linux/kernel/locking/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
  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#include <linux/kmemcheck.h>
  48
  49#include <asm/sections.h>
  50
  51#include "lockdep_internals.h"
  52
  53#define CREATE_TRACE_POINTS
  54#include <trace/events/lock.h>
  55
  56#ifdef CONFIG_PROVE_LOCKING
  57int prove_locking = 1;
  58module_param(prove_locking, int, 0644);
  59#else
  60#define prove_locking 0
  61#endif
  62
  63#ifdef CONFIG_LOCK_STAT
  64int lock_stat = 1;
  65module_param(lock_stat, int, 0644);
  66#else
  67#define lock_stat 0
  68#endif
  69
  70/*
  71 * lockdep_lock: protects the lockdep graph, the hashes and the
  72 *               class/list/hash allocators.
  73 *
  74 * This is one of the rare exceptions where it's justified
  75 * to use a raw spinlock - we really dont want the spinlock
  76 * code to recurse back into the lockdep code...
  77 */
  78static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  79
  80static int graph_lock(void)
  81{
  82        arch_spin_lock(&lockdep_lock);
  83        /*
  84         * Make sure that if another CPU detected a bug while
  85         * walking the graph we dont change it (while the other
  86         * CPU is busy printing out stuff with the graph lock
  87         * dropped already)
  88         */
  89        if (!debug_locks) {
  90                arch_spin_unlock(&lockdep_lock);
  91                return 0;
  92        }
  93        /* prevent any recursions within lockdep from causing deadlocks */
  94        current->lockdep_recursion++;
  95        return 1;
  96}
  97
  98static inline int graph_unlock(void)
  99{
 100        if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
 101                /*
 102                 * The lockdep graph lock isn't locked while we expect it to
 103                 * be, we're confused now, bye!
 104                 */
 105                return DEBUG_LOCKS_WARN_ON(1);
 106        }
 107
 108        current->lockdep_recursion--;
 109        arch_spin_unlock(&lockdep_lock);
 110        return 0;
 111}
 112
 113/*
 114 * Turn lock debugging off and return with 0 if it was off already,
 115 * and also release the graph lock:
 116 */
 117static inline int debug_locks_off_graph_unlock(void)
 118{
 119        int ret = debug_locks_off();
 120
 121        arch_spin_unlock(&lockdep_lock);
 122
 123        return ret;
 124}
 125
 126unsigned long nr_list_entries;
 127static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
 128
 129/*
 130 * All data structures here are protected by the global debug_lock.
 131 *
 132 * Mutex key structs only get allocated, once during bootup, and never
 133 * get freed - this significantly simplifies the debugging code.
 134 */
 135unsigned long nr_lock_classes;
 136static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
 137
 138static inline struct lock_class *hlock_class(struct held_lock *hlock)
 139{
 140        if (!hlock->class_idx) {
 141                /*
 142                 * Someone passed in garbage, we give up.
 143                 */
 144                DEBUG_LOCKS_WARN_ON(1);
 145                return NULL;
 146        }
 147        return lock_classes + hlock->class_idx - 1;
 148}
 149
 150#ifdef CONFIG_LOCK_STAT
 151static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
 152
 153static inline u64 lockstat_clock(void)
 154{
 155        return local_clock();
 156}
 157
 158static int lock_point(unsigned long points[], unsigned long ip)
 159{
 160        int i;
 161
 162        for (i = 0; i < LOCKSTAT_POINTS; i++) {
 163                if (points[i] == 0) {
 164                        points[i] = ip;
 165                        break;
 166                }
 167                if (points[i] == ip)
 168                        break;
 169        }
 170
 171        return i;
 172}
 173
 174static void lock_time_inc(struct lock_time *lt, u64 time)
 175{
 176        if (time > lt->max)
 177                lt->max = time;
 178
 179        if (time < lt->min || !lt->nr)
 180                lt->min = time;
 181
 182        lt->total += time;
 183        lt->nr++;
 184}
 185
 186static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
 187{
 188        if (!src->nr)
 189                return;
 190
 191        if (src->max > dst->max)
 192                dst->max = src->max;
 193
 194        if (src->min < dst->min || !dst->nr)
 195                dst->min = src->min;
 196
 197        dst->total += src->total;
 198        dst->nr += src->nr;
 199}
 200
 201struct lock_class_stats lock_stats(struct lock_class *class)
 202{
 203        struct lock_class_stats stats;
 204        int cpu, i;
 205
 206        memset(&stats, 0, sizeof(struct lock_class_stats));
 207        for_each_possible_cpu(cpu) {
 208                struct lock_class_stats *pcs =
 209                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
 210
 211                for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
 212                        stats.contention_point[i] += pcs->contention_point[i];
 213
 214                for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
 215                        stats.contending_point[i] += pcs->contending_point[i];
 216
 217                lock_time_add(&pcs->read_waittime, &stats.read_waittime);
 218                lock_time_add(&pcs->write_waittime, &stats.write_waittime);
 219
 220                lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
 221                lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
 222
 223                for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
 224                        stats.bounces[i] += pcs->bounces[i];
 225        }
 226
 227        return stats;
 228}
 229
 230void clear_lock_stats(struct lock_class *class)
 231{
 232        int cpu;
 233
 234        for_each_possible_cpu(cpu) {
 235                struct lock_class_stats *cpu_stats =
 236                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
 237
 238                memset(cpu_stats, 0, sizeof(struct lock_class_stats));
 239        }
 240        memset(class->contention_point, 0, sizeof(class->contention_point));
 241        memset(class->contending_point, 0, sizeof(class->contending_point));
 242}
 243
 244static struct lock_class_stats *get_lock_stats(struct lock_class *class)
 245{
 246        return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
 247}
 248
 249static void put_lock_stats(struct lock_class_stats *stats)
 250{
 251        put_cpu_var(cpu_lock_stats);
 252}
 253
 254static void lock_release_holdtime(struct held_lock *hlock)
 255{
 256        struct lock_class_stats *stats;
 257        u64 holdtime;
 258
 259        if (!lock_stat)
 260                return;
 261
 262        holdtime = lockstat_clock() - hlock->holdtime_stamp;
 263
 264        stats = get_lock_stats(hlock_class(hlock));
 265        if (hlock->read)
 266                lock_time_inc(&stats->read_holdtime, holdtime);
 267        else
 268                lock_time_inc(&stats->write_holdtime, holdtime);
 269        put_lock_stats(stats);
 270}
 271#else
 272static inline void lock_release_holdtime(struct held_lock *hlock)
 273{
 274}
 275#endif
 276
 277/*
 278 * We keep a global list of all lock classes. The list only grows,
 279 * never shrinks. The list is only accessed with the lockdep
 280 * spinlock lock held.
 281 */
 282LIST_HEAD(all_lock_classes);
 283
 284/*
 285 * The lockdep classes are in a hash-table as well, for fast lookup:
 286 */
 287#define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
 288#define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
 289#define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
 290#define classhashentry(key)     (classhash_table + __classhashfn((key)))
 291
 292static struct hlist_head classhash_table[CLASSHASH_SIZE];
 293
 294/*
 295 * We put the lock dependency chains into a hash-table as well, to cache
 296 * their existence:
 297 */
 298#define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
 299#define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
 300#define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
 301#define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
 302
 303static struct hlist_head chainhash_table[CHAINHASH_SIZE];
 304
 305/*
 306 * The hash key of the lock dependency chains is a hash itself too:
 307 * it's a hash of all locks taken up to that lock, including that lock.
 308 * It's a 64-bit hash, because it's important for the keys to be
 309 * unique.
 310 */
 311#define iterate_chain_key(key1, key2) \
 312        (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
 313        ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
 314        (key2))
 315
 316void lockdep_off(void)
 317{
 318        current->lockdep_recursion++;
 319}
 320EXPORT_SYMBOL(lockdep_off);
 321
 322void lockdep_on(void)
 323{
 324        current->lockdep_recursion--;
 325}
 326EXPORT_SYMBOL(lockdep_on);
 327
 328/*
 329 * Debugging switches:
 330 */
 331
 332#define VERBOSE                 0
 333#define VERY_VERBOSE            0
 334
 335#if VERBOSE
 336# define HARDIRQ_VERBOSE        1
 337# define SOFTIRQ_VERBOSE        1
 338# define RECLAIM_VERBOSE        1
 339#else
 340# define HARDIRQ_VERBOSE        0
 341# define SOFTIRQ_VERBOSE        0
 342# define RECLAIM_VERBOSE        0
 343#endif
 344
 345#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
 346/*
 347 * Quick filtering for interesting events:
 348 */
 349static int class_filter(struct lock_class *class)
 350{
 351#if 0
 352        /* Example */
 353        if (class->name_version == 1 &&
 354                        !strcmp(class->name, "lockname"))
 355                return 1;
 356        if (class->name_version == 1 &&
 357                        !strcmp(class->name, "&struct->lockfield"))
 358                return 1;
 359#endif
 360        /* Filter everything else. 1 would be to allow everything else */
 361        return 0;
 362}
 363#endif
 364
 365static int verbose(struct lock_class *class)
 366{
 367#if VERBOSE
 368        return class_filter(class);
 369#endif
 370        return 0;
 371}
 372
 373/*
 374 * Stack-trace: tightly packed array of stack backtrace
 375 * addresses. Protected by the graph_lock.
 376 */
 377unsigned long nr_stack_trace_entries;
 378static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
 379
 380static void print_lockdep_off(const char *bug_msg)
 381{
 382        printk(KERN_DEBUG "%s\n", bug_msg);
 383        printk(KERN_DEBUG "turning off the locking correctness validator.\n");
 384#ifdef CONFIG_LOCK_STAT
 385        printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
 386#endif
 387}
 388
 389static int save_trace(struct stack_trace *trace)
 390{
 391        trace->nr_entries = 0;
 392        trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
 393        trace->entries = stack_trace + nr_stack_trace_entries;
 394
 395        trace->skip = 3;
 396
 397        save_stack_trace(trace);
 398
 399        /*
 400         * Some daft arches put -1 at the end to indicate its a full trace.
 401         *
 402         * <rant> this is buggy anyway, since it takes a whole extra entry so a
 403         * complete trace that maxes out the entries provided will be reported
 404         * as incomplete, friggin useless </rant>
 405         */
 406        if (trace->nr_entries != 0 &&
 407            trace->entries[trace->nr_entries-1] == ULONG_MAX)
 408                trace->nr_entries--;
 409
 410        trace->max_entries = trace->nr_entries;
 411
 412        nr_stack_trace_entries += trace->nr_entries;
 413
 414        if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
 415                if (!debug_locks_off_graph_unlock())
 416                        return 0;
 417
 418                print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
 419                dump_stack();
 420
 421                return 0;
 422        }
 423
 424        return 1;
 425}
 426
 427unsigned int nr_hardirq_chains;
 428unsigned int nr_softirq_chains;
 429unsigned int nr_process_chains;
 430unsigned int max_lockdep_depth;
 431
 432#ifdef CONFIG_DEBUG_LOCKDEP
 433/*
 434 * Various lockdep statistics:
 435 */
 436DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
 437#endif
 438
 439/*
 440 * Locking printouts:
 441 */
 442
 443#define __USAGE(__STATE)                                                \
 444        [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
 445        [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
 446        [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
 447        [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
 448
 449static const char *usage_str[] =
 450{
 451#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
 452#include "lockdep_states.h"
 453#undef LOCKDEP_STATE
 454        [LOCK_USED] = "INITIAL USE",
 455};
 456
 457const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
 458{
 459        return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
 460}
 461
 462static inline unsigned long lock_flag(enum lock_usage_bit bit)
 463{
 464        return 1UL << bit;
 465}
 466
 467static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
 468{
 469        char c = '.';
 470
 471        if (class->usage_mask & lock_flag(bit + 2))
 472                c = '+';
 473        if (class->usage_mask & lock_flag(bit)) {
 474                c = '-';
 475                if (class->usage_mask & lock_flag(bit + 2))
 476                        c = '?';
 477        }
 478
 479        return c;
 480}
 481
 482void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
 483{
 484        int i = 0;
 485
 486#define LOCKDEP_STATE(__STATE)                                          \
 487        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
 488        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
 489#include "lockdep_states.h"
 490#undef LOCKDEP_STATE
 491
 492        usage[i] = '\0';
 493}
 494
 495static void __print_lock_name(struct lock_class *class)
 496{
 497        char str[KSYM_NAME_LEN];
 498        const char *name;
 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}
 512
 513static void print_lock_name(struct lock_class *class)
 514{
 515        char usage[LOCK_USAGE_CHARS];
 516
 517        get_usage_chars(class, usage);
 518
 519        printk(" (");
 520        __print_lock_name(class);
 521        printk("){%s}", usage);
 522}
 523
 524static void print_lockdep_cache(struct lockdep_map *lock)
 525{
 526        const char *name;
 527        char str[KSYM_NAME_LEN];
 528
 529        name = lock->name;
 530        if (!name)
 531                name = __get_key_name(lock->key->subkeys, str);
 532
 533        printk("%s", name);
 534}
 535
 536static void print_lock(struct held_lock *hlock)
 537{
 538        /*
 539         * We can be called locklessly through debug_show_all_locks() so be
 540         * extra careful, the hlock might have been released and cleared.
 541         */
 542        unsigned int class_idx = hlock->class_idx;
 543
 544        /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
 545        barrier();
 546
 547        if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
 548                printk("<RELEASED>\n");
 549                return;
 550        }
 551
 552        print_lock_name(lock_classes + class_idx - 1);
 553        printk(", at: ");
 554        print_ip_sym(hlock->acquire_ip);
 555}
 556
 557static void lockdep_print_held_locks(struct task_struct *curr)
 558{
 559        int i, depth = curr->lockdep_depth;
 560
 561        if (!depth) {
 562                printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
 563                return;
 564        }
 565        printk("%d lock%s held by %s/%d:\n",
 566                depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
 567
 568        for (i = 0; i < depth; i++) {
 569                printk(" #%d: ", i);
 570                print_lock(curr->held_locks + i);
 571        }
 572}
 573
 574static void print_kernel_ident(void)
 575{
 576        printk("%s %.*s %s\n", init_utsname()->release,
 577                (int)strcspn(init_utsname()->version, " "),
 578                init_utsname()->version,
 579                print_tainted());
 580}
 581
 582static int very_verbose(struct lock_class *class)
 583{
 584#if VERY_VERBOSE
 585        return class_filter(class);
 586#endif
 587        return 0;
 588}
 589
 590/*
 591 * Is this the address of a static object:
 592 */
 593#ifdef __KERNEL__
 594static int static_obj(void *obj)
 595{
 596        unsigned long start = (unsigned long) &_stext,
 597                      end   = (unsigned long) &_end,
 598                      addr  = (unsigned long) obj;
 599
 600        /*
 601         * static variable?
 602         */
 603        if ((addr >= start) && (addr < end))
 604                return 1;
 605
 606        if (arch_is_kernel_data(addr))
 607                return 1;
 608
 609        /*
 610         * in-kernel percpu var?
 611         */
 612        if (is_kernel_percpu_address(addr))
 613                return 1;
 614
 615        /*
 616         * module static or percpu var?
 617         */
 618        return is_module_address(addr) || is_module_percpu_address(addr);
 619}
 620#endif
 621
 622/*
 623 * To make lock name printouts unique, we calculate a unique
 624 * class->name_version generation counter:
 625 */
 626static int count_matching_names(struct lock_class *new_class)
 627{
 628        struct lock_class *class;
 629        int count = 0;
 630
 631        if (!new_class->name)
 632                return 0;
 633
 634        list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
 635                if (new_class->key - new_class->subclass == class->key)
 636                        return class->name_version;
 637                if (class->name && !strcmp(class->name, new_class->name))
 638                        count = max(count, class->name_version);
 639        }
 640
 641        return count + 1;
 642}
 643
 644/*
 645 * Register a lock's class in the hash-table, if the class is not present
 646 * yet. Otherwise we look it up. We cache the result in the lock object
 647 * itself, so actual lookup of the hash should be once per lock object.
