linux/kernel/lockdep.c
<<
>>
Prefs
   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                /*
 102                 * The lockdep graph lock isn't locked while we expect it to
 103                 * be, we're confused now, bye!
 104                 */
 105                return DEBUG_LOCKS_WARN_ON(1);
 106        }
 107
 108        current->lockdep_recursion--;
 109        arch_spin_unlock(&lockdep_lock);
 110        return 0;
 111}
 112
 113/*
 114 * Turn lock debugging off and return with 0 if it was off already,
 115 * and also release the graph lock:
 116 */
 117static inline int debug_locks_off_graph_unlock(void)
 118{
 119        int ret = debug_locks_off();
 120
 121        arch_spin_unlock(&lockdep_lock);
 122
 123        return ret;
 124}
 125
 126static int lockdep_initialized;
 127
 128unsigned long nr_list_entries;
 129static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
 130
 131/*
 132 * All data structures here are protected by the global debug_lock.
 133 *
 134 * Mutex key structs only get allocated, once during bootup, and never
 135 * get freed - this significantly simplifies the debugging code.
 136 */
 137unsigned long nr_lock_classes;
 138static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
 139
 140static inline struct lock_class *hlock_class(struct held_lock *hlock)
 141{
 142        if (!hlock->class_idx) {
 143                /*
 144                 * Someone passed in garbage, we give up.
 145                 */
 146                DEBUG_LOCKS_WARN_ON(1);
 147                return NULL;
 148        }
 149        return lock_classes + hlock->class_idx - 1;
 150}
 151
 152#ifdef CONFIG_LOCK_STAT
 153static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
 154                      cpu_lock_stats);
 155
 156static inline u64 lockstat_clock(void)
 157{
 158        return local_clock();
 159}
 160
 161static int lock_point(unsigned long points[], unsigned long ip)
 162{
 163        int i;
 164
 165        for (i = 0; i < LOCKSTAT_POINTS; i++) {
 166                if (points[i] == 0) {
 167                        points[i] = ip;
 168                        break;
 169                }
 170                if (points[i] == ip)
 171                        break;
 172        }
 173
 174        return i;
 175}
 176
 177static void lock_time_inc(struct lock_time *lt, u64 time)
 178{
 179        if (time > lt->max)
 180                lt->max = time;
 181
 182        if (time < lt->min || !lt->nr)
 183                lt->min = time;
 184
 185        lt->total += time;
 186        lt->nr++;
 187}
 188
 189static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
 190{
 191        if (!src->nr)
 192                return;
 193
 194        if (src->max > dst->max)
 195                dst->max = src->max;
 196
 197        if (src->min < dst->min || !dst->nr)
 198                dst->min = src->min;
 199
 200        dst->total += src->total;
 201        dst->nr += src->nr;
 202}
 203
 204struct lock_class_stats lock_stats(struct lock_class *class)
 205{
 206        struct lock_class_stats stats;
 207        int cpu, i;
 208
 209        memset(&stats, 0, sizeof(struct lock_class_stats));
 210        for_each_possible_cpu(cpu) {
 211                struct lock_class_stats *pcs =
 212                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
 213
 214                for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
 215                        stats.contention_point[i] += pcs->contention_point[i];
 216
 217                for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
 218                        stats.contending_point[i] += pcs->contending_point[i];
 219
 220                lock_time_add(&pcs->read_waittime, &stats.read_waittime);
 221                lock_time_add(&pcs->write_waittime, &stats.write_waittime);
 222
 223                lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
 224                lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
 225
 226                for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
 227                        stats.bounces[i] += pcs->bounces[i];
 228        }
 229
 230        return stats;
 231}
 232
 233void clear_lock_stats(struct lock_class *class)
 234{
 235        int cpu;
 236
 237        for_each_possible_cpu(cpu) {
 238                struct lock_class_stats *cpu_stats =
 239                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
 240
 241                memset(cpu_stats, 0, sizeof(struct lock_class_stats));
 242        }
 243        memset(class->contention_point, 0, sizeof(class->contention_point));
 244        memset(class->contending_point, 0, sizeof(class->contending_point));
 245}
 246
 247static struct lock_class_stats *get_lock_stats(struct lock_class *class)
 248{
 249        return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
 250}
 251
 252static void put_lock_stats(struct lock_class_stats *stats)
 253{
 254        put_cpu_var(cpu_lock_stats);
 255}
 256
 257static void lock_release_holdtime(struct held_lock *hlock)
 258{
 259        struct lock_class_stats *stats;
 260        u64 holdtime;
 261
 262        if (!lock_stat)
 263                return;
 264
 265        holdtime = lockstat_clock() - hlock->holdtime_stamp;
 266
 267        stats = get_lock_stats(hlock_class(hlock));
 268        if (hlock->read)
 269                lock_time_inc(&stats->read_holdtime, holdtime);
 270        else
 271                lock_time_inc(&stats->write_holdtime, holdtime);
 272        put_lock_stats(stats);
 273}
 274#else
 275static inline void lock_release_holdtime(struct held_lock *hlock)
 276{
 277}
 278#endif
 279
 280/*
 281 * We keep a global list of all lock classes. The list only grows,
 282 * never shrinks. The list is only accessed with the lockdep
 283 * spinlock lock held.
 284 */
 285LIST_HEAD(all_lock_classes);
 286
 287/*
 288 * The lockdep classes are in a hash-table as well, for fast lookup:
 289 */
 290#define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
 291#define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
 292#define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
 293#define classhashentry(key)     (classhash_table + __classhashfn((key)))
 294
 295static struct list_head classhash_table[CLASSHASH_SIZE];
 296
 297/*
 298 * We put the lock dependency chains into a hash-table as well, to cache
 299 * their existence:
 300 */
 301#define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
 302#define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
 303#define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
 304#define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
 305
 306static struct list_head chainhash_table[CHAINHASH_SIZE];
 307
 308/*
 309 * The hash key of the lock dependency chains is a hash itself too:
 310 * it's a hash of all locks taken up to that lock, including that lock.
 311 * It's a 64-bit hash, because it's important for the keys to be
 312 * unique.
 313 */
 314#define iterate_chain_key(key1, key2) \
 315        (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
 316        ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
 317        (key2))
 318
 319void lockdep_off(void)
 320{
 321        current->lockdep_recursion++;
 322}
 323EXPORT_SYMBOL(lockdep_off);
 324
 325void lockdep_on(void)
 326{
 327        current->lockdep_recursion--;
 328}
 329EXPORT_SYMBOL(lockdep_on);
 330
 331/*
 332 * Debugging switches:
 333 */
 334
 335#define VERBOSE                 0
 336#define VERY_VERBOSE            0
 337
 338#if VERBOSE
 339# define HARDIRQ_VERBOSE        1
 340# define SOFTIRQ_VERBOSE        1
 341# define RECLAIM_VERBOSE        1
 342#else
 343# define HARDIRQ_VERBOSE        0
 344# define SOFTIRQ_VERBOSE        0
 345# define RECLAIM_VERBOSE        0
 346#endif
 347
 348#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
 349/*
 350 * Quick filtering for interesting events:
 351 */
 352static int class_filter(struct lock_class *class)
 353{
 354#if 0
 355        /* Example */
 356        if (class->name_version == 1 &&
 357                        !strcmp(class->name, "lockname"))
 358                return 1;
 359        if (class->name_version == 1 &&
 360                        !strcmp(class->name, "&struct->lockfield"))
 361                return 1;
 362#endif
 363        /* Filter everything else. 1 would be to allow everything else */
 364        return 0;
 365}
 366#endif
 367
 368static int verbose(struct lock_class *class)
 369{
 370#if VERBOSE
 371        return class_filter(class);
 372#endif
 373        return 0;
 374}
 375
 376/*
 377 * Stack-trace: tightly packed array of stack backtrace
 378 * addresses. Protected by the graph_lock.
 379 */
 380unsigned long nr_stack_trace_entries;
 381static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
 382
 383static int save_trace(struct stack_trace *trace)
 384{
 385        trace->nr_entries = 0;
 386        trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
 387        trace->entries = stack_trace + nr_stack_trace_entries;
 388
 389        trace->skip = 3;
 390
 391        save_stack_trace(trace);
 392
 393        /*
 394         * Some daft arches put -1 at the end to indicate its a full trace.
 395         *
 396         * <rant> this is buggy anyway, since it takes a whole extra entry so a
 397         * complete trace that maxes out the entries provided will be reported
 398         * as incomplete, friggin useless </rant>
 399         */
 400        if (trace->nr_entries != 0 &&
 401            trace->entries[trace->nr_entries-1] == ULONG_MAX)
 402                trace->nr_entries--;
 403
 404        trace->max_entries = trace->nr_entries;
 405
 406        nr_stack_trace_entries += trace->nr_entries;
 407
 408        if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
 409                if (!debug_locks_off_graph_unlock())
 410                        return 0;
 411
 412                printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
 413                printk("turning off the locking correctness validator.\n");
 414                dump_stack();
 415
 416                return 0;
 417        }
 418
 419        return 1;
 420}
 421
 422unsigned int nr_hardirq_chains;
 423unsigned int nr_softirq_chains;
 424unsigned int nr_process_chains;
 425unsigned int max_lockdep_depth;
 426
 427#ifdef CONFIG_DEBUG_LOCKDEP
 428/*
 429 * We cannot printk in early bootup code. Not even early_printk()
 430 * might work. So we mark any initialization errors and printk
 431 * about it later on, in lockdep_info().
 432 */
 433static int lockdep_init_error;
 434static const char *lock_init_error;
 435static unsigned long lockdep_init_trace_data[20];
 436static struct stack_trace lockdep_init_trace = {
 437        .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
 438        .entries = lockdep_init_trace_data,
 439};
 440
 441/*
 442 * Various lockdep statistics:
 443 */
 444DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
 445#endif
 446
 447/*
 448 * Locking printouts:
 449 */
 450
 451#define __USAGE(__STATE)                                                \
 452        [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
 453        [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
 454        [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
 455        [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
 456
 457static const char *usage_str[] =
 458{
 459#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
 460#include "lockdep_states.h"
 461#undef LOCKDEP_STATE
 462        [LOCK_USED] = "INITIAL USE",
 463};
 464
 465const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
 466{
 467        return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
 468}
 469
 470static inline unsigned long lock_flag(enum lock_usage_bit bit)
 471{
 472        return 1UL << bit;
 473}
 474
 475static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
 476{
 477        char c = '.';
 478
 479        if (class->usage_mask & lock_flag(bit + 2))
 480                c = '+';
 481        if (class->usage_mask & lock_flag(bit)) {
 482                c = '-';
 483                if (class->usage_mask & lock_flag(bit + 2))
 484                        c = '?';
 485        }
 486
 487        return c;
 488}
 489
 490void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
 491{
 492        int i = 0;
 493
 494#define LOCKDEP_STATE(__STATE)                                          \
 495        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
 496        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
 497#include "lockdep_states.h"
 498#undef LOCKDEP_STATE
 499
 500        usage[i] = '\0';
 501}
 502
 503static void __print_lock_name(struct lock_class *class)
 504{
 505        char str[KSYM_NAME_LEN];
 506        const char *name;
 507
 508        name = class->name;
 509        if (!name) {
 510                name = __get_key_name(class->key, str);
 511                printk("%s", name);
 512        } else {
 513                printk("%s", name);
 514                if (class->name_version > 1)
 515                        printk("#%d", class->name_version);
 516                if (class->subclass)
 517                        printk("/%d", class->subclass);
 518        }
 519}
 520
 521static void print_lock_name(struct lock_class *class)
 522{
 523        char usage[LOCK_USAGE_CHARS];
 524
 525        get_usage_chars(class, usage);
 526
 527        printk(" (");
 528        __print_lock_name(class);
 529        printk("){%s}", usage);
 530}
 531
 532static void print_lockdep_cache(struct lockdep_map *lock)
 533{
 534        const char *name;
 535        char str[KSYM_NAME_LEN];
 536
 537        name = lock->name;
 538        if (!name)
 539                name = __get_key_name(lock->key->subkeys, str);
 540
 541        printk("%s", name);
 542}
 543
 544static void print_lock(struct held_lock *hlock)
 545{
 546        print_lock_name(hlock_class(hlock));
 547        printk(", at: ");
 548        print_ip_sym(hlock->acquire_ip);
 549}
 550
 551static void lockdep_print_held_locks(struct task_struct *curr)
 552{
 553        int i, depth = curr->lockdep_depth;
 554
 555        if (!depth) {
 556                printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
 557                return;
 558        }
 559        printk("%d lock%s held by %s/%d:\n",
 560                depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
 561
 562        for (i = 0; i < depth; i++) {
 563                printk(" #%d: ", i);
 564                print_lock(curr->held_locks + i);
 565        }
 566}
 567
 568static void print_kernel_ident(void)
 569{
 570        printk("%s %.*s %s\n", init_utsname()->release,
 571                (int)strcspn(init_utsname()->version, " "),
 572                init_utsname()->version,
 573                print_tainted());
 574}
 575
 576static int very_verbose(struct lock_class *class)
 577{
 578#if VERY_VERBOSE
 579        return class_filter(class);
 580#endif
 581        return 0;
 582}
 583
 584/*
 585 * Is this the address of a static object:
 586 */
 587static int static_obj(void *obj)
 588{
 589        unsigned long start = (unsigned long) &_stext,
 590                      end   = (unsigned long) &_end,
 591                      addr  = (unsigned long) obj;
 592
 593        /*
 594         * static variable?
 595         */
 596        if ((addr >= start) && (addr < end))
 597                return 1;
 598
 599        if (arch_is_kernel_data(addr))
 600                return 1;
 601
 602        /*
 603         * in-kernel percpu var?
 604         */
 605        if (is_kernel_percpu_address(addr))
 606                return 1;
 607
 608        /*
 609         * module static or percpu var?
 610         */
 611        return is_module_address(addr) || is_module_percpu_address(addr);
 612}
 613
 614/*
 615 * To make lock name printouts unique, we calculate a unique
 616 * class->name_version generation counter:
 617 */
 618static int count_matching_names(struct lock_class *new_class)
 619{
 620        struct lock_class *class;
 621        int count = 0;
 622
 623        if (!new_class->name)
 624                return 0;
 625
 626        list_for_each_entry(class, &all_lock_classes, lock_entry) {
 627                if (new_class->key - new_class->subclass == class->key)
 628                        return class->name_version;
 629                if (class->name && !strcmp(class->name, new_class->name))
 630                        count = max(count, class->name_version);
 631        }
 632
 633        return count + 1;
 634}
 635
 636/*
 637 * Register a lock's class in the hash-table, if the class is not present
 638 * yet. Otherwise we look it up. We cache the result in the lock object
 639 * itself, so actual lookup of the hash should be once per lock object.
