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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 | * | |
4b32d0a4 | 8 | * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
90eec103 | 9 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra |
fbb9ce95 IM |
10 | * |
11 | * this code maps all the lock dependencies as they occur in a live kernel | |
12 | * and will warn about the following classes of locking bugs: | |
13 | * | |
14 | * - lock inversion scenarios | |
15 | * - circular lock dependencies | |
16 | * - hardirq/softirq safe/unsafe locking bugs | |
17 | * | |
18 | * Bugs are reported even if the current locking scenario does not cause | |
19 | * any deadlock at this point. | |
20 | * | |
21 | * I.e. if anytime in the past two locks were taken in a different order, | |
22 | * even if it happened for another task, even if those were different | |
23 | * locks (but of the same class as this lock), this code will detect it. | |
24 | * | |
25 | * Thanks to Arjan van de Ven for coming up with the initial idea of | |
26 | * mapping lock dependencies runtime. | |
27 | */ | |
a5e25883 | 28 | #define DISABLE_BRANCH_PROFILING |
fbb9ce95 IM |
29 | #include <linux/mutex.h> |
30 | #include <linux/sched.h> | |
e6017571 | 31 | #include <linux/sched/clock.h> |
29930025 | 32 | #include <linux/sched/task.h> |
6d7225f0 | 33 | #include <linux/sched/mm.h> |
fbb9ce95 IM |
34 | #include <linux/delay.h> |
35 | #include <linux/module.h> | |
36 | #include <linux/proc_fs.h> | |
37 | #include <linux/seq_file.h> | |
38 | #include <linux/spinlock.h> | |
39 | #include <linux/kallsyms.h> | |
40 | #include <linux/interrupt.h> | |
41 | #include <linux/stacktrace.h> | |
42 | #include <linux/debug_locks.h> | |
43 | #include <linux/irqflags.h> | |
99de055a | 44 | #include <linux/utsname.h> |
4b32d0a4 | 45 | #include <linux/hash.h> |
81d68a96 | 46 | #include <linux/ftrace.h> |
b4b136f4 | 47 | #include <linux/stringify.h> |
d588e461 | 48 | #include <linux/bitops.h> |
5a0e3ad6 | 49 | #include <linux/gfp.h> |
e7904a28 | 50 | #include <linux/random.h> |
dfaaf3fa | 51 | #include <linux/jhash.h> |
88f1c87d | 52 | #include <linux/nmi.h> |
af012961 | 53 | |
fbb9ce95 IM |
54 | #include <asm/sections.h> |
55 | ||
56 | #include "lockdep_internals.h" | |
57 | ||
a8d154b0 | 58 | #define CREATE_TRACE_POINTS |
67178767 | 59 | #include <trace/events/lock.h> |
a8d154b0 | 60 | |
f20786ff PZ |
61 | #ifdef CONFIG_PROVE_LOCKING |
62 | int prove_locking = 1; | |
63 | module_param(prove_locking, int, 0644); | |
64 | #else | |
65 | #define prove_locking 0 | |
66 | #endif | |
67 | ||
68 | #ifdef CONFIG_LOCK_STAT | |
69 | int lock_stat = 1; | |
70 | module_param(lock_stat, int, 0644); | |
71 | #else | |
72 | #define lock_stat 0 | |
73 | #endif | |
74 | ||
fbb9ce95 | 75 | /* |
74c383f1 IM |
76 | * lockdep_lock: protects the lockdep graph, the hashes and the |
77 | * class/list/hash allocators. | |
fbb9ce95 IM |
78 | * |
79 | * This is one of the rare exceptions where it's justified | |
80 | * to use a raw spinlock - we really dont want the spinlock | |
74c383f1 | 81 | * code to recurse back into the lockdep code... |
fbb9ce95 | 82 | */ |
edc35bd7 | 83 | static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
74c383f1 IM |
84 | |
85 | static int graph_lock(void) | |
86 | { | |
0199c4e6 | 87 | arch_spin_lock(&lockdep_lock); |
74c383f1 IM |
88 | /* |
89 | * Make sure that if another CPU detected a bug while | |
90 | * walking the graph we dont change it (while the other | |
91 | * CPU is busy printing out stuff with the graph lock | |
92 | * dropped already) | |
93 | */ | |
94 | if (!debug_locks) { | |
0199c4e6 | 95 | arch_spin_unlock(&lockdep_lock); |
74c383f1 IM |
96 | return 0; |
97 | } | |
bb065afb SR |
98 | /* prevent any recursions within lockdep from causing deadlocks */ |
99 | current->lockdep_recursion++; | |
74c383f1 IM |
100 | return 1; |
101 | } | |
102 | ||
103 | static inline int graph_unlock(void) | |
104 | { | |
0119fee4 PZ |
105 | if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) { |
106 | /* | |
107 | * The lockdep graph lock isn't locked while we expect it to | |
108 | * be, we're confused now, bye! | |
109 | */ | |
381a2292 | 110 | return DEBUG_LOCKS_WARN_ON(1); |
0119fee4 | 111 | } |
381a2292 | 112 | |
bb065afb | 113 | current->lockdep_recursion--; |
0199c4e6 | 114 | arch_spin_unlock(&lockdep_lock); |
74c383f1 IM |
115 | return 0; |
116 | } | |
117 | ||
118 | /* | |
119 | * Turn lock debugging off and return with 0 if it was off already, | |
120 | * and also release the graph lock: | |
121 | */ | |
122 | static inline int debug_locks_off_graph_unlock(void) | |
123 | { | |
124 | int ret = debug_locks_off(); | |
125 | ||
0199c4e6 | 126 | arch_spin_unlock(&lockdep_lock); |
74c383f1 IM |
127 | |
128 | return ret; | |
129 | } | |
fbb9ce95 | 130 | |
fbb9ce95 | 131 | unsigned long nr_list_entries; |
af012961 | 132 | static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; |
fbb9ce95 | 133 | |
fbb9ce95 IM |
134 | /* |
135 | * All data structures here are protected by the global debug_lock. | |
136 | * | |
137 | * Mutex key structs only get allocated, once during bootup, and never | |
138 | * get freed - this significantly simplifies the debugging code. | |
139 | */ | |
140 | unsigned long nr_lock_classes; | |
141 | static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; | |
142 | ||
71895ab3 | 143 | static inline struct lock_class *hlock_class(struct held_lock *hlock) |
f82b217e DJ |
144 | { |
145 | if (!hlock->class_idx) { | |
0119fee4 PZ |
146 | /* |
147 | * Someone passed in garbage, we give up. | |
148 | */ | |
f82b217e DJ |
149 | DEBUG_LOCKS_WARN_ON(1); |
150 | return NULL; | |
151 | } | |
152 | return lock_classes + hlock->class_idx - 1; | |
153 | } | |
154 | ||
f20786ff | 155 | #ifdef CONFIG_LOCK_STAT |
25528213 | 156 | static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats); |
f20786ff | 157 | |
3365e779 PZ |
158 | static inline u64 lockstat_clock(void) |
159 | { | |
c676329a | 160 | return local_clock(); |
3365e779 PZ |
161 | } |
162 | ||
c7e78cff | 163 | static int lock_point(unsigned long points[], unsigned long ip) |
f20786ff PZ |
164 | { |
165 | int i; | |
166 | ||
c7e78cff PZ |
167 | for (i = 0; i < LOCKSTAT_POINTS; i++) { |
168 | if (points[i] == 0) { | |
169 | points[i] = ip; | |
f20786ff PZ |
170 | break; |
171 | } | |
c7e78cff | 172 | if (points[i] == ip) |
f20786ff PZ |
173 | break; |
174 | } | |
175 | ||
176 | return i; | |
177 | } | |
178 | ||
3365e779 | 179 | static void lock_time_inc(struct lock_time *lt, u64 time) |
f20786ff PZ |
180 | { |
181 | if (time > lt->max) | |
182 | lt->max = time; | |
183 | ||
109d71c6 | 184 | if (time < lt->min || !lt->nr) |
f20786ff PZ |
185 | lt->min = time; |
186 | ||
187 | lt->total += time; | |
188 | lt->nr++; | |
189 | } | |
190 | ||
c46261de PZ |
191 | static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) |
192 | { | |
109d71c6 FR |
193 | if (!src->nr) |
194 | return; | |
195 | ||
196 | if (src->max > dst->max) | |
197 | dst->max = src->max; | |
198 | ||
199 | if (src->min < dst->min || !dst->nr) | |
200 | dst->min = src->min; | |
201 | ||
c46261de PZ |
202 | dst->total += src->total; |
203 | dst->nr += src->nr; | |
204 | } | |
205 | ||
206 | struct lock_class_stats lock_stats(struct lock_class *class) | |
207 | { | |
208 | struct lock_class_stats stats; | |
209 | int cpu, i; | |
210 | ||
211 | memset(&stats, 0, sizeof(struct lock_class_stats)); | |
212 | for_each_possible_cpu(cpu) { | |
213 | struct lock_class_stats *pcs = | |
1871e52c | 214 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
c46261de PZ |
215 | |
216 | for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) | |
217 | stats.contention_point[i] += pcs->contention_point[i]; | |
218 | ||
c7e78cff PZ |
219 | for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) |
220 | stats.contending_point[i] += pcs->contending_point[i]; | |
221 | ||
c46261de PZ |
222 | lock_time_add(&pcs->read_waittime, &stats.read_waittime); |
223 | lock_time_add(&pcs->write_waittime, &stats.write_waittime); | |
224 | ||
225 | lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); | |
226 | lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); | |
96645678 PZ |
227 | |
228 | for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) | |
229 | stats.bounces[i] += pcs->bounces[i]; | |
c46261de PZ |
230 | } |
231 | ||
232 | return stats; | |
233 | } | |
234 | ||
235 | void clear_lock_stats(struct lock_class *class) | |
236 | { | |
237 | int cpu; | |
238 | ||
239 | for_each_possible_cpu(cpu) { | |
240 | struct lock_class_stats *cpu_stats = | |
1871e52c | 241 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
c46261de PZ |
242 | |
243 | memset(cpu_stats, 0, sizeof(struct lock_class_stats)); | |
244 | } | |
245 | memset(class->contention_point, 0, sizeof(class->contention_point)); | |
c7e78cff | 246 | memset(class->contending_point, 0, sizeof(class->contending_point)); |
c46261de PZ |
247 | } |
248 | ||
f20786ff PZ |
249 | static struct lock_class_stats *get_lock_stats(struct lock_class *class) |
250 | { | |
1871e52c | 251 | return &get_cpu_var(cpu_lock_stats)[class - lock_classes]; |
f20786ff PZ |
252 | } |
253 | ||
254 | static void put_lock_stats(struct lock_class_stats *stats) | |
255 | { | |
1871e52c | 256 | put_cpu_var(cpu_lock_stats); |
f20786ff PZ |
257 | } |
258 | ||
259 | static void lock_release_holdtime(struct held_lock *hlock) | |
260 | { | |
261 | struct lock_class_stats *stats; | |
3365e779 | 262 | u64 holdtime; |
f20786ff PZ |
263 | |
264 | if (!lock_stat) | |
265 | return; | |
266 | ||
3365e779 | 267 | holdtime = lockstat_clock() - hlock->holdtime_stamp; |
f20786ff | 268 | |
f82b217e | 269 | stats = get_lock_stats(hlock_class(hlock)); |
f20786ff PZ |
270 | if (hlock->read) |
271 | lock_time_inc(&stats->read_holdtime, holdtime); | |
272 | else | |
273 | lock_time_inc(&stats->write_holdtime, holdtime); | |
274 | put_lock_stats(stats); | |
275 | } | |
276 | #else | |
277 | static inline void lock_release_holdtime(struct held_lock *hlock) | |
278 | { | |
279 | } | |
280 | #endif | |
281 | ||
fbb9ce95 IM |
282 | /* |
283 | * We keep a global list of all lock classes. The list only grows, | |
284 | * never shrinks. The list is only accessed with the lockdep | |
285 | * spinlock lock held. | |
286 | */ | |
287 | LIST_HEAD(all_lock_classes); | |
288 | ||
289 | /* | |
290 | * The lockdep classes are in a hash-table as well, for fast lookup: | |
291 | */ | |
292 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) | |
293 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) | |
4b32d0a4 | 294 | #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) |
fbb9ce95 IM |
295 | #define classhashentry(key) (classhash_table + __classhashfn((key))) |
296 | ||
a63f38cc | 297 | static struct hlist_head classhash_table[CLASSHASH_SIZE]; |
fbb9ce95 | 298 | |
fbb9ce95 IM |
299 | /* |
300 | * We put the lock dependency chains into a hash-table as well, to cache | |
301 | * their existence: | |
302 | */ | |
303 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) | |
304 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) | |
4b32d0a4 | 305 | #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) |
fbb9ce95 IM |
306 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) |
307 | ||
a63f38cc | 308 | static struct hlist_head chainhash_table[CHAINHASH_SIZE]; |
fbb9ce95 IM |
309 | |
310 | /* | |
311 | * The hash key of the lock dependency chains is a hash itself too: | |
312 | * it's a hash of all locks taken up to that lock, including that lock. | |
313 | * It's a 64-bit hash, because it's important for the keys to be | |
314 | * unique. | |
315 | */ | |
dfaaf3fa PZ |
316 | static inline u64 iterate_chain_key(u64 key, u32 idx) |
317 | { | |
318 | u32 k0 = key, k1 = key >> 32; | |
319 | ||
320 | __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */ | |
321 | ||
322 | return k0 | (u64)k1 << 32; | |
323 | } | |
fbb9ce95 | 324 | |
1d09daa5 | 325 | void lockdep_off(void) |
fbb9ce95 IM |
326 | { |
327 | current->lockdep_recursion++; | |
328 | } | |
fbb9ce95 IM |
329 | EXPORT_SYMBOL(lockdep_off); |
330 | ||
1d09daa5 | 331 | void lockdep_on(void) |
fbb9ce95 IM |
332 | { |
333 | current->lockdep_recursion--; | |
334 | } | |
fbb9ce95 IM |
335 | EXPORT_SYMBOL(lockdep_on); |
336 | ||
fbb9ce95 IM |
337 | /* |
338 | * Debugging switches: | |
339 | */ | |
340 | ||
341 | #define VERBOSE 0 | |
33e94e96 | 342 | #define VERY_VERBOSE 0 |
fbb9ce95 IM |
343 | |
344 | #if VERBOSE | |
345 | # define HARDIRQ_VERBOSE 1 | |
346 | # define SOFTIRQ_VERBOSE 1 | |
347 | #else | |
348 | # define HARDIRQ_VERBOSE 0 | |
349 | # define SOFTIRQ_VERBOSE 0 | |
350 | #endif | |
351 | ||
d92a8cfc | 352 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE |
fbb9ce95 IM |
353 | /* |
354 | * Quick filtering for interesting events: | |
355 | */ | |
356 | static int class_filter(struct lock_class *class) | |
357 | { | |
f9829cce AK |
358 | #if 0 |
359 | /* Example */ | |
fbb9ce95 | 360 | if (class->name_version == 1 && |
f9829cce | 361 | !strcmp(class->name, "lockname")) |
fbb9ce95 IM |
362 | return 1; |
363 | if (class->name_version == 1 && | |
f9829cce | 364 | !strcmp(class->name, "&struct->lockfield")) |
fbb9ce95 | 365 | return 1; |
f9829cce | 366 | #endif |
a6640897 IM |
367 | /* Filter everything else. 1 would be to allow everything else */ |
368 | return 0; | |
fbb9ce95 IM |
369 | } |
370 | #endif | |
371 | ||
372 | static int verbose(struct lock_class *class) | |
373 | { | |
374 | #if VERBOSE | |
375 | return class_filter(class); | |
376 | #endif | |
377 | return 0; | |
378 | } | |
379 | ||
fbb9ce95 IM |
380 | /* |
381 | * Stack-trace: tightly packed array of stack backtrace | |
74c383f1 | 382 | * addresses. Protected by the graph_lock. |
fbb9ce95 IM |
383 | */ |
384 | unsigned long nr_stack_trace_entries; | |
385 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; | |
386 | ||
2c522836 DJ |
387 | static void print_lockdep_off(const char *bug_msg) |
388 | { | |
389 | printk(KERN_DEBUG "%s\n", bug_msg); | |
390 | printk(KERN_DEBUG "turning off the locking correctness validator.\n"); | |
acf59377 | 391 | #ifdef CONFIG_LOCK_STAT |
2c522836 | 392 | printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n"); |
acf59377 | 393 | #endif |
2c522836 DJ |
394 | } |
395 | ||
fbb9ce95 IM |
396 | static int save_trace(struct stack_trace *trace) |
397 | { | |
398 | trace->nr_entries = 0; | |
399 | trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; | |
400 | trace->entries = stack_trace + nr_stack_trace_entries; | |
401 | ||
5a1b3999 | 402 | trace->skip = 3; |
5a1b3999 | 403 | |
ab1b6f03 | 404 | save_stack_trace(trace); |
fbb9ce95 | 405 | |
4f84f433 PZ |
406 | /* |
407 | * Some daft arches put -1 at the end to indicate its a full trace. | |
408 | * | |
409 | * <rant> this is buggy anyway, since it takes a whole extra entry so a | |
410 | * complete trace that maxes out the entries provided will be reported | |
411 | * as incomplete, friggin useless </rant> | |
412 | */ | |
ea5b41f9 TL |
413 | if (trace->nr_entries != 0 && |
414 | trace->entries[trace->nr_entries-1] == ULONG_MAX) | |
4f84f433 PZ |
415 | trace->nr_entries--; |
416 | ||
fbb9ce95 IM |
417 | trace->max_entries = trace->nr_entries; |
418 | ||
419 | nr_stack_trace_entries += trace->nr_entries; | |
fbb9ce95 | 420 | |
4f84f433 | 421 | if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { |
74c383f1 IM |
422 | if (!debug_locks_off_graph_unlock()) |
423 | return 0; | |
424 | ||
2c522836 | 425 | print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); |
74c383f1 IM |
426 | dump_stack(); |
427 | ||
fbb9ce95 IM |
428 | return 0; |
429 | } | |
430 | ||
431 | return 1; | |
432 | } | |
433 | ||
434 | unsigned int nr_hardirq_chains; | |
435 | unsigned int nr_softirq_chains; | |
436 | unsigned int nr_process_chains; | |
437 | unsigned int max_lockdep_depth; | |
fbb9ce95 IM |
438 | |
439 | #ifdef CONFIG_DEBUG_LOCKDEP | |
fbb9ce95 IM |
440 | /* |
441 | * Various lockdep statistics: | |
442 | */ | |
bd6d29c2 | 443 | DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); |
fbb9ce95 IM |
444 | #endif |
445 | ||
446 | /* | |
447 | * Locking printouts: | |
448 | */ | |
449 | ||
fabe9c42 | 450 | #define __USAGE(__STATE) \ |
b4b136f4 PZ |
451 | [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ |
452 | [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ | |
453 | [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ | |
454 | [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", | |
fabe9c42 | 455 | |
fbb9ce95 IM |
456 | static const char *usage_str[] = |
457 | { | |
fabe9c42 PZ |
458 | #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) |
459 | #include "lockdep_states.h" | |
460 | #undef LOCKDEP_STATE | |
461 | [LOCK_USED] = "INITIAL USE", | |
fbb9ce95 IM |
462 | }; |
463 | ||
464 | const char * __get_key_name(struct lockdep_subclass_key *key, char *str) | |
465 | { | |
ffb45122 | 466 | return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); |
fbb9ce95 IM |
467 | } |
468 | ||
3ff176ca | 469 | static inline unsigned long lock_flag(enum lock_usage_bit bit) |
fbb9ce95 | 470 | { |
3ff176ca PZ |
471 | return 1UL << bit; |
472 | } | |
fbb9ce95 | 473 | |
3ff176ca PZ |
474 | static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) |
475 | { | |
476 | char c = '.'; | |
477 | ||
478 | if (class->usage_mask & lock_flag(bit + 2)) | |
479 | c = '+'; | |
480 | if (class->usage_mask & lock_flag(bit)) { | |
481 | c = '-'; | |
482 | if (class->usage_mask & lock_flag(bit + 2)) | |
483 | c = '?'; | |
fbb9ce95 IM |
484 | } |
485 | ||
3ff176ca PZ |
486 | return c; |
487 | } | |
cf40bd16 | 488 | |
f510b233 | 489 | void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) |
3ff176ca | 490 | { |
f510b233 | 491 | int i = 0; |
cf40bd16 | 492 | |
f510b233 PZ |
493 | #define LOCKDEP_STATE(__STATE) \ |
494 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ | |
495 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); | |
496 | #include "lockdep_states.h" | |
497 | #undef LOCKDEP_STATE | |
498 | ||
499 | usage[i] = '\0'; | |
fbb9ce95 IM |
500 | } |
501 | ||
e5e78d08 | 502 | static void __print_lock_name(struct lock_class *class) |
3003eba3 SR |
503 | { |
504 | char str[KSYM_NAME_LEN]; | |
505 | const char *name; | |
506 | ||
fbb9ce95 IM |
507 | name = class->name; |
508 | if (!name) { | |
509 | name = __get_key_name(class->key, str); | |
f943fe0f | 510 | printk(KERN_CONT "%s", name); |
fbb9ce95 | 511 | } else { |
f943fe0f | 512 | printk(KERN_CONT "%s", name); |
fbb9ce95 | 513 | if (class->name_version > 1) |
f943fe0f | 514 | printk(KERN_CONT "#%d", class->name_version); |
fbb9ce95 | 515 | if (class->subclass) |
f943fe0f | 516 | printk(KERN_CONT "/%d", class->subclass); |
fbb9ce95 | 517 | } |
e5e78d08 SR |
518 | } |
519 | ||
520 | static void print_lock_name(struct lock_class *class) | |
521 | { | |
522 | char usage[LOCK_USAGE_CHARS]; | |
523 | ||
524 | get_usage_chars(class, usage); | |
525 | ||
f943fe0f | 526 | printk(KERN_CONT " ("); |
e5e78d08 | 527 | __print_lock_name(class); |
f943fe0f | 528 | printk(KERN_CONT "){%s}", usage); |
fbb9ce95 IM |
529 | } |
530 | ||
531 | static void print_lockdep_cache(struct lockdep_map *lock) | |
532 | { | |
533 | const char *name; | |
9281acea | 534 | char str[KSYM_NAME_LEN]; |
fbb9ce95 IM |
535 | |
536 | name = lock->name; | |
537 | if (!name) | |
538 | name = __get_key_name(lock->key->subkeys, str); | |
539 | ||
f943fe0f | 540 | printk(KERN_CONT "%s", name); |
fbb9ce95 IM |
541 | } |
542 | ||
543 | static void print_lock(struct held_lock *hlock) | |
544 | { | |
d7bc3197 PZ |
545 | /* |
546 | * We can be called locklessly through debug_show_all_locks() so be | |
547 | * extra careful, the hlock might have been released and cleared. | |
548 | */ | |
549 | unsigned int class_idx = hlock->class_idx; | |
550 | ||
551 | /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */ | |
552 | barrier(); | |
553 | ||
554 | if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) { | |
f943fe0f | 555 | printk(KERN_CONT "<RELEASED>\n"); |
d7bc3197 PZ |
556 | return; |
557 | } | |
558 | ||
559 | print_lock_name(lock_classes + class_idx - 1); | |
f943fe0f DV |
560 | printk(KERN_CONT ", at: [<%p>] %pS\n", |
561 | (void *)hlock->acquire_ip, (void *)hlock->acquire_ip); | |
fbb9ce95 IM |
562 | } |
563 | ||
564 | static void lockdep_print_held_locks(struct task_struct *curr) | |
565 | { | |
566 | int i, depth = curr->lockdep_depth; | |
567 | ||
568 | if (!depth) { | |
ba25f9dc | 569 | printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr)); |
fbb9ce95 IM |
570 | return; |
571 | } | |
572 | printk("%d lock%s held by %s/%d:\n", | |
ba25f9dc | 573 | depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr)); |
fbb9ce95 IM |
574 | |
575 | for (i = 0; i < depth; i++) { | |
576 | printk(" #%d: ", i); | |
577 | print_lock(curr->held_locks + i); | |
578 | } | |
579 | } | |
fbb9ce95 | 580 | |
fbdc4b9a | 581 | static void print_kernel_ident(void) |
8e18257d | 582 | { |
fbdc4b9a | 583 | printk("%s %.*s %s\n", init_utsname()->release, |
8e18257d | 584 | (int)strcspn(init_utsname()->version, " "), |
fbdc4b9a BH |
585 | init_utsname()->version, |
586 | print_tainted()); | |
8e18257d PZ |
587 | } |
588 | ||
589 | static int very_verbose(struct lock_class *class) | |
590 | { | |
591 | #if VERY_VERBOSE | |
592 | return class_filter(class); | |
593 | #endif | |
594 | return 0; | |
595 | } | |
596 | ||
fbb9ce95 | 597 | /* |
8e18257d | 598 | * Is this the address of a static object: |
fbb9ce95 | 599 | */ |
8dce7a9a | 600 | #ifdef __KERNEL__ |