 648 */
 649static inline struct lock_class *
 650look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
 651{
 652        struct lockdep_subclass_key *key;
 653        struct hlist_head *hash_head;
 654        struct lock_class *class;
 655
 656        if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
 657                debug_locks_off();
 658                printk(KERN_ERR
 659                        "BUG: looking up invalid subclass: %u\n", subclass);
 660                printk(KERN_ERR
 661                        "turning off the locking correctness validator.\n");
 662                dump_stack();
 663                return NULL;
 664        }
 665
 666        /*
 667         * Static locks do not have their class-keys yet - for them the key
 668         * is the lock object itself:
 669         */
 670        if (unlikely(!lock->key))
 671                lock->key = (void *)lock;
 672
 673        /*
 674         * NOTE: the class-key must be unique. For dynamic locks, a static
 675         * lock_class_key variable is passed in through the mutex_init()
 676         * (or spin_lock_init()) call - which acts as the key. For static
 677         * locks we use the lock object itself as the key.
 678         */
 679        BUILD_BUG_ON(sizeof(struct lock_class_key) >
 680                        sizeof(struct lockdep_map));
 681
 682        key = lock->key->subkeys + subclass;
 683
 684        hash_head = classhashentry(key);
 685
 686        /*
 687         * We do an RCU walk of the hash, see lockdep_free_key_range().
 688         */
 689        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
 690                return NULL;
 691
 692        hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
 693                if (class->key == key) {
 694                        /*
 695                         * Huh! same key, different name? Did someone trample
 696                         * on some memory? We're most confused.
 697                         */
 698                        WARN_ON_ONCE(class->name != lock->name);
 699                        return class;
 700                }
 701        }
 702
 703        return NULL;
 704}
 705
 706/*
 707 * Register a lock's class in the hash-table, if the class is not present
 708 * yet. Otherwise we look it up. We cache the result in the lock object
 709 * itself, so actual lookup of the hash should be once per lock object.
 710 */
 711static inline struct lock_class *
 712register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 713{
 714        struct lockdep_subclass_key *key;
 715        struct hlist_head *hash_head;
 716        struct lock_class *class;
 717
 718        DEBUG_LOCKS_WARN_ON(!irqs_disabled());
 719
 720        class = look_up_lock_class(lock, subclass);
 721        if (likely(class))
 722                goto out_set_class_cache;
 723
 724        /*
 725         * Debug-check: all keys must be persistent!
 726         */
 727        if (!static_obj(lock->key)) {
 728                debug_locks_off();
 729                printk("INFO: trying to register non-static key.\n");
 730                printk("the code is fine but needs lockdep annotation.\n");
 731                printk("turning off the locking correctness validator.\n");
 732                dump_stack();
 733
 734                return NULL;
 735        }
 736
 737        key = lock->key->subkeys + subclass;
 738        hash_head = classhashentry(key);
 739
 740        if (!graph_lock()) {
 741                return NULL;
 742        }
 743        /*
 744         * We have to do the hash-walk again, to avoid races
 745         * with another CPU:
 746         */
 747        hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
 748                if (class->key == key)
 749                        goto out_unlock_set;
 750        }
 751
 752        /*
 753         * Allocate a new key from the static array, and add it to
 754         * the hash:
 755         */
 756        if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
 757                if (!debug_locks_off_graph_unlock()) {
 758                        return NULL;
 759                }
 760
 761                print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
 762                dump_stack();
 763                return NULL;
 764        }
 765        class = lock_classes + nr_lock_classes++;
 766        debug_atomic_inc(nr_unused_locks);
 767        class->key = key;
 768        class->name = lock->name;
 769        class->subclass = subclass;
 770        INIT_LIST_HEAD(&class->lock_entry);
 771        INIT_LIST_HEAD(&class->locks_before);
 772        INIT_LIST_HEAD(&class->locks_after);
 773        class->name_version = count_matching_names(class);
 774        /*
 775         * We use RCU's safe list-add method to make
 776         * parallel walking of the hash-list safe:
 777         */
 778        hlist_add_head_rcu(&class->hash_entry, hash_head);
 779        /*
 780         * Add it to the global list of classes:
 781         */
 782        list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
 783
 784        if (verbose(class)) {
 785                graph_unlock();
 786
 787                printk("\nnew class %p: %s", class->key, class->name);
 788                if (class->name_version > 1)
 789                        printk("#%d", class->name_version);
 790                printk("\n");
 791                dump_stack();
 792
 793                if (!graph_lock()) {
 794                        return NULL;
 795                }
 796        }
 797out_unlock_set:
 798        graph_unlock();
 799
 800out_set_class_cache:
 801        if (!subclass || force)
 802                lock->class_cache[0] = class;
 803        else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
 804                lock->class_cache[subclass] = class;
 805
 806        /*
 807         * Hash collision, did we smoke some? We found a class with a matching
 808         * hash but the subclass -- which is hashed in -- didn't match.
 809         */
 810        if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
 811                return NULL;
 812
 813        return class;
 814}
 815
 816#ifdef CONFIG_PROVE_LOCKING
 817/*
 818 * Allocate a lockdep entry. (assumes the graph_lock held, returns
 819 * with NULL on failure)
 820 */
 821static struct lock_list *alloc_list_entry(void)
 822{
 823        if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
 824                if (!debug_locks_off_graph_unlock())
 825                        return NULL;
 826
 827                print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
 828                dump_stack();
 829                return NULL;
 830        }
 831        return list_entries + nr_list_entries++;
 832}
 833
 834/*
 835 * Add a new dependency to the head of the list:
 836 */
 837static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
 838                            struct list_head *head, unsigned long ip,
 839                            int distance, struct stack_trace *trace)
 840{
 841        struct lock_list *entry;
 842        /*
 843         * Lock not present yet - get a new dependency struct and
 844         * add it to the list:
 845         */
 846        entry = alloc_list_entry();
 847        if (!entry)
 848                return 0;
 849
 850        entry->class = this;
 851        entry->distance = distance;
 852        entry->trace = *trace;
 853        /*
 854         * Both allocation and removal are done under the graph lock; but
 855         * iteration is under RCU-sched; see look_up_lock_class() and
 856         * lockdep_free_key_range().
 857         */
 858        list_add_tail_rcu(&entry->entry, head);
 859
 860        return 1;
 861}
 862
 863/*
 864 * For good efficiency of modular, we use power of 2
 865 */
 866#define MAX_CIRCULAR_QUEUE_SIZE         4096UL
 867#define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
 868
 869/*
 870 * The circular_queue and helpers is used to implement the
 871 * breadth-first search(BFS)algorithem, by which we can build
 872 * the shortest path from the next lock to be acquired to the
 873 * previous held lock if there is a circular between them.
 874 */
 875struct circular_queue {
 876        unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
 877        unsigned int  front, rear;
 878};
 879
 880static struct circular_queue lock_cq;
 881
 882unsigned int max_bfs_queue_depth;
 883
 884static unsigned int lockdep_dependency_gen_id;
 885
 886static inline void __cq_init(struct circular_queue *cq)
 887{
 888        cq->front = cq->rear = 0;
 889        lockdep_dependency_gen_id++;
 890}
 891
 892static inline int __cq_empty(struct circular_queue *cq)
 893{
 894        return (cq->front == cq->rear);
 895}
 896
 897static inline int __cq_full(struct circular_queue *cq)
 898{
 899        return ((cq->rear + 1) & CQ_MASK) == cq->front;
 900}
 901
 902static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
 903{
 904        if (__cq_full(cq))
 905                return -1;
 906
 907        cq->element[cq->rear] = elem;
 908        cq->rear = (cq->rear + 1) & CQ_MASK;
 909        return 0;
 910}
 911
 912static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
 913{
 914        if (__cq_empty(cq))
 915                return -1;
 916
 917        *elem = cq->element[cq->front];
 918        cq->front = (cq->front + 1) & CQ_MASK;
 919        return 0;
 920}
 921
 922static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
 923{
 924        return (cq->rear - cq->front) & CQ_MASK;
 925}
 926
 927static inline void mark_lock_accessed(struct lock_list *lock,
 928                                        struct lock_list *parent)
 929{
 930        unsigned long nr;
 931
 932        nr = lock - list_entries;
 933        WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
 934        lock->parent = parent;
 935        lock->class->dep_gen_id = lockdep_dependency_gen_id;
 936}
 937
 938static inline unsigned long lock_accessed(struct lock_list *lock)
 939{
 940        unsigned long nr;
 941
 942        nr = lock - list_entries;
 943        WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
 944        return lock->class->dep_gen_id == lockdep_dependency_gen_id;
 945}
 946
 947static inline struct lock_list *get_lock_parent(struct lock_list *child)
 948{
 949        return child->parent;
 950}
 951
 952static inline int get_lock_depth(struct lock_list *child)
 953{
 954        int depth = 0;
 955        struct lock_list *parent;
 956
 957        while ((parent = get_lock_parent(child))) {
 958                child = parent;
 959                depth++;
 960        }
 961        return depth;
 962}
 963
 964static int __bfs(struct lock_list *source_entry,
 965                 void *data,
 966                 int (*match)(struct lock_list *entry, void *data),
 967                 struct lock_list **target_entry,
 968                 int forward)
 969{
 970        struct lock_list *entry;
 971        struct list_head *head;
 972        struct circular_queue *cq = &lock_cq;
 973        int ret = 1;
 974
 975        if (match(source_entry, data)) {
 976                *target_entry = source_entry;
 977                ret = 0;
 978                goto exit;
 979        }
 980
 981        if (forward)
 982                head = &source_entry->class->locks_after;
 983        else
 984                head = &source_entry->class->locks_before;
 985
 986        if (list_empty(head))
 987                goto exit;
 988
 989        __cq_init(cq);
 990        __cq_enqueue(cq, (unsigned long)source_entry);
 991
 992        while (!__cq_empty(cq)) {
 993                struct lock_list *lock;
 994
 995                __cq_dequeue(cq, (unsigned long *)&lock);
 996
 997                if (!lock->class) {
 998                        ret = -2;
 999                        goto exit;
1000                }
1001
1002                if (forward)
1003                        head = &lock->class->locks_after;
1004                else
1005                        head = &lock->class->locks_before;
1006
1007                DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1008
1009                list_for_each_entry_rcu(entry, head, entry) {
1010                        if (!lock_accessed(entry)) {
1011                                unsigned int cq_depth;
1012                                mark_lock_accessed(entry, lock);
1013                                if (match(entry, data)) {
1014                                        *target_entry = entry;
1015                                        ret = 0;
1016                                        goto exit;
1017                                }
1018
1019                                if (__cq_enqueue(cq, (unsigned long)entry)) {
1020                                        ret = -1;
1021                                        goto exit;
1022                                }
1023                                cq_depth = __cq_get_elem_count(cq);
1024                                if (max_bfs_queue_depth < cq_depth)
1025                                        max_bfs_queue_depth = cq_depth;
1026                        }
1027                }
1028        }
1029exit:
1030        return ret;
1031}
1032
1033static inline int __bfs_forwards(struct lock_list *src_entry,
1034                        void *data,
1035                        int (*match)(struct lock_list *entry, void *data),
1036                        struct lock_list **target_entry)
1037{
1038        return __bfs(src_entry, data, match, target_entry, 1);
1039
1040}
1041
1042static inline int __bfs_backwards(struct lock_list *src_entry,
1043                        void *data,
1044                        int (*match)(struct lock_list *entry, void *data),
1045                        struct lock_list **target_entry)
1046{
1047        return __bfs(src_entry, data, match, target_entry, 0);
1048
1049}
1050
1051/*
1052 * Recursive, forwards-direction lock-dependency checking, used for
1053 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1054 * checking.
1055 */
1056
1057/*
1058 * Print a dependency chain entry (this is only done when a deadlock
1059 * has been detected):
1060 */
1061static noinline int
1062print_circular_bug_entry(struct lock_list *target, int depth)
1063{
1064        if (debug_locks_silent)
1065                return 0;
1066        printk("\n-> #%u", depth);
1067        print_lock_name(target->class);
1068        printk(":\n");
1069        print_stack_trace(&target->trace, 6);
1070
1071        return 0;
1072}
1073
1074static void
1075print_circular_lock_scenario(struct held_lock *src,
1076                             struct held_lock *tgt,
1077                             struct lock_list *prt)
1078{
1079        struct lock_class *source = hlock_class(src);
1080        struct lock_class *target = hlock_class(tgt);
1081        struct lock_class *parent = prt->class;
1082
1083        /*
1084         * A direct locking problem where unsafe_class lock is taken
1085         * directly by safe_class lock, then all we need to show
1086         * is the deadlock scenario, as it is obvious that the
1087         * unsafe lock is taken under the safe lock.
1088         *
1089         * But if there is a chain instead, where the safe lock takes
1090         * an intermediate lock (middle_class) where this lock is
1091         * not the same as the safe lock, then the lock chain is
1092         * used to describe the problem. Otherwise we would need
1093         * to show a different CPU case for each link in the chain
1094         * from the safe_class lock to the unsafe_class lock.
1095         */
1096        if (parent != source) {
1097                printk("Chain exists of:\n  ");
1098                __print_lock_name(source);
1099                printk(" --> ");
1100                __print_lock_name(parent);
1101                printk(" --> ");
1102                __print_lock_name(target);
1103                printk("\n\n");
1104        }
1105
1106        printk(" Possible unsafe locking scenario:\n\n");
1107        printk("       CPU0                    CPU1\n");
1108        printk("       ----                    ----\n");
1109        printk("  lock(");
1110        __print_lock_name(target);
1111        printk(");\n");
1112        printk("                               lock(");
1113        __print_lock_name(parent);
1114        printk(");\n");
1115        printk("                               lock(");
1116        __print_lock_name(target);
1117        printk(");\n");
1118        printk("  lock(");
1119        __print_lock_name(source);
1120        printk(");\n");
1121        printk("\n *** DEADLOCK ***\n\n");
1122}
1123
1124/*
1125 * When a circular dependency is detected, print the
1126 * header first:
1127 */
1128static noinline int
1129print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1130                        struct held_lock *check_src,
1131                        struct held_lock *check_tgt)
1132{
1133        struct task_struct *curr = current;
1134
1135        if (debug_locks_silent)
1136                return 0;
1137
1138        printk("\n");
1139        printk("======================================================\n");
1140        printk("[ INFO: possible circular locking dependency detected ]\n");
1141        print_kernel_ident();
1142        printk("-------------------------------------------------------\n");
1143        printk("%s/%d is trying to acquire lock:\n",
1144                curr->comm, task_pid_nr(curr));
1145        print_lock(check_src);
1146        printk("\nbut task is already holding lock:\n");
1147        print_lock(check_tgt);
1148        printk("\nwhich lock already depends on the new lock.\n\n");
1149        printk("\nthe existing dependency chain (in reverse order) is:\n");
1150
1151        print_circular_bug_entry(entry, depth);
1152
1153        return 0;
1154}
1155
1156static inline int class_equal(struct lock_list *entry, void *data)
1157{
1158        return entry->class == data;
1159}
1160
1161static noinline int print_circular_bug(struct lock_list *this,
1162                                struct lock_list *target,
1163                                struct held_lock *check_src,
1164                                struct held_lock *check_tgt)
1165{
1166        struct task_struct *curr = current;
1167        struct lock_list *parent;
1168        struct lock_list *first_parent;
1169        int depth;
1170
1171        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1172                return 0;
1173
1174        if (!save_trace(&this->trace))
1175                return 0;
1176
1177        depth = get_lock_depth(target);
1178
1179        print_circular_bug_header(target, depth, check_src, check_tgt);
1180
1181        parent = get_lock_parent(target);
1182        first_parent = parent;
1183
1184        while (parent) {
1185                print_circular_bug_entry(parent, --depth);
1186                parent = get_lock_parent(parent);
1187        }
1188
1189        printk("\nother info that might help us debug this:\n\n");
1190        print_circular_lock_scenario(check_src, check_tgt,
1191                                     first_parent);
1192
1193        lockdep_print_held_locks(curr);
1194
1195        printk("\nstack backtrace:\n");
1196        dump_stack();
1197
1198        return 0;
1199}
1200
1201static noinline int print_bfs_bug(int ret)
1202{
1203        if (!debug_locks_off_graph_unlock())
1204                return 0;
1205
1206        /*
1207         * Breadth-first-search failed, graph got corrupted?