 640 */
 641static inline struct lock_class *
 642look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
 643{
 644        struct lockdep_subclass_key *key;
 645        struct list_head *hash_head;
 646        struct lock_class *class;
 647
 648#ifdef CONFIG_DEBUG_LOCKDEP
 649        /*
 650         * If the architecture calls into lockdep before initializing
 651         * the hashes then we'll warn about it later. (we cannot printk
 652         * right now)
 653         */
 654        if (unlikely(!lockdep_initialized)) {
 655                lockdep_init();
 656                lockdep_init_error = 1;
 657                lock_init_error = lock->name;
 658                save_stack_trace(&lockdep_init_trace);
 659        }
 660#endif
 661
 662        if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
 663                debug_locks_off();
 664                printk(KERN_ERR
 665                        "BUG: looking up invalid subclass: %u\n", subclass);
 666                printk(KERN_ERR
 667                        "turning off the locking correctness validator.\n");
 668                dump_stack();
 669                return NULL;
 670        }
 671
 672        /*
 673         * Static locks do not have their class-keys yet - for them the key
 674         * is the lock object itself:
 675         */
 676        if (unlikely(!lock->key))
 677                lock->key = (void *)lock;
 678
 679        /*
 680         * NOTE: the class-key must be unique. For dynamic locks, a static
 681         * lock_class_key variable is passed in through the mutex_init()
 682         * (or spin_lock_init()) call - which acts as the key. For static
 683         * locks we use the lock object itself as the key.
 684         */
 685        BUILD_BUG_ON(sizeof(struct lock_class_key) >
 686                        sizeof(struct lockdep_map));
 687
 688        key = lock->key->subkeys + subclass;
 689
 690        hash_head = classhashentry(key);
 691
 692        /*
 693         * We can walk the hash lockfree, because the hash only
 694         * grows, and we are careful when adding entries to the end:
 695         */
 696        list_for_each_entry(class, hash_head, hash_entry) {
 697                if (class->key == key) {
 698                        /*
 699                         * Huh! same key, different name? Did someone trample
 700                         * on some memory? We're most confused.
 701                         */
 702                        WARN_ON_ONCE(class->name != lock->name);
 703                        return class;
 704                }
 705        }
 706
 707        return NULL;
 708}
 709
 710/*
 711 * Register a lock's class in the hash-table, if the class is not present
 712 * yet. Otherwise we look it up. We cache the result in the lock object
 713 * itself, so actual lookup of the hash should be once per lock object.
 714 */
 715static inline struct lock_class *
 716register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 717{
 718        struct lockdep_subclass_key *key;
 719        struct list_head *hash_head;
 720        struct lock_class *class;
 721        unsigned long flags;
 722
 723        class = look_up_lock_class(lock, subclass);
 724        if (likely(class))
 725                goto out_set_class_cache;
 726
 727        /*
 728         * Debug-check: all keys must be persistent!
 729         */
 730        if (!static_obj(lock->key)) {
 731                debug_locks_off();
 732                printk("INFO: trying to register non-static key.\n");
 733                printk("the code is fine but needs lockdep annotation.\n");
 734                printk("turning off the locking correctness validator.\n");
 735                dump_stack();
 736
 737                return NULL;
 738        }
 739
 740        key = lock->key->subkeys + subclass;
 741        hash_head = classhashentry(key);
 742
 743        raw_local_irq_save(flags);
 744        if (!graph_lock()) {
 745                raw_local_irq_restore(flags);
 746                return NULL;
 747        }
 748        /*
 749         * We have to do the hash-walk again, to avoid races
 750         * with another CPU:
 751         */
 752        list_for_each_entry(class, hash_head, hash_entry)
 753                if (class->key == key)
 754                        goto out_unlock_set;
 755        /*
 756         * Allocate a new key from the static array, and add it to
 757         * the hash:
 758         */
 759        if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
 760                if (!debug_locks_off_graph_unlock()) {
 761                        raw_local_irq_restore(flags);
 762                        return NULL;
 763                }
 764                raw_local_irq_restore(flags);
 765
 766                printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
 767                printk("turning off the locking correctness validator.\n");
 768                dump_stack();
 769                return NULL;
 770        }
 771        class = lock_classes + nr_lock_classes++;
 772        debug_atomic_inc(nr_unused_locks);
 773        class->key = key;
 774        class->name = lock->name;
 775        class->subclass = subclass;
 776        INIT_LIST_HEAD(&class->lock_entry);
 777        INIT_LIST_HEAD(&class->locks_before);
 778        INIT_LIST_HEAD(&class->locks_after);
 779        class->name_version = count_matching_names(class);
 780        /*
 781         * We use RCU's safe list-add method to make
 782         * parallel walking of the hash-list safe:
 783         */
 784        list_add_tail_rcu(&class->hash_entry, hash_head);
 785        /*
 786         * Add it to the global list of classes:
 787         */
 788        list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
 789
 790        if (verbose(class)) {
 791                graph_unlock();
 792                raw_local_irq_restore(flags);
 793
 794                printk("\nnew class %p: %s", class->key, class->name);
 795                if (class->name_version > 1)
 796                        printk("#%d", class->name_version);
 797                printk("\n");
 798                dump_stack();
 799
 800                raw_local_irq_save(flags);
 801                if (!graph_lock()) {
 802                        raw_local_irq_restore(flags);
 803                        return NULL;
 804                }
 805        }
 806out_unlock_set:
 807        graph_unlock();
 808        raw_local_irq_restore(flags);
 809
 810out_set_class_cache:
 811        if (!subclass || force)
 812                lock->class_cache[0] = class;
 813        else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
 814                lock->class_cache[subclass] = class;
 815
 816        /*
 817         * Hash collision, did we smoke some? We found a class with a matching
 818         * hash but the subclass -- which is hashed in -- didn't match.
 819         */
 820        if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
 821                return NULL;
 822
 823        return class;
 824}
 825
 826#ifdef CONFIG_PROVE_LOCKING
 827/*
 828 * Allocate a lockdep entry. (assumes the graph_lock held, returns
 829 * with NULL on failure)
 830 */
 831static struct lock_list *alloc_list_entry(void)
 832{
 833        if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
 834                if (!debug_locks_off_graph_unlock())
 835                        return NULL;
 836
 837                printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
 838                printk("turning off the locking correctness validator.\n");
 839                dump_stack();
 840                return NULL;
 841        }
 842        return list_entries + nr_list_entries++;
 843}
 844
 845/*
 846 * Add a new dependency to the head of the list:
 847 */
 848static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
 849                            struct list_head *head, unsigned long ip,
 850                            int distance, struct stack_trace *trace)
 851{
 852        struct lock_list *entry;
 853        /*
 854         * Lock not present yet - get a new dependency struct and
 855         * add it to the list:
 856         */
 857        entry = alloc_list_entry();
 858        if (!entry)
 859                return 0;
 860
 861        entry->class = this;
 862        entry->distance = distance;
 863        entry->trace = *trace;
 864        /*
 865         * Since we never remove from the dependency list, the list can
 866         * be walked lockless by other CPUs, it's only allocation
 867         * that must be protected by the spinlock. But this also means
 868         * we must make new entries visible only once writes to the
 869         * entry become visible - hence the RCU op:
 870         */
 871        list_add_tail_rcu(&entry->entry, head);
 872
 873        return 1;
 874}
 875
 876/*
 877 * For good efficiency of modular, we use power of 2
 878 */
 879#define MAX_CIRCULAR_QUEUE_SIZE         4096UL
 880#define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
 881
 882/*
 883 * The circular_queue and helpers is used to implement the
 884 * breadth-first search(BFS)algorithem, by which we can build
 885 * the shortest path from the next lock to be acquired to the
 886 * previous held lock if there is a circular between them.
 887 */
 888struct circular_queue {
 889        unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
 890        unsigned int  front, rear;
 891};
 892
 893static struct circular_queue lock_cq;
 894
 895unsigned int max_bfs_queue_depth;
 896
 897static unsigned int lockdep_dependency_gen_id;
 898
 899static inline void __cq_init(struct circular_queue *cq)
 900{
 901        cq->front = cq->rear = 0;
 902        lockdep_dependency_gen_id++;
 903}
 904
 905static inline int __cq_empty(struct circular_queue *cq)
 906{
 907        return (cq->front == cq->rear);
 908}
 909
 910static inline int __cq_full(struct circular_queue *cq)
 911{
 912        return ((cq->rear + 1) & CQ_MASK) == cq->front;
 913}
 914
 915static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
 916{
 917        if (__cq_full(cq))
 918                return -1;
 919
 920        cq->element[cq->rear] = elem;
 921        cq->rear = (cq->rear + 1) & CQ_MASK;
 922        return 0;
 923}
 924
 925static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
 926{
 927        if (__cq_empty(cq))
 928                return -1;
 929
 930        *elem = cq->element[cq->front];
 931        cq->front = (cq->front + 1) & CQ_MASK;
 932        return 0;
 933}
 934
 935static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
 936{
 937        return (cq->rear - cq->front) & CQ_MASK;
 938}
 939
 940static inline void mark_lock_accessed(struct lock_list *lock,
 941                                        struct lock_list *parent)
 942{
 943        unsigned long nr;
 944
 945        nr = lock - list_entries;
 946        WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
 947        lock->parent = parent;
 948        lock->class->dep_gen_id = lockdep_dependency_gen_id;
 949}
 950
 951static inline unsigned long lock_accessed(struct lock_list *lock)
 952{
 953        unsigned long nr;
 954
 955        nr = lock - list_entries;
 956        WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
 957        return lock->class->dep_gen_id == lockdep_dependency_gen_id;
 958}
 959
 960static inline struct lock_list *get_lock_parent(struct lock_list *child)
 961{
 962        return child->parent;
 963}
 964
 965static inline int get_lock_depth(struct lock_list *child)
 966{
 967        int depth = 0;
 968        struct lock_list *parent;
 969
 970        while ((parent = get_lock_parent(child))) {
 971                child = parent;
 972                depth++;
 973        }
 974        return depth;
 975}
 976
 977static int __bfs(struct lock_list *source_entry,
 978                 void *data,
 979                 int (*match)(struct lock_list *entry, void *data),
 980                 struct lock_list **target_entry,
 981                 int forward)
 982{
 983        struct lock_list *entry;
 984        struct list_head *head;
 985        struct circular_queue *cq = &lock_cq;
 986        int ret = 1;
 987
 988        if (match(source_entry, data)) {
 989                *target_entry = source_entry;
 990                ret = 0;
 991                goto exit;
 992        }
 993
 994        if (forward)
 995                head = &source_entry->class->locks_after;
 996        else
 997                head = &source_entry->class->locks_before;
 998
 999        if (list_empty(head))
1000                goto exit;
1001
1002        __cq_init(cq);
1003        __cq_enqueue(cq, (unsigned long)source_entry);
1004
1005        while (!__cq_empty(cq)) {
1006                struct lock_list *lock;
1007
1008                __cq_dequeue(cq, (unsigned long *)&lock);
1009
1010                if (!lock->class) {
1011                        ret = -2;
1012                        goto exit;
1013                }
1014
1015                if (forward)
1016                        head = &lock->class->locks_after;
1017                else
1018                        head = &lock->class->locks_before;
1019
1020                list_for_each_entry(entry, head, entry) {
1021                        if (!lock_accessed(entry)) {
1022                                unsigned int cq_depth;
1023                                mark_lock_accessed(entry, lock);
1024                                if (match(entry, data)) {
1025                                        *target_entry = entry;
1026                                        ret = 0;
1027                                        goto exit;
1028                                }
1029
1030                                if (__cq_enqueue(cq, (unsigned long)entry)) {
1031                                        ret = -1;
1032                                        goto exit;
1033                                }
1034                                cq_depth = __cq_get_elem_count(cq);
1035                                if (max_bfs_queue_depth < cq_depth)
1036                                        max_bfs_queue_depth = cq_depth;
1037                        }
1038                }
1039        }
1040exit:
1041        return ret;
1042}
1043
1044static inline int __bfs_forwards(struct lock_list *src_entry,
1045                        void *data,
1046                        int (*match)(struct lock_list *entry, void *data),
1047                        struct lock_list **target_entry)
1048{
1049        return __bfs(src_entry, data, match, target_entry, 1);
1050
1051}
1052
1053static inline int __bfs_backwards(struct lock_list *src_entry,
1054                        void *data,
1055                        int (*match)(struct lock_list *entry, void *data),
1056                        struct lock_list **target_entry)
1057{
1058        return __bfs(src_entry, data, match, target_entry, 0);
1059
1060}
1061
1062/*
1063 * Recursive, forwards-direction lock-dependency checking, used for
1064 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1065 * checking.
1066 */
1067
1068/*
1069 * Print a dependency chain entry (this is only done when a deadlock
1070 * has been detected):
1071 */
1072static noinline int
1073print_circular_bug_entry(struct lock_list *target, int depth)
1074{
1075        if (debug_locks_silent)
1076                return 0;
1077        printk("\n-> #%u", depth);
1078        print_lock_name(target->class);
1079        printk(":\n");
1080        print_stack_trace(&target->trace, 6);
1081
1082        return 0;
1083}
1084
1085static void
1086print_circular_lock_scenario(struct held_lock *src,
1087                             struct held_lock *tgt,
1088                             struct lock_list *prt)
1089{
1090        struct lock_class *source = hlock_class(src);
1091        struct lock_class *target = hlock_class(tgt);
1092        struct lock_class *parent = prt->class;
1093
1094        /*
1095         * A direct locking problem where unsafe_class lock is taken
1096         * directly by safe_class lock, then all we need to show
1097         * is the deadlock scenario, as it is obvious that the
1098         * unsafe lock is taken under the safe lock.
1099         *
1100         * But if there is a chain instead, where the safe lock takes
1101         * an intermediate lock (middle_class) where this lock is
1102         * not the same as the safe lock, then the lock chain is
1103         * used to describe the problem. Otherwise we would need
1104         * to show a different CPU case for each link in the chain
1105         * from the safe_class lock to the unsafe_class lock.
