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 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/sched/clock.h> 32 #include <linux/sched/task.h> 33 #include <linux/sched/mm.h> 34 #include <linux/delay.h> 35 #include <linux/module.h> 36 #include <linux/proc_fs.h> 37 #include <linux/seq_file.h> 38 #include <linux/spinlock.h> 39 #include <linux/kallsyms.h> 40 #include <linux/interrupt.h> 41 #include <linux/stacktrace.h> 42 #include <linux/debug_locks.h> 43 #include <linux/irqflags.h> 44 #include <linux/utsname.h> 45 #include <linux/hash.h> 46 #include <linux/ftrace.h> 47 #include <linux/stringify.h> 48 #include <linux/bitops.h> 49 #include <linux/gfp.h> 50 #include <linux/kmemcheck.h> 51 #include <linux/random.h> 52 #include <linux/jhash.h> 53 54 #include <asm/sections.h> 55 56 #include "lockdep_internals.h" 57 58 #define CREATE_TRACE_POINTS 59 #include <trace/events/lock.h> 60 61 #ifdef CONFIG_LOCKDEP_CROSSRELEASE 62 #include <linux/slab.h> 63 #endif 64 65 #ifdef CONFIG_PROVE_LOCKING 66 int prove_locking = 1; 67 module_param(prove_locking, int, 0644); 68 #else 69 #define prove_locking 0 70 #endif 71 72 #ifdef CONFIG_LOCK_STAT 73 int lock_stat = 1; 74 module_param(lock_stat, int, 0644); 75 #else 76 #define lock_stat 0 77 #endif 78 79 /* 80 * lockdep_lock: protects the lockdep graph, the hashes and the 81 * class/list/hash allocators. 82 * 83 * This is one of the rare exceptions where it's justified 84 * to use a raw spinlock - we really dont want the spinlock 85 * code to recurse back into the lockdep code... 86 */ 87 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; 88 89 static int graph_lock(void) 90 { 91 arch_spin_lock(&lockdep_lock); 92 /* 93 * Make sure that if another CPU detected a bug while 94 * walking the graph we dont change it (while the other 95 * CPU is busy printing out stuff with the graph lock 96 * dropped already) 97 */ 98 if (!debug_locks) { 99 arch_spin_unlock(&lockdep_lock); 100 return 0; 101 } 102 /* prevent any recursions within lockdep from causing deadlocks */ 103 current->lockdep_recursion++; 104 return 1; 105 } 106 107 static inline int graph_unlock(void) 108 { 109 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) { 110 /* 111 * The lockdep graph lock isn't locked while we expect it to 112 * be, we're confused now, bye! 113 */ 114 return DEBUG_LOCKS_WARN_ON(1); 115 } 116 117 current->lockdep_recursion--; 118 arch_spin_unlock(&lockdep_lock); 119 return 0; 120 } 121 122 /* 123 * Turn lock debugging off and return with 0 if it was off already, 124 * and also release the graph lock: 125 */ 126 static inline int debug_locks_off_graph_unlock(void) 127 { 128 int ret = debug_locks_off(); 129 130 arch_spin_unlock(&lockdep_lock); 131 132 return ret; 133 } 134 135 unsigned long nr_list_entries; 136 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; 137 138 /* 139 * All data structures here are protected by the global debug_lock. 140 * 141 * Mutex key structs only get allocated, once during bootup, and never 142 * get freed - this significantly simplifies the debugging code. 143 */ 144 unsigned long nr_lock_classes; 145 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; 146 147 static inline struct lock_class *hlock_class(struct held_lock *hlock) 148 { 149 if (!hlock->class_idx) { 150 /* 151 * Someone passed in garbage, we give up. 152 */ 153 DEBUG_LOCKS_WARN_ON(1); 154 return NULL; 155 } 156 return lock_classes + hlock->class_idx - 1; 157 } 158 159 #ifdef CONFIG_LOCK_STAT 160 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats); 161 162 static inline u64 lockstat_clock(void) 163 { 164 return local_clock(); 165 } 166 167 static int lock_point(unsigned long points[], unsigned long ip) 168 { 169 int i; 170 171 for (i = 0; i < LOCKSTAT_POINTS; i++) { 172 if (points[i] == 0) { 173 points[i] = ip; 174 break; 175 } 176 if (points[i] == ip) 177 break; 178 } 179 180 return i; 181 } 182 183 static void lock_time_inc(struct lock_time *lt, u64 time) 184 { 185 if (time > lt->max) 186 lt->max = time; 187 188 if (time < lt->min || !lt->nr) 189 lt->min = time; 190 191 lt->total += time; 192 lt->nr++; 193 } 194 195 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) 196 { 197 if (!src->nr) 198 return; 199 200 if (src->max > dst->max) 201 dst->max = src->max; 202 203 if (src->min < dst->min || !dst->nr) 204 dst->min = src->min; 205 206 dst->total += src->total; 207 dst->nr += src->nr; 208 } 209 210 struct lock_class_stats lock_stats(struct lock_class *class) 211 { 212 struct lock_class_stats stats; 213 int cpu, i; 214 215 memset(&stats, 0, sizeof(struct lock_class_stats)); 216 for_each_possible_cpu(cpu) { 217 struct lock_class_stats *pcs = 218 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; 219 220 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) 221 stats.contention_point[i] += pcs->contention_point[i]; 222 223 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) 224 stats.contending_point[i] += pcs->contending_point[i]; 225 226 lock_time_add(&pcs->read_waittime, &stats.read_waittime); 227 lock_time_add(&pcs->write_waittime, &stats.write_waittime); 228 229 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); 230 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); 231 232 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) 233 stats.bounces[i] += pcs->bounces[i]; 234 } 235 236 return stats; 237 } 238 239 void clear_lock_stats(struct lock_class *class) 240 { 241 int cpu; 242 243 for_each_possible_cpu(cpu) { 244 struct lock_class_stats *cpu_stats = 245 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; 246 247 memset(cpu_stats, 0, sizeof(struct lock_class_stats)); 248 } 249 memset(class->contention_point, 0, sizeof(class->contention_point)); 250 memset(class->contending_point, 0, sizeof(class->contending_point)); 251 } 252 253 static struct lock_class_stats *get_lock_stats(struct lock_class *class) 254 { 255 return &get_cpu_var(cpu_lock_stats)[class - lock_classes]; 256 } 257 258 static void put_lock_stats(struct lock_class_stats *stats) 259 { 260 put_cpu_var(cpu_lock_stats); 261 } 262 263 static void lock_release_holdtime(struct held_lock *hlock) 264 { 265 struct lock_class_stats *stats; 266 u64 holdtime; 267 268 if (!lock_stat) 269 return; 270 271 holdtime = lockstat_clock() - hlock->holdtime_stamp; 272 273 stats = get_lock_stats(hlock_class(hlock)); 274 if (hlock->read) 275 lock_time_inc(&stats->read_holdtime, holdtime); 276 else 277 lock_time_inc(&stats->write_holdtime, holdtime); 278 put_lock_stats(stats); 279 } 280 #else 281 static inline void lock_release_holdtime(struct held_lock *hlock) 282 { 283 } 284 #endif 285 286 /* 287 * We keep a global list of all lock classes. The list only grows, 288 * never shrinks. The list is only accessed with the lockdep 289 * spinlock lock held. 290 */ 291 LIST_HEAD(all_lock_classes); 292 293 /* 294 * The lockdep classes are in a hash-table as well, for fast lookup: 295 */ 296 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) 297 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) 298 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) 299 #define classhashentry(key) (classhash_table + __classhashfn((key))) 300 301 static struct hlist_head classhash_table[CLASSHASH_SIZE]; 302 303 /* 304 * We put the lock dependency chains into a hash-table as well, to cache 305 * their existence: 306 */ 307 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) 308 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) 309 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) 310 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) 311 312 static struct hlist_head chainhash_table[CHAINHASH_SIZE]; 313 314 /* 315 * The hash key of the lock dependency chains is a hash itself too: 316 * it's a hash of all locks taken up to that lock, including that lock. 317 * It's a 64-bit hash, because it's important for the keys to be 318 * unique. 319 */ 320 static inline u64 iterate_chain_key(u64 key, u32 idx) 321 { 322 u32 k0 = key, k1 = key >> 32; 323 324 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */ 325 326 return k0 | (u64)k1 << 32; 327 } 328 329 void lockdep_off(void) 330 { 331 current->lockdep_recursion++; 332 } 333 EXPORT_SYMBOL(lockdep_off); 334 335 void lockdep_on(void) 336 { 337 current->lockdep_recursion--; 338 } 339 EXPORT_SYMBOL(lockdep_on); 340 341 /* 342 * Debugging switches: 343 */ 344 345 #define VERBOSE 0 346 #define VERY_VERBOSE 0 347 348 #if VERBOSE 349 # define HARDIRQ_VERBOSE 1 350 # define SOFTIRQ_VERBOSE 1 351 #else 352 # define HARDIRQ_VERBOSE 0 353 # define SOFTIRQ_VERBOSE 0 354 #endif 355 356 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE 357 /* 358 * Quick filtering for interesting events: 359 */ 360 static int class_filter(struct lock_class *class) 361 { 362 #if 0 363 /* Example */ 364 if (class->name_version == 1 && 365 !strcmp(class->name, "lockname")) 366 return 1; 367 if (class->name_version == 1 && 368 !strcmp(class->name, "&struct->lockfield")) 369 return 1; 370 #endif 371 /* Filter everything else. 1 would be to allow everything else */ 372 return 0; 373 } 374 #endif 375 376 static int verbose(struct lock_class *class) 377 { 378 #if VERBOSE 379 return class_filter(class); 380 #endif 381 return 0; 382 } 383 384 /* 385 * Stack-trace: tightly packed array of stack backtrace 386 * addresses. Protected by the graph_lock. 387 */ 388 unsigned long nr_stack_trace_entries; 389 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; 390 391 static void print_lockdep_off(const char *bug_msg) 392 { 393 printk(KERN_DEBUG "%s\n", bug_msg); 394 printk(KERN_DEBUG "turning off the locking correctness validator.\n"); 395 #ifdef CONFIG_LOCK_STAT 396 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n"); 397 #endif 398 } 399 400 static int save_trace(struct stack_trace *trace) 401 { 402 trace->nr_entries = 0; 403 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; 404 trace->entries = stack_trace + nr_stack_trace_entries; 405 406 trace->skip = 3; 407 408 save_stack_trace(trace); 409 410 /* 411 * Some daft arches put -1 at the end to indicate its a full trace. 412 * 413 * <rant> this is buggy anyway, since it takes a whole extra entry so a 414 * complete trace that maxes out the entries provided will be reported 415 * as incomplete, friggin useless </rant> 416 */ 417 if (trace->nr_entries != 0 && 418 trace->entries[trace->nr_entries-1] == ULONG_MAX) 419 trace->nr_entries--; 420 421 trace->max_entries = trace->nr_entries; 422 423 nr_stack_trace_entries += trace->nr_entries; 424 425 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { 426 if (!debug_locks_off_graph_unlock()) 427 return 0; 428 429 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); 430 dump_stack(); 431 432 return 0; 433 } 434 435 return 1; 436 } 437 438 unsigned int nr_hardirq_chains; 439 unsigned int nr_softirq_chains; 440 unsigned int nr_process_chains; 441 unsigned int max_lockdep_depth; 442 443 #ifdef CONFIG_DEBUG_LOCKDEP 444 /* 445 * Various lockdep statistics: 446 */ 447 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); 448 #endif 449 450 /* 451 * Locking printouts: 452 */ 453 454 #define __USAGE(__STATE) \ 455 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ 456 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ 457 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ 458 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", 459 460 static const char *usage_str[] = 461 { 462 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) 463 #include "lockdep_states.h" 464 #undef LOCKDEP_STATE 465 [LOCK_USED] = "INITIAL USE", 466 }; 467 468 const char * __get_key_name(struct lockdep_subclass_key *key, char *str) 469 { 470 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); 471 } 472 473 static inline unsigned long lock_flag(enum lock_usage_bit bit) 474 { 475 return 1UL << bit; 476 } 477 478 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) 479 { 480 char c = '.'; 481 482 if (class->usage_mask & lock_flag(bit + 2)) 483 c = '+'; 484 if (class->usage_mask & lock_flag(bit)) { 485 c = '-'; 486 if (class->usage_mask & lock_flag(bit + 2)) 487 c = '?'; 488 } 489 490 return c; 491 } 492 493 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) 494 { 495 int i = 0; 496 497 #define LOCKDEP_STATE(__STATE) \ 498 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ 499 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); 500 #include "lockdep_states.h" 501 #undef LOCKDEP_STATE 502 503 usage[i] = '\0'; 504 } 505 506 static void __print_lock_name(struct lock_class *class) 507 { 508 char str[KSYM_NAME_LEN]; 509 const char *name; 510 511 name = class->name; 512 if (!name) { 513 name = __get_key_name(class->key, str); 514 printk(KERN_CONT "%s", name); 515 } else { 516 printk(KERN_CONT "%s", name); 517 if (class->name_version > 1) 518 printk(KERN_CONT "#%d", class->name_version); 519 if (class->subclass) 520 printk(KERN_CONT "/%d", class->subclass); 521 } 522 } 523 524 static void print_lock_name(struct lock_class *class) 525 { 526 char usage[LOCK_USAGE_CHARS]; 527 528 get_usage_chars(class, usage); 529 530 printk(KERN_CONT " ("); 531 __print_lock_name(class); 532 printk(KERN_CONT "){%s}", usage); 533 } 534 535 static void print_lockdep_cache(struct lockdep_map *lock) 536 { 537 const char *name; 538 char str[KSYM_NAME_LEN]; 539 540 name = lock->name; 541 if (!name) 542 name = __get_key_name(lock->key->subkeys, str); 543 544 printk(KERN_CONT "%s", name); 545 } 546 547 static void print_lock(struct held_lock *hlock) 548 { 549 /* 550 * We can be called locklessly through debug_show_all_locks() so be 551 * extra careful, the hlock might have been released and cleared. 552 */ 553 unsigned int class_idx = hlock->class_idx; 554 555 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */ 556 barrier(); 557 558 if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) { 559 printk(KERN_CONT "<RELEASED>\n"); 560 return; 561 } 562 563 print_lock_name(lock_classes + class_idx - 1); 564 printk(KERN_CONT ", at: [<%p>] %pS\n", 565 (void *)hlock->acquire_ip, (void *)hlock->acquire_ip); 566 } 567 568 static void lockdep_print_held_locks(struct task_struct *curr) 569 { 570 int i, depth = curr->lockdep_depth; 571 572 if (!depth) { 573 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr)); 574 return; 575 } 576 printk("%d lock%s held by %s/%d:\n", 577 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr)); 578 579 for (i = 0; i < depth; i++) { 580 printk(" #%d: ", i); 581 print_lock(curr->held_locks + i); 582 } 583 } 584 585 static void print_kernel_ident(void) 586 { 587 printk("%s %.*s %s\n", init_utsname()->release, 588 (int)strcspn(init_utsname()->version, " "), 589 init_utsname()->version, 590 print_tainted()); 591 } 592 593 static int very_verbose(struct lock_class *class) 594 { 595 #if VERY_VERBOSE 596 return class_filter(class); 597 #endif 598 return 0; 599 } 600 601 /* 602 * Is this the address of a static object: 603 */ 604 #ifdef __KERNEL__ 605 static int static_obj(void *obj) 606 { 607 unsigned long start = (unsigned long) &_stext, 608 end = (unsigned long) &_end, 609 addr = (unsigned long) obj; 610 611 /* 612 * static variable? 613 */ 614 if ((addr >= start) && (addr < end)) 615 return 1; 616 617 if (arch_is_kernel_data(addr)) 618 return 1; 619 620 /* 621 * in-kernel percpu var? 622 */ 623 if (is_kernel_percpu_address(addr)) 624 return 1; 625 626 /* 627 * module static or percpu var? 628 */ 629 return is_module_address(addr) || is_module_percpu_address(addr); 630 } 631 #endif 632 633 /* 634 * To make lock name printouts unique, we calculate a unique 635 * class->name_version generation counter: 636 */ 637 static int count_matching_names(struct lock_class *new_class) 638 { 639 struct lock_class *class; 640 int count = 0; 641 642 if (!new_class->name) 643 return 0; 644 645 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) { 646 if (new_class->key - new_class->subclass == class->key) 647 return class->name_version; 648 if (class->name && !strcmp(class->name, new_class->name)) 649 count = max(count, class->name_version); 650 } 651 652 return count + 1; 653 } 654 655 /* 656 * Register a lock's class in the hash-table, if the class is not present 657 * yet. Otherwise we look it up. We cache the result in the lock object 658 * itself, so actual lookup of the hash should be once per lock object. 659 */ 660 static inline struct lock_class * 661 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) 662 { 663 struct lockdep_subclass_key *key; 664 struct hlist_head *hash_head; 665 struct lock_class *class; 666 bool is_static = false; 667 668 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { 669 debug_locks_off(); 670 printk(KERN_ERR 671 "BUG: looking up invalid subclass: %u\n", subclass); 672 printk(KERN_ERR 673 "turning off the locking correctness validator.\n"); 674 dump_stack(); 675 return NULL; 676 } 677 678 /* 679 * Static locks do not have their class-keys yet - for them the key 680 * is the lock object itself. If the lock is in the per cpu area, 681 * the canonical address of the lock (per cpu offset removed) is 682 * used. 683 */ 684 if (unlikely(!lock->key)) { 685 unsigned long can_addr, addr = (unsigned long)lock; 686 687 if (__is_kernel_percpu_address(addr, &can_addr)) 688 lock->key = (void *)can_addr; 689 else if (__is_module_percpu_address(addr, &can_addr)) 690 lock->key = (void *)can_addr; 691 else if (static_obj(lock)) 692 lock->key = (void *)lock; 693 else 694 return ERR_PTR(-EINVAL); 695 is_static = true; 696 } 697 698 /* 699 * NOTE: the class-key must be unique. For dynamic locks, a static 700 * lock_class_key variable is passed in through the mutex_init() 701 * (or spin_lock_init()) call - which acts as the key. For static 702 * locks we use the lock object itself as the key. 703 */ 704 BUILD_BUG_ON(sizeof(struct lock_class_key) > 705 sizeof(struct lockdep_map)); 706 707 key = lock->key->subkeys + subclass; 708 709 hash_head = classhashentry(key); 710 711 /* 712 * We do an RCU walk of the hash, see lockdep_free_key_range(). 