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