1106         */
1107        if (parent != source) {
1108                printk("Chain exists of:\n  ");
1109                __print_lock_name(source);
1110                printk(" --> ");
1111                __print_lock_name(parent);
1112                printk(" --> ");
1113                __print_lock_name(target);
1114                printk("\n\n");
1115        }
1116
1117        printk(" Possible unsafe locking scenario:\n\n");
1118        printk("       CPU0                    CPU1\n");
1119        printk("       ----                    ----\n");
1120        printk("  lock(");
1121        __print_lock_name(target);
1122        printk(");\n");
1123        printk("                               lock(");
1124        __print_lock_name(parent);
1125        printk(");\n");
1126        printk("                               lock(");
1127        __print_lock_name(target);
1128        printk(");\n");
1129        printk("  lock(");
1130        __print_lock_name(source);
1131        printk(");\n");
1132        printk("\n *** DEADLOCK ***\n\n");
1133}
1134
1135/*
1136 * When a circular dependency is detected, print the
1137 * header first:
1138 */
1139static noinline int
1140print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1141                        struct held_lock *check_src,
1142                        struct held_lock *check_tgt)
1143{
1144        struct task_struct *curr = current;
1145
1146        if (debug_locks_silent)
1147                return 0;
1148
1149        printk("\n");
1150        printk("======================================================\n");
1151        printk("[ INFO: possible circular locking dependency detected ]\n");
1152        print_kernel_ident();
1153        printk("-------------------------------------------------------\n");
1154        printk("%s/%d is trying to acquire lock:\n",
1155                curr->comm, task_pid_nr(curr));
1156        print_lock(check_src);
1157        printk("\nbut task is already holding lock:\n");
1158        print_lock(check_tgt);
1159        printk("\nwhich lock already depends on the new lock.\n\n");
1160        printk("\nthe existing dependency chain (in reverse order) is:\n");
1161
1162        print_circular_bug_entry(entry, depth);
1163
1164        return 0;
1165}
1166
1167static inline int class_equal(struct lock_list *entry, void *data)
1168{
1169        return entry->class == data;
1170}
1171
1172static noinline int print_circular_bug(struct lock_list *this,
1173                                struct lock_list *target,
1174                                struct held_lock *check_src,
1175                                struct held_lock *check_tgt)
1176{
1177        struct task_struct *curr = current;
1178        struct lock_list *parent;
1179        struct lock_list *first_parent;
1180        int depth;
1181
1182        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1183                return 0;
1184
1185        if (!save_trace(&this->trace))
1186                return 0;
1187
1188        depth = get_lock_depth(target);
1189
1190        print_circular_bug_header(target, depth, check_src, check_tgt);
1191
1192        parent = get_lock_parent(target);
1193        first_parent = parent;
1194
1195        while (parent) {
1196                print_circular_bug_entry(parent, --depth);
1197                parent = get_lock_parent(parent);
1198        }
1199
1200        printk("\nother info that might help us debug this:\n\n");
1201        print_circular_lock_scenario(check_src, check_tgt,
1202                                     first_parent);
1203
1204        lockdep_print_held_locks(curr);
1205
1206        printk("\nstack backtrace:\n");
1207        dump_stack();
1208
1209        return 0;
1210}
1211
1212static noinline int print_bfs_bug(int ret)
1213{
1214        if (!debug_locks_off_graph_unlock())
1215                return 0;
1216
1217        /*
1218         * Breadth-first-search failed, graph got corrupted?
1219         */
1220        WARN(1, "lockdep bfs error:%d\n", ret);
1221
1222        return 0;
1223}
1224
1225static int noop_count(struct lock_list *entry, void *data)
1226{
1227        (*(unsigned long *)data)++;
1228        return 0;
1229}
1230
1231unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1232{
1233        unsigned long  count = 0;
1234        struct lock_list *uninitialized_var(target_entry);
1235
1236        __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1237
1238        return count;
1239}
1240unsigned long lockdep_count_forward_deps(struct lock_class *class)
1241{
1242        unsigned long ret, flags;
1243        struct lock_list this;
1244
1245        this.parent = NULL;
1246        this.class = class;
1247
1248        local_irq_save(flags);
1249        arch_spin_lock(&lockdep_lock);
1250        ret = __lockdep_count_forward_deps(&this);
1251        arch_spin_unlock(&lockdep_lock);
1252        local_irq_restore(flags);
1253
1254        return ret;
1255}
1256
1257unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1258{
1259        unsigned long  count = 0;
1260        struct lock_list *uninitialized_var(target_entry);
1261
1262        __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1263
1264        return count;
1265}
1266
1267unsigned long lockdep_count_backward_deps(struct lock_class *class)
1268{
1269        unsigned long ret, flags;
1270        struct lock_list this;
1271
1272        this.parent = NULL;
1273        this.class = class;
1274
1275        local_irq_save(flags);
1276        arch_spin_lock(&lockdep_lock);
1277        ret = __lockdep_count_backward_deps(&this);
1278        arch_spin_unlock(&lockdep_lock);
1279        local_irq_restore(flags);
1280
1281        return ret;
1282}
1283
1284/*
1285 * Prove that the dependency graph starting at <entry> can not
1286 * lead to <target>. Print an error and return 0 if it does.
1287 */
1288static noinline int
1289check_noncircular(struct lock_list *root, struct lock_class *target,
1290                struct lock_list **target_entry)
1291{
1292        int result;
1293
1294        debug_atomic_inc(nr_cyclic_checks);
1295
1296        result = __bfs_forwards(root, target, class_equal, target_entry);
1297
1298        return result;
1299}
1300
1301#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1302/*
1303 * Forwards and backwards subgraph searching, for the purposes of
1304 * proving that two subgraphs can be connected by a new dependency
1305 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1306 */
1307
1308static inline int usage_match(struct lock_list *entry, void *bit)
1309{
1310        return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1311}
1312
1313
1314
1315/*
1316 * Find a node in the forwards-direction dependency sub-graph starting
1317 * at @root->class that matches @bit.
1318 *
1319 * Return 0 if such a node exists in the subgraph, and put that node
1320 * into *@target_entry.
1321 *
1322 * Return 1 otherwise and keep *@target_entry unchanged.
1323 * Return <0 on error.
1324 */
1325static int
1326find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1327                        struct lock_list **target_entry)
1328{
1329        int result;
1330
1331        debug_atomic_inc(nr_find_usage_forwards_checks);
1332
1333        result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1334
1335        return result;
1336}
1337
1338/*
1339 * Find a node in the backwards-direction dependency sub-graph starting
1340 * at @root->class that matches @bit.
1341 *
1342 * Return 0 if such a node exists in the subgraph, and put that node
1343 * into *@target_entry.
1344 *
1345 * Return 1 otherwise and keep *@target_entry unchanged.
1346 * Return <0 on error.
1347 */
1348static int
1349find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1350                        struct lock_list **target_entry)
1351{
1352        int result;
1353
1354        debug_atomic_inc(nr_find_usage_backwards_checks);
1355
1356        result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1357
1358        return result;
1359}
1360
1361static void print_lock_class_header(struct lock_class *class, int depth)
1362{
1363        int bit;
1364
1365        printk("%*s->", depth, "");
1366        print_lock_name(class);
1367        printk(" ops: %lu", class->ops);
1368        printk(" {\n");
1369
1370        for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1371                if (class->usage_mask & (1 << bit)) {
1372                        int len = depth;
1373
1374                        len += printk("%*s   %s", depth, "", usage_str[bit]);
1375                        len += printk(" at:\n");
1376                        print_stack_trace(class->usage_traces + bit, len);
1377                }
1378        }
1379        printk("%*s }\n", depth, "");
1380
1381        printk("%*s ... key      at: ",depth,"");
1382        print_ip_sym((unsigned long)class->key);
1383}
1384
1385/*
1386 * printk the shortest lock dependencies from @start to @end in reverse order:
1387 */
1388static void __used
1389print_shortest_lock_dependencies(struct lock_list *leaf,
1390                                struct lock_list *root)
1391{
1392        struct lock_list *entry = leaf;
1393        int depth;
1394
1395        /*compute depth from generated tree by BFS*/
1396        depth = get_lock_depth(leaf);
1397
1398        do {
1399                print_lock_class_header(entry->class, depth);
1400                printk("%*s ... acquired at:\n", depth, "");
1401                print_stack_trace(&entry->trace, 2);
1402                printk("\n");
1403
1404                if (depth == 0 && (entry != root)) {
1405                        printk("lockdep:%s bad path found in chain graph\n", __func__);
1406                        break;
1407                }
1408
1409                entry = get_lock_parent(entry);
1410                depth--;
1411        } while (entry && (depth >= 0));
1412
1413        return;
1414}
1415
1416static void
1417print_irq_lock_scenario(struct lock_list *safe_entry,
1418                        struct lock_list *unsafe_entry,
1419                        struct lock_class *prev_class,
1420                        struct lock_class *next_class)
1421{
1422        struct lock_class *safe_class = safe_entry->class;
1423        struct lock_class *unsafe_class = unsafe_entry->class;
1424        struct lock_class *middle_class = prev_class;
1425
1426        if (middle_class == safe_class)
1427                middle_class = next_class;
1428
1429        /*
1430         * A direct locking problem where unsafe_class lock is taken
1431         * directly by safe_class lock, then all we need to show
1432         * is the deadlock scenario, as it is obvious that the
1433         * unsafe lock is taken under the safe lock.
1434         *
1435         * But if there is a chain instead, where the safe lock takes
1436         * an intermediate lock (middle_class) where this lock is
1437         * not the same as the safe lock, then the lock chain is
1438         * used to describe the problem. Otherwise we would need
1439         * to show a different CPU case for each link in the chain
1440         * from the safe_class lock to the unsafe_class lock.
1441         */
1442        if (middle_class != unsafe_class) {
1443                printk("Chain exists of:\n  ");
1444                __print_lock_name(safe_class);
1445                printk(" --> ");
1446                __print_lock_name(middle_class);
1447                printk(" --> ");
1448                __print_lock_name(unsafe_class);
1449                printk("\n\n");
1450        }
1451
1452        printk(" Possible interrupt unsafe locking scenario:\n\n");
1453        printk("       CPU0                    CPU1\n");
1454        printk("       ----                    ----\n");
1455        printk("  lock(");
1456        __print_lock_name(unsafe_class);
1457        printk(");\n");
1458        printk("                               local_irq_disable();\n");
1459        printk("                               lock(");
1460        __print_lock_name(safe_class);
1461        printk(");\n");
1462        printk("                               lock(");
1463        __print_lock_name(middle_class);
1464        printk(");\n");
1465        printk("  <Interrupt>\n");
1466        printk("    lock(");
1467        __print_lock_name(safe_class);
1468        printk(");\n");
1469        printk("\n *** DEADLOCK ***\n\n");
1470}
1471
1472static int
1473print_bad_irq_dependency(struct task_struct *curr,
1474                         struct lock_list *prev_root,
1475                         struct lock_list *next_root,
1476                         struct lock_list *backwards_entry,
1477                         struct lock_list *forwards_entry,
1478                         struct held_lock *prev,
1479                         struct held_lock *next,
1480                         enum lock_usage_bit bit1,
1481                         enum lock_usage_bit bit2,
1482                         const char *irqclass)
1483{
1484        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1485                return 0;
1486
1487        printk("\n");
1488        printk("======================================================\n");
1489        printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1490                irqclass, irqclass);
1491        print_kernel_ident();
1492        printk("------------------------------------------------------\n");
1493        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1494                curr->comm, task_pid_nr(curr),
1495                curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1496                curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1497                curr->hardirqs_enabled,
1498                curr->softirqs_enabled);
1499        print_lock(next);
1500
1501        printk("\nand this task is already holding:\n");
1502        print_lock(prev);
1503        printk("which would create a new lock dependency:\n");
1504        print_lock_name(hlock_class(prev));
1505        printk(" ->");
1506        print_lock_name(hlock_class(next));
1507        printk("\n");
1508
1509        printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1510                irqclass);
1511        print_lock_name(backwards_entry->class);
1512        printk("\n... which became %s-irq-safe at:\n", irqclass);
1513
1514        print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1515
1516        printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1517        print_lock_name(forwards_entry->class);
1518        printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1519        printk("...");
1520
1521        print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1522
1523        printk("\nother info that might help us debug this:\n\n");
1524        print_irq_lock_scenario(backwards_entry, forwards_entry,
1525                                hlock_class(prev), hlock_class(next));
1526
1527        lockdep_print_held_locks(curr);
1528
1529        printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1530        printk(" and the holding lock:\n");
1531        if (!save_trace(&prev_root->trace))
1532                return 0;
1533        print_shortest_lock_dependencies(backwards_entry, prev_root);
1534
1535        printk("\nthe dependencies between the lock to be acquired");
1536        printk(" and %s-irq-unsafe lock:\n", irqclass);
1537        if (!save_trace(&next_root->trace))
1538                return 0;
1539        print_shortest_lock_dependencies(forwards_entry, next_root);
1540
1541        printk("\nstack backtrace:\n");
1542        dump_stack();
1543
1544        return 0;
1545}
1546
1547static int
1548check_usage(struct task_struct *curr, struct held_lock *prev,
1549            struct held_lock *next, enum lock_usage_bit bit_backwards,
1550            enum lock_usage_bit bit_forwards, const char *irqclass)
1551{
1552        int ret;
1553        struct lock_list this, that;
1554        struct lock_list *uninitialized_var(target_entry);
1555        struct lock_list *uninitialized_var(target_entry1);
1556
1557        this.parent = NULL;
1558
1559        this.class = hlock_class(prev);
1560        ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1561        if (ret < 0)
1562                return print_bfs_bug(ret);
1563        if (ret == 1)
1564                return ret;
1565
1566        that.parent = NULL;
1567        that.class = hlock_class(next);
1568        ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1569        if (ret < 0)
1570                return print_bfs_bug(ret);
1571        if (ret == 1)
1572                return ret;
1573
1574        return print_bad_irq_dependency(curr, &this, &that,
1575                        target_entry, target_entry1,
1576                        prev, next,
1577                        bit_backwards, bit_forwards, irqclass);
1578}
1579
1580static const char *state_names[] = {
1581#define LOCKDEP_STATE(__STATE) \
1582        __stringify(__STATE),
1583#include "lockdep_states.h"
1584#undef LOCKDEP_STATE
1585};
1586
1587static const char *state_rnames[] = {
1588#define LOCKDEP_STATE(__STATE) \
1589        __stringify(__STATE)"-READ",
1590#include "lockdep_states.h"
1591#undef LOCKDEP_STATE
1592};
1593
1594static inline const char *state_name(enum lock_usage_bit bit)
1595{
1596        return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1597}
1598
1599static int exclusive_bit(int new_bit)
1600{
1601        /*
1602         * USED_IN
1603         * USED_IN_READ
1604         * ENABLED
1605         * ENABLED_READ
1606         *
1607         * bit 0 - write/read
1608         * bit 1 - used_in/enabled
1609         * bit 2+  state
1610         */
1611
1612        int state = new_bit & ~3;
1613        int dir = new_bit & 2;
1614
1615        /*
1616         * keep state, bit flip the direction and strip read.
