx == class - lock_classes + 1) | |
3268 | return 1; | |
3269 | } | |
3270 | ||
3271 | return 0; | |
3272 | } | |
3273 | ||
3274 | static int | |
3275 | __lock_set_class(struct lockdep_map *lock, const char *name, | |
3276 | struct lock_class_key *key, unsigned int subclass, | |
3277 | unsigned long ip) | |
3278 | { | |
3279 | struct task_struct *curr = current; | |
3280 | struct held_lock *hlock, *prev_hlock; | |
3281 | struct lock_class *class; | |
3282 | unsigned int depth; | |
3283 | int i; | |
3284 | ||
3285 | depth = curr->lockdep_depth; | |
3286 | /* | |
3287 | * This function is about (re)setting the class of a held lock, | |
3288 | * yet we're not actually holding any locks. Naughty user! | |
3289 | */ | |
3290 | if (DEBUG_LOCKS_WARN_ON(!depth)) | |
3291 | return 0; | |
3292 | ||
3293 | prev_hlock = NULL; | |
3294 | for (i = depth-1; i >= 0; i--) { | |
3295 | hlock = curr->held_locks + i; | |
3296 | /* | |
3297 | * We must not cross into another context: | |
3298 | */ | |
3299 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) | |
3300 | break; | |
3301 | if (match_held_lock(hlock, lock)) | |
3302 | goto found_it; | |
3303 | prev_hlock = hlock; | |
3304 | } | |
3305 | return print_unlock_imbalance_bug(curr, lock, ip); | |
3306 | ||
3307 | found_it: | |
3308 | lockdep_init_map(lock, name, key, 0); | |
3309 | class = register_lock_class(lock, subclass, 0); | |
3310 | hlock->class_idx = class - lock_classes + 1; | |
3311 | ||
3312 | curr->lockdep_depth = i; | |
3313 | curr->curr_chain_key = hlock->prev_chain_key; | |
3314 | ||
3315 | for (; i < depth; i++) { | |
3316 | hlock = curr->held_locks + i; | |
3317 | if (!__lock_acquire(hlock->instance, | |
3318 | hlock_class(hlock)->subclass, hlock->trylock, | |
3319 | hlock->read, hlock->check, hlock->hardirqs_off, | |
3320 | hlock->nest_lock, hlock->acquire_ip, | |
3321 | hlock->references, hlock->pin_count)) | |
3322 | return 0; | |
3323 | } | |
3324 | ||
3325 | /* | |
3326 | * I took it apart and put it back together again, except now I have | |
3327 | * these 'spare' parts.. where shall I put them. | |
3328 | */ | |
3329 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) | |
3330 | return 0; | |
3331 | return 1; | |
3332 | } | |
3333 | ||
3334 | /* | |
3335 | * Remove the lock to the list of currently held locks - this gets | |
3336 | * called on mutex_unlock()/spin_unlock*() (or on a failed | |
3337 | * mutex_lock_interruptible()). | |
3338 | * | |
3339 | * @nested is an hysterical artifact, needs a tree wide cleanup. | |
3340 | */ | |
3341 | static int | |
3342 | __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) | |
3343 | { | |
3344 | struct task_struct *curr = current; | |
3345 | struct held_lock *hlock, *prev_hlock; | |
3346 | unsigned int depth; | |
3347 | int i; | |
3348 | ||
3349 | if (unlikely(!debug_locks)) | |
3350 | return 0; | |
3351 | ||
3352 | depth = curr->lockdep_depth; | |
3353 | /* | |
3354 | * So we're all set to release this lock.. wait what lock? We don't | |
3355 | * own any locks, you've been drinking again? | |
3356 | */ | |
3357 | if (DEBUG_LOCKS_WARN_ON(depth <= 0)) | |
3358 | return print_unlock_imbalance_bug(curr, lock, ip); | |
3359 | ||
3360 | /* | |
3361 | * Check whether the lock exists in the current stack | |
3362 | * of held locks: | |
3363 | */ | |
3364 | prev_hlock = NULL; | |
3365 | for (i = depth-1; i >= 0; i--) { | |
3366 | hlock = curr->held_locks + i; | |
3367 | /* | |
3368 | * We must not cross into another context: | |
3369 | */ | |
3370 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) | |
3371 | break; | |
3372 | if (match_held_lock(hlock, lock)) | |
3373 | goto found_it; | |
3374 | prev_hlock = hlock; | |
3375 | } | |
3376 | return print_unlock_imbalance_bug(curr, lock, ip); | |
3377 | ||
3378 | found_it: | |
3379 | if (hlock->instance == lock) | |
3380 | lock_release_holdtime(hlock); | |
3381 | ||
3382 | WARN(hlock->pin_count, "releasing a pinned lock\n"); | |
3383 | ||
3384 | if (hlock->references) { | |
3385 | hlock->references--; | |
3386 | if (hlock->references) { | |
3387 | /* | |
3388 | * We had, and after removing one, still have | |
