linux/kernel/lockdep.c
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   1/*
   2 * kernel/lockdep.c
   3 *
   4 * Runtime locking correctness validator
   5 *
   6 * Started by Ingo Molnar:
   7 *
   8 *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   9 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
  10 *
  11 * this code maps all the lock dependencies as they occur in a live kernel
  12 * and will warn about the following classes of locking bugs:
  13 *
  14 * - lock inversion scenarios
  15 * - circular lock dependencies
  16 * - hardirq/softirq safe/unsafe locking bugs
  17 *
  18 * Bugs are reported even if the current locking scenario does not cause
  19 * any deadlock at this point.
  20 *
  21 * I.e. if anytime in the past two locks were taken in a different order,
  22 * even if it happened for another task, even if those were different
  23 * locks (but of the same class as this lock), this code will detect it.
  24 *
  25 * Thanks to Arjan van de Ven for coming up with the initial idea of
  26 * mapping lock dependencies runtime.
  27 */
  28#define DISABLE_BRANCH_PROFILING
  29#include <linux/mutex.h>
  30#include <linux/sched.h>
  31#include <linux/delay.h>
  32#include <linux/module.h>
  33#include <linux/proc_fs.h>
  34#include <linux/seq_file.h>
  35#include <linux/spinlock.h>
  36#include <linux/kallsyms.h>
  37#include <linux/interrupt.h>
  38#include <linux/stacktrace.h>
  39#include <linux/debug_locks.h>
  40#include <linux/irqflags.h>
  41#include <linux/utsname.h>
  42#include <linux/hash.h>
  43#include <linux/ftrace.h>
  44#include <linux/stringify.h>
  45#include <linux/bitops.h>
  46#include <linux/gfp.h>
  47
  48#include <asm/sections.h>
  49
  50#include "lockdep_internals.h"
  51
  52#define CREATE_TRACE_POINTS
  53#include <trace/events/lock.h>
  54
  55#ifdef CONFIG_PROVE_LOCKING
  56int prove_locking = 1;
  57module_param(prove_locking, int, 0644);
  58#else
  59#define prove_locking 0
  60#endif
  61
  62#ifdef CONFIG_LOCK_STAT
  63int lock_stat = 1;
  64module_param(lock_stat, int, 0644);
  65#else
  66#define lock_stat 0
  67#endif
  68
  69/*
  70 * lockdep_lock: protects the lockdep graph, the hashes and the
  71 *               class/list/hash allocators.
  72 *
  73 * This is one of the rare exceptions where it's justified
  74 * to use a raw spinlock - we really dont want the spinlock
  75 * code to recurse back into the lockdep code...
  76 */
  77static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  78
  79static int graph_lock(void)
  80{
  81        arch_spin_lock(&lockdep_lock);
  82        /*
  83         * Make sure that if another CPU detected a bug while
  84         * walking the graph we dont change it (while the other
  85         * CPU is busy printing out stuff with the graph lock
  86         * dropped already)
  87         */
  88        if (!debug_locks) {
  89                arch_spin_unlock(&lockdep_lock);
  90                return 0;
  91        }
  92        /* prevent any recursions within lockdep from causing deadlocks */
  93        current->lockdep_recursion++;
  94        return 1;
  95}
  96
  97static inline int graph_unlock(void)
  98{
  99        if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
 100                return DEBUG_LOCKS_WARN_ON(1);
 101
 102        current->lockdep_recursion--;
 103        arch_spin_unlock(&lockdep_lock);
 104        return 0;
 105}
 106
 107/*
 108 * Turn lock debugging off and return with 0 if it was off already,
 109 * and also release the graph lock:
 110 */
 111static inline int debug_locks_off_graph_unlock(void)
 112{
 113        int ret = debug_locks_off();
 114
 115        arch_spin_unlock(&lockdep_lock);
 116
 117        return ret;
 118}
 119
 120static int lockdep_initialized;
 121
 122unsigned long nr_list_entries;
 123static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
 124
 125/*
 126 * All data structures here are protected by the global debug_lock.
 127 *
 128 * Mutex key structs only get allocated, once during bootup, and never
 129 * get freed - this significantly simplifies the debugging code.
 130 */
 131unsigned long nr_lock_classes;
 132static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
 133
 134static inline struct lock_class *hlock_class(struct held_lock *hlock)
 135{
 136        if (!hlock->class_idx) {
 137                DEBUG_LOCKS_WARN_ON(1);
 138                return NULL;
 139        }
 140        return lock_classes + hlock->class_idx - 1;
 141}
 142
 143#ifdef CONFIG_LOCK_STAT
 144static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
 145                      cpu_lock_stats);
 146
 147static inline u64 lockstat_clock(void)
 148{
 149        return local_clock();
 150}
 151
 152static int lock_point(unsigned long points[], unsigned long ip)
 153{
 154        int i;
 155
 156        for (i = 0; i < LOCKSTAT_POINTS; i++) {
 157                if (points[i] == 0) {
 158                        points[i] = ip;
 159                        break;
 160                }
 161                if (points[i] == ip)
 162                        break;
 163        }
 164
 165        return i;
 166}
 167
 168static void lock_time_inc(struct lock_time *lt, u64 time)
 169{
 170        if (time > lt->max)
 171                lt->max = time;
 172
 173        if (time < lt->min || !lt->nr)
 174                lt->min = time;
 175
 176        lt->total += time;
 177        lt->nr++;
 178}
 179
 180static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
 181{
 182        if (!src->nr)
 183                return;
 184
 185        if (src->max > dst->max)
 186                dst->max = src->max;
 187
 188        if (src->min < dst->min || !dst->nr)
 189                dst->min = src->min;
 190
 191        dst->total += src->total;
 192        dst->nr += src->nr;
 193}
 194
 195struct lock_class_stats lock_stats(struct lock_class *class)
 196{
 197        struct lock_class_stats stats;
 198        int cpu, i;
 199
 200        memset(&stats, 0, sizeof(struct lock_class_stats));
 201        for_each_possible_cpu(cpu) {
 202                struct lock_class_stats *pcs =
 203                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
 204
 205                for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
 206                        stats.contention_point[i] += pcs->contention_point[i];
 207
 208                for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
 209                        stats.contending_point[i] += pcs->contending_point[i];
 210
 211                lock_time_add(&pcs->read_waittime, &stats.read_waittime);
 212                lock_time_add(&pcs->write_waittime, &stats.write_waittime);
 213
 214                lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
 215                lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
 216
 217                for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
 218                        stats.bounces[i] += pcs->bounces[i];
 219        }
 220
 221        return stats;
 222}
 223
 224void clear_lock_stats(struct lock_class *class)
 225{
 226        int cpu;
 227
 228        for_each_possible_cpu(cpu) {
 229                struct lock_class_stats *cpu_stats =
 230                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
 231
 232                memset(cpu_stats, 0, sizeof(struct lock_class_stats));
 233        }
 234        memset(class->contention_point, 0, sizeof(class->contention_point));
 235        memset(class->contending_point, 0, sizeof(class->contending_point));
 236}
 237
 238static struct lock_class_stats *get_lock_stats(struct lock_class *class)
 239{
 240        return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
 241}
 242
 243static void put_lock_stats(struct lock_class_stats *stats)
 244{
 245        put_cpu_var(cpu_lock_stats);
 246}
 247
 248static void lock_release_holdtime(struct held_lock *hlock)
 249{
 250        struct lock_class_stats *stats;
 251        u64 holdtime;
 252
 253        if (!lock_stat)
 254                return;
 255
 256        holdtime = lockstat_clock() - hlock->holdtime_stamp;
 257
 258        stats = get_lock_stats(hlock_class(hlock));
 259        if (hlock->read)
 260                lock_time_inc(&stats->read_holdtime, holdtime);
 261        else
 262                lock_time_inc(&stats->write_holdtime, holdtime);
 263        put_lock_stats(stats);
 264}
 265#else
 266static inline void lock_release_holdtime(struct held_lock *hlock)
 267{
 268}
 269#endif
 270
 271/*
 272 * We keep a global list of all lock classes. The list only grows,
 273 * never shrinks. The list is only accessed with the lockdep
 274 * spinlock lock held.
 275 */
 276LIST_HEAD(all_lock_classes);
 277
 278/*
 279 * The lockdep classes are in a hash-table as well, for fast lookup:
 280 */
 281#define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
 282#define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
 283#define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
 284#define classhashentry(key)     (classhash_table + __classhashfn((key)))
 285
 286static struct list_head classhash_table[CLASSHASH_SIZE];
 287
 288/*
 289 * We put the lock dependency chains into a hash-table as well, to cache
 290 * their existence:
 291 */
 292#define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
 293#define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
 294#define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
 295#define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
 296
 297static struct list_head chainhash_table[CHAINHASH_SIZE];
 298
 299/*
 300 * The hash key of the lock dependency chains is a hash itself too:
 301 * it's a hash of all locks taken up to that lock, including that lock.
 302 * It's a 64-bit hash, because it's important for the keys to be
 303 * unique.
 304 */
 305#define iterate_chain_key(key1, key2) \
 306        (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
 307        ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
 308        (key2))
 309
 310void lockdep_off(void)
 311{
 312        current->lockdep_recursion++;
 313}
 314EXPORT_SYMBOL(lockdep_off);
 315
 316void lockdep_on(void)
 317{
 318        current->lockdep_recursion--;
 319}
 320EXPORT_SYMBOL(lockdep_on);
 321
 322/*
 323 * Debugging switches:
 324 */
 325
 326#define VERBOSE                 0
 327#define VERY_VERBOSE            0
 328
 329#if VERBOSE
 330# define HARDIRQ_VERBOSE        1
 331# define SOFTIRQ_VERBOSE        1
 332# define RECLAIM_VERBOSE        1
 333#else
 334# define HARDIRQ_VERBOSE        0
 335# define SOFTIRQ_VERBOSE        0
 336# define RECLAIM_VERBOSE        0
 337#endif
 338
 339#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
 340/*
 341 * Quick filtering for interesting events:
 342 */
 343static int class_filter(struct lock_class *class)
 344{
 345#if 0
 346        /* Example */
 347        if (class->name_version == 1 &&
 348                        !strcmp(class->name, "lockname"))
 349                return 1;
 350        if (class->name_version == 1 &&
 351                        !strcmp(class->name, "&struct->lockfield"))
 352                return 1;
 353#endif
 354        /* Filter everything else. 1 would be to allow everything else */
 355        return 0;
 356}
 357#endif
 358
 359static int verbose(struct lock_class *class)
 360{
 361#if VERBOSE
 362        return class_filter(class);
 363#endif
 364        return 0;
 365}
 366
 367/*
 368 * Stack-trace: tightly packed array of stack backtrace
 369 * addresses. Protected by the graph_lock.
 370 */
 371unsigned long nr_stack_trace_entries;
 372static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
 373
 374static int save_trace(struct stack_trace *trace)
 375{
 376        trace->nr_entries = 0;
 377        trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
 378        trace->entries = stack_trace + nr_stack_trace_entries;
 379
 380        trace->skip = 3;
 381
 382        save_stack_trace(trace);
 383
 384        /*
 385         * Some daft arches put -1 at the end to indicate its a full trace.
 386         *
 387         * <rant> this is buggy anyway, since it takes a whole extra entry so a
 388         * complete trace that maxes out the entries provided will be reported
 389         * as incomplete, friggin useless </rant>
 390         */
 391        if (trace->nr_entries != 0 &&
 392            trace->entries[trace->nr_entries-1] == ULONG_MAX)
 393                trace->nr_entries--;
 394
 395        trace->max_entries = trace->nr_entries;
 396
 397        nr_stack_trace_entries += trace->nr_entries;
 398
 399        if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
 400                if (!debug_locks_off_graph_unlock())
 401                        return 0;
 402
 403                printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
 404                printk("turning off the locking correctness validator.\n");
 405                dump_stack();
 406
 407                return 0;
 408        }
 409
 410        return 1;
 411}
 412
 413unsigned int nr_hardirq_chains;
 414unsigned int nr_softirq_chains;
 415unsigned int nr_process_chains;
 416unsigned int max_lockdep_depth;
 417
 418#ifdef CONFIG_DEBUG_LOCKDEP
 419/*
 420 * We cannot printk in early bootup code. Not even early_printk()
 421 * might work. So we mark any initialization errors and printk
 422 * about it later on, in lockdep_info().
