linux/kernel/lockdep.c
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   1/*
   2 * kernel/lockdep.c
   3 *
   4 * Runtime locking correctness validator
   5 *
   6 * Started by Ingo Molnar:
   7 *
   8 *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   9 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
  10 *
  11 * this code maps all the lock dependencies as they occur in a live kernel
  12 * and will warn about the following classes of locking bugs:
  13 *
  14 * - lock inversion scenarios
  15 * - circular lock dependencies
  16 * - hardirq/softirq safe/unsafe locking bugs
  17 *
  18 * Bugs are reported even if the current locking scenario does not cause
  19 * any deadlock at this point.
  20 *
  21 * I.e. if anytime in the past two locks were taken in a different order,
  22 * even if it happened for another task, even if those were different
  23 * locks (but of the same class as this lock), this code will detect it.
  24 *
  25 * Thanks to Arjan van de Ven for coming up with the initial idea of
  26 * mapping lock dependencies runtime.
  27 */
  28#define DISABLE_BRANCH_PROFILING
  29#include <linux/mutex.h>
  30#include <linux/sched.h>
  31#include <linux/delay.h>
  32#include <linux/module.h>
  33#include <linux/proc_fs.h>
  34#include <linux/seq_file.h>
  35#include <linux/spinlock.h>
  36#include <linux/kallsyms.h>
  37#include <linux/interrupt.h>
  38#include <linux/stacktrace.h>
  39#include <linux/debug_locks.h>
  40#include <linux/irqflags.h>
  41#include <linux/utsname.h>
  42#include <linux/hash.h>
  43#include <linux/ftrace.h>
  44#include <linux/stringify.h>
  45#include <linux/bitops.h>
  46#include <linux/gfp.h>
  47#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                return DEBUG_LOCKS_WARN_ON(1);
 102
 103        current->lockdep_recursion--;
 104        arch_spin_unlock(&lockdep_lock);
 105        return 0;
 106}
 107
 108/*
 109 * Turn lock debugging off and return with 0 if it was off already,
 110 * and also release the graph lock:
 111 */
 112static inline int debug_locks_off_graph_unlock(void)
 113{
 114        int ret = debug_locks_off();
 115
 116        arch_spin_unlock(&lockdep_lock);
 117
 118        return ret;
 119}
 120
 121static int lockdep_initialized;
 122
 123unsigned long nr_list_entries;
 124static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
 125
 126/*
 127 * All data structures here are protected by the global debug_lock.
 128 *
 129 * Mutex key structs only get allocated, once during bootup, and never
 130 * get freed - this significantly simplifies the debugging code.
 131 */
 132unsigned long nr_lock_classes;
 133static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
 134
 135static inline struct lock_class *hlock_class(struct held_lock *hlock)
 136{
 137        if (!hlock->class_idx) {
 138                DEBUG_LOCKS_WARN_ON(1);
 139                return NULL;
 140        }
 141        return lock_classes + hlock->class_idx - 1;
 142}
 143
 144#ifdef CONFIG_LOCK_STAT
 145static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
 146                      cpu_lock_stats);
 147
 148static inline u64 lockstat_clock(void)
 149{
 150        return local_clock();
 151}
 152
 153static int lock_point(unsigned long points[], unsigned long ip)
 154{
 155        int i;
 156
 157        for (i = 0; i < LOCKSTAT_POINTS; i++) {
 158                if (points[i] == 0) {
 159                        points[i] = ip;
 160                        break;
 161                }
 162                if (points[i] == ip)
 163                        break;
 164        }
 165
 166        return i;
 167}
 168
 169static void lock_time_inc(struct lock_time *lt, u64 time)
 170{
 171        if (time > lt->max)
 172                lt->max = time;
 173
 174        if (time < lt->min || !lt->nr)
 175                lt->min = time;
 176
 177        lt->total += time;
 178        lt->nr++;
 179}
 180
 181static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
 182{
 183        if (!src->nr)
 184                return;
 185
 186        if (src->max > dst->max)
 187                dst->max = src->max;
 188
 189        if (src->min < dst->min || !dst->nr)
 190                dst->min = src->min;
 191
 192        dst->total += src->total;
 193        dst->nr += src->nr;
 194}
 195
 196struct lock_class_stats lock_stats(struct lock_class *class)
 197{
 198        struct lock_class_stats stats;
 199        int cpu, i;
 200
 201        memset(&stats, 0, sizeof(struct lock_class_stats));
 202        for_each_possible_cpu(cpu) {
 203                struct lock_class_stats *pcs =
 204                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
 205
 206                for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
 207                        stats.contention_point[i] += pcs->contention_point[i];
 208
 209                for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
 210                        stats.contending_point[i] += pcs->contending_point[i];
 211
 212                lock_time_add(&pcs->read_waittime, &stats.read_waittime);
 213                lock_time_add(&pcs->write_waittime, &stats.write_waittime);
 214
 215                lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
 216                lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
 217
 218                for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
 219                        stats.bounces[i] += pcs->bounces[i];
 220        }
 221
 222        return stats;
 223}
 224
 225void clear_lock_stats(struct lock_class *class)
 226{
 227        int cpu;
 228
 229        for_each_possible_cpu(cpu) {
 230                struct lock_class_stats *cpu_stats =
 231                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
 232
 233                memset(cpu_stats, 0, sizeof(struct lock_class_stats));
 234        }
 235        memset(class->contention_point, 0, sizeof(class->contention_point));
 236        memset(class->contending_point, 0, sizeof(class->contending_point));
 237}
 238
 239static struct lock_class_stats *get_lock_stats(struct lock_class *class)
 240{
 241        return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
 242}
 243
 244static void put_lock_stats(struct lock_class_stats *stats)
 245{
 246        put_cpu_var(cpu_lock_stats);
 247}
 248
 249static void lock_release_holdtime(struct held_lock *hlock)
 250{
 251        struct lock_class_stats *stats;
 252        u64 holdtime;
 253
 254        if (!lock_stat)
 255                return;
 256
 257        holdtime = lockstat_clock() - hlock->holdtime_stamp;
 258
 259        stats = get_lock_stats(hlock_class(hlock));
 260        if (hlock->read)
 261                lock_time_inc(&stats->read_holdtime, holdtime);
 262        else
 263                lock_time_inc(&stats->write_holdtime, holdtime);
 264        put_lock_stats(stats);
 265}
 266#else
 267static inline void lock_release_holdtime(struct held_lock *hlock)
 268{
 269}
 270#endif
 271
 272/*
 273 * We keep a global list of all lock classes. The list only grows,
 274 * never shrinks. The list is only accessed with the lockdep
 275 * spinlock lock held.
 276 */
 277LIST_HEAD(all_lock_classes);
 278
 279/*
 280 * The lockdep classes are in a hash-table as well, for fast lookup:
 281 */
 282#define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
 283#define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
 284#define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
 285#define classhashentry(key)     (classhash_table + __classhashfn((key)))
 286
 287static struct list_head classhash_table[CLASSHASH_SIZE];
 288
 289/*
 290 * We put the lock dependency chains into a hash-table as well, to cache
 291 * their existence:
 292 */
 293#define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
 294#define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
 295#define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
 296#define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
 297
 298static struct list_head chainhash_table[CHAINHASH_SIZE];
 299
 300/*
 301 * The hash key of the lock dependency chains is a hash itself too:
 302 * it's a hash of all locks taken up to that lock, including that lock.
 303 * It's a 64-bit hash, because it's important for the keys to be
 304 * unique.
 305 */
 306#define iterate_chain_key(key1, key2) \
 307        (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
 308        ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
 309        (key2))
 310
 311void lockdep_off(void)
 312{
 313        current->lockdep_recursion++;
 314}
 315EXPORT_SYMBOL(lockdep_off);
 316
 317void lockdep_on(void)
 318{
 319        current->lockdep_recursion--;
 320}
 321EXPORT_SYMBOL(lockdep_on);
 322
 323/*
 324 * Debugging switches:
 325 */
 326
 327#define VERBOSE                 0
 328#define VERY_VERBOSE            0
 329
 330#if VERBOSE
 331# define HARDIRQ_VERBOSE        1
 332# define SOFTIRQ_VERBOSE        1
 333# define RECLAIM_VERBOSE        1
 334#else
 335# define HARDIRQ_VERBOSE        0
 336# define SOFTIRQ_VERBOSE        0
 337# define RECLAIM_VERBOSE        0
 338#endif
 339
 340#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
 341/*
 342 * Quick filtering for interesting events:
 343 */
 344static int class_filter(struct lock_class *class)
 345{
 346#if 0
 347        /* Example */
 348        if (class->name_version == 1 &&
 349                        !strcmp(class->name, "lockname"))
 350                return 1;
 351        if (class->name_version == 1 &&
 352                        !strcmp(class->name, "&struct->lockfield"))
 353                return 1;
 354#endif
 355        /* Filter everything else. 1 would be to allow everything else */
 356        return 0;
 357}
 358#endif
 359
 360static int verbose(struct lock_class *class)
 361{
 362#if VERBOSE
 363        return class_filter(class);
 364#endif
 365        return 0;
 366}
 367
 368/*
 369 * Stack-trace: tightly packed array of stack backtrace
 370 * addresses. Protected by the graph_lock.
 371 */
 372unsigned long nr_stack_trace_entries;
 373static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
 374
 375static int save_trace(struct stack_trace *trace)
 376{
 377        trace->nr_entries = 0;
 378        trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
 379        trace->entries = stack_trace + nr_stack_trace_entries;
 380
 381        trace->skip = 3;
 382
 383        save_stack_trace(trace);
 384
 385        /*
 386         * Some daft arches put -1 at the end to indicate its a full trace.
 387         *
 388         * <rant> this is buggy anyway, since it takes a whole extra entry so a
 389         * complete trace that maxes out the entries provided will be reported
 390         * as incomplete, friggin useless </rant>
 391         */
 392        if (trace->nr_entries != 0 &&
 393            trace->entries[trace->nr_entries-1] == ULONG_MAX)
 394                trace->nr_entries--;
 395
 396        trace->max_entries = trace->nr_entries;
 397
 398        nr_stack_trace_entries += trace->nr_entries;
 399
 400        if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
 401                if (!debug_locks_off_graph_unlock())
 402                        return 0;
 403
 404                printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
 405                printk("turning off the locking correctness validator.\n");
 406                dump_stack();
 407
 408                return 0;
 409        }
 410
 411        return 1;
 412}
 413
 414unsigned int nr_hardirq_chains;
 415unsigned int nr_softirq_chains;
 416unsigned int nr_process_chains;
 417unsigned int max_lockdep_depth;
 418
 419#ifdef CONFIG_DEBUG_LOCKDEP
 420/*
 421 * We cannot printk in early bootup code. Not even early_printk()
 422 * might work. So we mark any initialization errors and printk
 423 * about it later on, in lockdep_info().
 424 */
 425static int lockdep_init_error;
 426static unsigned long lockdep_init_trace_data[20];
 427static struct stack_trace lockdep_init_trace = {
 428        .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
 429        .entries = lockdep_init_trace_data,
 430};
 431
 432/*
 433 * Various lockdep statistics:
 434 */
 435DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
 436#endif
 437
 438/*
 439 * Locking printouts:
 440 */
 441
 442#define __USAGE(__STATE)                                                \
 443        [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
 444        [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
 445        [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
 446        [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
 447
 448static const char *usage_str[] =
 449{
 450#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
 451#include "lockdep_states.h"
 452#undef LOCKDEP_STATE
 453        [LOCK_USED] = "INITIAL USE",
 454};
 455
 456const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
 457{
 458        return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
 459}
 460
 461static inline unsigned long lock_flag(enum lock_usage_bit bit)
 462{
 463        return 1UL << bit;
 464}
 465
 466static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
 467{
 468        char c = '.';
 469
 470        if (class->usage_mask & lock_flag(bit + 2))
 471                c = '+';
 472        if (class->usage_mask & lock_flag(bit)) {
 473                c = '-';
 474                if (class->usage_mask & lock_flag(bit + 2))
 475                        c = '?';
 476        }
 477
 478        return c;
 479}
 480
 481void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
 482{
 483        int i = 0;
 484
 485#define LOCKDEP_STATE(__STATE)                                          \
 486        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
 487        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
 488#include "lockdep_states.h"
 489#undef LOCKDEP_STATE
 490
 491        usage[i] = '\0';
 492}
 493
 494static int __print_lock_name(struct lock_class *class)
 495{
 496        char str[KSYM_NAME_LEN];
 497        const char *name;
 498
 499        name = class->name;
 500        if (!name)
 501                name = __get_key_name(class->key, str);
 502
 503        return printk("%s", name);
 504}
 505
 506static void print_lock_name(struct lock_class *class)
 507{
 508        char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
 509        const char *name;
 510
 511        get_usage_chars(class, usage);
 512
 513        name = class->name;
 514        if (!name) {
 515                name = __get_key_name(class->key, str);
 516                printk(" (%s", name);
 517        } else {
 518                printk(" (%s", name);
 519                if (class->name_version > 1)
 520                        printk("#%d", class->name_version);
 521                if (class->subclass)
 522                        printk("/%d", class->subclass);
 523        }
 524        printk("){%s}", usage);
 525}
 526
 527static void print_lockdep_cache(struct lockdep_map *lock)
 528{
 529        const char *name;
 530        char str[KSYM_NAME_LEN];
 531
 532        name = lock->name;
 533        if (!name)
 534                name = __get_key_name(lock->key->subkeys, str);
 535
 536        printk("%s", name);
 537}
 538
 539static void print_lock(struct held_lock *hlock)
 540{
 541        print_lock_name(hlock_class(hlock));
 542        printk(", at: ");
 543        print_ip_sym(hlock->acquire_ip);
 544}
 545
 546static void lockdep_print_held_locks(struct task_struct *curr)
 547{
 548        int i, depth = curr->lockdep_depth;
 549
 550        if (!depth) {
 551                printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
 552                return;
 553        }
 554        printk("%d lock%s held by %s/%d:\n",
 555                depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
 556
 557        for (i = 0; i < depth; i++) {
 558                printk(" #%d: ", i);
 559                print_lock(curr->held_locks + i);
 560        }
 561}
 562
 563static void print_kernel_version(void)
 564{
 565        printk("%s %.*s\n", init_utsname()->release,
 566                (int)strcspn(init_utsname()->version, " "),
 567                init_utsname()->version);
 568}
 569
 570static int very_verbose(struct lock_class *class)
 571{
 572#if VERY_VERBOSE
 573        return class_filter(class);
 574#endif
 575        return 0;
 576}
 577
 578/*
 579 * Is this the address of a static object:
 580 */
 581static int static_obj(void *obj)
 582{
 583        unsigned long start = (unsigned long) &_stext,
 584                      end   = (unsigned long) &_end,
 585                      addr  = (unsigned long) obj;
 586
 587        /*
 588         * static variable?
