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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> | |
99de055a | 39 | #include <linux/utsname.h> |
fbb9ce95 IM |
40 | |
41 | #include <asm/sections.h> | |
42 | ||
43 | #include "lockdep_internals.h" | |
44 | ||
45 | /* | |
46 | * hash_lock: protects the lockdep hashes and class/list/hash allocators. | |
47 | * | |
48 | * This is one of the rare exceptions where it's justified | |
49 | * to use a raw spinlock - we really dont want the spinlock | |
50 | * code to recurse back into the lockdep code. | |
51 | */ | |
52 | static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; | |
53 | ||
54 | static int lockdep_initialized; | |
55 | ||
56 | unsigned long nr_list_entries; | |
57 | static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; | |
58 | ||
59 | /* | |
60 | * Allocate a lockdep entry. (assumes hash_lock held, returns | |
61 | * with NULL on failure) | |
62 | */ | |
63 | static struct lock_list *alloc_list_entry(void) | |
64 | { | |
65 | if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { | |
66 | __raw_spin_unlock(&hash_lock); | |
67 | debug_locks_off(); | |
68 | printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n"); | |
69 | printk("turning off the locking correctness validator.\n"); | |
70 | return NULL; | |
71 | } | |
72 | return list_entries + nr_list_entries++; | |
73 | } | |
74 | ||
75 | /* | |
76 | * All data structures here are protected by the global debug_lock. | |
77 | * | |
78 | * Mutex key structs only get allocated, once during bootup, and never | |
79 | * get freed - this significantly simplifies the debugging code. | |
80 | */ | |
81 | unsigned long nr_lock_classes; | |
82 | static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; | |
83 | ||
84 | /* | |
85 | * We keep a global list of all lock classes. The list only grows, | |
86 | * never shrinks. The list is only accessed with the lockdep | |
87 | * spinlock lock held. | |
88 | */ | |
89 | LIST_HEAD(all_lock_classes); | |
90 | ||
91 | /* | |
92 | * The lockdep classes are in a hash-table as well, for fast lookup: | |
93 | */ | |
94 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) | |
95 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) | |
96 | #define CLASSHASH_MASK (CLASSHASH_SIZE - 1) | |
97 | #define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK) | |
98 | #define classhashentry(key) (classhash_table + __classhashfn((key))) | |
99 | ||
100 | static struct list_head classhash_table[CLASSHASH_SIZE]; | |
101 | ||
102 | unsigned long nr_lock_chains; | |
103 | static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; | |
104 | ||
105 | /* | |
106 | * We put the lock dependency chains into a hash-table as well, to cache | |
107 | * their existence: | |
108 | */ | |
109 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) | |
110 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) | |
111 | #define CHAINHASH_MASK (CHAINHASH_SIZE - 1) | |
112 | #define __chainhashfn(chain) \ | |
113 | (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK) | |
114 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) | |
115 | ||
116 | static struct list_head chainhash_table[CHAINHASH_SIZE]; | |
117 | ||
118 | /* | |
119 | * The hash key of the lock dependency chains is a hash itself too: | |
120 | * it's a hash of all locks taken up to that lock, including that lock. | |
121 | * It's a 64-bit hash, because it's important for the keys to be | |
122 | * unique. | |
123 | */ | |
124 | #define iterate_chain_key(key1, key2) \ | |
125 | (((key1) << MAX_LOCKDEP_KEYS_BITS/2) ^ \ | |
126 | ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS/2)) ^ \ | |
127 | (key2)) | |
128 | ||
129 | void lockdep_off(void) | |
130 | { | |
131 | current->lockdep_recursion++; | |
132 | } | |
133 | ||
134 | EXPORT_SYMBOL(lockdep_off); | |
135 | ||
136 | void lockdep_on(void) | |
137 | { | |
138 | current->lockdep_recursion--; | |
139 | } | |
140 | ||
141 | EXPORT_SYMBOL(lockdep_on); | |
142 | ||
143 | int lockdep_internal(void) | |
144 | { | |
145 | return current->lockdep_recursion != 0; | |
146 | } | |
147 | ||
148 | EXPORT_SYMBOL(lockdep_internal); | |
149 | ||
150 | /* | |
151 | * Debugging switches: | |
152 | */ | |
153 | ||
154 | #define VERBOSE 0 | |
155 | #ifdef VERBOSE | |
156 | # define VERY_VERBOSE 0 | |
157 | #endif | |
158 | ||
159 | #if VERBOSE | |
160 | # define HARDIRQ_VERBOSE 1 | |
161 | # define SOFTIRQ_VERBOSE 1 | |
162 | #else | |
163 | # define HARDIRQ_VERBOSE 0 | |
164 | # define SOFTIRQ_VERBOSE 0 | |
165 | #endif | |
166 | ||
167 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE | |
168 | /* | |
169 | * Quick filtering for interesting events: | |
170 | */ | |
171 | static int class_filter(struct lock_class *class) | |
172 | { | |
f9829cce AK |
173 | #if 0 |
174 | /* Example */ | |
fbb9ce95 | 175 | if (class->name_version == 1 && |
f9829cce | 176 | !strcmp(class->name, "lockname")) |
fbb9ce95 IM |
177 | return 1; |
178 | if (class->name_version == 1 && | |
f9829cce | 179 | !strcmp(class->name, "&struct->lockfield")) |
fbb9ce95 | 180 | return 1; |
f9829cce AK |
181 | #endif |
182 | /* Allow everything else. 0 would be filter everything else */ | |
183 | return 1; | |
fbb9ce95 IM |
184 | } |
185 | #endif | |
186 | ||
187 | static int verbose(struct lock_class *class) | |
188 | { | |
189 | #if VERBOSE | |
190 | return class_filter(class); | |
191 | #endif | |
192 | return 0; | |
193 | } | |
194 | ||
195 | #ifdef CONFIG_TRACE_IRQFLAGS | |
196 | ||
197 | static int hardirq_verbose(struct lock_class *class) | |
198 | { | |
199 | #if HARDIRQ_VERBOSE | |
200 | return class_filter(class); | |
201 | #endif | |
202 | return 0; | |
203 | } | |
204 | ||
205 | static int softirq_verbose(struct lock_class *class) | |
206 | { | |
207 | #if SOFTIRQ_VERBOSE | |
208 | return class_filter(class); | |
209 | #endif | |
210 | return 0; | |
211 | } | |
212 | ||
213 | #endif | |
214 | ||
215 | /* | |
216 | * Stack-trace: tightly packed array of stack backtrace | |
217 | * addresses. Protected by the hash_lock. | |
218 | */ | |
219 | unsigned long nr_stack_trace_entries; | |
220 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; | |
221 | ||
222 | static int save_trace(struct stack_trace *trace) | |
223 | { | |
224 | trace->nr_entries = 0; | |
225 | trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; | |
226 | trace->entries = stack_trace + nr_stack_trace_entries; | |
227 | ||
5a1b3999 AK |
228 | trace->skip = 3; |
229 | trace->all_contexts = 0; | |
230 | ||
3fa7c794 AK |
231 | /* Make sure to not recurse in case the the unwinder needs to tak |
232 | e locks. */ | |
233 | lockdep_off(); | |
5a1b3999 | 234 | save_stack_trace(trace, NULL); |
3fa7c794 | 235 | lockdep_on(); |
fbb9ce95 IM |
236 | |
237 | trace->max_entries = trace->nr_entries; | |
238 | ||
239 | nr_stack_trace_entries += trace->nr_entries; | |
240 | if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES)) | |
241 | return 0; | |
242 | ||
243 | if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) { | |
244 | __raw_spin_unlock(&hash_lock); | |
245 | if (debug_locks_off()) { | |
246 | printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); | |
247 | printk("turning off the locking correctness validator.\n"); | |
248 | dump_stack(); | |
249 | } | |
250 | return 0; | |
251 | } | |
252 | ||
253 | return 1; | |
254 | } | |
255 | ||
256 | unsigned int nr_hardirq_chains; | |
257 | unsigned int nr_softirq_chains; | |
258 | unsigned int nr_process_chains; | |
259 | unsigned int max_lockdep_depth; | |
260 | unsigned int max_recursion_depth; | |
261 | ||
262 | #ifdef CONFIG_DEBUG_LOCKDEP | |
263 | /* | |
264 | * We cannot printk in early bootup code. Not even early_printk() | |
265 | * might work. So we mark any initialization errors and printk | |
266 | * about it later on, in lockdep_info(). | |
267 | */ | |
268 | static int lockdep_init_error; | |
269 | ||
270 | /* | |
271 | * Various lockdep statistics: | |
272 | */ | |
273 | atomic_t chain_lookup_hits; | |
274 | atomic_t chain_lookup_misses; | |
275 | atomic_t hardirqs_on_events; | |
276 | atomic_t hardirqs_off_events; | |
277 | atomic_t redundant_hardirqs_on; | |
278 | atomic_t redundant_hardirqs_off; | |
279 | atomic_t softirqs_on_events; | |
280 | atomic_t softirqs_off_events; | |
281 | atomic_t redundant_softirqs_on; | |
282 | atomic_t redundant_softirqs_off; | |
283 | atomic_t nr_unused_locks; | |
284 | atomic_t nr_cyclic_checks; | |
285 | atomic_t nr_cyclic_check_recursions; | |
286 | atomic_t nr_find_usage_forwards_checks; | |
287 | atomic_t nr_find_usage_forwards_recursions; | |
288 | atomic_t nr_find_usage_backwards_checks; | |
289 | atomic_t nr_find_usage_backwards_recursions; | |
290 | # define debug_atomic_inc(ptr) atomic_inc(ptr) | |
291 | # define debug_atomic_dec(ptr) atomic_dec(ptr) | |
292 | # define debug_atomic_read(ptr) atomic_read(ptr) | |
293 | #else | |
294 | # define debug_atomic_inc(ptr) do { } while (0) | |
295 | # define debug_atomic_dec(ptr) do { } while (0) | |
296 | # define debug_atomic_read(ptr) 0 | |
297 | #endif | |
298 | ||
299 | /* | |
300 | * Locking printouts: | |
301 | */ | |
302 | ||
303 | static const char *usage_str[] = | |
304 | { | |
305 | [LOCK_USED] = "initial-use ", | |
306 | [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W", | |
307 | [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W", | |
308 | [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W", | |
309 | [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W", | |
310 | [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R", | |
311 | [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R", | |
312 | [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R", | |
313 | [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R", | |
314 | }; | |
315 | ||
316 | const char * __get_key_name(struct lockdep_subclass_key *key, char *str) | |
317 | { | |
318 | unsigned long offs, size; | |
319 | char *modname; | |
320 | ||
321 | return kallsyms_lookup((unsigned long)key, &size, &offs, &modname, str); | |
322 | } | |
323 | ||
324 | void | |
325 | get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4) | |
326 | { | |
327 | *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.'; | |
328 | ||
329 | if (class->usage_mask & LOCKF_USED_IN_HARDIRQ) | |
330 | *c1 = '+'; | |
331 | else | |
332 | if (class->usage_mask & LOCKF_ENABLED_HARDIRQS) | |
333 | *c1 = '-'; | |
334 | ||
335 | if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ) | |
336 | *c2 = '+'; | |
337 | else | |
338 | if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS) | |
339 | *c2 = '-'; | |
340 | ||
341 | if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) | |
342 | *c3 = '-'; | |
343 | if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) { | |
344 | *c3 = '+'; | |
345 | if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) | |
346 | *c3 = '?'; | |
347 | } | |
348 | ||
349 | if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) | |
350 | *c4 = '-'; | |
351 | if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) { | |
352 | *c4 = '+'; | |
353 | if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) | |
354 | *c4 = '?'; | |
355 | } | |
356 | } | |
357 | ||
358 | static void print_lock_name(struct lock_class *class) | |
359 | { | |
360 | char str[128], c1, c2, c3, c4; | |
361 | const char *name; | |
362 | ||
363 | get_usage_chars(class, &c1, &c2, &c3, &c4); | |
364 | ||
365 | name = class->name; | |
366 | if (!name) { | |
367 | name = __get_key_name(class->key, str); | |
368 | printk(" (%s", name); | |
369 | } else { | |
370 | printk(" (%s", name); | |
371 | if (class->name_version > 1) | |
372 | printk("#%d", class->name_version); | |
