| 1 | /* |
| 2 | * kernel/lockdep.c |
| 3 | * |
| 4 | * Runtime locking correctness validator |
| 5 | * |
| 6 | * Started by Ingo Molnar: |
| 7 | * |
| 8 | * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
| 9 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
| 10 | * |
| 11 | * this code maps all the lock dependencies as they occur in a live kernel |
| 12 | * and will warn about the following classes of locking bugs: |
| 13 | * |
| 14 | * - lock inversion scenarios |
| 15 | * - circular lock dependencies |
| 16 | * - hardirq/softirq safe/unsafe locking bugs |
| 17 | * |
| 18 | * Bugs are reported even if the current locking scenario does not cause |
| 19 | * any deadlock at this point. |
| 20 | * |
| 21 | * I.e. if anytime in the past two locks were taken in a different order, |
| 22 | * even if it happened for another task, even if those were different |
| 23 | * locks (but of the same class as this lock), this code will detect it. |
| 24 | * |
| 25 | * Thanks to Arjan van de Ven for coming up with the initial idea of |
| 26 | * mapping lock dependencies runtime. |
| 27 | */ |
| 28 | #define DISABLE_BRANCH_PROFILING |
| 29 | #include <linux/mutex.h> |
| 30 | #include <linux/sched.h> |
| 31 | #include <linux/delay.h> |
| 32 | #include <linux/module.h> |
| 33 | #include <linux/proc_fs.h> |
| 34 | #include <linux/seq_file.h> |
| 35 | #include <linux/spinlock.h> |
| 36 | #include <linux/kallsyms.h> |
| 37 | #include <linux/interrupt.h> |
| 38 | #include <linux/stacktrace.h> |
| 39 | #include <linux/debug_locks.h> |
| 40 | #include <linux/irqflags.h> |
| 41 | #include <linux/utsname.h> |
| 42 | #include <linux/hash.h> |
| 43 | #include <linux/ftrace.h> |
| 44 | #include <linux/stringify.h> |
| 45 | #include <linux/bitops.h> |
| 46 | #include <linux/gfp.h> |
| 47 | |
| 48 | #include <asm/sections.h> |
| 49 | |
| 50 | #include "lockdep_internals.h" |
| 51 | |
| 52 | #define CREATE_TRACE_POINTS |
| 53 | #include <trace/events/lock.h> |
| 54 | |
| 55 | #ifdef CONFIG_PROVE_LOCKING |
| 56 | int prove_locking = 1; |
| 57 | module_param(prove_locking, int, 0644); |
| 58 | #else |
| 59 | #define prove_locking 0 |
| 60 | #endif |
| 61 | |
| 62 | #ifdef CONFIG_LOCK_STAT |
| 63 | int lock_stat = 1; |
| 64 | module_param(lock_stat, int, 0644); |
| 65 | #else |
| 66 | #define lock_stat 0 |
| 67 | #endif |
| 68 | |
| 69 | /* |
| 70 | * lockdep_lock: protects the lockdep graph, the hashes and the |
| 71 | * class/list/hash allocators. |
| 72 | * |
| 73 | * This is one of the rare exceptions where it's justified |
| 74 | * to use a raw spinlock - we really dont want the spinlock |
| 75 | * code to recurse back into the lockdep code... |
| 76 | */ |
| 77 | static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
| 78 | |
| 79 | static int graph_lock(void) |
| 80 | { |
| 81 | arch_spin_lock(&lockdep_lock); |
| 82 | /* |
| 83 | * Make sure that if another CPU detected a bug while |
| 84 | * walking the graph we dont change it (while the other |
| 85 | * CPU is busy printing out stuff with the graph lock |
| 86 | * dropped already) |
| 87 | */ |
| 88 | if (!debug_locks) { |
| 89 | arch_spin_unlock(&lockdep_lock); |
| 90 | return 0; |
| 91 | } |
| 92 | /* prevent any recursions within lockdep from causing deadlocks */ |
| 93 | current->lockdep_recursion++; |
| 94 | return 1; |
| 95 | } |
| 96 | |
| 97 | static inline int graph_unlock(void) |
| 98 | { |
| 99 | if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) |
| 100 | return DEBUG_LOCKS_WARN_ON(1); |
| 101 | |
| 102 | current->lockdep_recursion--; |
| 103 | arch_spin_unlock(&lockdep_lock); |
| 104 | return 0; |
| 105 | } |
| 106 | |
| 107 | /* |
| 108 | * Turn lock debugging off and return with 0 if it was off already, |
| 109 | * and also release the graph lock: |
| 110 | */ |
| 111 | static inline int debug_locks_off_graph_unlock(void) |
| 112 | { |
| 113 | int ret = debug_locks_off(); |
| 114 | |
| 115 | arch_spin_unlock(&lockdep_lock); |
| 116 | |
| 117 | return ret; |
| 118 | } |
| 119 | |
| 120 | static int lockdep_initialized; |
| 121 | |
| 122 | unsigned long nr_list_entries; |
| 123 | static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; |
| 124 | |
| 125 | /* |
| 126 | * All data structures here are protected by the global debug_lock. |
| 127 | * |
| 128 | * Mutex key structs only get allocated, once during bootup, and never |
| 129 | * get freed - this significantly simplifies the debugging code. |
| 130 | */ |
| 131 | unsigned long nr_lock_classes; |
| 132 | static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; |
| 133 | |
| 134 | static inline struct lock_class *hlock_class(struct held_lock *hlock) |
| 135 | { |
| 136 | if (!hlock->class_idx) { |
| 137 | DEBUG_LOCKS_WARN_ON(1); |
| 138 | return NULL; |
| 139 | } |
| 140 | return lock_classes + hlock->class_idx - 1; |
| 141 | } |
| 142 | |
| 143 | #ifdef CONFIG_LOCK_STAT |
| 144 | static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], |
| 145 | cpu_lock_stats); |
| 146 | |
| 147 | static inline u64 lockstat_clock(void) |
| 148 | { |
| 149 | return local_clock(); |
| 150 | } |
| 151 | |
| 152 | static int lock_point(unsigned long points[], unsigned long ip) |
| 153 | { |
| 154 | int i; |
| 155 | |
| 156 | for (i = 0; i < LOCKSTAT_POINTS; i++) { |
| 157 | if (points[i] == 0) { |
| 158 | points[i] = ip; |
| 159 | break; |
| 160 | } |
| 161 | if (points[i] == ip) |
| 162 | break; |
| 163 | } |
| 164 | |
| 165 | return i; |
| 166 | } |
| 167 | |
| 168 | static void lock_time_inc(struct lock_time *lt, u64 time) |
| 169 | { |
| 170 | if (time > lt->max) |
| 171 | lt->max = time; |
| 172 | |
| 173 | if (time < lt->min || !lt->nr) |
| 174 | lt->min = time; |
| 175 | |
| 176 | lt->total += time; |
| 177 | lt->nr++; |
| 178 | } |
| 179 | |
| 180 | static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) |
| 181 | { |
| 182 | if (!src->nr) |
| 183 | return; |
| 184 | |
| 185 | if (src->max > dst->max) |
| 186 | dst->max = src->max; |
| 187 | |
| 188 | if (src->min < dst->min || !dst->nr) |
| 189 | dst->min = src->min; |
| 190 | |
| 191 | dst->total += src->total; |
| 192 | dst->nr += src->nr; |
| 193 | } |
| 194 | |
| 195 | struct lock_class_stats lock_stats(struct lock_class *class) |
| 196 | { |
| 197 | struct lock_class_stats stats; |
| 198 | int cpu, i; |
| 199 | |
| 200 | memset(&stats, 0, sizeof(struct lock_class_stats)); |
| 201 | for_each_possible_cpu(cpu) { |
| 202 | struct lock_class_stats *pcs = |
| 203 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
| 204 | |
| 205 | for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) |
| 206 | stats.contention_point[i] += pcs->contention_point[i]; |
| 207 | |
| 208 | for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) |
| 209 | stats.contending_point[i] += pcs->contending_point[i]; |
| 210 | |
| 211 | lock_time_add(&pcs->read_waittime, &stats.read_waittime); |
| 212 | lock_time_add(&pcs->write_waittime, &stats.write_waittime); |
| 213 | |
| 214 | lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); |
| 215 | lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); |
| 216 | |
| 217 | for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) |
| 218 | stats.bounces[i] += pcs->bounces[i]; |
| 219 | } |
| 220 | |
| 221 | return stats; |
| 222 | } |
| 223 | |
| 224 | void clear_lock_stats(struct lock_class *class) |
| 225 | { |
| 226 | int cpu; |
| 227 | |
| 228 | for_each_possible_cpu(cpu) { |
| 229 | struct lock_class_stats *cpu_stats = |
| 230 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
| 231 | |
| 232 | memset(cpu_stats, 0, sizeof(struct lock_class_stats)); |
| 233 | } |
| 234 | memset(class->contention_point, 0, sizeof(class->contention_point)); |
| 235 | memset(class->contending_point, 0, sizeof(class->contending_point)); |
| 236 | } |
| 237 | |
| 238 | static struct lock_class_stats *get_lock_stats(struct lock_class *class) |
| 239 | { |
| 240 | return &get_cpu_var(cpu_lock_stats)[class - lock_classes]; |
| 241 | } |
| 242 | |
| 243 | static void put_lock_stats(struct lock_class_stats *stats) |
| 244 | { |
| 245 | put_cpu_var(cpu_lock_stats); |
| 246 | } |
| 247 | |
| 248 | static void lock_release_holdtime(struct held_lock *hlock) |
| 249 | { |
| 250 | struct lock_class_stats *stats; |
| 251 | u64 holdtime; |
| 252 | |
| 253 | if (!lock_stat) |
| 254 | return; |
| 255 | |
| 256 | holdtime = lockstat_clock() - hlock->holdtime_stamp; |
| 257 | |
| 258 | stats = get_lock_stats(hlock_class(hlock)); |
| 259 | if (hlock->read) |
| 260 | lock_time_inc(&stats->read_holdtime, holdtime); |
| 261 | else |
| 262 | lock_time_inc(&stats->write_holdtime, holdtime); |
| 263 | put_lock_stats(stats); |
| 264 | } |
| 265 | #else |
| 266 | static inline void lock_release_holdtime(struct held_lock *hlock) |
| 267 | { |
| 268 | } |
| 269 | #endif |
| 270 | |
| 271 | /* |
| 272 | * We keep a global list of all lock classes. The list only grows, |
| 273 | * never shrinks. The list is only accessed with the lockdep |
| 274 | * spinlock lock held. |
| 275 | */ |
| 276 | LIST_HEAD(all_lock_classes); |
| 277 | |
| 278 | /* |
| 279 | * The lockdep classes are in a hash-table as well, for fast lookup: |
| 280 | */ |
| 281 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) |
| 282 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) |
| 283 | #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) |
| 284 | #define classhashentry(key) (classhash_table + __classhashfn((key))) |
| 285 | |
| 286 | static struct list_head classhash_table[CLASSHASH_SIZE]; |
| 287 | |
| 288 | /* |
| 289 | * We put the lock dependency chains into a hash-table as well, to cache |
| 290 | * their existence: |
| 291 | */ |
| 292 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) |
| 293 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) |
| 294 | #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) |
| 295 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) |
| 296 | |
| 297 | static struct list_head chainhash_table[CHAINHASH_SIZE]; |
| 298 | |
| 299 | /* |
| 300 | * The hash key of the lock dependency chains is a hash itself too: |
| 301 | * it's a hash of all locks taken up to that lock, including that lock. |
| 302 | * It's a 64-bit hash, because it's important for the keys to be |
| 303 | * unique. |
| 304 | */ |
| 305 | #define iterate_chain_key(key1, key2) \ |
| 306 | (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \ |
| 307 | ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \ |
| 308 | (key2)) |
| 309 | |
| 310 | void lockdep_off(void) |
| 311 | { |
| 312 | current->lockdep_recursion++; |
| 313 | } |
| 314 | EXPORT_SYMBOL(lockdep_off); |
| 315 | |
| 316 | void lockdep_on(void) |
| 317 | { |
| 318 | current->lockdep_recursion--; |
| 319 | } |
| 320 | EXPORT_SYMBOL(lockdep_on); |
| 321 | |
| 322 | /* |
| 323 | * Debugging switches: |
| 324 | */ |
| 325 | |
| 326 | #define VERBOSE 0 |
| 327 | #define VERY_VERBOSE 0 |
| 328 | |
| 329 | #if VERBOSE |
| 330 | # define HARDIRQ_VERBOSE 1 |
| 331 | # define SOFTIRQ_VERBOSE 1 |
| 332 | # define RECLAIM_VERBOSE 1 |
| 333 | #else |
| 334 | # define HARDIRQ_VERBOSE 0 |
| 335 | # define SOFTIRQ_VERBOSE 0 |
| 336 | # define RECLAIM_VERBOSE 0 |
| 337 | #endif |
| 338 | |
| 339 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE |
| 340 | /* |
| 341 | * Quick filtering for interesting events: |
| 342 | */ |
| 343 | static int class_filter(struct lock_class *class) |
| 344 | { |
| 345 | #if 0 |
| 346 | /* Example */ |
| 347 | if (class->name_version == 1 && |
| 348 | !strcmp(class->name, "lockname")) |
| 349 | return 1; |
| 350 | if (class->name_version == 1 && |
| 351 | !strcmp(class->name, "&struct->lockfield")) |
| 352 | return 1; |
| 353 | #endif |
| 354 | /* Filter everything else. 1 would be to allow everything else */ |
| 355 | return 0; |
| 356 | } |
| 357 | #endif |
| 358 | |
| 359 | static int verbose(struct lock_class *class) |
| 360 | { |
| 361 | #if VERBOSE |
| 362 | return class_filter(class); |
| 363 | #endif |
| 364 | return 0; |
| 365 | } |
| 366 | |
| 367 | /* |
| 368 | * Stack-trace: tightly packed array of stack backtrace |
| 369 | * addresses. Protected by the graph_lock. |
| 370 | */ |
| 371 | unsigned long nr_stack_trace_entries; |
| 372 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; |
| 373 | |
| 374 | static int save_trace(struct stack_trace *trace) |
| 375 | { |
| 376 | trace->nr_entries = 0; |
| 377 | trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; |
| 378 | trace->entries = stack_trace + nr_stack_trace_entries; |
| 379 | |
| 380 | trace->skip = 3; |
| 381 | |
| 382 | save_stack_trace(trace); |
| 383 | |
| 384 | /* |
| 385 | * Some daft arches put -1 at the end to indicate its a full trace. |
| 386 | * |
| 387 | * <rant> this is buggy anyway, since it takes a whole extra entry so a |
| 388 | * complete trace that maxes out the entries provided will be reported |
| 389 | * as incomplete, friggin useless </rant> |
| 390 | */ |
| 391 | if (trace->nr_entries != 0 && |
| 392 | trace->entries[trace->nr_entries-1] == ULONG_MAX) |
| 393 | trace->nr_entries--; |
| 394 | |
| 395 | trace->max_entries = trace->nr_entries; |
| 396 | |
| 397 | nr_stack_trace_entries += trace->nr_entries; |
| 398 | |
| 399 | if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { |
| 400 | if (!debug_locks_off_graph_unlock()) |
| 401 | return 0; |
| 402 | |
| 403 | printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); |
| 404 | printk("turning off the locking correctness validator.\n"); |
| 405 | dump_stack(); |
| 406 | |
| 407 | return 0; |
| 408 | } |
| 409 | |
| 410 | return 1; |
| 411 | } |
| 412 | |
| 413 | unsigned int nr_hardirq_chains; |
| 414 | unsigned int nr_softirq_chains; |
| 415 | unsigned int nr_process_chains; |
| 416 | unsigned int max_lockdep_depth; |
| 417 | |
| 418 | #ifdef CONFIG_DEBUG_LOCKDEP |
| 419 | /* |
| 420 | * We cannot printk in early bootup code. Not even early_printk() |
| 421 | * might work. So we mark any initialization errors and printk |
| 422 | * about it later on, in lockdep_info(). |
| 423 | */ |
| 424 | static int lockdep_init_error; |
| 425 | static unsigned long lockdep_init_trace_data[20]; |
| 426 | static struct stack_trace lockdep_init_trace = { |
| 427 | .max_entries = ARRAY_SIZE(lockdep_init_trace_data), |
| 428 | .entries = lockdep_init_trace_data, |
| 429 | }; |
| 430 | |
| 431 | /* |
| 432 | * Various lockdep statistics: |
| 433 | */ |
| 434 | DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); |
| 435 | #endif |
| 436 | |
| 437 | /* |
| 438 | * Locking printouts: |
| 439 | */ |
| 440 | |
| 441 | #define __USAGE(__STATE) \ |
| 442 | [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ |
| 443 | [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ |
| 444 | [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ |
| 445 | [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", |
| 446 | |
| 447 | static const char *usage_str[] = |
| 448 | { |
| 449 | #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) |
| 450 | #include "lockdep_states.h" |
| 451 | #undef LOCKDEP_STATE |
| 452 | [LOCK_USED] = "INITIAL USE", |
| 453 | }; |
| 454 | |
| 455 | const char * __get_key_name(struct lockdep_subclass_key *key, char *str) |
| 456 | { |
| 457 | return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); |
| 458 | } |
| 459 | |
| 460 | static inline unsigned long lock_flag(enum lock_usage_bit bit) |
| 461 | { |
| 462 | return 1UL << bit; |
| 463 | } |
| 464 | |
| 465 | static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) |
| 466 | { |
| 467 | char c = '.'; |
| 468 | |
| 469 | if (class->usage_mask & lock_flag(bit + 2)) |
| 470 | c = '+'; |
| 471 | if (class->usage_mask & lock_flag(bit)) { |
| 472 | c = '-'; |
| 473 | if (class->usage_mask & lock_flag(bit + 2)) |
| 474 | c = '?'; |
| 475 | } |
| 476 | |
| 477 | return c; |
| 478 | } |
| 479 | |
| 480 | void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) |
| 481 | { |
| 482 | int i = 0; |
| 483 | |
| 484 | #define LOCKDEP_STATE(__STATE) \ |
| 485 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ |
