Commit | Line | Data |
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fbb9ce95 IM |
1 | /* |
2 | * kernel/lockdep.c | |
3 | * | |
4 | * Runtime locking correctness validator | |
5 | * | |
6 | * Started by Ingo Molnar: | |
7 | * | |
8 | * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
9 | * | |
10 | * this code maps all the lock dependencies as they occur in a live kernel | |
11 | * and will warn about the following classes of locking bugs: | |
12 | * | |
13 | * - lock inversion scenarios | |
14 | * - circular lock dependencies | |
15 | * - hardirq/softirq safe/unsafe locking bugs | |
16 | * | |
17 | * Bugs are reported even if the current locking scenario does not cause | |
18 | * any deadlock at this point. | |
19 | * | |
20 | * I.e. if anytime in the past two locks were taken in a different order, | |
21 | * even if it happened for another task, even if those were different | |
22 | * locks (but of the same class as this lock), this code will detect it. | |
23 | * | |
24 | * Thanks to Arjan van de Ven for coming up with the initial idea of | |
25 | * mapping lock dependencies runtime. | |
26 | */ | |
27 | #include <linux/mutex.h> | |
28 | #include <linux/sched.h> | |
29 | #include <linux/delay.h> | |
30 | #include <linux/module.h> | |
31 | #include <linux/proc_fs.h> | |
32 | #include <linux/seq_file.h> | |
33 | #include <linux/spinlock.h> | |
34 | #include <linux/kallsyms.h> | |
35 | #include <linux/interrupt.h> | |
36 | #include <linux/stacktrace.h> | |
37 | #include <linux/debug_locks.h> | |
38 | #include <linux/irqflags.h> | |
39 | ||
40 | #include <asm/sections.h> | |
41 | ||
42 | #include "lockdep_internals.h" | |
43 | ||
44 | /* | |
45 | * hash_lock: protects the lockdep hashes and class/list/hash allocators. | |
46 | * | |
47 | * This is one of the rare exceptions where it's justified | |
48 | * to use a raw spinlock - we really dont want the spinlock | |
49 | * code to recurse back into the lockdep code. | |
50 | */ | |
51 | static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; | |
52 | ||
53 | static int lockdep_initialized; | |
54 | ||
55 | unsigned long nr_list_entries; | |
56 | static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; | |
57 | ||
58 | /* | |
59 | * Allocate a lockdep entry. (assumes hash_lock held, returns | |
60 | * with NULL on failure) | |
61 | */ | |
62 | static struct lock_list *alloc_list_entry(void) | |
63 | { | |
64 | if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { | |
65 | __raw_spin_unlock(&hash_lock); | |
66 | debug_locks_off(); | |
67 | printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n"); | |
68 | printk("turning off the locking correctness validator.\n"); | |
69 | return NULL; | |
70 | } | |
71 | return list_entries + nr_list_entries++; | |
72 | } | |
73 | ||
74 | /* | |
75 | * All data structures here are protected by the global debug_lock. | |
76 | * | |
77 | * Mutex key structs only get allocated, once during bootup, and never | |
78 | * get freed - this significantly simplifies the debugging code. | |
79 | */ | |
80 | unsigned long nr_lock_classes; | |
81 | static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; | |
82 | ||
83 | /* | |
84 | * We keep a global list of all lock classes. The list only grows, | |
85 | * never shrinks. The list is only accessed with the lockdep | |
86 | * spinlock lock held. | |
87 | */ | |
88 | LIST_HEAD(all_lock_classes); | |
89 | ||
90 | /* | |
91 | * The lockdep classes are in a hash-table as well, for fast lookup: | |
92 | */ | |
93 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) | |
94 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) | |
95 | #define CLASSHASH_MASK (CLASSHASH_SIZE - 1) | |
96 | #define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK) | |
97 | #define classhashentry(key) (classhash_table + __classhashfn((key))) | |
98 | ||
99 | static struct list_head classhash_table[CLASSHASH_SIZE]; | |
100 | ||
101 | unsigned long nr_lock_chains; | |
102 | static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; | |
103 | ||
104 | /* | |
105 | * We put the lock dependency chains into a hash-table as well, to cache | |
106 | * their existence: | |
107 | */ | |
108 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) | |
109 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) | |
110 | #define CHAINHASH_MASK (CHAINHASH_SIZE - 1) | |
111 | #define __chainhashfn(chain) \ | |
112 | (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK) | |
113 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) | |
114 | ||
115 | static struct list_head chainhash_table[CHAINHASH_SIZE]; | |
116 | ||
117 | /* | |
118 | * The hash key of the lock dependency chains is a hash itself too: | |
119 | * it's a hash of all locks taken up to that lock, including that lock. | |
120 | * It's a 64-bit hash, because it's important for the keys to be | |
121 | * unique. | |
122 | */ | |
123 | #define iterate_chain_key(key1, key2) \ | |
124 | (((key1) << MAX_LOCKDEP_KEYS_BITS/2) ^ \ | |
125 | ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS/2)) ^ \ | |
126 | (key2)) | |
127 | ||
128 | void lockdep_off(void) | |
129 | { | |
130 | current->lockdep_recursion++; | |
131 | } | |
132 | ||
133 | EXPORT_SYMBOL(lockdep_off); | |
134 | ||
135 | void lockdep_on(void) | |
136 | { | |
137 | current->lockdep_recursion--; | |
138 | } | |
139 | ||
140 | EXPORT_SYMBOL(lockdep_on); | |
141 | ||
142 | int lockdep_internal(void) | |
143 | { | |
144 | return current->lockdep_recursion != 0; | |
145 | } | |
146 | ||
147 | EXPORT_SYMBOL(lockdep_internal); | |
148 | ||
149 | /* | |
150 | * Debugging switches: | |
151 | */ | |
152 | ||
153 | #define VERBOSE 0 | |
154 | #ifdef VERBOSE | |
155 | # define VERY_VERBOSE 0 | |
156 | #endif | |
157 | ||
158 | #if VERBOSE | |
159 | # define HARDIRQ_VERBOSE 1 | |
160 | # define SOFTIRQ_VERBOSE 1 | |
161 | #else | |
162 | # define HARDIRQ_VERBOSE 0 | |
163 | # define SOFTIRQ_VERBOSE 0 | |
164 | #endif | |
165 | ||
166 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE | |
167 | /* | |
168 | * Quick filtering for interesting events: | |
169 | */ | |
170 | static int class_filter(struct lock_class *class) | |
171 | { | |
f9829cce AK |
172 | #if 0 |
173 | /* Example */ | |
fbb9ce95 | 174 | if (class->name_version == 1 && |
f9829cce | 175 | !strcmp(class->name, "lockname")) |
fbb9ce95 IM |
176 | return 1; |
177 | if (class->name_version == 1 && | |
f9829cce | 178 | !strcmp(class->name, "&struct->lockfield")) |
fbb9ce95 | 179 | return 1; |
f9829cce AK |
180 | #endif |
181 | /* Allow everything else. 0 would be filter everything else */ | |
182 | return 1; | |
fbb9ce95 IM |
183 | } |
184 | #endif | |
185 | ||
186 | static int verbose(struct lock_class *class) | |
187 | { | |
188 | #if VERBOSE | |
189 | return class_filter(class); | |
190 | #endif | |
191 | return 0; | |
192 | } | |
193 | ||
194 | #ifdef CONFIG_TRACE_IRQFLAGS | |
195 | ||
196 | static int hardirq_verbose(struct lock_class *class) | |
197 | { | |
198 | #if HARDIRQ_VERBOSE | |
199 | return class_filter(class); | |
200 | #endif | |
201 | return 0; | |
202 | } | |
203 | ||
204 | static int softirq_verbose(struct lock_class *class) | |
205 | { | |
206 | #if SOFTIRQ_VERBOSE | |
207 | return class_filter(class); | |
208 | #endif | |
209 | return 0; | |
210 | } | |
211 | ||
212 | #endif | |
213 | ||
214 | /* | |
215 | * Stack-trace: tightly packed array of stack backtrace | |
216 | * addresses. Protected by the hash_lock. | |
217 | */ | |
218 | unsigned long nr_stack_trace_entries; | |
219 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; | |
220 | ||
221 | static int save_trace(struct stack_trace *trace) | |
222 | { | |
223 | trace->nr_entries = 0; | |
224 | trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; | |
225 | trace->entries = stack_trace + nr_stack_trace_entries; | |
226 | ||
227 | save_stack_trace(trace, NULL, 0, 3); | |
228 | ||
229 | trace->max_entries = trace->nr_entries; | |
230 | ||
231 | nr_stack_trace_entries += trace->nr_entries; | |
232 | if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES)) | |
233 | return 0; | |
234 | ||
235 | if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) { | |
236 | __raw_spin_unlock(&hash_lock); | |
237 | if (debug_locks_off()) { | |
238 | printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); | |
239 | printk("turning off the locking correctness validator.\n"); | |
240 | dump_stack(); | |
241 | } | |
242 | return 0; | |
243 | } | |
244 | ||
245 | return 1; | |
246 | } | |
247 | ||
248 | unsigned int nr_hardirq_chains; | |
249 | unsigned int nr_softirq_chains; | |
250 | unsigned int nr_process_chains; | |
251 | unsigned int max_lockdep_depth; | |
252 | unsigned int max_recursion_depth; | |
253 | ||
254 | #ifdef CONFIG_DEBUG_LOCKDEP | |
255 | /* | |
256 | * We cannot printk in early bootup code. Not even early_printk() | |
257 | * might work. So we mark any initialization errors and printk | |
258 | * about it later on, in lockdep_info(). | |
259 | */ | |
260 | static int lockdep_init_error; | |
261 | ||
262 | /* | |
263 | * Various lockdep statistics: | |
264 | */ | |
265 | atomic_t chain_lookup_hits; | |
266 | atomic_t chain_lookup_misses; | |
267 | atomic_t hardirqs_on_events; | |
268 | atomic_t hardirqs_off_events; | |
269 | atomic_t redundant_hardirqs_on; | |
270 | atomic_t redundant_hardirqs_off; | |
271 | atomic_t softirqs_on_events; | |
272 | atomic_t softirqs_off_events; | |
273 | atomic_t redundant_softirqs_on; | |
274 | atomic_t redundant_softirqs_off; | |
275 | atomic_t nr_unused_locks; | |
276 | atomic_t nr_cyclic_checks; | |
277 | atomic_t nr_cyclic_check_recursions; | |
278 | atomic_t nr_find_usage_forwards_checks; | |
279 | atomic_t nr_find_usage_forwards_recursions; | |
280 | atomic_t nr_find_usage_backwards_checks; | |
281 | atomic_t nr_find_usage_backwards_recursions; | |
282 | # define debug_atomic_inc(ptr) atomic_inc(ptr) | |
283 | # define debug_atomic_dec(ptr) atomic_dec(ptr) | |
284 | # define debug_atomic_read(ptr) atomic_read(ptr) | |
285 | #else | |
286 | # define debug_atomic_inc(ptr) do { } while (0) | |
287 | # define debug_atomic_dec(ptr) do { } while (0) | |
288 | # define debug_atomic_read(ptr) 0 | |
289 | #endif | |
290 | ||
291 | /* | |
292 | * Locking printouts: | |
293 | */ | |
294 | ||
295 | static const char *usage_str[] = | |
296 | { | |
297 | [LOCK_USED] = "initial-use ", | |
298 | [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W", | |
299 | [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W", | |
300 | [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W", | |
301 | [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W", | |
302 | [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R", | |
303 | [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R", | |
304 | [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R", | |
305 | [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R", | |
306 | }; | |
307 | ||
308 | const char * __get_key_name(struct lockdep_subclass_key *key, char *str) | |
309 | { | |
310 | unsigned long offs, size; | |
311 | char *modname; | |
312 | ||
313 | return kallsyms_lookup((unsigned long)key, &size, &offs, &modname, str); | |
314 | } | |
315 | ||
316 | void | |
317 | get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4) | |
318 | { | |
319 | *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.'; | |
320 | ||
321 | if (class->usage_mask & LOCKF_USED_IN_HARDIRQ) | |
322 | *c1 = '+'; | |
323 | else | |
324 | if (class->usage_mask & LOCKF_ENABLED_HARDIRQS) | |
325 | *c1 = '-'; | |
326 | ||
327 | if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ) | |
328 | *c2 = '+'; | |
