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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 void print_lockdep_off(const char *bug_msg) |
384 | { |
385 | printk(KERN_DEBUG "%s\n", bug_msg); |
386 | printk(KERN_DEBUG "turning off the locking correctness validator.\n"); |
387 | printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n"); |
388 | } |
389 | |
390 | static int save_trace(struct stack_trace *trace) |
391 | { |
392 | trace->nr_entries = 0; |
393 | trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; |
394 | trace->entries = stack_trace + nr_stack_trace_entries; |
395 | |
396 | trace->skip = 3; |
397 | |
398 | save_stack_trace(trace); |
399 | |
400 | /* |
401 | * Some daft arches put -1 at the end to indicate its a full trace. |
402 | * |
403 | * <rant> this is buggy anyway, since it takes a whole extra entry so a |
404 | * complete trace that maxes out the entries provided will be reported |
405 | * as incomplete, friggin useless </rant> |
406 | */ |
407 | if (trace->nr_entries != 0 && |
408 | trace->entries[trace->nr_entries-1] == ULONG_MAX) |
409 | trace->nr_entries--; |
410 | |
411 | trace->max_entries = trace->nr_entries; |
412 | |
413 | nr_stack_trace_entries += trace->nr_entries; |
414 | |
415 | if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { |
416 | if (!debug_locks_off_graph_unlock()) |
417 | return 0; |
418 | |
419 | print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); |
420 | dump_stack(); |
421 | |
422 | return 0; |
423 | } |
424 | |
425 | return 1; |
426 | } |
427 | |
428 | unsigned int nr_hardirq_chains; |
429 | unsigned int nr_softirq_chains; |
430 | unsigned int nr_process_chains; |
431 | unsigned int max_lockdep_depth; |
432 | |
433 | #ifdef CONFIG_DEBUG_LOCKDEP |
434 | /* |
435 | * We cannot printk in early bootup code. Not even early_printk() |
436 | * might work. So we mark any initialization errors and printk |
437 | * about it later on, in lockdep_info(). |
438 | */ |
439 | static int lockdep_init_error; |
440 | static const char *lock_init_error; |
441 | static unsigned long lockdep_init_trace_data[20]; |
442 | static struct stack_trace lockdep_init_trace = { |
443 | .max_entries = ARRAY_SIZE(lockdep_init_trace_data), |
444 | .entries = lockdep_init_trace_data, |
445 | }; |
446 | |
447 | /* |
448 | * Various lockdep statistics: |
449 | */ |
450 | DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); |
451 | #endif |
452 | |
453 | /* |
454 | * Locking printouts: |
455 | */ |
456 | |
457 | #define __USAGE(__STATE) \ |
458 | [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ |
459 | [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ |
460 | [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ |
461 | [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", |
462 | |
463 | static const char *usage_str[] = |
464 | { |
465 | #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) |
466 | #include "lockdep_states.h" |
467 | #undef LOCKDEP_STATE |
468 | [LOCK_USED] = "INITIAL USE", |
469 | }; |
470 | |
471 | const char * __get_key_name(struct lockdep_subclass_key *key, char *str) |
472 | { |
473 | return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); |
474 | } |
475 | |
476 | static inline unsigned long lock_flag(enum lock_usage_bit bit) |
477 | { |
478 | return 1UL << bit; |
479 | } |
480 | |
481 | static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) |
482 | { |
483 | char c = '.'; |
484 | |
485 | if (class->usage_mask & lock_flag(bit + 2)) |
486 | c = '+'; |
487 | if (class->usage_mask & lock_flag(bit)) { |
488 | c = '-'; |
489 | if (class->usage_mask & lock_flag(bit + 2)) |
490 | c = '?'; |
491 | } |
492 | |
493 | return c; |
494 | } |
495 | |
496 | void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) |
497 | { |
498 | int i = 0; |
499 | |
500 | #define LOCKDEP_STATE(__STATE) \ |
501 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ |
502 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); |
503 | #include "lockdep_states.h" |
504 | #undef LOCKDEP_STATE |
505 | |
506 | usage[i] = '\0'; |
507 | } |
508 | |
509 | static void __print_lock_name(struct lock_class *class) |
510 | { |
511 | char str[KSYM_NAME_LEN]; |
512 | const char *name; |
513 | |
514 | name = class->name; |
515 | if (!name) { |
516 | name = __get_key_name(class->key, str); |
517 | printk("%s", name); |
518 | } else { |
519 | printk("%s", name); |
520 | if (class->name_version > 1) |
521 | printk("#%d", class->name_version); |
522 | if (class->subclass) |
523 | printk("/%d", class->subclass); |
524 | } |
525 | } |
526 | |
527 | static void print_lock_name(struct lock_class *class) |
528 | { |
529 | char usage[LOCK_USAGE_CHARS]; |
530 | |
531 | get_usage_chars(class, usage); |
532 | |
533 | printk(" ("); |
534 | __print_lock_name(class); |
535 | printk("){%s}", usage); |
536 | } |
537 | |
538 | static void print_lockdep_cache(struct lockdep_map *lock) |
539 | { |
540 | const char *name; |
541 | char str[KSYM_NAME_LEN]; |
542 | |
543 | name = lock->name; |
544 | if (!name) |
545 | name = __get_key_name(lock->key->subkeys, str); |
546 | |
547 | printk("%s", name); |
548 | } |
549 | |
550 | static void print_lock(struct held_lock *hlock) |
551 | { |
552 | print_lock_name(hlock_class(hlock)); |
553 | printk(", at: "); |
554 | print_ip_sym(hlock->acquire_ip); |
555 | } |
556 | |
557 | static void lockdep_print_held_locks(struct task_struct *curr) |
558 | { |
559 | int i, depth = curr->lockdep_depth; |
560 | |
561 | if (!depth) { |
562 | printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr)); |
563 | return; |
564 | } |
565 | printk("%d lock%s held by %s/%d:\n", |
566 | depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr)); |
567 | |
568 | for (i = 0; i < depth; i++) { |
569 | printk(" #%d: ", i); |
570 | print_lock(curr->held_locks + i); |
571 | } |
572 | } |
573 | |
574 | static void print_kernel_ident(void) |
575 | { |
576 | printk("%s %.*s %s\n", init_utsname()->release, |
577 | (int)strcspn(init_utsname()->version, " "), |
578 | init_utsname()->version, |
579 | print_tainted()); |
580 | } |
581 | |
582 | static int very_verbose(struct lock_class *class) |
583 | { |
584 | #if VERY_VERBOSE |
585 | return class_filter(class); |
586 | #endif |
587 | return 0; |
588 | } |
589 | |
590 | /* |
591 | * Is this the address of a static object: |
592 | */ |
593 | static int static_obj(void *obj) |
594 | { |
595 | unsigned long start = (unsigned long) &_stext, |
596 | end = (unsigned long) &_end, |
597 | addr = (unsigned long) obj; |
598 | |
599 | /* |
600 | * static variable? |
601 | */ |
602 | if ((addr >= start) && (addr < end)) |
603 | return 1; |
604 | |
605 | if (arch_is_kernel_data(addr)) |
606 | return 1; |
607 | |
608 | /* |
609 | * in-kernel percpu var? |
610 | */ |
611 | if (is_kernel_percpu_address(addr)) |
612 | return 1; |
613 | |
614 | /* |
615 | * module static or percpu var? |
616 | */ |
617 | return is_module_address(addr) || is_module_percpu_address(addr); |
618 | } |
619 | |
620 | /* |
621 | * To make lock name printouts unique, we calculate a unique |
622 | * class->name_version generation counter: |
623 | */ |
624 | static int count_matching_names(struct lock_class *new_class) |
625 | { |
626 | struct lock_class *class; |
627 | int count = 0; |
628 | |
629 | if (!new_class->name) |
630 | return 0; |
631 | |
632 | list_for_each_entry(class, &all_lock_classes, lock_entry) { |
633 | if (new_class->key - new_class->subclass == class->key) |
634 | return class->name_version; |
635 | if (class->name && !strcmp(class->name, new_class->name)) |
636 | count = max(count, class->name_version); |
637 | } |
638 | |
639 | return count + 1; |
640 | } |
641 | |
642 | /* |
643 | * Register a lock's class in the hash-table, if the class is not present |
644 | * yet. Otherwise we look it up. We cache the result in the lock object |
645 | * itself, so actual lookup of the hash should be once per lock object. |
646 | */ |
647 | static inline struct lock_class * |
648 | look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) |
649 | { |
650 | struct lockdep_subclass_key *key; |
651 | struct list_head *hash_head; |
652 | struct lock_class *class; |
653 | |
654 | #ifdef CONFIG_DEBUG_LOCKDEP |
655 | /* |
656 | * If the architecture calls into lockdep before initializing |
657 | * the hashes then we'll warn about it later. (we cannot printk |
658 | * right now) |
659 | */ |
660 | if (unlikely(!lockdep_initialized)) { |
661 | lockdep_init(); |
662 | lockdep_init_error = 1; |
663 | lock_init_error = lock->name; |
664 | save_stack_trace(&lockdep_init_trace); |
665 | } |
666 | #endif |
667 | |
668 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { |
669 | debug_locks_off(); |
670 | printk(KERN_ERR |
671 | "BUG: looking up invalid subclass: %u\n", subclass); |
672 | printk(KERN_ERR |
673 | "turning off the locking correctness validator.\n"); |
674 | dump_stack(); |
675 | return NULL; |
676 | } |
677 | |
678 | /* |
679 | * Static locks do not have their class-keys yet - for them the key |
680 | * is the lock object itself: |
681 | */ |
682 | if (unlikely(!lock->key)) |
683 | lock->key = (void *)lock; |
684 | |
685 | /* |
686 | * NOTE: the class-key must be unique. For dynamic locks, a static |
687 | * lock_class_key variable is passed in through the mutex_init() |
688 | * (or spin_lock_init()) call - which acts as the key. For static |
689 | * locks we use the lock object itself as the key. |
690 | */ |
691 | BUILD_BUG_ON(sizeof(struct lock_class_key) > |
692 | sizeof(struct lockdep_map)); |
693 | |
694 | key = lock->key->subkeys + subclass; |
695 | |
696 | hash_head = classhashentry(key); |
697 | |
698 | /* |
699 | * We can walk the hash lockfree, because the hash only |
700 | * grows, and we are careful when adding entries to the end: |
701 | */ |
702 | list_for_each_entry(class, hash_head, hash_entry) { |
703 | if (class->key == key) { |
704 | /* |
705 | * Huh! same key, different name? Did someone trample |
706 | * on some memory? We're most confused. |
707 | */ |
708 | WARN_ON_ONCE(class->name != lock->name); |
709 | return class; |
710 | } |
711 | } |
712 | |
713 | return NULL; |
714 | } |
715 | |
716 | /* |
717 | * Register a lock's class in the hash-table, if the class is not present |
718 | * yet. Otherwise we look it up. We cache the result in the lock object |
719 | * itself, so actual lookup of the hash should be once per lock object. |
720 | */ |
721 | static inline struct lock_class * |
722 | register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) |
723 | { |
724 | struct lockdep_subclass_key *key; |
725 | struct list_head *hash_head; |
726 | struct lock_class *class; |
727 | unsigned long flags; |
728 | |
729 | class = look_up_lock_class(lock, subclass); |
730 | if (likely(class)) |
731 | goto out_set_class_cache; |
732 | |
733 | /* |
734 | * Debug-check: all keys must be persistent! |
735 | */ |
736 | if (!static_obj(lock->key)) { |
737 | debug_locks_off(); |
738 | printk("INFO: trying to register non-static key.\n"); |
739 | printk("the code is fine but needs lockdep annotation.\n"); |
740 | printk("turning off the locking correctness validator.\n"); |
741 | dump_stack(); |
742 | |
743 | return NULL; |
744 | } |
745 | |
746 | key = lock->key->subkeys + subclass; |
747 | hash_head = classhashentry(key); |
748 | |
749 | raw_local_irq_save(flags); |
750 | if (!graph_lock()) { |
751 | raw_local_irq_restore(flags); |
752 | return NULL; |
753 | } |
754 | /* |
755 | * We have to do the hash-walk again, to avoid races |
756 | * with another CPU: |
757 | */ |
758 | list_for_each_entry(class, hash_head, hash_entry) |
759 | if (class->key == key) |
760 | goto out_unlock_set; |
761 | /* |
762 | * Allocate a new key from the static array, and add it to |
763 | * the hash: |
764 | */ |
765 | if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { |
766 | if (!debug_locks_off_graph_unlock()) { |
767 | raw_local_irq_restore(flags); |
768 | return NULL; |
769 | } |
770 | raw_local_irq_restore(flags); |
771 | |
772 | print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!"); |
773 | dump_stack(); |
774 | return NULL; |
775 | } |
776 | class = lock_classes + nr_lock_classes++; |
777 | debug_atomic_inc(nr_unused_locks); |
778 | class->key = key; |
779 | class->name = lock->name; |
780 | class->subclass = subclass; |
781 | INIT_LIST_HEAD(&class->lock_entry); |
782 | INIT_LIST_HEAD(&class->locks_before); |
783 | INIT_LIST_HEAD(&class->locks_after); |
784 | class->name_version = count_matching_names(class); |
785 | /* |
786 | * We use RCU's safe list-add method to make |
787 | * parallel walking of the hash-list safe: |
788 | */ |
789 | list_add_tail_rcu(&class->hash_entry, hash_head); |
790 | /* |
791 | * Add it to the global list of classes: |
792 | */ |
793 | list_add_tail_rcu(&class->lock_entry, &all_lock_classes); |
794 | |
795 | if (verbose(class)) { |
796 | graph_unlock(); |
797 | raw_local_irq_restore(flags); |
798 | |
799 | printk("\nnew class %p: %s", class->key, class->name); |
800 | if (class->name_version > 1) |
801 | printk("#%d", class->name_version); |
802 | printk("\n"); |
803 | dump_stack(); |
804 | |
805 | raw_local_irq_save(flags); |
806 | if (!graph_lock()) { |
807 | raw_local_irq_restore(flags); |
808 | return NULL; |
809 | } |
810 | } |
811 | out_unlock_set: |
812 | graph_unlock(); |
813 | raw_local_irq_restore(flags); |
814 | |
815 | out_set_class_cache: |
816 | if (!subclass || force) |
817 | lock->class_cache[0] = class; |
818 | else if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
819 | lock->class_cache[subclass] = class; |
820 | |
821 | /* |
822 | * Hash collision, did we smoke some? We found a class with a matching |
823 | * hash but the subclass -- which is hashed in -- didn't match. |
824 | */ |
825 | if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) |
826 | return NULL; |
827 | |
828 | return class; |
829 | } |
830 | |
831 | #ifdef CONFIG_PROVE_LOCKING |
832 | /* |
833 | * Allocate a lockdep entry. (assumes the graph_lock held, returns |
834 | * with NULL on failure) |
835 | */ |
836 | static struct lock_list *alloc_list_entry(void) |
837 | { |
838 | if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { |
839 | if (!debug_locks_off_graph_unlock()) |
840 | return NULL; |
841 | |
842 | print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!"); |
843 | dump_stack(); |
844 | return NULL; |
845 | } |
846 | return list_entries + nr_list_entries++; |
847 | } |
848 | |
849 | /* |
850 | * Add a new dependency to the head of the list: |
851 | */ |
852 | static int add_lock_to_list(struct lock_class *class, struct lock_class *this, |
853 | struct list_head *head, unsigned long ip, |
854 | int distance, struct stack_trace *trace) |
855 | { |
856 | struct lock_list *entry; |
857 | /* |
858 | * Lock not present yet - get a new dependency struct and |
859 | * add it to the list: |
860 | */ |
861 | entry = alloc_list_entry(); |
862 | if (!entry) |
863 | return 0; |
864 | |
865 | entry->class = this; |
866 | entry->distance = distance; |
867 | entry->trace = *trace; |
868 | /* |
869 | * Since we never remove from the dependency list, the list can |
870 | * be walked lockless by other CPUs, it's only allocation |
871 | * that must be protected by the spinlock. But this also means |
872 | * we must make new entries visible only once writes to the |
873 | * entry become visible - hence the RCU op: |
874 | */ |
875 | list_add_tail_rcu(&entry->entry, head); |
876 | |
877 | return 1; |
878 | } |
879 | |
880 | /* |
881 | * For good efficiency of modular, we use power of 2 |
882 | */ |
883 | #define MAX_CIRCULAR_QUEUE_SIZE 4096UL |