| 486 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); |
| 487 | #include "lockdep_states.h" |
| 488 | #undef LOCKDEP_STATE |
| 489 | |
| 490 | usage[i] = '\0'; |
| 491 | } |
| 492 | |
| 493 | static void print_lock_name(struct lock_class *class) |
| 494 | { |
| 495 | char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS]; |
| 496 | const char *name; |
| 497 | |
| 498 | get_usage_chars(class, usage); |
| 499 | |
| 500 | name = class->name; |
| 501 | if (!name) { |
| 502 | name = __get_key_name(class->key, str); |
| 503 | printk(" (%s", name); |
| 504 | } else { |
| 505 | printk(" (%s", name); |
| 506 | if (class->name_version > 1) |
| 507 | printk("#%d", class->name_version); |
| 508 | if (class->subclass) |
| 509 | printk("/%d", class->subclass); |
| 510 | } |
| 511 | printk("){%s}", usage); |
| 512 | } |
| 513 | |
| 514 | static void print_lockdep_cache(struct lockdep_map *lock) |
| 515 | { |
| 516 | const char *name; |
| 517 | char str[KSYM_NAME_LEN]; |
| 518 | |
| 519 | name = lock->name; |
| 520 | if (!name) |
| 521 | name = __get_key_name(lock->key->subkeys, str); |
| 522 | |
| 523 | printk("%s", name); |
| 524 | } |
| 525 | |
| 526 | static void print_lock(struct held_lock *hlock) |
| 527 | { |
| 528 | print_lock_name(hlock_class(hlock)); |
| 529 | printk(", at: "); |
| 530 | print_ip_sym(hlock->acquire_ip); |
| 531 | } |
| 532 | |
| 533 | static void lockdep_print_held_locks(struct task_struct *curr) |
| 534 | { |
| 535 | int i, depth = curr->lockdep_depth; |
| 536 | |
| 537 | if (!depth) { |
| 538 | printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr)); |
| 539 | return; |
| 540 | } |
| 541 | printk("%d lock%s held by %s/%d:\n", |
| 542 | depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr)); |
| 543 | |
| 544 | for (i = 0; i < depth; i++) { |
| 545 | printk(" #%d: ", i); |
| 546 | print_lock(curr->held_locks + i); |
| 547 | } |
| 548 | } |
| 549 | |
| 550 | static void print_kernel_version(void) |
| 551 | { |
| 552 | printk("%s %.*s\n", init_utsname()->release, |
| 553 | (int)strcspn(init_utsname()->version, " "), |
| 554 | init_utsname()->version); |
| 555 | } |
| 556 | |
| 557 | static int very_verbose(struct lock_class *class) |
| 558 | { |
| 559 | #if VERY_VERBOSE |
| 560 | return class_filter(class); |
| 561 | #endif |
| 562 | return 0; |
| 563 | } |
| 564 | |
| 565 | /* |
| 566 | * Is this the address of a static object: |
| 567 | */ |
| 568 | static int static_obj(void *obj) |
| 569 | { |
| 570 | unsigned long start = (unsigned long) &_stext, |
| 571 | end = (unsigned long) &_end, |
| 572 | addr = (unsigned long) obj; |
| 573 | |
| 574 | /* |
| 575 | * static variable? |
| 576 | */ |
| 577 | if ((addr >= start) && (addr < end)) |
| 578 | return 1; |
| 579 | |
| 580 | if (arch_is_kernel_data(addr)) |
| 581 | return 1; |
| 582 | |
| 583 | /* |
| 584 | * in-kernel percpu var? |
| 585 | */ |
| 586 | if (is_kernel_percpu_address(addr)) |
| 587 | return 1; |
| 588 | |
| 589 | /* |
| 590 | * module static or percpu var? |
| 591 | */ |
| 592 | return is_module_address(addr) || is_module_percpu_address(addr); |
| 593 | } |
| 594 | |
| 595 | /* |
| 596 | * To make lock name printouts unique, we calculate a unique |
| 597 | * class->name_version generation counter: |
| 598 | */ |
| 599 | static int count_matching_names(struct lock_class *new_class) |
| 600 | { |
| 601 | struct lock_class *class; |
| 602 | int count = 0; |
| 603 | |
| 604 | if (!new_class->name) |
| 605 | return 0; |
| 606 | |
| 607 | list_for_each_entry(class, &all_lock_classes, lock_entry) { |
| 608 | if (new_class->key - new_class->subclass == class->key) |
| 609 | return class->name_version; |
| 610 | if (class->name && !strcmp(class->name, new_class->name)) |
| 611 | count = max(count, class->name_version); |
| 612 | } |
| 613 | |
| 614 | return count + 1; |
| 615 | } |
| 616 | |
| 617 | /* |
| 618 | * Register a lock's class in the hash-table, if the class is not present |
| 619 | * yet. Otherwise we look it up. We cache the result in the lock object |
| 620 | * itself, so actual lookup of the hash should be once per lock object. |
| 621 | */ |
| 622 | static inline struct lock_class * |
| 623 | look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) |
| 624 | { |
| 625 | struct lockdep_subclass_key *key; |
| 626 | struct list_head *hash_head; |
| 627 | struct lock_class *class; |
| 628 | |
| 629 | #ifdef CONFIG_DEBUG_LOCKDEP |
| 630 | /* |
| 631 | * If the architecture calls into lockdep before initializing |
| 632 | * the hashes then we'll warn about it later. (we cannot printk |
| 633 | * right now) |
| 634 | */ |
| 635 | if (unlikely(!lockdep_initialized)) { |
| 636 | lockdep_init(); |
| 637 | lockdep_init_error = 1; |
| 638 | save_stack_trace(&lockdep_init_trace); |
| 639 | } |
| 640 | #endif |
| 641 | |
| 642 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { |
| 643 | debug_locks_off(); |
| 644 | printk(KERN_ERR |
| 645 | "BUG: looking up invalid subclass: %u\n", subclass); |
| 646 | printk(KERN_ERR |
| 647 | "turning off the locking correctness validator.\n"); |
| 648 | dump_stack(); |
| 649 | return NULL; |
| 650 | } |
| 651 | |
| 652 | /* |
| 653 | * Static locks do not have their class-keys yet - for them the key |
| 654 | * is the lock object itself: |
| 655 | */ |
| 656 | if (unlikely(!lock->key)) |
| 657 | lock->key = (void *)lock; |
| 658 | |
| 659 | /* |
| 660 | * NOTE: the class-key must be unique. For dynamic locks, a static |
| 661 | * lock_class_key variable is passed in through the mutex_init() |
| 662 | * (or spin_lock_init()) call - which acts as the key. For static |
| 663 | * locks we use the lock object itself as the key. |
| 664 | */ |
| 665 | BUILD_BUG_ON(sizeof(struct lock_class_key) > |
| 666 | sizeof(struct lockdep_map)); |
| 667 | |
| 668 | key = lock->key->subkeys + subclass; |
| 669 | |
| 670 | hash_head = classhashentry(key); |
| 671 | |
| 672 | /* |
| 673 | * We can walk the hash lockfree, because the hash only |
| 674 | * grows, and we are careful when adding entries to the end: |
| 675 | */ |
| 676 | list_for_each_entry(class, hash_head, hash_entry) { |
| 677 | if (class->key == key) { |
| 678 | WARN_ON_ONCE(class->name != lock->name); |
| 679 | return class; |
| 680 | } |
| 681 | } |
| 682 | |
| 683 | return NULL; |
| 684 | } |
| 685 | |
| 686 | /* |
| 687 | * Register a lock's class in the hash-table, if the class is not present |
| 688 | * yet. Otherwise we look it up. We cache the result in the lock object |
| 689 | * itself, so actual lookup of the hash should be once per lock object. |
| 690 | */ |
| 691 | static inline struct lock_class * |
| 692 | register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) |
| 693 | { |
| 694 | struct lockdep_subclass_key *key; |
| 695 | struct list_head *hash_head; |
| 696 | struct lock_class *class; |
| 697 | unsigned long flags; |
| 698 | |
| 699 | class = look_up_lock_class(lock, subclass); |
| 700 | if (likely(class)) |
| 701 | return class; |
| 702 | |
| 703 | /* |
| 704 | * Debug-check: all keys must be persistent! |
| 705 | */ |
| 706 | if (!static_obj(lock->key)) { |
| 707 | debug_locks_off(); |
| 708 | printk("INFO: trying to register non-static key.\n"); |
| 709 | printk("the code is fine but needs lockdep annotation.\n"); |
| 710 | printk("turning off the locking correctness validator.\n"); |
| 711 | dump_stack(); |
| 712 | |
| 713 | return NULL; |
| 714 | } |
| 715 | |
| 716 | key = lock->key->subkeys + subclass; |
| 717 | hash_head = classhashentry(key); |
| 718 | |
| 719 | raw_local_irq_save(flags); |
| 720 | if (!graph_lock()) { |
| 721 | raw_local_irq_restore(flags); |
| 722 | return NULL; |
| 723 | } |
| 724 | /* |
| 725 | * We have to do the hash-walk again, to avoid races |
| 726 | * with another CPU: |
| 727 | */ |
| 728 | list_for_each_entry(class, hash_head, hash_entry) |
| 729 | if (class->key == key) |
| 730 | goto out_unlock_set; |
| 731 | /* |
| 732 | * Allocate a new key from the static array, and add it to |
| 733 | * the hash: |
| 734 | */ |
| 735 | if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { |
| 736 | if (!debug_locks_off_graph_unlock()) { |
| 737 | raw_local_irq_restore(flags); |
| 738 | return NULL; |
| 739 | } |
| 740 | raw_local_irq_restore(flags); |
| 741 | |
| 742 | printk("BUG: MAX_LOCKDEP_KEYS too low!\n"); |
| 743 | printk("turning off the locking correctness validator.\n"); |
| 744 | dump_stack(); |
| 745 | return NULL; |
| 746 | } |
| 747 | class = lock_classes + nr_lock_classes++; |
| 748 | debug_atomic_inc(nr_unused_locks); |
| 749 | class->key = key; |
| 750 | class->name = lock->name; |
| 751 | class->subclass = subclass; |
| 752 | INIT_LIST_HEAD(&class->lock_entry); |
| 753 | INIT_LIST_HEAD(&class->locks_before); |
| 754 | INIT_LIST_HEAD(&class->locks_after); |
| 755 | class->name_version = count_matching_names(class); |
| 756 | /* |
| 757 | * We use RCU's safe list-add method to make |
| 758 | * parallel walking of the hash-list safe: |
| 759 | */ |
| 760 | list_add_tail_rcu(&class->hash_entry, hash_head); |
| 761 | /* |
| 762 | * Add it to the global list of classes: |
| 763 | */ |
| 764 | list_add_tail_rcu(&class->lock_entry, &all_lock_classes); |
| 765 | |
| 766 | if (verbose(class)) { |
| 767 | graph_unlock(); |
| 768 | raw_local_irq_restore(flags); |
| 769 | |
| 770 | printk("\nnew class %p: %s", class->key, class->name); |
| 771 | if (class->name_version > 1) |
| 772 | printk("#%d", class->name_version); |
| 773 | printk("\n"); |
| 774 | dump_stack(); |
| 775 | |
| 776 | raw_local_irq_save(flags); |
| 777 | if (!graph_lock()) { |
| 778 | raw_local_irq_restore(flags); |
| 779 | return NULL; |
| 780 | } |
| 781 | } |
| 782 | out_unlock_set: |
| 783 | graph_unlock(); |
| 784 | raw_local_irq_restore(flags); |
| 785 | |
| 786 | if (!subclass || force) |
| 787 | lock->class_cache[0] = class; |
| 788 | else if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
| 789 | lock->class_cache[subclass] = class; |
| 790 | |
| 791 | if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) |
| 792 | return NULL; |
| 793 | |
| 794 | return class; |
| 795 | } |
| 796 | |
| 797 | #ifdef CONFIG_PROVE_LOCKING |
| 798 | /* |
| 799 | * Allocate a lockdep entry. (assumes the graph_lock held, returns |
| 800 | * with NULL on failure) |
| 801 | */ |
| 802 | static struct lock_list *alloc_list_entry(void) |
| 803 | { |
| 804 | if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { |
| 805 | if (!debug_locks_off_graph_unlock()) |
| 806 | return NULL; |
| 807 | |
| 808 | printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n"); |
| 809 | printk("turning off the locking correctness validator.\n"); |
| 810 | dump_stack(); |
| 811 | return NULL; |
| 812 | } |
| 813 | return list_entries + nr_list_entries++; |
| 814 | } |
| 815 | |
| 816 | /* |
| 817 | * Add a new dependency to the head of the list: |
| 818 | */ |
| 819 | static int add_lock_to_list(struct lock_class *class, struct lock_class *this, |
| 820 | struct list_head *head, unsigned long ip, |
| 821 | int distance, struct stack_trace *trace) |
| 822 | { |
| 823 | struct lock_list *entry; |
| 824 | /* |
| 825 | * Lock not present yet - get a new dependency struct and |
| 826 | * add it to the list: |
| 827 | */ |
| 828 | entry = alloc_list_entry(); |
| 829 | if (!entry) |
| 830 | return 0; |
| 831 | |
| 832 | entry->class = this; |
| 833 | entry->distance = distance; |
| 834 | entry->trace = *trace; |
| 835 | /* |
| 836 | * Since we never remove from the dependency list, the list can |
| 837 | * be walked lockless by other CPUs, it's only allocation |
| 838 | * that must be protected by the spinlock. But this also means |
| 839 | * we must make new entries visible only once writes to the |
| 840 | * entry become visible - hence the RCU op: |
| 841 | */ |
| 842 | list_add_tail_rcu(&entry->entry, head); |
| 843 | |
| 844 | return 1; |
| 845 | } |
| 846 | |
| 847 | /* |
| 848 | * For good efficiency of modular, we use power of 2 |
| 849 | */ |
| 850 | #define MAX_CIRCULAR_QUEUE_SIZE 4096UL |
| 851 | #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) |
| 852 | |
| 853 | /* |
| 854 | * The circular_queue and helpers is used to implement the |
| 855 | * breadth-first search(BFS)algorithem, by which we can build |
| 856 | * the shortest path from the next lock to be acquired to the |
| 857 | * previous held lock if there is a circular between them. |
| 858 | */ |
| 859 | struct circular_queue { |
| 860 | unsigned long element[MAX_CIRCULAR_QUEUE_SIZE]; |
| 861 | unsigned int front, rear; |
| 862 | }; |
| 863 | |
| 864 | static struct circular_queue lock_cq; |
| 865 | |
| 866 | unsigned int max_bfs_queue_depth; |
| 867 | |
| 868 | static unsigned int lockdep_dependency_gen_id; |
| 869 | |
| 870 | static inline void __cq_init(struct circular_queue *cq) |
| 871 | { |
| 872 | cq->front = cq->rear = 0; |
| 873 | lockdep_dependency_gen_id++; |
| 874 | } |
| 875 | |
| 876 | static inline int __cq_empty(struct circular_queue *cq) |
| 877 | { |
| 878 | return (cq->front == cq->rear); |
| 879 | } |
| 880 | |
| 881 | static inline int __cq_full(struct circular_queue *cq) |
| 882 | { |
| 883 | return ((cq->rear + 1) & CQ_MASK) == cq->front; |
| 884 | } |
| 885 | |
| 886 | static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) |
| 887 | { |
| 888 | if (__cq_full(cq)) |
| 889 | return -1; |
| 890 | |
| 891 | cq->element[cq->rear] = elem; |
| 892 | cq->rear = (cq->rear + 1) & CQ_MASK; |
| 893 | return 0; |
| 894 | } |
| 895 | |
| 896 | static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) |
| 897 | { |
| 898 | if (__cq_empty(cq)) |
| 899 | return -1; |
| 900 | |
| 901 | *elem = cq->element[cq->front]; |
| 902 | cq->front = (cq->front + 1) & CQ_MASK; |
| 903 | return 0; |
| 904 | } |
| 905 | |
| 906 | static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) |
| 907 | { |
| 908 | return (cq->rear - cq->front) & CQ_MASK; |
| 909 | } |
| 910 | |
| 911 | static inline void mark_lock_accessed(struct lock_list *lock, |
| 912 | struct lock_list *parent) |
| 913 | { |
| 914 | unsigned long nr; |
| 915 | |
| 916 | nr = lock - list_entries; |
| 917 | WARN_ON(nr >= nr_list_entries); |
| 918 | lock->parent = parent; |
| 919 | lock->class->dep_gen_id = lockdep_dependency_gen_id; |
| 920 | } |
| 921 | |
| 922 | static inline unsigned long lock_accessed(struct lock_list *lock) |
| 923 | { |
| 924 | unsigned long nr; |
| 925 | |
| 926 | nr = lock - list_entries; |
| 927 | WARN_ON(nr >= nr_list_entries); |
| 928 | return lock->class->dep_gen_id == lockdep_dependency_gen_id; |
| 929 | } |
| 930 | |
| 931 | static inline struct lock_list *get_lock_parent(struct lock_list *child) |
| 932 | { |
| 933 | return child->parent; |
| 934 | } |
| 935 | |
| 936 | static inline int get_lock_depth(struct lock_list *child) |
| 937 | { |
| 938 | int depth = 0; |
| 939 | struct lock_list *parent; |
| 940 | |
| 941 | while ((parent = get_lock_parent(child))) { |
| 942 | child = parent; |
| 943 | depth++; |
| 944 | } |
| 945 | return depth; |
| 946 | } |
| 947 | |
| 948 | static int __bfs(struct lock_list *source_entry, |
| 949 | void *data, |
| 950 | int (*match)(struct lock_list *entry, void *data), |
| 951 | struct lock_list **target_entry, |
| 952 | int forward) |
| 953 | { |
| 954 | struct lock_list *entry; |
| 955 | struct list_head *head; |
| 956 | struct circular_queue *cq = &lock_cq; |
| 957 | int ret = 1; |
| 958 | |
| 959 | if (match(source_entry, data)) { |
| 960 | *target_entry = source_entry; |
| 961 | ret = 0; |
| 962 | goto exit; |
| 963 | } |
| 964 | |
| 965 | if (forward) |
| 966 | head = &source_entry->class->locks_after; |
| 967 | else |
| 968 | head = &source_entry->class->locks_before; |
| 969 | |
| 970 | if (list_empty(head)) |
| 971 | goto exit; |
| 972 | |
| 973 | __cq_init(cq); |
| 974 | __cq_enqueue(cq, (unsigned long)source_entry); |
| 975 | |
| 976 | while (!__cq_empty(cq)) { |
| 977 | struct lock_list *lock; |
| 978 | |
| 979 | __cq_dequeue(cq, (unsigned long *)&lock); |
| 980 | |
| 981 | if (!lock->class) { |
| 982 | ret = -2; |
| 983 | goto exit; |
| 984 | } |
| 985 | |
