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Source at commit b13e7eb172b6f08e5fc22da162bdde5fcde201b5 created 11 years 11 months ago. By Maarten ter Huurne, fbcon: Add 6x10 font | |
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1 | /* |
2 | * kernel/lockdep.c |
3 | * |
4 | * Runtime locking correctness validator |
5 | * |
6 | * Started by Ingo Molnar: |
7 | * |
8 | * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
9 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
10 | * |
11 | * this code maps all the lock dependencies as they occur in a live kernel |
12 | * and will warn about the following classes of locking bugs: |
13 | * |
14 | * - lock inversion scenarios |
15 | * - circular lock dependencies |
16 | * - hardirq/softirq safe/unsafe locking bugs |
17 | * |
18 | * Bugs are reported even if the current locking scenario does not cause |
19 | * any deadlock at this point. |
20 | * |
21 | * I.e. if anytime in the past two locks were taken in a different order, |
22 | * even if it happened for another task, even if those were different |
23 | * locks (but of the same class as this lock), this code will detect it. |
24 | * |
25 | * Thanks to Arjan van de Ven for coming up with the initial idea of |
26 | * mapping lock dependencies runtime. |
27 | */ |
28 | #define DISABLE_BRANCH_PROFILING |
29 | #include <linux/mutex.h> |
30 | #include <linux/sched.h> |
31 | #include <linux/delay.h> |
32 | #include <linux/module.h> |
33 | #include <linux/proc_fs.h> |
34 | #include <linux/seq_file.h> |
35 | #include <linux/spinlock.h> |
36 | #include <linux/kallsyms.h> |
37 | #include <linux/interrupt.h> |
38 | #include <linux/stacktrace.h> |
39 | #include <linux/debug_locks.h> |
40 | #include <linux/irqflags.h> |
41 | #include <linux/utsname.h> |
42 | #include <linux/hash.h> |
43 | #include <linux/ftrace.h> |
44 | #include <linux/stringify.h> |
45 | #include <linux/bitops.h> |
46 | #include <linux/gfp.h> |
47 | #include <linux/kmemcheck.h> |
48 | |
49 | #include <asm/sections.h> |
50 | |
51 | #include "lockdep_internals.h" |
52 | |
53 | #define CREATE_TRACE_POINTS |
54 | #include <trace/events/lock.h> |
55 | |
56 | #ifdef CONFIG_PROVE_LOCKING |
57 | int prove_locking = 1; |
58 | module_param(prove_locking, int, 0644); |
59 | #else |
60 | #define prove_locking 0 |
61 | #endif |
62 | |
63 | #ifdef CONFIG_LOCK_STAT |
64 | int lock_stat = 1; |
65 | module_param(lock_stat, int, 0644); |
66 | #else |
67 | #define lock_stat 0 |
68 | #endif |
69 | |
70 | /* |
71 | * lockdep_lock: protects the lockdep graph, the hashes and the |
72 | * class/list/hash allocators. |
73 | * |
74 | * This is one of the rare exceptions where it's justified |
75 | * to use a raw spinlock - we really dont want the spinlock |
76 | * code to recurse back into the lockdep code... |
77 | */ |
78 | static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
79 | |
80 | static int graph_lock(void) |
81 | { |
82 | arch_spin_lock(&lockdep_lock); |
83 | /* |
84 | * Make sure that if another CPU detected a bug while |
85 | * walking the graph we dont change it (while the other |
86 | * CPU is busy printing out stuff with the graph lock |
87 | * dropped already) |
88 | */ |
89 | if (!debug_locks) { |
90 | arch_spin_unlock(&lockdep_lock); |
91 | return 0; |
92 | } |
93 | /* prevent any recursions within lockdep from causing deadlocks */ |
94 | current->lockdep_recursion++; |
95 | return 1; |
96 | } |
97 | |
98 | static inline int graph_unlock(void) |
99 | { |
100 | if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) { |
101 | /* |
102 | * The lockdep graph lock isn't locked while we expect it to |
103 | * be, we're confused now, bye! |
104 | */ |
105 | return DEBUG_LOCKS_WARN_ON(1); |
106 | } |
107 | |
108 | current->lockdep_recursion--; |
109 | arch_spin_unlock(&lockdep_lock); |
110 | return 0; |
111 | } |
112 | |
113 | /* |
114 | * Turn lock debugging off and return with 0 if it was off already, |
115 | * and also release the graph lock: |
116 | */ |
117 | static inline int debug_locks_off_graph_unlock(void) |
118 | { |
119 | int ret = debug_locks_off(); |
120 | |
121 | arch_spin_unlock(&lockdep_lock); |
122 | |
123 | return ret; |
124 | } |
125 | |
126 | static int lockdep_initialized; |
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], |
154 | cpu_lock_stats); |
155 | |
156 | static inline u64 lockstat_clock(void) |
157 | { |
158 | return local_clock(); |
159 | } |
160 | |
161 | static int lock_point(unsigned long points[], unsigned long ip) |
162 | { |
163 | int i; |
164 | |
165 | for (i = 0; i < LOCKSTAT_POINTS; i++) { |
166 | if (points[i] == 0) { |
167 | points[i] = ip; |
168 | break; |
169 | } |
170 | if (points[i] == ip) |
171 | break; |
172 | } |
173 | |
174 | return i; |
175 | } |
176 | |
177 | static void lock_time_inc(struct lock_time *lt, u64 time) |
178 | { |
179 | if (time > lt->max) |
180 | lt->max = time; |
181 | |
182 | if (time < lt->min || !lt->nr) |
183 | lt->min = time; |
184 | |
185 | lt->total += time; |
186 | lt->nr++; |
187 | } |
188 | |
189 | static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) |
190 | { |
191 | if (!src->nr) |
192 | return; |
193 | |
194 | if (src->max > dst->max) |
195 | dst->max = src->max; |
196 | |
197 | if (src->min < dst->min || !dst->nr) |
198 | dst->min = src->min; |
199 | |
200 | dst->total += src->total; |
201 | dst->nr += src->nr; |
202 | } |
203 | |
204 | struct lock_class_stats lock_stats(struct lock_class *class) |
205 | { |
206 | struct lock_class_stats stats; |
207 | int cpu, i; |
208 | |
209 | memset(&stats, 0, sizeof(struct lock_class_stats)); |
210 | for_each_possible_cpu(cpu) { |
211 | struct lock_class_stats *pcs = |
212 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
213 | |
214 | for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) |
215 | stats.contention_point[i] += pcs->contention_point[i]; |
216 | |
217 | for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) |
218 | stats.contending_point[i] += pcs->contending_point[i]; |
219 | |
220 | lock_time_add(&pcs->read_waittime, &stats.read_waittime); |
221 | lock_time_add(&pcs->write_waittime, &stats.write_waittime); |
222 | |
223 | lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); |
224 | lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); |
225 | |
226 | for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) |
227 | stats.bounces[i] += pcs->bounces[i]; |
228 | } |
229 | |
230 | return stats; |
231 | } |
232 | |
233 | void clear_lock_stats(struct lock_class *class) |
234 | { |
235 | int cpu; |
236 | |
237 | for_each_possible_cpu(cpu) { |
238 | struct lock_class_stats *cpu_stats = |
239 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
240 | |
241 | memset(cpu_stats, 0, sizeof(struct lock_class_stats)); |
242 | } |
243 | memset(class->contention_point, 0, sizeof(class->contention_point)); |
244 | memset(class->contending_point, 0, sizeof(class->contending_point)); |
245 | } |
246 | |
247 | static struct lock_class_stats *get_lock_stats(struct lock_class *class) |
248 | { |
249 | return &get_cpu_var(cpu_lock_stats)[class - lock_classes]; |
250 | } |
251 | |
252 | static void put_lock_stats(struct lock_class_stats *stats) |
253 | { |
254 | put_cpu_var(cpu_lock_stats); |
255 | } |
256 | |
257 | static void lock_release_holdtime(struct held_lock *hlock) |
258 | { |
259 | struct lock_class_stats *stats; |
260 | u64 holdtime; |
261 | |
262 | if (!lock_stat) |
263 | return; |
264 | |
265 | holdtime = lockstat_clock() - hlock->holdtime_stamp; |
266 | |
267 | stats = get_lock_stats(hlock_class(hlock)); |
268 | if (hlock->read) |
269 | lock_time_inc(&stats->read_holdtime, holdtime); |
270 | else |
271 | lock_time_inc(&stats->write_holdtime, holdtime); |
272 | put_lock_stats(stats); |
273 | } |
274 | #else |
275 | static inline void lock_release_holdtime(struct held_lock *hlock) |
276 | { |
277 | } |
278 | #endif |
279 | |
280 | /* |
281 | * We keep a global list of all lock classes. The list only grows, |
282 | * never shrinks. The list is only accessed with the lockdep |
283 | * spinlock lock held. |
284 | */ |
285 | LIST_HEAD(all_lock_classes); |
286 | |
287 | /* |
288 | * The lockdep classes are in a hash-table as well, for fast lookup: |
289 | */ |
290 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) |
291 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) |
292 | #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) |
293 | #define classhashentry(key) (classhash_table + __classhashfn((key))) |
294 | |
295 | static struct list_head classhash_table[CLASSHASH_SIZE]; |
296 | |
297 | /* |
298 | * We put the lock dependency chains into a hash-table as well, to cache |
299 | * their existence: |
300 | */ |
301 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) |
302 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) |
303 | #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) |
304 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) |
305 | |
306 | static struct list_head chainhash_table[CHAINHASH_SIZE]; |
307 | |
308 | /* |
309 | * The hash key of the lock dependency chains is a hash itself too: |
310 | * it's a hash of all locks taken up to that lock, including that lock. |
311 | * It's a 64-bit hash, because it's important for the keys to be |
312 | * unique. |
313 | */ |
314 | #define iterate_chain_key(key1, key2) \ |
315 | (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \ |
316 | ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \ |
317 | (key2)) |
318 | |
319 | void lockdep_off(void) |
320 | { |
321 | current->lockdep_recursion++; |
322 | } |
323 | EXPORT_SYMBOL(lockdep_off); |
324 | |
325 | void lockdep_on(void) |
326 | { |
327 | current->lockdep_recursion--; |
328 | } |
329 | EXPORT_SYMBOL(lockdep_on); |
330 | |
331 | /* |
332 | * Debugging switches: |
333 | */ |
334 | |
335 | #define VERBOSE 0 |
336 | #define VERY_VERBOSE 0 |
337 | |
338 | #if VERBOSE |
339 | # define HARDIRQ_VERBOSE 1 |
340 | # define SOFTIRQ_VERBOSE 1 |
341 | # define RECLAIM_VERBOSE 1 |
342 | #else |
343 | # define HARDIRQ_VERBOSE 0 |
344 | # define SOFTIRQ_VERBOSE 0 |
345 | # define RECLAIM_VERBOSE 0 |
346 | #endif |
347 | |
348 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE |
349 | /* |
350 | * Quick filtering for interesting events: |
351 | */ |
352 | static int class_filter(struct lock_class *class) |
353 | { |
354 | #if 0 |
355 | /* Example */ |
356 | if (class->name_version == 1 && |
357 | !strcmp(class->name, "lockname")) |
358 | return 1; |
359 | if (class->name_version == 1 && |
360 | !strcmp(class->name, "&struct->lockfield")) |
361 | return 1; |
362 | #endif |
363 | /* Filter everything else. 1 would be to allow everything else */ |
364 | return 0; |
365 | } |
366 | #endif |
367 | |
368 | static int verbose(struct lock_class *class) |
369 | { |
370 | #if VERBOSE |
371 | return class_filter(class); |
372 | #endif |
373 | return 0; |
374 | } |
375 | |
376 | /* |
377 | * Stack-trace: tightly packed array of stack backtrace |
378 | * addresses. Protected by the graph_lock. |
379 | */ |
380 | unsigned long nr_stack_trace_entries; |
381 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; |
382 | |
383 | static int save_trace(struct stack_trace *trace) |
384 | { |
385 | trace->nr_entries = 0; |
386 | trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; |
387 | trace->entries = stack_trace + nr_stack_trace_entries; |
388 | |
389 | trace->skip = 3; |
390 | |
391 | save_stack_trace(trace); |
392 | |
393 | /* |
394 | * Some daft arches put -1 at the end to indicate its a full trace. |
395 | * |
396 | * <rant> this is buggy anyway, since it takes a whole extra entry so a |
397 | * complete trace that maxes out the entries provided will be reported |
398 | * as incomplete, friggin useless </rant> |
399 | */ |
400 | if (trace->nr_entries != 0 && |
401 | trace->entries[trace->nr_entries-1] == ULONG_MAX) |
402 | trace->nr_entries--; |
403 | |
404 | trace->max_entries = trace->nr_entries; |
405 | |
406 | nr_stack_trace_entries += trace->nr_entries; |
407 | |
408 | if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { |
409 | if (!debug_locks_off_graph_unlock()) |
410 | return 0; |
411 | |
412 | printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); |
413 | printk("turning off the locking correctness validator.\n"); |
414 | dump_stack(); |
415 | |
416 | return 0; |
417 | } |
418 | |
419 | return 1; |
420 | } |
421 | |
422 | unsigned int nr_hardirq_chains; |
423 | unsigned int nr_softirq_chains; |
424 | unsigned int nr_process_chains; |
425 | unsigned int max_lockdep_depth; |
426 | |
427 | #ifdef CONFIG_DEBUG_LOCKDEP |
428 | /* |
429 | * We cannot printk in early bootup code. Not even early_printk() |
430 | * might work. So we mark any initialization errors and printk |
431 | * about it later on, in lockdep_info(). |
432 | */ |
433 | static int lockdep_init_error; |
434 | static const char *lock_init_error; |
435 | static unsigned long lockdep_init_trace_data[20]; |
436 | static struct stack_trace lockdep_init_trace = { |
437 | .max_entries = ARRAY_SIZE(lockdep_init_trace_data), |
438 | .entries = lockdep_init_trace_data, |
439 | }; |
440 | |
441 | /* |
442 | * Various lockdep statistics: |
443 | */ |
444 | DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); |
445 | #endif |
446 | |
447 | /* |
448 | * Locking printouts: |
449 | */ |
450 | |
451 | #define __USAGE(__STATE) \ |
452 | [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ |
453 | [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ |
454 | [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ |
455 | [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", |
456 | |
457 | static const char *usage_str[] = |
458 | { |
459 | #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) |
460 | #include "lockdep_states.h" |
461 | #undef LOCKDEP_STATE |
462 | [LOCK_USED] = "INITIAL USE", |
463 | }; |
464 | |
465 | const char * __get_key_name(struct lockdep_subclass_key *key, char *str) |
466 | { |
467 | return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); |
468 | } |
469 | |
470 | static inline unsigned long lock_flag(enum lock_usage_bit bit) |
471 | { |
472 | return 1UL << bit; |
473 | } |
474 | |
475 | static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) |
476 | { |
477 | char c = '.'; |
478 | |
479 | if (class->usage_mask & lock_flag(bit + 2)) |
480 | c = '+'; |
481 | if (class->usage_mask & lock_flag(bit)) { |
482 | c = '-'; |
483 | if (class->usage_mask & lock_flag(bit + 2)) |
484 | c = '?'; |
485 | } |
486 | |
487 | return c; |
488 | } |
489 | |
490 | void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) |
491 | { |
492 | int i = 0; |
493 | |
494 | #define LOCKDEP_STATE(__STATE) \ |
495 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ |
496 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); |
497 | #include "lockdep_states.h" |
498 | #undef LOCKDEP_STATE |
499 | |
500 | usage[i] = '\0'; |
501 | } |
502 | |
503 | static void __print_lock_name(struct lock_class *class) |
504 | { |
505 | char str[KSYM_NAME_LEN]; |
506 | const char *name; |
507 | |
508 | name = class->name; |
509 | if (!name) { |
510 | name = __get_key_name(class->key, str); |
511 | printk("%s", name); |
512 | } else { |
513 | printk("%s", name); |
514 | if (class->name_version > 1) |
515 | printk("#%d", class->name_version); |
516 | if (class->subclass) |
517 | printk("/%d", class->subclass); |
518 | } |
519 | } |
520 | |
521 | static void print_lock_name(struct lock_class *class) |
522 | { |
523 | char usage[LOCK_USAGE_CHARS]; |
524 | |
525 | get_usage_chars(class, usage); |
526 | |
527 | printk(" ("); |
528 | __print_lock_name(class); |
529 | printk("){%s}", usage); |
530 | } |
531 | |
532 | static void print_lockdep_cache(struct lockdep_map *lock) |
533 | { |
534 | const char *name; |
535 | char str[KSYM_NAME_LEN]; |
536 | |
537 | name = lock->name; |
538 | if (!name) |
539 | name = __get_key_name(lock->key->subkeys, str); |
540 | |
541 | printk("%s", name); |
542 | } |
543 | |
544 | static void print_lock(struct held_lock *hlock) |
545 | { |
546 | print_lock_name(hlock_class(hlock)); |
547 | printk(", at: "); |
548 | print_ip_sym(hlock->acquire_ip); |
549 | } |
550 | |
551 | static void lockdep_print_held_locks(struct task_struct *curr) |
552 | { |
553 | int i, depth = curr->lockdep_depth; |
554 | |
555 | if (!depth) { |
556 | printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr)); |
557 | return; |
558 | } |
559 | printk("%d lock%s held by %s/%d:\n", |
560 | depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr)); |
561 | |
562 | for (i = 0; i < depth; i++) { |