1208         */
1209        WARN(1, "lockdep bfs error:%d\n", ret);
1210
1211        return 0;
1212}
1213
1214static int noop_count(struct lock_list *entry, void *data)
1215{
1216        (*(unsigned long *)data)++;
1217        return 0;
1218}
1219
1220static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1221{
1222        unsigned long  count = 0;
1223        struct lock_list *uninitialized_var(target_entry);
1224
1225        __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1226
1227        return count;
1228}
1229unsigned long lockdep_count_forward_deps(struct lock_class *class)
1230{
1231        unsigned long ret, flags;
1232        struct lock_list this;
1233
1234        this.parent = NULL;
1235        this.class = class;
1236
1237        local_irq_save(flags);
1238        arch_spin_lock(&lockdep_lock);
1239        ret = __lockdep_count_forward_deps(&this);
1240        arch_spin_unlock(&lockdep_lock);
1241        local_irq_restore(flags);
1242
1243        return ret;
1244}
1245
1246static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1247{
1248        unsigned long  count = 0;
1249        struct lock_list *uninitialized_var(target_entry);
1250
1251        __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1252
1253        return count;
1254}
1255
1256unsigned long lockdep_count_backward_deps(struct lock_class *class)
1257{
1258        unsigned long ret, flags;
1259        struct lock_list this;
1260
1261        this.parent = NULL;
1262        this.class = class;
1263
1264        local_irq_save(flags);
1265        arch_spin_lock(&lockdep_lock);
1266        ret = __lockdep_count_backward_deps(&this);
1267        arch_spin_unlock(&lockdep_lock);
1268        local_irq_restore(flags);
1269
1270        return ret;
1271}
1272
1273/*
1274 * Prove that the dependency graph starting at <entry> can not
1275 * lead to <target>. Print an error and return 0 if it does.
1276 */
1277static noinline int
1278check_noncircular(struct lock_list *root, struct lock_class *target,
1279                struct lock_list **target_entry)
1280{
1281        int result;
1282
1283        debug_atomic_inc(nr_cyclic_checks);
1284
1285        result = __bfs_forwards(root, target, class_equal, target_entry);
1286
1287        return result;
1288}
1289
1290#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1291/*
1292 * Forwards and backwards subgraph searching, for the purposes of
1293 * proving that two subgraphs can be connected by a new dependency
1294 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1295 */
1296
1297static inline int usage_match(struct lock_list *entry, void *bit)
1298{
1299        return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1300}
1301
1302
1303
1304/*
1305 * Find a node in the forwards-direction dependency sub-graph starting
1306 * at @root->class that matches @bit.
1307 *
1308 * Return 0 if such a node exists in the subgraph, and put that node
1309 * into *@target_entry.
1310 *
1311 * Return 1 otherwise and keep *@target_entry unchanged.
1312 * Return <0 on error.
1313 */
1314static int
1315find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1316                        struct lock_list **target_entry)
1317{
1318        int result;
1319
1320        debug_atomic_inc(nr_find_usage_forwards_checks);
1321
1322        result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1323
1324        return result;
1325}
1326
1327/*
1328 * Find a node in the backwards-direction dependency sub-graph starting
1329 * at @root->class that matches @bit.
1330 *
1331 * Return 0 if such a node exists in the subgraph, and put that node
1332 * into *@target_entry.
1333 *
1334 * Return 1 otherwise and keep *@target_entry unchanged.
1335 * Return <0 on error.
1336 */
1337static int
1338find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1339                        struct lock_list **target_entry)
1340{
1341        int result;
1342
1343        debug_atomic_inc(nr_find_usage_backwards_checks);
1344
1345        result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1346
1347        return result;
1348}
1349
1350static void print_lock_class_header(struct lock_class *class, int depth)
1351{
1352        int bit;
1353
1354        printk("%*s->", depth, "");
1355        print_lock_name(class);
1356        printk(" ops: %lu", class->ops);
1357        printk(" {\n");
1358
1359        for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1360                if (class->usage_mask & (1 << bit)) {
1361                        int len = depth;
1362
1363                        len += printk("%*s   %s", depth, "", usage_str[bit]);
1364                        len += printk(" at:\n");
1365                        print_stack_trace(class->usage_traces + bit, len);
1366                }
1367        }
1368        printk("%*s }\n", depth, "");
1369
1370        printk("%*s ... key      at: ",depth,"");
1371        print_ip_sym((unsigned long)class->key);
1372}
1373
1374/*
1375 * printk the shortest lock dependencies from @start to @end in reverse order:
1376 */
1377static void __used
1378print_shortest_lock_dependencies(struct lock_list *leaf,
1379                                struct lock_list *root)
1380{
1381        struct lock_list *entry = leaf;
1382        int depth;
1383
1384        /*compute depth from generated tree by BFS*/
1385        depth = get_lock_depth(leaf);
1386
1387        do {
1388                print_lock_class_header(entry->class, depth);
1389                printk("%*s ... acquired at:\n", depth, "");
1390                print_stack_trace(&entry->trace, 2);
1391                printk("\n");
1392
1393                if (depth == 0 && (entry != root)) {
1394                        printk("lockdep:%s bad path found in chain graph\n", __func__);
1395                        break;
1396                }
1397
1398                entry = get_lock_parent(entry);
1399                depth--;
1400        } while (entry && (depth >= 0));
1401
1402        return;
1403}
1404
1405static void
1406print_irq_lock_scenario(struct lock_list *safe_entry,
1407                        struct lock_list *unsafe_entry,
1408                        struct lock_class *prev_class,
1409                        struct lock_class *next_class)
1410{
1411        struct lock_class *safe_class = safe_entry->class;
1412        struct lock_class *unsafe_class = unsafe_entry->class;
1413        struct lock_class *middle_class = prev_class;
1414
1415        if (middle_class == safe_class)
1416                middle_class = next_class;
1417
1418        /*
1419         * A direct locking problem where unsafe_class lock is taken
1420         * directly by safe_class lock, then all we need to show
1421         * is the deadlock scenario, as it is obvious that the
1422         * unsafe lock is taken under the safe lock.
1423         *
1424         * But if there is a chain instead, where the safe lock takes
1425         * an intermediate lock (middle_class) where this lock is
1426         * not the same as the safe lock, then the lock chain is
1427         * used to describe the problem. Otherwise we would need
1428         * to show a different CPU case for each link in the chain
1429         * from the safe_class lock to the unsafe_class lock.
1430         */
1431        if (middle_class != unsafe_class) {
1432                printk("Chain exists of:\n  ");
1433                __print_lock_name(safe_class);
1434                printk(" --> ");
1435                __print_lock_name(middle_class);
1436                printk(" --> ");
1437                __print_lock_name(unsafe_class);
1438                printk("\n\n");
1439        }
1440
1441        printk(" Possible interrupt unsafe locking scenario:\n\n");
1442        printk("       CPU0                    CPU1\n");
1443        printk("       ----                    ----\n");
1444        printk("  lock(");
1445        __print_lock_name(unsafe_class);
1446        printk(");\n");
1447        printk("                               local_irq_disable();\n");
1448        printk("                               lock(");
1449        __print_lock_name(safe_class);
1450        printk(");\n");
1451        printk("                               lock(");
1452        __print_lock_name(middle_class);
1453        printk(");\n");
1454        printk("  <Interrupt>\n");
1455        printk("    lock(");
1456        __print_lock_name(safe_class);
1457        printk(");\n");
1458        printk("\n *** DEADLOCK ***\n\n");
1459}
1460
1461static int
1462print_bad_irq_dependency(struct task_struct *curr,
1463                         struct lock_list *prev_root,
1464                         struct lock_list *next_root,
1465                         struct lock_list *backwards_entry,
1466                         struct lock_list *forwards_entry,
1467                         struct held_lock *prev,
1468                         struct held_lock *next,
1469                         enum lock_usage_bit bit1,
1470                         enum lock_usage_bit bit2,
1471                         const char *irqclass)
1472{
1473        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1474                return 0;
1475
1476        printk("\n");
1477        printk("======================================================\n");
1478        printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1479                irqclass, irqclass);
1480        print_kernel_ident();
1481        printk("------------------------------------------------------\n");
1482        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1483                curr->comm, task_pid_nr(curr),
1484                curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1485                curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1486                curr->hardirqs_enabled,
1487                curr->softirqs_enabled);
1488        print_lock(next);
1489
1490        printk("\nand this task is already holding:\n");
1491        print_lock(prev);
1492        printk("which would create a new lock dependency:\n");
1493        print_lock_name(hlock_class(prev));
1494        printk(" ->");
1495        print_lock_name(hlock_class(next));
1496        printk("\n");
1497
1498        printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1499                irqclass);
1500        print_lock_name(backwards_entry->class);
1501        printk("\n... which became %s-irq-safe at:\n", irqclass);
1502
1503        print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1504
1505        printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1506        print_lock_name(forwards_entry->class);
1507        printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1508        printk("...");
1509
1510        print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1511
1512        printk("\nother info that might help us debug this:\n\n");
1513        print_irq_lock_scenario(backwards_entry, forwards_entry,
1514                                hlock_class(prev), hlock_class(next));
1515
1516        lockdep_print_held_locks(curr);
1517
1518        printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1519        printk(" and the holding lock:\n");
1520        if (!save_trace(&prev_root->trace))
1521                return 0;
1522        print_shortest_lock_dependencies(backwards_entry, prev_root);
1523
1524        printk("\nthe dependencies between the lock to be acquired");
1525        printk(" and %s-irq-unsafe lock:\n", irqclass);
1526        if (!save_trace(&next_root->trace))
1527                return 0;
1528        print_shortest_lock_dependencies(forwards_entry, next_root);
1529
1530        printk("\nstack backtrace:\n");
1531        dump_stack();
1532
1533        return 0;
1534}
1535
1536static int
1537check_usage(struct task_struct *curr, struct held_lock *prev,
1538            struct held_lock *next, enum lock_usage_bit bit_backwards,
1539            enum lock_usage_bit bit_forwards, const char *irqclass)
1540{
1541        int ret;
1542        struct lock_list this, that;
1543        struct lock_list *uninitialized_var(target_entry);
1544        struct lock_list *uninitialized_var(target_entry1);
1545
1546        this.parent = NULL;
1547
1548        this.class = hlock_class(prev);
1549        ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1550        if (ret < 0)
1551                return print_bfs_bug(ret);
1552        if (ret == 1)
1553                return ret;
1554
1555        that.parent = NULL;
1556        that.class = hlock_class(next);
1557        ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1558        if (ret < 0)
1559                return print_bfs_bug(ret);
1560        if (ret == 1)
1561                return ret;
1562
1563        return print_bad_irq_dependency(curr, &this, &that,
1564                        target_entry, target_entry1,
1565                        prev, next,
1566                        bit_backwards, bit_forwards, irqclass);
1567}
1568
1569static const char *state_names[] = {
1570#define LOCKDEP_STATE(__STATE) \
1571        __stringify(__STATE),
1572#include "lockdep_states.h"
1573#undef LOCKDEP_STATE
1574};
1575
1576static const char *state_rnames[] = {
1577#define LOCKDEP_STATE(__STATE) \
1578        __stringify(__STATE)"-READ",
1579#include "lockdep_states.h"
1580#undef LOCKDEP_STATE
1581};
1582
1583static inline const char *state_name(enum lock_usage_bit bit)
1584{
1585        return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1586}
1587
1588static int exclusive_bit(int new_bit)
1589{
1590        /*
1591         * USED_IN
1592         * USED_IN_READ
1593         * ENABLED
1594         * ENABLED_READ
1595         *
1596         * bit 0 - write/read
1597         * bit 1 - used_in/enabled
1598         * bit 2+  state
1599         */
1600
1601        int state = new_bit & ~3;
1602        int dir = new_bit & 2;
1603
1604        /*
1605         * keep state, bit flip the direction and strip read.
1606         */
1607        return state | (dir ^ 2);
1608}
1609
1610static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1611                           struct held_lock *next, enum lock_usage_bit bit)
1612{
1613        /*
1614         * Prove that the new dependency does not connect a hardirq-safe
1615         * lock with a hardirq-unsafe lock - to achieve this we search
1616         * the backwards-subgraph starting at <prev>, and the
1617         * forwards-subgraph starting at <next>:
1618         */
1619        if (!check_usage(curr, prev, next, bit,
1620                           exclusive_bit(bit), state_name(bit)))
1621                return 0;
1622
1623        bit++; /* _READ */
1624
1625        /*
1626         * Prove that the new dependency does not connect a hardirq-safe-read
1627         * lock with a hardirq-unsafe lock - to achieve this we search
1628         * the backwards-subgraph starting at <prev>, and the
1629         * forwards-subgraph starting at <next>:
1630         */
1631        if (!check_usage(curr, prev, next, bit,
1632                           exclusive_bit(bit), state_name(bit)))
1633                return 0;
1634
1635        return 1;
1636}
1637
1638static int
1639check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1640                struct held_lock *next)
1641{
1642#define LOCKDEP_STATE(__STATE)                                          \
1643        if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1644                return 0;
1645#include "lockdep_states.h"
1646#undef LOCKDEP_STATE
1647
1648        return 1;
1649}
1650
1651static void inc_chains(void)
1652{
1653        if (current->hardirq_context)
1654                nr_hardirq_chains++;
1655        else {
1656                if (current->softirq_context)
1657                        nr_softirq_chains++;
1658                else
1659                        nr_process_chains++;
1660        }
1661}
1662
1663#else
1664
1665static inline int
1666check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1667                struct held_lock *next)
1668{
1669        return 1;
1670}
1671
1672static inline void inc_chains(void)
1673{
1674        nr_process_chains++;
1675}
1676
1677#endif
1678
1679static void
1680print_deadlock_scenario(struct held_lock *nxt,
1681                             struct held_lock *prv)
1682{
1683        struct lock_class *next = hlock_class(nxt);
1684        struct lock_class *prev = hlock_class(prv);
1685
1686        printk(" Possible unsafe locking scenario:\n\n");
1687        printk("       CPU0\n");
1688        printk("       ----\n");
1689        printk("  lock(");
1690        __print_lock_name(prev);
1691        printk(");\n");
1692        printk("  lock(");
1693        __print_lock_name(next);
1694        printk(");\n");
1695        printk("\n *** DEADLOCK ***\n\n");
1696        printk(" May be due to missing lock nesting notation\n\n");
1697}
1698
1699static int
1700print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1701                   struct held_lock *next)
1702{
1703        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1704                return 0;
1705
1706        printk("\n");
1707        printk("=============================================\n");
1708        printk("[ INFO: possible recursive locking detected ]\n");
1709        print_kernel_ident();
1710        printk("---------------------------------------------\n");
1711        printk("%s/%d is trying to acquire lock:\n",
1712                curr->comm, task_pid_nr(curr));
1713        print_lock(next);
1714        printk("\nbut task is already holding lock:\n");
1715        print_lock(prev);
1716
1717        printk("\nother info that might help us debug this:\n");
1718        print_deadlock_scenario(next, prev);
1719        lockdep_print_held_locks(curr);
1720
1721        printk("\nstack backtrace:\n");
1722        dump_stack();
1723
1724        return 0;
1725}
1726
1727/*
1728 * Check whether we are holding such a class already.
1729 *
1730 * (Note that this has to be done separately, because the graph cannot
1731 * detect such classes of deadlocks.)