8e18257d | 601 | static int static_obj(void *obj) |
fbb9ce95 | 602 | { |
8e18257d PZ |
603 | unsigned long start = (unsigned long) &_stext, |
604 | end = (unsigned long) &_end, | |
605 | addr = (unsigned long) obj; | |
8e18257d | 606 | |
fbb9ce95 | 607 | /* |
8e18257d | 608 | * static variable? |
fbb9ce95 | 609 | */ |
8e18257d PZ |
610 | if ((addr >= start) && (addr < end)) |
611 | return 1; | |
fbb9ce95 | 612 | |
2a9ad18d MF |
613 | if (arch_is_kernel_data(addr)) |
614 | return 1; | |
615 | ||
fbb9ce95 | 616 | /* |
10fad5e4 | 617 | * in-kernel percpu var? |
fbb9ce95 | 618 | */ |
10fad5e4 TH |
619 | if (is_kernel_percpu_address(addr)) |
620 | return 1; | |
fbb9ce95 | 621 | |
8e18257d | 622 | /* |
10fad5e4 | 623 | * module static or percpu var? |
8e18257d | 624 | */ |
10fad5e4 | 625 | return is_module_address(addr) || is_module_percpu_address(addr); |
99de055a | 626 | } |
8dce7a9a | 627 | #endif |
99de055a | 628 | |
fbb9ce95 | 629 | /* |
8e18257d PZ |
630 | * To make lock name printouts unique, we calculate a unique |
631 | * class->name_version generation counter: | |
fbb9ce95 | 632 | */ |
8e18257d | 633 | static int count_matching_names(struct lock_class *new_class) |
fbb9ce95 | 634 | { |
8e18257d PZ |
635 | struct lock_class *class; |
636 | int count = 0; | |
fbb9ce95 | 637 | |
8e18257d | 638 | if (!new_class->name) |
fbb9ce95 IM |
639 | return 0; |
640 | ||
35a9393c | 641 | list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) { |
8e18257d PZ |
642 | if (new_class->key - new_class->subclass == class->key) |
643 | return class->name_version; | |
644 | if (class->name && !strcmp(class->name, new_class->name)) | |
645 | count = max(count, class->name_version); | |
646 | } | |
fbb9ce95 | 647 | |
8e18257d | 648 | return count + 1; |
fbb9ce95 IM |
649 | } |
650 | ||
8e18257d PZ |
651 | /* |
652 | * Register a lock's class in the hash-table, if the class is not present | |
653 | * yet. Otherwise we look it up. We cache the result in the lock object | |
654 | * itself, so actual lookup of the hash should be once per lock object. | |
655 | */ | |
656 | static inline struct lock_class * | |
657 | look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) | |
fbb9ce95 | 658 | { |
8e18257d | 659 | struct lockdep_subclass_key *key; |
a63f38cc | 660 | struct hlist_head *hash_head; |
8e18257d | 661 | struct lock_class *class; |
383776fa | 662 | bool is_static = false; |
fbb9ce95 | 663 | |
4ba053c0 HM |
664 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { |
665 | debug_locks_off(); | |
666 | printk(KERN_ERR | |
667 | "BUG: looking up invalid subclass: %u\n", subclass); | |
668 | printk(KERN_ERR | |
669 | "turning off the locking correctness validator.\n"); | |
670 | dump_stack(); | |
671 | return NULL; | |
672 | } | |
673 | ||
8e18257d PZ |
674 | /* |
675 | * Static locks do not have their class-keys yet - for them the key | |
383776fa TG |
676 | * is the lock object itself. If the lock is in the per cpu area, |
677 | * the canonical address of the lock (per cpu offset removed) is | |
678 | * used. | |
8e18257d | 679 | */ |
383776fa TG |
680 | if (unlikely(!lock->key)) { |
681 | unsigned long can_addr, addr = (unsigned long)lock; | |
682 | ||
683 | if (__is_kernel_percpu_address(addr, &can_addr)) | |
684 | lock->key = (void *)can_addr; | |
685 | else if (__is_module_percpu_address(addr, &can_addr)) | |
686 | lock->key = (void *)can_addr; | |
687 | else if (static_obj(lock)) | |
688 | lock->key = (void *)lock; | |
689 | else | |
690 | return ERR_PTR(-EINVAL); | |
691 | is_static = true; | |
692 | } | |
fbb9ce95 | 693 | |
8e18257d PZ |
694 | /* |
695 | * NOTE: the class-key must be unique. For dynamic locks, a static | |
696 | * lock_class_key variable is passed in through the mutex_init() | |
697 | * (or spin_lock_init()) call - which acts as the key. For static | |
698 | * locks we use the lock object itself as the key. | |
699 | */ | |
4b32d0a4 PZ |
700 | BUILD_BUG_ON(sizeof(struct lock_class_key) > |
701 | sizeof(struct lockdep_map)); | |
fbb9ce95 | 702 | |
8e18257d | 703 | key = lock->key->subkeys + subclass; |
ca268c69 | 704 | |
8e18257d | 705 | hash_head = classhashentry(key); |
74c383f1 | 706 | |
8e18257d | 707 | /* |
35a9393c | 708 | * We do an RCU walk of the hash, see lockdep_free_key_range(). |
8e18257d | 709 | */ |
35a9393c PZ |
710 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
711 | return NULL; | |
712 | ||
a63f38cc | 713 | hlist_for_each_entry_rcu(class, hash_head, hash_entry) { |
4b32d0a4 | 714 | if (class->key == key) { |
0119fee4 PZ |
715 | /* |
716 | * Huh! same key, different name? Did someone trample | |
717 | * on some memory? We're most confused. | |
718 | */ | |
4b32d0a4 | 719 | WARN_ON_ONCE(class->name != lock->name); |
8e18257d | 720 | return class; |
4b32d0a4 PZ |
721 | } |
722 | } | |
fbb9ce95 | 723 | |
383776fa | 724 | return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL); |
fbb9ce95 IM |
725 | } |
726 | ||
727 | /* | |
8e18257d PZ |
728 | * Register a lock's class in the hash-table, if the class is not present |
729 | * yet. Otherwise we look it up. We cache the result in the lock object | |
730 | * itself, so actual lookup of the hash should be once per lock object. | |
fbb9ce95 | 731 | */ |
c003ed92 | 732 | static struct lock_class * |
8e18257d | 733 | register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) |
fbb9ce95 | 734 | { |
8e18257d | 735 | struct lockdep_subclass_key *key; |
a63f38cc | 736 | struct hlist_head *hash_head; |
8e18257d | 737 | struct lock_class *class; |
35a9393c PZ |
738 | |
739 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); | |
8e18257d PZ |
740 | |
741 | class = look_up_lock_class(lock, subclass); | |
383776fa | 742 | if (likely(!IS_ERR_OR_NULL(class))) |
87cdee71 | 743 | goto out_set_class_cache; |
8e18257d PZ |
744 | |
745 | /* | |
746 | * Debug-check: all keys must be persistent! | |
383776fa TG |
747 | */ |
748 | if (IS_ERR(class)) { | |
8e18257d PZ |
749 | debug_locks_off(); |
750 | printk("INFO: trying to register non-static key.\n"); | |
751 | printk("the code is fine but needs lockdep annotation.\n"); | |
752 | printk("turning off the locking correctness validator.\n"); | |
753 | dump_stack(); | |
8e18257d PZ |
754 | return NULL; |
755 | } | |
756 | ||
757 | key = lock->key->subkeys + subclass; | |
758 | hash_head = classhashentry(key); | |
759 | ||
8e18257d | 760 | if (!graph_lock()) { |
8e18257d PZ |
761 | return NULL; |
762 | } | |
763 | /* | |
764 | * We have to do the hash-walk again, to avoid races | |
765 | * with another CPU: | |
766 | */ | |
a63f38cc | 767 | hlist_for_each_entry_rcu(class, hash_head, hash_entry) { |
8e18257d PZ |
768 | if (class->key == key) |
769 | goto out_unlock_set; | |
35a9393c PZ |
770 | } |
771 | ||
8e18257d PZ |
772 | /* |
773 | * Allocate a new key from the static array, and add it to | |
774 | * the hash: | |
775 | */ | |
776 | if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { | |
777 | if (!debug_locks_off_graph_unlock()) { | |
8e18257d PZ |
778 | return NULL; |
779 | } | |
8e18257d | 780 | |
2c522836 | 781 | print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!"); |
eedeeabd | 782 | dump_stack(); |
8e18257d PZ |
783 | return NULL; |
784 | } | |
785 | class = lock_classes + nr_lock_classes++; | |
bd6d29c2 | 786 | debug_atomic_inc(nr_unused_locks); |
8e18257d PZ |
787 | class->key = key; |
788 | class->name = lock->name; | |
789 | class->subclass = subclass; | |
790 | INIT_LIST_HEAD(&class->lock_entry); | |
791 | INIT_LIST_HEAD(&class->locks_before); | |
792 | INIT_LIST_HEAD(&class->locks_after); | |
793 | class->name_version = count_matching_names(class); | |
794 | /* | |
795 | * We use RCU's safe list-add method to make | |
796 | * parallel walking of the hash-list safe: | |
797 | */ | |
a63f38cc | 798 | hlist_add_head_rcu(&class->hash_entry, hash_head); |
1481197b DF |
799 | /* |
800 | * Add it to the global list of classes: | |
801 | */ | |
802 | list_add_tail_rcu(&class->lock_entry, &all_lock_classes); | |
8e18257d PZ |
803 | |
804 | if (verbose(class)) { | |
805 | graph_unlock(); | |
8e18257d PZ |
806 | |
807 | printk("\nnew class %p: %s", class->key, class->name); | |
808 | if (class->name_version > 1) | |
f943fe0f DV |
809 | printk(KERN_CONT "#%d", class->name_version); |
810 | printk(KERN_CONT "\n"); | |
8e18257d PZ |
811 | dump_stack(); |
812 | ||
8e18257d | 813 | if (!graph_lock()) { |
8e18257d PZ |
814 | return NULL; |
815 | } | |
816 | } | |
817 | out_unlock_set: | |
818 | graph_unlock(); | |
8e18257d | 819 | |
87cdee71 | 820 | out_set_class_cache: |
8e18257d | 821 | if (!subclass || force) |
62016250 HM |
822 | lock->class_cache[0] = class; |
823 | else if (subclass < NR_LOCKDEP_CACHING_CLASSES) | |
824 | lock->class_cache[subclass] = class; | |
8e18257d | 825 | |
0119fee4 PZ |
826 | /* |
827 | * Hash collision, did we smoke some? We found a class with a matching | |
828 | * hash but the subclass -- which is hashed in -- didn't match. | |
829 | */ | |
8e18257d PZ |
830 | if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) |
831 | return NULL; | |
832 | ||
833 | return class; | |
834 | } | |
835 | ||
836 | #ifdef CONFIG_PROVE_LOCKING | |
837 | /* | |
838 | * Allocate a lockdep entry. (assumes the graph_lock held, returns | |
839 | * with NULL on failure) | |
840 | */ | |
841 | static struct lock_list *alloc_list_entry(void) | |
842 | { | |
843 | if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { | |
844 | if (!debug_locks_off_graph_unlock()) | |
845 | return NULL; | |
846 | ||
2c522836 | 847 | print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!"); |
eedeeabd | 848 | dump_stack(); |
8e18257d PZ |
849 | return NULL; |
850 | } | |
851 | return list_entries + nr_list_entries++; | |
852 | } | |
853 | ||
854 | /* | |
855 | * Add a new dependency to the head of the list: | |
856 | */ | |
83f06168 TE |
857 | static int add_lock_to_list(struct lock_class *this, struct list_head *head, |
858 | unsigned long ip, int distance, | |
859 | struct stack_trace *trace) | |
8e18257d PZ |
860 | { |
861 | struct lock_list *entry; | |
862 | /* | |
863 | * Lock not present yet - get a new dependency struct and | |
864 | * add it to the list: | |
865 | */ | |
866 | entry = alloc_list_entry(); | |
867 | if (!entry) | |
868 | return 0; | |
869 | ||
74870172 ZY |
870 | entry->class = this; |
871 | entry->distance = distance; | |
4726f2a6 | 872 | entry->trace = *trace; |
8e18257d | 873 | /* |
35a9393c PZ |
874 | * Both allocation and removal are done under the graph lock; but |
875 | * iteration is under RCU-sched; see look_up_lock_class() and | |
876 | * lockdep_free_key_range(). | |
8e18257d PZ |
877 | */ |
878 | list_add_tail_rcu(&entry->entry, head); | |
879 | ||
880 | return 1; | |
881 | } | |
882 | ||
98c33edd PZ |
883 | /* |
884 | * For good efficiency of modular, we use power of 2 | |
885 | */ | |
af012961 PZ |
886 | #define MAX_CIRCULAR_QUEUE_SIZE 4096UL |
887 | #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) | |
888 | ||
98c33edd PZ |
889 | /* |
890 | * The circular_queue and helpers is used to implement the | |
af012961 PZ |
891 | * breadth-first search(BFS)algorithem, by which we can build |
892 | * the shortest path from the next lock to be acquired to the | |
893 | * previous held lock if there is a circular between them. | |
98c33edd | 894 | */ |
af012961 PZ |
895 | struct circular_queue { |
896 | unsigned long element[MAX_CIRCULAR_QUEUE_SIZE]; | |
897 | unsigned int front, rear; | |
898 | }; | |
899 | ||
900 | static struct circular_queue lock_cq; | |
af012961 | 901 | |
12f3dfd0 | 902 | unsigned int max_bfs_queue_depth; |
af012961 | 903 | |
e351b660 ML |
904 | static unsigned int lockdep_dependency_gen_id; |
905 | ||
af012961 PZ |
906 | static inline void __cq_init(struct circular_queue *cq) |
907 | { | |
908 | cq->front = cq->rear = 0; | |
e351b660 | 909 | lockdep_dependency_gen_id++; |
af012961 PZ |
910 | } |
911 | ||
912 | static inline int __cq_empty(struct circular_queue *cq) | |
913 | { | |
914 | return (cq->front == cq->rear); | |
915 | } | |
916 | ||
917 | static inline int __cq_full(struct circular_queue *cq) | |
918 | { | |
919 | return ((cq->rear + 1) & CQ_MASK) == cq->front; | |
920 | } | |
921 | ||
922 | static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) | |
923 | { | |
924 | if (__cq_full(cq)) | |
925 | return -1; | |
926 | ||
927 | cq->element[cq->rear] = elem; | |
928 | cq->rear = (cq->rear + 1) & CQ_MASK; | |
929 | return 0; | |
930 | } | |
931 | ||
932 | static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) | |
933 | { | |
934 | if (__cq_empty(cq)) | |
935 | return -1; | |
936 | ||
937 | *elem = cq->element[cq->front]; | |
938 | cq->front = (cq->front + 1) & CQ_MASK; | |
939 | return 0; | |
940 | } | |
941 | ||
942 | static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) | |
943 | { | |
944 | return (cq->rear - cq->front) & CQ_MASK; | |
945 | } | |
946 | ||
947 | static inline void mark_lock_accessed(struct lock_list *lock, | |
948 | struct lock_list *parent) | |
949 | { | |
950 | unsigned long nr; | |
98c33edd | 951 | |
af012961 | 952 | nr = lock - list_entries; |
0119fee4 | 953 | WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ |
af012961 | 954 | lock->parent = parent; |
e351b660 | 955 | lock->class->dep_gen_id = lockdep_dependency_gen_id; |
af012961 PZ |
956 | } |
957 | ||
958 | static inline unsigned long lock_accessed(struct lock_list *lock) | |
959 | { | |
960 | unsigned long nr; | |
98c33edd | 961 | |
af012961 | 962 | nr = lock - list_entries; |
0119fee4 | 963 | WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ |
e351b660 | 964 | return lock->class->dep_gen_id == lockdep_dependency_gen_id; |
af012961 PZ |
965 | } |
966 | ||
967 | static inline struct lock_list *get_lock_parent(struct lock_list *child) | |
968 | { | |
969 | return child->parent; | |
970 | } | |
971 | ||
972 | static inline int get_lock_depth(struct lock_list *child) | |
973 | { | |
974 | int depth = 0; | |
975 | struct lock_list *parent; | |
976 | ||
977 | while ((parent = get_lock_parent(child))) { | |
978 | child = parent; | |
979 | depth++; | |
980 | } | |
981 | return depth; | |
982 | } | |
983 | ||
9e2d551e | 984 | static int __bfs(struct lock_list *source_entry, |
af012961 PZ |
985 | void *data, |
986 | int (*match)(struct lock_list *entry, void *data), | |
987 | struct lock_list **target_entry, | |
988 | int forward) | |
c94aa5ca ML |
989 | { |
990 | struct lock_list *entry; | |
d588e461 | 991 | struct list_head *head; |
c94aa5ca ML |
992 | struct circular_queue *cq = &lock_cq; |
993 | int ret = 1; | |
994 | ||
9e2d551e | 995 | if (match(source_entry, data)) { |
c94aa5ca ML |
996 | *target_entry = source_entry; |
997 | ret = 0; | |
998 | goto exit; | |
999 | } | |
1000 | ||
d588e461 ML |
1001 | if (forward) |
1002 | head = &source_entry->class->locks_after; | |
1003 | else | |
1004 | head = &source_entry->class->locks_before; | |
1005 | ||
1006 | if (list_empty(head)) | |
1007 | goto exit; | |
1008 | ||
1009 | __cq_init(cq); | |
c94aa5ca ML |
1010 | __cq_enqueue(cq, (unsigned long)source_entry); |
1011 | ||
1012 | while (!__cq_empty(cq)) { | |
1013 | struct lock_list *lock; | |
c94aa5ca ML |
1014 | |
1015 | __cq_dequeue(cq, (unsigned long *)&lock); | |
1016 | ||
1017 | if (!lock->class) { | |
1018 | ret = -2; | |
1019 | goto exit; | |
1020 | } | |
1021 | ||
1022 | if (forward) | |
1023 | head = &lock->class->locks_after; | |
1024 | else | |
1025 | head = &lock->class->locks_before; | |
1026 | ||
35a9393c PZ |
1027 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); |
1028 | ||
1029 | list_for_each_entry_rcu(entry, head, entry) { | |
c94aa5ca | 1030 | if (!lock_accessed(entry)) { |
12f3dfd0 | 1031 | unsigned int cq_depth; |
c94aa5ca | 1032 | mark_lock_accessed(entry, lock); |
9e2d551e | 1033 | if (match(entry, data)) { |
c94aa5ca ML |
1034 | *target_entry = entry; |
1035 | ret = 0; | |
1036 | goto exit; | |
1037 | } | |
1038 | ||
1039 | if (__cq_enqueue(cq, (unsigned long)entry)) { | |
1040 | ret = -1; | |
1041 | goto exit; | |
1042 | } | |
12f3dfd0 ML |
1043 | cq_depth = __cq_get_elem_count(cq); |
1044 | if (max_bfs_queue_depth < cq_depth) | |
1045 | max_bfs_queue_depth = cq_depth; | |
c94aa5ca ML |
1046 | } |
1047 | } | |
1048 | } | |
1049 | exit: | |
1050 | return ret; | |
1051 | } | |
1052 | ||
d7aaba14 | 1053 | static inline int __bfs_forwards(struct lock_list *src_entry, |
9e2d551e ML |
1054 | void *data, |
1055 | int (*match)(struct lock_list *entry, void *data), | |
1056 | struct lock_list **target_entry) | |
c94aa5ca | 1057 | { |
9e2d551e | 1058 | return __bfs(src_entry, data, match, target_entry, 1); |
c94aa5ca ML |
1059 | |
1060 | } | |
1061 | ||
d7aaba14 | 1062 | static inline int __bfs_backwards(struct lock_list *src_entry, |
9e2d551e ML |
1063 | void *data, |
1064 | int (*match)(struct lock_list *entry, void *data), | |
1065 | struct lock_list **target_entry) | |
c94aa5ca | 1066 | { |
9e2d551e | 1067 | return __bfs(src_entry, data, match, target_entry, 0); |
c94aa5ca ML |
1068 | |
1069 | } | |
1070 | ||
8e18257d PZ |
1071 | /* |
1072 | * Recursive, forwards-direction lock-dependency checking, used for | |
1073 | * both noncyclic checking and for hardirq-unsafe/softirq-unsafe | |
1074 | * checking. | |
8e18257d | 1075 | */ |
8e18257d PZ |
1076 | |
1077 | /* | |
1078 | * Print a dependency chain entry (this is only done when a deadlock | |
1079 | * has been detected): | |
1080 | */ | |
1081 | static noinline int | |
24208ca7 | 1082 | print_circular_bug_entry(struct lock_list *target, int depth) |
8e18257d PZ |
1083 | { |
1084 | if (debug_locks_silent) | |
1085 | return 0; | |
1086 | printk("\n-> #%u", depth); | |
1087 | print_lock_name(target->class); | |
f943fe0f | 1088 | printk(KERN_CONT ":\n"); |
8e18257d PZ |
1089 | print_stack_trace(&target->trace, 6); |
1090 | ||
1091 | return 0; | |
1092 | } | |
1093 | ||
f4185812 SR |
1094 | static void |
1095 | print_circular_lock_scenario(struct held_lock *src, | |
1096 | struct held_lock *tgt, | |
1097 | struct lock_list *prt) | |
1098 | { | |
1099 | struct lock_class *source = hlock_class(src); | |
1100 | struct lock_class *target = hlock_class(tgt); | |
1101 | struct lock_class *parent = prt->class; | |
1102 | ||
1103 | /* | |
1104 | * A direct locking problem where unsafe_class lock is taken | |
1105 | * directly by safe_class lock, then all we need to show | |
1106 | * is the deadlock scenario, as it is obvious that the | |
1107 | * unsafe lock is taken under the safe lock. | |
1108 | * | |
1109 | * But if there is a chain instead, where the safe lock takes | |
1110 | * an intermediate lock (middle_class) where this lock is | |
1111 | * not the same as the safe lock, then the lock chain is | |
1112 | * used to describe the problem. Otherwise we would need | |
1113 | * to show a different CPU case for each link in the chain | |
1114 | * from the safe_class lock to the unsafe_class lock. | |
1115 | */ | |
1116 | if (parent != source) { | |
1117 | printk("Chain exists of:\n "); | |
1118 | __print_lock_name(source); | |
f943fe0f | 1119 | printk(KERN_CONT " --> "); |
f4185812 | 1120 | __print_lock_name(parent); |
f943fe0f | 1121 | printk(KERN_CONT " --> "); |
f4185812 | 1122 | __print_lock_name(target); |
f943fe0f | 1123 | printk(KERN_CONT "\n\n"); |
f4185812 SR |
1124 | } |
1125 | ||
e966eaee IM |
1126 | printk(" Possible unsafe locking scenario:\n\n"); |
1127 | printk(" CPU0 CPU1\n"); | |
1128 | printk(" ---- ----\n"); | |
1129 | printk(" lock("); | |
1130 | __print_lock_name(target); | |
1131 | printk(KERN_CONT ");\n"); | |
1132 | printk(" lock("); | |
1133 | __print_lock_name(parent); | |
1134 | printk(KERN_CONT ");\n"); | |
1135 | printk(" lock("); | |
1136 | __print_lock_name(target); | |
1137 | printk(KERN_CONT ");\n"); | |
1138 | printk(" lock("); | |
1139 | __print_lock_name(source); | |
1140 | printk(KERN_CONT ");\n"); | |
1141 | printk("\n *** DEADLOCK ***\n\n"); | |
f4185812 SR |
1142 | } |
1143 | ||
8e18257d PZ |
1144 | /* |
1145 | * When a circular dependency is detected, print the | |
1146 | * header first: | |
1147 | */ | |
1148 | static noinline int | |
db0002a3 ML |
1149 | print_circular_bug_header(struct lock_list *entry, unsigned int depth, |
1150 | struct held_lock *check_src, | |
1151 | struct held_lock *check_tgt) | |
8e18257d PZ |
1152 | { |
1153 | struct task_struct *curr = current; | |
1154 | ||
c94aa5ca | 1155 | if (debug_locks_silent) |
8e18257d PZ |
1156 | return 0; |
1157 | ||
681fbec8 | 1158 | pr_warn("\n"); |
a5dd63ef PM |
1159 | pr_warn("======================================================\n"); |
1160 | pr_warn("WARNING: possible circular locking dependency detected\n"); | |
fbdc4b9a | 1161 | print_kernel_ident(); |
a5dd63ef | 1162 | pr_warn("------------------------------------------------------\n"); |
681fbec8 | 1163 | pr_warn("%s/%d is trying to acquire lock:\n", |
ba25f9dc | 1164 | curr->comm, task_pid_nr(curr)); |
db0002a3 | 1165 | print_lock(check_src); |
383a4bc8 | 1166 | |
e966eaee | 1167 | pr_warn("\nbut task is already holding lock:\n"); |
383a4bc8 | 1168 | |
db0002a3 | 1169 | print_lock(check_tgt); |
681fbec8 PM |
1170 | pr_warn("\nwhich lock already depends on the new lock.\n\n"); |
1171 | pr_warn("\nthe existing dependency chain (in reverse order) is:\n"); | |
8e18257d PZ |
1172 | |
1173 | print_circular_bug_entry(entry, depth); | |
1174 | ||
1175 | return 0; | |
1176 | } | |
1177 | ||
9e2d551e ML |
1178 | static inline int class_equal(struct lock_list *entry, void *data) |
1179 | { | |
1180 | return entry->class == data; | |