1617         */
1618        return state | (dir ^ 2);
1619}
1620
1621static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1622                           struct held_lock *next, enum lock_usage_bit bit)
1623{
1624        /*
1625         * Prove that the new dependency does not connect a hardirq-safe
1626         * lock with a hardirq-unsafe lock - to achieve this we search
1627         * the backwards-subgraph starting at <prev>, and the
1628         * forwards-subgraph starting at <next>:
1629         */
1630        if (!check_usage(curr, prev, next, bit,
1631                           exclusive_bit(bit), state_name(bit)))
1632                return 0;
1633
1634        bit++; /* _READ */
1635
1636        /*
1637         * Prove that the new dependency does not connect a hardirq-safe-read
1638         * lock with a hardirq-unsafe lock - to achieve this we search
1639         * the backwards-subgraph starting at <prev>, and the
1640         * forwards-subgraph starting at <next>:
1641         */
1642        if (!check_usage(curr, prev, next, bit,
1643                           exclusive_bit(bit), state_name(bit)))
1644                return 0;
1645
1646        return 1;
1647}
1648
1649static int
1650check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1651                struct held_lock *next)
1652{
1653#define LOCKDEP_STATE(__STATE)                                          \
1654        if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1655                return 0;
1656#include "lockdep_states.h"
1657#undef LOCKDEP_STATE
1658
1659        return 1;
1660}
1661
1662static void inc_chains(void)
1663{
1664        if (current->hardirq_context)
1665                nr_hardirq_chains++;
1666        else {
1667                if (current->softirq_context)
1668                        nr_softirq_chains++;
1669                else
1670                        nr_process_chains++;
1671        }
1672}
1673
1674#else
1675
1676static inline int
1677check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1678                struct held_lock *next)
1679{
1680        return 1;
1681}
1682
1683static inline void inc_chains(void)
1684{
1685        nr_process_chains++;
1686}
1687
1688#endif
1689
1690static void
1691print_deadlock_scenario(struct held_lock *nxt,
1692                             struct held_lock *prv)
1693{
1694        struct lock_class *next = hlock_class(nxt);
1695        struct lock_class *prev = hlock_class(prv);
1696
1697        printk(" Possible unsafe locking scenario:\n\n");
1698        printk("       CPU0\n");
1699        printk("       ----\n");
1700        printk("  lock(");
1701        __print_lock_name(prev);
1702        printk(");\n");
1703        printk("  lock(");
1704        __print_lock_name(next);
1705        printk(");\n");
1706        printk("\n *** DEADLOCK ***\n\n");
1707        printk(" May be due to missing lock nesting notation\n\n");
1708}
1709
1710static int
1711print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1712                   struct held_lock *next)
1713{
1714        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1715                return 0;
1716
1717        printk("\n");
1718        printk("=============================================\n");
1719        printk("[ INFO: possible recursive locking detected ]\n");
1720        print_kernel_ident();
1721        printk("---------------------------------------------\n");
1722        printk("%s/%d is trying to acquire lock:\n",
1723                curr->comm, task_pid_nr(curr));
1724        print_lock(next);
1725        printk("\nbut task is already holding lock:\n");
1726        print_lock(prev);
1727
1728        printk("\nother info that might help us debug this:\n");
1729        print_deadlock_scenario(next, prev);
1730        lockdep_print_held_locks(curr);
1731
1732        printk("\nstack backtrace:\n");
1733        dump_stack();
1734
1735        return 0;
1736}
1737
1738/*
1739 * Check whether we are holding such a class already.
1740 *
1741 * (Note that this has to be done separately, because the graph cannot
1742 * detect such classes of deadlocks.)
1743 *
1744 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1745 */
1746static int
1747check_deadlock(struct task_struct *curr, struct held_lock *next,
1748               struct lockdep_map *next_instance, int read)
1749{
1750        struct held_lock *prev;
1751        struct held_lock *nest = NULL;
1752        int i;
1753
1754        for (i = 0; i < curr->lockdep_depth; i++) {
1755                prev = curr->held_locks + i;
1756
1757                if (prev->instance == next->nest_lock)
1758                        nest = prev;
1759
1760                if (hlock_class(prev) != hlock_class(next))
1761                        continue;
1762
1763                /*
1764                 * Allow read-after-read recursion of the same
1765                 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1766                 */
1767                if ((read == 2) && prev->read)
1768                        return 2;
1769
1770                /*
1771                 * We're holding the nest_lock, which serializes this lock's
1772                 * nesting behaviour.
1773                 */
1774                if (nest)
1775                        return 2;
1776
1777                return print_deadlock_bug(curr, prev, next);
1778        }
1779        return 1;
1780}
1781
1782/*
1783 * There was a chain-cache miss, and we are about to add a new dependency
1784 * to a previous lock. We recursively validate the following rules:
1785 *
1786 *  - would the adding of the <prev> -> <next> dependency create a
1787 *    circular dependency in the graph? [== circular deadlock]
1788 *
1789 *  - does the new prev->next dependency connect any hardirq-safe lock
1790 *    (in the full backwards-subgraph starting at <prev>) with any
1791 *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1792 *    <next>)? [== illegal lock inversion with hardirq contexts]
1793 *
1794 *  - does the new prev->next dependency connect any softirq-safe lock
1795 *    (in the full backwards-subgraph starting at <prev>) with any
1796 *    softirq-unsafe lock (in the full forwards-subgraph starting at
1797 *    <next>)? [== illegal lock inversion with softirq contexts]
1798 *
1799 * any of these scenarios could lead to a deadlock.
1800 *
1801 * Then if all the validations pass, we add the forwards and backwards
1802 * dependency.
1803 */
1804static int
1805check_prev_add(struct task_struct *curr, struct held_lock *prev,
1806               struct held_lock *next, int distance, int trylock_loop)
1807{
1808        struct lock_list *entry;
1809        int ret;
1810        struct lock_list this;
1811        struct lock_list *uninitialized_var(target_entry);
1812        /*
1813         * Static variable, serialized by the graph_lock().
1814         *
1815         * We use this static variable to save the stack trace in case
1816         * we call into this function multiple times due to encountering
1817         * trylocks in the held lock stack.
1818         */
1819        static struct stack_trace trace;
1820
1821        /*
1822         * Prove that the new <prev> -> <next> dependency would not
1823         * create a circular dependency in the graph. (We do this by
1824         * forward-recursing into the graph starting at <next>, and
1825         * checking whether we can reach <prev>.)
1826         *
1827         * We are using global variables to control the recursion, to
1828         * keep the stackframe size of the recursive functions low:
1829         */
1830        this.class = hlock_class(next);
1831        this.parent = NULL;
1832        ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1833        if (unlikely(!ret))
1834                return print_circular_bug(&this, target_entry, next, prev);
1835        else if (unlikely(ret < 0))
1836                return print_bfs_bug(ret);
1837
1838        if (!check_prev_add_irq(curr, prev, next))
1839                return 0;
1840
1841        /*
1842         * For recursive read-locks we do all the dependency checks,
1843         * but we dont store read-triggered dependencies (only
1844         * write-triggered dependencies). This ensures that only the
1845         * write-side dependencies matter, and that if for example a
1846         * write-lock never takes any other locks, then the reads are
1847         * equivalent to a NOP.
1848         */
1849        if (next->read == 2 || prev->read == 2)
1850                return 1;
1851        /*
1852         * Is the <prev> -> <next> dependency already present?
1853         *
1854         * (this may occur even though this is a new chain: consider
1855         *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1856         *  chains - the second one will be new, but L1 already has
1857         *  L2 added to its dependency list, due to the first chain.)
1858         */
1859        list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1860                if (entry->class == hlock_class(next)) {
1861                        if (distance == 1)
1862                                entry->distance = 1;
1863                        return 2;
1864                }
1865        }
1866
1867        if (!trylock_loop && !save_trace(&trace))
1868                return 0;
1869
1870        /*
1871         * Ok, all validations passed, add the new lock
1872         * to the previous lock's dependency list:
1873         */
1874        ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1875                               &hlock_class(prev)->locks_after,
1876                               next->acquire_ip, distance, &trace);
1877
1878        if (!ret)
1879                return 0;
1880
1881        ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1882                               &hlock_class(next)->locks_before,
1883                               next->acquire_ip, distance, &trace);
1884        if (!ret)
1885                return 0;
1886
1887        /*
1888         * Debugging printouts:
1889         */
1890        if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1891                graph_unlock();
1892                printk("\n new dependency: ");
1893                print_lock_name(hlock_class(prev));
1894                printk(" => ");
1895                print_lock_name(hlock_class(next));
1896                printk("\n");
1897                dump_stack();
1898                return graph_lock();
1899        }
1900        return 1;
1901}
1902
1903/*
1904 * Add the dependency to all directly-previous locks that are 'relevant'.
1905 * The ones that are relevant are (in increasing distance from curr):
1906 * all consecutive trylock entries and the final non-trylock entry - or
1907 * the end of this context's lock-chain - whichever comes first.
1908 */
1909static int
1910check_prevs_add(struct task_struct *curr, struct held_lock *next)
1911{
1912        int depth = curr->lockdep_depth;
1913        int trylock_loop = 0;
1914        struct held_lock *hlock;
1915
1916        /*
1917         * Debugging checks.
1918         *
1919         * Depth must not be zero for a non-head lock:
1920         */
1921        if (!depth)
1922                goto out_bug;
1923        /*
1924         * At least two relevant locks must exist for this
1925         * to be a head:
1926         */
1927        if (curr->held_locks[depth].irq_context !=
1928                        curr->held_locks[depth-1].irq_context)
1929                goto out_bug;
1930
1931        for (;;) {
1932                int distance = curr->lockdep_depth - depth + 1;
1933                hlock = curr->held_locks + depth-1;
1934                /*
1935                 * Only non-recursive-read entries get new dependencies
1936                 * added:
1937                 */
1938                if (hlock->read != 2) {
1939                        if (!check_prev_add(curr, hlock, next,
1940                                                distance, trylock_loop))
1941                                return 0;
1942                        /*
1943                         * Stop after the first non-trylock entry,
1944                         * as non-trylock entries have added their
1945                         * own direct dependencies already, so this
1946                         * lock is connected to them indirectly:
1947                         */
1948                        if (!hlock->trylock)
1949                                break;
1950                }
1951                depth--;
1952                /*
1953                 * End of lock-stack?
1954                 */
1955                if (!depth)
1956                        break;
1957                /*
1958                 * Stop the search if we cross into another context:
1959                 */
1960                if (curr->held_locks[depth].irq_context !=
1961                                curr->held_locks[depth-1].irq_context)
1962                        break;
1963                trylock_loop = 1;
1964        }
1965        return 1;
1966out_bug:
1967        if (!debug_locks_off_graph_unlock())
1968                return 0;
1969
1970        /*
1971         * Clearly we all shouldn't be here, but since we made it we
1972         * can reliable say we messed up our state. See the above two
1973         * gotos for reasons why we could possibly end up here.
1974         */
1975        WARN_ON(1);
1976
1977        return 0;
1978}
1979
1980unsigned long nr_lock_chains;
1981struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1982int nr_chain_hlocks;
1983static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1984
1985struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1986{
1987        return lock_classes + chain_hlocks[chain->base + i];
1988}
1989
1990/*
1991 * Look up a dependency chain. If the key is not present yet then
1992 * add it and return 1 - in this case the new dependency chain is
1993 * validated. If the key is already hashed, return 0.
1994 * (On return with 1 graph_lock is held.)
1995 */
1996static inline int lookup_chain_cache(struct task_struct *curr,
1997                                     struct held_lock *hlock,
1998                                     u64 chain_key)
1999{
2000        struct lock_class *class = hlock_class(hlock);
2001        struct list_head *hash_head = chainhashentry(chain_key);
2002        struct lock_chain *chain;
2003        struct held_lock *hlock_curr, *hlock_next;
2004        int i, j;
2005
2006        /*
2007         * We might need to take the graph lock, ensure we've got IRQs
2008         * disabled to make this an IRQ-safe lock.. for recursion reasons
2009         * lockdep won't complain about its own locking errors.
2010         */
2011        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2012                return 0;
2013        /*
2014         * We can walk it lock-free, because entries only get added
2015         * to the hash:
2016         */
2017        list_for_each_entry(chain, hash_head, entry) {
2018                if (chain->chain_key == chain_key) {
2019cache_hit:
2020                        debug_atomic_inc(chain_lookup_hits);
2021                        if (very_verbose(class))
2022                                printk("\nhash chain already cached, key: "
2023                                        "%016Lx tail class: [%p] %s\n",
2024                                        (unsigned long long)chain_key,
2025                                        class->key, class->name);
2026                        return 0;
2027                }
2028        }
2029        if (very_verbose(class))
2030                printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2031                        (unsigned long long)chain_key, class->key, class->name);
2032        /*
2033         * Allocate a new chain entry from the static array, and add
2034         * it to the hash:
2035         */
2036        if (!graph_lock())
2037                return 0;
2038        /*
2039         * We have to walk the chain again locked - to avoid duplicates:
2040         */
2041        list_for_each_entry(chain, hash_head, entry) {
2042                if (chain->chain_key == chain_key) {
2043                        graph_unlock();
2044                        goto cache_hit;
2045                }
2046        }
2047        if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2048                if (!debug_locks_off_graph_unlock())
2049                        return 0;
2050
2051                printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2052                printk("turning off the locking correctness validator.\n");
2053                dump_stack();
2054                return 0;
2055        }
2056        chain = lock_chains + nr_lock_chains++;
2057        chain->chain_key = chain_key;
2058        chain->irq_context = hlock->irq_context;
2059        /* Find the first held_lock of current chain */
2060        hlock_next = hlock;
2061        for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2062                hlock_curr = curr->held_locks + i;
2063                if (hlock_curr->irq_context != hlock_next->irq_context)
2064                        break;
2065                hlock_next = hlock;
2066        }
2067        i++;
2068        chain->depth = curr->lockdep_depth + 1 - i;
2069        if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2070                chain->base = nr_chain_hlocks;
2071                nr_chain_hlocks += chain->depth;
2072                for (j = 0; j < chain->depth - 1; j++, i++) {
2073                        int lock_id = curr->held_locks[i].class_idx - 1;
2074                        chain_hlocks[chain->base + j] = lock_id;
2075                }
2076                chain_hlocks[chain->base + j] = class - lock_classes;
2077        }
2078        list_add_tail_rcu(&chain->entry, hash_head);
2079        debug_atomic_inc(chain_lookup_misses);
2080        inc_chains();
2081
2082        return 1;
2083}
2084
2085static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2086                struct held_lock *hlock, int chain_head, u64 chain_key)
2087{
2088        /*
2089         * Trylock needs to maintain the stack of held locks, but it
2090         * does not add new dependencies, because trylock can be done
2091         * in any order.