3389 | * references, the current lock stack is still | |
3390 | * valid. We're done! | |
3391 | */ | |
3392 | return 1; | |
3393 | } | |
3394 | } | |
3395 | ||
3396 | /* | |
3397 | * We have the right lock to unlock, 'hlock' points to it. | |
3398 | * Now we remove it from the stack, and add back the other | |
3399 | * entries (if any), recalculating the hash along the way: | |
3400 | */ | |
3401 | ||
3402 | curr->lockdep_depth = i; | |
3403 | curr->curr_chain_key = hlock->prev_chain_key; | |
3404 | ||
3405 | for (i++; i < depth; i++) { | |
3406 | hlock = curr->held_locks + i; | |
3407 | if (!__lock_acquire(hlock->instance, | |
3408 | hlock_class(hlock)->subclass, hlock->trylock, | |
3409 | hlock->read, hlock->check, hlock->hardirqs_off, | |
3410 | hlock->nest_lock, hlock->acquire_ip, | |
3411 | hlock->references, hlock->pin_count)) | |
3412 | return 0; | |
3413 | } | |
3414 | ||
3415 | /* | |
3416 | * We had N bottles of beer on the wall, we drank one, but now | |
3417 | * there's not N-1 bottles of beer left on the wall... | |
3418 | */ | |
3419 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) | |
3420 | return 0; | |
3421 | ||
3422 | return 1; | |
3423 | } | |
3424 | ||
3425 | static int __lock_is_held(struct lockdep_map *lock) | |
3426 | { | |
3427 | struct task_struct *curr = current; | |
3428 | int i; | |
3429 | ||
3430 | for (i = 0; i < curr->lockdep_depth; i++) { | |
3431 | struct held_lock *hlock = curr->held_locks + i; | |
3432 | ||
3433 | if (match_held_lock(hlock, lock)) | |
3434 | return 1; | |
3435 | } | |
3436 | ||
3437 | return 0; | |
3438 | } | |
3439 | ||
3440 | static void __lock_pin_lock(struct lockdep_map *lock) | |
3441 | { | |
3442 | struct task_struct *curr = current; | |
3443 | int i; | |
3444 | ||
3445 | if (unlikely(!debug_locks)) | |
3446 | return; | |
3447 | ||
3448 | for (i = 0; i < curr->lockdep_depth; i++) { | |
3449 | struct held_lock *hlock = curr->held_locks + i; | |
3450 | ||
3451 | if (match_held_lock(hlock, lock)) { | |
3452 | hlock->pin_count++; | |
3453 | return; | |
3454 | } | |
3455 | } | |
3456 | ||
3457 | WARN(1, "pinning an unheld lock\n"); | |
3458 | } | |
3459 | ||
3460 | static void __lock_unpin_lock(struct lockdep_map *lock) | |
3461 | { | |
3462 | struct task_struct *curr = current; | |
3463 | int i; | |
3464 | ||
3465 | if (unlikely(!debug_locks)) | |
3466 | return; | |
3467 | ||
3468 | for (i = 0; i < curr->lockdep_depth; i++) { | |
3469 | struct held_lock *hlock = curr->held_locks + i; | |
3470 | ||
3471 | if (match_held_lock(hlock, lock)) { | |
3472 | if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n")) | |
3473 | return; | |
3474 | ||
3475 | hlock->pin_count--; | |
3476 | return; | |
3477 | } | |
3478 | } | |
3479 | ||
3480 | WARN(1, "unpinning an unheld lock\n"); | |
3481 | } | |
3482 | ||
3483 | /* | |
3484 | * Check whether we follow the irq-flags state precisely: | |
3485 | */ | |
3486 | static void check_flags(unsigned long flags) | |
3487 | { | |
3488 | #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \ | |
3489 | defined(CONFIG_TRACE_IRQFLAGS) | |
3490 | if (!debug_locks) | |
3491 | return; | |
3492 | ||
3493 | if (irqs_disabled_flags(flags)) { | |
3494 | if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { | |
3495 | printk("possible reason: unannotated irqs-off.\n"); | |
3496 | } | |
3497 | } else { | |
3498 | if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { | |
3499 | printk("possible reason: unannotated irqs-on.\n"); | |
3500 | } | |
3501 | } | |
3502 | ||
3503 | /* | |
3504 | * We dont accurately track softirq state in e.g. | |
3505 | * hardirq contexts (such as on 4KSTACKS), so only | |
3506 | * check if not in hardirq contexts: | |
3507 | */ | |
3508 | if (!hardirq_count()) { | |
3509 | if (softirq_count()) { | |
3510 | /* like the above, but with softirqs */ | |
3511 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); | |
3512 | } else { | |
3513 | /* lick the above, does it taste good? */ | |
3514 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); | |
3515 | } | |
3516 | } | |
3517 | ||
3518 | if (!debug_locks) | |
3519 | print_irqtrace_events(current); | |
3520 | #endif | |
3521 | } | |