373 | if (class->subclass) | |
374 | printk("/%d", class->subclass); | |
375 | } | |
376 | printk("){%c%c%c%c}", c1, c2, c3, c4); | |
377 | } | |
378 | ||
379 | static void print_lockdep_cache(struct lockdep_map *lock) | |
380 | { | |
381 | const char *name; | |
382 | char str[128]; | |
383 | ||
384 | name = lock->name; | |
385 | if (!name) | |
386 | name = __get_key_name(lock->key->subkeys, str); | |
387 | ||
388 | printk("%s", name); | |
389 | } | |
390 | ||
391 | static void print_lock(struct held_lock *hlock) | |
392 | { | |
393 | print_lock_name(hlock->class); | |
394 | printk(", at: "); | |
395 | print_ip_sym(hlock->acquire_ip); | |
396 | } | |
397 | ||
398 | static void lockdep_print_held_locks(struct task_struct *curr) | |
399 | { | |
400 | int i, depth = curr->lockdep_depth; | |
401 | ||
402 | if (!depth) { | |
403 | printk("no locks held by %s/%d.\n", curr->comm, curr->pid); | |
404 | return; | |
405 | } | |
406 | printk("%d lock%s held by %s/%d:\n", | |
407 | depth, depth > 1 ? "s" : "", curr->comm, curr->pid); | |
408 | ||
409 | for (i = 0; i < depth; i++) { | |
410 | printk(" #%d: ", i); | |
411 | print_lock(curr->held_locks + i); | |
412 | } | |
413 | } | |
fbb9ce95 IM |
414 | |
415 | static void print_lock_class_header(struct lock_class *class, int depth) | |
416 | { | |
417 | int bit; | |
418 | ||
f9829cce | 419 | printk("%*s->", depth, ""); |
fbb9ce95 IM |
420 | print_lock_name(class); |
421 | printk(" ops: %lu", class->ops); | |
422 | printk(" {\n"); | |
423 | ||
424 | for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { | |
425 | if (class->usage_mask & (1 << bit)) { | |
426 | int len = depth; | |
427 | ||
f9829cce | 428 | len += printk("%*s %s", depth, "", usage_str[bit]); |
fbb9ce95 IM |
429 | len += printk(" at:\n"); |
430 | print_stack_trace(class->usage_traces + bit, len); | |
431 | } | |
432 | } | |
f9829cce | 433 | printk("%*s }\n", depth, ""); |
fbb9ce95 | 434 | |
f9829cce | 435 | printk("%*s ... key at: ",depth,""); |
fbb9ce95 IM |
436 | print_ip_sym((unsigned long)class->key); |
437 | } | |
438 | ||
439 | /* | |
440 | * printk all lock dependencies starting at <entry>: | |
441 | */ | |
442 | static void print_lock_dependencies(struct lock_class *class, int depth) | |
443 | { | |
444 | struct lock_list *entry; | |
445 | ||
446 | if (DEBUG_LOCKS_WARN_ON(depth >= 20)) | |
447 | return; | |
448 | ||
449 | print_lock_class_header(class, depth); | |
450 | ||
451 | list_for_each_entry(entry, &class->locks_after, entry) { | |
452 | DEBUG_LOCKS_WARN_ON(!entry->class); | |
453 | print_lock_dependencies(entry->class, depth + 1); | |
454 | ||
f9829cce | 455 | printk("%*s ... acquired at:\n",depth,""); |
fbb9ce95 IM |
456 | print_stack_trace(&entry->trace, 2); |
457 | printk("\n"); | |
458 | } | |
459 | } | |
460 | ||
461 | /* | |
462 | * Add a new dependency to the head of the list: | |
463 | */ | |
464 | static int add_lock_to_list(struct lock_class *class, struct lock_class *this, | |
465 | struct list_head *head, unsigned long ip) | |
466 | { | |
467 | struct lock_list *entry; | |
468 | /* | |
469 | * Lock not present yet - get a new dependency struct and | |
470 | * add it to the list: | |
471 | */ | |
472 | entry = alloc_list_entry(); | |
473 | if (!entry) | |
474 | return 0; | |
475 | ||
476 | entry->class = this; | |
477 | save_trace(&entry->trace); | |
478 | ||
479 | /* | |
480 | * Since we never remove from the dependency list, the list can | |
481 | * be walked lockless by other CPUs, it's only allocation | |
482 | * that must be protected by the spinlock. But this also means | |
483 | * we must make new entries visible only once writes to the | |
484 | * entry become visible - hence the RCU op: | |
485 | */ | |
486 | list_add_tail_rcu(&entry->entry, head); | |
487 | ||
488 | return 1; | |
489 | } | |
490 | ||
491 | /* | |
492 | * Recursive, forwards-direction lock-dependency checking, used for | |
493 | * both noncyclic checking and for hardirq-unsafe/softirq-unsafe | |
494 | * checking. | |
495 | * | |
496 | * (to keep the stackframe of the recursive functions small we | |
497 | * use these global variables, and we also mark various helper | |
498 | * functions as noinline.) | |
499 | */ | |
500 | static struct held_lock *check_source, *check_target; | |
501 | ||
502 | /* | |
503 | * Print a dependency chain entry (this is only done when a deadlock | |
504 | * has been detected): | |
505 | */ | |
506 | static noinline int | |
507 | print_circular_bug_entry(struct lock_list *target, unsigned int depth) | |
508 | { | |
509 | if (debug_locks_silent) | |
510 | return 0; | |
511 | printk("\n-> #%u", depth); | |
512 | print_lock_name(target->class); | |
513 | printk(":\n"); | |
514 | print_stack_trace(&target->trace, 6); | |
515 | ||
516 | return 0; | |
517 | } | |
518 | ||
99de055a DJ |
519 | static void print_kernel_version(void) |
520 | { | |
521 | printk("%s %.*s\n", system_utsname.release, | |
522 | (int)strcspn(system_utsname.version, " "), | |
523 | system_utsname.version); | |
524 | } | |
525 | ||
fbb9ce95 IM |
526 | /* |
527 | * When a circular dependency is detected, print the | |
528 | * header first: | |
529 | */ | |
530 | static noinline int | |
531 | print_circular_bug_header(struct lock_list *entry, unsigned int depth) | |
532 | { | |
533 | struct task_struct *curr = current; | |
534 | ||
535 | __raw_spin_unlock(&hash_lock); | |
536 | debug_locks_off(); | |
537 | if (debug_locks_silent) | |
538 | return 0; | |
539 | ||
540 | printk("\n=======================================================\n"); | |
541 | printk( "[ INFO: possible circular locking dependency detected ]\n"); | |
99de055a | 542 | print_kernel_version(); |
fbb9ce95 IM |
543 | printk( "-------------------------------------------------------\n"); |
544 | printk("%s/%d is trying to acquire lock:\n", | |
545 | curr->comm, curr->pid); | |
546 | print_lock(check_source); | |
547 | printk("\nbut task is already holding lock:\n"); | |
548 | print_lock(check_target); | |
549 | printk("\nwhich lock already depends on the new lock.\n\n"); | |
550 | printk("\nthe existing dependency chain (in reverse order) is:\n"); | |
551 | ||
552 | print_circular_bug_entry(entry, depth); | |
553 | ||
554 | return 0; | |
555 | } | |
556 | ||
557 | static noinline int print_circular_bug_tail(void) | |
558 | { | |
559 | struct task_struct *curr = current; | |
560 | struct lock_list this; | |
561 | ||
562 | if (debug_locks_silent) | |
563 | return 0; | |
564 | ||
565 | this.class = check_source->class; | |
566 | save_trace(&this.trace); | |
567 | print_circular_bug_entry(&this, 0); | |
568 | ||
569 | printk("\nother info that might help us debug this:\n\n"); | |
570 | lockdep_print_held_locks(curr); | |
571 | ||
572 | printk("\nstack backtrace:\n"); | |
573 | dump_stack(); | |
574 | ||
575 | return 0; | |
576 | } | |
577 | ||
578 | static int noinline print_infinite_recursion_bug(void) | |
579 | { | |
580 | __raw_spin_unlock(&hash_lock); | |
581 | DEBUG_LOCKS_WARN_ON(1); | |
582 | ||
583 | return 0; | |
584 | } | |
585 | ||
586 | /* | |
587 | * Prove that the dependency graph starting at <entry> can not | |
588 | * lead to <target>. Print an error and return 0 if it does. | |
589 | */ | |
590 | static noinline int | |
591 | check_noncircular(struct lock_class *source, unsigned int depth) | |
592 | { | |
593 | struct lock_list *entry; | |
594 | ||
595 | debug_atomic_inc(&nr_cyclic_check_recursions); | |
596 | if (depth > max_recursion_depth) | |
597 | max_recursion_depth = depth; | |
598 | if (depth >= 20) | |
599 | return print_infinite_recursion_bug(); | |
600 | /* | |
601 | * Check this lock's dependency list: | |
602 | */ | |
603 | list_for_each_entry(entry, &source->locks_after, entry) { | |
604 | if (entry->class == check_target->class) | |
605 | return print_circular_bug_header(entry, depth+1); | |
606 | debug_atomic_inc(&nr_cyclic_checks); | |
607 | if (!check_noncircular(entry->class, depth+1)) | |
608 | return print_circular_bug_entry(entry, depth+1); | |
609 | } | |
610 | return 1; | |
611 | } | |
612 | ||
613 | static int very_verbose(struct lock_class *class) | |
614 | { | |
615 | #if VERY_VERBOSE | |
616 | return class_filter(class); | |
617 | #endif | |
618 | return 0; | |
619 | } | |
620 | #ifdef CONFIG_TRACE_IRQFLAGS | |
621 | ||
622 | /* | |
623 | * Forwards and backwards subgraph searching, for the purposes of | |
624 | * proving that two subgraphs can be connected by a new dependency | |
625 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. | |
626 | */ | |
627 | static enum lock_usage_bit find_usage_bit; | |
628 | static struct lock_class *forwards_match, *backwards_match; | |
629 | ||
630 | /* | |
631 | * Find a node in the forwards-direction dependency sub-graph starting | |
632 | * at <source> that matches <find_usage_bit>. | |
633 | * | |
634 | * Return 2 if such a node exists in the subgraph, and put that node | |
635 | * into <forwards_match>. | |
636 | * | |
637 | * Return 1 otherwise and keep <forwards_match> unchanged. | |
638 | * Return 0 on error. | |
639 | */ | |
640 | static noinline int | |
641 | find_usage_forwards(struct lock_class *source, unsigned int depth) | |
642 | { | |
643 | struct lock_list *entry; | |
644 | int ret; | |
645 | ||
646 | if (depth > max_recursion_depth) | |
647 | max_recursion_depth = depth; | |
648 | if (depth >= 20) | |
649 | return print_infinite_recursion_bug(); | |
650 | ||
651 | debug_atomic_inc(&nr_find_usage_forwards_checks); | |
652 | if (source->usage_mask & (1 << find_usage_bit)) { | |
653 | forwards_match = source; | |
654 | return 2; | |
655 | } | |
656 | ||
657 | /* | |
658 | * Check this lock's dependency list: | |
659 | */ | |
660 | list_for_each_entry(entry, &source->locks_after, entry) { | |
661 | debug_atomic_inc(&nr_find_usage_forwards_recursions); | |
662 | ret = find_usage_forwards(entry->class, depth+1); | |
663 | if (ret == 2 || ret == 0) | |
664 | return ret; | |
665 | } | |
666 | return 1; | |
667 | } | |
668 | ||
669 | /* | |
670 | * Find a node in the backwards-direction dependency sub-graph starting | |
671 | * at <source> that matches <find_usage_bit>. | |
672 | * | |
673 | * Return 2 if such a node exists in the subgraph, and put that node | |
674 | * into <backwards_match>. | |
675 | * | |
676 | * Return 1 otherwise and keep <backwards_match> unchanged. | |
677 | * Return 0 on error. | |
678 | */ | |
679 | static noinline int | |
680 | find_usage_backwards(struct lock_class *source, unsigned int depth) | |
681 | { | |
682 | struct lock_list *entry; | |
683 | int ret; | |
684 | ||
685 | if (depth > max_recursion_depth) | |
686 | max_recursion_depth = depth; | |
687 | if (depth >= 20) | |
688 | return print_infinite_recursion_bug(); | |
689 | ||
690 | debug_atomic_inc(&nr_find_usage_backwards_checks); | |
691 | if (source->usage_mask & (1 << find_usage_bit)) { | |
692 | backwards_match = source; | |
693 | return 2; | |
694 | } | |
695 | ||
696 | /* | |
697 | * Check this lock's dependency list: | |
698 | */ | |
699 | list_for_each_entry(entry, &source->locks_before, entry) { | |
700 | debug_atomic_inc(&nr_find_usage_backwards_recursions); | |
701 | ret = find_usage_backwards(entry->class, depth+1); | |
702 | if (ret == 2 || ret == 0) | |
703 | return ret; | |
704 | } | |
705 | return 1; | |
706 | } | |
707 | ||
708 | static int | |
709 | print_bad_irq_dependency(struct task_struct *curr, | |
710 | struct held_lock *prev, | |
711 | struct held_lock *next, | |
712 | enum lock_usage_bit bit1, | |
713 | enum lock_usage_bit bit2, | |
714 | const char *irqclass) | |
715 | { | |
716 | __raw_spin_unlock(&hash_lock); | |
717 | debug_locks_off(); | |
718 | if (debug_locks_silent) | |
719 | return 0; | |
720 | ||