 423 */
 424static int lockdep_init_error;
 425static unsigned long lockdep_init_trace_data[20];
 426static struct stack_trace lockdep_init_trace = {
 427        .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
 428        .entries = lockdep_init_trace_data,
 429};
 430
 431/*
 432 * Various lockdep statistics:
 433 */
 434DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
 435#endif
 436
 437/*
 438 * Locking printouts:
 439 */
 440
 441#define __USAGE(__STATE)                                                \
 442        [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
 443        [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
 444        [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
 445        [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
 446
 447static const char *usage_str[] =
 448{
 449#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
 450#include "lockdep_states.h"
 451#undef LOCKDEP_STATE
 452        [LOCK_USED] = "INITIAL USE",
 453};
 454
 455const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
 456{
 457        return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
 458}
 459
 460static inline unsigned long lock_flag(enum lock_usage_bit bit)
 461{
 462        return 1UL << bit;
 463}
 464
 465static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
 466{
 467        char c = '.';
 468
 469        if (class->usage_mask & lock_flag(bit + 2))
 470                c = '+';
 471        if (class->usage_mask & lock_flag(bit)) {
 472                c = '-';
 473                if (class->usage_mask & lock_flag(bit + 2))
 474                        c = '?';
 475        }
 476
 477        return c;
 478}
 479
 480void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
 481{
 482        int i = 0;
 483
 484#define LOCKDEP_STATE(__STATE)                                          \
 485        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
 486        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
 487#include "lockdep_states.h"
 488#undef LOCKDEP_STATE
 489
 490        usage[i] = '\0';
 491}
 492
 493static void print_lock_name(struct lock_class *class)
 494{
 495        char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
 496        const char *name;
 497
 498        get_usage_chars(class, usage);
 499
 500        name = class->name;
 501        if (!name) {
 502                name = __get_key_name(class->key, str);
 503                printk(" (%s", name);
 504        } else {
 505                printk(" (%s", name);
 506                if (class->name_version > 1)
 507                        printk("#%d", class->name_version);
 508                if (class->subclass)
 509                        printk("/%d", class->subclass);
 510        }
 511        printk("){%s}", usage);
 512}
 513
 514static void print_lockdep_cache(struct lockdep_map *lock)
 515{
 516        const char *name;
 517        char str[KSYM_NAME_LEN];
 518
 519        name = lock->name;
 520        if (!name)
 521                name = __get_key_name(lock->key->subkeys, str);
 522
 523        printk("%s", name);
 524}
 525
 526static void print_lock(struct held_lock *hlock)
 527{
 528        print_lock_name(hlock_class(hlock));
 529        printk(", at: ");
 530        print_ip_sym(hlock->acquire_ip);
 531}
 532
 533static void lockdep_print_held_locks(struct task_struct *curr)
 534{
 535        int i, depth = curr->lockdep_depth;
 536
 537        if (!depth) {
 538                printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
 539                return;
 540        }
 541        printk("%d lock%s held by %s/%d:\n",
 542                depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
 543
 544        for (i = 0; i < depth; i++) {
 545                printk(" #%d: ", i);
 546                print_lock(curr->held_locks + i);
 547        }
 548}
 549
 550static void print_kernel_version(void)
 551{
 552        printk("%s %.*s\n", init_utsname()->release,
 553                (int)strcspn(init_utsname()->version, " "),
 554                init_utsname()->version);
 555}
 556
 557static int very_verbose(struct lock_class *class)
 558{
 559#if VERY_VERBOSE
 560        return class_filter(class);
 561#endif
 562        return 0;
 563}
 564
 565/*
 566 * Is this the address of a static object:
 567 */
 568static int static_obj(void *obj)
 569{
 570        unsigned long start = (unsigned long) &_stext,
 571                      end   = (unsigned long) &_end,
 572                      addr  = (unsigned long) obj;
 573
 574        /*
 575         * static variable?
 576         */
 577        if ((addr >= start) && (addr < end))
 578                return 1;
 579
 580        if (arch_is_kernel_data(addr))
 581                return 1;
 582
 583        /*
 584         * in-kernel percpu var?
 585         */
 586        if (is_kernel_percpu_address(addr))
 587                return 1;
 588
 589        /*
 590         * module static or percpu var?
 591         */
 592        return is_module_address(addr) || is_module_percpu_address(addr);
 593}
 594
 595/*
 596 * To make lock name printouts unique, we calculate a unique
 597 * class->name_version generation counter:
 598 */
 599static int count_matching_names(struct lock_class *new_class)
 600{
 601        struct lock_class *class;
 602        int count = 0;
 603
 604        if (!new_class->name)
 605                return 0;
 606
 607        list_for_each_entry(class, &all_lock_classes, lock_entry) {
 608                if (new_class->key - new_class->subclass == class->key)
 609                        return class->name_version;
 610                if (class->name && !strcmp(class->name, new_class->name))
 611                        count = max(count, class->name_version);
 612        }
 613
 614        return count + 1;
 615}
 616
 617/*
 618 * Register a lock's class in the hash-table, if the class is not present
 619 * yet. Otherwise we look it up. We cache the result in the lock object
 620 * itself, so actual lookup of the hash should be once per lock object.
 621 */
 622static inline struct lock_class *
 623look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
 624{
 625        struct lockdep_subclass_key *key;
 626        struct list_head *hash_head;
 627        struct lock_class *class;
 628
 629#ifdef CONFIG_DEBUG_LOCKDEP
 630        /*
 631         * If the architecture calls into lockdep before initializing
 632         * the hashes then we'll warn about it later. (we cannot printk
 633         * right now)
 634         */
 635        if (unlikely(!lockdep_initialized)) {
 636                lockdep_init();
 637                lockdep_init_error = 1;
 638                save_stack_trace(&lockdep_init_trace);
 639        }
 640#endif
 641
 642        if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
 643                debug_locks_off();
 644                printk(KERN_ERR
 645                        "BUG: looking up invalid subclass: %u\n", subclass);
 646                printk(KERN_ERR
 647                        "turning off the locking correctness validator.\n");
 648                dump_stack();
 649                return NULL;
 650        }
 651
 652        /*
 653         * Static locks do not have their class-keys yet - for them the key
 654         * is the lock object itself:
 655         */
 656        if (unlikely(!lock->key))
 657                lock->key = (void *)lock;
 658
 659        /*
 660         * NOTE: the class-key must be unique. For dynamic locks, a static
 661         * lock_class_key variable is passed in through the mutex_init()
 662         * (or spin_lock_init()) call - which acts as the key. For static
 663         * locks we use the lock object itself as the key.
 664         */
 665        BUILD_BUG_ON(sizeof(struct lock_class_key) >
 666                        sizeof(struct lockdep_map));
 667
 668        key = lock->key->subkeys + subclass;
 669
 670        hash_head = classhashentry(key);
 671
 672        /*
 673         * We can walk the hash lockfree, because the hash only
 674         * grows, and we are careful when adding entries to the end:
 675         */
 676        list_for_each_entry(class, hash_head, hash_entry) {
 677                if (class->key == key) {
 678                        WARN_ON_ONCE(class->name != lock->name);
 679                        return class;
 680                }
 681        }
 682
 683        return NULL;
 684}
 685
 686/*
 687 * Register a lock's class in the hash-table, if the class is not present
 688 * yet. Otherwise we look it up. We cache the result in the lock object
 689 * itself, so actual lookup of the hash should be once per lock object.
 690 */
 691static inline struct lock_class *
 692register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 693{
 694        struct lockdep_subclass_key *key;
 695        struct list_head *hash_head;
 696        struct lock_class *class;
 697        unsigned long flags;
 698
 699        class = look_up_lock_class(lock, subclass);
 700        if (likely(class))
 701                return class;
 702
 703        /*
 704         * Debug-check: all keys must be persistent!
 705         */
 706        if (!static_obj(lock->key)) {
 707                debug_locks_off();
 708                printk("INFO: trying to register non-static key.\n");
 709                printk("the code is fine but needs lockdep annotation.\n");
 710                printk("turning off the locking correctness validator.\n");
 711                dump_stack();
 712
 713                return NULL;
 714        }
 715
 716        key = lock->key->subkeys + subclass;
 717        hash_head = classhashentry(key);
 718
 719        raw_local_irq_save(flags);
 720        if (!graph_lock()) {
 721                raw_local_irq_restore(flags);
 722                return NULL;
 723        }
 724        /*
 725         * We have to do the hash-walk again, to avoid races
 726         * with another CPU:
 727         */
 728        list_for_each_entry(class, hash_head, hash_entry)
 729                if (class->key == key)
 730                        goto out_unlock_set;
 731        /*
 732         * Allocate a new key from the static array, and add it to
 733         * the hash:
 734         */
 735        if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
 736                if (!debug_locks_off_graph_unlock()) {
 737                        raw_local_irq_restore(flags);
 738                        return NULL;
 739                }
 740                raw_local_irq_restore(flags);
 741
 742                printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
 743                printk("turning off the locking correctness validator.\n");
 744                dump_stack();
 745                return NULL;
 746        }
 747        class = lock_classes + nr_lock_classes++;
 748        debug_atomic_inc(nr_unused_locks);
 749        class->key = key;
 750        class->name = lock->name;
 751        class->subclass = subclass;
 752        INIT_LIST_HEAD(&class->lock_entry);
 753        INIT_LIST_HEAD(&class->locks_before);
 754        INIT_LIST_HEAD(&class->locks_after);
 755        class->name_version = count_matching_names(class);
 756        /*
 757         * We use RCU's safe list-add method to make
 758         * parallel walking of the hash-list safe:
 759         */
 760        list_add_tail_rcu(&class->hash_entry, hash_head);
 761        /*
 762         * Add it to the global list of classes:
 763         */
 764        list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
 765
 766        if (verbose(class)) {
 767                graph_unlock();
 768                raw_local_irq_restore(flags);
 769
 770                printk("\nnew class %p: %s", class->key, class->name);
 771                if (class->name_version > 1)
 772                        printk("#%d", class->name_version);
 773                printk("\n");
 774                dump_stack();
 775
 776                raw_local_irq_save(flags);
 777                if (!graph_lock()) {
 778                        raw_local_irq_restore(flags);
 779                        return NULL;
 780                }
 781        }
 782out_unlock_set:
 783        graph_unlock();
 784        raw_local_irq_restore(flags);
 785
 786        if (!subclass || force)
 787                lock->class_cache[0] = class;
 788        else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
 789                lock->class_cache[subclass] = class;
 790
 791        if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
 792                return NULL;
 793
 794        return class;
 795}
 796
 797#ifdef CONFIG_PROVE_LOCKING
 798/*
 799 * Allocate a lockdep entry. (assumes the graph_lock held, returns
 800 * with NULL on failure)
 801 */
 802static struct lock_list *alloc_list_entry(void)
 803{
 804        if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
 805                if (!debug_locks_off_graph_unlock())
 806                        return NULL;
 807
 808                printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
 809                printk("turning off the locking correctness validator.\n");
 810                dump_stack();
 811                return NULL;
 812        }
 813        return list_entries + nr_list_entries++;
 814}
 815
 816/*
 817 * Add a new dependency to the head of the list:
 818 */
 819static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
 820                            struct list_head *head, unsigned long ip,
 821                            int distance, struct stack_trace *trace)
 822{
 823        struct lock_list *entry;
 824        /*
 825         * Lock not present yet - get a new dependency struct and
 826         * add it to the list:
 827         */
 828        entry = alloc_list_entry();
 829        if (!entry)
 830                return 0;
 831
 832        entry->class = this;
 833        entry->distance = distance;
 834        entry->trace = *trace;
 835        /*
 836         * Since we never remove from the dependency list, the list can
 837         * be walked lockless by other CPUs, it's only allocation
 838         * that must be protected by the spinlock. But this also means
 839         * we must make new entries visible only once writes to the
 840         * entry become visible - hence the RCU op:
 841         */
 842        list_add_tail_rcu(&entry->entry, head);
 843
 844        return 1;
 845}
 846
 847/*
 848 * For good efficiency of modular, we use power of 2
 849 */
 850#define MAX_CIRCULAR_QUEUE_SIZE         4096UL
 851#define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
 852
 853/*
 854 * The circular_queue and helpers is used to implement the
 855 * breadth-first search(BFS)algorithem, by which we can build
 856 * the shortest path from the next lock to be acquired to the
 857 * previous held lock if there is a circular between them.
 858 */
 859struct circular_queue {
 860        unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
 861        unsigned int  front, rear;
 862};
 863
 864static struct circular_queue lock_cq;
 865
 866unsigned int max_bfs_queue_depth;
 867
 868static unsigned int lockdep_dependency_gen_id;
 869
 870static inline void __cq_init(struct circular_queue *cq)
 871{
 872        cq->front = cq->rear = 0;
 873        lockdep_dependency_gen_id++;
 874}
 875
 876static inline int __cq_empty(struct circular_queue *cq)
 877{
 878        return (cq->front == cq->rear);
 879}
 880
 881static inline int __cq_full(struct circular_queue *cq)
 882{
 883        return ((cq->rear + 1) & CQ_MASK) == cq->front;
 884}
 885
 886static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
 887{
 888        if (__cq_full(cq))
 889                return -1;
 890
 891        cq->element[cq->rear] = elem;
 892        cq->rear = (cq->rear + 1) & CQ_MASK;
 893        return 0;
 894}
 895
 896static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
 897{
 898        if (__cq_empty(cq))
 899                return -1;
 900
 901        *elem = cq->element[cq->front];
 902        cq->front = (cq->front + 1) & CQ_MASK;
 903        return 0;
 904}
 905
 906static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
 907{
 908        return (cq->rear - cq->front) & CQ_MASK;
 909}
 910
 911static inline void mark_lock_accessed(struct lock_list *lock,
 912                                        struct lock_list *parent)
 913{
 914        unsigned long nr;
 915
 916        nr = lock - list_entries;
 917        WARN_ON(nr >= nr_list_entries);
 918        lock->parent = parent;
 919        lock->class->dep_gen_id = lockdep_dependency_gen_id;
 920}
 921
 922static inline unsigned long lock_accessed(struct lock_list *lock)
 923{
 924        unsigned long nr;
 925
 926        nr = lock - list_entries;
 927        WARN_ON(nr >= nr_list_entries);
 928        return lock->class->dep_gen_id == lockdep_dependency_gen_id;
 929}
 930
 931static inline struct lock_list *get_lock_parent(struct lock_list *child)
 932{
 933        return child->parent;
 934}
 935
 936static inline int get_lock_depth(struct lock_list *child)
 937{
 938        int depth = 0;
 939        struct lock_list *parent;
 940
 941        while ((parent = get_lock_parent(child))) {
 942                child = parent;
 943                depth++;
 944        }
 945        return depth;
 946}
 947
 948static int __bfs(struct lock_list *source_entry,
 949                 void *data,
 950                 int (*match)(struct lock_list *entry, void *data),
 951                 struct lock_list **target_entry,
 952                 int forward)
 953{
 954        struct lock_list *entry;
 955        struct list_head *head;
 956        struct circular_queue *cq = &lock_cq;
 957        int ret = 1;
 958
 959        if (match(source_entry, data)) {
 960                *target_entry = source_entry;
 961                ret = 0;
 962                goto exit;
 963        }
 964
 965        if (forward)
 966                head = &source_entry->class->locks_after;
 967        else
 968                head = &source_entry->class->locks_before;
 969
 970        if (list_empty(head))
 971                goto exit;
 972
 973        __cq_init(cq);
 974        __cq_enqueue(cq, (unsigned long)source_entry);
 975
 976        while (!__cq_empty(cq)) {
 977                struct lock_list *lock;
 978
 979                __cq_dequeue(cq, (unsigned long *)&lock);
 980
 981                if (!lock->class) {
 982                        ret = -2;
 983                        goto exit;
 984                }
 985
 986                if (forward)
 987                        head = &lock->class->locks_after;
 988                else
 989                        head = &lock->class->locks_before;
 990
 991                list_for_each_entry(entry, head, entry) {
 992                        if (!lock_accessed(entry)) {
 993                                unsigned int cq_depth;
 994                                mark_lock_accessed(entry, lock);
 995                                if (match(entry, data)) {
 996                                        *target_entry = entry;
 997                                        ret = 0;
 998                                        goto exit;
 999                                }
1000
1001                                if (__cq_enqueue(cq, (unsigned long)entry)) {
1002                                        ret = -1;
1003                                        goto exit;
1004                                }
1005                                cq_depth = __cq_get_elem_count(cq);
1006                                if (max_bfs_queue_depth < cq_depth)
1007                                        max_bfs_queue_depth = cq_depth;
1008                        }
1009                }
1010        }
1011exit:
1012        return ret;
1013}
1014
1015static inline int __bfs_forwards(struct lock_list *src_entry,
1016                        void *data,
1017                        int (*match)(struct lock_list *entry, void *data),
1018                        struct lock_list **target_entry)
1019{
1020        return __bfs(src_entry, data, match, target_entry, 1);
1021
1022}
1023
1024static inline int __bfs_backwards(struct lock_list *src_entry,
1025                        void *data,
1026                        int (*match)(struct lock_list *entry, void *data),
1027                        struct lock_list **target_entry)
1028{
1029        return __bfs(src_entry, data, match, target_entry, 0);
1030
1031}
1032
1033/*
1034 * Recursive, forwards-direction lock-dependency checking, used for
1035 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1036 * checking.