 589         */
 590        if ((addr >= start) && (addr < end))
 591                return 1;
 592
 593        if (arch_is_kernel_data(addr))
 594                return 1;
 595
 596        /*
 597         * in-kernel percpu var?
 598         */
 599        if (is_kernel_percpu_address(addr))
 600                return 1;
 601
 602        /*
 603         * module static or percpu var?
 604         */
 605        return is_module_address(addr) || is_module_percpu_address(addr);
 606}
 607
 608/*
 609 * To make lock name printouts unique, we calculate a unique
 610 * class->name_version generation counter:
 611 */
 612static int count_matching_names(struct lock_class *new_class)
 613{
 614        struct lock_class *class;
 615        int count = 0;
 616
 617        if (!new_class->name)
 618                return 0;
 619
 620        list_for_each_entry(class, &all_lock_classes, lock_entry) {
 621                if (new_class->key - new_class->subclass == class->key)
 622                        return class->name_version;
 623                if (class->name && !strcmp(class->name, new_class->name))
 624                        count = max(count, class->name_version);
 625        }
 626
 627        return count + 1;
 628}
 629
 630/*
 631 * Register a lock's class in the hash-table, if the class is not present
 632 * yet. Otherwise we look it up. We cache the result in the lock object
 633 * itself, so actual lookup of the hash should be once per lock object.
 634 */
 635static inline struct lock_class *
 636look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
 637{
 638        struct lockdep_subclass_key *key;
 639        struct list_head *hash_head;
 640        struct lock_class *class;
 641
 642#ifdef CONFIG_DEBUG_LOCKDEP
 643        /*
 644         * If the architecture calls into lockdep before initializing
 645         * the hashes then we'll warn about it later. (we cannot printk
 646         * right now)
 647         */
 648        if (unlikely(!lockdep_initialized)) {
 649                lockdep_init();
 650                lockdep_init_error = 1;
 651                save_stack_trace(&lockdep_init_trace);
 652        }
 653#endif
 654
 655        if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
 656                debug_locks_off();
 657                printk(KERN_ERR
 658                        "BUG: looking up invalid subclass: %u\n", subclass);
 659                printk(KERN_ERR
 660                        "turning off the locking correctness validator.\n");
 661                dump_stack();
 662                return NULL;
 663        }
 664
 665        /*
 666         * Static locks do not have their class-keys yet - for them the key
 667         * is the lock object itself:
 668         */
 669        if (unlikely(!lock->key))
 670                lock->key = (void *)lock;
 671
 672        /*
 673         * NOTE: the class-key must be unique. For dynamic locks, a static
 674         * lock_class_key variable is passed in through the mutex_init()
 675         * (or spin_lock_init()) call - which acts as the key. For static
 676         * locks we use the lock object itself as the key.
 677         */
 678        BUILD_BUG_ON(sizeof(struct lock_class_key) >
 679                        sizeof(struct lockdep_map));
 680
 681        key = lock->key->subkeys + subclass;
 682
 683        hash_head = classhashentry(key);
 684
 685        /*
 686         * We can walk the hash lockfree, because the hash only
 687         * grows, and we are careful when adding entries to the end:
 688         */
 689        list_for_each_entry(class, hash_head, hash_entry) {
 690                if (class->key == key) {
 691                        WARN_ON_ONCE(class->name != lock->name);
 692                        return class;
 693                }
 694        }
 695
 696        return NULL;
 697}
 698
 699/*
 700 * Register a lock's class in the hash-table, if the class is not present
 701 * yet. Otherwise we look it up. We cache the result in the lock object
 702 * itself, so actual lookup of the hash should be once per lock object.
 703 */
 704static inline struct lock_class *
 705register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 706{
 707        struct lockdep_subclass_key *key;
 708        struct list_head *hash_head;
 709        struct lock_class *class;
 710        unsigned long flags;
 711
 712        class = look_up_lock_class(lock, subclass);
 713        if (likely(class))
 714                return class;
 715
 716        /*
 717         * Debug-check: all keys must be persistent!
 718         */
 719        if (!static_obj(lock->key)) {
 720                debug_locks_off();
 721                printk("INFO: trying to register non-static key.\n");
 722                printk("the code is fine but needs lockdep annotation.\n");
 723                printk("turning off the locking correctness validator.\n");
 724                dump_stack();
 725
 726                return NULL;
 727        }
 728
 729        key = lock->key->subkeys + subclass;
 730        hash_head = classhashentry(key);
 731
 732        raw_local_irq_save(flags);
 733        if (!graph_lock()) {
 734                raw_local_irq_restore(flags);
 735                return NULL;
 736        }
 737        /*
 738         * We have to do the hash-walk again, to avoid races
 739         * with another CPU:
 740         */
 741        list_for_each_entry(class, hash_head, hash_entry)
 742                if (class->key == key)
 743                        goto out_unlock_set;
 744        /*
 745         * Allocate a new key from the static array, and add it to
 746         * the hash:
 747         */
 748        if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
 749                if (!debug_locks_off_graph_unlock()) {
 750                        raw_local_irq_restore(flags);
 751                        return NULL;
 752                }
 753                raw_local_irq_restore(flags);
 754
 755                printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
 756                printk("turning off the locking correctness validator.\n");
 757                dump_stack();
 758                return NULL;
 759        }
 760        class = lock_classes + nr_lock_classes++;
 761        debug_atomic_inc(nr_unused_locks);
 762        class->key = key;
 763        class->name = lock->name;
 764        class->subclass = subclass;
 765        INIT_LIST_HEAD(&class->lock_entry);
 766        INIT_LIST_HEAD(&class->locks_before);
 767        INIT_LIST_HEAD(&class->locks_after);
 768        class->name_version = count_matching_names(class);
 769        /*
 770         * We use RCU's safe list-add method to make
 771         * parallel walking of the hash-list safe:
 772         */
 773        list_add_tail_rcu(&class->hash_entry, hash_head);
 774        /*
 775         * Add it to the global list of classes:
 776         */
 777        list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
 778
 779        if (verbose(class)) {
 780                graph_unlock();
 781                raw_local_irq_restore(flags);
 782
 783                printk("\nnew class %p: %s", class->key, class->name);
 784                if (class->name_version > 1)
 785                        printk("#%d", class->name_version);
 786                printk("\n");
 787                dump_stack();
 788
 789                raw_local_irq_save(flags);
 790                if (!graph_lock()) {
 791                        raw_local_irq_restore(flags);
 792                        return NULL;
 793                }
 794        }
 795out_unlock_set:
 796        graph_unlock();
 797        raw_local_irq_restore(flags);
 798
 799        if (!subclass || force)
 800                lock->class_cache[0] = class;
 801        else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
 802                lock->class_cache[subclass] = class;
 803
 804        if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
 805                return NULL;
 806
 807        return class;
 808}
 809
 810#ifdef CONFIG_PROVE_LOCKING
 811/*
 812 * Allocate a lockdep entry. (assumes the graph_lock held, returns
 813 * with NULL on failure)
 814 */
 815static struct lock_list *alloc_list_entry(void)
 816{
 817        if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
 818                if (!debug_locks_off_graph_unlock())
 819                        return NULL;
 820
 821                printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
 822                printk("turning off the locking correctness validator.\n");
 823                dump_stack();
 824                return NULL;
 825        }
 826        return list_entries + nr_list_entries++;
 827}
 828
 829/*
 830 * Add a new dependency to the head of the list:
 831 */
 832static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
 833                            struct list_head *head, unsigned long ip,
 834                            int distance, struct stack_trace *trace)
 835{
 836        struct lock_list *entry;
 837        /*
 838         * Lock not present yet - get a new dependency struct and
 839         * add it to the list:
 840         */
 841        entry = alloc_list_entry();
 842        if (!entry)
 843                return 0;
 844
 845        entry->class = this;
 846        entry->distance = distance;
 847        entry->trace = *trace;
 848        /*
 849         * Since we never remove from the dependency list, the list can
 850         * be walked lockless by other CPUs, it's only allocation
 851         * that must be protected by the spinlock. But this also means
 852         * we must make new entries visible only once writes to the
 853         * entry become visible - hence the RCU op:
 854         */
 855        list_add_tail_rcu(&entry->entry, head);
 856
 857        return 1;
 858}
 859
 860/*
 861 * For good efficiency of modular, we use power of 2
 862 */
 863#define MAX_CIRCULAR_QUEUE_SIZE         4096UL
 864#define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
 865
 866/*
 867 * The circular_queue and helpers is used to implement the
 868 * breadth-first search(BFS)algorithem, by which we can build
 869 * the shortest path from the next lock to be acquired to the
 870 * previous held lock if there is a circular between them.
 871 */
 872struct circular_queue {
 873        unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
 874        unsigned int  front, rear;
 875};
 876
 877static struct circular_queue lock_cq;
 878
 879unsigned int max_bfs_queue_depth;
 880
 881static unsigned int lockdep_dependency_gen_id;
 882
 883static inline void __cq_init(struct circular_queue *cq)
 884{
 885        cq->front = cq->rear = 0;
 886        lockdep_dependency_gen_id++;
 887}
 888
 889static inline int __cq_empty(struct circular_queue *cq)
 890{
 891        return (cq->front == cq->rear);
 892}
 893
 894static inline int __cq_full(struct circular_queue *cq)
 895{
 896        return ((cq->rear + 1) & CQ_MASK) == cq->front;
 897}
 898
 899static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
 900{
 901        if (__cq_full(cq))
 902                return -1;
 903
 904        cq->element[cq->rear] = elem;
 905        cq->rear = (cq->rear + 1) & CQ_MASK;
 906        return 0;
 907}
 908
 909static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
 910{
 911        if (__cq_empty(cq))
 912                return -1;
 913
 914        *elem = cq->element[cq->front];
 915        cq->front = (cq->front + 1) & CQ_MASK;
 916        return 0;
 917}
 918
 919static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
 920{
 921        return (cq->rear - cq->front) & CQ_MASK;
 922}
 923
 924static inline void mark_lock_accessed(struct lock_list *lock,
 925                                        struct lock_list *parent)
 926{
 927        unsigned long nr;
 928
 929        nr = lock - list_entries;
 930        WARN_ON(nr >= nr_list_entries);
 931        lock->parent = parent;
 932        lock->class->dep_gen_id = lockdep_dependency_gen_id;
 933}
 934
 935static inline unsigned long lock_accessed(struct lock_list *lock)
 936{
 937        unsigned long nr;
 938
 939        nr = lock - list_entries;
 940        WARN_ON(nr >= nr_list_entries);
 941        return lock->class->dep_gen_id == lockdep_dependency_gen_id;
 942}
 943
 944static inline struct lock_list *get_lock_parent(struct lock_list *child)
 945{
 946        return child->parent;
 947}
 948
 949static inline int get_lock_depth(struct lock_list *child)
 950{
 951        int depth = 0;
 952        struct lock_list *parent;
 953
 954        while ((parent = get_lock_parent(child))) {
 955                child = parent;
 956                depth++;
 957        }
 958        return depth;
 959}
 960
 961static int __bfs(struct lock_list *source_entry,
 962                 void *data,
 963                 int (*match)(struct lock_list *entry, void *data),
 964                 struct lock_list **target_entry,
 965                 int forward)
 966{
 967        struct lock_list *entry;
 968        struct list_head *head;
 969        struct circular_queue *cq = &lock_cq;
 970        int ret = 1;
 971
 972        if (match(source_entry, data)) {
 973                *target_entry = source_entry;
 974                ret = 0;
 975                goto exit;
 976        }
 977
 978        if (forward)
 979                head = &source_entry->class->locks_after;
 980        else
 981                head = &source_entry->class->locks_before;
 982
 983        if (list_empty(head))
 984                goto exit;
 985
 986        __cq_init(cq);
 987        __cq_enqueue(cq, (unsigned long)source_entry);
 988
 989        while (!__cq_empty(cq)) {
 990                struct lock_list *lock;
 991
 992                __cq_dequeue(cq, (unsigned long *)&lock);
 993
 994                if (!lock->class) {
 995                        ret = -2;
 996                        goto exit;
 997                }
 998
 999                if (forward)
1000                        head = &lock->class->locks_after;
1001                else
1002                        head = &lock->class->locks_before;
1003
1004                list_for_each_entry(entry, head, entry) {
1005                        if (!lock_accessed(entry)) {
1006                                unsigned int cq_depth;
1007                                mark_lock_accessed(entry, lock);
1008                                if (match(entry, data)) {
1009                                        *target_entry = entry;
1010                                        ret = 0;
1011                                        goto exit;
1012                                }
1013
1014                                if (__cq_enqueue(cq, (unsigned long)entry)) {
1015                                        ret = -1;
1016                                        goto exit;
1017                                }
1018                                cq_depth = __cq_get_elem_count(cq);
1019                                if (max_bfs_queue_depth < cq_depth)
1020                                        max_bfs_queue_depth = cq_depth;
1021                        }
1022                }
1023        }
1024exit:
1025        return ret;
1026}
1027
1028static inline int __bfs_forwards(struct lock_list *src_entry,
1029                        void *data,
1030                        int (*match)(struct lock_list *entry, void *data),
1031                        struct lock_list **target_entry)
1032{
1033        return __bfs(src_entry, data, match, target_entry, 1);
1034
1035}
1036
1037static inline int __bfs_backwards(struct lock_list *src_entry,
1038                        void *data,
1039                        int (*match)(struct lock_list *entry, void *data),
1040                        struct lock_list **target_entry)
1041{
1042        return __bfs(src_entry, data, match, target_entry, 0);
1043
1044}
1045
1046/*
1047 * Recursive, forwards-direction lock-dependency checking, used for
1048 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1049 * checking.
1050 */
1051
1052/*
1053 * Print a dependency chain entry (this is only done when a deadlock
1054 * has been detected):
1055 */
1056static noinline int
1057print_circular_bug_entry(struct lock_list *target, int depth)
1058{
1059        if (debug_locks_silent)
1060                return 0;
1061        printk("\n-> #%u", depth);
1062        print_lock_name(target->class);
1063        printk(":\n");
1064        print_stack_trace(&target->trace, 6);
1065
1066        return 0;
1067}
1068
1069static void
1070print_circular_lock_scenario(struct held_lock *src,
1071                             struct held_lock *tgt,
1072                             struct lock_list *prt)
1073{
1074        struct lock_class *source = hlock_class(src);
1075        struct lock_class *target = hlock_class(tgt);
1076        struct lock_class *parent = prt->class;
1077
1078        /*
1079         * A direct locking problem where unsafe_class lock is taken
1080         * directly by safe_class lock, then all we need to show
1081         * is the deadlock scenario, as it is obvious that the
1082         * unsafe lock is taken under the safe lock.