563 | printk(" #%d: ", i); |
564 | print_lock(curr->held_locks + i); |
565 | } |
566 | } |
567 | |
568 | static void print_kernel_ident(void) |
569 | { |
570 | printk("%s %.*s %s\n", init_utsname()->release, |
571 | (int)strcspn(init_utsname()->version, " "), |
572 | init_utsname()->version, |
573 | print_tainted()); |
574 | } |
575 | |
576 | static int very_verbose(struct lock_class *class) |
577 | { |
578 | #if VERY_VERBOSE |
579 | return class_filter(class); |
580 | #endif |
581 | return 0; |
582 | } |
583 | |
584 | /* |
585 | * Is this the address of a static object: |
586 | */ |
587 | static int static_obj(void *obj) |
588 | { |
589 | unsigned long start = (unsigned long) &_stext, |
590 | end = (unsigned long) &_end, |
591 | addr = (unsigned long) obj; |
592 | |
593 | /* |
594 | * static variable? |
595 | */ |
596 | if ((addr >= start) && (addr < end)) |
597 | return 1; |
598 | |
599 | if (arch_is_kernel_data(addr)) |
600 | return 1; |
601 | |
602 | /* |
603 | * in-kernel percpu var? |
604 | */ |
605 | if (is_kernel_percpu_address(addr)) |
606 | return 1; |
607 | |
608 | /* |
609 | * module static or percpu var? |
610 | */ |
611 | return is_module_address(addr) || is_module_percpu_address(addr); |
612 | } |
613 | |
614 | /* |
615 | * To make lock name printouts unique, we calculate a unique |
616 | * class->name_version generation counter: |
617 | */ |
618 | static int count_matching_names(struct lock_class *new_class) |
619 | { |
620 | struct lock_class *class; |
621 | int count = 0; |
622 | |
623 | if (!new_class->name) |
624 | return 0; |
625 | |
626 | list_for_each_entry(class, &all_lock_classes, lock_entry) { |
627 | if (new_class->key - new_class->subclass == class->key) |
628 | return class->name_version; |
629 | if (class->name && !strcmp(class->name, new_class->name)) |
630 | count = max(count, class->name_version); |
631 | } |
632 | |
633 | return count + 1; |
634 | } |
635 | |
636 | /* |
637 | * Register a lock's class in the hash-table, if the class is not present |
638 | * yet. Otherwise we look it up. We cache the result in the lock object |
639 | * itself, so actual lookup of the hash should be once per lock object. |
640 | */ |
641 | static inline struct lock_class * |
642 | look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) |
643 | { |
644 | struct lockdep_subclass_key *key; |
645 | struct list_head *hash_head; |
646 | struct lock_class *class; |
647 | |
648 | #ifdef CONFIG_DEBUG_LOCKDEP |
649 | /* |
650 | * If the architecture calls into lockdep before initializing |
651 | * the hashes then we'll warn about it later. (we cannot printk |
652 | * right now) |
653 | */ |
654 | if (unlikely(!lockdep_initialized)) { |
655 | lockdep_init(); |
656 | lockdep_init_error = 1; |
657 | lock_init_error = lock->name; |
658 | save_stack_trace(&lockdep_init_trace); |
659 | } |
660 | #endif |
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 can walk the hash lockfree, because the hash only |
694 | * grows, and we are careful when adding entries to the end: |
695 | */ |
696 | list_for_each_entry(class, hash_head, hash_entry) { |
697 | if (class->key == key) { |
698 | /* |
699 | * Huh! same key, different name? Did someone trample |
700 | * on some memory? We're most confused. |
701 | */ |
702 | WARN_ON_ONCE(class->name != lock->name); |
703 | return class; |
704 | } |
705 | } |
706 | |
707 | return NULL; |
708 | } |
709 | |
710 | /* |
711 | * Register a lock's class in the hash-table, if the class is not present |
712 | * yet. Otherwise we look it up. We cache the result in the lock object |
713 | * itself, so actual lookup of the hash should be once per lock object. |
714 | */ |
715 | static inline struct lock_class * |
716 | register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) |
717 | { |
718 | struct lockdep_subclass_key *key; |
719 | struct list_head *hash_head; |
720 | struct lock_class *class; |
721 | unsigned long flags; |
722 | |
723 | class = look_up_lock_class(lock, subclass); |
724 | if (likely(class)) |
725 | goto out_set_class_cache; |
726 | |
727 | /* |
728 | * Debug-check: all keys must be persistent! |
729 | */ |
730 | if (!static_obj(lock->key)) { |
731 | debug_locks_off(); |
732 | printk("INFO: trying to register non-static key.\n"); |
733 | printk("the code is fine but needs lockdep annotation.\n"); |
734 | printk("turning off the locking correctness validator.\n"); |
735 | dump_stack(); |
736 | |
737 | return NULL; |
738 | } |
739 | |
740 | key = lock->key->subkeys + subclass; |
741 | hash_head = classhashentry(key); |
742 | |
743 | raw_local_irq_save(flags); |
744 | if (!graph_lock()) { |
745 | raw_local_irq_restore(flags); |
746 | return NULL; |
747 | } |
748 | /* |
749 | * We have to do the hash-walk again, to avoid races |
750 | * with another CPU: |
751 | */ |
752 | list_for_each_entry(class, hash_head, hash_entry) |
753 | if (class->key == key) |
754 | goto out_unlock_set; |
755 | /* |
756 | * Allocate a new key from the static array, and add it to |
757 | * the hash: |
758 | */ |
759 | if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { |
760 | if (!debug_locks_off_graph_unlock()) { |
761 | raw_local_irq_restore(flags); |
762 | return NULL; |
763 | } |
764 | raw_local_irq_restore(flags); |
765 | |
766 | printk("BUG: MAX_LOCKDEP_KEYS too low!\n"); |
767 | printk("turning off the locking correctness validator.\n"); |
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 | list_add_tail_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 | raw_local_irq_restore(flags); |
793 | |
794 | printk("\nnew class %p: %s", class->key, class->name); |
795 | if (class->name_version > 1) |
796 | printk("#%d", class->name_version); |
797 | printk("\n"); |
798 | dump_stack(); |
799 | |
800 | raw_local_irq_save(flags); |
801 | if (!graph_lock()) { |
802 | raw_local_irq_restore(flags); |
803 | return NULL; |
804 | } |
805 | } |
806 | out_unlock_set: |
807 | graph_unlock(); |
808 | raw_local_irq_restore(flags); |
809 | |
810 | out_set_class_cache: |
811 | if (!subclass || force) |
812 | lock->class_cache[0] = class; |
813 | else if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
814 | lock->class_cache[subclass] = class; |
815 | |
816 | /* |
817 | * Hash collision, did we smoke some? We found a class with a matching |
818 | * hash but the subclass -- which is hashed in -- didn't match. |
819 | */ |
820 | if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) |
821 | return NULL; |
822 | |
823 | return class; |
824 | } |
825 | |
826 | #ifdef CONFIG_PROVE_LOCKING |
827 | /* |
828 | * Allocate a lockdep entry. (assumes the graph_lock held, returns |
829 | * with NULL on failure) |
830 | */ |
831 | static struct lock_list *alloc_list_entry(void) |
832 | { |
833 | if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { |
834 | if (!debug_locks_off_graph_unlock()) |
835 | return NULL; |
836 | |
837 | printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n"); |
838 | printk("turning off the locking correctness validator.\n"); |
839 | dump_stack(); |
840 | return NULL; |
841 | } |
842 | return list_entries + nr_list_entries++; |
843 | } |
844 | |
845 | /* |
846 | * Add a new dependency to the head of the list: |
847 | */ |
848 | static int add_lock_to_list(struct lock_class *class, struct lock_class *this, |
849 | struct list_head *head, unsigned long ip, |
850 | int distance, struct stack_trace *trace) |
851 | { |
852 | struct lock_list *entry; |
853 | /* |
854 | * Lock not present yet - get a new dependency struct and |
855 | * add it to the list: |
856 | */ |
857 | entry = alloc_list_entry(); |
858 | if (!entry) |
859 | return 0; |
860 | |
861 | entry->class = this; |
862 | entry->distance = distance; |
863 | entry->trace = *trace; |
864 | /* |
865 | * Since we never remove from the dependency list, the list can |
866 | * be walked lockless by other CPUs, it's only allocation |
867 | * that must be protected by the spinlock. But this also means |
868 | * we must make new entries visible only once writes to the |
869 | * entry become visible - hence the RCU op: |
870 | */ |
871 | list_add_tail_rcu(&entry->entry, head); |
872 | |
873 | return 1; |
874 | } |
875 | |
876 | /* |
877 | * For good efficiency of modular, we use power of 2 |
878 | */ |
879 | #define MAX_CIRCULAR_QUEUE_SIZE 4096UL |
880 | #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) |
881 | |
882 | /* |
883 | * The circular_queue and helpers is used to implement the |
884 | * breadth-first search(BFS)algorithem, by which we can build |
885 | * the shortest path from the next lock to be acquired to the |
886 | * previous held lock if there is a circular between them. |
887 | */ |
888 | struct circular_queue { |
889 | unsigned long element[MAX_CIRCULAR_QUEUE_SIZE]; |
890 | unsigned int front, rear; |
891 | }; |
892 | |
893 | static struct circular_queue lock_cq; |
894 | |
895 | unsigned int max_bfs_queue_depth; |
896 | |
897 | static unsigned int lockdep_dependency_gen_id; |
898 | |
899 | static inline void __cq_init(struct circular_queue *cq) |
900 | { |
901 | cq->front = cq->rear = 0; |
902 | lockdep_dependency_gen_id++; |
903 | } |
904 | |
905 | static inline int __cq_empty(struct circular_queue *cq) |
906 | { |
907 | return (cq->front == cq->rear); |
908 | } |
909 | |
910 | static inline int __cq_full(struct circular_queue *cq) |
911 | { |
912 | return ((cq->rear + 1) & CQ_MASK) == cq->front; |
913 | } |
914 | |
915 | static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) |
916 | { |
917 | if (__cq_full(cq)) |
918 | return -1; |
919 | |
920 | cq->element[cq->rear] = elem; |
921 | cq->rear = (cq->rear + 1) & CQ_MASK; |
922 | return 0; |
923 | } |
924 | |
925 | static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) |
926 | { |
927 | if (__cq_empty(cq)) |
928 | return -1; |
929 | |
930 | *elem = cq->element[cq->front]; |
931 | cq->front = (cq->front + 1) & CQ_MASK; |
932 | return 0; |
933 | } |
934 | |
935 | static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) |
936 | { |
937 | return (cq->rear - cq->front) & CQ_MASK; |
938 | } |
939 | |
940 | static inline void mark_lock_accessed(struct lock_list *lock, |
941 | struct lock_list *parent) |
942 | { |
943 | unsigned long nr; |
944 | |
945 | nr = lock - list_entries; |
946 | WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ |
947 | lock->parent = parent; |
948 | lock->class->dep_gen_id = lockdep_dependency_gen_id; |
949 | } |
950 | |
951 | static inline unsigned long lock_accessed(struct lock_list *lock) |
952 | { |
953 | unsigned long nr; |
954 | |
955 | nr = lock - list_entries; |
956 | WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ |
957 | return lock->class->dep_gen_id == lockdep_dependency_gen_id; |
958 | } |
959 | |
960 | static inline struct lock_list *get_lock_parent(struct lock_list *child) |
961 | { |
962 | return child->parent; |
963 | } |
964 | |
965 | static inline int get_lock_depth(struct lock_list *child) |
966 | { |
967 | int depth = 0; |
968 | struct lock_list *parent; |
969 | |
970 | while ((parent = get_lock_parent(child))) { |
971 | child = parent; |
972 | depth++; |
973 | } |
974 | return depth; |
975 | } |
976 | |
977 | static int __bfs(struct lock_list *source_entry, |
978 | void *data, |
979 | int (*match)(struct lock_list *entry, void *data), |
980 | struct lock_list **target_entry, |
981 | int forward) |
982 | { |
983 | struct lock_list *entry; |
984 | struct list_head *head; |
985 | struct circular_queue *cq = &lock_cq; |
986 | int ret = 1; |
987 | |
988 | if (match(source_entry, data)) { |
989 | *target_entry = source_entry; |
990 | ret = 0; |
991 | goto exit; |
992 | } |
993 | |
994 | if (forward) |
995 | head = &source_entry->class->locks_after; |
996 | else |
997 | head = &source_entry->class->locks_before; |
998 | |
999 | if (list_empty(head)) |
1000 | goto exit; |
1001 | |
1002 | __cq_init(cq); |
1003 | __cq_enqueue(cq, (unsigned long)source_entry); |
1004 | |
1005 | while (!__cq_empty(cq)) { |
1006 | struct lock_list *lock; |
1007 | |
1008 | __cq_dequeue(cq, (unsigned long *)&lock); |
1009 | |
1010 | if (!lock->class) { |
1011 | ret = -2; |
1012 | goto exit; |
1013 | } |
1014 | |
1015 | if (forward) |
1016 | head = &lock->class->locks_after; |
1017 | else |
1018 | head = &lock->class->locks_before; |
1019 | |
1020 | list_for_each_entry(entry, head, entry) { |
1021 | if (!lock_accessed(entry)) { |
1022 | unsigned int cq_depth; |
1023 | mark_lock_accessed(entry, lock); |
1024 | if (match(entry, data)) { |
1025 | *target_entry = entry; |
1026 | ret = 0; |
1027 | goto exit; |
1028 | } |
1029 | |
1030 | if (__cq_enqueue(cq, (unsigned long)entry)) { |
1031 | ret = -1; |
1032 | goto exit; |
1033 | } |
1034 | cq_depth = __cq_get_elem_count(cq); |
1035 | if (max_bfs_queue_depth < cq_depth) |
1036 | max_bfs_queue_depth = cq_depth; |
1037 | } |
1038 | } |
1039 | } |
1040 | exit: |
1041 | return ret; |
1042 | } |
1043 | |
1044 | static inline int __bfs_forwards(struct lock_list *src_entry, |
1045 | void *data, |
1046 | int (*match)(struct lock_list *entry, void *data), |
1047 | struct lock_list **target_entry) |
1048 | { |
1049 | return __bfs(src_entry, data, match, target_entry, 1); |
1050 | |
1051 | } |
1052 | |
1053 | static inline int __bfs_backwards(struct lock_list *src_entry, |
1054 | void *data, |
1055 | int (*match)(struct lock_list *entry, void *data), |
1056 | struct lock_list **target_entry) |
1057 | { |
1058 | return __bfs(src_entry, data, match, target_entry, 0); |
1059 | |
1060 | } |
1061 | |
1062 | /* |
1063 | * Recursive, forwards-direction lock-dependency checking, used for |
1064 | * both noncyclic checking and for hardirq-unsafe/softirq-unsafe |
1065 | * checking. |
1066 | */ |
1067 | |
1068 | /* |
1069 | * Print a dependency chain entry (this is only done when a deadlock |
1070 | * has been detected): |
1071 | */ |
1072 | static noinline int |
1073 | print_circular_bug_entry(struct lock_list *target, int depth) |
1074 | { |
1075 | if (debug_locks_silent) |
1076 | return 0; |
1077 | printk("\n-> #%u", depth); |
1078 | print_lock_name(target->class); |
1079 | printk(":\n"); |
1080 | print_stack_trace(&target->trace, 6); |
1081 | |
1082 | return 0; |
1083 | } |
1084 | |
1085 | static void |
1086 | print_circular_lock_scenario(struct held_lock *src, |
1087 | struct held_lock *tgt, |
1088 | struct lock_list *prt) |
1089 | { |
1090 | struct lock_class *source = hlock_class(src); |
1091 | struct lock_class *target = hlock_class(tgt); |
1092 | struct lock_class *parent = prt->class; |
1093 | |
1094 | /* |
1095 | * A direct locking problem where unsafe_class lock is taken |
1096 | * directly by safe_class lock, then all we need to show |
1097 | * is the deadlock scenario, as it is obvious that the |
1098 | * unsafe lock is taken under the safe lock. |
1099 | * |
1100 | * But if there is a chain instead, where the safe lock takes |
1101 | * an intermediate lock (middle_class) where this lock is |
1102 | * not the same as the safe lock, then the lock chain is |
1103 | * used to describe the problem. Otherwise we would need |
1104 | * to show a different CPU case for each link in the chain |
1105 | * from the safe_class lock to the unsafe_class lock. |
1106 | */ |
1107 | if (parent != source) { |
1108 | printk("Chain exists of:\n "); |
1109 | __print_lock_name(source); |
1110 | printk(" --> "); |
1111 | __print_lock_name(parent); |
1112 | printk(" --> "); |
1113 | __print_lock_name(target); |
1114 | printk("\n\n"); |
1115 | } |
1116 | |
1117 | printk(" Possible unsafe locking scenario:\n\n"); |
1118 | printk(" CPU0 CPU1\n"); |
1119 | printk(" ---- ----\n"); |
1120 | printk(" lock("); |
1121 | __print_lock_name(target); |
1122 | printk(");\n"); |
1123 | printk(" lock("); |
1124 | __print_lock_name(parent); |
1125 | printk(");\n"); |
1126 | printk(" lock("); |
1127 | __print_lock_name(target); |
1128 | printk(");\n"); |
1129 | printk(" lock("); |
1130 | __print_lock_name(source); |
1131 | printk(");\n"); |
1132 | printk("\n *** DEADLOCK ***\n\n"); |
1133 | } |
1134 | |
1135 | /* |
1136 | * When a circular dependency is detected, print the |
1137 | * header first: |
1138 | */ |
1139 | static noinline int |
1140 | print_circular_bug_header(struct lock_list *entry, unsigned int depth, |
1141 | struct held_lock *check_src, |
1142 | struct held_lock *check_tgt) |
1143 | { |
1144 | struct task_struct *curr = current; |
1145 | |
1146 | if (debug_locks_silent) |
1147 | return 0; |
1148 | |
1149 | printk("\n"); |
1150 | printk("======================================================\n"); |
1151 | printk("[ INFO: possible circular locking dependency detected ]\n"); |