713 */ 714 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) 715 return NULL; 716 717 hlist_for_each_entry_rcu(class, hash_head, hash_entry) { 718 if (class->key == key) { 719 /* 720 * Huh! same key, different name? Did someone trample 721 * on some memory? We're most confused. 722 */ 723 WARN_ON_ONCE(class->name != lock->name); 724 return class; 725 } 726 } 727 728 return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL); 729 } 730 731 #ifdef CONFIG_LOCKDEP_CROSSRELEASE 732 static void cross_init(struct lockdep_map *lock, int cross); 733 static int cross_lock(struct lockdep_map *lock); 734 static int lock_acquire_crosslock(struct held_lock *hlock); 735 static int lock_release_crosslock(struct lockdep_map *lock); 736 #else 737 static inline void cross_init(struct lockdep_map *lock, int cross) {} 738 static inline int cross_lock(struct lockdep_map *lock) { return 0; } 739 static inline int lock_acquire_crosslock(struct held_lock *hlock) { return 2; } 740 static inline int lock_release_crosslock(struct lockdep_map *lock) { return 2; } 741 #endif 742 743 /* 744 * Register a lock's class in the hash-table, if the class is not present 745 * yet. Otherwise we look it up. We cache the result in the lock object 746 * itself, so actual lookup of the hash should be once per lock object. 747 */ 748 static struct lock_class * 749 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) 750 { 751 struct lockdep_subclass_key *key; 752 struct hlist_head *hash_head; 753 struct lock_class *class; 754 755 DEBUG_LOCKS_WARN_ON(!irqs_disabled()); 756 757 class = look_up_lock_class(lock, subclass); 758 if (likely(!IS_ERR_OR_NULL(class))) 759 goto out_set_class_cache; 760 761 /* 762 * Debug-check: all keys must be persistent! 763 */ 764 if (IS_ERR(class)) { 765 debug_locks_off(); 766 printk("INFO: trying to register non-static key.\n"); 767 printk("the code is fine but needs lockdep annotation.\n"); 768 printk("turning off the locking correctness validator.\n"); 769 dump_stack(); 770 return NULL; 771 } 772 773 key = lock->key->subkeys + subclass; 774 hash_head = classhashentry(key); 775 776 if (!graph_lock()) { 777 return NULL; 778 } 779 /* 780 * We have to do the hash-walk again, to avoid races 781 * with another CPU: 782 */ 783 hlist_for_each_entry_rcu(class, hash_head, hash_entry) { 784 if (class->key == key) 785 goto out_unlock_set; 786 } 787 788 /* 789 * Allocate a new key from the static array, and add it to 790 * the hash: 791 */ 792 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { 793 if (!debug_locks_off_graph_unlock()) { 794 return NULL; 795 } 796 797 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!"); 798 dump_stack(); 799 return NULL; 800 } 801 class = lock_classes + nr_lock_classes++; 802 debug_atomic_inc(nr_unused_locks); 803 class->key = key; 804 class->name = lock->name; 805 class->subclass = subclass; 806 INIT_LIST_HEAD(&class->lock_entry); 807 INIT_LIST_HEAD(&class->locks_before); 808 INIT_LIST_HEAD(&class->locks_after); 809 class->name_version = count_matching_names(class); 810 /* 811 * We use RCU's safe list-add method to make 812 * parallel walking of the hash-list safe: 813 */ 814 hlist_add_head_rcu(&class->hash_entry, hash_head); 815 /* 816 * Add it to the global list of classes: 817 */ 818 list_add_tail_rcu(&class->lock_entry, &all_lock_classes); 819 820 if (verbose(class)) { 821 graph_unlock(); 822 823 printk("\nnew class %p: %s", class->key, class->name); 824 if (class->name_version > 1) 825 printk(KERN_CONT "#%d", class->name_version); 826 printk(KERN_CONT "\n"); 827 dump_stack(); 828 829 if (!graph_lock()) { 830 return NULL; 831 } 832 } 833 out_unlock_set: 834 graph_unlock(); 835 836 out_set_class_cache: 837 if (!subclass || force) 838 lock->class_cache[0] = class; 839 else if (subclass < NR_LOCKDEP_CACHING_CLASSES) 840 lock->class_cache[subclass] = class; 841 842 /* 843 * Hash collision, did we smoke some? We found a class with a matching 844 * hash but the subclass -- which is hashed in -- didn't match. 845 */ 846 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) 847 return NULL; 848 849 return class; 850 } 851 852 #ifdef CONFIG_PROVE_LOCKING 853 /* 854 * Allocate a lockdep entry. (assumes the graph_lock held, returns 855 * with NULL on failure) 856 */ 857 static struct lock_list *alloc_list_entry(void) 858 { 859 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { 860 if (!debug_locks_off_graph_unlock()) 861 return NULL; 862 863 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!"); 864 dump_stack(); 865 return NULL; 866 } 867 return list_entries + nr_list_entries++; 868 } 869 870 /* 871 * Add a new dependency to the head of the list: 872 */ 873 static int add_lock_to_list(struct lock_class *this, struct list_head *head, 874 unsigned long ip, int distance, 875 struct stack_trace *trace) 876 { 877 struct lock_list *entry; 878 /* 879 * Lock not present yet - get a new dependency struct and 880 * add it to the list: 881 */ 882 entry = alloc_list_entry(); 883 if (!entry) 884 return 0; 885 886 entry->class = this; 887 entry->distance = distance; 888 entry->trace = *trace; 889 /* 890 * Both allocation and removal are done under the graph lock; but 891 * iteration is under RCU-sched; see look_up_lock_class() and 892 * lockdep_free_key_range(). 893 */ 894 list_add_tail_rcu(&entry->entry, head); 895 896 return 1; 897 } 898 899 /* 900 * For good efficiency of modular, we use power of 2 901 */ 902 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL 903 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) 904 905 /* 906 * The circular_queue and helpers is used to implement the 907 * breadth-first search(BFS)algorithem, by which we can build 908 * the shortest path from the next lock to be acquired to the 909 * previous held lock if there is a circular between them. 910 */ 911 struct circular_queue { 912 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE]; 913 unsigned int front, rear; 914 }; 915 916 static struct circular_queue lock_cq; 917 918 unsigned int max_bfs_queue_depth; 919 920 static unsigned int lockdep_dependency_gen_id; 921 922 static inline void __cq_init(struct circular_queue *cq) 923 { 924 cq->front = cq->rear = 0; 925 lockdep_dependency_gen_id++; 926 } 927 928 static inline int __cq_empty(struct circular_queue *cq) 929 { 930 return (cq->front == cq->rear); 931 } 932 933 static inline int __cq_full(struct circular_queue *cq) 934 { 935 return ((cq->rear + 1) & CQ_MASK) == cq->front; 936 } 937 938 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) 939 { 940 if (__cq_full(cq)) 941 return -1; 942 943 cq->element[cq->rear] = elem; 944 cq->rear = (cq->rear + 1) & CQ_MASK; 945 return 0; 946 } 947 948 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) 949 { 950 if (__cq_empty(cq)) 951 return -1; 952 953 *elem = cq->element[cq->front]; 954 cq->front = (cq->front + 1) & CQ_MASK; 955 return 0; 956 } 957 958 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) 959 { 960 return (cq->rear - cq->front) & CQ_MASK; 961 } 962 963 static inline void mark_lock_accessed(struct lock_list *lock, 964 struct lock_list *parent) 965 { 966 unsigned long nr; 967 968 nr = lock - list_entries; 969 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ 970 lock->parent = parent; 971 lock->class->dep_gen_id = lockdep_dependency_gen_id; 972 } 973 974 static inline unsigned long lock_accessed(struct lock_list *lock) 975 { 976 unsigned long nr; 977 978 nr = lock - list_entries; 979 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ 980 return lock->class->dep_gen_id == lockdep_dependency_gen_id; 981 } 982 983 static inline struct lock_list *get_lock_parent(struct lock_list *child) 984 { 985 return child->parent; 986 } 987 988 static inline int get_lock_depth(struct lock_list *child) 989 { 990 int depth = 0; 991 struct lock_list *parent; 992 993 while ((parent = get_lock_parent(child))) { 994 child = parent; 995 depth++; 996 } 997 return depth; 998 } 999 1000 static int __bfs(struct lock_list *source_entry, 1001 void *data, 1002 int (*match)(struct lock_list *entry, void *data), 1003 struct lock_list **target_entry, 1004 int forward) 1005 { 1006 struct lock_list *entry; 1007 struct list_head *head; 1008 struct circular_queue *cq = &lock_cq; 1009 int ret = 1; 1010 1011 if (match(source_entry, data)) { 1012 *target_entry = source_entry; 1013 ret = 0; 1014 goto exit; 1015 } 1016 1017 if (forward) 1018 head = &source_entry->class->locks_after; 1019 else 1020 head = &source_entry->class->locks_before; 1021 1022 if (list_empty(head)) 1023 goto exit; 1024 1025 __cq_init(cq); 1026 __cq_enqueue(cq, (unsigned long)source_entry); 1027 1028 while (!__cq_empty(cq)) { 1029 struct lock_list *lock; 1030 1031 __cq_dequeue(cq, (unsigned long *)&lock); 1032 1033 if (!lock->class) { 1034 ret = -2; 1035 goto exit; 1036 } 1037 1038 if (forward) 1039 head = &lock->class->locks_after; 1040 else 1041 head = &lock->class->locks_before; 1042 1043 DEBUG_LOCKS_WARN_ON(!irqs_disabled()); 1044 1045 list_for_each_entry_rcu(entry, head, entry) { 1046 if (!lock_accessed(entry)) { 1047 unsigned int cq_depth; 1048 mark_lock_accessed(entry, lock); 1049 if (match(entry, data)) { 1050 *target_entry = entry; 1051 ret = 0; 1052 goto exit; 1053 } 1054 1055 if (__cq_enqueue(cq, (unsigned long)entry)) { 1056 ret = -1; 1057 goto exit; 1058 } 1059 cq_depth = __cq_get_elem_count(cq); 1060 if (max_bfs_queue_depth < cq_depth) 1061 max_bfs_queue_depth = cq_depth; 1062 } 1063 } 1064 } 1065 exit: 1066 return ret; 1067 } 1068 1069 static inline int __bfs_forwards(struct lock_list *src_entry, 1070 void *data, 1071 int (*match)(struct lock_list *entry, void *data), 1072 struct lock_list **target_entry) 1073 { 1074 return __bfs(src_entry, data, match, target_entry, 1); 1075 1076 } 1077 1078 static inline int __bfs_backwards(struct lock_list *src_entry, 1079 void *data, 1080 int (*match)(struct lock_list *entry, void *data), 1081 struct lock_list **target_entry) 1082 { 1083 return __bfs(src_entry, data, match, target_entry, 0); 1084 1085 } 1086 1087 /* 1088 * Recursive, forwards-direction lock-dependency checking, used for 1089 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe 1090 * checking. 1091 */ 1092 1093 /* 1094 * Print a dependency chain entry (this is only done when a deadlock 1095 * has been detected): 1096 */ 1097 static noinline int 1098 print_circular_bug_entry(struct lock_list *target, int depth) 1099 { 1100 if (debug_locks_silent) 1101 return 0; 1102 printk("\n-> #%u", depth); 1103 print_lock_name(target->class); 1104 printk(KERN_CONT ":\n"); 1105 print_stack_trace(&target->trace, 6); 1106 1107 return 0; 1108 } 1109 1110 static void 1111 print_circular_lock_scenario(struct held_lock *src, 1112 struct held_lock *tgt, 1113 struct lock_list *prt) 1114 { 1115 struct lock_class *source = hlock_class(src); 1116 struct lock_class *target = hlock_class(tgt); 1117 struct lock_class *parent = prt->class; 1118 1119 /* 1120 * A direct locking problem where unsafe_class lock is taken 1121 * directly by safe_class lock, then all we need to show 1122 * is the deadlock scenario, as it is obvious that the 1123 * unsafe lock is taken under the safe lock. 1124 * 1125 * But if there is a chain instead, where the safe lock takes 1126 * an intermediate lock (middle_class) where this lock is 1127 * not the same as the safe lock, then the lock chain is 1128 * used to describe the problem. Otherwise we would need 1129 * to show a different CPU case for each link in the chain 1130 * from the safe_class lock to the unsafe_class lock. 1131 */ 1132 if (parent != source) { 1133 printk("Chain exists of:\n "); 1134 __print_lock_name(source); 1135 printk(KERN_CONT " --> "); 1136 __print_lock_name(parent); 1137 printk(KERN_CONT " --> "); 1138 __print_lock_name(target); 1139 printk(KERN_CONT "\n\n"); 1140 } 1141 1142 if (cross_lock(tgt->instance)) { 1143 printk(" Possible unsafe locking scenario by crosslock:\n\n"); 1144 printk(" CPU0 CPU1\n"); 1145 printk(" ---- ----\n"); 1146 printk(" lock("); 1147 __print_lock_name(parent); 1148 printk(KERN_CONT ");\n"); 1149 printk(" lock("); 1150 __print_lock_name(target); 1151 printk(KERN_CONT ");\n"); 1152 printk(" lock("); 1153 __print_lock_name(source); 1154 printk(KERN_CONT ");\n"); 1155 printk(" unlock("); 1156 __print_lock_name(target); 1157 printk(KERN_CONT ");\n"); 1158 printk("\n *** DEADLOCK ***\n\n"); 1159 } else { 1160 printk(" Possible unsafe locking scenario:\n\n"); 1161 printk(" CPU0 CPU1\n"); 1162 printk(" ---- ----\n"); 1163 printk(" lock("); 1164 __print_lock_name(target); 1165 printk(KERN_CONT ");\n"); 1166 printk(" lock("); 1167 __print_lock_name(parent); 1168 printk(KERN_CONT ");\n"); 1169 printk(" lock("); 1170 __print_lock_name(target); 1171 printk(KERN_CONT ");\n"); 1172 printk(" lock("); 1173 __print_lock_name(source); 1174 printk(KERN_CONT ");\n"); 1175 printk("\n *** DEADLOCK ***\n\n"); 1176 } 1177 } 1178 1179 /* 1180 * When a circular dependency is detected, print the 1181 * header first: 1182 */ 1183 static noinline int 1184 print_circular_bug_header(struct lock_list *entry, unsigned int depth, 1185 struct held_lock *check_src, 1186 struct held_lock *check_tgt) 1187 { 1188 struct task_struct *curr = current; 1189 1190 if (debug_locks_silent) 1191 return 0; 1192 1193 pr_warn("\n"); 1194 pr_warn("======================================================\n"); 1195 pr_warn("WARNING: possible circular locking dependency detected\n"); 1196 print_kernel_ident(); 1197 pr_warn("------------------------------------------------------\n"); 1198 pr_warn("%s/%d is trying to acquire lock:\n", 1199 curr->comm, task_pid_nr(curr)); 1200 print_lock(check_src); 1201 1202 if (cross_lock(check_tgt->instance)) 1203 pr_warn("\nbut now in release context of a crosslock acquired at the following:\n"); 1204 else 1205 pr_warn("\nbut task is already holding lock:\n"); 1206 1207 print_lock(check_tgt); 1208 pr_warn("\nwhich lock already depends on the new lock.\n\n"); 1209 pr_warn("\nthe existing dependency chain (in reverse order) is:\n"); 1210 1211 print_circular_bug_entry(entry, depth); 1212 1213 return 0; 1214 } 1215 1216 static inline int class_equal(struct lock_list *entry, void *data) 1217 { 1218 return entry->class == data; 1219 } 1220 1221 static noinline int print_circular_bug(struct lock_list *this, 1222 struct lock_list *target, 1223 struct held_lock *check_src, 1224 struct held_lock *check_tgt, 1225 struct stack_trace *trace) 1226 { 1227 struct task_struct *curr = current; 1228 struct lock_list *parent; 1229 struct lock_list *first_parent; 1230 int depth; 1231 1232 if (!debug_locks_off_graph_unlock() || debug_locks_silent) 1233 return 0; 1234 1235 if (cross_lock(check_tgt->instance)) 1236 this->trace = *trace; 1237 else if (!save_trace(&this->trace)) 1238 return 0; 1239 1240 depth = get_lock_depth(target); 1241 1242 print_circular_bug_header(target, depth, check_src, check_tgt); 1243 1244 parent = get_lock_parent(target); 1245 first_parent = parent; 1246 1247 while (parent) { 1248 print_circular_bug_entry(parent, --depth); 1249 parent = get_lock_parent(parent); 1250 } 1251 1252 printk("\nother info that might help us debug this:\n\n"); 1253 print_circular_lock_scenario(check_src, check_tgt, 1254 first_parent); 1255 1256 lockdep_print_held_locks(curr); 1257 1258 printk("\nstack backtrace:\n"); 1259 dump_stack(); 1260 1261 return 0; 1262 } 1263 1264 static noinline int print_bfs_bug(int ret) 1265 { 1266 if (!debug_locks_off_graph_unlock()) 1267 return 0; 1268 1269 /* 1270 * Breadth-first-search failed, graph got corrupted? 1271 */ 1272 WARN(1, "lockdep bfs error:%d\n", ret); 1273 1274 return 0; 1275 } 1276 1277 static int noop_count(struct lock_list *entry, void *data) 1278 { 1279 (*(unsigned long *)data)++; 1280 return 0; 1281 } 1282 1283 static unsigned long __lockdep_count_forward_deps(struct lock_list *this) 1284 { 1285 unsigned long count = 0; 1286 struct lock_list *uninitialized_var(target_entry); 1287 1288 __bfs_forwards(this, (void *)&count, noop_count, &target_entry); 1289 1290 return count; 1291 } 1292 unsigned long lockdep_count_forward_deps(struct lock_class *class) 1293 { 1294 unsigned long ret, flags; 1295 struct lock_list this; 1296 1297 this.parent = NULL; 1298 this.class = class; 1299 1300 local_irq_save(flags); 1301 arch_spin_lock(&lockdep_lock); 1302 ret = __lockdep_count_forward_deps(&this); 1303 arch_spin_unlock(&lockdep_lock); 1304 local_irq_restore(flags); 1305 1306 return ret; 1307 } 1308 1309 static unsigned long __lockdep_count_backward_deps(struct lock_list *this) 1310 { 1311 unsigned long count = 0; 1312 struct lock_list *uninitialized_var(target_entry); 1313 1314 __bfs_backwards(this, (void *)&count, noop_count, &target_entry); 1315 1316 return count; 1317 } 1318 1319 unsigned long lockdep_count_backward_deps(struct lock_class *class) 1320 { 1321 unsigned long ret, flags; 1322 struct lock_list this; 1323 1324 this.parent = NULL; 1325 this.class = class; 1326 1327 local_irq_save(flags); 1328 arch_spin_lock(&lockdep_lock); 1329 ret = __lockdep_count_backward_deps(&this); 1330 arch_spin_unlock(&lockdep_lock); 1331 local_irq_restore(flags); 1332 1333 return ret; 1334 } 1335 1336 /* 1337 * Prove that the dependency graph starting at <entry> can not 1338 * lead to <target>. Print an error and return 0 if it does. 1339 */ 1340 static noinline int 1341 check_noncircular(struct lock_list *root, struct lock_class *target, 1342 struct lock_list **target_entry) 1343 { 1344 int result; 1345 1346 debug_atomic_inc(nr_cyclic_checks); 1347 1348 result = __bfs_forwards(root, target, class_equal, target_entry); 1349 1350 return result; 1351 } 1352 1353 static noinline int 1354 check_redundant(struct lock_list *root, struct lock_class *target, 1355 struct lock_list **target_entry) 1356 { 1357 int result; 1358 1359 debug_atomic_inc(nr_redundant_checks); 1360 1361 result = __bfs_forwards(root, target, class_equal, target_entry); 1362 1363 return result; 1364 } 1365 1366 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) 1367 /* 1368 * Forwards and backwards subgraph searching, for the purposes of 1369 * proving that two subgraphs can be connected by a new dependency 1370 * without creating any illegal irq-safe -> irq-unsafe lock dependency. 