3522 | ||
3523 | void lock_set_class(struct lockdep_map *lock, const char *name, | |
3524 | struct lock_class_key *key, unsigned int subclass, | |
3525 | unsigned long ip) | |
3526 | { | |
3527 | unsigned long flags; | |
3528 | ||
3529 | if (unlikely(current->lockdep_recursion)) | |
3530 | return; | |
3531 | ||
3532 | raw_local_irq_save(flags); | |
3533 | current->lockdep_recursion = 1; | |
3534 | check_flags(flags); | |
3535 | if (__lock_set_class(lock, name, key, subclass, ip)) | |
3536 | check_chain_key(current); | |
3537 | current->lockdep_recursion = 0; | |
3538 | raw_local_irq_restore(flags); | |
3539 | } | |
3540 | EXPORT_SYMBOL_GPL(lock_set_class); | |
3541 | ||
3542 | /* | |
3543 | * We are not always called with irqs disabled - do that here, | |
3544 | * and also avoid lockdep recursion: | |
3545 | */ | |
3546 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
3547 | int trylock, int read, int check, | |
3548 | struct lockdep_map *nest_lock, unsigned long ip) | |
3549 | { | |
3550 | unsigned long flags; | |
3551 | ||
3552 | if (unlikely(current->lockdep_recursion)) | |
3553 | return; | |
3554 | ||
3555 | raw_local_irq_save(flags); | |
3556 | check_flags(flags); | |
3557 | ||
3558 | current->lockdep_recursion = 1; | |
3559 | trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); | |
3560 | __lock_acquire(lock, subclass, trylock, read, check, | |
3561 | irqs_disabled_flags(flags), nest_lock, ip, 0, 0); | |
3562 | current->lockdep_recursion = 0; | |
3563 | raw_local_irq_restore(flags); | |
3564 | } | |
3565 | EXPORT_SYMBOL_GPL(lock_acquire); | |
3566 | ||
3567 | void lock_release(struct lockdep_map *lock, int nested, | |
3568 | unsigned long ip) | |
3569 | { | |
3570 | unsigned long flags; | |
3571 | ||
3572 | if (unlikely(current->lockdep_recursion)) | |
3573 | return; | |
3574 | ||
3575 | raw_local_irq_save(flags); | |
3576 | check_flags(flags); | |
3577 | current->lockdep_recursion = 1; | |
3578 | trace_lock_release(lock, ip); | |
3579 | if (__lock_release(lock, nested, ip)) | |
3580 | check_chain_key(current); | |
3581 | current->lockdep_recursion = 0; | |
3582 | raw_local_irq_restore(flags); | |
3583 | } | |
3584 | EXPORT_SYMBOL_GPL(lock_release); | |
3585 | ||
3586 | int lock_is_held(struct lockdep_map *lock) | |
3587 | { | |
3588 | unsigned long flags; | |
3589 | int ret = 0; | |
3590 | ||
3591 | if (unlikely(current->lockdep_recursion)) | |
3592 | return 1; /* avoid false negative lockdep_assert_held() */ | |
3593 | ||
3594 | raw_local_irq_save(flags); | |
3595 | check_flags(flags); | |
3596 | ||
3597 | current->lockdep_recursion = 1; | |
3598 | ret = __lock_is_held(lock); | |
3599 | current->lockdep_recursion = 0; | |
3600 | raw_local_irq_restore(flags); | |
3601 | ||
3602 | return ret; | |
3603 | } | |
3604 | EXPORT_SYMBOL_GPL(lock_is_held); | |
3605 | ||
3606 | void lock_pin_lock(struct lockdep_map *lock) | |
3607 | { | |
3608 | unsigned long flags; | |
3609 | ||
3610 | if (unlikely(current->lockdep_recursion)) | |
3611 | return; | |
3612 | ||
3613 | raw_local_irq_save(flags); | |
3614 | check_flags(flags); | |
3615 | ||
3616 | current->lockdep_recursion = 1; | |
3617 | __lock_pin_lock(lock); | |
3618 | current->lockdep_recursion = 0; | |
3619 | raw_local_irq_restore(flags); | |
3620 | } | |
3621 | EXPORT_SYMBOL_GPL(lock_pin_lock); | |
3622 | ||
3623 | void lock_unpin_lock(struct lockdep_map *lock) | |
3624 | { | |
3625 | unsigned long flags; | |
3626 | ||
3627 | if (unlikely(current->lockdep_recursion)) | |
3628 | return; | |
3629 | ||
3630 | raw_local_irq_save(flags); | |
3631 | check_flags(flags); | |
3632 | ||
3633 | current->lockdep_recursion = 1; | |
3634 | __lock_unpin_lock(lock); | |
3635 | current->lockdep_recursion = 0; | |
3636 | raw_local_irq_restore(flags); | |
3637 | } | |
3638 | EXPORT_SYMBOL_GPL(lock_unpin_lock); | |
3639 | ||
3640 | void lockdep_set_current_reclaim_state(gfp_t gfp_mask) | |
3641 | { | |
3642 | current->lockdep_reclaim_gfp = gfp_mask; | |
3643 | } | |
3644 | ||
3645 | void lockdep_clear_current_reclaim_state(void) | |
3646 | { | |
3647 | current->lockdep_reclaim_gfp = 0; | |
3648 | } | |
3649 | ||
3650 | #ifdef CONFIG_LOCK_STAT | |