1083         *
1084         * But if there is a chain instead, where the safe lock takes
1085         * an intermediate lock (middle_class) where this lock is
1086         * not the same as the safe lock, then the lock chain is
1087         * used to describe the problem. Otherwise we would need
1088         * to show a different CPU case for each link in the chain
1089         * from the safe_class lock to the unsafe_class lock.
1090         */
1091        if (parent != source) {
1092                printk("Chain exists of:\n  ");
1093                __print_lock_name(source);
1094                printk(" --> ");
1095                __print_lock_name(parent);
1096                printk(" --> ");
1097                __print_lock_name(target);
1098                printk("\n\n");
1099        }
1100
1101        printk(" Possible unsafe locking scenario:\n\n");
1102        printk("       CPU0                    CPU1\n");
1103        printk("       ----                    ----\n");
1104        printk("  lock(");
1105        __print_lock_name(target);
1106        printk(");\n");
1107        printk("                               lock(");
1108        __print_lock_name(parent);
1109        printk(");\n");
1110        printk("                               lock(");
1111        __print_lock_name(target);
1112        printk(");\n");
1113        printk("  lock(");
1114        __print_lock_name(source);
1115        printk(");\n");
1116        printk("\n *** DEADLOCK ***\n\n");
1117}
1118
1119/*
1120 * When a circular dependency is detected, print the
1121 * header first:
1122 */
1123static noinline int
1124print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1125                        struct held_lock *check_src,
1126                        struct held_lock *check_tgt)
1127{
1128        struct task_struct *curr = current;
1129
1130        if (debug_locks_silent)
1131                return 0;
1132
1133        printk("\n=======================================================\n");
1134        printk(  "[ INFO: possible circular locking dependency detected ]\n");
1135        print_kernel_version();
1136        printk(  "-------------------------------------------------------\n");
1137        printk("%s/%d is trying to acquire lock:\n",
1138                curr->comm, task_pid_nr(curr));
1139        print_lock(check_src);
1140        printk("\nbut task is already holding lock:\n");
1141        print_lock(check_tgt);
1142        printk("\nwhich lock already depends on the new lock.\n\n");
1143        printk("\nthe existing dependency chain (in reverse order) is:\n");
1144
1145        print_circular_bug_entry(entry, depth);
1146
1147        return 0;
1148}
1149
1150static inline int class_equal(struct lock_list *entry, void *data)
1151{
1152        return entry->class == data;
1153}
1154
1155static noinline int print_circular_bug(struct lock_list *this,
1156                                struct lock_list *target,
1157                                struct held_lock *check_src,
1158                                struct held_lock *check_tgt)
1159{
1160        struct task_struct *curr = current;
1161        struct lock_list *parent;
1162        struct lock_list *first_parent;
1163        int depth;
1164
1165        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1166                return 0;
1167
1168        if (!save_trace(&this->trace))
1169                return 0;
1170
1171        depth = get_lock_depth(target);
1172
1173        print_circular_bug_header(target, depth, check_src, check_tgt);
1174
1175        parent = get_lock_parent(target);
1176        first_parent = parent;
1177
1178        while (parent) {
1179                print_circular_bug_entry(parent, --depth);
1180                parent = get_lock_parent(parent);
1181        }
1182
1183        printk("\nother info that might help us debug this:\n\n");
1184        print_circular_lock_scenario(check_src, check_tgt,
1185                                     first_parent);
1186
1187        lockdep_print_held_locks(curr);
1188
1189        printk("\nstack backtrace:\n");
1190        dump_stack();
1191
1192        return 0;
1193}
1194
1195static noinline int print_bfs_bug(int ret)
1196{
1197        if (!debug_locks_off_graph_unlock())
1198                return 0;
1199
1200        WARN(1, "lockdep bfs error:%d\n", ret);
1201
1202        return 0;
1203}
1204
1205static int noop_count(struct lock_list *entry, void *data)
1206{
1207        (*(unsigned long *)data)++;
1208        return 0;
1209}
1210
1211unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1212{
1213        unsigned long  count = 0;
1214        struct lock_list *uninitialized_var(target_entry);
1215
1216        __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1217
1218        return count;
1219}
1220unsigned long lockdep_count_forward_deps(struct lock_class *class)
1221{
1222        unsigned long ret, flags;
1223        struct lock_list this;
1224
1225        this.parent = NULL;
1226        this.class = class;
1227
1228        local_irq_save(flags);
1229        arch_spin_lock(&lockdep_lock);
1230        ret = __lockdep_count_forward_deps(&this);
1231        arch_spin_unlock(&lockdep_lock);
1232        local_irq_restore(flags);
1233
1234        return ret;
1235}
1236
1237unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1238{
1239        unsigned long  count = 0;
1240        struct lock_list *uninitialized_var(target_entry);
1241
1242        __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1243
1244        return count;
1245}
1246
1247unsigned long lockdep_count_backward_deps(struct lock_class *class)
1248{
1249        unsigned long ret, flags;
1250        struct lock_list this;
1251
1252        this.parent = NULL;
1253        this.class = class;
1254
1255        local_irq_save(flags);
1256        arch_spin_lock(&lockdep_lock);
1257        ret = __lockdep_count_backward_deps(&this);
1258        arch_spin_unlock(&lockdep_lock);
1259        local_irq_restore(flags);
1260
1261        return ret;
1262}
1263
1264/*
1265 * Prove that the dependency graph starting at <entry> can not
1266 * lead to <target>. Print an error and return 0 if it does.
1267 */
1268static noinline int
1269check_noncircular(struct lock_list *root, struct lock_class *target,
1270                struct lock_list **target_entry)
1271{
1272        int result;
1273
1274        debug_atomic_inc(nr_cyclic_checks);
1275
1276        result = __bfs_forwards(root, target, class_equal, target_entry);
1277
1278        return result;
1279}
1280
1281#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1282/*
1283 * Forwards and backwards subgraph searching, for the purposes of
1284 * proving that two subgraphs can be connected by a new dependency
1285 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1286 */
1287
1288static inline int usage_match(struct lock_list *entry, void *bit)
1289{
1290        return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1291}
1292
1293
1294
1295/*
1296 * Find a node in the forwards-direction dependency sub-graph starting
1297 * at @root->class that matches @bit.
1298 *
1299 * Return 0 if such a node exists in the subgraph, and put that node
1300 * into *@target_entry.
1301 *
1302 * Return 1 otherwise and keep *@target_entry unchanged.
1303 * Return <0 on error.
1304 */
1305static int
1306find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1307                        struct lock_list **target_entry)
1308{
1309        int result;
1310
1311        debug_atomic_inc(nr_find_usage_forwards_checks);
1312
1313        result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1314
1315        return result;
1316}
1317
1318/*
1319 * Find a node in the backwards-direction dependency sub-graph starting
1320 * at @root->class that matches @bit.
1321 *
1322 * Return 0 if such a node exists in the subgraph, and put that node
1323 * into *@target_entry.
1324 *
1325 * Return 1 otherwise and keep *@target_entry unchanged.
1326 * Return <0 on error.
1327 */
1328static int
1329find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1330                        struct lock_list **target_entry)
1331{
1332        int result;
1333
1334        debug_atomic_inc(nr_find_usage_backwards_checks);
1335
1336        result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1337
1338        return result;
1339}
1340
1341static void print_lock_class_header(struct lock_class *class, int depth)
1342{
1343        int bit;
1344
1345        printk("%*s->", depth, "");
1346        print_lock_name(class);
1347        printk(" ops: %lu", class->ops);
1348        printk(" {\n");
1349
1350        for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1351                if (class->usage_mask & (1 << bit)) {
1352                        int len = depth;
1353
1354                        len += printk("%*s   %s", depth, "", usage_str[bit]);
1355                        len += printk(" at:\n");
1356                        print_stack_trace(class->usage_traces + bit, len);
1357                }
1358        }
1359        printk("%*s }\n", depth, "");
1360
1361        printk("%*s ... key      at: ",depth,"");
1362        print_ip_sym((unsigned long)class->key);
1363}
1364
1365/*
1366 * printk the shortest lock dependencies from @start to @end in reverse order:
1367 */
1368static void __used
1369print_shortest_lock_dependencies(struct lock_list *leaf,
1370                                struct lock_list *root)
1371{
1372        struct lock_list *entry = leaf;
1373        int depth;
1374
1375        /*compute depth from generated tree by BFS*/
1376        depth = get_lock_depth(leaf);
1377
1378        do {
1379                print_lock_class_header(entry->class, depth);
1380                printk("%*s ... acquired at:\n", depth, "");
1381                print_stack_trace(&entry->trace, 2);
1382                printk("\n");
1383
1384                if (depth == 0 && (entry != root)) {
1385                        printk("lockdep:%s bad path found in chain graph\n", __func__);
1386                        break;
1387                }
1388
1389                entry = get_lock_parent(entry);
1390                depth--;
1391        } while (entry && (depth >= 0));
1392
1393        return;
1394}
1395
1396static void
1397print_irq_lock_scenario(struct lock_list *safe_entry,
1398                        struct lock_list *unsafe_entry,
1399                        struct lock_class *prev_class,
1400                        struct lock_class *next_class)
1401{
1402        struct lock_class *safe_class = safe_entry->class;
1403        struct lock_class *unsafe_class = unsafe_entry->class;
1404        struct lock_class *middle_class = prev_class;
1405
1406        if (middle_class == safe_class)
1407                middle_class = next_class;
1408
1409        /*
1410         * A direct locking problem where unsafe_class lock is taken
1411         * directly by safe_class lock, then all we need to show
1412         * is the deadlock scenario, as it is obvious that the
1413         * unsafe lock is taken under the safe lock.
1414         *
1415         * But if there is a chain instead, where the safe lock takes
1416         * an intermediate lock (middle_class) where this lock is
1417         * not the same as the safe lock, then the lock chain is
1418         * used to describe the problem. Otherwise we would need
1419         * to show a different CPU case for each link in the chain
1420         * from the safe_class lock to the unsafe_class lock.
1421         */
1422        if (middle_class != unsafe_class) {
1423                printk("Chain exists of:\n  ");
1424                __print_lock_name(safe_class);
1425                printk(" --> ");
1426                __print_lock_name(middle_class);
1427                printk(" --> ");
1428                __print_lock_name(unsafe_class);
1429                printk("\n\n");
1430        }
1431
1432        printk(" Possible interrupt unsafe locking scenario:\n\n");
1433        printk("       CPU0                    CPU1\n");
1434        printk("       ----                    ----\n");
1435        printk("  lock(");
1436        __print_lock_name(unsafe_class);
1437        printk(");\n");
1438        printk("                               local_irq_disable();\n");
1439        printk("                               lock(");
1440        __print_lock_name(safe_class);
1441        printk(");\n");
1442        printk("                               lock(");
1443        __print_lock_name(middle_class);
1444        printk(");\n");
1445        printk("  <Interrupt>\n");
1446        printk("    lock(");
1447        __print_lock_name(safe_class);
1448        printk(");\n");
1449        printk("\n *** DEADLOCK ***\n\n");
1450}
1451
1452static int
1453print_bad_irq_dependency(struct task_struct *curr,
1454                         struct lock_list *prev_root,
1455                         struct lock_list *next_root,
1456                         struct lock_list *backwards_entry,
1457                         struct lock_list *forwards_entry,
1458                         struct held_lock *prev,
1459                         struct held_lock *next,
1460                         enum lock_usage_bit bit1,
1461                         enum lock_usage_bit bit2,
1462                         const char *irqclass)
1463{
1464        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1465                return 0;
1466
1467        printk("\n======================================================\n");
1468        printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1469                irqclass, irqclass);
1470        print_kernel_version();
1471        printk(  "------------------------------------------------------\n");
1472        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1473                curr->comm, task_pid_nr(curr),
1474                curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1475                curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1476                curr->hardirqs_enabled,
1477                curr->softirqs_enabled);
1478        print_lock(next);
1479
1480        printk("\nand this task is already holding:\n");
1481        print_lock(prev);
1482        printk("which would create a new lock dependency:\n");
1483        print_lock_name(hlock_class(prev));
1484        printk(" ->");
1485        print_lock_name(hlock_class(next));
1486        printk("\n");
1487
1488        printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1489                irqclass);
1490        print_lock_name(backwards_entry->class);
1491        printk("\n... which became %s-irq-safe at:\n", irqclass);
1492
1493        print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1494
1495        printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1496        print_lock_name(forwards_entry->class);
1497        printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1498        printk("...");
1499
1500        print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1501
1502        printk("\nother info that might help us debug this:\n\n");
1503        print_irq_lock_scenario(backwards_entry, forwards_entry,
1504                                hlock_class(prev), hlock_class(next));
1505
1506        lockdep_print_held_locks(curr);
1507
1508        printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1509        printk(" and the holding lock:\n");
1510        if (!save_trace(&prev_root->trace))
1511                return 0;
1512        print_shortest_lock_dependencies(backwards_entry, prev_root);
1513
1514        printk("\nthe dependencies between the lock to be acquired");
1515        printk(" and %s-irq-unsafe lock:\n", irqclass);
1516        if (!save_trace(&next_root->trace))
1517                return 0;
1518        print_shortest_lock_dependencies(forwards_entry, next_root);
1519
1520        printk("\nstack backtrace:\n");
1521        dump_stack();
1522
1523        return 0;
1524}
1525
1526static int
1527check_usage(struct task_struct *curr, struct held_lock *prev,
1528            struct held_lock *next, enum lock_usage_bit bit_backwards,
1529            enum lock_usage_bit bit_forwards, const char *irqclass)
1530{
1531        int ret;
1532        struct lock_list this, that;
1533        struct lock_list *uninitialized_var(target_entry);
1534        struct lock_list *uninitialized_var(target_entry1);
1535
1536        this.parent = NULL;
1537
1538        this.class = hlock_class(prev);
1539        ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1540        if (ret < 0)
1541                return print_bfs_bug(ret);
1542        if (ret == 1)
1543                return ret;
1544
1545        that.parent = NULL;
1546        that.class = hlock_class(next);
1547        ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1548        if (ret < 0)
1549                return print_bfs_bug(ret);
1550        if (ret == 1)
1551                return ret;
1552
1553        return print_bad_irq_dependency(curr, &this, &that,
1554                        target_entry, target_entry1,
1555                        prev, next,
1556                        bit_backwards, bit_forwards, irqclass);
1557}
1558
1559static const char *state_names[] = {
1560#define LOCKDEP_STATE(__STATE) \
1561        __stringify(__STATE),
1562#include "lockdep_states.h"
1563#undef LOCKDEP_STATE
1564};
1565
1566static const char *state_rnames[] = {
1567#define LOCKDEP_STATE(__STATE) \
1568        __stringify(__STATE)"-READ",
1569#include "lockdep_states.h"
1570#undef LOCKDEP_STATE
1571};
1572
1573static inline const char *state_name(enum lock_usage_bit bit)
1574{
1575        return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1576}
1577
1578static int exclusive_bit(int new_bit)
1579{
1580        /*
1581         * USED_IN
1582         * USED_IN_READ
1583         * ENABLED
1584         * ENABLED_READ
1585         *
1586         * bit 0 - write/read
1587         * bit 1 - used_in/enabled
1588         * bit 2+  state
1589         */
1590
1591        int state = new_bit & ~3;
1592        int dir = new_bit & 2;
1593
1594        /*
1595         * keep state, bit flip the direction and strip read.