721 | printk("\n======================================================\n"); | |
722 | printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", | |
723 | irqclass, irqclass); | |
99de055a | 724 | print_kernel_version(); |
fbb9ce95 IM |
725 | printk( "------------------------------------------------------\n"); |
726 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", | |
727 | curr->comm, curr->pid, | |
728 | curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, | |
729 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, | |
730 | curr->hardirqs_enabled, | |
731 | curr->softirqs_enabled); | |
732 | print_lock(next); | |
733 | ||
734 | printk("\nand this task is already holding:\n"); | |
735 | print_lock(prev); | |
736 | printk("which would create a new lock dependency:\n"); | |
737 | print_lock_name(prev->class); | |
738 | printk(" ->"); | |
739 | print_lock_name(next->class); | |
740 | printk("\n"); | |
741 | ||
742 | printk("\nbut this new dependency connects a %s-irq-safe lock:\n", | |
743 | irqclass); | |
744 | print_lock_name(backwards_match); | |
745 | printk("\n... which became %s-irq-safe at:\n", irqclass); | |
746 | ||
747 | print_stack_trace(backwards_match->usage_traces + bit1, 1); | |
748 | ||
749 | printk("\nto a %s-irq-unsafe lock:\n", irqclass); | |
750 | print_lock_name(forwards_match); | |
751 | printk("\n... which became %s-irq-unsafe at:\n", irqclass); | |
752 | printk("..."); | |
753 | ||
754 | print_stack_trace(forwards_match->usage_traces + bit2, 1); | |
755 | ||
756 | printk("\nother info that might help us debug this:\n\n"); | |
757 | lockdep_print_held_locks(curr); | |
758 | ||
759 | printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass); | |
760 | print_lock_dependencies(backwards_match, 0); | |
761 | ||
762 | printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass); | |
763 | print_lock_dependencies(forwards_match, 0); | |
764 | ||
765 | printk("\nstack backtrace:\n"); | |
766 | dump_stack(); | |
767 | ||
768 | return 0; | |
769 | } | |
770 | ||
771 | static int | |
772 | check_usage(struct task_struct *curr, struct held_lock *prev, | |
773 | struct held_lock *next, enum lock_usage_bit bit_backwards, | |
774 | enum lock_usage_bit bit_forwards, const char *irqclass) | |
775 | { | |
776 | int ret; | |
777 | ||
778 | find_usage_bit = bit_backwards; | |
779 | /* fills in <backwards_match> */ | |
780 | ret = find_usage_backwards(prev->class, 0); | |
781 | if (!ret || ret == 1) | |
782 | return ret; | |
783 | ||
784 | find_usage_bit = bit_forwards; | |
785 | ret = find_usage_forwards(next->class, 0); | |
786 | if (!ret || ret == 1) | |
787 | return ret; | |
788 | /* ret == 2 */ | |
789 | return print_bad_irq_dependency(curr, prev, next, | |
790 | bit_backwards, bit_forwards, irqclass); | |
791 | } | |
792 | ||
793 | #endif | |
794 | ||
795 | static int | |
796 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, | |
797 | struct held_lock *next) | |
798 | { | |
799 | debug_locks_off(); | |
800 | __raw_spin_unlock(&hash_lock); | |
801 | if (debug_locks_silent) | |
802 | return 0; | |
803 | ||
804 | printk("\n=============================================\n"); | |
805 | printk( "[ INFO: possible recursive locking detected ]\n"); | |
99de055a | 806 | print_kernel_version(); |
fbb9ce95 IM |
807 | printk( "---------------------------------------------\n"); |
808 | printk("%s/%d is trying to acquire lock:\n", | |
809 | curr->comm, curr->pid); | |
810 | print_lock(next); | |
811 | printk("\nbut task is already holding lock:\n"); | |
812 | print_lock(prev); | |
813 | ||
814 | printk("\nother info that might help us debug this:\n"); | |
815 | lockdep_print_held_locks(curr); | |
816 | ||
817 | printk("\nstack backtrace:\n"); | |
818 | dump_stack(); | |
819 | ||
820 | return 0; | |
821 | } | |
822 | ||
823 | /* | |
824 | * Check whether we are holding such a class already. | |
825 | * | |
826 | * (Note that this has to be done separately, because the graph cannot | |
827 | * detect such classes of deadlocks.) | |
828 | * | |
829 | * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read | |
830 | */ | |
831 | static int | |
832 | check_deadlock(struct task_struct *curr, struct held_lock *next, | |
833 | struct lockdep_map *next_instance, int read) | |
834 | { | |
835 | struct held_lock *prev; | |
836 | int i; | |
837 | ||
838 | for (i = 0; i < curr->lockdep_depth; i++) { | |
839 | prev = curr->held_locks + i; | |
840 | if (prev->class != next->class) | |
841 | continue; | |
842 | /* | |
843 | * Allow read-after-read recursion of the same | |
6c9076ec | 844 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
fbb9ce95 | 845 | */ |
6c9076ec | 846 | if ((read == 2) && prev->read) |
fbb9ce95 IM |
847 | return 2; |
848 | return print_deadlock_bug(curr, prev, next); | |
849 | } | |
850 | return 1; | |
851 | } | |
852 | ||
853 | /* | |
854 | * There was a chain-cache miss, and we are about to add a new dependency | |
855 | * to a previous lock. We recursively validate the following rules: | |
856 | * | |
857 | * - would the adding of the <prev> -> <next> dependency create a | |
858 | * circular dependency in the graph? [== circular deadlock] | |
859 | * | |
860 | * - does the new prev->next dependency connect any hardirq-safe lock | |
861 | * (in the full backwards-subgraph starting at <prev>) with any | |
862 | * hardirq-unsafe lock (in the full forwards-subgraph starting at | |
863 | * <next>)? [== illegal lock inversion with hardirq contexts] | |
864 | * | |
865 | * - does the new prev->next dependency connect any softirq-safe lock | |
866 | * (in the full backwards-subgraph starting at <prev>) with any | |
867 | * softirq-unsafe lock (in the full forwards-subgraph starting at | |
868 | * <next>)? [== illegal lock inversion with softirq contexts] | |
869 | * | |
870 | * any of these scenarios could lead to a deadlock. | |
871 | * | |
872 | * Then if all the validations pass, we add the forwards and backwards | |
873 | * dependency. | |
874 | */ | |
875 | static int | |
876 | check_prev_add(struct task_struct *curr, struct held_lock *prev, | |
877 | struct held_lock *next) | |
878 | { | |
879 | struct lock_list *entry; | |
880 | int ret; | |
881 | ||
882 | /* | |
883 | * Prove that the new <prev> -> <next> dependency would not | |
884 | * create a circular dependency in the graph. (We do this by | |
885 | * forward-recursing into the graph starting at <next>, and | |
886 | * checking whether we can reach <prev>.) | |
887 | * | |
888 | * We are using global variables to control the recursion, to | |
889 | * keep the stackframe size of the recursive functions low: | |
890 | */ | |
891 | check_source = next; | |
892 | check_target = prev; | |
893 | if (!(check_noncircular(next->class, 0))) | |
894 | return print_circular_bug_tail(); | |
895 | ||
896 | #ifdef CONFIG_TRACE_IRQFLAGS | |
897 | /* | |
898 | * Prove that the new dependency does not connect a hardirq-safe | |
899 | * lock with a hardirq-unsafe lock - to achieve this we search | |
900 | * the backwards-subgraph starting at <prev>, and the | |
901 | * forwards-subgraph starting at <next>: | |
902 | */ | |
903 | if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ, | |
904 | LOCK_ENABLED_HARDIRQS, "hard")) | |
905 | return 0; | |
906 | ||
907 | /* | |
908 | * Prove that the new dependency does not connect a hardirq-safe-read | |
909 | * lock with a hardirq-unsafe lock - to achieve this we search | |
910 | * the backwards-subgraph starting at <prev>, and the | |
911 | * forwards-subgraph starting at <next>: | |
912 | */ | |
913 | if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ, | |
914 | LOCK_ENABLED_HARDIRQS, "hard-read")) | |
915 | return 0; | |
916 | ||
917 | /* | |
918 | * Prove that the new dependency does not connect a softirq-safe | |
919 | * lock with a softirq-unsafe lock - to achieve this we search | |
920 | * the backwards-subgraph starting at <prev>, and the | |
921 | * forwards-subgraph starting at <next>: | |
922 | */ | |
923 | if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ, | |
924 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
925 | return 0; | |
926 | /* | |
927 | * Prove that the new dependency does not connect a softirq-safe-read | |
928 | * lock with a softirq-unsafe lock - to achieve this we search | |
929 | * the backwards-subgraph starting at <prev>, and the | |
930 | * forwards-subgraph starting at <next>: | |
931 | */ | |
932 | if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ, | |
933 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
934 | return 0; | |
935 | #endif | |
936 | /* | |
937 | * For recursive read-locks we do all the dependency checks, | |
938 | * but we dont store read-triggered dependencies (only | |
939 | * write-triggered dependencies). This ensures that only the | |
940 | * write-side dependencies matter, and that if for example a | |
941 | * write-lock never takes any other locks, then the reads are | |
942 | * equivalent to a NOP. | |
943 | */ | |
944 | if (next->read == 2 || prev->read == 2) | |
945 | return 1; | |
946 | /* | |
947 | * Is the <prev> -> <next> dependency already present? | |
948 | * | |
949 | * (this may occur even though this is a new chain: consider | |
950 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 | |
951 | * chains - the second one will be new, but L1 already has | |
952 | * L2 added to its dependency list, due to the first chain.) | |
953 | */ | |
954 | list_for_each_entry(entry, &prev->class->locks_after, entry) { | |
955 | if (entry->class == next->class) | |
956 | return 2; | |
957 | } | |
958 | ||
959 | /* | |
960 | * Ok, all validations passed, add the new lock | |
961 | * to the previous lock's dependency list: | |
962 | */ | |
963 | ret = add_lock_to_list(prev->class, next->class, | |
964 | &prev->class->locks_after, next->acquire_ip); | |
965 | if (!ret) | |
966 | return 0; | |
967 | /* | |
968 | * Return value of 2 signals 'dependency already added', | |
969 | * in that case we dont have to add the backlink either. | |
970 | */ | |
971 | if (ret == 2) | |
972 | return 2; | |
973 | ret = add_lock_to_list(next->class, prev->class, | |
974 | &next->class->locks_before, next->acquire_ip); | |
975 | ||
976 | /* | |
977 | * Debugging printouts: | |
978 | */ | |
979 | if (verbose(prev->class) || verbose(next->class)) { | |
980 | __raw_spin_unlock(&hash_lock); | |
981 | printk("\n new dependency: "); | |
982 | print_lock_name(prev->class); | |
983 | printk(" => "); | |
984 | print_lock_name(next->class); | |
985 | printk("\n"); | |
986 | dump_stack(); | |
987 | __raw_spin_lock(&hash_lock); | |
988 | } | |
989 | return 1; | |
990 | } | |
991 | ||
992 | /* | |
993 | * Add the dependency to all directly-previous locks that are 'relevant'. | |
994 | * The ones that are relevant are (in increasing distance from curr): | |
995 | * all consecutive trylock entries and the final non-trylock entry - or | |
996 | * the end of this context's lock-chain - whichever comes first. | |
997 | */ | |
998 | static int | |
999 | check_prevs_add(struct task_struct *curr, struct held_lock *next) | |
1000 | { | |
1001 | int depth = curr->lockdep_depth; | |
1002 | struct held_lock *hlock; | |
1003 | ||
1004 | /* | |
1005 | * Debugging checks. | |
1006 | * | |
1007 | * Depth must not be zero for a non-head lock: | |
1008 | */ | |
1009 | if (!depth) | |
1010 | goto out_bug; | |
1011 | /* | |
1012 | * At least two relevant locks must exist for this | |
1013 | * to be a head: | |
1014 | */ | |
1015 | if (curr->held_locks[depth].irq_context != | |
1016 | curr->held_locks[depth-1].irq_context) | |
1017 | goto out_bug; | |
1018 | ||
1019 | for (;;) { | |
1020 | hlock = curr->held_locks + depth-1; | |
1021 | /* | |