1371 */ 1372 1373 static inline int usage_match(struct lock_list *entry, void *bit) 1374 { 1375 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); 1376 } 1377 1378 1379 1380 /* 1381 * Find a node in the forwards-direction dependency sub-graph starting 1382 * at @root->class that matches @bit. 1383 * 1384 * Return 0 if such a node exists in the subgraph, and put that node 1385 * into *@target_entry. 1386 * 1387 * Return 1 otherwise and keep *@target_entry unchanged. 1388 * Return <0 on error. 1389 */ 1390 static int 1391 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, 1392 struct lock_list **target_entry) 1393 { 1394 int result; 1395 1396 debug_atomic_inc(nr_find_usage_forwards_checks); 1397 1398 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); 1399 1400 return result; 1401 } 1402 1403 /* 1404 * Find a node in the backwards-direction dependency sub-graph starting 1405 * at @root->class that matches @bit. 1406 * 1407 * Return 0 if such a node exists in the subgraph, and put that node 1408 * into *@target_entry. 1409 * 1410 * Return 1 otherwise and keep *@target_entry unchanged. 1411 * Return <0 on error. 1412 */ 1413 static int 1414 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, 1415 struct lock_list **target_entry) 1416 { 1417 int result; 1418 1419 debug_atomic_inc(nr_find_usage_backwards_checks); 1420 1421 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); 1422 1423 return result; 1424 } 1425 1426 static void print_lock_class_header(struct lock_class *class, int depth) 1427 { 1428 int bit; 1429 1430 printk("%*s->", depth, ""); 1431 print_lock_name(class); 1432 printk(KERN_CONT " ops: %lu", class->ops); 1433 printk(KERN_CONT " {\n"); 1434 1435 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { 1436 if (class->usage_mask & (1 << bit)) { 1437 int len = depth; 1438 1439 len += printk("%*s %s", depth, "", usage_str[bit]); 1440 len += printk(KERN_CONT " at:\n"); 1441 print_stack_trace(class->usage_traces + bit, len); 1442 } 1443 } 1444 printk("%*s }\n", depth, ""); 1445 1446 printk("%*s ... key at: [<%p>] %pS\n", 1447 depth, "", class->key, class->key); 1448 } 1449 1450 /* 1451 * printk the shortest lock dependencies from @start to @end in reverse order: 1452 */ 1453 static void __used 1454 print_shortest_lock_dependencies(struct lock_list *leaf, 1455 struct lock_list *root) 1456 { 1457 struct lock_list *entry = leaf; 1458 int depth; 1459 1460 /*compute depth from generated tree by BFS*/ 1461 depth = get_lock_depth(leaf); 1462 1463 do { 1464 print_lock_class_header(entry->class, depth); 1465 printk("%*s ... acquired at:\n", depth, ""); 1466 print_stack_trace(&entry->trace, 2); 1467 printk("\n"); 1468 1469 if (depth == 0 && (entry != root)) { 1470 printk("lockdep:%s bad path found in chain graph\n", __func__); 1471 break; 1472 } 1473 1474 entry = get_lock_parent(entry); 1475 depth--; 1476 } while (entry && (depth >= 0)); 1477 1478 return; 1479 } 1480 1481 static void 1482 print_irq_lock_scenario(struct lock_list *safe_entry, 1483 struct lock_list *unsafe_entry, 1484 struct lock_class *prev_class, 1485 struct lock_class *next_class) 1486 { 1487 struct lock_class *safe_class = safe_entry->class; 1488 struct lock_class *unsafe_class = unsafe_entry->class; 1489 struct lock_class *middle_class = prev_class; 1490 1491 if (middle_class == safe_class) 1492 middle_class = next_class; 1493 1494 /* 1495 * A direct locking problem where unsafe_class lock is taken 1496 * directly by safe_class lock, then all we need to show 1497 * is the deadlock scenario, as it is obvious that the 1498 * unsafe lock is taken under the safe lock. 1499 * 1500 * But if there is a chain instead, where the safe lock takes 1501 * an intermediate lock (middle_class) where this lock is 1502 * not the same as the safe lock, then the lock chain is 1503 * used to describe the problem. Otherwise we would need 1504 * to show a different CPU case for each link in the chain 1505 * from the safe_class lock to the unsafe_class lock. 1506 */ 1507 if (middle_class != unsafe_class) { 1508 printk("Chain exists of:\n "); 1509 __print_lock_name(safe_class); 1510 printk(KERN_CONT " --> "); 1511 __print_lock_name(middle_class); 1512 printk(KERN_CONT " --> "); 1513 __print_lock_name(unsafe_class); 1514 printk(KERN_CONT "\n\n"); 1515 } 1516 1517 printk(" Possible interrupt unsafe locking scenario:\n\n"); 1518 printk(" CPU0 CPU1\n"); 1519 printk(" ---- ----\n"); 1520 printk(" lock("); 1521 __print_lock_name(unsafe_class); 1522 printk(KERN_CONT ");\n"); 1523 printk(" local_irq_disable();\n"); 1524 printk(" lock("); 1525 __print_lock_name(safe_class); 1526 printk(KERN_CONT ");\n"); 1527 printk(" lock("); 1528 __print_lock_name(middle_class); 1529 printk(KERN_CONT ");\n"); 1530 printk(" <Interrupt>\n"); 1531 printk(" lock("); 1532 __print_lock_name(safe_class); 1533 printk(KERN_CONT ");\n"); 1534 printk("\n *** DEADLOCK ***\n\n"); 1535 } 1536 1537 static int 1538 print_bad_irq_dependency(struct task_struct *curr, 1539 struct lock_list *prev_root, 1540 struct lock_list *next_root, 1541 struct lock_list *backwards_entry, 1542 struct lock_list *forwards_entry, 1543 struct held_lock *prev, 1544 struct held_lock *next, 1545 enum lock_usage_bit bit1, 1546 enum lock_usage_bit bit2, 1547 const char *irqclass) 1548 { 1549 if (!debug_locks_off_graph_unlock() || debug_locks_silent) 1550 return 0; 1551 1552 pr_warn("\n"); 1553 pr_warn("=====================================================\n"); 1554 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n", 1555 irqclass, irqclass); 1556 print_kernel_ident(); 1557 pr_warn("-----------------------------------------------------\n"); 1558 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", 1559 curr->comm, task_pid_nr(curr), 1560 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, 1561 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, 1562 curr->hardirqs_enabled, 1563 curr->softirqs_enabled); 1564 print_lock(next); 1565 1566 pr_warn("\nand this task is already holding:\n"); 1567 print_lock(prev); 1568 pr_warn("which would create a new lock dependency:\n"); 1569 print_lock_name(hlock_class(prev)); 1570 pr_cont(" ->"); 1571 print_lock_name(hlock_class(next)); 1572 pr_cont("\n"); 1573 1574 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n", 1575 irqclass); 1576 print_lock_name(backwards_entry->class); 1577 pr_warn("\n... which became %s-irq-safe at:\n", irqclass); 1578 1579 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); 1580 1581 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass); 1582 print_lock_name(forwards_entry->class); 1583 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass); 1584 pr_warn("..."); 1585 1586 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); 1587 1588 pr_warn("\nother info that might help us debug this:\n\n"); 1589 print_irq_lock_scenario(backwards_entry, forwards_entry, 1590 hlock_class(prev), hlock_class(next)); 1591 1592 lockdep_print_held_locks(curr); 1593 1594 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); 1595 if (!save_trace(&prev_root->trace)) 1596 return 0; 1597 print_shortest_lock_dependencies(backwards_entry, prev_root); 1598 1599 pr_warn("\nthe dependencies between the lock to be acquired"); 1600 pr_warn(" and %s-irq-unsafe lock:\n", irqclass); 1601 if (!save_trace(&next_root->trace)) 1602 return 0; 1603 print_shortest_lock_dependencies(forwards_entry, next_root); 1604 1605 pr_warn("\nstack backtrace:\n"); 1606 dump_stack(); 1607 1608 return 0; 1609 } 1610 1611 static int 1612 check_usage(struct task_struct *curr, struct held_lock *prev, 1613 struct held_lock *next, enum lock_usage_bit bit_backwards, 1614 enum lock_usage_bit bit_forwards, const char *irqclass) 1615 { 1616 int ret; 1617 struct lock_list this, that; 1618 struct lock_list *uninitialized_var(target_entry); 1619 struct lock_list *uninitialized_var(target_entry1); 1620 1621 this.parent = NULL; 1622 1623 this.class = hlock_class(prev); 1624 ret = find_usage_backwards(&this, bit_backwards, &target_entry); 1625 if (ret < 0) 1626 return print_bfs_bug(ret); 1627 if (ret == 1) 1628 return ret; 1629 1630 that.parent = NULL; 1631 that.class = hlock_class(next); 1632 ret = find_usage_forwards(&that, bit_forwards, &target_entry1); 1633 if (ret < 0) 1634 return print_bfs_bug(ret); 1635 if (ret == 1) 1636 return ret; 1637 1638 return print_bad_irq_dependency(curr, &this, &that, 1639 target_entry, target_entry1, 1640 prev, next, 1641 bit_backwards, bit_forwards, irqclass); 1642 } 1643 1644 static const char *state_names[] = { 1645 #define LOCKDEP_STATE(__STATE) \ 1646 __stringify(__STATE), 1647 #include "lockdep_states.h" 1648 #undef LOCKDEP_STATE 1649 }; 1650 1651 static const char *state_rnames[] = { 1652 #define LOCKDEP_STATE(__STATE) \ 1653 __stringify(__STATE)"-READ", 1654 #include "lockdep_states.h" 1655 #undef LOCKDEP_STATE 1656 }; 1657 1658 static inline const char *state_name(enum lock_usage_bit bit) 1659 { 1660 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2]; 1661 } 1662 1663 static int exclusive_bit(int new_bit) 1664 { 1665 /* 1666 * USED_IN 1667 * USED_IN_READ 1668 * ENABLED 1669 * ENABLED_READ 1670 * 1671 * bit 0 - write/read 1672 * bit 1 - used_in/enabled 1673 * bit 2+ state 1674 */ 1675 1676 int state = new_bit & ~3; 1677 int dir = new_bit & 2; 1678 1679 /* 1680 * keep state, bit flip the direction and strip read. 1681 */ 1682 return state | (dir ^ 2); 1683 } 1684 1685 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, 1686 struct held_lock *next, enum lock_usage_bit bit) 1687 { 1688 /* 1689 * Prove that the new dependency does not connect a hardirq-safe 1690 * lock with a hardirq-unsafe lock - to achieve this we search 1691 * the backwards-subgraph starting at <prev>, and the 1692 * forwards-subgraph starting at <next>: 1693 */ 1694 if (!check_usage(curr, prev, next, bit, 1695 exclusive_bit(bit), state_name(bit))) 1696 return 0; 1697 1698 bit++; /* _READ */ 1699 1700 /* 1701 * Prove that the new dependency does not connect a hardirq-safe-read 1702 * lock with a hardirq-unsafe lock - to achieve this we search 1703 * the backwards-subgraph starting at <prev>, and the 1704 * forwards-subgraph starting at <next>: 1705 */ 1706 if (!check_usage(curr, prev, next, bit, 1707 exclusive_bit(bit), state_name(bit))) 1708 return 0; 1709 1710 return 1; 1711 } 1712 1713 static int 1714 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, 1715 struct held_lock *next) 1716 { 1717 #define LOCKDEP_STATE(__STATE) \ 1718 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ 1719 return 0; 1720 #include "lockdep_states.h" 1721 #undef LOCKDEP_STATE 1722 1723 return 1; 1724 } 1725 1726 static void inc_chains(void) 1727 { 1728 if (current->hardirq_context) 1729 nr_hardirq_chains++; 1730 else { 1731 if (current->softirq_context) 1732 nr_softirq_chains++; 1733 else 1734 nr_process_chains++; 1735 } 1736 } 1737 1738 #else 1739 1740 static inline int 1741 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, 1742 struct held_lock *next) 1743 { 1744 return 1; 1745 } 1746 1747 static inline void inc_chains(void) 1748 { 1749 nr_process_chains++; 1750 } 1751 1752 #endif 1753 1754 static void 1755 print_deadlock_scenario(struct held_lock *nxt, 1756 struct held_lock *prv) 1757 { 1758 struct lock_class *next = hlock_class(nxt); 1759 struct lock_class *prev = hlock_class(prv); 1760 1761 printk(" Possible unsafe locking scenario:\n\n"); 1762 printk(" CPU0\n"); 1763 printk(" ----\n"); 1764 printk(" lock("); 1765 __print_lock_name(prev); 1766 printk(KERN_CONT ");\n"); 1767 printk(" lock("); 1768 __print_lock_name(next); 1769 printk(KERN_CONT ");\n"); 1770 printk("\n *** DEADLOCK ***\n\n"); 1771 printk(" May be due to missing lock nesting notation\n\n"); 1772 } 1773 1774 static int 1775 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, 1776 struct held_lock *next) 1777 { 1778 if (!debug_locks_off_graph_unlock() || debug_locks_silent) 1779 return 0; 1780 1781 pr_warn("\n"); 1782 pr_warn("============================================\n"); 1783 pr_warn("WARNING: possible recursive locking detected\n"); 1784 print_kernel_ident(); 1785 pr_warn("--------------------------------------------\n"); 1786 pr_warn("%s/%d is trying to acquire lock:\n", 1787 curr->comm, task_pid_nr(curr)); 1788 print_lock(next); 1789 pr_warn("\nbut task is already holding lock:\n"); 1790 print_lock(prev); 1791 1792 pr_warn("\nother info that might help us debug this:\n"); 1793 print_deadlock_scenario(next, prev); 1794 lockdep_print_held_locks(curr); 1795 1796 pr_warn("\nstack backtrace:\n"); 1797 dump_stack(); 1798 1799 return 0; 1800 } 1801 1802 /* 1803 * Check whether we are holding such a class already. 1804 * 1805 * (Note that this has to be done separately, because the graph cannot 1806 * detect such classes of deadlocks.) 1807 * 1808 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read 1809 */ 1810 static int 1811 check_deadlock(struct task_struct *curr, struct held_lock *next, 1812 struct lockdep_map *next_instance, int read) 1813 { 1814 struct held_lock *prev; 1815 struct held_lock *nest = NULL; 1816 int i; 1817 1818 for (i = 0; i < curr->lockdep_depth; i++) { 1819 prev = curr->held_locks + i; 1820 1821 if (prev->instance == next->nest_lock) 1822 nest = prev; 1823 1824 if (hlock_class(prev) != hlock_class(next)) 1825 continue; 1826 1827 /* 1828 * Allow read-after-read recursion of the same 1829 * lock class (i.e. read_lock(lock)+read_lock(lock)): 1830 */ 1831 if ((read == 2) && prev->read) 1832 return 2; 1833 1834 /* 1835 * We're holding the nest_lock, which serializes this lock's 1836 * nesting behaviour. 1837 */ 1838 if (nest) 1839 return 2; 1840 1841 if (cross_lock(prev->instance)) 1842 continue; 1843 1844 return print_deadlock_bug(curr, prev, next); 1845 } 1846 return 1; 1847 } 1848 1849 /* 1850 * There was a chain-cache miss, and we are about to add a new dependency 1851 * to a previous lock. We recursively validate the following rules: 1852 * 1853 * - would the adding of the <prev> -> <next> dependency create a 1854 * circular dependency in the graph? [== circular deadlock] 1855 * 1856 * - does the new prev->next dependency connect any hardirq-safe lock 1857 * (in the full backwards-subgraph starting at <prev>) with any 1858 * hardirq-unsafe lock (in the full forwards-subgraph starting at 1859 * <next>)? [== illegal lock inversion with hardirq contexts] 1860 * 1861 * - does the new prev->next dependency connect any softirq-safe lock 1862 * (in the full backwards-subgraph starting at <prev>) with any 1863 * softirq-unsafe lock (in the full forwards-subgraph starting at 1864 * <next>)? [== illegal lock inversion with softirq contexts] 1865 * 1866 * any of these scenarios could lead to a deadlock. 1867 * 1868 * Then if all the validations pass, we add the forwards and backwards 1869 * dependency. 1870 */ 1871 static int 1872 check_prev_add(struct task_struct *curr, struct held_lock *prev, 1873 struct held_lock *next, int distance, struct stack_trace *trace, 1874 int (*save)(struct stack_trace *trace)) 1875 { 1876 struct lock_list *uninitialized_var(target_entry); 1877 struct lock_list *entry; 1878 struct lock_list this; 1879 int ret; 1880 1881 /* 1882 * Prove that the new <prev> -> <next> dependency would not 1883 * create a circular dependency in the graph. (We do this by 1884 * forward-recursing into the graph starting at <next>, and 1885 * checking whether we can reach <prev>.) 1886 * 1887 * We are using global variables to control the recursion, to 1888 * keep the stackframe size of the recursive functions low: 1889 */ 1890 this.class = hlock_class(next); 1891 this.parent = NULL; 1892 ret = check_noncircular(&this, hlock_class(prev), &target_entry); 1893 if (unlikely(!ret)) { 1894 if (!trace->entries) { 1895 /* 1896 * If @save fails here, the printing might trigger 1897 * a WARN but because of the !nr_entries it should 1898 * not do bad things. 1899 */ 1900 save(trace); 1901 } 1902 return print_circular_bug(&this, target_entry, next, prev, trace); 1903 } 1904 else if (unlikely(ret < 0)) 1905 return print_bfs_bug(ret); 1906 1907 if (!check_prev_add_irq(curr, prev, next)) 1908 return 0; 1909 1910 /* 1911 * For recursive read-locks we do all the dependency checks, 1912 * but we dont store read-triggered dependencies (only 1913 * write-triggered dependencies). This ensures that only the 1914 * write-side dependencies matter, and that if for example a 1915 * write-lock never takes any other locks, then the reads are 1916 * equivalent to a NOP. 1917 */ 1918 if (next->read == 2 || prev->read == 2) 1919 return 1; 1920 /* 1921 * Is the <prev> -> <next> dependency already present? 1922 * 1923 * (this may occur even though this is a new chain: consider 1924 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 1925 * chains - the second one will be new, but L1 already has 1926 * L2 added to its dependency list, due to the first chain.) 1927 */ 1928 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { 1929 if (entry->class == hlock_class(next)) { 1930 if (distance == 1) 1931 entry->distance = 1; 1932 return 1; 1933 } 1934 } 1935 1936 /* 1937 * Is the <prev> -> <next> link redundant? 1938 */ 1939 this.class = hlock_class(prev); 1940 this.parent = NULL; 1941 ret = check_redundant(&this, hlock_class(next), &target_entry); 1942 if (!ret) { 1943 debug_atomic_inc(nr_redundant); 1944 return 2; 1945 } 1946 if (ret < 0) 1947 return print_bfs_bug(ret); 1948 1949 1950 if (!trace->entries && !save(trace)) 1951 return 0; 1952 1953 /* 1954 * Ok, all validations passed, add the new lock 1955 * to the previous lock's dependency list: 1956 */ 1957 ret = add_lock_to_list(hlock_class(next), 1958 &hlock_class(prev)->locks_after, 1959 next->acquire_ip, distance, trace); 1960 1961 if (!ret) 1962 return 0; 1963 1964 ret = add_lock_to_list(hlock_class(prev), 1965 &hlock_class(next)->locks_before, 1966 next->acquire_ip, distance, trace); 1967 if (!ret) 1968 return 0; 1969 1970 return 2; 1971 } 1972 1973 /* 1974 * Add the dependency to all directly-previous locks that are 'relevant'. 