1596         */
1597        return state | (dir ^ 2);
1598}
1599
1600static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1601                           struct held_lock *next, enum lock_usage_bit bit)
1602{
1603        /*
1604         * Prove that the new dependency does not connect a hardirq-safe
1605         * lock with a hardirq-unsafe lock - to achieve this we search
1606         * the backwards-subgraph starting at <prev>, and the
1607         * forwards-subgraph starting at <next>:
1608         */
1609        if (!check_usage(curr, prev, next, bit,
1610                           exclusive_bit(bit), state_name(bit)))
1611                return 0;
1612
1613        bit++; /* _READ */
1614
1615        /*
1616         * Prove that the new dependency does not connect a hardirq-safe-read
1617         * lock with a hardirq-unsafe lock - to achieve this we search
1618         * the backwards-subgraph starting at <prev>, and the
1619         * forwards-subgraph starting at <next>:
1620         */
1621        if (!check_usage(curr, prev, next, bit,
1622                           exclusive_bit(bit), state_name(bit)))
1623                return 0;
1624
1625        return 1;
1626}
1627
1628static int
1629check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1630                struct held_lock *next)
1631{
1632#define LOCKDEP_STATE(__STATE)                                          \
1633        if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1634                return 0;
1635#include "lockdep_states.h"
1636#undef LOCKDEP_STATE
1637
1638        return 1;
1639}
1640
1641static void inc_chains(void)
1642{
1643        if (current->hardirq_context)
1644                nr_hardirq_chains++;
1645        else {
1646                if (current->softirq_context)
1647                        nr_softirq_chains++;
1648                else
1649                        nr_process_chains++;
1650        }
1651}
1652
1653#else
1654
1655static inline int
1656check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1657                struct held_lock *next)
1658{
1659        return 1;
1660}
1661
1662static inline void inc_chains(void)
1663{
1664        nr_process_chains++;
1665}
1666
1667#endif
1668
1669static void
1670print_deadlock_scenario(struct held_lock *nxt,
1671                             struct held_lock *prv)
1672{
1673        struct lock_class *next = hlock_class(nxt);
1674        struct lock_class *prev = hlock_class(prv);
1675
1676        printk(" Possible unsafe locking scenario:\n\n");
1677        printk("       CPU0\n");
1678        printk("       ----\n");
1679        printk("  lock(");
1680        __print_lock_name(prev);
1681        printk(");\n");
1682        printk("  lock(");
1683        __print_lock_name(next);
1684        printk(");\n");
1685        printk("\n *** DEADLOCK ***\n\n");
1686        printk(" May be due to missing lock nesting notation\n\n");
1687}
1688
1689static int
1690print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1691                   struct held_lock *next)
1692{
1693        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1694                return 0;
1695
1696        printk("\n=============================================\n");
1697        printk(  "[ INFO: possible recursive locking detected ]\n");
1698        print_kernel_version();
1699        printk(  "---------------------------------------------\n");
1700        printk("%s/%d is trying to acquire lock:\n",
1701                curr->comm, task_pid_nr(curr));
1702        print_lock(next);
1703        printk("\nbut task is already holding lock:\n");
1704        print_lock(prev);
1705
1706        printk("\nother info that might help us debug this:\n");
1707        print_deadlock_scenario(next, prev);
1708        lockdep_print_held_locks(curr);
1709
1710        printk("\nstack backtrace:\n");
1711        dump_stack();
1712
1713        return 0;
1714}
1715
1716/*
1717 * Check whether we are holding such a class already.
1718 *
1719 * (Note that this has to be done separately, because the graph cannot
1720 * detect such classes of deadlocks.)
1721 *
1722 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1723 */
1724static int
1725check_deadlock(struct task_struct *curr, struct held_lock *next,
1726               struct lockdep_map *next_instance, int read)
1727{
1728        struct held_lock *prev;
1729        struct held_lock *nest = NULL;
1730        int i;
1731
1732        for (i = 0; i < curr->lockdep_depth; i++) {
1733                prev = curr->held_locks + i;
1734
1735                if (prev->instance == next->nest_lock)
1736                        nest = prev;
1737
1738                if (hlock_class(prev) != hlock_class(next))
1739                        continue;
1740
1741                /*
1742                 * Allow read-after-read recursion of the same
1743                 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1744                 */
1745                if ((read == 2) && prev->read)
1746                        return 2;
1747
1748                /*
1749                 * We're holding the nest_lock, which serializes this lock's
1750                 * nesting behaviour.
1751                 */
1752                if (nest)
1753                        return 2;
1754
1755                return print_deadlock_bug(curr, prev, next);
1756        }
1757        return 1;
1758}
1759
1760/*
1761 * There was a chain-cache miss, and we are about to add a new dependency
1762 * to a previous lock. We recursively validate the following rules:
1763 *
1764 *  - would the adding of the <prev> -> <next> dependency create a
1765 *    circular dependency in the graph? [== circular deadlock]
1766 *
1767 *  - does the new prev->next dependency connect any hardirq-safe lock
1768 *    (in the full backwards-subgraph starting at <prev>) with any
1769 *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1770 *    <next>)? [== illegal lock inversion with hardirq contexts]
1771 *
1772 *  - does the new prev->next dependency connect any softirq-safe lock
1773 *    (in the full backwards-subgraph starting at <prev>) with any
1774 *    softirq-unsafe lock (in the full forwards-subgraph starting at
1775 *    <next>)? [== illegal lock inversion with softirq contexts]
1776 *
1777 * any of these scenarios could lead to a deadlock.
1778 *
1779 * Then if all the validations pass, we add the forwards and backwards
1780 * dependency.
1781 */
1782static int
1783check_prev_add(struct task_struct *curr, struct held_lock *prev,
1784               struct held_lock *next, int distance, int trylock_loop)
1785{
1786        struct lock_list *entry;
1787        int ret;
1788        struct lock_list this;
1789        struct lock_list *uninitialized_var(target_entry);
1790        /*
1791         * Static variable, serialized by the graph_lock().
1792         *
1793         * We use this static variable to save the stack trace in case
1794         * we call into this function multiple times due to encountering
1795         * trylocks in the held lock stack.
1796         */
1797        static struct stack_trace trace;
1798
1799        /*
1800         * Prove that the new <prev> -> <next> dependency would not
1801         * create a circular dependency in the graph. (We do this by
1802         * forward-recursing into the graph starting at <next>, and
1803         * checking whether we can reach <prev>.)
1804         *
1805         * We are using global variables to control the recursion, to
1806         * keep the stackframe size of the recursive functions low:
1807         */
1808        this.class = hlock_class(next);
1809        this.parent = NULL;
1810        ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1811        if (unlikely(!ret))
1812                return print_circular_bug(&this, target_entry, next, prev);
1813        else if (unlikely(ret < 0))
1814                return print_bfs_bug(ret);
1815
1816        if (!check_prev_add_irq(curr, prev, next))
1817                return 0;
1818
1819        /*
1820         * For recursive read-locks we do all the dependency checks,
1821         * but we dont store read-triggered dependencies (only
1822         * write-triggered dependencies). This ensures that only the
1823         * write-side dependencies matter, and that if for example a
1824         * write-lock never takes any other locks, then the reads are
1825         * equivalent to a NOP.
1826         */
1827        if (next->read == 2 || prev->read == 2)
1828                return 1;
1829        /*
1830         * Is the <prev> -> <next> dependency already present?
1831         *
1832         * (this may occur even though this is a new chain: consider
1833         *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1834         *  chains - the second one will be new, but L1 already has
1835         *  L2 added to its dependency list, due to the first chain.)
1836         */
1837        list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1838                if (entry->class == hlock_class(next)) {
1839                        if (distance == 1)
1840                                entry->distance = 1;
1841                        return 2;
1842                }
1843        }
1844
1845        if (!trylock_loop && !save_trace(&trace))
1846                return 0;
1847
1848        /*
1849         * Ok, all validations passed, add the new lock
1850         * to the previous lock's dependency list:
1851         */
1852        ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1853                               &hlock_class(prev)->locks_after,
1854                               next->acquire_ip, distance, &trace);
1855
1856        if (!ret)
1857                return 0;
1858
1859        ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1860                               &hlock_class(next)->locks_before,
1861                               next->acquire_ip, distance, &trace);
1862        if (!ret)
1863                return 0;
1864
1865        /*
1866         * Debugging printouts:
1867         */
1868        if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1869                graph_unlock();
1870                printk("\n new dependency: ");
1871                print_lock_name(hlock_class(prev));
1872                printk(" => ");
1873                print_lock_name(hlock_class(next));
1874                printk("\n");
1875                dump_stack();
1876                return graph_lock();
1877        }
1878        return 1;
1879}
1880
1881/*
1882 * Add the dependency to all directly-previous locks that are 'relevant'.
1883 * The ones that are relevant are (in increasing distance from curr):
1884 * all consecutive trylock entries and the final non-trylock entry - or
1885 * the end of this context's lock-chain - whichever comes first.
1886 */
1887static int
1888check_prevs_add(struct task_struct *curr, struct held_lock *next)
1889{
1890        int depth = curr->lockdep_depth;
1891        int trylock_loop = 0;
1892        struct held_lock *hlock;
1893
1894        /*
1895         * Debugging checks.
1896         *
1897         * Depth must not be zero for a non-head lock:
1898         */
1899        if (!depth)
1900                goto out_bug;
1901        /*
1902         * At least two relevant locks must exist for this
1903         * to be a head:
1904         */
1905        if (curr->held_locks[depth].irq_context !=
1906                        curr->held_locks[depth-1].irq_context)
1907                goto out_bug;
1908
1909        for (;;) {
1910                int distance = curr->lockdep_depth - depth + 1;
1911                hlock = curr->held_locks + depth-1;
1912                /*
1913                 * Only non-recursive-read entries get new dependencies
1914                 * added:
1915                 */
1916                if (hlock->read != 2) {
1917                        if (!check_prev_add(curr, hlock, next,
1918                                                distance, trylock_loop))
1919                                return 0;
1920                        /*
1921                         * Stop after the first non-trylock entry,
1922                         * as non-trylock entries have added their
1923                         * own direct dependencies already, so this
1924                         * lock is connected to them indirectly:
1925                         */
1926                        if (!hlock->trylock)
1927                                break;
1928                }
1929                depth--;
1930                /*
1931                 * End of lock-stack?
1932                 */
1933                if (!depth)
1934                        break;
1935                /*
1936                 * Stop the search if we cross into another context:
1937                 */
1938                if (curr->held_locks[depth].irq_context !=
1939                                curr->held_locks[depth-1].irq_context)
1940                        break;
1941                trylock_loop = 1;
1942        }
1943        return 1;
1944out_bug:
1945        if (!debug_locks_off_graph_unlock())
1946                return 0;
1947
1948        WARN_ON(1);
1949
1950        return 0;
1951}
1952
1953unsigned long nr_lock_chains;
1954struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1955int nr_chain_hlocks;
1956static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1957
1958struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1959{
1960        return lock_classes + chain_hlocks[chain->base + i];
1961}
1962
1963/*
1964 * Look up a dependency chain. If the key is not present yet then
1965 * add it and return 1 - in this case the new dependency chain is
1966 * validated. If the key is already hashed, return 0.
1967 * (On return with 1 graph_lock is held.)
1968 */
1969static inline int lookup_chain_cache(struct task_struct *curr,
1970                                     struct held_lock *hlock,
1971                                     u64 chain_key)
1972{
1973        struct lock_class *class = hlock_class(hlock);
1974        struct list_head *hash_head = chainhashentry(chain_key);
1975        struct lock_chain *chain;
1976        struct held_lock *hlock_curr, *hlock_next;
1977        int i, j;
1978
1979        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1980                return 0;
1981        /*
1982         * We can walk it lock-free, because entries only get added
1983         * to the hash:
1984         */
1985        list_for_each_entry(chain, hash_head, entry) {
1986                if (chain->chain_key == chain_key) {
1987cache_hit:
1988                        debug_atomic_inc(chain_lookup_hits);
1989                        if (very_verbose(class))
1990                                printk("\nhash chain already cached, key: "
1991                                        "%016Lx tail class: [%p] %s\n",
1992                                        (unsigned long long)chain_key,
1993                                        class->key, class->name);
1994                        return 0;
1995                }
1996        }
1997        if (very_verbose(class))
1998                printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1999                        (unsigned long long)chain_key, class->key, class->name);
2000        /*
2001         * Allocate a new chain entry from the static array, and add
2002         * it to the hash:
2003         */
2004        if (!graph_lock())
2005                return 0;
2006        /*
2007         * We have to walk the chain again locked - to avoid duplicates:
2008         */
2009        list_for_each_entry(chain, hash_head, entry) {
2010                if (chain->chain_key == chain_key) {
2011                        graph_unlock();
2012                        goto cache_hit;
2013                }
2014        }
2015        if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2016                if (!debug_locks_off_graph_unlock())
2017                        return 0;
2018
2019                printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2020                printk("turning off the locking correctness validator.\n");
2021                dump_stack();
2022                return 0;
2023        }
2024        chain = lock_chains + nr_lock_chains++;
2025        chain->chain_key = chain_key;
2026        chain->irq_context = hlock->irq_context;
2027        /* Find the first held_lock of current chain */
2028        hlock_next = hlock;
2029        for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2030                hlock_curr = curr->held_locks + i;
2031                if (hlock_curr->irq_context != hlock_next->irq_context)
2032                        break;
2033                hlock_next = hlock;
2034        }
2035        i++;
2036        chain->depth = curr->lockdep_depth + 1 - i;
2037        if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2038                chain->base = nr_chain_hlocks;
2039                nr_chain_hlocks += chain->depth;
2040                for (j = 0; j < chain->depth - 1; j++, i++) {
2041                        int lock_id = curr->held_locks[i].class_idx - 1;
2042                        chain_hlocks[chain->base + j] = lock_id;
2043                }
2044                chain_hlocks[chain->base + j] = class - lock_classes;
2045        }
2046        list_add_tail_rcu(&chain->entry, hash_head);
2047        debug_atomic_inc(chain_lookup_misses);
2048        inc_chains();
2049
2050        return 1;
2051}
2052
2053static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2054                struct held_lock *hlock, int chain_head, u64 chain_key)
2055{
2056        /*
2057         * Trylock needs to maintain the stack of held locks, but it
2058         * does not add new dependencies, because trylock can be done
2059         * in any order.