1022 | * Only non-recursive-read entries get new dependencies | |
1023 | * added: | |
1024 | */ | |
1025 | if (hlock->read != 2) { | |
1026 | check_prev_add(curr, hlock, next); | |
1027 | /* | |
1028 | * Stop after the first non-trylock entry, | |
1029 | * as non-trylock entries have added their | |
1030 | * own direct dependencies already, so this | |
1031 | * lock is connected to them indirectly: | |
1032 | */ | |
1033 | if (!hlock->trylock) | |
1034 | break; | |
1035 | } | |
1036 | depth--; | |
1037 | /* | |
1038 | * End of lock-stack? | |
1039 | */ | |
1040 | if (!depth) | |
1041 | break; | |
1042 | /* | |
1043 | * Stop the search if we cross into another context: | |
1044 | */ | |
1045 | if (curr->held_locks[depth].irq_context != | |
1046 | curr->held_locks[depth-1].irq_context) | |
1047 | break; | |
1048 | } | |
1049 | return 1; | |
1050 | out_bug: | |
1051 | __raw_spin_unlock(&hash_lock); | |
1052 | DEBUG_LOCKS_WARN_ON(1); | |
1053 | ||
1054 | return 0; | |
1055 | } | |
1056 | ||
1057 | ||
1058 | /* | |
1059 | * Is this the address of a static object: | |
1060 | */ | |
1061 | static int static_obj(void *obj) | |
1062 | { | |
1063 | unsigned long start = (unsigned long) &_stext, | |
1064 | end = (unsigned long) &_end, | |
1065 | addr = (unsigned long) obj; | |
1066 | #ifdef CONFIG_SMP | |
1067 | int i; | |
1068 | #endif | |
1069 | ||
1070 | /* | |
1071 | * static variable? | |
1072 | */ | |
1073 | if ((addr >= start) && (addr < end)) | |
1074 | return 1; | |
1075 | ||
1076 | #ifdef CONFIG_SMP | |
1077 | /* | |
1078 | * percpu var? | |
1079 | */ | |
1080 | for_each_possible_cpu(i) { | |
1081 | start = (unsigned long) &__per_cpu_start + per_cpu_offset(i); | |
1082 | end = (unsigned long) &__per_cpu_end + per_cpu_offset(i); | |
1083 | ||
1084 | if ((addr >= start) && (addr < end)) | |
1085 | return 1; | |
1086 | } | |
1087 | #endif | |
1088 | ||
1089 | /* | |
1090 | * module var? | |
1091 | */ | |
1092 | return is_module_address(addr); | |
1093 | } | |
1094 | ||
1095 | /* | |
1096 | * To make lock name printouts unique, we calculate a unique | |
1097 | * class->name_version generation counter: | |
1098 | */ | |
1099 | static int count_matching_names(struct lock_class *new_class) | |
1100 | { | |
1101 | struct lock_class *class; | |
1102 | int count = 0; | |
1103 | ||
1104 | if (!new_class->name) | |
1105 | return 0; | |
1106 | ||
1107 | list_for_each_entry(class, &all_lock_classes, lock_entry) { | |
1108 | if (new_class->key - new_class->subclass == class->key) | |
1109 | return class->name_version; | |
1110 | if (class->name && !strcmp(class->name, new_class->name)) | |
1111 | count = max(count, class->name_version); | |
1112 | } | |
1113 | ||
1114 | return count + 1; | |
1115 | } | |
1116 | ||
1117 | extern void __error_too_big_MAX_LOCKDEP_SUBCLASSES(void); | |
1118 | ||
1119 | /* | |
1120 | * Register a lock's class in the hash-table, if the class is not present | |
1121 | * yet. Otherwise we look it up. We cache the result in the lock object | |
1122 | * itself, so actual lookup of the hash should be once per lock object. | |
1123 | */ | |
1124 | static inline struct lock_class * | |
d6d897ce | 1125 | look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) |
fbb9ce95 IM |
1126 | { |
1127 | struct lockdep_subclass_key *key; | |
1128 | struct list_head *hash_head; | |
1129 | struct lock_class *class; | |
1130 | ||
1131 | #ifdef CONFIG_DEBUG_LOCKDEP | |
1132 | /* | |
1133 | * If the architecture calls into lockdep before initializing | |
1134 | * the hashes then we'll warn about it later. (we cannot printk | |
1135 | * right now) | |
1136 | */ | |
1137 | if (unlikely(!lockdep_initialized)) { | |
1138 | lockdep_init(); | |
1139 | lockdep_init_error = 1; | |
1140 | } | |
1141 | #endif | |
1142 | ||
1143 | /* | |
1144 | * Static locks do not have their class-keys yet - for them the key | |
1145 | * is the lock object itself: | |
1146 | */ | |
1147 | if (unlikely(!lock->key)) | |
1148 | lock->key = (void *)lock; | |
1149 | ||
1150 | /* | |
1151 | * NOTE: the class-key must be unique. For dynamic locks, a static | |
1152 | * lock_class_key variable is passed in through the mutex_init() | |
1153 | * (or spin_lock_init()) call - which acts as the key. For static | |
1154 | * locks we use the lock object itself as the key. | |
1155 | */ | |
1156 | if (sizeof(struct lock_class_key) > sizeof(struct lock_class)) | |
1157 | __error_too_big_MAX_LOCKDEP_SUBCLASSES(); | |
1158 | ||
1159 | key = lock->key->subkeys + subclass; | |
1160 | ||
1161 | hash_head = classhashentry(key); | |
1162 | ||
1163 | /* | |
1164 | * We can walk the hash lockfree, because the hash only | |
1165 | * grows, and we are careful when adding entries to the end: | |
1166 | */ | |
1167 | list_for_each_entry(class, hash_head, hash_entry) | |
1168 | if (class->key == key) | |
d6d897ce IM |
1169 | return class; |
1170 | ||
1171 | return NULL; | |
1172 | } | |
1173 | ||
1174 | /* | |
1175 | * Register a lock's class in the hash-table, if the class is not present | |
1176 | * yet. Otherwise we look it up. We cache the result in the lock object | |
1177 | * itself, so actual lookup of the hash should be once per lock object. | |
1178 | */ | |
1179 | static inline struct lock_class * | |
1180 | register_lock_class(struct lockdep_map *lock, unsigned int subclass) | |
1181 | { | |
1182 | struct lockdep_subclass_key *key; | |
1183 | struct list_head *hash_head; | |
1184 | struct lock_class *class; | |
1185 | ||
1186 | class = look_up_lock_class(lock, subclass); | |
1187 | if (likely(class)) | |
1188 | return class; | |
fbb9ce95 IM |
1189 | |
1190 | /* | |
1191 | * Debug-check: all keys must be persistent! | |
1192 | */ | |
1193 | if (!static_obj(lock->key)) { | |
1194 | debug_locks_off(); | |
1195 | printk("INFO: trying to register non-static key.\n"); | |
1196 | printk("the code is fine but needs lockdep annotation.\n"); | |
1197 | printk("turning off the locking correctness validator.\n"); | |
1198 | dump_stack(); | |
1199 | ||
1200 | return NULL; | |
1201 | } | |
1202 | ||
d6d897ce IM |
1203 | key = lock->key->subkeys + subclass; |
1204 | hash_head = classhashentry(key); | |
1205 | ||
fbb9ce95 IM |
1206 | __raw_spin_lock(&hash_lock); |
1207 | /* | |
1208 | * We have to do the hash-walk again, to avoid races | |
1209 | * with another CPU: | |
1210 | */ | |
1211 | list_for_each_entry(class, hash_head, hash_entry) | |
1212 | if (class->key == key) | |
1213 | goto out_unlock_set; | |
1214 | /* | |
1215 | * Allocate a new key from the static array, and add it to | |
1216 | * the hash: | |
1217 | */ | |
1218 | if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { | |
1219 | __raw_spin_unlock(&hash_lock); | |
1220 | debug_locks_off(); | |
1221 | printk("BUG: MAX_LOCKDEP_KEYS too low!\n"); | |
1222 | printk("turning off the locking correctness validator.\n"); | |
1223 | return NULL; | |
1224 | } | |
1225 | class = lock_classes + nr_lock_classes++; | |
1226 | debug_atomic_inc(&nr_unused_locks); | |
1227 | class->key = key; | |
1228 | class->name = lock->name; | |
1229 | class->subclass = subclass; | |
1230 | INIT_LIST_HEAD(&class->lock_entry); | |
1231 | INIT_LIST_HEAD(&class->locks_before); | |
1232 | INIT_LIST_HEAD(&class->locks_after); | |
1233 | class->name_version = count_matching_names(class); | |
1234 | /* | |
1235 | * We use RCU's safe list-add method to make | |
1236 | * parallel walking of the hash-list safe: | |
1237 | */ | |
1238 | list_add_tail_rcu(&class->hash_entry, hash_head); | |
1239 | ||
1240 | if (verbose(class)) { | |
1241 | __raw_spin_unlock(&hash_lock); | |
1242 | printk("\nnew class %p: %s", class->key, class->name); | |
1243 | if (class->name_version > 1) | |
1244 | printk("#%d", class->name_version); | |
1245 | printk("\n"); | |
1246 | dump_stack(); | |
1247 | __raw_spin_lock(&hash_lock); | |
1248 | } | |
1249 | out_unlock_set: | |
1250 | __raw_spin_unlock(&hash_lock); | |
1251 | ||
d6d897ce IM |
1252 | if (!subclass) |
1253 | lock->class_cache = class; | |
fbb9ce95 IM |
1254 | |
1255 | DEBUG_LOCKS_WARN_ON(class->subclass != subclass); | |
1256 | ||
1257 | return class; | |
1258 | } | |
1259 | ||
1260 | /* | |
1261 | * Look up a dependency chain. If the key is not present yet then | |
1262 | * add it and return 0 - in this case the new dependency chain is | |
1263 | * validated. If the key is already hashed, return 1. | |
1264 | */ | |
1265 | static inline int lookup_chain_cache(u64 chain_key) | |
1266 | { | |
1267 | struct list_head *hash_head = chainhashentry(chain_key); | |
1268 | struct lock_chain *chain; | |
1269 | ||
1270 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); | |
1271 | /* | |
1272 | * We can walk it lock-free, because entries only get added | |
1273 | * to the hash: | |
1274 | */ | |
1275 | list_for_each_entry(chain, hash_head, entry) { | |
1276 | if (chain->chain_key == chain_key) { | |
1277 | cache_hit: | |
1278 | debug_atomic_inc(&chain_lookup_hits); | |
1279 | /* | |
1280 | * In the debugging case, force redundant checking | |
1281 | * by returning 1: | |
1282 | */ | |
1283 | #ifdef CONFIG_DEBUG_LOCKDEP | |
1284 | __raw_spin_lock(&hash_lock); | |
1285 | return 1; | |
1286 | #endif | |
1287 | return 0; | |
1288 | } | |
1289 | } | |
1290 | /* | |
1291 | * Allocate a new chain entry from the static array, and add | |
1292 | * it to the hash: | |
1293 | */ | |
1294 | __raw_spin_lock(&hash_lock); | |
1295 | /* | |
1296 | * We have to walk the chain again locked - to avoid duplicates: | |
1297 | */ | |
1298 | list_for_each_entry(chain, hash_head, entry) { | |
1299 | if (chain->chain_key == chain_key) { | |
1300 | __raw_spin_unlock(&hash_lock); | |
1301 | goto cache_hit; | |
1302 | } | |
1303 | } | |
1304 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { | |
1305 | __raw_spin_unlock(&hash_lock); | |
1306 | debug_locks_off(); | |
1307 | printk("BUG: MAX_LOCKDEP_CHAINS too low!\n"); | |
1308 | printk("turning off the locking correctness validator.\n"); | |
1309 | return 0; | |
1310 | } | |
1311 | chain = lock_chains + nr_lock_chains++; | |
1312 | chain->chain_key = chain_key; | |
1313 | list_add_tail_rcu(&chain->entry, hash_head); | |
1314 | debug_atomic_inc(&chain_lookup_misses); | |
1315 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1316 | if (current->hardirq_context) | |
1317 | nr_hardirq_chains++; | |
1318 | else { | |
1319 | if (current->softirq_context) | |
1320 | nr_softirq_chains++; | |
1321 | else | |
1322 | nr_process_chains++; | |
1323 | } | |
1324 | #else | |
1325 | nr_process_chains++; | |
1326 | #endif | |
1327 | ||
1328 | return 1; | |
1329 | } | |
1330 | ||
1331 | /* | |
1332 | * We are building curr_chain_key incrementally, so double-check | |
1333 | * it from scratch, to make sure that it's done correctly: | |
1334 | */ | |
1335 | static void check_chain_key(struct task_struct *curr) | |
1336 | { | |
1337 | #ifdef CONFIG_DEBUG_LOCKDEP | |
1338 | struct held_lock *hlock, *prev_hlock = NULL; | |
1339 | unsigned int i, id; | |
1340 | u64 chain_key = 0; | |
1341 | ||
1342 | for (i = 0; i < curr->lockdep_depth; i++) { | |
1343 | hlock = curr->held_locks + i; | |
1344 | if (chain_key != hlock->prev_chain_key) { | |
1345 | debug_locks_off(); | |
1346 | printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n", | |
1347 | curr->lockdep_depth, i, | |
1348 | (unsigned long long)chain_key, | |
1349 | (unsigned long long)hlock->prev_chain_key); | |
1350 | WARN_ON(1); | |
1351 | return; | |
1352 | } | |
1353 | id = hlock->class - lock_classes; | |
1354 | DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS); | |
1355 | if (prev_hlock && (prev_hlock->irq_context != | |
1356 | hlock->irq_context)) | |
1357 | chain_key = 0; | |
1358 | chain_key = iterate_chain_key(chain_key, id); | |