329 | else | |
330 | if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS) | |
331 | *c2 = '-'; | |
332 | ||
333 | if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) | |
334 | *c3 = '-'; | |
335 | if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) { | |
336 | *c3 = '+'; | |
337 | if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) | |
338 | *c3 = '?'; | |
339 | } | |
340 | ||
341 | if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) | |
342 | *c4 = '-'; | |
343 | if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) { | |
344 | *c4 = '+'; | |
345 | if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) | |
346 | *c4 = '?'; | |
347 | } | |
348 | } | |
349 | ||
350 | static void print_lock_name(struct lock_class *class) | |
351 | { | |
352 | char str[128], c1, c2, c3, c4; | |
353 | const char *name; | |
354 | ||
355 | get_usage_chars(class, &c1, &c2, &c3, &c4); | |
356 | ||
357 | name = class->name; | |
358 | if (!name) { | |
359 | name = __get_key_name(class->key, str); | |
360 | printk(" (%s", name); | |
361 | } else { | |
362 | printk(" (%s", name); | |
363 | if (class->name_version > 1) | |
364 | printk("#%d", class->name_version); | |
365 | if (class->subclass) | |
366 | printk("/%d", class->subclass); | |
367 | } | |
368 | printk("){%c%c%c%c}", c1, c2, c3, c4); | |
369 | } | |
370 | ||
371 | static void print_lockdep_cache(struct lockdep_map *lock) | |
372 | { | |
373 | const char *name; | |
374 | char str[128]; | |
375 | ||
376 | name = lock->name; | |
377 | if (!name) | |
378 | name = __get_key_name(lock->key->subkeys, str); | |
379 | ||
380 | printk("%s", name); | |
381 | } | |
382 | ||
383 | static void print_lock(struct held_lock *hlock) | |
384 | { | |
385 | print_lock_name(hlock->class); | |
386 | printk(", at: "); | |
387 | print_ip_sym(hlock->acquire_ip); | |
388 | } | |
389 | ||
390 | static void lockdep_print_held_locks(struct task_struct *curr) | |
391 | { | |
392 | int i, depth = curr->lockdep_depth; | |
393 | ||
394 | if (!depth) { | |
395 | printk("no locks held by %s/%d.\n", curr->comm, curr->pid); | |
396 | return; | |
397 | } | |
398 | printk("%d lock%s held by %s/%d:\n", | |
399 | depth, depth > 1 ? "s" : "", curr->comm, curr->pid); | |
400 | ||
401 | for (i = 0; i < depth; i++) { | |
402 | printk(" #%d: ", i); | |
403 | print_lock(curr->held_locks + i); | |
404 | } | |
405 | } | |
fbb9ce95 IM |
406 | |
407 | static void print_lock_class_header(struct lock_class *class, int depth) | |
408 | { | |
409 | int bit; | |
410 | ||
f9829cce | 411 | printk("%*s->", depth, ""); |
fbb9ce95 IM |
412 | print_lock_name(class); |
413 | printk(" ops: %lu", class->ops); | |
414 | printk(" {\n"); | |
415 | ||
416 | for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { | |
417 | if (class->usage_mask & (1 << bit)) { | |
418 | int len = depth; | |
419 | ||
f9829cce | 420 | len += printk("%*s %s", depth, "", usage_str[bit]); |
fbb9ce95 IM |
421 | len += printk(" at:\n"); |
422 | print_stack_trace(class->usage_traces + bit, len); | |
423 | } | |
424 | } | |
f9829cce | 425 | printk("%*s }\n", depth, ""); |
fbb9ce95 | 426 | |
f9829cce | 427 | printk("%*s ... key at: ",depth,""); |
fbb9ce95 IM |
428 | print_ip_sym((unsigned long)class->key); |
429 | } | |
430 | ||
431 | /* | |
432 | * printk all lock dependencies starting at <entry>: | |
433 | */ | |
434 | static void print_lock_dependencies(struct lock_class *class, int depth) | |
435 | { | |
436 | struct lock_list *entry; | |
437 | ||
438 | if (DEBUG_LOCKS_WARN_ON(depth >= 20)) | |
439 | return; | |
440 | ||
441 | print_lock_class_header(class, depth); | |
442 | ||
443 | list_for_each_entry(entry, &class->locks_after, entry) { | |
444 | DEBUG_LOCKS_WARN_ON(!entry->class); | |
445 | print_lock_dependencies(entry->class, depth + 1); | |
446 | ||
f9829cce | 447 | printk("%*s ... acquired at:\n",depth,""); |
fbb9ce95 IM |
448 | print_stack_trace(&entry->trace, 2); |
449 | printk("\n"); | |
450 | } | |
451 | } | |
452 | ||
453 | /* | |
454 | * Add a new dependency to the head of the list: | |
455 | */ | |
456 | static int add_lock_to_list(struct lock_class *class, struct lock_class *this, | |
457 | struct list_head *head, unsigned long ip) | |
458 | { | |
459 | struct lock_list *entry; | |
460 | /* | |
461 | * Lock not present yet - get a new dependency struct and | |
462 | * add it to the list: | |
463 | */ | |
464 | entry = alloc_list_entry(); | |
465 | if (!entry) | |
466 | return 0; | |
467 | ||
468 | entry->class = this; | |
469 | save_trace(&entry->trace); | |
470 | ||
471 | /* | |
472 | * Since we never remove from the dependency list, the list can | |
473 | * be walked lockless by other CPUs, it's only allocation | |
474 | * that must be protected by the spinlock. But this also means | |
475 | * we must make new entries visible only once writes to the | |
476 | * entry become visible - hence the RCU op: | |
477 | */ | |
478 | list_add_tail_rcu(&entry->entry, head); | |
479 | ||
480 | return 1; | |
481 | } | |
482 | ||
483 | /* | |
484 | * Recursive, forwards-direction lock-dependency checking, used for | |
485 | * both noncyclic checking and for hardirq-unsafe/softirq-unsafe | |
486 | * checking. | |
487 | * | |
488 | * (to keep the stackframe of the recursive functions small we | |
489 | * use these global variables, and we also mark various helper | |
490 | * functions as noinline.) | |
491 | */ | |
492 | static struct held_lock *check_source, *check_target; | |
493 | ||
494 | /* | |
495 | * Print a dependency chain entry (this is only done when a deadlock | |
496 | * has been detected): | |
497 | */ | |
498 | static noinline int | |
499 | print_circular_bug_entry(struct lock_list *target, unsigned int depth) | |
500 | { | |
501 | if (debug_locks_silent) | |
502 | return 0; | |
503 | printk("\n-> #%u", depth); | |
504 | print_lock_name(target->class); | |
505 | printk(":\n"); | |
506 | print_stack_trace(&target->trace, 6); | |
507 | ||
508 | return 0; | |
509 | } | |
510 | ||
511 | /* | |
512 | * When a circular dependency is detected, print the | |
513 | * header first: | |
514 | */ | |
515 | static noinline int | |
516 | print_circular_bug_header(struct lock_list *entry, unsigned int depth) | |
517 | { | |
518 | struct task_struct *curr = current; | |
519 | ||
520 | __raw_spin_unlock(&hash_lock); | |
521 | debug_locks_off(); | |
522 | if (debug_locks_silent) | |
523 | return 0; | |
524 | ||
525 | printk("\n=======================================================\n"); | |
526 | printk( "[ INFO: possible circular locking dependency detected ]\n"); | |
527 | printk( "-------------------------------------------------------\n"); | |
528 | printk("%s/%d is trying to acquire lock:\n", | |
529 | curr->comm, curr->pid); | |
530 | print_lock(check_source); | |
531 | printk("\nbut task is already holding lock:\n"); | |
532 | print_lock(check_target); | |
533 | printk("\nwhich lock already depends on the new lock.\n\n"); | |
534 | printk("\nthe existing dependency chain (in reverse order) is:\n"); | |
535 | ||
536 | print_circular_bug_entry(entry, depth); | |
537 | ||
538 | return 0; | |
539 | } | |
540 | ||
541 | static noinline int print_circular_bug_tail(void) | |
542 | { | |
543 | struct task_struct *curr = current; | |
544 | struct lock_list this; | |
545 | ||
546 | if (debug_locks_silent) | |
547 | return 0; | |
548 | ||
549 | this.class = check_source->class; | |
550 | save_trace(&this.trace); | |
551 | print_circular_bug_entry(&this, 0); | |
552 | ||
553 | printk("\nother info that might help us debug this:\n\n"); | |
554 | lockdep_print_held_locks(curr); | |
555 | ||
556 | printk("\nstack backtrace:\n"); | |
557 | dump_stack(); | |
558 | ||
559 | return 0; | |
560 | } | |
561 | ||
562 | static int noinline print_infinite_recursion_bug(void) | |
563 | { | |
564 | __raw_spin_unlock(&hash_lock); | |
565 | DEBUG_LOCKS_WARN_ON(1); | |
566 | ||
567 | return 0; | |
568 | } | |
569 | ||
570 | /* | |
571 | * Prove that the dependency graph starting at <entry> can not | |
572 | * lead to <target>. Print an error and return 0 if it does. | |
573 | */ | |
574 | static noinline int | |
575 | check_noncircular(struct lock_class *source, unsigned int depth) | |
576 | { | |
577 | struct lock_list *entry; | |
578 | ||
579 | debug_atomic_inc(&nr_cyclic_check_recursions); | |
580 | if (depth > max_recursion_depth) | |
581 | max_recursion_depth = depth; | |
582 | if (depth >= 20) | |
583 | return print_infinite_recursion_bug(); | |
584 | /* | |
585 | * Check this lock's dependency list: | |
586 | */ | |
587 | list_for_each_entry(entry, &source->locks_after, entry) { | |
588 | if (entry->class == check_target->class) | |
589 | return print_circular_bug_header(entry, depth+1); | |
590 | debug_atomic_inc(&nr_cyclic_checks); | |
591 | if (!check_noncircular(entry->class, depth+1)) | |
592 | return print_circular_bug_entry(entry, depth+1); | |
593 | } | |
594 | return 1; | |
595 | } | |
596 | ||
597 | static int very_verbose(struct lock_class *class) | |
598 | { | |
599 | #if VERY_VERBOSE | |
600 | return class_filter(class); | |
601 | #endif | |
602 | return 0; | |
603 | } | |
604 | #ifdef CONFIG_TRACE_IRQFLAGS | |
605 | ||
606 | /* | |
607 | * Forwards and backwards subgraph searching, for the purposes of | |
608 | * proving that two subgraphs can be connected by a new dependency | |
609 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. | |
610 | */ | |
611 | static enum lock_usage_bit find_usage_bit; | |
612 | static struct lock_class *forwards_match, *backwards_match; | |
613 | ||
614 | /* | |
615 | * Find a node in the forwards-direction dependency sub-graph starting | |
616 | * at <source> that matches <find_usage_bit>. | |
617 | * | |
618 | * Return 2 if such a node exists in the subgraph, and put that node | |
619 | * into <forwards_match>. | |
620 | * | |
621 | * Return 1 otherwise and keep <forwards_match> unchanged. | |
622 | * Return 0 on error. | |
623 | */ | |
624 | static noinline int | |
625 | find_usage_forwards(struct lock_class *source, unsigned int depth) | |
626 | { | |
627 | struct lock_list *entry; | |
628 | int ret; | |
629 | ||
630 | if (depth > max_recursion_depth) | |
631 | max_recursion_depth = depth; | |
632 | if (depth >= 20) | |
633 | return print_infinite_recursion_bug(); | |
634 | ||
635 | debug_atomic_inc(&nr_find_usage_forwards_checks); | |
636 | if (source->usage_mask & (1 << find_usage_bit)) { | |
637 | forwards_match = source; | |
638 | return 2; | |
639 | } | |
640 | ||
641 | /* | |
642 | * Check this lock's dependency list: | |
643 | */ | |
644 | list_for_each_entry(entry, &source->locks_after, entry) { | |
645 | debug_atomic_inc(&nr_find_usage_forwards_recursions); | |
646 | ret = find_usage_forwards(entry->class, depth+1); | |
647 | if (ret == 2 || ret == 0) | |
648 | return ret; | |
649 | } | |
650 | return 1; | |
651 | } | |
652 | ||
653 | /* | |
654 | * Find a node in the backwards-direction dependency sub-graph starting | |
655 | * at <source> that matches <find_usage_bit>. | |
656 | * | |
657 | * Return 2 if such a node exists in the subgraph, and put that node | |
658 | * into <backwards_match>. | |
659 | * | |
660 | * Return 1 otherwise and keep <backwards_match> unchanged. | |
661 | * Return 0 on error. | |
662 | */ | |
663 | static noinline int | |
664 | find_usage_backwards(struct lock_class *source, unsigned int depth) | |
665 | { | |
666 | struct lock_list *entry; | |
667 | int ret; | |
668 | ||
669 | if (depth > max_recursion_depth) | |
670 | max_recursion_depth = depth; | |
671 | if (depth >= 20) | |
672 | return print_infinite_recursion_bug(); | |
673 | ||
674 | debug_atomic_inc(&nr_find_usage_backwards_checks); | |