884 | #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) |
885 | |
886 | /* |
887 | * The circular_queue and helpers is used to implement the |
888 | * breadth-first search(BFS)algorithem, by which we can build |
889 | * the shortest path from the next lock to be acquired to the |
890 | * previous held lock if there is a circular between them. |
891 | */ |
892 | struct circular_queue { |
893 | unsigned long element[MAX_CIRCULAR_QUEUE_SIZE]; |
894 | unsigned int front, rear; |
895 | }; |
896 | |
897 | static struct circular_queue lock_cq; |
898 | |
899 | unsigned int max_bfs_queue_depth; |
900 | |
901 | static unsigned int lockdep_dependency_gen_id; |
902 | |
903 | static inline void __cq_init(struct circular_queue *cq) |
904 | { |
905 | cq->front = cq->rear = 0; |
906 | lockdep_dependency_gen_id++; |
907 | } |
908 | |
909 | static inline int __cq_empty(struct circular_queue *cq) |
910 | { |
911 | return (cq->front == cq->rear); |
912 | } |
913 | |
914 | static inline int __cq_full(struct circular_queue *cq) |
915 | { |
916 | return ((cq->rear + 1) & CQ_MASK) == cq->front; |
917 | } |
918 | |
919 | static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) |
920 | { |
921 | if (__cq_full(cq)) |
922 | return -1; |
923 | |
924 | cq->element[cq->rear] = elem; |
925 | cq->rear = (cq->rear + 1) & CQ_MASK; |
926 | return 0; |
927 | } |
928 | |
929 | static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) |
930 | { |
931 | if (__cq_empty(cq)) |
932 | return -1; |
933 | |
934 | *elem = cq->element[cq->front]; |
935 | cq->front = (cq->front + 1) & CQ_MASK; |
936 | return 0; |
937 | } |
938 | |
939 | static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) |
940 | { |
941 | return (cq->rear - cq->front) & CQ_MASK; |
942 | } |
943 | |
944 | static inline void mark_lock_accessed(struct lock_list *lock, |
945 | struct lock_list *parent) |
946 | { |
947 | unsigned long nr; |
948 | |
949 | nr = lock - list_entries; |
950 | WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ |
951 | lock->parent = parent; |
952 | lock->class->dep_gen_id = lockdep_dependency_gen_id; |
953 | } |
954 | |
955 | static inline unsigned long lock_accessed(struct lock_list *lock) |
956 | { |
957 | unsigned long nr; |
958 | |
959 | nr = lock - list_entries; |
960 | WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ |
961 | return lock->class->dep_gen_id == lockdep_dependency_gen_id; |
962 | } |
963 | |
964 | static inline struct lock_list *get_lock_parent(struct lock_list *child) |
965 | { |
966 | return child->parent; |
967 | } |
968 | |
969 | static inline int get_lock_depth(struct lock_list *child) |
970 | { |
971 | int depth = 0; |
972 | struct lock_list *parent; |
973 | |
974 | while ((parent = get_lock_parent(child))) { |
975 | child = parent; |
976 | depth++; |
977 | } |
978 | return depth; |
979 | } |
980 | |
981 | static int __bfs(struct lock_list *source_entry, |
982 | void *data, |
983 | int (*match)(struct lock_list *entry, void *data), |
984 | struct lock_list **target_entry, |
985 | int forward) |
986 | { |
987 | struct lock_list *entry; |
988 | struct list_head *head; |
989 | struct circular_queue *cq = &lock_cq; |
990 | int ret = 1; |
991 | |
992 | if (match(source_entry, data)) { |
993 | *target_entry = source_entry; |
994 | ret = 0; |
995 | goto exit; |
996 | } |
997 | |
998 | if (forward) |
999 | head = &source_entry->class->locks_after; |
1000 | else |
1001 | head = &source_entry->class->locks_before; |
1002 | |
1003 | if (list_empty(head)) |
1004 | goto exit; |
1005 | |
1006 | __cq_init(cq); |
1007 | __cq_enqueue(cq, (unsigned long)source_entry); |
1008 | |
1009 | while (!__cq_empty(cq)) { |
1010 | struct lock_list *lock; |
1011 | |
1012 | __cq_dequeue(cq, (unsigned long *)&lock); |
1013 | |
1014 | if (!lock->class) { |
1015 | ret = -2; |
1016 | goto exit; |
1017 | } |
1018 | |
1019 | if (forward) |
1020 | head = &lock->class->locks_after; |
1021 | else |
1022 | head = &lock->class->locks_before; |
1023 | |
1024 | list_for_each_entry(entry, head, entry) { |
1025 | if (!lock_accessed(entry)) { |
1026 | unsigned int cq_depth; |
1027 | mark_lock_accessed(entry, lock); |
1028 | if (match(entry, data)) { |
1029 | *target_entry = entry; |
1030 | ret = 0; |
1031 | goto exit; |
1032 | } |
1033 | |
1034 | if (__cq_enqueue(cq, (unsigned long)entry)) { |
1035 | ret = -1; |
1036 | goto exit; |
1037 | } |
1038 | cq_depth = __cq_get_elem_count(cq); |
1039 | if (max_bfs_queue_depth < cq_depth) |
1040 | max_bfs_queue_depth = cq_depth; |
1041 | } |
1042 | } |
1043 | } |
1044 | exit: |
1045 | return ret; |
1046 | } |
1047 | |
1048 | static inline int __bfs_forwards(struct lock_list *src_entry, |
1049 | void *data, |
1050 | int (*match)(struct lock_list *entry, void *data), |
1051 | struct lock_list **target_entry) |
1052 | { |
1053 | return __bfs(src_entry, data, match, target_entry, 1); |
1054 | |
1055 | } |
1056 | |
1057 | static inline int __bfs_backwards(struct lock_list *src_entry, |
1058 | void *data, |
1059 | int (*match)(struct lock_list *entry, void *data), |
1060 | struct lock_list **target_entry) |
1061 | { |
1062 | return __bfs(src_entry, data, match, target_entry, 0); |
1063 | |
1064 | } |
1065 | |
1066 | /* |
1067 | * Recursive, forwards-direction lock-dependency checking, used for |
1068 | * both noncyclic checking and for hardirq-unsafe/softirq-unsafe |
1069 | * checking. |
1070 | */ |
1071 | |
1072 | /* |
1073 | * Print a dependency chain entry (this is only done when a deadlock |
1074 | * has been detected): |
1075 | */ |
1076 | static noinline int |
1077 | print_circular_bug_entry(struct lock_list *target, int depth) |
1078 | { |
1079 | if (debug_locks_silent) |
1080 | return 0; |
1081 | printk("\n-> #%u", depth); |
1082 | print_lock_name(target->class); |
1083 | printk(":\n"); |
1084 | print_stack_trace(&target->trace, 6); |
1085 | |
1086 | return 0; |
1087 | } |
1088 | |
1089 | static void |
1090 | print_circular_lock_scenario(struct held_lock *src, |
1091 | struct held_lock *tgt, |
1092 | struct lock_list *prt) |
1093 | { |
1094 | struct lock_class *source = hlock_class(src); |
1095 | struct lock_class *target = hlock_class(tgt); |
1096 | struct lock_class *parent = prt->class; |
1097 | |
1098 | /* |
1099 | * A direct locking problem where unsafe_class lock is taken |
1100 | * directly by safe_class lock, then all we need to show |
1101 | * is the deadlock scenario, as it is obvious that the |
1102 | * unsafe lock is taken under the safe lock. |
1103 | * |
1104 | * But if there is a chain instead, where the safe lock takes |
1105 | * an intermediate lock (middle_class) where this lock is |
1106 | * not the same as the safe lock, then the lock chain is |
1107 | * used to describe the problem. Otherwise we would need |
1108 | * to show a different CPU case for each link in the chain |
1109 | * from the safe_class lock to the unsafe_class lock. |
1110 | */ |
1111 | if (parent != source) { |
1112 | printk("Chain exists of:\n "); |
1113 | __print_lock_name(source); |
1114 | printk(" --> "); |
1115 | __print_lock_name(parent); |
1116 | printk(" --> "); |
1117 | __print_lock_name(target); |
1118 | printk("\n\n"); |
1119 | } |
1120 | |
1121 | printk(" Possible unsafe locking scenario:\n\n"); |
1122 | printk(" CPU0 CPU1\n"); |
1123 | printk(" ---- ----\n"); |
1124 | printk(" lock("); |
1125 | __print_lock_name(target); |
1126 | printk(");\n"); |
1127 | printk(" lock("); |
1128 | __print_lock_name(parent); |
1129 | printk(");\n"); |
1130 | printk(" lock("); |
1131 | __print_lock_name(target); |
1132 | printk(");\n"); |
1133 | printk(" lock("); |
1134 | __print_lock_name(source); |
1135 | printk(");\n"); |
1136 | printk("\n *** DEADLOCK ***\n\n"); |
1137 | } |
1138 | |
1139 | /* |
1140 | * When a circular dependency is detected, print the |
1141 | * header first: |
1142 | */ |
1143 | static noinline int |
1144 | print_circular_bug_header(struct lock_list *entry, unsigned int depth, |
1145 | struct held_lock *check_src, |
1146 | struct held_lock *check_tgt) |
1147 | { |
1148 | struct task_struct *curr = current; |
1149 | |
1150 | if (debug_locks_silent) |
1151 | return 0; |
1152 | |
1153 | printk("\n"); |
1154 | printk("======================================================\n"); |
1155 | printk("[ INFO: possible circular locking dependency detected ]\n"); |
1156 | print_kernel_ident(); |
1157 | printk("-------------------------------------------------------\n"); |
1158 | printk("%s/%d is trying to acquire lock:\n", |
1159 | curr->comm, task_pid_nr(curr)); |
1160 | print_lock(check_src); |
1161 | printk("\nbut task is already holding lock:\n"); |
1162 | print_lock(check_tgt); |
1163 | printk("\nwhich lock already depends on the new lock.\n\n"); |
1164 | printk("\nthe existing dependency chain (in reverse order) is:\n"); |
1165 | |
1166 | print_circular_bug_entry(entry, depth); |
1167 | |
1168 | return 0; |
1169 | } |
1170 | |
1171 | static inline int class_equal(struct lock_list *entry, void *data) |
1172 | { |
1173 | return entry->class == data; |
1174 | } |
1175 | |
1176 | static noinline int print_circular_bug(struct lock_list *this, |
1177 | struct lock_list *target, |
1178 | struct held_lock *check_src, |
1179 | struct held_lock *check_tgt) |
1180 | { |
1181 | struct task_struct *curr = current; |
1182 | struct lock_list *parent; |
1183 | struct lock_list *first_parent; |
1184 | int depth; |
1185 | |
1186 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
1187 | return 0; |
1188 | |
1189 | if (!save_trace(&this->trace)) |
1190 | return 0; |
1191 | |
1192 | depth = get_lock_depth(target); |
1193 | |
1194 | print_circular_bug_header(target, depth, check_src, check_tgt); |
1195 | |
1196 | parent = get_lock_parent(target); |
1197 | first_parent = parent; |
1198 | |
1199 | while (parent) { |
1200 | print_circular_bug_entry(parent, --depth); |
1201 | parent = get_lock_parent(parent); |
1202 | } |
1203 | |
1204 | printk("\nother info that might help us debug this:\n\n"); |
1205 | print_circular_lock_scenario(check_src, check_tgt, |
1206 | first_parent); |
1207 | |
1208 | lockdep_print_held_locks(curr); |
1209 | |
1210 | printk("\nstack backtrace:\n"); |
1211 | dump_stack(); |
1212 | |
1213 | return 0; |
1214 | } |
1215 | |
1216 | static noinline int print_bfs_bug(int ret) |
1217 | { |
1218 | if (!debug_locks_off_graph_unlock()) |
1219 | return 0; |
1220 | |
1221 | /* |
1222 | * Breadth-first-search failed, graph got corrupted? |
1223 | */ |
1224 | WARN(1, "lockdep bfs error:%d\n", ret); |
1225 | |
1226 | return 0; |
1227 | } |
1228 | |
1229 | static int noop_count(struct lock_list *entry, void *data) |
1230 | { |
1231 | (*(unsigned long *)data)++; |
1232 | return 0; |
1233 | } |
1234 | |
1235 | unsigned long __lockdep_count_forward_deps(struct lock_list *this) |
1236 | { |
1237 | unsigned long count = 0; |
1238 | struct lock_list *uninitialized_var(target_entry); |
1239 | |
1240 | __bfs_forwards(this, (void *)&count, noop_count, &target_entry); |
1241 | |
1242 | return count; |
1243 | } |
1244 | unsigned long lockdep_count_forward_deps(struct lock_class *class) |
1245 | { |
1246 | unsigned long ret, flags; |
1247 | struct lock_list this; |
1248 | |
1249 | this.parent = NULL; |
1250 | this.class = class; |
1251 | |
1252 | local_irq_save(flags); |
1253 | arch_spin_lock(&lockdep_lock); |
1254 | ret = __lockdep_count_forward_deps(&this); |
1255 | arch_spin_unlock(&lockdep_lock); |
1256 | local_irq_restore(flags); |
1257 | |
1258 | return ret; |
1259 | } |
1260 | |
1261 | unsigned long __lockdep_count_backward_deps(struct lock_list *this) |
1262 | { |
1263 | unsigned long count = 0; |
1264 | struct lock_list *uninitialized_var(target_entry); |
1265 | |
1266 | __bfs_backwards(this, (void *)&count, noop_count, &target_entry); |
1267 | |
1268 | return count; |
1269 | } |
1270 | |
1271 | unsigned long lockdep_count_backward_deps(struct lock_class *class) |
1272 | { |
1273 | unsigned long ret, flags; |
1274 | struct lock_list this; |
1275 | |
1276 | this.parent = NULL; |
1277 | this.class = class; |
1278 | |
1279 | local_irq_save(flags); |
1280 | arch_spin_lock(&lockdep_lock); |
1281 | ret = __lockdep_count_backward_deps(&this); |
1282 | arch_spin_unlock(&lockdep_lock); |
1283 | local_irq_restore(flags); |
1284 | |
1285 | return ret; |
1286 | } |
1287 | |
1288 | /* |
1289 | * Prove that the dependency graph starting at <entry> can not |
1290 | * lead to <target>. Print an error and return 0 if it does. |
1291 | */ |
1292 | static noinline int |
1293 | check_noncircular(struct lock_list *root, struct lock_class *target, |
1294 | struct lock_list **target_entry) |
1295 | { |
1296 | int result; |
1297 | |
1298 | debug_atomic_inc(nr_cyclic_checks); |
1299 | |
1300 | result = __bfs_forwards(root, target, class_equal, target_entry); |
1301 | |
1302 | return result; |
1303 | } |
1304 | |
1305 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
1306 | /* |
1307 | * Forwards and backwards subgraph searching, for the purposes of |
1308 | * proving that two subgraphs can be connected by a new dependency |
1309 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. |
1310 | */ |
1311 | |
1312 | static inline int usage_match(struct lock_list *entry, void *bit) |
1313 | { |
1314 | return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); |
1315 | } |
1316 | |
1317 | |
1318 | |
1319 | /* |
1320 | * Find a node in the forwards-direction dependency sub-graph starting |
1321 | * at @root->class that matches @bit. |
1322 | * |
1323 | * Return 0 if such a node exists in the subgraph, and put that node |
1324 | * into *@target_entry. |
1325 | * |
1326 | * Return 1 otherwise and keep *@target_entry unchanged. |
1327 | * Return <0 on error. |
1328 | */ |
1329 | static int |
1330 | find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, |
1331 | struct lock_list **target_entry) |
1332 | { |
1333 | int result; |
1334 | |
1335 | debug_atomic_inc(nr_find_usage_forwards_checks); |
1336 | |
1337 | result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); |
1338 | |
1339 | return result; |
1340 | } |
1341 | |
1342 | /* |
1343 | * Find a node in the backwards-direction dependency sub-graph starting |
1344 | * at @root->class that matches @bit. |
1345 | * |
1346 | * Return 0 if such a node exists in the subgraph, and put that node |
1347 | * into *@target_entry. |
1348 | * |
1349 | * Return 1 otherwise and keep *@target_entry unchanged. |
1350 | * Return <0 on error. |
1351 | */ |
1352 | static int |
1353 | find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, |
1354 | struct lock_list **target_entry) |
1355 | { |
1356 | int result; |
1357 | |
1358 | debug_atomic_inc(nr_find_usage_backwards_checks); |
1359 | |
1360 | result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); |
1361 | |
1362 | return result; |
1363 | } |
1364 | |
1365 | static void print_lock_class_header(struct lock_class *class, int depth) |
1366 | { |
1367 | int bit; |
1368 | |
1369 | printk("%*s->", depth, ""); |
1370 | print_lock_name(class); |
1371 | printk(" ops: %lu", class->ops); |
1372 | printk(" {\n"); |
1373 | |
1374 | for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { |
1375 | if (class->usage_mask & (1 << bit)) { |
1376 | int len = depth; |
1377 | |
1378 | len += printk("%*s %s", depth, "", usage_str[bit]); |
1379 | len += printk(" at:\n"); |
1380 | print_stack_trace(class->usage_traces + bit, len); |
1381 | } |
1382 | } |
1383 | printk("%*s }\n", depth, ""); |
1384 | |
1385 | printk("%*s ... key at: ",depth,""); |
1386 | print_ip_sym((unsigned long)class->key); |
1387 | } |
1388 | |
1389 | /* |