2092         *
2093         * We look up the chain_key and do the O(N^2) check and update of
2094         * the dependencies only if this is a new dependency chain.
2095         * (If lookup_chain_cache() returns with 1 it acquires
2096         * graph_lock for us)
2097         */
2098        if (!hlock->trylock && (hlock->check == 2) &&
2099            lookup_chain_cache(curr, hlock, chain_key)) {
2100                /*
2101                 * Check whether last held lock:
2102                 *
2103                 * - is irq-safe, if this lock is irq-unsafe
2104                 * - is softirq-safe, if this lock is hardirq-unsafe
2105                 *
2106                 * And check whether the new lock's dependency graph
2107                 * could lead back to the previous lock.
2108                 *
2109                 * any of these scenarios could lead to a deadlock. If
2110                 * All validations
2111                 */
2112                int ret = check_deadlock(curr, hlock, lock, hlock->read);
2113
2114                if (!ret)
2115                        return 0;
2116                /*
2117                 * Mark recursive read, as we jump over it when
2118                 * building dependencies (just like we jump over
2119                 * trylock entries):
2120                 */
2121                if (ret == 2)
2122                        hlock->read = 2;
2123                /*
2124                 * Add dependency only if this lock is not the head
2125                 * of the chain, and if it's not a secondary read-lock:
2126                 */
2127                if (!chain_head && ret != 2)
2128                        if (!check_prevs_add(curr, hlock))
2129                                return 0;
2130                graph_unlock();
2131        } else
2132                /* after lookup_chain_cache(): */
2133                if (unlikely(!debug_locks))
2134                        return 0;
2135
2136        return 1;
2137}
2138#else
2139static inline int validate_chain(struct task_struct *curr,
2140                struct lockdep_map *lock, struct held_lock *hlock,
2141                int chain_head, u64 chain_key)
2142{
2143        return 1;
2144}
2145#endif
2146
2147/*
2148 * We are building curr_chain_key incrementally, so double-check
2149 * it from scratch, to make sure that it's done correctly:
2150 */
2151static void check_chain_key(struct task_struct *curr)
2152{
2153#ifdef CONFIG_DEBUG_LOCKDEP
2154        struct held_lock *hlock, *prev_hlock = NULL;
2155        unsigned int i, id;
2156        u64 chain_key = 0;
2157
2158        for (i = 0; i < curr->lockdep_depth; i++) {
2159                hlock = curr->held_locks + i;
2160                if (chain_key != hlock->prev_chain_key) {
2161                        debug_locks_off();
2162                        /*
2163                         * We got mighty confused, our chain keys don't match
2164                         * with what we expect, someone trample on our task state?
2165                         */
2166                        WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2167                                curr->lockdep_depth, i,
2168                                (unsigned long long)chain_key,
2169                                (unsigned long long)hlock->prev_chain_key);
2170                        return;
2171                }
2172                id = hlock->class_idx - 1;
2173                /*
2174                 * Whoops ran out of static storage again?
2175                 */
2176                if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2177                        return;
2178
2179                if (prev_hlock && (prev_hlock->irq_context !=
2180                                                        hlock->irq_context))
2181                        chain_key = 0;
2182                chain_key = iterate_chain_key(chain_key, id);
2183                prev_hlock = hlock;
2184        }
2185        if (chain_key != curr->curr_chain_key) {
2186                debug_locks_off();
2187                /*
2188                 * More smoking hash instead of calculating it, damn see these
2189                 * numbers float.. I bet that a pink elephant stepped on my memory.
2190                 */
2191                WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2192                        curr->lockdep_depth, i,
2193                        (unsigned long long)chain_key,
2194                        (unsigned long long)curr->curr_chain_key);
2195        }
2196#endif
2197}
2198
2199static void
2200print_usage_bug_scenario(struct held_lock *lock)
2201{
2202        struct lock_class *class = hlock_class(lock);
2203
2204        printk(" Possible unsafe locking scenario:\n\n");
2205        printk("       CPU0\n");
2206        printk("       ----\n");
2207        printk("  lock(");
2208        __print_lock_name(class);
2209        printk(");\n");
2210        printk("  <Interrupt>\n");
2211        printk("    lock(");
2212        __print_lock_name(class);
2213        printk(");\n");
2214        printk("\n *** DEADLOCK ***\n\n");
2215}
2216
2217static int
2218print_usage_bug(struct task_struct *curr, struct held_lock *this,
2219                enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2220{
2221        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2222                return 0;
2223
2224        printk("\n");
2225        printk("=================================\n");
2226        printk("[ INFO: inconsistent lock state ]\n");
2227        print_kernel_ident();
2228        printk("---------------------------------\n");
2229
2230        printk("inconsistent {%s} -> {%s} usage.\n",
2231                usage_str[prev_bit], usage_str[new_bit]);
2232
2233        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2234                curr->comm, task_pid_nr(curr),
2235                trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2236                trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2237                trace_hardirqs_enabled(curr),
2238                trace_softirqs_enabled(curr));
2239        print_lock(this);
2240
2241        printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2242        print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2243
2244        print_irqtrace_events(curr);
2245        printk("\nother info that might help us debug this:\n");
2246        print_usage_bug_scenario(this);
2247
2248        lockdep_print_held_locks(curr);
2249
2250        printk("\nstack backtrace:\n");
2251        dump_stack();
2252
2253        return 0;
2254}
2255
2256/*
2257 * Print out an error if an invalid bit is set:
2258 */
2259static inline int
2260valid_state(struct task_struct *curr, struct held_lock *this,
2261            enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2262{
2263        if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2264                return print_usage_bug(curr, this, bad_bit, new_bit);
2265        return 1;
2266}
2267
2268static int mark_lock(struct task_struct *curr, struct held_lock *this,
2269                     enum lock_usage_bit new_bit);
2270
2271#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2272
2273/*
2274 * print irq inversion bug:
2275 */
2276static int
2277print_irq_inversion_bug(struct task_struct *curr,
2278                        struct lock_list *root, struct lock_list *other,
2279                        struct held_lock *this, int forwards,
2280                        const char *irqclass)
2281{
2282        struct lock_list *entry = other;
2283        struct lock_list *middle = NULL;
2284        int depth;
2285
2286        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2287                return 0;
2288
2289        printk("\n");
2290        printk("=========================================================\n");
2291        printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2292        print_kernel_ident();
2293        printk("---------------------------------------------------------\n");
2294        printk("%s/%d just changed the state of lock:\n",
2295                curr->comm, task_pid_nr(curr));
2296        print_lock(this);
2297        if (forwards)
2298                printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2299        else
2300                printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2301        print_lock_name(other->class);
2302        printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2303
2304        printk("\nother info that might help us debug this:\n");
2305
2306        /* Find a middle lock (if one exists) */
2307        depth = get_lock_depth(other);
2308        do {
2309                if (depth == 0 && (entry != root)) {
2310                        printk("lockdep:%s bad path found in chain graph\n", __func__);
2311                        break;
2312                }
2313                middle = entry;
2314                entry = get_lock_parent(entry);
2315                depth--;
2316        } while (entry && entry != root && (depth >= 0));
2317        if (forwards)
2318                print_irq_lock_scenario(root, other,
2319                        middle ? middle->class : root->class, other->class);
2320        else
2321                print_irq_lock_scenario(other, root,
2322                        middle ? middle->class : other->class, root->class);
2323
2324        lockdep_print_held_locks(curr);
2325
2326        printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2327        if (!save_trace(&root->trace))
2328                return 0;
2329        print_shortest_lock_dependencies(other, root);
2330
2331        printk("\nstack backtrace:\n");
2332        dump_stack();
2333
2334        return 0;
2335}
2336
2337/*
2338 * Prove that in the forwards-direction subgraph starting at <this>
2339 * there is no lock matching <mask>:
2340 */
2341static int
2342check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2343                     enum lock_usage_bit bit, const char *irqclass)
2344{
2345        int ret;
2346        struct lock_list root;
2347        struct lock_list *uninitialized_var(target_entry);
2348
2349        root.parent = NULL;
2350        root.class = hlock_class(this);
2351        ret = find_usage_forwards(&root, bit, &target_entry);
2352        if (ret < 0)
2353                return print_bfs_bug(ret);
2354        if (ret == 1)
2355                return ret;
2356
2357        return print_irq_inversion_bug(curr, &root, target_entry,
2358                                        this, 1, irqclass);
2359}
2360
2361/*
2362 * Prove that in the backwards-direction subgraph starting at <this>
2363 * there is no lock matching <mask>:
2364 */
2365static int
2366check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2367                      enum lock_usage_bit bit, const char *irqclass)
2368{
2369        int ret;
2370        struct lock_list root;
2371        struct lock_list *uninitialized_var(target_entry);
2372
2373        root.parent = NULL;
2374        root.class = hlock_class(this);
2375        ret = find_usage_backwards(&root, bit, &target_entry);
2376        if (ret < 0)
2377                return print_bfs_bug(ret);
2378        if (ret == 1)
2379                return ret;
2380
2381        return print_irq_inversion_bug(curr, &root, target_entry,
2382                                        this, 0, irqclass);
2383}
2384
2385void print_irqtrace_events(struct task_struct *curr)
2386{
2387        printk("irq event stamp: %u\n", curr->irq_events);
2388        printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2389        print_ip_sym(curr->hardirq_enable_ip);
2390        printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2391        print_ip_sym(curr->hardirq_disable_ip);
2392        printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2393        print_ip_sym(curr->softirq_enable_ip);
2394        printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2395        print_ip_sym(curr->softirq_disable_ip);
2396}
2397
2398static int HARDIRQ_verbose(struct lock_class *class)
2399{
2400#if HARDIRQ_VERBOSE
2401        return class_filter(class);
2402#endif
2403        return 0;
2404}
2405
2406static int SOFTIRQ_verbose(struct lock_class *class)
2407{
2408#if SOFTIRQ_VERBOSE
2409        return class_filter(class);
2410#endif
2411        return 0;
2412}
2413
2414static int RECLAIM_FS_verbose(struct lock_class *class)
2415{
2416#if RECLAIM_VERBOSE
2417        return class_filter(class);
2418#endif
2419        return 0;
2420}
2421
2422#define STRICT_READ_CHECKS      1
2423
2424static int (*state_verbose_f[])(struct lock_class *class) = {
2425#define LOCKDEP_STATE(__STATE) \
2426        __STATE##_verbose,
2427#include "lockdep_states.h"
2428#undef LOCKDEP_STATE
2429};
2430
2431static inline int state_verbose(enum lock_usage_bit bit,
2432                                struct lock_class *class)
2433{
2434        return state_verbose_f[bit >> 2](class);
2435}
2436
2437typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2438                             enum lock_usage_bit bit, const char *name);
2439
2440static int
2441mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2442                enum lock_usage_bit new_bit)
2443{
2444        int excl_bit = exclusive_bit(new_bit);
2445        int read = new_bit & 1;
2446        int dir = new_bit & 2;
2447
2448        /*
2449         * mark USED_IN has to look forwards -- to ensure no dependency
2450         * has ENABLED state, which would allow recursion deadlocks.
2451         *
2452         * mark ENABLED has to look backwards -- to ensure no dependee
2453         * has USED_IN state, which, again, would allow  recursion deadlocks.
2454         */
2455        check_usage_f usage = dir ?
2456                check_usage_backwards : check_usage_forwards;
2457
2458        /*
2459         * Validate that this particular lock does not have conflicting
2460         * usage states.
2461         */
2462        if (!valid_state(curr, this, new_bit, excl_bit))
2463                return 0;
2464
2465        /*
2466         * Validate that the lock dependencies don't have conflicting usage
2467         * states.
2468         */
2469        if ((!read || !dir || STRICT_READ_CHECKS) &&
2470                        !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2471                return 0;
2472
2473        /*
2474         * Check for read in write conflicts
2475         */
2476        if (!read) {
2477                if (!valid_state(curr, this, new_bit, excl_bit + 1))
2478                        return 0;
2479
2480                if (STRICT_READ_CHECKS &&
2481                        !usage(curr, this, excl_bit + 1,
2482                                state_name(new_bit + 1)))
2483                        return 0;
2484        }
2485
2486        if (state_verbose(new_bit, hlock_class(this)))
2487                return 2;
2488
2489        return 1;
2490}
2491
2492enum mark_type {
2493#define LOCKDEP_STATE(__STATE)  __STATE,
2494#include "lockdep_states.h"
2495#undef LOCKDEP_STATE
2496};
2497
2498/*
2499 * Mark all held locks with a usage bit:
2500 */
2501static int
2502mark_held_locks(struct task_struct *curr, enum mark_type mark)
2503{
2504        enum lock_usage_bit usage_bit;
2505        struct held_lock *hlock;
2506        int i;
2507
2508        for (i = 0; i < curr->lockdep_depth; i++) {
2509                hlock = curr->held_locks + i;
2510
2511                usage_bit = 2 + (mark << 2); /* ENABLED */
2512                if (hlock->read)
2513                        usage_bit += 1; /* READ */
2514
2515                BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2516
2517                if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
2518                        continue;
2519
2520                if (!mark_lock(curr, hlock, usage_bit))
2521                        return 0;
2522        }
2523
2524        return 1;
2525}
2526
2527/*
2528 * Hardirqs will be enabled:
2529 */
2530static void __trace_hardirqs_on_caller(unsigned long ip)
2531{
2532        struct task_struct *curr = current;
2533
2534        /* we'll do an OFF -> ON transition: */
2535        curr->hardirqs_enabled = 1;
2536
2537        /*
2538         * We are going to turn hardirqs on, so set the
2539         * usage bit for all held locks:
2540         */
2541        if (!mark_held_locks(curr, HARDIRQ))
2542                return;
2543        /*
2544         * If we have softirqs enabled, then set the usage
2545         * bit for all held locks. (disabled hardirqs prevented
2546         * this bit from being set before)
2547         */
2548        if (curr->softirqs_enabled)
2549                if (!mark_held_locks(curr, SOFTIRQ))
2550                        return;
2551
2552        curr->hardirq_enable_ip = ip;
2553        curr->hardirq_enable_event = ++curr->irq_events;
2554        debug_atomic_inc(hardirqs_on_events);
2555}
2556
2557void trace_hardirqs_on_caller(unsigned long ip)
2558{
2559        time_hardirqs_on(CALLER_ADDR0, ip);
2560
2561        if (unlikely(!debug_locks || current->lockdep_recursion))
2562                return;
2563
2564        if (unlikely(current->hardirqs_enabled)) {
2565                /*
2566                 * Neither irq nor preemption are disabled here
2567                 * so this is racy by nature but losing one hit
2568                 * in a stat is not a big deal.