675 | if (source->usage_mask & (1 << find_usage_bit)) { | |
676 | backwards_match = source; | |
677 | return 2; | |
678 | } | |
679 | ||
680 | /* | |
681 | * Check this lock's dependency list: | |
682 | */ | |
683 | list_for_each_entry(entry, &source->locks_before, entry) { | |
684 | debug_atomic_inc(&nr_find_usage_backwards_recursions); | |
685 | ret = find_usage_backwards(entry->class, depth+1); | |
686 | if (ret == 2 || ret == 0) | |
687 | return ret; | |
688 | } | |
689 | return 1; | |
690 | } | |
691 | ||
692 | static int | |
693 | print_bad_irq_dependency(struct task_struct *curr, | |
694 | struct held_lock *prev, | |
695 | struct held_lock *next, | |
696 | enum lock_usage_bit bit1, | |
697 | enum lock_usage_bit bit2, | |
698 | const char *irqclass) | |
699 | { | |
700 | __raw_spin_unlock(&hash_lock); | |
701 | debug_locks_off(); | |
702 | if (debug_locks_silent) | |
703 | return 0; | |
704 | ||
705 | printk("\n======================================================\n"); | |
706 | printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", | |
707 | irqclass, irqclass); | |
708 | printk( "------------------------------------------------------\n"); | |
709 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", | |
710 | curr->comm, curr->pid, | |
711 | curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, | |
712 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, | |
713 | curr->hardirqs_enabled, | |
714 | curr->softirqs_enabled); | |
715 | print_lock(next); | |
716 | ||
717 | printk("\nand this task is already holding:\n"); | |
718 | print_lock(prev); | |
719 | printk("which would create a new lock dependency:\n"); | |
720 | print_lock_name(prev->class); | |
721 | printk(" ->"); | |
722 | print_lock_name(next->class); | |
723 | printk("\n"); | |
724 | ||
725 | printk("\nbut this new dependency connects a %s-irq-safe lock:\n", | |
726 | irqclass); | |
727 | print_lock_name(backwards_match); | |
728 | printk("\n... which became %s-irq-safe at:\n", irqclass); | |
729 | ||
730 | print_stack_trace(backwards_match->usage_traces + bit1, 1); | |
731 | ||
732 | printk("\nto a %s-irq-unsafe lock:\n", irqclass); | |
733 | print_lock_name(forwards_match); | |
734 | printk("\n... which became %s-irq-unsafe at:\n", irqclass); | |
735 | printk("..."); | |
736 | ||
737 | print_stack_trace(forwards_match->usage_traces + bit2, 1); | |
738 | ||
739 | printk("\nother info that might help us debug this:\n\n"); | |
740 | lockdep_print_held_locks(curr); | |
741 | ||
742 | printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass); | |
743 | print_lock_dependencies(backwards_match, 0); | |
744 | ||
745 | printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass); | |
746 | print_lock_dependencies(forwards_match, 0); | |
747 | ||
748 | printk("\nstack backtrace:\n"); | |
749 | dump_stack(); | |
750 | ||
751 | return 0; | |
752 | } | |
753 | ||
754 | static int | |
755 | check_usage(struct task_struct *curr, struct held_lock *prev, | |
756 | struct held_lock *next, enum lock_usage_bit bit_backwards, | |
757 | enum lock_usage_bit bit_forwards, const char *irqclass) | |
758 | { | |
759 | int ret; | |
760 | ||
761 | find_usage_bit = bit_backwards; | |
762 | /* fills in <backwards_match> */ | |
763 | ret = find_usage_backwards(prev->class, 0); | |
764 | if (!ret || ret == 1) | |
765 | return ret; | |
766 | ||
767 | find_usage_bit = bit_forwards; | |
768 | ret = find_usage_forwards(next->class, 0); | |
769 | if (!ret || ret == 1) | |
770 | return ret; | |
771 | /* ret == 2 */ | |
772 | return print_bad_irq_dependency(curr, prev, next, | |
773 | bit_backwards, bit_forwards, irqclass); | |
774 | } | |
775 | ||
776 | #endif | |
777 | ||
778 | static int | |
779 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, | |
780 | struct held_lock *next) | |
781 | { | |
782 | debug_locks_off(); | |
783 | __raw_spin_unlock(&hash_lock); | |
784 | if (debug_locks_silent) | |
785 | return 0; | |
786 | ||
787 | printk("\n=============================================\n"); | |
788 | printk( "[ INFO: possible recursive locking detected ]\n"); | |
789 | printk( "---------------------------------------------\n"); | |
790 | printk("%s/%d is trying to acquire lock:\n", | |
791 | curr->comm, curr->pid); | |
792 | print_lock(next); | |
793 | printk("\nbut task is already holding lock:\n"); | |
794 | print_lock(prev); | |
795 | ||
796 | printk("\nother info that might help us debug this:\n"); | |
797 | lockdep_print_held_locks(curr); | |
798 | ||
799 | printk("\nstack backtrace:\n"); | |
800 | dump_stack(); | |
801 | ||
802 | return 0; | |
803 | } | |
804 | ||
805 | /* | |
806 | * Check whether we are holding such a class already. | |
807 | * | |
808 | * (Note that this has to be done separately, because the graph cannot | |
809 | * detect such classes of deadlocks.) | |
810 | * | |
811 | * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read | |
812 | */ | |
813 | static int | |
814 | check_deadlock(struct task_struct *curr, struct held_lock *next, | |
815 | struct lockdep_map *next_instance, int read) | |
816 | { | |
817 | struct held_lock *prev; | |
818 | int i; | |
819 | ||
820 | for (i = 0; i < curr->lockdep_depth; i++) { | |
821 | prev = curr->held_locks + i; | |
822 | if (prev->class != next->class) | |
823 | continue; | |
824 | /* | |
825 | * Allow read-after-read recursion of the same | |
6c9076ec | 826 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
fbb9ce95 | 827 | */ |
6c9076ec | 828 | if ((read == 2) && prev->read) |
fbb9ce95 IM |
829 | return 2; |
830 | return print_deadlock_bug(curr, prev, next); | |
831 | } | |
832 | return 1; | |
833 | } | |
834 | ||
835 | /* | |
836 | * There was a chain-cache miss, and we are about to add a new dependency | |
837 | * to a previous lock. We recursively validate the following rules: | |
838 | * | |
839 | * - would the adding of the <prev> -> <next> dependency create a | |
840 | * circular dependency in the graph? [== circular deadlock] | |
841 | * | |
842 | * - does the new prev->next dependency connect any hardirq-safe lock | |
843 | * (in the full backwards-subgraph starting at <prev>) with any | |
844 | * hardirq-unsafe lock (in the full forwards-subgraph starting at | |
845 | * <next>)? [== illegal lock inversion with hardirq contexts] | |
846 | * | |
847 | * - does the new prev->next dependency connect any softirq-safe lock | |
848 | * (in the full backwards-subgraph starting at <prev>) with any | |
849 | * softirq-unsafe lock (in the full forwards-subgraph starting at | |
850 | * <next>)? [== illegal lock inversion with softirq contexts] | |
851 | * | |
852 | * any of these scenarios could lead to a deadlock. | |
853 | * | |
854 | * Then if all the validations pass, we add the forwards and backwards | |
855 | * dependency. | |
856 | */ | |
857 | static int | |
858 | check_prev_add(struct task_struct *curr, struct held_lock *prev, | |
859 | struct held_lock *next) | |
860 | { | |
861 | struct lock_list *entry; | |
862 | int ret; | |
863 | ||
864 | /* | |
865 | * Prove that the new <prev> -> <next> dependency would not | |
866 | * create a circular dependency in the graph. (We do this by | |
867 | * forward-recursing into the graph starting at <next>, and | |
868 | * checking whether we can reach <prev>.) | |
869 | * | |
870 | * We are using global variables to control the recursion, to | |
871 | * keep the stackframe size of the recursive functions low: | |
872 | */ | |
873 | check_source = next; | |
874 | check_target = prev; | |
875 | if (!(check_noncircular(next->class, 0))) | |
876 | return print_circular_bug_tail(); | |
877 | ||
878 | #ifdef CONFIG_TRACE_IRQFLAGS | |
879 | /* | |
880 | * Prove that the new dependency does not connect a hardirq-safe | |
881 | * lock with a hardirq-unsafe lock - to achieve this we search | |
882 | * the backwards-subgraph starting at <prev>, and the | |
883 | * forwards-subgraph starting at <next>: | |
884 | */ | |
885 | if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ, | |
886 | LOCK_ENABLED_HARDIRQS, "hard")) | |
887 | return 0; | |
888 | ||
889 | /* | |
890 | * Prove that the new dependency does not connect a hardirq-safe-read | |
891 | * lock with a hardirq-unsafe lock - to achieve this we search | |
892 | * the backwards-subgraph starting at <prev>, and the | |
893 | * forwards-subgraph starting at <next>: | |
894 | */ | |
895 | if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ, | |
896 | LOCK_ENABLED_HARDIRQS, "hard-read")) | |
897 | return 0; | |
898 | ||
899 | /* | |
900 | * Prove that the new dependency does not connect a softirq-safe | |
901 | * lock with a softirq-unsafe lock - to achieve this we search | |
902 | * the backwards-subgraph starting at <prev>, and the | |
903 | * forwards-subgraph starting at <next>: | |
904 | */ | |
905 | if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ, | |
906 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
907 | return 0; | |
908 | /* | |
909 | * Prove that the new dependency does not connect a softirq-safe-read | |
910 | * lock with a softirq-unsafe lock - to achieve this we search | |
911 | * the backwards-subgraph starting at <prev>, and the | |
912 | * forwards-subgraph starting at <next>: | |
913 | */ | |
914 | if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ, | |
915 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
916 | return 0; | |
917 | #endif | |
918 | /* | |
919 | * For recursive read-locks we do all the dependency checks, | |
920 | * but we dont store read-triggered dependencies (only | |
921 | * write-triggered dependencies). This ensures that only the | |
922 | * write-side dependencies matter, and that if for example a | |
923 | * write-lock never takes any other locks, then the reads are | |
924 | * equivalent to a NOP. | |
925 | */ | |
926 | if (next->read == 2 || prev->read == 2) | |
927 | return 1; | |
928 | /* | |
929 | * Is the <prev> -> <next> dependency already present? | |
930 | * | |
931 | * (this may occur even though this is a new chain: consider | |
932 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 | |
933 | * chains - the second one will be new, but L1 already has | |
934 | * L2 added to its dependency list, due to the first chain.) | |
935 | */ | |
936 | list_for_each_entry(entry, &prev->class->locks_after, entry) { | |
937 | if (entry->class == next->class) | |
938 | return 2; | |
939 | } | |
940 | ||
941 | /* | |
942 | * Ok, all validations passed, add the new lock | |
943 | * to the previous lock's dependency list: | |
944 | */ | |
945 | ret = add_lock_to_list(prev->class, next->class, | |
946 | &prev->class->locks_after, next->acquire_ip); | |
947 | if (!ret) | |
948 | return 0; | |
949 | /* | |
950 | * Return value of 2 signals 'dependency already added', | |
951 | * in that case we dont have to add the backlink either. | |
952 | */ | |
953 | if (ret == 2) | |
954 | return 2; | |
955 | ret = add_lock_to_list(next->class, prev->class, | |
956 | &next->class->locks_before, next->acquire_ip); | |
957 | ||
958 | /* | |
959 | * Debugging printouts: | |
960 | */ | |
961 | if (verbose(prev->class) || verbose(next->class)) { | |
962 | __raw_spin_unlock(&hash_lock); | |
963 | printk("\n new dependency: "); | |
964 | print_lock_name(prev->class); | |
965 | printk(" => "); | |
966 | print_lock_name(next->class); | |
967 | printk("\n"); | |
968 | dump_stack(); | |
969 | __raw_spin_lock(&hash_lock); | |
970 | } | |
971 | return 1; | |
972 | } | |
973 | ||
974 | /* | |
975 | * Add the dependency to all directly-previous locks that are 'relevant'. | |
976 | * The ones that are relevant are (in increasing distance from curr): | |