2060         *
2061         * We look up the chain_key and do the O(N^2) check and update of
2062         * the dependencies only if this is a new dependency chain.
2063         * (If lookup_chain_cache() returns with 1 it acquires
2064         * graph_lock for us)
2065         */
2066        if (!hlock->trylock && (hlock->check == 2) &&
2067            lookup_chain_cache(curr, hlock, chain_key)) {
2068                /*
2069                 * Check whether last held lock:
2070                 *
2071                 * - is irq-safe, if this lock is irq-unsafe
2072                 * - is softirq-safe, if this lock is hardirq-unsafe
2073                 *
2074                 * And check whether the new lock's dependency graph
2075                 * could lead back to the previous lock.
2076                 *
2077                 * any of these scenarios could lead to a deadlock. If
2078                 * All validations
2079                 */
2080                int ret = check_deadlock(curr, hlock, lock, hlock->read);
2081
2082                if (!ret)
2083                        return 0;
2084                /*
2085                 * Mark recursive read, as we jump over it when
2086                 * building dependencies (just like we jump over
2087                 * trylock entries):
2088                 */
2089                if (ret == 2)
2090                        hlock->read = 2;
2091                /*
2092                 * Add dependency only if this lock is not the head
2093                 * of the chain, and if it's not a secondary read-lock:
2094                 */
2095                if (!chain_head && ret != 2)
2096                        if (!check_prevs_add(curr, hlock))
2097                                return 0;
2098                graph_unlock();
2099        } else
2100                /* after lookup_chain_cache(): */
2101                if (unlikely(!debug_locks))
2102                        return 0;
2103
2104        return 1;
2105}
2106#else
2107static inline int validate_chain(struct task_struct *curr,
2108                struct lockdep_map *lock, struct held_lock *hlock,
2109                int chain_head, u64 chain_key)
2110{
2111        return 1;
2112}
2113#endif
2114
2115/*
2116 * We are building curr_chain_key incrementally, so double-check
2117 * it from scratch, to make sure that it's done correctly:
2118 */
2119static void check_chain_key(struct task_struct *curr)
2120{
2121#ifdef CONFIG_DEBUG_LOCKDEP
2122        struct held_lock *hlock, *prev_hlock = NULL;
2123        unsigned int i, id;
2124        u64 chain_key = 0;
2125
2126        for (i = 0; i < curr->lockdep_depth; i++) {
2127                hlock = curr->held_locks + i;
2128                if (chain_key != hlock->prev_chain_key) {
2129                        debug_locks_off();
2130                        WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2131                                curr->lockdep_depth, i,
2132                                (unsigned long long)chain_key,
2133                                (unsigned long long)hlock->prev_chain_key);
2134                        return;
2135                }
2136                id = hlock->class_idx - 1;
2137                if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2138                        return;
2139
2140                if (prev_hlock && (prev_hlock->irq_context !=
2141                                                        hlock->irq_context))
2142                        chain_key = 0;
2143                chain_key = iterate_chain_key(chain_key, id);
2144                prev_hlock = hlock;
2145        }
2146        if (chain_key != curr->curr_chain_key) {
2147                debug_locks_off();
2148                WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2149                        curr->lockdep_depth, i,
2150                        (unsigned long long)chain_key,
2151                        (unsigned long long)curr->curr_chain_key);
2152        }
2153#endif
2154}
2155
2156static void
2157print_usage_bug_scenario(struct held_lock *lock)
2158{
2159        struct lock_class *class = hlock_class(lock);
2160
2161        printk(" Possible unsafe locking scenario:\n\n");
2162        printk("       CPU0\n");
2163        printk("       ----\n");
2164        printk("  lock(");
2165        __print_lock_name(class);
2166        printk(");\n");
2167        printk("  <Interrupt>\n");
2168        printk("    lock(");
2169        __print_lock_name(class);
2170        printk(");\n");
2171        printk("\n *** DEADLOCK ***\n\n");
2172}
2173
2174static int
2175print_usage_bug(struct task_struct *curr, struct held_lock *this,
2176                enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2177{
2178        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2179                return 0;
2180
2181        printk("\n=================================\n");
2182        printk(  "[ INFO: inconsistent lock state ]\n");
2183        print_kernel_version();
2184        printk(  "---------------------------------\n");
2185
2186        printk("inconsistent {%s} -> {%s} usage.\n",
2187                usage_str[prev_bit], usage_str[new_bit]);
2188
2189        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2190                curr->comm, task_pid_nr(curr),
2191                trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2192                trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2193                trace_hardirqs_enabled(curr),
2194                trace_softirqs_enabled(curr));
2195        print_lock(this);
2196
2197        printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2198        print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2199
2200        print_irqtrace_events(curr);
2201        printk("\nother info that might help us debug this:\n");
2202        print_usage_bug_scenario(this);
2203
2204        lockdep_print_held_locks(curr);
2205
2206        printk("\nstack backtrace:\n");
2207        dump_stack();
2208
2209        return 0;
2210}
2211
2212/*
2213 * Print out an error if an invalid bit is set:
2214 */
2215static inline int
2216valid_state(struct task_struct *curr, struct held_lock *this,
2217            enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2218{
2219        if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2220                return print_usage_bug(curr, this, bad_bit, new_bit);
2221        return 1;
2222}
2223
2224static int mark_lock(struct task_struct *curr, struct held_lock *this,
2225                     enum lock_usage_bit new_bit);
2226
2227#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2228
2229/*
2230 * print irq inversion bug:
2231 */
2232static int
2233print_irq_inversion_bug(struct task_struct *curr,
2234                        struct lock_list *root, struct lock_list *other,
2235                        struct held_lock *this, int forwards,
2236                        const char *irqclass)
2237{
2238        struct lock_list *entry = other;
2239        struct lock_list *middle = NULL;
2240        int depth;
2241
2242        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2243                return 0;
2244
2245        printk("\n=========================================================\n");
2246        printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2247        print_kernel_version();
2248        printk(  "---------------------------------------------------------\n");
2249        printk("%s/%d just changed the state of lock:\n",
2250                curr->comm, task_pid_nr(curr));
2251        print_lock(this);
2252        if (forwards)
2253                printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2254        else
2255                printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2256        print_lock_name(other->class);
2257        printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2258
2259        printk("\nother info that might help us debug this:\n");
2260
2261        /* Find a middle lock (if one exists) */
2262        depth = get_lock_depth(other);
2263        do {
2264                if (depth == 0 && (entry != root)) {
2265                        printk("lockdep:%s bad path found in chain graph\n", __func__);
2266                        break;
2267                }
2268                middle = entry;
2269                entry = get_lock_parent(entry);
2270                depth--;
2271        } while (entry && entry != root && (depth >= 0));
2272        if (forwards)
2273                print_irq_lock_scenario(root, other,
2274                        middle ? middle->class : root->class, other->class);
2275        else
2276                print_irq_lock_scenario(other, root,
2277                        middle ? middle->class : other->class, root->class);
2278
2279        lockdep_print_held_locks(curr);
2280
2281        printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2282        if (!save_trace(&root->trace))
2283                return 0;
2284        print_shortest_lock_dependencies(other, root);
2285
2286        printk("\nstack backtrace:\n");
2287        dump_stack();
2288
2289        return 0;
2290}
2291
2292/*
2293 * Prove that in the forwards-direction subgraph starting at <this>
2294 * there is no lock matching <mask>:
2295 */
2296static int
2297check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2298                     enum lock_usage_bit bit, const char *irqclass)
2299{
2300        int ret;
2301        struct lock_list root;
2302        struct lock_list *uninitialized_var(target_entry);
2303
2304        root.parent = NULL;
2305        root.class = hlock_class(this);
2306        ret = find_usage_forwards(&root, bit, &target_entry);
2307        if (ret < 0)
2308                return print_bfs_bug(ret);
2309        if (ret == 1)
2310                return ret;
2311
2312        return print_irq_inversion_bug(curr, &root, target_entry,
2313                                        this, 1, irqclass);
2314}
2315
2316/*
2317 * Prove that in the backwards-direction subgraph starting at <this>
2318 * there is no lock matching <mask>:
2319 */
2320static int
2321check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2322                      enum lock_usage_bit bit, const char *irqclass)
2323{
2324        int ret;
2325        struct lock_list root;
2326        struct lock_list *uninitialized_var(target_entry);
2327
2328        root.parent = NULL;
2329        root.class = hlock_class(this);
2330        ret = find_usage_backwards(&root, bit, &target_entry);
2331        if (ret < 0)
2332                return print_bfs_bug(ret);
2333        if (ret == 1)
2334                return ret;
2335
2336        return print_irq_inversion_bug(curr, &root, target_entry,
2337                                        this, 0, irqclass);
2338}
2339
2340void print_irqtrace_events(struct task_struct *curr)
2341{
2342        printk("irq event stamp: %u\n", curr->irq_events);
2343        printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2344        print_ip_sym(curr->hardirq_enable_ip);
2345        printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2346        print_ip_sym(curr->hardirq_disable_ip);
2347        printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2348        print_ip_sym(curr->softirq_enable_ip);
2349        printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2350        print_ip_sym(curr->softirq_disable_ip);
2351}
2352
2353static int HARDIRQ_verbose(struct lock_class *class)
2354{
2355#if HARDIRQ_VERBOSE
2356        return class_filter(class);
2357#endif
2358        return 0;
2359}
2360
2361static int SOFTIRQ_verbose(struct lock_class *class)
2362{
2363#if SOFTIRQ_VERBOSE
2364        return class_filter(class);
2365#endif
2366        return 0;
2367}
2368
2369static int RECLAIM_FS_verbose(struct lock_class *class)
2370{
2371#if RECLAIM_VERBOSE
2372        return class_filter(class);
2373#endif
2374        return 0;
2375}
2376
2377#define STRICT_READ_CHECKS      1
2378
2379static int (*state_verbose_f[])(struct lock_class *class) = {
2380#define LOCKDEP_STATE(__STATE) \
2381        __STATE##_verbose,
2382#include "lockdep_states.h"
2383#undef LOCKDEP_STATE
2384};
2385
2386static inline int state_verbose(enum lock_usage_bit bit,
2387                                struct lock_class *class)
2388{
2389        return state_verbose_f[bit >> 2](class);
2390}
2391
2392typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2393                             enum lock_usage_bit bit, const char *name);
2394
2395static int
2396mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2397                enum lock_usage_bit new_bit)
2398{
2399        int excl_bit = exclusive_bit(new_bit);
2400        int read = new_bit & 1;
2401        int dir = new_bit & 2;
2402
2403        /*
2404         * mark USED_IN has to look forwards -- to ensure no dependency
2405         * has ENABLED state, which would allow recursion deadlocks.
2406         *
2407         * mark ENABLED has to look backwards -- to ensure no dependee
2408         * has USED_IN state, which, again, would allow  recursion deadlocks.
2409         */
2410        check_usage_f usage = dir ?
2411                check_usage_backwards : check_usage_forwards;
2412
2413        /*
2414         * Validate that this particular lock does not have conflicting
2415         * usage states.
2416         */
2417        if (!valid_state(curr, this, new_bit, excl_bit))
2418                return 0;
2419
2420        /*
2421         * Validate that the lock dependencies don't have conflicting usage
2422         * states.
2423         */
2424        if ((!read || !dir || STRICT_READ_CHECKS) &&
2425                        !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2426                return 0;
2427
2428        /*
2429         * Check for read in write conflicts
2430         */
2431        if (!read) {
2432                if (!valid_state(curr, this, new_bit, excl_bit + 1))
2433                        return 0;
2434
2435                if (STRICT_READ_CHECKS &&
2436                        !usage(curr, this, excl_bit + 1,
2437                                state_name(new_bit + 1)))
2438                        return 0;
2439        }
2440
2441        if (state_verbose(new_bit, hlock_class(this)))
2442                return 2;
2443
2444        return 1;
2445}
2446
2447enum mark_type {
2448#define LOCKDEP_STATE(__STATE)  __STATE,
2449#include "lockdep_states.h"
2450#undef LOCKDEP_STATE
2451};
2452
2453/*
2454 * Mark all held locks with a usage bit:
2455 */
2456static int
2457mark_held_locks(struct task_struct *curr, enum mark_type mark)
2458{
2459        enum lock_usage_bit usage_bit;
2460        struct held_lock *hlock;
2461        int i;
2462
2463        for (i = 0; i < curr->lockdep_depth; i++) {
2464                hlock = curr->held_locks + i;
2465
2466                usage_bit = 2 + (mark << 2); /* ENABLED */
2467                if (hlock->read)
2468                        usage_bit += 1; /* READ */
2469
2470                BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2471
2472                if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
2473                        continue;
2474
2475                if (!mark_lock(curr, hlock, usage_bit))
2476                        return 0;
2477        }
2478
2479        return 1;
2480}
2481
2482/*
2483 * Hardirqs will be enabled:
2484 */
2485static void __trace_hardirqs_on_caller(unsigned long ip)
2486{
2487        struct task_struct *curr = current;
2488
2489        /* we'll do an OFF -> ON transition: */
2490        curr->hardirqs_enabled = 1;
2491
2492        /*
2493         * We are going to turn hardirqs on, so set the
2494         * usage bit for all held locks:
2495         */
2496        if (!mark_held_locks(curr, HARDIRQ))
2497                return;
2498        /*
2499         * If we have softirqs enabled, then set the usage
2500         * bit for all held locks. (disabled hardirqs prevented
2501         * this bit from being set before)
2502         */
2503        if (curr->softirqs_enabled)
2504                if (!mark_held_locks(curr, SOFTIRQ))
2505                        return;
2506
2507        curr->hardirq_enable_ip = ip;
2508        curr->hardirq_enable_event = ++curr->irq_events;
2509        debug_atomic_inc(hardirqs_on_events);
2510}
2511
2512void trace_hardirqs_on_caller(unsigned long ip)
2513{
2514        time_hardirqs_on(CALLER_ADDR0, ip);
2515
2516        if (unlikely(!debug_locks || current->lockdep_recursion))
2517                return;
2518
2519        if (unlikely(current->hardirqs_enabled)) {
2520                /*
2521                 * Neither irq nor preemption are disabled here
2522                 * so this is racy by nature but losing one hit
2523                 * in a stat is not a big deal.