1181 | } | |
1182 | ||
db0002a3 ML |
1183 | static noinline int print_circular_bug(struct lock_list *this, |
1184 | struct lock_list *target, | |
1185 | struct held_lock *check_src, | |
383a4bc8 BP |
1186 | struct held_lock *check_tgt, |
1187 | struct stack_trace *trace) | |
8e18257d PZ |
1188 | { |
1189 | struct task_struct *curr = current; | |
c94aa5ca | 1190 | struct lock_list *parent; |
f4185812 | 1191 | struct lock_list *first_parent; |
24208ca7 | 1192 | int depth; |
8e18257d | 1193 | |
c94aa5ca | 1194 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
8e18257d PZ |
1195 | return 0; |
1196 | ||
e966eaee | 1197 | if (!save_trace(&this->trace)) |
8e18257d PZ |
1198 | return 0; |
1199 | ||
c94aa5ca ML |
1200 | depth = get_lock_depth(target); |
1201 | ||
db0002a3 | 1202 | print_circular_bug_header(target, depth, check_src, check_tgt); |
c94aa5ca ML |
1203 | |
1204 | parent = get_lock_parent(target); | |
f4185812 | 1205 | first_parent = parent; |
c94aa5ca ML |
1206 | |
1207 | while (parent) { | |
1208 | print_circular_bug_entry(parent, --depth); | |
1209 | parent = get_lock_parent(parent); | |
1210 | } | |
8e18257d PZ |
1211 | |
1212 | printk("\nother info that might help us debug this:\n\n"); | |
f4185812 SR |
1213 | print_circular_lock_scenario(check_src, check_tgt, |
1214 | first_parent); | |
1215 | ||
8e18257d PZ |
1216 | lockdep_print_held_locks(curr); |
1217 | ||
1218 | printk("\nstack backtrace:\n"); | |
1219 | dump_stack(); | |
1220 | ||
1221 | return 0; | |
1222 | } | |
1223 | ||
db0002a3 ML |
1224 | static noinline int print_bfs_bug(int ret) |
1225 | { | |
1226 | if (!debug_locks_off_graph_unlock()) | |
1227 | return 0; | |
1228 | ||
0119fee4 PZ |
1229 | /* |
1230 | * Breadth-first-search failed, graph got corrupted? | |
1231 | */ | |
db0002a3 ML |
1232 | WARN(1, "lockdep bfs error:%d\n", ret); |
1233 | ||
1234 | return 0; | |
1235 | } | |
1236 | ||
ef681026 | 1237 | static int noop_count(struct lock_list *entry, void *data) |
419ca3f1 | 1238 | { |
ef681026 ML |
1239 | (*(unsigned long *)data)++; |
1240 | return 0; | |
1241 | } | |
419ca3f1 | 1242 | |
5216d530 | 1243 | static unsigned long __lockdep_count_forward_deps(struct lock_list *this) |
ef681026 ML |
1244 | { |
1245 | unsigned long count = 0; | |
1246 | struct lock_list *uninitialized_var(target_entry); | |
419ca3f1 | 1247 | |
ef681026 | 1248 | __bfs_forwards(this, (void *)&count, noop_count, &target_entry); |
419ca3f1 | 1249 | |
ef681026 | 1250 | return count; |
419ca3f1 | 1251 | } |
419ca3f1 DM |
1252 | unsigned long lockdep_count_forward_deps(struct lock_class *class) |
1253 | { | |
1254 | unsigned long ret, flags; | |
ef681026 ML |
1255 | struct lock_list this; |
1256 | ||
1257 | this.parent = NULL; | |
1258 | this.class = class; | |
419ca3f1 DM |
1259 | |
1260 | local_irq_save(flags); | |
0199c4e6 | 1261 | arch_spin_lock(&lockdep_lock); |
ef681026 | 1262 | ret = __lockdep_count_forward_deps(&this); |
0199c4e6 | 1263 | arch_spin_unlock(&lockdep_lock); |
419ca3f1 DM |
1264 | local_irq_restore(flags); |
1265 | ||
1266 | return ret; | |
1267 | } | |
1268 | ||
5216d530 | 1269 | static unsigned long __lockdep_count_backward_deps(struct lock_list *this) |
419ca3f1 | 1270 | { |
ef681026 ML |
1271 | unsigned long count = 0; |
1272 | struct lock_list *uninitialized_var(target_entry); | |
419ca3f1 | 1273 | |
ef681026 | 1274 | __bfs_backwards(this, (void *)&count, noop_count, &target_entry); |
419ca3f1 | 1275 | |
ef681026 | 1276 | return count; |
419ca3f1 DM |
1277 | } |
1278 | ||
1279 | unsigned long lockdep_count_backward_deps(struct lock_class *class) | |
1280 | { | |
1281 | unsigned long ret, flags; | |
ef681026 ML |
1282 | struct lock_list this; |
1283 | ||
1284 | this.parent = NULL; | |
1285 | this.class = class; | |
419ca3f1 DM |
1286 | |
1287 | local_irq_save(flags); | |
0199c4e6 | 1288 | arch_spin_lock(&lockdep_lock); |
ef681026 | 1289 | ret = __lockdep_count_backward_deps(&this); |
0199c4e6 | 1290 | arch_spin_unlock(&lockdep_lock); |
419ca3f1 DM |
1291 | local_irq_restore(flags); |
1292 | ||
1293 | return ret; | |
1294 | } | |
1295 | ||
8e18257d PZ |
1296 | /* |
1297 | * Prove that the dependency graph starting at <entry> can not | |
1298 | * lead to <target>. Print an error and return 0 if it does. | |
1299 | */ | |
1300 | static noinline int | |
db0002a3 ML |
1301 | check_noncircular(struct lock_list *root, struct lock_class *target, |
1302 | struct lock_list **target_entry) | |
8e18257d | 1303 | { |
db0002a3 | 1304 | int result; |
8e18257d | 1305 | |
bd6d29c2 | 1306 | debug_atomic_inc(nr_cyclic_checks); |
419ca3f1 | 1307 | |
d7aaba14 | 1308 | result = __bfs_forwards(root, target, class_equal, target_entry); |
fbb9ce95 | 1309 | |
db0002a3 ML |
1310 | return result; |
1311 | } | |
c94aa5ca | 1312 | |
ae813308 PZ |
1313 | static noinline int |
1314 | check_redundant(struct lock_list *root, struct lock_class *target, | |
1315 | struct lock_list **target_entry) | |
1316 | { | |
1317 | int result; | |
1318 | ||
1319 | debug_atomic_inc(nr_redundant_checks); | |
1320 | ||
1321 | result = __bfs_forwards(root, target, class_equal, target_entry); | |
1322 | ||
1323 | return result; | |
1324 | } | |
1325 | ||
81d68a96 | 1326 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
fbb9ce95 IM |
1327 | /* |
1328 | * Forwards and backwards subgraph searching, for the purposes of | |
1329 | * proving that two subgraphs can be connected by a new dependency | |
1330 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. | |
1331 | */ | |
fbb9ce95 | 1332 | |
d7aaba14 ML |
1333 | static inline int usage_match(struct lock_list *entry, void *bit) |
1334 | { | |
1335 | return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); | |
1336 | } | |
1337 | ||
1338 | ||
1339 | ||
fbb9ce95 IM |
1340 | /* |
1341 | * Find a node in the forwards-direction dependency sub-graph starting | |
d7aaba14 | 1342 | * at @root->class that matches @bit. |
fbb9ce95 | 1343 | * |
d7aaba14 ML |
1344 | * Return 0 if such a node exists in the subgraph, and put that node |
1345 | * into *@target_entry. | |
fbb9ce95 | 1346 | * |
d7aaba14 ML |
1347 | * Return 1 otherwise and keep *@target_entry unchanged. |
1348 | * Return <0 on error. | |
fbb9ce95 | 1349 | */ |
d7aaba14 ML |
1350 | static int |
1351 | find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, | |
1352 | struct lock_list **target_entry) | |
fbb9ce95 | 1353 | { |
d7aaba14 | 1354 | int result; |
fbb9ce95 | 1355 | |
bd6d29c2 | 1356 | debug_atomic_inc(nr_find_usage_forwards_checks); |
fbb9ce95 | 1357 | |
d7aaba14 ML |
1358 | result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); |
1359 | ||
1360 | return result; | |
fbb9ce95 IM |
1361 | } |
1362 | ||
1363 | /* | |
1364 | * Find a node in the backwards-direction dependency sub-graph starting | |
d7aaba14 | 1365 | * at @root->class that matches @bit. |
fbb9ce95 | 1366 | * |
d7aaba14 ML |
1367 | * Return 0 if such a node exists in the subgraph, and put that node |
1368 | * into *@target_entry. | |
fbb9ce95 | 1369 | * |
d7aaba14 ML |
1370 | * Return 1 otherwise and keep *@target_entry unchanged. |
1371 | * Return <0 on error. | |
fbb9ce95 | 1372 | */ |
d7aaba14 ML |
1373 | static int |
1374 | find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, | |
1375 | struct lock_list **target_entry) | |
fbb9ce95 | 1376 | { |
d7aaba14 | 1377 | int result; |
fbb9ce95 | 1378 | |
bd6d29c2 | 1379 | debug_atomic_inc(nr_find_usage_backwards_checks); |
fbb9ce95 | 1380 | |
d7aaba14 | 1381 | result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); |
f82b217e | 1382 | |
d7aaba14 | 1383 | return result; |
fbb9ce95 IM |
1384 | } |
1385 | ||
af012961 PZ |
1386 | static void print_lock_class_header(struct lock_class *class, int depth) |
1387 | { | |
1388 | int bit; | |
1389 | ||
1390 | printk("%*s->", depth, ""); | |
1391 | print_lock_name(class); | |
f943fe0f DV |
1392 | printk(KERN_CONT " ops: %lu", class->ops); |
1393 | printk(KERN_CONT " {\n"); | |
af012961 PZ |
1394 | |
1395 | for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { | |
1396 | if (class->usage_mask & (1 << bit)) { | |
1397 | int len = depth; | |
1398 | ||
1399 | len += printk("%*s %s", depth, "", usage_str[bit]); | |
f943fe0f | 1400 | len += printk(KERN_CONT " at:\n"); |
af012961 PZ |
1401 | print_stack_trace(class->usage_traces + bit, len); |
1402 | } | |
1403 | } | |
1404 | printk("%*s }\n", depth, ""); | |
1405 | ||
f943fe0f DV |
1406 | printk("%*s ... key at: [<%p>] %pS\n", |
1407 | depth, "", class->key, class->key); | |
af012961 PZ |
1408 | } |
1409 | ||
1410 | /* | |
1411 | * printk the shortest lock dependencies from @start to @end in reverse order: | |
1412 | */ | |
1413 | static void __used | |
1414 | print_shortest_lock_dependencies(struct lock_list *leaf, | |
1415 | struct lock_list *root) | |
1416 | { | |
1417 | struct lock_list *entry = leaf; | |
1418 | int depth; | |
1419 | ||
1420 | /*compute depth from generated tree by BFS*/ | |
1421 | depth = get_lock_depth(leaf); | |
1422 | ||
1423 | do { | |
1424 | print_lock_class_header(entry->class, depth); | |
1425 | printk("%*s ... acquired at:\n", depth, ""); | |
1426 | print_stack_trace(&entry->trace, 2); | |
1427 | printk("\n"); | |
1428 | ||
1429 | if (depth == 0 && (entry != root)) { | |
6be8c393 | 1430 | printk("lockdep:%s bad path found in chain graph\n", __func__); |
af012961 PZ |
1431 | break; |
1432 | } | |
1433 | ||
1434 | entry = get_lock_parent(entry); | |
1435 | depth--; | |
1436 | } while (entry && (depth >= 0)); | |
1437 | ||
1438 | return; | |
1439 | } | |
d7aaba14 | 1440 | |
3003eba3 SR |
1441 | static void |
1442 | print_irq_lock_scenario(struct lock_list *safe_entry, | |
1443 | struct lock_list *unsafe_entry, | |
dad3d743 SR |
1444 | struct lock_class *prev_class, |
1445 | struct lock_class *next_class) | |
3003eba3 SR |
1446 | { |
1447 | struct lock_class *safe_class = safe_entry->class; | |
1448 | struct lock_class *unsafe_class = unsafe_entry->class; | |
dad3d743 | 1449 | struct lock_class *middle_class = prev_class; |
3003eba3 SR |
1450 | |
1451 | if (middle_class == safe_class) | |
dad3d743 | 1452 | middle_class = next_class; |
3003eba3 SR |
1453 | |
1454 | /* | |
1455 | * A direct locking problem where unsafe_class lock is taken | |
1456 | * directly by safe_class lock, then all we need to show | |
1457 | * is the deadlock scenario, as it is obvious that the | |
1458 | * unsafe lock is taken under the safe lock. | |
1459 | * | |
1460 | * But if there is a chain instead, where the safe lock takes | |
1461 | * an intermediate lock (middle_class) where this lock is | |
1462 | * not the same as the safe lock, then the lock chain is | |
1463 | * used to describe the problem. Otherwise we would need | |
1464 | * to show a different CPU case for each link in the chain | |
1465 | * from the safe_class lock to the unsafe_class lock. | |
1466 | */ | |
1467 | if (middle_class != unsafe_class) { | |
1468 | printk("Chain exists of:\n "); | |
1469 | __print_lock_name(safe_class); | |
f943fe0f | 1470 | printk(KERN_CONT " --> "); |
3003eba3 | 1471 | __print_lock_name(middle_class); |
f943fe0f | 1472 | printk(KERN_CONT " --> "); |
3003eba3 | 1473 | __print_lock_name(unsafe_class); |
f943fe0f | 1474 | printk(KERN_CONT "\n\n"); |
3003eba3 SR |
1475 | } |
1476 | ||
1477 | printk(" Possible interrupt unsafe locking scenario:\n\n"); | |
1478 | printk(" CPU0 CPU1\n"); | |
1479 | printk(" ---- ----\n"); | |
1480 | printk(" lock("); | |
1481 | __print_lock_name(unsafe_class); | |
f943fe0f | 1482 | printk(KERN_CONT ");\n"); |
3003eba3 SR |
1483 | printk(" local_irq_disable();\n"); |
1484 | printk(" lock("); | |
1485 | __print_lock_name(safe_class); | |
f943fe0f | 1486 | printk(KERN_CONT ");\n"); |
3003eba3 SR |
1487 | printk(" lock("); |
1488 | __print_lock_name(middle_class); | |
f943fe0f | 1489 | printk(KERN_CONT ");\n"); |
3003eba3 SR |
1490 | printk(" <Interrupt>\n"); |
1491 | printk(" lock("); | |
1492 | __print_lock_name(safe_class); | |
f943fe0f | 1493 | printk(KERN_CONT ");\n"); |
3003eba3 SR |
1494 | printk("\n *** DEADLOCK ***\n\n"); |
1495 | } | |
1496 | ||
fbb9ce95 IM |
1497 | static int |
1498 | print_bad_irq_dependency(struct task_struct *curr, | |
24208ca7 ML |
1499 | struct lock_list *prev_root, |
1500 | struct lock_list *next_root, | |
1501 | struct lock_list *backwards_entry, | |
1502 | struct lock_list *forwards_entry, | |
fbb9ce95 IM |
1503 | struct held_lock *prev, |
1504 | struct held_lock *next, | |
1505 | enum lock_usage_bit bit1, | |
1506 | enum lock_usage_bit bit2, | |
1507 | const char *irqclass) | |
1508 | { | |
74c383f1 | 1509 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
fbb9ce95 IM |
1510 | return 0; |
1511 | ||
681fbec8 | 1512 | pr_warn("\n"); |
a5dd63ef PM |
1513 | pr_warn("=====================================================\n"); |
1514 | pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n", | |
fbb9ce95 | 1515 | irqclass, irqclass); |
fbdc4b9a | 1516 | print_kernel_ident(); |
a5dd63ef | 1517 | pr_warn("-----------------------------------------------------\n"); |
681fbec8 | 1518 | pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", |
ba25f9dc | 1519 | curr->comm, task_pid_nr(curr), |
fbb9ce95 IM |
1520 | curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, |
1521 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, | |
1522 | curr->hardirqs_enabled, | |
1523 | curr->softirqs_enabled); | |
1524 | print_lock(next); | |
1525 | ||
681fbec8 | 1526 | pr_warn("\nand this task is already holding:\n"); |
fbb9ce95 | 1527 | print_lock(prev); |
681fbec8 | 1528 | pr_warn("which would create a new lock dependency:\n"); |
f82b217e | 1529 | print_lock_name(hlock_class(prev)); |
681fbec8 | 1530 | pr_cont(" ->"); |
f82b217e | 1531 | print_lock_name(hlock_class(next)); |
681fbec8 | 1532 | pr_cont("\n"); |
fbb9ce95 | 1533 | |
681fbec8 | 1534 | pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n", |
fbb9ce95 | 1535 | irqclass); |
24208ca7 | 1536 | print_lock_name(backwards_entry->class); |
681fbec8 | 1537 | pr_warn("\n... which became %s-irq-safe at:\n", irqclass); |
fbb9ce95 | 1538 | |
24208ca7 | 1539 | print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); |
fbb9ce95 | 1540 | |
681fbec8 | 1541 | pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass); |
24208ca7 | 1542 | print_lock_name(forwards_entry->class); |
681fbec8 PM |
1543 | pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass); |
1544 | pr_warn("..."); | |
fbb9ce95 | 1545 | |
24208ca7 | 1546 | print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); |
fbb9ce95 | 1547 | |
681fbec8 | 1548 | pr_warn("\nother info that might help us debug this:\n\n"); |
dad3d743 SR |
1549 | print_irq_lock_scenario(backwards_entry, forwards_entry, |
1550 | hlock_class(prev), hlock_class(next)); | |
3003eba3 | 1551 | |
fbb9ce95 IM |
1552 | lockdep_print_held_locks(curr); |
1553 | ||
681fbec8 | 1554 | pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); |
24208ca7 ML |
1555 | if (!save_trace(&prev_root->trace)) |
1556 | return 0; | |
1557 | print_shortest_lock_dependencies(backwards_entry, prev_root); | |
fbb9ce95 | 1558 | |
681fbec8 PM |
1559 | pr_warn("\nthe dependencies between the lock to be acquired"); |
1560 | pr_warn(" and %s-irq-unsafe lock:\n", irqclass); | |
24208ca7 ML |
1561 | if (!save_trace(&next_root->trace)) |
1562 | return 0; | |
1563 | print_shortest_lock_dependencies(forwards_entry, next_root); | |
fbb9ce95 | 1564 | |
681fbec8 | 1565 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 IM |
1566 | dump_stack(); |
1567 | ||
1568 | return 0; | |
1569 | } | |
1570 | ||
1571 | static int | |
1572 | check_usage(struct task_struct *curr, struct held_lock *prev, | |
1573 | struct held_lock *next, enum lock_usage_bit bit_backwards, | |
1574 | enum lock_usage_bit bit_forwards, const char *irqclass) | |
1575 | { | |
1576 | int ret; | |
24208ca7 | 1577 | struct lock_list this, that; |
d7aaba14 | 1578 | struct lock_list *uninitialized_var(target_entry); |
24208ca7 | 1579 | struct lock_list *uninitialized_var(target_entry1); |
d7aaba14 ML |
1580 | |
1581 | this.parent = NULL; | |
1582 | ||
1583 | this.class = hlock_class(prev); | |
1584 | ret = find_usage_backwards(&this, bit_backwards, &target_entry); | |
af012961 PZ |
1585 | if (ret < 0) |
1586 | return print_bfs_bug(ret); | |
1587 | if (ret == 1) | |
1588 | return ret; | |
d7aaba14 | 1589 | |
24208ca7 ML |
1590 | that.parent = NULL; |
1591 | that.class = hlock_class(next); | |
1592 | ret = find_usage_forwards(&that, bit_forwards, &target_entry1); | |
af012961 PZ |
1593 | if (ret < 0) |
1594 | return print_bfs_bug(ret); | |
1595 | if (ret == 1) | |
1596 | return ret; | |
fbb9ce95 | 1597 | |
24208ca7 ML |
1598 | return print_bad_irq_dependency(curr, &this, &that, |
1599 | target_entry, target_entry1, | |
1600 | prev, next, | |
fbb9ce95 IM |
1601 | bit_backwards, bit_forwards, irqclass); |
1602 | } | |
1603 | ||
4f367d8a PZ |
1604 | static const char *state_names[] = { |
1605 | #define LOCKDEP_STATE(__STATE) \ | |
b4b136f4 | 1606 | __stringify(__STATE), |
4f367d8a PZ |
1607 | #include "lockdep_states.h" |
1608 | #undef LOCKDEP_STATE | |
1609 | }; | |
1610 | ||
1611 | static const char *state_rnames[] = { | |
1612 | #define LOCKDEP_STATE(__STATE) \ | |
b4b136f4 | 1613 | __stringify(__STATE)"-READ", |
4f367d8a PZ |
1614 | #include "lockdep_states.h" |
1615 | #undef LOCKDEP_STATE | |
1616 | }; | |
1617 | ||
1618 | static inline const char *state_name(enum lock_usage_bit bit) | |
8e18257d | 1619 | { |
4f367d8a PZ |
1620 | return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2]; |
1621 | } | |
8e18257d | 1622 | |
4f367d8a PZ |
1623 | static int exclusive_bit(int new_bit) |
1624 | { | |
8e18257d | 1625 | /* |
4f367d8a PZ |
1626 | * USED_IN |
1627 | * USED_IN_READ | |
1628 | * ENABLED | |
1629 | * ENABLED_READ | |
1630 | * | |
1631 | * bit 0 - write/read | |
1632 | * bit 1 - used_in/enabled | |
1633 | * bit 2+ state | |
8e18257d | 1634 | */ |
4f367d8a PZ |
1635 | |
1636 | int state = new_bit & ~3; | |
1637 | int dir = new_bit & 2; | |
8e18257d PZ |
1638 | |
1639 | /* | |
4f367d8a | 1640 | * keep state, bit flip the direction and strip read. |
8e18257d | 1641 | */ |
4f367d8a PZ |
1642 | return state | (dir ^ 2); |
1643 | } | |
1644 | ||
1645 | static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, | |
1646 | struct held_lock *next, enum lock_usage_bit bit) | |
1647 | { | |
8e18257d | 1648 | /* |
4f367d8a PZ |
1649 | * Prove that the new dependency does not connect a hardirq-safe |
1650 | * lock with a hardirq-unsafe lock - to achieve this we search | |
8e18257d PZ |
1651 | * the backwards-subgraph starting at <prev>, and the |
1652 | * forwards-subgraph starting at <next>: | |
1653 | */ | |
4f367d8a PZ |
1654 | if (!check_usage(curr, prev, next, bit, |
1655 | exclusive_bit(bit), state_name(bit))) | |
8e18257d PZ |
1656 | return 0; |
1657 | ||
4f367d8a PZ |
1658 | bit++; /* _READ */ |
1659 | ||
cf40bd16 | 1660 | /* |
4f367d8a PZ |
1661 | * Prove that the new dependency does not connect a hardirq-safe-read |
1662 | * lock with a hardirq-unsafe lock - to achieve this we search | |
cf40bd16 NP |
1663 | * the backwards-subgraph starting at <prev>, and the |
1664 | * forwards-subgraph starting at <next>: | |
1665 | */ | |
4f367d8a PZ |
1666 | if (!check_usage(curr, prev, next, bit, |
1667 | exclusive_bit(bit), state_name(bit))) | |
cf40bd16 NP |
1668 | return 0; |
1669 | ||
4f367d8a PZ |
1670 | return 1; |
1671 | } | |
1672 | ||
1673 | static int | |
1674 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, | |
1675 | struct held_lock *next) | |
1676 | { | |
1677 | #define LOCKDEP_STATE(__STATE) \ | |
1678 | if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ | |
cf40bd16 | 1679 | return 0; |
4f367d8a PZ |
1680 | #include "lockdep_states.h" |
1681 | #undef LOCKDEP_STATE | |
cf40bd16 | 1682 | |
8e18257d PZ |
1683 | return 1; |
1684 | } | |
1685 | ||
1686 | static void inc_chains(void) | |
1687 | { | |
1688 | if (current->hardirq_context) | |
1689 | nr_hardirq_chains++; | |
1690 | else { | |
1691 | if (current->softirq_context) | |
1692 | nr_softirq_chains++; | |
1693 | else | |
1694 | nr_process_chains++; | |
1695 | } | |
1696 | } | |
1697 | ||
1698 | #else | |
1699 | ||
1700 | static inline int | |
1701 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, | |
1702 | struct held_lock *next) | |
1703 | { | |
1704 | return 1; | |
1705 | } | |
1706 | ||
1707 | static inline void inc_chains(void) | |
1708 | { | |
1709 | nr_process_chains++; | |
1710 | } | |
1711 | ||
fbb9ce95 IM |
1712 | #endif |
1713 | ||
48702ecf SR |
1714 | static void |
1715 | print_deadlock_scenario(struct held_lock *nxt, | |
1716 | struct held_lock *prv) | |
1717 | { | |
1718 | struct lock_class *next = hlock_class(nxt); | |
1719 | struct lock_class *prev = hlock_class(prv); | |
1720 | ||
1721 | printk(" Possible unsafe locking scenario:\n\n"); | |
1722 | printk(" CPU0\n"); | |
1723 | printk(" ----\n"); | |
1724 | printk(" lock("); | |
1725 | __print_lock_name(prev); | |
f943fe0f | 1726 | printk(KERN_CONT ");\n"); |
48702ecf SR |
1727 | printk(" lock("); |
1728 | __print_lock_name(next); | |
f943fe0f | 1729 | printk(KERN_CONT ");\n"); |
48702ecf SR |
1730 | printk("\n *** DEADLOCK ***\n\n"); |
1731 | printk(" May be due to missing lock nesting notation\n\n"); | |
1732 | } | |
1733 | ||
fbb9ce95 IM |
1734 | static int |
1735 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, | |
1736 | struct held_lock *next) | |
1737 | { | |
74c383f1 | 1738 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
fbb9ce95 IM |
1739 | return 0; |
1740 | ||
681fbec8 | 1741 | pr_warn("\n"); |