1152 | print_kernel_ident(); |
1153 | printk("-------------------------------------------------------\n"); |
1154 | printk("%s/%d is trying to acquire lock:\n", |
1155 | curr->comm, task_pid_nr(curr)); |
1156 | print_lock(check_src); |
1157 | printk("\nbut task is already holding lock:\n"); |
1158 | print_lock(check_tgt); |
1159 | printk("\nwhich lock already depends on the new lock.\n\n"); |
1160 | printk("\nthe existing dependency chain (in reverse order) is:\n"); |
1161 | |
1162 | print_circular_bug_entry(entry, depth); |
1163 | |
1164 | return 0; |
1165 | } |
1166 | |
1167 | static inline int class_equal(struct lock_list *entry, void *data) |
1168 | { |
1169 | return entry->class == data; |
1170 | } |
1171 | |
1172 | static noinline int print_circular_bug(struct lock_list *this, |
1173 | struct lock_list *target, |
1174 | struct held_lock *check_src, |
1175 | struct held_lock *check_tgt) |
1176 | { |
1177 | struct task_struct *curr = current; |
1178 | struct lock_list *parent; |
1179 | struct lock_list *first_parent; |
1180 | int depth; |
1181 | |
1182 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
1183 | return 0; |
1184 | |
1185 | if (!save_trace(&this->trace)) |
1186 | return 0; |
1187 | |
1188 | depth = get_lock_depth(target); |
1189 | |
1190 | print_circular_bug_header(target, depth, check_src, check_tgt); |
1191 | |
1192 | parent = get_lock_parent(target); |
1193 | first_parent = parent; |
1194 | |
1195 | while (parent) { |
1196 | print_circular_bug_entry(parent, --depth); |
1197 | parent = get_lock_parent(parent); |
1198 | } |
1199 | |
1200 | printk("\nother info that might help us debug this:\n\n"); |
1201 | print_circular_lock_scenario(check_src, check_tgt, |
1202 | first_parent); |
1203 | |
1204 | lockdep_print_held_locks(curr); |
1205 | |
1206 | printk("\nstack backtrace:\n"); |
1207 | dump_stack(); |
1208 | |
1209 | return 0; |
1210 | } |
1211 | |
1212 | static noinline int print_bfs_bug(int ret) |
1213 | { |
1214 | if (!debug_locks_off_graph_unlock()) |
1215 | return 0; |
1216 | |
1217 | /* |
1218 | * Breadth-first-search failed, graph got corrupted? |
1219 | */ |
1220 | WARN(1, "lockdep bfs error:%d\n", ret); |
1221 | |
1222 | return 0; |
1223 | } |
1224 | |
1225 | static int noop_count(struct lock_list *entry, void *data) |
1226 | { |
1227 | (*(unsigned long *)data)++; |
1228 | return 0; |
1229 | } |
1230 | |
1231 | unsigned long __lockdep_count_forward_deps(struct lock_list *this) |
1232 | { |
1233 | unsigned long count = 0; |
1234 | struct lock_list *uninitialized_var(target_entry); |
1235 | |
1236 | __bfs_forwards(this, (void *)&count, noop_count, &target_entry); |
1237 | |
1238 | return count; |
1239 | } |
1240 | unsigned long lockdep_count_forward_deps(struct lock_class *class) |
1241 | { |
1242 | unsigned long ret, flags; |
1243 | struct lock_list this; |
1244 | |
1245 | this.parent = NULL; |
1246 | this.class = class; |
1247 | |
1248 | local_irq_save(flags); |
1249 | arch_spin_lock(&lockdep_lock); |
1250 | ret = __lockdep_count_forward_deps(&this); |
1251 | arch_spin_unlock(&lockdep_lock); |
1252 | local_irq_restore(flags); |
1253 | |
1254 | return ret; |
1255 | } |
1256 | |
1257 | unsigned long __lockdep_count_backward_deps(struct lock_list *this) |
1258 | { |
1259 | unsigned long count = 0; |
1260 | struct lock_list *uninitialized_var(target_entry); |
1261 | |
1262 | __bfs_backwards(this, (void *)&count, noop_count, &target_entry); |
1263 | |
1264 | return count; |
1265 | } |
1266 | |
1267 | unsigned long lockdep_count_backward_deps(struct lock_class *class) |
1268 | { |
1269 | unsigned long ret, flags; |
1270 | struct lock_list this; |
1271 | |
1272 | this.parent = NULL; |
1273 | this.class = class; |
1274 | |
1275 | local_irq_save(flags); |
1276 | arch_spin_lock(&lockdep_lock); |
1277 | ret = __lockdep_count_backward_deps(&this); |
1278 | arch_spin_unlock(&lockdep_lock); |
1279 | local_irq_restore(flags); |
1280 | |
1281 | return ret; |
1282 | } |
1283 | |
1284 | /* |
1285 | * Prove that the dependency graph starting at <entry> can not |
1286 | * lead to <target>. Print an error and return 0 if it does. |
1287 | */ |
1288 | static noinline int |
1289 | check_noncircular(struct lock_list *root, struct lock_class *target, |
1290 | struct lock_list **target_entry) |
1291 | { |
1292 | int result; |
1293 | |
1294 | debug_atomic_inc(nr_cyclic_checks); |
1295 | |
1296 | result = __bfs_forwards(root, target, class_equal, target_entry); |
1297 | |
1298 | return result; |
1299 | } |
1300 | |
1301 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
1302 | /* |
1303 | * Forwards and backwards subgraph searching, for the purposes of |
1304 | * proving that two subgraphs can be connected by a new dependency |
1305 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. |
1306 | */ |
1307 | |
1308 | static inline int usage_match(struct lock_list *entry, void *bit) |
1309 | { |
1310 | return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); |
1311 | } |
1312 | |
1313 | |
1314 | |
1315 | /* |
1316 | * Find a node in the forwards-direction dependency sub-graph starting |
1317 | * at @root->class that matches @bit. |
1318 | * |
1319 | * Return 0 if such a node exists in the subgraph, and put that node |
1320 | * into *@target_entry. |
1321 | * |
1322 | * Return 1 otherwise and keep *@target_entry unchanged. |
1323 | * Return <0 on error. |
1324 | */ |
1325 | static int |
1326 | find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, |
1327 | struct lock_list **target_entry) |
1328 | { |
1329 | int result; |
1330 | |
1331 | debug_atomic_inc(nr_find_usage_forwards_checks); |
1332 | |
1333 | result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); |
1334 | |
1335 | return result; |
1336 | } |
1337 | |
1338 | /* |
1339 | * Find a node in the backwards-direction dependency sub-graph starting |
1340 | * at @root->class that matches @bit. |
1341 | * |
1342 | * Return 0 if such a node exists in the subgraph, and put that node |
1343 | * into *@target_entry. |
1344 | * |
1345 | * Return 1 otherwise and keep *@target_entry unchanged. |
1346 | * Return <0 on error. |
1347 | */ |
1348 | static int |
1349 | find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, |
1350 | struct lock_list **target_entry) |
1351 | { |
1352 | int result; |
1353 | |
1354 | debug_atomic_inc(nr_find_usage_backwards_checks); |
1355 | |
1356 | result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); |
1357 | |
1358 | return result; |
1359 | } |
1360 | |
1361 | static void print_lock_class_header(struct lock_class *class, int depth) |
1362 | { |
1363 | int bit; |
1364 | |
1365 | printk("%*s->", depth, ""); |
1366 | print_lock_name(class); |
1367 | printk(" ops: %lu", class->ops); |
1368 | printk(" {\n"); |
1369 | |
1370 | for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { |
1371 | if (class->usage_mask & (1 << bit)) { |
1372 | int len = depth; |
1373 | |
1374 | len += printk("%*s %s", depth, "", usage_str[bit]); |
1375 | len += printk(" at:\n"); |
1376 | print_stack_trace(class->usage_traces + bit, len); |
1377 | } |
1378 | } |
1379 | printk("%*s }\n", depth, ""); |
1380 | |
1381 | printk("%*s ... key at: ",depth,""); |
1382 | print_ip_sym((unsigned long)class->key); |
1383 | } |
1384 | |
1385 | /* |
1386 | * printk the shortest lock dependencies from @start to @end in reverse order: |
1387 | */ |
1388 | static void __used |
1389 | print_shortest_lock_dependencies(struct lock_list *leaf, |
1390 | struct lock_list *root) |
1391 | { |
1392 | struct lock_list *entry = leaf; |
1393 | int depth; |
1394 | |
1395 | /*compute depth from generated tree by BFS*/ |
1396 | depth = get_lock_depth(leaf); |
1397 | |
1398 | do { |
1399 | print_lock_class_header(entry->class, depth); |
1400 | printk("%*s ... acquired at:\n", depth, ""); |
1401 | print_stack_trace(&entry->trace, 2); |
1402 | printk("\n"); |
1403 | |
1404 | if (depth == 0 && (entry != root)) { |
1405 | printk("lockdep:%s bad path found in chain graph\n", __func__); |
1406 | break; |
1407 | } |
1408 | |
1409 | entry = get_lock_parent(entry); |
1410 | depth--; |
1411 | } while (entry && (depth >= 0)); |
1412 | |
1413 | return; |
1414 | } |
1415 | |
1416 | static void |
1417 | print_irq_lock_scenario(struct lock_list *safe_entry, |
1418 | struct lock_list *unsafe_entry, |
1419 | struct lock_class *prev_class, |
1420 | struct lock_class *next_class) |
1421 | { |
1422 | struct lock_class *safe_class = safe_entry->class; |
1423 | struct lock_class *unsafe_class = unsafe_entry->class; |
1424 | struct lock_class *middle_class = prev_class; |
1425 | |
1426 | if (middle_class == safe_class) |
1427 | middle_class = next_class; |
1428 | |
1429 | /* |
1430 | * A direct locking problem where unsafe_class lock is taken |
1431 | * directly by safe_class lock, then all we need to show |
1432 | * is the deadlock scenario, as it is obvious that the |
1433 | * unsafe lock is taken under the safe lock. |
1434 | * |
1435 | * But if there is a chain instead, where the safe lock takes |
1436 | * an intermediate lock (middle_class) where this lock is |
1437 | * not the same as the safe lock, then the lock chain is |
1438 | * used to describe the problem. Otherwise we would need |
1439 | * to show a different CPU case for each link in the chain |
1440 | * from the safe_class lock to the unsafe_class lock. |
1441 | */ |
1442 | if (middle_class != unsafe_class) { |
1443 | printk("Chain exists of:\n "); |
1444 | __print_lock_name(safe_class); |
1445 | printk(" --> "); |
1446 | __print_lock_name(middle_class); |
1447 | printk(" --> "); |
1448 | __print_lock_name(unsafe_class); |
1449 | printk("\n\n"); |
1450 | } |
1451 | |
1452 | printk(" Possible interrupt unsafe locking scenario:\n\n"); |
1453 | printk(" CPU0 CPU1\n"); |
1454 | printk(" ---- ----\n"); |
1455 | printk(" lock("); |
1456 | __print_lock_name(unsafe_class); |
1457 | printk(");\n"); |
1458 | printk(" local_irq_disable();\n"); |
1459 | printk(" lock("); |
1460 | __print_lock_name(safe_class); |
1461 | printk(");\n"); |
1462 | printk(" lock("); |
1463 | __print_lock_name(middle_class); |
1464 | printk(");\n"); |
1465 | printk(" <Interrupt>\n"); |
1466 | printk(" lock("); |
1467 | __print_lock_name(safe_class); |
1468 | printk(");\n"); |
1469 | printk("\n *** DEADLOCK ***\n\n"); |
1470 | } |
1471 | |
1472 | static int |
1473 | print_bad_irq_dependency(struct task_struct *curr, |
1474 | struct lock_list *prev_root, |
1475 | struct lock_list *next_root, |
1476 | struct lock_list *backwards_entry, |
1477 | struct lock_list *forwards_entry, |
1478 | struct held_lock *prev, |
1479 | struct held_lock *next, |
1480 | enum lock_usage_bit bit1, |
1481 | enum lock_usage_bit bit2, |
1482 | const char *irqclass) |
1483 | { |
1484 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
1485 | return 0; |
1486 | |
1487 | printk("\n"); |
1488 | printk("======================================================\n"); |
1489 | printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", |
1490 | irqclass, irqclass); |
1491 | print_kernel_ident(); |
1492 | printk("------------------------------------------------------\n"); |
1493 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", |
1494 | curr->comm, task_pid_nr(curr), |
1495 | curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, |
1496 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, |
1497 | curr->hardirqs_enabled, |
1498 | curr->softirqs_enabled); |
1499 | print_lock(next); |
1500 | |
1501 | printk("\nand this task is already holding:\n"); |
1502 | print_lock(prev); |
1503 | printk("which would create a new lock dependency:\n"); |
1504 | print_lock_name(hlock_class(prev)); |
1505 | printk(" ->"); |
1506 | print_lock_name(hlock_class(next)); |
1507 | printk("\n"); |
1508 | |
1509 | printk("\nbut this new dependency connects a %s-irq-safe lock:\n", |
1510 | irqclass); |
1511 | print_lock_name(backwards_entry->class); |
1512 | printk("\n... which became %s-irq-safe at:\n", irqclass); |
1513 | |
1514 | print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); |
1515 | |
1516 | printk("\nto a %s-irq-unsafe lock:\n", irqclass); |
1517 | print_lock_name(forwards_entry->class); |
1518 | printk("\n... which became %s-irq-unsafe at:\n", irqclass); |
1519 | printk("..."); |
1520 | |
1521 | print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); |
1522 | |
1523 | printk("\nother info that might help us debug this:\n\n"); |
1524 | print_irq_lock_scenario(backwards_entry, forwards_entry, |
1525 | hlock_class(prev), hlock_class(next)); |
1526 | |
1527 | lockdep_print_held_locks(curr); |
1528 | |
1529 | printk("\nthe dependencies between %s-irq-safe lock", irqclass); |
1530 | printk(" and the holding lock:\n"); |
1531 | if (!save_trace(&prev_root->trace)) |
1532 | return 0; |
1533 | print_shortest_lock_dependencies(backwards_entry, prev_root); |
1534 | |
1535 | printk("\nthe dependencies between the lock to be acquired"); |
1536 | printk(" and %s-irq-unsafe lock:\n", irqclass); |
1537 | if (!save_trace(&next_root->trace)) |
1538 | return 0; |
1539 | print_shortest_lock_dependencies(forwards_entry, next_root); |
1540 | |
1541 | printk("\nstack backtrace:\n"); |
1542 | dump_stack(); |
1543 | |
1544 | return 0; |
1545 | } |
1546 | |
1547 | static int |
1548 | check_usage(struct task_struct *curr, struct held_lock *prev, |
1549 | struct held_lock *next, enum lock_usage_bit bit_backwards, |
1550 | enum lock_usage_bit bit_forwards, const char *irqclass) |
1551 | { |
1552 | int ret; |
1553 | struct lock_list this, that; |
1554 | struct lock_list *uninitialized_var(target_entry); |
1555 | struct lock_list *uninitialized_var(target_entry1); |
1556 | |
1557 | this.parent = NULL; |
1558 | |
1559 | this.class = hlock_class(prev); |
1560 | ret = find_usage_backwards(&this, bit_backwards, &target_entry); |
1561 | if (ret < 0) |
1562 | return print_bfs_bug(ret); |
1563 | if (ret == 1) |
1564 | return ret; |
1565 | |
1566 | that.parent = NULL; |
1567 | that.class = hlock_class(next); |
1568 | ret = find_usage_forwards(&that, bit_forwards, &target_entry1); |
1569 | if (ret < 0) |
1570 | return print_bfs_bug(ret); |
1571 | if (ret == 1) |
1572 | return ret; |
1573 | |
1574 | return print_bad_irq_dependency(curr, &this, &that, |
1575 | target_entry, target_entry1, |
1576 | prev, next, |
1577 | bit_backwards, bit_forwards, irqclass); |
1578 | } |
1579 | |
1580 | static const char *state_names[] = { |
1581 | #define LOCKDEP_STATE(__STATE) \ |
1582 | __stringify(__STATE), |
1583 | #include "lockdep_states.h" |
1584 | #undef LOCKDEP_STATE |
1585 | }; |
1586 | |
1587 | static const char *state_rnames[] = { |
1588 | #define LOCKDEP_STATE(__STATE) \ |
1589 | __stringify(__STATE)"-READ", |
1590 | #include "lockdep_states.h" |
1591 | #undef LOCKDEP_STATE |
1592 | }; |
1593 | |
1594 | static inline const char *state_name(enum lock_usage_bit bit) |
1595 | { |
1596 | return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2]; |
1597 | } |
1598 | |
1599 | static int exclusive_bit(int new_bit) |
1600 | { |
1601 | /* |
1602 | * USED_IN |
1603 | * USED_IN_READ |
1604 | * ENABLED |
1605 | * ENABLED_READ |
1606 | * |
1607 | * bit 0 - write/read |
1608 | * bit 1 - used_in/enabled |
1609 | * bit 2+ state |
1610 | */ |
1611 | |
1612 | int state = new_bit & ~3; |
1613 | int dir = new_bit & 2; |
1614 | |
1615 | /* |
1616 | * keep state, bit flip the direction and strip read. |
1617 | */ |
1618 | return state | (dir ^ 2); |
1619 | } |
1620 | |
1621 | static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, |
1622 | struct held_lock *next, enum lock_usage_bit bit) |
1623 | { |
1624 | /* |
1625 | * Prove that the new dependency does not connect a hardirq-safe |
1626 | * lock with a hardirq-unsafe lock - to achieve this we search |
1627 | * the backwards-subgraph starting at <prev>, and the |
1628 | * forwards-subgraph starting at <next>: |
1629 | */ |
1630 | if (!check_usage(curr, prev, next, bit, |
1631 | exclusive_bit(bit), state_name(bit))) |
1632 | return 0; |
1633 | |
1634 | bit++; /* _READ */ |
1635 | |
1636 | /* |
1637 | * Prove that the new dependency does not connect a hardirq-safe-read |
1638 | * lock with a hardirq-unsafe lock - to achieve this we search |
1639 | * the backwards-subgraph starting at <prev>, and the |
1640 | * forwards-subgraph starting at <next>: |
1641 | */ |
1642 | if (!check_usage(curr, prev, next, bit, |
1643 | exclusive_bit(bit), state_name(bit))) |
1644 | return 0; |
1645 | |
1646 | return 1; |
1647 | } |
1648 | |
1649 | static int |
1650 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, |
1651 | struct held_lock *next) |