| 986 | if (forward) |
| 987 | head = &lock->class->locks_after; |
| 988 | else |
| 989 | head = &lock->class->locks_before; |
| 990 | |
| 991 | list_for_each_entry(entry, head, entry) { |
| 992 | if (!lock_accessed(entry)) { |
| 993 | unsigned int cq_depth; |
| 994 | mark_lock_accessed(entry, lock); |
| 995 | if (match(entry, data)) { |
| 996 | *target_entry = entry; |
| 997 | ret = 0; |
| 998 | goto exit; |
| 999 | } |
| 1000 | |
| 1001 | if (__cq_enqueue(cq, (unsigned long)entry)) { |
| 1002 | ret = -1; |
| 1003 | goto exit; |
| 1004 | } |
| 1005 | cq_depth = __cq_get_elem_count(cq); |
| 1006 | if (max_bfs_queue_depth < cq_depth) |
| 1007 | max_bfs_queue_depth = cq_depth; |
| 1008 | } |
| 1009 | } |
| 1010 | } |
| 1011 | exit: |
| 1012 | return ret; |
| 1013 | } |
| 1014 | |
| 1015 | static inline int __bfs_forwards(struct lock_list *src_entry, |
| 1016 | void *data, |
| 1017 | int (*match)(struct lock_list *entry, void *data), |
| 1018 | struct lock_list **target_entry) |
| 1019 | { |
| 1020 | return __bfs(src_entry, data, match, target_entry, 1); |
| 1021 | |
| 1022 | } |
| 1023 | |
| 1024 | static inline int __bfs_backwards(struct lock_list *src_entry, |
| 1025 | void *data, |
| 1026 | int (*match)(struct lock_list *entry, void *data), |
| 1027 | struct lock_list **target_entry) |
| 1028 | { |
| 1029 | return __bfs(src_entry, data, match, target_entry, 0); |
| 1030 | |
| 1031 | } |
| 1032 | |
| 1033 | /* |
| 1034 | * Recursive, forwards-direction lock-dependency checking, used for |
| 1035 | * both noncyclic checking and for hardirq-unsafe/softirq-unsafe |
| 1036 | * checking. |
| 1037 | */ |
| 1038 | |
| 1039 | /* |
| 1040 | * Print a dependency chain entry (this is only done when a deadlock |
| 1041 | * has been detected): |
| 1042 | */ |
| 1043 | static noinline int |
| 1044 | print_circular_bug_entry(struct lock_list *target, int depth) |
| 1045 | { |
| 1046 | if (debug_locks_silent) |
| 1047 | return 0; |
| 1048 | printk("\n-> #%u", depth); |
| 1049 | print_lock_name(target->class); |
| 1050 | printk(":\n"); |
| 1051 | print_stack_trace(&target->trace, 6); |
| 1052 | |
| 1053 | return 0; |
| 1054 | } |
| 1055 | |
| 1056 | /* |
| 1057 | * When a circular dependency is detected, print the |
| 1058 | * header first: |
| 1059 | */ |
| 1060 | static noinline int |
| 1061 | print_circular_bug_header(struct lock_list *entry, unsigned int depth, |
| 1062 | struct held_lock *check_src, |
| 1063 | struct held_lock *check_tgt) |
| 1064 | { |
| 1065 | struct task_struct *curr = current; |
| 1066 | |
| 1067 | if (debug_locks_silent) |
| 1068 | return 0; |
| 1069 | |
| 1070 | printk("\n=======================================================\n"); |
| 1071 | printk( "[ INFO: possible circular locking dependency detected ]\n"); |
| 1072 | print_kernel_version(); |
| 1073 | printk( "-------------------------------------------------------\n"); |
| 1074 | printk("%s/%d is trying to acquire lock:\n", |
| 1075 | curr->comm, task_pid_nr(curr)); |
| 1076 | print_lock(check_src); |
| 1077 | printk("\nbut task is already holding lock:\n"); |
| 1078 | print_lock(check_tgt); |
| 1079 | printk("\nwhich lock already depends on the new lock.\n\n"); |
| 1080 | printk("\nthe existing dependency chain (in reverse order) is:\n"); |
| 1081 | |
| 1082 | print_circular_bug_entry(entry, depth); |
| 1083 | |
| 1084 | return 0; |
| 1085 | } |
| 1086 | |
| 1087 | static inline int class_equal(struct lock_list *entry, void *data) |
| 1088 | { |
| 1089 | return entry->class == data; |
| 1090 | } |
| 1091 | |
| 1092 | static noinline int print_circular_bug(struct lock_list *this, |
| 1093 | struct lock_list *target, |
| 1094 | struct held_lock *check_src, |
| 1095 | struct held_lock *check_tgt) |
| 1096 | { |
| 1097 | struct task_struct *curr = current; |
| 1098 | struct lock_list *parent; |
| 1099 | int depth; |
| 1100 | |
| 1101 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
| 1102 | return 0; |
| 1103 | |
| 1104 | if (!save_trace(&this->trace)) |
| 1105 | return 0; |
| 1106 | |
| 1107 | depth = get_lock_depth(target); |
| 1108 | |
| 1109 | print_circular_bug_header(target, depth, check_src, check_tgt); |
| 1110 | |
| 1111 | parent = get_lock_parent(target); |
| 1112 | |
| 1113 | while (parent) { |
| 1114 | print_circular_bug_entry(parent, --depth); |
| 1115 | parent = get_lock_parent(parent); |
| 1116 | } |
| 1117 | |
| 1118 | printk("\nother info that might help us debug this:\n\n"); |
| 1119 | lockdep_print_held_locks(curr); |
| 1120 | |
| 1121 | printk("\nstack backtrace:\n"); |
| 1122 | dump_stack(); |
| 1123 | |
| 1124 | return 0; |
| 1125 | } |
| 1126 | |
| 1127 | static noinline int print_bfs_bug(int ret) |
| 1128 | { |
| 1129 | if (!debug_locks_off_graph_unlock()) |
| 1130 | return 0; |
| 1131 | |
| 1132 | WARN(1, "lockdep bfs error:%d\n", ret); |
| 1133 | |
| 1134 | return 0; |
| 1135 | } |
| 1136 | |
| 1137 | static int noop_count(struct lock_list *entry, void *data) |
| 1138 | { |
| 1139 | (*(unsigned long *)data)++; |
| 1140 | return 0; |
| 1141 | } |
| 1142 | |
| 1143 | unsigned long __lockdep_count_forward_deps(struct lock_list *this) |
| 1144 | { |
| 1145 | unsigned long count = 0; |
| 1146 | struct lock_list *uninitialized_var(target_entry); |
| 1147 | |
| 1148 | __bfs_forwards(this, (void *)&count, noop_count, &target_entry); |
| 1149 | |
| 1150 | return count; |
| 1151 | } |
| 1152 | unsigned long lockdep_count_forward_deps(struct lock_class *class) |
| 1153 | { |
| 1154 | unsigned long ret, flags; |
| 1155 | struct lock_list this; |
| 1156 | |
| 1157 | this.parent = NULL; |
| 1158 | this.class = class; |
| 1159 | |
| 1160 | local_irq_save(flags); |
| 1161 | arch_spin_lock(&lockdep_lock); |
| 1162 | ret = __lockdep_count_forward_deps(&this); |
| 1163 | arch_spin_unlock(&lockdep_lock); |
| 1164 | local_irq_restore(flags); |
| 1165 | |
| 1166 | return ret; |
| 1167 | } |
| 1168 | |
| 1169 | unsigned long __lockdep_count_backward_deps(struct lock_list *this) |
| 1170 | { |
| 1171 | unsigned long count = 0; |
| 1172 | struct lock_list *uninitialized_var(target_entry); |
| 1173 | |
| 1174 | __bfs_backwards(this, (void *)&count, noop_count, &target_entry); |
| 1175 | |
| 1176 | return count; |
| 1177 | } |
| 1178 | |
| 1179 | unsigned long lockdep_count_backward_deps(struct lock_class *class) |
| 1180 | { |
| 1181 | unsigned long ret, flags; |
| 1182 | struct lock_list this; |
| 1183 | |
| 1184 | this.parent = NULL; |
| 1185 | this.class = class; |
| 1186 | |
| 1187 | local_irq_save(flags); |
| 1188 | arch_spin_lock(&lockdep_lock); |
| 1189 | ret = __lockdep_count_backward_deps(&this); |
| 1190 | arch_spin_unlock(&lockdep_lock); |
| 1191 | local_irq_restore(flags); |
| 1192 | |
| 1193 | return ret; |
| 1194 | } |
| 1195 | |
| 1196 | /* |
| 1197 | * Prove that the dependency graph starting at <entry> can not |
| 1198 | * lead to <target>. Print an error and return 0 if it does. |
| 1199 | */ |
| 1200 | static noinline int |
| 1201 | check_noncircular(struct lock_list *root, struct lock_class *target, |
| 1202 | struct lock_list **target_entry) |
| 1203 | { |
| 1204 | int result; |
| 1205 | |
| 1206 | debug_atomic_inc(nr_cyclic_checks); |
| 1207 | |
| 1208 | result = __bfs_forwards(root, target, class_equal, target_entry); |
| 1209 | |
| 1210 | return result; |
| 1211 | } |
| 1212 | |
| 1213 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
| 1214 | /* |
| 1215 | * Forwards and backwards subgraph searching, for the purposes of |
| 1216 | * proving that two subgraphs can be connected by a new dependency |
| 1217 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. |
| 1218 | */ |
| 1219 | |
| 1220 | static inline int usage_match(struct lock_list *entry, void *bit) |
| 1221 | { |
| 1222 | return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); |
| 1223 | } |
| 1224 | |
| 1225 | |
| 1226 | |
| 1227 | /* |
| 1228 | * Find a node in the forwards-direction dependency sub-graph starting |
| 1229 | * at @root->class that matches @bit. |
| 1230 | * |
| 1231 | * Return 0 if such a node exists in the subgraph, and put that node |
| 1232 | * into *@target_entry. |
| 1233 | * |
| 1234 | * Return 1 otherwise and keep *@target_entry unchanged. |
| 1235 | * Return <0 on error. |
| 1236 | */ |
| 1237 | static int |
| 1238 | find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, |
| 1239 | struct lock_list **target_entry) |
| 1240 | { |
| 1241 | int result; |
| 1242 | |
| 1243 | debug_atomic_inc(nr_find_usage_forwards_checks); |
| 1244 | |
| 1245 | result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); |
| 1246 | |
| 1247 | return result; |
| 1248 | } |
| 1249 | |
| 1250 | /* |
| 1251 | * Find a node in the backwards-direction dependency sub-graph starting |
| 1252 | * at @root->class that matches @bit. |
| 1253 | * |
| 1254 | * Return 0 if such a node exists in the subgraph, and put that node |
| 1255 | * into *@target_entry. |
| 1256 | * |
| 1257 | * Return 1 otherwise and keep *@target_entry unchanged. |
| 1258 | * Return <0 on error. |
| 1259 | */ |
| 1260 | static int |
| 1261 | find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, |
| 1262 | struct lock_list **target_entry) |
| 1263 | { |
| 1264 | int result; |
| 1265 | |
| 1266 | debug_atomic_inc(nr_find_usage_backwards_checks); |
| 1267 | |
| 1268 | result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); |
| 1269 | |
| 1270 | return result; |
| 1271 | } |
| 1272 | |
| 1273 | static void print_lock_class_header(struct lock_class *class, int depth) |
| 1274 | { |
| 1275 | int bit; |
| 1276 | |
| 1277 | printk("%*s->", depth, ""); |
| 1278 | print_lock_name(class); |
| 1279 | printk(" ops: %lu", class->ops); |
| 1280 | printk(" {\n"); |
| 1281 | |
| 1282 | for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { |
| 1283 | if (class->usage_mask & (1 << bit)) { |
| 1284 | int len = depth; |
| 1285 | |
| 1286 | len += printk("%*s %s", depth, "", usage_str[bit]); |
| 1287 | len += printk(" at:\n"); |
| 1288 | print_stack_trace(class->usage_traces + bit, len); |
| 1289 | } |
| 1290 | } |
| 1291 | printk("%*s }\n", depth, ""); |
| 1292 | |
| 1293 | printk("%*s ... key at: ",depth,""); |
| 1294 | print_ip_sym((unsigned long)class->key); |
| 1295 | } |
| 1296 | |
| 1297 | /* |
| 1298 | * printk the shortest lock dependencies from @start to @end in reverse order: |
| 1299 | */ |
| 1300 | static void __used |
| 1301 | print_shortest_lock_dependencies(struct lock_list *leaf, |
| 1302 | struct lock_list *root) |
| 1303 | { |
| 1304 | struct lock_list *entry = leaf; |
| 1305 | int depth; |
| 1306 | |
| 1307 | /*compute depth from generated tree by BFS*/ |
| 1308 | depth = get_lock_depth(leaf); |
| 1309 | |
| 1310 | do { |
| 1311 | print_lock_class_header(entry->class, depth); |
| 1312 | printk("%*s ... acquired at:\n", depth, ""); |
| 1313 | print_stack_trace(&entry->trace, 2); |
| 1314 | printk("\n"); |
| 1315 | |
| 1316 | if (depth == 0 && (entry != root)) { |
| 1317 | printk("lockdep:%s bad BFS generated tree\n", __func__); |
| 1318 | break; |
| 1319 | } |
| 1320 | |
| 1321 | entry = get_lock_parent(entry); |
| 1322 | depth--; |
| 1323 | } while (entry && (depth >= 0)); |
| 1324 | |
| 1325 | return; |
| 1326 | } |
| 1327 | |
| 1328 | static int |
| 1329 | print_bad_irq_dependency(struct task_struct *curr, |
| 1330 | struct lock_list *prev_root, |
| 1331 | struct lock_list *next_root, |
| 1332 | struct lock_list *backwards_entry, |
| 1333 | struct lock_list *forwards_entry, |
| 1334 | struct held_lock *prev, |
| 1335 | struct held_lock *next, |
| 1336 | enum lock_usage_bit bit1, |
| 1337 | enum lock_usage_bit bit2, |
| 1338 | const char *irqclass) |
| 1339 | { |
| 1340 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
| 1341 | return 0; |
| 1342 | |
| 1343 | printk("\n======================================================\n"); |
| 1344 | printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", |
| 1345 | irqclass, irqclass); |
| 1346 | print_kernel_version(); |
| 1347 | printk( "------------------------------------------------------\n"); |
| 1348 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", |
| 1349 | curr->comm, task_pid_nr(curr), |
| 1350 | curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, |
| 1351 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, |
| 1352 | curr->hardirqs_enabled, |
| 1353 | curr->softirqs_enabled); |
| 1354 | print_lock(next); |
| 1355 | |
| 1356 | printk("\nand this task is already holding:\n"); |
| 1357 | print_lock(prev); |
| 1358 | printk("which would create a new lock dependency:\n"); |
| 1359 | print_lock_name(hlock_class(prev)); |
| 1360 | printk(" ->"); |
| 1361 | print_lock_name(hlock_class(next)); |
| 1362 | printk("\n"); |
| 1363 | |
| 1364 | printk("\nbut this new dependency connects a %s-irq-safe lock:\n", |
| 1365 | irqclass); |
| 1366 | print_lock_name(backwards_entry->class); |
| 1367 | printk("\n... which became %s-irq-safe at:\n", irqclass); |
| 1368 | |
| 1369 | print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); |
| 1370 | |
| 1371 | printk("\nto a %s-irq-unsafe lock:\n", irqclass); |
| 1372 | print_lock_name(forwards_entry->class); |
| 1373 | printk("\n... which became %s-irq-unsafe at:\n", irqclass); |
| 1374 | printk("..."); |
| 1375 | |
| 1376 | print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); |
| 1377 | |
| 1378 | printk("\nother info that might help us debug this:\n\n"); |
| 1379 | lockdep_print_held_locks(curr); |
| 1380 | |
| 1381 | printk("\nthe dependencies between %s-irq-safe lock", irqclass); |
| 1382 | printk(" and the holding lock:\n"); |
| 1383 | if (!save_trace(&prev_root->trace)) |
| 1384 | return 0; |
| 1385 | print_shortest_lock_dependencies(backwards_entry, prev_root); |
| 1386 | |
| 1387 | printk("\nthe dependencies between the lock to be acquired"); |
| 1388 | printk(" and %s-irq-unsafe lock:\n", irqclass); |
| 1389 | if (!save_trace(&next_root->trace)) |
| 1390 | return 0; |
| 1391 | print_shortest_lock_dependencies(forwards_entry, next_root); |
| 1392 | |
| 1393 | printk("\nstack backtrace:\n"); |
| 1394 | dump_stack(); |
| 1395 | |
| 1396 | return 0; |
| 1397 | } |
| 1398 | |
| 1399 | static int |
| 1400 | check_usage(struct task_struct *curr, struct held_lock *prev, |
| 1401 | struct held_lock *next, enum lock_usage_bit bit_backwards, |
| 1402 | enum lock_usage_bit bit_forwards, const char *irqclass) |
| 1403 | { |
| 1404 | int ret; |
| 1405 | struct lock_list this, that; |
| 1406 | struct lock_list *uninitialized_var(target_entry); |
| 1407 | struct lock_list *uninitialized_var(target_entry1); |
| 1408 | |
| 1409 | this.parent = NULL; |
| 1410 | |
| 1411 | this.class = hlock_class(prev); |
| 1412 | ret = find_usage_backwards(&this, bit_backwards, &target_entry); |
| 1413 | if (ret < 0) |
| 1414 | return print_bfs_bug(ret); |
| 1415 | if (ret == 1) |
| 1416 | return ret; |
| 1417 | |
| 1418 | that.parent = NULL; |
| 1419 | that.class = hlock_class(next); |
| 1420 | ret = find_usage_forwards(&that, bit_forwards, &target_entry1); |
| 1421 | if (ret < 0) |
| 1422 | return print_bfs_bug(ret); |
| 1423 | if (ret == 1) |
| 1424 | return ret; |
| 1425 | |
| 1426 | return print_bad_irq_dependency(curr, &this, &that, |
| 1427 | target_entry, target_entry1, |
| 1428 | prev, next, |
| 1429 | bit_backwards, bit_forwards, irqclass); |
| 1430 | } |
| 1431 | |
| 1432 | static const char *state_names[] = { |
| 1433 | #define LOCKDEP_STATE(__STATE) \ |
| 1434 | __stringify(__STATE), |
| 1435 | #include "lockdep_states.h" |
| 1436 | #undef LOCKDEP_STATE |
| 1437 | }; |
| 1438 | |
| 1439 | static const char *state_rnames[] = { |
| 1440 | #define LOCKDEP_STATE(__STATE) \ |
| 1441 | __stringify(__STATE)"-READ", |
| 1442 | #include "lockdep_states.h" |
| 1443 | #undef LOCKDEP_STATE |
| 1444 | }; |
| 1445 | |
| 1446 | static inline const char *state_name(enum lock_usage_bit bit) |
| 1447 | { |
| 1448 | return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2]; |
| 1449 | } |
| 1450 | |
| 1451 | static int exclusive_bit(int new_bit) |
| 1452 | { |
| 1453 | /* |
| 1454 | * USED_IN |
| 1455 | * USED_IN_READ |