1975 * The ones that are relevant are (in increasing distance from curr): 1976 * all consecutive trylock entries and the final non-trylock entry - or 1977 * the end of this context's lock-chain - whichever comes first. 1978 */ 1979 static int 1980 check_prevs_add(struct task_struct *curr, struct held_lock *next) 1981 { 1982 int depth = curr->lockdep_depth; 1983 struct held_lock *hlock; 1984 struct stack_trace trace = { 1985 .nr_entries = 0, 1986 .max_entries = 0, 1987 .entries = NULL, 1988 .skip = 0, 1989 }; 1990 1991 /* 1992 * Debugging checks. 1993 * 1994 * Depth must not be zero for a non-head lock: 1995 */ 1996 if (!depth) 1997 goto out_bug; 1998 /* 1999 * At least two relevant locks must exist for this 2000 * to be a head: 2001 */ 2002 if (curr->held_locks[depth].irq_context != 2003 curr->held_locks[depth-1].irq_context) 2004 goto out_bug; 2005 2006 for (;;) { 2007 int distance = curr->lockdep_depth - depth + 1; 2008 hlock = curr->held_locks + depth - 1; 2009 /* 2010 * Only non-crosslock entries get new dependencies added. 2011 * Crosslock entries will be added by commit later: 2012 */ 2013 if (!cross_lock(hlock->instance)) { 2014 /* 2015 * Only non-recursive-read entries get new dependencies 2016 * added: 2017 */ 2018 if (hlock->read != 2 && hlock->check) { 2019 int ret = check_prev_add(curr, hlock, next, 2020 distance, &trace, save_trace); 2021 if (!ret) 2022 return 0; 2023 2024 /* 2025 * Stop after the first non-trylock entry, 2026 * as non-trylock entries have added their 2027 * own direct dependencies already, so this 2028 * lock is connected to them indirectly: 2029 */ 2030 if (!hlock->trylock) 2031 break; 2032 } 2033 } 2034 depth--; 2035 /* 2036 * End of lock-stack? 2037 */ 2038 if (!depth) 2039 break; 2040 /* 2041 * Stop the search if we cross into another context: 2042 */ 2043 if (curr->held_locks[depth].irq_context != 2044 curr->held_locks[depth-1].irq_context) 2045 break; 2046 } 2047 return 1; 2048 out_bug: 2049 if (!debug_locks_off_graph_unlock()) 2050 return 0; 2051 2052 /* 2053 * Clearly we all shouldn't be here, but since we made it we 2054 * can reliable say we messed up our state. See the above two 2055 * gotos for reasons why we could possibly end up here. 2056 */ 2057 WARN_ON(1); 2058 2059 return 0; 2060 } 2061 2062 unsigned long nr_lock_chains; 2063 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; 2064 int nr_chain_hlocks; 2065 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; 2066 2067 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) 2068 { 2069 return lock_classes + chain_hlocks[chain->base + i]; 2070 } 2071 2072 /* 2073 * Returns the index of the first held_lock of the current chain 2074 */ 2075 static inline int get_first_held_lock(struct task_struct *curr, 2076 struct held_lock *hlock) 2077 { 2078 int i; 2079 struct held_lock *hlock_curr; 2080 2081 for (i = curr->lockdep_depth - 1; i >= 0; i--) { 2082 hlock_curr = curr->held_locks + i; 2083 if (hlock_curr->irq_context != hlock->irq_context) 2084 break; 2085 2086 } 2087 2088 return ++i; 2089 } 2090 2091 #ifdef CONFIG_DEBUG_LOCKDEP 2092 /* 2093 * Returns the next chain_key iteration 2094 */ 2095 static u64 print_chain_key_iteration(int class_idx, u64 chain_key) 2096 { 2097 u64 new_chain_key = iterate_chain_key(chain_key, class_idx); 2098 2099 printk(" class_idx:%d -> chain_key:%016Lx", 2100 class_idx, 2101 (unsigned long long)new_chain_key); 2102 return new_chain_key; 2103 } 2104 2105 static void 2106 print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next) 2107 { 2108 struct held_lock *hlock; 2109 u64 chain_key = 0; 2110 int depth = curr->lockdep_depth; 2111 int i; 2112 2113 printk("depth: %u\n", depth + 1); 2114 for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) { 2115 hlock = curr->held_locks + i; 2116 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key); 2117 2118 print_lock(hlock); 2119 } 2120 2121 print_chain_key_iteration(hlock_next->class_idx, chain_key); 2122 print_lock(hlock_next); 2123 } 2124 2125 static void print_chain_keys_chain(struct lock_chain *chain) 2126 { 2127 int i; 2128 u64 chain_key = 0; 2129 int class_id; 2130 2131 printk("depth: %u\n", chain->depth); 2132 for (i = 0; i < chain->depth; i++) { 2133 class_id = chain_hlocks[chain->base + i]; 2134 chain_key = print_chain_key_iteration(class_id + 1, chain_key); 2135 2136 print_lock_name(lock_classes + class_id); 2137 printk("\n"); 2138 } 2139 } 2140 2141 static void print_collision(struct task_struct *curr, 2142 struct held_lock *hlock_next, 2143 struct lock_chain *chain) 2144 { 2145 pr_warn("\n"); 2146 pr_warn("============================\n"); 2147 pr_warn("WARNING: chain_key collision\n"); 2148 print_kernel_ident(); 2149 pr_warn("----------------------------\n"); 2150 pr_warn("%s/%d: ", current->comm, task_pid_nr(current)); 2151 pr_warn("Hash chain already cached but the contents don't match!\n"); 2152 2153 pr_warn("Held locks:"); 2154 print_chain_keys_held_locks(curr, hlock_next); 2155 2156 pr_warn("Locks in cached chain:"); 2157 print_chain_keys_chain(chain); 2158 2159 pr_warn("\nstack backtrace:\n"); 2160 dump_stack(); 2161 } 2162 #endif 2163 2164 /* 2165 * Checks whether the chain and the current held locks are consistent 2166 * in depth and also in content. If they are not it most likely means 2167 * that there was a collision during the calculation of the chain_key. 2168 * Returns: 0 not passed, 1 passed 2169 */ 2170 static int check_no_collision(struct task_struct *curr, 2171 struct held_lock *hlock, 2172 struct lock_chain *chain) 2173 { 2174 #ifdef CONFIG_DEBUG_LOCKDEP 2175 int i, j, id; 2176 2177 i = get_first_held_lock(curr, hlock); 2178 2179 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) { 2180 print_collision(curr, hlock, chain); 2181 return 0; 2182 } 2183 2184 for (j = 0; j < chain->depth - 1; j++, i++) { 2185 id = curr->held_locks[i].class_idx - 1; 2186 2187 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) { 2188 print_collision(curr, hlock, chain); 2189 return 0; 2190 } 2191 } 2192 #endif 2193 return 1; 2194 } 2195 2196 /* 2197 * This is for building a chain between just two different classes, 2198 * instead of adding a new hlock upon current, which is done by 2199 * add_chain_cache(). 2200 * 2201 * This can be called in any context with two classes, while 2202 * add_chain_cache() must be done within the lock owener's context 2203 * since it uses hlock which might be racy in another context. 2204 */ 2205 static inline int add_chain_cache_classes(unsigned int prev, 2206 unsigned int next, 2207 unsigned int irq_context, 2208 u64 chain_key) 2209 { 2210 struct hlist_head *hash_head = chainhashentry(chain_key); 2211 struct lock_chain *chain; 2212 2213 /* 2214 * Allocate a new chain entry from the static array, and add 2215 * it to the hash: 2216 */ 2217 2218 /* 2219 * We might need to take the graph lock, ensure we've got IRQs 2220 * disabled to make this an IRQ-safe lock.. for recursion reasons 2221 * lockdep won't complain about its own locking errors. 2222 */ 2223 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) 2224 return 0; 2225 2226 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { 2227 if (!debug_locks_off_graph_unlock()) 2228 return 0; 2229 2230 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); 2231 dump_stack(); 2232 return 0; 2233 } 2234 2235 chain = lock_chains + nr_lock_chains++; 2236 chain->chain_key = chain_key; 2237 chain->irq_context = irq_context; 2238 chain->depth = 2; 2239 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { 2240 chain->base = nr_chain_hlocks; 2241 nr_chain_hlocks += chain->depth; 2242 chain_hlocks[chain->base] = prev - 1; 2243 chain_hlocks[chain->base + 1] = next -1; 2244 } 2245 #ifdef CONFIG_DEBUG_LOCKDEP 2246 /* 2247 * Important for check_no_collision(). 2248 */ 2249 else { 2250 if (!debug_locks_off_graph_unlock()) 2251 return 0; 2252 2253 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); 2254 dump_stack(); 2255 return 0; 2256 } 2257 #endif 2258 2259 hlist_add_head_rcu(&chain->entry, hash_head); 2260 debug_atomic_inc(chain_lookup_misses); 2261 inc_chains(); 2262 2263 return 1; 2264 } 2265 2266 /* 2267 * Adds a dependency chain into chain hashtable. And must be called with 2268 * graph_lock held. 2269 * 2270 * Return 0 if fail, and graph_lock is released. 2271 * Return 1 if succeed, with graph_lock held. 2272 */ 2273 static inline int add_chain_cache(struct task_struct *curr, 2274 struct held_lock *hlock, 2275 u64 chain_key) 2276 { 2277 struct lock_class *class = hlock_class(hlock); 2278 struct hlist_head *hash_head = chainhashentry(chain_key); 2279 struct lock_chain *chain; 2280 int i, j; 2281 2282 /* 2283 * Allocate a new chain entry from the static array, and add 2284 * it to the hash: 2285 */ 2286 2287 /* 2288 * We might need to take the graph lock, ensure we've got IRQs 2289 * disabled to make this an IRQ-safe lock.. for recursion reasons 2290 * lockdep won't complain about its own locking errors. 2291 */ 2292 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) 2293 return 0; 2294 2295 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { 2296 if (!debug_locks_off_graph_unlock()) 2297 return 0; 2298 2299 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); 2300 dump_stack(); 2301 return 0; 2302 } 2303 chain = lock_chains + nr_lock_chains++; 2304 chain->chain_key = chain_key; 2305 chain->irq_context = hlock->irq_context; 2306 i = get_first_held_lock(curr, hlock); 2307 chain->depth = curr->lockdep_depth + 1 - i; 2308 2309 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks)); 2310 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks)); 2311 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes)); 2312 2313 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { 2314 chain->base = nr_chain_hlocks; 2315 for (j = 0; j < chain->depth - 1; j++, i++) { 2316 int lock_id = curr->held_locks[i].class_idx - 1; 2317 chain_hlocks[chain->base + j] = lock_id; 2318 } 2319 chain_hlocks[chain->base + j] = class - lock_classes; 2320 } 2321 2322 if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS) 2323 nr_chain_hlocks += chain->depth; 2324 2325 #ifdef CONFIG_DEBUG_LOCKDEP 2326 /* 2327 * Important for check_no_collision(). 2328 */ 2329 if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) { 2330 if (!debug_locks_off_graph_unlock()) 2331 return 0; 2332 2333 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); 2334 dump_stack(); 2335 return 0; 2336 } 2337 #endif 2338 2339 hlist_add_head_rcu(&chain->entry, hash_head); 2340 debug_atomic_inc(chain_lookup_misses); 2341 inc_chains(); 2342 2343 return 1; 2344 } 2345 2346 /* 2347 * Look up a dependency chain. 2348 */ 2349 static inline struct lock_chain *lookup_chain_cache(u64 chain_key) 2350 { 2351 struct hlist_head *hash_head = chainhashentry(chain_key); 2352 struct lock_chain *chain; 2353 2354 /* 2355 * We can walk it lock-free, because entries only get added 2356 * to the hash: 2357 */ 2358 hlist_for_each_entry_rcu(chain, hash_head, entry) { 2359 if (chain->chain_key == chain_key) { 2360 debug_atomic_inc(chain_lookup_hits); 2361 return chain; 2362 } 2363 } 2364 return NULL; 2365 } 2366 2367 /* 2368 * If the key is not present yet in dependency chain cache then 2369 * add it and return 1 - in this case the new dependency chain is 2370 * validated. If the key is already hashed, return 0. 2371 * (On return with 1 graph_lock is held.) 2372 */ 2373 static inline int lookup_chain_cache_add(struct task_struct *curr, 2374 struct held_lock *hlock, 2375 u64 chain_key) 2376 { 2377 struct lock_class *class = hlock_class(hlock); 2378 struct lock_chain *chain = lookup_chain_cache(chain_key); 2379 2380 if (chain) { 2381 cache_hit: 2382 if (!check_no_collision(curr, hlock, chain)) 2383 return 0; 2384 2385 if (very_verbose(class)) { 2386 printk("\nhash chain already cached, key: " 2387 "%016Lx tail class: [%p] %s\n", 2388 (unsigned long long)chain_key, 2389 class->key, class->name); 2390 } 2391 2392 return 0; 2393 } 2394 2395 if (very_verbose(class)) { 2396 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", 2397 (unsigned long long)chain_key, class->key, class->name); 2398 } 2399 2400 if (!graph_lock()) 2401 return 0; 2402 2403 /* 2404 * We have to walk the chain again locked - to avoid duplicates: 2405 */ 2406 chain = lookup_chain_cache(chain_key); 2407 if (chain) { 2408 graph_unlock(); 2409 goto cache_hit; 2410 } 2411 2412 if (!add_chain_cache(curr, hlock, chain_key)) 2413 return 0; 2414 2415 return 1; 2416 } 2417 2418 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, 2419 struct held_lock *hlock, int chain_head, u64 chain_key) 2420 { 2421 /* 2422 * Trylock needs to maintain the stack of held locks, but it 2423 * does not add new dependencies, because trylock can be done 2424 * in any order. 2425 * 2426 * We look up the chain_key and do the O(N^2) check and update of 2427 * the dependencies only if this is a new dependency chain. 2428 * (If lookup_chain_cache_add() return with 1 it acquires 2429 * graph_lock for us) 2430 */ 2431 if (!hlock->trylock && hlock->check && 2432 lookup_chain_cache_add(curr, hlock, chain_key)) { 2433 /* 2434 * Check whether last held lock: 2435 * 2436 * - is irq-safe, if this lock is irq-unsafe 2437 * - is softirq-safe, if this lock is hardirq-unsafe 2438 * 2439 * And check whether the new lock's dependency graph 2440 * could lead back to the previous lock. 2441 * 2442 * any of these scenarios could lead to a deadlock. If 2443 * All validations 2444 */ 2445 int ret = check_deadlock(curr, hlock, lock, hlock->read); 2446 2447 if (!ret) 2448 return 0; 2449 /* 2450 * Mark recursive read, as we jump over it when 2451 * building dependencies (just like we jump over 2452 * trylock entries): 2453 */ 2454 if (ret == 2) 2455 hlock->read = 2; 2456 /* 2457 * Add dependency only if this lock is not the head 2458 * of the chain, and if it's not a secondary read-lock: 2459 */ 2460 if (!chain_head && ret != 2) { 2461 if (!check_prevs_add(curr, hlock)) 2462 return 0; 2463 } 2464 2465 graph_unlock(); 2466 } else { 2467 /* after lookup_chain_cache_add(): */ 2468 if (unlikely(!debug_locks)) 2469 return 0; 2470 } 2471 2472 return 1; 2473 } 2474 #else 2475 static inline int validate_chain(struct task_struct *curr, 2476 struct lockdep_map *lock, struct held_lock *hlock, 2477 int chain_head, u64 chain_key) 2478 { 2479 return 1; 2480 } 2481 #endif 2482 2483 /* 2484 * We are building curr_chain_key incrementally, so double-check 2485 * it from scratch, to make sure that it's done correctly: 2486 */ 2487 static void check_chain_key(struct task_struct *curr) 2488 { 2489 #ifdef CONFIG_DEBUG_LOCKDEP 2490 struct held_lock *hlock, *prev_hlock = NULL; 2491 unsigned int i; 2492 u64 chain_key = 0; 2493 2494 for (i = 0; i < curr->lockdep_depth; i++) { 2495 hlock = curr->held_locks + i; 2496 if (chain_key != hlock->prev_chain_key) { 2497 debug_locks_off(); 2498 /* 2499 * We got mighty confused, our chain keys don't match 2500 * with what we expect, someone trample on our task state? 2501 */ 2502 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", 2503 curr->lockdep_depth, i, 2504 (unsigned long long)chain_key, 2505 (unsigned long long)hlock->prev_chain_key); 2506 return; 2507 } 2508 /* 2509 * Whoops ran out of static storage again? 2510 */ 2511 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS)) 2512 return; 2513 2514 if (prev_hlock && (prev_hlock->irq_context != 2515 hlock->irq_context)) 2516 chain_key = 0; 2517 chain_key = iterate_chain_key(chain_key, hlock->class_idx); 2518 prev_hlock = hlock; 2519 } 2520 if (chain_key != curr->curr_chain_key) { 2521 debug_locks_off(); 2522 /* 2523 * More smoking hash instead of calculating it, damn see these 2524 * numbers float.. I bet that a pink elephant stepped on my memory. 2525 */ 2526 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", 2527 curr->lockdep_depth, i, 2528 (unsigned long long)chain_key, 2529 (unsigned long long)curr->curr_chain_key); 2530 } 2531 #endif 2532 } 2533 2534 static void 2535 print_usage_bug_scenario(struct held_lock *lock) 2536 { 2537 struct lock_class *class = hlock_class(lock); 2538 2539 printk(" Possible unsafe locking scenario:\n\n"); 2540 printk(" CPU0\n"); 2541 printk(" ----\n"); 2542 printk(" lock("); 2543 __print_lock_name(class); 2544 printk(KERN_CONT ");\n"); 2545 printk(" <Interrupt>\n"); 2546 printk(" lock("); 2547 __print_lock_name(class); 2548 printk(KERN_CONT ");\n"); 2549 printk("\n *** DEADLOCK ***\n\n"); 2550 } 2551 2552 static int 2553 print_usage_bug(struct task_struct *curr, struct held_lock *this, 2554 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) 2555 { 2556 if (!debug_locks_off_graph_unlock() || debug_locks_silent) 2557 return 0; 2558 2559 pr_warn("\n"); 2560 pr_warn("================================\n"); 2561 pr_warn("WARNING: inconsistent lock state\n"); 2562 print_kernel_ident(); 2563 pr_warn("--------------------------------\n"); 2564 2565 pr_warn("inconsistent {%s} -> {%s} usage.