a5dd63ef PM |
1742 | pr_warn("============================================\n"); |
1743 | pr_warn("WARNING: possible recursive locking detected\n"); | |
fbdc4b9a | 1744 | print_kernel_ident(); |
a5dd63ef | 1745 | pr_warn("--------------------------------------------\n"); |
681fbec8 | 1746 | pr_warn("%s/%d is trying to acquire lock:\n", |
ba25f9dc | 1747 | curr->comm, task_pid_nr(curr)); |
fbb9ce95 | 1748 | print_lock(next); |
681fbec8 | 1749 | pr_warn("\nbut task is already holding lock:\n"); |
fbb9ce95 IM |
1750 | print_lock(prev); |
1751 | ||
681fbec8 | 1752 | pr_warn("\nother info that might help us debug this:\n"); |
48702ecf | 1753 | print_deadlock_scenario(next, prev); |
fbb9ce95 IM |
1754 | lockdep_print_held_locks(curr); |
1755 | ||
681fbec8 | 1756 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 IM |
1757 | dump_stack(); |
1758 | ||
1759 | return 0; | |
1760 | } | |
1761 | ||
1762 | /* | |
1763 | * Check whether we are holding such a class already. | |
1764 | * | |
1765 | * (Note that this has to be done separately, because the graph cannot | |
1766 | * detect such classes of deadlocks.) | |
1767 | * | |
1768 | * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read | |
1769 | */ | |
1770 | static int | |
1771 | check_deadlock(struct task_struct *curr, struct held_lock *next, | |
1772 | struct lockdep_map *next_instance, int read) | |
1773 | { | |
1774 | struct held_lock *prev; | |
7531e2f3 | 1775 | struct held_lock *nest = NULL; |
fbb9ce95 IM |
1776 | int i; |
1777 | ||
1778 | for (i = 0; i < curr->lockdep_depth; i++) { | |
1779 | prev = curr->held_locks + i; | |
7531e2f3 PZ |
1780 | |
1781 | if (prev->instance == next->nest_lock) | |
1782 | nest = prev; | |
1783 | ||
f82b217e | 1784 | if (hlock_class(prev) != hlock_class(next)) |
fbb9ce95 | 1785 | continue; |
7531e2f3 | 1786 | |
fbb9ce95 IM |
1787 | /* |
1788 | * Allow read-after-read recursion of the same | |
6c9076ec | 1789 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
fbb9ce95 | 1790 | */ |
6c9076ec | 1791 | if ((read == 2) && prev->read) |
fbb9ce95 | 1792 | return 2; |
7531e2f3 PZ |
1793 | |
1794 | /* | |
1795 | * We're holding the nest_lock, which serializes this lock's | |
1796 | * nesting behaviour. | |
1797 | */ | |
1798 | if (nest) | |
1799 | return 2; | |
1800 | ||
fbb9ce95 IM |
1801 | return print_deadlock_bug(curr, prev, next); |
1802 | } | |
1803 | return 1; | |
1804 | } | |
1805 | ||
1806 | /* | |
1807 | * There was a chain-cache miss, and we are about to add a new dependency | |
1808 | * to a previous lock. We recursively validate the following rules: | |
1809 | * | |
1810 | * - would the adding of the <prev> -> <next> dependency create a | |
1811 | * circular dependency in the graph? [== circular deadlock] | |
1812 | * | |
1813 | * - does the new prev->next dependency connect any hardirq-safe lock | |
1814 | * (in the full backwards-subgraph starting at <prev>) with any | |
1815 | * hardirq-unsafe lock (in the full forwards-subgraph starting at | |
1816 | * <next>)? [== illegal lock inversion with hardirq contexts] | |
1817 | * | |
1818 | * - does the new prev->next dependency connect any softirq-safe lock | |
1819 | * (in the full backwards-subgraph starting at <prev>) with any | |
1820 | * softirq-unsafe lock (in the full forwards-subgraph starting at | |
1821 | * <next>)? [== illegal lock inversion with softirq contexts] | |
1822 | * | |
1823 | * any of these scenarios could lead to a deadlock. | |
1824 | * | |
1825 | * Then if all the validations pass, we add the forwards and backwards | |
1826 | * dependency. | |
1827 | */ | |
1828 | static int | |
1829 | check_prev_add(struct task_struct *curr, struct held_lock *prev, | |
ce07a941 BP |
1830 | struct held_lock *next, int distance, struct stack_trace *trace, |
1831 | int (*save)(struct stack_trace *trace)) | |
fbb9ce95 | 1832 | { |
8b405d5c | 1833 | struct lock_list *uninitialized_var(target_entry); |
fbb9ce95 | 1834 | struct lock_list *entry; |
db0002a3 | 1835 | struct lock_list this; |
8b405d5c | 1836 | int ret; |
fbb9ce95 IM |
1837 | |
1838 | /* | |
1839 | * Prove that the new <prev> -> <next> dependency would not | |
1840 | * create a circular dependency in the graph. (We do this by | |
1841 | * forward-recursing into the graph starting at <next>, and | |
1842 | * checking whether we can reach <prev>.) | |
1843 | * | |
1844 | * We are using global variables to control the recursion, to | |
1845 | * keep the stackframe size of the recursive functions low: | |
1846 | */ | |
db0002a3 ML |
1847 | this.class = hlock_class(next); |
1848 | this.parent = NULL; | |
1849 | ret = check_noncircular(&this, hlock_class(prev), &target_entry); | |
8b405d5c PZ |
1850 | if (unlikely(!ret)) { |
1851 | if (!trace->entries) { | |
1852 | /* | |
1853 | * If @save fails here, the printing might trigger | |
1854 | * a WARN but because of the !nr_entries it should | |
1855 | * not do bad things. | |
1856 | */ | |
1857 | save(trace); | |
1858 | } | |
383a4bc8 | 1859 | return print_circular_bug(&this, target_entry, next, prev, trace); |
8b405d5c | 1860 | } |
db0002a3 ML |
1861 | else if (unlikely(ret < 0)) |
1862 | return print_bfs_bug(ret); | |
c94aa5ca | 1863 | |
8e18257d | 1864 | if (!check_prev_add_irq(curr, prev, next)) |
fbb9ce95 IM |
1865 | return 0; |
1866 | ||
fbb9ce95 IM |
1867 | /* |
1868 | * For recursive read-locks we do all the dependency checks, | |
1869 | * but we dont store read-triggered dependencies (only | |
1870 | * write-triggered dependencies). This ensures that only the | |
1871 | * write-side dependencies matter, and that if for example a | |
1872 | * write-lock never takes any other locks, then the reads are | |
1873 | * equivalent to a NOP. | |
1874 | */ | |
1875 | if (next->read == 2 || prev->read == 2) | |
1876 | return 1; | |
1877 | /* | |
1878 | * Is the <prev> -> <next> dependency already present? | |
1879 | * | |
1880 | * (this may occur even though this is a new chain: consider | |
1881 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 | |
1882 | * chains - the second one will be new, but L1 already has | |
1883 | * L2 added to its dependency list, due to the first chain.) | |
1884 | */ | |
f82b217e DJ |
1885 | list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { |
1886 | if (entry->class == hlock_class(next)) { | |
068135e6 JB |
1887 | if (distance == 1) |
1888 | entry->distance = 1; | |
70911fdc | 1889 | return 1; |
068135e6 | 1890 | } |
fbb9ce95 IM |
1891 | } |
1892 | ||
ae813308 PZ |
1893 | /* |
1894 | * Is the <prev> -> <next> link redundant? | |
1895 | */ | |
1896 | this.class = hlock_class(prev); | |
1897 | this.parent = NULL; | |
1898 | ret = check_redundant(&this, hlock_class(next), &target_entry); | |
1899 | if (!ret) { | |
1900 | debug_atomic_inc(nr_redundant); | |
1901 | return 2; | |
1902 | } | |
1903 | if (ret < 0) | |
1904 | return print_bfs_bug(ret); | |
1905 | ||
1906 | ||
8b405d5c | 1907 | if (!trace->entries && !save(trace)) |
ce07a941 | 1908 | return 0; |
4726f2a6 | 1909 | |
fbb9ce95 IM |
1910 | /* |
1911 | * Ok, all validations passed, add the new lock | |
1912 | * to the previous lock's dependency list: | |
1913 | */ | |
83f06168 | 1914 | ret = add_lock_to_list(hlock_class(next), |
f82b217e | 1915 | &hlock_class(prev)->locks_after, |
ce07a941 | 1916 | next->acquire_ip, distance, trace); |
068135e6 | 1917 | |
fbb9ce95 IM |
1918 | if (!ret) |
1919 | return 0; | |
910b1b2e | 1920 | |
83f06168 | 1921 | ret = add_lock_to_list(hlock_class(prev), |
f82b217e | 1922 | &hlock_class(next)->locks_before, |
ce07a941 | 1923 | next->acquire_ip, distance, trace); |
910b1b2e JP |
1924 | if (!ret) |
1925 | return 0; | |
fbb9ce95 | 1926 | |
70911fdc | 1927 | return 2; |
8e18257d | 1928 | } |
fbb9ce95 | 1929 | |
8e18257d PZ |
1930 | /* |
1931 | * Add the dependency to all directly-previous locks that are 'relevant'. | |
1932 | * The ones that are relevant are (in increasing distance from curr): | |
1933 | * all consecutive trylock entries and the final non-trylock entry - or | |
1934 | * the end of this context's lock-chain - whichever comes first. | |
1935 | */ | |
1936 | static int | |
1937 | check_prevs_add(struct task_struct *curr, struct held_lock *next) | |
1938 | { | |
1939 | int depth = curr->lockdep_depth; | |
1940 | struct held_lock *hlock; | |
8b405d5c PZ |
1941 | struct stack_trace trace = { |
1942 | .nr_entries = 0, | |
1943 | .max_entries = 0, | |
1944 | .entries = NULL, | |
1945 | .skip = 0, | |
1946 | }; | |
d6d897ce | 1947 | |
fbb9ce95 | 1948 | /* |
8e18257d PZ |
1949 | * Debugging checks. |
1950 | * | |
1951 | * Depth must not be zero for a non-head lock: | |
fbb9ce95 | 1952 | */ |
8e18257d PZ |
1953 | if (!depth) |
1954 | goto out_bug; | |
fbb9ce95 | 1955 | /* |
8e18257d PZ |
1956 | * At least two relevant locks must exist for this |
1957 | * to be a head: | |
fbb9ce95 | 1958 | */ |
8e18257d PZ |
1959 | if (curr->held_locks[depth].irq_context != |
1960 | curr->held_locks[depth-1].irq_context) | |
1961 | goto out_bug; | |
74c383f1 | 1962 | |
8e18257d PZ |
1963 | for (;;) { |
1964 | int distance = curr->lockdep_depth - depth + 1; | |
1b5ff816 | 1965 | hlock = curr->held_locks + depth - 1; |
e966eaee | 1966 | |
8e18257d | 1967 | /* |
e966eaee IM |
1968 | * Only non-recursive-read entries get new dependencies |
1969 | * added: | |
8e18257d | 1970 | */ |
e966eaee IM |
1971 | if (hlock->read != 2 && hlock->check) { |
1972 | int ret = check_prev_add(curr, hlock, next, distance, &trace, save_trace); | |
1973 | if (!ret) | |
1974 | return 0; | |
1975 | ||
ce07a941 | 1976 | /* |
e966eaee IM |
1977 | * Stop after the first non-trylock entry, |
1978 | * as non-trylock entries have added their | |
1979 | * own direct dependencies already, so this | |
1980 | * lock is connected to them indirectly: | |
ce07a941 | 1981 | */ |
e966eaee IM |
1982 | if (!hlock->trylock) |
1983 | break; | |
74c383f1 | 1984 | } |
e966eaee | 1985 | |
8e18257d PZ |
1986 | depth--; |
1987 | /* | |
1988 | * End of lock-stack? | |
1989 | */ | |
1990 | if (!depth) | |
1991 | break; | |
1992 | /* | |
1993 | * Stop the search if we cross into another context: | |
1994 | */ | |
1995 | if (curr->held_locks[depth].irq_context != | |
1996 | curr->held_locks[depth-1].irq_context) | |
1997 | break; | |
fbb9ce95 | 1998 | } |
8e18257d PZ |
1999 | return 1; |
2000 | out_bug: | |
2001 | if (!debug_locks_off_graph_unlock()) | |
2002 | return 0; | |
fbb9ce95 | 2003 | |
0119fee4 PZ |
2004 | /* |
2005 | * Clearly we all shouldn't be here, but since we made it we | |
2006 | * can reliable say we messed up our state. See the above two | |
2007 | * gotos for reasons why we could possibly end up here. | |
2008 | */ | |
8e18257d | 2009 | WARN_ON(1); |
fbb9ce95 | 2010 | |
8e18257d | 2011 | return 0; |
fbb9ce95 IM |
2012 | } |
2013 | ||
8e18257d | 2014 | unsigned long nr_lock_chains; |
443cd507 | 2015 | struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; |
cd1a28e8 | 2016 | int nr_chain_hlocks; |
443cd507 HY |
2017 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; |
2018 | ||
2019 | struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) | |
2020 | { | |
2021 | return lock_classes + chain_hlocks[chain->base + i]; | |
2022 | } | |
8e18257d | 2023 | |
9e4e7554 IM |
2024 | /* |
2025 | * Returns the index of the first held_lock of the current chain | |
2026 | */ | |
2027 | static inline int get_first_held_lock(struct task_struct *curr, | |
2028 | struct held_lock *hlock) | |
2029 | { | |
2030 | int i; | |
2031 | struct held_lock *hlock_curr; | |
2032 | ||
2033 | for (i = curr->lockdep_depth - 1; i >= 0; i--) { | |
2034 | hlock_curr = curr->held_locks + i; | |
2035 | if (hlock_curr->irq_context != hlock->irq_context) | |
2036 | break; | |
2037 | ||
2038 | } | |
2039 | ||
2040 | return ++i; | |
2041 | } | |
2042 | ||
5c8a010c | 2043 | #ifdef CONFIG_DEBUG_LOCKDEP |
39e2e173 AAF |
2044 | /* |
2045 | * Returns the next chain_key iteration | |
2046 | */ | |
2047 | static u64 print_chain_key_iteration(int class_idx, u64 chain_key) | |
2048 | { | |
2049 | u64 new_chain_key = iterate_chain_key(chain_key, class_idx); | |
2050 | ||
2051 | printk(" class_idx:%d -> chain_key:%016Lx", | |
2052 | class_idx, | |
2053 | (unsigned long long)new_chain_key); | |
2054 | return new_chain_key; | |
2055 | } | |
2056 | ||
2057 | static void | |
2058 | print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next) | |
2059 | { | |
2060 | struct held_lock *hlock; | |
2061 | u64 chain_key = 0; | |
2062 | int depth = curr->lockdep_depth; | |
2063 | int i; | |
2064 | ||
2065 | printk("depth: %u\n", depth + 1); | |
2066 | for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) { | |
2067 | hlock = curr->held_locks + i; | |
2068 | chain_key = print_chain_key_iteration(hlock->class_idx, chain_key); | |
2069 | ||
2070 | print_lock(hlock); | |
2071 | } | |
2072 | ||
2073 | print_chain_key_iteration(hlock_next->class_idx, chain_key); | |
2074 | print_lock(hlock_next); | |
2075 | } | |
2076 | ||
2077 | static void print_chain_keys_chain(struct lock_chain *chain) | |
2078 | { | |
2079 | int i; | |
2080 | u64 chain_key = 0; | |
2081 | int class_id; | |
2082 | ||
2083 | printk("depth: %u\n", chain->depth); | |
2084 | for (i = 0; i < chain->depth; i++) { | |
2085 | class_id = chain_hlocks[chain->base + i]; | |
2086 | chain_key = print_chain_key_iteration(class_id + 1, chain_key); | |
2087 | ||
2088 | print_lock_name(lock_classes + class_id); | |
2089 | printk("\n"); | |
2090 | } | |
2091 | } | |
2092 | ||
2093 | static void print_collision(struct task_struct *curr, | |
2094 | struct held_lock *hlock_next, | |
2095 | struct lock_chain *chain) | |
2096 | { | |
681fbec8 | 2097 | pr_warn("\n"); |
a5dd63ef PM |
2098 | pr_warn("============================\n"); |
2099 | pr_warn("WARNING: chain_key collision\n"); | |
39e2e173 | 2100 | print_kernel_ident(); |
a5dd63ef | 2101 | pr_warn("----------------------------\n"); |
681fbec8 PM |
2102 | pr_warn("%s/%d: ", current->comm, task_pid_nr(current)); |
2103 | pr_warn("Hash chain already cached but the contents don't match!\n"); | |
39e2e173 | 2104 | |
681fbec8 | 2105 | pr_warn("Held locks:"); |
39e2e173 AAF |
2106 | print_chain_keys_held_locks(curr, hlock_next); |
2107 | ||
681fbec8 | 2108 | pr_warn("Locks in cached chain:"); |
39e2e173 AAF |
2109 | print_chain_keys_chain(chain); |
2110 | ||
681fbec8 | 2111 | pr_warn("\nstack backtrace:\n"); |
39e2e173 AAF |
2112 | dump_stack(); |
2113 | } | |
5c8a010c | 2114 | #endif |
39e2e173 | 2115 | |
9e4e7554 IM |
2116 | /* |
2117 | * Checks whether the chain and the current held locks are consistent | |
2118 | * in depth and also in content. If they are not it most likely means | |
2119 | * that there was a collision during the calculation of the chain_key. | |
2120 | * Returns: 0 not passed, 1 passed | |
2121 | */ | |
2122 | static int check_no_collision(struct task_struct *curr, | |
2123 | struct held_lock *hlock, | |
2124 | struct lock_chain *chain) | |
2125 | { | |
2126 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2127 | int i, j, id; | |
2128 | ||
2129 | i = get_first_held_lock(curr, hlock); | |
2130 | ||
39e2e173 AAF |
2131 | if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) { |
2132 | print_collision(curr, hlock, chain); | |
9e4e7554 | 2133 | return 0; |
39e2e173 | 2134 | } |
9e4e7554 IM |
2135 | |
2136 | for (j = 0; j < chain->depth - 1; j++, i++) { | |
2137 | id = curr->held_locks[i].class_idx - 1; | |
2138 | ||
39e2e173 AAF |
2139 | if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) { |
2140 | print_collision(curr, hlock, chain); | |
9e4e7554 | 2141 | return 0; |
39e2e173 | 2142 | } |
9e4e7554 IM |
2143 | } |
2144 | #endif | |
2145 | return 1; | |
2146 | } | |
2147 | ||
49347a98 BP |
2148 | /* |
2149 | * This is for building a chain between just two different classes, | |
2150 | * instead of adding a new hlock upon current, which is done by | |
2151 | * add_chain_cache(). | |
2152 | * | |
2153 | * This can be called in any context with two classes, while | |
2154 | * add_chain_cache() must be done within the lock owener's context | |
2155 | * since it uses hlock which might be racy in another context. | |
2156 | */ | |
2157 | static inline int add_chain_cache_classes(unsigned int prev, | |
2158 | unsigned int next, | |
2159 | unsigned int irq_context, | |
2160 | u64 chain_key) | |
2161 | { | |
2162 | struct hlist_head *hash_head = chainhashentry(chain_key); | |
2163 | struct lock_chain *chain; | |
2164 | ||
2165 | /* | |
2166 | * Allocate a new chain entry from the static array, and add | |
2167 | * it to the hash: | |
2168 | */ | |
2169 | ||
2170 | /* | |
2171 | * We might need to take the graph lock, ensure we've got IRQs | |
2172 | * disabled to make this an IRQ-safe lock.. for recursion reasons | |
2173 | * lockdep won't complain about its own locking errors. | |
2174 | */ | |
2175 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
2176 | return 0; | |
2177 | ||
2178 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { | |
2179 | if (!debug_locks_off_graph_unlock()) | |
2180 | return 0; | |
2181 | ||
2182 | print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); | |
2183 | dump_stack(); | |
2184 | return 0; | |
2185 | } | |
2186 | ||
2187 | chain = lock_chains + nr_lock_chains++; | |
2188 | chain->chain_key = chain_key; | |
2189 | chain->irq_context = irq_context; | |
2190 | chain->depth = 2; | |
2191 | if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { | |
2192 | chain->base = nr_chain_hlocks; | |
2193 | nr_chain_hlocks += chain->depth; | |
2194 | chain_hlocks[chain->base] = prev - 1; | |
2195 | chain_hlocks[chain->base + 1] = next -1; | |
2196 | } | |
2197 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2198 | /* | |
2199 | * Important for check_no_collision(). | |
2200 | */ | |
2201 | else { | |
2202 | if (!debug_locks_off_graph_unlock()) | |
2203 | return 0; | |
2204 | ||
2205 | print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); | |
2206 | dump_stack(); | |
2207 | return 0; | |
2208 | } | |
2209 | #endif | |
2210 | ||
2211 | hlist_add_head_rcu(&chain->entry, hash_head); | |
2212 | debug_atomic_inc(chain_lookup_misses); | |
2213 | inc_chains(); | |
2214 | ||
2215 | return 1; | |
2216 | } | |
2217 | ||
fbb9ce95 | 2218 | /* |
545c23f2 BP |
2219 | * Adds a dependency chain into chain hashtable. And must be called with |
2220 | * graph_lock held. | |
2221 | * | |
2222 | * Return 0 if fail, and graph_lock is released. | |
2223 | * Return 1 if succeed, with graph_lock held. | |
fbb9ce95 | 2224 | */ |
545c23f2 BP |
2225 | static inline int add_chain_cache(struct task_struct *curr, |
2226 | struct held_lock *hlock, | |
2227 | u64 chain_key) | |
fbb9ce95 | 2228 | { |
f82b217e | 2229 | struct lock_class *class = hlock_class(hlock); |
a63f38cc | 2230 | struct hlist_head *hash_head = chainhashentry(chain_key); |
fbb9ce95 | 2231 | struct lock_chain *chain; |
e0944ee6 | 2232 | int i, j; |
fbb9ce95 | 2233 | |
545c23f2 BP |
2234 | /* |
2235 | * Allocate a new chain entry from the static array, and add | |
2236 | * it to the hash: | |
2237 | */ | |
2238 | ||
0119fee4 PZ |
2239 | /* |
2240 | * We might need to take the graph lock, ensure we've got IRQs | |
2241 | * disabled to make this an IRQ-safe lock.. for recursion reasons | |
2242 | * lockdep won't complain about its own locking errors. | |
2243 | */ | |
381a2292 JP |
2244 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2245 | return 0; | |
9e4e7554 | 2246 | |
fbb9ce95 | 2247 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { |
74c383f1 IM |
2248 | if (!debug_locks_off_graph_unlock()) |
2249 | return 0; | |
2250 | ||
2c522836 | 2251 | print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); |
eedeeabd | 2252 | dump_stack(); |
fbb9ce95 IM |
2253 | return 0; |
2254 | } | |
2255 | chain = lock_chains + nr_lock_chains++; | |
2256 | chain->chain_key = chain_key; | |
443cd507 | 2257 | chain->irq_context = hlock->irq_context; |
9e4e7554 | 2258 | i = get_first_held_lock(curr, hlock); |
443cd507 | 2259 | chain->depth = curr->lockdep_depth + 1 - i; |
75dd602a PZ |
2260 | |
2261 | BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks)); | |
2262 | BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks)); | |
2263 | BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes)); | |
2264 | ||
e0944ee6 SR |
2265 | if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { |
2266 | chain->base = nr_chain_hlocks; | |
443cd507 | 2267 | for (j = 0; j < chain->depth - 1; j++, i++) { |
f82b217e | 2268 | int lock_id = curr->held_locks[i].class_idx - 1; |
443cd507 HY |
2269 | chain_hlocks[chain->base + j] = lock_id; |
2270 | } | |
2271 | chain_hlocks[chain->base + j] = class - lock_classes; | |
2272 | } | |
75dd602a PZ |
2273 | |
2274 | if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS) | |
2275 | nr_chain_hlocks += chain->depth; | |
2276 | ||
2277 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2278 | /* | |
2279 | * Important for check_no_collision(). | |
2280 | */ | |
2281 | if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) { | |
f9af456a | 2282 | if (!debug_locks_off_graph_unlock()) |
75dd602a PZ |
2283 | return 0; |
2284 | ||
2285 | print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); | |
2286 | dump_stack(); | |
2287 | return 0; | |
2288 | } | |
2289 | #endif | |
2290 | ||
a63f38cc | 2291 | hlist_add_head_rcu(&chain->entry, hash_head); |
bd6d29c2 | 2292 | debug_atomic_inc(chain_lookup_misses); |
8e18257d PZ |
2293 | inc_chains(); |
2294 | ||
2295 | return 1; | |
2296 | } | |
2297 | ||
545c23f2 BP |
2298 | /* |