3651 | static int | |
3652 | print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, | |
3653 | unsigned long ip) | |
3654 | { | |
3655 | if (!debug_locks_off()) | |
3656 | return 0; | |
3657 | if (debug_locks_silent) | |
3658 | return 0; | |
3659 | ||
3660 | printk("\n"); | |
3661 | printk("=================================\n"); | |
3662 | printk("[ BUG: bad contention detected! ]\n"); | |
3663 | print_kernel_ident(); | |
3664 | printk("---------------------------------\n"); | |
3665 | printk("%s/%d is trying to contend lock (", | |
3666 | curr->comm, task_pid_nr(curr)); | |
3667 | print_lockdep_cache(lock); | |
3668 | printk(") at:\n"); | |
3669 | print_ip_sym(ip); | |
3670 | printk("but there are no locks held!\n"); | |
3671 | printk("\nother info that might help us debug this:\n"); | |
3672 | lockdep_print_held_locks(curr); | |
3673 | ||
3674 | printk("\nstack backtrace:\n"); | |
3675 | dump_stack(); | |
3676 | ||
3677 | return 0; | |
3678 | } | |
3679 | ||
3680 | static void | |
3681 | __lock_contended(struct lockdep_map *lock, unsigned long ip) | |
3682 | { | |
3683 | struct task_struct *curr = current; | |
3684 | struct held_lock *hlock, *prev_hlock; | |
3685 | struct lock_class_stats *stats; | |
3686 | unsigned int depth; | |
3687 | int i, contention_point, contending_point; | |
3688 | ||
3689 | depth = curr->lockdep_depth; | |
3690 | /* | |
3691 | * Whee, we contended on this lock, except it seems we're not | |
3692 | * actually trying to acquire anything much at all.. | |
3693 | */ | |
3694 | if (DEBUG_LOCKS_WARN_ON(!depth)) | |
3695 | return; | |
3696 | ||
3697 | prev_hlock = NULL; | |
3698 | for (i = depth-1; i >= 0; i--) { | |
3699 | hlock = curr->held_locks + i; | |
3700 | /* | |
3701 | * We must not cross into another context: | |
3702 | */ | |
3703 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) | |
3704 | break; | |
3705 | if (match_held_lock(hlock, lock)) | |
3706 | goto found_it; | |
3707 | prev_hlock = hlock; | |
3708 | } | |
3709 | print_lock_contention_bug(curr, lock, ip); | |
3710 | return; | |
3711 | ||
3712 | found_it: | |
3713 | if (hlock->instance != lock) | |
3714 | return; | |
3715 | ||
3716 | hlock->waittime_stamp = lockstat_clock(); | |
3717 | ||
3718 | contention_point = lock_point(hlock_class(hlock)->contention_point, ip); | |
3719 | contending_point = lock_point(hlock_class(hlock)->contending_point, | |
3720 | lock->ip); | |
3721 | ||
3722 | stats = get_lock_stats(hlock_class(hlock)); | |
3723 | if (contention_point < LOCKSTAT_POINTS) | |
3724 | stats->contention_point[contention_point]++; | |
3725 | if (contending_point < LOCKSTAT_POINTS) | |
3726 | stats->contending_point[contending_point]++; | |
3727 | if (lock->cpu != smp_processor_id()) | |
3728 | stats->bounces[bounce_contended + !!hlock->read]++; | |
3729 | put_lock_stats(stats); | |
3730 | } | |
3731 | ||
3732 | static void | |
3733 | __lock_acquired(struct lockdep_map *lock, unsigned long ip) | |
3734 | { | |
3735 | struct task_struct *curr = current; | |
3736 | struct held_lock *hlock, *prev_hlock; | |
3737 | struct lock_class_stats *stats; | |
3738 | unsigned int depth; | |
3739 | u64 now, waittime = 0; | |
3740 | int i, cpu; | |
3741 | ||
3742 | depth = curr->lockdep_depth; | |
3743 | /* | |
3744 | * Yay, we acquired ownership of this lock we didn't try to | |
3745 | * acquire, how the heck did that happen? | |
3746 | */ | |
3747 | if (DEBUG_LOCKS_WARN_ON(!depth)) | |
3748 | return; | |
3749 | ||
3750 | prev_hlock = NULL; | |
3751 | for (i = depth-1; i >= 0; i--) { | |
3752 | hlock = curr->held_locks + i; | |
3753 | /* | |
3754 | * We must not cross into another context: | |
3755 | */ | |
3756 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) | |
3757 | break; | |
3758 | if (match_held_lock(hlock, lock)) | |
3759 | goto found_it; | |
3760 | prev_hlock = hlock; | |
3761 | } | |
3762 | print_lock_contention_bug(curr, lock, _RET_IP_); | |
3763 | return; | |
3764 | ||
3765 | found_it: | |
3766 | if (hlock->instance != lock) | |
3767 | return; | |
3768 | ||
3769 | cpu = smp_processor_id(); | |
3770 | if (hlock->waittime_stamp) { | |
3771 | now = lockstat_clock(); | |