1390 | * printk the shortest lock dependencies from @start to @end in reverse order: |
1391 | */ |
1392 | static void __used |
1393 | print_shortest_lock_dependencies(struct lock_list *leaf, |
1394 | struct lock_list *root) |
1395 | { |
1396 | struct lock_list *entry = leaf; |
1397 | int depth; |
1398 | |
1399 | /*compute depth from generated tree by BFS*/ |
1400 | depth = get_lock_depth(leaf); |
1401 | |
1402 | do { |
1403 | print_lock_class_header(entry->class, depth); |
1404 | printk("%*s ... acquired at:\n", depth, ""); |
1405 | print_stack_trace(&entry->trace, 2); |
1406 | printk("\n"); |
1407 | |
1408 | if (depth == 0 && (entry != root)) { |
1409 | printk("lockdep:%s bad path found in chain graph\n", __func__); |
1410 | break; |
1411 | } |
1412 | |
1413 | entry = get_lock_parent(entry); |
1414 | depth--; |
1415 | } while (entry && (depth >= 0)); |
1416 | |
1417 | return; |
1418 | } |
1419 | |
1420 | static void |
1421 | print_irq_lock_scenario(struct lock_list *safe_entry, |
1422 | struct lock_list *unsafe_entry, |
1423 | struct lock_class *prev_class, |
1424 | struct lock_class *next_class) |
1425 | { |
1426 | struct lock_class *safe_class = safe_entry->class; |
1427 | struct lock_class *unsafe_class = unsafe_entry->class; |
1428 | struct lock_class *middle_class = prev_class; |
1429 | |
1430 | if (middle_class == safe_class) |
1431 | middle_class = next_class; |
1432 | |
1433 | /* |
1434 | * A direct locking problem where unsafe_class lock is taken |
1435 | * directly by safe_class lock, then all we need to show |
1436 | * is the deadlock scenario, as it is obvious that the |
1437 | * unsafe lock is taken under the safe lock. |
1438 | * |
1439 | * But if there is a chain instead, where the safe lock takes |
1440 | * an intermediate lock (middle_class) where this lock is |
1441 | * not the same as the safe lock, then the lock chain is |
1442 | * used to describe the problem. Otherwise we would need |
1443 | * to show a different CPU case for each link in the chain |
1444 | * from the safe_class lock to the unsafe_class lock. |
1445 | */ |
1446 | if (middle_class != unsafe_class) { |
1447 | printk("Chain exists of:\n "); |
1448 | __print_lock_name(safe_class); |
1449 | printk(" --> "); |
1450 | __print_lock_name(middle_class); |
1451 | printk(" --> "); |
1452 | __print_lock_name(unsafe_class); |
1453 | printk("\n\n"); |
1454 | } |
1455 | |
1456 | printk(" Possible interrupt unsafe locking scenario:\n\n"); |
1457 | printk(" CPU0 CPU1\n"); |
1458 | printk(" ---- ----\n"); |
1459 | printk(" lock("); |
1460 | __print_lock_name(unsafe_class); |
1461 | printk(");\n"); |
1462 | printk(" local_irq_disable();\n"); |
1463 | printk(" lock("); |
1464 | __print_lock_name(safe_class); |
1465 | printk(");\n"); |
1466 | printk(" lock("); |
1467 | __print_lock_name(middle_class); |
1468 | printk(");\n"); |
1469 | printk(" <Interrupt>\n"); |
1470 | printk(" lock("); |
1471 | __print_lock_name(safe_class); |
1472 | printk(");\n"); |
1473 | printk("\n *** DEADLOCK ***\n\n"); |
1474 | } |
1475 | |
1476 | static int |
1477 | print_bad_irq_dependency(struct task_struct *curr, |
1478 | struct lock_list *prev_root, |
1479 | struct lock_list *next_root, |
1480 | struct lock_list *backwards_entry, |
1481 | struct lock_list *forwards_entry, |
1482 | struct held_lock *prev, |
1483 | struct held_lock *next, |
1484 | enum lock_usage_bit bit1, |
1485 | enum lock_usage_bit bit2, |
1486 | const char *irqclass) |
1487 | { |
1488 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
1489 | return 0; |
1490 | |
1491 | printk("\n"); |
1492 | printk("======================================================\n"); |
1493 | printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", |
1494 | irqclass, irqclass); |
1495 | print_kernel_ident(); |
1496 | printk("------------------------------------------------------\n"); |
1497 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", |
1498 | curr->comm, task_pid_nr(curr), |
1499 | curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, |
1500 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, |
1501 | curr->hardirqs_enabled, |
1502 | curr->softirqs_enabled); |
1503 | print_lock(next); |
1504 | |
1505 | printk("\nand this task is already holding:\n"); |
1506 | print_lock(prev); |
1507 | printk("which would create a new lock dependency:\n"); |
1508 | print_lock_name(hlock_class(prev)); |
1509 | printk(" ->"); |
1510 | print_lock_name(hlock_class(next)); |
1511 | printk("\n"); |
1512 | |
1513 | printk("\nbut this new dependency connects a %s-irq-safe lock:\n", |
1514 | irqclass); |
1515 | print_lock_name(backwards_entry->class); |
1516 | printk("\n... which became %s-irq-safe at:\n", irqclass); |
1517 | |
1518 | print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); |
1519 | |
1520 | printk("\nto a %s-irq-unsafe lock:\n", irqclass); |
1521 | print_lock_name(forwards_entry->class); |
1522 | printk("\n... which became %s-irq-unsafe at:\n", irqclass); |
1523 | printk("..."); |
1524 | |
1525 | print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); |
1526 | |
1527 | printk("\nother info that might help us debug this:\n\n"); |
1528 | print_irq_lock_scenario(backwards_entry, forwards_entry, |
1529 | hlock_class(prev), hlock_class(next)); |
1530 | |
1531 | lockdep_print_held_locks(curr); |
1532 | |
1533 | printk("\nthe dependencies between %s-irq-safe lock", irqclass); |
1534 | printk(" and the holding lock:\n"); |
1535 | if (!save_trace(&prev_root->trace)) |
1536 | return 0; |
1537 | print_shortest_lock_dependencies(backwards_entry, prev_root); |
1538 | |
1539 | printk("\nthe dependencies between the lock to be acquired"); |
1540 | printk(" and %s-irq-unsafe lock:\n", irqclass); |
1541 | if (!save_trace(&next_root->trace)) |
1542 | return 0; |
1543 | print_shortest_lock_dependencies(forwards_entry, next_root); |
1544 | |
1545 | printk("\nstack backtrace:\n"); |
1546 | dump_stack(); |
1547 | |
1548 | return 0; |
1549 | } |
1550 | |
1551 | static int |
1552 | check_usage(struct task_struct *curr, struct held_lock *prev, |
1553 | struct held_lock *next, enum lock_usage_bit bit_backwards, |
1554 | enum lock_usage_bit bit_forwards, const char *irqclass) |
1555 | { |
1556 | int ret; |
1557 | struct lock_list this, that; |
1558 | struct lock_list *uninitialized_var(target_entry); |
1559 | struct lock_list *uninitialized_var(target_entry1); |
1560 | |
1561 | this.parent = NULL; |
1562 | |
1563 | this.class = hlock_class(prev); |
1564 | ret = find_usage_backwards(&this, bit_backwards, &target_entry); |
1565 | if (ret < 0) |
1566 | return print_bfs_bug(ret); |
1567 | if (ret == 1) |
1568 | return ret; |
1569 | |
1570 | that.parent = NULL; |
1571 | that.class = hlock_class(next); |
1572 | ret = find_usage_forwards(&that, bit_forwards, &target_entry1); |
1573 | if (ret < 0) |
1574 | return print_bfs_bug(ret); |
1575 | if (ret == 1) |
1576 | return ret; |
1577 | |
1578 | return print_bad_irq_dependency(curr, &this, &that, |
1579 | target_entry, target_entry1, |
1580 | prev, next, |
1581 | bit_backwards, bit_forwards, irqclass); |
1582 | } |
1583 | |
1584 | static const char *state_names[] = { |
1585 | #define LOCKDEP_STATE(__STATE) \ |
1586 | __stringify(__STATE), |
1587 | #include "lockdep_states.h" |
1588 | #undef LOCKDEP_STATE |
1589 | }; |
1590 | |
1591 | static const char *state_rnames[] = { |
1592 | #define LOCKDEP_STATE(__STATE) \ |
1593 | __stringify(__STATE)"-READ", |
1594 | #include "lockdep_states.h" |
1595 | #undef LOCKDEP_STATE |
1596 | }; |
1597 | |
1598 | static inline const char *state_name(enum lock_usage_bit bit) |
1599 | { |
1600 | return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2]; |
1601 | } |
1602 | |
1603 | static int exclusive_bit(int new_bit) |
1604 | { |
1605 | /* |
1606 | * USED_IN |
1607 | * USED_IN_READ |
1608 | * ENABLED |
1609 | * ENABLED_READ |
1610 | * |
1611 | * bit 0 - write/read |
1612 | * bit 1 - used_in/enabled |
1613 | * bit 2+ state |
1614 | */ |
1615 | |
1616 | int state = new_bit & ~3; |
1617 | int dir = new_bit & 2; |
1618 | |
1619 | /* |
1620 | * keep state, bit flip the direction and strip read. |
1621 | */ |
1622 | return state | (dir ^ 2); |
1623 | } |
1624 | |
1625 | static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, |
1626 | struct held_lock *next, enum lock_usage_bit bit) |
1627 | { |
1628 | /* |
1629 | * Prove that the new dependency does not connect a hardirq-safe |
1630 | * lock with a hardirq-unsafe lock - to achieve this we search |
1631 | * the backwards-subgraph starting at <prev>, and the |
1632 | * forwards-subgraph starting at <next>: |
1633 | */ |
1634 | if (!check_usage(curr, prev, next, bit, |
1635 | exclusive_bit(bit), state_name(bit))) |
1636 | return 0; |
1637 | |
1638 | bit++; /* _READ */ |
1639 | |
1640 | /* |
1641 | * Prove that the new dependency does not connect a hardirq-safe-read |
1642 | * lock with a hardirq-unsafe lock - to achieve this we search |
1643 | * the backwards-subgraph starting at <prev>, and the |
1644 | * forwards-subgraph starting at <next>: |
1645 | */ |
1646 | if (!check_usage(curr, prev, next, bit, |
1647 | exclusive_bit(bit), state_name(bit))) |
1648 | return 0; |
1649 | |
1650 | return 1; |
1651 | } |
1652 | |
1653 | static int |
1654 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, |
1655 | struct held_lock *next) |
1656 | { |
1657 | #define LOCKDEP_STATE(__STATE) \ |
1658 | if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ |
1659 | return 0; |
1660 | #include "lockdep_states.h" |
1661 | #undef LOCKDEP_STATE |
1662 | |
1663 | return 1; |
1664 | } |
1665 | |
1666 | static void inc_chains(void) |
1667 | { |
1668 | if (current->hardirq_context) |
1669 | nr_hardirq_chains++; |
1670 | else { |
1671 | if (current->softirq_context) |
1672 | nr_softirq_chains++; |
1673 | else |
1674 | nr_process_chains++; |
1675 | } |
1676 | } |
1677 | |
1678 | #else |
1679 | |
1680 | static inline int |
1681 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, |
1682 | struct held_lock *next) |
1683 | { |
1684 | return 1; |
1685 | } |
1686 | |
1687 | static inline void inc_chains(void) |
1688 | { |
1689 | nr_process_chains++; |
1690 | } |
1691 | |
1692 | #endif |
1693 | |
1694 | static void |
1695 | print_deadlock_scenario(struct held_lock *nxt, |
1696 | struct held_lock *prv) |
1697 | { |
1698 | struct lock_class *next = hlock_class(nxt); |
1699 | struct lock_class *prev = hlock_class(prv); |
1700 | |
1701 | printk(" Possible unsafe locking scenario:\n\n"); |
1702 | printk(" CPU0\n"); |
1703 | printk(" ----\n"); |
1704 | printk(" lock("); |
1705 | __print_lock_name(prev); |
1706 | printk(");\n"); |
1707 | printk(" lock("); |
1708 | __print_lock_name(next); |
1709 | printk(");\n"); |
1710 | printk("\n *** DEADLOCK ***\n\n"); |
1711 | printk(" May be due to missing lock nesting notation\n\n"); |
1712 | } |
1713 | |
1714 | static int |
1715 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, |
1716 | struct held_lock *next) |
1717 | { |
1718 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
1719 | return 0; |
1720 | |
1721 | printk("\n"); |
1722 | printk("=============================================\n"); |
1723 | printk("[ INFO: possible recursive locking detected ]\n"); |
1724 | print_kernel_ident(); |
1725 | printk("---------------------------------------------\n"); |
1726 | printk("%s/%d is trying to acquire lock:\n", |
1727 | curr->comm, task_pid_nr(curr)); |
1728 | print_lock(next); |
1729 | printk("\nbut task is already holding lock:\n"); |
1730 | print_lock(prev); |
1731 | |
1732 | printk("\nother info that might help us debug this:\n"); |
1733 | print_deadlock_scenario(next, prev); |
1734 | lockdep_print_held_locks(curr); |
1735 | |
1736 | printk("\nstack backtrace:\n"); |
1737 | dump_stack(); |
1738 | |
1739 | return 0; |
1740 | } |
1741 | |
1742 | /* |
1743 | * Check whether we are holding such a class already. |
1744 | * |
1745 | * (Note that this has to be done separately, because the graph cannot |
1746 | * detect such classes of deadlocks.) |
1747 | * |
1748 | * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read |
1749 | */ |
1750 | static int |
1751 | check_deadlock(struct task_struct *curr, struct held_lock *next, |
1752 | struct lockdep_map *next_instance, int read) |
1753 | { |
1754 | struct held_lock *prev; |
1755 | struct held_lock *nest = NULL; |
1756 | int i; |
1757 | |
1758 | for (i = 0; i < curr->lockdep_depth; i++) { |
1759 | prev = curr->held_locks + i; |
1760 | |
1761 | if (prev->instance == next->nest_lock) |
1762 | nest = prev; |
1763 | |
1764 | if (hlock_class(prev) != hlock_class(next)) |
1765 | continue; |
1766 | |
1767 | /* |
1768 | * Allow read-after-read recursion of the same |
1769 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
1770 | */ |
1771 | if ((read == 2) && prev->read) |
1772 | return 2; |
1773 | |
1774 | /* |
1775 | * We're holding the nest_lock, which serializes this lock's |
1776 | * nesting behaviour. |
1777 | */ |
1778 | if (nest) |
1779 | return 2; |
1780 | |
1781 | return print_deadlock_bug(curr, prev, next); |
1782 | } |
1783 | return 1; |
1784 | } |
1785 | |
1786 | /* |
1787 | * There was a chain-cache miss, and we are about to add a new dependency |
1788 | * to a previous lock. We recursively validate the following rules: |
1789 | * |
1790 | * - would the adding of the <prev> -> <next> dependency create a |
1791 | * circular dependency in the graph? [== circular deadlock] |
1792 | * |
1793 | * - does the new prev->next dependency connect any hardirq-safe lock |
1794 | * (in the full backwards-subgraph starting at <prev>) with any |
1795 | * hardirq-unsafe lock (in the full forwards-subgraph starting at |
1796 | * <next>)? [== illegal lock inversion with hardirq contexts] |
1797 | * |
1798 | * - does the new prev->next dependency connect any softirq-safe lock |
1799 | * (in the full backwards-subgraph starting at <prev>) with any |
1800 | * softirq-unsafe lock (in the full forwards-subgraph starting at |
1801 | * <next>)? [== illegal lock inversion with softirq contexts] |
1802 | * |
1803 | * any of these scenarios could lead to a deadlock. |
1804 | * |
1805 | * Then if all the validations pass, we add the forwards and backwards |
1806 | * dependency. |
1807 | */ |
1808 | static int |
1809 | check_prev_add(struct task_struct *curr, struct held_lock *prev, |
1810 | struct held_lock *next, int distance, int trylock_loop) |
1811 | { |
1812 | struct lock_list *entry; |
1813 | int ret; |
1814 | struct lock_list this; |
1815 | struct lock_list *uninitialized_var(target_entry); |
1816 | /* |
1817 | * Static variable, serialized by the graph_lock(). |
1818 | * |
1819 | * We use this static variable to save the stack trace in case |
1820 | * we call into this function multiple times due to encountering |
1821 | * trylocks in the held lock stack. |
1822 | */ |
1823 | static struct stack_trace trace; |
1824 | |
1825 | /* |
1826 | * Prove that the new <prev> -> <next> dependency would not |
1827 | * create a circular dependency in the graph. (We do this by |
1828 | * forward-recursing into the graph starting at <next>, and |
1829 | * checking whether we can reach <prev>.) |
1830 | * |
1831 | * We are using global variables to control the recursion, to |
1832 | * keep the stackframe size of the recursive functions low: |
1833 | */ |
1834 | this.class = hlock_class(next); |
1835 | this.parent = NULL; |
1836 | ret = check_noncircular(&this, hlock_class(prev), &target_entry); |
1837 | if (unlikely(!ret)) |
1838 | return print_circular_bug(&this, target_entry, next, prev); |
1839 | else if (unlikely(ret < 0)) |
1840 | return print_bfs_bug(ret); |
1841 | |
1842 | if (!check_prev_add_irq(curr, prev, next)) |