2299 | * Look up a dependency chain. | |
2300 | */ | |
2301 | static inline struct lock_chain *lookup_chain_cache(u64 chain_key) | |
2302 | { | |
2303 | struct hlist_head *hash_head = chainhashentry(chain_key); | |
2304 | struct lock_chain *chain; | |
2305 | ||
2306 | /* | |
2307 | * We can walk it lock-free, because entries only get added | |
2308 | * to the hash: | |
2309 | */ | |
2310 | hlist_for_each_entry_rcu(chain, hash_head, entry) { | |
2311 | if (chain->chain_key == chain_key) { | |
2312 | debug_atomic_inc(chain_lookup_hits); | |
2313 | return chain; | |
2314 | } | |
2315 | } | |
2316 | return NULL; | |
2317 | } | |
2318 | ||
2319 | /* | |
2320 | * If the key is not present yet in dependency chain cache then | |
2321 | * add it and return 1 - in this case the new dependency chain is | |
2322 | * validated. If the key is already hashed, return 0. | |
2323 | * (On return with 1 graph_lock is held.) | |
2324 | */ | |
2325 | static inline int lookup_chain_cache_add(struct task_struct *curr, | |
2326 | struct held_lock *hlock, | |
2327 | u64 chain_key) | |
2328 | { | |
2329 | struct lock_class *class = hlock_class(hlock); | |
2330 | struct lock_chain *chain = lookup_chain_cache(chain_key); | |
2331 | ||
2332 | if (chain) { | |
2333 | cache_hit: | |
2334 | if (!check_no_collision(curr, hlock, chain)) | |
2335 | return 0; | |
2336 | ||
2337 | if (very_verbose(class)) { | |
2338 | printk("\nhash chain already cached, key: " | |
2339 | "%016Lx tail class: [%p] %s\n", | |
2340 | (unsigned long long)chain_key, | |
2341 | class->key, class->name); | |
2342 | } | |
2343 | ||
2344 | return 0; | |
2345 | } | |
2346 | ||
2347 | if (very_verbose(class)) { | |
2348 | printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", | |
2349 | (unsigned long long)chain_key, class->key, class->name); | |
2350 | } | |
2351 | ||
2352 | if (!graph_lock()) | |
2353 | return 0; | |
2354 | ||
2355 | /* | |
2356 | * We have to walk the chain again locked - to avoid duplicates: | |
2357 | */ | |
2358 | chain = lookup_chain_cache(chain_key); | |
2359 | if (chain) { | |
2360 | graph_unlock(); | |
2361 | goto cache_hit; | |
2362 | } | |
2363 | ||
2364 | if (!add_chain_cache(curr, hlock, chain_key)) | |
2365 | return 0; | |
2366 | ||
2367 | return 1; | |
2368 | } | |
2369 | ||
8e18257d | 2370 | static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, |
4e6045f1 | 2371 | struct held_lock *hlock, int chain_head, u64 chain_key) |
8e18257d PZ |
2372 | { |
2373 | /* | |
2374 | * Trylock needs to maintain the stack of held locks, but it | |
2375 | * does not add new dependencies, because trylock can be done | |
2376 | * in any order. | |
2377 | * | |
2378 | * We look up the chain_key and do the O(N^2) check and update of | |
2379 | * the dependencies only if this is a new dependency chain. | |
545c23f2 | 2380 | * (If lookup_chain_cache_add() return with 1 it acquires |
8e18257d PZ |
2381 | * graph_lock for us) |
2382 | */ | |
fb9edbe9 | 2383 | if (!hlock->trylock && hlock->check && |
545c23f2 | 2384 | lookup_chain_cache_add(curr, hlock, chain_key)) { |
8e18257d PZ |
2385 | /* |
2386 | * Check whether last held lock: | |
2387 | * | |
2388 | * - is irq-safe, if this lock is irq-unsafe | |
2389 | * - is softirq-safe, if this lock is hardirq-unsafe | |
2390 | * | |
2391 | * And check whether the new lock's dependency graph | |
2392 | * could lead back to the previous lock. | |
2393 | * | |
2394 | * any of these scenarios could lead to a deadlock. If | |
2395 | * All validations | |
2396 | */ | |
2397 | int ret = check_deadlock(curr, hlock, lock, hlock->read); | |
2398 | ||
2399 | if (!ret) | |
2400 | return 0; | |
2401 | /* | |
2402 | * Mark recursive read, as we jump over it when | |
2403 | * building dependencies (just like we jump over | |
2404 | * trylock entries): | |
2405 | */ | |
2406 | if (ret == 2) | |
2407 | hlock->read = 2; | |
2408 | /* | |
2409 | * Add dependency only if this lock is not the head | |
2410 | * of the chain, and if it's not a secondary read-lock: | |
2411 | */ | |
545c23f2 | 2412 | if (!chain_head && ret != 2) { |
8e18257d PZ |
2413 | if (!check_prevs_add(curr, hlock)) |
2414 | return 0; | |
545c23f2 BP |
2415 | } |
2416 | ||
8e18257d | 2417 | graph_unlock(); |
545c23f2 BP |
2418 | } else { |
2419 | /* after lookup_chain_cache_add(): */ | |
8e18257d PZ |
2420 | if (unlikely(!debug_locks)) |
2421 | return 0; | |
545c23f2 | 2422 | } |
fbb9ce95 IM |
2423 | |
2424 | return 1; | |
2425 | } | |
8e18257d PZ |
2426 | #else |
2427 | static inline int validate_chain(struct task_struct *curr, | |
2428 | struct lockdep_map *lock, struct held_lock *hlock, | |
3aa416b0 | 2429 | int chain_head, u64 chain_key) |
8e18257d PZ |
2430 | { |
2431 | return 1; | |
2432 | } | |
ca58abcb | 2433 | #endif |
fbb9ce95 IM |
2434 | |
2435 | /* | |
2436 | * We are building curr_chain_key incrementally, so double-check | |
2437 | * it from scratch, to make sure that it's done correctly: | |
2438 | */ | |
1d09daa5 | 2439 | static void check_chain_key(struct task_struct *curr) |
fbb9ce95 IM |
2440 | { |
2441 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2442 | struct held_lock *hlock, *prev_hlock = NULL; | |
5f18ab5c | 2443 | unsigned int i; |
fbb9ce95 IM |
2444 | u64 chain_key = 0; |
2445 | ||
2446 | for (i = 0; i < curr->lockdep_depth; i++) { | |
2447 | hlock = curr->held_locks + i; | |
2448 | if (chain_key != hlock->prev_chain_key) { | |
2449 | debug_locks_off(); | |
0119fee4 PZ |
2450 | /* |
2451 | * We got mighty confused, our chain keys don't match | |
2452 | * with what we expect, someone trample on our task state? | |
2453 | */ | |
2df8b1d6 | 2454 | WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", |
fbb9ce95 IM |
2455 | curr->lockdep_depth, i, |
2456 | (unsigned long long)chain_key, | |
2457 | (unsigned long long)hlock->prev_chain_key); | |
fbb9ce95 IM |
2458 | return; |
2459 | } | |
0119fee4 PZ |
2460 | /* |
2461 | * Whoops ran out of static storage again? | |
2462 | */ | |
5f18ab5c | 2463 | if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS)) |
381a2292 JP |
2464 | return; |
2465 | ||
fbb9ce95 IM |
2466 | if (prev_hlock && (prev_hlock->irq_context != |
2467 | hlock->irq_context)) | |
2468 | chain_key = 0; | |
5f18ab5c | 2469 | chain_key = iterate_chain_key(chain_key, hlock->class_idx); |
fbb9ce95 IM |
2470 | prev_hlock = hlock; |
2471 | } | |
2472 | if (chain_key != curr->curr_chain_key) { | |
2473 | debug_locks_off(); | |
0119fee4 PZ |
2474 | /* |
2475 | * More smoking hash instead of calculating it, damn see these | |
2476 | * numbers float.. I bet that a pink elephant stepped on my memory. | |
2477 | */ | |
2df8b1d6 | 2478 | WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", |
fbb9ce95 IM |
2479 | curr->lockdep_depth, i, |
2480 | (unsigned long long)chain_key, | |
2481 | (unsigned long long)curr->curr_chain_key); | |
fbb9ce95 IM |
2482 | } |
2483 | #endif | |
2484 | } | |
2485 | ||
282b5c2f SR |
2486 | static void |
2487 | print_usage_bug_scenario(struct held_lock *lock) | |
2488 | { | |
2489 | struct lock_class *class = hlock_class(lock); | |
2490 | ||
2491 | printk(" Possible unsafe locking scenario:\n\n"); | |
2492 | printk(" CPU0\n"); | |
2493 | printk(" ----\n"); | |
2494 | printk(" lock("); | |
2495 | __print_lock_name(class); | |
f943fe0f | 2496 | printk(KERN_CONT ");\n"); |
282b5c2f SR |
2497 | printk(" <Interrupt>\n"); |
2498 | printk(" lock("); | |
2499 | __print_lock_name(class); | |
f943fe0f | 2500 | printk(KERN_CONT ");\n"); |
282b5c2f SR |
2501 | printk("\n *** DEADLOCK ***\n\n"); |
2502 | } | |
2503 | ||
8e18257d PZ |
2504 | static int |
2505 | print_usage_bug(struct task_struct *curr, struct held_lock *this, | |
2506 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) | |
2507 | { | |
2508 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) | |
2509 | return 0; | |
2510 | ||
681fbec8 | 2511 | pr_warn("\n"); |
a5dd63ef PM |
2512 | pr_warn("================================\n"); |
2513 | pr_warn("WARNING: inconsistent lock state\n"); | |
fbdc4b9a | 2514 | print_kernel_ident(); |
a5dd63ef | 2515 | pr_warn("--------------------------------\n"); |
8e18257d | 2516 | |
681fbec8 | 2517 | pr_warn("inconsistent {%s} -> {%s} usage.\n", |
8e18257d PZ |
2518 | usage_str[prev_bit], usage_str[new_bit]); |
2519 | ||
681fbec8 | 2520 | pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", |
ba25f9dc | 2521 | curr->comm, task_pid_nr(curr), |
8e18257d PZ |
2522 | trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, |
2523 | trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, | |
2524 | trace_hardirqs_enabled(curr), | |
2525 | trace_softirqs_enabled(curr)); | |
2526 | print_lock(this); | |
2527 | ||
681fbec8 | 2528 | pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]); |
f82b217e | 2529 | print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1); |
8e18257d PZ |
2530 | |
2531 | print_irqtrace_events(curr); | |
681fbec8 | 2532 | pr_warn("\nother info that might help us debug this:\n"); |
282b5c2f SR |
2533 | print_usage_bug_scenario(this); |
2534 | ||
8e18257d PZ |
2535 | lockdep_print_held_locks(curr); |
2536 | ||
681fbec8 | 2537 | pr_warn("\nstack backtrace:\n"); |
8e18257d PZ |
2538 | dump_stack(); |
2539 | ||
2540 | return 0; | |
2541 | } | |
2542 | ||
2543 | /* | |
2544 | * Print out an error if an invalid bit is set: | |
2545 | */ | |
2546 | static inline int | |
2547 | valid_state(struct task_struct *curr, struct held_lock *this, | |
2548 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) | |
2549 | { | |
f82b217e | 2550 | if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) |
8e18257d PZ |
2551 | return print_usage_bug(curr, this, bad_bit, new_bit); |
2552 | return 1; | |
2553 | } | |
2554 | ||
2555 | static int mark_lock(struct task_struct *curr, struct held_lock *this, | |
2556 | enum lock_usage_bit new_bit); | |
2557 | ||
81d68a96 | 2558 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
fbb9ce95 IM |
2559 | |
2560 | /* | |
2561 | * print irq inversion bug: | |
2562 | */ | |
2563 | static int | |
24208ca7 ML |
2564 | print_irq_inversion_bug(struct task_struct *curr, |
2565 | struct lock_list *root, struct lock_list *other, | |
fbb9ce95 IM |
2566 | struct held_lock *this, int forwards, |
2567 | const char *irqclass) | |
2568 | { | |
dad3d743 SR |
2569 | struct lock_list *entry = other; |
2570 | struct lock_list *middle = NULL; | |
2571 | int depth; | |
2572 | ||
74c383f1 | 2573 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
fbb9ce95 IM |
2574 | return 0; |
2575 | ||
681fbec8 | 2576 | pr_warn("\n"); |
a5dd63ef PM |
2577 | pr_warn("========================================================\n"); |
2578 | pr_warn("WARNING: possible irq lock inversion dependency detected\n"); | |
fbdc4b9a | 2579 | print_kernel_ident(); |
a5dd63ef | 2580 | pr_warn("--------------------------------------------------------\n"); |
681fbec8 | 2581 | pr_warn("%s/%d just changed the state of lock:\n", |
ba25f9dc | 2582 | curr->comm, task_pid_nr(curr)); |
fbb9ce95 IM |
2583 | print_lock(this); |
2584 | if (forwards) | |
681fbec8 | 2585 | pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass); |
fbb9ce95 | 2586 | else |
681fbec8 | 2587 | pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); |
24208ca7 | 2588 | print_lock_name(other->class); |
681fbec8 | 2589 | pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n"); |
fbb9ce95 | 2590 | |
681fbec8 | 2591 | pr_warn("\nother info that might help us debug this:\n"); |
dad3d743 SR |
2592 | |
2593 | /* Find a middle lock (if one exists) */ | |
2594 | depth = get_lock_depth(other); | |
2595 | do { | |
2596 | if (depth == 0 && (entry != root)) { | |
681fbec8 | 2597 | pr_warn("lockdep:%s bad path found in chain graph\n", __func__); |
dad3d743 SR |
2598 | break; |
2599 | } | |
2600 | middle = entry; | |
2601 | entry = get_lock_parent(entry); | |
2602 | depth--; | |
2603 | } while (entry && entry != root && (depth >= 0)); | |
2604 | if (forwards) | |
2605 | print_irq_lock_scenario(root, other, | |
2606 | middle ? middle->class : root->class, other->class); | |
2607 | else | |
2608 | print_irq_lock_scenario(other, root, | |
2609 | middle ? middle->class : other->class, root->class); | |
2610 | ||
fbb9ce95 IM |
2611 | lockdep_print_held_locks(curr); |
2612 | ||
681fbec8 | 2613 | pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); |
24208ca7 ML |
2614 | if (!save_trace(&root->trace)) |
2615 | return 0; | |
2616 | print_shortest_lock_dependencies(other, root); | |
fbb9ce95 | 2617 | |
681fbec8 | 2618 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 IM |
2619 | dump_stack(); |
2620 | ||
2621 | return 0; | |
2622 | } | |
2623 | ||
2624 | /* | |
2625 | * Prove that in the forwards-direction subgraph starting at <this> | |
2626 | * there is no lock matching <mask>: | |
2627 | */ | |
2628 | static int | |
2629 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, | |
2630 | enum lock_usage_bit bit, const char *irqclass) | |
2631 | { | |
2632 | int ret; | |
d7aaba14 ML |
2633 | struct lock_list root; |
2634 | struct lock_list *uninitialized_var(target_entry); | |
fbb9ce95 | 2635 | |
d7aaba14 ML |
2636 | root.parent = NULL; |
2637 | root.class = hlock_class(this); | |
2638 | ret = find_usage_forwards(&root, bit, &target_entry); | |
af012961 PZ |
2639 | if (ret < 0) |
2640 | return print_bfs_bug(ret); | |
2641 | if (ret == 1) | |
2642 | return ret; | |
fbb9ce95 | 2643 | |
24208ca7 | 2644 | return print_irq_inversion_bug(curr, &root, target_entry, |
d7aaba14 | 2645 | this, 1, irqclass); |
fbb9ce95 IM |
2646 | } |
2647 | ||
2648 | /* | |
2649 | * Prove that in the backwards-direction subgraph starting at <this> | |
2650 | * there is no lock matching <mask>: | |
2651 | */ | |
2652 | static int | |
2653 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, | |
2654 | enum lock_usage_bit bit, const char *irqclass) | |
2655 | { | |
2656 | int ret; | |
d7aaba14 ML |
2657 | struct lock_list root; |
2658 | struct lock_list *uninitialized_var(target_entry); | |
fbb9ce95 | 2659 | |
d7aaba14 ML |
2660 | root.parent = NULL; |
2661 | root.class = hlock_class(this); | |
2662 | ret = find_usage_backwards(&root, bit, &target_entry); | |
af012961 PZ |
2663 | if (ret < 0) |
2664 | return print_bfs_bug(ret); | |
2665 | if (ret == 1) | |
2666 | return ret; | |
fbb9ce95 | 2667 | |
24208ca7 | 2668 | return print_irq_inversion_bug(curr, &root, target_entry, |
48d50674 | 2669 | this, 0, irqclass); |
fbb9ce95 IM |
2670 | } |
2671 | ||
3117df04 | 2672 | void print_irqtrace_events(struct task_struct *curr) |
fbb9ce95 IM |
2673 | { |
2674 | printk("irq event stamp: %u\n", curr->irq_events); | |
f943fe0f DV |
2675 | printk("hardirqs last enabled at (%u): [<%p>] %pS\n", |
2676 | curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip, | |
2677 | (void *)curr->hardirq_enable_ip); | |
2678 | printk("hardirqs last disabled at (%u): [<%p>] %pS\n", | |
2679 | curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip, | |
2680 | (void *)curr->hardirq_disable_ip); | |
2681 | printk("softirqs last enabled at (%u): [<%p>] %pS\n", | |
2682 | curr->softirq_enable_event, (void *)curr->softirq_enable_ip, | |
2683 | (void *)curr->softirq_enable_ip); | |
2684 | printk("softirqs last disabled at (%u): [<%p>] %pS\n", | |
2685 | curr->softirq_disable_event, (void *)curr->softirq_disable_ip, | |
2686 | (void *)curr->softirq_disable_ip); | |
fbb9ce95 IM |
2687 | } |
2688 | ||
cd95302d | 2689 | static int HARDIRQ_verbose(struct lock_class *class) |
fbb9ce95 | 2690 | { |
8e18257d PZ |
2691 | #if HARDIRQ_VERBOSE |
2692 | return class_filter(class); | |
2693 | #endif | |
fbb9ce95 IM |
2694 | return 0; |
2695 | } | |
2696 | ||
cd95302d | 2697 | static int SOFTIRQ_verbose(struct lock_class *class) |
fbb9ce95 | 2698 | { |
8e18257d PZ |
2699 | #if SOFTIRQ_VERBOSE |
2700 | return class_filter(class); | |
2701 | #endif | |
2702 | return 0; | |
fbb9ce95 IM |
2703 | } |
2704 | ||
2705 | #define STRICT_READ_CHECKS 1 | |
2706 | ||
cd95302d PZ |
2707 | static int (*state_verbose_f[])(struct lock_class *class) = { |
2708 | #define LOCKDEP_STATE(__STATE) \ | |
2709 | __STATE##_verbose, | |
2710 | #include "lockdep_states.h" | |
2711 | #undef LOCKDEP_STATE | |
2712 | }; | |
2713 | ||
2714 | static inline int state_verbose(enum lock_usage_bit bit, | |
2715 | struct lock_class *class) | |
2716 | { | |
2717 | return state_verbose_f[bit >> 2](class); | |
2718 | } | |
2719 | ||
42c50d54 PZ |
2720 | typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, |
2721 | enum lock_usage_bit bit, const char *name); | |
2722 | ||
6a6904d3 | 2723 | static int |
1c21f14e PZ |
2724 | mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
2725 | enum lock_usage_bit new_bit) | |
6a6904d3 | 2726 | { |
f989209e | 2727 | int excl_bit = exclusive_bit(new_bit); |
9d3651a2 | 2728 | int read = new_bit & 1; |
42c50d54 PZ |
2729 | int dir = new_bit & 2; |
2730 | ||
38aa2714 PZ |
2731 | /* |
2732 | * mark USED_IN has to look forwards -- to ensure no dependency | |
2733 | * has ENABLED state, which would allow recursion deadlocks. | |
2734 | * | |
2735 | * mark ENABLED has to look backwards -- to ensure no dependee | |
2736 | * has USED_IN state, which, again, would allow recursion deadlocks. | |
2737 | */ | |
42c50d54 PZ |
2738 | check_usage_f usage = dir ? |
2739 | check_usage_backwards : check_usage_forwards; | |
f989209e | 2740 | |
38aa2714 PZ |
2741 | /* |
2742 | * Validate that this particular lock does not have conflicting | |
2743 | * usage states. | |
2744 | */ | |
6a6904d3 PZ |
2745 | if (!valid_state(curr, this, new_bit, excl_bit)) |
2746 | return 0; | |
42c50d54 | 2747 | |
38aa2714 PZ |
2748 | /* |
2749 | * Validate that the lock dependencies don't have conflicting usage | |
2750 | * states. | |
2751 | */ | |
2752 | if ((!read || !dir || STRICT_READ_CHECKS) && | |
1c21f14e | 2753 | !usage(curr, this, excl_bit, state_name(new_bit & ~1))) |
6a6904d3 | 2754 | return 0; |
780e820b | 2755 | |
38aa2714 PZ |
2756 | /* |
2757 | * Check for read in write conflicts | |
2758 | */ | |
2759 | if (!read) { | |
2760 | if (!valid_state(curr, this, new_bit, excl_bit + 1)) | |
2761 | return 0; | |
2762 | ||
2763 | if (STRICT_READ_CHECKS && | |
4f367d8a PZ |
2764 | !usage(curr, this, excl_bit + 1, |
2765 | state_name(new_bit + 1))) | |
38aa2714 PZ |
2766 | return 0; |
2767 | } | |
780e820b | 2768 | |
cd95302d | 2769 | if (state_verbose(new_bit, hlock_class(this))) |
6a6904d3 PZ |
2770 | return 2; |
2771 | ||
2772 | return 1; | |
2773 | } | |
2774 | ||
cf40bd16 | 2775 | enum mark_type { |
36bfb9bb PZ |
2776 | #define LOCKDEP_STATE(__STATE) __STATE, |
2777 | #include "lockdep_states.h" | |
2778 | #undef LOCKDEP_STATE | |
cf40bd16 NP |
2779 | }; |
2780 | ||
fbb9ce95 IM |
2781 | /* |
2782 | * Mark all held locks with a usage bit: | |
2783 | */ | |
1d09daa5 | 2784 | static int |
cf40bd16 | 2785 | mark_held_locks(struct task_struct *curr, enum mark_type mark) |
fbb9ce95 IM |
2786 | { |
2787 | enum lock_usage_bit usage_bit; | |
2788 | struct held_lock *hlock; | |
2789 | int i; | |
2790 | ||
2791 | for (i = 0; i < curr->lockdep_depth; i++) { | |
2792 | hlock = curr->held_locks + i; | |
2793 | ||
cf2ad4d1 PZ |
2794 | usage_bit = 2 + (mark << 2); /* ENABLED */ |
2795 | if (hlock->read) | |
2796 | usage_bit += 1; /* READ */ | |
2797 | ||
2798 | BUG_ON(usage_bit >= LOCK_USAGE_STATES); | |
cf40bd16 | 2799 | |
34d0ed5e | 2800 | if (!hlock->check) |
efbe2eee PZ |
2801 | continue; |
2802 | ||
4ff773bb | 2803 | if (!mark_lock(curr, hlock, usage_bit)) |
fbb9ce95 IM |
2804 | return 0; |
2805 | } | |
2806 | ||
2807 | return 1; | |
2808 | } | |
2809 | ||
fbb9ce95 IM |
2810 | /* |
2811 | * Hardirqs will be enabled: | |
2812 | */ | |
dd4e5d3a | 2813 | static void __trace_hardirqs_on_caller(unsigned long ip) |
fbb9ce95 IM |
2814 | { |
2815 | struct task_struct *curr = current; | |
fbb9ce95 | 2816 | |
fbb9ce95 IM |
2817 | /* we'll do an OFF -> ON transition: */ |
2818 | curr->hardirqs_enabled = 1; | |
fbb9ce95 | 2819 | |
fbb9ce95 IM |
2820 | /* |
2821 | * We are going to turn hardirqs on, so set the | |
2822 | * usage bit for all held locks: | |
2823 | */ | |
cf40bd16 | 2824 | if (!mark_held_locks(curr, HARDIRQ)) |
fbb9ce95 IM |
2825 | return; |
2826 | /* | |
2827 | * If we have softirqs enabled, then set the usage | |
2828 | * bit for all held locks. (disabled hardirqs prevented | |
2829 | * this bit from being set before) | |
2830 | */ | |
2831 | if (curr->softirqs_enabled) | |
cf40bd16 | 2832 | if (!mark_held_locks(curr, SOFTIRQ)) |
fbb9ce95 IM |
2833 | return; |
2834 | ||
8e18257d PZ |
2835 | curr->hardirq_enable_ip = ip; |
2836 | curr->hardirq_enable_event = ++curr->irq_events; | |
bd6d29c2 | 2837 | debug_atomic_inc(hardirqs_on_events); |
8e18257d | 2838 | } |
dd4e5d3a | 2839 | |
b35f8305 | 2840 | __visible void trace_hardirqs_on_caller(unsigned long ip) |
dd4e5d3a PZ |
2841 | { |
2842 | time_hardirqs_on(CALLER_ADDR0, ip); | |
2843 | ||
2844 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
2845 | return; | |
2846 | ||
7d36b26b PZ |
2847 | if (unlikely(current->hardirqs_enabled)) { |
2848 | /* | |
2849 | * Neither irq nor preemption are disabled here | |
2850 | * so this is racy by nature but losing one hit | |
2851 | * in a stat is not a big deal. | |
2852 | */ | |
2853 | __debug_atomic_inc(redundant_hardirqs_on); | |
2854 | return; | |
2855 | } | |
2856 | ||
0119fee4 PZ |
2857 | /* |
2858 | * We're enabling irqs and according to our state above irqs weren't | |
2859 | * already enabled, yet we find the hardware thinks they are in fact | |
2860 | * enabled.. someone messed up their IRQ state tracing. | |
2861 | */ | |