977 | * all consecutive trylock entries and the final non-trylock entry - or | |
978 | * the end of this context's lock-chain - whichever comes first. | |
979 | */ | |
980 | static int | |
981 | check_prevs_add(struct task_struct *curr, struct held_lock *next) | |
982 | { | |
983 | int depth = curr->lockdep_depth; | |
984 | struct held_lock *hlock; | |
985 | ||
986 | /* | |
987 | * Debugging checks. | |
988 | * | |
989 | * Depth must not be zero for a non-head lock: | |
990 | */ | |
991 | if (!depth) | |
992 | goto out_bug; | |
993 | /* | |
994 | * At least two relevant locks must exist for this | |
995 | * to be a head: | |
996 | */ | |
997 | if (curr->held_locks[depth].irq_context != | |
998 | curr->held_locks[depth-1].irq_context) | |
999 | goto out_bug; | |
1000 | ||
1001 | for (;;) { | |
1002 | hlock = curr->held_locks + depth-1; | |
1003 | /* | |
1004 | * Only non-recursive-read entries get new dependencies | |
1005 | * added: | |
1006 | */ | |
1007 | if (hlock->read != 2) { | |
1008 | check_prev_add(curr, hlock, next); | |
1009 | /* | |
1010 | * Stop after the first non-trylock entry, | |
1011 | * as non-trylock entries have added their | |
1012 | * own direct dependencies already, so this | |
1013 | * lock is connected to them indirectly: | |
1014 | */ | |
1015 | if (!hlock->trylock) | |
1016 | break; | |
1017 | } | |
1018 | depth--; | |
1019 | /* | |
1020 | * End of lock-stack? | |
1021 | */ | |
1022 | if (!depth) | |
1023 | break; | |
1024 | /* | |
1025 | * Stop the search if we cross into another context: | |
1026 | */ | |
1027 | if (curr->held_locks[depth].irq_context != | |
1028 | curr->held_locks[depth-1].irq_context) | |
1029 | break; | |
1030 | } | |
1031 | return 1; | |
1032 | out_bug: | |
1033 | __raw_spin_unlock(&hash_lock); | |
1034 | DEBUG_LOCKS_WARN_ON(1); | |
1035 | ||
1036 | return 0; | |
1037 | } | |
1038 | ||
1039 | ||
1040 | /* | |
1041 | * Is this the address of a static object: | |
1042 | */ | |
1043 | static int static_obj(void *obj) | |
1044 | { | |
1045 | unsigned long start = (unsigned long) &_stext, | |
1046 | end = (unsigned long) &_end, | |
1047 | addr = (unsigned long) obj; | |
1048 | #ifdef CONFIG_SMP | |
1049 | int i; | |
1050 | #endif | |
1051 | ||
1052 | /* | |
1053 | * static variable? | |
1054 | */ | |
1055 | if ((addr >= start) && (addr < end)) | |
1056 | return 1; | |
1057 | ||
1058 | #ifdef CONFIG_SMP | |
1059 | /* | |
1060 | * percpu var? | |
1061 | */ | |
1062 | for_each_possible_cpu(i) { | |
1063 | start = (unsigned long) &__per_cpu_start + per_cpu_offset(i); | |
1064 | end = (unsigned long) &__per_cpu_end + per_cpu_offset(i); | |
1065 | ||
1066 | if ((addr >= start) && (addr < end)) | |
1067 | return 1; | |
1068 | } | |
1069 | #endif | |
1070 | ||
1071 | /* | |
1072 | * module var? | |
1073 | */ | |
1074 | return is_module_address(addr); | |
1075 | } | |
1076 | ||
1077 | /* | |
1078 | * To make lock name printouts unique, we calculate a unique | |
1079 | * class->name_version generation counter: | |
1080 | */ | |
1081 | static int count_matching_names(struct lock_class *new_class) | |
1082 | { | |
1083 | struct lock_class *class; | |
1084 | int count = 0; | |
1085 | ||
1086 | if (!new_class->name) | |
1087 | return 0; | |
1088 | ||
1089 | list_for_each_entry(class, &all_lock_classes, lock_entry) { | |
1090 | if (new_class->key - new_class->subclass == class->key) | |
1091 | return class->name_version; | |
1092 | if (class->name && !strcmp(class->name, new_class->name)) | |
1093 | count = max(count, class->name_version); | |
1094 | } | |
1095 | ||
1096 | return count + 1; | |
1097 | } | |
1098 | ||
1099 | extern void __error_too_big_MAX_LOCKDEP_SUBCLASSES(void); | |
1100 | ||
1101 | /* | |
1102 | * Register a lock's class in the hash-table, if the class is not present | |
1103 | * yet. Otherwise we look it up. We cache the result in the lock object | |
1104 | * itself, so actual lookup of the hash should be once per lock object. | |
1105 | */ | |
1106 | static inline struct lock_class * | |
1107 | register_lock_class(struct lockdep_map *lock, unsigned int subclass) | |
1108 | { | |
1109 | struct lockdep_subclass_key *key; | |
1110 | struct list_head *hash_head; | |
1111 | struct lock_class *class; | |
1112 | ||
1113 | #ifdef CONFIG_DEBUG_LOCKDEP | |
1114 | /* | |
1115 | * If the architecture calls into lockdep before initializing | |
1116 | * the hashes then we'll warn about it later. (we cannot printk | |
1117 | * right now) | |
1118 | */ | |
1119 | if (unlikely(!lockdep_initialized)) { | |
1120 | lockdep_init(); | |
1121 | lockdep_init_error = 1; | |
1122 | } | |
1123 | #endif | |
1124 | ||
1125 | /* | |
1126 | * Static locks do not have their class-keys yet - for them the key | |
1127 | * is the lock object itself: | |
1128 | */ | |
1129 | if (unlikely(!lock->key)) | |
1130 | lock->key = (void *)lock; | |
1131 | ||
1132 | /* | |
1133 | * NOTE: the class-key must be unique. For dynamic locks, a static | |
1134 | * lock_class_key variable is passed in through the mutex_init() | |
1135 | * (or spin_lock_init()) call - which acts as the key. For static | |
1136 | * locks we use the lock object itself as the key. | |
1137 | */ | |
1138 | if (sizeof(struct lock_class_key) > sizeof(struct lock_class)) | |
1139 | __error_too_big_MAX_LOCKDEP_SUBCLASSES(); | |
1140 | ||
1141 | key = lock->key->subkeys + subclass; | |
1142 | ||
1143 | hash_head = classhashentry(key); | |
1144 | ||
1145 | /* | |
1146 | * We can walk the hash lockfree, because the hash only | |
1147 | * grows, and we are careful when adding entries to the end: | |
1148 | */ | |
1149 | list_for_each_entry(class, hash_head, hash_entry) | |
1150 | if (class->key == key) | |
1151 | goto out_set; | |
1152 | ||
1153 | /* | |
1154 | * Debug-check: all keys must be persistent! | |
1155 | */ | |
1156 | if (!static_obj(lock->key)) { | |
1157 | debug_locks_off(); | |
1158 | printk("INFO: trying to register non-static key.\n"); | |
1159 | printk("the code is fine but needs lockdep annotation.\n"); | |
1160 | printk("turning off the locking correctness validator.\n"); | |
1161 | dump_stack(); | |
1162 | ||
1163 | return NULL; | |
1164 | } | |
1165 | ||
1166 | __raw_spin_lock(&hash_lock); | |
1167 | /* | |
1168 | * We have to do the hash-walk again, to avoid races | |
1169 | * with another CPU: | |
1170 | */ | |
1171 | list_for_each_entry(class, hash_head, hash_entry) | |
1172 | if (class->key == key) | |
1173 | goto out_unlock_set; | |
1174 | /* | |
1175 | * Allocate a new key from the static array, and add it to | |
1176 | * the hash: | |
1177 | */ | |
1178 | if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { | |
1179 | __raw_spin_unlock(&hash_lock); | |
1180 | debug_locks_off(); | |
1181 | printk("BUG: MAX_LOCKDEP_KEYS too low!\n"); | |
1182 | printk("turning off the locking correctness validator.\n"); | |
1183 | return NULL; | |
1184 | } | |
1185 | class = lock_classes + nr_lock_classes++; | |
1186 | debug_atomic_inc(&nr_unused_locks); | |
1187 | class->key = key; | |
1188 | class->name = lock->name; | |
1189 | class->subclass = subclass; | |
1190 | INIT_LIST_HEAD(&class->lock_entry); | |
1191 | INIT_LIST_HEAD(&class->locks_before); | |
1192 | INIT_LIST_HEAD(&class->locks_after); | |
1193 | class->name_version = count_matching_names(class); | |
1194 | /* | |
1195 | * We use RCU's safe list-add method to make | |
1196 | * parallel walking of the hash-list safe: | |
1197 | */ | |
1198 | list_add_tail_rcu(&class->hash_entry, hash_head); | |
1199 | ||
1200 | if (verbose(class)) { | |
1201 | __raw_spin_unlock(&hash_lock); | |
1202 | printk("\nnew class %p: %s", class->key, class->name); | |
1203 | if (class->name_version > 1) | |
1204 | printk("#%d", class->name_version); | |
1205 | printk("\n"); | |
1206 | dump_stack(); | |
1207 | __raw_spin_lock(&hash_lock); | |
1208 | } | |
1209 | out_unlock_set: | |
1210 | __raw_spin_unlock(&hash_lock); | |
1211 | ||
1212 | out_set: | |
1213 | lock->class[subclass] = class; | |
1214 | ||
1215 | DEBUG_LOCKS_WARN_ON(class->subclass != subclass); | |
1216 | ||
1217 | return class; | |
1218 | } | |
1219 | ||
1220 | /* | |
1221 | * Look up a dependency chain. If the key is not present yet then | |
1222 | * add it and return 0 - in this case the new dependency chain is | |
1223 | * validated. If the key is already hashed, return 1. | |
1224 | */ | |
1225 | static inline int lookup_chain_cache(u64 chain_key) | |
1226 | { | |
1227 | struct list_head *hash_head = chainhashentry(chain_key); | |
1228 | struct lock_chain *chain; | |
1229 | ||
1230 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); | |
1231 | /* | |
1232 | * We can walk it lock-free, because entries only get added | |
1233 | * to the hash: | |
1234 | */ | |
1235 | list_for_each_entry(chain, hash_head, entry) { | |
1236 | if (chain->chain_key == chain_key) { | |
1237 | cache_hit: | |
1238 | debug_atomic_inc(&chain_lookup_hits); | |
1239 | /* | |
1240 | * In the debugging case, force redundant checking | |
1241 | * by returning 1: | |
1242 | */ | |
1243 | #ifdef CONFIG_DEBUG_LOCKDEP | |
1244 | __raw_spin_lock(&hash_lock); | |
1245 | return 1; | |
1246 | #endif | |
1247 | return 0; | |
1248 | } | |
1249 | } | |
1250 | /* | |
1251 | * Allocate a new chain entry from the static array, and add | |
1252 | * it to the hash: | |
1253 | */ | |
1254 | __raw_spin_lock(&hash_lock); | |
1255 | /* | |
1256 | * We have to walk the chain again locked - to avoid duplicates: | |
1257 | */ | |
1258 | list_for_each_entry(chain, hash_head, entry) { | |
1259 | if (chain->chain_key == chain_key) { | |
1260 | __raw_spin_unlock(&hash_lock); | |
1261 | goto cache_hit; | |
1262 | } | |
1263 | } | |
1264 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { | |
1265 | __raw_spin_unlock(&hash_lock); | |
1266 | debug_locks_off(); | |
1267 | printk("BUG: MAX_LOCKDEP_CHAINS too low!\n"); | |
1268 | printk("turning off the locking correctness validator.\n"); | |
1269 | return 0; | |
1270 | } | |
1271 | chain = lock_chains + nr_lock_chains++; | |
1272 | chain->chain_key = chain_key; | |
1273 | list_add_tail_rcu(&chain->entry, hash_head); | |
1274 | debug_atomic_inc(&chain_lookup_misses); | |
1275 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1276 | if (current->hardirq_context) | |
1277 | nr_hardirq_chains++; | |
1278 | else { | |
1279 | if (current->softirq_context) | |
1280 | nr_softirq_chains++; | |
1281 | else | |
1282 | nr_process_chains++; | |
1283 | } | |
1284 | #else | |
1285 | nr_process_chains++; | |
1286 | #endif | |
1287 | ||
1288 | return 1; | |
1289 | } | |
1290 | ||
1291 | /* | |
1292 | * We are building curr_chain_key incrementally, so double-check | |
1293 | * it from scratch, to make sure that it's done correctly: | |
1294 | */ | |
1295 | static void check_chain_key(struct task_struct *curr) | |
1296 | { | |
1297 | #ifdef CONFIG_DEBUG_LOCKDEP | |
1298 | struct held_lock *hlock, *prev_hlock = NULL; | |
1299 | unsigned int i, id; | |
1300 | u64 chain_key = 0; | |
1301 | ||
1302 | for (i = 0; i < curr->lockdep_depth; i++) { | |
1303 | hlock = curr->held_locks + i; | |
1304 | if (chain_key != hlock->prev_chain_key) { | |
1305 | debug_locks_off(); | |
1306 | printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n", | |
1307 | curr->lockdep_depth, i, | |
1308 | (unsigned long long)chain_key, | |
1309 | (unsigned long long)hlock->prev_chain_key); | |
1310 | WARN_ON(1); | |
1311 | return; | |
1312 | } | |
1313 | id = hlock->class - lock_classes; | |
1314 | DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS); | |
1315 | if (prev_hlock && (prev_hlock->irq_context != | |
1316 | hlock->irq_context)) | |
1317 | chain_key = 0; | |
1318 | chain_key = iterate_chain_key(chain_key, id); | |