1732 *
1733 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1734 */
1735static int
1736check_deadlock(struct task_struct *curr, struct held_lock *next,
1737               struct lockdep_map *next_instance, int read)
1738{
1739        struct held_lock *prev;
1740        struct held_lock *nest = NULL;
1741        int i;
1742
1743        for (i = 0; i < curr->lockdep_depth; i++) {
1744                prev = curr->held_locks + i;
1745
1746                if (prev->instance == next->nest_lock)
1747                        nest = prev;
1748
1749                if (hlock_class(prev) != hlock_class(next))
1750                        continue;
1751
1752                /*
1753                 * Allow read-after-read recursion of the same
1754                 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1755                 */
1756                if ((read == 2) && prev->read)
1757                        return 2;
1758
1759                /*
1760                 * We're holding the nest_lock, which serializes this lock's
1761                 * nesting behaviour.
1762                 */
1763                if (nest)
1764                        return 2;
1765
1766                return print_deadlock_bug(curr, prev, next);
1767        }
1768        return 1;
1769}
1770
1771/*
1772 * There was a chain-cache miss, and we are about to add a new dependency
1773 * to a previous lock. We recursively validate the following rules:
1774 *
1775 *  - would the adding of the <prev> -> <next> dependency create a
1776 *    circular dependency in the graph? [== circular deadlock]
1777 *
1778 *  - does the new prev->next dependency connect any hardirq-safe lock
1779 *    (in the full backwards-subgraph starting at <prev>) with any
1780 *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1781 *    <next>)? [== illegal lock inversion with hardirq contexts]
1782 *
1783 *  - does the new prev->next dependency connect any softirq-safe lock
1784 *    (in the full backwards-subgraph starting at <prev>) with any
1785 *    softirq-unsafe lock (in the full forwards-subgraph starting at
1786 *    <next>)? [== illegal lock inversion with softirq contexts]
1787 *
1788 * any of these scenarios could lead to a deadlock.
1789 *
1790 * Then if all the validations pass, we add the forwards and backwards
1791 * dependency.
1792 */
1793static int
1794check_prev_add(struct task_struct *curr, struct held_lock *prev,
1795               struct held_lock *next, int distance, int *stack_saved)
1796{
1797        struct lock_list *entry;
1798        int ret;
1799        struct lock_list this;
1800        struct lock_list *uninitialized_var(target_entry);
1801        /*
1802         * Static variable, serialized by the graph_lock().
1803         *
1804         * We use this static variable to save the stack trace in case
1805         * we call into this function multiple times due to encountering
1806         * trylocks in the held lock stack.
1807         */
1808        static struct stack_trace trace;
1809
1810        /*
1811         * Prove that the new <prev> -> <next> dependency would not
1812         * create a circular dependency in the graph. (We do this by
1813         * forward-recursing into the graph starting at <next>, and
1814         * checking whether we can reach <prev>.)
1815         *
1816         * We are using global variables to control the recursion, to
1817         * keep the stackframe size of the recursive functions low:
1818         */
1819        this.class = hlock_class(next);
1820        this.parent = NULL;
1821        ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1822        if (unlikely(!ret))
1823                return print_circular_bug(&this, target_entry, next, prev);
1824        else if (unlikely(ret < 0))
1825                return print_bfs_bug(ret);
1826
1827        if (!check_prev_add_irq(curr, prev, next))
1828                return 0;
1829
1830        /*
1831         * For recursive read-locks we do all the dependency checks,
1832         * but we dont store read-triggered dependencies (only
1833         * write-triggered dependencies). This ensures that only the
1834         * write-side dependencies matter, and that if for example a
1835         * write-lock never takes any other locks, then the reads are
1836         * equivalent to a NOP.
1837         */
1838        if (next->read == 2 || prev->read == 2)
1839                return 1;
1840        /*
1841         * Is the <prev> -> <next> dependency already present?
1842         *
1843         * (this may occur even though this is a new chain: consider
1844         *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1845         *  chains - the second one will be new, but L1 already has
1846         *  L2 added to its dependency list, due to the first chain.)
1847         */
1848        list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1849                if (entry->class == hlock_class(next)) {
1850                        if (distance == 1)
1851                                entry->distance = 1;
1852                        return 2;
1853                }
1854        }
1855
1856        if (!*stack_saved) {
1857                if (!save_trace(&trace))
1858                        return 0;
1859                *stack_saved = 1;
1860        }
1861
1862        /*
1863         * Ok, all validations passed, add the new lock
1864         * to the previous lock's dependency list:
1865         */
1866        ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1867                               &hlock_class(prev)->locks_after,
1868                               next->acquire_ip, distance, &trace);
1869
1870        if (!ret)
1871                return 0;
1872
1873        ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1874                               &hlock_class(next)->locks_before,
1875                               next->acquire_ip, distance, &trace);
1876        if (!ret)
1877                return 0;
1878
1879        /*
1880         * Debugging printouts:
1881         */
1882        if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1883                /* We drop graph lock, so another thread can overwrite trace. */
1884                *stack_saved = 0;
1885                graph_unlock();
1886                printk("\n new dependency: ");
1887                print_lock_name(hlock_class(prev));
1888                printk(" => ");
1889                print_lock_name(hlock_class(next));
1890                printk("\n");
1891                dump_stack();
1892                return graph_lock();
1893        }
1894        return 1;
1895}
1896
1897/*
1898 * Add the dependency to all directly-previous locks that are 'relevant'.
1899 * The ones that are relevant are (in increasing distance from curr):
1900 * all consecutive trylock entries and the final non-trylock entry - or
1901 * the end of this context's lock-chain - whichever comes first.
1902 */
1903static int
1904check_prevs_add(struct task_struct *curr, struct held_lock *next)
1905{
1906        int depth = curr->lockdep_depth;
1907        int stack_saved = 0;
1908        struct held_lock *hlock;
1909
1910        /*
1911         * Debugging checks.
1912         *
1913         * Depth must not be zero for a non-head lock:
1914         */
1915        if (!depth)
1916                goto out_bug;
1917        /*
1918         * At least two relevant locks must exist for this
1919         * to be a head:
1920         */
1921        if (curr->held_locks[depth].irq_context !=
1922                        curr->held_locks[depth-1].irq_context)
1923                goto out_bug;
1924
1925        for (;;) {
1926                int distance = curr->lockdep_depth - depth + 1;
1927                hlock = curr->held_locks + depth - 1;
1928                /*
1929                 * Only non-recursive-read entries get new dependencies
1930                 * added:
1931                 */
1932                if (hlock->read != 2 && hlock->check) {
1933                        if (!check_prev_add(curr, hlock, next,
1934                                                distance, &stack_saved))
1935                                return 0;
1936                        /*
1937                         * Stop after the first non-trylock entry,
1938                         * as non-trylock entries have added their
1939                         * own direct dependencies already, so this
1940                         * lock is connected to them indirectly:
1941                         */
1942                        if (!hlock->trylock)
1943                                break;
1944                }
1945                depth--;
1946                /*
1947                 * End of lock-stack?
1948                 */
1949                if (!depth)
1950                        break;
1951                /*
1952                 * Stop the search if we cross into another context:
1953                 */
1954                if (curr->held_locks[depth].irq_context !=
1955                                curr->held_locks[depth-1].irq_context)
1956                        break;
1957        }
1958        return 1;
1959out_bug:
1960        if (!debug_locks_off_graph_unlock())
1961                return 0;
1962
1963        /*
1964         * Clearly we all shouldn't be here, but since we made it we
1965         * can reliable say we messed up our state. See the above two
1966         * gotos for reasons why we could possibly end up here.
1967         */
1968        WARN_ON(1);
1969
1970        return 0;
1971}
1972
1973unsigned long nr_lock_chains;
1974struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1975int nr_chain_hlocks;
1976static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1977
1978struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1979{
1980        return lock_classes + chain_hlocks[chain->base + i];
1981}
1982
1983/*
1984 * Returns the index of the first held_lock of the current chain
1985 */
1986static inline int get_first_held_lock(struct task_struct *curr,
1987                                        struct held_lock *hlock)
1988{
1989        int i;
1990        struct held_lock *hlock_curr;
1991
1992        for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1993                hlock_curr = curr->held_locks + i;
1994                if (hlock_curr->irq_context != hlock->irq_context)
1995                        break;
1996
1997        }
1998
1999        return ++i;
2000}
2001
2002#ifdef CONFIG_DEBUG_LOCKDEP
2003/*
2004 * Returns the next chain_key iteration
2005 */
2006static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2007{
2008        u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2009
2010        printk(" class_idx:%d -> chain_key:%016Lx",
2011                class_idx,
2012                (unsigned long long)new_chain_key);
2013        return new_chain_key;
2014}
2015
2016static void
2017print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2018{
2019        struct held_lock *hlock;
2020        u64 chain_key = 0;
2021        int depth = curr->lockdep_depth;
2022        int i;
2023
2024        printk("depth: %u\n", depth + 1);
2025        for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2026                hlock = curr->held_locks + i;
2027                chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2028
2029                print_lock(hlock);
2030        }
2031
2032        print_chain_key_iteration(hlock_next->class_idx, chain_key);
2033        print_lock(hlock_next);
2034}
2035
2036static void print_chain_keys_chain(struct lock_chain *chain)
2037{
2038        int i;
2039        u64 chain_key = 0;
2040        int class_id;
2041
2042        printk("depth: %u\n", chain->depth);
2043        for (i = 0; i < chain->depth; i++) {
2044                class_id = chain_hlocks[chain->base + i];
2045                chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2046
2047                print_lock_name(lock_classes + class_id);
2048                printk("\n");
2049        }
2050}
2051
2052static void print_collision(struct task_struct *curr,
2053                        struct held_lock *hlock_next,
2054                        struct lock_chain *chain)
2055{
2056        printk("\n");
2057        printk("======================\n");
2058        printk("[chain_key collision ]\n");
2059        print_kernel_ident();
2060        printk("----------------------\n");
2061        printk("%s/%d: ", current->comm, task_pid_nr(current));
2062        printk("Hash chain already cached but the contents don't match!\n");
2063
2064        printk("Held locks:");
2065        print_chain_keys_held_locks(curr, hlock_next);
2066
2067        printk("Locks in cached chain:");
2068        print_chain_keys_chain(chain);
2069
2070        printk("\nstack backtrace:\n");
2071        dump_stack();
2072}
2073#endif
2074
2075/*
2076 * Checks whether the chain and the current held locks are consistent
2077 * in depth and also in content. If they are not it most likely means
2078 * that there was a collision during the calculation of the chain_key.
2079 * Returns: 0 not passed, 1 passed
2080 */
2081static int check_no_collision(struct task_struct *curr,
2082                        struct held_lock *hlock,
2083                        struct lock_chain *chain)
2084{
2085#ifdef CONFIG_DEBUG_LOCKDEP
2086        int i, j, id;
2087
2088        i = get_first_held_lock(curr, hlock);
2089
2090        if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2091                print_collision(curr, hlock, chain);
2092                return 0;
2093        }
2094
2095        for (j = 0; j < chain->depth - 1; j++, i++) {
2096                id = curr->held_locks[i].class_idx - 1;
2097
2098                if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2099                        print_collision(curr, hlock, chain);
2100                        return 0;
2101                }
2102        }
2103#endif
2104        return 1;
2105}
2106
2107/*
2108 * Look up a dependency chain. If the key is not present yet then
2109 * add it and return 1 - in this case the new dependency chain is
2110 * validated. If the key is already hashed, return 0.
2111 * (On return with 1 graph_lock is held.)
2112 */
2113static inline int lookup_chain_cache(struct task_struct *curr,
2114                                     struct held_lock *hlock,
2115                                     u64 chain_key)
2116{
2117        struct lock_class *class = hlock_class(hlock);
2118        struct hlist_head *hash_head = chainhashentry(chain_key);
2119        struct lock_chain *chain;
2120        int i, j;
2121
2122        /*
2123         * We might need to take the graph lock, ensure we've got IRQs
2124         * disabled to make this an IRQ-safe lock.. for recursion reasons
2125         * lockdep won't complain about its own locking errors.
2126         */
2127        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2128                return 0;
2129        /*
2130         * We can walk it lock-free, because entries only get added
2131         * to the hash:
2132         */
2133        hlist_for_each_entry_rcu(chain, hash_head, entry) {
2134                if (chain->chain_key == chain_key) {
2135cache_hit:
2136                        debug_atomic_inc(chain_lookup_hits);
2137                        if (!check_no_collision(curr, hlock, chain))
2138                                return 0;
2139
2140                        if (very_verbose(class))
2141                                printk("\nhash chain already cached, key: "
2142                                        "%016Lx tail class: [%p] %s\n",
2143                                        (unsigned long long)chain_key,
2144                                        class->key, class->name);
2145                        return 0;
2146                }
2147        }
2148        if (very_verbose(class))
2149                printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2150                        (unsigned long long)chain_key, class->key, class->name);
2151        /*
2152         * Allocate a new chain entry from the static array, and add
2153         * it to the hash:
2154         */
2155        if (!graph_lock())
2156                return 0;
2157        /*
2158         * We have to walk the chain again locked - to avoid duplicates:
2159         */
2160        hlist_for_each_entry(chain, hash_head, entry) {
2161                if (chain->chain_key == chain_key) {
2162                        graph_unlock();
2163                        goto cache_hit;
2164                }
2165        }
2166        if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2167                if (!debug_locks_off_graph_unlock())
2168                        return 0;
2169
2170                print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2171                dump_stack();
2172                return 0;
2173        }
2174        chain = lock_chains + nr_lock_chains++;
2175        chain->chain_key = chain_key;
2176        chain->irq_context = hlock->irq_context;
2177        i = get_first_held_lock(curr, hlock);
2178        chain->depth = curr->lockdep_depth + 1 - i;
2179
2180        BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2181        BUILD_BUG_ON((1UL << 6)  <= ARRAY_SIZE(curr->held_locks));
2182        BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2183
2184        if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2185                chain->base = nr_chain_hlocks;
2186                for (j = 0; j < chain->depth - 1; j++, i++) {
2187                        int lock_id = curr->held_locks[i].class_idx - 1;
2188                        chain_hlocks[chain->base + j] = lock_id;
2189                }
2190                chain_hlocks[chain->base + j] = class - lock_classes;
2191        }
2192
2193        if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2194                nr_chain_hlocks += chain->depth;
2195
2196#ifdef CONFIG_DEBUG_LOCKDEP
2197        /*
2198         * Important for check_no_collision().
2199         */
2200        if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2201                if (debug_locks_off_graph_unlock())
2202                        return 0;
2203
2204                print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2205                dump_stack();
2206                return 0;
2207        }
2208#endif
2209
2210        hlist_add_head_rcu(&chain->entry, hash_head);
2211        debug_atomic_inc(chain_lookup_misses);
2212        inc_chains();
2213
2214        return 1;
2215}
2216
2217static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2218                struct held_lock *hlock, int chain_head, u64 chain_key)
2219{
2220        /*
2221         * Trylock needs to maintain the stack of held locks, but it
2222         * does not add new dependencies, because trylock can be done
2223         * in any order.
2224         *
2225         * We look up the chain_key and do the O(N^2) check and update of
2226         * the dependencies only if this is a new dependency chain.
2227         * (If lookup_chain_cache() returns with 1 it acquires
2228         * graph_lock for us)
2229         */
2230        if (!hlock->trylock && hlock->check &&
2231            lookup_chain_cache(curr, hlock, chain_key)) {
2232                /*
2233                 * Check whether last held lock:
2234                 *
2235                 * - is irq-safe, if this lock is irq-unsafe
2236                 * - is softirq-safe, if this lock is hardirq-unsafe
2237                 *
2238                 * And check whether the new lock's dependency graph
2239                 * could lead back to the previous lock.