\n", 2566 usage_str[prev_bit], usage_str[new_bit]); 2567 2568 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", 2569 curr->comm, task_pid_nr(curr), 2570 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, 2571 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, 2572 trace_hardirqs_enabled(curr), 2573 trace_softirqs_enabled(curr)); 2574 print_lock(this); 2575 2576 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]); 2577 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1); 2578 2579 print_irqtrace_events(curr); 2580 pr_warn("\nother info that might help us debug this:\n"); 2581 print_usage_bug_scenario(this); 2582 2583 lockdep_print_held_locks(curr); 2584 2585 pr_warn("\nstack backtrace:\n"); 2586 dump_stack(); 2587 2588 return 0; 2589 } 2590 2591 /* 2592 * Print out an error if an invalid bit is set: 2593 */ 2594 static inline int 2595 valid_state(struct task_struct *curr, struct held_lock *this, 2596 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) 2597 { 2598 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) 2599 return print_usage_bug(curr, this, bad_bit, new_bit); 2600 return 1; 2601 } 2602 2603 static int mark_lock(struct task_struct *curr, struct held_lock *this, 2604 enum lock_usage_bit new_bit); 2605 2606 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) 2607 2608 /* 2609 * print irq inversion bug: 2610 */ 2611 static int 2612 print_irq_inversion_bug(struct task_struct *curr, 2613 struct lock_list *root, struct lock_list *other, 2614 struct held_lock *this, int forwards, 2615 const char *irqclass) 2616 { 2617 struct lock_list *entry = other; 2618 struct lock_list *middle = NULL; 2619 int depth; 2620 2621 if (!debug_locks_off_graph_unlock() || debug_locks_silent) 2622 return 0; 2623 2624 pr_warn("\n"); 2625 pr_warn("========================================================\n"); 2626 pr_warn("WARNING: possible irq lock inversion dependency detected\n"); 2627 print_kernel_ident(); 2628 pr_warn("--------------------------------------------------------\n"); 2629 pr_warn("%s/%d just changed the state of lock:\n", 2630 curr->comm, task_pid_nr(curr)); 2631 print_lock(this); 2632 if (forwards) 2633 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass); 2634 else 2635 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); 2636 print_lock_name(other->class); 2637 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n"); 2638 2639 pr_warn("\nother info that might help us debug this:\n"); 2640 2641 /* Find a middle lock (if one exists) */ 2642 depth = get_lock_depth(other); 2643 do { 2644 if (depth == 0 && (entry != root)) { 2645 pr_warn("lockdep:%s bad path found in chain graph\n", __func__); 2646 break; 2647 } 2648 middle = entry; 2649 entry = get_lock_parent(entry); 2650 depth--; 2651 } while (entry && entry != root && (depth >= 0)); 2652 if (forwards) 2653 print_irq_lock_scenario(root, other, 2654 middle ? middle->class : root->class, other->class); 2655 else 2656 print_irq_lock_scenario(other, root, 2657 middle ? middle->class : other->class, root->class); 2658 2659 lockdep_print_held_locks(curr); 2660 2661 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); 2662 if (!save_trace(&root->trace)) 2663 return 0; 2664 print_shortest_lock_dependencies(other, root); 2665 2666 pr_warn("\nstack backtrace:\n"); 2667 dump_stack(); 2668 2669 return 0; 2670 } 2671 2672 /* 2673 * Prove that in the forwards-direction subgraph starting at <this> 2674 * there is no lock matching <mask>: 2675 */ 2676 static int 2677 check_usage_forwards(struct task_struct *curr, struct held_lock *this, 2678 enum lock_usage_bit bit, const char *irqclass) 2679 { 2680 int ret; 2681 struct lock_list root; 2682 struct lock_list *uninitialized_var(target_entry); 2683 2684 root.parent = NULL; 2685 root.class = hlock_class(this); 2686 ret = find_usage_forwards(&root, bit, &target_entry); 2687 if (ret < 0) 2688 return print_bfs_bug(ret); 2689 if (ret == 1) 2690 return ret; 2691 2692 return print_irq_inversion_bug(curr, &root, target_entry, 2693 this, 1, irqclass); 2694 } 2695 2696 /* 2697 * Prove that in the backwards-direction subgraph starting at <this> 2698 * there is no lock matching <mask>: 2699 */ 2700 static int 2701 check_usage_backwards(struct task_struct *curr, struct held_lock *this, 2702 enum lock_usage_bit bit, const char *irqclass) 2703 { 2704 int ret; 2705 struct lock_list root; 2706 struct lock_list *uninitialized_var(target_entry); 2707 2708 root.parent = NULL; 2709 root.class = hlock_class(this); 2710 ret = find_usage_backwards(&root, bit, &target_entry); 2711 if (ret < 0) 2712 return print_bfs_bug(ret); 2713 if (ret == 1) 2714 return ret; 2715 2716 return print_irq_inversion_bug(curr, &root, target_entry, 2717 this, 0, irqclass); 2718 } 2719 2720 void print_irqtrace_events(struct task_struct *curr) 2721 { 2722 printk("irq event stamp: %u\n", curr->irq_events); 2723 printk("hardirqs last enabled at (%u): [<%p>] %pS\n", 2724 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip, 2725 (void *)curr->hardirq_enable_ip); 2726 printk("hardirqs last disabled at (%u): [<%p>] %pS\n", 2727 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip, 2728 (void *)curr->hardirq_disable_ip); 2729 printk("softirqs last enabled at (%u): [<%p>] %pS\n", 2730 curr->softirq_enable_event, (void *)curr->softirq_enable_ip, 2731 (void *)curr->softirq_enable_ip); 2732 printk("softirqs last disabled at (%u): [<%p>] %pS\n", 2733 curr->softirq_disable_event, (void *)curr->softirq_disable_ip, 2734 (void *)curr->softirq_disable_ip); 2735 } 2736 2737 static int HARDIRQ_verbose(struct lock_class *class) 2738 { 2739 #if HARDIRQ_VERBOSE 2740 return class_filter(class); 2741 #endif 2742 return 0; 2743 } 2744 2745 static int SOFTIRQ_verbose(struct lock_class *class) 2746 { 2747 #if SOFTIRQ_VERBOSE 2748 return class_filter(class); 2749 #endif 2750 return 0; 2751 } 2752 2753 #define STRICT_READ_CHECKS 1 2754 2755 static int (*state_verbose_f[])(struct lock_class *class) = { 2756 #define LOCKDEP_STATE(__STATE) \ 2757 __STATE##_verbose, 2758 #include "lockdep_states.h" 2759 #undef LOCKDEP_STATE 2760 }; 2761 2762 static inline int state_verbose(enum lock_usage_bit bit, 2763 struct lock_class *class) 2764 { 2765 return state_verbose_f[bit >> 2](class); 2766 } 2767 2768 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, 2769 enum lock_usage_bit bit, const char *name); 2770 2771 static int 2772 mark_lock_irq(struct task_struct *curr, struct held_lock *this, 2773 enum lock_usage_bit new_bit) 2774 { 2775 int excl_bit = exclusive_bit(new_bit); 2776 int read = new_bit & 1; 2777 int dir = new_bit & 2; 2778 2779 /* 2780 * mark USED_IN has to look forwards -- to ensure no dependency 2781 * has ENABLED state, which would allow recursion deadlocks. 2782 * 2783 * mark ENABLED has to look backwards -- to ensure no dependee 2784 * has USED_IN state, which, again, would allow recursion deadlocks. 2785 */ 2786 check_usage_f usage = dir ? 2787 check_usage_backwards : check_usage_forwards; 2788 2789 /* 2790 * Validate that this particular lock does not have conflicting 2791 * usage states. 2792 */ 2793 if (!valid_state(curr, this, new_bit, excl_bit)) 2794 return 0; 2795 2796 /* 2797 * Validate that the lock dependencies don't have conflicting usage 2798 * states. 2799 */ 2800 if ((!read || !dir || STRICT_READ_CHECKS) && 2801 !usage(curr, this, excl_bit, state_name(new_bit & ~1))) 2802 return 0; 2803 2804 /* 2805 * Check for read in write conflicts 2806 */ 2807 if (!read) { 2808 if (!valid_state(curr, this, new_bit, excl_bit + 1)) 2809 return 0; 2810 2811 if (STRICT_READ_CHECKS && 2812 !usage(curr, this, excl_bit + 1, 2813 state_name(new_bit + 1))) 2814 return 0; 2815 } 2816 2817 if (state_verbose(new_bit, hlock_class(this))) 2818 return 2; 2819 2820 return 1; 2821 } 2822 2823 enum mark_type { 2824 #define LOCKDEP_STATE(__STATE) __STATE, 2825 #include "lockdep_states.h" 2826 #undef LOCKDEP_STATE 2827 }; 2828 2829 /* 2830 * Mark all held locks with a usage bit: 2831 */ 2832 static int 2833 mark_held_locks(struct task_struct *curr, enum mark_type mark) 2834 { 2835 enum lock_usage_bit usage_bit; 2836 struct held_lock *hlock; 2837 int i; 2838 2839 for (i = 0; i < curr->lockdep_depth; i++) { 2840 hlock = curr->held_locks + i; 2841 2842 usage_bit = 2 + (mark << 2); /* ENABLED */ 2843 if (hlock->read) 2844 usage_bit += 1; /* READ */ 2845 2846 BUG_ON(usage_bit >= LOCK_USAGE_STATES); 2847 2848 if (!hlock->check) 2849 continue; 2850 2851 if (!mark_lock(curr, hlock, usage_bit)) 2852 return 0; 2853 } 2854 2855 return 1; 2856 } 2857 2858 /* 2859 * Hardirqs will be enabled: 2860 */ 2861 static void __trace_hardirqs_on_caller(unsigned long ip) 2862 { 2863 struct task_struct *curr = current; 2864 2865 /* we'll do an OFF -> ON transition: */ 2866 curr->hardirqs_enabled = 1; 2867 2868 /* 2869 * We are going to turn hardirqs on, so set the 2870 * usage bit for all held locks: 2871 */ 2872 if (!mark_held_locks(curr, HARDIRQ)) 2873 return; 2874 /* 2875 * If we have softirqs enabled, then set the usage 2876 * bit for all held locks. (disabled hardirqs prevented 2877 * this bit from being set before) 2878 */ 2879 if (curr->softirqs_enabled) 2880 if (!mark_held_locks(curr, SOFTIRQ)) 2881 return; 2882 2883 curr->hardirq_enable_ip = ip; 2884 curr->hardirq_enable_event = ++curr->irq_events; 2885 debug_atomic_inc(hardirqs_on_events); 2886 } 2887 2888 __visible void trace_hardirqs_on_caller(unsigned long ip) 2889 { 2890 time_hardirqs_on(CALLER_ADDR0, ip); 2891 2892 if (unlikely(!debug_locks || current->lockdep_recursion)) 2893 return; 2894 2895 if (unlikely(current->hardirqs_enabled)) { 2896 /* 2897 * Neither irq nor preemption are disabled here 2898 * so this is racy by nature but losing one hit 2899 * in a stat is not a big deal. 2900 */ 2901 __debug_atomic_inc(redundant_hardirqs_on); 2902 return; 2903 } 2904 2905 /* 2906 * We're enabling irqs and according to our state above irqs weren't 2907 * already enabled, yet we find the hardware thinks they are in fact 2908 * enabled.. someone messed up their IRQ state tracing. 2909 */ 2910 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) 2911 return; 2912 2913 /* 2914 * See the fine text that goes along with this variable definition. 2915 */ 2916 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) 2917 return; 2918 2919 /* 2920 * Can't allow enabling interrupts while in an interrupt handler, 2921 * that's general bad form and such. Recursion, limited stack etc.. 2922 */ 2923 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) 2924 return; 2925 2926 current->lockdep_recursion = 1; 2927 __trace_hardirqs_on_caller(ip); 2928 current->lockdep_recursion = 0; 2929 } 2930 EXPORT_SYMBOL(trace_hardirqs_on_caller); 2931 2932 void trace_hardirqs_on(void) 2933 { 2934 trace_hardirqs_on_caller(CALLER_ADDR0); 2935 } 2936 EXPORT_SYMBOL(trace_hardirqs_on); 2937 2938 /* 2939 * Hardirqs were disabled: 2940 */ 2941 __visible void trace_hardirqs_off_caller(unsigned long ip) 2942 { 2943 struct task_struct *curr = current; 2944 2945 time_hardirqs_off(CALLER_ADDR0, ip); 2946 2947 if (unlikely(!debug_locks || current->lockdep_recursion)) 2948 return; 2949 2950 /* 2951 * So we're supposed to get called after you mask local IRQs, but for 2952 * some reason the hardware doesn't quite think you did a proper job. 2953 */ 2954 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) 2955 return; 2956 2957 if (curr->hardirqs_enabled) { 2958 /* 2959 * We have done an ON -> OFF transition: 2960 */ 2961 curr->hardirqs_enabled = 0; 2962 curr->hardirq_disable_ip = ip; 2963 curr->hardirq_disable_event = ++curr->irq_events; 2964 debug_atomic_inc(hardirqs_off_events); 2965 } else 2966 debug_atomic_inc(redundant_hardirqs_off); 2967 } 2968 EXPORT_SYMBOL(trace_hardirqs_off_caller); 2969 2970 void trace_hardirqs_off(void) 2971 { 2972 trace_hardirqs_off_caller(CALLER_ADDR0); 2973 } 2974 EXPORT_SYMBOL(trace_hardirqs_off); 2975 2976 /* 2977 * Softirqs will be enabled: 2978 */ 2979 void trace_softirqs_on(unsigned long ip) 2980 { 2981 struct task_struct *curr = current; 2982 2983 if (unlikely(!debug_locks || current->lockdep_recursion)) 2984 return; 2985 2986 /* 2987 * We fancy IRQs being disabled here, see softirq.c, avoids 2988 * funny state and nesting things. 2989 */ 2990 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) 2991 return; 2992 2993 if (curr->softirqs_enabled) { 2994 debug_atomic_inc(redundant_softirqs_on); 2995 return; 2996 } 2997 2998 current->lockdep_recursion = 1; 2999 /* 3000 * We'll do an OFF -> ON transition: 3001 */ 3002 curr->softirqs_enabled = 1; 3003 curr->softirq_enable_ip = ip; 3004 curr->softirq_enable_event = ++curr->irq_events; 3005 debug_atomic_inc(softirqs_on_events); 3006 /* 3007 * We are going to turn softirqs on, so set the 3008 * usage bit for all held locks, if hardirqs are 3009 * enabled too: 3010 */ 3011 if (curr->hardirqs_enabled) 3012 mark_held_locks(curr, SOFTIRQ); 3013 current->lockdep_recursion = 0; 3014 } 3015 3016 /* 3017 * Softirqs were disabled: 3018 */ 3019 void trace_softirqs_off(unsigned long ip) 3020 { 3021 struct task_struct *curr = current; 3022 3023 if (unlikely(!debug_locks || current->lockdep_recursion)) 3024 return; 3025 3026 /* 3027 * We fancy IRQs being disabled here, see softirq.c 3028 */ 3029 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) 3030 return; 3031 3032 if (curr->softirqs_enabled) { 3033 /* 3034 * We have done an ON -> OFF transition: 3035 */ 3036 curr->softirqs_enabled = 0; 3037 curr->softirq_disable_ip = ip; 3038 curr->softirq_disable_event = ++curr->irq_events; 3039 debug_atomic_inc(softirqs_off_events); 3040 /* 3041 * Whoops, we wanted softirqs off, so why aren't they? 3042 */ 3043 DEBUG_LOCKS_WARN_ON(!softirq_count()); 3044 } else 3045 debug_atomic_inc(redundant_softirqs_off); 3046 } 3047 3048 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) 3049 { 3050 /* 3051 * If non-trylock use in a hardirq or softirq context, then 3052 * mark the lock as used in these contexts: 3053 */ 3054 if (!hlock->trylock) { 3055 if (hlock->read) { 3056 if (curr->hardirq_context) 3057 if (!mark_lock(curr, hlock, 3058 LOCK_USED_IN_HARDIRQ_READ)) 3059 return 0; 3060 if (curr->softirq_context) 3061 if (!mark_lock(curr, hlock, 3062 LOCK_USED_IN_SOFTIRQ_READ)) 3063 return 0; 3064 } else { 3065 if (curr->hardirq_context) 3066 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) 3067 return 0; 3068 if (curr->softirq_context) 3069 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) 3070 return 0; 3071 } 3072 } 3073 if (!hlock->hardirqs_off) { 3074 if (hlock->read) { 3075 if (!mark_lock(curr, hlock, 3076 LOCK_ENABLED_HARDIRQ_READ)) 3077 return 0; 3078 if (curr->softirqs_enabled) 3079 if (!mark_lock(curr, hlock, 3080 LOCK_ENABLED_SOFTIRQ_READ)) 3081 return 0; 3082 } else { 3083 if (!mark_lock(curr, hlock, 3084 LOCK_ENABLED_HARDIRQ)) 3085 return 0; 3086 if (curr->softirqs_enabled) 3087 if (!mark_lock(curr, hlock, 3088 LOCK_ENABLED_SOFTIRQ)) 3089 return 0; 3090 } 3091 } 3092 3093 return 1; 3094 } 3095 3096 static inline unsigned int task_irq_context(struct task_struct *task) 3097 { 3098 return 2 * !!task->hardirq_context + !!task->softirq_context; 3099 } 3100 3101 static int separate_irq_context(struct task_struct *curr, 3102 struct held_lock *hlock) 3103 { 3104 unsigned int depth = curr->lockdep_depth; 3105 3106 /* 3107 * Keep track of points where we cross into an interrupt context: 3108 */ 3109 if (depth) { 3110 struct held_lock *prev_hlock; 3111 3112 prev_hlock = curr->held_locks + depth-1; 3113 /* 3114 * If we cross into another context, reset the 3115 * hash key (this also prevents the checking and the 3116 * adding of the dependency to 'prev'): 3117 */ 3118 if (prev_hlock->irq_context != hlock->irq_context) 3119 return 1; 3120 } 3121 return 0; 3122 } 3123 3124 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ 3125 3126 static inline 3127 int mark_lock_irq(struct task_struct *curr, struct held_lock *this, 3128 enum lock_usage_bit new_bit) 3129 { 3130 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */ 3131 return 1; 3132 } 3133 3134 static inline int mark_irqflags(struct task_struct *curr, 3135 struct held_lock *hlock) 3136 { 3137 return 1; 3138 } 3139 3140 static inline unsigned int task_irq_context(struct task_struct *task) 3141 { 3142 return 0; 3143 } 3144 3145 static inline int separate_irq_context(struct task_struct *curr, 3146 struct held_lock *hlock) 3147 { 3148 return 0; 3149 } 3150 3151 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ 3152 3153 /* 3154 * Mark a lock with a usage bit, and validate the state transition: 3155 */ 3156 static int mark_lock(struct task_struct *curr, struct held_lock *this, 3157 enum lock_usage_bit new_bit) 3158 { 3159 unsigned int new_mask = 1 << new_bit, ret = 1; 3160 3161 /* 3162 * If already set then do not dirty the cacheline, 3163 * nor do any checks: 3164 */ 3165 if (likely(hlock_class(this)->usage_mask & new_mask)) 3166 return 1; 3167 3168 if (!graph_lock()) 3169 return 0; 3170 /* 3171 * Make sure we didn't race: 3172 */ 3173 if (unlikely(hlock_class(this)->usage_mask & new_mask)) { 3174 graph_unlock(); 3175 return 1; 3176 } 3177 3178 hlock_class(this)->usage_mask |= new_mask; 3179 3180 if (!save_trace(hlock_class(this)->usage_traces + new_bit)) 3181 return 0; 3182 3183 switch (new_bit) { 3184 #define LOCKDEP_STATE(__STATE) \ 3185 case LOCK_USED_IN_##__STATE: \ 3186 case LOCK_USED_IN_##__STATE##_READ: \ 3187 case LOCK_ENABLED_##__STATE: \ 3188 case LOCK_ENABLED_##__STATE##_READ: 3189 #include "lockdep_states.h" 3190 #undef LOCKDEP_STATE 3191 ret = mark_lock_irq(curr, this, new_bit); 3192 if (!ret) 3193 return 0; 3194 break; 3195 case LOCK_USED: 3196 debug_atomic_dec(nr_unused_locks); 3197 break; 3198 default: 3199 if (!debug_locks_off_graph_unlock()) 3200 return 0; 3201 WARN_ON(1); 3202 return 0; 3203 } 3204 3205 graph_unlock(); 3206 3207 /* 3208 * We must printk outside of the graph_lock: 3209 */ 3210 if (ret == 2) { 3211 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); 3212 print_lock(this); 3213 print_irqtrace_events(curr); 3214 dump_stack(); 3215 } 3216 3217 return ret; 3218 } 3219 3220 /* 3221 * Initialize a lock instance's lock-class mapping info: 3222 */ 3223 static void __lockdep_init_map(struct lockdep_map *lock, const char *name, 3224 struct lock_class_key *key, int subclass) 3225 { 3226 int i; 3227 3228 kmemcheck_mark_initialized(lock, sizeof(*lock)); 3229 3230 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) 3231 lock->class_cache[i] = NULL; 3232 3233 #ifdef CONFIG_LOCK_STAT 3234 lock->cpu = raw_smp_processor_id(); 3235 #endif 3236 3237 /* 3238 * Can't be having no nameless bastards around this place! 3239 */ 3240 if (DEBUG_LOCKS_WARN_ON(!name)) { 3241 lock->name = "NULL"; 3242 return; 3243 } 3244 3245 lock->name = name; 3246 3247 /* 3248 * No key, no joy, we need to hash something. 