1037 */
1038
1039/*
1040 * Print a dependency chain entry (this is only done when a deadlock
1041 * has been detected):
1042 */
1043static noinline int
1044print_circular_bug_entry(struct lock_list *target, int depth)
1045{
1046        if (debug_locks_silent)
1047                return 0;
1048        printk("\n-> #%u", depth);
1049        print_lock_name(target->class);
1050        printk(":\n");
1051        print_stack_trace(&target->trace, 6);
1052
1053        return 0;
1054}
1055
1056/*
1057 * When a circular dependency is detected, print the
1058 * header first:
1059 */
1060static noinline int
1061print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1062                        struct held_lock *check_src,
1063                        struct held_lock *check_tgt)
1064{
1065        struct task_struct *curr = current;
1066
1067        if (debug_locks_silent)
1068                return 0;
1069
1070        printk("\n=======================================================\n");
1071        printk(  "[ INFO: possible circular locking dependency detected ]\n");
1072        print_kernel_version();
1073        printk(  "-------------------------------------------------------\n");
1074        printk("%s/%d is trying to acquire lock:\n",
1075                curr->comm, task_pid_nr(curr));
1076        print_lock(check_src);
1077        printk("\nbut task is already holding lock:\n");
1078        print_lock(check_tgt);
1079        printk("\nwhich lock already depends on the new lock.\n\n");
1080        printk("\nthe existing dependency chain (in reverse order) is:\n");
1081
1082        print_circular_bug_entry(entry, depth);
1083
1084        return 0;
1085}
1086
1087static inline int class_equal(struct lock_list *entry, void *data)
1088{
1089        return entry->class == data;
1090}
1091
1092static noinline int print_circular_bug(struct lock_list *this,
1093                                struct lock_list *target,
1094                                struct held_lock *check_src,
1095                                struct held_lock *check_tgt)
1096{
1097        struct task_struct *curr = current;
1098        struct lock_list *parent;
1099        int depth;
1100
1101        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1102                return 0;
1103
1104        if (!save_trace(&this->trace))
1105                return 0;
1106
1107        depth = get_lock_depth(target);
1108
1109        print_circular_bug_header(target, depth, check_src, check_tgt);
1110
1111        parent = get_lock_parent(target);
1112
1113        while (parent) {
1114                print_circular_bug_entry(parent, --depth);
1115                parent = get_lock_parent(parent);
1116        }
1117
1118        printk("\nother info that might help us debug this:\n\n");
1119        lockdep_print_held_locks(curr);
1120
1121        printk("\nstack backtrace:\n");
1122        dump_stack();
1123
1124        return 0;
1125}
1126
1127static noinline int print_bfs_bug(int ret)
1128{
1129        if (!debug_locks_off_graph_unlock())
1130                return 0;
1131
1132        WARN(1, "lockdep bfs error:%d\n", ret);
1133
1134        return 0;
1135}
1136
1137static int noop_count(struct lock_list *entry, void *data)
1138{
1139        (*(unsigned long *)data)++;
1140        return 0;
1141}
1142
1143unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1144{
1145        unsigned long  count = 0;
1146        struct lock_list *uninitialized_var(target_entry);
1147
1148        __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1149
1150        return count;
1151}
1152unsigned long lockdep_count_forward_deps(struct lock_class *class)
1153{
1154        unsigned long ret, flags;
1155        struct lock_list this;
1156
1157        this.parent = NULL;
1158        this.class = class;
1159
1160        local_irq_save(flags);
1161        arch_spin_lock(&lockdep_lock);
1162        ret = __lockdep_count_forward_deps(&this);
1163        arch_spin_unlock(&lockdep_lock);
1164        local_irq_restore(flags);
1165
1166        return ret;
1167}
1168
1169unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1170{
1171        unsigned long  count = 0;
1172        struct lock_list *uninitialized_var(target_entry);
1173
1174        __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1175
1176        return count;
1177}
1178
1179unsigned long lockdep_count_backward_deps(struct lock_class *class)
1180{
1181        unsigned long ret, flags;
1182        struct lock_list this;
1183
1184        this.parent = NULL;
1185        this.class = class;
1186
1187        local_irq_save(flags);
1188        arch_spin_lock(&lockdep_lock);
1189        ret = __lockdep_count_backward_deps(&this);
1190        arch_spin_unlock(&lockdep_lock);
1191        local_irq_restore(flags);
1192
1193        return ret;
1194}
1195
1196/*
1197 * Prove that the dependency graph starting at <entry> can not
1198 * lead to <target>. Print an error and return 0 if it does.
1199 */
1200static noinline int
1201check_noncircular(struct lock_list *root, struct lock_class *target,
1202                struct lock_list **target_entry)
1203{
1204        int result;
1205
1206        debug_atomic_inc(nr_cyclic_checks);
1207
1208        result = __bfs_forwards(root, target, class_equal, target_entry);
1209
1210        return result;
1211}
1212
1213#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1214/*
1215 * Forwards and backwards subgraph searching, for the purposes of
1216 * proving that two subgraphs can be connected by a new dependency
1217 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1218 */
1219
1220static inline int usage_match(struct lock_list *entry, void *bit)
1221{
1222        return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1223}
1224
1225
1226
1227/*
1228 * Find a node in the forwards-direction dependency sub-graph starting
1229 * at @root->class that matches @bit.
1230 *
1231 * Return 0 if such a node exists in the subgraph, and put that node
1232 * into *@target_entry.
1233 *
1234 * Return 1 otherwise and keep *@target_entry unchanged.
1235 * Return <0 on error.
1236 */
1237static int
1238find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1239                        struct lock_list **target_entry)
1240{
1241        int result;
1242
1243        debug_atomic_inc(nr_find_usage_forwards_checks);
1244
1245        result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1246
1247        return result;
1248}
1249
1250/*
1251 * Find a node in the backwards-direction dependency sub-graph starting
1252 * at @root->class that matches @bit.
1253 *
1254 * Return 0 if such a node exists in the subgraph, and put that node
1255 * into *@target_entry.
1256 *
1257 * Return 1 otherwise and keep *@target_entry unchanged.
1258 * Return <0 on error.
1259 */
1260static int
1261find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1262                        struct lock_list **target_entry)
1263{
1264        int result;
1265
1266        debug_atomic_inc(nr_find_usage_backwards_checks);
1267
1268        result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1269
1270        return result;
1271}
1272
1273static void print_lock_class_header(struct lock_class *class, int depth)
1274{
1275        int bit;
1276
1277        printk("%*s->", depth, "");
1278        print_lock_name(class);
1279        printk(" ops: %lu", class->ops);
1280        printk(" {\n");
1281
1282        for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1283                if (class->usage_mask & (1 << bit)) {
1284                        int len = depth;
1285
1286                        len += printk("%*s   %s", depth, "", usage_str[bit]);
1287                        len += printk(" at:\n");
1288                        print_stack_trace(class->usage_traces + bit, len);
1289                }
1290        }
1291        printk("%*s }\n", depth, "");
1292
1293        printk("%*s ... key      at: ",depth,"");
1294        print_ip_sym((unsigned long)class->key);
1295}
1296
1297/*
1298 * printk the shortest lock dependencies from @start to @end in reverse order:
1299 */
1300static void __used
1301print_shortest_lock_dependencies(struct lock_list *leaf,
1302                                struct lock_list *root)
1303{
1304        struct lock_list *entry = leaf;
1305        int depth;
1306
1307        /*compute depth from generated tree by BFS*/
1308        depth = get_lock_depth(leaf);
1309
1310        do {
1311                print_lock_class_header(entry->class, depth);
1312                printk("%*s ... acquired at:\n", depth, "");
1313                print_stack_trace(&entry->trace, 2);
1314                printk("\n");
1315
1316                if (depth == 0 && (entry != root)) {
1317                        printk("lockdep:%s bad BFS generated tree\n", __func__);
1318                        break;
1319                }
1320
1321                entry = get_lock_parent(entry);
1322                depth--;
1323        } while (entry && (depth >= 0));
1324
1325        return;
1326}
1327
1328static int
1329print_bad_irq_dependency(struct task_struct *curr,
1330                         struct lock_list *prev_root,
1331                         struct lock_list *next_root,
1332                         struct lock_list *backwards_entry,
1333                         struct lock_list *forwards_entry,
1334                         struct held_lock *prev,
1335                         struct held_lock *next,
1336                         enum lock_usage_bit bit1,
1337                         enum lock_usage_bit bit2,
1338                         const char *irqclass)
1339{
1340        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1341                return 0;
1342
1343        printk("\n======================================================\n");
1344        printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1345                irqclass, irqclass);
1346        print_kernel_version();
1347        printk(  "------------------------------------------------------\n");
1348        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1349                curr->comm, task_pid_nr(curr),
1350                curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1351                curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1352                curr->hardirqs_enabled,
1353                curr->softirqs_enabled);
1354        print_lock(next);
1355
1356        printk("\nand this task is already holding:\n");
1357        print_lock(prev);
1358        printk("which would create a new lock dependency:\n");
1359        print_lock_name(hlock_class(prev));
1360        printk(" ->");
1361        print_lock_name(hlock_class(next));
1362        printk("\n");
1363
1364        printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1365                irqclass);
1366        print_lock_name(backwards_entry->class);
1367        printk("\n... which became %s-irq-safe at:\n", irqclass);
1368
1369        print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1370
1371        printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1372        print_lock_name(forwards_entry->class);
1373        printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1374        printk("...");
1375
1376        print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1377
1378        printk("\nother info that might help us debug this:\n\n");
1379        lockdep_print_held_locks(curr);
1380
1381        printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1382        printk(" and the holding lock:\n");
1383        if (!save_trace(&prev_root->trace))
1384                return 0;
1385        print_shortest_lock_dependencies(backwards_entry, prev_root);
1386
1387        printk("\nthe dependencies between the lock to be acquired");
1388        printk(" and %s-irq-unsafe lock:\n", irqclass);
1389        if (!save_trace(&next_root->trace))
1390                return 0;
1391        print_shortest_lock_dependencies(forwards_entry, next_root);
1392
1393        printk("\nstack backtrace:\n");
1394        dump_stack();
1395
1396        return 0;
1397}
1398
1399static int
1400check_usage(struct task_struct *curr, struct held_lock *prev,
1401            struct held_lock *next, enum lock_usage_bit bit_backwards,
1402            enum lock_usage_bit bit_forwards, const char *irqclass)
1403{
1404        int ret;
1405        struct lock_list this, that;
1406        struct lock_list *uninitialized_var(target_entry);
1407        struct lock_list *uninitialized_var(target_entry1);
1408
1409        this.parent = NULL;
1410
1411        this.class = hlock_class(prev);
1412        ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1413        if (ret < 0)
1414                return print_bfs_bug(ret);
1415        if (ret == 1)
1416                return ret;
1417
1418        that.parent = NULL;
1419        that.class = hlock_class(next);
1420        ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1421        if (ret < 0)
1422                return print_bfs_bug(ret);
1423        if (ret == 1)
1424                return ret;
1425
1426        return print_bad_irq_dependency(curr, &this, &that,
1427                        target_entry, target_entry1,
1428                        prev, next,
1429                        bit_backwards, bit_forwards, irqclass);
1430}
1431
1432static const char *state_names[] = {
1433#define LOCKDEP_STATE(__STATE) \
1434        __stringify(__STATE),
1435#include "lockdep_states.h"
1436#undef LOCKDEP_STATE
1437};
1438
1439static const char *state_rnames[] = {
1440#define LOCKDEP_STATE(__STATE) \
1441        __stringify(__STATE)"-READ",
1442#include "lockdep_states.h"
1443#undef LOCKDEP_STATE
1444};
1445
1446static inline const char *state_name(enum lock_usage_bit bit)
1447{
1448        return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1449}
1450
1451static int exclusive_bit(int new_bit)
1452{
1453        /*
1454         * USED_IN
1455         * USED_IN_READ
1456         * ENABLED
1457         * ENABLED_READ
1458         *
1459         * bit 0 - write/read
1460         * bit 1 - used_in/enabled
1461         * bit 2+  state
1462         */
1463
1464        int state = new_bit & ~3;
1465        int dir = new_bit & 2;
1466
1467        /*
1468         * keep state, bit flip the direction and strip read.