2524                 */
2525                __debug_atomic_inc(redundant_hardirqs_on);
2526                return;
2527        }
2528
2529        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2530                return;
2531
2532        if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2533                return;
2534
2535        if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2536                return;
2537
2538        current->lockdep_recursion = 1;
2539        __trace_hardirqs_on_caller(ip);
2540        current->lockdep_recursion = 0;
2541}
2542EXPORT_SYMBOL(trace_hardirqs_on_caller);
2543
2544void trace_hardirqs_on(void)
2545{
2546        trace_hardirqs_on_caller(CALLER_ADDR0);
2547}
2548EXPORT_SYMBOL(trace_hardirqs_on);
2549
2550/*
2551 * Hardirqs were disabled:
2552 */
2553void trace_hardirqs_off_caller(unsigned long ip)
2554{
2555        struct task_struct *curr = current;
2556
2557        time_hardirqs_off(CALLER_ADDR0, ip);
2558
2559        if (unlikely(!debug_locks || current->lockdep_recursion))
2560                return;
2561
2562        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2563                return;
2564
2565        if (curr->hardirqs_enabled) {
2566                /*
2567                 * We have done an ON -> OFF transition:
2568                 */
2569                curr->hardirqs_enabled = 0;
2570                curr->hardirq_disable_ip = ip;
2571                curr->hardirq_disable_event = ++curr->irq_events;
2572                debug_atomic_inc(hardirqs_off_events);
2573        } else
2574                debug_atomic_inc(redundant_hardirqs_off);
2575}
2576EXPORT_SYMBOL(trace_hardirqs_off_caller);
2577
2578void trace_hardirqs_off(void)
2579{
2580        trace_hardirqs_off_caller(CALLER_ADDR0);
2581}
2582EXPORT_SYMBOL(trace_hardirqs_off);
2583
2584/*
2585 * Softirqs will be enabled:
2586 */
2587void trace_softirqs_on(unsigned long ip)
2588{
2589        struct task_struct *curr = current;
2590
2591        if (unlikely(!debug_locks || current->lockdep_recursion))
2592                return;
2593
2594        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2595                return;
2596
2597        if (curr->softirqs_enabled) {
2598                debug_atomic_inc(redundant_softirqs_on);
2599                return;
2600        }
2601
2602        current->lockdep_recursion = 1;
2603        /*
2604         * We'll do an OFF -> ON transition:
2605         */
2606        curr->softirqs_enabled = 1;
2607        curr->softirq_enable_ip = ip;
2608        curr->softirq_enable_event = ++curr->irq_events;
2609        debug_atomic_inc(softirqs_on_events);
2610        /*
2611         * We are going to turn softirqs on, so set the
2612         * usage bit for all held locks, if hardirqs are
2613         * enabled too:
2614         */
2615        if (curr->hardirqs_enabled)
2616                mark_held_locks(curr, SOFTIRQ);
2617        current->lockdep_recursion = 0;
2618}
2619
2620/*
2621 * Softirqs were disabled:
2622 */
2623void trace_softirqs_off(unsigned long ip)
2624{
2625        struct task_struct *curr = current;
2626
2627        if (unlikely(!debug_locks || current->lockdep_recursion))
2628                return;
2629
2630        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2631                return;
2632
2633        if (curr->softirqs_enabled) {
2634                /*
2635                 * We have done an ON -> OFF transition:
2636                 */
2637                curr->softirqs_enabled = 0;
2638                curr->softirq_disable_ip = ip;
2639                curr->softirq_disable_event = ++curr->irq_events;
2640                debug_atomic_inc(softirqs_off_events);
2641                DEBUG_LOCKS_WARN_ON(!softirq_count());
2642        } else
2643                debug_atomic_inc(redundant_softirqs_off);
2644}
2645
2646static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2647{
2648        struct task_struct *curr = current;
2649
2650        if (unlikely(!debug_locks))
2651                return;
2652
2653        /* no reclaim without waiting on it */
2654        if (!(gfp_mask & __GFP_WAIT))
2655                return;
2656
2657        /* this guy won't enter reclaim */
2658        if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2659                return;
2660
2661        /* We're only interested __GFP_FS allocations for now */
2662        if (!(gfp_mask & __GFP_FS))
2663                return;
2664
2665        if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2666                return;
2667
2668        mark_held_locks(curr, RECLAIM_FS);
2669}
2670
2671static void check_flags(unsigned long flags);
2672
2673void lockdep_trace_alloc(gfp_t gfp_mask)
2674{
2675        unsigned long flags;
2676
2677        if (unlikely(current->lockdep_recursion))
2678                return;
2679
2680        raw_local_irq_save(flags);
2681        check_flags(flags);
2682        current->lockdep_recursion = 1;
2683        __lockdep_trace_alloc(gfp_mask, flags);
2684        current->lockdep_recursion = 0;
2685        raw_local_irq_restore(flags);
2686}
2687
2688static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2689{
2690        /*
2691         * If non-trylock use in a hardirq or softirq context, then
2692         * mark the lock as used in these contexts:
2693         */
2694        if (!hlock->trylock) {
2695                if (hlock->read) {
2696                        if (curr->hardirq_context)
2697                                if (!mark_lock(curr, hlock,
2698                                                LOCK_USED_IN_HARDIRQ_READ))
2699                                        return 0;
2700                        if (curr->softirq_context)
2701                                if (!mark_lock(curr, hlock,
2702                                                LOCK_USED_IN_SOFTIRQ_READ))
2703                                        return 0;
2704                } else {
2705                        if (curr->hardirq_context)
2706                                if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2707                                        return 0;
2708                        if (curr->softirq_context)
2709                                if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2710                                        return 0;
2711                }
2712        }
2713        if (!hlock->hardirqs_off) {
2714                if (hlock->read) {
2715                        if (!mark_lock(curr, hlock,
2716                                        LOCK_ENABLED_HARDIRQ_READ))
2717                                return 0;
2718                        if (curr->softirqs_enabled)
2719                                if (!mark_lock(curr, hlock,
2720                                                LOCK_ENABLED_SOFTIRQ_READ))
2721                                        return 0;
2722                } else {
2723                        if (!mark_lock(curr, hlock,
2724                                        LOCK_ENABLED_HARDIRQ))
2725                                return 0;
2726                        if (curr->softirqs_enabled)
2727                                if (!mark_lock(curr, hlock,
2728                                                LOCK_ENABLED_SOFTIRQ))
2729                                        return 0;
2730                }
2731        }
2732
2733        /*
2734         * We reuse the irq context infrastructure more broadly as a general
2735         * context checking code. This tests GFP_FS recursion (a lock taken
2736         * during reclaim for a GFP_FS allocation is held over a GFP_FS
2737         * allocation).
2738         */
2739        if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2740                if (hlock->read) {
2741                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2742                                        return 0;
2743                } else {
2744                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2745                                        return 0;
2746                }
2747        }
2748
2749        return 1;
2750}
2751
2752static int separate_irq_context(struct task_struct *curr,
2753                struct held_lock *hlock)
2754{
2755        unsigned int depth = curr->lockdep_depth;
2756
2757        /*
2758         * Keep track of points where we cross into an interrupt context:
2759         */
2760        hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2761                                curr->softirq_context;
2762        if (depth) {
2763                struct held_lock *prev_hlock;
2764
2765                prev_hlock = curr->held_locks + depth-1;
2766                /*
2767                 * If we cross into another context, reset the
2768                 * hash key (this also prevents the checking and the
2769                 * adding of the dependency to 'prev'):
2770                 */
2771                if (prev_hlock->irq_context != hlock->irq_context)
2772                        return 1;
2773        }
2774        return 0;
2775}
2776
2777#else
2778
2779static inline
2780int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2781                enum lock_usage_bit new_bit)
2782{
2783        WARN_ON(1);
2784        return 1;
2785}
2786
2787static inline int mark_irqflags(struct task_struct *curr,
2788                struct held_lock *hlock)
2789{
2790        return 1;
2791}
2792
2793static inline int separate_irq_context(struct task_struct *curr,
2794                struct held_lock *hlock)
2795{
2796        return 0;
2797}
2798
2799void lockdep_trace_alloc(gfp_t gfp_mask)
2800{
2801}
2802
2803#endif
2804
2805/*
2806 * Mark a lock with a usage bit, and validate the state transition:
2807 */
2808static int mark_lock(struct task_struct *curr, struct held_lock *this,
2809                             enum lock_usage_bit new_bit)
2810{
2811        unsigned int new_mask = 1 << new_bit, ret = 1;
2812
2813        /*
2814         * If already set then do not dirty the cacheline,
2815         * nor do any checks:
2816         */
2817        if (likely(hlock_class(this)->usage_mask & new_mask))
2818                return 1;
2819
2820        if (!graph_lock())
2821                return 0;
2822        /*
2823         * Make sure we didn't race:
2824         */
2825        if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2826                graph_unlock();
2827                return 1;
2828        }
2829
2830        hlock_class(this)->usage_mask |= new_mask;
2831
2832        if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2833                return 0;
2834
2835        switch (new_bit) {
2836#define LOCKDEP_STATE(__STATE)                  \
2837        case LOCK_USED_IN_##__STATE:            \
2838        case LOCK_USED_IN_##__STATE##_READ:     \
2839        case LOCK_ENABLED_##__STATE:            \
2840        case LOCK_ENABLED_##__STATE##_READ:
2841#include "lockdep_states.h"
2842#undef LOCKDEP_STATE
2843                ret = mark_lock_irq(curr, this, new_bit);
2844                if (!ret)
2845                        return 0;
2846                break;
2847        case LOCK_USED:
2848                debug_atomic_dec(nr_unused_locks);
2849                break;
2850        default:
2851                if (!debug_locks_off_graph_unlock())
2852                        return 0;
2853                WARN_ON(1);
2854                return 0;
2855        }
2856
2857        graph_unlock();
2858
2859        /*
2860         * We must printk outside of the graph_lock:
2861         */
2862        if (ret == 2) {
2863                printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2864                print_lock(this);
2865                print_irqtrace_events(curr);
2866                dump_stack();
2867        }
2868
2869        return ret;
2870}
2871
2872/*
2873 * Initialize a lock instance's lock-class mapping info:
2874 */
2875void lockdep_init_map(struct lockdep_map *lock, const char *name,
2876                      struct lock_class_key *key, int subclass)
2877{
2878        int i;
2879
2880        kmemcheck_mark_initialized(lock, sizeof(*lock));
2881
2882        for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2883                lock->class_cache[i] = NULL;
2884
2885#ifdef CONFIG_LOCK_STAT
2886        lock->cpu = raw_smp_processor_id();
2887#endif
2888
2889        if (DEBUG_LOCKS_WARN_ON(!name)) {
2890                lock->name = "NULL";
2891                return;
2892        }
2893
2894        lock->name = name;
2895
2896        if (DEBUG_LOCKS_WARN_ON(!key))
2897                return;
2898        /*
2899         * Sanity check, the lock-class key must be persistent:
2900         */
2901        if (!static_obj(key)) {
2902                printk("BUG: key %p not in .data!\n", key);
2903                DEBUG_LOCKS_WARN_ON(1);
2904                return;
2905        }
2906        lock->key = key;
2907
2908        if (unlikely(!debug_locks))
2909                return;
2910
2911        if (subclass)
2912                register_lock_class(lock, subclass, 1);
2913}
2914EXPORT_SYMBOL_GPL(lockdep_init_map);
2915
2916struct lock_class_key __lockdep_no_validate__;
2917
2918/*
2919 * This gets called for every mutex_lock*()/spin_lock*() operation.
2920 * We maintain the dependency maps and validate the locking attempt:
2921 */
2922static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2923                          int trylock, int read, int check, int hardirqs_off,
2924                          struct lockdep_map *nest_lock, unsigned long ip,
2925                          int references)
2926{
2927        struct task_struct *curr = current;
2928        struct lock_class *class = NULL;
2929        struct held_lock *hlock;
2930        unsigned int depth, id;
2931        int chain_head = 0;
2932        int class_idx;
2933        u64 chain_key;
2934
2935        if (!prove_locking)
2936                check = 1;
2937
2938        if (unlikely(!debug_locks))
2939                return 0;
2940
2941        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2942                return 0;
2943
2944        if (lock->key == &__lockdep_no_validate__)
2945                check = 1;
2946
2947        if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2948                class = lock->class_cache[subclass];
2949        /*
2950         * Not cached?
2951         */
2952        if (unlikely(!class)) {
2953                class = register_lock_class(lock, subclass, 0);
2954                if (!class)
2955                        return 0;
2956        }
2957        atomic_inc((atomic_t *)&class->ops);
2958        if (very_verbose(class)) {
2959                printk("\nacquire class [%p] %s", class->key, class->name);
2960                if (class->name_version > 1)
2961                        printk("#%d", class->name_version);
2962                printk("\n");
2963                dump_stack();
2964        }
2965
2966        /*
2967         * Add the lock to the list of currently held locks.
2968         * (we dont increase the depth just yet, up until the
2969         * dependency checks are done)
2970         */
2971        depth = curr->lockdep_depth;
2972        if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2973                return 0;
2974
2975        class_idx = class - lock_classes + 1;
2976
2977        if (depth) {
2978                hlock = curr->held_locks + depth - 1;
2979                if (hlock->class_idx == class_idx && nest_lock) {
2980                        if (hlock->references)
2981                                hlock->references++;
2982                        else
2983                                hlock->references = 2;
2984
2985                        return 1;
2986                }
2987        }
2988
2989        hlock = curr->held_locks + depth;
2990        if (DEBUG_LOCKS_WARN_ON(!class))
2991                return 0;
2992        hlock->class_idx = class_idx;
2993        hlock->acquire_ip = ip;
2994        hlock->instance = lock;
2995        hlock->nest_lock = nest_lock;
2996        hlock->trylock = trylock;
2997        hlock->read = read;
2998        hlock->check = check;
2999        hlock->hardirqs_off = !!hardirqs_off;
3000        hlock->references = references;
3001#ifdef CONFIG_LOCK_STAT
3002        hlock->waittime_stamp = 0;
3003        hlock->holdtime_stamp = lockstat_clock();
3004#endif
3005
3006        if (check == 2 && !mark_irqflags(curr, hlock))
3007                return 0;
3008
3009        /* mark it as used: */
3010        if (!mark_lock(curr, hlock, LOCK_USED))
3011                return 0;
3012
3013        /*
3014         * Calculate the chain hash: it's the combined hash of all the
3015         * lock keys along the dependency chain. We save the hash value
3016         * at every step so that we can get the current hash easily
3017         * after unlock. The chain hash is then used to cache dependency
3018         * results.
3019         *
3020         * The 'key ID' is what is the most compact key value to drive
3021         * the hash, not class->key.