1652 | { |
1653 | #define LOCKDEP_STATE(__STATE) \ |
1654 | if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ |
1655 | return 0; |
1656 | #include "lockdep_states.h" |
1657 | #undef LOCKDEP_STATE |
1658 | |
1659 | return 1; |
1660 | } |
1661 | |
1662 | static void inc_chains(void) |
1663 | { |
1664 | if (current->hardirq_context) |
1665 | nr_hardirq_chains++; |
1666 | else { |
1667 | if (current->softirq_context) |
1668 | nr_softirq_chains++; |
1669 | else |
1670 | nr_process_chains++; |
1671 | } |
1672 | } |
1673 | |
1674 | #else |
1675 | |
1676 | static inline int |
1677 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, |
1678 | struct held_lock *next) |
1679 | { |
1680 | return 1; |
1681 | } |
1682 | |
1683 | static inline void inc_chains(void) |
1684 | { |
1685 | nr_process_chains++; |
1686 | } |
1687 | |
1688 | #endif |
1689 | |
1690 | static void |
1691 | print_deadlock_scenario(struct held_lock *nxt, |
1692 | struct held_lock *prv) |
1693 | { |
1694 | struct lock_class *next = hlock_class(nxt); |
1695 | struct lock_class *prev = hlock_class(prv); |
1696 | |
1697 | printk(" Possible unsafe locking scenario:\n\n"); |
1698 | printk(" CPU0\n"); |
1699 | printk(" ----\n"); |
1700 | printk(" lock("); |
1701 | __print_lock_name(prev); |
1702 | printk(");\n"); |
1703 | printk(" lock("); |
1704 | __print_lock_name(next); |
1705 | printk(");\n"); |
1706 | printk("\n *** DEADLOCK ***\n\n"); |
1707 | printk(" May be due to missing lock nesting notation\n\n"); |
1708 | } |
1709 | |
1710 | static int |
1711 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, |
1712 | struct held_lock *next) |
1713 | { |
1714 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
1715 | return 0; |
1716 | |
1717 | printk("\n"); |
1718 | printk("=============================================\n"); |
1719 | printk("[ INFO: possible recursive locking detected ]\n"); |
1720 | print_kernel_ident(); |
1721 | printk("---------------------------------------------\n"); |
1722 | printk("%s/%d is trying to acquire lock:\n", |
1723 | curr->comm, task_pid_nr(curr)); |
1724 | print_lock(next); |
1725 | printk("\nbut task is already holding lock:\n"); |
1726 | print_lock(prev); |
1727 | |
1728 | printk("\nother info that might help us debug this:\n"); |
1729 | print_deadlock_scenario(next, prev); |
1730 | lockdep_print_held_locks(curr); |
1731 | |
1732 | printk("\nstack backtrace:\n"); |
1733 | dump_stack(); |
1734 | |
1735 | return 0; |
1736 | } |
1737 | |
1738 | /* |
1739 | * Check whether we are holding such a class already. |
1740 | * |
1741 | * (Note that this has to be done separately, because the graph cannot |
1742 | * detect such classes of deadlocks.) |
1743 | * |
1744 | * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read |
1745 | */ |
1746 | static int |
1747 | check_deadlock(struct task_struct *curr, struct held_lock *next, |
1748 | struct lockdep_map *next_instance, int read) |
1749 | { |
1750 | struct held_lock *prev; |
1751 | struct held_lock *nest = NULL; |
1752 | int i; |
1753 | |
1754 | for (i = 0; i < curr->lockdep_depth; i++) { |
1755 | prev = curr->held_locks + i; |
1756 | |
1757 | if (prev->instance == next->nest_lock) |
1758 | nest = prev; |
1759 | |
1760 | if (hlock_class(prev) != hlock_class(next)) |
1761 | continue; |
1762 | |
1763 | /* |
1764 | * Allow read-after-read recursion of the same |
1765 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
1766 | */ |
1767 | if ((read == 2) && prev->read) |
1768 | return 2; |
1769 | |
1770 | /* |
1771 | * We're holding the nest_lock, which serializes this lock's |
1772 | * nesting behaviour. |
1773 | */ |
1774 | if (nest) |
1775 | return 2; |
1776 | |
1777 | return print_deadlock_bug(curr, prev, next); |
1778 | } |
1779 | return 1; |
1780 | } |
1781 | |
1782 | /* |
1783 | * There was a chain-cache miss, and we are about to add a new dependency |
1784 | * to a previous lock. We recursively validate the following rules: |
1785 | * |
1786 | * - would the adding of the <prev> -> <next> dependency create a |
1787 | * circular dependency in the graph? [== circular deadlock] |
1788 | * |
1789 | * - does the new prev->next dependency connect any hardirq-safe lock |
1790 | * (in the full backwards-subgraph starting at <prev>) with any |
1791 | * hardirq-unsafe lock (in the full forwards-subgraph starting at |
1792 | * <next>)? [== illegal lock inversion with hardirq contexts] |
1793 | * |
1794 | * - does the new prev->next dependency connect any softirq-safe lock |
1795 | * (in the full backwards-subgraph starting at <prev>) with any |
1796 | * softirq-unsafe lock (in the full forwards-subgraph starting at |
1797 | * <next>)? [== illegal lock inversion with softirq contexts] |
1798 | * |
1799 | * any of these scenarios could lead to a deadlock. |
1800 | * |
1801 | * Then if all the validations pass, we add the forwards and backwards |
1802 | * dependency. |
1803 | */ |
1804 | static int |
1805 | check_prev_add(struct task_struct *curr, struct held_lock *prev, |
1806 | struct held_lock *next, int distance, int trylock_loop) |
1807 | { |
1808 | struct lock_list *entry; |
1809 | int ret; |
1810 | struct lock_list this; |
1811 | struct lock_list *uninitialized_var(target_entry); |
1812 | /* |
1813 | * Static variable, serialized by the graph_lock(). |
1814 | * |
1815 | * We use this static variable to save the stack trace in case |
1816 | * we call into this function multiple times due to encountering |
1817 | * trylocks in the held lock stack. |
1818 | */ |
1819 | static struct stack_trace trace; |
1820 | |
1821 | /* |
1822 | * Prove that the new <prev> -> <next> dependency would not |
1823 | * create a circular dependency in the graph. (We do this by |
1824 | * forward-recursing into the graph starting at <next>, and |
1825 | * checking whether we can reach <prev>.) |
1826 | * |
1827 | * We are using global variables to control the recursion, to |
1828 | * keep the stackframe size of the recursive functions low: |
1829 | */ |
1830 | this.class = hlock_class(next); |
1831 | this.parent = NULL; |
1832 | ret = check_noncircular(&this, hlock_class(prev), &target_entry); |
1833 | if (unlikely(!ret)) |
1834 | return print_circular_bug(&this, target_entry, next, prev); |
1835 | else if (unlikely(ret < 0)) |
1836 | return print_bfs_bug(ret); |
1837 | |
1838 | if (!check_prev_add_irq(curr, prev, next)) |
1839 | return 0; |
1840 | |
1841 | /* |
1842 | * For recursive read-locks we do all the dependency checks, |
1843 | * but we dont store read-triggered dependencies (only |
1844 | * write-triggered dependencies). This ensures that only the |
1845 | * write-side dependencies matter, and that if for example a |
1846 | * write-lock never takes any other locks, then the reads are |
1847 | * equivalent to a NOP. |
1848 | */ |
1849 | if (next->read == 2 || prev->read == 2) |
1850 | return 1; |
1851 | /* |
1852 | * Is the <prev> -> <next> dependency already present? |
1853 | * |
1854 | * (this may occur even though this is a new chain: consider |
1855 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 |
1856 | * chains - the second one will be new, but L1 already has |
1857 | * L2 added to its dependency list, due to the first chain.) |
1858 | */ |
1859 | list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { |
1860 | if (entry->class == hlock_class(next)) { |
1861 | if (distance == 1) |
1862 | entry->distance = 1; |
1863 | return 2; |
1864 | } |
1865 | } |
1866 | |
1867 | if (!trylock_loop && !save_trace(&trace)) |
1868 | return 0; |
1869 | |
1870 | /* |
1871 | * Ok, all validations passed, add the new lock |
1872 | * to the previous lock's dependency list: |
1873 | */ |
1874 | ret = add_lock_to_list(hlock_class(prev), hlock_class(next), |
1875 | &hlock_class(prev)->locks_after, |
1876 | next->acquire_ip, distance, &trace); |
1877 | |
1878 | if (!ret) |
1879 | return 0; |
1880 | |
1881 | ret = add_lock_to_list(hlock_class(next), hlock_class(prev), |
1882 | &hlock_class(next)->locks_before, |
1883 | next->acquire_ip, distance, &trace); |
1884 | if (!ret) |
1885 | return 0; |
1886 | |
1887 | /* |
1888 | * Debugging printouts: |
1889 | */ |
1890 | if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) { |
1891 | graph_unlock(); |
1892 | printk("\n new dependency: "); |
1893 | print_lock_name(hlock_class(prev)); |
1894 | printk(" => "); |
1895 | print_lock_name(hlock_class(next)); |
1896 | printk("\n"); |
1897 | dump_stack(); |
1898 | return graph_lock(); |
1899 | } |
1900 | return 1; |
1901 | } |
1902 | |
1903 | /* |
1904 | * Add the dependency to all directly-previous locks that are 'relevant'. |
1905 | * The ones that are relevant are (in increasing distance from curr): |
1906 | * all consecutive trylock entries and the final non-trylock entry - or |
1907 | * the end of this context's lock-chain - whichever comes first. |
1908 | */ |
1909 | static int |
1910 | check_prevs_add(struct task_struct *curr, struct held_lock *next) |
1911 | { |
1912 | int depth = curr->lockdep_depth; |
1913 | int trylock_loop = 0; |
1914 | struct held_lock *hlock; |
1915 | |
1916 | /* |
1917 | * Debugging checks. |
1918 | * |
1919 | * Depth must not be zero for a non-head lock: |
1920 | */ |
1921 | if (!depth) |
1922 | goto out_bug; |
1923 | /* |
1924 | * At least two relevant locks must exist for this |
1925 | * to be a head: |
1926 | */ |
1927 | if (curr->held_locks[depth].irq_context != |
1928 | curr->held_locks[depth-1].irq_context) |
1929 | goto out_bug; |
1930 | |
1931 | for (;;) { |
1932 | int distance = curr->lockdep_depth - depth + 1; |
1933 | hlock = curr->held_locks + depth-1; |
1934 | /* |
1935 | * Only non-recursive-read entries get new dependencies |
1936 | * added: |
1937 | */ |
1938 | if (hlock->read != 2) { |
1939 | if (!check_prev_add(curr, hlock, next, |
1940 | distance, trylock_loop)) |
1941 | return 0; |
1942 | /* |
1943 | * Stop after the first non-trylock entry, |
1944 | * as non-trylock entries have added their |
1945 | * own direct dependencies already, so this |
1946 | * lock is connected to them indirectly: |
1947 | */ |
1948 | if (!hlock->trylock) |
1949 | break; |
1950 | } |
1951 | depth--; |
1952 | /* |
1953 | * End of lock-stack? |
1954 | */ |
1955 | if (!depth) |
1956 | break; |
1957 | /* |
1958 | * Stop the search if we cross into another context: |
1959 | */ |
1960 | if (curr->held_locks[depth].irq_context != |
1961 | curr->held_locks[depth-1].irq_context) |
1962 | break; |
1963 | trylock_loop = 1; |
1964 | } |
1965 | return 1; |
1966 | out_bug: |
1967 | if (!debug_locks_off_graph_unlock()) |
1968 | return 0; |
1969 | |
1970 | /* |
1971 | * Clearly we all shouldn't be here, but since we made it we |
1972 | * can reliable say we messed up our state. See the above two |
1973 | * gotos for reasons why we could possibly end up here. |
1974 | */ |
1975 | WARN_ON(1); |
1976 | |
1977 | return 0; |
1978 | } |
1979 | |
1980 | unsigned long nr_lock_chains; |
1981 | struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; |
1982 | int nr_chain_hlocks; |
1983 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; |
1984 | |
1985 | struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) |
1986 | { |
1987 | return lock_classes + chain_hlocks[chain->base + i]; |
1988 | } |
1989 | |
1990 | /* |
1991 | * Look up a dependency chain. If the key is not present yet then |
1992 | * add it and return 1 - in this case the new dependency chain is |
1993 | * validated. If the key is already hashed, return 0. |
1994 | * (On return with 1 graph_lock is held.) |
1995 | */ |
1996 | static inline int lookup_chain_cache(struct task_struct *curr, |
1997 | struct held_lock *hlock, |
1998 | u64 chain_key) |
1999 | { |
2000 | struct lock_class *class = hlock_class(hlock); |
2001 | struct list_head *hash_head = chainhashentry(chain_key); |
2002 | struct lock_chain *chain; |
2003 | struct held_lock *hlock_curr, *hlock_next; |
2004 | int i, j; |
2005 | |
2006 | /* |
2007 | * We might need to take the graph lock, ensure we've got IRQs |
2008 | * disabled to make this an IRQ-safe lock.. for recursion reasons |
2009 | * lockdep won't complain about its own locking errors. |
2010 | */ |
2011 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2012 | return 0; |
2013 | /* |
2014 | * We can walk it lock-free, because entries only get added |
2015 | * to the hash: |
2016 | */ |
2017 | list_for_each_entry(chain, hash_head, entry) { |
2018 | if (chain->chain_key == chain_key) { |
2019 | cache_hit: |
2020 | debug_atomic_inc(chain_lookup_hits); |
2021 | if (very_verbose(class)) |
2022 | printk("\nhash chain already cached, key: " |
2023 | "%016Lx tail class: [%p] %s\n", |
2024 | (unsigned long long)chain_key, |
2025 | class->key, class->name); |
2026 | return 0; |
2027 | } |
2028 | } |
2029 | if (very_verbose(class)) |
2030 | printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", |
2031 | (unsigned long long)chain_key, class->key, class->name); |
2032 | /* |
2033 | * Allocate a new chain entry from the static array, and add |
2034 | * it to the hash: |
2035 | */ |
2036 | if (!graph_lock()) |
2037 | return 0; |
2038 | /* |
2039 | * We have to walk the chain again locked - to avoid duplicates: |
2040 | */ |
2041 | list_for_each_entry(chain, hash_head, entry) { |
2042 | if (chain->chain_key == chain_key) { |
2043 | graph_unlock(); |
2044 | goto cache_hit; |
2045 | } |
2046 | } |
2047 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { |
2048 | if (!debug_locks_off_graph_unlock()) |
2049 | return 0; |
2050 | |
2051 | printk("BUG: MAX_LOCKDEP_CHAINS too low!\n"); |
2052 | printk("turning off the locking correctness validator.\n"); |
2053 | dump_stack(); |
2054 | return 0; |
2055 | } |
2056 | chain = lock_chains + nr_lock_chains++; |
2057 | chain->chain_key = chain_key; |
2058 | chain->irq_context = hlock->irq_context; |
2059 | /* Find the first held_lock of current chain */ |
2060 | hlock_next = hlock; |
2061 | for (i = curr->lockdep_depth - 1; i >= 0; i--) { |
2062 | hlock_curr = curr->held_locks + i; |
2063 | if (hlock_curr->irq_context != hlock_next->irq_context) |
2064 | break; |
2065 | hlock_next = hlock; |
2066 | } |
2067 | i++; |
2068 | chain->depth = curr->lockdep_depth + 1 - i; |
2069 | if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { |
2070 | chain->base = nr_chain_hlocks; |
2071 | nr_chain_hlocks += chain->depth; |
2072 | for (j = 0; j < chain->depth - 1; j++, i++) { |
2073 | int lock_id = curr->held_locks[i].class_idx - 1; |
2074 | chain_hlocks[chain->base + j] = lock_id; |
2075 | } |
2076 | chain_hlocks[chain->base + j] = class - lock_classes; |
2077 | } |
2078 | list_add_tail_rcu(&chain->entry, hash_head); |
2079 | debug_atomic_inc(chain_lookup_misses); |
2080 | inc_chains(); |
2081 | |
2082 | return 1; |
2083 | } |
2084 | |
2085 | static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, |
2086 | struct held_lock *hlock, int chain_head, u64 chain_key) |
2087 | { |
2088 | /* |
2089 | * Trylock needs to maintain the stack of held locks, but it |
2090 | * does not add new dependencies, because trylock can be done |
2091 | * in any order. |
2092 | * |
2093 | * We look up the chain_key and do the O(N^2) check and update of |
2094 | * the dependencies only if this is a new dependency chain. |
2095 | * (If lookup_chain_cache() returns with 1 it acquires |
2096 | * graph_lock for us) |
2097 | */ |
2098 | if (!hlock->trylock && (hlock->check == 2) && |
2099 | lookup_chain_cache(curr, hlock, chain_key)) { |
2100 | /* |
2101 | * Check whether last held lock: |
2102 | * |
2103 | * - is irq-safe, if this lock is irq-unsafe |
2104 | * - is softirq-safe, if this lock is hardirq-unsafe |
2105 | * |
2106 | * And check whether the new lock's dependency graph |
2107 | * could lead back to the previous lock. |
2108 | * |
2109 | * any of these scenarios could lead to a deadlock. If |
2110 | * All validations |
2111 | */ |
2112 | int ret = check_deadlock(curr, hlock, lock, hlock->read); |
2113 | |
2114 | if (!ret) |
2115 | return 0; |
2116 | /* |
2117 | * Mark recursive read, as we jump over it when |
2118 | * building dependencies (just like we jump over |
2119 | * trylock entries): |
2120 | */ |
2121 | if (ret == 2) |
2122 | hlock->read = 2; |
2123 | /* |
2124 | * Add dependency only if this lock is not the head |
2125 | * of the chain, and if it's not a secondary read-lock: |
2126 | */ |
2127 | if (!chain_head && ret != 2) |
2128 | if (!check_prevs_add(curr, hlock)) |
2129 | return 0; |
2130 | graph_unlock(); |
2131 | } else |
2132 | /* after lookup_chain_cache(): */ |
2133 | if (unlikely(!debug_locks)) |
2134 | return 0; |
2135 | |
2136 | return 1; |