1469         */
1470        return state | (dir ^ 2);
1471}
1472
1473static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1474                           struct held_lock *next, enum lock_usage_bit bit)
1475{
1476        /*
1477         * Prove that the new dependency does not connect a hardirq-safe
1478         * lock with a hardirq-unsafe lock - to achieve this we search
1479         * the backwards-subgraph starting at <prev>, and the
1480         * forwards-subgraph starting at <next>:
1481         */
1482        if (!check_usage(curr, prev, next, bit,
1483                           exclusive_bit(bit), state_name(bit)))
1484                return 0;
1485
1486        bit++; /* _READ */
1487
1488        /*
1489         * Prove that the new dependency does not connect a hardirq-safe-read
1490         * lock with a hardirq-unsafe lock - to achieve this we search
1491         * the backwards-subgraph starting at <prev>, and the
1492         * forwards-subgraph starting at <next>:
1493         */
1494        if (!check_usage(curr, prev, next, bit,
1495                           exclusive_bit(bit), state_name(bit)))
1496                return 0;
1497
1498        return 1;
1499}
1500
1501static int
1502check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1503                struct held_lock *next)
1504{
1505#define LOCKDEP_STATE(__STATE)                                          \
1506        if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1507                return 0;
1508#include "lockdep_states.h"
1509#undef LOCKDEP_STATE
1510
1511        return 1;
1512}
1513
1514static void inc_chains(void)
1515{
1516        if (current->hardirq_context)
1517                nr_hardirq_chains++;
1518        else {
1519                if (current->softirq_context)
1520                        nr_softirq_chains++;
1521                else
1522                        nr_process_chains++;
1523        }
1524}
1525
1526#else
1527
1528static inline int
1529check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1530                struct held_lock *next)
1531{
1532        return 1;
1533}
1534
1535static inline void inc_chains(void)
1536{
1537        nr_process_chains++;
1538}
1539
1540#endif
1541
1542static int
1543print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1544                   struct held_lock *next)
1545{
1546        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1547                return 0;
1548
1549        printk("\n=============================================\n");
1550        printk(  "[ INFO: possible recursive locking detected ]\n");
1551        print_kernel_version();
1552        printk(  "---------------------------------------------\n");
1553        printk("%s/%d is trying to acquire lock:\n",
1554                curr->comm, task_pid_nr(curr));
1555        print_lock(next);
1556        printk("\nbut task is already holding lock:\n");
1557        print_lock(prev);
1558
1559        printk("\nother info that might help us debug this:\n");
1560        lockdep_print_held_locks(curr);
1561
1562        printk("\nstack backtrace:\n");
1563        dump_stack();
1564
1565        return 0;
1566}
1567
1568/*
1569 * Check whether we are holding such a class already.
1570 *
1571 * (Note that this has to be done separately, because the graph cannot
1572 * detect such classes of deadlocks.)
1573 *
1574 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1575 */
1576static int
1577check_deadlock(struct task_struct *curr, struct held_lock *next,
1578               struct lockdep_map *next_instance, int read)
1579{
1580        struct held_lock *prev;
1581        struct held_lock *nest = NULL;
1582        int i;
1583
1584        for (i = 0; i < curr->lockdep_depth; i++) {
1585                prev = curr->held_locks + i;
1586
1587                if (prev->instance == next->nest_lock)
1588                        nest = prev;
1589
1590                if (hlock_class(prev) != hlock_class(next))
1591                        continue;
1592
1593                /*
1594                 * Allow read-after-read recursion of the same
1595                 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1596                 */
1597                if ((read == 2) && prev->read)
1598                        return 2;
1599
1600                /*
1601                 * We're holding the nest_lock, which serializes this lock's
1602                 * nesting behaviour.
1603                 */
1604                if (nest)
1605                        return 2;
1606
1607                return print_deadlock_bug(curr, prev, next);
1608        }
1609        return 1;
1610}
1611
1612/*
1613 * There was a chain-cache miss, and we are about to add a new dependency
1614 * to a previous lock. We recursively validate the following rules:
1615 *
1616 *  - would the adding of the <prev> -> <next> dependency create a
1617 *    circular dependency in the graph? [== circular deadlock]
1618 *
1619 *  - does the new prev->next dependency connect any hardirq-safe lock
1620 *    (in the full backwards-subgraph starting at <prev>) with any
1621 *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1622 *    <next>)? [== illegal lock inversion with hardirq contexts]
1623 *
1624 *  - does the new prev->next dependency connect any softirq-safe lock
1625 *    (in the full backwards-subgraph starting at <prev>) with any
1626 *    softirq-unsafe lock (in the full forwards-subgraph starting at
1627 *    <next>)? [== illegal lock inversion with softirq contexts]
1628 *
1629 * any of these scenarios could lead to a deadlock.
1630 *
1631 * Then if all the validations pass, we add the forwards and backwards
1632 * dependency.
1633 */
1634static int
1635check_prev_add(struct task_struct *curr, struct held_lock *prev,
1636               struct held_lock *next, int distance, int trylock_loop)
1637{
1638        struct lock_list *entry;
1639        int ret;
1640        struct lock_list this;
1641        struct lock_list *uninitialized_var(target_entry);
1642        /*
1643         * Static variable, serialized by the graph_lock().
1644         *
1645         * We use this static variable to save the stack trace in case
1646         * we call into this function multiple times due to encountering
1647         * trylocks in the held lock stack.
1648         */
1649        static struct stack_trace trace;
1650
1651        /*
1652         * Prove that the new <prev> -> <next> dependency would not
1653         * create a circular dependency in the graph. (We do this by
1654         * forward-recursing into the graph starting at <next>, and
1655         * checking whether we can reach <prev>.)
1656         *
1657         * We are using global variables to control the recursion, to
1658         * keep the stackframe size of the recursive functions low:
1659         */
1660        this.class = hlock_class(next);
1661        this.parent = NULL;
1662        ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1663        if (unlikely(!ret))
1664                return print_circular_bug(&this, target_entry, next, prev);
1665        else if (unlikely(ret < 0))
1666                return print_bfs_bug(ret);
1667
1668        if (!check_prev_add_irq(curr, prev, next))
1669                return 0;
1670
1671        /*
1672         * For recursive read-locks we do all the dependency checks,
1673         * but we dont store read-triggered dependencies (only
1674         * write-triggered dependencies). This ensures that only the
1675         * write-side dependencies matter, and that if for example a
1676         * write-lock never takes any other locks, then the reads are
1677         * equivalent to a NOP.
1678         */
1679        if (next->read == 2 || prev->read == 2)
1680                return 1;
1681        /*
1682         * Is the <prev> -> <next> dependency already present?
1683         *
1684         * (this may occur even though this is a new chain: consider
1685         *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1686         *  chains - the second one will be new, but L1 already has
1687         *  L2 added to its dependency list, due to the first chain.)
1688         */
1689        list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1690                if (entry->class == hlock_class(next)) {
1691                        if (distance == 1)
1692                                entry->distance = 1;
1693                        return 2;
1694                }
1695        }
1696
1697        if (!trylock_loop && !save_trace(&trace))
1698                return 0;
1699
1700        /*
1701         * Ok, all validations passed, add the new lock
1702         * to the previous lock's dependency list:
1703         */
1704        ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1705                               &hlock_class(prev)->locks_after,
1706                               next->acquire_ip, distance, &trace);
1707
1708        if (!ret)
1709                return 0;
1710
1711        ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1712                               &hlock_class(next)->locks_before,
1713                               next->acquire_ip, distance, &trace);
1714        if (!ret)
1715                return 0;
1716
1717        /*
1718         * Debugging printouts:
1719         */
1720        if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1721                graph_unlock();
1722                printk("\n new dependency: ");
1723                print_lock_name(hlock_class(prev));
1724                printk(" => ");
1725                print_lock_name(hlock_class(next));
1726                printk("\n");
1727                dump_stack();
1728                return graph_lock();
1729        }
1730        return 1;
1731}
1732
1733/*
1734 * Add the dependency to all directly-previous locks that are 'relevant'.
1735 * The ones that are relevant are (in increasing distance from curr):
1736 * all consecutive trylock entries and the final non-trylock entry - or
1737 * the end of this context's lock-chain - whichever comes first.
1738 */
1739static int
1740check_prevs_add(struct task_struct *curr, struct held_lock *next)
1741{
1742        int depth = curr->lockdep_depth;
1743        int trylock_loop = 0;
1744        struct held_lock *hlock;
1745
1746        /*
1747         * Debugging checks.
1748         *
1749         * Depth must not be zero for a non-head lock:
1750         */
1751        if (!depth)
1752                goto out_bug;
1753        /*
1754         * At least two relevant locks must exist for this
1755         * to be a head:
1756         */
1757        if (curr->held_locks[depth].irq_context !=
1758                        curr->held_locks[depth-1].irq_context)
1759                goto out_bug;
1760
1761        for (;;) {
1762                int distance = curr->lockdep_depth - depth + 1;
1763                hlock = curr->held_locks + depth-1;
1764                /*
1765                 * Only non-recursive-read entries get new dependencies
1766                 * added:
1767                 */
1768                if (hlock->read != 2) {
1769                        if (!check_prev_add(curr, hlock, next,
1770                                                distance, trylock_loop))
1771                                return 0;
1772                        /*
1773                         * Stop after the first non-trylock entry,
1774                         * as non-trylock entries have added their
1775                         * own direct dependencies already, so this
1776                         * lock is connected to them indirectly:
1777                         */
1778                        if (!hlock->trylock)
1779                                break;
1780                }
1781                depth--;
1782                /*
1783                 * End of lock-stack?
1784                 */
1785                if (!depth)
1786                        break;
1787                /*
1788                 * Stop the search if we cross into another context:
1789                 */
1790                if (curr->held_locks[depth].irq_context !=
1791                                curr->held_locks[depth-1].irq_context)
1792                        break;
1793                trylock_loop = 1;
1794        }
1795        return 1;
1796out_bug:
1797        if (!debug_locks_off_graph_unlock())
1798                return 0;
1799
1800        WARN_ON(1);
1801
1802        return 0;
1803}
1804
1805unsigned long nr_lock_chains;
1806struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1807int nr_chain_hlocks;
1808static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1809
1810struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1811{
1812        return lock_classes + chain_hlocks[chain->base + i];
1813}
1814
1815/*
1816 * Look up a dependency chain. If the key is not present yet then
1817 * add it and return 1 - in this case the new dependency chain is
1818 * validated. If the key is already hashed, return 0.
1819 * (On return with 1 graph_lock is held.)
1820 */
1821static inline int lookup_chain_cache(struct task_struct *curr,
1822                                     struct held_lock *hlock,
1823                                     u64 chain_key)
1824{
1825        struct lock_class *class = hlock_class(hlock);
1826        struct list_head *hash_head = chainhashentry(chain_key);
1827        struct lock_chain *chain;
1828        struct held_lock *hlock_curr, *hlock_next;
1829        int i, j, n, cn;
1830
1831        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1832                return 0;
1833        /*
1834         * We can walk it lock-free, because entries only get added
1835         * to the hash:
1836         */
1837        list_for_each_entry(chain, hash_head, entry) {
1838                if (chain->chain_key == chain_key) {
1839cache_hit:
1840                        debug_atomic_inc(chain_lookup_hits);
1841                        if (very_verbose(class))
1842                                printk("\nhash chain already cached, key: "
1843                                        "%016Lx tail class: [%p] %s\n",
1844                                        (unsigned long long)chain_key,
1845                                        class->key, class->name);
1846                        return 0;
1847                }
1848        }
1849        if (very_verbose(class))
1850                printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1851                        (unsigned long long)chain_key, class->key, class->name);
1852        /*
1853         * Allocate a new chain entry from the static array, and add
1854         * it to the hash:
1855         */
1856        if (!graph_lock())
1857                return 0;
1858        /*
1859         * We have to walk the chain again locked - to avoid duplicates:
1860         */
1861        list_for_each_entry(chain, hash_head, entry) {
1862                if (chain->chain_key == chain_key) {
1863                        graph_unlock();
1864                        goto cache_hit;
1865                }
1866        }
1867        if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1868                if (!debug_locks_off_graph_unlock())
1869                        return 0;
1870
1871                printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1872                printk("turning off the locking correctness validator.\n");
1873                dump_stack();
1874                return 0;
1875        }
1876        chain = lock_chains + nr_lock_chains++;
1877        chain->chain_key = chain_key;
1878        chain->irq_context = hlock->irq_context;
1879        /* Find the first held_lock of current chain */
1880        hlock_next = hlock;
1881        for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1882                hlock_curr = curr->held_locks + i;
1883                if (hlock_curr->irq_context != hlock_next->irq_context)
1884                        break;
1885                hlock_next = hlock;
1886        }
1887        i++;
1888        chain->depth = curr->lockdep_depth + 1 - i;
1889        cn = nr_chain_hlocks;
1890        while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1891                n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1892                if (n == cn)
1893                        break;
1894                cn = n;
1895        }
1896        if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1897                chain->base = cn;
1898                for (j = 0; j < chain->depth - 1; j++, i++) {
1899                        int lock_id = curr->held_locks[i].class_idx - 1;
1900                        chain_hlocks[chain->base + j] = lock_id;
1901                }
1902                chain_hlocks[chain->base + j] = class - lock_classes;
1903        }
1904        list_add_tail_rcu(&chain->entry, hash_head);
1905        debug_atomic_inc(chain_lookup_misses);
1906        inc_chains();
1907
1908        return 1;
1909}
1910
1911static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1912                struct held_lock *hlock, int chain_head, u64 chain_key)
1913{
1914        /*
1915         * Trylock needs to maintain the stack of held locks, but it
1916         * does not add new dependencies, because trylock can be done
1917         * in any order.
1918         *
1919         * We look up the chain_key and do the O(N^2) check and update of
1920         * the dependencies only if this is a new dependency chain.
1921         * (If lookup_chain_cache() returns with 1 it acquires
1922         * graph_lock for us)
1923         */
1924        if (!hlock->trylock && (hlock->check == 2) &&
1925            lookup_chain_cache(curr, hlock, chain_key)) {
1926                /*
1927                 * Check whether last held lock:
1928                 *
1929                 * - is irq-safe, if this lock is irq-unsafe
1930                 * - is softirq-safe, if this lock is hardirq-unsafe
1931                 *
1932                 * And check whether the new lock's dependency graph
1933                 * could lead back to the previous lock.