1843 | return 0; |
1844 | |
1845 | /* |
1846 | * For recursive read-locks we do all the dependency checks, |
1847 | * but we dont store read-triggered dependencies (only |
1848 | * write-triggered dependencies). This ensures that only the |
1849 | * write-side dependencies matter, and that if for example a |
1850 | * write-lock never takes any other locks, then the reads are |
1851 | * equivalent to a NOP. |
1852 | */ |
1853 | if (next->read == 2 || prev->read == 2) |
1854 | return 1; |
1855 | /* |
1856 | * Is the <prev> -> <next> dependency already present? |
1857 | * |
1858 | * (this may occur even though this is a new chain: consider |
1859 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 |
1860 | * chains - the second one will be new, but L1 already has |
1861 | * L2 added to its dependency list, due to the first chain.) |
1862 | */ |
1863 | list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { |
1864 | if (entry->class == hlock_class(next)) { |
1865 | if (distance == 1) |
1866 | entry->distance = 1; |
1867 | return 2; |
1868 | } |
1869 | } |
1870 | |
1871 | if (!trylock_loop && !save_trace(&trace)) |
1872 | return 0; |
1873 | |
1874 | /* |
1875 | * Ok, all validations passed, add the new lock |
1876 | * to the previous lock's dependency list: |
1877 | */ |
1878 | ret = add_lock_to_list(hlock_class(prev), hlock_class(next), |
1879 | &hlock_class(prev)->locks_after, |
1880 | next->acquire_ip, distance, &trace); |
1881 | |
1882 | if (!ret) |
1883 | return 0; |
1884 | |
1885 | ret = add_lock_to_list(hlock_class(next), hlock_class(prev), |
1886 | &hlock_class(next)->locks_before, |
1887 | next->acquire_ip, distance, &trace); |
1888 | if (!ret) |
1889 | return 0; |
1890 | |
1891 | /* |
1892 | * Debugging printouts: |
1893 | */ |
1894 | if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) { |
1895 | graph_unlock(); |
1896 | printk("\n new dependency: "); |
1897 | print_lock_name(hlock_class(prev)); |
1898 | printk(" => "); |
1899 | print_lock_name(hlock_class(next)); |
1900 | printk("\n"); |
1901 | dump_stack(); |
1902 | return graph_lock(); |
1903 | } |
1904 | return 1; |
1905 | } |
1906 | |
1907 | /* |
1908 | * Add the dependency to all directly-previous locks that are 'relevant'. |
1909 | * The ones that are relevant are (in increasing distance from curr): |
1910 | * all consecutive trylock entries and the final non-trylock entry - or |
1911 | * the end of this context's lock-chain - whichever comes first. |
1912 | */ |
1913 | static int |
1914 | check_prevs_add(struct task_struct *curr, struct held_lock *next) |
1915 | { |
1916 | int depth = curr->lockdep_depth; |
1917 | int trylock_loop = 0; |
1918 | struct held_lock *hlock; |
1919 | |
1920 | /* |
1921 | * Debugging checks. |
1922 | * |
1923 | * Depth must not be zero for a non-head lock: |
1924 | */ |
1925 | if (!depth) |
1926 | goto out_bug; |
1927 | /* |
1928 | * At least two relevant locks must exist for this |
1929 | * to be a head: |
1930 | */ |
1931 | if (curr->held_locks[depth].irq_context != |
1932 | curr->held_locks[depth-1].irq_context) |
1933 | goto out_bug; |
1934 | |
1935 | for (;;) { |
1936 | int distance = curr->lockdep_depth - depth + 1; |
1937 | hlock = curr->held_locks + depth-1; |
1938 | /* |
1939 | * Only non-recursive-read entries get new dependencies |
1940 | * added: |
1941 | */ |
1942 | if (hlock->read != 2) { |
1943 | if (!check_prev_add(curr, hlock, next, |
1944 | distance, trylock_loop)) |
1945 | return 0; |
1946 | /* |
1947 | * Stop after the first non-trylock entry, |
1948 | * as non-trylock entries have added their |
1949 | * own direct dependencies already, so this |
1950 | * lock is connected to them indirectly: |
1951 | */ |
1952 | if (!hlock->trylock) |
1953 | break; |
1954 | } |
1955 | depth--; |
1956 | /* |
1957 | * End of lock-stack? |
1958 | */ |
1959 | if (!depth) |
1960 | break; |
1961 | /* |
1962 | * Stop the search if we cross into another context: |
1963 | */ |
1964 | if (curr->held_locks[depth].irq_context != |
1965 | curr->held_locks[depth-1].irq_context) |
1966 | break; |
1967 | trylock_loop = 1; |
1968 | } |
1969 | return 1; |
1970 | out_bug: |
1971 | if (!debug_locks_off_graph_unlock()) |
1972 | return 0; |
1973 | |
1974 | /* |
1975 | * Clearly we all shouldn't be here, but since we made it we |
1976 | * can reliable say we messed up our state. See the above two |
1977 | * gotos for reasons why we could possibly end up here. |
1978 | */ |
1979 | WARN_ON(1); |
1980 | |
1981 | return 0; |
1982 | } |
1983 | |
1984 | unsigned long nr_lock_chains; |
1985 | struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; |
1986 | int nr_chain_hlocks; |
1987 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; |
1988 | |
1989 | struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) |
1990 | { |
1991 | return lock_classes + chain_hlocks[chain->base + i]; |
1992 | } |
1993 | |
1994 | /* |
1995 | * Look up a dependency chain. If the key is not present yet then |
1996 | * add it and return 1 - in this case the new dependency chain is |
1997 | * validated. If the key is already hashed, return 0. |
1998 | * (On return with 1 graph_lock is held.) |
1999 | */ |
2000 | static inline int lookup_chain_cache(struct task_struct *curr, |
2001 | struct held_lock *hlock, |
2002 | u64 chain_key) |
2003 | { |
2004 | struct lock_class *class = hlock_class(hlock); |
2005 | struct list_head *hash_head = chainhashentry(chain_key); |
2006 | struct lock_chain *chain; |
2007 | struct held_lock *hlock_curr; |
2008 | int i, j; |
2009 | |
2010 | /* |
2011 | * We might need to take the graph lock, ensure we've got IRQs |
2012 | * disabled to make this an IRQ-safe lock.. for recursion reasons |
2013 | * lockdep won't complain about its own locking errors. |
2014 | */ |
2015 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2016 | return 0; |
2017 | /* |
2018 | * We can walk it lock-free, because entries only get added |
2019 | * to the hash: |
2020 | */ |
2021 | list_for_each_entry(chain, hash_head, entry) { |
2022 | if (chain->chain_key == chain_key) { |
2023 | cache_hit: |
2024 | debug_atomic_inc(chain_lookup_hits); |
2025 | if (very_verbose(class)) |
2026 | printk("\nhash chain already cached, key: " |
2027 | "%016Lx tail class: [%p] %s\n", |
2028 | (unsigned long long)chain_key, |
2029 | class->key, class->name); |
2030 | return 0; |
2031 | } |
2032 | } |
2033 | if (very_verbose(class)) |
2034 | printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", |
2035 | (unsigned long long)chain_key, class->key, class->name); |
2036 | /* |
2037 | * Allocate a new chain entry from the static array, and add |
2038 | * it to the hash: |
2039 | */ |
2040 | if (!graph_lock()) |
2041 | return 0; |
2042 | /* |
2043 | * We have to walk the chain again locked - to avoid duplicates: |
2044 | */ |
2045 | list_for_each_entry(chain, hash_head, entry) { |
2046 | if (chain->chain_key == chain_key) { |
2047 | graph_unlock(); |
2048 | goto cache_hit; |
2049 | } |
2050 | } |
2051 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { |
2052 | if (!debug_locks_off_graph_unlock()) |
2053 | return 0; |
2054 | |
2055 | print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); |
2056 | dump_stack(); |
2057 | return 0; |
2058 | } |
2059 | chain = lock_chains + nr_lock_chains++; |
2060 | chain->chain_key = chain_key; |
2061 | chain->irq_context = hlock->irq_context; |
2062 | /* Find the first held_lock of current chain */ |
2063 | for (i = curr->lockdep_depth - 1; i >= 0; i--) { |
2064 | hlock_curr = curr->held_locks + i; |
2065 | if (hlock_curr->irq_context != hlock->irq_context) |
2066 | break; |
2067 | } |
2068 | i++; |
2069 | chain->depth = curr->lockdep_depth + 1 - i; |
2070 | if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { |
2071 | chain->base = nr_chain_hlocks; |
2072 | nr_chain_hlocks += chain->depth; |
2073 | for (j = 0; j < chain->depth - 1; j++, i++) { |
2074 | int lock_id = curr->held_locks[i].class_idx - 1; |
2075 | chain_hlocks[chain->base + j] = lock_id; |
2076 | } |
2077 | chain_hlocks[chain->base + j] = class - lock_classes; |
2078 | } |
2079 | list_add_tail_rcu(&chain->entry, hash_head); |
2080 | debug_atomic_inc(chain_lookup_misses); |
2081 | inc_chains(); |
2082 | |
2083 | return 1; |
2084 | } |
2085 | |
2086 | static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, |
2087 | struct held_lock *hlock, int chain_head, u64 chain_key) |
2088 | { |
2089 | /* |
2090 | * Trylock needs to maintain the stack of held locks, but it |
2091 | * does not add new dependencies, because trylock can be done |
2092 | * in any order. |
2093 | * |
2094 | * We look up the chain_key and do the O(N^2) check and update of |
2095 | * the dependencies only if this is a new dependency chain. |
2096 | * (If lookup_chain_cache() returns with 1 it acquires |
2097 | * graph_lock for us) |
2098 | */ |
2099 | if (!hlock->trylock && (hlock->check == 2) && |
2100 | lookup_chain_cache(curr, hlock, chain_key)) { |
2101 | /* |
2102 | * Check whether last held lock: |
2103 | * |
2104 | * - is irq-safe, if this lock is irq-unsafe |
2105 | * - is softirq-safe, if this lock is hardirq-unsafe |
2106 | * |
2107 | * And check whether the new lock's dependency graph |
2108 | * could lead back to the previous lock. |
2109 | * |
2110 | * any of these scenarios could lead to a deadlock. If |
2111 | * All validations |
2112 | */ |
2113 | int ret = check_deadlock(curr, hlock, lock, hlock->read); |
2114 | |
2115 | if (!ret) |
2116 | return 0; |
2117 | /* |
2118 | * Mark recursive read, as we jump over it when |
2119 | * building dependencies (just like we jump over |
2120 | * trylock entries): |
2121 | */ |
2122 | if (ret == 2) |
2123 | hlock->read = 2; |
2124 | /* |
2125 | * Add dependency only if this lock is not the head |
2126 | * of the chain, and if it's not a secondary read-lock: |
2127 | */ |
2128 | if (!chain_head && ret != 2) |
2129 | if (!check_prevs_add(curr, hlock)) |
2130 | return 0; |
2131 | graph_unlock(); |
2132 | } else |
2133 | /* after lookup_chain_cache(): */ |
2134 | if (unlikely(!debug_locks)) |
2135 | return 0; |
2136 | |
2137 | return 1; |
2138 | } |
2139 | #else |
2140 | static inline int validate_chain(struct task_struct *curr, |
2141 | struct lockdep_map *lock, struct held_lock *hlock, |
2142 | int chain_head, u64 chain_key) |
2143 | { |
2144 | return 1; |
2145 | } |
2146 | #endif |
2147 | |
2148 | /* |
2149 | * We are building curr_chain_key incrementally, so double-check |
2150 | * it from scratch, to make sure that it's done correctly: |
2151 | */ |
2152 | static void check_chain_key(struct task_struct *curr) |
2153 | { |
2154 | #ifdef CONFIG_DEBUG_LOCKDEP |
2155 | struct held_lock *hlock, *prev_hlock = NULL; |
2156 | unsigned int i, id; |
2157 | u64 chain_key = 0; |
2158 | |
2159 | for (i = 0; i < curr->lockdep_depth; i++) { |
2160 | hlock = curr->held_locks + i; |
2161 | if (chain_key != hlock->prev_chain_key) { |
2162 | debug_locks_off(); |
2163 | /* |
2164 | * We got mighty confused, our chain keys don't match |
2165 | * with what we expect, someone trample on our task state? |
2166 | */ |
2167 | WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", |
2168 | curr->lockdep_depth, i, |
2169 | (unsigned long long)chain_key, |
2170 | (unsigned long long)hlock->prev_chain_key); |
2171 | return; |
2172 | } |
2173 | id = hlock->class_idx - 1; |
2174 | /* |
2175 | * Whoops ran out of static storage again? |
2176 | */ |
2177 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) |
2178 | return; |
2179 | |
2180 | if (prev_hlock && (prev_hlock->irq_context != |
2181 | hlock->irq_context)) |
2182 | chain_key = 0; |
2183 | chain_key = iterate_chain_key(chain_key, id); |
2184 | prev_hlock = hlock; |
2185 | } |
2186 | if (chain_key != curr->curr_chain_key) { |
2187 | debug_locks_off(); |
2188 | /* |
2189 | * More smoking hash instead of calculating it, damn see these |
2190 | * numbers float.. I bet that a pink elephant stepped on my memory. |
2191 | */ |
2192 | WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", |
2193 | curr->lockdep_depth, i, |
2194 | (unsigned long long)chain_key, |
2195 | (unsigned long long)curr->curr_chain_key); |
2196 | } |
2197 | #endif |
2198 | } |
2199 | |
2200 | static void |
2201 | print_usage_bug_scenario(struct held_lock *lock) |
2202 | { |
2203 | struct lock_class *class = hlock_class(lock); |
2204 | |
2205 | printk(" Possible unsafe locking scenario:\n\n"); |
2206 | printk(" CPU0\n"); |
2207 | printk(" ----\n"); |
2208 | printk(" lock("); |
2209 | __print_lock_name(class); |
2210 | printk(");\n"); |
2211 | printk(" <Interrupt>\n"); |
2212 | printk(" lock("); |
2213 | __print_lock_name(class); |
2214 | printk(");\n"); |
2215 | printk("\n *** DEADLOCK ***\n\n"); |
2216 | } |
2217 | |
2218 | static int |
2219 | print_usage_bug(struct task_struct *curr, struct held_lock *this, |
2220 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) |
2221 | { |
2222 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
2223 | return 0; |
2224 | |
2225 | printk("\n"); |
2226 | printk("=================================\n"); |
2227 | printk("[ INFO: inconsistent lock state ]\n"); |
2228 | print_kernel_ident(); |
2229 | printk("---------------------------------\n"); |
2230 | |
2231 | printk("inconsistent {%s} -> {%s} usage.\n", |
2232 | usage_str[prev_bit], usage_str[new_bit]); |
2233 | |
2234 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", |
2235 | curr->comm, task_pid_nr(curr), |
2236 | trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, |
2237 | trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, |
2238 | trace_hardirqs_enabled(curr), |
2239 | trace_softirqs_enabled(curr)); |
2240 | print_lock(this); |
2241 | |
2242 | printk("{%s} state was registered at:\n", usage_str[prev_bit]); |
2243 | print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1); |
2244 | |
2245 | print_irqtrace_events(curr); |
2246 | printk("\nother info that might help us debug this:\n"); |
2247 | print_usage_bug_scenario(this); |
2248 | |
2249 | lockdep_print_held_locks(curr); |
2250 | |
2251 | printk("\nstack backtrace:\n"); |
2252 | dump_stack(); |
2253 | |
2254 | return 0; |
2255 | } |
2256 | |
2257 | /* |
2258 | * Print out an error if an invalid bit is set: |
2259 | */ |
2260 | static inline int |
2261 | valid_state(struct task_struct *curr, struct held_lock *this, |
2262 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) |
2263 | { |
2264 | if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) |
2265 | return print_usage_bug(curr, this, bad_bit, new_bit); |
2266 | return 1; |
2267 | } |
2268 | |
2269 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
2270 | enum lock_usage_bit new_bit); |
2271 | |
2272 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
2273 | |
2274 | /* |
2275 | * print irq inversion bug: |
2276 | */ |
2277 | static int |
2278 | print_irq_inversion_bug(struct task_struct *curr, |
2279 | struct lock_list *root, struct lock_list *other, |
2280 | struct held_lock *this, int forwards, |
2281 | const char *irqclass) |
2282 | { |
2283 | struct lock_list *entry = other; |
2284 | struct lock_list *middle = NULL; |
2285 | int depth; |
2286 | |
2287 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
2288 | return 0; |
2289 | |
2290 | printk("\n"); |
2291 | printk("=========================================================\n"); |
2292 | printk("[ INFO: possible irq lock inversion dependency detected ]\n"); |
2293 | print_kernel_ident(); |
2294 | printk("---------------------------------------------------------\n"); |
2295 | printk("%s/%d just changed the state of lock:\n", |