2569                 */
2570                __debug_atomic_inc(redundant_hardirqs_on);
2571                return;
2572        }
2573
2574        /*
2575         * We're enabling irqs and according to our state above irqs weren't
2576         * already enabled, yet we find the hardware thinks they are in fact
2577         * enabled.. someone messed up their IRQ state tracing.
2578         */
2579        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2580                return;
2581
2582        /*
2583         * See the fine text that goes along with this variable definition.
2584         */
2585        if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2586                return;
2587
2588        /*
2589         * Can't allow enabling interrupts while in an interrupt handler,
2590         * that's general bad form and such. Recursion, limited stack etc..
2591         */
2592        if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2593                return;
2594
2595        current->lockdep_recursion = 1;
2596        __trace_hardirqs_on_caller(ip);
2597        current->lockdep_recursion = 0;
2598}
2599EXPORT_SYMBOL(trace_hardirqs_on_caller);
2600
2601void trace_hardirqs_on(void)
2602{
2603        trace_hardirqs_on_caller(CALLER_ADDR0);
2604}
2605EXPORT_SYMBOL(trace_hardirqs_on);
2606
2607/*
2608 * Hardirqs were disabled:
2609 */
2610void trace_hardirqs_off_caller(unsigned long ip)
2611{
2612        struct task_struct *curr = current;
2613
2614        time_hardirqs_off(CALLER_ADDR0, ip);
2615
2616        if (unlikely(!debug_locks || current->lockdep_recursion))
2617                return;
2618
2619        /*
2620         * So we're supposed to get called after you mask local IRQs, but for
2621         * some reason the hardware doesn't quite think you did a proper job.
2622         */
2623        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2624                return;
2625
2626        if (curr->hardirqs_enabled) {
2627                /*
2628                 * We have done an ON -> OFF transition:
2629                 */
2630                curr->hardirqs_enabled = 0;
2631                curr->hardirq_disable_ip = ip;
2632                curr->hardirq_disable_event = ++curr->irq_events;
2633                debug_atomic_inc(hardirqs_off_events);
2634        } else
2635                debug_atomic_inc(redundant_hardirqs_off);
2636}
2637EXPORT_SYMBOL(trace_hardirqs_off_caller);
2638
2639void trace_hardirqs_off(void)
2640{
2641        trace_hardirqs_off_caller(CALLER_ADDR0);
2642}
2643EXPORT_SYMBOL(trace_hardirqs_off);
2644
2645/*
2646 * Softirqs will be enabled:
2647 */
2648void trace_softirqs_on(unsigned long ip)
2649{
2650        struct task_struct *curr = current;
2651
2652        if (unlikely(!debug_locks || current->lockdep_recursion))
2653                return;
2654
2655        /*
2656         * We fancy IRQs being disabled here, see softirq.c, avoids
2657         * funny state and nesting things.
2658         */
2659        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2660                return;
2661
2662        if (curr->softirqs_enabled) {
2663                debug_atomic_inc(redundant_softirqs_on);
2664                return;
2665        }
2666
2667        current->lockdep_recursion = 1;
2668        /*
2669         * We'll do an OFF -> ON transition:
2670         */
2671        curr->softirqs_enabled = 1;
2672        curr->softirq_enable_ip = ip;
2673        curr->softirq_enable_event = ++curr->irq_events;
2674        debug_atomic_inc(softirqs_on_events);
2675        /*
2676         * We are going to turn softirqs on, so set the
2677         * usage bit for all held locks, if hardirqs are
2678         * enabled too:
2679         */
2680        if (curr->hardirqs_enabled)
2681                mark_held_locks(curr, SOFTIRQ);
2682        current->lockdep_recursion = 0;
2683}
2684
2685/*
2686 * Softirqs were disabled:
2687 */
2688void trace_softirqs_off(unsigned long ip)
2689{
2690        struct task_struct *curr = current;
2691
2692        if (unlikely(!debug_locks || current->lockdep_recursion))
2693                return;
2694
2695        /*
2696         * We fancy IRQs being disabled here, see softirq.c
2697         */
2698        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2699                return;
2700
2701        if (curr->softirqs_enabled) {
2702                /*
2703                 * We have done an ON -> OFF transition:
2704                 */
2705                curr->softirqs_enabled = 0;
2706                curr->softirq_disable_ip = ip;
2707                curr->softirq_disable_event = ++curr->irq_events;
2708                debug_atomic_inc(softirqs_off_events);
2709                /*
2710                 * Whoops, we wanted softirqs off, so why aren't they?
2711                 */
2712                DEBUG_LOCKS_WARN_ON(!softirq_count());
2713        } else
2714                debug_atomic_inc(redundant_softirqs_off);
2715}
2716
2717static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2718{
2719        struct task_struct *curr = current;
2720
2721        if (unlikely(!debug_locks))
2722                return;
2723
2724        /* no reclaim without waiting on it */
2725        if (!(gfp_mask & __GFP_WAIT))
2726                return;
2727
2728        /* this guy won't enter reclaim */
2729        if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2730                return;
2731
2732        /* We're only interested __GFP_FS allocations for now */
2733        if (!(gfp_mask & __GFP_FS))
2734                return;
2735
2736        /*
2737         * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2738         */
2739        if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2740                return;
2741
2742        mark_held_locks(curr, RECLAIM_FS);
2743}
2744
2745static void check_flags(unsigned long flags);
2746
2747void lockdep_trace_alloc(gfp_t gfp_mask)
2748{
2749        unsigned long flags;
2750
2751        if (unlikely(current->lockdep_recursion))
2752                return;
2753
2754        raw_local_irq_save(flags);
2755        check_flags(flags);
2756        current->lockdep_recursion = 1;
2757        __lockdep_trace_alloc(gfp_mask, flags);
2758        current->lockdep_recursion = 0;
2759        raw_local_irq_restore(flags);
2760}
2761
2762static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2763{
2764        /*
2765         * If non-trylock use in a hardirq or softirq context, then
2766         * mark the lock as used in these contexts:
2767         */
2768        if (!hlock->trylock) {
2769                if (hlock->read) {
2770                        if (curr->hardirq_context)
2771                                if (!mark_lock(curr, hlock,
2772                                                LOCK_USED_IN_HARDIRQ_READ))
2773                                        return 0;
2774                        if (curr->softirq_context)
2775                                if (!mark_lock(curr, hlock,
2776                                                LOCK_USED_IN_SOFTIRQ_READ))
2777                                        return 0;
2778                } else {
2779                        if (curr->hardirq_context)
2780                                if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2781                                        return 0;
2782                        if (curr->softirq_context)
2783                                if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2784                                        return 0;
2785                }
2786        }
2787        if (!hlock->hardirqs_off) {
2788                if (hlock->read) {
2789                        if (!mark_lock(curr, hlock,
2790                                        LOCK_ENABLED_HARDIRQ_READ))
2791                                return 0;
2792                        if (curr->softirqs_enabled)
2793                                if (!mark_lock(curr, hlock,
2794                                                LOCK_ENABLED_SOFTIRQ_READ))
2795                                        return 0;
2796                } else {
2797                        if (!mark_lock(curr, hlock,
2798                                        LOCK_ENABLED_HARDIRQ))
2799                                return 0;
2800                        if (curr->softirqs_enabled)
2801                                if (!mark_lock(curr, hlock,
2802                                                LOCK_ENABLED_SOFTIRQ))
2803                                        return 0;
2804                }
2805        }
2806
2807        /*
2808         * We reuse the irq context infrastructure more broadly as a general
2809         * context checking code. This tests GFP_FS recursion (a lock taken
2810         * during reclaim for a GFP_FS allocation is held over a GFP_FS
2811         * allocation).
2812         */
2813        if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2814                if (hlock->read) {
2815                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2816                                        return 0;
2817                } else {
2818                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2819                                        return 0;
2820                }
2821        }
2822
2823        return 1;
2824}
2825
2826static int separate_irq_context(struct task_struct *curr,
2827                struct held_lock *hlock)
2828{
2829        unsigned int depth = curr->lockdep_depth;
2830
2831        /*
2832         * Keep track of points where we cross into an interrupt context:
2833         */
2834        hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2835                                curr->softirq_context;
2836        if (depth) {
2837                struct held_lock *prev_hlock;
2838
2839                prev_hlock = curr->held_locks + depth-1;
2840                /*
2841                 * If we cross into another context, reset the
2842                 * hash key (this also prevents the checking and the
2843                 * adding of the dependency to 'prev'):
2844                 */
2845                if (prev_hlock->irq_context != hlock->irq_context)
2846                        return 1;
2847        }
2848        return 0;
2849}
2850
2851#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2852
2853static inline
2854int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2855                enum lock_usage_bit new_bit)
2856{
2857        WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2858        return 1;
2859}
2860
2861static inline int mark_irqflags(struct task_struct *curr,
2862                struct held_lock *hlock)
2863{
2864        return 1;
2865}
2866
2867static inline int separate_irq_context(struct task_struct *curr,
2868                struct held_lock *hlock)
2869{
2870        return 0;
2871}
2872
2873void lockdep_trace_alloc(gfp_t gfp_mask)
2874{
2875}
2876
2877#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2878
2879/*
2880 * Mark a lock with a usage bit, and validate the state transition:
2881 */
2882static int mark_lock(struct task_struct *curr, struct held_lock *this,
2883                             enum lock_usage_bit new_bit)
2884{
2885        unsigned int new_mask = 1 << new_bit, ret = 1;
2886
2887        /*
2888         * If already set then do not dirty the cacheline,
2889         * nor do any checks:
2890         */
2891        if (likely(hlock_class(this)->usage_mask & new_mask))
2892                return 1;
2893
2894        if (!graph_lock())
2895                return 0;
2896        /*
2897         * Make sure we didn't race:
2898         */
2899        if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2900                graph_unlock();
2901                return 1;
2902        }
2903
2904        hlock_class(this)->usage_mask |= new_mask;
2905
2906        if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2907                return 0;
2908
2909        switch (new_bit) {
2910#define LOCKDEP_STATE(__STATE)                  \
2911        case LOCK_USED_IN_##__STATE:            \
2912        case LOCK_USED_IN_##__STATE##_READ:     \
2913        case LOCK_ENABLED_##__STATE:            \
2914        case LOCK_ENABLED_##__STATE##_READ:
2915#include "lockdep_states.h"
2916#undef LOCKDEP_STATE
2917                ret = mark_lock_irq(curr, this, new_bit);
2918                if (!ret)
2919                        return 0;
2920                break;
2921        case LOCK_USED:
2922                debug_atomic_dec(nr_unused_locks);
2923                break;
2924        default:
2925                if (!debug_locks_off_graph_unlock())
2926                        return 0;
2927                WARN_ON(1);
2928                return 0;
2929        }
2930
2931        graph_unlock();
2932
2933        /*
2934         * We must printk outside of the graph_lock:
2935         */
2936        if (ret == 2) {
2937                printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2938                print_lock(this);
2939                print_irqtrace_events(curr);
2940                dump_stack();
2941        }
2942
2943        return ret;
2944}
2945
2946/*
2947 * Initialize a lock instance's lock-class mapping info:
2948 */
2949void lockdep_init_map(struct lockdep_map *lock, const char *name,
2950                      struct lock_class_key *key, int subclass)
2951{
2952        int i;
2953
2954        kmemcheck_mark_initialized(lock, sizeof(*lock));
2955
2956        for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2957                lock->class_cache[i] = NULL;
2958
2959#ifdef CONFIG_LOCK_STAT
2960        lock->cpu = raw_smp_processor_id();
2961#endif
2962
2963        /*
2964         * Can't be having no nameless bastards around this place!
2965         */
2966        if (DEBUG_LOCKS_WARN_ON(!name)) {
2967                lock->name = "NULL";
2968                return;
2969        }
2970
2971        lock->name = name;
2972
2973        /*
2974         * No key, no joy, we need to hash something.
2975         */
2976        if (DEBUG_LOCKS_WARN_ON(!key))
2977                return;
2978        /*
2979         * Sanity check, the lock-class key must be persistent:
2980         */
2981        if (!static_obj(key)) {
2982                printk("BUG: key %p not in .data!\n", key);
2983                /*
2984                 * What it says above ^^^^^, I suggest you read it.
2985                 */
2986                DEBUG_LOCKS_WARN_ON(1);
2987                return;
2988        }
2989        lock->key = key;
2990
2991        if (unlikely(!debug_locks))
2992                return;
2993
2994        if (subclass)
2995                register_lock_class(lock, subclass, 1);
2996}
2997EXPORT_SYMBOL_GPL(lockdep_init_map);
2998
2999struct lock_class_key __lockdep_no_validate__;
3000
3001static int
3002print_lock_nested_lock_not_held(struct task_struct *curr,
3003                                struct held_lock *hlock,
3004                                unsigned long ip)
3005{
3006        if (!debug_locks_off())
3007                return 0;
3008        if (debug_locks_silent)
3009                return 0;
3010
3011        printk("\n");
3012        printk("==================================\n");
3013        printk("[ BUG: Nested lock was not taken ]\n");
3014        print_kernel_ident();
3015        printk("----------------------------------\n");
3016
3017        printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3018        print_lock(hlock);
3019
3020        printk("\nbut this task is not holding:\n");
3021        printk("%s\n", hlock->nest_lock->name);
3022
3023        printk("\nstack backtrace:\n");
3024        dump_stack();
3025
3026        printk("\nother info that might help us debug this:\n");
3027        lockdep_print_held_locks(curr);
3028
3029        printk("\nstack backtrace:\n");
3030        dump_stack();
3031
3032        return 0;
3033}
3034
3035static int __lock_is_held(struct lockdep_map *lock);
3036
3037/*
3038 * This gets called for every mutex_lock*()/spin_lock*() operation.
3039 * We maintain the dependency maps and validate the locking attempt:
3040 */
3041static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3042                          int trylock, int read, int check, int hardirqs_off,
3043                          struct lockdep_map *nest_lock, unsigned long ip,
3044                          int references)
3045{
3046        struct task_struct *curr = current;
3047        struct lock_class *class = NULL;
3048        struct held_lock *hlock;
3049        unsigned int depth, id;
3050        int chain_head = 0;
3051        int class_idx;
3052        u64 chain_key;
3053
3054        if (!prove_locking)
3055                check = 1;
3056
3057        if (unlikely(!debug_locks))
3058                return 0;
3059
3060        /*
3061         * Lockdep should run with IRQs disabled, otherwise we could
3062         * get an interrupt which would want to take locks, which would
3063         * end up in lockdep and have you got a head-ache already?