1359 | prev_hlock = hlock; | |
1360 | } | |
1361 | if (chain_key != curr->curr_chain_key) { | |
1362 | debug_locks_off(); | |
1363 | printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n", | |
1364 | curr->lockdep_depth, i, | |
1365 | (unsigned long long)chain_key, | |
1366 | (unsigned long long)curr->curr_chain_key); | |
1367 | WARN_ON(1); | |
1368 | } | |
1369 | #endif | |
1370 | } | |
1371 | ||
1372 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1373 | ||
1374 | /* | |
1375 | * print irq inversion bug: | |
1376 | */ | |
1377 | static int | |
1378 | print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other, | |
1379 | struct held_lock *this, int forwards, | |
1380 | const char *irqclass) | |
1381 | { | |
1382 | __raw_spin_unlock(&hash_lock); | |
1383 | debug_locks_off(); | |
1384 | if (debug_locks_silent) | |
1385 | return 0; | |
1386 | ||
1387 | printk("\n=========================================================\n"); | |
1388 | printk( "[ INFO: possible irq lock inversion dependency detected ]\n"); | |
99de055a | 1389 | print_kernel_version(); |
fbb9ce95 IM |
1390 | printk( "---------------------------------------------------------\n"); |
1391 | printk("%s/%d just changed the state of lock:\n", | |
1392 | curr->comm, curr->pid); | |
1393 | print_lock(this); | |
1394 | if (forwards) | |
1395 | printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass); | |
1396 | else | |
1397 | printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass); | |
1398 | print_lock_name(other); | |
1399 | printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); | |
1400 | ||
1401 | printk("\nother info that might help us debug this:\n"); | |
1402 | lockdep_print_held_locks(curr); | |
1403 | ||
1404 | printk("\nthe first lock's dependencies:\n"); | |
1405 | print_lock_dependencies(this->class, 0); | |
1406 | ||
1407 | printk("\nthe second lock's dependencies:\n"); | |
1408 | print_lock_dependencies(other, 0); | |
1409 | ||
1410 | printk("\nstack backtrace:\n"); | |
1411 | dump_stack(); | |
1412 | ||
1413 | return 0; | |
1414 | } | |
1415 | ||
1416 | /* | |
1417 | * Prove that in the forwards-direction subgraph starting at <this> | |
1418 | * there is no lock matching <mask>: | |
1419 | */ | |
1420 | static int | |
1421 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, | |
1422 | enum lock_usage_bit bit, const char *irqclass) | |
1423 | { | |
1424 | int ret; | |
1425 | ||
1426 | find_usage_bit = bit; | |
1427 | /* fills in <forwards_match> */ | |
1428 | ret = find_usage_forwards(this->class, 0); | |
1429 | if (!ret || ret == 1) | |
1430 | return ret; | |
1431 | ||
1432 | return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass); | |
1433 | } | |
1434 | ||
1435 | /* | |
1436 | * Prove that in the backwards-direction subgraph starting at <this> | |
1437 | * there is no lock matching <mask>: | |
1438 | */ | |
1439 | static int | |
1440 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, | |
1441 | enum lock_usage_bit bit, const char *irqclass) | |
1442 | { | |
1443 | int ret; | |
1444 | ||
1445 | find_usage_bit = bit; | |
1446 | /* fills in <backwards_match> */ | |
1447 | ret = find_usage_backwards(this->class, 0); | |
1448 | if (!ret || ret == 1) | |
1449 | return ret; | |
1450 | ||
1451 | return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass); | |
1452 | } | |
1453 | ||
1454 | static inline void print_irqtrace_events(struct task_struct *curr) | |
1455 | { | |
1456 | printk("irq event stamp: %u\n", curr->irq_events); | |
1457 | printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event); | |
1458 | print_ip_sym(curr->hardirq_enable_ip); | |
1459 | printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event); | |
1460 | print_ip_sym(curr->hardirq_disable_ip); | |
1461 | printk("softirqs last enabled at (%u): ", curr->softirq_enable_event); | |
1462 | print_ip_sym(curr->softirq_enable_ip); | |
1463 | printk("softirqs last disabled at (%u): ", curr->softirq_disable_event); | |
1464 | print_ip_sym(curr->softirq_disable_ip); | |
1465 | } | |
1466 | ||
1467 | #else | |
1468 | static inline void print_irqtrace_events(struct task_struct *curr) | |
1469 | { | |
1470 | } | |
1471 | #endif | |
1472 | ||
1473 | static int | |
1474 | print_usage_bug(struct task_struct *curr, struct held_lock *this, | |
1475 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) | |
1476 | { | |
1477 | __raw_spin_unlock(&hash_lock); | |
1478 | debug_locks_off(); | |
1479 | if (debug_locks_silent) | |
1480 | return 0; | |
1481 | ||
1482 | printk("\n=================================\n"); | |
1483 | printk( "[ INFO: inconsistent lock state ]\n"); | |
99de055a | 1484 | print_kernel_version(); |
fbb9ce95 IM |
1485 | printk( "---------------------------------\n"); |
1486 | ||
1487 | printk("inconsistent {%s} -> {%s} usage.\n", | |
1488 | usage_str[prev_bit], usage_str[new_bit]); | |
1489 | ||
1490 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", | |
1491 | curr->comm, curr->pid, | |
1492 | trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, | |
1493 | trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, | |
1494 | trace_hardirqs_enabled(curr), | |
1495 | trace_softirqs_enabled(curr)); | |
1496 | print_lock(this); | |
1497 | ||
1498 | printk("{%s} state was registered at:\n", usage_str[prev_bit]); | |
1499 | print_stack_trace(this->class->usage_traces + prev_bit, 1); | |
1500 | ||
1501 | print_irqtrace_events(curr); | |
1502 | printk("\nother info that might help us debug this:\n"); | |
1503 | lockdep_print_held_locks(curr); | |
1504 | ||
1505 | printk("\nstack backtrace:\n"); | |
1506 | dump_stack(); | |
1507 | ||
1508 | return 0; | |
1509 | } | |
1510 | ||
1511 | /* | |
1512 | * Print out an error if an invalid bit is set: | |
1513 | */ | |
1514 | static inline int | |
1515 | valid_state(struct task_struct *curr, struct held_lock *this, | |
1516 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) | |
1517 | { | |
1518 | if (unlikely(this->class->usage_mask & (1 << bad_bit))) | |
1519 | return print_usage_bug(curr, this, bad_bit, new_bit); | |
1520 | return 1; | |
1521 | } | |
1522 | ||
1523 | #define STRICT_READ_CHECKS 1 | |
1524 | ||
1525 | /* | |
1526 | * Mark a lock with a usage bit, and validate the state transition: | |
1527 | */ | |
1528 | static int mark_lock(struct task_struct *curr, struct held_lock *this, | |
1529 | enum lock_usage_bit new_bit, unsigned long ip) | |
1530 | { | |
1531 | unsigned int new_mask = 1 << new_bit, ret = 1; | |
1532 | ||
1533 | /* | |
1534 | * If already set then do not dirty the cacheline, | |
1535 | * nor do any checks: | |
1536 | */ | |
1537 | if (likely(this->class->usage_mask & new_mask)) | |
1538 | return 1; | |
1539 | ||
1540 | __raw_spin_lock(&hash_lock); | |
1541 | /* | |
1542 | * Make sure we didnt race: | |
1543 | */ | |
1544 | if (unlikely(this->class->usage_mask & new_mask)) { | |
1545 | __raw_spin_unlock(&hash_lock); | |
1546 | return 1; | |
1547 | } | |
1548 | ||
1549 | this->class->usage_mask |= new_mask; | |
1550 | ||
1551 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1552 | if (new_bit == LOCK_ENABLED_HARDIRQS || | |
1553 | new_bit == LOCK_ENABLED_HARDIRQS_READ) | |
1554 | ip = curr->hardirq_enable_ip; | |
1555 | else if (new_bit == LOCK_ENABLED_SOFTIRQS || | |
1556 | new_bit == LOCK_ENABLED_SOFTIRQS_READ) | |
1557 | ip = curr->softirq_enable_ip; | |
1558 | #endif | |
1559 | if (!save_trace(this->class->usage_traces + new_bit)) | |
1560 | return 0; | |
1561 | ||
1562 | switch (new_bit) { | |
1563 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1564 | case LOCK_USED_IN_HARDIRQ: | |
1565 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS)) | |
1566 | return 0; | |
1567 | if (!valid_state(curr, this, new_bit, | |
1568 | LOCK_ENABLED_HARDIRQS_READ)) | |
1569 | return 0; | |
1570 | /* | |
1571 | * just marked it hardirq-safe, check that this lock | |
1572 | * took no hardirq-unsafe lock in the past: | |
1573 | */ | |
1574 | if (!check_usage_forwards(curr, this, | |
1575 | LOCK_ENABLED_HARDIRQS, "hard")) | |
1576 | return 0; | |
1577 | #if STRICT_READ_CHECKS | |
1578 | /* | |
1579 | * just marked it hardirq-safe, check that this lock | |
1580 | * took no hardirq-unsafe-read lock in the past: | |
1581 | */ | |
1582 | if (!check_usage_forwards(curr, this, | |
1583 | LOCK_ENABLED_HARDIRQS_READ, "hard-read")) | |
1584 | return 0; | |
1585 | #endif | |
1586 | if (hardirq_verbose(this->class)) | |
1587 | ret = 2; | |
1588 | break; | |
1589 | case LOCK_USED_IN_SOFTIRQ: | |
1590 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS)) | |
1591 | return 0; | |
1592 | if (!valid_state(curr, this, new_bit, | |
1593 | LOCK_ENABLED_SOFTIRQS_READ)) | |
1594 | return 0; | |
1595 | /* | |
1596 | * just marked it softirq-safe, check that this lock | |
1597 | * took no softirq-unsafe lock in the past: | |
1598 | */ | |
1599 | if (!check_usage_forwards(curr, this, | |
1600 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
1601 | return 0; | |
1602 | #if STRICT_READ_CHECKS | |
1603 | /* | |
1604 | * just marked it softirq-safe, check that this lock | |
1605 | * took no softirq-unsafe-read lock in the past: | |
1606 | */ | |
1607 | if (!check_usage_forwards(curr, this, | |
1608 | LOCK_ENABLED_SOFTIRQS_READ, "soft-read")) | |
1609 | return 0; | |
1610 | #endif | |
1611 | if (softirq_verbose(this->class)) | |
1612 | ret = 2; | |
1613 | break; | |
1614 | case LOCK_USED_IN_HARDIRQ_READ: | |
1615 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS)) | |
1616 | return 0; | |
1617 | /* | |
1618 | * just marked it hardirq-read-safe, check that this lock | |
1619 | * took no hardirq-unsafe lock in the past: | |
1620 | */ | |
1621 | if (!check_usage_forwards(curr, this, | |
1622 | LOCK_ENABLED_HARDIRQS, "hard")) | |
1623 | return 0; | |
1624 | if (hardirq_verbose(this->class)) | |
1625 | ret = 2; | |
1626 | break; | |
1627 | case LOCK_USED_IN_SOFTIRQ_READ: | |
1628 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS)) | |
1629 | return 0; | |
1630 | /* | |
1631 | * just marked it softirq-read-safe, check that this lock | |
1632 | * took no softirq-unsafe lock in the past: | |
1633 | */ | |
1634 | if (!check_usage_forwards(curr, this, | |
1635 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
1636 | return 0; | |
1637 | if (softirq_verbose(this->class)) | |
1638 | ret = 2; | |
1639 | break; | |
1640 | case LOCK_ENABLED_HARDIRQS: | |
1641 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ)) | |
1642 | return 0; | |
1643 | if (!valid_state(curr, this, new_bit, | |
1644 | LOCK_USED_IN_HARDIRQ_READ)) | |
1645 | return 0; | |
1646 | /* | |
1647 | * just marked it hardirq-unsafe, check that no hardirq-safe | |
1648 | * lock in the system ever took it in the past: | |
1649 | */ | |
1650 | if (!check_usage_backwards(curr, this, | |
1651 | LOCK_USED_IN_HARDIRQ, "hard")) | |
1652 | return 0; | |
1653 | #if STRICT_READ_CHECKS | |
1654 | /* | |
1655 | * just marked it hardirq-unsafe, check that no | |
1656 | * hardirq-safe-read lock in the system ever took | |
1657 | * it in the past: | |
1658 | */ | |
1659 | if (!check_usage_backwards(curr, this, | |
1660 | LOCK_USED_IN_HARDIRQ_READ, "hard-read")) | |
1661 | return 0; | |
1662 | #endif | |
1663 | if (hardirq_verbose(this->class)) | |
1664 | ret = 2; | |
1665 | break; | |
1666 | case LOCK_ENABLED_SOFTIRQS: | |
1667 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ)) | |
1668 | return 0; | |
1669 | if (!valid_state(curr, this, new_bit, | |
1670 | LOCK_USED_IN_SOFTIRQ_READ)) | |
1671 | return 0; | |
1672 | /* | |
1673 | * just marked it softirq-unsafe, check that no softirq-safe | |
1674 | * lock in the system ever took it in the past: | |
1675 | */ | |
1676 | if (!check_usage_backwards(curr, this, | |