3022         */
3023        id = class - lock_classes;
3024        if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3025                return 0;
3026
3027        chain_key = curr->curr_chain_key;
3028        if (!depth) {
3029                if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3030                        return 0;
3031                chain_head = 1;
3032        }
3033
3034        hlock->prev_chain_key = chain_key;
3035        if (separate_irq_context(curr, hlock)) {
3036                chain_key = 0;
3037                chain_head = 1;
3038        }
3039        chain_key = iterate_chain_key(chain_key, id);
3040
3041        if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3042                return 0;
3043
3044        curr->curr_chain_key = chain_key;
3045        curr->lockdep_depth++;
3046        check_chain_key(curr);
3047#ifdef CONFIG_DEBUG_LOCKDEP
3048        if (unlikely(!debug_locks))
3049                return 0;
3050#endif
3051        if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3052                debug_locks_off();
3053                printk("BUG: MAX_LOCK_DEPTH too low!\n");
3054                printk("turning off the locking correctness validator.\n");
3055                dump_stack();
3056                return 0;
3057        }
3058
3059        if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3060                max_lockdep_depth = curr->lockdep_depth;
3061
3062        return 1;
3063}
3064
3065static int
3066print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3067                           unsigned long ip)
3068{
3069        if (!debug_locks_off())
3070                return 0;
3071        if (debug_locks_silent)
3072                return 0;
3073
3074        printk("\n=====================================\n");
3075        printk(  "[ BUG: bad unlock balance detected! ]\n");
3076        printk(  "-------------------------------------\n");
3077        printk("%s/%d is trying to release lock (",
3078                curr->comm, task_pid_nr(curr));
3079        print_lockdep_cache(lock);
3080        printk(") at:\n");
3081        print_ip_sym(ip);
3082        printk("but there are no more locks to release!\n");
3083        printk("\nother info that might help us debug this:\n");
3084        lockdep_print_held_locks(curr);
3085
3086        printk("\nstack backtrace:\n");
3087        dump_stack();
3088
3089        return 0;
3090}
3091
3092/*
3093 * Common debugging checks for both nested and non-nested unlock:
3094 */
3095static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3096                        unsigned long ip)
3097{
3098        if (unlikely(!debug_locks))
3099                return 0;
3100        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3101                return 0;
3102
3103        if (curr->lockdep_depth <= 0)
3104                return print_unlock_inbalance_bug(curr, lock, ip);
3105
3106        return 1;
3107}
3108
3109static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3110{
3111        if (hlock->instance == lock)
3112                return 1;
3113
3114        if (hlock->references) {
3115                struct lock_class *class = lock->class_cache[0];
3116
3117                if (!class)
3118                        class = look_up_lock_class(lock, 0);
3119
3120                /*
3121                 * If look_up_lock_class() failed to find a class, we're trying
3122                 * to test if we hold a lock that has never yet been acquired.
3123                 * Clearly if the lock hasn't been acquired _ever_, we're not
3124                 * holding it either, so report failure.
3125                 */
3126                if (!class)
3127                        return 0;
3128
3129                if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3130                        return 0;
3131
3132                if (hlock->class_idx == class - lock_classes + 1)
3133                        return 1;
3134        }
3135
3136        return 0;
3137}
3138
3139static int
3140__lock_set_class(struct lockdep_map *lock, const char *name,
3141                 struct lock_class_key *key, unsigned int subclass,
3142                 unsigned long ip)
3143{
3144        struct task_struct *curr = current;
3145        struct held_lock *hlock, *prev_hlock;
3146        struct lock_class *class;
3147        unsigned int depth;
3148        int i;
3149
3150        depth = curr->lockdep_depth;
3151        if (DEBUG_LOCKS_WARN_ON(!depth))
3152                return 0;
3153
3154        prev_hlock = NULL;
3155        for (i = depth-1; i >= 0; i--) {
3156                hlock = curr->held_locks + i;
3157                /*
3158                 * We must not cross into another context:
3159                 */
3160                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3161                        break;
3162                if (match_held_lock(hlock, lock))
3163                        goto found_it;
3164                prev_hlock = hlock;
3165        }
3166        return print_unlock_inbalance_bug(curr, lock, ip);
3167
3168found_it:
3169        lockdep_init_map(lock, name, key, 0);
3170        class = register_lock_class(lock, subclass, 0);
3171        hlock->class_idx = class - lock_classes + 1;
3172
3173        curr->lockdep_depth = i;
3174        curr->curr_chain_key = hlock->prev_chain_key;
3175
3176        for (; i < depth; i++) {
3177                hlock = curr->held_locks + i;
3178                if (!__lock_acquire(hlock->instance,
3179                        hlock_class(hlock)->subclass, hlock->trylock,
3180                                hlock->read, hlock->check, hlock->hardirqs_off,
3181                                hlock->nest_lock, hlock->acquire_ip,
3182                                hlock->references))
3183                        return 0;
3184        }
3185
3186        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3187                return 0;
3188        return 1;
3189}
3190
3191/*
3192 * Remove the lock to the list of currently held locks in a
3193 * potentially non-nested (out of order) manner. This is a
3194 * relatively rare operation, as all the unlock APIs default
3195 * to nested mode (which uses lock_release()):
3196 */
3197static int
3198lock_release_non_nested(struct task_struct *curr,
3199                        struct lockdep_map *lock, unsigned long ip)
3200{
3201        struct held_lock *hlock, *prev_hlock;
3202        unsigned int depth;
3203        int i;
3204
3205        /*
3206         * Check whether the lock exists in the current stack
3207         * of held locks:
3208         */
3209        depth = curr->lockdep_depth;
3210        if (DEBUG_LOCKS_WARN_ON(!depth))
3211                return 0;
3212
3213        prev_hlock = NULL;
3214        for (i = depth-1; i >= 0; i--) {
3215                hlock = curr->held_locks + i;
3216                /*
3217                 * We must not cross into another context:
3218                 */
3219                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3220                        break;
3221                if (match_held_lock(hlock, lock))
3222                        goto found_it;
3223                prev_hlock = hlock;
3224        }
3225        return print_unlock_inbalance_bug(curr, lock, ip);
3226
3227found_it:
3228        if (hlock->instance == lock)
3229                lock_release_holdtime(hlock);
3230
3231        if (hlock->references) {
3232                hlock->references--;
3233                if (hlock->references) {
3234                        /*
3235                         * We had, and after removing one, still have
3236                         * references, the current lock stack is still
3237                         * valid. We're done!
3238                         */
3239                        return 1;
3240                }
3241        }
3242
3243        /*
3244         * We have the right lock to unlock, 'hlock' points to it.
3245         * Now we remove it from the stack, and add back the other
3246         * entries (if any), recalculating the hash along the way:
3247         */
3248
3249        curr->lockdep_depth = i;
3250        curr->curr_chain_key = hlock->prev_chain_key;
3251
3252        for (i++; i < depth; i++) {
3253                hlock = curr->held_locks + i;
3254                if (!__lock_acquire(hlock->instance,
3255                        hlock_class(hlock)->subclass, hlock->trylock,
3256                                hlock->read, hlock->check, hlock->hardirqs_off,
3257                                hlock->nest_lock, hlock->acquire_ip,
3258                                hlock->references))
3259                        return 0;
3260        }
3261
3262        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3263                return 0;
3264        return 1;
3265}
3266
3267/*
3268 * Remove the lock to the list of currently held locks - this gets
3269 * called on mutex_unlock()/spin_unlock*() (or on a failed
3270 * mutex_lock_interruptible()). This is done for unlocks that nest
3271 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3272 */
3273static int lock_release_nested(struct task_struct *curr,
3274                               struct lockdep_map *lock, unsigned long ip)
3275{
3276        struct held_lock *hlock;
3277        unsigned int depth;
3278
3279        /*
3280         * Pop off the top of the lock stack:
3281         */
3282        depth = curr->lockdep_depth - 1;
3283        hlock = curr->held_locks + depth;
3284
3285        /*
3286         * Is the unlock non-nested:
3287         */
3288        if (hlock->instance != lock || hlock->references)
3289                return lock_release_non_nested(curr, lock, ip);
3290        curr->lockdep_depth--;
3291
3292        if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3293                return 0;
3294
3295        curr->curr_chain_key = hlock->prev_chain_key;
3296
3297        lock_release_holdtime(hlock);
3298
3299#ifdef CONFIG_DEBUG_LOCKDEP
3300        hlock->prev_chain_key = 0;
3301        hlock->class_idx = 0;
3302        hlock->acquire_ip = 0;
3303        hlock->irq_context = 0;
3304#endif
3305        return 1;
3306}
3307
3308/*
3309 * Remove the lock to the list of currently held locks - this gets
3310 * called on mutex_unlock()/spin_unlock*() (or on a failed
3311 * mutex_lock_interruptible()). This is done for unlocks that nest
3312 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3313 */
3314static void
3315__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3316{
3317        struct task_struct *curr = current;
3318
3319        if (!check_unlock(curr, lock, ip))
3320                return;
3321
3322        if (nested) {
3323                if (!lock_release_nested(curr, lock, ip))
3324                        return;
3325        } else {
3326                if (!lock_release_non_nested(curr, lock, ip))
3327                        return;
3328        }
3329
3330        check_chain_key(curr);
3331}
3332
3333static int __lock_is_held(struct lockdep_map *lock)
3334{
3335        struct task_struct *curr = current;
3336        int i;
3337
3338        for (i = 0; i < curr->lockdep_depth; i++) {
3339                struct held_lock *hlock = curr->held_locks + i;
3340
3341                if (match_held_lock(hlock, lock))
3342                        return 1;
3343        }
3344
3345        return 0;
3346}
3347
3348/*
3349 * Check whether we follow the irq-flags state precisely:
3350 */
3351static void check_flags(unsigned long flags)
3352{
3353#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3354    defined(CONFIG_TRACE_IRQFLAGS)
3355        if (!debug_locks)
3356                return;
3357
3358        if (irqs_disabled_flags(flags)) {
3359                if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3360                        printk("possible reason: unannotated irqs-off.\n");
3361                }
3362        } else {
3363                if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3364                        printk("possible reason: unannotated irqs-on.\n");
3365                }
3366        }
3367
3368        /*
3369         * We dont accurately track softirq state in e.g.
3370         * hardirq contexts (such as on 4KSTACKS), so only
3371         * check if not in hardirq contexts:
3372         */
3373        if (!hardirq_count()) {
3374                if (softirq_count())
3375                        DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3376                else
3377                        DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3378        }
3379
3380        if (!debug_locks)
3381                print_irqtrace_events(current);
3382#endif
3383}
3384
3385void lock_set_class(struct lockdep_map *lock, const char *name,
3386                    struct lock_class_key *key, unsigned int subclass,
3387                    unsigned long ip)
3388{
3389        unsigned long flags;
3390
3391        if (unlikely(current->lockdep_recursion))
3392                return;
3393
3394        raw_local_irq_save(flags);
3395        current->lockdep_recursion = 1;
3396        check_flags(flags);
3397        if (__lock_set_class(lock, name, key, subclass, ip))
3398                check_chain_key(current);
3399        current->lockdep_recursion = 0;
3400        raw_local_irq_restore(flags);
3401}
3402EXPORT_SYMBOL_GPL(lock_set_class);
3403
3404/*
3405 * We are not always called with irqs disabled - do that here,
3406 * and also avoid lockdep recursion:
3407 */
3408void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3409                          int trylock, int read, int check,
3410                          struct lockdep_map *nest_lock, unsigned long ip)
3411{
3412        unsigned long flags;
3413
3414        if (unlikely(current->lockdep_recursion))
3415                return;
3416
3417        raw_local_irq_save(flags);
3418        check_flags(flags);
3419
3420        current->lockdep_recursion = 1;
3421        trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3422        __lock_acquire(lock, subclass, trylock, read, check,
3423                       irqs_disabled_flags(flags), nest_lock, ip, 0);
3424        current->lockdep_recursion = 0;
3425        raw_local_irq_restore(flags);
3426}
3427EXPORT_SYMBOL_GPL(lock_acquire);
3428
3429void lock_release(struct lockdep_map *lock, int nested,
3430                          unsigned long ip)
3431{
3432        unsigned long flags;
3433
3434        if (unlikely(current->lockdep_recursion))
3435                return;
3436
3437        raw_local_irq_save(flags);
3438        check_flags(flags);
3439        current->lockdep_recursion = 1;
3440        trace_lock_release(lock, ip);
3441        __lock_release(lock, nested, ip);
3442        current->lockdep_recursion = 0;
3443        raw_local_irq_restore(flags);
3444}
3445EXPORT_SYMBOL_GPL(lock_release);
3446
3447int lock_is_held(struct lockdep_map *lock)
3448{
3449        unsigned long flags;
3450        int ret = 0;
3451
3452        if (unlikely(current->lockdep_recursion))
3453                return 1; /* avoid false negative lockdep_assert_held() */
3454
3455        raw_local_irq_save(flags);
3456        check_flags(flags);
3457
3458        current->lockdep_recursion = 1;
3459        ret = __lock_is_held(lock);
3460        current->lockdep_recursion = 0;
3461        raw_local_irq_restore(flags);
3462
3463        return ret;
3464}
3465EXPORT_SYMBOL_GPL(lock_is_held);
3466
3467void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3468{
3469        current->lockdep_reclaim_gfp = gfp_mask;
3470}
3471
3472void lockdep_clear_current_reclaim_state(void)
3473{
3474        current->lockdep_reclaim_gfp = 0;
3475}
3476
3477#ifdef CONFIG_LOCK_STAT
3478static int
3479print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3480                           unsigned long ip)
3481{
3482        if (!debug_locks_off())
3483                return 0;
3484        if (debug_locks_silent)
3485                return 0;
3486
3487        printk("\n=================================\n");
3488        printk(  "[ BUG: bad contention detected! ]\n");
3489        printk(  "---------------------------------\n");
3490        printk("%s/%d is trying to contend lock (",
3491                curr->comm, task_pid_nr(curr));
3492        print_lockdep_cache(lock);
3493        printk(") at:\n");
3494        print_ip_sym(ip);
3495        printk("but there are no locks held!\n");
3496        printk("\nother info that might help us debug this:\n");
3497        lockdep_print_held_locks(curr);
3498
3499        printk("\nstack backtrace:\n");
3500        dump_stack();
3501
3502        return 0;
3503}
3504
3505static void
3506__lock_contended(struct lockdep_map *lock, unsigned long ip)
3507{
3508        struct task_struct *curr = current;
3509        struct held_lock *hlock, *prev_hlock;
3510        struct lock_class_stats *stats;
3511        unsigned int depth;
3512        int i, contention_point, contending_point;
3513
3514        depth = curr->lockdep_depth;
3515        if (DEBUG_LOCKS_WARN_ON(!depth))
3516                return;
3517
3518        prev_hlock = NULL;
3519        for (i = depth-1; i >= 0; i--) {
3520                hlock = curr->held_locks + i;
3521                /*
3522                 * We must not cross into another context:
3523                 */
3524                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3525                        break;
3526                if (match_held_lock(hlock, lock))
3527                        goto found_it;
3528                prev_hlock = hlock;
3529        }
3530        print_lock_contention_bug(curr, lock, ip);
3531        return;
3532
3533found_it:
3534        if (hlock->instance != lock)