dd4e5d3a PZ |
2862 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2863 | return; | |
2864 | ||
0119fee4 PZ |
2865 | /* |
2866 | * See the fine text that goes along with this variable definition. | |
2867 | */ | |
7d36b26b PZ |
2868 | if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) |
2869 | return; | |
2870 | ||
0119fee4 PZ |
2871 | /* |
2872 | * Can't allow enabling interrupts while in an interrupt handler, | |
2873 | * that's general bad form and such. Recursion, limited stack etc.. | |
2874 | */ | |
7d36b26b PZ |
2875 | if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) |
2876 | return; | |
2877 | ||
dd4e5d3a PZ |
2878 | current->lockdep_recursion = 1; |
2879 | __trace_hardirqs_on_caller(ip); | |
2880 | current->lockdep_recursion = 0; | |
2881 | } | |
81d68a96 | 2882 | EXPORT_SYMBOL(trace_hardirqs_on_caller); |
8e18257d | 2883 | |
1d09daa5 | 2884 | void trace_hardirqs_on(void) |
81d68a96 SR |
2885 | { |
2886 | trace_hardirqs_on_caller(CALLER_ADDR0); | |
2887 | } | |
8e18257d PZ |
2888 | EXPORT_SYMBOL(trace_hardirqs_on); |
2889 | ||
2890 | /* | |
2891 | * Hardirqs were disabled: | |
2892 | */ | |
b35f8305 | 2893 | __visible void trace_hardirqs_off_caller(unsigned long ip) |
8e18257d PZ |
2894 | { |
2895 | struct task_struct *curr = current; | |
2896 | ||
6afe40b4 | 2897 | time_hardirqs_off(CALLER_ADDR0, ip); |
81d68a96 | 2898 | |
8e18257d PZ |
2899 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
2900 | return; | |
2901 | ||
0119fee4 PZ |
2902 | /* |
2903 | * So we're supposed to get called after you mask local IRQs, but for | |
2904 | * some reason the hardware doesn't quite think you did a proper job. | |
2905 | */ | |
8e18257d PZ |
2906 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2907 | return; | |
2908 | ||
2909 | if (curr->hardirqs_enabled) { | |
2910 | /* | |
2911 | * We have done an ON -> OFF transition: | |
2912 | */ | |
2913 | curr->hardirqs_enabled = 0; | |
6afe40b4 | 2914 | curr->hardirq_disable_ip = ip; |
8e18257d | 2915 | curr->hardirq_disable_event = ++curr->irq_events; |
bd6d29c2 | 2916 | debug_atomic_inc(hardirqs_off_events); |
8e18257d | 2917 | } else |
bd6d29c2 | 2918 | debug_atomic_inc(redundant_hardirqs_off); |
8e18257d | 2919 | } |
81d68a96 | 2920 | EXPORT_SYMBOL(trace_hardirqs_off_caller); |
8e18257d | 2921 | |
1d09daa5 | 2922 | void trace_hardirqs_off(void) |
81d68a96 SR |
2923 | { |
2924 | trace_hardirqs_off_caller(CALLER_ADDR0); | |
2925 | } | |
8e18257d PZ |
2926 | EXPORT_SYMBOL(trace_hardirqs_off); |
2927 | ||
2928 | /* | |
2929 | * Softirqs will be enabled: | |
2930 | */ | |
2931 | void trace_softirqs_on(unsigned long ip) | |
2932 | { | |
2933 | struct task_struct *curr = current; | |
2934 | ||
dd4e5d3a | 2935 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
8e18257d PZ |
2936 | return; |
2937 | ||
0119fee4 PZ |
2938 | /* |
2939 | * We fancy IRQs being disabled here, see softirq.c, avoids | |
2940 | * funny state and nesting things. | |
2941 | */ | |
8e18257d PZ |
2942 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2943 | return; | |
2944 | ||
2945 | if (curr->softirqs_enabled) { | |
bd6d29c2 | 2946 | debug_atomic_inc(redundant_softirqs_on); |
8e18257d PZ |
2947 | return; |
2948 | } | |
2949 | ||
dd4e5d3a | 2950 | current->lockdep_recursion = 1; |
8e18257d PZ |
2951 | /* |
2952 | * We'll do an OFF -> ON transition: | |
2953 | */ | |
2954 | curr->softirqs_enabled = 1; | |
2955 | curr->softirq_enable_ip = ip; | |
2956 | curr->softirq_enable_event = ++curr->irq_events; | |
bd6d29c2 | 2957 | debug_atomic_inc(softirqs_on_events); |
8e18257d PZ |
2958 | /* |
2959 | * We are going to turn softirqs on, so set the | |
2960 | * usage bit for all held locks, if hardirqs are | |
2961 | * enabled too: | |
2962 | */ | |
2963 | if (curr->hardirqs_enabled) | |
cf40bd16 | 2964 | mark_held_locks(curr, SOFTIRQ); |
dd4e5d3a | 2965 | current->lockdep_recursion = 0; |
8e18257d PZ |
2966 | } |
2967 | ||
2968 | /* | |
2969 | * Softirqs were disabled: | |
2970 | */ | |
2971 | void trace_softirqs_off(unsigned long ip) | |
2972 | { | |
2973 | struct task_struct *curr = current; | |
2974 | ||
dd4e5d3a | 2975 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
8e18257d PZ |
2976 | return; |
2977 | ||
0119fee4 PZ |
2978 | /* |
2979 | * We fancy IRQs being disabled here, see softirq.c | |
2980 | */ | |
8e18257d PZ |
2981 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
2982 | return; | |
2983 | ||
2984 | if (curr->softirqs_enabled) { | |
2985 | /* | |
2986 | * We have done an ON -> OFF transition: | |
2987 | */ | |
2988 | curr->softirqs_enabled = 0; | |
2989 | curr->softirq_disable_ip = ip; | |
2990 | curr->softirq_disable_event = ++curr->irq_events; | |
bd6d29c2 | 2991 | debug_atomic_inc(softirqs_off_events); |
0119fee4 PZ |
2992 | /* |
2993 | * Whoops, we wanted softirqs off, so why aren't they? | |
2994 | */ | |
8e18257d PZ |
2995 | DEBUG_LOCKS_WARN_ON(!softirq_count()); |
2996 | } else | |
bd6d29c2 | 2997 | debug_atomic_inc(redundant_softirqs_off); |
8e18257d PZ |
2998 | } |
2999 | ||
3000 | static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) | |
3001 | { | |
3002 | /* | |
3003 | * If non-trylock use in a hardirq or softirq context, then | |
3004 | * mark the lock as used in these contexts: | |
3005 | */ | |
3006 | if (!hlock->trylock) { | |
3007 | if (hlock->read) { | |
3008 | if (curr->hardirq_context) | |
3009 | if (!mark_lock(curr, hlock, | |
3010 | LOCK_USED_IN_HARDIRQ_READ)) | |
3011 | return 0; | |
3012 | if (curr->softirq_context) | |
3013 | if (!mark_lock(curr, hlock, | |
3014 | LOCK_USED_IN_SOFTIRQ_READ)) | |
3015 | return 0; | |
3016 | } else { | |
3017 | if (curr->hardirq_context) | |
3018 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) | |
3019 | return 0; | |
3020 | if (curr->softirq_context) | |
3021 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) | |
3022 | return 0; | |
3023 | } | |
3024 | } | |
3025 | if (!hlock->hardirqs_off) { | |
3026 | if (hlock->read) { | |
3027 | if (!mark_lock(curr, hlock, | |
4fc95e86 | 3028 | LOCK_ENABLED_HARDIRQ_READ)) |
8e18257d PZ |
3029 | return 0; |
3030 | if (curr->softirqs_enabled) | |
3031 | if (!mark_lock(curr, hlock, | |
4fc95e86 | 3032 | LOCK_ENABLED_SOFTIRQ_READ)) |
8e18257d PZ |
3033 | return 0; |
3034 | } else { | |
3035 | if (!mark_lock(curr, hlock, | |
4fc95e86 | 3036 | LOCK_ENABLED_HARDIRQ)) |
8e18257d PZ |
3037 | return 0; |
3038 | if (curr->softirqs_enabled) | |
3039 | if (!mark_lock(curr, hlock, | |
4fc95e86 | 3040 | LOCK_ENABLED_SOFTIRQ)) |
8e18257d PZ |
3041 | return 0; |
3042 | } | |
3043 | } | |
3044 | ||
3045 | return 1; | |
3046 | } | |
3047 | ||
c2469756 BF |
3048 | static inline unsigned int task_irq_context(struct task_struct *task) |
3049 | { | |
3050 | return 2 * !!task->hardirq_context + !!task->softirq_context; | |
3051 | } | |
3052 | ||
8e18257d PZ |
3053 | static int separate_irq_context(struct task_struct *curr, |
3054 | struct held_lock *hlock) | |
3055 | { | |
3056 | unsigned int depth = curr->lockdep_depth; | |
3057 | ||
3058 | /* | |
3059 | * Keep track of points where we cross into an interrupt context: | |
3060 | */ | |
8e18257d PZ |
3061 | if (depth) { |
3062 | struct held_lock *prev_hlock; | |
3063 | ||
3064 | prev_hlock = curr->held_locks + depth-1; | |
3065 | /* | |
3066 | * If we cross into another context, reset the | |
3067 | * hash key (this also prevents the checking and the | |
3068 | * adding of the dependency to 'prev'): | |
3069 | */ | |
3070 | if (prev_hlock->irq_context != hlock->irq_context) | |
3071 | return 1; | |
3072 | } | |
3073 | return 0; | |
fbb9ce95 IM |
3074 | } |
3075 | ||
0119fee4 | 3076 | #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ |
fbb9ce95 | 3077 | |
8e18257d PZ |
3078 | static inline |
3079 | int mark_lock_irq(struct task_struct *curr, struct held_lock *this, | |
3080 | enum lock_usage_bit new_bit) | |
fbb9ce95 | 3081 | { |
0119fee4 | 3082 | WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */ |
8e18257d PZ |
3083 | return 1; |
3084 | } | |
fbb9ce95 | 3085 | |
8e18257d PZ |
3086 | static inline int mark_irqflags(struct task_struct *curr, |
3087 | struct held_lock *hlock) | |
3088 | { | |
3089 | return 1; | |
3090 | } | |
fbb9ce95 | 3091 | |
c2469756 BF |
3092 | static inline unsigned int task_irq_context(struct task_struct *task) |
3093 | { | |
3094 | return 0; | |
3095 | } | |
3096 | ||
8e18257d PZ |
3097 | static inline int separate_irq_context(struct task_struct *curr, |
3098 | struct held_lock *hlock) | |
3099 | { | |
3100 | return 0; | |
fbb9ce95 IM |
3101 | } |
3102 | ||
0119fee4 | 3103 | #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ |
fbb9ce95 IM |
3104 | |
3105 | /* | |
8e18257d | 3106 | * Mark a lock with a usage bit, and validate the state transition: |
fbb9ce95 | 3107 | */ |
1d09daa5 | 3108 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
0764d23c | 3109 | enum lock_usage_bit new_bit) |
fbb9ce95 | 3110 | { |
8e18257d | 3111 | unsigned int new_mask = 1 << new_bit, ret = 1; |
fbb9ce95 IM |
3112 | |
3113 | /* | |
8e18257d PZ |
3114 | * If already set then do not dirty the cacheline, |
3115 | * nor do any checks: | |
fbb9ce95 | 3116 | */ |
f82b217e | 3117 | if (likely(hlock_class(this)->usage_mask & new_mask)) |
8e18257d PZ |
3118 | return 1; |
3119 | ||
3120 | if (!graph_lock()) | |
3121 | return 0; | |
fbb9ce95 | 3122 | /* |
25985edc | 3123 | * Make sure we didn't race: |
fbb9ce95 | 3124 | */ |
f82b217e | 3125 | if (unlikely(hlock_class(this)->usage_mask & new_mask)) { |
8e18257d PZ |
3126 | graph_unlock(); |
3127 | return 1; | |
3128 | } | |
fbb9ce95 | 3129 | |
f82b217e | 3130 | hlock_class(this)->usage_mask |= new_mask; |
fbb9ce95 | 3131 | |
f82b217e | 3132 | if (!save_trace(hlock_class(this)->usage_traces + new_bit)) |
8e18257d | 3133 | return 0; |
fbb9ce95 | 3134 | |
8e18257d | 3135 | switch (new_bit) { |
5346417e PZ |
3136 | #define LOCKDEP_STATE(__STATE) \ |
3137 | case LOCK_USED_IN_##__STATE: \ | |
3138 | case LOCK_USED_IN_##__STATE##_READ: \ | |
3139 | case LOCK_ENABLED_##__STATE: \ | |
3140 | case LOCK_ENABLED_##__STATE##_READ: | |
3141 | #include "lockdep_states.h" | |
3142 | #undef LOCKDEP_STATE | |
8e18257d PZ |
3143 | ret = mark_lock_irq(curr, this, new_bit); |
3144 | if (!ret) | |
3145 | return 0; | |
3146 | break; | |
3147 | case LOCK_USED: | |
bd6d29c2 | 3148 | debug_atomic_dec(nr_unused_locks); |
8e18257d PZ |
3149 | break; |
3150 | default: | |
3151 | if (!debug_locks_off_graph_unlock()) | |
3152 | return 0; | |
3153 | WARN_ON(1); | |
3154 | return 0; | |
3155 | } | |
fbb9ce95 | 3156 | |
8e18257d PZ |
3157 | graph_unlock(); |
3158 | ||
3159 | /* | |
3160 | * We must printk outside of the graph_lock: | |
3161 | */ | |
3162 | if (ret == 2) { | |
3163 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); | |
3164 | print_lock(this); | |
3165 | print_irqtrace_events(curr); | |
3166 | dump_stack(); | |
3167 | } | |
3168 | ||
3169 | return ret; | |
3170 | } | |
fbb9ce95 IM |
3171 | |
3172 | /* | |
3173 | * Initialize a lock instance's lock-class mapping info: | |
3174 | */ | |
b09be676 | 3175 | static void __lockdep_init_map(struct lockdep_map *lock, const char *name, |
4dfbb9d8 | 3176 | struct lock_class_key *key, int subclass) |
fbb9ce95 | 3177 | { |
d3d03d4f YZ |
3178 | int i; |
3179 | ||
d3d03d4f YZ |
3180 | for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) |
3181 | lock->class_cache[i] = NULL; | |
62016250 | 3182 | |
c8a25005 PZ |
3183 | #ifdef CONFIG_LOCK_STAT |
3184 | lock->cpu = raw_smp_processor_id(); | |
3185 | #endif | |
3186 | ||
0119fee4 PZ |
3187 | /* |
3188 | * Can't be having no nameless bastards around this place! | |
3189 | */ | |
c8a25005 PZ |
3190 | if (DEBUG_LOCKS_WARN_ON(!name)) { |
3191 | lock->name = "NULL"; | |
fbb9ce95 | 3192 | return; |
c8a25005 PZ |
3193 | } |
3194 | ||
3195 | lock->name = name; | |
fbb9ce95 | 3196 | |
0119fee4 PZ |
3197 | /* |
3198 | * No key, no joy, we need to hash something. | |
3199 | */ | |
fbb9ce95 IM |
3200 | if (DEBUG_LOCKS_WARN_ON(!key)) |
3201 | return; | |
fbb9ce95 IM |
3202 | /* |
3203 | * Sanity check, the lock-class key must be persistent: | |
3204 | */ | |
3205 | if (!static_obj(key)) { | |
3206 | printk("BUG: key %p not in .data!\n", key); | |
0119fee4 PZ |
3207 | /* |
3208 | * What it says above ^^^^^, I suggest you read it. | |
3209 | */ | |
fbb9ce95 IM |
3210 | DEBUG_LOCKS_WARN_ON(1); |
3211 | return; | |
3212 | } | |
fbb9ce95 | 3213 | lock->key = key; |
c8a25005 PZ |
3214 | |
3215 | if (unlikely(!debug_locks)) | |
3216 | return; | |
3217 | ||
35a9393c PZ |
3218 | if (subclass) { |
3219 | unsigned long flags; | |
3220 | ||
3221 | if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion)) | |
3222 | return; | |
3223 | ||
3224 | raw_local_irq_save(flags); | |
3225 | current->lockdep_recursion = 1; | |
4dfbb9d8 | 3226 | register_lock_class(lock, subclass, 1); |
35a9393c PZ |
3227 | current->lockdep_recursion = 0; |
3228 | raw_local_irq_restore(flags); | |
3229 | } | |
fbb9ce95 | 3230 | } |
b09be676 BP |
3231 | |
3232 | void lockdep_init_map(struct lockdep_map *lock, const char *name, | |
3233 | struct lock_class_key *key, int subclass) | |
3234 | { | |
b09be676 BP |
3235 | __lockdep_init_map(lock, name, key, subclass); |
3236 | } | |
fbb9ce95 IM |
3237 | EXPORT_SYMBOL_GPL(lockdep_init_map); |
3238 | ||
1704f47b | 3239 | struct lock_class_key __lockdep_no_validate__; |
ea6749c7 | 3240 | EXPORT_SYMBOL_GPL(__lockdep_no_validate__); |
1704f47b | 3241 | |
d0945950 ML |
3242 | static int |
3243 | print_lock_nested_lock_not_held(struct task_struct *curr, | |
3244 | struct held_lock *hlock, | |
3245 | unsigned long ip) | |
3246 | { | |
3247 | if (!debug_locks_off()) | |
3248 | return 0; | |
3249 | if (debug_locks_silent) | |
3250 | return 0; | |
3251 | ||
681fbec8 | 3252 | pr_warn("\n"); |
a5dd63ef PM |
3253 | pr_warn("==================================\n"); |
3254 | pr_warn("WARNING: Nested lock was not taken\n"); | |
d0945950 | 3255 | print_kernel_ident(); |
a5dd63ef | 3256 | pr_warn("----------------------------------\n"); |
d0945950 | 3257 | |
681fbec8 | 3258 | pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr)); |
d0945950 ML |
3259 | print_lock(hlock); |
3260 | ||
681fbec8 PM |
3261 | pr_warn("\nbut this task is not holding:\n"); |
3262 | pr_warn("%s\n", hlock->nest_lock->name); | |
d0945950 | 3263 | |
681fbec8 | 3264 | pr_warn("\nstack backtrace:\n"); |
d0945950 ML |
3265 | dump_stack(); |
3266 | ||
681fbec8 | 3267 | pr_warn("\nother info that might help us debug this:\n"); |
d0945950 ML |
3268 | lockdep_print_held_locks(curr); |
3269 | ||
681fbec8 | 3270 | pr_warn("\nstack backtrace:\n"); |
d0945950 ML |
3271 | dump_stack(); |
3272 | ||
3273 | return 0; | |
3274 | } | |
3275 | ||
f8319483 | 3276 | static int __lock_is_held(struct lockdep_map *lock, int read); |
d0945950 | 3277 | |
fbb9ce95 IM |
3278 | /* |
3279 | * This gets called for every mutex_lock*()/spin_lock*() operation. | |
3280 | * We maintain the dependency maps and validate the locking attempt: | |
3281 | */ | |
3282 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
3283 | int trylock, int read, int check, int hardirqs_off, | |
bb97a91e | 3284 | struct lockdep_map *nest_lock, unsigned long ip, |
21199f27 | 3285 | int references, int pin_count) |
fbb9ce95 IM |
3286 | { |
3287 | struct task_struct *curr = current; | |
d6d897ce | 3288 | struct lock_class *class = NULL; |
fbb9ce95 | 3289 | struct held_lock *hlock; |
5f18ab5c | 3290 | unsigned int depth; |
fbb9ce95 | 3291 | int chain_head = 0; |
bb97a91e | 3292 | int class_idx; |
fbb9ce95 IM |
3293 | u64 chain_key; |
3294 | ||
3295 | if (unlikely(!debug_locks)) | |
3296 | return 0; | |
3297 | ||
0119fee4 PZ |
3298 | /* |
3299 | * Lockdep should run with IRQs disabled, otherwise we could | |
3300 | * get an interrupt which would want to take locks, which would | |
3301 | * end up in lockdep and have you got a head-ache already? | |
3302 | */ | |
fbb9ce95 IM |
3303 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
3304 | return 0; | |
3305 | ||
fb9edbe9 ON |
3306 | if (!prove_locking || lock->key == &__lockdep_no_validate__) |
3307 | check = 0; | |
1704f47b | 3308 | |
62016250 HM |
3309 | if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
3310 | class = lock->class_cache[subclass]; | |
d6d897ce | 3311 | /* |
62016250 | 3312 | * Not cached? |
d6d897ce | 3313 | */ |
fbb9ce95 | 3314 | if (unlikely(!class)) { |
4dfbb9d8 | 3315 | class = register_lock_class(lock, subclass, 0); |
fbb9ce95 IM |
3316 | if (!class) |
3317 | return 0; | |
3318 | } | |
bd6d29c2 | 3319 | atomic_inc((atomic_t *)&class->ops); |
fbb9ce95 IM |
3320 | if (very_verbose(class)) { |
3321 | printk("\nacquire class [%p] %s", class->key, class->name); | |
3322 | if (class->name_version > 1) | |
f943fe0f DV |
3323 | printk(KERN_CONT "#%d", class->name_version); |
3324 | printk(KERN_CONT "\n"); | |
fbb9ce95 IM |
3325 | dump_stack(); |
3326 | } | |
3327 | ||
3328 | /* | |
3329 | * Add the lock to the list of currently held locks. | |
3330 | * (we dont increase the depth just yet, up until the | |
3331 | * dependency checks are done) | |
3332 | */ | |
3333 | depth = curr->lockdep_depth; | |
0119fee4 PZ |
3334 | /* |
3335 | * Ran out of static storage for our per-task lock stack again have we? | |
3336 | */ | |
fbb9ce95 IM |
3337 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) |
3338 | return 0; | |
3339 | ||
bb97a91e PZ |
3340 | class_idx = class - lock_classes + 1; |
3341 | ||
e966eaee | 3342 | if (depth) { |
bb97a91e PZ |
3343 | hlock = curr->held_locks + depth - 1; |
3344 | if (hlock->class_idx == class_idx && nest_lock) { | |
7fb4a2ce PZ |
3345 | if (hlock->references) { |
3346 | /* | |
3347 | * Check: unsigned int references:12, overflow. | |
3348 | */ | |
3349 | if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1)) | |
3350 | return 0; | |
3351 | ||
bb97a91e | 3352 | hlock->references++; |
7fb4a2ce | 3353 | } else { |
bb97a91e | 3354 | hlock->references = 2; |
7fb4a2ce | 3355 | } |
bb97a91e PZ |
3356 | |
3357 | return 1; | |
3358 | } | |
3359 | } | |
3360 | ||
fbb9ce95 | 3361 | hlock = curr->held_locks + depth; |
0119fee4 PZ |
3362 | /* |
3363 | * Plain impossible, we just registered it and checked it weren't no | |
3364 | * NULL like.. I bet this mushroom I ate was good! | |
3365 | */ | |
f82b217e DJ |
3366 | if (DEBUG_LOCKS_WARN_ON(!class)) |
3367 | return 0; | |
bb97a91e | 3368 | hlock->class_idx = class_idx; |
fbb9ce95 IM |
3369 | hlock->acquire_ip = ip; |
3370 | hlock->instance = lock; | |
7531e2f3 | 3371 | hlock->nest_lock = nest_lock; |
c2469756 | 3372 | hlock->irq_context = task_irq_context(curr); |
fbb9ce95 IM |
3373 | hlock->trylock = trylock; |
3374 | hlock->read = read; | |
3375 | hlock->check = check; | |
6951b12a | 3376 | hlock->hardirqs_off = !!hardirqs_off; |
bb97a91e | 3377 | hlock->references = references; |
f20786ff PZ |
3378 | #ifdef CONFIG_LOCK_STAT |
3379 | hlock->waittime_stamp = 0; | |
3365e779 | 3380 | hlock->holdtime_stamp = lockstat_clock(); |
f20786ff | 3381 | #endif |
21199f27 | 3382 | hlock->pin_count = pin_count; |
fbb9ce95 | 3383 | |
fb9edbe9 | 3384 | if (check && !mark_irqflags(curr, hlock)) |
8e18257d PZ |
3385 | return 0; |
3386 | ||
fbb9ce95 | 3387 | /* mark it as used: */ |
4ff773bb | 3388 | if (!mark_lock(curr, hlock, LOCK_USED)) |
fbb9ce95 | 3389 | return 0; |
8e18257d | 3390 | |
fbb9ce95 | 3391 | /* |
17aacfb9 | 3392 | * Calculate the chain hash: it's the combined hash of all the |
fbb9ce95 IM |
3393 | * lock keys along the dependency chain. We save the hash value |
3394 | * at every step so that we can get the current hash easily | |
3395 | * after unlock. The chain hash is then used to cache dependency | |
3396 | * results. | |
3397 | * | |
3398 | * The 'key ID' is what is the most compact key value to drive | |
3399 | * the hash, not class->key. | |
3400 | */ | |
0119fee4 PZ |
3401 | /* |
3402 | * Whoops, we did it again.. ran straight out of our static allocation. | |
3403 | */ | |
5f18ab5c | 3404 | if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS)) |
fbb9ce95 IM |
3405 | return 0; |
3406 | ||
3407 | chain_key = curr->curr_chain_key; | |
3408 | if (!depth) { | |
0119fee4 PZ |
3409 | /* |
3410 | * How can we have a chain hash when we ain't got no keys?! | |
3411 | */ | |
fbb9ce95 IM |
3412 | if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) |
3413 | return 0; | |
3414 | chain_head = 1; | |
3415 | } | |
3416 | ||
3417 | hlock->prev_chain_key = chain_key; | |
8e18257d PZ |
3418 | if (separate_irq_context(curr, hlock)) { |
3419 | chain_key = 0; | |
3420 | chain_head = 1; | |
fbb9ce95 | 3421 | } |
5f18ab5c | 3422 | chain_key = iterate_chain_key(chain_key, class_idx); |
fbb9ce95 | 3423 | |
f8319483 | 3424 | if (nest_lock && !__lock_is_held(nest_lock, -1)) |
d0945950 ML |
3425 | return print_lock_nested_lock_not_held(curr, hlock, ip); |
3426 | ||
3aa416b0 | 3427 | if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) |
8e18257d | 3428 | return 0; |
381a2292 | 3429 | |
3aa416b0 | 3430 | curr->curr_chain_key = chain_key; |
fbb9ce95 IM |
3431 | curr->lockdep_depth++; |
3432 | check_chain_key(curr); | |
60e114d1 JP |
3433 | #ifdef CONFIG_DEBUG_LOCKDEP |
3434 | if (unlikely(!debug_locks)) | |
3435 | return 0; | |
3436 | #endif | |
fbb9ce95 IM |
3437 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { |
3438 | debug_locks_off(); | |
2c522836 DJ |
3439 | print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!"); |
3440 | printk(KERN_DEBUG "depth: %i max: %lu!\n", | |
c0540606 | 3441 | curr->lockdep_depth, MAX_LOCK_DEPTH); |
c0540606 BG |
3442 | |
3443 | lockdep_print_held_locks(current); | |