3772 | waittime = now - hlock->waittime_stamp; | |
3773 | hlock->holdtime_stamp = now; | |
3774 | } | |
3775 | ||
3776 | trace_lock_acquired(lock, ip); | |
3777 | ||
3778 | stats = get_lock_stats(hlock_class(hlock)); | |
3779 | if (waittime) { | |
3780 | if (hlock->read) | |
3781 | lock_time_inc(&stats->read_waittime, waittime); | |
3782 | else | |
3783 | lock_time_inc(&stats->write_waittime, waittime); | |
3784 | } | |
3785 | if (lock->cpu != cpu) | |
3786 | stats->bounces[bounce_acquired + !!hlock->read]++; | |
3787 | put_lock_stats(stats); | |
3788 | ||
3789 | lock->cpu = cpu; | |
3790 | lock->ip = ip; | |
3791 | } | |
3792 | ||
3793 | void lock_contended(struct lockdep_map *lock, unsigned long ip) | |
3794 | { | |
3795 | unsigned long flags; | |
3796 | ||
3797 | if (unlikely(!lock_stat)) | |
3798 | return; | |
3799 | ||
3800 | if (unlikely(current->lockdep_recursion)) | |
3801 | return; | |
3802 | ||
3803 | raw_local_irq_save(flags); | |
3804 | check_flags(flags); | |
3805 | current->lockdep_recursion = 1; | |
3806 | trace_lock_contended(lock, ip); | |
3807 | __lock_contended(lock, ip); | |
3808 | current->lockdep_recursion = 0; | |
3809 | raw_local_irq_restore(flags); | |
3810 | } | |
3811 | EXPORT_SYMBOL_GPL(lock_contended); | |
3812 | ||
3813 | void lock_acquired(struct lockdep_map *lock, unsigned long ip) | |
3814 | { | |
3815 | unsigned long flags; | |
3816 | ||
3817 | if (unlikely(!lock_stat)) | |
3818 | return; | |
3819 | ||
3820 | if (unlikely(current->lockdep_recursion)) | |
3821 | return; | |
3822 | ||
3823 | raw_local_irq_save(flags); | |
3824 | check_flags(flags); | |
3825 | current->lockdep_recursion = 1; | |
3826 | __lock_acquired(lock, ip); | |
3827 | current->lockdep_recursion = 0; | |
3828 | raw_local_irq_restore(flags); | |
3829 | } | |
3830 | EXPORT_SYMBOL_GPL(lock_acquired); | |
3831 | #endif | |
3832 | ||
3833 | /* | |
3834 | * Used by the testsuite, sanitize the validator state | |
3835 | * after a simulated failure: | |
3836 | */ | |
3837 | ||
3838 | void lockdep_reset(void) | |
3839 | { | |
3840 | unsigned long flags; | |
3841 | int i; | |
3842 | ||
3843 | raw_local_irq_save(flags); | |
3844 | current->curr_chain_key = 0; | |
3845 | current->lockdep_depth = 0; | |
3846 | current->lockdep_recursion = 0; | |
3847 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); | |
3848 | nr_hardirq_chains = 0; | |
3849 | nr_softirq_chains = 0; | |
3850 | nr_process_chains = 0; | |
3851 | debug_locks = 1; | |
3852 | for (i = 0; i < CHAINHASH_SIZE; i++) | |
3853 | INIT_HLIST_HEAD(chainhash_table + i); | |
3854 | raw_local_irq_restore(flags); | |
3855 | } | |
3856 | ||
3857 | static void zap_class(struct lock_class *class) | |
3858 | { | |
3859 | int i; | |
3860 | ||
3861 | /* | |
3862 | * Remove all dependencies this lock is | |
3863 | * involved in: | |
3864 | */ | |
3865 | for (i = 0; i < nr_list_entries; i++) { | |
3866 | if (list_entries[i].class == class) | |
3867 | list_del_rcu(&list_entries[i].entry); | |
3868 | } | |
3869 | /* | |
3870 | * Unhash the class and remove it from the all_lock_classes list: | |
3871 | */ | |
3872 | hlist_del_rcu(&class->hash_entry); | |
3873 | list_del_rcu(&class->lock_entry); | |
3874 | ||
3875 | RCU_INIT_POINTER(class->key, NULL); | |
3876 | RCU_INIT_POINTER(class->name, NULL); | |
3877 | } | |
3878 | ||
3879 | static inline int within(const void *addr, void *start, unsigned long size) | |
3880 | { | |
3881 | return addr >= start && addr < start + size; | |
3882 | } | |
3883 | ||
3884 | /* | |
3885 | * Used in module.c to remove lock classes from memory that is going to be | |
3886 | * freed; and possibly re-used by other modules. | |
3887 | * | |
3888 | * We will have had one sync_sched() before getting here, so we're guaranteed | |
3889 | * nobody will look up these exact classes -- they're properly dead but still | |
3890 | * allocated. | |
3891 | */ | |
3892 | void lockdep_free_key_range(void *start, unsigned long size) | |
3893 | { | |
3894 | struct lock_class *class; | |
3895 | struct hlist_head *head; | |
3896 | unsigned long flags; | |
3897 | int i; | |
3898 | int locked; | |
3899 | ||
3900 | raw_local_irq_save(flags); | |