| 1456 | * ENABLED |
| 1457 | * ENABLED_READ |
| 1458 | * |
| 1459 | * bit 0 - write/read |
| 1460 | * bit 1 - used_in/enabled |
| 1461 | * bit 2+ state |
| 1462 | */ |
| 1463 | |
| 1464 | int state = new_bit & ~3; |
| 1465 | int dir = new_bit & 2; |
| 1466 | |
| 1467 | /* |
| 1468 | * keep state, bit flip the direction and strip read. |
| 1469 | */ |
| 1470 | return state | (dir ^ 2); |
| 1471 | } |
| 1472 | |
| 1473 | static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, |
| 1474 | struct held_lock *next, enum lock_usage_bit bit) |
| 1475 | { |
| 1476 | /* |
| 1477 | * Prove that the new dependency does not connect a hardirq-safe |
| 1478 | * lock with a hardirq-unsafe lock - to achieve this we search |
| 1479 | * the backwards-subgraph starting at <prev>, and the |
| 1480 | * forwards-subgraph starting at <next>: |
| 1481 | */ |
| 1482 | if (!check_usage(curr, prev, next, bit, |
| 1483 | exclusive_bit(bit), state_name(bit))) |
| 1484 | return 0; |
| 1485 | |
| 1486 | bit++; /* _READ */ |
| 1487 | |
| 1488 | /* |
| 1489 | * Prove that the new dependency does not connect a hardirq-safe-read |
| 1490 | * lock with a hardirq-unsafe lock - to achieve this we search |
| 1491 | * the backwards-subgraph starting at <prev>, and the |
| 1492 | * forwards-subgraph starting at <next>: |
| 1493 | */ |
| 1494 | if (!check_usage(curr, prev, next, bit, |
| 1495 | exclusive_bit(bit), state_name(bit))) |
| 1496 | return 0; |
| 1497 | |
| 1498 | return 1; |
| 1499 | } |
| 1500 | |
| 1501 | static int |
| 1502 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, |
| 1503 | struct held_lock *next) |
| 1504 | { |
| 1505 | #define LOCKDEP_STATE(__STATE) \ |
| 1506 | if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ |
| 1507 | return 0; |
| 1508 | #include "lockdep_states.h" |
| 1509 | #undef LOCKDEP_STATE |
| 1510 | |
| 1511 | return 1; |
| 1512 | } |
| 1513 | |
| 1514 | static void inc_chains(void) |
| 1515 | { |
| 1516 | if (current->hardirq_context) |
| 1517 | nr_hardirq_chains++; |
| 1518 | else { |
| 1519 | if (current->softirq_context) |
| 1520 | nr_softirq_chains++; |
| 1521 | else |
| 1522 | nr_process_chains++; |
| 1523 | } |
| 1524 | } |
| 1525 | |
| 1526 | #else |
| 1527 | |
| 1528 | static inline int |
| 1529 | check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, |
| 1530 | struct held_lock *next) |
| 1531 | { |
| 1532 | return 1; |
| 1533 | } |
| 1534 | |
| 1535 | static inline void inc_chains(void) |
| 1536 | { |
| 1537 | nr_process_chains++; |
| 1538 | } |
| 1539 | |
| 1540 | #endif |
| 1541 | |
| 1542 | static int |
| 1543 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, |
| 1544 | struct held_lock *next) |
| 1545 | { |
| 1546 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
| 1547 | return 0; |
| 1548 | |
| 1549 | printk("\n=============================================\n"); |
| 1550 | printk( "[ INFO: possible recursive locking detected ]\n"); |
| 1551 | print_kernel_version(); |
| 1552 | printk( "---------------------------------------------\n"); |
| 1553 | printk("%s/%d is trying to acquire lock:\n", |
| 1554 | curr->comm, task_pid_nr(curr)); |
| 1555 | print_lock(next); |
| 1556 | printk("\nbut task is already holding lock:\n"); |
| 1557 | print_lock(prev); |
| 1558 | |
| 1559 | printk("\nother info that might help us debug this:\n"); |
| 1560 | lockdep_print_held_locks(curr); |
| 1561 | |
| 1562 | printk("\nstack backtrace:\n"); |
| 1563 | dump_stack(); |
| 1564 | |
| 1565 | return 0; |
| 1566 | } |
| 1567 | |
| 1568 | /* |
| 1569 | * Check whether we are holding such a class already. |
| 1570 | * |
| 1571 | * (Note that this has to be done separately, because the graph cannot |
| 1572 | * detect such classes of deadlocks.) |
| 1573 | * |
| 1574 | * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read |
| 1575 | */ |
| 1576 | static int |
| 1577 | check_deadlock(struct task_struct *curr, struct held_lock *next, |
| 1578 | struct lockdep_map *next_instance, int read) |
| 1579 | { |
| 1580 | struct held_lock *prev; |
| 1581 | struct held_lock *nest = NULL; |
| 1582 | int i; |
| 1583 | |
| 1584 | for (i = 0; i < curr->lockdep_depth; i++) { |
| 1585 | prev = curr->held_locks + i; |
| 1586 | |
| 1587 | if (prev->instance == next->nest_lock) |
| 1588 | nest = prev; |
| 1589 | |
| 1590 | if (hlock_class(prev) != hlock_class(next)) |
| 1591 | continue; |
| 1592 | |
| 1593 | /* |
| 1594 | * Allow read-after-read recursion of the same |
| 1595 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
| 1596 | */ |
| 1597 | if ((read == 2) && prev->read) |
| 1598 | return 2; |
| 1599 | |
| 1600 | /* |
| 1601 | * We're holding the nest_lock, which serializes this lock's |
| 1602 | * nesting behaviour. |
| 1603 | */ |
| 1604 | if (nest) |
| 1605 | return 2; |
| 1606 | |
| 1607 | return print_deadlock_bug(curr, prev, next); |
| 1608 | } |
| 1609 | return 1; |
| 1610 | } |
| 1611 | |
| 1612 | /* |
| 1613 | * There was a chain-cache miss, and we are about to add a new dependency |
| 1614 | * to a previous lock. We recursively validate the following rules: |
| 1615 | * |
| 1616 | * - would the adding of the <prev> -> <next> dependency create a |
| 1617 | * circular dependency in the graph? [== circular deadlock] |
| 1618 | * |
| 1619 | * - does the new prev->next dependency connect any hardirq-safe lock |
| 1620 | * (in the full backwards-subgraph starting at <prev>) with any |
| 1621 | * hardirq-unsafe lock (in the full forwards-subgraph starting at |
| 1622 | * <next>)? [== illegal lock inversion with hardirq contexts] |
| 1623 | * |
| 1624 | * - does the new prev->next dependency connect any softirq-safe lock |
| 1625 | * (in the full backwards-subgraph starting at <prev>) with any |
| 1626 | * softirq-unsafe lock (in the full forwards-subgraph starting at |
| 1627 | * <next>)? [== illegal lock inversion with softirq contexts] |
| 1628 | * |
| 1629 | * any of these scenarios could lead to a deadlock. |
| 1630 | * |
| 1631 | * Then if all the validations pass, we add the forwards and backwards |
| 1632 | * dependency. |
| 1633 | */ |
| 1634 | static int |
| 1635 | check_prev_add(struct task_struct *curr, struct held_lock *prev, |
| 1636 | struct held_lock *next, int distance, int trylock_loop) |
| 1637 | { |
| 1638 | struct lock_list *entry; |
| 1639 | int ret; |
| 1640 | struct lock_list this; |
| 1641 | struct lock_list *uninitialized_var(target_entry); |
| 1642 | /* |
| 1643 | * Static variable, serialized by the graph_lock(). |
| 1644 | * |
| 1645 | * We use this static variable to save the stack trace in case |
| 1646 | * we call into this function multiple times due to encountering |
| 1647 | * trylocks in the held lock stack. |
| 1648 | */ |
| 1649 | static struct stack_trace trace; |
| 1650 | |
| 1651 | /* |
| 1652 | * Prove that the new <prev> -> <next> dependency would not |
| 1653 | * create a circular dependency in the graph. (We do this by |
| 1654 | * forward-recursing into the graph starting at <next>, and |
| 1655 | * checking whether we can reach <prev>.) |
| 1656 | * |
| 1657 | * We are using global variables to control the recursion, to |
| 1658 | * keep the stackframe size of the recursive functions low: |
| 1659 | */ |
| 1660 | this.class = hlock_class(next); |
| 1661 | this.parent = NULL; |
| 1662 | ret = check_noncircular(&this, hlock_class(prev), &target_entry); |
| 1663 | if (unlikely(!ret)) |
| 1664 | return print_circular_bug(&this, target_entry, next, prev); |
| 1665 | else if (unlikely(ret < 0)) |
| 1666 | return print_bfs_bug(ret); |
| 1667 | |
| 1668 | if (!check_prev_add_irq(curr, prev, next)) |
| 1669 | return 0; |
| 1670 | |
| 1671 | /* |
| 1672 | * For recursive read-locks we do all the dependency checks, |
| 1673 | * but we dont store read-triggered dependencies (only |
| 1674 | * write-triggered dependencies). This ensures that only the |
| 1675 | * write-side dependencies matter, and that if for example a |
| 1676 | * write-lock never takes any other locks, then the reads are |
| 1677 | * equivalent to a NOP. |
| 1678 | */ |
| 1679 | if (next->read == 2 || prev->read == 2) |
| 1680 | return 1; |
| 1681 | /* |
| 1682 | * Is the <prev> -> <next> dependency already present? |
| 1683 | * |
| 1684 | * (this may occur even though this is a new chain: consider |
| 1685 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 |
| 1686 | * chains - the second one will be new, but L1 already has |
| 1687 | * L2 added to its dependency list, due to the first chain.) |
| 1688 | */ |
| 1689 | list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { |
| 1690 | if (entry->class == hlock_class(next)) { |
| 1691 | if (distance == 1) |
| 1692 | entry->distance = 1; |
| 1693 | return 2; |
| 1694 | } |
| 1695 | } |
| 1696 | |
| 1697 | if (!trylock_loop && !save_trace(&trace)) |
| 1698 | return 0; |
| 1699 | |
| 1700 | /* |
| 1701 | * Ok, all validations passed, add the new lock |
| 1702 | * to the previous lock's dependency list: |
| 1703 | */ |
| 1704 | ret = add_lock_to_list(hlock_class(prev), hlock_class(next), |
| 1705 | &hlock_class(prev)->locks_after, |
| 1706 | next->acquire_ip, distance, &trace); |
| 1707 | |
| 1708 | if (!ret) |
| 1709 | return 0; |
| 1710 | |
| 1711 | ret = add_lock_to_list(hlock_class(next), hlock_class(prev), |
| 1712 | &hlock_class(next)->locks_before, |
| 1713 | next->acquire_ip, distance, &trace); |
| 1714 | if (!ret) |
| 1715 | return 0; |
| 1716 | |
| 1717 | /* |
| 1718 | * Debugging printouts: |
| 1719 | */ |
| 1720 | if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) { |
| 1721 | graph_unlock(); |
| 1722 | printk("\n new dependency: "); |
| 1723 | print_lock_name(hlock_class(prev)); |
| 1724 | printk(" => "); |
| 1725 | print_lock_name(hlock_class(next)); |
| 1726 | printk("\n"); |
| 1727 | dump_stack(); |
| 1728 | return graph_lock(); |
| 1729 | } |
| 1730 | return 1; |
| 1731 | } |
| 1732 | |
| 1733 | /* |
| 1734 | * Add the dependency to all directly-previous locks that are 'relevant'. |
| 1735 | * The ones that are relevant are (in increasing distance from curr): |
| 1736 | * all consecutive trylock entries and the final non-trylock entry - or |
| 1737 | * the end of this context's lock-chain - whichever comes first. |
| 1738 | */ |
| 1739 | static int |
| 1740 | check_prevs_add(struct task_struct *curr, struct held_lock *next) |
| 1741 | { |
| 1742 | int depth = curr->lockdep_depth; |
| 1743 | int trylock_loop = 0; |
| 1744 | struct held_lock *hlock; |
| 1745 | |
| 1746 | /* |
| 1747 | * Debugging checks. |
| 1748 | * |
| 1749 | * Depth must not be zero for a non-head lock: |
| 1750 | */ |
| 1751 | if (!depth) |
| 1752 | goto out_bug; |
| 1753 | /* |
| 1754 | * At least two relevant locks must exist for this |
| 1755 | * to be a head: |
| 1756 | */ |
| 1757 | if (curr->held_locks[depth].irq_context != |
| 1758 | curr->held_locks[depth-1].irq_context) |
| 1759 | goto out_bug; |
| 1760 | |
| 1761 | for (;;) { |
| 1762 | int distance = curr->lockdep_depth - depth + 1; |
| 1763 | hlock = curr->held_locks + depth-1; |
| 1764 | /* |
| 1765 | * Only non-recursive-read entries get new dependencies |
| 1766 | * added: |
| 1767 | */ |
| 1768 | if (hlock->read != 2) { |
| 1769 | if (!check_prev_add(curr, hlock, next, |
| 1770 | distance, trylock_loop)) |
| 1771 | return 0; |
| 1772 | /* |
| 1773 | * Stop after the first non-trylock entry, |
| 1774 | * as non-trylock entries have added their |
| 1775 | * own direct dependencies already, so this |
| 1776 | * lock is connected to them indirectly: |
| 1777 | */ |
| 1778 | if (!hlock->trylock) |
| 1779 | break; |
| 1780 | } |
| 1781 | depth--; |
| 1782 | /* |
| 1783 | * End of lock-stack? |
| 1784 | */ |
| 1785 | if (!depth) |
| 1786 | break; |
| 1787 | /* |
| 1788 | * Stop the search if we cross into another context: |
| 1789 | */ |
| 1790 | if (curr->held_locks[depth].irq_context != |
| 1791 | curr->held_locks[depth-1].irq_context) |
| 1792 | break; |
| 1793 | trylock_loop = 1; |
| 1794 | } |
| 1795 | return 1; |
| 1796 | out_bug: |
| 1797 | if (!debug_locks_off_graph_unlock()) |
| 1798 | return 0; |
| 1799 | |
| 1800 | WARN_ON(1); |
| 1801 | |
| 1802 | return 0; |
| 1803 | } |
| 1804 | |
| 1805 | unsigned long nr_lock_chains; |
| 1806 | struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; |
| 1807 | int nr_chain_hlocks; |
| 1808 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; |
| 1809 | |
| 1810 | struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) |
| 1811 | { |
| 1812 | return lock_classes + chain_hlocks[chain->base + i]; |
| 1813 | } |
| 1814 | |
| 1815 | /* |
| 1816 | * Look up a dependency chain. If the key is not present yet then |
| 1817 | * add it and return 1 - in this case the new dependency chain is |
| 1818 | * validated. If the key is already hashed, return 0. |
| 1819 | * (On return with 1 graph_lock is held.) |
| 1820 | */ |
| 1821 | static inline int lookup_chain_cache(struct task_struct *curr, |
| 1822 | struct held_lock *hlock, |
| 1823 | u64 chain_key) |
| 1824 | { |
| 1825 | struct lock_class *class = hlock_class(hlock); |
| 1826 | struct list_head *hash_head = chainhashentry(chain_key); |
| 1827 | struct lock_chain *chain; |
| 1828 | struct held_lock *hlock_curr, *hlock_next; |
| 1829 | int i, j, n, cn; |
| 1830 | |
| 1831 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| 1832 | return 0; |
| 1833 | /* |
| 1834 | * We can walk it lock-free, because entries only get added |
| 1835 | * to the hash: |
| 1836 | */ |
| 1837 | list_for_each_entry(chain, hash_head, entry) { |
| 1838 | if (chain->chain_key == chain_key) { |
| 1839 | cache_hit: |
| 1840 | debug_atomic_inc(chain_lookup_hits); |
| 1841 | if (very_verbose(class)) |
| 1842 | printk("\nhash chain already cached, key: " |
| 1843 | "%016Lx tail class: [%p] %s\n", |
| 1844 | (unsigned long long)chain_key, |
| 1845 | class->key, class->name); |
| 1846 | return 0; |
| 1847 | } |
| 1848 | } |
| 1849 | if (very_verbose(class)) |
| 1850 | printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", |
| 1851 | (unsigned long long)chain_key, class->key, class->name); |
| 1852 | /* |
| 1853 | * Allocate a new chain entry from the static array, and add |
| 1854 | * it to the hash: |
| 1855 | */ |
| 1856 | if (!graph_lock()) |
| 1857 | return 0; |
| 1858 | /* |
| 1859 | * We have to walk the chain again locked - to avoid duplicates: |
| 1860 | */ |
| 1861 | list_for_each_entry(chain, hash_head, entry) { |
| 1862 | if (chain->chain_key == chain_key) { |
| 1863 | graph_unlock(); |
| 1864 | goto cache_hit; |
| 1865 | } |
| 1866 | } |
| 1867 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { |
| 1868 | if (!debug_locks_off_graph_unlock()) |
| 1869 | return 0; |
| 1870 | |
| 1871 | printk("BUG: MAX_LOCKDEP_CHAINS too low!\n"); |
| 1872 | printk("turning off the locking correctness validator.\n"); |
| 1873 | dump_stack(); |
| 1874 | return 0; |
| 1875 | } |
| 1876 | chain = lock_chains + nr_lock_chains++; |
| 1877 | chain->chain_key = chain_key; |
| 1878 | chain->irq_context = hlock->irq_context; |
| 1879 | /* Find the first held_lock of current chain */ |
| 1880 | hlock_next = hlock; |
| 1881 | for (i = curr->lockdep_depth - 1; i >= 0; i--) { |
| 1882 | hlock_curr = curr->held_locks + i; |
| 1883 | if (hlock_curr->irq_context != hlock_next->irq_context) |
| 1884 | break; |
| 1885 | hlock_next = hlock; |
| 1886 | } |
| 1887 | i++; |
| 1888 | chain->depth = curr->lockdep_depth + 1 - i; |
| 1889 | cn = nr_chain_hlocks; |
| 1890 | while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) { |
| 1891 | n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth); |
| 1892 | if (n == cn) |
| 1893 | break; |
| 1894 | cn = n; |
| 1895 | } |
| 1896 | if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { |
| 1897 | chain->base = cn; |
| 1898 | for (j = 0; j < chain->depth - 1; j++, i++) { |
| 1899 | int lock_id = curr->held_locks[i].class_idx - 1; |
| 1900 | chain_hlocks[chain->base + j] = lock_id; |
| 1901 | } |
| 1902 | chain_hlocks[chain->base + j] = class - lock_classes; |
| 1903 | } |
| 1904 | list_add_tail_rcu(&chain->entry, hash_head); |