2137 | } |
2138 | #else |
2139 | static inline int validate_chain(struct task_struct *curr, |
2140 | struct lockdep_map *lock, struct held_lock *hlock, |
2141 | int chain_head, u64 chain_key) |
2142 | { |
2143 | return 1; |
2144 | } |
2145 | #endif |
2146 | |
2147 | /* |
2148 | * We are building curr_chain_key incrementally, so double-check |
2149 | * it from scratch, to make sure that it's done correctly: |
2150 | */ |
2151 | static void check_chain_key(struct task_struct *curr) |
2152 | { |
2153 | #ifdef CONFIG_DEBUG_LOCKDEP |
2154 | struct held_lock *hlock, *prev_hlock = NULL; |
2155 | unsigned int i, id; |
2156 | u64 chain_key = 0; |
2157 | |
2158 | for (i = 0; i < curr->lockdep_depth; i++) { |
2159 | hlock = curr->held_locks + i; |
2160 | if (chain_key != hlock->prev_chain_key) { |
2161 | debug_locks_off(); |
2162 | /* |
2163 | * We got mighty confused, our chain keys don't match |
2164 | * with what we expect, someone trample on our task state? |
2165 | */ |
2166 | WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", |
2167 | curr->lockdep_depth, i, |
2168 | (unsigned long long)chain_key, |
2169 | (unsigned long long)hlock->prev_chain_key); |
2170 | return; |
2171 | } |
2172 | id = hlock->class_idx - 1; |
2173 | /* |
2174 | * Whoops ran out of static storage again? |
2175 | */ |
2176 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) |
2177 | return; |
2178 | |
2179 | if (prev_hlock && (prev_hlock->irq_context != |
2180 | hlock->irq_context)) |
2181 | chain_key = 0; |
2182 | chain_key = iterate_chain_key(chain_key, id); |
2183 | prev_hlock = hlock; |
2184 | } |
2185 | if (chain_key != curr->curr_chain_key) { |
2186 | debug_locks_off(); |
2187 | /* |
2188 | * More smoking hash instead of calculating it, damn see these |
2189 | * numbers float.. I bet that a pink elephant stepped on my memory. |
2190 | */ |
2191 | WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", |
2192 | curr->lockdep_depth, i, |
2193 | (unsigned long long)chain_key, |
2194 | (unsigned long long)curr->curr_chain_key); |
2195 | } |
2196 | #endif |
2197 | } |
2198 | |
2199 | static void |
2200 | print_usage_bug_scenario(struct held_lock *lock) |
2201 | { |
2202 | struct lock_class *class = hlock_class(lock); |
2203 | |
2204 | printk(" Possible unsafe locking scenario:\n\n"); |
2205 | printk(" CPU0\n"); |
2206 | printk(" ----\n"); |
2207 | printk(" lock("); |
2208 | __print_lock_name(class); |
2209 | printk(");\n"); |
2210 | printk(" <Interrupt>\n"); |
2211 | printk(" lock("); |
2212 | __print_lock_name(class); |
2213 | printk(");\n"); |
2214 | printk("\n *** DEADLOCK ***\n\n"); |
2215 | } |
2216 | |
2217 | static int |
2218 | print_usage_bug(struct task_struct *curr, struct held_lock *this, |
2219 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) |
2220 | { |
2221 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
2222 | return 0; |
2223 | |
2224 | printk("\n"); |
2225 | printk("=================================\n"); |
2226 | printk("[ INFO: inconsistent lock state ]\n"); |
2227 | print_kernel_ident(); |
2228 | printk("---------------------------------\n"); |
2229 | |
2230 | printk("inconsistent {%s} -> {%s} usage.\n", |
2231 | usage_str[prev_bit], usage_str[new_bit]); |
2232 | |
2233 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", |
2234 | curr->comm, task_pid_nr(curr), |
2235 | trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, |
2236 | trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, |
2237 | trace_hardirqs_enabled(curr), |
2238 | trace_softirqs_enabled(curr)); |
2239 | print_lock(this); |
2240 | |
2241 | printk("{%s} state was registered at:\n", usage_str[prev_bit]); |
2242 | print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1); |
2243 | |
2244 | print_irqtrace_events(curr); |
2245 | printk("\nother info that might help us debug this:\n"); |
2246 | print_usage_bug_scenario(this); |
2247 | |
2248 | lockdep_print_held_locks(curr); |
2249 | |
2250 | printk("\nstack backtrace:\n"); |
2251 | dump_stack(); |
2252 | |
2253 | return 0; |
2254 | } |
2255 | |
2256 | /* |
2257 | * Print out an error if an invalid bit is set: |
2258 | */ |
2259 | static inline int |
2260 | valid_state(struct task_struct *curr, struct held_lock *this, |
2261 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) |
2262 | { |
2263 | if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) |
2264 | return print_usage_bug(curr, this, bad_bit, new_bit); |
2265 | return 1; |
2266 | } |
2267 | |
2268 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
2269 | enum lock_usage_bit new_bit); |
2270 | |
2271 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
2272 | |
2273 | /* |
2274 | * print irq inversion bug: |
2275 | */ |
2276 | static int |
2277 | print_irq_inversion_bug(struct task_struct *curr, |
2278 | struct lock_list *root, struct lock_list *other, |
2279 | struct held_lock *this, int forwards, |
2280 | const char *irqclass) |
2281 | { |
2282 | struct lock_list *entry = other; |
2283 | struct lock_list *middle = NULL; |
2284 | int depth; |
2285 | |
2286 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
2287 | return 0; |
2288 | |
2289 | printk("\n"); |
2290 | printk("=========================================================\n"); |
2291 | printk("[ INFO: possible irq lock inversion dependency detected ]\n"); |
2292 | print_kernel_ident(); |
2293 | printk("---------------------------------------------------------\n"); |
2294 | printk("%s/%d just changed the state of lock:\n", |
2295 | curr->comm, task_pid_nr(curr)); |
2296 | print_lock(this); |
2297 | if (forwards) |
2298 | printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass); |
2299 | else |
2300 | printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); |
2301 | print_lock_name(other->class); |
2302 | printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); |
2303 | |
2304 | printk("\nother info that might help us debug this:\n"); |
2305 | |
2306 | /* Find a middle lock (if one exists) */ |
2307 | depth = get_lock_depth(other); |
2308 | do { |
2309 | if (depth == 0 && (entry != root)) { |
2310 | printk("lockdep:%s bad path found in chain graph\n", __func__); |
2311 | break; |
2312 | } |
2313 | middle = entry; |
2314 | entry = get_lock_parent(entry); |
2315 | depth--; |
2316 | } while (entry && entry != root && (depth >= 0)); |
2317 | if (forwards) |
2318 | print_irq_lock_scenario(root, other, |
2319 | middle ? middle->class : root->class, other->class); |
2320 | else |
2321 | print_irq_lock_scenario(other, root, |
2322 | middle ? middle->class : other->class, root->class); |
2323 | |
2324 | lockdep_print_held_locks(curr); |
2325 | |
2326 | printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); |
2327 | if (!save_trace(&root->trace)) |
2328 | return 0; |
2329 | print_shortest_lock_dependencies(other, root); |
2330 | |
2331 | printk("\nstack backtrace:\n"); |
2332 | dump_stack(); |
2333 | |
2334 | return 0; |
2335 | } |
2336 | |
2337 | /* |
2338 | * Prove that in the forwards-direction subgraph starting at <this> |
2339 | * there is no lock matching <mask>: |
2340 | */ |
2341 | static int |
2342 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, |
2343 | enum lock_usage_bit bit, const char *irqclass) |
2344 | { |
2345 | int ret; |
2346 | struct lock_list root; |
2347 | struct lock_list *uninitialized_var(target_entry); |
2348 | |
2349 | root.parent = NULL; |
2350 | root.class = hlock_class(this); |
2351 | ret = find_usage_forwards(&root, bit, &target_entry); |
2352 | if (ret < 0) |
2353 | return print_bfs_bug(ret); |
2354 | if (ret == 1) |
2355 | return ret; |
2356 | |
2357 | return print_irq_inversion_bug(curr, &root, target_entry, |
2358 | this, 1, irqclass); |
2359 | } |
2360 | |
2361 | /* |
2362 | * Prove that in the backwards-direction subgraph starting at <this> |
2363 | * there is no lock matching <mask>: |
2364 | */ |
2365 | static int |
2366 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, |
2367 | enum lock_usage_bit bit, const char *irqclass) |
2368 | { |
2369 | int ret; |
2370 | struct lock_list root; |
2371 | struct lock_list *uninitialized_var(target_entry); |
2372 | |
2373 | root.parent = NULL; |
2374 | root.class = hlock_class(this); |
2375 | ret = find_usage_backwards(&root, bit, &target_entry); |
2376 | if (ret < 0) |
2377 | return print_bfs_bug(ret); |
2378 | if (ret == 1) |
2379 | return ret; |
2380 | |
2381 | return print_irq_inversion_bug(curr, &root, target_entry, |
2382 | this, 0, irqclass); |
2383 | } |
2384 | |
2385 | void print_irqtrace_events(struct task_struct *curr) |
2386 | { |
2387 | printk("irq event stamp: %u\n", curr->irq_events); |
2388 | printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event); |
2389 | print_ip_sym(curr->hardirq_enable_ip); |
2390 | printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event); |
2391 | print_ip_sym(curr->hardirq_disable_ip); |
2392 | printk("softirqs last enabled at (%u): ", curr->softirq_enable_event); |
2393 | print_ip_sym(curr->softirq_enable_ip); |
2394 | printk("softirqs last disabled at (%u): ", curr->softirq_disable_event); |
2395 | print_ip_sym(curr->softirq_disable_ip); |
2396 | } |
2397 | |
2398 | static int HARDIRQ_verbose(struct lock_class *class) |
2399 | { |
2400 | #if HARDIRQ_VERBOSE |
2401 | return class_filter(class); |
2402 | #endif |
2403 | return 0; |
2404 | } |
2405 | |
2406 | static int SOFTIRQ_verbose(struct lock_class *class) |
2407 | { |
2408 | #if SOFTIRQ_VERBOSE |
2409 | return class_filter(class); |
2410 | #endif |
2411 | return 0; |
2412 | } |
2413 | |
2414 | static int RECLAIM_FS_verbose(struct lock_class *class) |
2415 | { |
2416 | #if RECLAIM_VERBOSE |
2417 | return class_filter(class); |
2418 | #endif |
2419 | return 0; |
2420 | } |
2421 | |
2422 | #define STRICT_READ_CHECKS 1 |
2423 | |
2424 | static int (*state_verbose_f[])(struct lock_class *class) = { |
2425 | #define LOCKDEP_STATE(__STATE) \ |
2426 | __STATE##_verbose, |
2427 | #include "lockdep_states.h" |
2428 | #undef LOCKDEP_STATE |
2429 | }; |
2430 | |
2431 | static inline int state_verbose(enum lock_usage_bit bit, |
2432 | struct lock_class *class) |
2433 | { |
2434 | return state_verbose_f[bit >> 2](class); |
2435 | } |
2436 | |
2437 | typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, |
2438 | enum lock_usage_bit bit, const char *name); |
2439 | |
2440 | static int |
2441 | mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
2442 | enum lock_usage_bit new_bit) |
2443 | { |
2444 | int excl_bit = exclusive_bit(new_bit); |
2445 | int read = new_bit & 1; |
2446 | int dir = new_bit & 2; |
2447 | |
2448 | /* |
2449 | * mark USED_IN has to look forwards -- to ensure no dependency |
2450 | * has ENABLED state, which would allow recursion deadlocks. |
2451 | * |
2452 | * mark ENABLED has to look backwards -- to ensure no dependee |
2453 | * has USED_IN state, which, again, would allow recursion deadlocks. |
2454 | */ |
2455 | check_usage_f usage = dir ? |
2456 | check_usage_backwards : check_usage_forwards; |
2457 | |
2458 | /* |
2459 | * Validate that this particular lock does not have conflicting |
2460 | * usage states. |
2461 | */ |
2462 | if (!valid_state(curr, this, new_bit, excl_bit)) |
2463 | return 0; |
2464 | |
2465 | /* |
2466 | * Validate that the lock dependencies don't have conflicting usage |
2467 | * states. |
2468 | */ |
2469 | if ((!read || !dir || STRICT_READ_CHECKS) && |
2470 | !usage(curr, this, excl_bit, state_name(new_bit & ~1))) |
2471 | return 0; |
2472 | |
2473 | /* |
2474 | * Check for read in write conflicts |
2475 | */ |
2476 | if (!read) { |
2477 | if (!valid_state(curr, this, new_bit, excl_bit + 1)) |
2478 | return 0; |
2479 | |
2480 | if (STRICT_READ_CHECKS && |
2481 | !usage(curr, this, excl_bit + 1, |
2482 | state_name(new_bit + 1))) |
2483 | return 0; |
2484 | } |
2485 | |
2486 | if (state_verbose(new_bit, hlock_class(this))) |
2487 | return 2; |
2488 | |
2489 | return 1; |
2490 | } |
2491 | |
2492 | enum mark_type { |
2493 | #define LOCKDEP_STATE(__STATE) __STATE, |
2494 | #include "lockdep_states.h" |
2495 | #undef LOCKDEP_STATE |
2496 | }; |
2497 | |
2498 | /* |
2499 | * Mark all held locks with a usage bit: |
2500 | */ |
2501 | static int |
2502 | mark_held_locks(struct task_struct *curr, enum mark_type mark) |
2503 | { |
2504 | enum lock_usage_bit usage_bit; |
2505 | struct held_lock *hlock; |
2506 | int i; |
2507 | |
2508 | for (i = 0; i < curr->lockdep_depth; i++) { |
2509 | hlock = curr->held_locks + i; |
2510 | |
2511 | usage_bit = 2 + (mark << 2); /* ENABLED */ |
2512 | if (hlock->read) |
2513 | usage_bit += 1; /* READ */ |
2514 | |
2515 | BUG_ON(usage_bit >= LOCK_USAGE_STATES); |
2516 | |
2517 | if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys) |
2518 | continue; |
2519 | |
2520 | if (!mark_lock(curr, hlock, usage_bit)) |
2521 | return 0; |
2522 | } |
2523 | |
2524 | return 1; |
2525 | } |
2526 | |
2527 | /* |
2528 | * Hardirqs will be enabled: |
2529 | */ |
2530 | static void __trace_hardirqs_on_caller(unsigned long ip) |
2531 | { |
2532 | struct task_struct *curr = current; |
2533 | |
2534 | /* we'll do an OFF -> ON transition: */ |
2535 | curr->hardirqs_enabled = 1; |
2536 | |
2537 | /* |
2538 | * We are going to turn hardirqs on, so set the |
2539 | * usage bit for all held locks: |
2540 | */ |
2541 | if (!mark_held_locks(curr, HARDIRQ)) |
2542 | return; |
2543 | /* |
2544 | * If we have softirqs enabled, then set the usage |
2545 | * bit for all held locks. (disabled hardirqs prevented |
2546 | * this bit from being set before) |
2547 | */ |
2548 | if (curr->softirqs_enabled) |
2549 | if (!mark_held_locks(curr, SOFTIRQ)) |
2550 | return; |
2551 | |
2552 | curr->hardirq_enable_ip = ip; |
2553 | curr->hardirq_enable_event = ++curr->irq_events; |
2554 | debug_atomic_inc(hardirqs_on_events); |
2555 | } |
2556 | |
2557 | void trace_hardirqs_on_caller(unsigned long ip) |
2558 | { |
2559 | time_hardirqs_on(CALLER_ADDR0, ip); |
2560 | |
2561 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2562 | return; |
2563 | |
2564 | if (unlikely(current->hardirqs_enabled)) { |
2565 | /* |
2566 | * Neither irq nor preemption are disabled here |
2567 | * so this is racy by nature but losing one hit |
2568 | * in a stat is not a big deal. |
2569 | */ |
2570 | __debug_atomic_inc(redundant_hardirqs_on); |
2571 | return; |
2572 | } |
2573 | |
2574 | /* |
2575 | * We're enabling irqs and according to our state above irqs weren't |
2576 | * already enabled, yet we find the hardware thinks they are in fact |
2577 | * enabled.. someone messed up their IRQ state tracing. |
2578 | */ |
2579 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2580 | return; |
2581 | |
2582 | /* |
2583 | * See the fine text that goes along with this variable definition. |
2584 | */ |
2585 | if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) |
2586 | return; |
2587 | |
2588 | /* |
2589 | * Can't allow enabling interrupts while in an interrupt handler, |
2590 | * that's general bad form and such. Recursion, limited stack etc.. |
2591 | */ |
2592 | if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) |
2593 | return; |
2594 | |
2595 | current->lockdep_recursion = 1; |
2596 | __trace_hardirqs_on_caller(ip); |
2597 | current->lockdep_recursion = 0; |
2598 | } |
2599 | EXPORT_SYMBOL(trace_hardirqs_on_caller); |
2600 | |
2601 | void trace_hardirqs_on(void) |
2602 | { |
2603 | trace_hardirqs_on_caller(CALLER_ADDR0); |
2604 | } |
2605 | EXPORT_SYMBOL(trace_hardirqs_on); |
2606 | |
2607 | /* |
2608 | * Hardirqs were disabled: |
2609 | */ |
2610 | void trace_hardirqs_off_caller(unsigned long ip) |
2611 | { |
2612 | struct task_struct *curr = current; |
2613 | |
2614 | time_hardirqs_off(CALLER_ADDR0, ip); |
2615 | |
2616 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2617 | return; |
2618 | |
2619 | /* |
2620 | * So we're supposed to get called after you mask local IRQs, but for |
2621 | * some reason the hardware doesn't quite think you did a proper job. |
2622 | */ |
2623 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2624 | return; |
2625 | |
2626 | if (curr->hardirqs_enabled) { |
2627 | /* |
2628 | * We have done an ON -> OFF transition: |
2629 | */ |
2630 | curr->hardirqs_enabled = 0; |
2631 | curr->hardirq_disable_ip = ip; |
2632 | curr->hardirq_disable_event = ++curr->irq_events; |
2633 | debug_atomic_inc(hardirqs_off_events); |
2634 | } else |
2635 | debug_atomic_inc(redundant_hardirqs_off); |
2636 | } |
2637 | EXPORT_SYMBOL(trace_hardirqs_off_caller); |
2638 | |
2639 | void trace_hardirqs_off(void) |
2640 | { |
2641 | trace_hardirqs_off_caller(CALLER_ADDR0); |
2642 | } |