2240                 *
2241                 * any of these scenarios could lead to a deadlock. If
2242                 * All validations
2243                 */
2244                int ret = check_deadlock(curr, hlock, lock, hlock->read);
2245
2246                if (!ret)
2247                        return 0;
2248                /*
2249                 * Mark recursive read, as we jump over it when
2250                 * building dependencies (just like we jump over
2251                 * trylock entries):
2252                 */
2253                if (ret == 2)
2254                        hlock->read = 2;
2255                /*
2256                 * Add dependency only if this lock is not the head
2257                 * of the chain, and if it's not a secondary read-lock:
2258                 */
2259                if (!chain_head && ret != 2)
2260                        if (!check_prevs_add(curr, hlock))
2261                                return 0;
2262                graph_unlock();
2263        } else
2264                /* after lookup_chain_cache(): */
2265                if (unlikely(!debug_locks))
2266                        return 0;
2267
2268        return 1;
2269}
2270#else
2271static inline int validate_chain(struct task_struct *curr,
2272                struct lockdep_map *lock, struct held_lock *hlock,
2273                int chain_head, u64 chain_key)
2274{
2275        return 1;
2276}
2277#endif
2278
2279/*
2280 * We are building curr_chain_key incrementally, so double-check
2281 * it from scratch, to make sure that it's done correctly:
2282 */
2283static void check_chain_key(struct task_struct *curr)
2284{
2285#ifdef CONFIG_DEBUG_LOCKDEP
2286        struct held_lock *hlock, *prev_hlock = NULL;
2287        unsigned int i;
2288        u64 chain_key = 0;
2289
2290        for (i = 0; i < curr->lockdep_depth; i++) {
2291                hlock = curr->held_locks + i;
2292                if (chain_key != hlock->prev_chain_key) {
2293                        debug_locks_off();
2294                        /*
2295                         * We got mighty confused, our chain keys don't match
2296                         * with what we expect, someone trample on our task state?
2297                         */
2298                        WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2299                                curr->lockdep_depth, i,
2300                                (unsigned long long)chain_key,
2301                                (unsigned long long)hlock->prev_chain_key);
2302                        return;
2303                }
2304                /*
2305                 * Whoops ran out of static storage again?
2306                 */
2307                if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2308                        return;
2309
2310                if (prev_hlock && (prev_hlock->irq_context !=
2311                                                        hlock->irq_context))
2312                        chain_key = 0;
2313                chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2314                prev_hlock = hlock;
2315        }
2316        if (chain_key != curr->curr_chain_key) {
2317                debug_locks_off();
2318                /*
2319                 * More smoking hash instead of calculating it, damn see these
2320                 * numbers float.. I bet that a pink elephant stepped on my memory.
2321                 */
2322                WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2323                        curr->lockdep_depth, i,
2324                        (unsigned long long)chain_key,
2325                        (unsigned long long)curr->curr_chain_key);
2326        }
2327#endif
2328}
2329
2330static void
2331print_usage_bug_scenario(struct held_lock *lock)
2332{
2333        struct lock_class *class = hlock_class(lock);
2334
2335        printk(" Possible unsafe locking scenario:\n\n");
2336        printk("       CPU0\n");
2337        printk("       ----\n");
2338        printk("  lock(");
2339        __print_lock_name(class);
2340        printk(");\n");
2341        printk("  <Interrupt>\n");
2342        printk("    lock(");
2343        __print_lock_name(class);
2344        printk(");\n");
2345        printk("\n *** DEADLOCK ***\n\n");
2346}
2347
2348static int
2349print_usage_bug(struct task_struct *curr, struct held_lock *this,
2350                enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2351{
2352        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2353                return 0;
2354
2355        printk("\n");
2356        printk("=================================\n");
2357        printk("[ INFO: inconsistent lock state ]\n");
2358        print_kernel_ident();
2359        printk("---------------------------------\n");
2360
2361        printk("inconsistent {%s} -> {%s} usage.\n",
2362                usage_str[prev_bit], usage_str[new_bit]);
2363
2364        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2365                curr->comm, task_pid_nr(curr),
2366                trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2367                trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2368                trace_hardirqs_enabled(curr),
2369                trace_softirqs_enabled(curr));
2370        print_lock(this);
2371
2372        printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2373        print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2374
2375        print_irqtrace_events(curr);
2376        printk("\nother info that might help us debug this:\n");
2377        print_usage_bug_scenario(this);
2378
2379        lockdep_print_held_locks(curr);
2380
2381        printk("\nstack backtrace:\n");
2382        dump_stack();
2383
2384        return 0;
2385}
2386
2387/*
2388 * Print out an error if an invalid bit is set:
2389 */
2390static inline int
2391valid_state(struct task_struct *curr, struct held_lock *this,
2392            enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2393{
2394        if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2395                return print_usage_bug(curr, this, bad_bit, new_bit);
2396        return 1;
2397}
2398
2399static int mark_lock(struct task_struct *curr, struct held_lock *this,
2400                     enum lock_usage_bit new_bit);
2401
2402#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2403
2404/*
2405 * print irq inversion bug:
2406 */
2407static int
2408print_irq_inversion_bug(struct task_struct *curr,
2409                        struct lock_list *root, struct lock_list *other,
2410                        struct held_lock *this, int forwards,
2411                        const char *irqclass)
2412{
2413        struct lock_list *entry = other;
2414        struct lock_list *middle = NULL;
2415        int depth;
2416
2417        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2418                return 0;
2419
2420        printk("\n");
2421        printk("=========================================================\n");
2422        printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2423        print_kernel_ident();
2424        printk("---------------------------------------------------------\n");
2425        printk("%s/%d just changed the state of lock:\n",
2426                curr->comm, task_pid_nr(curr));
2427        print_lock(this);
2428        if (forwards)
2429                printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2430        else
2431                printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2432        print_lock_name(other->class);
2433        printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2434
2435        printk("\nother info that might help us debug this:\n");
2436
2437        /* Find a middle lock (if one exists) */
2438        depth = get_lock_depth(other);
2439        do {
2440                if (depth == 0 && (entry != root)) {
2441                        printk("lockdep:%s bad path found in chain graph\n", __func__);
2442                        break;
2443                }
2444                middle = entry;
2445                entry = get_lock_parent(entry);
2446                depth--;
2447        } while (entry && entry != root && (depth >= 0));
2448        if (forwards)
2449                print_irq_lock_scenario(root, other,
2450                        middle ? middle->class : root->class, other->class);
2451        else
2452                print_irq_lock_scenario(other, root,
2453                        middle ? middle->class : other->class, root->class);
2454
2455        lockdep_print_held_locks(curr);
2456
2457        printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2458        if (!save_trace(&root->trace))
2459                return 0;
2460        print_shortest_lock_dependencies(other, root);
2461
2462        printk("\nstack backtrace:\n");
2463        dump_stack();
2464
2465        return 0;
2466}
2467
2468/*
2469 * Prove that in the forwards-direction subgraph starting at <this>
2470 * there is no lock matching <mask>:
2471 */
2472static int
2473check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2474                     enum lock_usage_bit bit, const char *irqclass)
2475{
2476        int ret;
2477        struct lock_list root;
2478        struct lock_list *uninitialized_var(target_entry);
2479
2480        root.parent = NULL;
2481        root.class = hlock_class(this);
2482        ret = find_usage_forwards(&root, bit, &target_entry);
2483        if (ret < 0)
2484                return print_bfs_bug(ret);
2485        if (ret == 1)
2486                return ret;
2487
2488        return print_irq_inversion_bug(curr, &root, target_entry,
2489                                        this, 1, irqclass);
2490}
2491
2492/*
2493 * Prove that in the backwards-direction subgraph starting at <this>
2494 * there is no lock matching <mask>:
2495 */
2496static int
2497check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2498                      enum lock_usage_bit bit, const char *irqclass)
2499{
2500        int ret;
2501        struct lock_list root;
2502        struct lock_list *uninitialized_var(target_entry);
2503
2504        root.parent = NULL;
2505        root.class = hlock_class(this);
2506        ret = find_usage_backwards(&root, bit, &target_entry);
2507        if (ret < 0)
2508                return print_bfs_bug(ret);
2509        if (ret == 1)
2510                return ret;
2511
2512        return print_irq_inversion_bug(curr, &root, target_entry,
2513                                        this, 0, irqclass);
2514}
2515
2516void print_irqtrace_events(struct task_struct *curr)
2517{
2518        printk("irq event stamp: %u\n", curr->irq_events);
2519        printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2520        print_ip_sym(curr->hardirq_enable_ip);
2521        printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2522        print_ip_sym(curr->hardirq_disable_ip);
2523        printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2524        print_ip_sym(curr->softirq_enable_ip);
2525        printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2526        print_ip_sym(curr->softirq_disable_ip);
2527}
2528
2529static int HARDIRQ_verbose(struct lock_class *class)
2530{
2531#if HARDIRQ_VERBOSE
2532        return class_filter(class);
2533#endif
2534        return 0;
2535}
2536
2537static int SOFTIRQ_verbose(struct lock_class *class)
2538{
2539#if SOFTIRQ_VERBOSE
2540        return class_filter(class);
2541#endif
2542        return 0;
2543}
2544
2545static int RECLAIM_FS_verbose(struct lock_class *class)
2546{
2547#if RECLAIM_VERBOSE
2548        return class_filter(class);
2549#endif
2550        return 0;
2551}
2552
2553#define STRICT_READ_CHECKS      1
2554
2555static int (*state_verbose_f[])(struct lock_class *class) = {
2556#define LOCKDEP_STATE(__STATE) \
2557        __STATE##_verbose,
2558#include "lockdep_states.h"
2559#undef LOCKDEP_STATE
2560};
2561
2562static inline int state_verbose(enum lock_usage_bit bit,
2563                                struct lock_class *class)
2564{
2565        return state_verbose_f[bit >> 2](class);
2566}
2567
2568typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2569                             enum lock_usage_bit bit, const char *name);
2570
2571static int
2572mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2573                enum lock_usage_bit new_bit)
2574{
2575        int excl_bit = exclusive_bit(new_bit);
2576        int read = new_bit & 1;
2577        int dir = new_bit & 2;
2578
2579        /*
2580         * mark USED_IN has to look forwards -- to ensure no dependency
2581         * has ENABLED state, which would allow recursion deadlocks.
2582         *
2583         * mark ENABLED has to look backwards -- to ensure no dependee
2584         * has USED_IN state, which, again, would allow  recursion deadlocks.
2585         */
2586        check_usage_f usage = dir ?
2587                check_usage_backwards : check_usage_forwards;
2588
2589        /*
2590         * Validate that this particular lock does not have conflicting
2591         * usage states.
2592         */
2593        if (!valid_state(curr, this, new_bit, excl_bit))
2594                return 0;
2595
2596        /*
2597         * Validate that the lock dependencies don't have conflicting usage
2598         * states.
2599         */
2600        if ((!read || !dir || STRICT_READ_CHECKS) &&
2601                        !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2602                return 0;
2603
2604        /*
2605         * Check for read in write conflicts
2606         */
2607        if (!read) {
2608                if (!valid_state(curr, this, new_bit, excl_bit + 1))
2609                        return 0;
2610
2611                if (STRICT_READ_CHECKS &&
2612                        !usage(curr, this, excl_bit + 1,
2613                                state_name(new_bit + 1)))
2614                        return 0;
2615        }
2616
2617        if (state_verbose(new_bit, hlock_class(this)))
2618                return 2;
2619
2620        return 1;
2621}
2622
2623enum mark_type {
2624#define LOCKDEP_STATE(__STATE)  __STATE,
2625#include "lockdep_states.h"
2626#undef LOCKDEP_STATE
2627};
2628
2629/*
2630 * Mark all held locks with a usage bit:
2631 */
2632static int
2633mark_held_locks(struct task_struct *curr, enum mark_type mark)
2634{
2635        enum lock_usage_bit usage_bit;
2636        struct held_lock *hlock;
2637        int i;
2638
2639        for (i = 0; i < curr->lockdep_depth; i++) {
2640                hlock = curr->held_locks + i;
2641
2642                usage_bit = 2 + (mark << 2); /* ENABLED */
2643                if (hlock->read)
2644                        usage_bit += 1; /* READ */
2645
2646                BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2647
2648                if (!hlock->check)
2649                        continue;
2650
2651                if (!mark_lock(curr, hlock, usage_bit))
2652                        return 0;
2653        }
2654
2655        return 1;
2656}
2657
2658/*
2659 * Hardirqs will be enabled:
2660 */
2661static void __trace_hardirqs_on_caller(unsigned long ip)
2662{
2663        struct task_struct *curr = current;
2664
2665        /* we'll do an OFF -> ON transition: */
2666        curr->hardirqs_enabled = 1;
2667
2668        /*
2669         * We are going to turn hardirqs on, so set the
2670         * usage bit for all held locks:
2671         */
2672        if (!mark_held_locks(curr, HARDIRQ))
2673                return;
2674        /*
2675         * If we have softirqs enabled, then set the usage
2676         * bit for all held locks. (disabled hardirqs prevented
2677         * this bit from being set before)
2678         */
2679        if (curr->softirqs_enabled)
2680                if (!mark_held_locks(curr, SOFTIRQ))
2681                        return;
2682
2683        curr->hardirq_enable_ip = ip;
2684        curr->hardirq_enable_event = ++curr->irq_events;
2685        debug_atomic_inc(hardirqs_on_events);
2686}
2687
2688__visible void trace_hardirqs_on_caller(unsigned long ip)
2689{
2690        time_hardirqs_on(CALLER_ADDR0, ip);
2691
2692        if (unlikely(!debug_locks || current->lockdep_recursion))
2693                return;
2694
2695        if (unlikely(current->hardirqs_enabled)) {
2696                /*
2697                 * Neither irq nor preemption are disabled here
2698                 * so this is racy by nature but losing one hit
2699                 * in a stat is not a big deal.
2700                 */
2701                __debug_atomic_inc(redundant_hardirqs_on);
2702                return;
2703        }
2704
2705        /*
2706         * We're enabling irqs and according to our state above irqs weren't
2707         * already enabled, yet we find the hardware thinks they are in fact
2708         * enabled.. someone messed up their IRQ state tracing.
2709         */
2710        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2711                return;
2712
2713        /*
2714         * See the fine text that goes along with this variable definition.
2715         */
2716        if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2717                return;
2718
2719        /*
2720         * Can't allow enabling interrupts while in an interrupt handler,
2721         * that's general bad form and such. Recursion, limited stack etc..
2722         */
2723        if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2724                return;
2725
2726        current->lockdep_recursion = 1;
2727        __trace_hardirqs_on_caller(ip);
2728        current->lockdep_recursion = 0;
2729}
2730EXPORT_SYMBOL(trace_hardirqs_on_caller);
2731
2732void trace_hardirqs_on(void)
2733{
2734        trace_hardirqs_on_caller(CALLER_ADDR0);
2735}
2736EXPORT_SYMBOL(trace_hardirqs_on);
2737
2738/*
2739 * Hardirqs were disabled:
2740 */
2741__visible void trace_hardirqs_off_caller(unsigned long ip)
2742{
2743        struct task_struct *curr = current;
2744
2745        time_hardirqs_off(CALLER_ADDR0, ip);
2746
2747        if (unlikely(!debug_locks || current->lockdep_recursion))
2748                return;
2749
2750        /*
2751         * So we're supposed to get called after you mask local IRQs, but for
2752         * some reason the hardware doesn't quite think you did a proper job.
2753         */
2754        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2755                return;
2756
2757        if (curr->hardirqs_enabled) {
2758                /*
2759                 * We have done an ON -> OFF transition:
2760                 */
2761                curr->hardirqs_enabled = 0;
2762                curr->hardirq_disable_ip = ip;
2763                curr->hardirq_disable_event = ++curr->irq_events;
2764                debug_atomic_inc(hardirqs_off_events);
2765        } else
2766                debug_atomic_inc(redundant_hardirqs_off);
2767}
2768EXPORT_SYMBOL(trace_hardirqs_off_caller);
2769
2770void trace_hardirqs_off(void)
2771{
2772        trace_hardirqs_off_caller(CALLER_ADDR0);
2773}
2774EXPORT_SYMBOL(trace_hardirqs_off);
2775
2776/*
2777 * Softirqs will be enabled:
2778 */
2779void trace_softirqs_on(unsigned long ip)
2780{
2781        struct task_struct *curr = current;
2782
2783        if (unlikely(!debug_locks || current->lockdep_recursion))
2784                return;
2785
2786        /*
2787         * We fancy IRQs being disabled here, see softirq.c, avoids
2788         * funny state and nesting things.