1677 | LOCK_USED_IN_SOFTIRQ, "soft")) | |
1678 | return 0; | |
1679 | #if STRICT_READ_CHECKS | |
1680 | /* | |
1681 | * just marked it softirq-unsafe, check that no | |
1682 | * softirq-safe-read lock in the system ever took | |
1683 | * it in the past: | |
1684 | */ | |
1685 | if (!check_usage_backwards(curr, this, | |
1686 | LOCK_USED_IN_SOFTIRQ_READ, "soft-read")) | |
1687 | return 0; | |
1688 | #endif | |
1689 | if (softirq_verbose(this->class)) | |
1690 | ret = 2; | |
1691 | break; | |
1692 | case LOCK_ENABLED_HARDIRQS_READ: | |
1693 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ)) | |
1694 | return 0; | |
1695 | #if STRICT_READ_CHECKS | |
1696 | /* | |
1697 | * just marked it hardirq-read-unsafe, check that no | |
1698 | * hardirq-safe lock in the system ever took it in the past: | |
1699 | */ | |
1700 | if (!check_usage_backwards(curr, this, | |
1701 | LOCK_USED_IN_HARDIRQ, "hard")) | |
1702 | return 0; | |
1703 | #endif | |
1704 | if (hardirq_verbose(this->class)) | |
1705 | ret = 2; | |
1706 | break; | |
1707 | case LOCK_ENABLED_SOFTIRQS_READ: | |
1708 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ)) | |
1709 | return 0; | |
1710 | #if STRICT_READ_CHECKS | |
1711 | /* | |
1712 | * just marked it softirq-read-unsafe, check that no | |
1713 | * softirq-safe lock in the system ever took it in the past: | |
1714 | */ | |
1715 | if (!check_usage_backwards(curr, this, | |
1716 | LOCK_USED_IN_SOFTIRQ, "soft")) | |
1717 | return 0; | |
1718 | #endif | |
1719 | if (softirq_verbose(this->class)) | |
1720 | ret = 2; | |
1721 | break; | |
1722 | #endif | |
1723 | case LOCK_USED: | |
1724 | /* | |
1725 | * Add it to the global list of classes: | |
1726 | */ | |
1727 | list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes); | |
1728 | debug_atomic_dec(&nr_unused_locks); | |
1729 | break; | |
1730 | default: | |
1731 | debug_locks_off(); | |
1732 | WARN_ON(1); | |
1733 | return 0; | |
1734 | } | |
1735 | ||
1736 | __raw_spin_unlock(&hash_lock); | |
1737 | ||
1738 | /* | |
1739 | * We must printk outside of the hash_lock: | |
1740 | */ | |
1741 | if (ret == 2) { | |
1742 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); | |
1743 | print_lock(this); | |
1744 | print_irqtrace_events(curr); | |
1745 | dump_stack(); | |
1746 | } | |
1747 | ||
1748 | return ret; | |
1749 | } | |
1750 | ||
1751 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1752 | /* | |
1753 | * Mark all held locks with a usage bit: | |
1754 | */ | |
1755 | static int | |
1756 | mark_held_locks(struct task_struct *curr, int hardirq, unsigned long ip) | |
1757 | { | |
1758 | enum lock_usage_bit usage_bit; | |
1759 | struct held_lock *hlock; | |
1760 | int i; | |
1761 | ||
1762 | for (i = 0; i < curr->lockdep_depth; i++) { | |
1763 | hlock = curr->held_locks + i; | |
1764 | ||
1765 | if (hardirq) { | |
1766 | if (hlock->read) | |
1767 | usage_bit = LOCK_ENABLED_HARDIRQS_READ; | |
1768 | else | |
1769 | usage_bit = LOCK_ENABLED_HARDIRQS; | |
1770 | } else { | |
1771 | if (hlock->read) | |
1772 | usage_bit = LOCK_ENABLED_SOFTIRQS_READ; | |
1773 | else | |
1774 | usage_bit = LOCK_ENABLED_SOFTIRQS; | |
1775 | } | |
1776 | if (!mark_lock(curr, hlock, usage_bit, ip)) | |
1777 | return 0; | |
1778 | } | |
1779 | ||
1780 | return 1; | |
1781 | } | |
1782 | ||
1783 | /* | |
1784 | * Debugging helper: via this flag we know that we are in | |
1785 | * 'early bootup code', and will warn about any invalid irqs-on event: | |
1786 | */ | |
1787 | static int early_boot_irqs_enabled; | |
1788 | ||
1789 | void early_boot_irqs_off(void) | |
1790 | { | |
1791 | early_boot_irqs_enabled = 0; | |
1792 | } | |
1793 | ||
1794 | void early_boot_irqs_on(void) | |
1795 | { | |
1796 | early_boot_irqs_enabled = 1; | |
1797 | } | |
1798 | ||
1799 | /* | |
1800 | * Hardirqs will be enabled: | |
1801 | */ | |
1802 | void trace_hardirqs_on(void) | |
1803 | { | |
1804 | struct task_struct *curr = current; | |
1805 | unsigned long ip; | |
1806 | ||
1807 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
1808 | return; | |
1809 | ||
1810 | if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled))) | |
1811 | return; | |
1812 | ||
1813 | if (unlikely(curr->hardirqs_enabled)) { | |
1814 | debug_atomic_inc(&redundant_hardirqs_on); | |
1815 | return; | |
1816 | } | |
1817 | /* we'll do an OFF -> ON transition: */ | |
1818 | curr->hardirqs_enabled = 1; | |
1819 | ip = (unsigned long) __builtin_return_address(0); | |
1820 | ||
1821 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1822 | return; | |
1823 | if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) | |
1824 | return; | |
1825 | /* | |
1826 | * We are going to turn hardirqs on, so set the | |
1827 | * usage bit for all held locks: | |
1828 | */ | |
1829 | if (!mark_held_locks(curr, 1, ip)) | |
1830 | return; | |
1831 | /* | |
1832 | * If we have softirqs enabled, then set the usage | |
1833 | * bit for all held locks. (disabled hardirqs prevented | |
1834 | * this bit from being set before) | |
1835 | */ | |
1836 | if (curr->softirqs_enabled) | |
1837 | if (!mark_held_locks(curr, 0, ip)) | |
1838 | return; | |
1839 | ||
1840 | curr->hardirq_enable_ip = ip; | |
1841 | curr->hardirq_enable_event = ++curr->irq_events; | |
1842 | debug_atomic_inc(&hardirqs_on_events); | |
1843 | } | |
1844 | ||
1845 | EXPORT_SYMBOL(trace_hardirqs_on); | |
1846 | ||
1847 | /* | |
1848 | * Hardirqs were disabled: | |
1849 | */ | |
1850 | void trace_hardirqs_off(void) | |
1851 | { | |
1852 | struct task_struct *curr = current; | |
1853 | ||
1854 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
1855 | return; | |
1856 | ||
1857 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1858 | return; | |
1859 | ||
1860 | if (curr->hardirqs_enabled) { | |
1861 | /* | |
1862 | * We have done an ON -> OFF transition: | |
1863 | */ | |
1864 | curr->hardirqs_enabled = 0; | |
1865 | curr->hardirq_disable_ip = _RET_IP_; | |
1866 | curr->hardirq_disable_event = ++curr->irq_events; | |
1867 | debug_atomic_inc(&hardirqs_off_events); | |
1868 | } else | |
1869 | debug_atomic_inc(&redundant_hardirqs_off); | |
1870 | } | |
1871 | ||
1872 | EXPORT_SYMBOL(trace_hardirqs_off); | |
1873 | ||
1874 | /* | |
1875 | * Softirqs will be enabled: | |
1876 | */ | |
1877 | void trace_softirqs_on(unsigned long ip) | |
1878 | { | |
1879 | struct task_struct *curr = current; | |
1880 | ||
1881 | if (unlikely(!debug_locks)) | |
1882 | return; | |
1883 | ||
1884 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1885 | return; | |
1886 | ||
1887 | if (curr->softirqs_enabled) { | |
1888 | debug_atomic_inc(&redundant_softirqs_on); | |
1889 | return; | |
1890 | } | |
1891 | ||
1892 | /* | |
1893 | * We'll do an OFF -> ON transition: | |
1894 | */ | |
1895 | curr->softirqs_enabled = 1; | |
1896 | curr->softirq_enable_ip = ip; | |
1897 | curr->softirq_enable_event = ++curr->irq_events; | |
1898 | debug_atomic_inc(&softirqs_on_events); | |
1899 | /* | |
1900 | * We are going to turn softirqs on, so set the | |
1901 | * usage bit for all held locks, if hardirqs are | |
1902 | * enabled too: | |
1903 | */ | |
1904 | if (curr->hardirqs_enabled) | |
1905 | mark_held_locks(curr, 0, ip); | |
1906 | } | |
1907 | ||
1908 | /* | |
1909 | * Softirqs were disabled: | |
1910 | */ | |
1911 | void trace_softirqs_off(unsigned long ip) | |
1912 | { | |
1913 | struct task_struct *curr = current; | |
1914 | ||
1915 | if (unlikely(!debug_locks)) | |
1916 | return; | |
1917 | ||
1918 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1919 | return; | |
1920 | ||
1921 | if (curr->softirqs_enabled) { | |
1922 | /* | |
1923 | * We have done an ON -> OFF transition: | |
1924 | */ | |
1925 | curr->softirqs_enabled = 0; | |
1926 | curr->softirq_disable_ip = ip; | |
1927 | curr->softirq_disable_event = ++curr->irq_events; | |
1928 | debug_atomic_inc(&softirqs_off_events); | |
1929 | DEBUG_LOCKS_WARN_ON(!softirq_count()); | |
1930 | } else | |
1931 | debug_atomic_inc(&redundant_softirqs_off); | |
1932 | } | |
1933 | ||
1934 | #endif | |
1935 | ||
1936 | /* | |
1937 | * Initialize a lock instance's lock-class mapping info: | |
1938 | */ | |
1939 | void lockdep_init_map(struct lockdep_map *lock, const char *name, | |
1940 | struct lock_class_key *key) | |
1941 | { | |
1942 | if (unlikely(!debug_locks)) | |
1943 | return; | |
1944 | ||
1945 | if (DEBUG_LOCKS_WARN_ON(!key)) | |
1946 | return; | |
1947 | if (DEBUG_LOCKS_WARN_ON(!name)) | |
1948 | return; | |
1949 | /* | |
1950 | * Sanity check, the lock-class key must be persistent: | |
1951 | */ | |
1952 | if (!static_obj(key)) { | |
1953 | printk("BUG: key %p not in .data!\n", key); | |
1954 | DEBUG_LOCKS_WARN_ON(1); | |
1955 | return; | |
1956 | } | |
1957 | lock->name = name; | |
1958 | lock->key = key; | |
d6d897ce | 1959 | lock->class_cache = NULL; |
fbb9ce95 IM |
1960 | } |
1961 | ||
1962 | EXPORT_SYMBOL_GPL(lockdep_init_map); | |
1963 | ||
1964 | /* | |
1965 | * This gets called for every mutex_lock*()/spin_lock*() operation. | |
1966 | * We maintain the dependency maps and validate the locking attempt: | |
1967 | */ | |
1968 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
1969 | int trylock, int read, int check, int hardirqs_off, | |
1970 | unsigned long ip) | |
1971 | { | |
1972 | struct task_struct *curr = current; | |
d6d897ce | 1973 | struct lock_class *class = NULL; |
fbb9ce95 | 1974 | struct held_lock *hlock; |
fbb9ce95 IM |
1975 | unsigned int depth, id; |
1976 | int chain_head = 0; | |
1977 | u64 chain_key; | |
1978 | ||
1979 | if (unlikely(!debug_locks)) | |
1980 | return 0; | |
1981 | ||
1982 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1983 | return 0; | |
1984 | ||
1985 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { | |
1986 | debug_locks_off(); | |
1987 | printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n"); | |
1988 | printk("turning off the locking correctness validator.\n"); | |
1989 | return 0; | |
1990 | } | |
1991 | ||
d6d897ce IM |
1992 | if (!subclass) |
1993 | class = lock->class_cache; | |
1994 | /* | |
1995 | * Not cached yet or subclass? | |
1996 | */ | |
fbb9ce95 IM |
1997 | if (unlikely(!class)) { |
1998 | class = register_lock_class(lock, subclass); | |
1999 | if (!class) | |
2000 | return 0; | |
2001 | } | |
2002 | debug_atomic_inc((atomic_t *)&class->ops); | |
2003 | if (very_verbose(class)) { | |
2004 | printk("\nacquire class [%p] %s", class->key, class->name); | |
2005 | if (class->name_version > 1) | |
2006 | printk("#%d", class->name_version); | |
2007 | printk("\n"); | |
2008 | dump_stack(); | |
2009 | } | |
2010 | ||
2011 | /* | |
2012 | * Add the lock to the list of currently held locks. | |
2013 | * (we dont increase the depth just yet, up until the | |
2014 | * dependency checks are done) | |
2015 | */ | |
2016 | depth = curr->lockdep_depth; | |
2017 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) | |
2018 | return 0; | |
2019 | ||
2020 | hlock = curr->held_locks + depth; | |
2021 | ||
2022 | hlock->class = class; | |
2023 | hlock->acquire_ip = ip; | |
2024 | hlock->instance = lock; | |
2025 | hlock->trylock = trylock; | |
2026 | hlock->read = read; | |
2027 | hlock->check = check; | |
2028 | hlock->hardirqs_off = hardirqs_off; | |
2029 | ||
2030 | if (check != 2) | |
2031 | goto out_calc_hash; | |
2032 | #ifdef CONFIG_TRACE_IRQFLAGS | |
2033 | /* | |
2034 | * If non-trylock use in a hardirq or softirq context, then | |
2035 | * mark the lock as used in these contexts: | |
2036 | */ | |
2037 | if (!trylock) { | |
2038 | if (read) { | |
2039 | if (curr->hardirq_context) | |
2040 | if (!mark_lock(curr, hlock, | |
2041 | LOCK_USED_IN_HARDIRQ_READ, ip)) | |
2042 | return 0; | |
2043 | if (curr->softirq_context) | |