2643 | EXPORT_SYMBOL(trace_hardirqs_off); |
2644 | |
2645 | /* |
2646 | * Softirqs will be enabled: |
2647 | */ |
2648 | void trace_softirqs_on(unsigned long ip) |
2649 | { |
2650 | struct task_struct *curr = current; |
2651 | |
2652 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2653 | return; |
2654 | |
2655 | /* |
2656 | * We fancy IRQs being disabled here, see softirq.c, avoids |
2657 | * funny state and nesting things. |
2658 | */ |
2659 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2660 | return; |
2661 | |
2662 | if (curr->softirqs_enabled) { |
2663 | debug_atomic_inc(redundant_softirqs_on); |
2664 | return; |
2665 | } |
2666 | |
2667 | current->lockdep_recursion = 1; |
2668 | /* |
2669 | * We'll do an OFF -> ON transition: |
2670 | */ |
2671 | curr->softirqs_enabled = 1; |
2672 | curr->softirq_enable_ip = ip; |
2673 | curr->softirq_enable_event = ++curr->irq_events; |
2674 | debug_atomic_inc(softirqs_on_events); |
2675 | /* |
2676 | * We are going to turn softirqs on, so set the |
2677 | * usage bit for all held locks, if hardirqs are |
2678 | * enabled too: |
2679 | */ |
2680 | if (curr->hardirqs_enabled) |
2681 | mark_held_locks(curr, SOFTIRQ); |
2682 | current->lockdep_recursion = 0; |
2683 | } |
2684 | |
2685 | /* |
2686 | * Softirqs were disabled: |
2687 | */ |
2688 | void trace_softirqs_off(unsigned long ip) |
2689 | { |
2690 | struct task_struct *curr = current; |
2691 | |
2692 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2693 | return; |
2694 | |
2695 | /* |
2696 | * We fancy IRQs being disabled here, see softirq.c |
2697 | */ |
2698 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2699 | return; |
2700 | |
2701 | if (curr->softirqs_enabled) { |
2702 | /* |
2703 | * We have done an ON -> OFF transition: |
2704 | */ |
2705 | curr->softirqs_enabled = 0; |
2706 | curr->softirq_disable_ip = ip; |
2707 | curr->softirq_disable_event = ++curr->irq_events; |
2708 | debug_atomic_inc(softirqs_off_events); |
2709 | /* |
2710 | * Whoops, we wanted softirqs off, so why aren't they? |
2711 | */ |
2712 | DEBUG_LOCKS_WARN_ON(!softirq_count()); |
2713 | } else |
2714 | debug_atomic_inc(redundant_softirqs_off); |
2715 | } |
2716 | |
2717 | static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags) |
2718 | { |
2719 | struct task_struct *curr = current; |
2720 | |
2721 | if (unlikely(!debug_locks)) |
2722 | return; |
2723 | |
2724 | /* no reclaim without waiting on it */ |
2725 | if (!(gfp_mask & __GFP_WAIT)) |
2726 | return; |
2727 | |
2728 | /* this guy won't enter reclaim */ |
2729 | if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC)) |
2730 | return; |
2731 | |
2732 | /* We're only interested __GFP_FS allocations for now */ |
2733 | if (!(gfp_mask & __GFP_FS)) |
2734 | return; |
2735 | |
2736 | /* |
2737 | * Oi! Can't be having __GFP_FS allocations with IRQs disabled. |
2738 | */ |
2739 | if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))) |
2740 | return; |
2741 | |
2742 | mark_held_locks(curr, RECLAIM_FS); |
2743 | } |
2744 | |
2745 | static void check_flags(unsigned long flags); |
2746 | |
2747 | void lockdep_trace_alloc(gfp_t gfp_mask) |
2748 | { |
2749 | unsigned long flags; |
2750 | |
2751 | if (unlikely(current->lockdep_recursion)) |
2752 | return; |
2753 | |
2754 | raw_local_irq_save(flags); |
2755 | check_flags(flags); |
2756 | current->lockdep_recursion = 1; |
2757 | __lockdep_trace_alloc(gfp_mask, flags); |
2758 | current->lockdep_recursion = 0; |
2759 | raw_local_irq_restore(flags); |
2760 | } |
2761 | |
2762 | static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) |
2763 | { |
2764 | /* |
2765 | * If non-trylock use in a hardirq or softirq context, then |
2766 | * mark the lock as used in these contexts: |
2767 | */ |
2768 | if (!hlock->trylock) { |
2769 | if (hlock->read) { |
2770 | if (curr->hardirq_context) |
2771 | if (!mark_lock(curr, hlock, |
2772 | LOCK_USED_IN_HARDIRQ_READ)) |
2773 | return 0; |
2774 | if (curr->softirq_context) |
2775 | if (!mark_lock(curr, hlock, |
2776 | LOCK_USED_IN_SOFTIRQ_READ)) |
2777 | return 0; |
2778 | } else { |
2779 | if (curr->hardirq_context) |
2780 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) |
2781 | return 0; |
2782 | if (curr->softirq_context) |
2783 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) |
2784 | return 0; |
2785 | } |
2786 | } |
2787 | if (!hlock->hardirqs_off) { |
2788 | if (hlock->read) { |
2789 | if (!mark_lock(curr, hlock, |
2790 | LOCK_ENABLED_HARDIRQ_READ)) |
2791 | return 0; |
2792 | if (curr->softirqs_enabled) |
2793 | if (!mark_lock(curr, hlock, |
2794 | LOCK_ENABLED_SOFTIRQ_READ)) |
2795 | return 0; |
2796 | } else { |
2797 | if (!mark_lock(curr, hlock, |
2798 | LOCK_ENABLED_HARDIRQ)) |
2799 | return 0; |
2800 | if (curr->softirqs_enabled) |
2801 | if (!mark_lock(curr, hlock, |
2802 | LOCK_ENABLED_SOFTIRQ)) |
2803 | return 0; |
2804 | } |
2805 | } |
2806 | |
2807 | /* |
2808 | * We reuse the irq context infrastructure more broadly as a general |
2809 | * context checking code. This tests GFP_FS recursion (a lock taken |
2810 | * during reclaim for a GFP_FS allocation is held over a GFP_FS |
2811 | * allocation). |
2812 | */ |
2813 | if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) { |
2814 | if (hlock->read) { |
2815 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ)) |
2816 | return 0; |
2817 | } else { |
2818 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS)) |
2819 | return 0; |
2820 | } |
2821 | } |
2822 | |
2823 | return 1; |
2824 | } |
2825 | |
2826 | static int separate_irq_context(struct task_struct *curr, |
2827 | struct held_lock *hlock) |
2828 | { |
2829 | unsigned int depth = curr->lockdep_depth; |
2830 | |
2831 | /* |
2832 | * Keep track of points where we cross into an interrupt context: |
2833 | */ |
2834 | hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) + |
2835 | curr->softirq_context; |
2836 | if (depth) { |
2837 | struct held_lock *prev_hlock; |
2838 | |
2839 | prev_hlock = curr->held_locks + depth-1; |
2840 | /* |
2841 | * If we cross into another context, reset the |
2842 | * hash key (this also prevents the checking and the |
2843 | * adding of the dependency to 'prev'): |
2844 | */ |
2845 | if (prev_hlock->irq_context != hlock->irq_context) |
2846 | return 1; |
2847 | } |
2848 | return 0; |
2849 | } |
2850 | |
2851 | #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ |
2852 | |
2853 | static inline |
2854 | int mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
2855 | enum lock_usage_bit new_bit) |
2856 | { |
2857 | WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */ |
2858 | return 1; |
2859 | } |
2860 | |
2861 | static inline int mark_irqflags(struct task_struct *curr, |
2862 | struct held_lock *hlock) |
2863 | { |
2864 | return 1; |
2865 | } |
2866 | |
2867 | static inline int separate_irq_context(struct task_struct *curr, |
2868 | struct held_lock *hlock) |
2869 | { |
2870 | return 0; |
2871 | } |
2872 | |
2873 | void lockdep_trace_alloc(gfp_t gfp_mask) |
2874 | { |
2875 | } |
2876 | |
2877 | #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ |
2878 | |
2879 | /* |
2880 | * Mark a lock with a usage bit, and validate the state transition: |
2881 | */ |
2882 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
2883 | enum lock_usage_bit new_bit) |
2884 | { |
2885 | unsigned int new_mask = 1 << new_bit, ret = 1; |
2886 | |
2887 | /* |
2888 | * If already set then do not dirty the cacheline, |
2889 | * nor do any checks: |
2890 | */ |
2891 | if (likely(hlock_class(this)->usage_mask & new_mask)) |
2892 | return 1; |
2893 | |
2894 | if (!graph_lock()) |
2895 | return 0; |
2896 | /* |
2897 | * Make sure we didn't race: |
2898 | */ |
2899 | if (unlikely(hlock_class(this)->usage_mask & new_mask)) { |
2900 | graph_unlock(); |
2901 | return 1; |
2902 | } |
2903 | |
2904 | hlock_class(this)->usage_mask |= new_mask; |
2905 | |
2906 | if (!save_trace(hlock_class(this)->usage_traces + new_bit)) |
2907 | return 0; |
2908 | |
2909 | switch (new_bit) { |
2910 | #define LOCKDEP_STATE(__STATE) \ |
2911 | case LOCK_USED_IN_##__STATE: \ |
2912 | case LOCK_USED_IN_##__STATE##_READ: \ |
2913 | case LOCK_ENABLED_##__STATE: \ |
2914 | case LOCK_ENABLED_##__STATE##_READ: |
2915 | #include "lockdep_states.h" |
2916 | #undef LOCKDEP_STATE |
2917 | ret = mark_lock_irq(curr, this, new_bit); |
2918 | if (!ret) |
2919 | return 0; |
2920 | break; |
2921 | case LOCK_USED: |
2922 | debug_atomic_dec(nr_unused_locks); |
2923 | break; |
2924 | default: |
2925 | if (!debug_locks_off_graph_unlock()) |
2926 | return 0; |
2927 | WARN_ON(1); |
2928 | return 0; |
2929 | } |
2930 | |
2931 | graph_unlock(); |
2932 | |
2933 | /* |
2934 | * We must printk outside of the graph_lock: |
2935 | */ |
2936 | if (ret == 2) { |
2937 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); |
2938 | print_lock(this); |
2939 | print_irqtrace_events(curr); |
2940 | dump_stack(); |
2941 | } |
2942 | |
2943 | return ret; |
2944 | } |
2945 | |
2946 | /* |
2947 | * Initialize a lock instance's lock-class mapping info: |
2948 | */ |
2949 | void lockdep_init_map(struct lockdep_map *lock, const char *name, |
2950 | struct lock_class_key *key, int subclass) |
2951 | { |
2952 | int i; |
2953 | |
2954 | kmemcheck_mark_initialized(lock, sizeof(*lock)); |
2955 | |
2956 | for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) |
2957 | lock->class_cache[i] = NULL; |
2958 | |
2959 | #ifdef CONFIG_LOCK_STAT |
2960 | lock->cpu = raw_smp_processor_id(); |
2961 | #endif |
2962 | |
2963 | /* |
2964 | * Can't be having no nameless bastards around this place! |
2965 | */ |
2966 | if (DEBUG_LOCKS_WARN_ON(!name)) { |
2967 | lock->name = "NULL"; |
2968 | return; |
2969 | } |
2970 | |
2971 | lock->name = name; |
2972 | |
2973 | /* |
2974 | * No key, no joy, we need to hash something. |
2975 | */ |
2976 | if (DEBUG_LOCKS_WARN_ON(!key)) |
2977 | return; |
2978 | /* |
2979 | * Sanity check, the lock-class key must be persistent: |
2980 | */ |
2981 | if (!static_obj(key)) { |
2982 | printk("BUG: key %p not in .data!\n", key); |
2983 | /* |
2984 | * What it says above ^^^^^, I suggest you read it. |
2985 | */ |
2986 | DEBUG_LOCKS_WARN_ON(1); |
2987 | return; |
2988 | } |
2989 | lock->key = key; |
2990 | |
2991 | if (unlikely(!debug_locks)) |
2992 | return; |
2993 | |
2994 | if (subclass) |
2995 | register_lock_class(lock, subclass, 1); |
2996 | } |
2997 | EXPORT_SYMBOL_GPL(lockdep_init_map); |
2998 | |
2999 | struct lock_class_key __lockdep_no_validate__; |
3000 | |
3001 | /* |
3002 | * This gets called for every mutex_lock*()/spin_lock*() operation. |
3003 | * We maintain the dependency maps and validate the locking attempt: |
3004 | */ |
3005 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
3006 | int trylock, int read, int check, int hardirqs_off, |
3007 | struct lockdep_map *nest_lock, unsigned long ip, |
3008 | int references) |
3009 | { |
3010 | struct task_struct *curr = current; |
3011 | struct lock_class *class = NULL; |
3012 | struct held_lock *hlock; |
3013 | unsigned int depth, id; |
3014 | int chain_head = 0; |
3015 | int class_idx; |
3016 | u64 chain_key; |
3017 | |
3018 | if (!prove_locking) |
3019 | check = 1; |
3020 | |
3021 | if (unlikely(!debug_locks)) |
3022 | return 0; |
3023 | |
3024 | /* |
3025 | * Lockdep should run with IRQs disabled, otherwise we could |
3026 | * get an interrupt which would want to take locks, which would |
3027 | * end up in lockdep and have you got a head-ache already? |
3028 | */ |
3029 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
3030 | return 0; |
3031 | |
3032 | if (lock->key == &__lockdep_no_validate__) |
3033 | check = 1; |
3034 | |
3035 | if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
3036 | class = lock->class_cache[subclass]; |
3037 | /* |
3038 | * Not cached? |
3039 | */ |
3040 | if (unlikely(!class)) { |
3041 | class = register_lock_class(lock, subclass, 0); |
3042 | if (!class) |
3043 | return 0; |
3044 | } |
3045 | atomic_inc((atomic_t *)&class->ops); |
3046 | if (very_verbose(class)) { |
3047 | printk("\nacquire class [%p] %s", class->key, class->name); |
3048 | if (class->name_version > 1) |
3049 | printk("#%d", class->name_version); |
3050 | printk("\n"); |
3051 | dump_stack(); |
3052 | } |
3053 | |
3054 | /* |
3055 | * Add the lock to the list of currently held locks. |
3056 | * (we dont increase the depth just yet, up until the |
3057 | * dependency checks are done) |
3058 | */ |
3059 | depth = curr->lockdep_depth; |
3060 | /* |
3061 | * Ran out of static storage for our per-task lock stack again have we? |
3062 | */ |
3063 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) |
3064 | return 0; |
3065 | |
3066 | class_idx = class - lock_classes + 1; |
3067 | |
3068 | if (depth) { |
3069 | hlock = curr->held_locks + depth - 1; |
3070 | if (hlock->class_idx == class_idx && nest_lock) { |
3071 | if (hlock->references) |
3072 | hlock->references++; |
3073 | else |
3074 | hlock->references = 2; |
3075 | |
3076 | return 1; |
3077 | } |
3078 | } |
3079 | |
3080 | hlock = curr->held_locks + depth; |
3081 | /* |
3082 | * Plain impossible, we just registered it and checked it weren't no |
3083 | * NULL like.. I bet this mushroom I ate was good! |
3084 | */ |
3085 | if (DEBUG_LOCKS_WARN_ON(!class)) |
3086 | return 0; |
3087 | hlock->class_idx = class_idx; |
3088 | hlock->acquire_ip = ip; |
3089 | hlock->instance = lock; |
3090 | hlock->nest_lock = nest_lock; |
3091 | hlock->trylock = trylock; |
3092 | hlock->read = read; |
3093 | hlock->check = check; |
3094 | hlock->hardirqs_off = !!hardirqs_off; |
3095 | hlock->references = references; |
3096 | #ifdef CONFIG_LOCK_STAT |
3097 | hlock->waittime_stamp = 0; |
3098 | hlock->holdtime_stamp = lockstat_clock(); |
3099 | #endif |
3100 | |
3101 | if (check == 2 && !mark_irqflags(curr, hlock)) |
3102 | return 0; |
3103 | |
3104 | /* mark it as used: */ |
3105 | if (!mark_lock(curr, hlock, LOCK_USED)) |
3106 | return 0; |
3107 | |
3108 | /* |
3109 | * Calculate the chain hash: it's the combined hash of all the |
3110 | * lock keys along the dependency chain. We save the hash value |
3111 | * at every step so that we can get the current hash easily |
3112 | * after unlock. The chain hash is then used to cache dependency |
3113 | * results. |
3114 | * |
3115 | * The 'key ID' is what is the most compact key value to drive |
3116 | * the hash, not class->key. |
3117 | */ |
3118 | id = class - lock_classes; |
3119 | /* |
3120 | * Whoops, we did it again.. ran straight out of our static allocation. |
3121 | */ |
3122 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) |
3123 | return 0; |
3124 | |
3125 | chain_key = curr->curr_chain_key; |
3126 | if (!depth) { |
3127 | /* |
3128 | * How can we have a chain hash when we ain't got no keys?! |
3129 | */ |
3130 | if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) |
3131 | return 0; |
3132 | chain_head = 1; |
3133 | } |
3134 | |
3135 | hlock->prev_chain_key = chain_key; |
3136 | if (separate_irq_context(curr, hlock)) { |
3137 | chain_key = 0; |
3138 | chain_head = 1; |
3139 | } |
3140 | chain_key = iterate_chain_key(chain_key, id); |
3141 | |
3142 | if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) |
3143 | return 0; |
3144 | |
3145 | curr->curr_chain_key = chain_key; |
3146 | curr->lockdep_depth++; |
3147 | check_chain_key(curr); |
3148 | #ifdef CONFIG_DEBUG_LOCKDEP |
3149 | if (unlikely(!debug_locks)) |
3150 | return 0; |
3151 | #endif |
3152 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { |
3153 | debug_locks_off(); |
3154 | printk("BUG: MAX_LOCK_DEPTH too low!\n"); |
3155 | printk("turning off the locking correctness validator.\n"); |
3156 | dump_stack(); |
3157 | return 0; |
3158 | } |
3159 | |
3160 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) |
3161 | max_lockdep_depth = curr->lockdep_depth; |
3162 | |
3163 | return 1; |
3164 | } |
3165 | |
3166 | static int |
3167 | print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock, |
3168 | unsigned long ip) |
3169 | { |
3170 | if (!debug_locks_off()) |
3171 | return 0; |
3172 | if (debug_locks_silent) |
3173 | return 0; |
3174 | |
3175 | printk("\n"); |
3176 | printk("=====================================\n"); |
3177 | printk("[ BUG: bad unlock balance detected! ]\n"); |
3178 | print_kernel_ident(); |
3179 | printk("-------------------------------------\n"); |
3180 | printk("%s/%d is trying to release lock (", |
3181 | curr->comm, task_pid_nr(curr)); |
3182 | print_lockdep_cache(lock); |
3183 | printk(") at:\n"); |
3184 | print_ip_sym(ip); |
3185 | printk("but there are no more locks to release!\n"); |