2789         */
2790        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2791                return;
2792
2793        if (curr->softirqs_enabled) {
2794                debug_atomic_inc(redundant_softirqs_on);
2795                return;
2796        }
2797
2798        current->lockdep_recursion = 1;
2799        /*
2800         * We'll do an OFF -> ON transition:
2801         */
2802        curr->softirqs_enabled = 1;
2803        curr->softirq_enable_ip = ip;
2804        curr->softirq_enable_event = ++curr->irq_events;
2805        debug_atomic_inc(softirqs_on_events);
2806        /*
2807         * We are going to turn softirqs on, so set the
2808         * usage bit for all held locks, if hardirqs are
2809         * enabled too:
2810         */
2811        if (curr->hardirqs_enabled)
2812                mark_held_locks(curr, SOFTIRQ);
2813        current->lockdep_recursion = 0;
2814}
2815
2816/*
2817 * Softirqs were disabled:
2818 */
2819void trace_softirqs_off(unsigned long ip)
2820{
2821        struct task_struct *curr = current;
2822
2823        if (unlikely(!debug_locks || current->lockdep_recursion))
2824                return;
2825
2826        /*
2827         * We fancy IRQs being disabled here, see softirq.c
2828         */
2829        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2830                return;
2831
2832        if (curr->softirqs_enabled) {
2833                /*
2834                 * We have done an ON -> OFF transition:
2835                 */
2836                curr->softirqs_enabled = 0;
2837                curr->softirq_disable_ip = ip;
2838                curr->softirq_disable_event = ++curr->irq_events;
2839                debug_atomic_inc(softirqs_off_events);
2840                /*
2841                 * Whoops, we wanted softirqs off, so why aren't they?
2842                 */
2843                DEBUG_LOCKS_WARN_ON(!softirq_count());
2844        } else
2845                debug_atomic_inc(redundant_softirqs_off);
2846}
2847
2848static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2849{
2850        struct task_struct *curr = current;
2851
2852        if (unlikely(!debug_locks))
2853                return;
2854
2855        /* no reclaim without waiting on it */
2856        if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2857                return;
2858
2859        /* this guy won't enter reclaim */
2860        if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2861                return;
2862
2863        /* We're only interested __GFP_FS allocations for now */
2864        if (!(gfp_mask & __GFP_FS))
2865                return;
2866
2867        /*
2868         * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2869         */
2870        if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2871                return;
2872
2873        mark_held_locks(curr, RECLAIM_FS);
2874}
2875
2876static void check_flags(unsigned long flags);
2877
2878void lockdep_trace_alloc(gfp_t gfp_mask)
2879{
2880        unsigned long flags;
2881
2882        if (unlikely(current->lockdep_recursion))
2883                return;
2884
2885        raw_local_irq_save(flags);
2886        check_flags(flags);
2887        current->lockdep_recursion = 1;
2888        __lockdep_trace_alloc(gfp_mask, flags);
2889        current->lockdep_recursion = 0;
2890        raw_local_irq_restore(flags);
2891}
2892
2893static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2894{
2895        /*
2896         * If non-trylock use in a hardirq or softirq context, then
2897         * mark the lock as used in these contexts:
2898         */
2899        if (!hlock->trylock) {
2900                if (hlock->read) {
2901                        if (curr->hardirq_context)
2902                                if (!mark_lock(curr, hlock,
2903                                                LOCK_USED_IN_HARDIRQ_READ))
2904                                        return 0;
2905                        if (curr->softirq_context)
2906                                if (!mark_lock(curr, hlock,
2907                                                LOCK_USED_IN_SOFTIRQ_READ))
2908                                        return 0;
2909                } else {
2910                        if (curr->hardirq_context)
2911                                if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2912                                        return 0;
2913                        if (curr->softirq_context)
2914                                if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2915                                        return 0;
2916                }
2917        }
2918        if (!hlock->hardirqs_off) {
2919                if (hlock->read) {
2920                        if (!mark_lock(curr, hlock,
2921                                        LOCK_ENABLED_HARDIRQ_READ))
2922                                return 0;
2923                        if (curr->softirqs_enabled)
2924                                if (!mark_lock(curr, hlock,
2925                                                LOCK_ENABLED_SOFTIRQ_READ))
2926                                        return 0;
2927                } else {
2928                        if (!mark_lock(curr, hlock,
2929                                        LOCK_ENABLED_HARDIRQ))
2930                                return 0;
2931                        if (curr->softirqs_enabled)
2932                                if (!mark_lock(curr, hlock,
2933                                                LOCK_ENABLED_SOFTIRQ))
2934                                        return 0;
2935                }
2936        }
2937
2938        /*
2939         * We reuse the irq context infrastructure more broadly as a general
2940         * context checking code. This tests GFP_FS recursion (a lock taken
2941         * during reclaim for a GFP_FS allocation is held over a GFP_FS
2942         * allocation).
2943         */
2944        if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2945                if (hlock->read) {
2946                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2947                                        return 0;
2948                } else {
2949                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2950                                        return 0;
2951                }
2952        }
2953
2954        return 1;
2955}
2956
2957static inline unsigned int task_irq_context(struct task_struct *task)
2958{
2959        return 2 * !!task->hardirq_context + !!task->softirq_context;
2960}
2961
2962static int separate_irq_context(struct task_struct *curr,
2963                struct held_lock *hlock)
2964{
2965        unsigned int depth = curr->lockdep_depth;
2966
2967        /*
2968         * Keep track of points where we cross into an interrupt context:
2969         */
2970        if (depth) {
2971                struct held_lock *prev_hlock;
2972
2973                prev_hlock = curr->held_locks + depth-1;
2974                /*
2975                 * If we cross into another context, reset the
2976                 * hash key (this also prevents the checking and the
2977                 * adding of the dependency to 'prev'):
2978                 */
2979                if (prev_hlock->irq_context != hlock->irq_context)
2980                        return 1;
2981        }
2982        return 0;
2983}
2984
2985#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2986
2987static inline
2988int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2989                enum lock_usage_bit new_bit)
2990{
2991        WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2992        return 1;
2993}
2994
2995static inline int mark_irqflags(struct task_struct *curr,
2996                struct held_lock *hlock)
2997{
2998        return 1;
2999}
3000
3001static inline unsigned int task_irq_context(struct task_struct *task)
3002{
3003        return 0;
3004}
3005
3006static inline int separate_irq_context(struct task_struct *curr,
3007                struct held_lock *hlock)
3008{
3009        return 0;
3010}
3011
3012void lockdep_trace_alloc(gfp_t gfp_mask)
3013{
3014}
3015
3016#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3017
3018/*
3019 * Mark a lock with a usage bit, and validate the state transition:
3020 */
3021static int mark_lock(struct task_struct *curr, struct held_lock *this,
3022                             enum lock_usage_bit new_bit)
3023{
3024        unsigned int new_mask = 1 << new_bit, ret = 1;
3025
3026        /*
3027         * If already set then do not dirty the cacheline,
3028         * nor do any checks:
3029         */
3030        if (likely(hlock_class(this)->usage_mask & new_mask))
3031                return 1;
3032
3033        if (!graph_lock())
3034                return 0;
3035        /*
3036         * Make sure we didn't race:
3037         */
3038        if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3039                graph_unlock();
3040                return 1;
3041        }
3042
3043        hlock_class(this)->usage_mask |= new_mask;
3044
3045        if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3046                return 0;
3047
3048        switch (new_bit) {
3049#define LOCKDEP_STATE(__STATE)                  \
3050        case LOCK_USED_IN_##__STATE:            \
3051        case LOCK_USED_IN_##__STATE##_READ:     \
3052        case LOCK_ENABLED_##__STATE:            \
3053        case LOCK_ENABLED_##__STATE##_READ:
3054#include "lockdep_states.h"
3055#undef LOCKDEP_STATE
3056                ret = mark_lock_irq(curr, this, new_bit);
3057                if (!ret)
3058                        return 0;
3059                break;
3060        case LOCK_USED:
3061                debug_atomic_dec(nr_unused_locks);
3062                break;
3063        default:
3064                if (!debug_locks_off_graph_unlock())
3065                        return 0;
3066                WARN_ON(1);
3067                return 0;
3068        }
3069
3070        graph_unlock();
3071
3072        /*
3073         * We must printk outside of the graph_lock:
3074         */
3075        if (ret == 2) {
3076                printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3077                print_lock(this);
3078                print_irqtrace_events(curr);
3079                dump_stack();
3080        }
3081
3082        return ret;
3083}
3084
3085/*
3086 * Initialize a lock instance's lock-class mapping info:
3087 */
3088void lockdep_init_map(struct lockdep_map *lock, const char *name,
3089                      struct lock_class_key *key, int subclass)
3090{
3091        int i;
3092
3093        kmemcheck_mark_initialized(lock, sizeof(*lock));
3094
3095        for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3096                lock->class_cache[i] = NULL;
3097
3098#ifdef CONFIG_LOCK_STAT
3099        lock->cpu = raw_smp_processor_id();
3100#endif
3101
3102        /*
3103         * Can't be having no nameless bastards around this place!
3104         */
3105        if (DEBUG_LOCKS_WARN_ON(!name)) {
3106                lock->name = "NULL";
3107                return;
3108        }
3109
3110        lock->name = name;
3111
3112        /*
3113         * No key, no joy, we need to hash something.
3114         */
3115        if (DEBUG_LOCKS_WARN_ON(!key))
3116                return;
3117        /*
3118         * Sanity check, the lock-class key must be persistent:
3119         */
3120        if (!static_obj(key)) {
3121                printk("BUG: key %p not in .data!\n", key);
3122                /*
3123                 * What it says above ^^^^^, I suggest you read it.
3124                 */
3125                DEBUG_LOCKS_WARN_ON(1);
3126                return;
3127        }
3128        lock->key = key;
3129
3130        if (unlikely(!debug_locks))
3131                return;
3132
3133        if (subclass) {
3134                unsigned long flags;
3135
3136                if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3137                        return;
3138
3139                raw_local_irq_save(flags);
3140                current->lockdep_recursion = 1;
3141                register_lock_class(lock, subclass, 1);
3142                current->lockdep_recursion = 0;
3143                raw_local_irq_restore(flags);
3144        }
3145}
3146EXPORT_SYMBOL_GPL(lockdep_init_map);
3147
3148struct lock_class_key __lockdep_no_validate__;
3149EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3150
3151static int
3152print_lock_nested_lock_not_held(struct task_struct *curr,
3153                                struct held_lock *hlock,
3154                                unsigned long ip)
3155{
3156        if (!debug_locks_off())
3157                return 0;
3158        if (debug_locks_silent)
3159                return 0;
3160
3161        printk("\n");
3162        printk("==================================\n");
3163        printk("[ BUG: Nested lock was not taken ]\n");
3164        print_kernel_ident();
3165        printk("----------------------------------\n");
3166
3167        printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3168        print_lock(hlock);
3169
3170        printk("\nbut this task is not holding:\n");
3171        printk("%s\n", hlock->nest_lock->name);
3172
3173        printk("\nstack backtrace:\n");
3174        dump_stack();
3175
3176        printk("\nother info that might help us debug this:\n");
3177        lockdep_print_held_locks(curr);
3178
3179        printk("\nstack backtrace:\n");
3180        dump_stack();
3181
3182        return 0;
3183}
3184
3185static int __lock_is_held(struct lockdep_map *lock);
3186
3187/*
3188 * This gets called for every mutex_lock*()/spin_lock*() operation.
3189 * We maintain the dependency maps and validate the locking attempt:
3190 */
3191static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3192                          int trylock, int read, int check, int hardirqs_off,
3193                          struct lockdep_map *nest_lock, unsigned long ip,
3194                          int references, int pin_count)
3195{
3196        struct task_struct *curr = current;
3197        struct lock_class *class = NULL;
3198        struct held_lock *hlock;
3199        unsigned int depth;
3200        int chain_head = 0;
3201        int class_idx;
3202        u64 chain_key;
3203
3204        if (unlikely(!debug_locks))
3205                return 0;
3206
3207        /*
3208         * Lockdep should run with IRQs disabled, otherwise we could
3209         * get an interrupt which would want to take locks, which would
3210         * end up in lockdep and have you got a head-ache already?
3211         */
3212        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3213                return 0;
3214
3215        if (!prove_locking || lock->key == &__lockdep_no_validate__)
3216                check = 0;
3217
3218        if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3219                class = lock->class_cache[subclass];
3220        /*
3221         * Not cached?
3222         */
3223        if (unlikely(!class)) {
3224                class = register_lock_class(lock, subclass, 0);
3225                if (!class)
3226                        return 0;
3227        }
3228        atomic_inc((atomic_t *)&class->ops);
3229        if (very_verbose(class)) {
3230                printk("\nacquire class [%p] %s", class->key, class->name);
3231                if (class->name_version > 1)
3232                        printk("#%d", class->name_version);
3233                printk("\n");
3234                dump_stack();
3235        }
3236
3237        /*
3238         * Add the lock to the list of currently held locks.
3239         * (we dont increase the depth just yet, up until the
3240         * dependency checks are done)
3241         */
3242        depth = curr->lockdep_depth;
3243        /*
3244         * Ran out of static storage for our per-task lock stack again have we?
3245         */
3246        if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3247                return 0;
3248
3249        class_idx = class - lock_classes + 1;
3250
3251        if (depth) {
3252                hlock = curr->held_locks + depth - 1;
3253                if (hlock->class_idx == class_idx && nest_lock) {
3254                        if (hlock->references)
3255                                hlock->references++;
3256                        else
3257                                hlock->references = 2;
3258
3259                        return 1;
3260                }
3261        }
3262
3263        hlock = curr->held_locks + depth;
3264        /*
3265         * Plain impossible, we just registered it and checked it weren't no
3266         * NULL like.. I bet this mushroom I ate was good!
3267         */
3268        if (DEBUG_LOCKS_WARN_ON(!class))
3269                return 0;
3270        hlock->class_idx = class_idx;
3271        hlock->acquire_ip = ip;
3272        hlock->instance = lock;
3273        hlock->nest_lock = nest_lock;
3274        hlock->irq_context = task_irq_context(curr);
3275        hlock->trylock = trylock;
3276        hlock->read = read;
3277        hlock->check = check;
3278        hlock->hardirqs_off = !!hardirqs_off;
3279        hlock->references = references;
3280#ifdef CONFIG_LOCK_STAT
3281        hlock->waittime_stamp = 0;
3282        hlock->holdtime_stamp = lockstat_clock();
3283#endif
3284        hlock->pin_count = pin_count;
3285
3286        if (check && !mark_irqflags(curr, hlock))
3287                return 0;
3288
3289        /* mark it as used: */
3290        if (!mark_lock(curr, hlock, LOCK_USED))
3291                return 0;
3292
3293        /*
3294         * Calculate the chain hash: it's the combined hash of all the
3295         * lock keys along the dependency chain. We save the hash value
3296         * at every step so that we can get the current hash easily
3297         * after unlock. The chain hash is then used to cache dependency
3298         * results.
3299         *
3300         * The 'key ID' is what is the most compact key value to drive
3301         * the hash, not class->key.
3302         */
3303        /*
3304         * Whoops, we did it again.. ran straight out of our static allocation.
3305         */
3306        if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3307                return 0;
3308
3309        chain_key = curr->curr_chain_key;
3310        if (!depth) {
3311                /*
3312                 * How can we have a chain hash when we ain't got no keys?!