3901 | locked = graph_lock(); | |
3902 | ||
3903 | /* | |
3904 | * Unhash all classes that were created by this module: | |
3905 | */ | |
3906 | for (i = 0; i < CLASSHASH_SIZE; i++) { | |
3907 | head = classhash_table + i; | |
3908 | hlist_for_each_entry_rcu(class, head, hash_entry) { | |
3909 | if (within(class->key, start, size)) | |
3910 | zap_class(class); | |
3911 | else if (within(class->name, start, size)) | |
3912 | zap_class(class); | |
3913 | } | |
3914 | } | |
3915 | ||
3916 | if (locked) | |
3917 | graph_unlock(); | |
3918 | raw_local_irq_restore(flags); | |
3919 | ||
3920 | /* | |
3921 | * Wait for any possible iterators from look_up_lock_class() to pass | |
3922 | * before continuing to free the memory they refer to. | |
3923 | * | |
3924 | * sync_sched() is sufficient because the read-side is IRQ disable. | |
3925 | */ | |
3926 | synchronize_sched(); | |
3927 | ||
3928 | /* | |
3929 | * XXX at this point we could return the resources to the pool; | |
3930 | * instead we leak them. We would need to change to bitmap allocators | |
3931 | * instead of the linear allocators we have now. | |
3932 | */ | |
3933 | } | |
3934 | ||
3935 | void lockdep_reset_lock(struct lockdep_map *lock) | |
3936 | { | |
3937 | struct lock_class *class; | |
3938 | struct hlist_head *head; | |
3939 | unsigned long flags; | |
3940 | int i, j; | |
3941 | int locked; | |
3942 | ||
3943 | raw_local_irq_save(flags); | |
3944 | ||
3945 | /* | |
3946 | * Remove all classes this lock might have: | |
3947 | */ | |
3948 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { | |
3949 | /* | |
3950 | * If the class exists we look it up and zap it: | |
3951 | */ | |
3952 | class = look_up_lock_class(lock, j); | |
3953 | if (class) | |
3954 | zap_class(class); | |
3955 | } | |
3956 | /* | |
3957 | * Debug check: in the end all mapped classes should | |
3958 | * be gone. | |
3959 | */ | |
3960 | locked = graph_lock(); | |
3961 | for (i = 0; i < CLASSHASH_SIZE; i++) { | |
3962 | head = classhash_table + i; | |
3963 | hlist_for_each_entry_rcu(class, head, hash_entry) { | |
3964 | int match = 0; | |
3965 | ||
3966 | for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) | |
3967 | match |= class == lock->class_cache[j]; | |
3968 | ||
3969 | if (unlikely(match)) { | |
3970 | if (debug_locks_off_graph_unlock()) { | |
3971 | /* | |
3972 | * We all just reset everything, how did it match? | |
3973 | */ | |
3974 | WARN_ON(1); | |
3975 | } | |
3976 | goto out_restore; | |
3977 | } | |
3978 | } | |
3979 | } | |
3980 | if (locked) | |
3981 | graph_unlock(); | |
3982 | ||
3983 | out_restore: | |
3984 | raw_local_irq_restore(flags); | |
3985 | } | |
3986 | ||
3987 | void __init lockdep_info(void) | |
3988 | { | |
3989 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); | |
3990 | ||
3991 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); | |
3992 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); | |
3993 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); | |
3994 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); | |
3995 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); | |
3996 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); | |
3997 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); | |
3998 | ||
3999 | printk(" memory used by lock dependency info: %lu kB\n", | |
4000 | (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + | |
4001 | sizeof(struct list_head) * CLASSHASH_SIZE + | |
4002 | sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + | |
4003 | sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + | |
4004 | sizeof(struct list_head) * CHAINHASH_SIZE | |
4005 | #ifdef CONFIG_PROVE_LOCKING | |
4006 | + sizeof(struct circular_queue) | |
4007 | #endif | |
4008 | ) / 1024 | |
4009 | ); | |
4010 | ||
4011 | printk(" per task-struct memory footprint: %lu bytes\n", | |
4012 | sizeof(struct held_lock) * MAX_LOCK_DEPTH); | |
4013 | } | |
4014 | ||
4015 | static void | |
4016 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, | |
4017 | const void *mem_to, struct held_lock *hlock) | |
4018 | { | |
4019 | if (!debug_locks_off()) | |
4020 | return; | |