2296 | curr->comm, task_pid_nr(curr)); |
2297 | print_lock(this); |
2298 | if (forwards) |
2299 | printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass); |
2300 | else |
2301 | printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); |
2302 | print_lock_name(other->class); |
2303 | printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); |
2304 | |
2305 | printk("\nother info that might help us debug this:\n"); |
2306 | |
2307 | /* Find a middle lock (if one exists) */ |
2308 | depth = get_lock_depth(other); |
2309 | do { |
2310 | if (depth == 0 && (entry != root)) { |
2311 | printk("lockdep:%s bad path found in chain graph\n", __func__); |
2312 | break; |
2313 | } |
2314 | middle = entry; |
2315 | entry = get_lock_parent(entry); |
2316 | depth--; |
2317 | } while (entry && entry != root && (depth >= 0)); |
2318 | if (forwards) |
2319 | print_irq_lock_scenario(root, other, |
2320 | middle ? middle->class : root->class, other->class); |
2321 | else |
2322 | print_irq_lock_scenario(other, root, |
2323 | middle ? middle->class : other->class, root->class); |
2324 | |
2325 | lockdep_print_held_locks(curr); |
2326 | |
2327 | printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); |
2328 | if (!save_trace(&root->trace)) |
2329 | return 0; |
2330 | print_shortest_lock_dependencies(other, root); |
2331 | |
2332 | printk("\nstack backtrace:\n"); |
2333 | dump_stack(); |
2334 | |
2335 | return 0; |
2336 | } |
2337 | |
2338 | /* |
2339 | * Prove that in the forwards-direction subgraph starting at <this> |
2340 | * there is no lock matching <mask>: |
2341 | */ |
2342 | static int |
2343 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, |
2344 | enum lock_usage_bit bit, const char *irqclass) |
2345 | { |
2346 | int ret; |
2347 | struct lock_list root; |
2348 | struct lock_list *uninitialized_var(target_entry); |
2349 | |
2350 | root.parent = NULL; |
2351 | root.class = hlock_class(this); |
2352 | ret = find_usage_forwards(&root, bit, &target_entry); |
2353 | if (ret < 0) |
2354 | return print_bfs_bug(ret); |
2355 | if (ret == 1) |
2356 | return ret; |
2357 | |
2358 | return print_irq_inversion_bug(curr, &root, target_entry, |
2359 | this, 1, irqclass); |
2360 | } |
2361 | |
2362 | /* |
2363 | * Prove that in the backwards-direction subgraph starting at <this> |
2364 | * there is no lock matching <mask>: |
2365 | */ |
2366 | static int |
2367 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, |
2368 | enum lock_usage_bit bit, const char *irqclass) |
2369 | { |
2370 | int ret; |
2371 | struct lock_list root; |
2372 | struct lock_list *uninitialized_var(target_entry); |
2373 | |
2374 | root.parent = NULL; |
2375 | root.class = hlock_class(this); |
2376 | ret = find_usage_backwards(&root, bit, &target_entry); |
2377 | if (ret < 0) |
2378 | return print_bfs_bug(ret); |
2379 | if (ret == 1) |
2380 | return ret; |
2381 | |
2382 | return print_irq_inversion_bug(curr, &root, target_entry, |
2383 | this, 0, irqclass); |
2384 | } |
2385 | |
2386 | void print_irqtrace_events(struct task_struct *curr) |
2387 | { |
2388 | printk("irq event stamp: %u\n", curr->irq_events); |
2389 | printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event); |
2390 | print_ip_sym(curr->hardirq_enable_ip); |
2391 | printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event); |
2392 | print_ip_sym(curr->hardirq_disable_ip); |
2393 | printk("softirqs last enabled at (%u): ", curr->softirq_enable_event); |
2394 | print_ip_sym(curr->softirq_enable_ip); |
2395 | printk("softirqs last disabled at (%u): ", curr->softirq_disable_event); |
2396 | print_ip_sym(curr->softirq_disable_ip); |
2397 | } |
2398 | |
2399 | static int HARDIRQ_verbose(struct lock_class *class) |
2400 | { |
2401 | #if HARDIRQ_VERBOSE |
2402 | return class_filter(class); |
2403 | #endif |
2404 | return 0; |
2405 | } |
2406 | |
2407 | static int SOFTIRQ_verbose(struct lock_class *class) |
2408 | { |
2409 | #if SOFTIRQ_VERBOSE |
2410 | return class_filter(class); |
2411 | #endif |
2412 | return 0; |
2413 | } |
2414 | |
2415 | static int RECLAIM_FS_verbose(struct lock_class *class) |
2416 | { |
2417 | #if RECLAIM_VERBOSE |
2418 | return class_filter(class); |
2419 | #endif |
2420 | return 0; |
2421 | } |
2422 | |
2423 | #define STRICT_READ_CHECKS 1 |
2424 | |
2425 | static int (*state_verbose_f[])(struct lock_class *class) = { |
2426 | #define LOCKDEP_STATE(__STATE) \ |
2427 | __STATE##_verbose, |
2428 | #include "lockdep_states.h" |
2429 | #undef LOCKDEP_STATE |
2430 | }; |
2431 | |
2432 | static inline int state_verbose(enum lock_usage_bit bit, |
2433 | struct lock_class *class) |
2434 | { |
2435 | return state_verbose_f[bit >> 2](class); |
2436 | } |
2437 | |
2438 | typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, |
2439 | enum lock_usage_bit bit, const char *name); |
2440 | |
2441 | static int |
2442 | mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
2443 | enum lock_usage_bit new_bit) |
2444 | { |
2445 | int excl_bit = exclusive_bit(new_bit); |
2446 | int read = new_bit & 1; |
2447 | int dir = new_bit & 2; |
2448 | |
2449 | /* |
2450 | * mark USED_IN has to look forwards -- to ensure no dependency |
2451 | * has ENABLED state, which would allow recursion deadlocks. |
2452 | * |
2453 | * mark ENABLED has to look backwards -- to ensure no dependee |
2454 | * has USED_IN state, which, again, would allow recursion deadlocks. |
2455 | */ |
2456 | check_usage_f usage = dir ? |
2457 | check_usage_backwards : check_usage_forwards; |
2458 | |
2459 | /* |
2460 | * Validate that this particular lock does not have conflicting |
2461 | * usage states. |
2462 | */ |
2463 | if (!valid_state(curr, this, new_bit, excl_bit)) |
2464 | return 0; |
2465 | |
2466 | /* |
2467 | * Validate that the lock dependencies don't have conflicting usage |
2468 | * states. |
2469 | */ |
2470 | if ((!read || !dir || STRICT_READ_CHECKS) && |
2471 | !usage(curr, this, excl_bit, state_name(new_bit & ~1))) |
2472 | return 0; |
2473 | |
2474 | /* |
2475 | * Check for read in write conflicts |
2476 | */ |
2477 | if (!read) { |
2478 | if (!valid_state(curr, this, new_bit, excl_bit + 1)) |
2479 | return 0; |
2480 | |
2481 | if (STRICT_READ_CHECKS && |
2482 | !usage(curr, this, excl_bit + 1, |
2483 | state_name(new_bit + 1))) |
2484 | return 0; |
2485 | } |
2486 | |
2487 | if (state_verbose(new_bit, hlock_class(this))) |
2488 | return 2; |
2489 | |
2490 | return 1; |
2491 | } |
2492 | |
2493 | enum mark_type { |
2494 | #define LOCKDEP_STATE(__STATE) __STATE, |
2495 | #include "lockdep_states.h" |
2496 | #undef LOCKDEP_STATE |
2497 | }; |
2498 | |
2499 | /* |
2500 | * Mark all held locks with a usage bit: |
2501 | */ |
2502 | static int |
2503 | mark_held_locks(struct task_struct *curr, enum mark_type mark) |
2504 | { |
2505 | enum lock_usage_bit usage_bit; |
2506 | struct held_lock *hlock; |
2507 | int i; |
2508 | |
2509 | for (i = 0; i < curr->lockdep_depth; i++) { |
2510 | hlock = curr->held_locks + i; |
2511 | |
2512 | usage_bit = 2 + (mark << 2); /* ENABLED */ |
2513 | if (hlock->read) |
2514 | usage_bit += 1; /* READ */ |
2515 | |
2516 | BUG_ON(usage_bit >= LOCK_USAGE_STATES); |
2517 | |
2518 | if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys) |
2519 | continue; |
2520 | |
2521 | if (!mark_lock(curr, hlock, usage_bit)) |
2522 | return 0; |
2523 | } |
2524 | |
2525 | return 1; |
2526 | } |
2527 | |
2528 | /* |
2529 | * Hardirqs will be enabled: |
2530 | */ |
2531 | static void __trace_hardirqs_on_caller(unsigned long ip) |
2532 | { |
2533 | struct task_struct *curr = current; |
2534 | |
2535 | /* we'll do an OFF -> ON transition: */ |
2536 | curr->hardirqs_enabled = 1; |
2537 | |
2538 | /* |
2539 | * We are going to turn hardirqs on, so set the |
2540 | * usage bit for all held locks: |
2541 | */ |
2542 | if (!mark_held_locks(curr, HARDIRQ)) |
2543 | return; |
2544 | /* |
2545 | * If we have softirqs enabled, then set the usage |
2546 | * bit for all held locks. (disabled hardirqs prevented |
2547 | * this bit from being set before) |
2548 | */ |
2549 | if (curr->softirqs_enabled) |
2550 | if (!mark_held_locks(curr, SOFTIRQ)) |
2551 | return; |
2552 | |
2553 | curr->hardirq_enable_ip = ip; |
2554 | curr->hardirq_enable_event = ++curr->irq_events; |
2555 | debug_atomic_inc(hardirqs_on_events); |
2556 | } |
2557 | |
2558 | void trace_hardirqs_on_caller(unsigned long ip) |
2559 | { |
2560 | time_hardirqs_on(CALLER_ADDR0, ip); |
2561 | |
2562 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2563 | return; |
2564 | |
2565 | if (unlikely(current->hardirqs_enabled)) { |
2566 | /* |
2567 | * Neither irq nor preemption are disabled here |
2568 | * so this is racy by nature but losing one hit |
2569 | * in a stat is not a big deal. |
2570 | */ |
2571 | __debug_atomic_inc(redundant_hardirqs_on); |
2572 | return; |
2573 | } |
2574 | |
2575 | /* |
2576 | * We're enabling irqs and according to our state above irqs weren't |
2577 | * already enabled, yet we find the hardware thinks they are in fact |
2578 | * enabled.. someone messed up their IRQ state tracing. |
2579 | */ |
2580 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2581 | return; |
2582 | |
2583 | /* |
2584 | * See the fine text that goes along with this variable definition. |
2585 | */ |
2586 | if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) |
2587 | return; |
2588 | |
2589 | /* |
2590 | * Can't allow enabling interrupts while in an interrupt handler, |
2591 | * that's general bad form and such. Recursion, limited stack etc.. |
2592 | */ |
2593 | if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) |
2594 | return; |
2595 | |
2596 | current->lockdep_recursion = 1; |
2597 | __trace_hardirqs_on_caller(ip); |
2598 | current->lockdep_recursion = 0; |
2599 | } |
2600 | EXPORT_SYMBOL(trace_hardirqs_on_caller); |
2601 | |
2602 | void trace_hardirqs_on(void) |
2603 | { |
2604 | trace_hardirqs_on_caller(CALLER_ADDR0); |
2605 | } |
2606 | EXPORT_SYMBOL(trace_hardirqs_on); |
2607 | |
2608 | /* |
2609 | * Hardirqs were disabled: |
2610 | */ |
2611 | void trace_hardirqs_off_caller(unsigned long ip) |
2612 | { |
2613 | struct task_struct *curr = current; |
2614 | |
2615 | time_hardirqs_off(CALLER_ADDR0, ip); |
2616 | |
2617 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2618 | return; |
2619 | |
2620 | /* |
2621 | * So we're supposed to get called after you mask local IRQs, but for |
2622 | * some reason the hardware doesn't quite think you did a proper job. |
2623 | */ |
2624 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2625 | return; |
2626 | |
2627 | if (curr->hardirqs_enabled) { |
2628 | /* |
2629 | * We have done an ON -> OFF transition: |
2630 | */ |
2631 | curr->hardirqs_enabled = 0; |
2632 | curr->hardirq_disable_ip = ip; |
2633 | curr->hardirq_disable_event = ++curr->irq_events; |
2634 | debug_atomic_inc(hardirqs_off_events); |
2635 | } else |
2636 | debug_atomic_inc(redundant_hardirqs_off); |
2637 | } |
2638 | EXPORT_SYMBOL(trace_hardirqs_off_caller); |
2639 | |
2640 | void trace_hardirqs_off(void) |
2641 | { |
2642 | trace_hardirqs_off_caller(CALLER_ADDR0); |
2643 | } |
2644 | EXPORT_SYMBOL(trace_hardirqs_off); |
2645 | |
2646 | /* |
2647 | * Softirqs will be enabled: |
2648 | */ |
2649 | void trace_softirqs_on(unsigned long ip) |
2650 | { |
2651 | struct task_struct *curr = current; |
2652 | |
2653 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2654 | return; |
2655 | |
2656 | /* |
2657 | * We fancy IRQs being disabled here, see softirq.c, avoids |
2658 | * funny state and nesting things. |
2659 | */ |
2660 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2661 | return; |
2662 | |
2663 | if (curr->softirqs_enabled) { |
2664 | debug_atomic_inc(redundant_softirqs_on); |
2665 | return; |
2666 | } |
2667 | |
2668 | current->lockdep_recursion = 1; |
2669 | /* |
2670 | * We'll do an OFF -> ON transition: |
2671 | */ |
2672 | curr->softirqs_enabled = 1; |
2673 | curr->softirq_enable_ip = ip; |
2674 | curr->softirq_enable_event = ++curr->irq_events; |
2675 | debug_atomic_inc(softirqs_on_events); |
2676 | /* |
2677 | * We are going to turn softirqs on, so set the |
2678 | * usage bit for all held locks, if hardirqs are |
2679 | * enabled too: |
2680 | */ |
2681 | if (curr->hardirqs_enabled) |
2682 | mark_held_locks(curr, SOFTIRQ); |
2683 | current->lockdep_recursion = 0; |
2684 | } |
2685 | |
2686 | /* |
2687 | * Softirqs were disabled: |
2688 | */ |
2689 | void trace_softirqs_off(unsigned long ip) |
2690 | { |
2691 | struct task_struct *curr = current; |
2692 | |
2693 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2694 | return; |
2695 | |
2696 | /* |
2697 | * We fancy IRQs being disabled here, see softirq.c |
2698 | */ |
2699 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2700 | return; |
2701 | |
2702 | if (curr->softirqs_enabled) { |
2703 | /* |
2704 | * We have done an ON -> OFF transition: |
2705 | */ |
2706 | curr->softirqs_enabled = 0; |
2707 | curr->softirq_disable_ip = ip; |
2708 | curr->softirq_disable_event = ++curr->irq_events; |
2709 | debug_atomic_inc(softirqs_off_events); |
2710 | /* |
2711 | * Whoops, we wanted softirqs off, so why aren't they? |
2712 | */ |
2713 | DEBUG_LOCKS_WARN_ON(!softirq_count()); |
2714 | } else |
2715 | debug_atomic_inc(redundant_softirqs_off); |
2716 | } |
2717 | |
2718 | static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags) |
2719 | { |
2720 | struct task_struct *curr = current; |
2721 | |
2722 | if (unlikely(!debug_locks)) |
2723 | return; |
2724 | |
2725 | /* no reclaim without waiting on it */ |
2726 | if (!(gfp_mask & __GFP_WAIT)) |
2727 | return; |
2728 | |
2729 | /* this guy won't enter reclaim */ |
2730 | if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC)) |
2731 | return; |
2732 | |
2733 | /* We're only interested __GFP_FS allocations for now */ |
2734 | if (!(gfp_mask & __GFP_FS)) |
2735 | return; |
2736 | |
2737 | /* |
2738 | * Oi! Can't be having __GFP_FS allocations with IRQs disabled. |
2739 | */ |
2740 | if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))) |
2741 | return; |
2742 | |
2743 | mark_held_locks(curr, RECLAIM_FS); |
2744 | } |
2745 | |
2746 | static void check_flags(unsigned long flags); |
2747 | |
2748 | void lockdep_trace_alloc(gfp_t gfp_mask) |
2749 | { |
2750 | unsigned long flags; |
2751 | |
2752 | if (unlikely(current->lockdep_recursion)) |
2753 | return; |
2754 | |
2755 | raw_local_irq_save(flags); |
2756 | check_flags(flags); |
2757 | current->lockdep_recursion = 1; |
2758 | __lockdep_trace_alloc(gfp_mask, flags); |
2759 | current->lockdep_recursion = 0; |
2760 | raw_local_irq_restore(flags); |
2761 | } |
2762 | |
2763 | static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) |
2764 | { |
2765 | /* |
2766 | * If non-trylock use in a hardirq or softirq context, then |
2767 | * mark the lock as used in these contexts: |
2768 | */ |
2769 | if (!hlock->trylock) { |
2770 | if (hlock->read) { |
2771 | if (curr->hardirq_context) |
2772 | if (!mark_lock(curr, hlock, |
2773 | LOCK_USED_IN_HARDIRQ_READ)) |
2774 | return 0; |
2775 | if (curr->softirq_context) |
2776 | if (!mark_lock(curr, hlock, |
2777 | LOCK_USED_IN_SOFTIRQ_READ)) |
2778 | return 0; |
2779 | } else { |
2780 | if (curr->hardirq_context) |
2781 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) |
2782 | return 0; |
2783 | if (curr->softirq_context) |
2784 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) |
2785 | return 0; |
2786 | } |
2787 | } |
2788 | if (!hlock->hardirqs_off) { |
2789 | if (hlock->read) { |
2790 | if (!mark_lock(curr, hlock, |
2791 | LOCK_ENABLED_HARDIRQ_READ)) |
2792 | return 0; |
2793 | if (curr->softirqs_enabled) |