3313                 */
3314                if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3315                        return 0;
3316                chain_head = 1;
3317        }
3318
3319        hlock->prev_chain_key = chain_key;
3320        if (separate_irq_context(curr, hlock)) {
3321                chain_key = 0;
3322                chain_head = 1;
3323        }
3324        chain_key = iterate_chain_key(chain_key, class_idx);
3325
3326        if (nest_lock && !__lock_is_held(nest_lock))
3327                return print_lock_nested_lock_not_held(curr, hlock, ip);
3328
3329        if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3330                return 0;
3331
3332        curr->curr_chain_key = chain_key;
3333        curr->lockdep_depth++;
3334        check_chain_key(curr);
3335#ifdef CONFIG_DEBUG_LOCKDEP
3336        if (unlikely(!debug_locks))
3337                return 0;
3338#endif
3339        if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3340                debug_locks_off();
3341                print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3342                printk(KERN_DEBUG "depth: %i  max: %lu!\n",
3343                       curr->lockdep_depth, MAX_LOCK_DEPTH);
3344
3345                lockdep_print_held_locks(current);
3346                debug_show_all_locks();
3347                dump_stack();
3348
3349                return 0;
3350        }
3351
3352        if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3353                max_lockdep_depth = curr->lockdep_depth;
3354
3355        return 1;
3356}
3357
3358static int
3359print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3360                           unsigned long ip)
3361{
3362        if (!debug_locks_off())
3363                return 0;
3364        if (debug_locks_silent)
3365                return 0;
3366
3367        printk("\n");
3368        printk("=====================================\n");
3369        printk("[ BUG: bad unlock balance detected! ]\n");
3370        print_kernel_ident();
3371        printk("-------------------------------------\n");
3372        printk("%s/%d is trying to release lock (",
3373                curr->comm, task_pid_nr(curr));
3374        print_lockdep_cache(lock);
3375        printk(") at:\n");
3376        print_ip_sym(ip);
3377        printk("but there are no more locks to release!\n");
3378        printk("\nother info that might help us debug this:\n");
3379        lockdep_print_held_locks(curr);
3380
3381        printk("\nstack backtrace:\n");
3382        dump_stack();
3383
3384        return 0;
3385}
3386
3387static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3388{
3389        if (hlock->instance == lock)
3390                return 1;
3391
3392        if (hlock->references) {
3393                struct lock_class *class = lock->class_cache[0];
3394
3395                if (!class)
3396                        class = look_up_lock_class(lock, 0);
3397
3398                /*
3399                 * If look_up_lock_class() failed to find a class, we're trying
3400                 * to test if we hold a lock that has never yet been acquired.
3401                 * Clearly if the lock hasn't been acquired _ever_, we're not
3402                 * holding it either, so report failure.
3403                 */
3404                if (!class)
3405                        return 0;
3406
3407                /*
3408                 * References, but not a lock we're actually ref-counting?
3409                 * State got messed up, follow the sites that change ->references
3410                 * and try to make sense of it.
3411                 */
3412                if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3413                        return 0;
3414
3415                if (hlock->class_idx == class - lock_classes + 1)
3416                        return 1;
3417        }
3418
3419        return 0;
3420}
3421
3422static int
3423__lock_set_class(struct lockdep_map *lock, const char *name,
3424                 struct lock_class_key *key, unsigned int subclass,
3425                 unsigned long ip)
3426{
3427        struct task_struct *curr = current;
3428        struct held_lock *hlock, *prev_hlock;
3429        struct lock_class *class;
3430        unsigned int depth;
3431        int i;
3432
3433        depth = curr->lockdep_depth;
3434        /*
3435         * This function is about (re)setting the class of a held lock,
3436         * yet we're not actually holding any locks. Naughty user!
3437         */
3438        if (DEBUG_LOCKS_WARN_ON(!depth))
3439                return 0;
3440
3441        prev_hlock = NULL;
3442        for (i = depth-1; i >= 0; i--) {
3443                hlock = curr->held_locks + i;
3444                /*
3445                 * We must not cross into another context:
3446                 */
3447                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3448                        break;
3449                if (match_held_lock(hlock, lock))
3450                        goto found_it;
3451                prev_hlock = hlock;
3452        }
3453        return print_unlock_imbalance_bug(curr, lock, ip);
3454
3455found_it:
3456        lockdep_init_map(lock, name, key, 0);
3457        class = register_lock_class(lock, subclass, 0);
3458        hlock->class_idx = class - lock_classes + 1;
3459
3460        curr->lockdep_depth = i;
3461        curr->curr_chain_key = hlock->prev_chain_key;
3462
3463        for (; i < depth; i++) {
3464                hlock = curr->held_locks + i;
3465                if (!__lock_acquire(hlock->instance,
3466                        hlock_class(hlock)->subclass, hlock->trylock,
3467                                hlock->read, hlock->check, hlock->hardirqs_off,
3468                                hlock->nest_lock, hlock->acquire_ip,
3469                                hlock->references, hlock->pin_count))
3470                        return 0;
3471        }
3472
3473        /*
3474         * I took it apart and put it back together again, except now I have
3475         * these 'spare' parts.. where shall I put them.
3476         */
3477        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3478                return 0;
3479        return 1;
3480}
3481
3482/*
3483 * Remove the lock to the list of currently held locks - this gets
3484 * called on mutex_unlock()/spin_unlock*() (or on a failed
3485 * mutex_lock_interruptible()).
3486 *
3487 * @nested is an hysterical artifact, needs a tree wide cleanup.
3488 */
3489static int
3490__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3491{
3492        struct task_struct *curr = current;
3493        struct held_lock *hlock, *prev_hlock;
3494        unsigned int depth;
3495        int i;
3496
3497        if (unlikely(!debug_locks))
3498                return 0;
3499
3500        depth = curr->lockdep_depth;
3501        /*
3502         * So we're all set to release this lock.. wait what lock? We don't
3503         * own any locks, you've been drinking again?
3504         */
3505        if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3506                 return print_unlock_imbalance_bug(curr, lock, ip);
3507
3508        /*
3509         * Check whether the lock exists in the current stack
3510         * of held locks:
3511         */
3512        prev_hlock = NULL;
3513        for (i = depth-1; i >= 0; i--) {
3514                hlock = curr->held_locks + i;
3515                /*
3516                 * We must not cross into another context:
3517                 */
3518                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3519                        break;
3520                if (match_held_lock(hlock, lock))
3521                        goto found_it;
3522                prev_hlock = hlock;
3523        }
3524        return print_unlock_imbalance_bug(curr, lock, ip);
3525
3526found_it:
3527        if (hlock->instance == lock)
3528                lock_release_holdtime(hlock);
3529
3530        WARN(hlock->pin_count, "releasing a pinned lock\n");
3531
3532        if (hlock->references) {
3533                hlock->references--;
3534                if (hlock->references) {
3535                        /*
3536                         * We had, and after removing one, still have
3537                         * references, the current lock stack is still
3538                         * valid. We're done!
3539                         */
3540                        return 1;
3541                }
3542        }
3543
3544        /*
3545         * We have the right lock to unlock, 'hlock' points to it.
3546         * Now we remove it from the stack, and add back the other
3547         * entries (if any), recalculating the hash along the way:
3548         */
3549
3550        curr->lockdep_depth = i;
3551        curr->curr_chain_key = hlock->prev_chain_key;
3552
3553        for (i++; i < depth; i++) {
3554                hlock = curr->held_locks + i;
3555                if (!__lock_acquire(hlock->instance,
3556                        hlock_class(hlock)->subclass, hlock->trylock,
3557                                hlock->read, hlock->check, hlock->hardirqs_off,
3558                                hlock->nest_lock, hlock->acquire_ip,
3559                                hlock->references, hlock->pin_count))
3560                        return 0;
3561        }
3562
3563        /*
3564         * We had N bottles of beer on the wall, we drank one, but now
3565         * there's not N-1 bottles of beer left on the wall...
3566         */
3567        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3568                return 0;
3569
3570        return 1;
3571}
3572
3573static int __lock_is_held(struct lockdep_map *lock)
3574{
3575        struct task_struct *curr = current;
3576        int i;
3577
3578        for (i = 0; i < curr->lockdep_depth; i++) {
3579                struct held_lock *hlock = curr->held_locks + i;
3580
3581                if (match_held_lock(hlock, lock))
3582                        return 1;
3583        }
3584
3585        return 0;
3586}
3587
3588static void __lock_pin_lock(struct lockdep_map *lock)
3589{
3590        struct task_struct *curr = current;
3591        int i;
3592
3593        if (unlikely(!debug_locks))
3594                return;
3595
3596        for (i = 0; i < curr->lockdep_depth; i++) {
3597                struct held_lock *hlock = curr->held_locks + i;
3598
3599                if (match_held_lock(hlock, lock)) {
3600                        hlock->pin_count++;
3601                        return;
3602                }
3603        }
3604
3605        WARN(1, "pinning an unheld lock\n");
3606}
3607
3608static void __lock_unpin_lock(struct lockdep_map *lock)
3609{
3610        struct task_struct *curr = current;
3611        int i;
3612
3613        if (unlikely(!debug_locks))
3614                return;
3615
3616        for (i = 0; i < curr->lockdep_depth; i++) {
3617                struct held_lock *hlock = curr->held_locks + i;
3618
3619                if (match_held_lock(hlock, lock)) {
3620                        if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3621                                return;
3622
3623                        hlock->pin_count--;
3624                        return;
3625                }
3626        }
3627
3628        WARN(1, "unpinning an unheld lock\n");
3629}
3630
3631/*
3632 * Check whether we follow the irq-flags state precisely:
3633 */
3634static void check_flags(unsigned long flags)
3635{
3636#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3637    defined(CONFIG_TRACE_IRQFLAGS)
3638        if (!debug_locks)
3639                return;
3640
3641        if (irqs_disabled_flags(flags)) {
3642                if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3643                        printk("possible reason: unannotated irqs-off.\n");
3644                }
3645        } else {
3646                if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3647                        printk("possible reason: unannotated irqs-on.\n");
3648                }
3649        }
3650
3651        /*
3652         * We dont accurately track softirq state in e.g.
3653         * hardirq contexts (such as on 4KSTACKS), so only
3654         * check if not in hardirq contexts:
3655         */
3656        if (!hardirq_count()) {
3657                if (softirq_count()) {
3658                        /* like the above, but with softirqs */
3659                        DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3660                } else {
3661                        /* lick the above, does it taste good? */
3662                        DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3663                }
3664        }
3665
3666        if (!debug_locks)
3667                print_irqtrace_events(current);
3668#endif
3669}
3670
3671void lock_set_class(struct lockdep_map *lock, const char *name,
3672                    struct lock_class_key *key, unsigned int subclass,
3673                    unsigned long ip)
3674{
3675        unsigned long flags;
3676
3677        if (unlikely(current->lockdep_recursion))
3678                return;
3679
3680        raw_local_irq_save(flags);
3681        current->lockdep_recursion = 1;
3682        check_flags(flags);
3683        if (__lock_set_class(lock, name, key, subclass, ip))
3684                check_chain_key(current);
3685        current->lockdep_recursion = 0;
3686        raw_local_irq_restore(flags);
3687}
3688EXPORT_SYMBOL_GPL(lock_set_class);
3689
3690/*
3691 * We are not always called with irqs disabled - do that here,
3692 * and also avoid lockdep recursion:
3693 */
3694void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3695                          int trylock, int read, int check,
3696                          struct lockdep_map *nest_lock, unsigned long ip)
3697{
3698        unsigned long flags;
3699
3700        if (unlikely(current->lockdep_recursion))
3701                return;
3702
3703        raw_local_irq_save(flags);
3704        check_flags(flags);
3705
3706        current->lockdep_recursion = 1;
3707        trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3708        __lock_acquire(lock, subclass, trylock, read, check,
3709                       irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3710        current->lockdep_recursion = 0;
3711        raw_local_irq_restore(flags);
3712}
3713EXPORT_SYMBOL_GPL(lock_acquire);
3714
3715void lock_release(struct lockdep_map *lock, int nested,
3716                          unsigned long ip)
3717{
3718        unsigned long flags;
3719
3720        if (unlikely(current->lockdep_recursion))
3721                return;
3722
3723        raw_local_irq_save(flags);
3724        check_flags(flags);
3725        current->lockdep_recursion = 1;
3726        trace_lock_release(lock, ip);
3727        if (__lock_release(lock, nested, ip))
3728                check_chain_key(current);
3729        current->lockdep_recursion = 0;
3730        raw_local_irq_restore(flags);
3731}
3732EXPORT_SYMBOL_GPL(lock_release);
3733
3734int lock_is_held(struct lockdep_map *lock)
3735{
3736        unsigned long flags;
3737        int ret = 0;
3738
3739        if (unlikely(current->lockdep_recursion))
3740                return 1; /* avoid false negative lockdep_assert_held() */
3741
3742        raw_local_irq_save(flags);
3743        check_flags(flags);
3744
3745        current->lockdep_recursion = 1;
3746        ret = __lock_is_held(lock);
3747        current->lockdep_recursion = 0;
3748        raw_local_irq_restore(flags);
3749
3750        return ret;
3751}
3752EXPORT_SYMBOL_GPL(lock_is_held);
3753
3754void lock_pin_lock(struct lockdep_map *lock)
3755{
3756        unsigned long flags;
3757
3758        if (unlikely(current->lockdep_recursion))
3759                return;
3760
3761        raw_local_irq_save(flags);
3762        check_flags(flags);
3763
3764        current->lockdep_recursion = 1;
3765        __lock_pin_lock(lock);
3766        current->lockdep_recursion = 0;
3767        raw_local_irq_restore(flags);
3768}
3769EXPORT_SYMBOL_GPL(lock_pin_lock);
3770
3771void lock_unpin_lock(struct lockdep_map *lock)
3772{
3773        unsigned long flags;
3774
3775        if (unlikely(current->lockdep_recursion))
3776                return;
3777
3778        raw_local_irq_save(flags);
3779        check_flags(flags);
3780
3781        current->lockdep_recursion = 1;
3782        __lock_unpin_lock(lock);
3783        current->lockdep_recursion = 0;
3784        raw_local_irq_restore(flags);
3785}
3786EXPORT_SYMBOL_GPL(lock_unpin_lock);
3787
3788void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3789{
3790        current->lockdep_reclaim_gfp = gfp_mask;
3791}
3792
3793void lockdep_clear_current_reclaim_state(void)
3794{
3795        current->lockdep_reclaim_gfp = 0;
3796}
3797
3798#ifdef CONFIG_LOCK_STAT
3799static int
3800print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3801                           unsigned long ip)
3802{
3803        if (!debug_locks_off())
3804                return 0;
3805        if (debug_locks_silent)
3806                return 0;
3807
3808        printk("\n");
3809        printk("=================================\n");
3810        printk("[ BUG: bad contention detected! ]\n");
3811        print_kernel_ident();
3812        printk("---------------------------------\n");
3813        printk("%s/%d is trying to contend lock (",
3814                curr->comm, task_pid_nr(curr));
3815        print_lockdep_cache(lock);
3816        printk(") at:\n");
3817        print_ip_sym(ip);
3818        printk("but there are no locks held!\n");
3819        printk("\nother info that might help us debug this:\n");
3820        lockdep_print_held_locks(curr);
3821
3822        printk("\nstack backtrace:\n");
3823        dump_stack();
3824
3825        return 0;
3826}
3827
3828static void
3829__lock_contended(struct lockdep_map *lock, unsigned long ip)
3830{
3831        struct task_struct *curr = current;
3832        struct held_lock *hlock, *prev_hlock;
3833        struct lock_class_stats *stats;
3834        unsigned int depth;
3835        int i, contention_point, contending_point;
3836
3837        depth = curr->lockdep_depth;
3838        /*
3839         * Whee, we contended on this lock, except it seems we're not
3840         * actually trying to acquire anything much at all..