1319 | prev_hlock = hlock; | |
1320 | } | |
1321 | if (chain_key != curr->curr_chain_key) { | |
1322 | debug_locks_off(); | |
1323 | printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n", | |
1324 | curr->lockdep_depth, i, | |
1325 | (unsigned long long)chain_key, | |
1326 | (unsigned long long)curr->curr_chain_key); | |
1327 | WARN_ON(1); | |
1328 | } | |
1329 | #endif | |
1330 | } | |
1331 | ||
1332 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1333 | ||
1334 | /* | |
1335 | * print irq inversion bug: | |
1336 | */ | |
1337 | static int | |
1338 | print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other, | |
1339 | struct held_lock *this, int forwards, | |
1340 | const char *irqclass) | |
1341 | { | |
1342 | __raw_spin_unlock(&hash_lock); | |
1343 | debug_locks_off(); | |
1344 | if (debug_locks_silent) | |
1345 | return 0; | |
1346 | ||
1347 | printk("\n=========================================================\n"); | |
1348 | printk( "[ INFO: possible irq lock inversion dependency detected ]\n"); | |
1349 | printk( "---------------------------------------------------------\n"); | |
1350 | printk("%s/%d just changed the state of lock:\n", | |
1351 | curr->comm, curr->pid); | |
1352 | print_lock(this); | |
1353 | if (forwards) | |
1354 | printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass); | |
1355 | else | |
1356 | printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass); | |
1357 | print_lock_name(other); | |
1358 | printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); | |
1359 | ||
1360 | printk("\nother info that might help us debug this:\n"); | |
1361 | lockdep_print_held_locks(curr); | |
1362 | ||
1363 | printk("\nthe first lock's dependencies:\n"); | |
1364 | print_lock_dependencies(this->class, 0); | |
1365 | ||
1366 | printk("\nthe second lock's dependencies:\n"); | |
1367 | print_lock_dependencies(other, 0); | |
1368 | ||
1369 | printk("\nstack backtrace:\n"); | |
1370 | dump_stack(); | |
1371 | ||
1372 | return 0; | |
1373 | } | |
1374 | ||
1375 | /* | |
1376 | * Prove that in the forwards-direction subgraph starting at <this> | |
1377 | * there is no lock matching <mask>: | |
1378 | */ | |
1379 | static int | |
1380 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, | |
1381 | enum lock_usage_bit bit, const char *irqclass) | |
1382 | { | |
1383 | int ret; | |
1384 | ||
1385 | find_usage_bit = bit; | |
1386 | /* fills in <forwards_match> */ | |
1387 | ret = find_usage_forwards(this->class, 0); | |
1388 | if (!ret || ret == 1) | |
1389 | return ret; | |
1390 | ||
1391 | return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass); | |
1392 | } | |
1393 | ||
1394 | /* | |
1395 | * Prove that in the backwards-direction subgraph starting at <this> | |
1396 | * there is no lock matching <mask>: | |
1397 | */ | |
1398 | static int | |
1399 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, | |
1400 | enum lock_usage_bit bit, const char *irqclass) | |
1401 | { | |
1402 | int ret; | |
1403 | ||
1404 | find_usage_bit = bit; | |
1405 | /* fills in <backwards_match> */ | |
1406 | ret = find_usage_backwards(this->class, 0); | |
1407 | if (!ret || ret == 1) | |
1408 | return ret; | |
1409 | ||
1410 | return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass); | |
1411 | } | |
1412 | ||
1413 | static inline void print_irqtrace_events(struct task_struct *curr) | |
1414 | { | |
1415 | printk("irq event stamp: %u\n", curr->irq_events); | |
1416 | printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event); | |
1417 | print_ip_sym(curr->hardirq_enable_ip); | |
1418 | printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event); | |
1419 | print_ip_sym(curr->hardirq_disable_ip); | |
1420 | printk("softirqs last enabled at (%u): ", curr->softirq_enable_event); | |
1421 | print_ip_sym(curr->softirq_enable_ip); | |
1422 | printk("softirqs last disabled at (%u): ", curr->softirq_disable_event); | |
1423 | print_ip_sym(curr->softirq_disable_ip); | |
1424 | } | |
1425 | ||
1426 | #else | |
1427 | static inline void print_irqtrace_events(struct task_struct *curr) | |
1428 | { | |
1429 | } | |
1430 | #endif | |
1431 | ||
1432 | static int | |
1433 | print_usage_bug(struct task_struct *curr, struct held_lock *this, | |
1434 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) | |
1435 | { | |
1436 | __raw_spin_unlock(&hash_lock); | |
1437 | debug_locks_off(); | |
1438 | if (debug_locks_silent) | |
1439 | return 0; | |
1440 | ||
1441 | printk("\n=================================\n"); | |
1442 | printk( "[ INFO: inconsistent lock state ]\n"); | |
1443 | printk( "---------------------------------\n"); | |
1444 | ||
1445 | printk("inconsistent {%s} -> {%s} usage.\n", | |
1446 | usage_str[prev_bit], usage_str[new_bit]); | |
1447 | ||
1448 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", | |
1449 | curr->comm, curr->pid, | |
1450 | trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, | |
1451 | trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, | |
1452 | trace_hardirqs_enabled(curr), | |
1453 | trace_softirqs_enabled(curr)); | |
1454 | print_lock(this); | |
1455 | ||
1456 | printk("{%s} state was registered at:\n", usage_str[prev_bit]); | |
1457 | print_stack_trace(this->class->usage_traces + prev_bit, 1); | |
1458 | ||
1459 | print_irqtrace_events(curr); | |
1460 | printk("\nother info that might help us debug this:\n"); | |
1461 | lockdep_print_held_locks(curr); | |
1462 | ||
1463 | printk("\nstack backtrace:\n"); | |
1464 | dump_stack(); | |
1465 | ||
1466 | return 0; | |
1467 | } | |
1468 | ||
1469 | /* | |
1470 | * Print out an error if an invalid bit is set: | |
1471 | */ | |
1472 | static inline int | |
1473 | valid_state(struct task_struct *curr, struct held_lock *this, | |
1474 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) | |
1475 | { | |
1476 | if (unlikely(this->class->usage_mask & (1 << bad_bit))) | |
1477 | return print_usage_bug(curr, this, bad_bit, new_bit); | |
1478 | return 1; | |
1479 | } | |
1480 | ||
1481 | #define STRICT_READ_CHECKS 1 | |
1482 | ||
1483 | /* | |
1484 | * Mark a lock with a usage bit, and validate the state transition: | |
1485 | */ | |
1486 | static int mark_lock(struct task_struct *curr, struct held_lock *this, | |
1487 | enum lock_usage_bit new_bit, unsigned long ip) | |
1488 | { | |
1489 | unsigned int new_mask = 1 << new_bit, ret = 1; | |
1490 | ||
1491 | /* | |
1492 | * If already set then do not dirty the cacheline, | |
1493 | * nor do any checks: | |
1494 | */ | |
1495 | if (likely(this->class->usage_mask & new_mask)) | |
1496 | return 1; | |
1497 | ||
1498 | __raw_spin_lock(&hash_lock); | |
1499 | /* | |
1500 | * Make sure we didnt race: | |
1501 | */ | |
1502 | if (unlikely(this->class->usage_mask & new_mask)) { | |
1503 | __raw_spin_unlock(&hash_lock); | |
1504 | return 1; | |
1505 | } | |
1506 | ||
1507 | this->class->usage_mask |= new_mask; | |
1508 | ||
1509 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1510 | if (new_bit == LOCK_ENABLED_HARDIRQS || | |
1511 | new_bit == LOCK_ENABLED_HARDIRQS_READ) | |
1512 | ip = curr->hardirq_enable_ip; | |
1513 | else if (new_bit == LOCK_ENABLED_SOFTIRQS || | |
1514 | new_bit == LOCK_ENABLED_SOFTIRQS_READ) | |
1515 | ip = curr->softirq_enable_ip; | |
1516 | #endif | |
1517 | if (!save_trace(this->class->usage_traces + new_bit)) | |
1518 | return 0; | |
1519 | ||
1520 | switch (new_bit) { | |
1521 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1522 | case LOCK_USED_IN_HARDIRQ: | |
1523 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS)) | |
1524 | return 0; | |
1525 | if (!valid_state(curr, this, new_bit, | |
1526 | LOCK_ENABLED_HARDIRQS_READ)) | |
1527 | return 0; | |
1528 | /* | |
1529 | * just marked it hardirq-safe, check that this lock | |
1530 | * took no hardirq-unsafe lock in the past: | |
1531 | */ | |
1532 | if (!check_usage_forwards(curr, this, | |
1533 | LOCK_ENABLED_HARDIRQS, "hard")) | |
1534 | return 0; | |
1535 | #if STRICT_READ_CHECKS | |
1536 | /* | |
1537 | * just marked it hardirq-safe, check that this lock | |
1538 | * took no hardirq-unsafe-read lock in the past: | |
1539 | */ | |
1540 | if (!check_usage_forwards(curr, this, | |
1541 | LOCK_ENABLED_HARDIRQS_READ, "hard-read")) | |
1542 | return 0; | |
1543 | #endif | |
1544 | if (hardirq_verbose(this->class)) | |
1545 | ret = 2; | |
1546 | break; | |
1547 | case LOCK_USED_IN_SOFTIRQ: | |
1548 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS)) | |
1549 | return 0; | |
1550 | if (!valid_state(curr, this, new_bit, | |
1551 | LOCK_ENABLED_SOFTIRQS_READ)) | |
1552 | return 0; | |
1553 | /* | |
1554 | * just marked it softirq-safe, check that this lock | |
1555 | * took no softirq-unsafe lock in the past: | |
1556 | */ | |
1557 | if (!check_usage_forwards(curr, this, | |
1558 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
1559 | return 0; | |
1560 | #if STRICT_READ_CHECKS | |
1561 | /* | |
1562 | * just marked it softirq-safe, check that this lock | |
1563 | * took no softirq-unsafe-read lock in the past: | |
1564 | */ | |
1565 | if (!check_usage_forwards(curr, this, | |
1566 | LOCK_ENABLED_SOFTIRQS_READ, "soft-read")) | |
1567 | return 0; | |
1568 | #endif | |
1569 | if (softirq_verbose(this->class)) | |
1570 | ret = 2; | |
1571 | break; | |
1572 | case LOCK_USED_IN_HARDIRQ_READ: | |
1573 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS)) | |
1574 | return 0; | |
1575 | /* | |
1576 | * just marked it hardirq-read-safe, check that this lock | |
1577 | * took no hardirq-unsafe lock in the past: | |
1578 | */ | |
1579 | if (!check_usage_forwards(curr, this, | |
1580 | LOCK_ENABLED_HARDIRQS, "hard")) | |
1581 | return 0; | |
1582 | if (hardirq_verbose(this->class)) | |
1583 | ret = 2; | |
1584 | break; | |
1585 | case LOCK_USED_IN_SOFTIRQ_READ: | |
1586 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS)) | |
1587 | return 0; | |
1588 | /* | |
1589 | * just marked it softirq-read-safe, check that this lock | |
1590 | * took no softirq-unsafe lock in the past: | |
1591 | */ | |
1592 | if (!check_usage_forwards(curr, this, | |
1593 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
1594 | return 0; | |
1595 | if (softirq_verbose(this->class)) | |
1596 | ret = 2; | |
1597 | break; | |
1598 | case LOCK_ENABLED_HARDIRQS: | |
1599 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ)) | |
1600 | return 0; | |
1601 | if (!valid_state(curr, this, new_bit, | |
1602 | LOCK_USED_IN_HARDIRQ_READ)) | |
1603 | return 0; | |
1604 | /* | |
1605 | * just marked it hardirq-unsafe, check that no hardirq-safe | |
1606 | * lock in the system ever took it in the past: | |
1607 | */ | |
1608 | if (!check_usage_backwards(curr, this, | |
1609 | LOCK_USED_IN_HARDIRQ, "hard")) | |
1610 | return 0; | |
1611 | #if STRICT_READ_CHECKS | |
1612 | /* | |
1613 | * just marked it hardirq-unsafe, check that no | |
1614 | * hardirq-safe-read lock in the system ever took | |
1615 | * it in the past: | |
1616 | */ | |
1617 | if (!check_usage_backwards(curr, this, | |
1618 | LOCK_USED_IN_HARDIRQ_READ, "hard-read")) | |
1619 | return 0; | |
1620 | #endif | |
1621 | if (hardirq_verbose(this->class)) | |
1622 | ret = 2; | |
1623 | break; | |
1624 | case LOCK_ENABLED_SOFTIRQS: | |
1625 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ)) | |
1626 | return 0; | |
1627 | if (!valid_state(curr, this, new_bit, | |
1628 | LOCK_USED_IN_SOFTIRQ_READ)) | |
1629 | return 0; | |
1630 | /* | |
1631 | * just marked it softirq-unsafe, check that no softirq-safe | |
1632 | * lock in the system ever took it in the past: | |
1633 | */ | |
1634 | if (!check_usage_backwards(curr, this, | |