2044 | if (!mark_lock(curr, hlock, | |
2045 | LOCK_USED_IN_SOFTIRQ_READ, ip)) | |
2046 | return 0; | |
2047 | } else { | |
2048 | if (curr->hardirq_context) | |
2049 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ, ip)) | |
2050 | return 0; | |
2051 | if (curr->softirq_context) | |
2052 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ, ip)) | |
2053 | return 0; | |
2054 | } | |
2055 | } | |
2056 | if (!hardirqs_off) { | |
2057 | if (read) { | |
2058 | if (!mark_lock(curr, hlock, | |
2059 | LOCK_ENABLED_HARDIRQS_READ, ip)) | |
2060 | return 0; | |
2061 | if (curr->softirqs_enabled) | |
2062 | if (!mark_lock(curr, hlock, | |
2063 | LOCK_ENABLED_SOFTIRQS_READ, ip)) | |
2064 | return 0; | |
2065 | } else { | |
2066 | if (!mark_lock(curr, hlock, | |
2067 | LOCK_ENABLED_HARDIRQS, ip)) | |
2068 | return 0; | |
2069 | if (curr->softirqs_enabled) | |
2070 | if (!mark_lock(curr, hlock, | |
2071 | LOCK_ENABLED_SOFTIRQS, ip)) | |
2072 | return 0; | |
2073 | } | |
2074 | } | |
2075 | #endif | |
2076 | /* mark it as used: */ | |
2077 | if (!mark_lock(curr, hlock, LOCK_USED, ip)) | |
2078 | return 0; | |
2079 | out_calc_hash: | |
2080 | /* | |
2081 | * Calculate the chain hash: it's the combined has of all the | |
2082 | * lock keys along the dependency chain. We save the hash value | |
2083 | * at every step so that we can get the current hash easily | |
2084 | * after unlock. The chain hash is then used to cache dependency | |
2085 | * results. | |
2086 | * | |
2087 | * The 'key ID' is what is the most compact key value to drive | |
2088 | * the hash, not class->key. | |
2089 | */ | |
2090 | id = class - lock_classes; | |
2091 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) | |
2092 | return 0; | |
2093 | ||
2094 | chain_key = curr->curr_chain_key; | |
2095 | if (!depth) { | |
2096 | if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) | |
2097 | return 0; | |
2098 | chain_head = 1; | |
2099 | } | |
2100 | ||
2101 | hlock->prev_chain_key = chain_key; | |
2102 | ||
2103 | #ifdef CONFIG_TRACE_IRQFLAGS | |
2104 | /* | |
2105 | * Keep track of points where we cross into an interrupt context: | |
2106 | */ | |
2107 | hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) + | |
2108 | curr->softirq_context; | |
2109 | if (depth) { | |
2110 | struct held_lock *prev_hlock; | |
2111 | ||
2112 | prev_hlock = curr->held_locks + depth-1; | |
2113 | /* | |
2114 | * If we cross into another context, reset the | |
2115 | * hash key (this also prevents the checking and the | |
2116 | * adding of the dependency to 'prev'): | |
2117 | */ | |
2118 | if (prev_hlock->irq_context != hlock->irq_context) { | |
2119 | chain_key = 0; | |
2120 | chain_head = 1; | |
2121 | } | |
2122 | } | |
2123 | #endif | |
2124 | chain_key = iterate_chain_key(chain_key, id); | |
2125 | curr->curr_chain_key = chain_key; | |
2126 | ||
2127 | /* | |
2128 | * Trylock needs to maintain the stack of held locks, but it | |
2129 | * does not add new dependencies, because trylock can be done | |
2130 | * in any order. | |
2131 | * | |
2132 | * We look up the chain_key and do the O(N^2) check and update of | |
2133 | * the dependencies only if this is a new dependency chain. | |
2134 | * (If lookup_chain_cache() returns with 1 it acquires | |
2135 | * hash_lock for us) | |
2136 | */ | |
2137 | if (!trylock && (check == 2) && lookup_chain_cache(chain_key)) { | |
2138 | /* | |
2139 | * Check whether last held lock: | |
2140 | * | |
2141 | * - is irq-safe, if this lock is irq-unsafe | |
2142 | * - is softirq-safe, if this lock is hardirq-unsafe | |
2143 | * | |
2144 | * And check whether the new lock's dependency graph | |
2145 | * could lead back to the previous lock. | |
2146 | * | |
2147 | * any of these scenarios could lead to a deadlock. If | |
2148 | * All validations | |
2149 | */ | |
2150 | int ret = check_deadlock(curr, hlock, lock, read); | |
2151 | ||
2152 | if (!ret) | |
2153 | return 0; | |
2154 | /* | |
2155 | * Mark recursive read, as we jump over it when | |
2156 | * building dependencies (just like we jump over | |
2157 | * trylock entries): | |
2158 | */ | |
2159 | if (ret == 2) | |
2160 | hlock->read = 2; | |
2161 | /* | |
2162 | * Add dependency only if this lock is not the head | |
2163 | * of the chain, and if it's not a secondary read-lock: | |
2164 | */ | |
2165 | if (!chain_head && ret != 2) | |
2166 | if (!check_prevs_add(curr, hlock)) | |
2167 | return 0; | |
2168 | __raw_spin_unlock(&hash_lock); | |
2169 | } | |
2170 | curr->lockdep_depth++; | |
2171 | check_chain_key(curr); | |
2172 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { | |
2173 | debug_locks_off(); | |
2174 | printk("BUG: MAX_LOCK_DEPTH too low!\n"); | |
2175 | printk("turning off the locking correctness validator.\n"); | |
2176 | return 0; | |
2177 | } | |
2178 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) | |
2179 | max_lockdep_depth = curr->lockdep_depth; | |
2180 | ||
2181 | return 1; | |
2182 | } | |
2183 | ||
2184 | static int | |
2185 | print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock, | |
2186 | unsigned long ip) | |
2187 | { | |
2188 | if (!debug_locks_off()) | |
2189 | return 0; | |
2190 | if (debug_locks_silent) | |
2191 | return 0; | |
2192 | ||
2193 | printk("\n=====================================\n"); | |
2194 | printk( "[ BUG: bad unlock balance detected! ]\n"); | |
2195 | printk( "-------------------------------------\n"); | |
2196 | printk("%s/%d is trying to release lock (", | |
2197 | curr->comm, curr->pid); | |
2198 | print_lockdep_cache(lock); | |
2199 | printk(") at:\n"); | |
2200 | print_ip_sym(ip); | |
2201 | printk("but there are no more locks to release!\n"); | |
2202 | printk("\nother info that might help us debug this:\n"); | |
2203 | lockdep_print_held_locks(curr); | |
2204 | ||
2205 | printk("\nstack backtrace:\n"); | |
2206 | dump_stack(); | |
2207 | ||
2208 | return 0; | |
2209 | } | |
2210 | ||
2211 | /* | |
2212 | * Common debugging checks for both nested and non-nested unlock: | |
2213 | */ | |
2214 | static int check_unlock(struct task_struct *curr, struct lockdep_map *lock, | |
2215 | unsigned long ip) | |
2216 | { | |
2217 | if (unlikely(!debug_locks)) | |
2218 | return 0; | |
2219 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
2220 | return 0; | |
2221 | ||
2222 | if (curr->lockdep_depth <= 0) | |
2223 | return print_unlock_inbalance_bug(curr, lock, ip); | |
2224 | ||
2225 | return 1; | |
2226 | } | |
2227 | ||
2228 | /* | |
2229 | * Remove the lock to the list of currently held locks in a | |
2230 | * potentially non-nested (out of order) manner. This is a | |
2231 | * relatively rare operation, as all the unlock APIs default | |
2232 | * to nested mode (which uses lock_release()): | |
2233 | */ | |
2234 | static int | |
2235 | lock_release_non_nested(struct task_struct *curr, | |
2236 | struct lockdep_map *lock, unsigned long ip) | |
2237 | { | |
2238 | struct held_lock *hlock, *prev_hlock; | |
2239 | unsigned int depth; | |
2240 | int i; | |
2241 | ||
2242 | /* | |
2243 | * Check whether the lock exists in the current stack | |
2244 | * of held locks: | |
2245 | */ | |
2246 | depth = curr->lockdep_depth; | |
2247 | if (DEBUG_LOCKS_WARN_ON(!depth)) | |
2248 | return 0; | |
2249 | ||
2250 | prev_hlock = NULL; | |
2251 | for (i = depth-1; i >= 0; i--) { | |
2252 | hlock = curr->held_locks + i; | |
2253 | /* | |
2254 | * We must not cross into another context: | |
2255 | */ | |
2256 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) | |
2257 | break; | |
2258 | if (hlock->instance == lock) | |
2259 | goto found_it; | |
2260 | prev_hlock = hlock; | |
2261 | } | |
2262 | return print_unlock_inbalance_bug(curr, lock, ip); | |
2263 | ||
2264 | found_it: | |
2265 | /* | |
2266 | * We have the right lock to unlock, 'hlock' points to it. | |
2267 | * Now we remove it from the stack, and add back the other | |
2268 | * entries (if any), recalculating the hash along the way: | |
2269 | */ | |
2270 | curr->lockdep_depth = i; | |
2271 | curr->curr_chain_key = hlock->prev_chain_key; | |
2272 | ||
2273 | for (i++; i < depth; i++) { | |
2274 | hlock = curr->held_locks + i; | |
2275 | if (!__lock_acquire(hlock->instance, | |
2276 | hlock->class->subclass, hlock->trylock, | |
2277 | hlock->read, hlock->check, hlock->hardirqs_off, | |
2278 | hlock->acquire_ip)) | |
2279 | return 0; | |
2280 | } | |
2281 | ||
2282 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) | |
2283 | return 0; | |
2284 | return 1; | |
2285 | } | |
2286 | ||
2287 | /* | |
2288 | * Remove the lock to the list of currently held locks - this gets | |
2289 | * called on mutex_unlock()/spin_unlock*() (or on a failed | |
2290 | * mutex_lock_interruptible()). This is done for unlocks that nest | |
2291 | * perfectly. (i.e. the current top of the lock-stack is unlocked) | |
2292 | */ | |
2293 | static int lock_release_nested(struct task_struct *curr, | |
2294 | struct lockdep_map *lock, unsigned long ip) | |
2295 | { | |
2296 | struct held_lock *hlock; | |
2297 | unsigned int depth; | |
2298 | ||
2299 | /* | |
2300 | * Pop off the top of the lock stack: | |
2301 | */ | |
2302 | depth = curr->lockdep_depth - 1; | |
2303 | hlock = curr->held_locks + depth; | |
2304 | ||
2305 | /* | |
2306 | * Is the unlock non-nested: | |
2307 | */ | |
2308 | if (hlock->instance != lock) | |
2309 | return lock_release_non_nested(curr, lock, ip); | |
2310 | curr->lockdep_depth--; | |
2311 | ||
2312 | if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0))) | |
2313 | return 0; | |
2314 | ||
2315 | curr->curr_chain_key = hlock->prev_chain_key; | |
2316 | ||
2317 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2318 | hlock->prev_chain_key = 0; | |
2319 | hlock->class = NULL; | |
2320 | hlock->acquire_ip = 0; | |
2321 | hlock->irq_context = 0; | |
2322 | #endif | |
2323 | return 1; | |
2324 | } | |
2325 | ||
2326 | /* | |
2327 | * Remove the lock to the list of currently held locks - this gets | |
2328 | * called on mutex_unlock()/spin_unlock*() (or on a failed | |
2329 | * mutex_lock_interruptible()). This is done for unlocks that nest | |
2330 | * perfectly. (i.e. the current top of the lock-stack is unlocked) | |
2331 | */ | |
2332 | static void | |
2333 | __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) | |
2334 | { | |
2335 | struct task_struct *curr = current; | |
2336 | ||
2337 | if (!check_unlock(curr, lock, ip)) | |
2338 | return; | |
2339 | ||
2340 | if (nested) { | |
2341 | if (!lock_release_nested(curr, lock, ip)) | |
2342 | return; | |
2343 | } else { | |
2344 | if (!lock_release_non_nested(curr, lock, ip)) | |
2345 | return; | |
2346 | } | |
2347 | ||
2348 | check_chain_key(curr); | |
2349 | } | |
2350 | ||
2351 | /* | |
2352 | * Check whether we follow the irq-flags state precisely: | |
2353 | */ | |
2354 | static void check_flags(unsigned long flags) | |
2355 | { | |
2356 | #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS) | |
2357 | if (!debug_locks) | |
2358 | return; | |
2359 | ||
2360 | if (irqs_disabled_flags(flags)) | |
2361 | DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled); | |
2362 | else | |
2363 | DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled); | |
2364 | ||
2365 | /* | |
2366 | * We dont accurately track softirq state in e.g. | |
2367 | * hardirq contexts (such as on 4KSTACKS), so only | |
2368 | * check if not in hardirq contexts: | |
2369 | */ | |
2370 | if (!hardirq_count()) { | |
2371 | if (softirq_count()) | |
2372 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); | |
2373 | else | |
2374 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); | |
2375 | } | |
2376 | ||
2377 | if (!debug_locks) | |
2378 | print_irqtrace_events(current); | |
2379 | #endif | |