| 1905 | debug_atomic_inc(chain_lookup_misses); |
| 1906 | inc_chains(); |
| 1907 | |
| 1908 | return 1; |
| 1909 | } |
| 1910 | |
| 1911 | static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, |
| 1912 | struct held_lock *hlock, int chain_head, u64 chain_key) |
| 1913 | { |
| 1914 | /* |
| 1915 | * Trylock needs to maintain the stack of held locks, but it |
| 1916 | * does not add new dependencies, because trylock can be done |
| 1917 | * in any order. |
| 1918 | * |
| 1919 | * We look up the chain_key and do the O(N^2) check and update of |
| 1920 | * the dependencies only if this is a new dependency chain. |
| 1921 | * (If lookup_chain_cache() returns with 1 it acquires |
| 1922 | * graph_lock for us) |
| 1923 | */ |
| 1924 | if (!hlock->trylock && (hlock->check == 2) && |
| 1925 | lookup_chain_cache(curr, hlock, chain_key)) { |
| 1926 | /* |
| 1927 | * Check whether last held lock: |
| 1928 | * |
| 1929 | * - is irq-safe, if this lock is irq-unsafe |
| 1930 | * - is softirq-safe, if this lock is hardirq-unsafe |
| 1931 | * |
| 1932 | * And check whether the new lock's dependency graph |
| 1933 | * could lead back to the previous lock. |
| 1934 | * |
| 1935 | * any of these scenarios could lead to a deadlock. If |
| 1936 | * All validations |
| 1937 | */ |
| 1938 | int ret = check_deadlock(curr, hlock, lock, hlock->read); |
| 1939 | |
| 1940 | if (!ret) |
| 1941 | return 0; |
| 1942 | /* |
| 1943 | * Mark recursive read, as we jump over it when |
| 1944 | * building dependencies (just like we jump over |
| 1945 | * trylock entries): |
| 1946 | */ |
| 1947 | if (ret == 2) |
| 1948 | hlock->read = 2; |
| 1949 | /* |
| 1950 | * Add dependency only if this lock is not the head |
| 1951 | * of the chain, and if it's not a secondary read-lock: |
| 1952 | */ |
| 1953 | if (!chain_head && ret != 2) |
| 1954 | if (!check_prevs_add(curr, hlock)) |
| 1955 | return 0; |
| 1956 | graph_unlock(); |
| 1957 | } else |
| 1958 | /* after lookup_chain_cache(): */ |
| 1959 | if (unlikely(!debug_locks)) |
| 1960 | return 0; |
| 1961 | |
| 1962 | return 1; |
| 1963 | } |
| 1964 | #else |
| 1965 | static inline int validate_chain(struct task_struct *curr, |
| 1966 | struct lockdep_map *lock, struct held_lock *hlock, |
| 1967 | int chain_head, u64 chain_key) |
| 1968 | { |
| 1969 | return 1; |
| 1970 | } |
| 1971 | #endif |
| 1972 | |
| 1973 | /* |
| 1974 | * We are building curr_chain_key incrementally, so double-check |
| 1975 | * it from scratch, to make sure that it's done correctly: |
| 1976 | */ |
| 1977 | static void check_chain_key(struct task_struct *curr) |
| 1978 | { |
| 1979 | #ifdef CONFIG_DEBUG_LOCKDEP |
| 1980 | struct held_lock *hlock, *prev_hlock = NULL; |
| 1981 | unsigned int i, id; |
| 1982 | u64 chain_key = 0; |
| 1983 | |
| 1984 | for (i = 0; i < curr->lockdep_depth; i++) { |
| 1985 | hlock = curr->held_locks + i; |
| 1986 | if (chain_key != hlock->prev_chain_key) { |
| 1987 | debug_locks_off(); |
| 1988 | WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", |
| 1989 | curr->lockdep_depth, i, |
| 1990 | (unsigned long long)chain_key, |
| 1991 | (unsigned long long)hlock->prev_chain_key); |
| 1992 | return; |
| 1993 | } |
| 1994 | id = hlock->class_idx - 1; |
| 1995 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) |
| 1996 | return; |
| 1997 | |
| 1998 | if (prev_hlock && (prev_hlock->irq_context != |
| 1999 | hlock->irq_context)) |
| 2000 | chain_key = 0; |
| 2001 | chain_key = iterate_chain_key(chain_key, id); |
| 2002 | prev_hlock = hlock; |
| 2003 | } |
| 2004 | if (chain_key != curr->curr_chain_key) { |
| 2005 | debug_locks_off(); |
| 2006 | WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", |
| 2007 | curr->lockdep_depth, i, |
| 2008 | (unsigned long long)chain_key, |
| 2009 | (unsigned long long)curr->curr_chain_key); |
| 2010 | } |
| 2011 | #endif |
| 2012 | } |
| 2013 | |
| 2014 | static int |
| 2015 | print_usage_bug(struct task_struct *curr, struct held_lock *this, |
| 2016 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) |
| 2017 | { |
| 2018 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
| 2019 | return 0; |
| 2020 | |
| 2021 | printk("\n=================================\n"); |
| 2022 | printk( "[ INFO: inconsistent lock state ]\n"); |
| 2023 | print_kernel_version(); |
| 2024 | printk( "---------------------------------\n"); |
| 2025 | |
| 2026 | printk("inconsistent {%s} -> {%s} usage.\n", |
| 2027 | usage_str[prev_bit], usage_str[new_bit]); |
| 2028 | |
| 2029 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", |
| 2030 | curr->comm, task_pid_nr(curr), |
| 2031 | trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, |
| 2032 | trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, |
| 2033 | trace_hardirqs_enabled(curr), |
| 2034 | trace_softirqs_enabled(curr)); |
| 2035 | print_lock(this); |
| 2036 | |
| 2037 | printk("{%s} state was registered at:\n", usage_str[prev_bit]); |
| 2038 | print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1); |
| 2039 | |
| 2040 | print_irqtrace_events(curr); |
| 2041 | printk("\nother info that might help us debug this:\n"); |
| 2042 | lockdep_print_held_locks(curr); |
| 2043 | |
| 2044 | printk("\nstack backtrace:\n"); |
| 2045 | dump_stack(); |
| 2046 | |
| 2047 | return 0; |
| 2048 | } |
| 2049 | |
| 2050 | /* |
| 2051 | * Print out an error if an invalid bit is set: |
| 2052 | */ |
| 2053 | static inline int |
| 2054 | valid_state(struct task_struct *curr, struct held_lock *this, |
| 2055 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) |
| 2056 | { |
| 2057 | if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) |
| 2058 | return print_usage_bug(curr, this, bad_bit, new_bit); |
| 2059 | return 1; |
| 2060 | } |
| 2061 | |
| 2062 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
| 2063 | enum lock_usage_bit new_bit); |
| 2064 | |
| 2065 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
| 2066 | |
| 2067 | /* |
| 2068 | * print irq inversion bug: |
| 2069 | */ |
| 2070 | static int |
| 2071 | print_irq_inversion_bug(struct task_struct *curr, |
| 2072 | struct lock_list *root, struct lock_list *other, |
| 2073 | struct held_lock *this, int forwards, |
| 2074 | const char *irqclass) |
| 2075 | { |
| 2076 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
| 2077 | return 0; |
| 2078 | |
| 2079 | printk("\n=========================================================\n"); |
| 2080 | printk( "[ INFO: possible irq lock inversion dependency detected ]\n"); |
| 2081 | print_kernel_version(); |
| 2082 | printk( "---------------------------------------------------------\n"); |
| 2083 | printk("%s/%d just changed the state of lock:\n", |
| 2084 | curr->comm, task_pid_nr(curr)); |
| 2085 | print_lock(this); |
| 2086 | if (forwards) |
| 2087 | printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass); |
| 2088 | else |
| 2089 | printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); |
| 2090 | print_lock_name(other->class); |
| 2091 | printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); |
| 2092 | |
| 2093 | printk("\nother info that might help us debug this:\n"); |
| 2094 | lockdep_print_held_locks(curr); |
| 2095 | |
| 2096 | printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); |
| 2097 | if (!save_trace(&root->trace)) |
| 2098 | return 0; |
| 2099 | print_shortest_lock_dependencies(other, root); |
| 2100 | |
| 2101 | printk("\nstack backtrace:\n"); |
| 2102 | dump_stack(); |
| 2103 | |
| 2104 | return 0; |
| 2105 | } |
| 2106 | |
| 2107 | /* |
| 2108 | * Prove that in the forwards-direction subgraph starting at <this> |
| 2109 | * there is no lock matching <mask>: |
| 2110 | */ |
| 2111 | static int |
| 2112 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, |
| 2113 | enum lock_usage_bit bit, const char *irqclass) |
| 2114 | { |
| 2115 | int ret; |
| 2116 | struct lock_list root; |
| 2117 | struct lock_list *uninitialized_var(target_entry); |
| 2118 | |
| 2119 | root.parent = NULL; |
| 2120 | root.class = hlock_class(this); |
| 2121 | ret = find_usage_forwards(&root, bit, &target_entry); |
| 2122 | if (ret < 0) |
| 2123 | return print_bfs_bug(ret); |
| 2124 | if (ret == 1) |
| 2125 | return ret; |
| 2126 | |
| 2127 | return print_irq_inversion_bug(curr, &root, target_entry, |
| 2128 | this, 1, irqclass); |
| 2129 | } |
| 2130 | |
| 2131 | /* |
| 2132 | * Prove that in the backwards-direction subgraph starting at <this> |
| 2133 | * there is no lock matching <mask>: |
| 2134 | */ |
| 2135 | static int |
| 2136 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, |
| 2137 | enum lock_usage_bit bit, const char *irqclass) |
| 2138 | { |
| 2139 | int ret; |
| 2140 | struct lock_list root; |
| 2141 | struct lock_list *uninitialized_var(target_entry); |
| 2142 | |
| 2143 | root.parent = NULL; |
| 2144 | root.class = hlock_class(this); |
| 2145 | ret = find_usage_backwards(&root, bit, &target_entry); |
| 2146 | if (ret < 0) |
| 2147 | return print_bfs_bug(ret); |
| 2148 | if (ret == 1) |
| 2149 | return ret; |
| 2150 | |
| 2151 | return print_irq_inversion_bug(curr, &root, target_entry, |
| 2152 | this, 0, irqclass); |
| 2153 | } |
| 2154 | |
| 2155 | void print_irqtrace_events(struct task_struct *curr) |
| 2156 | { |
| 2157 | printk("irq event stamp: %u\n", curr->irq_events); |
| 2158 | printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event); |
| 2159 | print_ip_sym(curr->hardirq_enable_ip); |
| 2160 | printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event); |
| 2161 | print_ip_sym(curr->hardirq_disable_ip); |
| 2162 | printk("softirqs last enabled at (%u): ", curr->softirq_enable_event); |
| 2163 | print_ip_sym(curr->softirq_enable_ip); |
| 2164 | printk("softirqs last disabled at (%u): ", curr->softirq_disable_event); |
| 2165 | print_ip_sym(curr->softirq_disable_ip); |
| 2166 | } |
| 2167 | |
| 2168 | static int HARDIRQ_verbose(struct lock_class *class) |
| 2169 | { |
| 2170 | #if HARDIRQ_VERBOSE |
| 2171 | return class_filter(class); |
| 2172 | #endif |
| 2173 | return 0; |
| 2174 | } |
| 2175 | |
| 2176 | static int SOFTIRQ_verbose(struct lock_class *class) |
| 2177 | { |
| 2178 | #if SOFTIRQ_VERBOSE |
| 2179 | return class_filter(class); |
| 2180 | #endif |
| 2181 | return 0; |
| 2182 | } |
| 2183 | |
| 2184 | static int RECLAIM_FS_verbose(struct lock_class *class) |
| 2185 | { |
| 2186 | #if RECLAIM_VERBOSE |
| 2187 | return class_filter(class); |
| 2188 | #endif |
| 2189 | return 0; |
| 2190 | } |
| 2191 | |
| 2192 | #define STRICT_READ_CHECKS 1 |
| 2193 | |
| 2194 | static int (*state_verbose_f[])(struct lock_class *class) = { |
| 2195 | #define LOCKDEP_STATE(__STATE) \ |
| 2196 | __STATE##_verbose, |
| 2197 | #include "lockdep_states.h" |
| 2198 | #undef LOCKDEP_STATE |
| 2199 | }; |
| 2200 | |
| 2201 | static inline int state_verbose(enum lock_usage_bit bit, |
| 2202 | struct lock_class *class) |
| 2203 | { |
| 2204 | return state_verbose_f[bit >> 2](class); |
| 2205 | } |
| 2206 | |
| 2207 | typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, |
| 2208 | enum lock_usage_bit bit, const char *name); |
| 2209 | |
| 2210 | static int |
| 2211 | mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
| 2212 | enum lock_usage_bit new_bit) |
| 2213 | { |
| 2214 | int excl_bit = exclusive_bit(new_bit); |
| 2215 | int read = new_bit & 1; |
| 2216 | int dir = new_bit & 2; |
| 2217 | |
| 2218 | /* |
| 2219 | * mark USED_IN has to look forwards -- to ensure no dependency |
| 2220 | * has ENABLED state, which would allow recursion deadlocks. |
| 2221 | * |
| 2222 | * mark ENABLED has to look backwards -- to ensure no dependee |
| 2223 | * has USED_IN state, which, again, would allow recursion deadlocks. |
| 2224 | */ |
| 2225 | check_usage_f usage = dir ? |
| 2226 | check_usage_backwards : check_usage_forwards; |
| 2227 | |
| 2228 | /* |
| 2229 | * Validate that this particular lock does not have conflicting |
| 2230 | * usage states. |
| 2231 | */ |
| 2232 | if (!valid_state(curr, this, new_bit, excl_bit)) |
| 2233 | return 0; |
| 2234 | |
| 2235 | /* |
| 2236 | * Validate that the lock dependencies don't have conflicting usage |
| 2237 | * states. |
| 2238 | */ |
| 2239 | if ((!read || !dir || STRICT_READ_CHECKS) && |
| 2240 | !usage(curr, this, excl_bit, state_name(new_bit & ~1))) |
| 2241 | return 0; |
| 2242 | |
| 2243 | /* |
| 2244 | * Check for read in write conflicts |
| 2245 | */ |
| 2246 | if (!read) { |
| 2247 | if (!valid_state(curr, this, new_bit, excl_bit + 1)) |
| 2248 | return 0; |
| 2249 | |
| 2250 | if (STRICT_READ_CHECKS && |
| 2251 | !usage(curr, this, excl_bit + 1, |
| 2252 | state_name(new_bit + 1))) |
| 2253 | return 0; |
| 2254 | } |
| 2255 | |
| 2256 | if (state_verbose(new_bit, hlock_class(this))) |
| 2257 | return 2; |
| 2258 | |
| 2259 | return 1; |
| 2260 | } |
| 2261 | |
| 2262 | enum mark_type { |
| 2263 | #define LOCKDEP_STATE(__STATE) __STATE, |
| 2264 | #include "lockdep_states.h" |
| 2265 | #undef LOCKDEP_STATE |
| 2266 | }; |
| 2267 | |
| 2268 | /* |
| 2269 | * Mark all held locks with a usage bit: |
| 2270 | */ |
| 2271 | static int |
| 2272 | mark_held_locks(struct task_struct *curr, enum mark_type mark) |
| 2273 | { |
| 2274 | enum lock_usage_bit usage_bit; |
| 2275 | struct held_lock *hlock; |
| 2276 | int i; |
| 2277 | |
| 2278 | for (i = 0; i < curr->lockdep_depth; i++) { |
| 2279 | hlock = curr->held_locks + i; |
| 2280 | |
| 2281 | usage_bit = 2 + (mark << 2); /* ENABLED */ |
| 2282 | if (hlock->read) |
| 2283 | usage_bit += 1; /* READ */ |
| 2284 | |
| 2285 | BUG_ON(usage_bit >= LOCK_USAGE_STATES); |
| 2286 | |
| 2287 | if (!mark_lock(curr, hlock, usage_bit)) |
| 2288 | return 0; |
| 2289 | } |
| 2290 | |
| 2291 | return 1; |
| 2292 | } |
| 2293 | |
| 2294 | /* |
| 2295 | * Hardirqs will be enabled: |
| 2296 | */ |
| 2297 | void trace_hardirqs_on_caller(unsigned long ip) |
| 2298 | { |
| 2299 | struct task_struct *curr = current; |
| 2300 | |
| 2301 | time_hardirqs_on(CALLER_ADDR0, ip); |
| 2302 | |
| 2303 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
| 2304 | return; |
| 2305 | |
| 2306 | if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) |
| 2307 | return; |
| 2308 | |
| 2309 | if (unlikely(curr->hardirqs_enabled)) { |
| 2310 | /* |
| 2311 | * Neither irq nor preemption are disabled here |
| 2312 | * so this is racy by nature but loosing one hit |
| 2313 | * in a stat is not a big deal. |
| 2314 | */ |
| 2315 | __debug_atomic_inc(redundant_hardirqs_on); |
| 2316 | return; |
| 2317 | } |
| 2318 | /* we'll do an OFF -> ON transition: */ |
| 2319 | curr->hardirqs_enabled = 1; |
| 2320 | |
| 2321 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| 2322 | return; |
| 2323 | if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) |
| 2324 | return; |
| 2325 | /* |
| 2326 | * We are going to turn hardirqs on, so set the |
| 2327 | * usage bit for all held locks: |
| 2328 | */ |
| 2329 | if (!mark_held_locks(curr, HARDIRQ)) |
| 2330 | return; |
| 2331 | /* |
| 2332 | * If we have softirqs enabled, then set the usage |
| 2333 | * bit for all held locks. (disabled hardirqs prevented |
| 2334 | * this bit from being set before) |
| 2335 | */ |
| 2336 | if (curr->softirqs_enabled) |
| 2337 | if (!mark_held_locks(curr, SOFTIRQ)) |
| 2338 | return; |
| 2339 | |
| 2340 | curr->hardirq_enable_ip = ip; |
| 2341 | curr->hardirq_enable_event = ++curr->irq_events; |
| 2342 | debug_atomic_inc(hardirqs_on_events); |
| 2343 | } |
| 2344 | EXPORT_SYMBOL(trace_hardirqs_on_caller); |
| 2345 | |
| 2346 | void trace_hardirqs_on(void) |
| 2347 | { |
| 2348 | trace_hardirqs_on_caller(CALLER_ADDR0); |
| 2349 | } |
| 2350 | EXPORT_SYMBOL(trace_hardirqs_on); |
| 2351 | |
| 2352 | /* |
| 2353 | * Hardirqs were disabled: |
| 2354 | */ |
| 2355 | void trace_hardirqs_off_caller(unsigned long ip) |
| 2356 | { |
| 2357 | struct task_struct *curr = current; |
| 2358 | |
| 2359 | time_hardirqs_off(CALLER_ADDR0, ip); |
| 2360 | |
| 2361 | if (unlikely(!debug_locks || current->lockdep_recursion)) |
| 2362 | return; |
| 2363 | |
| 2364 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| 2365 | return; |