3064         */
3065        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3066                return 0;
3067
3068        if (lock->key == &__lockdep_no_validate__)
3069                check = 1;
3070
3071        if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3072                class = lock->class_cache[subclass];
3073        /*
3074         * Not cached?
3075         */
3076        if (unlikely(!class)) {
3077                class = register_lock_class(lock, subclass, 0);
3078                if (!class)
3079                        return 0;
3080        }
3081        atomic_inc((atomic_t *)&class->ops);
3082        if (very_verbose(class)) {
3083                printk("\nacquire class [%p] %s", class->key, class->name);
3084                if (class->name_version > 1)
3085                        printk("#%d", class->name_version);
3086                printk("\n");
3087                dump_stack();
3088        }
3089
3090        /*
3091         * Add the lock to the list of currently held locks.
3092         * (we dont increase the depth just yet, up until the
3093         * dependency checks are done)
3094         */
3095        depth = curr->lockdep_depth;
3096        /*
3097         * Ran out of static storage for our per-task lock stack again have we?
3098         */
3099        if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3100                return 0;
3101
3102        class_idx = class - lock_classes + 1;
3103
3104        if (depth) {
3105                hlock = curr->held_locks + depth - 1;
3106                if (hlock->class_idx == class_idx && nest_lock) {
3107                        if (hlock->references)
3108                                hlock->references++;
3109                        else
3110                                hlock->references = 2;
3111
3112                        return 1;
3113                }
3114        }
3115
3116        hlock = curr->held_locks + depth;
3117        /*
3118         * Plain impossible, we just registered it and checked it weren't no
3119         * NULL like.. I bet this mushroom I ate was good!
3120         */
3121        if (DEBUG_LOCKS_WARN_ON(!class))
3122                return 0;
3123        hlock->class_idx = class_idx;
3124        hlock->acquire_ip = ip;
3125        hlock->instance = lock;
3126        hlock->nest_lock = nest_lock;
3127        hlock->trylock = trylock;
3128        hlock->read = read;
3129        hlock->check = check;
3130        hlock->hardirqs_off = !!hardirqs_off;
3131        hlock->references = references;
3132#ifdef CONFIG_LOCK_STAT
3133        hlock->waittime_stamp = 0;
3134        hlock->holdtime_stamp = lockstat_clock();
3135#endif
3136
3137        if (check == 2 && !mark_irqflags(curr, hlock))
3138                return 0;
3139
3140        /* mark it as used: */
3141        if (!mark_lock(curr, hlock, LOCK_USED))
3142                return 0;
3143
3144        /*
3145         * Calculate the chain hash: it's the combined hash of all the
3146         * lock keys along the dependency chain. We save the hash value
3147         * at every step so that we can get the current hash easily
3148         * after unlock. The chain hash is then used to cache dependency
3149         * results.
3150         *
3151         * The 'key ID' is what is the most compact key value to drive
3152         * the hash, not class->key.
3153         */
3154        id = class - lock_classes;
3155        /*
3156         * Whoops, we did it again.. ran straight out of our static allocation.
3157         */
3158        if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3159                return 0;
3160
3161        chain_key = curr->curr_chain_key;
3162        if (!depth) {
3163                /*
3164                 * How can we have a chain hash when we ain't got no keys?!
3165                 */
3166                if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3167                        return 0;
3168                chain_head = 1;
3169        }
3170
3171        hlock->prev_chain_key = chain_key;
3172        if (separate_irq_context(curr, hlock)) {
3173                chain_key = 0;
3174                chain_head = 1;
3175        }
3176        chain_key = iterate_chain_key(chain_key, id);
3177
3178        if (nest_lock && !__lock_is_held(nest_lock))
3179                return print_lock_nested_lock_not_held(curr, hlock, ip);
3180
3181        if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3182                return 0;
3183
3184        curr->curr_chain_key = chain_key;
3185        curr->lockdep_depth++;
3186        check_chain_key(curr);
3187#ifdef CONFIG_DEBUG_LOCKDEP
3188        if (unlikely(!debug_locks))
3189                return 0;
3190#endif
3191        if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3192                debug_locks_off();
3193                printk("BUG: MAX_LOCK_DEPTH too low!\n");
3194                printk("turning off the locking correctness validator.\n");
3195                dump_stack();
3196                return 0;
3197        }
3198
3199        if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3200                max_lockdep_depth = curr->lockdep_depth;
3201
3202        return 1;
3203}
3204
3205static int
3206print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3207                           unsigned long ip)
3208{
3209        if (!debug_locks_off())
3210                return 0;
3211        if (debug_locks_silent)
3212                return 0;
3213
3214        printk("\n");
3215        printk("=====================================\n");
3216        printk("[ BUG: bad unlock balance detected! ]\n");
3217        print_kernel_ident();
3218        printk("-------------------------------------\n");
3219        printk("%s/%d is trying to release lock (",
3220                curr->comm, task_pid_nr(curr));
3221        print_lockdep_cache(lock);
3222        printk(") at:\n");
3223        print_ip_sym(ip);
3224        printk("but there are no more locks to release!\n");
3225        printk("\nother info that might help us debug this:\n");
3226        lockdep_print_held_locks(curr);
3227
3228        printk("\nstack backtrace:\n");
3229        dump_stack();
3230
3231        return 0;
3232}
3233
3234/*
3235 * Common debugging checks for both nested and non-nested unlock:
3236 */
3237static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3238                        unsigned long ip)
3239{
3240        if (unlikely(!debug_locks))
3241                return 0;
3242        /*
3243         * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3244         */
3245        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3246                return 0;
3247
3248        if (curr->lockdep_depth <= 0)
3249                return print_unlock_inbalance_bug(curr, lock, ip);
3250
3251        return 1;
3252}
3253
3254static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3255{
3256        if (hlock->instance == lock)
3257                return 1;
3258
3259        if (hlock->references) {
3260                struct lock_class *class = lock->class_cache[0];
3261
3262                if (!class)
3263                        class = look_up_lock_class(lock, 0);
3264
3265                /*
3266                 * If look_up_lock_class() failed to find a class, we're trying
3267                 * to test if we hold a lock that has never yet been acquired.
3268                 * Clearly if the lock hasn't been acquired _ever_, we're not
3269                 * holding it either, so report failure.
3270                 */
3271                if (!class)
3272                        return 0;
3273
3274                /*
3275                 * References, but not a lock we're actually ref-counting?
3276                 * State got messed up, follow the sites that change ->references
3277                 * and try to make sense of it.
3278                 */
3279                if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3280                        return 0;
3281
3282                if (hlock->class_idx == class - lock_classes + 1)
3283                        return 1;
3284        }
3285
3286        return 0;
3287}
3288
3289static int
3290__lock_set_class(struct lockdep_map *lock, const char *name,
3291                 struct lock_class_key *key, unsigned int subclass,
3292                 unsigned long ip)
3293{
3294        struct task_struct *curr = current;
3295        struct held_lock *hlock, *prev_hlock;
3296        struct lock_class *class;
3297        unsigned int depth;
3298        int i;
3299
3300        depth = curr->lockdep_depth;
3301        /*
3302         * This function is about (re)setting the class of a held lock,
3303         * yet we're not actually holding any locks. Naughty user!
3304         */
3305        if (DEBUG_LOCKS_WARN_ON(!depth))
3306                return 0;
3307
3308        prev_hlock = NULL;
3309        for (i = depth-1; i >= 0; i--) {
3310                hlock = curr->held_locks + i;
3311                /*
3312                 * We must not cross into another context:
3313                 */
3314                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3315                        break;
3316                if (match_held_lock(hlock, lock))
3317                        goto found_it;
3318                prev_hlock = hlock;
3319        }
3320        return print_unlock_inbalance_bug(curr, lock, ip);
3321
3322found_it:
3323        lockdep_init_map(lock, name, key, 0);
3324        class = register_lock_class(lock, subclass, 0);
3325        hlock->class_idx = class - lock_classes + 1;
3326
3327        curr->lockdep_depth = i;
3328        curr->curr_chain_key = hlock->prev_chain_key;
3329
3330        for (; i < depth; i++) {
3331                hlock = curr->held_locks + i;
3332                if (!__lock_acquire(hlock->instance,
3333                        hlock_class(hlock)->subclass, hlock->trylock,
3334                                hlock->read, hlock->check, hlock->hardirqs_off,
3335                                hlock->nest_lock, hlock->acquire_ip,
3336                                hlock->references))
3337                        return 0;
3338        }
3339
3340        /*
3341         * I took it apart and put it back together again, except now I have
3342         * these 'spare' parts.. where shall I put them.
3343         */
3344        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3345                return 0;
3346        return 1;
3347}
3348
3349/*
3350 * Remove the lock to the list of currently held locks in a
3351 * potentially non-nested (out of order) manner. This is a
3352 * relatively rare operation, as all the unlock APIs default
3353 * to nested mode (which uses lock_release()):
3354 */
3355static int
3356lock_release_non_nested(struct task_struct *curr,
3357                        struct lockdep_map *lock, unsigned long ip)
3358{
3359        struct held_lock *hlock, *prev_hlock;
3360        unsigned int depth;
3361        int i;
3362
3363        /*
3364         * Check whether the lock exists in the current stack
3365         * of held locks:
3366         */
3367        depth = curr->lockdep_depth;
3368        /*
3369         * So we're all set to release this lock.. wait what lock? We don't
3370         * own any locks, you've been drinking again?
3371         */
3372        if (DEBUG_LOCKS_WARN_ON(!depth))
3373                return 0;
3374
3375        prev_hlock = NULL;
3376        for (i = depth-1; i >= 0; i--) {
3377                hlock = curr->held_locks + i;
3378                /*
3379                 * We must not cross into another context:
3380                 */
3381                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3382                        break;
3383                if (match_held_lock(hlock, lock))
3384                        goto found_it;
3385                prev_hlock = hlock;
3386        }
3387        return print_unlock_inbalance_bug(curr, lock, ip);
3388
3389found_it:
3390        if (hlock->instance == lock)
3391                lock_release_holdtime(hlock);
3392
3393        if (hlock->references) {
3394                hlock->references--;
3395                if (hlock->references) {
3396                        /*
3397                         * We had, and after removing one, still have
3398                         * references, the current lock stack is still
3399                         * valid. We're done!
3400                         */
3401                        return 1;
3402                }
3403        }
3404
3405        /*
3406         * We have the right lock to unlock, 'hlock' points to it.
3407         * Now we remove it from the stack, and add back the other
3408         * entries (if any), recalculating the hash along the way:
3409         */
3410
3411        curr->lockdep_depth = i;
3412        curr->curr_chain_key = hlock->prev_chain_key;
3413
3414        for (i++; i < depth; i++) {
3415                hlock = curr->held_locks + i;
3416                if (!__lock_acquire(hlock->instance,
3417                        hlock_class(hlock)->subclass, hlock->trylock,
3418                                hlock->read, hlock->check, hlock->hardirqs_off,
3419                                hlock->nest_lock, hlock->acquire_ip,
3420                                hlock->references))
3421                        return 0;
3422        }
3423
3424        /*
3425         * We had N bottles of beer on the wall, we drank one, but now
3426         * there's not N-1 bottles of beer left on the wall...
3427         */
3428        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3429                return 0;
3430        return 1;
3431}
3432
3433/*
3434 * Remove the lock to the list of currently held locks - this gets
3435 * called on mutex_unlock()/spin_unlock*() (or on a failed
3436 * mutex_lock_interruptible()). This is done for unlocks that nest
3437 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3438 */
3439static int lock_release_nested(struct task_struct *curr,
3440                               struct lockdep_map *lock, unsigned long ip)
3441{
3442        struct held_lock *hlock;
3443        unsigned int depth;
3444
3445        /*
3446         * Pop off the top of the lock stack:
3447         */
3448        depth = curr->lockdep_depth - 1;
3449        hlock = curr->held_locks + depth;
3450
3451        /*
3452         * Is the unlock non-nested:
3453         */
3454        if (hlock->instance != lock || hlock->references)
3455                return lock_release_non_nested(curr, lock, ip);
3456        curr->lockdep_depth--;
3457
3458        /*
3459         * No more locks, but somehow we've got hash left over, who left it?
3460         */
3461        if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3462                return 0;
3463
3464        curr->curr_chain_key = hlock->prev_chain_key;
3465
3466        lock_release_holdtime(hlock);
3467
3468#ifdef CONFIG_DEBUG_LOCKDEP
3469        hlock->prev_chain_key = 0;
3470        hlock->class_idx = 0;
3471        hlock->acquire_ip = 0;
3472        hlock->irq_context = 0;
3473#endif
3474        return 1;
3475}
3476
3477/*
3478 * Remove the lock to the list of currently held locks - this gets
3479 * called on mutex_unlock()/spin_unlock*() (or on a failed
3480 * mutex_lock_interruptible()). This is done for unlocks that nest
3481 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3482 */
3483static void
3484__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3485{
3486        struct task_struct *curr = current;
3487
3488        if (!check_unlock(curr, lock, ip))
3489                return;
3490
3491        if (nested) {
3492                if (!lock_release_nested(curr, lock, ip))
3493                        return;
3494        } else {
3495                if (!lock_release_non_nested(curr, lock, ip))
3496                        return;
3497        }
3498
3499        check_chain_key(curr);
3500}
3501
3502static int __lock_is_held(struct lockdep_map *lock)
3503{
3504        struct task_struct *curr = current;
3505        int i;
3506
3507        for (i = 0; i < curr->lockdep_depth; i++) {
3508                struct held_lock *hlock = curr->held_locks + i;
3509
3510                if (match_held_lock(hlock, lock))
3511                        return 1;
3512        }
3513
3514        return 0;
3515}
3516
3517/*
3518 * Check whether we follow the irq-flags state precisely:
3519 */
3520static void check_flags(unsigned long flags)
3521{
3522#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3523    defined(CONFIG_TRACE_IRQFLAGS)
3524        if (!debug_locks)
3525                return;
3526
3527        if (irqs_disabled_flags(flags)) {
3528                if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3529                        printk("possible reason: unannotated irqs-off.\n");
3530                }
3531        } else {
3532                if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3533                        printk("possible reason: unannotated irqs-on.\n");
3534                }
3535        }
3536
3537        /*
3538         * We dont accurately track softirq state in e.g.