3249 */ 3250 if (DEBUG_LOCKS_WARN_ON(!key)) 3251 return; 3252 /* 3253 * Sanity check, the lock-class key must be persistent: 3254 */ 3255 if (!static_obj(key)) { 3256 printk("BUG: key %p not in .data!\n", key); 3257 /* 3258 * What it says above ^^^^^, I suggest you read it. 3259 */ 3260 DEBUG_LOCKS_WARN_ON(1); 3261 return; 3262 } 3263 lock->key = key; 3264 3265 if (unlikely(!debug_locks)) 3266 return; 3267 3268 if (subclass) { 3269 unsigned long flags; 3270 3271 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion)) 3272 return; 3273 3274 raw_local_irq_save(flags); 3275 current->lockdep_recursion = 1; 3276 register_lock_class(lock, subclass, 1); 3277 current->lockdep_recursion = 0; 3278 raw_local_irq_restore(flags); 3279 } 3280 } 3281 3282 void lockdep_init_map(struct lockdep_map *lock, const char *name, 3283 struct lock_class_key *key, int subclass) 3284 { 3285 cross_init(lock, 0); 3286 __lockdep_init_map(lock, name, key, subclass); 3287 } 3288 EXPORT_SYMBOL_GPL(lockdep_init_map); 3289 3290 #ifdef CONFIG_LOCKDEP_CROSSRELEASE 3291 void lockdep_init_map_crosslock(struct lockdep_map *lock, const char *name, 3292 struct lock_class_key *key, int subclass) 3293 { 3294 cross_init(lock, 1); 3295 __lockdep_init_map(lock, name, key, subclass); 3296 } 3297 EXPORT_SYMBOL_GPL(lockdep_init_map_crosslock); 3298 #endif 3299 3300 struct lock_class_key __lockdep_no_validate__; 3301 EXPORT_SYMBOL_GPL(__lockdep_no_validate__); 3302 3303 static int 3304 print_lock_nested_lock_not_held(struct task_struct *curr, 3305 struct held_lock *hlock, 3306 unsigned long ip) 3307 { 3308 if (!debug_locks_off()) 3309 return 0; 3310 if (debug_locks_silent) 3311 return 0; 3312 3313 pr_warn("\n"); 3314 pr_warn("==================================\n"); 3315 pr_warn("WARNING: Nested lock was not taken\n"); 3316 print_kernel_ident(); 3317 pr_warn("----------------------------------\n"); 3318 3319 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr)); 3320 print_lock(hlock); 3321 3322 pr_warn("\nbut this task is not holding:\n"); 3323 pr_warn("%s\n", hlock->nest_lock->name); 3324 3325 pr_warn("\nstack backtrace:\n"); 3326 dump_stack(); 3327 3328 pr_warn("\nother info that might help us debug this:\n"); 3329 lockdep_print_held_locks(curr); 3330 3331 pr_warn("\nstack backtrace:\n"); 3332 dump_stack(); 3333 3334 return 0; 3335 } 3336 3337 static int __lock_is_held(struct lockdep_map *lock, int read); 3338 3339 /* 3340 * This gets called for every mutex_lock*()/spin_lock*() operation. 3341 * We maintain the dependency maps and validate the locking attempt: 3342 */ 3343 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, 3344 int trylock, int read, int check, int hardirqs_off, 3345 struct lockdep_map *nest_lock, unsigned long ip, 3346 int references, int pin_count) 3347 { 3348 struct task_struct *curr = current; 3349 struct lock_class *class = NULL; 3350 struct held_lock *hlock; 3351 unsigned int depth; 3352 int chain_head = 0; 3353 int class_idx; 3354 u64 chain_key; 3355 int ret; 3356 3357 if (unlikely(!debug_locks)) 3358 return 0; 3359 3360 /* 3361 * Lockdep should run with IRQs disabled, otherwise we could 3362 * get an interrupt which would want to take locks, which would 3363 * end up in lockdep and have you got a head-ache already? 3364 */ 3365 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) 3366 return 0; 3367 3368 if (!prove_locking || lock->key == &__lockdep_no_validate__) 3369 check = 0; 3370 3371 if (subclass < NR_LOCKDEP_CACHING_CLASSES) 3372 class = lock->class_cache[subclass]; 3373 /* 3374 * Not cached? 3375 */ 3376 if (unlikely(!class)) { 3377 class = register_lock_class(lock, subclass, 0); 3378 if (!class) 3379 return 0; 3380 } 3381 atomic_inc((atomic_t *)&class->ops); 3382 if (very_verbose(class)) { 3383 printk("\nacquire class [%p] %s", class->key, class->name); 3384 if (class->name_version > 1) 3385 printk(KERN_CONT "#%d", class->name_version); 3386 printk(KERN_CONT "\n"); 3387 dump_stack(); 3388 } 3389 3390 /* 3391 * Add the lock to the list of currently held locks. 3392 * (we dont increase the depth just yet, up until the 3393 * dependency checks are done) 3394 */ 3395 depth = curr->lockdep_depth; 3396 /* 3397 * Ran out of static storage for our per-task lock stack again have we? 3398 */ 3399 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) 3400 return 0; 3401 3402 class_idx = class - lock_classes + 1; 3403 3404 /* TODO: nest_lock is not implemented for crosslock yet. */ 3405 if (depth && !cross_lock(lock)) { 3406 hlock = curr->held_locks + depth - 1; 3407 if (hlock->class_idx == class_idx && nest_lock) { 3408 if (hlock->references) { 3409 /* 3410 * Check: unsigned int references:12, overflow. 3411 */ 3412 if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1)) 3413 return 0; 3414 3415 hlock->references++; 3416 } else { 3417 hlock->references = 2; 3418 } 3419 3420 return 1; 3421 } 3422 } 3423 3424 hlock = curr->held_locks + depth; 3425 /* 3426 * Plain impossible, we just registered it and checked it weren't no 3427 * NULL like.. I bet this mushroom I ate was good! 3428 */ 3429 if (DEBUG_LOCKS_WARN_ON(!class)) 3430 return 0; 3431 hlock->class_idx = class_idx; 3432 hlock->acquire_ip = ip; 3433 hlock->instance = lock; 3434 hlock->nest_lock = nest_lock; 3435 hlock->irq_context = task_irq_context(curr); 3436 hlock->trylock = trylock; 3437 hlock->read = read; 3438 hlock->check = check; 3439 hlock->hardirqs_off = !!hardirqs_off; 3440 hlock->references = references; 3441 #ifdef CONFIG_LOCK_STAT 3442 hlock->waittime_stamp = 0; 3443 hlock->holdtime_stamp = lockstat_clock(); 3444 #endif 3445 hlock->pin_count = pin_count; 3446 3447 if (check && !mark_irqflags(curr, hlock)) 3448 return 0; 3449 3450 /* mark it as used: */ 3451 if (!mark_lock(curr, hlock, LOCK_USED)) 3452 return 0; 3453 3454 /* 3455 * Calculate the chain hash: it's the combined hash of all the 3456 * lock keys along the dependency chain. We save the hash value 3457 * at every step so that we can get the current hash easily 3458 * after unlock. The chain hash is then used to cache dependency 3459 * results. 3460 * 3461 * The 'key ID' is what is the most compact key value to drive 3462 * the hash, not class->key. 3463 */ 3464 /* 3465 * Whoops, we did it again.. ran straight out of our static allocation. 3466 */ 3467 if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS)) 3468 return 0; 3469 3470 chain_key = curr->curr_chain_key; 3471 if (!depth) { 3472 /* 3473 * How can we have a chain hash when we ain't got no keys?! 3474 */ 3475 if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) 3476 return 0; 3477 chain_head = 1; 3478 } 3479 3480 hlock->prev_chain_key = chain_key; 3481 if (separate_irq_context(curr, hlock)) { 3482 chain_key = 0; 3483 chain_head = 1; 3484 } 3485 chain_key = iterate_chain_key(chain_key, class_idx); 3486 3487 if (nest_lock && !__lock_is_held(nest_lock, -1)) 3488 return print_lock_nested_lock_not_held(curr, hlock, ip); 3489 3490 if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) 3491 return 0; 3492 3493 ret = lock_acquire_crosslock(hlock); 3494 /* 3495 * 2 means normal acquire operations are needed. Otherwise, it's 3496 * ok just to return with '0:fail, 1:success'. 3497 */ 3498 if (ret != 2) 3499 return ret; 3500 3501 curr->curr_chain_key = chain_key; 3502 curr->lockdep_depth++; 3503 check_chain_key(curr); 3504 #ifdef CONFIG_DEBUG_LOCKDEP 3505 if (unlikely(!debug_locks)) 3506 return 0; 3507 #endif 3508 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { 3509 debug_locks_off(); 3510 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!"); 3511 printk(KERN_DEBUG "depth: %i max: %lu!\n", 3512 curr->lockdep_depth, MAX_LOCK_DEPTH); 3513 3514 lockdep_print_held_locks(current); 3515 debug_show_all_locks(); 3516 dump_stack(); 3517 3518 return 0; 3519 } 3520 3521 if (unlikely(curr->lockdep_depth > max_lockdep_depth)) 3522 max_lockdep_depth = curr->lockdep_depth; 3523 3524 return 1; 3525 } 3526 3527 static int 3528 print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock, 3529 unsigned long ip) 3530 { 3531 if (!debug_locks_off()) 3532 return 0; 3533 if (debug_locks_silent) 3534 return 0; 3535 3536 pr_warn("\n"); 3537 pr_warn("=====================================\n"); 3538 pr_warn("WARNING: bad unlock balance detected!\n"); 3539 print_kernel_ident(); 3540 pr_warn("-------------------------------------\n"); 3541 pr_warn("%s/%d is trying to release lock (", 3542 curr->comm, task_pid_nr(curr)); 3543 print_lockdep_cache(lock); 3544 pr_cont(") at:\n"); 3545 print_ip_sym(ip); 3546 pr_warn("but there are no more locks to release!\n"); 3547 pr_warn("\nother info that might help us debug this:\n"); 3548 lockdep_print_held_locks(curr); 3549 3550 pr_warn("\nstack backtrace:\n"); 3551 dump_stack(); 3552 3553 return 0; 3554 } 3555 3556 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) 3557 { 3558 if (hlock->instance == lock) 3559 return 1; 3560 3561 if (hlock->references) { 3562 struct lock_class *class = lock->class_cache[0]; 3563 3564 if (!class) 3565 class = look_up_lock_class(lock, 0); 3566 3567 /* 3568 * If look_up_lock_class() failed to find a class, we're trying 3569 * to test if we hold a lock that has never yet been acquired. 3570 * Clearly if the lock hasn't been acquired _ever_, we're not 3571 * holding it either, so report failure. 3572 */ 3573 if (IS_ERR_OR_NULL(class)) 3574 return 0; 3575 3576 /* 3577 * References, but not a lock we're actually ref-counting? 3578 * State got messed up, follow the sites that change ->references 3579 * and try to make sense of it. 3580 */ 3581 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) 3582 return 0; 3583 3584 if (hlock->class_idx == class - lock_classes + 1) 3585 return 1; 3586 } 3587 3588 return 0; 3589 } 3590 3591 /* @depth must not be zero */ 3592 static struct held_lock *find_held_lock(struct task_struct *curr, 3593 struct lockdep_map *lock, 3594 unsigned int depth, int *idx) 3595 { 3596 struct held_lock *ret, *hlock, *prev_hlock; 3597 int i; 3598 3599 i = depth - 1; 3600 hlock = curr->held_locks + i; 3601 ret = hlock; 3602 if (match_held_lock(hlock, lock)) 3603 goto out; 3604 3605 ret = NULL; 3606 for (i--, prev_hlock = hlock--; 3607 i >= 0; 3608 i--, prev_hlock = hlock--) { 3609 /* 3610 * We must not cross into another context: 3611 */ 3612 if (prev_hlock->irq_context != hlock->irq_context) { 3613 ret = NULL; 3614 break; 3615 } 3616 if (match_held_lock(hlock, lock)) { 3617 ret = hlock; 3618 break; 3619 } 3620 } 3621 3622 out: 3623 *idx = i; 3624 return ret; 3625 } 3626 3627 static int reacquire_held_locks(struct task_struct *curr, unsigned int depth, 3628 int idx) 3629 { 3630 struct held_lock *hlock; 3631 3632 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) { 3633 if (!__lock_acquire(hlock->instance, 3634 hlock_class(hlock)->subclass, 3635 hlock->trylock, 3636 hlock->read, hlock->check, 3637 hlock->hardirqs_off, 3638 hlock->nest_lock, hlock->acquire_ip, 3639 hlock->references, hlock->pin_count)) 3640 return 1; 3641 } 3642 return 0; 3643 } 3644 3645 static int 3646 __lock_set_class(struct lockdep_map *lock, const char *name, 3647 struct lock_class_key *key, unsigned int subclass, 3648 unsigned long ip) 3649 { 3650 struct task_struct *curr = current; 3651 struct held_lock *hlock; 3652 struct lock_class *class; 3653 unsigned int depth; 3654 int i; 3655 3656 depth = curr->lockdep_depth; 3657 /* 3658 * This function is about (re)setting the class of a held lock, 3659 * yet we're not actually holding any locks. Naughty user! 3660 */ 3661 if (DEBUG_LOCKS_WARN_ON(!depth)) 3662 return 0; 3663 3664 hlock = find_held_lock(curr, lock, depth, &i); 3665 if (!hlock) 3666 return print_unlock_imbalance_bug(curr, lock, ip); 3667 3668 lockdep_init_map(lock, name, key, 0); 3669 class = register_lock_class(lock, subclass, 0); 3670 hlock->class_idx = class - lock_classes + 1; 3671 3672 curr->lockdep_depth = i; 3673 curr->curr_chain_key = hlock->prev_chain_key; 3674 3675 if (reacquire_held_locks(curr, depth, i)) 3676 return 0; 3677 3678 /* 3679 * I took it apart and put it back together again, except now I have 3680 * these 'spare' parts.. where shall I put them. 3681 */ 3682 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) 3683 return 0; 3684 return 1; 3685 } 3686 3687 static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) 3688 { 3689 struct task_struct *curr = current; 3690 struct held_lock *hlock; 3691 unsigned int depth; 3692 int i; 3693 3694 depth = curr->lockdep_depth; 3695 /* 3696 * This function is about (re)setting the class of a held lock, 3697 * yet we're not actually holding any locks. Naughty user! 3698 */ 3699 if (DEBUG_LOCKS_WARN_ON(!depth)) 3700 return 0; 3701 3702 hlock = find_held_lock(curr, lock, depth, &i); 3703 if (!hlock) 3704 return print_unlock_imbalance_bug(curr, lock, ip); 3705 3706 curr->lockdep_depth = i; 3707 curr->curr_chain_key = hlock->prev_chain_key; 3708 3709 WARN(hlock->read, "downgrading a read lock"); 3710 hlock->read = 1; 3711 hlock->acquire_ip = ip; 3712 3713 if (reacquire_held_locks(curr, depth, i)) 3714 return 0; 3715 3716 /* 3717 * I took it apart and put it back together again, except now I have 3718 * these 'spare' parts.. where shall I put them. 3719 */ 3720 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) 3721 return 0; 3722 return 1; 3723 } 3724 3725 /* 3726 * Remove the lock to the list of currently held locks - this gets 3727 * called on mutex_unlock()/spin_unlock*() (or on a failed 3728 * mutex_lock_interruptible()). 3729 * 3730 * @nested is an hysterical artifact, needs a tree wide cleanup. 3731 */ 3732 static int 3733 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) 3734 { 3735 struct task_struct *curr = current; 3736 struct held_lock *hlock; 3737 unsigned int depth; 3738 int ret, i; 3739 3740 if (unlikely(!debug_locks)) 3741 return 0; 3742 3743 ret = lock_release_crosslock(lock); 3744 /* 3745 * 2 means normal release operations are needed. Otherwise, it's 3746 * ok just to return with '0:fail, 1:success'. 3747 */ 3748 if (ret != 2) 3749 return ret; 3750 3751 depth = curr->lockdep_depth; 3752 /* 3753 * So we're all set to release this lock.. wait what lock? We don't 3754 * own any locks, you've been drinking again? 3755 */ 3756 if (DEBUG_LOCKS_WARN_ON(depth <= 0)) 3757 return print_unlock_imbalance_bug(curr, lock, ip); 3758 3759 /* 3760 * Check whether the lock exists in the current stack 3761 * of held locks: 3762 */ 3763 hlock = find_held_lock(curr, lock, depth, &i); 3764 if (!hlock) 3765 return print_unlock_imbalance_bug(curr, lock, ip); 3766 3767 if (hlock->instance == lock) 3768 lock_release_holdtime(hlock); 3769 3770 WARN(hlock->pin_count, "releasing a pinned lock\n"); 3771 3772 if (hlock->references) { 3773 hlock->references--; 3774 if (hlock->references) { 3775 /* 3776 * We had, and after removing one, still have 3777 * references, the current lock stack is still 3778 * valid. We're done! 3779 */ 3780 return 1; 3781 } 3782 } 3783 3784 /* 3785 * We have the right lock to unlock, 'hlock' points to it. 3786 * Now we remove it from the stack, and add back the other 3787 * entries (if any), recalculating the hash along the way: 3788 */ 3789 3790 curr->lockdep_depth = i; 3791 curr->curr_chain_key = hlock->prev_chain_key; 3792 3793 if (reacquire_held_locks(curr, depth, i + 1)) 3794 return 0; 3795 3796 /* 3797 * We had N bottles of beer on the wall, we drank one, but now 3798 * there's not N-1 bottles of beer left on the wall... 3799 */ 3800 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) 3801 return 0; 3802 3803 return 1; 3804 } 3805 3806 static int __lock_is_held(struct lockdep_map *lock, int read) 3807 { 3808 struct task_struct *curr = current; 3809 int i; 3810 3811 for (i = 0; i < curr->lockdep_depth; i++) { 3812 struct held_lock *hlock = curr->held_locks + i; 3813 3814 if (match_held_lock(hlock, lock)) { 3815 if (read == -1 || hlock->read == read) 3816 return 1; 3817 3818 return 0; 3819 } 3820 } 3821 3822 return 0; 3823 } 3824 3825 static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) 3826 { 3827 struct pin_cookie cookie = NIL_COOKIE; 3828 struct task_struct *curr = current; 3829 int i; 3830 3831 if (unlikely(!debug_locks)) 3832 return cookie; 3833 3834 for (i = 0; i < curr->lockdep_depth; i++) { 3835 struct held_lock *hlock = curr->held_locks + i; 3836 3837 if (match_held_lock(hlock, lock)) { 3838 /* 3839 * Grab 16bits of randomness; this is sufficient to not 3840 * be guessable and still allows some pin nesting in 3841 * our u32 pin_count. 3842 */ 3843 cookie.val = 1 + (prandom_u32() >> 16); 3844 hlock->pin_count += cookie.val; 3845 return cookie; 3846 } 3847 } 3848 3849 WARN(1, "pinning an unheld lock\n"); 3850 return cookie; 3851 } 3852 3853 static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) 3854 { 3855 struct task_struct *curr = current; 3856 int i; 3857 3858 if (unlikely(!debug_locks)) 3859 return; 3860 3861 for (i = 0; i < curr->lockdep_depth; i++) { 3862 struct held_lock *hlock = curr->held_locks + i; 3863 3864 if (match_held_lock(hlock, lock)) { 3865 hlock->pin_count += cookie.val; 3866 return; 3867 } 3868 } 3869 3870 WARN(1, "pinning an unheld lock\n"); 3871 } 3872 3873 static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) 3874 { 3875 struct task_struct *curr = current; 3876 int i; 3877 3878 if (unlikely(!debug_locks)) 3879 return; 3880 3881 for (i = 0; i < curr->lockdep_depth; i++) { 3882 struct held_lock *hlock = curr->held_locks + i; 3883 3884 if (match_held_lock(hlock, lock)) { 3885 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n")) 3886 return; 3887 3888 hlock->pin_count -= cookie.val; 3889 3890 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n")) 3891 hlock->pin_count = 0; 3892 3893 return; 3894 } 3895 } 3896 3897 WARN(1, "unpinning an unheld lock\n"); 3898 } 3899 3900 /* 3901 * Check whether we follow the irq-flags state precisely: 3902 */ 3903 static void check_flags(unsigned long flags) 3904 { 3905 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \ 3906 defined(CONFIG_TRACE_IRQFLAGS) 3907 if (!debug_locks) 3908 return; 3909 3910 if (irqs_disabled_flags(flags)) { 3911 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { 3912 printk("possible reason: unannotated irqs-off.