| 2366 | |
| 2367 | if (curr->hardirqs_enabled) { |
| 2368 | /* |
| 2369 | * We have done an ON -> OFF transition: |
| 2370 | */ |
| 2371 | curr->hardirqs_enabled = 0; |
| 2372 | curr->hardirq_disable_ip = ip; |
| 2373 | curr->hardirq_disable_event = ++curr->irq_events; |
| 2374 | debug_atomic_inc(hardirqs_off_events); |
| 2375 | } else |
| 2376 | debug_atomic_inc(redundant_hardirqs_off); |
| 2377 | } |
| 2378 | EXPORT_SYMBOL(trace_hardirqs_off_caller); |
| 2379 | |
| 2380 | void trace_hardirqs_off(void) |
| 2381 | { |
| 2382 | trace_hardirqs_off_caller(CALLER_ADDR0); |
| 2383 | } |
| 2384 | EXPORT_SYMBOL(trace_hardirqs_off); |
| 2385 | |
| 2386 | /* |
| 2387 | * Softirqs will be enabled: |
| 2388 | */ |
| 2389 | void trace_softirqs_on(unsigned long ip) |
| 2390 | { |
| 2391 | struct task_struct *curr = current; |
| 2392 | |
| 2393 | if (unlikely(!debug_locks)) |
| 2394 | return; |
| 2395 | |
| 2396 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| 2397 | return; |
| 2398 | |
| 2399 | if (curr->softirqs_enabled) { |
| 2400 | debug_atomic_inc(redundant_softirqs_on); |
| 2401 | return; |
| 2402 | } |
| 2403 | |
| 2404 | /* |
| 2405 | * We'll do an OFF -> ON transition: |
| 2406 | */ |
| 2407 | curr->softirqs_enabled = 1; |
| 2408 | curr->softirq_enable_ip = ip; |
| 2409 | curr->softirq_enable_event = ++curr->irq_events; |
| 2410 | debug_atomic_inc(softirqs_on_events); |
| 2411 | /* |
| 2412 | * We are going to turn softirqs on, so set the |
| 2413 | * usage bit for all held locks, if hardirqs are |
| 2414 | * enabled too: |
| 2415 | */ |
| 2416 | if (curr->hardirqs_enabled) |
| 2417 | mark_held_locks(curr, SOFTIRQ); |
| 2418 | } |
| 2419 | |
| 2420 | /* |
| 2421 | * Softirqs were disabled: |
| 2422 | */ |
| 2423 | void trace_softirqs_off(unsigned long ip) |
| 2424 | { |
| 2425 | struct task_struct *curr = current; |
| 2426 | |
| 2427 | if (unlikely(!debug_locks)) |
| 2428 | return; |
| 2429 | |
| 2430 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| 2431 | return; |
| 2432 | |
| 2433 | if (curr->softirqs_enabled) { |
| 2434 | /* |
| 2435 | * We have done an ON -> OFF transition: |
| 2436 | */ |
| 2437 | curr->softirqs_enabled = 0; |
| 2438 | curr->softirq_disable_ip = ip; |
| 2439 | curr->softirq_disable_event = ++curr->irq_events; |
| 2440 | debug_atomic_inc(softirqs_off_events); |
| 2441 | DEBUG_LOCKS_WARN_ON(!softirq_count()); |
| 2442 | } else |
| 2443 | debug_atomic_inc(redundant_softirqs_off); |
| 2444 | } |
| 2445 | |
| 2446 | static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags) |
| 2447 | { |
| 2448 | struct task_struct *curr = current; |
| 2449 | |
| 2450 | if (unlikely(!debug_locks)) |
| 2451 | return; |
| 2452 | |
| 2453 | /* no reclaim without waiting on it */ |
| 2454 | if (!(gfp_mask & __GFP_WAIT)) |
| 2455 | return; |
| 2456 | |
| 2457 | /* this guy won't enter reclaim */ |
| 2458 | if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC)) |
| 2459 | return; |
| 2460 | |
| 2461 | /* We're only interested __GFP_FS allocations for now */ |
| 2462 | if (!(gfp_mask & __GFP_FS)) |
| 2463 | return; |
| 2464 | |
| 2465 | if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))) |
| 2466 | return; |
| 2467 | |
| 2468 | mark_held_locks(curr, RECLAIM_FS); |
| 2469 | } |
| 2470 | |
| 2471 | static void check_flags(unsigned long flags); |
| 2472 | |
| 2473 | void lockdep_trace_alloc(gfp_t gfp_mask) |
| 2474 | { |
| 2475 | unsigned long flags; |
| 2476 | |
| 2477 | if (unlikely(current->lockdep_recursion)) |
| 2478 | return; |
| 2479 | |
| 2480 | raw_local_irq_save(flags); |
| 2481 | check_flags(flags); |
| 2482 | current->lockdep_recursion = 1; |
| 2483 | __lockdep_trace_alloc(gfp_mask, flags); |
| 2484 | current->lockdep_recursion = 0; |
| 2485 | raw_local_irq_restore(flags); |
| 2486 | } |
| 2487 | |
| 2488 | static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) |
| 2489 | { |
| 2490 | /* |
| 2491 | * If non-trylock use in a hardirq or softirq context, then |
| 2492 | * mark the lock as used in these contexts: |
| 2493 | */ |
| 2494 | if (!hlock->trylock) { |
| 2495 | if (hlock->read) { |
| 2496 | if (curr->hardirq_context) |
| 2497 | if (!mark_lock(curr, hlock, |
| 2498 | LOCK_USED_IN_HARDIRQ_READ)) |
| 2499 | return 0; |
| 2500 | if (curr->softirq_context) |
| 2501 | if (!mark_lock(curr, hlock, |
| 2502 | LOCK_USED_IN_SOFTIRQ_READ)) |
| 2503 | return 0; |
| 2504 | } else { |
| 2505 | if (curr->hardirq_context) |
| 2506 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) |
| 2507 | return 0; |
| 2508 | if (curr->softirq_context) |
| 2509 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) |
| 2510 | return 0; |
| 2511 | } |
| 2512 | } |
| 2513 | if (!hlock->hardirqs_off) { |
| 2514 | if (hlock->read) { |
| 2515 | if (!mark_lock(curr, hlock, |
| 2516 | LOCK_ENABLED_HARDIRQ_READ)) |
| 2517 | return 0; |
| 2518 | if (curr->softirqs_enabled) |
| 2519 | if (!mark_lock(curr, hlock, |
| 2520 | LOCK_ENABLED_SOFTIRQ_READ)) |
| 2521 | return 0; |
| 2522 | } else { |
| 2523 | if (!mark_lock(curr, hlock, |
| 2524 | LOCK_ENABLED_HARDIRQ)) |
| 2525 | return 0; |
| 2526 | if (curr->softirqs_enabled) |
| 2527 | if (!mark_lock(curr, hlock, |
| 2528 | LOCK_ENABLED_SOFTIRQ)) |
| 2529 | return 0; |
| 2530 | } |
| 2531 | } |
| 2532 | |
| 2533 | /* |
| 2534 | * We reuse the irq context infrastructure more broadly as a general |
| 2535 | * context checking code. This tests GFP_FS recursion (a lock taken |
| 2536 | * during reclaim for a GFP_FS allocation is held over a GFP_FS |
| 2537 | * allocation). |
| 2538 | */ |
| 2539 | if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) { |
| 2540 | if (hlock->read) { |
| 2541 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ)) |
| 2542 | return 0; |
| 2543 | } else { |
| 2544 | if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS)) |
| 2545 | return 0; |
| 2546 | } |
| 2547 | } |
| 2548 | |
| 2549 | return 1; |
| 2550 | } |
| 2551 | |
| 2552 | static int separate_irq_context(struct task_struct *curr, |
| 2553 | struct held_lock *hlock) |
| 2554 | { |
| 2555 | unsigned int depth = curr->lockdep_depth; |
| 2556 | |
| 2557 | /* |
| 2558 | * Keep track of points where we cross into an interrupt context: |
| 2559 | */ |
| 2560 | hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) + |
| 2561 | curr->softirq_context; |
| 2562 | if (depth) { |
| 2563 | struct held_lock *prev_hlock; |
| 2564 | |
| 2565 | prev_hlock = curr->held_locks + depth-1; |
| 2566 | /* |
| 2567 | * If we cross into another context, reset the |
| 2568 | * hash key (this also prevents the checking and the |
| 2569 | * adding of the dependency to 'prev'): |
| 2570 | */ |
| 2571 | if (prev_hlock->irq_context != hlock->irq_context) |
| 2572 | return 1; |
| 2573 | } |
| 2574 | return 0; |
| 2575 | } |
| 2576 | |
| 2577 | #else |
| 2578 | |
| 2579 | static inline |
| 2580 | int mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
| 2581 | enum lock_usage_bit new_bit) |
| 2582 | { |
| 2583 | WARN_ON(1); |
| 2584 | return 1; |
| 2585 | } |
| 2586 | |
| 2587 | static inline int mark_irqflags(struct task_struct *curr, |
| 2588 | struct held_lock *hlock) |
| 2589 | { |
| 2590 | return 1; |
| 2591 | } |
| 2592 | |
| 2593 | static inline int separate_irq_context(struct task_struct *curr, |
| 2594 | struct held_lock *hlock) |
| 2595 | { |
| 2596 | return 0; |
| 2597 | } |
| 2598 | |
| 2599 | void lockdep_trace_alloc(gfp_t gfp_mask) |
| 2600 | { |
| 2601 | } |
| 2602 | |
| 2603 | #endif |
| 2604 | |
| 2605 | /* |
| 2606 | * Mark a lock with a usage bit, and validate the state transition: |
| 2607 | */ |
| 2608 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
| 2609 | enum lock_usage_bit new_bit) |
| 2610 | { |
| 2611 | unsigned int new_mask = 1 << new_bit, ret = 1; |
| 2612 | |
| 2613 | /* |
| 2614 | * If already set then do not dirty the cacheline, |
| 2615 | * nor do any checks: |
| 2616 | */ |
| 2617 | if (likely(hlock_class(this)->usage_mask & new_mask)) |
| 2618 | return 1; |
| 2619 | |
| 2620 | if (!graph_lock()) |
| 2621 | return 0; |
| 2622 | /* |
| 2623 | * Make sure we didnt race: |
| 2624 | */ |
| 2625 | if (unlikely(hlock_class(this)->usage_mask & new_mask)) { |
| 2626 | graph_unlock(); |
| 2627 | return 1; |
| 2628 | } |
| 2629 | |
| 2630 | hlock_class(this)->usage_mask |= new_mask; |
| 2631 | |
| 2632 | if (!save_trace(hlock_class(this)->usage_traces + new_bit)) |
| 2633 | return 0; |
| 2634 | |
| 2635 | switch (new_bit) { |
| 2636 | #define LOCKDEP_STATE(__STATE) \ |
| 2637 | case LOCK_USED_IN_##__STATE: \ |
| 2638 | case LOCK_USED_IN_##__STATE##_READ: \ |
| 2639 | case LOCK_ENABLED_##__STATE: \ |
| 2640 | case LOCK_ENABLED_##__STATE##_READ: |
| 2641 | #include "lockdep_states.h" |
| 2642 | #undef LOCKDEP_STATE |
| 2643 | ret = mark_lock_irq(curr, this, new_bit); |
| 2644 | if (!ret) |
| 2645 | return 0; |
| 2646 | break; |
| 2647 | case LOCK_USED: |
| 2648 | debug_atomic_dec(nr_unused_locks); |
| 2649 | break; |
| 2650 | default: |
| 2651 | if (!debug_locks_off_graph_unlock()) |
| 2652 | return 0; |
| 2653 | WARN_ON(1); |
| 2654 | return 0; |
| 2655 | } |
| 2656 | |
| 2657 | graph_unlock(); |
| 2658 | |
| 2659 | /* |
| 2660 | * We must printk outside of the graph_lock: |
| 2661 | */ |
| 2662 | if (ret == 2) { |
| 2663 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); |
| 2664 | print_lock(this); |
| 2665 | print_irqtrace_events(curr); |
| 2666 | dump_stack(); |
| 2667 | } |
| 2668 | |
| 2669 | return ret; |
| 2670 | } |
| 2671 | |
| 2672 | /* |
| 2673 | * Initialize a lock instance's lock-class mapping info: |
| 2674 | */ |
| 2675 | void lockdep_init_map(struct lockdep_map *lock, const char *name, |
| 2676 | struct lock_class_key *key, int subclass) |
| 2677 | { |
| 2678 | int i; |
| 2679 | |
| 2680 | for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) |
| 2681 | lock->class_cache[i] = NULL; |
| 2682 | |
| 2683 | #ifdef CONFIG_LOCK_STAT |
| 2684 | lock->cpu = raw_smp_processor_id(); |
| 2685 | #endif |
| 2686 | |
| 2687 | if (DEBUG_LOCKS_WARN_ON(!name)) { |
| 2688 | lock->name = "NULL"; |
| 2689 | return; |
| 2690 | } |
| 2691 | |
| 2692 | lock->name = name; |
| 2693 | |
| 2694 | if (DEBUG_LOCKS_WARN_ON(!key)) |
| 2695 | return; |
| 2696 | /* |
| 2697 | * Sanity check, the lock-class key must be persistent: |
| 2698 | */ |
| 2699 | if (!static_obj(key)) { |
| 2700 | printk("BUG: key %p not in .data!\n", key); |
| 2701 | DEBUG_LOCKS_WARN_ON(1); |
| 2702 | return; |
| 2703 | } |
| 2704 | lock->key = key; |
| 2705 | |
| 2706 | if (unlikely(!debug_locks)) |
| 2707 | return; |
| 2708 | |
| 2709 | if (subclass) |
| 2710 | register_lock_class(lock, subclass, 1); |
| 2711 | } |
| 2712 | EXPORT_SYMBOL_GPL(lockdep_init_map); |
| 2713 | |
| 2714 | struct lock_class_key __lockdep_no_validate__; |
| 2715 | |
| 2716 | /* |
| 2717 | * This gets called for every mutex_lock*()/spin_lock*() operation. |
| 2718 | * We maintain the dependency maps and validate the locking attempt: |
| 2719 | */ |
| 2720 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
| 2721 | int trylock, int read, int check, int hardirqs_off, |
| 2722 | struct lockdep_map *nest_lock, unsigned long ip, |
| 2723 | int references) |
| 2724 | { |
| 2725 | struct task_struct *curr = current; |
| 2726 | struct lock_class *class = NULL; |
| 2727 | struct held_lock *hlock; |
| 2728 | unsigned int depth, id; |
| 2729 | int chain_head = 0; |
| 2730 | int class_idx; |
| 2731 | u64 chain_key; |
| 2732 | |
| 2733 | if (!prove_locking) |
| 2734 | check = 1; |
| 2735 | |
| 2736 | if (unlikely(!debug_locks)) |
| 2737 | return 0; |
| 2738 | |
| 2739 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| 2740 | return 0; |
| 2741 | |
| 2742 | if (lock->key == &__lockdep_no_validate__) |
| 2743 | check = 1; |
| 2744 | |
| 2745 | if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
| 2746 | class = lock->class_cache[subclass]; |
| 2747 | /* |
| 2748 | * Not cached? |
| 2749 | */ |
| 2750 | if (unlikely(!class)) { |
| 2751 | class = register_lock_class(lock, subclass, 0); |
| 2752 | if (!class) |
| 2753 | return 0; |
| 2754 | } |
| 2755 | atomic_inc((atomic_t *)&class->ops); |
| 2756 | if (very_verbose(class)) { |
| 2757 | printk("\nacquire class [%p] %s", class->key, class->name); |
| 2758 | if (class->name_version > 1) |
| 2759 | printk("#%d", class->name_version); |
| 2760 | printk("\n"); |
| 2761 | dump_stack(); |
| 2762 | } |
| 2763 | |
| 2764 | /* |
| 2765 | * Add the lock to the list of currently held locks. |
| 2766 | * (we dont increase the depth just yet, up until the |
| 2767 | * dependency checks are done) |
| 2768 | */ |
| 2769 | depth = curr->lockdep_depth; |
| 2770 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) |
| 2771 | return 0; |
| 2772 | |
| 2773 | class_idx = class - lock_classes + 1; |
| 2774 | |
| 2775 | if (depth) { |
| 2776 | hlock = curr->held_locks + depth - 1; |
| 2777 | if (hlock->class_idx == class_idx && nest_lock) { |
| 2778 | if (hlock->references) |
| 2779 | hlock->references++; |
| 2780 | else |
| 2781 | hlock->references = 2; |
| 2782 | |
| 2783 | return 1; |
| 2784 | } |
| 2785 | } |
| 2786 | |
| 2787 | hlock = curr->held_locks + depth; |
| 2788 | if (DEBUG_LOCKS_WARN_ON(!class)) |
| 2789 | return 0; |
| 2790 | hlock->class_idx = class_idx; |
| 2791 | hlock->acquire_ip = ip; |
| 2792 | hlock->instance = lock; |
| 2793 | hlock->nest_lock = nest_lock; |
| 2794 | hlock->trylock = trylock; |
| 2795 | hlock->read = read; |
| 2796 | hlock->check = check; |
| 2797 | hlock->hardirqs_off = !!hardirqs_off; |
| 2798 | hlock->references = references; |
| 2799 | #ifdef CONFIG_LOCK_STAT |
| 2800 | hlock->waittime_stamp = 0; |
| 2801 | hlock->holdtime_stamp = lockstat_clock(); |
| 2802 | #endif |
| 2803 | |
| 2804 | if (check == 2 && !mark_irqflags(curr, hlock)) |
| 2805 | return 0; |
| 2806 | |
| 2807 | /* mark it as used: */ |
| 2808 | if (!mark_lock(curr, hlock, LOCK_USED)) |
| 2809 | return 0; |
| 2810 | |
| 2811 | /* |
| 2812 | * Calculate the chain hash: it's the combined hash of all the |
| 2813 | * lock keys along the dependency chain. We save the hash value |
| 2814 | * at every step so that we can get the current hash easily |
| 2815 | * after unlock. The chain hash is then used to cache dependency |
| 2816 | * results. |
| 2817 | * |
| 2818 | * The 'key ID' is what is the most compact key value to drive |
| 2819 | * the hash, not class->key. |
| 2820 | */ |
| 2821 | id = class - lock_classes; |
| 2822 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) |
| 2823 | return 0; |
| 2824 | |
| 2825 | chain_key = curr->curr_chain_key; |
| 2826 | if (!depth) { |
| 2827 | if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) |
| 2828 | return 0; |
| 2829 | chain_head = 1; |
| 2830 | } |
| 2831 | |
| 2832 | hlock->prev_chain_key = chain_key; |
| 2833 | if (separate_irq_context(curr, hlock)) { |
| 2834 | chain_key = 0; |
| 2835 | chain_head = 1; |
| 2836 | } |
| 2837 | chain_key = iterate_chain_key(chain_key, id); |
| 2838 | |
| 2839 | if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) |
| 2840 | return 0; |
| 2841 | |
| 2842 | curr->curr_chain_key = chain_key; |
| 2843 | curr->lockdep_depth++; |
| 2844 | check_chain_key(curr); |
| 2845 | #ifdef CONFIG_DEBUG_LOCKDEP |
| 2846 | if (unlikely(!debug_locks)) |
| 2847 | return 0; |
| 2848 | #endif |
| 2849 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { |
| 2850 | debug_locks_off(); |
| 2851 | printk("BUG: MAX_LOCK_DEPTH too low!\n"); |
| 2852 | printk("turning off the locking correctness validator.\n"); |
| 2853 | dump_stack(); |
| 2854 | return 0; |
| 2855 | } |
| 2856 | |
| 2857 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) |
| 2858 | max_lockdep_depth = curr->lockdep_depth; |
| 2859 | |
| 2860 | return 1; |
| 2861 | } |
| 2862 | |
| 2863 | static int |
| 2864 | print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock, |
| 2865 | unsigned long ip) |
| 2866 | { |
| 2867 | if (!debug_locks_off()) |
| 2868 | return 0; |
| 2869 | if (debug_locks_silent) |
| 2870 | return 0; |
| 2871 | |
| 2872 | printk("\n=====================================\n"); |