1934                 *
1935                 * any of these scenarios could lead to a deadlock. If
1936                 * All validations
1937                 */
1938                int ret = check_deadlock(curr, hlock, lock, hlock->read);
1939
1940                if (!ret)
1941                        return 0;
1942                /*
1943                 * Mark recursive read, as we jump over it when
1944                 * building dependencies (just like we jump over
1945                 * trylock entries):
1946                 */
1947                if (ret == 2)
1948                        hlock->read = 2;
1949                /*
1950                 * Add dependency only if this lock is not the head
1951                 * of the chain, and if it's not a secondary read-lock:
1952                 */
1953                if (!chain_head && ret != 2)
1954                        if (!check_prevs_add(curr, hlock))
1955                                return 0;
1956                graph_unlock();
1957        } else
1958                /* after lookup_chain_cache(): */
1959                if (unlikely(!debug_locks))
1960                        return 0;
1961
1962        return 1;
1963}
1964#else
1965static inline int validate_chain(struct task_struct *curr,
1966                struct lockdep_map *lock, struct held_lock *hlock,
1967                int chain_head, u64 chain_key)
1968{
1969        return 1;
1970}
1971#endif
1972
1973/*
1974 * We are building curr_chain_key incrementally, so double-check
1975 * it from scratch, to make sure that it's done correctly:
1976 */
1977static void check_chain_key(struct task_struct *curr)
1978{
1979#ifdef CONFIG_DEBUG_LOCKDEP
1980        struct held_lock *hlock, *prev_hlock = NULL;
1981        unsigned int i, id;
1982        u64 chain_key = 0;
1983
1984        for (i = 0; i < curr->lockdep_depth; i++) {
1985                hlock = curr->held_locks + i;
1986                if (chain_key != hlock->prev_chain_key) {
1987                        debug_locks_off();
1988                        WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1989                                curr->lockdep_depth, i,
1990                                (unsigned long long)chain_key,
1991                                (unsigned long long)hlock->prev_chain_key);
1992                        return;
1993                }
1994                id = hlock->class_idx - 1;
1995                if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1996                        return;
1997
1998                if (prev_hlock && (prev_hlock->irq_context !=
1999                                                        hlock->irq_context))
2000                        chain_key = 0;
2001                chain_key = iterate_chain_key(chain_key, id);
2002                prev_hlock = hlock;
2003        }
2004        if (chain_key != curr->curr_chain_key) {
2005                debug_locks_off();
2006                WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2007                        curr->lockdep_depth, i,
2008                        (unsigned long long)chain_key,
2009                        (unsigned long long)curr->curr_chain_key);
2010        }
2011#endif
2012}
2013
2014static int
2015print_usage_bug(struct task_struct *curr, struct held_lock *this,
2016                enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2017{
2018        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2019                return 0;
2020
2021        printk("\n=================================\n");
2022        printk(  "[ INFO: inconsistent lock state ]\n");
2023        print_kernel_version();
2024        printk(  "---------------------------------\n");
2025
2026        printk("inconsistent {%s} -> {%s} usage.\n",
2027                usage_str[prev_bit], usage_str[new_bit]);
2028
2029        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2030                curr->comm, task_pid_nr(curr),
2031                trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2032                trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2033                trace_hardirqs_enabled(curr),
2034                trace_softirqs_enabled(curr));
2035        print_lock(this);
2036
2037        printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2038        print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2039
2040        print_irqtrace_events(curr);
2041        printk("\nother info that might help us debug this:\n");
2042        lockdep_print_held_locks(curr);
2043
2044        printk("\nstack backtrace:\n");
2045        dump_stack();
2046
2047        return 0;
2048}
2049
2050/*
2051 * Print out an error if an invalid bit is set:
2052 */
2053static inline int
2054valid_state(struct task_struct *curr, struct held_lock *this,
2055            enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2056{
2057        if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2058                return print_usage_bug(curr, this, bad_bit, new_bit);
2059        return 1;
2060}
2061
2062static int mark_lock(struct task_struct *curr, struct held_lock *this,
2063                     enum lock_usage_bit new_bit);
2064
2065#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2066
2067/*
2068 * print irq inversion bug:
2069 */
2070static int
2071print_irq_inversion_bug(struct task_struct *curr,
2072                        struct lock_list *root, struct lock_list *other,
2073                        struct held_lock *this, int forwards,
2074                        const char *irqclass)
2075{
2076        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2077                return 0;
2078
2079        printk("\n=========================================================\n");
2080        printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2081        print_kernel_version();
2082        printk(  "---------------------------------------------------------\n");
2083        printk("%s/%d just changed the state of lock:\n",
2084                curr->comm, task_pid_nr(curr));
2085        print_lock(this);
2086        if (forwards)
2087                printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2088        else
2089                printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2090        print_lock_name(other->class);
2091        printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2092
2093        printk("\nother info that might help us debug this:\n");
2094        lockdep_print_held_locks(curr);
2095
2096        printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2097        if (!save_trace(&root->trace))
2098                return 0;
2099        print_shortest_lock_dependencies(other, root);
2100
2101        printk("\nstack backtrace:\n");
2102        dump_stack();
2103
2104        return 0;
2105}
2106
2107/*
2108 * Prove that in the forwards-direction subgraph starting at <this>
2109 * there is no lock matching <mask>:
2110 */
2111static int
2112check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2113                     enum lock_usage_bit bit, const char *irqclass)
2114{
2115        int ret;
2116        struct lock_list root;
2117        struct lock_list *uninitialized_var(target_entry);
2118
2119        root.parent = NULL;
2120        root.class = hlock_class(this);
2121        ret = find_usage_forwards(&root, bit, &target_entry);
2122        if (ret < 0)
2123                return print_bfs_bug(ret);
2124        if (ret == 1)
2125                return ret;
2126
2127        return print_irq_inversion_bug(curr, &root, target_entry,
2128                                        this, 1, irqclass);
2129}
2130
2131/*
2132 * Prove that in the backwards-direction subgraph starting at <this>
2133 * there is no lock matching <mask>:
2134 */
2135static int
2136check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2137                      enum lock_usage_bit bit, const char *irqclass)
2138{
2139        int ret;
2140        struct lock_list root;
2141        struct lock_list *uninitialized_var(target_entry);
2142
2143        root.parent = NULL;
2144        root.class = hlock_class(this);
2145        ret = find_usage_backwards(&root, bit, &target_entry);
2146        if (ret < 0)
2147                return print_bfs_bug(ret);
2148        if (ret == 1)
2149                return ret;
2150
2151        return print_irq_inversion_bug(curr, &root, target_entry,
2152                                        this, 0, irqclass);
2153}
2154
2155void print_irqtrace_events(struct task_struct *curr)
2156{
2157        printk("irq event stamp: %u\n", curr->irq_events);
2158        printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2159        print_ip_sym(curr->hardirq_enable_ip);
2160        printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2161        print_ip_sym(curr->hardirq_disable_ip);
2162        printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2163        print_ip_sym(curr->softirq_enable_ip);
2164        printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2165        print_ip_sym(curr->softirq_disable_ip);
2166}
2167
2168static int HARDIRQ_verbose(struct lock_class *class)
2169{
2170#if HARDIRQ_VERBOSE
2171        return class_filter(class);
2172#endif
2173        return 0;
2174}
2175
2176static int SOFTIRQ_verbose(struct lock_class *class)
2177{
2178#if SOFTIRQ_VERBOSE
2179        return class_filter(class);
2180#endif
2181        return 0;
2182}
2183
2184static int RECLAIM_FS_verbose(struct lock_class *class)
2185{
2186#if RECLAIM_VERBOSE
2187        return class_filter(class);
2188#endif
2189        return 0;
2190}
2191
2192#define STRICT_READ_CHECKS      1
2193
2194static int (*state_verbose_f[])(struct lock_class *class) = {
2195#define LOCKDEP_STATE(__STATE) \
2196        __STATE##_verbose,
2197#include "lockdep_states.h"
2198#undef LOCKDEP_STATE
2199};
2200
2201static inline int state_verbose(enum lock_usage_bit bit,
2202                                struct lock_class *class)
2203{
2204        return state_verbose_f[bit >> 2](class);
2205}
2206
2207typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2208                             enum lock_usage_bit bit, const char *name);
2209
2210static int
2211mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2212                enum lock_usage_bit new_bit)
2213{
2214        int excl_bit = exclusive_bit(new_bit);
2215        int read = new_bit & 1;
2216        int dir = new_bit & 2;
2217
2218        /*
2219         * mark USED_IN has to look forwards -- to ensure no dependency
2220         * has ENABLED state, which would allow recursion deadlocks.
2221         *
2222         * mark ENABLED has to look backwards -- to ensure no dependee
2223         * has USED_IN state, which, again, would allow  recursion deadlocks.
2224         */
2225        check_usage_f usage = dir ?
2226                check_usage_backwards : check_usage_forwards;
2227
2228        /*
2229         * Validate that this particular lock does not have conflicting
2230         * usage states.
2231         */
2232        if (!valid_state(curr, this, new_bit, excl_bit))
2233                return 0;
2234
2235        /*
2236         * Validate that the lock dependencies don't have conflicting usage
2237         * states.
2238         */
2239        if ((!read || !dir || STRICT_READ_CHECKS) &&
2240                        !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2241                return 0;
2242
2243        /*
2244         * Check for read in write conflicts
2245         */
2246        if (!read) {
2247                if (!valid_state(curr, this, new_bit, excl_bit + 1))
2248                        return 0;
2249
2250                if (STRICT_READ_CHECKS &&
2251                        !usage(curr, this, excl_bit + 1,
2252                                state_name(new_bit + 1)))
2253                        return 0;
2254        }
2255
2256        if (state_verbose(new_bit, hlock_class(this)))
2257                return 2;
2258
2259        return 1;
2260}
2261
2262enum mark_type {
2263#define LOCKDEP_STATE(__STATE)  __STATE,
2264#include "lockdep_states.h"
2265#undef LOCKDEP_STATE
2266};
2267
2268/*
2269 * Mark all held locks with a usage bit:
2270 */
2271static int
2272mark_held_locks(struct task_struct *curr, enum mark_type mark)
2273{
2274        enum lock_usage_bit usage_bit;
2275        struct held_lock *hlock;
2276        int i;
2277
2278        for (i = 0; i < curr->lockdep_depth; i++) {
2279                hlock = curr->held_locks + i;
2280
2281                usage_bit = 2 + (mark << 2); /* ENABLED */
2282                if (hlock->read)
2283                        usage_bit += 1; /* READ */
2284
2285                BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2286
2287                if (!mark_lock(curr, hlock, usage_bit))
2288                        return 0;
2289        }
2290
2291        return 1;
2292}
2293
2294/*
2295 * Debugging helper: via this flag we know that we are in
2296 * 'early bootup code', and will warn about any invalid irqs-on event:
2297 */
2298static int early_boot_irqs_enabled;
2299
2300void early_boot_irqs_off(void)
2301{
2302        early_boot_irqs_enabled = 0;
2303}
2304
2305void early_boot_irqs_on(void)
2306{
2307        early_boot_irqs_enabled = 1;
2308}
2309
2310/*
2311 * Hardirqs will be enabled:
2312 */
2313void trace_hardirqs_on_caller(unsigned long ip)
2314{
2315        struct task_struct *curr = current;
2316
2317        time_hardirqs_on(CALLER_ADDR0, ip);
2318
2319        if (unlikely(!debug_locks || current->lockdep_recursion))
2320                return;
2321
2322        if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2323                return;
2324
2325        if (unlikely(curr->hardirqs_enabled)) {
2326                /*
2327                 * Neither irq nor preemption are disabled here
2328                 * so this is racy by nature but loosing one hit
2329                 * in a stat is not a big deal.