3444 | debug_show_all_locks(); | |
eedeeabd | 3445 | dump_stack(); |
c0540606 | 3446 | |
fbb9ce95 IM |
3447 | return 0; |
3448 | } | |
381a2292 | 3449 | |
fbb9ce95 IM |
3450 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) |
3451 | max_lockdep_depth = curr->lockdep_depth; | |
3452 | ||
3453 | return 1; | |
3454 | } | |
3455 | ||
3456 | static int | |
f86f7554 | 3457 | print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock, |
fbb9ce95 IM |
3458 | unsigned long ip) |
3459 | { | |
3460 | if (!debug_locks_off()) | |
3461 | return 0; | |
3462 | if (debug_locks_silent) | |
3463 | return 0; | |
3464 | ||
681fbec8 | 3465 | pr_warn("\n"); |
a5dd63ef PM |
3466 | pr_warn("=====================================\n"); |
3467 | pr_warn("WARNING: bad unlock balance detected!\n"); | |
fbdc4b9a | 3468 | print_kernel_ident(); |
a5dd63ef | 3469 | pr_warn("-------------------------------------\n"); |
681fbec8 | 3470 | pr_warn("%s/%d is trying to release lock (", |
ba25f9dc | 3471 | curr->comm, task_pid_nr(curr)); |
fbb9ce95 | 3472 | print_lockdep_cache(lock); |
681fbec8 | 3473 | pr_cont(") at:\n"); |
fbb9ce95 | 3474 | print_ip_sym(ip); |
681fbec8 PM |
3475 | pr_warn("but there are no more locks to release!\n"); |
3476 | pr_warn("\nother info that might help us debug this:\n"); | |
fbb9ce95 IM |
3477 | lockdep_print_held_locks(curr); |
3478 | ||
681fbec8 | 3479 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 IM |
3480 | dump_stack(); |
3481 | ||
3482 | return 0; | |
3483 | } | |
3484 | ||
bb97a91e PZ |
3485 | static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) |
3486 | { | |
3487 | if (hlock->instance == lock) | |
3488 | return 1; | |
3489 | ||
3490 | if (hlock->references) { | |
62016250 | 3491 | struct lock_class *class = lock->class_cache[0]; |
bb97a91e PZ |
3492 | |
3493 | if (!class) | |
3494 | class = look_up_lock_class(lock, 0); | |
3495 | ||
80e0401e PZ |
3496 | /* |
3497 | * If look_up_lock_class() failed to find a class, we're trying | |
3498 | * to test if we hold a lock that has never yet been acquired. | |
3499 | * Clearly if the lock hasn't been acquired _ever_, we're not | |
3500 | * holding it either, so report failure. | |
3501 | */ | |
383776fa | 3502 | if (IS_ERR_OR_NULL(class)) |
bb97a91e PZ |
3503 | return 0; |
3504 | ||
0119fee4 PZ |
3505 | /* |
3506 | * References, but not a lock we're actually ref-counting? | |
3507 | * State got messed up, follow the sites that change ->references | |
3508 | * and try to make sense of it. | |
3509 | */ | |
bb97a91e PZ |
3510 | if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) |
3511 | return 0; | |
3512 | ||
3513 | if (hlock->class_idx == class - lock_classes + 1) | |
3514 | return 1; | |
3515 | } | |
3516 | ||
3517 | return 0; | |
3518 | } | |
3519 | ||
41c2c5b8 O |
3520 | /* @depth must not be zero */ |
3521 | static struct held_lock *find_held_lock(struct task_struct *curr, | |
3522 | struct lockdep_map *lock, | |
3523 | unsigned int depth, int *idx) | |
3524 | { | |
3525 | struct held_lock *ret, *hlock, *prev_hlock; | |
3526 | int i; | |
3527 | ||
3528 | i = depth - 1; | |
3529 | hlock = curr->held_locks + i; | |
3530 | ret = hlock; | |
3531 | if (match_held_lock(hlock, lock)) | |
3532 | goto out; | |
3533 | ||
3534 | ret = NULL; | |
3535 | for (i--, prev_hlock = hlock--; | |
3536 | i >= 0; | |
3537 | i--, prev_hlock = hlock--) { | |
3538 | /* | |
3539 | * We must not cross into another context: | |
3540 | */ | |
3541 | if (prev_hlock->irq_context != hlock->irq_context) { | |
3542 | ret = NULL; | |
3543 | break; | |
3544 | } | |
3545 | if (match_held_lock(hlock, lock)) { | |
3546 | ret = hlock; | |
3547 | break; | |
3548 | } | |
3549 | } | |
3550 | ||
3551 | out: | |
3552 | *idx = i; | |
3553 | return ret; | |
3554 | } | |
3555 | ||
e969970b O |
3556 | static int reacquire_held_locks(struct task_struct *curr, unsigned int depth, |
3557 | int idx) | |
3558 | { | |
3559 | struct held_lock *hlock; | |
3560 | ||
3561 | for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) { | |
3562 | if (!__lock_acquire(hlock->instance, | |
3563 | hlock_class(hlock)->subclass, | |
3564 | hlock->trylock, | |
3565 | hlock->read, hlock->check, | |
3566 | hlock->hardirqs_off, | |
3567 | hlock->nest_lock, hlock->acquire_ip, | |
3568 | hlock->references, hlock->pin_count)) | |
3569 | return 1; | |
3570 | } | |
3571 | return 0; | |
3572 | } | |
3573 | ||
64aa348e | 3574 | static int |
00ef9f73 PZ |
3575 | __lock_set_class(struct lockdep_map *lock, const char *name, |
3576 | struct lock_class_key *key, unsigned int subclass, | |
3577 | unsigned long ip) | |
64aa348e PZ |
3578 | { |
3579 | struct task_struct *curr = current; | |
41c2c5b8 | 3580 | struct held_lock *hlock; |
64aa348e PZ |
3581 | struct lock_class *class; |
3582 | unsigned int depth; | |
3583 | int i; | |
3584 | ||
3585 | depth = curr->lockdep_depth; | |
0119fee4 PZ |
3586 | /* |
3587 | * This function is about (re)setting the class of a held lock, | |
3588 | * yet we're not actually holding any locks. Naughty user! | |
3589 | */ | |
64aa348e PZ |
3590 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
3591 | return 0; | |
3592 | ||
41c2c5b8 O |
3593 | hlock = find_held_lock(curr, lock, depth, &i); |
3594 | if (!hlock) | |
3595 | return print_unlock_imbalance_bug(curr, lock, ip); | |
64aa348e | 3596 | |
00ef9f73 | 3597 | lockdep_init_map(lock, name, key, 0); |
64aa348e | 3598 | class = register_lock_class(lock, subclass, 0); |
f82b217e | 3599 | hlock->class_idx = class - lock_classes + 1; |
64aa348e PZ |
3600 | |
3601 | curr->lockdep_depth = i; | |
3602 | curr->curr_chain_key = hlock->prev_chain_key; | |
3603 | ||
e969970b O |
3604 | if (reacquire_held_locks(curr, depth, i)) |
3605 | return 0; | |
64aa348e | 3606 | |
0119fee4 PZ |
3607 | /* |
3608 | * I took it apart and put it back together again, except now I have | |
3609 | * these 'spare' parts.. where shall I put them. | |
3610 | */ | |
64aa348e PZ |
3611 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) |
3612 | return 0; | |
3613 | return 1; | |
3614 | } | |
3615 | ||
6419c4af O |
3616 | static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) |
3617 | { | |
3618 | struct task_struct *curr = current; | |
3619 | struct held_lock *hlock; | |
3620 | unsigned int depth; | |
3621 | int i; | |
3622 | ||
3623 | depth = curr->lockdep_depth; | |
3624 | /* | |
3625 | * This function is about (re)setting the class of a held lock, | |
3626 | * yet we're not actually holding any locks. Naughty user! | |
3627 | */ | |
3628 | if (DEBUG_LOCKS_WARN_ON(!depth)) | |
3629 | return 0; | |
3630 | ||
3631 | hlock = find_held_lock(curr, lock, depth, &i); | |
3632 | if (!hlock) | |
3633 | return print_unlock_imbalance_bug(curr, lock, ip); | |
3634 | ||
3635 | curr->lockdep_depth = i; | |
3636 | curr->curr_chain_key = hlock->prev_chain_key; | |
3637 | ||
3638 | WARN(hlock->read, "downgrading a read lock"); | |
3639 | hlock->read = 1; | |
3640 | hlock->acquire_ip = ip; | |
3641 | ||
3642 | if (reacquire_held_locks(curr, depth, i)) | |
3643 | return 0; | |
3644 | ||
3645 | /* | |
3646 | * I took it apart and put it back together again, except now I have | |
3647 | * these 'spare' parts.. where shall I put them. | |
3648 | */ | |
3649 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) | |
3650 | return 0; | |
3651 | return 1; | |
3652 | } | |
3653 | ||
fbb9ce95 | 3654 | /* |
e0f56fd7 PZ |
3655 | * Remove the lock to the list of currently held locks - this gets |
3656 | * called on mutex_unlock()/spin_unlock*() (or on a failed | |
3657 | * mutex_lock_interruptible()). | |
3658 | * | |
3659 | * @nested is an hysterical artifact, needs a tree wide cleanup. | |
fbb9ce95 IM |
3660 | */ |
3661 | static int | |
e0f56fd7 | 3662 | __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) |
fbb9ce95 | 3663 | { |
e0f56fd7 | 3664 | struct task_struct *curr = current; |
41c2c5b8 | 3665 | struct held_lock *hlock; |
fbb9ce95 | 3666 | unsigned int depth; |
e966eaee | 3667 | int i; |
fbb9ce95 | 3668 | |
e0f56fd7 PZ |
3669 | if (unlikely(!debug_locks)) |
3670 | return 0; | |
3671 | ||
fbb9ce95 | 3672 | depth = curr->lockdep_depth; |
0119fee4 PZ |
3673 | /* |
3674 | * So we're all set to release this lock.. wait what lock? We don't | |
3675 | * own any locks, you've been drinking again? | |
3676 | */ | |
e0f56fd7 PZ |
3677 | if (DEBUG_LOCKS_WARN_ON(depth <= 0)) |
3678 | return print_unlock_imbalance_bug(curr, lock, ip); | |
fbb9ce95 | 3679 | |
e0f56fd7 PZ |
3680 | /* |
3681 | * Check whether the lock exists in the current stack | |
3682 | * of held locks: | |
3683 | */ | |
41c2c5b8 O |
3684 | hlock = find_held_lock(curr, lock, depth, &i); |
3685 | if (!hlock) | |
3686 | return print_unlock_imbalance_bug(curr, lock, ip); | |
fbb9ce95 | 3687 | |
bb97a91e PZ |
3688 | if (hlock->instance == lock) |
3689 | lock_release_holdtime(hlock); | |
3690 | ||
a24fc60d PZ |
3691 | WARN(hlock->pin_count, "releasing a pinned lock\n"); |
3692 | ||
bb97a91e PZ |
3693 | if (hlock->references) { |
3694 | hlock->references--; | |
3695 | if (hlock->references) { | |
3696 | /* | |
3697 | * We had, and after removing one, still have | |
3698 | * references, the current lock stack is still | |
3699 | * valid. We're done! | |
3700 | */ | |
3701 | return 1; | |
3702 | } | |
3703 | } | |
f20786ff | 3704 | |
fbb9ce95 IM |
3705 | /* |
3706 | * We have the right lock to unlock, 'hlock' points to it. | |
3707 | * Now we remove it from the stack, and add back the other | |
3708 | * entries (if any), recalculating the hash along the way: | |
3709 | */ | |
bb97a91e | 3710 | |
fbb9ce95 IM |
3711 | curr->lockdep_depth = i; |
3712 | curr->curr_chain_key = hlock->prev_chain_key; | |
3713 | ||
e969970b O |
3714 | if (reacquire_held_locks(curr, depth, i + 1)) |
3715 | return 0; | |
fbb9ce95 | 3716 | |
0119fee4 PZ |
3717 | /* |
3718 | * We had N bottles of beer on the wall, we drank one, but now | |
3719 | * there's not N-1 bottles of beer left on the wall... | |
3720 | */ | |
fbb9ce95 IM |
3721 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) |
3722 | return 0; | |
f20786ff | 3723 | |
fbb9ce95 IM |
3724 | return 1; |
3725 | } | |
3726 | ||
f8319483 | 3727 | static int __lock_is_held(struct lockdep_map *lock, int read) |
fbb9ce95 | 3728 | { |
f607c668 PZ |
3729 | struct task_struct *curr = current; |
3730 | int i; | |
fbb9ce95 | 3731 | |
f607c668 | 3732 | for (i = 0; i < curr->lockdep_depth; i++) { |
bb97a91e | 3733 | struct held_lock *hlock = curr->held_locks + i; |
fbb9ce95 | 3734 | |
f8319483 PZ |
3735 | if (match_held_lock(hlock, lock)) { |
3736 | if (read == -1 || hlock->read == read) | |
3737 | return 1; | |
3738 | ||
3739 | return 0; | |
3740 | } | |
f607c668 | 3741 | } |
f20786ff | 3742 | |
f607c668 | 3743 | return 0; |
fbb9ce95 IM |
3744 | } |
3745 | ||
e7904a28 PZ |
3746 | static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) |
3747 | { | |
3748 | struct pin_cookie cookie = NIL_COOKIE; | |
3749 | struct task_struct *curr = current; | |
3750 | int i; | |
3751 | ||
3752 | if (unlikely(!debug_locks)) | |
3753 | return cookie; | |
3754 | ||
3755 | for (i = 0; i < curr->lockdep_depth; i++) { | |
3756 | struct held_lock *hlock = curr->held_locks + i; | |
3757 | ||
3758 | if (match_held_lock(hlock, lock)) { | |
3759 | /* | |
3760 | * Grab 16bits of randomness; this is sufficient to not | |
3761 | * be guessable and still allows some pin nesting in | |
3762 | * our u32 pin_count. | |
3763 | */ | |
3764 | cookie.val = 1 + (prandom_u32() >> 16); | |
3765 | hlock->pin_count += cookie.val; | |
3766 | return cookie; | |
3767 | } | |
3768 | } | |
3769 | ||
3770 | WARN(1, "pinning an unheld lock\n"); | |
3771 | return cookie; | |
3772 | } | |
3773 | ||
3774 | static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) | |
fbb9ce95 IM |
3775 | { |
3776 | struct task_struct *curr = current; | |
a24fc60d | 3777 | int i; |
fbb9ce95 | 3778 | |
a24fc60d | 3779 | if (unlikely(!debug_locks)) |
fbb9ce95 IM |
3780 | return; |
3781 | ||
a24fc60d PZ |
3782 | for (i = 0; i < curr->lockdep_depth; i++) { |
3783 | struct held_lock *hlock = curr->held_locks + i; | |
3784 | ||
3785 | if (match_held_lock(hlock, lock)) { | |
e7904a28 | 3786 | hlock->pin_count += cookie.val; |
fbb9ce95 | 3787 | return; |
a24fc60d | 3788 | } |
fbb9ce95 IM |
3789 | } |
3790 | ||
a24fc60d | 3791 | WARN(1, "pinning an unheld lock\n"); |
fbb9ce95 IM |
3792 | } |
3793 | ||
e7904a28 | 3794 | static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) |
f607c668 PZ |
3795 | { |
3796 | struct task_struct *curr = current; | |
3797 | int i; | |
3798 | ||
a24fc60d PZ |
3799 | if (unlikely(!debug_locks)) |
3800 | return; | |
3801 | ||
f607c668 | 3802 | for (i = 0; i < curr->lockdep_depth; i++) { |
bb97a91e PZ |
3803 | struct held_lock *hlock = curr->held_locks + i; |
3804 | ||
a24fc60d PZ |
3805 | if (match_held_lock(hlock, lock)) { |
3806 | if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n")) | |
3807 | return; | |
3808 | ||
e7904a28 PZ |
3809 | hlock->pin_count -= cookie.val; |
3810 | ||
3811 | if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n")) | |
3812 | hlock->pin_count = 0; | |
3813 | ||
a24fc60d PZ |
3814 | return; |
3815 | } | |
f607c668 PZ |
3816 | } |
3817 | ||
a24fc60d | 3818 | WARN(1, "unpinning an unheld lock\n"); |
f607c668 PZ |
3819 | } |
3820 | ||
fbb9ce95 IM |
3821 | /* |
3822 | * Check whether we follow the irq-flags state precisely: | |
3823 | */ | |
1d09daa5 | 3824 | static void check_flags(unsigned long flags) |
fbb9ce95 | 3825 | { |
992860e9 IM |
3826 | #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \ |
3827 | defined(CONFIG_TRACE_IRQFLAGS) | |
fbb9ce95 IM |
3828 | if (!debug_locks) |
3829 | return; | |
3830 | ||
5f9fa8a6 IM |
3831 | if (irqs_disabled_flags(flags)) { |
3832 | if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { | |
3833 | printk("possible reason: unannotated irqs-off.\n"); | |
3834 | } | |
3835 | } else { | |
3836 | if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { | |
3837 | printk("possible reason: unannotated irqs-on.\n"); | |
3838 | } | |
3839 | } | |
fbb9ce95 IM |
3840 | |
3841 | /* | |
3842 | * We dont accurately track softirq state in e.g. | |
3843 | * hardirq contexts (such as on 4KSTACKS), so only | |
3844 | * check if not in hardirq contexts: | |
3845 | */ | |
3846 | if (!hardirq_count()) { | |
0119fee4 PZ |
3847 | if (softirq_count()) { |
3848 | /* like the above, but with softirqs */ | |
fbb9ce95 | 3849 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); |
0119fee4 PZ |
3850 | } else { |
3851 | /* lick the above, does it taste good? */ | |
fbb9ce95 | 3852 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); |
0119fee4 | 3853 | } |
fbb9ce95 IM |
3854 | } |
3855 | ||
3856 | if (!debug_locks) | |
3857 | print_irqtrace_events(current); | |
3858 | #endif | |
3859 | } | |
3860 | ||
00ef9f73 PZ |
3861 | void lock_set_class(struct lockdep_map *lock, const char *name, |
3862 | struct lock_class_key *key, unsigned int subclass, | |
3863 | unsigned long ip) | |
64aa348e PZ |
3864 | { |
3865 | unsigned long flags; | |
3866 | ||
3867 | if (unlikely(current->lockdep_recursion)) | |
3868 | return; | |
3869 | ||
3870 | raw_local_irq_save(flags); | |
3871 | current->lockdep_recursion = 1; | |
3872 | check_flags(flags); | |
00ef9f73 | 3873 | if (__lock_set_class(lock, name, key, subclass, ip)) |
64aa348e PZ |
3874 | check_chain_key(current); |
3875 | current->lockdep_recursion = 0; | |
3876 | raw_local_irq_restore(flags); | |
3877 | } | |
00ef9f73 | 3878 | EXPORT_SYMBOL_GPL(lock_set_class); |
64aa348e | 3879 | |
6419c4af O |
3880 | void lock_downgrade(struct lockdep_map *lock, unsigned long ip) |
3881 | { | |
3882 | unsigned long flags; | |
3883 | ||
3884 | if (unlikely(current->lockdep_recursion)) | |
3885 | return; | |
3886 | ||
3887 | raw_local_irq_save(flags); | |
3888 | current->lockdep_recursion = 1; | |
3889 | check_flags(flags); | |
3890 | if (__lock_downgrade(lock, ip)) | |
3891 | check_chain_key(current); | |
3892 | current->lockdep_recursion = 0; | |
3893 | raw_local_irq_restore(flags); | |
3894 | } | |
3895 | EXPORT_SYMBOL_GPL(lock_downgrade); | |
3896 | ||
fbb9ce95 IM |
3897 | /* |
3898 | * We are not always called with irqs disabled - do that here, | |
3899 | * and also avoid lockdep recursion: | |
3900 | */ | |
1d09daa5 | 3901 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
7531e2f3 PZ |
3902 | int trylock, int read, int check, |
3903 | struct lockdep_map *nest_lock, unsigned long ip) | |
fbb9ce95 IM |
3904 | { |
3905 | unsigned long flags; | |
3906 | ||
3907 | if (unlikely(current->lockdep_recursion)) | |
3908 | return; | |
3909 | ||
3910 | raw_local_irq_save(flags); | |
3911 | check_flags(flags); | |
3912 | ||
3913 | current->lockdep_recursion = 1; | |
db2c4c77 | 3914 | trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); |
fbb9ce95 | 3915 | __lock_acquire(lock, subclass, trylock, read, check, |
21199f27 | 3916 | irqs_disabled_flags(flags), nest_lock, ip, 0, 0); |
fbb9ce95 IM |
3917 | current->lockdep_recursion = 0; |
3918 | raw_local_irq_restore(flags); | |
3919 | } | |
fbb9ce95 IM |
3920 | EXPORT_SYMBOL_GPL(lock_acquire); |
3921 | ||
1d09daa5 | 3922 | void lock_release(struct lockdep_map *lock, int nested, |
0764d23c | 3923 | unsigned long ip) |
fbb9ce95 IM |
3924 | { |
3925 | unsigned long flags; | |
3926 | ||
3927 | if (unlikely(current->lockdep_recursion)) | |
3928 | return; | |
3929 | ||
3930 | raw_local_irq_save(flags); | |
3931 | check_flags(flags); | |
3932 | current->lockdep_recursion = 1; | |
93135439 | 3933 | trace_lock_release(lock, ip); |
e0f56fd7 PZ |
3934 | if (__lock_release(lock, nested, ip)) |
3935 | check_chain_key(current); | |
fbb9ce95 IM |
3936 | current->lockdep_recursion = 0; |
3937 | raw_local_irq_restore(flags); | |
3938 | } | |
fbb9ce95 IM |
3939 | EXPORT_SYMBOL_GPL(lock_release); |
3940 | ||
f8319483 | 3941 | int lock_is_held_type(struct lockdep_map *lock, int read) |
f607c668 PZ |
3942 | { |
3943 | unsigned long flags; | |
3944 | int ret = 0; | |
3945 | ||
3946 | if (unlikely(current->lockdep_recursion)) | |
f2513cde | 3947 | return 1; /* avoid false negative lockdep_assert_held() */ |
f607c668 PZ |
3948 | |
3949 | raw_local_irq_save(flags); | |
3950 | check_flags(flags); | |
3951 | ||
3952 | current->lockdep_recursion = 1; | |
f8319483 | 3953 | ret = __lock_is_held(lock, read); |
f607c668 PZ |
3954 | current->lockdep_recursion = 0; |
3955 | raw_local_irq_restore(flags); | |
3956 | ||
3957 | return ret; | |
3958 | } | |
f8319483 | 3959 | EXPORT_SYMBOL_GPL(lock_is_held_type); |
f607c668 | 3960 | |
e7904a28 | 3961 | struct pin_cookie lock_pin_lock(struct lockdep_map *lock) |
a24fc60d | 3962 | { |
e7904a28 | 3963 | struct pin_cookie cookie = NIL_COOKIE; |
a24fc60d PZ |
3964 | unsigned long flags; |
3965 | ||
3966 | if (unlikely(current->lockdep_recursion)) | |
e7904a28 | 3967 | return cookie; |
a24fc60d PZ |
3968 | |
3969 | raw_local_irq_save(flags); | |
3970 | check_flags(flags); | |
3971 | ||
3972 | current->lockdep_recursion = 1; | |
e7904a28 | 3973 | cookie = __lock_pin_lock(lock); |
a24fc60d PZ |
3974 | current->lockdep_recursion = 0; |
3975 | raw_local_irq_restore(flags); | |
e7904a28 PZ |
3976 | |
3977 | return cookie; | |
a24fc60d PZ |
3978 | } |
3979 | EXPORT_SYMBOL_GPL(lock_pin_lock); | |
3980 | ||
e7904a28 PZ |
3981 | void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) |
3982 | { | |
3983 | unsigned long flags; | |
3984 | ||
3985 | if (unlikely(current->lockdep_recursion)) | |
3986 | return; | |
3987 | ||
3988 | raw_local_irq_save(flags); | |
3989 | check_flags(flags); | |
3990 | ||
3991 | current->lockdep_recursion = 1; | |
3992 | __lock_repin_lock(lock, cookie); | |
3993 | current->lockdep_recursion = 0; | |
3994 | raw_local_irq_restore(flags); | |
3995 | } | |
3996 | EXPORT_SYMBOL_GPL(lock_repin_lock); | |
3997 | ||
3998 | void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) | |
a24fc60d PZ |
3999 | { |
4000 | unsigned long flags; | |
4001 | ||
4002 | if (unlikely(current->lockdep_recursion)) | |
4003 | return; | |
4004 | ||
4005 | raw_local_irq_save(flags); | |
4006 | check_flags(flags); | |
4007 | ||
4008 | current->lockdep_recursion = 1; | |
e7904a28 | 4009 | __lock_unpin_lock(lock, cookie); |
a24fc60d PZ |
4010 | current->lockdep_recursion = 0; |
4011 | raw_local_irq_restore(flags); | |
4012 | } | |
4013 | EXPORT_SYMBOL_GPL(lock_unpin_lock); | |
4014 | ||
f20786ff PZ |
4015 | #ifdef CONFIG_LOCK_STAT |
4016 | static int | |
4017 | print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, | |
4018 | unsigned long ip) | |
4019 | { | |
4020 | if (!debug_locks_off()) | |
4021 | return 0; | |
4022 | if (debug_locks_silent) | |
4023 | return 0; | |
4024 | ||
681fbec8 | 4025 | pr_warn("\n"); |
a5dd63ef PM |
4026 | pr_warn("=================================\n"); |
4027 | pr_warn("WARNING: bad contention detected!\n"); | |
fbdc4b9a | 4028 | print_kernel_ident(); |
a5dd63ef | 4029 | pr_warn("---------------------------------\n"); |
681fbec8 | 4030 | pr_warn("%s/%d is trying to contend lock (", |
ba25f9dc | 4031 | curr->comm, task_pid_nr(curr)); |
f20786ff | 4032 | print_lockdep_cache(lock); |
681fbec8 | 4033 | pr_cont(") at:\n"); |
f20786ff | 4034 | print_ip_sym(ip); |
681fbec8 PM |
4035 | pr_warn("but there are no locks held!\n"); |
4036 | pr_warn("\nother info that might help us debug this:\n"); | |
f20786ff PZ |
4037 | lockdep_print_held_locks(curr); |
4038 | ||
681fbec8 | 4039 | pr_warn("\nstack backtrace:\n"); |
f20786ff PZ |
4040 | dump_stack(); |
4041 | ||
4042 | return 0; | |
4043 | } | |
4044 | ||
4045 | static void | |