3186 | printk("\nother info that might help us debug this:\n"); |
3187 | lockdep_print_held_locks(curr); |
3188 | |
3189 | printk("\nstack backtrace:\n"); |
3190 | dump_stack(); |
3191 | |
3192 | return 0; |
3193 | } |
3194 | |
3195 | /* |
3196 | * Common debugging checks for both nested and non-nested unlock: |
3197 | */ |
3198 | static int check_unlock(struct task_struct *curr, struct lockdep_map *lock, |
3199 | unsigned long ip) |
3200 | { |
3201 | if (unlikely(!debug_locks)) |
3202 | return 0; |
3203 | /* |
3204 | * Lockdep should run with IRQs disabled, recursion, head-ache, etc.. |
3205 | */ |
3206 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
3207 | return 0; |
3208 | |
3209 | if (curr->lockdep_depth <= 0) |
3210 | return print_unlock_inbalance_bug(curr, lock, ip); |
3211 | |
3212 | return 1; |
3213 | } |
3214 | |
3215 | static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) |
3216 | { |
3217 | if (hlock->instance == lock) |
3218 | return 1; |
3219 | |
3220 | if (hlock->references) { |
3221 | struct lock_class *class = lock->class_cache[0]; |
3222 | |
3223 | if (!class) |
3224 | class = look_up_lock_class(lock, 0); |
3225 | |
3226 | /* |
3227 | * If look_up_lock_class() failed to find a class, we're trying |
3228 | * to test if we hold a lock that has never yet been acquired. |
3229 | * Clearly if the lock hasn't been acquired _ever_, we're not |
3230 | * holding it either, so report failure. |
3231 | */ |
3232 | if (!class) |
3233 | return 0; |
3234 | |
3235 | /* |
3236 | * References, but not a lock we're actually ref-counting? |
3237 | * State got messed up, follow the sites that change ->references |
3238 | * and try to make sense of it. |
3239 | */ |
3240 | if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) |
3241 | return 0; |
3242 | |
3243 | if (hlock->class_idx == class - lock_classes + 1) |
3244 | return 1; |
3245 | } |
3246 | |
3247 | return 0; |
3248 | } |
3249 | |
3250 | static int |
3251 | __lock_set_class(struct lockdep_map *lock, const char *name, |
3252 | struct lock_class_key *key, unsigned int subclass, |
3253 | unsigned long ip) |
3254 | { |
3255 | struct task_struct *curr = current; |
3256 | struct held_lock *hlock, *prev_hlock; |
3257 | struct lock_class *class; |
3258 | unsigned int depth; |
3259 | int i; |
3260 | |
3261 | depth = curr->lockdep_depth; |
3262 | /* |
3263 | * This function is about (re)setting the class of a held lock, |
3264 | * yet we're not actually holding any locks. Naughty user! |
3265 | */ |
3266 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3267 | return 0; |
3268 | |
3269 | prev_hlock = NULL; |
3270 | for (i = depth-1; i >= 0; i--) { |
3271 | hlock = curr->held_locks + i; |
3272 | /* |
3273 | * We must not cross into another context: |
3274 | */ |
3275 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3276 | break; |
3277 | if (match_held_lock(hlock, lock)) |
3278 | goto found_it; |
3279 | prev_hlock = hlock; |
3280 | } |
3281 | return print_unlock_inbalance_bug(curr, lock, ip); |
3282 | |
3283 | found_it: |
3284 | lockdep_init_map(lock, name, key, 0); |
3285 | class = register_lock_class(lock, subclass, 0); |
3286 | hlock->class_idx = class - lock_classes + 1; |
3287 | |
3288 | curr->lockdep_depth = i; |
3289 | curr->curr_chain_key = hlock->prev_chain_key; |
3290 | |
3291 | for (; i < depth; i++) { |
3292 | hlock = curr->held_locks + i; |
3293 | if (!__lock_acquire(hlock->instance, |
3294 | hlock_class(hlock)->subclass, hlock->trylock, |
3295 | hlock->read, hlock->check, hlock->hardirqs_off, |
3296 | hlock->nest_lock, hlock->acquire_ip, |
3297 | hlock->references)) |
3298 | return 0; |
3299 | } |
3300 | |
3301 | /* |
3302 | * I took it apart and put it back together again, except now I have |
3303 | * these 'spare' parts.. where shall I put them. |
3304 | */ |
3305 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) |
3306 | return 0; |
3307 | return 1; |
3308 | } |
3309 | |
3310 | /* |
3311 | * Remove the lock to the list of currently held locks in a |
3312 | * potentially non-nested (out of order) manner. This is a |
3313 | * relatively rare operation, as all the unlock APIs default |
3314 | * to nested mode (which uses lock_release()): |
3315 | */ |
3316 | static int |
3317 | lock_release_non_nested(struct task_struct *curr, |
3318 | struct lockdep_map *lock, unsigned long ip) |
3319 | { |
3320 | struct held_lock *hlock, *prev_hlock; |
3321 | unsigned int depth; |
3322 | int i; |
3323 | |
3324 | /* |
3325 | * Check whether the lock exists in the current stack |
3326 | * of held locks: |
3327 | */ |
3328 | depth = curr->lockdep_depth; |
3329 | /* |
3330 | * So we're all set to release this lock.. wait what lock? We don't |
3331 | * own any locks, you've been drinking again? |
3332 | */ |
3333 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3334 | return 0; |
3335 | |
3336 | prev_hlock = NULL; |
3337 | for (i = depth-1; i >= 0; i--) { |
3338 | hlock = curr->held_locks + i; |
3339 | /* |
3340 | * We must not cross into another context: |
3341 | */ |
3342 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3343 | break; |
3344 | if (match_held_lock(hlock, lock)) |
3345 | goto found_it; |
3346 | prev_hlock = hlock; |
3347 | } |
3348 | return print_unlock_inbalance_bug(curr, lock, ip); |
3349 | |
3350 | found_it: |
3351 | if (hlock->instance == lock) |
3352 | lock_release_holdtime(hlock); |
3353 | |
3354 | if (hlock->references) { |
3355 | hlock->references--; |
3356 | if (hlock->references) { |
3357 | /* |
3358 | * We had, and after removing one, still have |
3359 | * references, the current lock stack is still |
3360 | * valid. We're done! |
3361 | */ |
3362 | return 1; |
3363 | } |
3364 | } |
3365 | |
3366 | /* |
3367 | * We have the right lock to unlock, 'hlock' points to it. |
3368 | * Now we remove it from the stack, and add back the other |
3369 | * entries (if any), recalculating the hash along the way: |
3370 | */ |
3371 | |
3372 | curr->lockdep_depth = i; |
3373 | curr->curr_chain_key = hlock->prev_chain_key; |
3374 | |
3375 | for (i++; i < depth; i++) { |
3376 | hlock = curr->held_locks + i; |
3377 | if (!__lock_acquire(hlock->instance, |
3378 | hlock_class(hlock)->subclass, hlock->trylock, |
3379 | hlock->read, hlock->check, hlock->hardirqs_off, |
3380 | hlock->nest_lock, hlock->acquire_ip, |
3381 | hlock->references)) |
3382 | return 0; |
3383 | } |
3384 | |
3385 | /* |
3386 | * We had N bottles of beer on the wall, we drank one, but now |
3387 | * there's not N-1 bottles of beer left on the wall... |
3388 | */ |
3389 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) |
3390 | return 0; |
3391 | return 1; |
3392 | } |
3393 | |
3394 | /* |
3395 | * Remove the lock to the list of currently held locks - this gets |
3396 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
3397 | * mutex_lock_interruptible()). This is done for unlocks that nest |
3398 | * perfectly. (i.e. the current top of the lock-stack is unlocked) |
3399 | */ |
3400 | static int lock_release_nested(struct task_struct *curr, |
3401 | struct lockdep_map *lock, unsigned long ip) |
3402 | { |
3403 | struct held_lock *hlock; |
3404 | unsigned int depth; |
3405 | |
3406 | /* |
3407 | * Pop off the top of the lock stack: |
3408 | */ |
3409 | depth = curr->lockdep_depth - 1; |
3410 | hlock = curr->held_locks + depth; |
3411 | |
3412 | /* |
3413 | * Is the unlock non-nested: |
3414 | */ |
3415 | if (hlock->instance != lock || hlock->references) |
3416 | return lock_release_non_nested(curr, lock, ip); |
3417 | curr->lockdep_depth--; |
3418 | |
3419 | /* |
3420 | * No more locks, but somehow we've got hash left over, who left it? |
3421 | */ |
3422 | if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0))) |
3423 | return 0; |
3424 | |
3425 | curr->curr_chain_key = hlock->prev_chain_key; |
3426 | |
3427 | lock_release_holdtime(hlock); |
3428 | |
3429 | #ifdef CONFIG_DEBUG_LOCKDEP |
3430 | hlock->prev_chain_key = 0; |
3431 | hlock->class_idx = 0; |
3432 | hlock->acquire_ip = 0; |
3433 | hlock->irq_context = 0; |
3434 | #endif |
3435 | return 1; |
3436 | } |
3437 | |
3438 | /* |
3439 | * Remove the lock to the list of currently held locks - this gets |
3440 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
3441 | * mutex_lock_interruptible()). This is done for unlocks that nest |
3442 | * perfectly. (i.e. the current top of the lock-stack is unlocked) |
3443 | */ |
3444 | static void |
3445 | __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) |
3446 | { |
3447 | struct task_struct *curr = current; |
3448 | |
3449 | if (!check_unlock(curr, lock, ip)) |
3450 | return; |
3451 | |
3452 | if (nested) { |
3453 | if (!lock_release_nested(curr, lock, ip)) |
3454 | return; |
3455 | } else { |
3456 | if (!lock_release_non_nested(curr, lock, ip)) |
3457 | return; |
3458 | } |
3459 | |
3460 | check_chain_key(curr); |
3461 | } |
3462 | |
3463 | static int __lock_is_held(struct lockdep_map *lock) |
3464 | { |
3465 | struct task_struct *curr = current; |
3466 | int i; |
3467 | |
3468 | for (i = 0; i < curr->lockdep_depth; i++) { |
3469 | struct held_lock *hlock = curr->held_locks + i; |
3470 | |
3471 | if (match_held_lock(hlock, lock)) |
3472 | return 1; |
3473 | } |
3474 | |
3475 | return 0; |
3476 | } |
3477 | |
3478 | /* |
3479 | * Check whether we follow the irq-flags state precisely: |
3480 | */ |
3481 | static void check_flags(unsigned long flags) |
3482 | { |
3483 | #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \ |
3484 | defined(CONFIG_TRACE_IRQFLAGS) |
3485 | if (!debug_locks) |
3486 | return; |
3487 | |
3488 | if (irqs_disabled_flags(flags)) { |
3489 | if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { |
3490 | printk("possible reason: unannotated irqs-off.\n"); |
3491 | } |
3492 | } else { |
3493 | if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { |
3494 | printk("possible reason: unannotated irqs-on.\n"); |
3495 | } |
3496 | } |
3497 | |
3498 | /* |
3499 | * We dont accurately track softirq state in e.g. |
3500 | * hardirq contexts (such as on 4KSTACKS), so only |
3501 | * check if not in hardirq contexts: |
3502 | */ |
3503 | if (!hardirq_count()) { |
3504 | if (softirq_count()) { |
3505 | /* like the above, but with softirqs */ |
3506 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); |
3507 | } else { |
3508 | /* lick the above, does it taste good? */ |
3509 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); |
3510 | } |
3511 | } |
3512 | |
3513 | if (!debug_locks) |
3514 | print_irqtrace_events(current); |
3515 | #endif |
3516 | } |
3517 | |
3518 | void lock_set_class(struct lockdep_map *lock, const char *name, |
3519 | struct lock_class_key *key, unsigned int subclass, |
3520 | unsigned long ip) |
3521 | { |
3522 | unsigned long flags; |
3523 | |
3524 | if (unlikely(current->lockdep_recursion)) |
3525 | return; |
3526 | |
3527 | raw_local_irq_save(flags); |
3528 | current->lockdep_recursion = 1; |
3529 | check_flags(flags); |
3530 | if (__lock_set_class(lock, name, key, subclass, ip)) |
3531 | check_chain_key(current); |
3532 | current->lockdep_recursion = 0; |
3533 | raw_local_irq_restore(flags); |
3534 | } |
3535 | EXPORT_SYMBOL_GPL(lock_set_class); |
3536 | |
3537 | /* |
3538 | * We are not always called with irqs disabled - do that here, |
3539 | * and also avoid lockdep recursion: |
3540 | */ |
3541 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
3542 | int trylock, int read, int check, |
3543 | struct lockdep_map *nest_lock, unsigned long ip) |
3544 | { |
3545 | unsigned long flags; |
3546 | |
3547 | if (unlikely(current->lockdep_recursion)) |
3548 | return; |
3549 | |
3550 | raw_local_irq_save(flags); |
3551 | check_flags(flags); |
3552 | |
3553 | current->lockdep_recursion = 1; |
3554 | trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); |
3555 | __lock_acquire(lock, subclass, trylock, read, check, |
3556 | irqs_disabled_flags(flags), nest_lock, ip, 0); |
3557 | current->lockdep_recursion = 0; |
3558 | raw_local_irq_restore(flags); |
3559 | } |
3560 | EXPORT_SYMBOL_GPL(lock_acquire); |
3561 | |
3562 | void lock_release(struct lockdep_map *lock, int nested, |
3563 | unsigned long ip) |
3564 | { |
3565 | unsigned long flags; |
3566 | |
3567 | if (unlikely(current->lockdep_recursion)) |
3568 | return; |
3569 | |
3570 | raw_local_irq_save(flags); |
3571 | check_flags(flags); |
3572 | current->lockdep_recursion = 1; |
3573 | trace_lock_release(lock, ip); |
3574 | __lock_release(lock, nested, ip); |
3575 | current->lockdep_recursion = 0; |
3576 | raw_local_irq_restore(flags); |
3577 | } |
3578 | EXPORT_SYMBOL_GPL(lock_release); |
3579 | |
3580 | int lock_is_held(struct lockdep_map *lock) |
3581 | { |
3582 | unsigned long flags; |
3583 | int ret = 0; |
3584 | |
3585 | if (unlikely(current->lockdep_recursion)) |
3586 | return 1; /* avoid false negative lockdep_assert_held() */ |
3587 | |
3588 | raw_local_irq_save(flags); |
3589 | check_flags(flags); |
3590 | |
3591 | current->lockdep_recursion = 1; |
3592 | ret = __lock_is_held(lock); |
3593 | current->lockdep_recursion = 0; |
3594 | raw_local_irq_restore(flags); |
3595 | |
3596 | return ret; |
3597 | } |
3598 | EXPORT_SYMBOL_GPL(lock_is_held); |
3599 | |
3600 | void lockdep_set_current_reclaim_state(gfp_t gfp_mask) |
3601 | { |
3602 | current->lockdep_reclaim_gfp = gfp_mask; |
3603 | } |
3604 | |
3605 | void lockdep_clear_current_reclaim_state(void) |
3606 | { |
3607 | current->lockdep_reclaim_gfp = 0; |
3608 | } |
3609 | |
3610 | #ifdef CONFIG_LOCK_STAT |
3611 | static int |
3612 | print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, |
3613 | unsigned long ip) |
3614 | { |
3615 | if (!debug_locks_off()) |
3616 | return 0; |
3617 | if (debug_locks_silent) |
3618 | return 0; |
3619 | |
3620 | printk("\n"); |
3621 | printk("=================================\n"); |
3622 | printk("[ BUG: bad contention detected! ]\n"); |
3623 | print_kernel_ident(); |
3624 | printk("---------------------------------\n"); |
3625 | printk("%s/%d is trying to contend lock (", |
3626 | curr->comm, task_pid_nr(curr)); |
3627 | print_lockdep_cache(lock); |
3628 | printk(") at:\n"); |
3629 | print_ip_sym(ip); |
3630 | printk("but there are no locks held!\n"); |
3631 | printk("\nother info that might help us debug this:\n"); |
3632 | lockdep_print_held_locks(curr); |
3633 | |
3634 | printk("\nstack backtrace:\n"); |
3635 | dump_stack(); |
3636 | |
3637 | return 0; |
3638 | } |
3639 | |
3640 | static void |
3641 | __lock_contended(struct lockdep_map *lock, unsigned long ip) |
3642 | { |
3643 | struct task_struct *curr = current; |
3644 | struct held_lock *hlock, *prev_hlock; |
3645 | struct lock_class_stats *stats; |
3646 | unsigned int depth; |
3647 | int i, contention_point, contending_point; |
3648 | |
3649 | depth = curr->lockdep_depth; |
3650 | /* |
3651 | * Whee, we contended on this lock, except it seems we're not |
3652 | * actually trying to acquire anything much at all.. |
3653 | */ |
3654 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3655 | return; |
3656 | |
3657 | prev_hlock = NULL; |
3658 | for (i = depth-1; i >= 0; i--) { |
3659 | hlock = curr->held_locks + i; |
3660 | /* |
3661 | * We must not cross into another context: |
3662 | */ |
3663 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3664 | break; |
3665 | if (match_held_lock(hlock, lock)) |
3666 | goto found_it; |
3667 | prev_hlock = hlock; |
3668 | } |
3669 | print_lock_contention_bug(curr, lock, ip); |
3670 | return; |
3671 | |
3672 | found_it: |
3673 | if (hlock->instance != lock) |
3674 | return; |
3675 | |
3676 | hlock->waittime_stamp = lockstat_clock(); |
3677 | |
3678 | contention_point = lock_point(hlock_class(hlock)->contention_point, ip); |
3679 | contending_point = lock_point(hlock_class(hlock)->contending_point, |
3680 | lock->ip); |
3681 | |
3682 | stats = get_lock_stats(hlock_class(hlock)); |
3683 | if (contention_point < LOCKSTAT_POINTS) |
3684 | stats->contention_point[contention_point]++; |
3685 | if (contending_point < LOCKSTAT_POINTS) |
3686 | stats->contending_point[contending_point]++; |
3687 | if (lock->cpu != smp_processor_id()) |
3688 | stats->bounces[bounce_contended + !!hlock->read]++; |
3689 | put_lock_stats(stats); |
3690 | } |
3691 | |
3692 | static void |
3693 | __lock_acquired(struct lockdep_map *lock, unsigned long ip) |
3694 | { |
3695 | struct task_struct *curr = current; |
3696 | struct held_lock *hlock, *prev_hlock; |
3697 | struct lock_class_stats *stats; |
3698 | unsigned int depth; |
3699 | u64 now, waittime = 0; |
3700 | int i, cpu; |
3701 | |
3702 | depth = curr->lockdep_depth; |
3703 | /* |