2794 | if (!mark_lock(curr, hlock, |
2795 | LOCK_ENABLED_SOFTIRQ_READ)) |
2796 | return 0; |
2797 | } else { |
2798 | if (!mark_lock(curr, hlock, |
2799 | LOCK_ENABLED_HARDIRQ)) |
2800 | return 0; |
2801 | if (curr->softirqs_enabled) |
2802 | if (!mark_lock(curr, hlock, |
2803 | LOCK_ENABLED_SOFTIRQ)) |
2804 | return 0; |
2805 | } |
2806 | } |
2807 | |
2808 | /* |
2809 | * We reuse the irq context infrastructure more broadly as a general |
2810 | * context checking code. This tests GFP_FS recursion (a lock taken |
2811 | * during reclaim for a GFP_FS allocation is held over a GFP_FS |
2812 | * allocation). |
2813 | */ |
2814 | if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) { |
2815 | if (hlock->read) { |
2816 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ)) |
2817 | return 0; |
2818 | } else { |
2819 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS)) |
2820 | return 0; |
2821 | } |
2822 | } |
2823 | |
2824 | return 1; |
2825 | } |
2826 | |
2827 | static int separate_irq_context(struct task_struct *curr, |
2828 | struct held_lock *hlock) |
2829 | { |
2830 | unsigned int depth = curr->lockdep_depth; |
2831 | |
2832 | /* |
2833 | * Keep track of points where we cross into an interrupt context: |
2834 | */ |
2835 | hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) + |
2836 | curr->softirq_context; |
2837 | if (depth) { |
2838 | struct held_lock *prev_hlock; |
2839 | |
2840 | prev_hlock = curr->held_locks + depth-1; |
2841 | /* |
2842 | * If we cross into another context, reset the |
2843 | * hash key (this also prevents the checking and the |
2844 | * adding of the dependency to 'prev'): |
2845 | */ |
2846 | if (prev_hlock->irq_context != hlock->irq_context) |
2847 | return 1; |
2848 | } |
2849 | return 0; |
2850 | } |
2851 | |
2852 | #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ |
2853 | |
2854 | static inline |
2855 | int mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
2856 | enum lock_usage_bit new_bit) |
2857 | { |
2858 | WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */ |
2859 | return 1; |
2860 | } |
2861 | |
2862 | static inline int mark_irqflags(struct task_struct *curr, |
2863 | struct held_lock *hlock) |
2864 | { |
2865 | return 1; |
2866 | } |
2867 | |
2868 | static inline int separate_irq_context(struct task_struct *curr, |
2869 | struct held_lock *hlock) |
2870 | { |
2871 | return 0; |
2872 | } |
2873 | |
2874 | void lockdep_trace_alloc(gfp_t gfp_mask) |
2875 | { |
2876 | } |
2877 | |
2878 | #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ |
2879 | |
2880 | /* |
2881 | * Mark a lock with a usage bit, and validate the state transition: |
2882 | */ |
2883 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
2884 | enum lock_usage_bit new_bit) |
2885 | { |
2886 | unsigned int new_mask = 1 << new_bit, ret = 1; |
2887 | |
2888 | /* |
2889 | * If already set then do not dirty the cacheline, |
2890 | * nor do any checks: |
2891 | */ |
2892 | if (likely(hlock_class(this)->usage_mask & new_mask)) |
2893 | return 1; |
2894 | |
2895 | if (!graph_lock()) |
2896 | return 0; |
2897 | /* |
2898 | * Make sure we didn't race: |
2899 | */ |
2900 | if (unlikely(hlock_class(this)->usage_mask & new_mask)) { |
2901 | graph_unlock(); |
2902 | return 1; |
2903 | } |
2904 | |
2905 | hlock_class(this)->usage_mask |= new_mask; |
2906 | |
2907 | if (!save_trace(hlock_class(this)->usage_traces + new_bit)) |
2908 | return 0; |
2909 | |
2910 | switch (new_bit) { |
2911 | #define LOCKDEP_STATE(__STATE) \ |
2912 | case LOCK_USED_IN_##__STATE: \ |
2913 | case LOCK_USED_IN_##__STATE##_READ: \ |
2914 | case LOCK_ENABLED_##__STATE: \ |
2915 | case LOCK_ENABLED_##__STATE##_READ: |
2916 | #include "lockdep_states.h" |
2917 | #undef LOCKDEP_STATE |
2918 | ret = mark_lock_irq(curr, this, new_bit); |
2919 | if (!ret) |
2920 | return 0; |
2921 | break; |
2922 | case LOCK_USED: |
2923 | debug_atomic_dec(nr_unused_locks); |
2924 | break; |
2925 | default: |
2926 | if (!debug_locks_off_graph_unlock()) |
2927 | return 0; |
2928 | WARN_ON(1); |
2929 | return 0; |
2930 | } |
2931 | |
2932 | graph_unlock(); |
2933 | |
2934 | /* |
2935 | * We must printk outside of the graph_lock: |
2936 | */ |
2937 | if (ret == 2) { |
2938 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); |
2939 | print_lock(this); |
2940 | print_irqtrace_events(curr); |
2941 | dump_stack(); |
2942 | } |
2943 | |
2944 | return ret; |
2945 | } |
2946 | |
2947 | /* |
2948 | * Initialize a lock instance's lock-class mapping info: |
2949 | */ |
2950 | void lockdep_init_map(struct lockdep_map *lock, const char *name, |
2951 | struct lock_class_key *key, int subclass) |
2952 | { |
2953 | int i; |
2954 | |
2955 | kmemcheck_mark_initialized(lock, sizeof(*lock)); |
2956 | |
2957 | for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) |
2958 | lock->class_cache[i] = NULL; |
2959 | |
2960 | #ifdef CONFIG_LOCK_STAT |
2961 | lock->cpu = raw_smp_processor_id(); |
2962 | #endif |
2963 | |
2964 | /* |
2965 | * Can't be having no nameless bastards around this place! |
2966 | */ |
2967 | if (DEBUG_LOCKS_WARN_ON(!name)) { |
2968 | lock->name = "NULL"; |
2969 | return; |
2970 | } |
2971 | |
2972 | lock->name = name; |
2973 | |
2974 | /* |
2975 | * No key, no joy, we need to hash something. |
2976 | */ |
2977 | if (DEBUG_LOCKS_WARN_ON(!key)) |
2978 | return; |
2979 | /* |
2980 | * Sanity check, the lock-class key must be persistent: |
2981 | */ |
2982 | if (!static_obj(key)) { |
2983 | printk("BUG: key %p not in .data!\n", key); |
2984 | /* |
2985 | * What it says above ^^^^^, I suggest you read it. |
2986 | */ |
2987 | DEBUG_LOCKS_WARN_ON(1); |
2988 | return; |
2989 | } |
2990 | lock->key = key; |
2991 | |
2992 | if (unlikely(!debug_locks)) |
2993 | return; |
2994 | |
2995 | if (subclass) |
2996 | register_lock_class(lock, subclass, 1); |
2997 | } |
2998 | EXPORT_SYMBOL_GPL(lockdep_init_map); |
2999 | |
3000 | struct lock_class_key __lockdep_no_validate__; |
3001 | EXPORT_SYMBOL_GPL(__lockdep_no_validate__); |
3002 | |
3003 | static int |
3004 | print_lock_nested_lock_not_held(struct task_struct *curr, |
3005 | struct held_lock *hlock, |
3006 | unsigned long ip) |
3007 | { |
3008 | if (!debug_locks_off()) |
3009 | return 0; |
3010 | if (debug_locks_silent) |
3011 | return 0; |
3012 | |
3013 | printk("\n"); |
3014 | printk("==================================\n"); |
3015 | printk("[ BUG: Nested lock was not taken ]\n"); |
3016 | print_kernel_ident(); |
3017 | printk("----------------------------------\n"); |
3018 | |
3019 | printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr)); |
3020 | print_lock(hlock); |
3021 | |
3022 | printk("\nbut this task is not holding:\n"); |
3023 | printk("%s\n", hlock->nest_lock->name); |
3024 | |
3025 | printk("\nstack backtrace:\n"); |
3026 | dump_stack(); |
3027 | |
3028 | printk("\nother info that might help us debug this:\n"); |
3029 | lockdep_print_held_locks(curr); |
3030 | |
3031 | printk("\nstack backtrace:\n"); |
3032 | dump_stack(); |
3033 | |
3034 | return 0; |
3035 | } |
3036 | |
3037 | static int __lock_is_held(struct lockdep_map *lock); |
3038 | |
3039 | /* |
3040 | * This gets called for every mutex_lock*()/spin_lock*() operation. |
3041 | * We maintain the dependency maps and validate the locking attempt: |
3042 | */ |
3043 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
3044 | int trylock, int read, int check, int hardirqs_off, |
3045 | struct lockdep_map *nest_lock, unsigned long ip, |
3046 | int references) |
3047 | { |
3048 | struct task_struct *curr = current; |
3049 | struct lock_class *class = NULL; |
3050 | struct held_lock *hlock; |
3051 | unsigned int depth, id; |
3052 | int chain_head = 0; |
3053 | int class_idx; |
3054 | u64 chain_key; |
3055 | |
3056 | if (!prove_locking) |
3057 | check = 1; |
3058 | |
3059 | if (unlikely(!debug_locks)) |
3060 | return 0; |
3061 | |
3062 | /* |
3063 | * Lockdep should run with IRQs disabled, otherwise we could |
3064 | * get an interrupt which would want to take locks, which would |
3065 | * end up in lockdep and have you got a head-ache already? |
3066 | */ |
3067 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
3068 | return 0; |
3069 | |
3070 | if (lock->key == &__lockdep_no_validate__) |
3071 | check = 1; |
3072 | |
3073 | if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
3074 | class = lock->class_cache[subclass]; |
3075 | /* |
3076 | * Not cached? |
3077 | */ |
3078 | if (unlikely(!class)) { |
3079 | class = register_lock_class(lock, subclass, 0); |
3080 | if (!class) |
3081 | return 0; |
3082 | } |
3083 | atomic_inc((atomic_t *)&class->ops); |
3084 | if (very_verbose(class)) { |
3085 | printk("\nacquire class [%p] %s", class->key, class->name); |
3086 | if (class->name_version > 1) |
3087 | printk("#%d", class->name_version); |
3088 | printk("\n"); |
3089 | dump_stack(); |
3090 | } |
3091 | |
3092 | /* |
3093 | * Add the lock to the list of currently held locks. |
3094 | * (we dont increase the depth just yet, up until the |
3095 | * dependency checks are done) |
3096 | */ |
3097 | depth = curr->lockdep_depth; |
3098 | /* |
3099 | * Ran out of static storage for our per-task lock stack again have we? |
3100 | */ |
3101 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) |
3102 | return 0; |
3103 | |
3104 | class_idx = class - lock_classes + 1; |
3105 | |
3106 | if (depth) { |
3107 | hlock = curr->held_locks + depth - 1; |
3108 | if (hlock->class_idx == class_idx && nest_lock) { |
3109 | if (hlock->references) |
3110 | hlock->references++; |
3111 | else |
3112 | hlock->references = 2; |
3113 | |
3114 | return 1; |
3115 | } |
3116 | } |
3117 | |
3118 | hlock = curr->held_locks + depth; |
3119 | /* |
3120 | * Plain impossible, we just registered it and checked it weren't no |
3121 | * NULL like.. I bet this mushroom I ate was good! |
3122 | */ |
3123 | if (DEBUG_LOCKS_WARN_ON(!class)) |
3124 | return 0; |
3125 | hlock->class_idx = class_idx; |
3126 | hlock->acquire_ip = ip; |
3127 | hlock->instance = lock; |
3128 | hlock->nest_lock = nest_lock; |
3129 | hlock->trylock = trylock; |
3130 | hlock->read = read; |
3131 | hlock->check = check; |
3132 | hlock->hardirqs_off = !!hardirqs_off; |
3133 | hlock->references = references; |
3134 | #ifdef CONFIG_LOCK_STAT |
3135 | hlock->waittime_stamp = 0; |
3136 | hlock->holdtime_stamp = lockstat_clock(); |
3137 | #endif |
3138 | |
3139 | if (check == 2 && !mark_irqflags(curr, hlock)) |
3140 | return 0; |
3141 | |
3142 | /* mark it as used: */ |
3143 | if (!mark_lock(curr, hlock, LOCK_USED)) |
3144 | return 0; |
3145 | |
3146 | /* |
3147 | * Calculate the chain hash: it's the combined hash of all the |
3148 | * lock keys along the dependency chain. We save the hash value |
3149 | * at every step so that we can get the current hash easily |
3150 | * after unlock. The chain hash is then used to cache dependency |
3151 | * results. |
3152 | * |
3153 | * The 'key ID' is what is the most compact key value to drive |
3154 | * the hash, not class->key. |
3155 | */ |
3156 | id = class - lock_classes; |
3157 | /* |
3158 | * Whoops, we did it again.. ran straight out of our static allocation. |
3159 | */ |
3160 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) |
3161 | return 0; |
3162 | |
3163 | chain_key = curr->curr_chain_key; |
3164 | if (!depth) { |
3165 | /* |
3166 | * How can we have a chain hash when we ain't got no keys?! |
3167 | */ |
3168 | if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) |
3169 | return 0; |
3170 | chain_head = 1; |
3171 | } |
3172 | |
3173 | hlock->prev_chain_key = chain_key; |
3174 | if (separate_irq_context(curr, hlock)) { |
3175 | chain_key = 0; |
3176 | chain_head = 1; |
3177 | } |
3178 | chain_key = iterate_chain_key(chain_key, id); |
3179 | |
3180 | if (nest_lock && !__lock_is_held(nest_lock)) |
3181 | return print_lock_nested_lock_not_held(curr, hlock, ip); |
3182 | |
3183 | if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) |
3184 | return 0; |
3185 | |
3186 | curr->curr_chain_key = chain_key; |
3187 | curr->lockdep_depth++; |
3188 | check_chain_key(curr); |
3189 | #ifdef CONFIG_DEBUG_LOCKDEP |
3190 | if (unlikely(!debug_locks)) |
3191 | return 0; |
3192 | #endif |
3193 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { |
3194 | debug_locks_off(); |
3195 | print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!"); |
3196 | printk(KERN_DEBUG "depth: %i max: %lu!\n", |
3197 | curr->lockdep_depth, MAX_LOCK_DEPTH); |
3198 | |
3199 | lockdep_print_held_locks(current); |
3200 | debug_show_all_locks(); |
3201 | dump_stack(); |
3202 | |
3203 | return 0; |
3204 | } |
3205 | |
3206 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) |
3207 | max_lockdep_depth = curr->lockdep_depth; |
3208 | |
3209 | return 1; |
3210 | } |
3211 | |
3212 | static int |
3213 | print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock, |
3214 | unsigned long ip) |
3215 | { |
3216 | if (!debug_locks_off()) |
3217 | return 0; |
3218 | if (debug_locks_silent) |
3219 | return 0; |
3220 | |
3221 | printk("\n"); |
3222 | printk("=====================================\n"); |
3223 | printk("[ BUG: bad unlock balance detected! ]\n"); |
3224 | print_kernel_ident(); |
3225 | printk("-------------------------------------\n"); |
3226 | printk("%s/%d is trying to release lock (", |
3227 | curr->comm, task_pid_nr(curr)); |
3228 | print_lockdep_cache(lock); |
3229 | printk(") at:\n"); |
3230 | print_ip_sym(ip); |
3231 | printk("but there are no more locks to release!\n"); |
3232 | printk("\nother info that might help us debug this:\n"); |
3233 | lockdep_print_held_locks(curr); |
3234 | |
3235 | printk("\nstack backtrace:\n"); |
3236 | dump_stack(); |
3237 | |
3238 | return 0; |
3239 | } |
3240 | |
3241 | /* |
3242 | * Common debugging checks for both nested and non-nested unlock: |
3243 | */ |
3244 | static int check_unlock(struct task_struct *curr, struct lockdep_map *lock, |
3245 | unsigned long ip) |
3246 | { |
3247 | if (unlikely(!debug_locks)) |
3248 | return 0; |
3249 | /* |
3250 | * Lockdep should run with IRQs disabled, recursion, head-ache, etc.. |
3251 | */ |
3252 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
3253 | return 0; |
3254 | |
3255 | if (curr->lockdep_depth <= 0) |
3256 | return print_unlock_imbalance_bug(curr, lock, ip); |
3257 | |
3258 | return 1; |
3259 | } |
3260 | |
3261 | static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) |
3262 | { |
3263 | if (hlock->instance == lock) |
3264 | return 1; |
3265 | |
3266 | if (hlock->references) { |
3267 | struct lock_class *class = lock->class_cache[0]; |
3268 | |
3269 | if (!class) |
3270 | class = look_up_lock_class(lock, 0); |
3271 | |
3272 | /* |
3273 | * If look_up_lock_class() failed to find a class, we're trying |
3274 | * to test if we hold a lock that has never yet been acquired. |
3275 | * Clearly if the lock hasn't been acquired _ever_, we're not |
3276 | * holding it either, so report failure. |
3277 | */ |
3278 | if (!class) |
3279 | return 0; |
3280 | |
3281 | /* |
3282 | * References, but not a lock we're actually ref-counting? |
3283 | * State got messed up, follow the sites that change ->references |
3284 | * and try to make sense of it. |
3285 | */ |
3286 | if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) |
3287 | return 0; |
3288 | |
3289 | if (hlock->class_idx == class - lock_classes + 1) |
3290 | return 1; |
3291 | } |
3292 | |
3293 | return 0; |
3294 | } |
3295 | |
3296 | static int |
3297 | __lock_set_class(struct lockdep_map *lock, const char *name, |
3298 | struct lock_class_key *key, unsigned int subclass, |
3299 | unsigned long ip) |
3300 | { |