2330                 */
2331                __debug_atomic_inc(redundant_hardirqs_on);
2332                return;
2333        }
2334        /* we'll do an OFF -> ON transition: */
2335        curr->hardirqs_enabled = 1;
2336
2337        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2338                return;
2339        if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2340                return;
2341        /*
2342         * We are going to turn hardirqs on, so set the
2343         * usage bit for all held locks:
2344         */
2345        if (!mark_held_locks(curr, HARDIRQ))
2346                return;
2347        /*
2348         * If we have softirqs enabled, then set the usage
2349         * bit for all held locks. (disabled hardirqs prevented
2350         * this bit from being set before)
2351         */
2352        if (curr->softirqs_enabled)
2353                if (!mark_held_locks(curr, SOFTIRQ))
2354                        return;
2355
2356        curr->hardirq_enable_ip = ip;
2357        curr->hardirq_enable_event = ++curr->irq_events;
2358        debug_atomic_inc(hardirqs_on_events);
2359}
2360EXPORT_SYMBOL(trace_hardirqs_on_caller);
2361
2362void trace_hardirqs_on(void)
2363{
2364        trace_hardirqs_on_caller(CALLER_ADDR0);
2365}
2366EXPORT_SYMBOL(trace_hardirqs_on);
2367
2368/*
2369 * Hardirqs were disabled:
2370 */
2371void trace_hardirqs_off_caller(unsigned long ip)
2372{
2373        struct task_struct *curr = current;
2374
2375        time_hardirqs_off(CALLER_ADDR0, ip);
2376
2377        if (unlikely(!debug_locks || current->lockdep_recursion))
2378                return;
2379
2380        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2381                return;
2382
2383        if (curr->hardirqs_enabled) {
2384                /*
2385                 * We have done an ON -> OFF transition:
2386                 */
2387                curr->hardirqs_enabled = 0;
2388                curr->hardirq_disable_ip = ip;
2389                curr->hardirq_disable_event = ++curr->irq_events;
2390                debug_atomic_inc(hardirqs_off_events);
2391        } else
2392                debug_atomic_inc(redundant_hardirqs_off);
2393}
2394EXPORT_SYMBOL(trace_hardirqs_off_caller);
2395
2396void trace_hardirqs_off(void)
2397{
2398        trace_hardirqs_off_caller(CALLER_ADDR0);
2399}
2400EXPORT_SYMBOL(trace_hardirqs_off);
2401
2402/*
2403 * Softirqs will be enabled:
2404 */
2405void trace_softirqs_on(unsigned long ip)
2406{
2407        struct task_struct *curr = current;
2408
2409        if (unlikely(!debug_locks))
2410                return;
2411
2412        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2413                return;
2414
2415        if (curr->softirqs_enabled) {
2416                debug_atomic_inc(redundant_softirqs_on);
2417                return;
2418        }
2419
2420        /*
2421         * We'll do an OFF -> ON transition:
2422         */
2423        curr->softirqs_enabled = 1;
2424        curr->softirq_enable_ip = ip;
2425        curr->softirq_enable_event = ++curr->irq_events;
2426        debug_atomic_inc(softirqs_on_events);
2427        /*
2428         * We are going to turn softirqs on, so set the
2429         * usage bit for all held locks, if hardirqs are
2430         * enabled too:
2431         */
2432        if (curr->hardirqs_enabled)
2433                mark_held_locks(curr, SOFTIRQ);
2434}
2435
2436/*
2437 * Softirqs were disabled:
2438 */
2439void trace_softirqs_off(unsigned long ip)
2440{
2441        struct task_struct *curr = current;
2442
2443        if (unlikely(!debug_locks))
2444                return;
2445
2446        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2447                return;
2448
2449        if (curr->softirqs_enabled) {
2450                /*
2451                 * We have done an ON -> OFF transition:
2452                 */
2453                curr->softirqs_enabled = 0;
2454                curr->softirq_disable_ip = ip;
2455                curr->softirq_disable_event = ++curr->irq_events;
2456                debug_atomic_inc(softirqs_off_events);
2457                DEBUG_LOCKS_WARN_ON(!softirq_count());
2458        } else
2459                debug_atomic_inc(redundant_softirqs_off);
2460}
2461
2462static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2463{
2464        struct task_struct *curr = current;
2465
2466        if (unlikely(!debug_locks))
2467                return;
2468
2469        /* no reclaim without waiting on it */
2470        if (!(gfp_mask & __GFP_WAIT))
2471                return;
2472
2473        /* this guy won't enter reclaim */
2474        if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2475                return;
2476
2477        /* We're only interested __GFP_FS allocations for now */
2478        if (!(gfp_mask & __GFP_FS))
2479                return;
2480
2481        if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2482                return;
2483
2484        mark_held_locks(curr, RECLAIM_FS);
2485}
2486
2487static void check_flags(unsigned long flags);
2488
2489void lockdep_trace_alloc(gfp_t gfp_mask)
2490{
2491        unsigned long flags;
2492
2493        if (unlikely(current->lockdep_recursion))
2494                return;
2495
2496        raw_local_irq_save(flags);
2497        check_flags(flags);
2498        current->lockdep_recursion = 1;
2499        __lockdep_trace_alloc(gfp_mask, flags);
2500        current->lockdep_recursion = 0;
2501        raw_local_irq_restore(flags);
2502}
2503
2504static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2505{
2506        /*
2507         * If non-trylock use in a hardirq or softirq context, then
2508         * mark the lock as used in these contexts:
2509         */
2510        if (!hlock->trylock) {
2511                if (hlock->read) {
2512                        if (curr->hardirq_context)
2513                                if (!mark_lock(curr, hlock,
2514                                                LOCK_USED_IN_HARDIRQ_READ))
2515                                        return 0;
2516                        if (curr->softirq_context)
2517                                if (!mark_lock(curr, hlock,
2518                                                LOCK_USED_IN_SOFTIRQ_READ))
2519                                        return 0;
2520                } else {
2521                        if (curr->hardirq_context)
2522                                if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2523                                        return 0;
2524                        if (curr->softirq_context)
2525                                if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2526                                        return 0;
2527                }
2528        }
2529        if (!hlock->hardirqs_off) {
2530                if (hlock->read) {
2531                        if (!mark_lock(curr, hlock,
2532                                        LOCK_ENABLED_HARDIRQ_READ))
2533                                return 0;
2534                        if (curr->softirqs_enabled)
2535                                if (!mark_lock(curr, hlock,
2536                                                LOCK_ENABLED_SOFTIRQ_READ))
2537                                        return 0;
2538                } else {
2539                        if (!mark_lock(curr, hlock,
2540                                        LOCK_ENABLED_HARDIRQ))
2541                                return 0;
2542                        if (curr->softirqs_enabled)
2543                                if (!mark_lock(curr, hlock,
2544                                                LOCK_ENABLED_SOFTIRQ))
2545                                        return 0;
2546                }
2547        }
2548
2549        /*
2550         * We reuse the irq context infrastructure more broadly as a general
2551         * context checking code. This tests GFP_FS recursion (a lock taken
2552         * during reclaim for a GFP_FS allocation is held over a GFP_FS
2553         * allocation).
2554         */
2555        if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2556                if (hlock->read) {
2557                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2558                                        return 0;
2559                } else {
2560                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2561                                        return 0;
2562                }
2563        }
2564
2565        return 1;
2566}
2567
2568static int separate_irq_context(struct task_struct *curr,
2569                struct held_lock *hlock)
2570{
2571        unsigned int depth = curr->lockdep_depth;
2572
2573        /*
2574         * Keep track of points where we cross into an interrupt context:
2575         */
2576        hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2577                                curr->softirq_context;
2578        if (depth) {
2579                struct held_lock *prev_hlock;
2580
2581                prev_hlock = curr->held_locks + depth-1;
2582                /*
2583                 * If we cross into another context, reset the
2584                 * hash key (this also prevents the checking and the
2585                 * adding of the dependency to 'prev'):
2586                 */
2587                if (prev_hlock->irq_context != hlock->irq_context)
2588                        return 1;
2589        }
2590        return 0;
2591}
2592
2593#else
2594
2595static inline
2596int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2597                enum lock_usage_bit new_bit)
2598{
2599        WARN_ON(1);
2600        return 1;
2601}
2602
2603static inline int mark_irqflags(struct task_struct *curr,
2604                struct held_lock *hlock)
2605{
2606        return 1;
2607}
2608
2609static inline int separate_irq_context(struct task_struct *curr,
2610                struct held_lock *hlock)
2611{
2612        return 0;
2613}
2614
2615void lockdep_trace_alloc(gfp_t gfp_mask)
2616{
2617}
2618
2619#endif
2620
2621/*
2622 * Mark a lock with a usage bit, and validate the state transition:
2623 */
2624static int mark_lock(struct task_struct *curr, struct held_lock *this,
2625                             enum lock_usage_bit new_bit)
2626{
2627        unsigned int new_mask = 1 << new_bit, ret = 1;
2628
2629        /*
2630         * If already set then do not dirty the cacheline,
2631         * nor do any checks:
2632         */
2633        if (likely(hlock_class(this)->usage_mask & new_mask))
2634                return 1;
2635
2636        if (!graph_lock())
2637                return 0;
2638        /*
2639         * Make sure we didnt race:
2640         */
2641        if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2642                graph_unlock();
2643                return 1;
2644        }
2645
2646        hlock_class(this)->usage_mask |= new_mask;
2647
2648        if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2649                return 0;
2650
2651        switch (new_bit) {
2652#define LOCKDEP_STATE(__STATE)                  \
2653        case LOCK_USED_IN_##__STATE:            \
2654        case LOCK_USED_IN_##__STATE##_READ:     \
2655        case LOCK_ENABLED_##__STATE:            \
2656        case LOCK_ENABLED_##__STATE##_READ:
2657#include "lockdep_states.h"
2658#undef LOCKDEP_STATE
2659                ret = mark_lock_irq(curr, this, new_bit);
2660                if (!ret)
2661                        return 0;
2662                break;
2663        case LOCK_USED:
2664                debug_atomic_dec(nr_unused_locks);
2665                break;
2666        default:
2667                if (!debug_locks_off_graph_unlock())
2668                        return 0;
2669                WARN_ON(1);
2670                return 0;
2671        }
2672
2673        graph_unlock();
2674
2675        /*
2676         * We must printk outside of the graph_lock:
2677         */
2678        if (ret == 2) {
2679                printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2680                print_lock(this);
2681                print_irqtrace_events(curr);
2682                dump_stack();
2683        }
2684
2685        return ret;
2686}
2687
2688/*
2689 * Initialize a lock instance's lock-class mapping info:
2690 */
2691void lockdep_init_map(struct lockdep_map *lock, const char *name,
2692                      struct lock_class_key *key, int subclass)
2693{
2694        int i;
2695
2696        for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2697                lock->class_cache[i] = NULL;
2698
2699#ifdef CONFIG_LOCK_STAT
2700        lock->cpu = raw_smp_processor_id();
2701#endif
2702
2703        if (DEBUG_LOCKS_WARN_ON(!name)) {
2704                lock->name = "NULL";
2705                return;
2706        }
2707
2708        lock->name = name;
2709
2710        if (DEBUG_LOCKS_WARN_ON(!key))
2711                return;
2712        /*
2713         * Sanity check, the lock-class key must be persistent:
2714         */
2715        if (!static_obj(key)) {
2716                printk("BUG: key %p not in .data!\n", key);
2717                DEBUG_LOCKS_WARN_ON(1);
2718                return;
2719        }
2720        lock->key = key;
2721
2722        if (unlikely(!debug_locks))
2723                return;
2724
2725        if (subclass)
2726                register_lock_class(lock, subclass, 1);
2727}
2728EXPORT_SYMBOL_GPL(lockdep_init_map);
2729
2730struct lock_class_key __lockdep_no_validate__;
2731
2732/*
2733 * This gets called for every mutex_lock*()/spin_lock*() operation.
2734 * We maintain the dependency maps and validate the locking attempt:
2735 */
2736static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2737                          int trylock, int read, int check, int hardirqs_off,
2738                          struct lockdep_map *nest_lock, unsigned long ip,
2739                          int references)
2740{
2741        struct task_struct *curr = current;
2742        struct lock_class *class = NULL;
2743        struct held_lock *hlock;
2744        unsigned int depth, id;
2745        int chain_head = 0;
2746        int class_idx;
2747        u64 chain_key;
2748
2749        if (!prove_locking)
2750                check = 1;
2751
2752        if (unlikely(!debug_locks))
2753                return 0;
2754
2755        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2756                return 0;
2757
2758        if (lock->key == &__lockdep_no_validate__)
2759                check = 1;
2760
2761        if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2762                class = lock->class_cache[subclass];
2763        /*
2764         * Not cached?
2765         */
2766        if (unlikely(!class)) {
2767                class = register_lock_class(lock, subclass, 0);
2768                if (!class)
2769                        return 0;
2770        }
2771        atomic_inc((atomic_t *)&class->ops);
2772        if (very_verbose(class)) {
2773                printk("\nacquire class [%p] %s", class->key, class->name);
2774                if (class->name_version > 1)
2775                        printk("#%d", class->name_version);
2776                printk("\n");
2777                dump_stack();
2778        }
2779
2780        /*
2781         * Add the lock to the list of currently held locks.
2782         * (we dont increase the depth just yet, up until the
2783         * dependency checks are done)
2784         */
2785        depth = curr->lockdep_depth;
2786        if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2787                return 0;
2788
2789        class_idx = class - lock_classes + 1;
2790
2791        if (depth) {
2792                hlock = curr->held_locks + depth - 1;
2793                if (hlock->class_idx == class_idx && nest_lock) {
2794                        if (hlock->references)
2795                                hlock->references++;
2796                        else
2797                                hlock->references = 2;
2798
2799                        return 1;
2800                }
2801        }
2802
2803        hlock = curr->held_locks + depth;
2804        if (DEBUG_LOCKS_WARN_ON(!class))
2805                return 0;
2806        hlock->class_idx = class_idx;
2807        hlock->acquire_ip = ip;
2808        hlock->instance = lock;
2809        hlock->nest_lock = nest_lock;
2810        hlock->trylock = trylock;
2811        hlock->read = read;
2812        hlock->check = check;
2813        hlock->hardirqs_off = !!hardirqs_off;
2814        hlock->references = references;
2815#ifdef CONFIG_LOCK_STAT
2816        hlock->waittime_stamp = 0;
2817        hlock->holdtime_stamp = lockstat_clock();
2818#endif
2819
2820        if (check == 2 && !mark_irqflags(curr, hlock))
2821                return 0;
2822
2823        /* mark it as used: */
2824        if (!mark_lock(curr, hlock, LOCK_USED))
2825                return 0;
2826
2827        /*
2828         * Calculate the chain hash: it's the combined hash of all the
2829         * lock keys along the dependency chain. We save the hash value
2830         * at every step so that we can get the current hash easily
2831         * after unlock. The chain hash is then used to cache dependency
2832         * results.
2833         *
2834         * The 'key ID' is what is the most compact key value to drive
2835         * the hash, not class->key.