| 2873 | printk( "[ BUG: bad unlock balance detected! ]\n"); |
| 2874 | printk( "-------------------------------------\n"); |
| 2875 | printk("%s/%d is trying to release lock (", |
| 2876 | curr->comm, task_pid_nr(curr)); |
| 2877 | print_lockdep_cache(lock); |
| 2878 | printk(") at:\n"); |
| 2879 | print_ip_sym(ip); |
| 2880 | printk("but there are no more locks to release!\n"); |
| 2881 | printk("\nother info that might help us debug this:\n"); |
| 2882 | lockdep_print_held_locks(curr); |
| 2883 | |
| 2884 | printk("\nstack backtrace:\n"); |
| 2885 | dump_stack(); |
| 2886 | |
| 2887 | return 0; |
| 2888 | } |
| 2889 | |
| 2890 | /* |
| 2891 | * Common debugging checks for both nested and non-nested unlock: |
| 2892 | */ |
| 2893 | static int check_unlock(struct task_struct *curr, struct lockdep_map *lock, |
| 2894 | unsigned long ip) |
| 2895 | { |
| 2896 | if (unlikely(!debug_locks)) |
| 2897 | return 0; |
| 2898 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
| 2899 | return 0; |
| 2900 | |
| 2901 | if (curr->lockdep_depth <= 0) |
| 2902 | return print_unlock_inbalance_bug(curr, lock, ip); |
| 2903 | |
| 2904 | return 1; |
| 2905 | } |
| 2906 | |
| 2907 | static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) |
| 2908 | { |
| 2909 | if (hlock->instance == lock) |
| 2910 | return 1; |
| 2911 | |
| 2912 | if (hlock->references) { |
| 2913 | struct lock_class *class = lock->class_cache[0]; |
| 2914 | |
| 2915 | if (!class) |
| 2916 | class = look_up_lock_class(lock, 0); |
| 2917 | |
| 2918 | if (DEBUG_LOCKS_WARN_ON(!class)) |
| 2919 | return 0; |
| 2920 | |
| 2921 | if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) |
| 2922 | return 0; |
| 2923 | |
| 2924 | if (hlock->class_idx == class - lock_classes + 1) |
| 2925 | return 1; |
| 2926 | } |
| 2927 | |
| 2928 | return 0; |
| 2929 | } |
| 2930 | |
| 2931 | static int |
| 2932 | __lock_set_class(struct lockdep_map *lock, const char *name, |
| 2933 | struct lock_class_key *key, unsigned int subclass, |
| 2934 | unsigned long ip) |
| 2935 | { |
| 2936 | struct task_struct *curr = current; |
| 2937 | struct held_lock *hlock, *prev_hlock; |
| 2938 | struct lock_class *class; |
| 2939 | unsigned int depth; |
| 2940 | int i; |
| 2941 | |
| 2942 | depth = curr->lockdep_depth; |
| 2943 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
| 2944 | return 0; |
| 2945 | |
| 2946 | prev_hlock = NULL; |
| 2947 | for (i = depth-1; i >= 0; i--) { |
| 2948 | hlock = curr->held_locks + i; |
| 2949 | /* |
| 2950 | * We must not cross into another context: |
| 2951 | */ |
| 2952 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
| 2953 | break; |
| 2954 | if (match_held_lock(hlock, lock)) |
| 2955 | goto found_it; |
| 2956 | prev_hlock = hlock; |
| 2957 | } |
| 2958 | return print_unlock_inbalance_bug(curr, lock, ip); |
| 2959 | |
| 2960 | found_it: |
| 2961 | lockdep_init_map(lock, name, key, 0); |
| 2962 | class = register_lock_class(lock, subclass, 0); |
| 2963 | hlock->class_idx = class - lock_classes + 1; |
| 2964 | |
| 2965 | curr->lockdep_depth = i; |
| 2966 | curr->curr_chain_key = hlock->prev_chain_key; |
| 2967 | |
| 2968 | for (; i < depth; i++) { |
| 2969 | hlock = curr->held_locks + i; |
| 2970 | if (!__lock_acquire(hlock->instance, |
| 2971 | hlock_class(hlock)->subclass, hlock->trylock, |
| 2972 | hlock->read, hlock->check, hlock->hardirqs_off, |
| 2973 | hlock->nest_lock, hlock->acquire_ip, |
| 2974 | hlock->references)) |
| 2975 | return 0; |
| 2976 | } |
| 2977 | |
| 2978 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) |
| 2979 | return 0; |
| 2980 | return 1; |
| 2981 | } |
| 2982 | |
| 2983 | /* |
| 2984 | * Remove the lock to the list of currently held locks in a |
| 2985 | * potentially non-nested (out of order) manner. This is a |
| 2986 | * relatively rare operation, as all the unlock APIs default |
| 2987 | * to nested mode (which uses lock_release()): |
| 2988 | */ |
| 2989 | static int |
| 2990 | lock_release_non_nested(struct task_struct *curr, |
| 2991 | struct lockdep_map *lock, unsigned long ip) |
| 2992 | { |
| 2993 | struct held_lock *hlock, *prev_hlock; |
| 2994 | unsigned int depth; |
| 2995 | int i; |
| 2996 | |
| 2997 | /* |
| 2998 | * Check whether the lock exists in the current stack |
| 2999 | * of held locks: |
| 3000 | */ |
| 3001 | depth = curr->lockdep_depth; |
| 3002 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
| 3003 | return 0; |
| 3004 | |
| 3005 | prev_hlock = NULL; |
| 3006 | for (i = depth-1; i >= 0; i--) { |
| 3007 | hlock = curr->held_locks + i; |
| 3008 | /* |
| 3009 | * We must not cross into another context: |
| 3010 | */ |
| 3011 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
| 3012 | break; |
| 3013 | if (match_held_lock(hlock, lock)) |
| 3014 | goto found_it; |
| 3015 | prev_hlock = hlock; |
| 3016 | } |
| 3017 | return print_unlock_inbalance_bug(curr, lock, ip); |
| 3018 | |
| 3019 | found_it: |
| 3020 | if (hlock->instance == lock) |
| 3021 | lock_release_holdtime(hlock); |
| 3022 | |
| 3023 | if (hlock->references) { |
| 3024 | hlock->references--; |
| 3025 | if (hlock->references) { |
| 3026 | /* |
| 3027 | * We had, and after removing one, still have |
| 3028 | * references, the current lock stack is still |
| 3029 | * valid. We're done! |
| 3030 | */ |
| 3031 | return 1; |
| 3032 | } |
| 3033 | } |
| 3034 | |
| 3035 | /* |
| 3036 | * We have the right lock to unlock, 'hlock' points to it. |
| 3037 | * Now we remove it from the stack, and add back the other |
| 3038 | * entries (if any), recalculating the hash along the way: |
| 3039 | */ |
| 3040 | |
| 3041 | curr->lockdep_depth = i; |
| 3042 | curr->curr_chain_key = hlock->prev_chain_key; |
| 3043 | |
| 3044 | for (i++; i < depth; i++) { |
| 3045 | hlock = curr->held_locks + i; |
| 3046 | if (!__lock_acquire(hlock->instance, |
| 3047 | hlock_class(hlock)->subclass, hlock->trylock, |
| 3048 | hlock->read, hlock->check, hlock->hardirqs_off, |
| 3049 | hlock->nest_lock, hlock->acquire_ip, |
| 3050 | hlock->references)) |
| 3051 | return 0; |
| 3052 | } |
| 3053 | |
| 3054 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) |
| 3055 | return 0; |
| 3056 | return 1; |
| 3057 | } |
| 3058 | |
| 3059 | /* |
| 3060 | * Remove the lock to the list of currently held locks - this gets |
| 3061 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
| 3062 | * mutex_lock_interruptible()). This is done for unlocks that nest |
| 3063 | * perfectly. (i.e. the current top of the lock-stack is unlocked) |
| 3064 | */ |
| 3065 | static int lock_release_nested(struct task_struct *curr, |
| 3066 | struct lockdep_map *lock, unsigned long ip) |
| 3067 | { |
| 3068 | struct held_lock *hlock; |
| 3069 | unsigned int depth; |
| 3070 | |
| 3071 | /* |
| 3072 | * Pop off the top of the lock stack: |
| 3073 | */ |
| 3074 | depth = curr->lockdep_depth - 1; |
| 3075 | hlock = curr->held_locks + depth; |
| 3076 | |
| 3077 | /* |
| 3078 | * Is the unlock non-nested: |
| 3079 | */ |
| 3080 | if (hlock->instance != lock || hlock->references) |
| 3081 | return lock_release_non_nested(curr, lock, ip); |
| 3082 | curr->lockdep_depth--; |
| 3083 | |
| 3084 | if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0))) |
| 3085 | return 0; |
| 3086 | |
| 3087 | curr->curr_chain_key = hlock->prev_chain_key; |
| 3088 | |
| 3089 | lock_release_holdtime(hlock); |
| 3090 | |
| 3091 | #ifdef CONFIG_DEBUG_LOCKDEP |
| 3092 | hlock->prev_chain_key = 0; |
| 3093 | hlock->class_idx = 0; |
| 3094 | hlock->acquire_ip = 0; |
| 3095 | hlock->irq_context = 0; |
| 3096 | #endif |
| 3097 | return 1; |
| 3098 | } |
| 3099 | |
| 3100 | /* |
| 3101 | * Remove the lock to the list of currently held locks - this gets |
| 3102 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
| 3103 | * mutex_lock_interruptible()). This is done for unlocks that nest |
| 3104 | * perfectly. (i.e. the current top of the lock-stack is unlocked) |
| 3105 | */ |
| 3106 | static void |
| 3107 | __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) |
| 3108 | { |
| 3109 | struct task_struct *curr = current; |
| 3110 | |
| 3111 | if (!check_unlock(curr, lock, ip)) |
| 3112 | return; |
| 3113 | |
| 3114 | if (nested) { |
| 3115 | if (!lock_release_nested(curr, lock, ip)) |
| 3116 | return; |
| 3117 | } else { |
| 3118 | if (!lock_release_non_nested(curr, lock, ip)) |
| 3119 | return; |
| 3120 | } |
| 3121 | |
| 3122 | check_chain_key(curr); |
| 3123 | } |
| 3124 | |
| 3125 | static int __lock_is_held(struct lockdep_map *lock) |
| 3126 | { |
| 3127 | struct task_struct *curr = current; |
| 3128 | int i; |
| 3129 | |
| 3130 | for (i = 0; i < curr->lockdep_depth; i++) { |
| 3131 | struct held_lock *hlock = curr->held_locks + i; |
| 3132 | |
| 3133 | if (match_held_lock(hlock, lock)) |
| 3134 | return 1; |
| 3135 | } |
| 3136 | |
| 3137 | return 0; |
| 3138 | } |
| 3139 | |
| 3140 | /* |
| 3141 | * Check whether we follow the irq-flags state precisely: |
| 3142 | */ |
| 3143 | static void check_flags(unsigned long flags) |
| 3144 | { |
| 3145 | #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \ |
| 3146 | defined(CONFIG_TRACE_IRQFLAGS) |
| 3147 | if (!debug_locks) |
| 3148 | return; |
| 3149 | |
| 3150 | if (irqs_disabled_flags(flags)) { |
| 3151 | if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { |
| 3152 | printk("possible reason: unannotated irqs-off.\n"); |
| 3153 | } |
| 3154 | } else { |
| 3155 | if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { |
| 3156 | printk("possible reason: unannotated irqs-on.\n"); |
| 3157 | } |
| 3158 | } |
| 3159 | |
| 3160 | /* |
| 3161 | * We dont accurately track softirq state in e.g. |
| 3162 | * hardirq contexts (such as on 4KSTACKS), so only |
| 3163 | * check if not in hardirq contexts: |
| 3164 | */ |
| 3165 | if (!hardirq_count()) { |
| 3166 | if (softirq_count()) |
| 3167 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); |
| 3168 | else |
| 3169 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); |
| 3170 | } |
| 3171 | |
| 3172 | if (!debug_locks) |
| 3173 | print_irqtrace_events(current); |
| 3174 | #endif |
| 3175 | } |
| 3176 | |
| 3177 | void lock_set_class(struct lockdep_map *lock, const char *name, |
| 3178 | struct lock_class_key *key, unsigned int subclass, |
| 3179 | unsigned long ip) |
| 3180 | { |
| 3181 | unsigned long flags; |
| 3182 | |
| 3183 | if (unlikely(current->lockdep_recursion)) |
| 3184 | return; |
| 3185 | |
| 3186 | raw_local_irq_save(flags); |
| 3187 | current->lockdep_recursion = 1; |
| 3188 | check_flags(flags); |
| 3189 | if (__lock_set_class(lock, name, key, subclass, ip)) |
| 3190 | check_chain_key(current); |
| 3191 | current->lockdep_recursion = 0; |
| 3192 | raw_local_irq_restore(flags); |
| 3193 | } |
| 3194 | EXPORT_SYMBOL_GPL(lock_set_class); |
| 3195 | |
| 3196 | /* |
| 3197 | * We are not always called with irqs disabled - do that here, |
| 3198 | * and also avoid lockdep recursion: |
| 3199 | */ |
| 3200 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
| 3201 | int trylock, int read, int check, |
| 3202 | struct lockdep_map *nest_lock, unsigned long ip) |
| 3203 | { |
| 3204 | unsigned long flags; |
| 3205 | |
| 3206 | if (unlikely(current->lockdep_recursion)) |
| 3207 | return; |
| 3208 | |
| 3209 | raw_local_irq_save(flags); |
| 3210 | check_flags(flags); |
| 3211 | |
| 3212 | current->lockdep_recursion = 1; |
| 3213 | trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); |
| 3214 | __lock_acquire(lock, subclass, trylock, read, check, |
| 3215 | irqs_disabled_flags(flags), nest_lock, ip, 0); |
| 3216 | current->lockdep_recursion = 0; |
| 3217 | raw_local_irq_restore(flags); |
| 3218 | } |
| 3219 | EXPORT_SYMBOL_GPL(lock_acquire); |
| 3220 | |
| 3221 | void lock_release(struct lockdep_map *lock, int nested, |
| 3222 | unsigned long ip) |
| 3223 | { |
| 3224 | unsigned long flags; |
| 3225 | |
| 3226 | if (unlikely(current->lockdep_recursion)) |
| 3227 | return; |
| 3228 | |
| 3229 | raw_local_irq_save(flags); |
| 3230 | check_flags(flags); |
| 3231 | current->lockdep_recursion = 1; |
| 3232 | trace_lock_release(lock, ip); |
| 3233 | __lock_release(lock, nested, ip); |
| 3234 | current->lockdep_recursion = 0; |
| 3235 | raw_local_irq_restore(flags); |
| 3236 | } |
| 3237 | EXPORT_SYMBOL_GPL(lock_release); |
| 3238 | |
| 3239 | int lock_is_held(struct lockdep_map *lock) |
| 3240 | { |
| 3241 | unsigned long flags; |
| 3242 | int ret = 0; |
| 3243 | |
| 3244 | if (unlikely(current->lockdep_recursion)) |
| 3245 | return ret; |
| 3246 | |
| 3247 | raw_local_irq_save(flags); |
| 3248 | check_flags(flags); |
| 3249 | |
| 3250 | current->lockdep_recursion = 1; |
| 3251 | ret = __lock_is_held(lock); |
| 3252 | current->lockdep_recursion = 0; |
| 3253 | raw_local_irq_restore(flags); |
| 3254 | |
| 3255 | return ret; |
| 3256 | } |
| 3257 | EXPORT_SYMBOL_GPL(lock_is_held); |
| 3258 | |
| 3259 | void lockdep_set_current_reclaim_state(gfp_t gfp_mask) |
| 3260 | { |
| 3261 | current->lockdep_reclaim_gfp = gfp_mask; |
| 3262 | } |
| 3263 | |
| 3264 | void lockdep_clear_current_reclaim_state(void) |
| 3265 | { |
| 3266 | current->lockdep_reclaim_gfp = 0; |
| 3267 | } |
| 3268 | |
| 3269 | #ifdef CONFIG_LOCK_STAT |
| 3270 | static int |
| 3271 | print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, |
| 3272 | unsigned long ip) |
| 3273 | { |
| 3274 | if (!debug_locks_off()) |
| 3275 | return 0; |
| 3276 | if (debug_locks_silent) |
| 3277 | return 0; |
| 3278 | |
| 3279 | printk("\n=================================\n"); |
| 3280 | printk( "[ BUG: bad contention detected! ]\n"); |
| 3281 | printk( "---------------------------------\n"); |
| 3282 | printk("%s/%d is trying to contend lock (", |
| 3283 | curr->comm, task_pid_nr(curr)); |
| 3284 | print_lockdep_cache(lock); |
| 3285 | printk(") at:\n"); |
| 3286 | print_ip_sym(ip); |
| 3287 | printk("but there are no locks held!\n"); |
| 3288 | printk("\nother info that might help us debug this:\n"); |
| 3289 | lockdep_print_held_locks(curr); |
| 3290 | |
| 3291 | printk("\nstack backtrace:\n"); |
| 3292 | dump_stack(); |
| 3293 | |
| 3294 | return 0; |
| 3295 | } |
| 3296 | |
| 3297 | static void |
| 3298 | __lock_contended(struct lockdep_map *lock, unsigned long ip) |
| 3299 | { |
| 3300 | struct task_struct *curr = current; |
| 3301 | struct held_lock *hlock, *prev_hlock; |
| 3302 | struct lock_class_stats *stats; |
| 3303 | unsigned int depth; |
| 3304 | int i, contention_point, contending_point; |
| 3305 | |
| 3306 | depth = curr->lockdep_depth; |
| 3307 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
| 3308 | return; |
| 3309 | |
| 3310 | prev_hlock = NULL; |
| 3311 | for (i = depth-1; i >= 0; i--) { |
| 3312 | hlock = curr->held_locks + i; |
| 3313 | /* |
| 3314 | * We must not cross into another context: |
| 3315 | */ |
| 3316 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
| 3317 | break; |
| 3318 | if (match_held_lock(hlock, lock)) |
| 3319 | goto found_it; |
| 3320 | prev_hlock = hlock; |
| 3321 | } |
| 3322 | print_lock_contention_bug(curr, lock, ip); |
| 3323 | return; |
| 3324 | |
| 3325 | found_it: |
| 3326 | if (hlock->instance != lock) |
| 3327 | return; |
| 3328 | |
| 3329 | hlock->waittime_stamp = lockstat_clock(); |
| 3330 | |
| 3331 | contention_point = lock_point(hlock_class(hlock)->contention_point, ip); |
| 3332 | contending_point = lock_point(hlock_class(hlock)->contending_point, |
| 3333 | lock->ip); |
| 3334 | |
| 3335 | stats = get_lock_stats(hlock_class(hlock)); |
| 3336 | if (contention_point < LOCKSTAT_POINTS) |
| 3337 | stats->contention_point[contention_point]++; |
| 3338 | if (contending_point < LOCKSTAT_POINTS) |
| 3339 | stats->contending_point[contending_point]++; |
| 3340 | if (lock->cpu != smp_processor_id()) |
| 3341 | stats->bounces[bounce_contended + !!hlock->read]++; |
| 3342 | put_lock_stats(stats); |
| 3343 | } |
| 3344 | |
| 3345 | static void |
| 3346 | __lock_acquired(struct lockdep_map *lock, unsigned long ip) |
| 3347 | { |
| 3348 | struct task_struct *curr = current; |
| 3349 | struct held_lock *hlock, *prev_hlock; |