3301 | struct task_struct *curr = current; |
3302 | struct held_lock *hlock, *prev_hlock; |
3303 | struct lock_class *class; |
3304 | unsigned int depth; |
3305 | int i; |
3306 | |
3307 | depth = curr->lockdep_depth; |
3308 | /* |
3309 | * This function is about (re)setting the class of a held lock, |
3310 | * yet we're not actually holding any locks. Naughty user! |
3311 | */ |
3312 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3313 | return 0; |
3314 | |
3315 | prev_hlock = NULL; |
3316 | for (i = depth-1; i >= 0; i--) { |
3317 | hlock = curr->held_locks + i; |
3318 | /* |
3319 | * We must not cross into another context: |
3320 | */ |
3321 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3322 | break; |
3323 | if (match_held_lock(hlock, lock)) |
3324 | goto found_it; |
3325 | prev_hlock = hlock; |
3326 | } |
3327 | return print_unlock_imbalance_bug(curr, lock, ip); |
3328 | |
3329 | found_it: |
3330 | lockdep_init_map(lock, name, key, 0); |
3331 | class = register_lock_class(lock, subclass, 0); |
3332 | hlock->class_idx = class - lock_classes + 1; |
3333 | |
3334 | curr->lockdep_depth = i; |
3335 | curr->curr_chain_key = hlock->prev_chain_key; |
3336 | |
3337 | for (; i < depth; i++) { |
3338 | hlock = curr->held_locks + i; |
3339 | if (!__lock_acquire(hlock->instance, |
3340 | hlock_class(hlock)->subclass, hlock->trylock, |
3341 | hlock->read, hlock->check, hlock->hardirqs_off, |
3342 | hlock->nest_lock, hlock->acquire_ip, |
3343 | hlock->references)) |
3344 | return 0; |
3345 | } |
3346 | |
3347 | /* |
3348 | * I took it apart and put it back together again, except now I have |
3349 | * these 'spare' parts.. where shall I put them. |
3350 | */ |
3351 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) |
3352 | return 0; |
3353 | return 1; |
3354 | } |
3355 | |
3356 | /* |
3357 | * Remove the lock to the list of currently held locks in a |
3358 | * potentially non-nested (out of order) manner. This is a |
3359 | * relatively rare operation, as all the unlock APIs default |
3360 | * to nested mode (which uses lock_release()): |
3361 | */ |
3362 | static int |
3363 | lock_release_non_nested(struct task_struct *curr, |
3364 | struct lockdep_map *lock, unsigned long ip) |
3365 | { |
3366 | struct held_lock *hlock, *prev_hlock; |
3367 | unsigned int depth; |
3368 | int i; |
3369 | |
3370 | /* |
3371 | * Check whether the lock exists in the current stack |
3372 | * of held locks: |
3373 | */ |
3374 | depth = curr->lockdep_depth; |
3375 | /* |
3376 | * So we're all set to release this lock.. wait what lock? We don't |
3377 | * own any locks, you've been drinking again? |
3378 | */ |
3379 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3380 | return 0; |
3381 | |
3382 | prev_hlock = NULL; |
3383 | for (i = depth-1; i >= 0; i--) { |
3384 | hlock = curr->held_locks + i; |
3385 | /* |
3386 | * We must not cross into another context: |
3387 | */ |
3388 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3389 | break; |
3390 | if (match_held_lock(hlock, lock)) |
3391 | goto found_it; |
3392 | prev_hlock = hlock; |
3393 | } |
3394 | return print_unlock_imbalance_bug(curr, lock, ip); |
3395 | |
3396 | found_it: |
3397 | if (hlock->instance == lock) |
3398 | lock_release_holdtime(hlock); |
3399 | |
3400 | if (hlock->references) { |
3401 | hlock->references--; |
3402 | if (hlock->references) { |
3403 | /* |
3404 | * We had, and after removing one, still have |
3405 | * references, the current lock stack is still |
3406 | * valid. We're done! |
3407 | */ |
3408 | return 1; |
3409 | } |
3410 | } |
3411 | |
3412 | /* |
3413 | * We have the right lock to unlock, 'hlock' points to it. |
3414 | * Now we remove it from the stack, and add back the other |
3415 | * entries (if any), recalculating the hash along the way: |
3416 | */ |
3417 | |
3418 | curr->lockdep_depth = i; |
3419 | curr->curr_chain_key = hlock->prev_chain_key; |
3420 | |
3421 | for (i++; i < depth; i++) { |
3422 | hlock = curr->held_locks + i; |
3423 | if (!__lock_acquire(hlock->instance, |
3424 | hlock_class(hlock)->subclass, hlock->trylock, |
3425 | hlock->read, hlock->check, hlock->hardirqs_off, |
3426 | hlock->nest_lock, hlock->acquire_ip, |
3427 | hlock->references)) |
3428 | return 0; |
3429 | } |
3430 | |
3431 | /* |
3432 | * We had N bottles of beer on the wall, we drank one, but now |
3433 | * there's not N-1 bottles of beer left on the wall... |
3434 | */ |
3435 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) |
3436 | return 0; |
3437 | return 1; |
3438 | } |
3439 | |
3440 | /* |
3441 | * Remove the lock to the list of currently held locks - this gets |
3442 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
3443 | * mutex_lock_interruptible()). This is done for unlocks that nest |
3444 | * perfectly. (i.e. the current top of the lock-stack is unlocked) |
3445 | */ |
3446 | static int lock_release_nested(struct task_struct *curr, |
3447 | struct lockdep_map *lock, unsigned long ip) |
3448 | { |
3449 | struct held_lock *hlock; |
3450 | unsigned int depth; |
3451 | |
3452 | /* |
3453 | * Pop off the top of the lock stack: |
3454 | */ |
3455 | depth = curr->lockdep_depth - 1; |
3456 | hlock = curr->held_locks + depth; |
3457 | |
3458 | /* |
3459 | * Is the unlock non-nested: |
3460 | */ |
3461 | if (hlock->instance != lock || hlock->references) |
3462 | return lock_release_non_nested(curr, lock, ip); |
3463 | curr->lockdep_depth--; |
3464 | |
3465 | /* |
3466 | * No more locks, but somehow we've got hash left over, who left it? |
3467 | */ |
3468 | if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0))) |
3469 | return 0; |
3470 | |
3471 | curr->curr_chain_key = hlock->prev_chain_key; |
3472 | |
3473 | lock_release_holdtime(hlock); |
3474 | |
3475 | #ifdef CONFIG_DEBUG_LOCKDEP |
3476 | hlock->prev_chain_key = 0; |
3477 | hlock->class_idx = 0; |
3478 | hlock->acquire_ip = 0; |
3479 | hlock->irq_context = 0; |
3480 | #endif |
3481 | return 1; |
3482 | } |
3483 | |
3484 | /* |
3485 | * Remove the lock to the list of currently held locks - this gets |
3486 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
3487 | * mutex_lock_interruptible()). This is done for unlocks that nest |
3488 | * perfectly. (i.e. the current top of the lock-stack is unlocked) |
3489 | */ |
3490 | static void |
3491 | __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) |
3492 | { |
3493 | struct task_struct *curr = current; |
3494 | |
3495 | if (!check_unlock(curr, lock, ip)) |
3496 | return; |
3497 | |
3498 | if (nested) { |
3499 | if (!lock_release_nested(curr, lock, ip)) |
3500 | return; |
3501 | } else { |
3502 | if (!lock_release_non_nested(curr, lock, ip)) |
3503 | return; |
3504 | } |
3505 | |
3506 | check_chain_key(curr); |
3507 | } |
3508 | |
3509 | static int __lock_is_held(struct lockdep_map *lock) |
3510 | { |
3511 | struct task_struct *curr = current; |
3512 | int i; |
3513 | |
3514 | for (i = 0; i < curr->lockdep_depth; i++) { |
3515 | struct held_lock *hlock = curr->held_locks + i; |
3516 | |
3517 | if (match_held_lock(hlock, lock)) |
3518 | return 1; |
3519 | } |
3520 | |
3521 | return 0; |
3522 | } |
3523 | |
3524 | /* |
3525 | * Check whether we follow the irq-flags state precisely: |
3526 | */ |
3527 | static void check_flags(unsigned long flags) |
3528 | { |
3529 | #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \ |
3530 | defined(CONFIG_TRACE_IRQFLAGS) |
3531 | if (!debug_locks) |
3532 | return; |
3533 | |
3534 | if (irqs_disabled_flags(flags)) { |
3535 | if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { |
3536 | printk("possible reason: unannotated irqs-off.\n"); |
3537 | } |
3538 | } else { |
3539 | if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { |
3540 | printk("possible reason: unannotated irqs-on.\n"); |
3541 | } |
3542 | } |
3543 | |
3544 | /* |
3545 | * We dont accurately track softirq state in e.g. |
3546 | * hardirq contexts (such as on 4KSTACKS), so only |
3547 | * check if not in hardirq contexts: |
3548 | */ |
3549 | if (!hardirq_count()) { |
3550 | if (softirq_count()) { |
3551 | /* like the above, but with softirqs */ |
3552 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); |
3553 | } else { |
3554 | /* lick the above, does it taste good? */ |
3555 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); |
3556 | } |
3557 | } |
3558 | |
3559 | if (!debug_locks) |
3560 | print_irqtrace_events(current); |
3561 | #endif |
3562 | } |
3563 | |
3564 | void lock_set_class(struct lockdep_map *lock, const char *name, |
3565 | struct lock_class_key *key, unsigned int subclass, |
3566 | unsigned long ip) |
3567 | { |
3568 | unsigned long flags; |
3569 | |
3570 | if (unlikely(current->lockdep_recursion)) |
3571 | return; |
3572 | |
3573 | raw_local_irq_save(flags); |
3574 | current->lockdep_recursion = 1; |
3575 | check_flags(flags); |
3576 | if (__lock_set_class(lock, name, key, subclass, ip)) |
3577 | check_chain_key(current); |
3578 | current->lockdep_recursion = 0; |
3579 | raw_local_irq_restore(flags); |
3580 | } |
3581 | EXPORT_SYMBOL_GPL(lock_set_class); |
3582 | |
3583 | /* |
3584 | * We are not always called with irqs disabled - do that here, |
3585 | * and also avoid lockdep recursion: |
3586 | */ |
3587 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
3588 | int trylock, int read, int check, |
3589 | struct lockdep_map *nest_lock, unsigned long ip) |
3590 | { |
3591 | unsigned long flags; |
3592 | |
3593 | if (unlikely(current->lockdep_recursion)) |
3594 | return; |
3595 | |
3596 | raw_local_irq_save(flags); |
3597 | check_flags(flags); |
3598 | |
3599 | current->lockdep_recursion = 1; |
3600 | trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); |
3601 | __lock_acquire(lock, subclass, trylock, read, check, |
3602 | irqs_disabled_flags(flags), nest_lock, ip, 0); |
3603 | current->lockdep_recursion = 0; |
3604 | raw_local_irq_restore(flags); |
3605 | } |
3606 | EXPORT_SYMBOL_GPL(lock_acquire); |
3607 | |
3608 | void lock_release(struct lockdep_map *lock, int nested, |
3609 | unsigned long ip) |
3610 | { |
3611 | unsigned long flags; |
3612 | |
3613 | if (unlikely(current->lockdep_recursion)) |
3614 | return; |
3615 | |
3616 | raw_local_irq_save(flags); |
3617 | check_flags(flags); |
3618 | current->lockdep_recursion = 1; |
3619 | trace_lock_release(lock, ip); |
3620 | __lock_release(lock, nested, ip); |
3621 | current->lockdep_recursion = 0; |
3622 | raw_local_irq_restore(flags); |
3623 | } |
3624 | EXPORT_SYMBOL_GPL(lock_release); |
3625 | |
3626 | int lock_is_held(struct lockdep_map *lock) |
3627 | { |
3628 | unsigned long flags; |
3629 | int ret = 0; |
3630 | |
3631 | if (unlikely(current->lockdep_recursion)) |
3632 | return 1; /* avoid false negative lockdep_assert_held() */ |
3633 | |
3634 | raw_local_irq_save(flags); |
3635 | check_flags(flags); |
3636 | |
3637 | current->lockdep_recursion = 1; |
3638 | ret = __lock_is_held(lock); |
3639 | current->lockdep_recursion = 0; |
3640 | raw_local_irq_restore(flags); |
3641 | |
3642 | return ret; |
3643 | } |
3644 | EXPORT_SYMBOL_GPL(lock_is_held); |
3645 | |
3646 | void lockdep_set_current_reclaim_state(gfp_t gfp_mask) |
3647 | { |
3648 | current->lockdep_reclaim_gfp = gfp_mask; |
3649 | } |
3650 | |
3651 | void lockdep_clear_current_reclaim_state(void) |
3652 | { |
3653 | current->lockdep_reclaim_gfp = 0; |
3654 | } |
3655 | |
3656 | #ifdef CONFIG_LOCK_STAT |
3657 | static int |
3658 | print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, |
3659 | unsigned long ip) |
3660 | { |
3661 | if (!debug_locks_off()) |
3662 | return 0; |
3663 | if (debug_locks_silent) |
3664 | return 0; |
3665 | |
3666 | printk("\n"); |
3667 | printk("=================================\n"); |
3668 | printk("[ BUG: bad contention detected! ]\n"); |
3669 | print_kernel_ident(); |
3670 | printk("---------------------------------\n"); |
3671 | printk("%s/%d is trying to contend lock (", |
3672 | curr->comm, task_pid_nr(curr)); |
3673 | print_lockdep_cache(lock); |
3674 | printk(") at:\n"); |
3675 | print_ip_sym(ip); |
3676 | printk("but there are no locks held!\n"); |
3677 | printk("\nother info that might help us debug this:\n"); |
3678 | lockdep_print_held_locks(curr); |
3679 | |
3680 | printk("\nstack backtrace:\n"); |
3681 | dump_stack(); |
3682 | |
3683 | return 0; |
3684 | } |
3685 | |
3686 | static void |
3687 | __lock_contended(struct lockdep_map *lock, unsigned long ip) |
3688 | { |
3689 | struct task_struct *curr = current; |
3690 | struct held_lock *hlock, *prev_hlock; |
3691 | struct lock_class_stats *stats; |
3692 | unsigned int depth; |
3693 | int i, contention_point, contending_point; |
3694 | |
3695 | depth = curr->lockdep_depth; |
3696 | /* |
3697 | * Whee, we contended on this lock, except it seems we're not |
3698 | * actually trying to acquire anything much at all.. |
3699 | */ |
3700 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3701 | return; |
3702 | |
3703 | prev_hlock = NULL; |
3704 | for (i = depth-1; i >= 0; i--) { |
3705 | hlock = curr->held_locks + i; |
3706 | /* |
3707 | * We must not cross into another context: |
3708 | */ |
3709 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3710 | break; |
3711 | if (match_held_lock(hlock, lock)) |
3712 | goto found_it; |
3713 | prev_hlock = hlock; |
3714 | } |
3715 | print_lock_contention_bug(curr, lock, ip); |
3716 | return; |
3717 | |
3718 | found_it: |
3719 | if (hlock->instance != lock) |
3720 | return; |
3721 | |
3722 | hlock->waittime_stamp = lockstat_clock(); |
3723 | |
3724 | contention_point = lock_point(hlock_class(hlock)->contention_point, ip); |
3725 | contending_point = lock_point(hlock_class(hlock)->contending_point, |
3726 | lock->ip); |
3727 | |
3728 | stats = get_lock_stats(hlock_class(hlock)); |
3729 | if (contention_point < LOCKSTAT_POINTS) |
3730 | stats->contention_point[contention_point]++; |
3731 | if (contending_point < LOCKSTAT_POINTS) |
3732 | stats->contending_point[contending_point]++; |
3733 | if (lock->cpu != smp_processor_id()) |
3734 | stats->bounces[bounce_contended + !!hlock->read]++; |
3735 | put_lock_stats(stats); |
3736 | } |
3737 | |
3738 | static void |
3739 | __lock_acquired(struct lockdep_map *lock, unsigned long ip) |
3740 | { |
3741 | struct task_struct *curr = current; |
3742 | struct held_lock *hlock, *prev_hlock; |
3743 | struct lock_class_stats *stats; |
3744 | unsigned int depth; |
3745 | u64 now, waittime = 0; |
3746 | int i, cpu; |
3747 | |
3748 | depth = curr->lockdep_depth; |
3749 | /* |
3750 | * Yay, we acquired ownership of this lock we didn't try to |
3751 | * acquire, how the heck did that happen? |
3752 | */ |
3753 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3754 | return; |
3755 | |
3756 | prev_hlock = NULL; |
3757 | for (i = depth-1; i >= 0; i--) { |
3758 | hlock = curr->held_locks + i; |
3759 | /* |
3760 | * We must not cross into another context: |
3761 | */ |
3762 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
3763 | break; |
3764 | if (match_held_lock(hlock, lock)) |
3765 | goto found_it; |
3766 | prev_hlock = hlock; |
3767 | } |
3768 | print_lock_contention_bug(curr, lock, _RET_IP_); |
3769 | return; |
3770 | |
3771 | found_it: |
3772 | if (hlock->instance != lock) |
3773 | return; |
3774 | |
3775 | cpu = smp_processor_id(); |
3776 | if (hlock->waittime_stamp) { |
3777 | now = lockstat_clock(); |
3778 | waittime = now - hlock->waittime_stamp; |
3779 | hlock->holdtime_stamp = now; |
3780 | } |
3781 | |
3782 | trace_lock_acquired(lock, ip); |
3783 | |
3784 | stats = get_lock_stats(hlock_class(hlock)); |
3785 | if (waittime) { |
3786 | if (hlock->read) |
3787 | lock_time_inc(&stats->read_waittime, waittime); |