2836         */
2837        id = class - lock_classes;
2838        if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2839                return 0;
2840
2841        chain_key = curr->curr_chain_key;
2842        if (!depth) {
2843                if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2844                        return 0;
2845                chain_head = 1;
2846        }
2847
2848        hlock->prev_chain_key = chain_key;
2849        if (separate_irq_context(curr, hlock)) {
2850                chain_key = 0;
2851                chain_head = 1;
2852        }
2853        chain_key = iterate_chain_key(chain_key, id);
2854
2855        if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2856                return 0;
2857
2858        curr->curr_chain_key = chain_key;
2859        curr->lockdep_depth++;
2860        check_chain_key(curr);
2861#ifdef CONFIG_DEBUG_LOCKDEP
2862        if (unlikely(!debug_locks))
2863                return 0;
2864#endif
2865        if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2866                debug_locks_off();
2867                printk("BUG: MAX_LOCK_DEPTH too low!\n");
2868                printk("turning off the locking correctness validator.\n");
2869                dump_stack();
2870                return 0;
2871        }
2872
2873        if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2874                max_lockdep_depth = curr->lockdep_depth;
2875
2876        return 1;
2877}
2878
2879static int
2880print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2881                           unsigned long ip)
2882{
2883        if (!debug_locks_off())
2884                return 0;
2885        if (debug_locks_silent)
2886                return 0;
2887
2888        printk("\n=====================================\n");
2889        printk(  "[ BUG: bad unlock balance detected! ]\n");
2890        printk(  "-------------------------------------\n");
2891        printk("%s/%d is trying to release lock (",
2892                curr->comm, task_pid_nr(curr));
2893        print_lockdep_cache(lock);
2894        printk(") at:\n");
2895        print_ip_sym(ip);
2896        printk("but there are no more locks to release!\n");
2897        printk("\nother info that might help us debug this:\n");
2898        lockdep_print_held_locks(curr);
2899
2900        printk("\nstack backtrace:\n");
2901        dump_stack();
2902
2903        return 0;
2904}
2905
2906/*
2907 * Common debugging checks for both nested and non-nested unlock:
2908 */
2909static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2910                        unsigned long ip)
2911{
2912        if (unlikely(!debug_locks))
2913                return 0;
2914        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2915                return 0;
2916
2917        if (curr->lockdep_depth <= 0)
2918                return print_unlock_inbalance_bug(curr, lock, ip);
2919
2920        return 1;
2921}
2922
2923static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2924{
2925        if (hlock->instance == lock)
2926                return 1;
2927
2928        if (hlock->references) {
2929                struct lock_class *class = lock->class_cache[0];
2930
2931                if (!class)
2932                        class = look_up_lock_class(lock, 0);
2933
2934                if (DEBUG_LOCKS_WARN_ON(!class))
2935                        return 0;
2936
2937                if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2938                        return 0;
2939
2940                if (hlock->class_idx == class - lock_classes + 1)
2941                        return 1;
2942        }
2943
2944        return 0;
2945}
2946
2947static int
2948__lock_set_class(struct lockdep_map *lock, const char *name,
2949                 struct lock_class_key *key, unsigned int subclass,
2950                 unsigned long ip)
2951{
2952        struct task_struct *curr = current;
2953        struct held_lock *hlock, *prev_hlock;
2954        struct lock_class *class;
2955        unsigned int depth;
2956        int i;
2957
2958        depth = curr->lockdep_depth;
2959        if (DEBUG_LOCKS_WARN_ON(!depth))
2960                return 0;
2961
2962        prev_hlock = NULL;
2963        for (i = depth-1; i >= 0; i--) {
2964                hlock = curr->held_locks + i;
2965                /*
2966                 * We must not cross into another context:
2967                 */
2968                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2969                        break;
2970                if (match_held_lock(hlock, lock))
2971                        goto found_it;
2972                prev_hlock = hlock;
2973        }
2974        return print_unlock_inbalance_bug(curr, lock, ip);
2975
2976found_it:
2977        lockdep_init_map(lock, name, key, 0);
2978        class = register_lock_class(lock, subclass, 0);
2979        hlock->class_idx = class - lock_classes + 1;
2980
2981        curr->lockdep_depth = i;
2982        curr->curr_chain_key = hlock->prev_chain_key;
2983
2984        for (; i < depth; i++) {
2985                hlock = curr->held_locks + i;
2986                if (!__lock_acquire(hlock->instance,
2987                        hlock_class(hlock)->subclass, hlock->trylock,
2988                                hlock->read, hlock->check, hlock->hardirqs_off,
2989                                hlock->nest_lock, hlock->acquire_ip,
2990                                hlock->references))
2991                        return 0;
2992        }
2993
2994        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2995                return 0;
2996        return 1;
2997}
2998
2999/*
3000 * Remove the lock to the list of currently held locks in a
3001 * potentially non-nested (out of order) manner. This is a
3002 * relatively rare operation, as all the unlock APIs default
3003 * to nested mode (which uses lock_release()):
3004 */
3005static int
3006lock_release_non_nested(struct task_struct *curr,
3007                        struct lockdep_map *lock, unsigned long ip)
3008{
3009        struct held_lock *hlock, *prev_hlock;
3010        unsigned int depth;
3011        int i;
3012
3013        /*
3014         * Check whether the lock exists in the current stack
3015         * of held locks:
3016         */
3017        depth = curr->lockdep_depth;
3018        if (DEBUG_LOCKS_WARN_ON(!depth))
3019                return 0;
3020
3021        prev_hlock = NULL;
3022        for (i = depth-1; i >= 0; i--) {
3023                hlock = curr->held_locks + i;
3024                /*
3025                 * We must not cross into another context:
3026                 */
3027                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3028                        break;
3029                if (match_held_lock(hlock, lock))
3030                        goto found_it;
3031                prev_hlock = hlock;
3032        }
3033        return print_unlock_inbalance_bug(curr, lock, ip);
3034
3035found_it:
3036        if (hlock->instance == lock)
3037                lock_release_holdtime(hlock);
3038
3039        if (hlock->references) {
3040                hlock->references--;
3041                if (hlock->references) {
3042                        /*
3043                         * We had, and after removing one, still have
3044                         * references, the current lock stack is still
3045                         * valid. We're done!
3046                         */
3047                        return 1;
3048                }
3049        }
3050
3051        /*
3052         * We have the right lock to unlock, 'hlock' points to it.
3053         * Now we remove it from the stack, and add back the other
3054         * entries (if any), recalculating the hash along the way:
3055         */
3056
3057        curr->lockdep_depth = i;
3058        curr->curr_chain_key = hlock->prev_chain_key;
3059
3060        for (i++; i < depth; i++) {
3061                hlock = curr->held_locks + i;
3062                if (!__lock_acquire(hlock->instance,
3063                        hlock_class(hlock)->subclass, hlock->trylock,
3064                                hlock->read, hlock->check, hlock->hardirqs_off,
3065                                hlock->nest_lock, hlock->acquire_ip,
3066                                hlock->references))
3067                        return 0;
3068        }
3069
3070        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3071                return 0;
3072        return 1;
3073}
3074
3075/*
3076 * Remove the lock to the list of currently held locks - this gets
3077 * called on mutex_unlock()/spin_unlock*() (or on a failed
3078 * mutex_lock_interruptible()). This is done for unlocks that nest
3079 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3080 */
3081static int lock_release_nested(struct task_struct *curr,
3082                               struct lockdep_map *lock, unsigned long ip)
3083{
3084        struct held_lock *hlock;
3085        unsigned int depth;
3086
3087        /*
3088         * Pop off the top of the lock stack:
3089         */
3090        depth = curr->lockdep_depth - 1;
3091        hlock = curr->held_locks + depth;
3092
3093        /*
3094         * Is the unlock non-nested:
3095         */
3096        if (hlock->instance != lock || hlock->references)
3097                return lock_release_non_nested(curr, lock, ip);
3098        curr->lockdep_depth--;
3099
3100        if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3101                return 0;
3102
3103        curr->curr_chain_key = hlock->prev_chain_key;
3104
3105        lock_release_holdtime(hlock);
3106
3107#ifdef CONFIG_DEBUG_LOCKDEP
3108        hlock->prev_chain_key = 0;
3109        hlock->class_idx = 0;
3110        hlock->acquire_ip = 0;
3111        hlock->irq_context = 0;
3112#endif
3113        return 1;
3114}
3115
3116/*
3117 * Remove the lock to the list of currently held locks - this gets
3118 * called on mutex_unlock()/spin_unlock*() (or on a failed
3119 * mutex_lock_interruptible()). This is done for unlocks that nest
3120 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3121 */
3122static void
3123__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3124{
3125        struct task_struct *curr = current;
3126
3127        if (!check_unlock(curr, lock, ip))
3128                return;
3129
3130        if (nested) {
3131                if (!lock_release_nested(curr, lock, ip))
3132                        return;
3133        } else {
3134                if (!lock_release_non_nested(curr, lock, ip))
3135                        return;
3136        }
3137
3138        check_chain_key(curr);
3139}
3140
3141static int __lock_is_held(struct lockdep_map *lock)
3142{
3143        struct task_struct *curr = current;
3144        int i;
3145
3146        for (i = 0; i < curr->lockdep_depth; i++) {
3147                struct held_lock *hlock = curr->held_locks + i;
3148
3149                if (match_held_lock(hlock, lock))
3150                        return 1;
3151        }
3152
3153        return 0;
3154}
3155
3156/*
3157 * Check whether we follow the irq-flags state precisely:
3158 */
3159static void check_flags(unsigned long flags)
3160{
3161#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3162    defined(CONFIG_TRACE_IRQFLAGS)
3163        if (!debug_locks)
3164                return;
3165
3166        if (irqs_disabled_flags(flags)) {
3167                if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3168                        printk("possible reason: unannotated irqs-off.\n");
3169                }
3170        } else {
3171                if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3172                        printk("possible reason: unannotated irqs-on.\n");
3173                }
3174        }
3175
3176        /*
3177         * We dont accurately track softirq state in e.g.
3178         * hardirq contexts (such as on 4KSTACKS), so only
3179         * check if not in hardirq contexts:
3180         */
3181        if (!hardirq_count()) {
3182                if (softirq_count())
3183                        DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3184                else
3185                        DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3186        }
3187
3188        if (!debug_locks)
3189                print_irqtrace_events(current);
3190#endif
3191}
3192
3193void lock_set_class(struct lockdep_map *lock, const char *name,
3194                    struct lock_class_key *key, unsigned int subclass,
3195                    unsigned long ip)
3196{
3197        unsigned long flags;
3198
3199        if (unlikely(current->lockdep_recursion))
3200                return;
3201
3202        raw_local_irq_save(flags);
3203        current->lockdep_recursion = 1;
3204        check_flags(flags);
3205        if (__lock_set_class(lock, name, key, subclass, ip))
3206                check_chain_key(current);
3207        current->lockdep_recursion = 0;
3208        raw_local_irq_restore(flags);
3209}
3210EXPORT_SYMBOL_GPL(lock_set_class);
3211
3212/*
3213 * We are not always called with irqs disabled - do that here,
3214 * and also avoid lockdep recursion:
3215 */
3216void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3217                          int trylock, int read, int check,
3218                          struct lockdep_map *nest_lock, unsigned long ip)
3219{
3220        unsigned long flags;
3221
3222        if (unlikely(current->lockdep_recursion))
3223                return;
3224
3225        raw_local_irq_save(flags);
3226        check_flags(flags);
3227
3228        current->lockdep_recursion = 1;
3229        trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3230        __lock_acquire(lock, subclass, trylock, read, check,
3231                       irqs_disabled_flags(flags), nest_lock, ip, 0);
3232        current->lockdep_recursion = 0;
3233        raw_local_irq_restore(flags);
3234}
3235EXPORT_SYMBOL_GPL(lock_acquire);
3236
3237void lock_release(struct lockdep_map *lock, int nested,
3238                          unsigned long ip)
3239{
3240        unsigned long flags;
3241
3242        if (unlikely(current->lockdep_recursion))
3243                return;
3244
3245        raw_local_irq_save(flags);
3246        check_flags(flags);
3247        current->lockdep_recursion = 1;
3248        trace_lock_release(lock, ip);
3249        __lock_release(lock, nested, ip);
3250        current->lockdep_recursion = 0;
3251        raw_local_irq_restore(flags);
3252}
3253EXPORT_SYMBOL_GPL(lock_release);
3254
3255int lock_is_held(struct lockdep_map *lock)
3256{
3257        unsigned long flags;
3258        int ret = 0;
3259
3260        if (unlikely(current->lockdep_recursion))
3261                return ret;
3262
3263        raw_local_irq_save(flags);
3264        check_flags(flags);
3265
3266        current->lockdep_recursion = 1;
3267        ret = __lock_is_held(lock);
3268        current->lockdep_recursion = 0;
3269        raw_local_irq_restore(flags);
3270
3271        return ret;
3272}
3273EXPORT_SYMBOL_GPL(lock_is_held);
3274
3275void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3276{
3277        current->lockdep_reclaim_gfp = gfp_mask;
3278}
3279
3280void lockdep_clear_current_reclaim_state(void)
3281{
3282        current->lockdep_reclaim_gfp = 0;
3283}
3284
3285#ifdef CONFIG_LOCK_STAT
3286static int
3287print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3288                           unsigned long ip)
3289{
3290        if (!debug_locks_off())
3291                return 0;
3292        if (debug_locks_silent)
3293                return 0;
3294
3295        printk("\n=================================\n");
3296        printk(  "[ BUG: bad contention detected! ]\n");
3297        printk(  "---------------------------------\n");
3298        printk("%s/%d is trying to contend lock (",
3299                curr->comm, task_pid_nr(curr));
3300        print_lockdep_cache(lock);
3301        printk(") at:\n");
3302        print_ip_sym(ip);
3303        printk("but there are no locks held!\n");
3304        printk("\nother info that might help us debug this:\n");
3305        lockdep_print_held_locks(curr);
3306
3307        printk("\nstack backtrace:\n");
3308        dump_stack();
3309
3310        return 0;
3311}
3312
3313static void
3314__lock_contended(struct lockdep_map *lock, unsigned long ip)
3315{
3316        struct task_struct *curr = current;
3317        struct held_lock *hlock, *prev_hlock;
3318        struct lock_class_stats *stats;
3319        unsigned int depth;
3320        int i, contention_point, contending_point;
3321
3322        depth = curr->lockdep_depth;
3323        if (DEBUG_LOCKS_WARN_ON(!depth))
3324                return;
3325
3326        prev_hlock = NULL;
3327        for (i = depth-1; i >= 0; i--) {
3328                hlock = curr->held_locks + i;
3329                /*
3330                 * We must not cross into another context:
3331                 */
3332                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3333                        break;
3334                if (match_held_lock(hlock, lock))
3335                        goto found_it;
3336                prev_hlock = hlock;
3337        }
3338        print_lock_contention_bug(curr, lock, ip);
3339        return;
3340
3341found_it:
3342        if (hlock->instance != lock)
3343                return;
3344
3345        hlock->waittime_stamp = lockstat_clock();
3346
3347        contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3348        contending_point = lock_point(hlock_class(hlock)->contending_point,