| 3350 | struct lock_class_stats *stats; |
| 3351 | unsigned int depth; |
| 3352 | u64 now, waittime = 0; |
| 3353 | int i, cpu; |
| 3354 | |
| 3355 | depth = curr->lockdep_depth; |
| 3356 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
| 3357 | return; |
| 3358 | |
| 3359 | prev_hlock = NULL; |
| 3360 | for (i = depth-1; i >= 0; i--) { |
| 3361 | hlock = curr->held_locks + i; |
| 3362 | /* |
| 3363 | * We must not cross into another context: |
| 3364 | */ |
| 3365 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) |
| 3366 | break; |
| 3367 | if (match_held_lock(hlock, lock)) |
| 3368 | goto found_it; |
| 3369 | prev_hlock = hlock; |
| 3370 | } |
| 3371 | print_lock_contention_bug(curr, lock, _RET_IP_); |
| 3372 | return; |
| 3373 | |
| 3374 | found_it: |
| 3375 | if (hlock->instance != lock) |
| 3376 | return; |
| 3377 | |
| 3378 | cpu = smp_processor_id(); |
| 3379 | if (hlock->waittime_stamp) { |
| 3380 | now = lockstat_clock(); |
| 3381 | waittime = now - hlock->waittime_stamp; |
| 3382 | hlock->holdtime_stamp = now; |
| 3383 | } |
| 3384 | |
| 3385 | trace_lock_acquired(lock, ip); |
| 3386 | |
| 3387 | stats = get_lock_stats(hlock_class(hlock)); |
| 3388 | if (waittime) { |
| 3389 | if (hlock->read) |
| 3390 | lock_time_inc(&stats->read_waittime, waittime); |
| 3391 | else |
| 3392 | lock_time_inc(&stats->write_waittime, waittime); |
| 3393 | } |
| 3394 | if (lock->cpu != cpu) |
| 3395 | stats->bounces[bounce_acquired + !!hlock->read]++; |
| 3396 | put_lock_stats(stats); |
| 3397 | |
| 3398 | lock->cpu = cpu; |
| 3399 | lock->ip = ip; |
| 3400 | } |
| 3401 | |
| 3402 | void lock_contended(struct lockdep_map *lock, unsigned long ip) |
| 3403 | { |
| 3404 | unsigned long flags; |
| 3405 | |
| 3406 | if (unlikely(!lock_stat)) |
| 3407 | return; |
| 3408 | |
| 3409 | if (unlikely(current->lockdep_recursion)) |
| 3410 | return; |
| 3411 | |
| 3412 | raw_local_irq_save(flags); |
| 3413 | check_flags(flags); |
| 3414 | current->lockdep_recursion = 1; |
| 3415 | trace_lock_contended(lock, ip); |
| 3416 | __lock_contended(lock, ip); |
| 3417 | current->lockdep_recursion = 0; |
| 3418 | raw_local_irq_restore(flags); |
| 3419 | } |
| 3420 | EXPORT_SYMBOL_GPL(lock_contended); |
| 3421 | |
| 3422 | void lock_acquired(struct lockdep_map *lock, unsigned long ip) |
| 3423 | { |
| 3424 | unsigned long flags; |
| 3425 | |
| 3426 | if (unlikely(!lock_stat)) |
| 3427 | return; |
| 3428 | |
| 3429 | if (unlikely(current->lockdep_recursion)) |
| 3430 | return; |
| 3431 | |
| 3432 | raw_local_irq_save(flags); |
| 3433 | check_flags(flags); |
| 3434 | current->lockdep_recursion = 1; |
| 3435 | __lock_acquired(lock, ip); |
| 3436 | current->lockdep_recursion = 0; |
| 3437 | raw_local_irq_restore(flags); |
| 3438 | } |
| 3439 | EXPORT_SYMBOL_GPL(lock_acquired); |
| 3440 | #endif |
| 3441 | |
| 3442 | /* |
| 3443 | * Used by the testsuite, sanitize the validator state |
| 3444 | * after a simulated failure: |
| 3445 | */ |
| 3446 | |
| 3447 | void lockdep_reset(void) |
| 3448 | { |
| 3449 | unsigned long flags; |
| 3450 | int i; |
| 3451 | |
| 3452 | raw_local_irq_save(flags); |
| 3453 | current->curr_chain_key = 0; |
| 3454 | current->lockdep_depth = 0; |
| 3455 | current->lockdep_recursion = 0; |
| 3456 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); |
| 3457 | nr_hardirq_chains = 0; |
| 3458 | nr_softirq_chains = 0; |
| 3459 | nr_process_chains = 0; |
| 3460 | debug_locks = 1; |
| 3461 | for (i = 0; i < CHAINHASH_SIZE; i++) |
| 3462 | INIT_LIST_HEAD(chainhash_table + i); |
| 3463 | raw_local_irq_restore(flags); |
| 3464 | } |
| 3465 | |
| 3466 | static void zap_class(struct lock_class *class) |
| 3467 | { |
| 3468 | int i; |
| 3469 | |
| 3470 | /* |
| 3471 | * Remove all dependencies this lock is |
| 3472 | * involved in: |
| 3473 | */ |
| 3474 | for (i = 0; i < nr_list_entries; i++) { |
| 3475 | if (list_entries[i].class == class) |
| 3476 | list_del_rcu(&list_entries[i].entry); |
| 3477 | } |
| 3478 | /* |
| 3479 | * Unhash the class and remove it from the all_lock_classes list: |
| 3480 | */ |
| 3481 | list_del_rcu(&class->hash_entry); |
| 3482 | list_del_rcu(&class->lock_entry); |
| 3483 | |
| 3484 | class->key = NULL; |
| 3485 | } |
| 3486 | |
| 3487 | static inline int within(const void *addr, void *start, unsigned long size) |
| 3488 | { |
| 3489 | return addr >= start && addr < start + size; |
| 3490 | } |
| 3491 | |
| 3492 | void lockdep_free_key_range(void *start, unsigned long size) |
| 3493 | { |
| 3494 | struct lock_class *class, *next; |
| 3495 | struct list_head *head; |
| 3496 | unsigned long flags; |
| 3497 | int i; |
| 3498 | int locked; |
| 3499 | |
| 3500 | raw_local_irq_save(flags); |
| 3501 | locked = graph_lock(); |
| 3502 | |
| 3503 | /* |
| 3504 | * Unhash all classes that were created by this module: |
| 3505 | */ |
| 3506 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
| 3507 | head = classhash_table + i; |
| 3508 | if (list_empty(head)) |
| 3509 | continue; |
| 3510 | list_for_each_entry_safe(class, next, head, hash_entry) { |
| 3511 | if (within(class->key, start, size)) |
| 3512 | zap_class(class); |
| 3513 | else if (within(class->name, start, size)) |
| 3514 | zap_class(class); |
| 3515 | } |
| 3516 | } |
| 3517 | |
| 3518 | if (locked) |
| 3519 | graph_unlock(); |
| 3520 | raw_local_irq_restore(flags); |
| 3521 | } |
| 3522 | |
| 3523 | void lockdep_reset_lock(struct lockdep_map *lock) |
| 3524 | { |
| 3525 | struct lock_class *class, *next; |
| 3526 | struct list_head *head; |
| 3527 | unsigned long flags; |
| 3528 | int i, j; |
| 3529 | int locked; |
| 3530 | |
| 3531 | raw_local_irq_save(flags); |
| 3532 | |
| 3533 | /* |
| 3534 | * Remove all classes this lock might have: |
| 3535 | */ |
| 3536 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { |
| 3537 | /* |
| 3538 | * If the class exists we look it up and zap it: |
| 3539 | */ |
| 3540 | class = look_up_lock_class(lock, j); |
| 3541 | if (class) |
| 3542 | zap_class(class); |
| 3543 | } |
| 3544 | /* |
| 3545 | * Debug check: in the end all mapped classes should |
| 3546 | * be gone. |
| 3547 | */ |
| 3548 | locked = graph_lock(); |
| 3549 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
| 3550 | head = classhash_table + i; |
| 3551 | if (list_empty(head)) |
| 3552 | continue; |
| 3553 | list_for_each_entry_safe(class, next, head, hash_entry) { |
| 3554 | int match = 0; |
| 3555 | |
| 3556 | for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) |
| 3557 | match |= class == lock->class_cache[j]; |
| 3558 | |
| 3559 | if (unlikely(match)) { |
| 3560 | if (debug_locks_off_graph_unlock()) |
| 3561 | WARN_ON(1); |
| 3562 | goto out_restore; |
| 3563 | } |
| 3564 | } |
| 3565 | } |
| 3566 | if (locked) |
| 3567 | graph_unlock(); |
| 3568 | |
| 3569 | out_restore: |
| 3570 | raw_local_irq_restore(flags); |
| 3571 | } |
| 3572 | |
| 3573 | void lockdep_init(void) |
| 3574 | { |
| 3575 | int i; |
| 3576 | |
| 3577 | /* |
| 3578 | * Some architectures have their own start_kernel() |
| 3579 | * code which calls lockdep_init(), while we also |
| 3580 | * call lockdep_init() from the start_kernel() itself, |
| 3581 | * and we want to initialize the hashes only once: |
| 3582 | */ |
| 3583 | if (lockdep_initialized) |
| 3584 | return; |
| 3585 | |
| 3586 | for (i = 0; i < CLASSHASH_SIZE; i++) |
| 3587 | INIT_LIST_HEAD(classhash_table + i); |
| 3588 | |
| 3589 | for (i = 0; i < CHAINHASH_SIZE; i++) |
| 3590 | INIT_LIST_HEAD(chainhash_table + i); |
| 3591 | |
| 3592 | lockdep_initialized = 1; |
| 3593 | } |
| 3594 | |
| 3595 | void __init lockdep_info(void) |
| 3596 | { |
| 3597 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); |
| 3598 | |
| 3599 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); |
| 3600 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); |
| 3601 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); |
| 3602 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); |
| 3603 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); |
| 3604 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); |
| 3605 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); |
| 3606 | |
| 3607 | printk(" memory used by lock dependency info: %lu kB\n", |
| 3608 | (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + |
| 3609 | sizeof(struct list_head) * CLASSHASH_SIZE + |
| 3610 | sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + |
| 3611 | sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + |
| 3612 | sizeof(struct list_head) * CHAINHASH_SIZE |
| 3613 | #ifdef CONFIG_PROVE_LOCKING |
| 3614 | + sizeof(struct circular_queue) |
| 3615 | #endif |
| 3616 | ) / 1024 |
| 3617 | ); |
| 3618 | |
| 3619 | printk(" per task-struct memory footprint: %lu bytes\n", |
| 3620 | sizeof(struct held_lock) * MAX_LOCK_DEPTH); |
| 3621 | |
| 3622 | #ifdef CONFIG_DEBUG_LOCKDEP |
| 3623 | if (lockdep_init_error) { |
| 3624 | printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n"); |
| 3625 | printk("Call stack leading to lockdep invocation was:\n"); |
| 3626 | print_stack_trace(&lockdep_init_trace, 0); |
| 3627 | } |
| 3628 | #endif |
| 3629 | } |
| 3630 | |
| 3631 | static void |
| 3632 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, |
| 3633 | const void *mem_to, struct held_lock *hlock) |
| 3634 | { |
| 3635 | if (!debug_locks_off()) |
| 3636 | return; |
| 3637 | if (debug_locks_silent) |
| 3638 | return; |
| 3639 | |
| 3640 | printk("\n=========================\n"); |
| 3641 | printk( "[ BUG: held lock freed! ]\n"); |
| 3642 | printk( "-------------------------\n"); |
| 3643 | printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", |
| 3644 | curr->comm, task_pid_nr(curr), mem_from, mem_to-1); |
| 3645 | print_lock(hlock); |
| 3646 | lockdep_print_held_locks(curr); |
| 3647 | |
| 3648 | printk("\nstack backtrace:\n"); |
| 3649 | dump_stack(); |
| 3650 | } |
| 3651 | |
| 3652 | static inline int not_in_range(const void* mem_from, unsigned long mem_len, |
| 3653 | const void* lock_from, unsigned long lock_len) |
| 3654 | { |
| 3655 | return lock_from + lock_len <= mem_from || |
| 3656 | mem_from + mem_len <= lock_from; |
| 3657 | } |
| 3658 | |
| 3659 | /* |
| 3660 | * Called when kernel memory is freed (or unmapped), or if a lock |
| 3661 | * is destroyed or reinitialized - this code checks whether there is |
| 3662 | * any held lock in the memory range of <from> to <to>: |
| 3663 | */ |
| 3664 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) |
| 3665 | { |
| 3666 | struct task_struct *curr = current; |
| 3667 | struct held_lock *hlock; |
| 3668 | unsigned long flags; |
| 3669 | int i; |
| 3670 | |
| 3671 | if (unlikely(!debug_locks)) |
| 3672 | return; |
| 3673 | |
| 3674 | local_irq_save(flags); |
| 3675 | for (i = 0; i < curr->lockdep_depth; i++) { |
| 3676 | hlock = curr->held_locks + i; |
| 3677 | |
| 3678 | if (not_in_range(mem_from, mem_len, hlock->instance, |
| 3679 | sizeof(*hlock->instance))) |
| 3680 | continue; |
| 3681 | |
| 3682 | print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); |
| 3683 | break; |
| 3684 | } |
| 3685 | local_irq_restore(flags); |
| 3686 | } |
| 3687 | EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); |
| 3688 | |
| 3689 | static void print_held_locks_bug(struct task_struct *curr) |
| 3690 | { |
| 3691 | if (!debug_locks_off()) |
| 3692 | return; |
| 3693 | if (debug_locks_silent) |
| 3694 | return; |
| 3695 | |
| 3696 | printk("\n=====================================\n"); |
| 3697 | printk( "[ BUG: lock held at task exit time! ]\n"); |
| 3698 | printk( "-------------------------------------\n"); |
| 3699 | printk("%s/%d is exiting with locks still held!\n", |
| 3700 | curr->comm, task_pid_nr(curr)); |
| 3701 | lockdep_print_held_locks(curr); |
| 3702 | |
| 3703 | printk("\nstack backtrace:\n"); |
| 3704 | dump_stack(); |
| 3705 | } |
| 3706 | |
| 3707 | void debug_check_no_locks_held(struct task_struct *task) |
| 3708 | { |
| 3709 | if (unlikely(task->lockdep_depth > 0)) |
| 3710 | print_held_locks_bug(task); |
| 3711 | } |
| 3712 | |
| 3713 | void debug_show_all_locks(void) |
| 3714 | { |
| 3715 | struct task_struct *g, *p; |
| 3716 | int count = 10; |
| 3717 | int unlock = 1; |
| 3718 | |
| 3719 | if (unlikely(!debug_locks)) { |
| 3720 | printk("INFO: lockdep is turned off.\n"); |
| 3721 | return; |
| 3722 | } |
| 3723 | printk("\nShowing all locks held in the system:\n"); |
| 3724 | |
| 3725 | /* |
| 3726 | * Here we try to get the tasklist_lock as hard as possible, |
| 3727 | * if not successful after 2 seconds we ignore it (but keep |
| 3728 | * trying). This is to enable a debug printout even if a |
| 3729 | * tasklist_lock-holding task deadlocks or crashes. |
| 3730 | */ |
| 3731 | retry: |
| 3732 | if (!read_trylock(&tasklist_lock)) { |
| 3733 | if (count == 10) |
| 3734 | printk("hm, tasklist_lock locked, retrying... "); |
| 3735 | if (count) { |
| 3736 | count--; |
| 3737 | printk(" #%d", 10-count); |
| 3738 | mdelay(200); |
| 3739 | goto retry; |
| 3740 | } |
| 3741 | printk(" ignoring it.\n"); |
| 3742 | unlock = 0; |
| 3743 | } else { |
| 3744 | if (count != 10) |
| 3745 | printk(KERN_CONT " locked it.\n"); |
| 3746 | } |
| 3747 | |
| 3748 | do_each_thread(g, p) { |
| 3749 | /* |
| 3750 | * It's not reliable to print a task's held locks |
| 3751 | * if it's not sleeping (or if it's not the current |
| 3752 | * task): |
| 3753 | */ |
| 3754 | if (p->state == TASK_RUNNING && p != current) |
| 3755 | continue; |
| 3756 | if (p->lockdep_depth) |
| 3757 | lockdep_print_held_locks(p); |
| 3758 | if (!unlock) |
| 3759 | if (read_trylock(&tasklist_lock)) |
| 3760 | unlock = 1; |
| 3761 | } while_each_thread(g, p); |
| 3762 | |
| 3763 | printk("\n"); |
| 3764 | printk("=============================================\n\n"); |
| 3765 | |
| 3766 | if (unlock) |
| 3767 | read_unlock(&tasklist_lock); |
| 3768 | } |
| 3769 | EXPORT_SYMBOL_GPL(debug_show_all_locks); |
| 3770 | |
| 3771 | /* |
| 3772 | * Careful: only use this function if you are sure that |
| 3773 | * the task cannot run in parallel! |
| 3774 | */ |
| 3775 | void debug_show_held_locks(struct task_struct *task) |
| 3776 | { |
| 3777 | if (unlikely(!debug_locks)) { |
| 3778 | printk("INFO: lockdep is turned off.\n"); |
| 3779 | return; |
| 3780 | } |
| 3781 | lockdep_print_held_locks(task); |
| 3782 | } |
| 3783 | EXPORT_SYMBOL_GPL(debug_show_held_locks); |
| 3784 | |
| 3785 | void lockdep_sys_exit(void) |
| 3786 | { |
| 3787 | struct task_struct *curr = current; |
| 3788 | |
| 3789 | if (unlikely(curr->lockdep_depth)) { |
| 3790 | if (!debug_locks_off()) |
| 3791 | return; |
| 3792 | printk("\n================================================\n"); |
| 3793 | printk( "[ BUG: lock held when returning to user space! ]\n"); |
| 3794 | printk( "------------------------------------------------\n"); |
| 3795 | printk("%s/%d is leaving the kernel with locks still held!\n", |
| 3796 | curr->comm, curr->pid); |
| 3797 | lockdep_print_held_locks(curr); |
| 3798 | } |
| 3799 | } |
| 3800 | |
| 3801 | void lockdep_rcu_dereference(const char *file, const int line) |
| 3802 | { |
| 3803 | struct task_struct *curr = current; |
| 3804 | |
| 3805 | #ifndef CONFIG_PROVE_RCU_REPEATEDLY |
| 3806 | if (!debug_locks_off()) |
| 3807 | return; |
| 3808 | #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */ |
| 3809 | /* Note: the following can be executed concurrently, so be careful. */ |
| 3810 | printk("\n===================================================\n"); |
| 3811 | printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n"); |
| 3812 | printk( "---------------------------------------------------\n"); |
| 3813 | printk("%s:%d invoked rcu_dereference_check() without protection!\n", |
| 3814 | file, line); |
| 3815 | printk("\nother info that might help us debug this:\n\n"); |
| 3816 | printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks); |
| 3817 | lockdep_print_held_locks(curr); |
| 3818 | printk("\nstack backtrace:\n"); |
| 3819 | dump_stack(); |
| 3820 | } |
| 3821 | EXPORT_SYMBOL_GPL(lockdep_rcu_dereference); |