2380 | } | |
2381 | ||
2382 | /* | |
2383 | * We are not always called with irqs disabled - do that here, | |
2384 | * and also avoid lockdep recursion: | |
2385 | */ | |
2386 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
2387 | int trylock, int read, int check, unsigned long ip) | |
2388 | { | |
2389 | unsigned long flags; | |
2390 | ||
2391 | if (unlikely(current->lockdep_recursion)) | |
2392 | return; | |
2393 | ||
2394 | raw_local_irq_save(flags); | |
2395 | check_flags(flags); | |
2396 | ||
2397 | current->lockdep_recursion = 1; | |
2398 | __lock_acquire(lock, subclass, trylock, read, check, | |
2399 | irqs_disabled_flags(flags), ip); | |
2400 | current->lockdep_recursion = 0; | |
2401 | raw_local_irq_restore(flags); | |
2402 | } | |
2403 | ||
2404 | EXPORT_SYMBOL_GPL(lock_acquire); | |
2405 | ||
2406 | void lock_release(struct lockdep_map *lock, int nested, unsigned long ip) | |
2407 | { | |
2408 | unsigned long flags; | |
2409 | ||
2410 | if (unlikely(current->lockdep_recursion)) | |
2411 | return; | |
2412 | ||
2413 | raw_local_irq_save(flags); | |
2414 | check_flags(flags); | |
2415 | current->lockdep_recursion = 1; | |
2416 | __lock_release(lock, nested, ip); | |
2417 | current->lockdep_recursion = 0; | |
2418 | raw_local_irq_restore(flags); | |
2419 | } | |
2420 | ||
2421 | EXPORT_SYMBOL_GPL(lock_release); | |
2422 | ||
2423 | /* | |
2424 | * Used by the testsuite, sanitize the validator state | |
2425 | * after a simulated failure: | |
2426 | */ | |
2427 | ||
2428 | void lockdep_reset(void) | |
2429 | { | |
2430 | unsigned long flags; | |
2431 | ||
2432 | raw_local_irq_save(flags); | |
2433 | current->curr_chain_key = 0; | |
2434 | current->lockdep_depth = 0; | |
2435 | current->lockdep_recursion = 0; | |
2436 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); | |
2437 | nr_hardirq_chains = 0; | |
2438 | nr_softirq_chains = 0; | |
2439 | nr_process_chains = 0; | |
2440 | debug_locks = 1; | |
2441 | raw_local_irq_restore(flags); | |
2442 | } | |
2443 | ||
2444 | static void zap_class(struct lock_class *class) | |
2445 | { | |
2446 | int i; | |
2447 | ||
2448 | /* | |
2449 | * Remove all dependencies this lock is | |
2450 | * involved in: | |
2451 | */ | |
2452 | for (i = 0; i < nr_list_entries; i++) { | |
2453 | if (list_entries[i].class == class) | |
2454 | list_del_rcu(&list_entries[i].entry); | |
2455 | } | |
2456 | /* | |
2457 | * Unhash the class and remove it from the all_lock_classes list: | |
2458 | */ | |
2459 | list_del_rcu(&class->hash_entry); | |
2460 | list_del_rcu(&class->lock_entry); | |
2461 | ||
2462 | } | |
2463 | ||
2464 | static inline int within(void *addr, void *start, unsigned long size) | |
2465 | { | |
2466 | return addr >= start && addr < start + size; | |
2467 | } | |
2468 | ||
2469 | void lockdep_free_key_range(void *start, unsigned long size) | |
2470 | { | |
2471 | struct lock_class *class, *next; | |
2472 | struct list_head *head; | |
2473 | unsigned long flags; | |
2474 | int i; | |
2475 | ||
2476 | raw_local_irq_save(flags); | |
2477 | __raw_spin_lock(&hash_lock); | |
2478 | ||
2479 | /* | |
2480 | * Unhash all classes that were created by this module: | |
2481 | */ | |
2482 | for (i = 0; i < CLASSHASH_SIZE; i++) { | |
2483 | head = classhash_table + i; | |
2484 | if (list_empty(head)) | |
2485 | continue; | |
2486 | list_for_each_entry_safe(class, next, head, hash_entry) | |
2487 | if (within(class->key, start, size)) | |
2488 | zap_class(class); | |
2489 | } | |
2490 | ||
2491 | __raw_spin_unlock(&hash_lock); | |
2492 | raw_local_irq_restore(flags); | |
2493 | } | |
2494 | ||
2495 | void lockdep_reset_lock(struct lockdep_map *lock) | |
2496 | { | |
d6d897ce | 2497 | struct lock_class *class, *next; |
fbb9ce95 IM |
2498 | struct list_head *head; |
2499 | unsigned long flags; | |
2500 | int i, j; | |
2501 | ||
2502 | raw_local_irq_save(flags); | |
fbb9ce95 IM |
2503 | |
2504 | /* | |
d6d897ce IM |
2505 | * Remove all classes this lock might have: |
2506 | */ | |
2507 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { | |
2508 | /* | |
2509 | * If the class exists we look it up and zap it: | |
2510 | */ | |
2511 | class = look_up_lock_class(lock, j); | |
2512 | if (class) | |
2513 | zap_class(class); | |
2514 | } | |
2515 | /* | |
2516 | * Debug check: in the end all mapped classes should | |
2517 | * be gone. | |
fbb9ce95 | 2518 | */ |
d6d897ce | 2519 | __raw_spin_lock(&hash_lock); |
fbb9ce95 IM |
2520 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
2521 | head = classhash_table + i; | |
2522 | if (list_empty(head)) | |
2523 | continue; | |
2524 | list_for_each_entry_safe(class, next, head, hash_entry) { | |
d6d897ce IM |
2525 | if (unlikely(class == lock->class_cache)) { |
2526 | __raw_spin_unlock(&hash_lock); | |
2527 | DEBUG_LOCKS_WARN_ON(1); | |
2528 | goto out_restore; | |
fbb9ce95 IM |
2529 | } |
2530 | } | |
2531 | } | |
fbb9ce95 | 2532 | __raw_spin_unlock(&hash_lock); |
d6d897ce IM |
2533 | |
2534 | out_restore: | |
fbb9ce95 IM |
2535 | raw_local_irq_restore(flags); |
2536 | } | |
2537 | ||
2538 | void __init lockdep_init(void) | |
2539 | { | |
2540 | int i; | |
2541 | ||
2542 | /* | |
2543 | * Some architectures have their own start_kernel() | |
2544 | * code which calls lockdep_init(), while we also | |
2545 | * call lockdep_init() from the start_kernel() itself, | |
2546 | * and we want to initialize the hashes only once: | |
2547 | */ | |
2548 | if (lockdep_initialized) | |
2549 | return; | |
2550 | ||
2551 | for (i = 0; i < CLASSHASH_SIZE; i++) | |
2552 | INIT_LIST_HEAD(classhash_table + i); | |
2553 | ||
2554 | for (i = 0; i < CHAINHASH_SIZE; i++) | |
2555 | INIT_LIST_HEAD(chainhash_table + i); | |
2556 | ||
2557 | lockdep_initialized = 1; | |
2558 | } | |
2559 | ||
2560 | void __init lockdep_info(void) | |
2561 | { | |
2562 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); | |
2563 | ||
2564 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); | |
2565 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); | |
2566 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); | |
2567 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); | |
2568 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); | |
2569 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); | |
2570 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); | |
2571 | ||
2572 | printk(" memory used by lock dependency info: %lu kB\n", | |
2573 | (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + | |
2574 | sizeof(struct list_head) * CLASSHASH_SIZE + | |
2575 | sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + | |
2576 | sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + | |
2577 | sizeof(struct list_head) * CHAINHASH_SIZE) / 1024); | |
2578 | ||
2579 | printk(" per task-struct memory footprint: %lu bytes\n", | |
2580 | sizeof(struct held_lock) * MAX_LOCK_DEPTH); | |
2581 | ||
2582 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2583 | if (lockdep_init_error) | |
2584 | printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n"); | |
2585 | #endif | |
2586 | } | |
2587 | ||
2588 | static inline int in_range(const void *start, const void *addr, const void *end) | |
2589 | { | |
2590 | return addr >= start && addr <= end; | |
2591 | } | |
2592 | ||
2593 | static void | |
2594 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, | |
55794a41 | 2595 | const void *mem_to, struct held_lock *hlock) |
fbb9ce95 IM |
2596 | { |
2597 | if (!debug_locks_off()) | |
2598 | return; | |
2599 | if (debug_locks_silent) | |
2600 | return; | |
2601 | ||
2602 | printk("\n=========================\n"); | |
2603 | printk( "[ BUG: held lock freed! ]\n"); | |
2604 | printk( "-------------------------\n"); | |
2605 | printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", | |
2606 | curr->comm, curr->pid, mem_from, mem_to-1); | |
55794a41 | 2607 | print_lock(hlock); |
fbb9ce95 IM |
2608 | lockdep_print_held_locks(curr); |
2609 | ||
2610 | printk("\nstack backtrace:\n"); | |
2611 | dump_stack(); | |
2612 | } | |
2613 | ||
2614 | /* | |
2615 | * Called when kernel memory is freed (or unmapped), or if a lock | |
2616 | * is destroyed or reinitialized - this code checks whether there is | |
2617 | * any held lock in the memory range of <from> to <to>: | |
2618 | */ | |
2619 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) | |
2620 | { | |
2621 | const void *mem_to = mem_from + mem_len, *lock_from, *lock_to; | |
2622 | struct task_struct *curr = current; | |
2623 | struct held_lock *hlock; | |
2624 | unsigned long flags; | |
2625 | int i; | |
2626 | ||
2627 | if (unlikely(!debug_locks)) | |
2628 | return; | |
2629 | ||
2630 | local_irq_save(flags); | |
2631 | for (i = 0; i < curr->lockdep_depth; i++) { | |
2632 | hlock = curr->held_locks + i; | |
2633 | ||
2634 | lock_from = (void *)hlock->instance; | |
2635 | lock_to = (void *)(hlock->instance + 1); | |
2636 | ||
2637 | if (!in_range(mem_from, lock_from, mem_to) && | |
2638 | !in_range(mem_from, lock_to, mem_to)) | |
2639 | continue; | |
2640 | ||
55794a41 | 2641 | print_freed_lock_bug(curr, mem_from, mem_to, hlock); |
fbb9ce95 IM |
2642 | break; |
2643 | } | |
2644 | local_irq_restore(flags); | |
2645 | } | |
2646 | ||
2647 | static void print_held_locks_bug(struct task_struct *curr) | |
2648 | { | |
2649 | if (!debug_locks_off()) | |
2650 | return; | |
2651 | if (debug_locks_silent) | |
2652 | return; | |
2653 | ||
2654 | printk("\n=====================================\n"); | |
2655 | printk( "[ BUG: lock held at task exit time! ]\n"); | |
2656 | printk( "-------------------------------------\n"); | |
2657 | printk("%s/%d is exiting with locks still held!\n", | |
2658 | curr->comm, curr->pid); | |
2659 | lockdep_print_held_locks(curr); | |
2660 | ||
2661 | printk("\nstack backtrace:\n"); | |
2662 | dump_stack(); | |
2663 | } | |
2664 | ||
2665 | void debug_check_no_locks_held(struct task_struct *task) | |
2666 | { | |
2667 | if (unlikely(task->lockdep_depth > 0)) | |
2668 | print_held_locks_bug(task); | |
2669 | } | |
2670 | ||
2671 | void debug_show_all_locks(void) | |
2672 | { | |
2673 | struct task_struct *g, *p; | |
2674 | int count = 10; | |
2675 | int unlock = 1; | |
2676 | ||
2677 | printk("\nShowing all locks held in the system:\n"); | |
2678 | ||
2679 | /* | |
2680 | * Here we try to get the tasklist_lock as hard as possible, | |
2681 | * if not successful after 2 seconds we ignore it (but keep | |
2682 | * trying). This is to enable a debug printout even if a | |
2683 | * tasklist_lock-holding task deadlocks or crashes. | |
2684 | */ | |
2685 | retry: | |
2686 | if (!read_trylock(&tasklist_lock)) { | |
2687 | if (count == 10) | |
2688 | printk("hm, tasklist_lock locked, retrying... "); | |
2689 | if (count) { | |
2690 | count--; | |
2691 | printk(" #%d", 10-count); | |
2692 | mdelay(200); | |
2693 | goto retry; | |
2694 | } | |
2695 | printk(" ignoring it.\n"); | |
2696 | unlock = 0; | |
2697 | } | |
2698 | if (count != 10) | |
2699 | printk(" locked it.\n"); | |
2700 | ||
2701 | do_each_thread(g, p) { | |
2702 | if (p->lockdep_depth) | |
2703 | lockdep_print_held_locks(p); | |
2704 | if (!unlock) | |
2705 | if (read_trylock(&tasklist_lock)) | |
2706 | unlock = 1; | |
2707 | } while_each_thread(g, p); | |
2708 | ||
2709 | printk("\n"); | |
2710 | printk("=============================================\n\n"); | |
2711 | ||
2712 | if (unlock) | |
2713 | read_unlock(&tasklist_lock); | |
2714 | } | |
2715 | ||
2716 | EXPORT_SYMBOL_GPL(debug_show_all_locks); | |
2717 | ||
2718 | void debug_show_held_locks(struct task_struct *task) | |
2719 | { | |
2720 | lockdep_print_held_locks(task); | |
2721 | } | |
2722 | ||
2723 | EXPORT_SYMBOL_GPL(debug_show_held_locks); | |
2724 |