\n"); 3913 } 3914 } else { 3915 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { 3916 printk("possible reason: unannotated irqs-on.\n"); 3917 } 3918 } 3919 3920 /* 3921 * We dont accurately track softirq state in e.g. 3922 * hardirq contexts (such as on 4KSTACKS), so only 3923 * check if not in hardirq contexts: 3924 */ 3925 if (!hardirq_count()) { 3926 if (softirq_count()) { 3927 /* like the above, but with softirqs */ 3928 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); 3929 } else { 3930 /* lick the above, does it taste good? */ 3931 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); 3932 } 3933 } 3934 3935 if (!debug_locks) 3936 print_irqtrace_events(current); 3937 #endif 3938 } 3939 3940 void lock_set_class(struct lockdep_map *lock, const char *name, 3941 struct lock_class_key *key, unsigned int subclass, 3942 unsigned long ip) 3943 { 3944 unsigned long flags; 3945 3946 if (unlikely(current->lockdep_recursion)) 3947 return; 3948 3949 raw_local_irq_save(flags); 3950 current->lockdep_recursion = 1; 3951 check_flags(flags); 3952 if (__lock_set_class(lock, name, key, subclass, ip)) 3953 check_chain_key(current); 3954 current->lockdep_recursion = 0; 3955 raw_local_irq_restore(flags); 3956 } 3957 EXPORT_SYMBOL_GPL(lock_set_class); 3958 3959 void lock_downgrade(struct lockdep_map *lock, unsigned long ip) 3960 { 3961 unsigned long flags; 3962 3963 if (unlikely(current->lockdep_recursion)) 3964 return; 3965 3966 raw_local_irq_save(flags); 3967 current->lockdep_recursion = 1; 3968 check_flags(flags); 3969 if (__lock_downgrade(lock, ip)) 3970 check_chain_key(current); 3971 current->lockdep_recursion = 0; 3972 raw_local_irq_restore(flags); 3973 } 3974 EXPORT_SYMBOL_GPL(lock_downgrade); 3975 3976 /* 3977 * We are not always called with irqs disabled - do that here, 3978 * and also avoid lockdep recursion: 3979 */ 3980 void lock_acquire(struct lockdep_map *lock, unsigned int subclass, 3981 int trylock, int read, int check, 3982 struct lockdep_map *nest_lock, unsigned long ip) 3983 { 3984 unsigned long flags; 3985 3986 if (unlikely(current->lockdep_recursion)) 3987 return; 3988 3989 raw_local_irq_save(flags); 3990 check_flags(flags); 3991 3992 current->lockdep_recursion = 1; 3993 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); 3994 __lock_acquire(lock, subclass, trylock, read, check, 3995 irqs_disabled_flags(flags), nest_lock, ip, 0, 0); 3996 current->lockdep_recursion = 0; 3997 raw_local_irq_restore(flags); 3998 } 3999 EXPORT_SYMBOL_GPL(lock_acquire); 4000 4001 void lock_release(struct lockdep_map *lock, int nested, 4002 unsigned long ip) 4003 { 4004 unsigned long flags; 4005 4006 if (unlikely(current->lockdep_recursion)) 4007 return; 4008 4009 raw_local_irq_save(flags); 4010 check_flags(flags); 4011 current->lockdep_recursion = 1; 4012 trace_lock_release(lock, ip); 4013 if (__lock_release(lock, nested, ip)) 4014 check_chain_key(current); 4015 current->lockdep_recursion = 0; 4016 raw_local_irq_restore(flags); 4017 } 4018 EXPORT_SYMBOL_GPL(lock_release); 4019 4020 int lock_is_held_type(struct lockdep_map *lock, int read) 4021 { 4022 unsigned long flags; 4023 int ret = 0; 4024 4025 if (unlikely(current->lockdep_recursion)) 4026 return 1; /* avoid false negative lockdep_assert_held() */ 4027 4028 raw_local_irq_save(flags); 4029 check_flags(flags); 4030 4031 current->lockdep_recursion = 1; 4032 ret = __lock_is_held(lock, read); 4033 current->lockdep_recursion = 0; 4034 raw_local_irq_restore(flags); 4035 4036 return ret; 4037 } 4038 EXPORT_SYMBOL_GPL(lock_is_held_type); 4039 4040 struct pin_cookie lock_pin_lock(struct lockdep_map *lock) 4041 { 4042 struct pin_cookie cookie = NIL_COOKIE; 4043 unsigned long flags; 4044 4045 if (unlikely(current->lockdep_recursion)) 4046 return cookie; 4047 4048 raw_local_irq_save(flags); 4049 check_flags(flags); 4050 4051 current->lockdep_recursion = 1; 4052 cookie = __lock_pin_lock(lock); 4053 current->lockdep_recursion = 0; 4054 raw_local_irq_restore(flags); 4055 4056 return cookie; 4057 } 4058 EXPORT_SYMBOL_GPL(lock_pin_lock); 4059 4060 void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) 4061 { 4062 unsigned long flags; 4063 4064 if (unlikely(current->lockdep_recursion)) 4065 return; 4066 4067 raw_local_irq_save(flags); 4068 check_flags(flags); 4069 4070 current->lockdep_recursion = 1; 4071 __lock_repin_lock(lock, cookie); 4072 current->lockdep_recursion = 0; 4073 raw_local_irq_restore(flags); 4074 } 4075 EXPORT_SYMBOL_GPL(lock_repin_lock); 4076 4077 void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) 4078 { 4079 unsigned long flags; 4080 4081 if (unlikely(current->lockdep_recursion)) 4082 return; 4083 4084 raw_local_irq_save(flags); 4085 check_flags(flags); 4086 4087 current->lockdep_recursion = 1; 4088 __lock_unpin_lock(lock, cookie); 4089 current->lockdep_recursion = 0; 4090 raw_local_irq_restore(flags); 4091 } 4092 EXPORT_SYMBOL_GPL(lock_unpin_lock); 4093 4094 #ifdef CONFIG_LOCK_STAT 4095 static int 4096 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, 4097 unsigned long ip) 4098 { 4099 if (!debug_locks_off()) 4100 return 0; 4101 if (debug_locks_silent) 4102 return 0; 4103 4104 pr_warn("\n"); 4105 pr_warn("=================================\n"); 4106 pr_warn("WARNING: bad contention detected!\n"); 4107 print_kernel_ident(); 4108 pr_warn("---------------------------------\n"); 4109 pr_warn("%s/%d is trying to contend lock (", 4110 curr->comm, task_pid_nr(curr)); 4111 print_lockdep_cache(lock); 4112 pr_cont(") at:\n"); 4113 print_ip_sym(ip); 4114 pr_warn("but there are no locks held!\n"); 4115 pr_warn("\nother info that might help us debug this:\n"); 4116 lockdep_print_held_locks(curr); 4117 4118 pr_warn("\nstack backtrace:\n"); 4119 dump_stack(); 4120 4121 return 0; 4122 } 4123 4124 static void 4125 __lock_contended(struct lockdep_map *lock, unsigned long ip) 4126 { 4127 struct task_struct *curr = current; 4128 struct held_lock *hlock; 4129 struct lock_class_stats *stats; 4130 unsigned int depth; 4131 int i, contention_point, contending_point; 4132 4133 depth = curr->lockdep_depth; 4134 /* 4135 * Whee, we contended on this lock, except it seems we're not 4136 * actually trying to acquire anything much at all.. 4137 */ 4138 if (DEBUG_LOCKS_WARN_ON(!depth)) 4139 return; 4140 4141 hlock = find_held_lock(curr, lock, depth, &i); 4142 if (!hlock) { 4143 print_lock_contention_bug(curr, lock, ip); 4144 return; 4145 } 4146 4147 if (hlock->instance != lock) 4148 return; 4149 4150 hlock->waittime_stamp = lockstat_clock(); 4151 4152 contention_point = lock_point(hlock_class(hlock)->contention_point, ip); 4153 contending_point = lock_point(hlock_class(hlock)->contending_point, 4154 lock->ip); 4155 4156 stats = get_lock_stats(hlock_class(hlock)); 4157 if (contention_point < LOCKSTAT_POINTS) 4158 stats->contention_point[contention_point]++; 4159 if (contending_point < LOCKSTAT_POINTS) 4160 stats->contending_point[contending_point]++; 4161 if (lock->cpu != smp_processor_id()) 4162 stats->bounces[bounce_contended + !!hlock->read]++; 4163 put_lock_stats(stats); 4164 } 4165 4166 static void 4167 __lock_acquired(struct lockdep_map *lock, unsigned long ip) 4168 { 4169 struct task_struct *curr = current; 4170 struct held_lock *hlock; 4171 struct lock_class_stats *stats; 4172 unsigned int depth; 4173 u64 now, waittime = 0; 4174 int i, cpu; 4175 4176 depth = curr->lockdep_depth; 4177 /* 4178 * Yay, we acquired ownership of this lock we didn't try to 4179 * acquire, how the heck did that happen? 4180 */ 4181 if (DEBUG_LOCKS_WARN_ON(!depth)) 4182 return; 4183 4184 hlock = find_held_lock(curr, lock, depth, &i); 4185 if (!hlock) { 4186 print_lock_contention_bug(curr, lock, _RET_IP_); 4187 return; 4188 } 4189 4190 if (hlock->instance != lock) 4191 return; 4192 4193 cpu = smp_processor_id(); 4194 if (hlock->waittime_stamp) { 4195 now = lockstat_clock(); 4196 waittime = now - hlock->waittime_stamp; 4197 hlock->holdtime_stamp = now; 4198 } 4199 4200 trace_lock_acquired(lock, ip); 4201 4202 stats = get_lock_stats(hlock_class(hlock)); 4203 if (waittime) { 4204 if (hlock->read) 4205 lock_time_inc(&stats->read_waittime, waittime); 4206 else 4207 lock_time_inc(&stats->write_waittime, waittime); 4208 } 4209 if (lock->cpu != cpu) 4210 stats->bounces[bounce_acquired + !!hlock->read]++; 4211 put_lock_stats(stats); 4212 4213 lock->cpu = cpu; 4214 lock->ip = ip; 4215 } 4216 4217 void lock_contended(struct lockdep_map *lock, unsigned long ip) 4218 { 4219 unsigned long flags; 4220 4221 if (unlikely(!lock_stat)) 4222 return; 4223 4224 if (unlikely(current->lockdep_recursion)) 4225 return; 4226 4227 raw_local_irq_save(flags); 4228 check_flags(flags); 4229 current->lockdep_recursion = 1; 4230 trace_lock_contended(lock, ip); 4231 __lock_contended(lock, ip); 4232 current->lockdep_recursion = 0; 4233 raw_local_irq_restore(flags); 4234 } 4235 EXPORT_SYMBOL_GPL(lock_contended); 4236 4237 void lock_acquired(struct lockdep_map *lock, unsigned long ip) 4238 { 4239 unsigned long flags; 4240 4241 if (unlikely(!lock_stat)) 4242 return; 4243 4244 if (unlikely(current->lockdep_recursion)) 4245 return; 4246 4247 raw_local_irq_save(flags); 4248 check_flags(flags); 4249 current->lockdep_recursion = 1; 4250 __lock_acquired(lock, ip); 4251 current->lockdep_recursion = 0; 4252 raw_local_irq_restore(flags); 4253 } 4254 EXPORT_SYMBOL_GPL(lock_acquired); 4255 #endif 4256 4257 /* 4258 * Used by the testsuite, sanitize the validator state 4259 * after a simulated failure: 4260 */ 4261 4262 void lockdep_reset(void) 4263 { 4264 unsigned long flags; 4265 int i; 4266 4267 raw_local_irq_save(flags); 4268 current->curr_chain_key = 0; 4269 current->lockdep_depth = 0; 4270 current->lockdep_recursion = 0; 4271 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); 4272 nr_hardirq_chains = 0; 4273 nr_softirq_chains = 0; 4274 nr_process_chains = 0; 4275 debug_locks = 1; 4276 for (i = 0; i < CHAINHASH_SIZE; i++) 4277 INIT_HLIST_HEAD(chainhash_table + i); 4278 raw_local_irq_restore(flags); 4279 } 4280 4281 static void zap_class(struct lock_class *class) 4282 { 4283 int i; 4284 4285 /* 4286 * Remove all dependencies this lock is 4287 * involved in: 4288 */ 4289 for (i = 0; i < nr_list_entries; i++) { 4290 if (list_entries[i].class == class) 4291 list_del_rcu(&list_entries[i].entry); 4292 } 4293 /* 4294 * Unhash the class and remove it from the all_lock_classes list: 4295 */ 4296 hlist_del_rcu(&class->hash_entry); 4297 list_del_rcu(&class->lock_entry); 4298 4299 RCU_INIT_POINTER(class->key, NULL); 4300 RCU_INIT_POINTER(class->name, NULL); 4301 } 4302 4303 static inline int within(const void *addr, void *start, unsigned long size) 4304 { 4305 return addr >= start && addr < start + size; 4306 } 4307 4308 /* 4309 * Used in module.c to remove lock classes from memory that is going to be 4310 * freed; and possibly re-used by other modules. 4311 * 4312 * We will have had one sync_sched() before getting here, so we're guaranteed 4313 * nobody will look up these exact classes -- they're properly dead but still 4314 * allocated. 4315 */ 4316 void lockdep_free_key_range(void *start, unsigned long size) 4317 { 4318 struct lock_class *class; 4319 struct hlist_head *head; 4320 unsigned long flags; 4321 int i; 4322 int locked; 4323 4324 raw_local_irq_save(flags); 4325 locked = graph_lock(); 4326 4327 /* 4328 * Unhash all classes that were created by this module: 4329 */ 4330 for (i = 0; i < CLASSHASH_SIZE; i++) { 4331 head = classhash_table + i; 4332 hlist_for_each_entry_rcu(class, head, hash_entry) { 4333 if (within(class->key, start, size)) 4334 zap_class(class); 4335 else if (within(class->name, start, size)) 4336 zap_class(class); 4337 } 4338 } 4339 4340 if (locked) 4341 graph_unlock(); 4342 raw_local_irq_restore(flags); 4343 4344 /* 4345 * Wait for any possible iterators from look_up_lock_class() to pass 4346 * before continuing to free the memory they refer to. 4347 * 4348 * sync_sched() is sufficient because the read-side is IRQ disable. 4349 */ 4350 synchronize_sched(); 4351 4352 /* 4353 * XXX at this point we could return the resources to the pool; 4354 * instead we leak them. We would need to change to bitmap allocators 4355 * instead of the linear allocators we have now. 4356 */ 4357 } 4358 4359 void lockdep_reset_lock(struct lockdep_map *lock) 4360 { 4361 struct lock_class *class; 4362 struct hlist_head *head; 4363 unsigned long flags; 4364 int i, j; 4365 int locked; 4366 4367 raw_local_irq_save(flags); 4368 4369 /* 4370 * Remove all classes this lock might have: 4371 */ 4372 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { 4373 /* 4374 * If the class exists we look it up and zap it: 4375 */ 4376 class = look_up_lock_class(lock, j); 4377 if (!IS_ERR_OR_NULL(class)) 4378 zap_class(class); 4379 } 4380 /* 4381 * Debug check: in the end all mapped classes should 4382 * be gone. 4383 */ 4384 locked = graph_lock(); 4385 for (i = 0; i < CLASSHASH_SIZE; i++) { 4386 head = classhash_table + i; 4387 hlist_for_each_entry_rcu(class, head, hash_entry) { 4388 int match = 0; 4389 4390 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) 4391 match |= class == lock->class_cache[j]; 4392 4393 if (unlikely(match)) { 4394 if (debug_locks_off_graph_unlock()) { 4395 /* 4396 * We all just reset everything, how did it match? 4397 */ 4398 WARN_ON(1); 4399 } 4400 goto out_restore; 4401 } 4402 } 4403 } 4404 if (locked) 4405 graph_unlock(); 4406 4407 out_restore: 4408 raw_local_irq_restore(flags); 4409 } 4410 4411 void __init lockdep_info(void) 4412 { 4413 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); 4414 4415 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); 4416 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); 4417 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); 4418 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); 4419 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); 4420 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); 4421 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); 4422 4423 printk(" memory used by lock dependency info: %lu kB\n", 4424 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + 4425 sizeof(struct list_head) * CLASSHASH_SIZE + 4426 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + 4427 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + 4428 sizeof(struct list_head) * CHAINHASH_SIZE 4429 #ifdef CONFIG_PROVE_LOCKING 4430 + sizeof(struct circular_queue) 4431 #endif 4432 ) / 1024 4433 ); 4434 4435 printk(" per task-struct memory footprint: %lu bytes\n", 4436 sizeof(struct held_lock) * MAX_LOCK_DEPTH); 4437 } 4438 4439 static void 4440 print_freed_lock_bug(struct task_struct *curr, const void *mem_from, 4441 const void *mem_to, struct held_lock *hlock) 4442 { 4443 if (!debug_locks_off()) 4444 return; 4445 if (debug_locks_silent) 4446 return; 4447 4448 pr_warn("\n"); 4449 pr_warn("=========================\n"); 4450 pr_warn("WARNING: held lock freed!\n"); 4451 print_kernel_ident(); 4452 pr_warn("-------------------------\n"); 4453 pr_warn("%s/%d is freeing memory %p-%p, with a lock still held there!\n", 4454 curr->comm, task_pid_nr(curr), mem_from, mem_to-1); 4455 print_lock(hlock); 4456 lockdep_print_held_locks(curr); 4457 4458 pr_warn("\nstack backtrace:\n"); 4459 dump_stack(); 4460 } 4461 4462 static inline int not_in_range(const void* mem_from, unsigned long mem_len, 4463 const void* lock_from, unsigned long lock_len) 4464 { 4465 return lock_from + lock_len <= mem_from || 4466 mem_from + mem_len <= lock_from; 4467 } 4468 4469 /* 4470 * Called when kernel memory is freed (or unmapped), or if a lock 4471 * is destroyed or reinitialized - this code checks whether there is 4472 * any held lock in the memory range of <from> to <to>: 4473 */ 4474 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) 4475 { 4476 struct task_struct *curr = current; 4477 struct held_lock *hlock; 4478 unsigned long flags; 4479 int i; 4480 4481 if (unlikely(!debug_locks)) 4482 return; 4483 4484 local_irq_save(flags); 4485 for (i = 0; i < curr->lockdep_depth; i++) { 4486 hlock = curr->held_locks + i; 4487 4488 if (not_in_range(mem_from, mem_len, hlock->instance, 4489 sizeof(*hlock->instance))) 4490 continue; 4491 4492 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); 4493 break; 4494 } 4495 local_irq_restore(flags); 4496 } 4497 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); 4498 4499 static void print_held_locks_bug(void) 4500 { 4501 if (!debug_locks_off()) 4502 return; 4503 if (debug_locks_silent) 4504 return; 4505 4506 pr_warn("\n"); 4507 pr_warn("====================================\n"); 4508 pr_warn("WARNING: %s/%d still has locks held!\n", 4509 current->comm, task_pid_nr(current)); 4510 print_kernel_ident(); 4511 pr_warn("------------------------------------\n"); 4512 lockdep_print_held_locks(current); 4513 pr_warn("\nstack backtrace:\n"); 4514 dump_stack(); 4515 } 4516 4517 void debug_check_no_locks_held(void) 4518 { 4519 if (unlikely(current->lockdep_depth > 0)) 4520 print_held_locks_bug(); 4521 } 4522 EXPORT_SYMBOL_GPL(debug_check_no_locks_held); 4523 4524 #ifdef __KERNEL__ 4525 void debug_show_all_locks(void) 4526 { 4527 struct task_struct *g, *p; 4528 int count = 10; 4529 int unlock = 1; 4530 4531 if (unlikely(!debug_locks)) { 4532 pr_warn("INFO: lockdep is turned off.\n"); 4533 return; 4534 } 4535 pr_warn("\nShowing all locks held in the system:\n"); 4536 4537 /* 4538 * Here we try to get the tasklist_lock as hard as possible, 4539 * if not successful after 2 seconds we ignore it (but keep 4540 * trying). This is to enable a debug printout even if a 4541 * tasklist_lock-holding task deadlocks or crashes. 4542 */ 4543 retry: 4544 if (!read_trylock(&tasklist_lock)) { 4545 if (count == 10) 4546 pr_warn("hm, tasklist_lock locked, retrying... "); 4547 if (count) { 4548 count--; 4549 pr_cont(" #%d", 10-count); 4550 mdelay(200); 4551 goto retry; 4552 } 4553 pr_cont(" ignoring it.