3535                return;
3536
3537        hlock->waittime_stamp = lockstat_clock();
3538
3539        contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3540        contending_point = lock_point(hlock_class(hlock)->contending_point,
3541                                      lock->ip);
3542
3543        stats = get_lock_stats(hlock_class(hlock));
3544        if (contention_point < LOCKSTAT_POINTS)
3545                stats->contention_point[contention_point]++;
3546        if (contending_point < LOCKSTAT_POINTS)
3547                stats->contending_point[contending_point]++;
3548        if (lock->cpu != smp_processor_id())
3549                stats->bounces[bounce_contended + !!hlock->read]++;
3550        put_lock_stats(stats);
3551}
3552
3553static void
3554__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3555{
3556        struct task_struct *curr = current;
3557        struct held_lock *hlock, *prev_hlock;
3558        struct lock_class_stats *stats;
3559        unsigned int depth;
3560        u64 now, waittime = 0;
3561        int i, cpu;
3562
3563        depth = curr->lockdep_depth;
3564        if (DEBUG_LOCKS_WARN_ON(!depth))
3565                return;
3566
3567        prev_hlock = NULL;
3568        for (i = depth-1; i >= 0; i--) {
3569                hlock = curr->held_locks + i;
3570                /*
3571                 * We must not cross into another context:
3572                 */
3573                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3574                        break;
3575                if (match_held_lock(hlock, lock))
3576                        goto found_it;
3577                prev_hlock = hlock;
3578        }
3579        print_lock_contention_bug(curr, lock, _RET_IP_);
3580        return;
3581
3582found_it:
3583        if (hlock->instance != lock)
3584                return;
3585
3586        cpu = smp_processor_id();
3587        if (hlock->waittime_stamp) {
3588                now = lockstat_clock();
3589                waittime = now - hlock->waittime_stamp;
3590                hlock->holdtime_stamp = now;
3591        }
3592
3593        trace_lock_acquired(lock, ip);
3594
3595        stats = get_lock_stats(hlock_class(hlock));
3596        if (waittime) {
3597                if (hlock->read)
3598                        lock_time_inc(&stats->read_waittime, waittime);
3599                else
3600                        lock_time_inc(&stats->write_waittime, waittime);
3601        }
3602        if (lock->cpu != cpu)
3603                stats->bounces[bounce_acquired + !!hlock->read]++;
3604        put_lock_stats(stats);
3605
3606        lock->cpu = cpu;
3607        lock->ip = ip;
3608}
3609
3610void lock_contended(struct lockdep_map *lock, unsigned long ip)
3611{
3612        unsigned long flags;
3613
3614        if (unlikely(!lock_stat))
3615                return;
3616
3617        if (unlikely(current->lockdep_recursion))
3618                return;
3619
3620        raw_local_irq_save(flags);
3621        check_flags(flags);
3622        current->lockdep_recursion = 1;
3623        trace_lock_contended(lock, ip);
3624        __lock_contended(lock, ip);
3625        current->lockdep_recursion = 0;
3626        raw_local_irq_restore(flags);
3627}
3628EXPORT_SYMBOL_GPL(lock_contended);
3629
3630void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3631{
3632        unsigned long flags;
3633
3634        if (unlikely(!lock_stat))
3635                return;
3636
3637        if (unlikely(current->lockdep_recursion))
3638                return;
3639
3640        raw_local_irq_save(flags);
3641        check_flags(flags);
3642        current->lockdep_recursion = 1;
3643        __lock_acquired(lock, ip);
3644        current->lockdep_recursion = 0;
3645        raw_local_irq_restore(flags);
3646}
3647EXPORT_SYMBOL_GPL(lock_acquired);
3648#endif
3649
3650/*
3651 * Used by the testsuite, sanitize the validator state
3652 * after a simulated failure:
3653 */
3654
3655void lockdep_reset(void)
3656{
3657        unsigned long flags;
3658        int i;
3659
3660        raw_local_irq_save(flags);
3661        current->curr_chain_key = 0;
3662        current->lockdep_depth = 0;
3663        current->lockdep_recursion = 0;
3664        memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3665        nr_hardirq_chains = 0;
3666        nr_softirq_chains = 0;
3667        nr_process_chains = 0;
3668        debug_locks = 1;
3669        for (i = 0; i < CHAINHASH_SIZE; i++)
3670                INIT_LIST_HEAD(chainhash_table + i);
3671        raw_local_irq_restore(flags);
3672}
3673
3674static void zap_class(struct lock_class *class)
3675{
3676        int i;
3677
3678        /*
3679         * Remove all dependencies this lock is
3680         * involved in:
3681         */
3682        for (i = 0; i < nr_list_entries; i++) {
3683                if (list_entries[i].class == class)
3684                        list_del_rcu(&list_entries[i].entry);
3685        }
3686        /*
3687         * Unhash the class and remove it from the all_lock_classes list:
3688         */
3689        list_del_rcu(&class->hash_entry);
3690        list_del_rcu(&class->lock_entry);
3691
3692        class->key = NULL;
3693}
3694
3695static inline int within(const void *addr, void *start, unsigned long size)
3696{
3697        return addr >= start && addr < start + size;
3698}
3699
3700void lockdep_free_key_range(void *start, unsigned long size)
3701{
3702        struct lock_class *class, *next;
3703        struct list_head *head;
3704        unsigned long flags;
3705        int i;
3706        int locked;
3707
3708        raw_local_irq_save(flags);
3709        locked = graph_lock();
3710
3711        /*
3712         * Unhash all classes that were created by this module:
3713         */
3714        for (i = 0; i < CLASSHASH_SIZE; i++) {
3715                head = classhash_table + i;
3716                if (list_empty(head))
3717                        continue;
3718                list_for_each_entry_safe(class, next, head, hash_entry) {
3719                        if (within(class->key, start, size))
3720                                zap_class(class);
3721                        else if (within(class->name, start, size))
3722                                zap_class(class);
3723                }
3724        }
3725
3726        if (locked)
3727                graph_unlock();
3728        raw_local_irq_restore(flags);
3729}
3730
3731void lockdep_reset_lock(struct lockdep_map *lock)
3732{
3733        struct lock_class *class, *next;
3734        struct list_head *head;
3735        unsigned long flags;
3736        int i, j;
3737        int locked;
3738
3739        raw_local_irq_save(flags);
3740
3741        /*
3742         * Remove all classes this lock might have:
3743         */
3744        for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3745                /*
3746                 * If the class exists we look it up and zap it:
3747                 */
3748                class = look_up_lock_class(lock, j);
3749                if (class)
3750                        zap_class(class);
3751        }
3752        /*
3753         * Debug check: in the end all mapped classes should
3754         * be gone.
3755         */
3756        locked = graph_lock();
3757        for (i = 0; i < CLASSHASH_SIZE; i++) {
3758                head = classhash_table + i;
3759                if (list_empty(head))
3760                        continue;
3761                list_for_each_entry_safe(class, next, head, hash_entry) {
3762                        int match = 0;
3763
3764                        for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3765                                match |= class == lock->class_cache[j];
3766
3767                        if (unlikely(match)) {
3768                                if (debug_locks_off_graph_unlock())
3769                                        WARN_ON(1);
3770                                goto out_restore;
3771                        }
3772                }
3773        }
3774        if (locked)
3775                graph_unlock();
3776
3777out_restore:
3778        raw_local_irq_restore(flags);
3779}
3780
3781void lockdep_init(void)
3782{
3783        int i;
3784
3785        /*
3786         * Some architectures have their own start_kernel()
3787         * code which calls lockdep_init(), while we also
3788         * call lockdep_init() from the start_kernel() itself,
3789         * and we want to initialize the hashes only once:
3790         */
3791        if (lockdep_initialized)
3792                return;
3793
3794        for (i = 0; i < CLASSHASH_SIZE; i++)
3795                INIT_LIST_HEAD(classhash_table + i);
3796
3797        for (i = 0; i < CHAINHASH_SIZE; i++)
3798                INIT_LIST_HEAD(chainhash_table + i);
3799
3800        lockdep_initialized = 1;
3801}
3802
3803void __init lockdep_info(void)
3804{
3805        printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3806
3807        printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3808        printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3809        printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3810        printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3811        printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3812        printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3813        printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3814
3815        printk(" memory used by lock dependency info: %lu kB\n",
3816                (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3817                sizeof(struct list_head) * CLASSHASH_SIZE +
3818                sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3819                sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3820                sizeof(struct list_head) * CHAINHASH_SIZE
3821#ifdef CONFIG_PROVE_LOCKING
3822                + sizeof(struct circular_queue)
3823#endif
3824                ) / 1024
3825                );
3826
3827        printk(" per task-struct memory footprint: %lu bytes\n",
3828                sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3829
3830#ifdef CONFIG_DEBUG_LOCKDEP
3831        if (lockdep_init_error) {
3832                printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3833                printk("Call stack leading to lockdep invocation was:\n");
3834                print_stack_trace(&lockdep_init_trace, 0);
3835        }
3836#endif
3837}
3838
3839static void
3840print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3841                     const void *mem_to, struct held_lock *hlock)
3842{
3843        if (!debug_locks_off())
3844                return;
3845        if (debug_locks_silent)
3846                return;
3847
3848        printk("\n=========================\n");
3849        printk(  "[ BUG: held lock freed! ]\n");
3850        printk(  "-------------------------\n");
3851        printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3852                curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3853        print_lock(hlock);
3854        lockdep_print_held_locks(curr);
3855
3856        printk("\nstack backtrace:\n");
3857        dump_stack();
3858}
3859
3860static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3861                                const void* lock_from, unsigned long lock_len)
3862{
3863        return lock_from + lock_len <= mem_from ||
3864                mem_from + mem_len <= lock_from;
3865}
3866
3867/*
3868 * Called when kernel memory is freed (or unmapped), or if a lock
3869 * is destroyed or reinitialized - this code checks whether there is
3870 * any held lock in the memory range of <from> to <to>:
3871 */
3872void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3873{
3874        struct task_struct *curr = current;
3875        struct held_lock *hlock;
3876        unsigned long flags;
3877        int i;
3878
3879        if (unlikely(!debug_locks))
3880                return;
3881
3882        local_irq_save(flags);
3883        for (i = 0; i < curr->lockdep_depth; i++) {
3884                hlock = curr->held_locks + i;
3885
3886                if (not_in_range(mem_from, mem_len, hlock->instance,
3887                                        sizeof(*hlock->instance)))
3888                        continue;
3889
3890                print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3891                break;
3892        }
3893        local_irq_restore(flags);
3894}
3895EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3896
3897static void print_held_locks_bug(struct task_struct *curr)
3898{
3899        if (!debug_locks_off())
3900                return;
3901        if (debug_locks_silent)
3902                return;
3903
3904        printk("\n=====================================\n");
3905        printk(  "[ BUG: lock held at task exit time! ]\n");
3906        printk(  "-------------------------------------\n");
3907        printk("%s/%d is exiting with locks still held!\n",
3908                curr->comm, task_pid_nr(curr));
3909        lockdep_print_held_locks(curr);
3910
3911        printk("\nstack backtrace:\n");
3912        dump_stack();
3913}
3914
3915void debug_check_no_locks_held(struct task_struct *task)
3916{
3917        if (unlikely(task->lockdep_depth > 0))
3918                print_held_locks_bug(task);
3919}
3920
3921void debug_show_all_locks(void)
3922{
3923        struct task_struct *g, *p;
3924        int count = 10;
3925        int unlock = 1;
3926
3927        if (unlikely(!debug_locks)) {
3928                printk("INFO: lockdep is turned off.\n");
3929                return;
3930        }
3931        printk("\nShowing all locks held in the system:\n");
3932
3933        /*
3934         * Here we try to get the tasklist_lock as hard as possible,
3935         * if not successful after 2 seconds we ignore it (but keep
3936         * trying). This is to enable a debug printout even if a
3937         * tasklist_lock-holding task deadlocks or crashes.
3938         */
3939retry:
3940        if (!read_trylock(&tasklist_lock)) {
3941                if (count == 10)
3942                        printk("hm, tasklist_lock locked, retrying... ");
3943                if (count) {
3944                        count--;
3945                        printk(" #%d", 10-count);
3946                        mdelay(200);
3947                        goto retry;
3948                }
3949                printk(" ignoring it.\n");
3950                unlock = 0;
3951        } else {
3952                if (count != 10)
3953                        printk(KERN_CONT " locked it.\n");
3954        }
3955
3956        do_each_thread(g, p) {
3957                /*
3958                 * It's not reliable to print a task's held locks
3959                 * if it's not sleeping (or if it's not the current
3960                 * task):
3961                 */
3962                if (p->state == TASK_RUNNING && p != current)
3963                        continue;
3964                if (p->lockdep_depth)
3965                        lockdep_print_held_locks(p);
3966                if (!unlock)
3967                        if (read_trylock(&tasklist_lock))
3968                                unlock = 1;
3969        } while_each_thread(g, p);
3970
3971        printk("\n");
3972        printk("=============================================\n\n");
3973
3974        if (unlock)
3975                read_unlock(&tasklist_lock);
3976}
3977EXPORT_SYMBOL_GPL(debug_show_all_locks);
3978
3979/*
3980 * Careful: only use this function if you are sure that
3981 * the task cannot run in parallel!
3982 */
3983void debug_show_held_locks(struct task_struct *task)
3984{
3985        if (unlikely(!debug_locks)) {
3986                printk("INFO: lockdep is turned off.\n");
3987                return;
3988        }
3989        lockdep_print_held_locks(task);
3990}
3991EXPORT_SYMBOL_GPL(debug_show_held_locks);
3992
3993void lockdep_sys_exit(void)
3994{
3995        struct task_struct *curr = current;
3996
3997        if (unlikely(curr->lockdep_depth)) {
3998                if (!debug_locks_off())
3999                        return;
4000                printk("\n================================================\n");
4001                printk(  "[ BUG: lock held when returning to user space! ]\n");
4002                printk(  "------------------------------------------------\n");
4003                printk("%s/%d is leaving the kernel with locks still held!\n",
4004                                curr->comm, curr->pid);
4005                lockdep_print_held_locks(curr);
4006        }
4007}
4008
4009void lockdep_rcu_dereference(const char *file, const int line)
4010{
4011        struct task_struct *curr = current;
4012
4013#ifndef CONFIG_PROVE_RCU_REPEATEDLY
4014        if (!debug_locks_off())
4015                return;
4016#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4017        /* Note: the following can be executed concurrently, so be careful. */
4018        printk("\n===================================================\n");
4019        printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
4020        printk(  "---------------------------------------------------\n");
4021        printk("%s:%d invoked rcu_dereference_check() without protection!\n",
4022                        file, line);
4023        printk("\nother info that might help us debug this:\n\n");
4024        printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
4025        lockdep_print_held_locks(curr);
4026        printk("\nstack backtrace:\n");
4027        dump_stack();
4028}
4029EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);
4030
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