4021 | if (debug_locks_silent) | |
4022 | return; | |
4023 | ||
4024 | printk("\n"); | |
4025 | printk("=========================\n"); | |
4026 | printk("[ BUG: held lock freed! ]\n"); | |
4027 | print_kernel_ident(); | |
4028 | printk("-------------------------\n"); | |
4029 | printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", | |
4030 | curr->comm, task_pid_nr(curr), mem_from, mem_to-1); | |
4031 | print_lock(hlock); | |
4032 | lockdep_print_held_locks(curr); | |
4033 | ||
4034 | printk("\nstack backtrace:\n"); | |
4035 | dump_stack(); | |
4036 | } | |
4037 | ||
4038 | static inline int not_in_range(const void* mem_from, unsigned long mem_len, | |
4039 | const void* lock_from, unsigned long lock_len) | |
4040 | { | |
4041 | return lock_from + lock_len <= mem_from || | |
4042 | mem_from + mem_len <= lock_from; | |
4043 | } | |
4044 | ||
4045 | /* | |
4046 | * Called when kernel memory is freed (or unmapped), or if a lock | |
4047 | * is destroyed or reinitialized - this code checks whether there is | |
4048 | * any held lock in the memory range of <from> to <to>: | |
4049 | */ | |
4050 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) | |
4051 | { | |
4052 | struct task_struct *curr = current; | |
4053 | struct held_lock *hlock; | |
4054 | unsigned long flags; | |
4055 | int i; | |
4056 | ||
4057 | if (unlikely(!debug_locks)) | |
4058 | return; | |
4059 | ||
4060 | local_irq_save(flags); | |
4061 | for (i = 0; i < curr->lockdep_depth; i++) { | |
4062 | hlock = curr->held_locks + i; | |
4063 | ||
4064 | if (not_in_range(mem_from, mem_len, hlock->instance, | |
4065 | sizeof(*hlock->instance))) | |
4066 | continue; | |
4067 | ||
4068 | print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); | |
4069 | break; | |
4070 | } | |
4071 | local_irq_restore(flags); | |
4072 | } | |
4073 | EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); | |
4074 | ||
4075 | static void print_held_locks_bug(void) | |
4076 | { | |
4077 | if (!debug_locks_off()) | |
4078 | return; | |
4079 | if (debug_locks_silent) | |
4080 | return; | |
4081 | ||
4082 | printk("\n"); | |
4083 | printk("=====================================\n"); | |
4084 | printk("[ BUG: %s/%d still has locks held! ]\n", | |
4085 | current->comm, task_pid_nr(current)); | |
4086 | print_kernel_ident(); | |
4087 | printk("-------------------------------------\n"); | |
4088 | lockdep_print_held_locks(current); | |
4089 | printk("\nstack backtrace:\n"); | |
4090 | dump_stack(); | |
4091 | } | |
4092 | ||
4093 | void debug_check_no_locks_held(void) | |
4094 | { | |
4095 | if (unlikely(current->lockdep_depth > 0)) | |
4096 | print_held_locks_bug(); | |
4097 | } | |
4098 | EXPORT_SYMBOL_GPL(debug_check_no_locks_held); | |
4099 | ||
4100 | #ifdef __KERNEL__ | |
4101 | void debug_show_all_locks(void) | |
4102 | { | |
4103 | struct task_struct *g, *p; | |
4104 | int count = 10; | |
4105 | int unlock = 1; | |
4106 | ||
4107 | if (unlikely(!debug_locks)) { | |
4108 | printk("INFO: lockdep is turned off.\n"); | |
4109 | return; | |
4110 | } | |
4111 | printk("\nShowing all locks held in the system:\n"); | |
4112 | ||
4113 | /* | |
4114 | * Here we try to get the tasklist_lock as hard as possible, | |
4115 | * if not successful after 2 seconds we ignore it (but keep | |
4116 | * trying). This is to enable a debug printout even if a | |
4117 | * tasklist_lock-holding task deadlocks or crashes. | |
4118 | */ | |
4119 | retry: | |
4120 | if (!read_trylock(&tasklist_lock)) { | |
4121 | if (count == 10) | |
4122 | printk("hm, tasklist_lock locked, retrying... "); | |
4123 | if (count) { | |
4124 | count--; | |
4125 | printk(" #%d", 10-count); | |
4126 | mdelay(200); | |
4127 | goto retry; | |
4128 | } | |
4129 | printk(" ignoring it.\n"); | |
4130 | unlock = 0; | |
4131 | } else { | |
4132 | if (count != 10) | |
4133 | printk(KERN_CONT " locked it.\n"); | |
4134 | } | |
4135 | ||
4136 | do_each_thread(g, p) { | |
4137 | /* | |
4138 | * It's not reliable to print a task's held locks | |
4139 | * if it's not sleeping (or if it's not the current | |
4140 | * task): | |
4141 | */ | |
4142 | if (p->state == TASK_RUNNING && p != current) | |