3788 | else |
3789 | lock_time_inc(&stats->write_waittime, waittime); |
3790 | } |
3791 | if (lock->cpu != cpu) |
3792 | stats->bounces[bounce_acquired + !!hlock->read]++; |
3793 | put_lock_stats(stats); |
3794 | |
3795 | lock->cpu = cpu; |
3796 | lock->ip = ip; |
3797 | } |
3798 | |
3799 | void lock_contended(struct lockdep_map *lock, unsigned long ip) |
3800 | { |
3801 | unsigned long flags; |
3802 | |
3803 | if (unlikely(!lock_stat)) |
3804 | return; |
3805 | |
3806 | if (unlikely(current->lockdep_recursion)) |
3807 | return; |
3808 | |
3809 | raw_local_irq_save(flags); |
3810 | check_flags(flags); |
3811 | current->lockdep_recursion = 1; |
3812 | trace_lock_contended(lock, ip); |
3813 | __lock_contended(lock, ip); |
3814 | current->lockdep_recursion = 0; |
3815 | raw_local_irq_restore(flags); |
3816 | } |
3817 | EXPORT_SYMBOL_GPL(lock_contended); |
3818 | |
3819 | void lock_acquired(struct lockdep_map *lock, unsigned long ip) |
3820 | { |
3821 | unsigned long flags; |
3822 | |
3823 | if (unlikely(!lock_stat)) |
3824 | return; |
3825 | |
3826 | if (unlikely(current->lockdep_recursion)) |
3827 | return; |
3828 | |
3829 | raw_local_irq_save(flags); |
3830 | check_flags(flags); |
3831 | current->lockdep_recursion = 1; |
3832 | __lock_acquired(lock, ip); |
3833 | current->lockdep_recursion = 0; |
3834 | raw_local_irq_restore(flags); |
3835 | } |
3836 | EXPORT_SYMBOL_GPL(lock_acquired); |
3837 | #endif |
3838 | |
3839 | /* |
3840 | * Used by the testsuite, sanitize the validator state |
3841 | * after a simulated failure: |
3842 | */ |
3843 | |
3844 | void lockdep_reset(void) |
3845 | { |
3846 | unsigned long flags; |
3847 | int i; |
3848 | |
3849 | raw_local_irq_save(flags); |
3850 | current->curr_chain_key = 0; |
3851 | current->lockdep_depth = 0; |
3852 | current->lockdep_recursion = 0; |
3853 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); |
3854 | nr_hardirq_chains = 0; |
3855 | nr_softirq_chains = 0; |
3856 | nr_process_chains = 0; |
3857 | debug_locks = 1; |
3858 | for (i = 0; i < CHAINHASH_SIZE; i++) |
3859 | INIT_LIST_HEAD(chainhash_table + i); |
3860 | raw_local_irq_restore(flags); |
3861 | } |
3862 | |
3863 | static void zap_class(struct lock_class *class) |
3864 | { |
3865 | int i; |
3866 | |
3867 | /* |
3868 | * Remove all dependencies this lock is |
3869 | * involved in: |
3870 | */ |
3871 | for (i = 0; i < nr_list_entries; i++) { |
3872 | if (list_entries[i].class == class) |
3873 | list_del_rcu(&list_entries[i].entry); |
3874 | } |
3875 | /* |
3876 | * Unhash the class and remove it from the all_lock_classes list: |
3877 | */ |
3878 | list_del_rcu(&class->hash_entry); |
3879 | list_del_rcu(&class->lock_entry); |
3880 | |
3881 | class->key = NULL; |
3882 | } |
3883 | |
3884 | static inline int within(const void *addr, void *start, unsigned long size) |
3885 | { |
3886 | return addr >= start && addr < start + size; |
3887 | } |
3888 | |
3889 | void lockdep_free_key_range(void *start, unsigned long size) |
3890 | { |
3891 | struct lock_class *class, *next; |
3892 | struct list_head *head; |
3893 | unsigned long flags; |
3894 | int i; |
3895 | int locked; |
3896 | |
3897 | raw_local_irq_save(flags); |
3898 | locked = graph_lock(); |
3899 | |
3900 | /* |
3901 | * Unhash all classes that were created by this module: |
3902 | */ |
3903 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
3904 | head = classhash_table + i; |
3905 | if (list_empty(head)) |
3906 | continue; |
3907 | list_for_each_entry_safe(class, next, head, hash_entry) { |
3908 | if (within(class->key, start, size)) |
3909 | zap_class(class); |
3910 | else if (within(class->name, start, size)) |
3911 | zap_class(class); |
3912 | } |
3913 | } |
3914 | |
3915 | if (locked) |
3916 | graph_unlock(); |
3917 | raw_local_irq_restore(flags); |
3918 | } |
3919 | |
3920 | void lockdep_reset_lock(struct lockdep_map *lock) |
3921 | { |
3922 | struct lock_class *class, *next; |
3923 | struct list_head *head; |
3924 | unsigned long flags; |
3925 | int i, j; |
3926 | int locked; |
3927 | |
3928 | raw_local_irq_save(flags); |
3929 | |
3930 | /* |
3931 | * Remove all classes this lock might have: |
3932 | */ |
3933 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { |
3934 | /* |
3935 | * If the class exists we look it up and zap it: |
3936 | */ |
3937 | class = look_up_lock_class(lock, j); |
3938 | if (class) |
3939 | zap_class(class); |
3940 | } |
3941 | /* |
3942 | * Debug check: in the end all mapped classes should |
3943 | * be gone. |
3944 | */ |
3945 | locked = graph_lock(); |
3946 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
3947 | head = classhash_table + i; |
3948 | if (list_empty(head)) |
3949 | continue; |
3950 | list_for_each_entry_safe(class, next, head, hash_entry) { |
3951 | int match = 0; |
3952 | |
3953 | for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) |
3954 | match |= class == lock->class_cache[j]; |
3955 | |
3956 | if (unlikely(match)) { |
3957 | if (debug_locks_off_graph_unlock()) { |
3958 | /* |
3959 | * We all just reset everything, how did it match? |
3960 | */ |
3961 | WARN_ON(1); |
3962 | } |
3963 | goto out_restore; |
3964 | } |
3965 | } |
3966 | } |
3967 | if (locked) |
3968 | graph_unlock(); |
3969 | |
3970 | out_restore: |
3971 | raw_local_irq_restore(flags); |
3972 | } |
3973 | |
3974 | void lockdep_init(void) |
3975 | { |
3976 | int i; |
3977 | |
3978 | /* |
3979 | * Some architectures have their own start_kernel() |
3980 | * code which calls lockdep_init(), while we also |
3981 | * call lockdep_init() from the start_kernel() itself, |
3982 | * and we want to initialize the hashes only once: |
3983 | */ |
3984 | if (lockdep_initialized) |
3985 | return; |
3986 | |
3987 | for (i = 0; i < CLASSHASH_SIZE; i++) |
3988 | INIT_LIST_HEAD(classhash_table + i); |
3989 | |
3990 | for (i = 0; i < CHAINHASH_SIZE; i++) |
3991 | INIT_LIST_HEAD(chainhash_table + i); |
3992 | |
3993 | lockdep_initialized = 1; |
3994 | } |
3995 | |
3996 | void __init lockdep_info(void) |
3997 | { |
3998 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); |
3999 | |
4000 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); |
4001 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); |
4002 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); |
4003 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); |
4004 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); |
4005 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); |
4006 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); |
4007 | |
4008 | printk(" memory used by lock dependency info: %lu kB\n", |
4009 | (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + |
4010 | sizeof(struct list_head) * CLASSHASH_SIZE + |
4011 | sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + |
4012 | sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + |
4013 | sizeof(struct list_head) * CHAINHASH_SIZE |
4014 | #ifdef CONFIG_PROVE_LOCKING |
4015 | + sizeof(struct circular_queue) |
4016 | #endif |
4017 | ) / 1024 |
4018 | ); |
4019 | |
4020 | printk(" per task-struct memory footprint: %lu bytes\n", |
4021 | sizeof(struct held_lock) * MAX_LOCK_DEPTH); |
4022 | |
4023 | #ifdef CONFIG_DEBUG_LOCKDEP |
4024 | if (lockdep_init_error) { |
4025 | printk("WARNING: lockdep init error! lock-%s was acquired" |
4026 | "before lockdep_init\n", lock_init_error); |
4027 | printk("Call stack leading to lockdep invocation was:\n"); |
4028 | print_stack_trace(&lockdep_init_trace, 0); |
4029 | } |
4030 | #endif |
4031 | } |
4032 | |
4033 | static void |
4034 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, |
4035 | const void *mem_to, struct held_lock *hlock) |
4036 | { |
4037 | if (!debug_locks_off()) |
4038 | return; |
4039 | if (debug_locks_silent) |
4040 | return; |
4041 | |
4042 | printk("\n"); |
4043 | printk("=========================\n"); |
4044 | printk("[ BUG: held lock freed! ]\n"); |
4045 | print_kernel_ident(); |
4046 | printk("-------------------------\n"); |
4047 | printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", |
4048 | curr->comm, task_pid_nr(curr), mem_from, mem_to-1); |
4049 | print_lock(hlock); |
4050 | lockdep_print_held_locks(curr); |
4051 | |
4052 | printk("\nstack backtrace:\n"); |
4053 | dump_stack(); |
4054 | } |
4055 | |
4056 | static inline int not_in_range(const void* mem_from, unsigned long mem_len, |
4057 | const void* lock_from, unsigned long lock_len) |
4058 | { |
4059 | return lock_from + lock_len <= mem_from || |
4060 | mem_from + mem_len <= lock_from; |
4061 | } |
4062 | |
4063 | /* |
4064 | * Called when kernel memory is freed (or unmapped), or if a lock |
4065 | * is destroyed or reinitialized - this code checks whether there is |
4066 | * any held lock in the memory range of <from> to <to>: |
4067 | */ |
4068 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) |
4069 | { |
4070 | struct task_struct *curr = current; |
4071 | struct held_lock *hlock; |
4072 | unsigned long flags; |
4073 | int i; |
4074 | |
4075 | if (unlikely(!debug_locks)) |
4076 | return; |
4077 | |
4078 | local_irq_save(flags); |
4079 | for (i = 0; i < curr->lockdep_depth; i++) { |
4080 | hlock = curr->held_locks + i; |
4081 | |
4082 | if (not_in_range(mem_from, mem_len, hlock->instance, |
4083 | sizeof(*hlock->instance))) |
4084 | continue; |
4085 | |
4086 | print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); |
4087 | break; |
4088 | } |
4089 | local_irq_restore(flags); |
4090 | } |
4091 | EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); |
4092 | |
4093 | static void print_held_locks_bug(void) |
4094 | { |
4095 | if (!debug_locks_off()) |
4096 | return; |
4097 | if (debug_locks_silent) |
4098 | return; |
4099 | |
4100 | printk("\n"); |
4101 | printk("=====================================\n"); |
4102 | printk("[ BUG: %s/%d still has locks held! ]\n", |
4103 | current->comm, task_pid_nr(current)); |
4104 | print_kernel_ident(); |
4105 | printk("-------------------------------------\n"); |
4106 | lockdep_print_held_locks(current); |
4107 | printk("\nstack backtrace:\n"); |
4108 | dump_stack(); |
4109 | } |
4110 | |
4111 | void debug_check_no_locks_held(void) |
4112 | { |
4113 | if (unlikely(current->lockdep_depth > 0)) |
4114 | print_held_locks_bug(); |
4115 | } |
4116 | EXPORT_SYMBOL_GPL(debug_check_no_locks_held); |
4117 | |
4118 | void debug_show_all_locks(void) |
4119 | { |
4120 | struct task_struct *g, *p; |
4121 | int count = 10; |
4122 | int unlock = 1; |
4123 | |
4124 | if (unlikely(!debug_locks)) { |
4125 | printk("INFO: lockdep is turned off.\n"); |
4126 | return; |
4127 | } |
4128 | printk("\nShowing all locks held in the system:\n"); |
4129 | |
4130 | /* |
4131 | * Here we try to get the tasklist_lock as hard as possible, |
4132 | * if not successful after 2 seconds we ignore it (but keep |
4133 | * trying). This is to enable a debug printout even if a |
4134 | * tasklist_lock-holding task deadlocks or crashes. |
4135 | */ |
4136 | retry: |
4137 | if (!read_trylock(&tasklist_lock)) { |
4138 | if (count == 10) |
4139 | printk("hm, tasklist_lock locked, retrying... "); |
4140 | if (count) { |
4141 | count--; |
4142 | printk(" #%d", 10-count); |
4143 | mdelay(200); |
4144 | goto retry; |
4145 | } |
4146 | printk(" ignoring it.\n"); |
4147 | unlock = 0; |
4148 | } else { |
4149 | if (count != 10) |
4150 | printk(KERN_CONT " locked it.\n"); |
4151 | } |
4152 | |
4153 | do_each_thread(g, p) { |
4154 | /* |
4155 | * It's not reliable to print a task's held locks |
4156 | * if it's not sleeping (or if it's not the current |
4157 | * task): |
4158 | */ |
4159 | if (p->state == TASK_RUNNING && p != current) |
4160 | continue; |
4161 | if (p->lockdep_depth) |
4162 | lockdep_print_held_locks(p); |
4163 | if (!unlock) |
4164 | if (read_trylock(&tasklist_lock)) |
4165 | unlock = 1; |
4166 | } while_each_thread(g, p); |
4167 | |
4168 | printk("\n"); |
4169 | printk("=============================================\n\n"); |
4170 | |
4171 | if (unlock) |
4172 | read_unlock(&tasklist_lock); |
4173 | } |
4174 | EXPORT_SYMBOL_GPL(debug_show_all_locks); |
4175 | |
4176 | /* |
4177 | * Careful: only use this function if you are sure that |
4178 | * the task cannot run in parallel! |
4179 | */ |
4180 | void debug_show_held_locks(struct task_struct *task) |
4181 | { |
4182 | if (unlikely(!debug_locks)) { |
4183 | printk("INFO: lockdep is turned off.\n"); |
4184 | return; |
4185 | } |
4186 | lockdep_print_held_locks(task); |
4187 | } |
4188 | EXPORT_SYMBOL_GPL(debug_show_held_locks); |
4189 | |
4190 | void lockdep_sys_exit(void) |
4191 | { |
4192 | struct task_struct *curr = current; |
4193 | |
4194 | if (unlikely(curr->lockdep_depth)) { |
4195 | if (!debug_locks_off()) |
4196 | return; |
4197 | printk("\n"); |
4198 | printk("================================================\n"); |
4199 | printk("[ BUG: lock held when returning to user space! ]\n"); |
4200 | print_kernel_ident(); |
4201 | printk("------------------------------------------------\n"); |
4202 | printk("%s/%d is leaving the kernel with locks still held!\n", |
4203 | curr->comm, curr->pid); |
4204 | lockdep_print_held_locks(curr); |
4205 | } |
4206 | } |
4207 | |
4208 | void lockdep_rcu_suspicious(const char *file, const int line, const char *s) |
4209 | { |
4210 | struct task_struct *curr = current; |
4211 | |
4212 | #ifndef CONFIG_PROVE_RCU_REPEATEDLY |
4213 | if (!debug_locks_off()) |
4214 | return; |
4215 | #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */ |
4216 | /* Note: the following can be executed concurrently, so be careful. */ |
4217 | printk("\n"); |
4218 | printk("===============================\n"); |
4219 | printk("[ INFO: suspicious RCU usage. ]\n"); |
4220 | print_kernel_ident(); |
4221 | printk("-------------------------------\n"); |
4222 | printk("%s:%d %s!\n", file, line, s); |
4223 | printk("\nother info that might help us debug this:\n\n"); |
4224 | printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n", |
4225 | !rcu_lockdep_current_cpu_online() |
4226 | ? "RCU used illegally from offline CPU!\n" |
4227 | : rcu_is_cpu_idle() |
4228 | ? "RCU used illegally from idle CPU!\n" |
4229 | : "", |
4230 | rcu_scheduler_active, debug_locks); |
4231 | |
4232 | /* |
4233 | * If a CPU is in the RCU-free window in idle (ie: in the section |
4234 | * between rcu_idle_enter() and rcu_idle_exit(), then RCU |
4235 | * considers that CPU to be in an "extended quiescent state", |
4236 | * which means that RCU will be completely ignoring that CPU. |
4237 | * Therefore, rcu_read_lock() and friends have absolutely no |
4238 | * effect on a CPU running in that state. In other words, even if |
4239 | * such an RCU-idle CPU has called rcu_read_lock(), RCU might well |
4240 | * delete data structures out from under it. RCU really has no |
4241 | * choice here: we need to keep an RCU-free window in idle where |
4242 | * the CPU may possibly enter into low power mode. This way we can |
4243 | * notice an extended quiescent state to other CPUs that started a grace |
4244 | * period. Otherwise we would delay any grace period as long as we run |
4245 | * in the idle task. |
4246 | * |
4247 | * So complain bitterly if someone does call rcu_read_lock(), |
4248 | * rcu_read_lock_bh() and so on from extended quiescent states. |
4249 | */ |
4250 | if (rcu_is_cpu_idle()) |
4251 | printk("RCU used illegally from extended quiescent state!\n"); |
4252 | |
4253 | lockdep_print_held_locks(curr); |
4254 | printk("\nstack backtrace:\n"); |
4255 | dump_stack(); |
4256 | } |
4257 | EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); |
4258 |
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