3349                                      lock->ip);
3350
3351        stats = get_lock_stats(hlock_class(hlock));
3352        if (contention_point < LOCKSTAT_POINTS)
3353                stats->contention_point[contention_point]++;
3354        if (contending_point < LOCKSTAT_POINTS)
3355                stats->contending_point[contending_point]++;
3356        if (lock->cpu != smp_processor_id())
3357                stats->bounces[bounce_contended + !!hlock->read]++;
3358        put_lock_stats(stats);
3359}
3360
3361static void
3362__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3363{
3364        struct task_struct *curr = current;
3365        struct held_lock *hlock, *prev_hlock;
3366        struct lock_class_stats *stats;
3367        unsigned int depth;
3368        u64 now, waittime = 0;
3369        int i, cpu;
3370
3371        depth = curr->lockdep_depth;
3372        if (DEBUG_LOCKS_WARN_ON(!depth))
3373                return;
3374
3375        prev_hlock = NULL;
3376        for (i = depth-1; i >= 0; i--) {
3377                hlock = curr->held_locks + i;
3378                /*
3379                 * We must not cross into another context:
3380                 */
3381                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3382                        break;
3383                if (match_held_lock(hlock, lock))
3384                        goto found_it;
3385                prev_hlock = hlock;
3386        }
3387        print_lock_contention_bug(curr, lock, _RET_IP_);
3388        return;
3389
3390found_it:
3391        if (hlock->instance != lock)
3392                return;
3393
3394        cpu = smp_processor_id();
3395        if (hlock->waittime_stamp) {
3396                now = lockstat_clock();
3397                waittime = now - hlock->waittime_stamp;
3398                hlock->holdtime_stamp = now;
3399        }
3400
3401        trace_lock_acquired(lock, ip);
3402
3403        stats = get_lock_stats(hlock_class(hlock));
3404        if (waittime) {
3405                if (hlock->read)
3406                        lock_time_inc(&stats->read_waittime, waittime);
3407                else
3408                        lock_time_inc(&stats->write_waittime, waittime);
3409        }
3410        if (lock->cpu != cpu)
3411                stats->bounces[bounce_acquired + !!hlock->read]++;
3412        put_lock_stats(stats);
3413
3414        lock->cpu = cpu;
3415        lock->ip = ip;
3416}
3417
3418void lock_contended(struct lockdep_map *lock, unsigned long ip)
3419{
3420        unsigned long flags;
3421
3422        if (unlikely(!lock_stat))
3423                return;
3424
3425        if (unlikely(current->lockdep_recursion))
3426                return;
3427
3428        raw_local_irq_save(flags);
3429        check_flags(flags);
3430        current->lockdep_recursion = 1;
3431        trace_lock_contended(lock, ip);
3432        __lock_contended(lock, ip);
3433        current->lockdep_recursion = 0;
3434        raw_local_irq_restore(flags);
3435}
3436EXPORT_SYMBOL_GPL(lock_contended);
3437
3438void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3439{
3440        unsigned long flags;
3441
3442        if (unlikely(!lock_stat))
3443                return;
3444
3445        if (unlikely(current->lockdep_recursion))
3446                return;
3447
3448        raw_local_irq_save(flags);
3449        check_flags(flags);
3450        current->lockdep_recursion = 1;
3451        __lock_acquired(lock, ip);
3452        current->lockdep_recursion = 0;
3453        raw_local_irq_restore(flags);
3454}
3455EXPORT_SYMBOL_GPL(lock_acquired);
3456#endif
3457
3458/*
3459 * Used by the testsuite, sanitize the validator state
3460 * after a simulated failure:
3461 */
3462
3463void lockdep_reset(void)
3464{
3465        unsigned long flags;
3466        int i;
3467
3468        raw_local_irq_save(flags);
3469        current->curr_chain_key = 0;
3470        current->lockdep_depth = 0;
3471        current->lockdep_recursion = 0;
3472        memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3473        nr_hardirq_chains = 0;
3474        nr_softirq_chains = 0;
3475        nr_process_chains = 0;
3476        debug_locks = 1;
3477        for (i = 0; i < CHAINHASH_SIZE; i++)
3478                INIT_LIST_HEAD(chainhash_table + i);
3479        raw_local_irq_restore(flags);
3480}
3481
3482static void zap_class(struct lock_class *class)
3483{
3484        int i;
3485
3486        /*
3487         * Remove all dependencies this lock is
3488         * involved in:
3489         */
3490        for (i = 0; i < nr_list_entries; i++) {
3491                if (list_entries[i].class == class)
3492                        list_del_rcu(&list_entries[i].entry);
3493        }
3494        /*
3495         * Unhash the class and remove it from the all_lock_classes list:
3496         */
3497        list_del_rcu(&class->hash_entry);
3498        list_del_rcu(&class->lock_entry);
3499
3500        class->key = NULL;
3501}
3502
3503static inline int within(const void *addr, void *start, unsigned long size)
3504{
3505        return addr >= start && addr < start + size;
3506}
3507
3508void lockdep_free_key_range(void *start, unsigned long size)
3509{
3510        struct lock_class *class, *next;
3511        struct list_head *head;
3512        unsigned long flags;
3513        int i;
3514        int locked;
3515
3516        raw_local_irq_save(flags);
3517        locked = graph_lock();
3518
3519        /*
3520         * Unhash all classes that were created by this module:
3521         */
3522        for (i = 0; i < CLASSHASH_SIZE; i++) {
3523                head = classhash_table + i;
3524                if (list_empty(head))
3525                        continue;
3526                list_for_each_entry_safe(class, next, head, hash_entry) {
3527                        if (within(class->key, start, size))
3528                                zap_class(class);
3529                        else if (within(class->name, start, size))
3530                                zap_class(class);
3531                }
3532        }
3533
3534        if (locked)
3535                graph_unlock();
3536        raw_local_irq_restore(flags);
3537}
3538
3539void lockdep_reset_lock(struct lockdep_map *lock)
3540{
3541        struct lock_class *class, *next;
3542        struct list_head *head;
3543        unsigned long flags;
3544        int i, j;
3545        int locked;
3546
3547        raw_local_irq_save(flags);
3548
3549        /*
3550         * Remove all classes this lock might have:
3551         */
3552        for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3553                /*
3554                 * If the class exists we look it up and zap it:
3555                 */
3556                class = look_up_lock_class(lock, j);
3557                if (class)
3558                        zap_class(class);
3559        }
3560        /*
3561         * Debug check: in the end all mapped classes should
3562         * be gone.
3563         */
3564        locked = graph_lock();
3565        for (i = 0; i < CLASSHASH_SIZE; i++) {
3566                head = classhash_table + i;
3567                if (list_empty(head))
3568                        continue;
3569                list_for_each_entry_safe(class, next, head, hash_entry) {
3570                        int match = 0;
3571
3572                        for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3573                                match |= class == lock->class_cache[j];
3574
3575                        if (unlikely(match)) {
3576                                if (debug_locks_off_graph_unlock())
3577                                        WARN_ON(1);
3578                                goto out_restore;
3579                        }
3580                }
3581        }
3582        if (locked)
3583                graph_unlock();
3584
3585out_restore:
3586        raw_local_irq_restore(flags);
3587}
3588
3589void lockdep_init(void)
3590{
3591        int i;
3592
3593        /*
3594         * Some architectures have their own start_kernel()
3595         * code which calls lockdep_init(), while we also
3596         * call lockdep_init() from the start_kernel() itself,
3597         * and we want to initialize the hashes only once:
3598         */
3599        if (lockdep_initialized)
3600                return;
3601
3602        for (i = 0; i < CLASSHASH_SIZE; i++)
3603                INIT_LIST_HEAD(classhash_table + i);
3604
3605        for (i = 0; i < CHAINHASH_SIZE; i++)
3606                INIT_LIST_HEAD(chainhash_table + i);
3607
3608        lockdep_initialized = 1;
3609}
3610
3611void __init lockdep_info(void)
3612{
3613        printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3614
3615        printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3616        printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3617        printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3618        printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3619        printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3620        printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3621        printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3622
3623        printk(" memory used by lock dependency info: %lu kB\n",
3624                (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3625                sizeof(struct list_head) * CLASSHASH_SIZE +
3626                sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3627                sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3628                sizeof(struct list_head) * CHAINHASH_SIZE
3629#ifdef CONFIG_PROVE_LOCKING
3630                + sizeof(struct circular_queue)
3631#endif
3632                ) / 1024
3633                );
3634
3635        printk(" per task-struct memory footprint: %lu bytes\n",
3636                sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3637
3638#ifdef CONFIG_DEBUG_LOCKDEP
3639        if (lockdep_init_error) {
3640                printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3641                printk("Call stack leading to lockdep invocation was:\n");
3642                print_stack_trace(&lockdep_init_trace, 0);
3643        }
3644#endif
3645}
3646
3647static void
3648print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3649                     const void *mem_to, struct held_lock *hlock)
3650{
3651        if (!debug_locks_off())
3652                return;
3653        if (debug_locks_silent)
3654                return;
3655
3656        printk("\n=========================\n");
3657        printk(  "[ BUG: held lock freed! ]\n");
3658        printk(  "-------------------------\n");
3659        printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3660                curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3661        print_lock(hlock);
3662        lockdep_print_held_locks(curr);
3663
3664        printk("\nstack backtrace:\n");
3665        dump_stack();
3666}
3667
3668static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3669                                const void* lock_from, unsigned long lock_len)
3670{
3671        return lock_from + lock_len <= mem_from ||
3672                mem_from + mem_len <= lock_from;
3673}
3674
3675/*
3676 * Called when kernel memory is freed (or unmapped), or if a lock
3677 * is destroyed or reinitialized - this code checks whether there is
3678 * any held lock in the memory range of <from> to <to>:
3679 */
3680void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3681{
3682        struct task_struct *curr = current;
3683        struct held_lock *hlock;
3684        unsigned long flags;
3685        int i;
3686
3687        if (unlikely(!debug_locks))
3688                return;
3689
3690        local_irq_save(flags);
3691        for (i = 0; i < curr->lockdep_depth; i++) {
3692                hlock = curr->held_locks + i;
3693
3694                if (not_in_range(mem_from, mem_len, hlock->instance,
3695                                        sizeof(*hlock->instance)))
3696                        continue;
3697
3698                print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3699                break;
3700        }
3701        local_irq_restore(flags);
3702}
3703EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3704
3705static void print_held_locks_bug(struct task_struct *curr)
3706{
3707        if (!debug_locks_off())
3708                return;
3709        if (debug_locks_silent)
3710                return;
3711
3712        printk("\n=====================================\n");
3713        printk(  "[ BUG: lock held at task exit time! ]\n");
3714        printk(  "-------------------------------------\n");
3715        printk("%s/%d is exiting with locks still held!\n",
3716                curr->comm, task_pid_nr(curr));
3717        lockdep_print_held_locks(curr);
3718
3719        printk("\nstack backtrace:\n");
3720        dump_stack();
3721}
3722
3723void debug_check_no_locks_held(struct task_struct *task)
3724{
3725        if (unlikely(task->lockdep_depth > 0))
3726                print_held_locks_bug(task);
3727}
3728
3729void debug_show_all_locks(void)
3730{
3731        struct task_struct *g, *p;
3732        int count = 10;
3733        int unlock = 1;
3734
3735        if (unlikely(!debug_locks)) {
3736                printk("INFO: lockdep is turned off.\n");
3737                return;
3738        }
3739        printk("\nShowing all locks held in the system:\n");
3740
3741        /*
3742         * Here we try to get the tasklist_lock as hard as possible,
3743         * if not successful after 2 seconds we ignore it (but keep
3744         * trying). This is to enable a debug printout even if a
3745         * tasklist_lock-holding task deadlocks or crashes.
3746         */
3747retry:
3748        if (!read_trylock(&tasklist_lock)) {
3749                if (count == 10)
3750                        printk("hm, tasklist_lock locked, retrying... ");
3751                if (count) {
3752                        count--;
3753                        printk(" #%d", 10-count);
3754                        mdelay(200);
3755                        goto retry;
3756                }
3757                printk(" ignoring it.\n");
3758                unlock = 0;
3759        } else {
3760                if (count != 10)
3761                        printk(KERN_CONT " locked it.\n");
3762        }
3763
3764        do_each_thread(g, p) {
3765                /*
3766                 * It's not reliable to print a task's held locks
3767                 * if it's not sleeping (or if it's not the current
3768                 * task):
3769                 */
3770                if (p->state == TASK_RUNNING && p != current)
3771                        continue;
3772                if (p->lockdep_depth)
3773                        lockdep_print_held_locks(p);
3774                if (!unlock)
3775                        if (read_trylock(&tasklist_lock))
3776                                unlock = 1;
3777        } while_each_thread(g, p);
3778
3779        printk("\n");
3780        printk("=============================================\n\n");
3781
3782        if (unlock)
3783                read_unlock(&tasklist_lock);
3784}
3785EXPORT_SYMBOL_GPL(debug_show_all_locks);
3786
3787/*
3788 * Careful: only use this function if you are sure that
3789 * the task cannot run in parallel!
3790 */
3791void debug_show_held_locks(struct task_struct *task)
3792{
3793        if (unlikely(!debug_locks)) {
3794                printk("INFO: lockdep is turned off.\n");
3795                return;
3796        }
3797        lockdep_print_held_locks(task);
3798}
3799EXPORT_SYMBOL_GPL(debug_show_held_locks);
3800
3801void lockdep_sys_exit(void)
3802{
3803        struct task_struct *curr = current;
3804
3805        if (unlikely(curr->lockdep_depth)) {
3806                if (!debug_locks_off())
3807                        return;
3808                printk("\n================================================\n");
3809                printk(  "[ BUG: lock held when returning to user space! ]\n");
3810                printk(  "------------------------------------------------\n");
3811                printk("%s/%d is leaving the kernel with locks still held!\n",
3812                                curr->comm, curr->pid);
3813                lockdep_print_held_locks(curr);
3814        }
3815}
3816
3817void lockdep_rcu_dereference(const char *file, const int line)
3818{
3819        struct task_struct *curr = current;
3820
3821#ifndef CONFIG_PROVE_RCU_REPEATEDLY
3822        if (!debug_locks_off())
3823                return;
3824#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
3825        /* Note: the following can be executed concurrently, so be careful. */
3826        printk("\n===================================================\n");
3827        printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3828        printk(  "---------------------------------------------------\n");
3829        printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3830                        file, line);
3831        printk("\nother info that might help us debug this:\n\n");
3832        printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3833        lockdep_print_held_locks(curr);
3834        printk("\nstack backtrace:\n");
3835        dump_stack();
3836}
3837EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);
3838