3704 | * Yay, we acquired ownership of this lock we didn't try to |
3705 | * acquire, how the heck did that happen? |
3706 | */ |
3707 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3708 | return; |
3709 | |
3710 | prev_hlock = NULL; |
3711 | for (i = depth-1; i >= 0; i--) { |
3712 | hlock = curr->held_locks + i; |
3713 | /* |
3714 | * We must not cross into another context: |
3715 | */ |
3716 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3717 | break; |
3718 | if (match_held_lock(hlock, lock)) |
3719 | goto found_it; |
3720 | prev_hlock = hlock; |
3721 | } |
3722 | print_lock_contention_bug(curr, lock, _RET_IP_); |
3723 | return; |
3724 | |
3725 | found_it: |
3726 | if (hlock->instance != lock) |
3727 | return; |
3728 | |
3729 | cpu = smp_processor_id(); |
3730 | if (hlock->waittime_stamp) { |
3731 | now = lockstat_clock(); |
3732 | waittime = now - hlock->waittime_stamp; |
3733 | hlock->holdtime_stamp = now; |
3734 | } |
3735 | |
3736 | trace_lock_acquired(lock, ip); |
3737 | |
3738 | stats = get_lock_stats(hlock_class(hlock)); |
3739 | if (waittime) { |
3740 | if (hlock->read) |
3741 | lock_time_inc(&stats->read_waittime, waittime); |
3742 | else |
3743 | lock_time_inc(&stats->write_waittime, waittime); |
3744 | } |
3745 | if (lock->cpu != cpu) |
3746 | stats->bounces[bounce_acquired + !!hlock->read]++; |
3747 | put_lock_stats(stats); |
3748 | |
3749 | lock->cpu = cpu; |
3750 | lock->ip = ip; |
3751 | } |
3752 | |
3753 | void lock_contended(struct lockdep_map *lock, unsigned long ip) |
3754 | { |
3755 | unsigned long flags; |
3756 | |
3757 | if (unlikely(!lock_stat)) |
3758 | return; |
3759 | |
3760 | if (unlikely(current->lockdep_recursion)) |
3761 | return; |
3762 | |
3763 | raw_local_irq_save(flags); |
3764 | check_flags(flags); |
3765 | current->lockdep_recursion = 1; |
3766 | trace_lock_contended(lock, ip); |
3767 | __lock_contended(lock, ip); |
3768 | current->lockdep_recursion = 0; |
3769 | raw_local_irq_restore(flags); |
3770 | } |
3771 | EXPORT_SYMBOL_GPL(lock_contended); |
3772 | |
3773 | void lock_acquired(struct lockdep_map *lock, unsigned long ip) |
3774 | { |
3775 | unsigned long flags; |
3776 | |
3777 | if (unlikely(!lock_stat)) |
3778 | return; |
3779 | |
3780 | if (unlikely(current->lockdep_recursion)) |
3781 | return; |
3782 | |
3783 | raw_local_irq_save(flags); |
3784 | check_flags(flags); |
3785 | current->lockdep_recursion = 1; |
3786 | __lock_acquired(lock, ip); |
3787 | current->lockdep_recursion = 0; |
3788 | raw_local_irq_restore(flags); |
3789 | } |
3790 | EXPORT_SYMBOL_GPL(lock_acquired); |
3791 | #endif |
3792 | |
3793 | /* |
3794 | * Used by the testsuite, sanitize the validator state |
3795 | * after a simulated failure: |
3796 | */ |
3797 | |
3798 | void lockdep_reset(void) |
3799 | { |
3800 | unsigned long flags; |
3801 | int i; |
3802 | |
3803 | raw_local_irq_save(flags); |
3804 | current->curr_chain_key = 0; |
3805 | current->lockdep_depth = 0; |
3806 | current->lockdep_recursion = 0; |
3807 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); |
3808 | nr_hardirq_chains = 0; |
3809 | nr_softirq_chains = 0; |
3810 | nr_process_chains = 0; |
3811 | debug_locks = 1; |
3812 | for (i = 0; i < CHAINHASH_SIZE; i++) |
3813 | INIT_LIST_HEAD(chainhash_table + i); |
3814 | raw_local_irq_restore(flags); |
3815 | } |
3816 | |
3817 | static void zap_class(struct lock_class *class) |
3818 | { |
3819 | int i; |
3820 | |
3821 | /* |
3822 | * Remove all dependencies this lock is |
3823 | * involved in: |
3824 | */ |
3825 | for (i = 0; i < nr_list_entries; i++) { |
3826 | if (list_entries[i].class == class) |
3827 | list_del_rcu(&list_entries[i].entry); |
3828 | } |
3829 | /* |
3830 | * Unhash the class and remove it from the all_lock_classes list: |
3831 | */ |
3832 | list_del_rcu(&class->hash_entry); |
3833 | list_del_rcu(&class->lock_entry); |
3834 | |
3835 | class->key = NULL; |
3836 | } |
3837 | |
3838 | static inline int within(const void *addr, void *start, unsigned long size) |
3839 | { |
3840 | return addr >= start && addr < start + size; |
3841 | } |
3842 | |
3843 | void lockdep_free_key_range(void *start, unsigned long size) |
3844 | { |
3845 | struct lock_class *class, *next; |
3846 | struct list_head *head; |
3847 | unsigned long flags; |
3848 | int i; |
3849 | int locked; |
3850 | |
3851 | raw_local_irq_save(flags); |
3852 | locked = graph_lock(); |
3853 | |
3854 | /* |
3855 | * Unhash all classes that were created by this module: |
3856 | */ |
3857 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
3858 | head = classhash_table + i; |
3859 | if (list_empty(head)) |
3860 | continue; |
3861 | list_for_each_entry_safe(class, next, head, hash_entry) { |
3862 | if (within(class->key, start, size)) |
3863 | zap_class(class); |
3864 | else if (within(class->name, start, size)) |
3865 | zap_class(class); |
3866 | } |
3867 | } |
3868 | |
3869 | if (locked) |
3870 | graph_unlock(); |
3871 | raw_local_irq_restore(flags); |
3872 | } |
3873 | |
3874 | void lockdep_reset_lock(struct lockdep_map *lock) |
3875 | { |
3876 | struct lock_class *class, *next; |
3877 | struct list_head *head; |
3878 | unsigned long flags; |
3879 | int i, j; |
3880 | int locked; |
3881 | |
3882 | raw_local_irq_save(flags); |
3883 | |
3884 | /* |
3885 | * Remove all classes this lock might have: |
3886 | */ |
3887 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { |
3888 | /* |
3889 | * If the class exists we look it up and zap it: |
3890 | */ |
3891 | class = look_up_lock_class(lock, j); |
3892 | if (class) |
3893 | zap_class(class); |
3894 | } |
3895 | /* |
3896 | * Debug check: in the end all mapped classes should |
3897 | * be gone. |
3898 | */ |
3899 | locked = graph_lock(); |
3900 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
3901 | head = classhash_table + i; |
3902 | if (list_empty(head)) |
3903 | continue; |
3904 | list_for_each_entry_safe(class, next, head, hash_entry) { |
3905 | int match = 0; |
3906 | |
3907 | for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) |
3908 | match |= class == lock->class_cache[j]; |
3909 | |
3910 | if (unlikely(match)) { |
3911 | if (debug_locks_off_graph_unlock()) { |
3912 | /* |
3913 | * We all just reset everything, how did it match? |
3914 | */ |
3915 | WARN_ON(1); |
3916 | } |
3917 | goto out_restore; |
3918 | } |
3919 | } |
3920 | } |
3921 | if (locked) |
3922 | graph_unlock(); |
3923 | |
3924 | out_restore: |
3925 | raw_local_irq_restore(flags); |
3926 | } |
3927 | |
3928 | void lockdep_init(void) |
3929 | { |
3930 | int i; |
3931 | |
3932 | /* |
3933 | * Some architectures have their own start_kernel() |
3934 | * code which calls lockdep_init(), while we also |
3935 | * call lockdep_init() from the start_kernel() itself, |
3936 | * and we want to initialize the hashes only once: |
3937 | */ |
3938 | if (lockdep_initialized) |
3939 | return; |
3940 | |
3941 | for (i = 0; i < CLASSHASH_SIZE; i++) |
3942 | INIT_LIST_HEAD(classhash_table + i); |
3943 | |
3944 | for (i = 0; i < CHAINHASH_SIZE; i++) |
3945 | INIT_LIST_HEAD(chainhash_table + i); |
3946 | |
3947 | lockdep_initialized = 1; |
3948 | } |
3949 | |
3950 | void __init lockdep_info(void) |
3951 | { |
3952 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); |
3953 | |
3954 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); |
3955 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); |
3956 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); |
3957 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); |
3958 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); |
3959 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); |
3960 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); |
3961 | |
3962 | printk(" memory used by lock dependency info: %lu kB\n", |
3963 | (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + |
3964 | sizeof(struct list_head) * CLASSHASH_SIZE + |
3965 | sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + |
3966 | sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + |
3967 | sizeof(struct list_head) * CHAINHASH_SIZE |
3968 | #ifdef CONFIG_PROVE_LOCKING |
3969 | + sizeof(struct circular_queue) |
3970 | #endif |
3971 | ) / 1024 |
3972 | ); |
3973 | |
3974 | printk(" per task-struct memory footprint: %lu bytes\n", |
3975 | sizeof(struct held_lock) * MAX_LOCK_DEPTH); |
3976 | |
3977 | #ifdef CONFIG_DEBUG_LOCKDEP |
3978 | if (lockdep_init_error) { |
3979 | printk("WARNING: lockdep init error! lock-%s was acquired" |
3980 | "before lockdep_init\n", lock_init_error); |
3981 | printk("Call stack leading to lockdep invocation was:\n"); |
3982 | print_stack_trace(&lockdep_init_trace, 0); |
3983 | } |
3984 | #endif |
3985 | } |
3986 | |
3987 | static void |
3988 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, |
3989 | const void *mem_to, struct held_lock *hlock) |
3990 | { |
3991 | if (!debug_locks_off()) |
3992 | return; |
3993 | if (debug_locks_silent) |
3994 | return; |
3995 | |
3996 | printk("\n"); |
3997 | printk("=========================\n"); |
3998 | printk("[ BUG: held lock freed! ]\n"); |
3999 | print_kernel_ident(); |
4000 | printk("-------------------------\n"); |
4001 | printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", |
4002 | curr->comm, task_pid_nr(curr), mem_from, mem_to-1); |
4003 | print_lock(hlock); |
4004 | lockdep_print_held_locks(curr); |
4005 | |
4006 | printk("\nstack backtrace:\n"); |
4007 | dump_stack(); |
4008 | } |
4009 | |
4010 | static inline int not_in_range(const void* mem_from, unsigned long mem_len, |
4011 | const void* lock_from, unsigned long lock_len) |
4012 | { |
4013 | return lock_from + lock_len <= mem_from || |
4014 | mem_from + mem_len <= lock_from; |
4015 | } |
4016 | |
4017 | /* |
4018 | * Called when kernel memory is freed (or unmapped), or if a lock |
4019 | * is destroyed or reinitialized - this code checks whether there is |
4020 | * any held lock in the memory range of <from> to <to>: |
4021 | */ |
4022 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) |
4023 | { |
4024 | struct task_struct *curr = current; |
4025 | struct held_lock *hlock; |
4026 | unsigned long flags; |
4027 | int i; |
4028 | |
4029 | if (unlikely(!debug_locks)) |
4030 | return; |
4031 | |
4032 | local_irq_save(flags); |
4033 | for (i = 0; i < curr->lockdep_depth; i++) { |
4034 | hlock = curr->held_locks + i; |
4035 | |
4036 | if (not_in_range(mem_from, mem_len, hlock->instance, |
4037 | sizeof(*hlock->instance))) |
4038 | continue; |
4039 | |
4040 | print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); |
4041 | break; |
4042 | } |
4043 | local_irq_restore(flags); |
4044 | } |
4045 | EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); |
4046 | |
4047 | static void print_held_locks_bug(struct task_struct *curr) |
4048 | { |
4049 | if (!debug_locks_off()) |
4050 | return; |
4051 | if (debug_locks_silent) |
4052 | return; |
4053 | |
4054 | printk("\n"); |
4055 | printk("=====================================\n"); |
4056 | printk("[ BUG: lock held at task exit time! ]\n"); |
4057 | print_kernel_ident(); |
4058 | printk("-------------------------------------\n"); |
4059 | printk("%s/%d is exiting with locks still held!\n", |
4060 | curr->comm, task_pid_nr(curr)); |
4061 | lockdep_print_held_locks(curr); |
4062 | |
4063 | printk("\nstack backtrace:\n"); |
4064 | dump_stack(); |
4065 | } |
4066 | |
4067 | void debug_check_no_locks_held(struct task_struct *task) |
4068 | { |
4069 | if (unlikely(task->lockdep_depth > 0)) |
4070 | print_held_locks_bug(task); |
4071 | } |
4072 | |
4073 | void debug_show_all_locks(void) |
4074 | { |
4075 | struct task_struct *g, *p; |
4076 | int count = 10; |
4077 | int unlock = 1; |
4078 | |
4079 | if (unlikely(!debug_locks)) { |
4080 | printk("INFO: lockdep is turned off.\n"); |
4081 | return; |
4082 | } |
4083 | printk("\nShowing all locks held in the system:\n"); |
4084 | |
4085 | /* |
4086 | * Here we try to get the tasklist_lock as hard as possible, |
4087 | * if not successful after 2 seconds we ignore it (but keep |
4088 | * trying). This is to enable a debug printout even if a |
4089 | * tasklist_lock-holding task deadlocks or crashes. |
4090 | */ |
4091 | retry: |
4092 | if (!read_trylock(&tasklist_lock)) { |
4093 | if (count == 10) |
4094 | printk("hm, tasklist_lock locked, retrying... "); |
4095 | if (count) { |
4096 | count--; |
4097 | printk(" #%d", 10-count); |
4098 | mdelay(200); |
4099 | goto retry; |
4100 | } |
4101 | printk(" ignoring it.\n"); |
4102 | unlock = 0; |
4103 | } else { |
4104 | if (count != 10) |
4105 | printk(KERN_CONT " locked it.\n"); |
4106 | } |
4107 | |
4108 | do_each_thread(g, p) { |
4109 | /* |
4110 | * It's not reliable to print a task's held locks |
4111 | * if it's not sleeping (or if it's not the current |
4112 | * task): |
4113 | */ |
4114 | if (p->state == TASK_RUNNING && p != current) |
4115 | continue; |
4116 | if (p->lockdep_depth) |
4117 | lockdep_print_held_locks(p); |
4118 | if (!unlock) |
4119 | if (read_trylock(&tasklist_lock)) |
4120 | unlock = 1; |
4121 | } while_each_thread(g, p); |
4122 | |
4123 | printk("\n"); |
4124 | printk("=============================================\n\n"); |
4125 | |
4126 | if (unlock) |
4127 | read_unlock(&tasklist_lock); |
4128 | } |
4129 | EXPORT_SYMBOL_GPL(debug_show_all_locks); |
4130 | |
4131 | /* |
4132 | * Careful: only use this function if you are sure that |
4133 | * the task cannot run in parallel! |
4134 | */ |
4135 | void debug_show_held_locks(struct task_struct *task) |
4136 | { |
4137 | if (unlikely(!debug_locks)) { |
4138 | printk("INFO: lockdep is turned off.\n"); |
4139 | return; |
4140 | } |
4141 | lockdep_print_held_locks(task); |
4142 | } |
4143 | EXPORT_SYMBOL_GPL(debug_show_held_locks); |
4144 | |
4145 | void lockdep_sys_exit(void) |
4146 | { |
4147 | struct task_struct *curr = current; |
4148 | |
4149 | if (unlikely(curr->lockdep_depth)) { |
4150 | if (!debug_locks_off()) |
4151 | return; |
4152 | printk("\n"); |
4153 | printk("================================================\n"); |
4154 | printk("[ BUG: lock held when returning to user space! ]\n"); |
4155 | print_kernel_ident(); |
4156 | printk("------------------------------------------------\n"); |
4157 | printk("%s/%d is leaving the kernel with locks still held!\n", |
4158 | curr->comm, curr->pid); |
4159 | lockdep_print_held_locks(curr); |
4160 | } |
4161 | } |
4162 | |
4163 | void lockdep_rcu_suspicious(const char *file, const int line, const char *s) |
4164 | { |
4165 | struct task_struct *curr = current; |
4166 | |
4167 | #ifndef CONFIG_PROVE_RCU_REPEATEDLY |
4168 | if (!debug_locks_off()) |
4169 | return; |
4170 | #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */ |
4171 | /* Note: the following can be executed concurrently, so be careful. */ |
4172 | printk("\n"); |
4173 | printk("===============================\n"); |
4174 | printk("[ INFO: suspicious RCU usage. ]\n"); |
4175 | print_kernel_ident(); |
4176 | printk("-------------------------------\n"); |
4177 | printk("%s:%d %s!\n", file, line, s); |
4178 | printk("\nother info that might help us debug this:\n\n"); |
4179 | printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks); |
4180 | |
4181 | /* |
4182 | * If a CPU is in the RCU-free window in idle (ie: in the section |
4183 | * between rcu_idle_enter() and rcu_idle_exit(), then RCU |
4184 | * considers that CPU to be in an "extended quiescent state", |
4185 | * which means that RCU will be completely ignoring that CPU. |
4186 | * Therefore, rcu_read_lock() and friends have absolutely no |
4187 | * effect on a CPU running in that state. In other words, even if |
4188 | * such an RCU-idle CPU has called rcu_read_lock(), RCU might well |
4189 | * delete data structures out from under it. RCU really has no |
4190 | * choice here: we need to keep an RCU-free window in idle where |
4191 | * the CPU may possibly enter into low power mode. This way we can |
4192 | * notice an extended quiescent state to other CPUs that started a grace |
4193 | * period. Otherwise we would delay any grace period as long as we run |
4194 | * in the idle task. |
4195 | * |
4196 | * So complain bitterly if someone does call rcu_read_lock(), |
4197 | * rcu_read_lock_bh() and so on from extended quiescent states. |
4198 | */ |
4199 | if (rcu_is_cpu_idle()) |
4200 | printk("RCU used illegally from extended quiescent state!\n"); |
4201 | |
4202 | lockdep_print_held_locks(curr); |
4203 | printk("\nstack backtrace:\n"); |
4204 | dump_stack(); |
4205 | } |
4206 | EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); |
4207 |
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