\n"); 4554 unlock = 0; 4555 } else { 4556 if (count != 10) 4557 pr_cont(" locked it.\n"); 4558 } 4559 4560 do_each_thread(g, p) { 4561 /* 4562 * It's not reliable to print a task's held locks 4563 * if it's not sleeping (or if it's not the current 4564 * task): 4565 */ 4566 if (p->state == TASK_RUNNING && p != current) 4567 continue; 4568 if (p->lockdep_depth) 4569 lockdep_print_held_locks(p); 4570 if (!unlock) 4571 if (read_trylock(&tasklist_lock)) 4572 unlock = 1; 4573 } while_each_thread(g, p); 4574 4575 pr_warn("\n"); 4576 pr_warn("=============================================\n\n"); 4577 4578 if (unlock) 4579 read_unlock(&tasklist_lock); 4580 } 4581 EXPORT_SYMBOL_GPL(debug_show_all_locks); 4582 #endif 4583 4584 /* 4585 * Careful: only use this function if you are sure that 4586 * the task cannot run in parallel! 4587 */ 4588 void debug_show_held_locks(struct task_struct *task) 4589 { 4590 if (unlikely(!debug_locks)) { 4591 printk("INFO: lockdep is turned off.\n"); 4592 return; 4593 } 4594 lockdep_print_held_locks(task); 4595 } 4596 EXPORT_SYMBOL_GPL(debug_show_held_locks); 4597 4598 asmlinkage __visible void lockdep_sys_exit(void) 4599 { 4600 struct task_struct *curr = current; 4601 4602 if (unlikely(curr->lockdep_depth)) { 4603 if (!debug_locks_off()) 4604 return; 4605 pr_warn("\n"); 4606 pr_warn("================================================\n"); 4607 pr_warn("WARNING: lock held when returning to user space!\n"); 4608 print_kernel_ident(); 4609 pr_warn("------------------------------------------------\n"); 4610 pr_warn("%s/%d is leaving the kernel with locks still held!\n", 4611 curr->comm, curr->pid); 4612 lockdep_print_held_locks(curr); 4613 } 4614 4615 /* 4616 * The lock history for each syscall should be independent. So wipe the 4617 * slate clean on return to userspace. 4618 */ 4619 lockdep_invariant_state(false); 4620 } 4621 4622 void lockdep_rcu_suspicious(const char *file, const int line, const char *s) 4623 { 4624 struct task_struct *curr = current; 4625 4626 /* Note: the following can be executed concurrently, so be careful. */ 4627 pr_warn("\n"); 4628 pr_warn("=============================\n"); 4629 pr_warn("WARNING: suspicious RCU usage\n"); 4630 print_kernel_ident(); 4631 pr_warn("-----------------------------\n"); 4632 pr_warn("%s:%d %s!\n", file, line, s); 4633 pr_warn("\nother info that might help us debug this:\n\n"); 4634 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n", 4635 !rcu_lockdep_current_cpu_online() 4636 ? "RCU used illegally from offline CPU!\n" 4637 : !rcu_is_watching() 4638 ? "RCU used illegally from idle CPU!\n" 4639 : "", 4640 rcu_scheduler_active, debug_locks); 4641 4642 /* 4643 * If a CPU is in the RCU-free window in idle (ie: in the section 4644 * between rcu_idle_enter() and rcu_idle_exit(), then RCU 4645 * considers that CPU to be in an "extended quiescent state", 4646 * which means that RCU will be completely ignoring that CPU. 4647 * Therefore, rcu_read_lock() and friends have absolutely no 4648 * effect on a CPU running in that state. In other words, even if 4649 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well 4650 * delete data structures out from under it. RCU really has no 4651 * choice here: we need to keep an RCU-free window in idle where 4652 * the CPU may possibly enter into low power mode. This way we can 4653 * notice an extended quiescent state to other CPUs that started a grace 4654 * period. Otherwise we would delay any grace period as long as we run 4655 * in the idle task. 4656 * 4657 * So complain bitterly if someone does call rcu_read_lock(), 4658 * rcu_read_lock_bh() and so on from extended quiescent states. 4659 */ 4660 if (!rcu_is_watching()) 4661 pr_warn("RCU used illegally from extended quiescent state!\n"); 4662 4663 lockdep_print_held_locks(curr); 4664 pr_warn("\nstack backtrace:\n"); 4665 dump_stack(); 4666 } 4667 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); 4668 4669 #ifdef CONFIG_LOCKDEP_CROSSRELEASE 4670 4671 /* 4672 * Crossrelease works by recording a lock history for each thread and 4673 * connecting those historic locks that were taken after the 4674 * wait_for_completion() in the complete() context. 4675 * 4676 * Task-A Task-B 4677 * 4678 * mutex_lock(&A); 4679 * mutex_unlock(&A); 4680 * 4681 * wait_for_completion(&C); 4682 * lock_acquire_crosslock(); 4683 * atomic_inc_return(&cross_gen_id); 4684 * | 4685 * | mutex_lock(&B); 4686 * | mutex_unlock(&B); 4687 * | 4688 * | complete(&C); 4689 * `-- lock_commit_crosslock(); 4690 * 4691 * Which will then add a dependency between B and C. 4692 */ 4693 4694 #define xhlock(i) (current->xhlocks[(i) % MAX_XHLOCKS_NR]) 4695 4696 /* 4697 * Whenever a crosslock is held, cross_gen_id will be increased. 4698 */ 4699 static atomic_t cross_gen_id; /* Can be wrapped */ 4700 4701 /* 4702 * Make an entry of the ring buffer invalid. 4703 */ 4704 static inline void invalidate_xhlock(struct hist_lock *xhlock) 4705 { 4706 /* 4707 * Normally, xhlock->hlock.instance must be !NULL. 4708 */ 4709 xhlock->hlock.instance = NULL; 4710 } 4711 4712 /* 4713 * Lock history stacks; we have 2 nested lock history stacks: 4714 * 4715 * HARD(IRQ) 4716 * SOFT(IRQ) 4717 * 4718 * The thing is that once we complete a HARD/SOFT IRQ the future task locks 4719 * should not depend on any of the locks observed while running the IRQ. So 4720 * what we do is rewind the history buffer and erase all our knowledge of that 4721 * temporal event. 4722 */ 4723 4724 void crossrelease_hist_start(enum xhlock_context_t c) 4725 { 4726 struct task_struct *cur = current; 4727 4728 if (!cur->xhlocks) 4729 return; 4730 4731 cur->xhlock_idx_hist[c] = cur->xhlock_idx; 4732 cur->hist_id_save[c] = cur->hist_id; 4733 } 4734 4735 void crossrelease_hist_end(enum xhlock_context_t c) 4736 { 4737 struct task_struct *cur = current; 4738 4739 if (cur->xhlocks) { 4740 unsigned int idx = cur->xhlock_idx_hist[c]; 4741 struct hist_lock *h = &xhlock(idx); 4742 4743 cur->xhlock_idx = idx; 4744 4745 /* Check if the ring was overwritten. */ 4746 if (h->hist_id != cur->hist_id_save[c]) 4747 invalidate_xhlock(h); 4748 } 4749 } 4750 4751 /* 4752 * lockdep_invariant_state() is used to annotate independence inside a task, to 4753 * make one task look like multiple independent 'tasks'. 4754 * 4755 * Take for instance workqueues; each work is independent of the last. The 4756 * completion of a future work does not depend on the completion of a past work 4757 * (in general). Therefore we must not carry that (lock) dependency across 4758 * works. 4759 * 4760 * This is true for many things; pretty much all kthreads fall into this 4761 * pattern, where they have an invariant state and future completions do not 4762 * depend on past completions. Its just that since they all have the 'same' 4763 * form -- the kthread does the same over and over -- it doesn't typically 4764 * matter. 4765 * 4766 * The same is true for system-calls, once a system call is completed (we've 4767 * returned to userspace) the next system call does not depend on the lock 4768 * history of the previous system call. 4769 * 4770 * They key property for independence, this invariant state, is that it must be 4771 * a point where we hold no locks and have no history. Because if we were to 4772 * hold locks, the restore at _end() would not necessarily recover it's history 4773 * entry. Similarly, independence per-definition means it does not depend on 4774 * prior state. 4775 */ 4776 void lockdep_invariant_state(bool force) 4777 { 4778 /* 4779 * We call this at an invariant point, no current state, no history. 4780 * Verify the former, enforce the latter. 4781 */ 4782 WARN_ON_ONCE(!force && current->lockdep_depth); 4783 invalidate_xhlock(&xhlock(current->xhlock_idx)); 4784 } 4785 4786 static int cross_lock(struct lockdep_map *lock) 4787 { 4788 return lock ? lock->cross : 0; 4789 } 4790 4791 /* 4792 * This is needed to decide the relationship between wrapable variables. 4793 */ 4794 static inline int before(unsigned int a, unsigned int b) 4795 { 4796 return (int)(a - b) < 0; 4797 } 4798 4799 static inline struct lock_class *xhlock_class(struct hist_lock *xhlock) 4800 { 4801 return hlock_class(&xhlock->hlock); 4802 } 4803 4804 static inline struct lock_class *xlock_class(struct cross_lock *xlock) 4805 { 4806 return hlock_class(&xlock->hlock); 4807 } 4808 4809 /* 4810 * Should we check a dependency with previous one? 4811 */ 4812 static inline int depend_before(struct held_lock *hlock) 4813 { 4814 return hlock->read != 2 && hlock->check && !hlock->trylock; 4815 } 4816 4817 /* 4818 * Should we check a dependency with next one? 4819 */ 4820 static inline int depend_after(struct held_lock *hlock) 4821 { 4822 return hlock->read != 2 && hlock->check; 4823 } 4824 4825 /* 4826 * Check if the xhlock is valid, which would be false if, 4827 * 4828 * 1. Has not used after initializaion yet. 4829 * 2. Got invalidated. 4830 * 4831 * Remind hist_lock is implemented as a ring buffer. 4832 */ 4833 static inline int xhlock_valid(struct hist_lock *xhlock) 4834 { 4835 /* 4836 * xhlock->hlock.instance must be !NULL. 4837 */ 4838 return !!xhlock->hlock.instance; 4839 } 4840 4841 /* 4842 * Record a hist_lock entry. 4843 * 4844 * Irq disable is only required. 4845 */ 4846 static void add_xhlock(struct held_lock *hlock) 4847 { 4848 unsigned int idx = ++current->xhlock_idx; 4849 struct hist_lock *xhlock = &xhlock(idx); 4850 4851 #ifdef CONFIG_DEBUG_LOCKDEP 4852 /* 4853 * This can be done locklessly because they are all task-local 4854 * state, we must however ensure IRQs are disabled. 4855 */ 4856 WARN_ON_ONCE(!irqs_disabled()); 4857 #endif 4858 4859 /* Initialize hist_lock's members */ 4860 xhlock->hlock = *hlock; 4861 xhlock->hist_id = ++current->hist_id; 4862 4863 xhlock->trace.nr_entries = 0; 4864 xhlock->trace.max_entries = MAX_XHLOCK_TRACE_ENTRIES; 4865 xhlock->trace.entries = xhlock->trace_entries; 4866 xhlock->trace.skip = 3; 4867 save_stack_trace(&xhlock->trace); 4868 } 4869 4870 static inline int same_context_xhlock(struct hist_lock *xhlock) 4871 { 4872 return xhlock->hlock.irq_context == task_irq_context(current); 4873 } 4874 4875 /* 4876 * This should be lockless as far as possible because this would be 4877 * called very frequently. 4878 */ 4879 static void check_add_xhlock(struct held_lock *hlock) 4880 { 4881 /* 4882 * Record a hist_lock, only in case that acquisitions ahead 4883 * could depend on the held_lock. For example, if the held_lock 4884 * is trylock then acquisitions ahead never depends on that. 4885 * In that case, we don't need to record it. Just return. 4886 */ 4887 if (!current->xhlocks || !depend_before(hlock)) 4888 return; 4889 4890 add_xhlock(hlock); 4891 } 4892 4893 /* 4894 * For crosslock. 4895 */ 4896 static int add_xlock(struct held_lock *hlock) 4897 { 4898 struct cross_lock *xlock; 4899 unsigned int gen_id; 4900 4901 if (!graph_lock()) 4902 return 0; 4903 4904 xlock = &((struct lockdep_map_cross *)hlock->instance)->xlock; 4905 4906 /* 4907 * When acquisitions for a crosslock are overlapped, we use 4908 * nr_acquire to perform commit for them, based on cross_gen_id 4909 * of the first acquisition, which allows to add additional 4910 * dependencies. 4911 * 4912 * Moreover, when no acquisition of a crosslock is in progress, 4913 * we should not perform commit because the lock might not exist 4914 * any more, which might cause incorrect memory access. So we 4915 * have to track the number of acquisitions of a crosslock. 4916 * 4917 * depend_after() is necessary to initialize only the first 4918 * valid xlock so that the xlock can be used on its commit. 4919 */ 4920 if (xlock->nr_acquire++ && depend_after(&xlock->hlock)) 4921 goto unlock; 4922 4923 gen_id = (unsigned int)atomic_inc_return(&cross_gen_id); 4924 xlock->hlock = *hlock; 4925 xlock->hlock.gen_id = gen_id; 4926 unlock: 4927 graph_unlock(); 4928 return 1; 4929 } 4930 4931 /* 4932 * Called for both normal and crosslock acquires. Normal locks will be 4933 * pushed on the hist_lock queue. Cross locks will record state and 4934 * stop regular lock_acquire() to avoid being placed on the held_lock 4935 * stack. 4936 * 4937 * Return: 0 - failure; 4938 * 1 - crosslock, done; 4939 * 2 - normal lock, continue to held_lock[] ops. 4940 */ 4941 static int lock_acquire_crosslock(struct held_lock *hlock) 4942 { 4943 /* 4944 * CONTEXT 1 CONTEXT 2 4945 * --------- --------- 4946 * lock A (cross) 4947 * X = atomic_inc_return(&cross_gen_id) 4948 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 4949 * Y = atomic_read_acquire(&cross_gen_id) 4950 * lock B 4951 * 4952 * atomic_read_acquire() is for ordering between A and B, 4953 * IOW, A happens before B, when CONTEXT 2 see Y >= X. 4954 * 4955 * Pairs with atomic_inc_return() in add_xlock(). 4956 */ 4957 hlock->gen_id = (unsigned int)atomic_read_acquire(&cross_gen_id); 4958 4959 if (cross_lock(hlock->instance)) 4960 return add_xlock(hlock); 4961 4962 check_add_xhlock(hlock); 4963 return 2; 4964 } 4965 4966 static int copy_trace(struct stack_trace *trace) 4967 { 4968 unsigned long *buf = stack_trace + nr_stack_trace_entries; 4969 unsigned int max_nr = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; 4970 unsigned int nr = min(max_nr, trace->nr_entries); 4971 4972 trace->nr_entries = nr; 4973 memcpy(buf, trace->entries, nr * sizeof(trace->entries[0])); 4974 trace->entries = buf; 4975 nr_stack_trace_entries += nr; 4976 4977 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { 4978 if (!debug_locks_off_graph_unlock()) 4979 return 0; 4980 4981 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); 4982 dump_stack(); 4983 4984 return 0; 4985 } 4986 4987 return 1; 4988 } 4989 4990 static int commit_xhlock(struct cross_lock *xlock, struct hist_lock *xhlock) 4991 { 4992 unsigned int xid, pid; 4993 u64 chain_key; 4994 4995 xid = xlock_class(xlock) - lock_classes; 4996 chain_key = iterate_chain_key((u64)0, xid); 4997 pid = xhlock_class(xhlock) - lock_classes; 4998 chain_key = iterate_chain_key(chain_key, pid); 4999 5000 if (lookup_chain_cache(chain_key)) 5001 return 1; 5002 5003 if (!add_chain_cache_classes(xid, pid, xhlock->hlock.irq_context, 5004 chain_key)) 5005 return 0; 5006 5007 if (!check_prev_add(current, &xlock->hlock, &xhlock->hlock, 1, 5008 &xhlock->trace, copy_trace)) 5009 return 0; 5010 5011 return 1; 5012 } 5013 5014 static void commit_xhlocks(struct cross_lock *xlock) 5015 { 5016 unsigned int cur = current->xhlock_idx; 5017 unsigned int prev_hist_id = xhlock(cur).hist_id; 5018 unsigned int i; 5019 5020 if (!graph_lock()) 5021 return; 5022 5023 if (xlock->nr_acquire) { 5024 for (i = 0; i < MAX_XHLOCKS_NR; i++) { 5025 struct hist_lock *xhlock = &xhlock(cur - i); 5026 5027 if (!xhlock_valid(xhlock)) 5028 break; 5029 5030 if (before(xhlock->hlock.gen_id, xlock->hlock.gen_id)) 5031 break; 5032 5033 if (!same_context_xhlock(xhlock)) 5034 break; 5035 5036 /* 5037 * Filter out the cases where the ring buffer was 5038 * overwritten and the current entry has a bigger 5039 * hist_id than the previous one, which is impossible 5040 * otherwise: 5041 */ 5042 if (unlikely(before(prev_hist_id, xhlock->hist_id))) 5043 break; 5044 5045 prev_hist_id = xhlock->hist_id; 5046 5047 /* 5048 * commit_xhlock() returns 0 with graph_lock already 5049 * released if fail. 5050 */ 5051 if (!commit_xhlock(xlock, xhlock)) 5052 return; 5053 } 5054 } 5055 5056 graph_unlock(); 5057 } 5058 5059 void lock_commit_crosslock(struct lockdep_map *lock) 5060 { 5061 struct cross_lock *xlock; 5062 unsigned long flags; 5063 5064 if (unlikely(!debug_locks || current->lockdep_recursion)) 5065 return; 5066 5067 if (!current->xhlocks) 5068 return; 5069 5070 /* 5071 * Do commit hist_locks with the cross_lock, only in case that 5072 * the cross_lock could depend on acquisitions after that. 5073 * 5074 * For example, if the cross_lock does not have the 'check' flag 5075 * then we don't need to check dependencies and commit for that. 5076 * Just skip it. In that case, of course, the cross_lock does 5077 * not depend on acquisitions ahead, either. 5078 * 5079 * WARNING: Don't do that in add_xlock() in advance. When an 5080 * acquisition context is different from the commit context, 5081 * invalid(skipped) cross_lock might be accessed. 5082 */ 5083 if (!depend_after(&((struct lockdep_map_cross *)lock)->xlock.hlock)) 5084 return; 5085 5086 raw_local_irq_save(flags); 5087 check_flags(flags); 5088 current->lockdep_recursion = 1; 5089 xlock = &((struct lockdep_map_cross *)lock)->xlock; 5090 commit_xhlocks(xlock); 5091 current->lockdep_recursion = 0; 5092 raw_local_irq_restore(flags); 5093 } 5094 EXPORT_SYMBOL_GPL(lock_commit_crosslock); 5095 5096 /* 5097 * Return: 0 - failure; 5098 * 1 - crosslock, done; 5099 * 2 - normal lock, continue to held_lock[] ops. 5100 */ 5101 static int lock_release_crosslock(struct lockdep_map *lock) 5102 { 5103 if (cross_lock(lock)) { 5104 if (!graph_lock()) 5105 return 0; 5106 ((struct lockdep_map_cross *)lock)->xlock.nr_acquire--; 5107 graph_unlock(); 5108 return 1; 5109 } 5110 return 2; 5111 } 5112 5113 static void cross_init(struct lockdep_map *lock, int cross) 5114 { 5115 if (cross) 5116 ((struct lockdep_map_cross *)lock)->xlock.nr_acquire = 0; 5117 5118 lock->cross = cross; 5119 5120 /* 5121 * Crossrelease assumes that the ring buffer size of xhlocks 5122 * is aligned with power of 2. So force it on build. 5123 */ 5124 BUILD_BUG_ON(MAX_XHLOCKS_NR & (MAX_XHLOCKS_NR - 1)); 5125 } 5126 5127 void lockdep_init_task(struct task_struct *task) 5128 { 5129 int i; 5130 5131 task->xhlock_idx = UINT_MAX; 5132 task->hist_id = 0; 5133 5134 for (i = 0; i < XHLOCK_CTX_NR; i++) { 5135 task->xhlock_idx_hist[i] = UINT_MAX; 5136 task->hist_id_save[i] = 0; 5137 } 5138 5139 task->xhlocks = kzalloc(sizeof(struct hist_lock) * MAX_XHLOCKS_NR, 5140 GFP_KERNEL); 5141 } 5142 5143 void lockdep_free_task(struct task_struct *task) 5144 { 5145 if (task->xhlocks) { 5146 void *tmp = task->xhlocks; 5147 /* Diable crossrelease for current */ 5148 task->xhlocks = NULL; 5149 kfree(tmp); 5150 } 5151 } 5152 #endif 5153