4143 | continue; | |
4144 | if (p->lockdep_depth) | |
4145 | lockdep_print_held_locks(p); | |
4146 | if (!unlock) | |
4147 | if (read_trylock(&tasklist_lock)) | |
4148 | unlock = 1; | |
4149 | } while_each_thread(g, p); | |
4150 | ||
4151 | printk("\n"); | |
4152 | printk("=============================================\n\n"); | |
4153 | ||
4154 | if (unlock) | |
4155 | read_unlock(&tasklist_lock); | |
4156 | } | |
4157 | EXPORT_SYMBOL_GPL(debug_show_all_locks); | |
4158 | #endif | |
4159 | ||
4160 | /* | |
4161 | * Careful: only use this function if you are sure that | |
4162 | * the task cannot run in parallel! | |
4163 | */ | |
4164 | void debug_show_held_locks(struct task_struct *task) | |
4165 | { | |
4166 | if (unlikely(!debug_locks)) { | |
4167 | printk("INFO: lockdep is turned off.\n"); | |
4168 | return; | |
4169 | } | |
4170 | lockdep_print_held_locks(task); | |
4171 | } | |
4172 | EXPORT_SYMBOL_GPL(debug_show_held_locks); | |
4173 | ||
4174 | asmlinkage __visible void lockdep_sys_exit(void) | |
4175 | { | |
4176 | struct task_struct *curr = current; | |
4177 | ||
4178 | if (unlikely(curr->lockdep_depth)) { | |
4179 | if (!debug_locks_off()) | |
4180 | return; | |
4181 | printk("\n"); | |
4182 | printk("================================================\n"); | |
4183 | printk("[ BUG: lock held when returning to user space! ]\n"); | |
4184 | print_kernel_ident(); | |
4185 | printk("------------------------------------------------\n"); | |
4186 | printk("%s/%d is leaving the kernel with locks still held!\n", | |
4187 | curr->comm, curr->pid); | |
4188 | lockdep_print_held_locks(curr); | |
4189 | } | |
4190 | } | |
4191 | ||
4192 | void lockdep_rcu_suspicious(const char *file, const int line, const char *s) | |
4193 | { | |
4194 | struct task_struct *curr = current; | |
4195 | ||
4196 | #ifndef CONFIG_PROVE_RCU_REPEATEDLY | |
4197 | if (!debug_locks_off()) | |
4198 | return; | |
4199 | #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */ | |
4200 | /* Note: the following can be executed concurrently, so be careful. */ | |
4201 | printk("\n"); | |
4202 | printk("===============================\n"); | |
4203 | printk("[ INFO: suspicious RCU usage. ]\n"); | |
4204 | print_kernel_ident(); | |
4205 | printk("-------------------------------\n"); | |
4206 | printk("%s:%d %s!\n", file, line, s); | |
4207 | printk("\nother info that might help us debug this:\n\n"); | |
4208 | printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n", | |
4209 | !rcu_lockdep_current_cpu_online() | |
4210 | ? "RCU used illegally from offline CPU!\n" | |
4211 | : !rcu_is_watching() | |
4212 | ? "RCU used illegally from idle CPU!\n" | |
4213 | : "", | |
4214 | rcu_scheduler_active, debug_locks); | |
4215 | ||
4216 | /* | |
4217 | * If a CPU is in the RCU-free window in idle (ie: in the section | |
4218 | * between rcu_idle_enter() and rcu_idle_exit(), then RCU | |
4219 | * considers that CPU to be in an "extended quiescent state", | |
4220 | * which means that RCU will be completely ignoring that CPU. | |
4221 | * Therefore, rcu_read_lock() and friends have absolutely no | |
4222 | * effect on a CPU running in that state. In other words, even if | |
4223 | * such an RCU-idle CPU has called rcu_read_lock(), RCU might well | |
4224 | * delete data structures out from under it. RCU really has no | |
4225 | * choice here: we need to keep an RCU-free window in idle where | |
4226 | * the CPU may possibly enter into low power mode. This way we can | |
4227 | * notice an extended quiescent state to other CPUs that started a grace | |
4228 | * period. Otherwise we would delay any grace period as long as we run | |
4229 | * in the idle task. | |
4230 | * | |
4231 | * So complain bitterly if someone does call rcu_read_lock(), | |
4232 | * rcu_read_lock_bh() and so on from extended quiescent states. | |
4233 | */ | |
4234 | if (!rcu_is_watching()) | |
4235 | printk("RCU used illegally from extended quiescent state!\n"); | |
4236 | ||
4237 | lockdep_print_held_locks(curr); | |
4238 | printk("\nstack backtrace:\n"); | |
4239 | dump_stack(); | |
4240 | } | |
4241 | EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); |