4046 | __lock_contended(struct lockdep_map *lock, unsigned long ip) | |
4047 | { | |
4048 | struct task_struct *curr = current; | |
41c2c5b8 | 4049 | struct held_lock *hlock; |
f20786ff PZ |
4050 | struct lock_class_stats *stats; |
4051 | unsigned int depth; | |
c7e78cff | 4052 | int i, contention_point, contending_point; |
f20786ff PZ |
4053 | |
4054 | depth = curr->lockdep_depth; | |
0119fee4 PZ |
4055 | /* |
4056 | * Whee, we contended on this lock, except it seems we're not | |
4057 | * actually trying to acquire anything much at all.. | |
4058 | */ | |
f20786ff PZ |
4059 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
4060 | return; | |
4061 | ||
41c2c5b8 O |
4062 | hlock = find_held_lock(curr, lock, depth, &i); |
4063 | if (!hlock) { | |
4064 | print_lock_contention_bug(curr, lock, ip); | |
4065 | return; | |
f20786ff | 4066 | } |
f20786ff | 4067 | |
bb97a91e PZ |
4068 | if (hlock->instance != lock) |
4069 | return; | |
4070 | ||
3365e779 | 4071 | hlock->waittime_stamp = lockstat_clock(); |
f20786ff | 4072 | |
c7e78cff PZ |
4073 | contention_point = lock_point(hlock_class(hlock)->contention_point, ip); |
4074 | contending_point = lock_point(hlock_class(hlock)->contending_point, | |
4075 | lock->ip); | |
f20786ff | 4076 | |
f82b217e | 4077 | stats = get_lock_stats(hlock_class(hlock)); |
c7e78cff PZ |
4078 | if (contention_point < LOCKSTAT_POINTS) |
4079 | stats->contention_point[contention_point]++; | |
4080 | if (contending_point < LOCKSTAT_POINTS) | |
4081 | stats->contending_point[contending_point]++; | |
96645678 PZ |
4082 | if (lock->cpu != smp_processor_id()) |
4083 | stats->bounces[bounce_contended + !!hlock->read]++; | |
f20786ff PZ |
4084 | put_lock_stats(stats); |
4085 | } | |
4086 | ||
4087 | static void | |
c7e78cff | 4088 | __lock_acquired(struct lockdep_map *lock, unsigned long ip) |
f20786ff PZ |
4089 | { |
4090 | struct task_struct *curr = current; | |
41c2c5b8 | 4091 | struct held_lock *hlock; |
f20786ff PZ |
4092 | struct lock_class_stats *stats; |
4093 | unsigned int depth; | |
3365e779 | 4094 | u64 now, waittime = 0; |
96645678 | 4095 | int i, cpu; |
f20786ff PZ |
4096 | |
4097 | depth = curr->lockdep_depth; | |
0119fee4 PZ |
4098 | /* |
4099 | * Yay, we acquired ownership of this lock we didn't try to | |
4100 | * acquire, how the heck did that happen? | |
4101 | */ | |
f20786ff PZ |
4102 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
4103 | return; | |
4104 | ||
41c2c5b8 O |
4105 | hlock = find_held_lock(curr, lock, depth, &i); |
4106 | if (!hlock) { | |
4107 | print_lock_contention_bug(curr, lock, _RET_IP_); | |
4108 | return; | |
f20786ff | 4109 | } |
f20786ff | 4110 | |
bb97a91e PZ |
4111 | if (hlock->instance != lock) |
4112 | return; | |
4113 | ||
96645678 PZ |
4114 | cpu = smp_processor_id(); |
4115 | if (hlock->waittime_stamp) { | |
3365e779 | 4116 | now = lockstat_clock(); |
96645678 PZ |
4117 | waittime = now - hlock->waittime_stamp; |
4118 | hlock->holdtime_stamp = now; | |
4119 | } | |
f20786ff | 4120 | |
883a2a31 | 4121 | trace_lock_acquired(lock, ip); |
2062501a | 4122 | |
f82b217e | 4123 | stats = get_lock_stats(hlock_class(hlock)); |
96645678 PZ |
4124 | if (waittime) { |
4125 | if (hlock->read) | |
4126 | lock_time_inc(&stats->read_waittime, waittime); | |
4127 | else | |
4128 | lock_time_inc(&stats->write_waittime, waittime); | |
4129 | } | |
4130 | if (lock->cpu != cpu) | |
4131 | stats->bounces[bounce_acquired + !!hlock->read]++; | |
f20786ff | 4132 | put_lock_stats(stats); |
96645678 PZ |
4133 | |
4134 | lock->cpu = cpu; | |
c7e78cff | 4135 | lock->ip = ip; |
f20786ff PZ |
4136 | } |
4137 | ||
4138 | void lock_contended(struct lockdep_map *lock, unsigned long ip) | |
4139 | { | |
4140 | unsigned long flags; | |
4141 | ||
4142 | if (unlikely(!lock_stat)) | |
4143 | return; | |
4144 | ||
4145 | if (unlikely(current->lockdep_recursion)) | |
4146 | return; | |
4147 | ||
4148 | raw_local_irq_save(flags); | |
4149 | check_flags(flags); | |
4150 | current->lockdep_recursion = 1; | |
db2c4c77 | 4151 | trace_lock_contended(lock, ip); |
f20786ff PZ |
4152 | __lock_contended(lock, ip); |
4153 | current->lockdep_recursion = 0; | |
4154 | raw_local_irq_restore(flags); | |
4155 | } | |
4156 | EXPORT_SYMBOL_GPL(lock_contended); | |
4157 | ||
c7e78cff | 4158 | void lock_acquired(struct lockdep_map *lock, unsigned long ip) |
f20786ff PZ |
4159 | { |
4160 | unsigned long flags; | |
4161 | ||
4162 | if (unlikely(!lock_stat)) | |
4163 | return; | |
4164 | ||
4165 | if (unlikely(current->lockdep_recursion)) | |
4166 | return; | |
4167 | ||
4168 | raw_local_irq_save(flags); | |
4169 | check_flags(flags); | |
4170 | current->lockdep_recursion = 1; | |
c7e78cff | 4171 | __lock_acquired(lock, ip); |
f20786ff PZ |
4172 | current->lockdep_recursion = 0; |
4173 | raw_local_irq_restore(flags); | |
4174 | } | |
4175 | EXPORT_SYMBOL_GPL(lock_acquired); | |
4176 | #endif | |
4177 | ||
fbb9ce95 IM |
4178 | /* |
4179 | * Used by the testsuite, sanitize the validator state | |
4180 | * after a simulated failure: | |
4181 | */ | |
4182 | ||
4183 | void lockdep_reset(void) | |
4184 | { | |
4185 | unsigned long flags; | |
23d95a03 | 4186 | int i; |
fbb9ce95 IM |
4187 | |
4188 | raw_local_irq_save(flags); | |
4189 | current->curr_chain_key = 0; | |
4190 | current->lockdep_depth = 0; | |
4191 | current->lockdep_recursion = 0; | |
4192 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); | |
4193 | nr_hardirq_chains = 0; | |
4194 | nr_softirq_chains = 0; | |
4195 | nr_process_chains = 0; | |
4196 | debug_locks = 1; | |
23d95a03 | 4197 | for (i = 0; i < CHAINHASH_SIZE; i++) |
a63f38cc | 4198 | INIT_HLIST_HEAD(chainhash_table + i); |
fbb9ce95 IM |
4199 | raw_local_irq_restore(flags); |
4200 | } | |
4201 | ||
4202 | static void zap_class(struct lock_class *class) | |
4203 | { | |
4204 | int i; | |
4205 | ||
4206 | /* | |
4207 | * Remove all dependencies this lock is | |
4208 | * involved in: | |
4209 | */ | |
4210 | for (i = 0; i < nr_list_entries; i++) { | |
4211 | if (list_entries[i].class == class) | |
4212 | list_del_rcu(&list_entries[i].entry); | |
4213 | } | |
4214 | /* | |
4215 | * Unhash the class and remove it from the all_lock_classes list: | |
4216 | */ | |
a63f38cc | 4217 | hlist_del_rcu(&class->hash_entry); |
fbb9ce95 IM |
4218 | list_del_rcu(&class->lock_entry); |
4219 | ||
cee34d88 PZ |
4220 | RCU_INIT_POINTER(class->key, NULL); |
4221 | RCU_INIT_POINTER(class->name, NULL); | |
fbb9ce95 IM |
4222 | } |
4223 | ||
fabe874a | 4224 | static inline int within(const void *addr, void *start, unsigned long size) |
fbb9ce95 IM |
4225 | { |
4226 | return addr >= start && addr < start + size; | |
4227 | } | |
4228 | ||
35a9393c PZ |
4229 | /* |
4230 | * Used in module.c to remove lock classes from memory that is going to be | |
4231 | * freed; and possibly re-used by other modules. | |
4232 | * | |
4233 | * We will have had one sync_sched() before getting here, so we're guaranteed | |
4234 | * nobody will look up these exact classes -- they're properly dead but still | |
4235 | * allocated. | |
4236 | */ | |
fbb9ce95 IM |
4237 | void lockdep_free_key_range(void *start, unsigned long size) |
4238 | { | |
35a9393c | 4239 | struct lock_class *class; |
a63f38cc | 4240 | struct hlist_head *head; |
fbb9ce95 IM |
4241 | unsigned long flags; |
4242 | int i; | |
5a26db5b | 4243 | int locked; |
fbb9ce95 IM |
4244 | |
4245 | raw_local_irq_save(flags); | |
5a26db5b | 4246 | locked = graph_lock(); |
fbb9ce95 IM |
4247 | |
4248 | /* | |
4249 | * Unhash all classes that were created by this module: | |
4250 | */ | |
4251 | for (i = 0; i < CLASSHASH_SIZE; i++) { | |
4252 | head = classhash_table + i; | |
a63f38cc | 4253 | hlist_for_each_entry_rcu(class, head, hash_entry) { |
fbb9ce95 IM |
4254 | if (within(class->key, start, size)) |
4255 | zap_class(class); | |
fabe874a AV |
4256 | else if (within(class->name, start, size)) |
4257 | zap_class(class); | |
4258 | } | |
fbb9ce95 IM |
4259 | } |
4260 | ||
5a26db5b NP |
4261 | if (locked) |
4262 | graph_unlock(); | |
fbb9ce95 | 4263 | raw_local_irq_restore(flags); |
35a9393c PZ |
4264 | |
4265 | /* | |
4266 | * Wait for any possible iterators from look_up_lock_class() to pass | |
4267 | * before continuing to free the memory they refer to. | |
4268 | * | |
4269 | * sync_sched() is sufficient because the read-side is IRQ disable. | |
4270 | */ | |
4271 | synchronize_sched(); | |
4272 | ||
4273 | /* | |
4274 | * XXX at this point we could return the resources to the pool; | |
4275 | * instead we leak them. We would need to change to bitmap allocators | |
4276 | * instead of the linear allocators we have now. | |
4277 | */ | |
fbb9ce95 IM |
4278 | } |
4279 | ||
4280 | void lockdep_reset_lock(struct lockdep_map *lock) | |
4281 | { | |
35a9393c | 4282 | struct lock_class *class; |
a63f38cc | 4283 | struct hlist_head *head; |
fbb9ce95 IM |
4284 | unsigned long flags; |
4285 | int i, j; | |
5a26db5b | 4286 | int locked; |
fbb9ce95 IM |
4287 | |
4288 | raw_local_irq_save(flags); | |
fbb9ce95 IM |
4289 | |
4290 | /* | |
d6d897ce IM |
4291 | * Remove all classes this lock might have: |
4292 | */ | |
4293 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { | |
4294 | /* | |
4295 | * If the class exists we look it up and zap it: | |
4296 | */ | |
4297 | class = look_up_lock_class(lock, j); | |
383776fa | 4298 | if (!IS_ERR_OR_NULL(class)) |
d6d897ce IM |
4299 | zap_class(class); |
4300 | } | |
4301 | /* | |
4302 | * Debug check: in the end all mapped classes should | |
4303 | * be gone. | |
fbb9ce95 | 4304 | */ |
5a26db5b | 4305 | locked = graph_lock(); |
fbb9ce95 IM |
4306 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
4307 | head = classhash_table + i; | |
a63f38cc | 4308 | hlist_for_each_entry_rcu(class, head, hash_entry) { |
62016250 HM |
4309 | int match = 0; |
4310 | ||
4311 | for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) | |
4312 | match |= class == lock->class_cache[j]; | |
4313 | ||
4314 | if (unlikely(match)) { | |
0119fee4 PZ |
4315 | if (debug_locks_off_graph_unlock()) { |
4316 | /* | |
4317 | * We all just reset everything, how did it match? | |
4318 | */ | |
74c383f1 | 4319 | WARN_ON(1); |
0119fee4 | 4320 | } |
d6d897ce | 4321 | goto out_restore; |
fbb9ce95 IM |
4322 | } |
4323 | } | |
4324 | } | |
5a26db5b NP |
4325 | if (locked) |
4326 | graph_unlock(); | |
d6d897ce IM |
4327 | |
4328 | out_restore: | |
fbb9ce95 IM |
4329 | raw_local_irq_restore(flags); |
4330 | } | |
4331 | ||
fbb9ce95 IM |
4332 | void __init lockdep_info(void) |
4333 | { | |
4334 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); | |
4335 | ||
b0788caf | 4336 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); |
fbb9ce95 IM |
4337 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); |
4338 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); | |
b0788caf | 4339 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); |
fbb9ce95 IM |
4340 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); |
4341 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); | |
4342 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); | |
4343 | ||
4344 | printk(" memory used by lock dependency info: %lu kB\n", | |
4345 | (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + | |
4346 | sizeof(struct list_head) * CLASSHASH_SIZE + | |
4347 | sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + | |
4348 | sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + | |
90629209 | 4349 | sizeof(struct list_head) * CHAINHASH_SIZE |
4dd861d6 | 4350 | #ifdef CONFIG_PROVE_LOCKING |
e351b660 | 4351 | + sizeof(struct circular_queue) |
4dd861d6 | 4352 | #endif |
90629209 | 4353 | ) / 1024 |
4dd861d6 | 4354 | ); |
fbb9ce95 IM |
4355 | |
4356 | printk(" per task-struct memory footprint: %lu bytes\n", | |
4357 | sizeof(struct held_lock) * MAX_LOCK_DEPTH); | |
fbb9ce95 IM |
4358 | } |
4359 | ||
fbb9ce95 IM |
4360 | static void |
4361 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, | |
55794a41 | 4362 | const void *mem_to, struct held_lock *hlock) |
fbb9ce95 IM |
4363 | { |
4364 | if (!debug_locks_off()) | |
4365 | return; | |
4366 | if (debug_locks_silent) | |
4367 | return; | |
4368 | ||
681fbec8 | 4369 | pr_warn("\n"); |
a5dd63ef PM |
4370 | pr_warn("=========================\n"); |
4371 | pr_warn("WARNING: held lock freed!\n"); | |
fbdc4b9a | 4372 | print_kernel_ident(); |
a5dd63ef | 4373 | pr_warn("-------------------------\n"); |
681fbec8 | 4374 | pr_warn("%s/%d is freeing memory %p-%p, with a lock still held there!\n", |
ba25f9dc | 4375 | curr->comm, task_pid_nr(curr), mem_from, mem_to-1); |
55794a41 | 4376 | print_lock(hlock); |
fbb9ce95 IM |
4377 | lockdep_print_held_locks(curr); |
4378 | ||
681fbec8 | 4379 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 IM |
4380 | dump_stack(); |
4381 | } | |
4382 | ||
54561783 ON |
4383 | static inline int not_in_range(const void* mem_from, unsigned long mem_len, |
4384 | const void* lock_from, unsigned long lock_len) | |
4385 | { | |
4386 | return lock_from + lock_len <= mem_from || | |
4387 | mem_from + mem_len <= lock_from; | |
4388 | } | |
4389 | ||
fbb9ce95 IM |
4390 | /* |
4391 | * Called when kernel memory is freed (or unmapped), or if a lock | |
4392 | * is destroyed or reinitialized - this code checks whether there is | |
4393 | * any held lock in the memory range of <from> to <to>: | |
4394 | */ | |
4395 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) | |
4396 | { | |
fbb9ce95 IM |
4397 | struct task_struct *curr = current; |
4398 | struct held_lock *hlock; | |
4399 | unsigned long flags; | |
4400 | int i; | |
4401 | ||
4402 | if (unlikely(!debug_locks)) | |
4403 | return; | |
4404 | ||
4405 | local_irq_save(flags); | |
4406 | for (i = 0; i < curr->lockdep_depth; i++) { | |
4407 | hlock = curr->held_locks + i; | |
4408 | ||
54561783 ON |
4409 | if (not_in_range(mem_from, mem_len, hlock->instance, |
4410 | sizeof(*hlock->instance))) | |
fbb9ce95 IM |
4411 | continue; |
4412 | ||
54561783 | 4413 | print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); |
fbb9ce95 IM |
4414 | break; |
4415 | } | |
4416 | local_irq_restore(flags); | |
4417 | } | |
ed07536e | 4418 | EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); |
fbb9ce95 | 4419 | |
1b1d2fb4 | 4420 | static void print_held_locks_bug(void) |
fbb9ce95 IM |
4421 | { |
4422 | if (!debug_locks_off()) | |
4423 | return; | |
4424 | if (debug_locks_silent) | |
4425 | return; | |
4426 | ||
681fbec8 | 4427 | pr_warn("\n"); |
a5dd63ef PM |
4428 | pr_warn("====================================\n"); |
4429 | pr_warn("WARNING: %s/%d still has locks held!\n", | |
1b1d2fb4 | 4430 | current->comm, task_pid_nr(current)); |
fbdc4b9a | 4431 | print_kernel_ident(); |
a5dd63ef | 4432 | pr_warn("------------------------------------\n"); |
1b1d2fb4 | 4433 | lockdep_print_held_locks(current); |
681fbec8 | 4434 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 IM |
4435 | dump_stack(); |
4436 | } | |
4437 | ||
1b1d2fb4 | 4438 | void debug_check_no_locks_held(void) |
fbb9ce95 | 4439 | { |
1b1d2fb4 CC |
4440 | if (unlikely(current->lockdep_depth > 0)) |
4441 | print_held_locks_bug(); | |
fbb9ce95 | 4442 | } |
1b1d2fb4 | 4443 | EXPORT_SYMBOL_GPL(debug_check_no_locks_held); |
fbb9ce95 | 4444 | |
8dce7a9a | 4445 | #ifdef __KERNEL__ |
fbb9ce95 IM |
4446 | void debug_show_all_locks(void) |
4447 | { | |
4448 | struct task_struct *g, *p; | |
4449 | int count = 10; | |
4450 | int unlock = 1; | |
4451 | ||
9c35dd7f | 4452 | if (unlikely(!debug_locks)) { |
681fbec8 | 4453 | pr_warn("INFO: lockdep is turned off.\n"); |
9c35dd7f JP |
4454 | return; |
4455 | } | |
681fbec8 | 4456 | pr_warn("\nShowing all locks held in the system:\n"); |
fbb9ce95 IM |
4457 | |
4458 | /* | |
4459 | * Here we try to get the tasklist_lock as hard as possible, | |
4460 | * if not successful after 2 seconds we ignore it (but keep | |
4461 | * trying). This is to enable a debug printout even if a | |
4462 | * tasklist_lock-holding task deadlocks or crashes. | |
4463 | */ | |
4464 | retry: | |
4465 | if (!read_trylock(&tasklist_lock)) { | |
4466 | if (count == 10) | |
681fbec8 | 4467 | pr_warn("hm, tasklist_lock locked, retrying... "); |
fbb9ce95 IM |
4468 | if (count) { |
4469 | count--; | |
681fbec8 | 4470 | pr_cont(" #%d", 10-count); |
fbb9ce95 IM |
4471 | mdelay(200); |
4472 | goto retry; | |
4473 | } | |
681fbec8 | 4474 | pr_cont(" ignoring it.\n"); |
fbb9ce95 | 4475 | unlock = 0; |
46fec7ac | 4476 | } else { |
4477 | if (count != 10) | |
681fbec8 | 4478 | pr_cont(" locked it.\n"); |
fbb9ce95 | 4479 | } |
fbb9ce95 IM |
4480 | |
4481 | do_each_thread(g, p) { | |
85684873 IM |
4482 | /* |
4483 | * It's not reliable to print a task's held locks | |
4484 | * if it's not sleeping (or if it's not the current | |
4485 | * task): | |
4486 | */ | |
4487 | if (p->state == TASK_RUNNING && p != current) | |
4488 | continue; | |
fbb9ce95 IM |
4489 | if (p->lockdep_depth) |
4490 | lockdep_print_held_locks(p); | |
4491 | if (!unlock) | |
4492 | if (read_trylock(&tasklist_lock)) | |
4493 | unlock = 1; | |
88f1c87d | 4494 | touch_nmi_watchdog(); |
fbb9ce95 IM |
4495 | } while_each_thread(g, p); |
4496 | ||
681fbec8 | 4497 | pr_warn("\n"); |
a5dd63ef | 4498 | pr_warn("=============================================\n\n"); |
fbb9ce95 IM |
4499 | |
4500 | if (unlock) | |
4501 | read_unlock(&tasklist_lock); | |
4502 | } | |
fbb9ce95 | 4503 | EXPORT_SYMBOL_GPL(debug_show_all_locks); |
8dce7a9a | 4504 | #endif |
fbb9ce95 | 4505 | |
82a1fcb9 IM |
4506 | /* |
4507 | * Careful: only use this function if you are sure that | |
4508 | * the task cannot run in parallel! | |
4509 | */ | |
f1b499f0 | 4510 | void debug_show_held_locks(struct task_struct *task) |
fbb9ce95 | 4511 | { |
9c35dd7f JP |
4512 | if (unlikely(!debug_locks)) { |
4513 | printk("INFO: lockdep is turned off.\n"); | |
4514 | return; | |
4515 | } | |
fbb9ce95 IM |
4516 | lockdep_print_held_locks(task); |
4517 | } | |
fbb9ce95 | 4518 | EXPORT_SYMBOL_GPL(debug_show_held_locks); |
b351d164 | 4519 | |
722a9f92 | 4520 | asmlinkage __visible void lockdep_sys_exit(void) |
b351d164 PZ |
4521 | { |
4522 | struct task_struct *curr = current; | |
4523 | ||
4524 | if (unlikely(curr->lockdep_depth)) { | |
4525 | if (!debug_locks_off()) | |
4526 | return; | |
681fbec8 | 4527 | pr_warn("\n"); |
a5dd63ef PM |
4528 | pr_warn("================================================\n"); |
4529 | pr_warn("WARNING: lock held when returning to user space!\n"); | |
fbdc4b9a | 4530 | print_kernel_ident(); |
a5dd63ef | 4531 | pr_warn("------------------------------------------------\n"); |
681fbec8 | 4532 | pr_warn("%s/%d is leaving the kernel with locks still held!\n", |
b351d164 PZ |
4533 | curr->comm, curr->pid); |
4534 | lockdep_print_held_locks(curr); | |
4535 | } | |
b09be676 BP |
4536 | |
4537 | /* | |
4538 | * The lock history for each syscall should be independent. So wipe the | |
4539 | * slate clean on return to userspace. | |
4540 | */ | |
f52be570 | 4541 | lockdep_invariant_state(false); |
b351d164 | 4542 | } |
0632eb3d | 4543 | |
b3fbab05 | 4544 | void lockdep_rcu_suspicious(const char *file, const int line, const char *s) |
0632eb3d PM |
4545 | { |
4546 | struct task_struct *curr = current; | |
4547 | ||
2b3fc35f | 4548 | /* Note: the following can be executed concurrently, so be careful. */ |
681fbec8 | 4549 | pr_warn("\n"); |
a5dd63ef PM |
4550 | pr_warn("=============================\n"); |
4551 | pr_warn("WARNING: suspicious RCU usage\n"); | |
fbdc4b9a | 4552 | print_kernel_ident(); |
a5dd63ef | 4553 | pr_warn("-----------------------------\n"); |
681fbec8 PM |
4554 | pr_warn("%s:%d %s!\n", file, line, s); |
4555 | pr_warn("\nother info that might help us debug this:\n\n"); | |
4556 | pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n", | |
c5fdcec9 PM |
4557 | !rcu_lockdep_current_cpu_online() |
4558 | ? "RCU used illegally from offline CPU!\n" | |
5c173eb8 | 4559 | : !rcu_is_watching() |
c5fdcec9 PM |
4560 | ? "RCU used illegally from idle CPU!\n" |
4561 | : "", | |
4562 | rcu_scheduler_active, debug_locks); | |
0464e937 FW |
4563 | |
4564 | /* | |
4565 | * If a CPU is in the RCU-free window in idle (ie: in the section | |
4566 | * between rcu_idle_enter() and rcu_idle_exit(), then RCU | |
4567 | * considers that CPU to be in an "extended quiescent state", | |
4568 | * which means that RCU will be completely ignoring that CPU. | |
4569 | * Therefore, rcu_read_lock() and friends have absolutely no | |
4570 | * effect on a CPU running in that state. In other words, even if | |
4571 | * such an RCU-idle CPU has called rcu_read_lock(), RCU might well | |
4572 | * delete data structures out from under it. RCU really has no | |
4573 | * choice here: we need to keep an RCU-free window in idle where | |
4574 | * the CPU may possibly enter into low power mode. This way we can | |
4575 | * notice an extended quiescent state to other CPUs that started a grace | |
4576 | * period. Otherwise we would delay any grace period as long as we run | |
4577 | * in the idle task. | |
4578 | * | |
4579 | * So complain bitterly if someone does call rcu_read_lock(), | |
4580 | * rcu_read_lock_bh() and so on from extended quiescent states. | |
4581 | */ | |
5c173eb8 | 4582 | if (!rcu_is_watching()) |
681fbec8 | 4583 | pr_warn("RCU used illegally from extended quiescent state!\n"); |
0464e937 | 4584 | |
0632eb3d | 4585 | lockdep_print_held_locks(curr); |
681fbec8 | 4586 | pr_warn("\nstack backtrace:\n"); |
0632eb3d PM |
4587 | dump_stack(); |
4588 | } | |
b3fbab05 | 4589 | EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); |