1635 | LOCK_USED_IN_SOFTIRQ, "soft")) | |
1636 | return 0; | |
1637 | #if STRICT_READ_CHECKS | |
1638 | /* | |
1639 | * just marked it softirq-unsafe, check that no | |
1640 | * softirq-safe-read lock in the system ever took | |
1641 | * it in the past: | |
1642 | */ | |
1643 | if (!check_usage_backwards(curr, this, | |
1644 | LOCK_USED_IN_SOFTIRQ_READ, "soft-read")) | |
1645 | return 0; | |
1646 | #endif | |
1647 | if (softirq_verbose(this->class)) | |
1648 | ret = 2; | |
1649 | break; | |
1650 | case LOCK_ENABLED_HARDIRQS_READ: | |
1651 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ)) | |
1652 | return 0; | |
1653 | #if STRICT_READ_CHECKS | |
1654 | /* | |
1655 | * just marked it hardirq-read-unsafe, check that no | |
1656 | * hardirq-safe lock in the system ever took it in the past: | |
1657 | */ | |
1658 | if (!check_usage_backwards(curr, this, | |
1659 | LOCK_USED_IN_HARDIRQ, "hard")) | |
1660 | return 0; | |
1661 | #endif | |
1662 | if (hardirq_verbose(this->class)) | |
1663 | ret = 2; | |
1664 | break; | |
1665 | case LOCK_ENABLED_SOFTIRQS_READ: | |
1666 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ)) | |
1667 | return 0; | |
1668 | #if STRICT_READ_CHECKS | |
1669 | /* | |
1670 | * just marked it softirq-read-unsafe, check that no | |
1671 | * softirq-safe lock in the system ever took it in the past: | |
1672 | */ | |
1673 | if (!check_usage_backwards(curr, this, | |
1674 | LOCK_USED_IN_SOFTIRQ, "soft")) | |
1675 | return 0; | |
1676 | #endif | |
1677 | if (softirq_verbose(this->class)) | |
1678 | ret = 2; | |
1679 | break; | |
1680 | #endif | |
1681 | case LOCK_USED: | |
1682 | /* | |
1683 | * Add it to the global list of classes: | |
1684 | */ | |
1685 | list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes); | |
1686 | debug_atomic_dec(&nr_unused_locks); | |
1687 | break; | |
1688 | default: | |
1689 | debug_locks_off(); | |
1690 | WARN_ON(1); | |
1691 | return 0; | |
1692 | } | |
1693 | ||
1694 | __raw_spin_unlock(&hash_lock); | |
1695 | ||
1696 | /* | |
1697 | * We must printk outside of the hash_lock: | |
1698 | */ | |
1699 | if (ret == 2) { | |
1700 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); | |
1701 | print_lock(this); | |
1702 | print_irqtrace_events(curr); | |
1703 | dump_stack(); | |
1704 | } | |
1705 | ||
1706 | return ret; | |
1707 | } | |
1708 | ||
1709 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1710 | /* | |
1711 | * Mark all held locks with a usage bit: | |
1712 | */ | |
1713 | static int | |
1714 | mark_held_locks(struct task_struct *curr, int hardirq, unsigned long ip) | |
1715 | { | |
1716 | enum lock_usage_bit usage_bit; | |
1717 | struct held_lock *hlock; | |
1718 | int i; | |
1719 | ||
1720 | for (i = 0; i < curr->lockdep_depth; i++) { | |
1721 | hlock = curr->held_locks + i; | |
1722 | ||
1723 | if (hardirq) { | |
1724 | if (hlock->read) | |
1725 | usage_bit = LOCK_ENABLED_HARDIRQS_READ; | |
1726 | else | |
1727 | usage_bit = LOCK_ENABLED_HARDIRQS; | |
1728 | } else { | |
1729 | if (hlock->read) | |
1730 | usage_bit = LOCK_ENABLED_SOFTIRQS_READ; | |
1731 | else | |
1732 | usage_bit = LOCK_ENABLED_SOFTIRQS; | |
1733 | } | |
1734 | if (!mark_lock(curr, hlock, usage_bit, ip)) | |
1735 | return 0; | |
1736 | } | |
1737 | ||
1738 | return 1; | |
1739 | } | |
1740 | ||
1741 | /* | |
1742 | * Debugging helper: via this flag we know that we are in | |
1743 | * 'early bootup code', and will warn about any invalid irqs-on event: | |
1744 | */ | |
1745 | static int early_boot_irqs_enabled; | |
1746 | ||
1747 | void early_boot_irqs_off(void) | |
1748 | { | |
1749 | early_boot_irqs_enabled = 0; | |
1750 | } | |
1751 | ||
1752 | void early_boot_irqs_on(void) | |
1753 | { | |
1754 | early_boot_irqs_enabled = 1; | |
1755 | } | |
1756 | ||
1757 | /* | |
1758 | * Hardirqs will be enabled: | |
1759 | */ | |
1760 | void trace_hardirqs_on(void) | |
1761 | { | |
1762 | struct task_struct *curr = current; | |
1763 | unsigned long ip; | |
1764 | ||
1765 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
1766 | return; | |
1767 | ||
1768 | if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled))) | |
1769 | return; | |
1770 | ||
1771 | if (unlikely(curr->hardirqs_enabled)) { | |
1772 | debug_atomic_inc(&redundant_hardirqs_on); | |
1773 | return; | |
1774 | } | |
1775 | /* we'll do an OFF -> ON transition: */ | |
1776 | curr->hardirqs_enabled = 1; | |
1777 | ip = (unsigned long) __builtin_return_address(0); | |
1778 | ||
1779 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1780 | return; | |
1781 | if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) | |
1782 | return; | |
1783 | /* | |
1784 | * We are going to turn hardirqs on, so set the | |
1785 | * usage bit for all held locks: | |
1786 | */ | |
1787 | if (!mark_held_locks(curr, 1, ip)) | |
1788 | return; | |
1789 | /* | |
1790 | * If we have softirqs enabled, then set the usage | |
1791 | * bit for all held locks. (disabled hardirqs prevented | |
1792 | * this bit from being set before) | |
1793 | */ | |
1794 | if (curr->softirqs_enabled) | |
1795 | if (!mark_held_locks(curr, 0, ip)) | |
1796 | return; | |
1797 | ||
1798 | curr->hardirq_enable_ip = ip; | |
1799 | curr->hardirq_enable_event = ++curr->irq_events; | |
1800 | debug_atomic_inc(&hardirqs_on_events); | |
1801 | } | |
1802 | ||
1803 | EXPORT_SYMBOL(trace_hardirqs_on); | |
1804 | ||
1805 | /* | |
1806 | * Hardirqs were disabled: | |
1807 | */ | |
1808 | void trace_hardirqs_off(void) | |
1809 | { | |
1810 | struct task_struct *curr = current; | |
1811 | ||
1812 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
1813 | return; | |
1814 | ||
1815 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1816 | return; | |
1817 | ||
1818 | if (curr->hardirqs_enabled) { | |
1819 | /* | |
1820 | * We have done an ON -> OFF transition: | |
1821 | */ | |
1822 | curr->hardirqs_enabled = 0; | |
1823 | curr->hardirq_disable_ip = _RET_IP_; | |
1824 | curr->hardirq_disable_event = ++curr->irq_events; | |
1825 | debug_atomic_inc(&hardirqs_off_events); | |
1826 | } else | |
1827 | debug_atomic_inc(&redundant_hardirqs_off); | |
1828 | } | |
1829 | ||
1830 | EXPORT_SYMBOL(trace_hardirqs_off); | |
1831 | ||
1832 | /* | |
1833 | * Softirqs will be enabled: | |
1834 | */ | |
1835 | void trace_softirqs_on(unsigned long ip) | |
1836 | { | |
1837 | struct task_struct *curr = current; | |
1838 | ||
1839 | if (unlikely(!debug_locks)) | |
1840 | return; | |
1841 | ||
1842 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1843 | return; | |
1844 | ||
1845 | if (curr->softirqs_enabled) { | |
1846 | debug_atomic_inc(&redundant_softirqs_on); | |
1847 | return; | |
1848 | } | |
1849 | ||
1850 | /* | |
1851 | * We'll do an OFF -> ON transition: | |
1852 | */ | |
1853 | curr->softirqs_enabled = 1; | |
1854 | curr->softirq_enable_ip = ip; | |
1855 | curr->softirq_enable_event = ++curr->irq_events; | |
1856 | debug_atomic_inc(&softirqs_on_events); | |
1857 | /* | |
1858 | * We are going to turn softirqs on, so set the | |
1859 | * usage bit for all held locks, if hardirqs are | |
1860 | * enabled too: | |
1861 | */ | |
1862 | if (curr->hardirqs_enabled) | |
1863 | mark_held_locks(curr, 0, ip); | |
1864 | } | |
1865 | ||
1866 | /* | |
1867 | * Softirqs were disabled: | |
1868 | */ | |
1869 | void trace_softirqs_off(unsigned long ip) | |
1870 | { | |
1871 | struct task_struct *curr = current; | |
1872 | ||
1873 | if (unlikely(!debug_locks)) | |
1874 | return; | |
1875 | ||
1876 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1877 | return; | |
1878 | ||
1879 | if (curr->softirqs_enabled) { | |
1880 | /* | |
1881 | * We have done an ON -> OFF transition: | |
1882 | */ | |
1883 | curr->softirqs_enabled = 0; | |
1884 | curr->softirq_disable_ip = ip; | |
1885 | curr->softirq_disable_event = ++curr->irq_events; | |
1886 | debug_atomic_inc(&softirqs_off_events); | |
1887 | DEBUG_LOCKS_WARN_ON(!softirq_count()); | |
1888 | } else | |
1889 | debug_atomic_inc(&redundant_softirqs_off); | |
1890 | } | |
1891 | ||
1892 | #endif | |
1893 | ||
1894 | /* | |
1895 | * Initialize a lock instance's lock-class mapping info: | |
1896 | */ | |
1897 | void lockdep_init_map(struct lockdep_map *lock, const char *name, | |
1898 | struct lock_class_key *key) | |
1899 | { | |
1900 | if (unlikely(!debug_locks)) | |
1901 | return; | |
1902 | ||
1903 | if (DEBUG_LOCKS_WARN_ON(!key)) | |
1904 | return; | |
1905 | if (DEBUG_LOCKS_WARN_ON(!name)) | |
1906 | return; | |
1907 | /* | |
1908 | * Sanity check, the lock-class key must be persistent: | |
1909 | */ | |
1910 | if (!static_obj(key)) { | |
1911 | printk("BUG: key %p not in .data!\n", key); | |
1912 | DEBUG_LOCKS_WARN_ON(1); | |
1913 | return; | |
1914 | } | |
1915 | lock->name = name; | |
1916 | lock->key = key; | |
1917 | memset(lock->class, 0, sizeof(lock->class[0])*MAX_LOCKDEP_SUBCLASSES); | |
1918 | } | |
1919 | ||
1920 | EXPORT_SYMBOL_GPL(lockdep_init_map); | |
1921 | ||
1922 | /* | |
1923 | * This gets called for every mutex_lock*()/spin_lock*() operation. | |
1924 | * We maintain the dependency maps and validate the locking attempt: | |
1925 | */ | |
1926 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
1927 | int trylock, int read, int check, int hardirqs_off, | |
1928 | unsigned long ip) | |
1929 | { | |
1930 | struct task_struct *curr = current; | |
1931 | struct held_lock *hlock; | |
1932 | struct lock_class *class; | |
1933 | unsigned int depth, id; | |
1934 | int chain_head = 0; | |
1935 | u64 chain_key; | |
1936 | ||
1937 | if (unlikely(!debug_locks)) | |
1938 | return 0; | |
1939 | ||
1940 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1941 | return 0; | |
1942 | ||
1943 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { | |
1944 | debug_locks_off(); | |
1945 | printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n"); | |
1946 | printk("turning off the locking correctness validator.\n"); | |
1947 | return 0; | |
1948 | } | |
1949 | ||
1950 | class = lock->class[subclass]; | |
1951 | /* not cached yet? */ | |
1952 | if (unlikely(!class)) { | |
1953 | class = register_lock_class(lock, subclass); | |
1954 | if (!class) | |
1955 | return 0; | |
1956 | } | |
1957 | debug_atomic_inc((atomic_t *)&class->ops); | |
1958 | if (very_verbose(class)) { | |
1959 | printk("\nacquire class [%p] %s", class->key, class->name); | |
1960 | if (class->name_version > 1) | |
1961 | printk("#%d", class->name_version); | |
1962 | printk("\n"); | |
1963 | dump_stack(); | |
1964 | } | |
1965 | ||
1966 | /* | |
1967 | * Add the lock to the list of currently held locks. | |
1968 | * (we dont increase the depth just yet, up until the | |
1969 | * dependency checks are done) | |
1970 | */ | |
1971 | depth = curr->lockdep_depth; | |
1972 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) | |
1973 | return 0; | |
1974 | ||
1975 | hlock = curr->held_locks + depth; | |
1976 | ||
1977 | hlock->class = class; | |
1978 | hlock->acquire_ip = ip; | |
1979 | hlock->instance = lock; | |
1980 | hlock->trylock = trylock; | |
1981 | hlock->read = read; | |
1982 | hlock->check = check; | |
1983 | hlock->hardirqs_off = hardirqs_off; | |
1984 | ||
1985 | if (check != 2) | |
1986 | goto out_calc_hash; | |
1987 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1988 | /* | |
1989 | * If non-trylock use in a hardirq or softirq context, then | |
1990 | * mark the lock as used in these contexts: | |
1991 | */ | |
1992 | if (!trylock) { | |
1993 | if (read) { | |
1994 | if (curr->hardirq_context) | |
1995 | if (!mark_lock(curr, hlock, | |
1996 | LOCK_USED_IN_HARDIRQ_READ, ip)) | |
1997 | return 0; | |
1998 | if (curr->softirq_context) | |
1999 | if (!mark_lock(curr, hlock, | |