3841         */
3842        if (DEBUG_LOCKS_WARN_ON(!depth))
3843                return;
3844
3845        prev_hlock = NULL;
3846        for (i = depth-1; i >= 0; i--) {
3847                hlock = curr->held_locks + i;
3848                /*
3849                 * We must not cross into another context:
3850                 */
3851                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3852                        break;
3853                if (match_held_lock(hlock, lock))
3854                        goto found_it;
3855                prev_hlock = hlock;
3856        }
3857        print_lock_contention_bug(curr, lock, ip);
3858        return;
3859
3860found_it:
3861        if (hlock->instance != lock)
3862                return;
3863
3864        hlock->waittime_stamp = lockstat_clock();
3865
3866        contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3867        contending_point = lock_point(hlock_class(hlock)->contending_point,
3868                                      lock->ip);
3869
3870        stats = get_lock_stats(hlock_class(hlock));
3871        if (contention_point < LOCKSTAT_POINTS)
3872                stats->contention_point[contention_point]++;
3873        if (contending_point < LOCKSTAT_POINTS)
3874                stats->contending_point[contending_point]++;
3875        if (lock->cpu != smp_processor_id())
3876                stats->bounces[bounce_contended + !!hlock->read]++;
3877        put_lock_stats(stats);
3878}
3879
3880static void
3881__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3882{
3883        struct task_struct *curr = current;
3884        struct held_lock *hlock, *prev_hlock;
3885        struct lock_class_stats *stats;
3886        unsigned int depth;
3887        u64 now, waittime = 0;
3888        int i, cpu;
3889
3890        depth = curr->lockdep_depth;
3891        /*
3892         * Yay, we acquired ownership of this lock we didn't try to
3893         * acquire, how the heck did that happen?
3894         */
3895        if (DEBUG_LOCKS_WARN_ON(!depth))
3896                return;
3897
3898        prev_hlock = NULL;
3899        for (i = depth-1; i >= 0; i--) {
3900                hlock = curr->held_locks + i;
3901                /*
3902                 * We must not cross into another context:
3903                 */
3904                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3905                        break;
3906                if (match_held_lock(hlock, lock))
3907                        goto found_it;
3908                prev_hlock = hlock;
3909        }
3910        print_lock_contention_bug(curr, lock, _RET_IP_);
3911        return;
3912
3913found_it:
3914        if (hlock->instance != lock)
3915                return;
3916
3917        cpu = smp_processor_id();
3918        if (hlock->waittime_stamp) {
3919                now = lockstat_clock();
3920                waittime = now - hlock->waittime_stamp;
3921                hlock->holdtime_stamp = now;
3922        }
3923
3924        trace_lock_acquired(lock, ip);
3925
3926        stats = get_lock_stats(hlock_class(hlock));
3927        if (waittime) {
3928                if (hlock->read)
3929                        lock_time_inc(&stats->read_waittime, waittime);
3930                else
3931                        lock_time_inc(&stats->write_waittime, waittime);
3932        }
3933        if (lock->cpu != cpu)
3934                stats->bounces[bounce_acquired + !!hlock->read]++;
3935        put_lock_stats(stats);
3936
3937        lock->cpu = cpu;
3938        lock->ip = ip;
3939}
3940
3941void lock_contended(struct lockdep_map *lock, unsigned long ip)
3942{
3943        unsigned long flags;
3944
3945        if (unlikely(!lock_stat))
3946                return;
3947
3948        if (unlikely(current->lockdep_recursion))
3949                return;
3950
3951        raw_local_irq_save(flags);
3952        check_flags(flags);
3953        current->lockdep_recursion = 1;
3954        trace_lock_contended(lock, ip);
3955        __lock_contended(lock, ip);
3956        current->lockdep_recursion = 0;
3957        raw_local_irq_restore(flags);
3958}
3959EXPORT_SYMBOL_GPL(lock_contended);
3960
3961void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3962{
3963        unsigned long flags;
3964
3965        if (unlikely(!lock_stat))
3966                return;
3967
3968        if (unlikely(current->lockdep_recursion))
3969                return;
3970
3971        raw_local_irq_save(flags);
3972        check_flags(flags);
3973        current->lockdep_recursion = 1;
3974        __lock_acquired(lock, ip);
3975        current->lockdep_recursion = 0;
3976        raw_local_irq_restore(flags);
3977}
3978EXPORT_SYMBOL_GPL(lock_acquired);
3979#endif
3980
3981/*
3982 * Used by the testsuite, sanitize the validator state
3983 * after a simulated failure:
3984 */
3985
3986void lockdep_reset(void)
3987{
3988        unsigned long flags;
3989        int i;
3990
3991        raw_local_irq_save(flags);
3992        current->curr_chain_key = 0;
3993        current->lockdep_depth = 0;
3994        current->lockdep_recursion = 0;
3995        memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3996        nr_hardirq_chains = 0;
3997        nr_softirq_chains = 0;
3998        nr_process_chains = 0;
3999        debug_locks = 1;
4000        for (i = 0; i < CHAINHASH_SIZE; i++)
4001                INIT_HLIST_HEAD(chainhash_table + i);
4002        raw_local_irq_restore(flags);
4003}
4004
4005static void zap_class(struct lock_class *class)
4006{
4007        int i;
4008
4009        /*
4010         * Remove all dependencies this lock is
4011         * involved in:
4012         */
4013        for (i = 0; i < nr_list_entries; i++) {
4014                if (list_entries[i].class == class)
4015                        list_del_rcu(&list_entries[i].entry);
4016        }
4017        /*
4018         * Unhash the class and remove it from the all_lock_classes list:
4019         */
4020        hlist_del_rcu(&class->hash_entry);
4021        list_del_rcu(&class->lock_entry);
4022
4023        RCU_INIT_POINTER(class->key, NULL);
4024        RCU_INIT_POINTER(class->name, NULL);
4025}
4026
4027static inline int within(const void *addr, void *start, unsigned long size)
4028{
4029        return addr >= start && addr < start + size;
4030}
4031
4032/*
4033 * Used in module.c to remove lock classes from memory that is going to be
4034 * freed; and possibly re-used by other modules.
4035 *
4036 * We will have had one sync_sched() before getting here, so we're guaranteed
4037 * nobody will look up these exact classes -- they're properly dead but still
4038 * allocated.
4039 */
4040void lockdep_free_key_range(void *start, unsigned long size)
4041{
4042        struct lock_class *class;
4043        struct hlist_head *head;
4044        unsigned long flags;
4045        int i;
4046        int locked;
4047
4048        raw_local_irq_save(flags);
4049        locked = graph_lock();
4050
4051        /*
4052         * Unhash all classes that were created by this module:
4053         */
4054        for (i = 0; i < CLASSHASH_SIZE; i++) {
4055                head = classhash_table + i;
4056                hlist_for_each_entry_rcu(class, head, hash_entry) {
4057                        if (within(class->key, start, size))
4058                                zap_class(class);
4059                        else if (within(class->name, start, size))
4060                                zap_class(class);
4061                }
4062        }
4063
4064        if (locked)
4065                graph_unlock();
4066        raw_local_irq_restore(flags);
4067
4068        /*
4069         * Wait for any possible iterators from look_up_lock_class() to pass
4070         * before continuing to free the memory they refer to.
4071         *
4072         * sync_sched() is sufficient because the read-side is IRQ disable.
4073         */
4074        synchronize_sched();
4075
4076        /*
4077         * XXX at this point we could return the resources to the pool;
4078         * instead we leak them. We would need to change to bitmap allocators
4079         * instead of the linear allocators we have now.
4080         */
4081}
4082
4083void lockdep_reset_lock(struct lockdep_map *lock)
4084{
4085        struct lock_class *class;
4086        struct hlist_head *head;
4087        unsigned long flags;
4088        int i, j;
4089        int locked;
4090
4091        raw_local_irq_save(flags);
4092
4093        /*
4094         * Remove all classes this lock might have:
4095         */
4096        for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4097                /*
4098                 * If the class exists we look it up and zap it:
4099                 */
4100                class = look_up_lock_class(lock, j);
4101                if (class)
4102                        zap_class(class);
4103        }
4104        /*
4105         * Debug check: in the end all mapped classes should
4106         * be gone.
4107         */
4108        locked = graph_lock();
4109        for (i = 0; i < CLASSHASH_SIZE; i++) {
4110                head = classhash_table + i;
4111                hlist_for_each_entry_rcu(class, head, hash_entry) {
4112                        int match = 0;
4113
4114                        for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4115                                match |= class == lock->class_cache[j];
4116
4117                        if (unlikely(match)) {
4118                                if (debug_locks_off_graph_unlock()) {
4119                                        /*
4120                                         * We all just reset everything, how did it match?
4121                                         */
4122                                        WARN_ON(1);
4123                                }
4124                                goto out_restore;
4125                        }
4126                }
4127        }
4128        if (locked)
4129                graph_unlock();
4130
4131out_restore:
4132        raw_local_irq_restore(flags);
4133}
4134
4135void __init lockdep_info(void)
4136{
4137        printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4138
4139        printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
4140        printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
4141        printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
4142        printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
4143        printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
4144        printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
4145        printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
4146
4147        printk(" memory used by lock dependency info: %lu kB\n",
4148                (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4149                sizeof(struct list_head) * CLASSHASH_SIZE +
4150                sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4151                sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4152                sizeof(struct list_head) * CHAINHASH_SIZE
4153#ifdef CONFIG_PROVE_LOCKING
4154                + sizeof(struct circular_queue)
4155#endif
4156                ) / 1024
4157                );
4158
4159        printk(" per task-struct memory footprint: %lu bytes\n",
4160                sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4161}
4162
4163static void
4164print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4165                     const void *mem_to, struct held_lock *hlock)
4166{
4167        if (!debug_locks_off())
4168                return;
4169        if (debug_locks_silent)
4170                return;
4171
4172        printk("\n");
4173        printk("=========================\n");
4174        printk("[ BUG: held lock freed! ]\n");
4175        print_kernel_ident();
4176        printk("-------------------------\n");
4177        printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4178                curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4179        print_lock(hlock);
4180        lockdep_print_held_locks(curr);
4181
4182        printk("\nstack backtrace:\n");
4183        dump_stack();
4184}
4185
4186static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4187                                const void* lock_from, unsigned long lock_len)
4188{
4189        return lock_from + lock_len <= mem_from ||
4190                mem_from + mem_len <= lock_from;
4191}
4192
4193/*
4194 * Called when kernel memory is freed (or unmapped), or if a lock
4195 * is destroyed or reinitialized - this code checks whether there is
4196 * any held lock in the memory range of <from> to <to>:
4197 */
4198void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4199{
4200        struct task_struct *curr = current;
4201        struct held_lock *hlock;
4202        unsigned long flags;
4203        int i;
4204
4205        if (unlikely(!debug_locks))
4206                return;
4207
4208        local_irq_save(flags);
4209        for (i = 0; i < curr->lockdep_depth; i++) {
4210                hlock = curr->held_locks + i;
4211
4212                if (not_in_range(mem_from, mem_len, hlock->instance,
4213                                        sizeof(*hlock->instance)))
4214                        continue;
4215
4216                print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4217                break;
4218        }
4219        local_irq_restore(flags);
4220}
4221EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4222
4223static void print_held_locks_bug(void)
4224{
4225        if (!debug_locks_off())
4226                return;
4227        if (debug_locks_silent)
4228                return;
4229
4230        printk("\n");
4231        printk("=====================================\n");
4232        printk("[ BUG: %s/%d still has locks held! ]\n",
4233               current->comm, task_pid_nr(current));
4234        print_kernel_ident();
4235        printk("-------------------------------------\n");
4236        lockdep_print_held_locks(current);
4237        printk("\nstack backtrace:\n");
4238        dump_stack();
4239}
4240
4241void debug_check_no_locks_held(void)
4242{
4243        if (unlikely(current->lockdep_depth > 0))
4244                print_held_locks_bug();
4245}
4246EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4247
4248#ifdef __KERNEL__
4249void debug_show_all_locks(void)
4250{
4251        struct task_struct *g, *p;
4252        int count = 10;
4253        int unlock = 1;
4254
4255        if (unlikely(!debug_locks)) {
4256                printk("INFO: lockdep is turned off.\n");
4257                return;
4258        }
4259        printk("\nShowing all locks held in the system:\n");
4260
4261        /*
4262         * Here we try to get the tasklist_lock as hard as possible,
4263         * if not successful after 2 seconds we ignore it (but keep
4264         * trying). This is to enable a debug printout even if a
4265         * tasklist_lock-holding task deadlocks or crashes.
4266         */
4267retry:
4268        if (!read_trylock(&tasklist_lock)) {
4269                if (count == 10)
4270                        printk("hm, tasklist_lock locked, retrying... ");
4271                if (count) {
4272                        count--;
4273                        printk(" #%d", 10-count);
4274                        mdelay(200);
4275                        goto retry;
4276                }
4277                printk(" ignoring it.\n");
4278                unlock = 0;
4279        } else {
4280                if (count != 10)
4281                        printk(KERN_CONT " locked it.\n");
4282        }
4283
4284        do_each_thread(g, p) {
4285                /*
4286                 * It's not reliable to print a task's held locks
4287                 * if it's not sleeping (or if it's not the current
4288                 * task):
4289                 */
4290                if (p->state == TASK_RUNNING && p != current)
4291                        continue;
4292                if (p->lockdep_depth)
4293                        lockdep_print_held_locks(p);
4294                if (!unlock)
4295                        if (read_trylock(&tasklist_lock))
4296                                unlock = 1;
4297        } while_each_thread(g, p);
4298
4299        printk("\n");
4300        printk("=============================================\n\n");
4301
4302        if (unlock)
4303                read_unlock(&tasklist_lock);
4304}
4305EXPORT_SYMBOL_GPL(debug_show_all_locks);
4306#endif
4307
4308/*
4309 * Careful: only use this function if you are sure that
4310 * the task cannot run in parallel!
4311 */
4312void debug_show_held_locks(struct task_struct *task)
4313{
4314        if (unlikely(!debug_locks)) {
4315                printk("INFO: lockdep is turned off.\n");
4316                return;
4317        }
4318        lockdep_print_held_locks(task);
4319}
4320EXPORT_SYMBOL_GPL(debug_show_held_locks);
4321
4322asmlinkage __visible void lockdep_sys_exit(void)
4323{
4324        struct task_struct *curr = current;
4325
4326        if (unlikely(curr->lockdep_depth)) {
4327                if (!debug_locks_off())
4328                        return;
4329                printk("\n");
4330                printk("================================================\n");
4331                printk("[ BUG: lock held when returning to user space! ]\n");
4332                print_kernel_ident();
4333                printk("------------------------------------------------\n");
4334                printk("%s/%d is leaving the kernel with locks still held!\n",
4335                                curr->comm, curr->pid);
4336                lockdep_print_held_locks(curr);
4337        }
4338}
4339
4340void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4341{
4342        struct task_struct *curr = current;
4343
4344#ifndef CONFIG_PROVE_RCU_REPEATEDLY
4345        if (!debug_locks_off())
4346                return;
4347#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4348        /* Note: the following can be executed concurrently, so be careful. */
4349        printk("\n");
4350        printk("===============================\n");
4351        printk("[ INFO: suspicious RCU usage. ]\n");
4352        print_kernel_ident();
4353        printk("-------------------------------\n");
4354        printk("%s:%d %s!\n", file, line, s);
4355        printk("\nother info that might help us debug this:\n\n");
4356        printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4357               !rcu_lockdep_current_cpu_online()
4358                        ? "RCU used illegally from offline CPU!\n"
4359                        : !rcu_is_watching()
4360                                ? "RCU used illegally from idle CPU!\n"
4361                                : "",
4362               rcu_scheduler_active, debug_locks);
4363
4364        /*
4365         * If a CPU is in the RCU-free window in idle (ie: in the section
4366         * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4367         * considers that CPU to be in an "extended quiescent state",
4368         * which means that RCU will be completely ignoring that CPU.
4369         * Therefore, rcu_read_lock() and friends have absolutely no
4370         * effect on a CPU running in that state. In other words, even if
4371         * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4372         * delete data structures out from under it.  RCU really has no
4373         * choice here: we need to keep an RCU-free window in idle where
4374         * the CPU may possibly enter into low power mode. This way we can
4375         * notice an extended quiescent state to other CPUs that started a grace
4376         * period. Otherwise we would delay any grace period as long as we run
4377         * in the idle task.
4378         *
4379         * So complain bitterly if someone does call rcu_read_lock(),
4380         * rcu_read_lock_bh() and so on from extended quiescent states.
4381         */
4382        if (!rcu_is_watching())
4383                printk("RCU used illegally from extended quiescent state!\n");
4384
4385        lockdep_print_held_locks(curr);
4386        printk("\nstack backtrace:\n");
4387        dump_stack();
4388}
4389EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
4390