2000 | LOCK_USED_IN_SOFTIRQ_READ, ip)) | |
2001 | return 0; | |
2002 | } else { | |
2003 | if (curr->hardirq_context) | |
2004 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ, ip)) | |
2005 | return 0; | |
2006 | if (curr->softirq_context) | |
2007 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ, ip)) | |
2008 | return 0; | |
2009 | } | |
2010 | } | |
2011 | if (!hardirqs_off) { | |
2012 | if (read) { | |
2013 | if (!mark_lock(curr, hlock, | |
2014 | LOCK_ENABLED_HARDIRQS_READ, ip)) | |
2015 | return 0; | |
2016 | if (curr->softirqs_enabled) | |
2017 | if (!mark_lock(curr, hlock, | |
2018 | LOCK_ENABLED_SOFTIRQS_READ, ip)) | |
2019 | return 0; | |
2020 | } else { | |
2021 | if (!mark_lock(curr, hlock, | |
2022 | LOCK_ENABLED_HARDIRQS, ip)) | |
2023 | return 0; | |
2024 | if (curr->softirqs_enabled) | |
2025 | if (!mark_lock(curr, hlock, | |
2026 | LOCK_ENABLED_SOFTIRQS, ip)) | |
2027 | return 0; | |
2028 | } | |
2029 | } | |
2030 | #endif | |
2031 | /* mark it as used: */ | |
2032 | if (!mark_lock(curr, hlock, LOCK_USED, ip)) | |
2033 | return 0; | |
2034 | out_calc_hash: | |
2035 | /* | |
2036 | * Calculate the chain hash: it's the combined has of all the | |
2037 | * lock keys along the dependency chain. We save the hash value | |
2038 | * at every step so that we can get the current hash easily | |
2039 | * after unlock. The chain hash is then used to cache dependency | |
2040 | * results. | |
2041 | * | |
2042 | * The 'key ID' is what is the most compact key value to drive | |
2043 | * the hash, not class->key. | |
2044 | */ | |
2045 | id = class - lock_classes; | |
2046 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) | |
2047 | return 0; | |
2048 | ||
2049 | chain_key = curr->curr_chain_key; | |
2050 | if (!depth) { | |
2051 | if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) | |
2052 | return 0; | |
2053 | chain_head = 1; | |
2054 | } | |
2055 | ||
2056 | hlock->prev_chain_key = chain_key; | |
2057 | ||
2058 | #ifdef CONFIG_TRACE_IRQFLAGS | |
2059 | /* | |
2060 | * Keep track of points where we cross into an interrupt context: | |
2061 | */ | |
2062 | hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) + | |
2063 | curr->softirq_context; | |
2064 | if (depth) { | |
2065 | struct held_lock *prev_hlock; | |
2066 | ||
2067 | prev_hlock = curr->held_locks + depth-1; | |
2068 | /* | |
2069 | * If we cross into another context, reset the | |
2070 | * hash key (this also prevents the checking and the | |
2071 | * adding of the dependency to 'prev'): | |
2072 | */ | |
2073 | if (prev_hlock->irq_context != hlock->irq_context) { | |
2074 | chain_key = 0; | |
2075 | chain_head = 1; | |
2076 | } | |
2077 | } | |
2078 | #endif | |
2079 | chain_key = iterate_chain_key(chain_key, id); | |
2080 | curr->curr_chain_key = chain_key; | |
2081 | ||
2082 | /* | |
2083 | * Trylock needs to maintain the stack of held locks, but it | |
2084 | * does not add new dependencies, because trylock can be done | |
2085 | * in any order. | |
2086 | * | |
2087 | * We look up the chain_key and do the O(N^2) check and update of | |
2088 | * the dependencies only if this is a new dependency chain. | |
2089 | * (If lookup_chain_cache() returns with 1 it acquires | |
2090 | * hash_lock for us) | |
2091 | */ | |
2092 | if (!trylock && (check == 2) && lookup_chain_cache(chain_key)) { | |
2093 | /* | |
2094 | * Check whether last held lock: | |
2095 | * | |
2096 | * - is irq-safe, if this lock is irq-unsafe | |
2097 | * - is softirq-safe, if this lock is hardirq-unsafe | |
2098 | * | |
2099 | * And check whether the new lock's dependency graph | |
2100 | * could lead back to the previous lock. | |
2101 | * | |
2102 | * any of these scenarios could lead to a deadlock. If | |
2103 | * All validations | |
2104 | */ | |
2105 | int ret = check_deadlock(curr, hlock, lock, read); | |
2106 | ||
2107 | if (!ret) | |
2108 | return 0; | |
2109 | /* | |
2110 | * Mark recursive read, as we jump over it when | |
2111 | * building dependencies (just like we jump over | |
2112 | * trylock entries): | |
2113 | */ | |
2114 | if (ret == 2) | |
2115 | hlock->read = 2; | |
2116 | /* | |
2117 | * Add dependency only if this lock is not the head | |
2118 | * of the chain, and if it's not a secondary read-lock: | |
2119 | */ | |
2120 | if (!chain_head && ret != 2) | |
2121 | if (!check_prevs_add(curr, hlock)) | |
2122 | return 0; | |
2123 | __raw_spin_unlock(&hash_lock); | |
2124 | } | |
2125 | curr->lockdep_depth++; | |
2126 | check_chain_key(curr); | |
2127 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { | |
2128 | debug_locks_off(); | |
2129 | printk("BUG: MAX_LOCK_DEPTH too low!\n"); | |
2130 | printk("turning off the locking correctness validator.\n"); | |
2131 | return 0; | |
2132 | } | |
2133 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) | |
2134 | max_lockdep_depth = curr->lockdep_depth; | |
2135 | ||
2136 | return 1; | |
2137 | } | |
2138 | ||
2139 | static int | |
2140 | print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock, | |
2141 | unsigned long ip) | |
2142 | { | |
2143 | if (!debug_locks_off()) | |
2144 | return 0; | |
2145 | if (debug_locks_silent) | |
2146 | return 0; | |
2147 | ||
2148 | printk("\n=====================================\n"); | |
2149 | printk( "[ BUG: bad unlock balance detected! ]\n"); | |
2150 | printk( "-------------------------------------\n"); | |
2151 | printk("%s/%d is trying to release lock (", | |
2152 | curr->comm, curr->pid); | |
2153 | print_lockdep_cache(lock); | |
2154 | printk(") at:\n"); | |
2155 | print_ip_sym(ip); | |
2156 | printk("but there are no more locks to release!\n"); | |
2157 | printk("\nother info that might help us debug this:\n"); | |
2158 | lockdep_print_held_locks(curr); | |
2159 | ||
2160 | printk("\nstack backtrace:\n"); | |
2161 | dump_stack(); | |
2162 | ||
2163 | return 0; | |
2164 | } | |
2165 | ||
2166 | /* | |
2167 | * Common debugging checks for both nested and non-nested unlock: | |
2168 | */ | |
2169 | static int check_unlock(struct task_struct *curr, struct lockdep_map *lock, | |
2170 | unsigned long ip) | |
2171 | { | |
2172 | if (unlikely(!debug_locks)) | |
2173 | return 0; | |
2174 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
2175 | return 0; | |
2176 | ||
2177 | if (curr->lockdep_depth <= 0) | |
2178 | return print_unlock_inbalance_bug(curr, lock, ip); | |
2179 | ||
2180 | return 1; | |
2181 | } | |
2182 | ||
2183 | /* | |
2184 | * Remove the lock to the list of currently held locks in a | |
2185 | * potentially non-nested (out of order) manner. This is a | |
2186 | * relatively rare operation, as all the unlock APIs default | |
2187 | * to nested mode (which uses lock_release()): | |
2188 | */ | |
2189 | static int | |
2190 | lock_release_non_nested(struct task_struct *curr, | |
2191 | struct lockdep_map *lock, unsigned long ip) | |
2192 | { | |
2193 | struct held_lock *hlock, *prev_hlock; | |
2194 | unsigned int depth; | |
2195 | int i; | |
2196 | ||
2197 | /* | |
2198 | * Check whether the lock exists in the current stack | |
2199 | * of held locks: | |
2200 | */ | |
2201 | depth = curr->lockdep_depth; | |
2202 | if (DEBUG_LOCKS_WARN_ON(!depth)) | |
2203 | return 0; | |
2204 | ||
2205 | prev_hlock = NULL; | |
2206 | for (i = depth-1; i >= 0; i--) { | |
2207 | hlock = curr->held_locks + i; | |
2208 | /* | |
2209 | * We must not cross into another context: | |
2210 | */ | |
2211 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) | |
2212 | break; | |
2213 | if (hlock->instance == lock) | |
2214 | goto found_it; | |
2215 | prev_hlock = hlock; | |
2216 | } | |
2217 | return print_unlock_inbalance_bug(curr, lock, ip); | |
2218 | ||
2219 | found_it: | |
2220 | /* | |
2221 | * We have the right lock to unlock, 'hlock' points to it. | |
2222 | * Now we remove it from the stack, and add back the other | |
2223 | * entries (if any), recalculating the hash along the way: | |
2224 | */ | |
2225 | curr->lockdep_depth = i; | |
2226 | curr->curr_chain_key = hlock->prev_chain_key; | |
2227 | ||
2228 | for (i++; i < depth; i++) { | |
2229 | hlock = curr->held_locks + i; | |
2230 | if (!__lock_acquire(hlock->instance, | |
2231 | hlock->class->subclass, hlock->trylock, | |
2232 | hlock->read, hlock->check, hlock->hardirqs_off, | |
2233 | hlock->acquire_ip)) | |
2234 | return 0; | |
2235 | } | |
2236 | ||
2237 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) | |
2238 | return 0; | |
2239 | return 1; | |
2240 | } | |
2241 | ||
2242 | /* | |
2243 | * Remove the lock to the list of currently held locks - this gets | |
2244 | * called on mutex_unlock()/spin_unlock*() (or on a failed | |
2245 | * mutex_lock_interruptible()). This is done for unlocks that nest | |
2246 | * perfectly. (i.e. the current top of the lock-stack is unlocked) | |
2247 | */ | |
2248 | static int lock_release_nested(struct task_struct *curr, | |
2249 | struct lockdep_map *lock, unsigned long ip) | |
2250 | { | |
2251 | struct held_lock *hlock; | |
2252 | unsigned int depth; | |
2253 | ||
2254 | /* | |
2255 | * Pop off the top of the lock stack: | |
2256 | */ | |
2257 | depth = curr->lockdep_depth - 1; | |
2258 | hlock = curr->held_locks + depth; | |
2259 | ||
2260 | /* | |
2261 | * Is the unlock non-nested: | |
2262 | */ | |
2263 | if (hlock->instance != lock) | |
2264 | return lock_release_non_nested(curr, lock, ip); | |
2265 | curr->lockdep_depth--; | |
2266 | ||
2267 | if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0))) | |
2268 | return 0; | |
2269 | ||
2270 | curr->curr_chain_key = hlock->prev_chain_key; | |
2271 | ||
2272 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2273 | hlock->prev_chain_key = 0; | |
2274 | hlock->class = NULL; | |
2275 | hlock->acquire_ip = 0; | |
2276 | hlock->irq_context = 0; | |
2277 | #endif | |
2278 | return 1; | |
2279 | } | |
2280 | ||
2281 | /* | |
2282 | * Remove the lock to the list of currently held locks - this gets | |
2283 | * called on mutex_unlock()/spin_unlock*() (or on a failed | |
2284 | * mutex_lock_interruptible()). This is done for unlocks that nest | |
2285 | * perfectly. (i.e. the current top of the lock-stack is unlocked) | |
2286 | */ | |
2287 | static void | |
2288 | __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) | |
2289 | { | |
2290 | struct task_struct *curr = current; | |
2291 | ||
2292 | if (!check_unlock(curr, lock, ip)) | |
2293 | return; | |
2294 | ||
2295 | if (nested) { | |
2296 | if (!lock_release_nested(curr, lock, ip)) | |
2297 | return; | |
2298 | } else { | |
2299 | if (!lock_release_non_nested(curr, lock, ip)) | |
2300 | return; | |
2301 | } | |
2302 | ||
2303 | check_chain_key(curr); | |
2304 | } | |
2305 | ||
2306 | /* | |
2307 | * Check whether we follow the irq-flags state precisely: | |
2308 | */ | |
2309 | static void check_flags(unsigned long flags) | |
2310 | { | |
2311 | #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS) | |
2312 | if (!debug_locks) | |
2313 | return; | |
2314 | ||
2315 | if (irqs_disabled_flags(flags)) | |
2316 | DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled); | |
2317 | else | |
2318 | DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled); | |
2319 | ||
2320 | /* | |
2321 | * We dont accurately track softirq state in e.g. | |
2322 | * hardirq contexts (such as on 4KSTACKS), so only | |
2323 | * check if not in hardirq contexts: | |
2324 | */ | |
2325 | if (!hardirq_count()) { | |
2326 | if (softirq_count()) | |
2327 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); | |
2328 | else | |
2329 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); | |
2330 | } | |
2331 | ||
2332 | if (!debug_locks) | |
2333 | print_irqtrace_events(current); | |
2334 | #endif | |
2335 | } | |
2336 | ||
2337 | /* | |
2338 | * We are not always called with irqs disabled - do that here, | |
2339 | * and also avoid lockdep recursion: | |
2340 | */ | |
2341 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
2342 | int trylock, int read, int check, unsigned long ip) | |
2343 | { | |
2344 | unsigned long flags; | |
2345 | ||
2346 | if (unlikely(current->lockdep_recursion)) | |
2347 | return; | |
2348 | ||
2349 | raw_local_irq_save(flags); | |
2350 | check_flags(flags); | |
2351 | ||
2352 | current->lockdep_recursion = 1; | |
2353 | __lock_acquire(lock, subclass, trylock, read, check, | |
2354 | irqs_disabled_flags(flags), ip); | |
2355 | current->lockdep_recursion = 0; | |
2356 | raw_local_irq_restore(flags); | |
2357 | } | |
2358 | ||
2359 | EXPORT_SYMBOL_GPL(lock_acquire); | |
2360 | ||
2361 | void lock_release(struct lockdep_map *lock, int nested, unsigned long ip) | |
2362 | { | |
2363 | unsigned long flags; | |
2364 | ||
2365 | if (unlikely(current->lockdep_recursion)) | |
2366 | return; | |
2367 | ||
2368 | raw_local_irq_save(flags); | |
2369 | check_flags(flags); | |
2370 | current->lockdep_recursion = 1; | |
2371 | __lock_release(lock, nested, ip); | |
2372 | current->lockdep_recursion = 0; | |
2373 | raw_local_irq_restore(flags); | |
2374 | } | |
2375 | ||
2376 | EXPORT_SYMBOL_GPL(lock_release); | |
2377 | ||
2378 | /* | |
2379 | * Used by the testsuite, sanitize the validator state | |
2380 | * after a simulated failure: | |
2381 | */ | |
2382 | ||
2383 | void lockdep_reset(void) | |
2384 | { | |
2385 | unsigned long flags; | |
2386 | ||
2387 | raw_local_irq_save(flags); | |
2388 | current->curr_chain_key = 0; | |
2389 | current->lockdep_depth = 0; | |
2390 | current->lockdep_recursion = 0; | |
2391 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); | |
2392 | nr_hardirq_chains = 0; | |
2393 | nr_softirq_chains = 0; | |
2394 | nr_process_chains = 0; | |
2395 | debug_locks = 1; | |
2396 | raw_local_irq_restore(flags); | |
2397 | } | |
2398 | ||
2399 | static void zap_class(struct lock_class *class) | |
2400 | { | |
2401 | int i; | |
2402 | ||
2403 | /* | |
2404 | * Remove all dependencies this lock is | |
2405 | * involved in: | |
2406 | */ | |
2407 | for (i = 0; i < nr_list_entries; i++) { | |
2408 | if (list_entries[i].class == class) | |
2409 | list_del_rcu(&list_entries[i].entry); | |
2410 | } | |
2411 | /* | |
2412 | * Unhash the class and remove it from the all_lock_classes list: | |
2413 | */ | |
2414 | list_del_rcu(&class->hash_entry); | |
2415 | list_del_rcu(&class->lock_entry); | |
2416 | ||
2417 | } | |
2418 | ||
2419 | static inline int within(void *addr, void *start, unsigned long size) | |
2420 | { | |
2421 | return addr >= start && addr < start + size; | |
2422 | } | |
2423 | ||
2424 | void lockdep_free_key_range(void *start, unsigned long size) | |
2425 | { | |
2426 | struct lock_class *class, *next; | |
2427 | struct list_head *head; | |
2428 | unsigned long flags; | |
2429 | int i; | |
2430 | ||
2431 | raw_local_irq_save(flags); | |
2432 | __raw_spin_lock(&hash_lock); | |
2433 | ||
2434 | /* | |
2435 | * Unhash all classes that were created by this module: | |
2436 | */ | |
2437 | for (i = 0; i < CLASSHASH_SIZE; i++) { | |
2438 | head = classhash_table + i; | |
2439 | if (list_empty(head)) | |
2440 | continue; | |
2441 | list_for_each_entry_safe(class, next, head, hash_entry) | |
2442 | if (within(class->key, start, size)) | |
2443 | zap_class(class); | |
2444 | } | |
2445 | ||
2446 | __raw_spin_unlock(&hash_lock); | |
2447 | raw_local_irq_restore(flags); | |
2448 | } | |
2449 | ||
2450 | void lockdep_reset_lock(struct lockdep_map *lock) | |
2451 | { | |
2452 | struct lock_class *class, *next, *entry; | |
2453 | struct list_head *head; | |
2454 | unsigned long flags; | |
2455 | int i, j; | |
2456 | ||
2457 | raw_local_irq_save(flags); | |
2458 | __raw_spin_lock(&hash_lock); | |
2459 | ||
2460 | /* | |
2461 | * Remove all classes this lock has: | |
2462 | */ | |
2463 | for (i = 0; i < CLASSHASH_SIZE; i++) { | |
2464 | head = classhash_table + i; | |
2465 | if (list_empty(head)) | |
2466 | continue; | |
2467 | list_for_each_entry_safe(class, next, head, hash_entry) { | |
2468 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { | |
2469 | entry = lock->class[j]; | |
2470 | if (class == entry) { | |
2471 | zap_class(class); | |
2472 | lock->class[j] = NULL; | |
2473 | break; | |
2474 | } | |
2475 | } | |
2476 | } | |
2477 | } | |
2478 | ||
2479 | /* | |
2480 | * Debug check: in the end all mapped classes should | |
2481 | * be gone. | |
2482 | */ | |
2483 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { | |
2484 | entry = lock->class[j]; | |
2485 | if (!entry) | |
2486 | continue; | |
2487 | __raw_spin_unlock(&hash_lock); | |
2488 | DEBUG_LOCKS_WARN_ON(1); | |
2489 | raw_local_irq_restore(flags); | |
2490 | return; | |
2491 | } | |
2492 | ||
2493 | __raw_spin_unlock(&hash_lock); | |
2494 | raw_local_irq_restore(flags); | |
2495 | } | |
2496 | ||
2497 | void __init lockdep_init(void) | |
2498 | { | |
2499 | int i; | |
2500 | ||
2501 | /* | |
2502 | * Some architectures have their own start_kernel() | |
2503 | * code which calls lockdep_init(), while we also | |
2504 | * call lockdep_init() from the start_kernel() itself, | |
2505 | * and we want to initialize the hashes only once: | |
2506 | */ | |
2507 | if (lockdep_initialized) | |
2508 | return; | |
2509 | ||
2510 | for (i = 0; i < CLASSHASH_SIZE; i++) | |
2511 | INIT_LIST_HEAD(classhash_table + i); | |
2512 | ||
2513 | for (i = 0; i < CHAINHASH_SIZE; i++) | |
2514 | INIT_LIST_HEAD(chainhash_table + i); | |
2515 | ||
2516 | lockdep_initialized = 1; | |
2517 | } | |
2518 | ||
2519 | void __init lockdep_info(void) | |
2520 | { | |
2521 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); | |
2522 | ||
2523 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); | |
2524 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); | |
2525 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); | |
2526 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); | |
2527 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); | |
2528 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); | |
2529 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); | |
2530 | ||
2531 | printk(" memory used by lock dependency info: %lu kB\n", | |
2532 | (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + | |
2533 | sizeof(struct list_head) * CLASSHASH_SIZE + | |
2534 | sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + | |
2535 | sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + | |
2536 | sizeof(struct list_head) * CHAINHASH_SIZE) / 1024); | |
2537 | ||
2538 | printk(" per task-struct memory footprint: %lu bytes\n", | |
2539 | sizeof(struct held_lock) * MAX_LOCK_DEPTH); | |
2540 | ||
2541 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2542 | if (lockdep_init_error) | |
2543 | printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n"); | |
2544 | #endif | |
2545 | } | |
2546 | ||
2547 | static inline int in_range(const void *start, const void *addr, const void *end) | |
2548 | { | |
2549 | return addr >= start && addr <= end; | |
2550 | } | |
2551 | ||
2552 | static void | |
2553 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, | |
55794a41 | 2554 | const void *mem_to, struct held_lock *hlock) |
fbb9ce95 IM |
2555 | { |
2556 | if (!debug_locks_off()) | |
2557 | return; | |
2558 | if (debug_locks_silent) | |
2559 | return; | |
2560 | ||
2561 | printk("\n=========================\n"); | |
2562 | printk( "[ BUG: held lock freed! ]\n"); | |
2563 | printk( "-------------------------\n"); | |
2564 | printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", | |
2565 | curr->comm, curr->pid, mem_from, mem_to-1); | |
55794a41 | 2566 | print_lock(hlock); |
fbb9ce95 IM |
2567 | lockdep_print_held_locks(curr); |
2568 | ||
2569 | printk("\nstack backtrace:\n"); | |
2570 | dump_stack(); | |
2571 | } | |
2572 | ||
2573 | /* | |
2574 | * Called when kernel memory is freed (or unmapped), or if a lock | |
2575 | * is destroyed or reinitialized - this code checks whether there is | |
2576 | * any held lock in the memory range of <from> to <to>: | |
2577 | */ | |
2578 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) | |
2579 | { | |
2580 | const void *mem_to = mem_from + mem_len, *lock_from, *lock_to; | |
2581 | struct task_struct *curr = current; | |
2582 | struct held_lock *hlock; | |
2583 | unsigned long flags; | |
2584 | int i; | |
2585 | ||
2586 | if (unlikely(!debug_locks)) | |
2587 | return; | |
2588 | ||
2589 | local_irq_save(flags); | |
2590 | for (i = 0; i < curr->lockdep_depth; i++) { | |
2591 | hlock = curr->held_locks + i; | |
2592 | ||
2593 | lock_from = (void *)hlock->instance; | |
2594 | lock_to = (void *)(hlock->instance + 1); | |
2595 | ||
2596 | if (!in_range(mem_from, lock_from, mem_to) && | |
2597 | !in_range(mem_from, lock_to, mem_to)) | |
2598 | continue; | |
2599 | ||
55794a41 | 2600 | print_freed_lock_bug(curr, mem_from, mem_to, hlock); |
fbb9ce95 IM |
2601 | break; |
2602 | } | |
2603 | local_irq_restore(flags); | |
2604 | } | |
2605 | ||
2606 | static void print_held_locks_bug(struct task_struct *curr) | |
2607 | { | |
2608 | if (!debug_locks_off()) | |
2609 | return; | |
2610 | if (debug_locks_silent) | |
2611 | return; | |
2612 | ||
2613 | printk("\n=====================================\n"); | |
2614 | printk( "[ BUG: lock held at task exit time! ]\n"); | |
2615 | printk( "-------------------------------------\n"); | |
2616 | printk("%s/%d is exiting with locks still held!\n", | |
2617 | curr->comm, curr->pid); | |
2618 | lockdep_print_held_locks(curr); | |
2619 | ||
2620 | printk("\nstack backtrace:\n"); | |
2621 | dump_stack(); | |
2622 | } | |
2623 | ||
2624 | void debug_check_no_locks_held(struct task_struct *task) | |
2625 | { | |
2626 | if (unlikely(task->lockdep_depth > 0)) | |
2627 | print_held_locks_bug(task); | |
2628 | } | |
2629 | ||
2630 | void debug_show_all_locks(void) | |
2631 | { | |
2632 | struct task_struct *g, *p; | |
2633 | int count = 10; | |
2634 | int unlock = 1; | |
2635 | ||
2636 | printk("\nShowing all locks held in the system:\n"); | |
2637 | ||
2638 | /* | |
2639 | * Here we try to get the tasklist_lock as hard as possible, | |
2640 | * if not successful after 2 seconds we ignore it (but keep | |
2641 | * trying). This is to enable a debug printout even if a | |
2642 | * tasklist_lock-holding task deadlocks or crashes. | |
2643 | */ | |
2644 | retry: | |
2645 | if (!read_trylock(&tasklist_lock)) { | |
2646 | if (count == 10) | |
2647 | printk("hm, tasklist_lock locked, retrying... "); | |
2648 | if (count) { | |
2649 | count--; | |
2650 | printk(" #%d", 10-count); | |
2651 | mdelay(200); | |
2652 | goto retry; | |
2653 | } | |
2654 | printk(" ignoring it.\n"); | |
2655 | unlock = 0; | |
2656 | } | |
2657 | if (count != 10) | |
2658 | printk(" locked it.\n"); | |
2659 | ||
2660 | do_each_thread(g, p) { | |
2661 | if (p->lockdep_depth) | |
2662 | lockdep_print_held_locks(p); | |
2663 | if (!unlock) | |
2664 | if (read_trylock(&tasklist_lock)) | |
2665 | unlock = 1; | |
2666 | } while_each_thread(g, p); | |
2667 | ||
2668 | printk("\n"); | |
2669 | printk("=============================================\n\n"); | |
2670 | ||
2671 | if (unlock) | |
2672 | read_unlock(&tasklist_lock); | |
2673 | } | |
2674 | ||
2675 | EXPORT_SYMBOL_GPL(debug_show_all_locks); | |
2676 | ||
2677 | void debug_show_held_locks(struct task_struct *task) | |
2678 | { | |
2679 | lockdep_print_held_locks(task); | |
2680 | } | |
2681 | ||
2682 | EXPORT_SYMBOL_GPL(debug_show_held_locks); | |
2683 |