3539         * hardirq contexts (such as on 4KSTACKS), so only
3540         * check if not in hardirq contexts:
3541         */
3542        if (!hardirq_count()) {
3543                if (softirq_count()) {
3544                        /* like the above, but with softirqs */
3545                        DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3546                } else {
3547                        /* lick the above, does it taste good? */
3548                        DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3549                }
3550        }
3551
3552        if (!debug_locks)
3553                print_irqtrace_events(current);
3554#endif
3555}
3556
3557void lock_set_class(struct lockdep_map *lock, const char *name,
3558                    struct lock_class_key *key, unsigned int subclass,
3559                    unsigned long ip)
3560{
3561        unsigned long flags;
3562
3563        if (unlikely(current->lockdep_recursion))
3564                return;
3565
3566        raw_local_irq_save(flags);
3567        current->lockdep_recursion = 1;
3568        check_flags(flags);
3569        if (__lock_set_class(lock, name, key, subclass, ip))
3570                check_chain_key(current);
3571        current->lockdep_recursion = 0;
3572        raw_local_irq_restore(flags);
3573}
3574EXPORT_SYMBOL_GPL(lock_set_class);
3575
3576/*
3577 * We are not always called with irqs disabled - do that here,
3578 * and also avoid lockdep recursion:
3579 */
3580void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3581                          int trylock, int read, int check,
3582                          struct lockdep_map *nest_lock, unsigned long ip)
3583{
3584        unsigned long flags;
3585
3586        if (unlikely(current->lockdep_recursion))
3587                return;
3588
3589        raw_local_irq_save(flags);
3590        check_flags(flags);
3591
3592        current->lockdep_recursion = 1;
3593        trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3594        __lock_acquire(lock, subclass, trylock, read, check,
3595                       irqs_disabled_flags(flags), nest_lock, ip, 0);
3596        current->lockdep_recursion = 0;
3597        raw_local_irq_restore(flags);
3598}
3599EXPORT_SYMBOL_GPL(lock_acquire);
3600
3601void lock_release(struct lockdep_map *lock, int nested,
3602                          unsigned long ip)
3603{
3604        unsigned long flags;
3605
3606        if (unlikely(current->lockdep_recursion))
3607                return;
3608
3609        raw_local_irq_save(flags);
3610        check_flags(flags);
3611        current->lockdep_recursion = 1;
3612        trace_lock_release(lock, ip);
3613        __lock_release(lock, nested, ip);
3614        current->lockdep_recursion = 0;
3615        raw_local_irq_restore(flags);
3616}
3617EXPORT_SYMBOL_GPL(lock_release);
3618
3619int lock_is_held(struct lockdep_map *lock)
3620{
3621        unsigned long flags;
3622        int ret = 0;
3623
3624        if (unlikely(current->lockdep_recursion))
3625                return 1; /* avoid false negative lockdep_assert_held() */
3626
3627        raw_local_irq_save(flags);
3628        check_flags(flags);
3629
3630        current->lockdep_recursion = 1;
3631        ret = __lock_is_held(lock);
3632        current->lockdep_recursion = 0;
3633        raw_local_irq_restore(flags);
3634
3635        return ret;
3636}
3637EXPORT_SYMBOL_GPL(lock_is_held);
3638
3639void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3640{
3641        current->lockdep_reclaim_gfp = gfp_mask;
3642}
3643
3644void lockdep_clear_current_reclaim_state(void)
3645{
3646        current->lockdep_reclaim_gfp = 0;
3647}
3648
3649#ifdef CONFIG_LOCK_STAT
3650static int
3651print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3652                           unsigned long ip)
3653{
3654        if (!debug_locks_off())
3655                return 0;
3656        if (debug_locks_silent)
3657                return 0;
3658
3659        printk("\n");
3660        printk("=================================\n");
3661        printk("[ BUG: bad contention detected! ]\n");
3662        print_kernel_ident();
3663        printk("---------------------------------\n");
3664        printk("%s/%d is trying to contend lock (",
3665                curr->comm, task_pid_nr(curr));
3666        print_lockdep_cache(lock);
3667        printk(") at:\n");
3668        print_ip_sym(ip);
3669        printk("but there are no locks held!\n");
3670        printk("\nother info that might help us debug this:\n");
3671        lockdep_print_held_locks(curr);
3672
3673        printk("\nstack backtrace:\n");
3674        dump_stack();
3675
3676        return 0;
3677}
3678
3679static void
3680__lock_contended(struct lockdep_map *lock, unsigned long ip)
3681{
3682        struct task_struct *curr = current;
3683        struct held_lock *hlock, *prev_hlock;
3684        struct lock_class_stats *stats;
3685        unsigned int depth;
3686        int i, contention_point, contending_point;
3687
3688        depth = curr->lockdep_depth;
3689        /*
3690         * Whee, we contended on this lock, except it seems we're not
3691         * actually trying to acquire anything much at all..
3692         */
3693        if (DEBUG_LOCKS_WARN_ON(!depth))
3694                return;
3695
3696        prev_hlock = NULL;
3697        for (i = depth-1; i >= 0; i--) {
3698                hlock = curr->held_locks + i;
3699                /*
3700                 * We must not cross into another context:
3701                 */
3702                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3703                        break;
3704                if (match_held_lock(hlock, lock))
3705                        goto found_it;
3706                prev_hlock = hlock;
3707        }
3708        print_lock_contention_bug(curr, lock, ip);
3709        return;
3710
3711found_it:
3712        if (hlock->instance != lock)
3713                return;
3714
3715        hlock->waittime_stamp = lockstat_clock();
3716
3717        contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3718        contending_point = lock_point(hlock_class(hlock)->contending_point,
3719                                      lock->ip);
3720
3721        stats = get_lock_stats(hlock_class(hlock));
3722        if (contention_point < LOCKSTAT_POINTS)
3723                stats->contention_point[contention_point]++;
3724        if (contending_point < LOCKSTAT_POINTS)
3725                stats->contending_point[contending_point]++;
3726        if (lock->cpu != smp_processor_id())
3727                stats->bounces[bounce_contended + !!hlock->read]++;
3728        put_lock_stats(stats);
3729}
3730
3731static void
3732__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3733{
3734        struct task_struct *curr = current;
3735        struct held_lock *hlock, *prev_hlock;
3736        struct lock_class_stats *stats;
3737        unsigned int depth;
3738        u64 now, waittime = 0;
3739        int i, cpu;
3740
3741        depth = curr->lockdep_depth;
3742        /*
3743         * Yay, we acquired ownership of this lock we didn't try to
3744         * acquire, how the heck did that happen?
3745         */
3746        if (DEBUG_LOCKS_WARN_ON(!depth))
3747                return;
3748
3749        prev_hlock = NULL;
3750        for (i = depth-1; i >= 0; i--) {
3751                hlock = curr->held_locks + i;
3752                /*
3753                 * We must not cross into another context:
3754                 */
3755                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3756                        break;
3757                if (match_held_lock(hlock, lock))
3758                        goto found_it;
3759                prev_hlock = hlock;
3760        }
3761        print_lock_contention_bug(curr, lock, _RET_IP_);
3762        return;
3763
3764found_it:
3765        if (hlock->instance != lock)
3766                return;
3767
3768        cpu = smp_processor_id();
3769        if (hlock->waittime_stamp) {
3770                now = lockstat_clock();
3771                waittime = now - hlock->waittime_stamp;
3772                hlock->holdtime_stamp = now;
3773        }
3774
3775        trace_lock_acquired(lock, ip);
3776
3777        stats = get_lock_stats(hlock_class(hlock));
3778        if (waittime) {
3779                if (hlock->read)
3780                        lock_time_inc(&stats->read_waittime, waittime);
3781                else
3782                        lock_time_inc(&stats->write_waittime, waittime);
3783        }
3784        if (lock->cpu != cpu)
3785                stats->bounces[bounce_acquired + !!hlock->read]++;
3786        put_lock_stats(stats);
3787
3788        lock->cpu = cpu;
3789        lock->ip = ip;
3790}
3791
3792void lock_contended(struct lockdep_map *lock, unsigned long ip)
3793{
3794        unsigned long flags;
3795
3796        if (unlikely(!lock_stat))
3797                return;
3798
3799        if (unlikely(current->lockdep_recursion))
3800                return;
3801
3802        raw_local_irq_save(flags);
3803        check_flags(flags);
3804        current->lockdep_recursion = 1;
3805        trace_lock_contended(lock, ip);
3806        __lock_contended(lock, ip);
3807        current->lockdep_recursion = 0;
3808        raw_local_irq_restore(flags);
3809}
3810EXPORT_SYMBOL_GPL(lock_contended);
3811
3812void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3813{
3814        unsigned long flags;
3815
3816        if (unlikely(!lock_stat))
3817                return;
3818
3819        if (unlikely(current->lockdep_recursion))
3820                return;
3821
3822        raw_local_irq_save(flags);
3823        check_flags(flags);
3824        current->lockdep_recursion = 1;
3825        __lock_acquired(lock, ip);
3826        current->lockdep_recursion = 0;
3827        raw_local_irq_restore(flags);
3828}
3829EXPORT_SYMBOL_GPL(lock_acquired);
3830#endif
3831
3832/*
3833 * Used by the testsuite, sanitize the validator state
3834 * after a simulated failure:
3835 */
3836
3837void lockdep_reset(void)
3838{
3839        unsigned long flags;
3840        int i;
3841
3842        raw_local_irq_save(flags);
3843        current->curr_chain_key = 0;
3844        current->lockdep_depth = 0;
3845        current->lockdep_recursion = 0;
3846        memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3847        nr_hardirq_chains = 0;
3848        nr_softirq_chains = 0;
3849        nr_process_chains = 0;
3850        debug_locks = 1;
3851        for (i = 0; i < CHAINHASH_SIZE; i++)
3852                INIT_LIST_HEAD(chainhash_table + i);
3853        raw_local_irq_restore(flags);
3854}
3855
3856static void zap_class(struct lock_class *class)
3857{
3858        int i;
3859
3860        /*
3861         * Remove all dependencies this lock is
3862         * involved in:
3863         */
3864        for (i = 0; i < nr_list_entries; i++) {
3865                if (list_entries[i].class == class)
3866                        list_del_rcu(&list_entries[i].entry);
3867        }
3868        /*
3869         * Unhash the class and remove it from the all_lock_classes list:
3870         */
3871        list_del_rcu(&class->hash_entry);
3872        list_del_rcu(&class->lock_entry);
3873
3874        class->key = NULL;
3875}
3876
3877static inline int within(const void *addr, void *start, unsigned long size)
3878{
3879        return addr >= start && addr < start + size;
3880}
3881
3882void lockdep_free_key_range(void *start, unsigned long size)
3883{
3884        struct lock_class *class, *next;
3885        struct list_head *head;
3886        unsigned long flags;
3887        int i;
3888        int locked;
3889
3890        raw_local_irq_save(flags);
3891        locked = graph_lock();
3892
3893        /*
3894         * Unhash all classes that were created by this module:
3895         */
3896        for (i = 0; i < CLASSHASH_SIZE; i++) {
3897                head = classhash_table + i;
3898                if (list_empty(head))
3899                        continue;
3900                list_for_each_entry_safe(class, next, head, hash_entry) {
3901                        if (within(class->key, start, size))
3902                                zap_class(class);
3903                        else if (within(class->name, start, size))
3904                                zap_class(class);
3905                }
3906        }
3907
3908        if (locked)
3909                graph_unlock();
3910        raw_local_irq_restore(flags);
3911}
3912
3913void lockdep_reset_lock(struct lockdep_map *lock)
3914{
3915        struct lock_class *class, *next;
3916        struct list_head *head;
3917        unsigned long flags;
3918        int i, j;
3919        int locked;
3920
3921        raw_local_irq_save(flags);
3922
3923        /*
3924         * Remove all classes this lock might have:
3925         */
3926        for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3927                /*
3928                 * If the class exists we look it up and zap it:
3929                 */
3930                class = look_up_lock_class(lock, j);
3931                if (class)
3932                        zap_class(class);
3933        }
3934        /*
3935         * Debug check: in the end all mapped classes should
3936         * be gone.
3937         */
3938        locked = graph_lock();
3939        for (i = 0; i < CLASSHASH_SIZE; i++) {
3940                head = classhash_table + i;
3941                if (list_empty(head))
3942                        continue;
3943                list_for_each_entry_safe(class, next, head, hash_entry) {
3944                        int match = 0;
3945
3946                        for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3947                                match |= class == lock->class_cache[j];
3948
3949                        if (unlikely(match)) {
3950                                if (debug_locks_off_graph_unlock()) {
3951                                        /*
3952                                         * We all just reset everything, how did it match?
3953                                         */
3954                                        WARN_ON(1);
3955                                }
3956                                goto out_restore;
3957                        }
3958                }
3959        }
3960        if (locked)
3961                graph_unlock();
3962
3963out_restore:
3964        raw_local_irq_restore(flags);
3965}
3966
3967void lockdep_init(void)
3968{
3969        int i;
3970
3971        /*
3972         * Some architectures have their own start_kernel()
3973         * code which calls lockdep_init(), while we also
3974         * call lockdep_init() from the start_kernel() itself,
3975         * and we want to initialize the hashes only once:
3976         */
3977        if (lockdep_initialized)
3978                return;
3979
3980        for (i = 0; i < CLASSHASH_SIZE; i++)
3981                INIT_LIST_HEAD(classhash_table + i);
3982
3983        for (i = 0; i < CHAINHASH_SIZE; i++)
3984                INIT_LIST_HEAD(chainhash_table + i);
3985
3986        lockdep_initialized = 1;
3987}
3988
3989void __init lockdep_info(void)
3990{
3991        printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3992
3993        printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3994        printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3995        printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3996        printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3997        printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3998        printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3999        printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
4000
4001        printk(" memory used by lock dependency info: %lu kB\n",
4002                (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4003                sizeof(struct list_head) * CLASSHASH_SIZE +
4004                sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4005                sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4006                sizeof(struct list_head) * CHAINHASH_SIZE
4007#ifdef CONFIG_PROVE_LOCKING
4008                + sizeof(struct circular_queue)
4009#endif
4010                ) / 1024
4011                );
4012
4013        printk(" per task-struct memory footprint: %lu bytes\n",
4014                sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4015
4016#ifdef CONFIG_DEBUG_LOCKDEP
4017        if (lockdep_init_error) {
4018                printk("WARNING: lockdep init error! lock-%s was acquired"
4019                        "before lockdep_init\n", lock_init_error);
4020                printk("Call stack leading to lockdep invocation was:\n");
4021                print_stack_trace(&lockdep_init_trace, 0);
4022        }
4023#endif
4024}
4025
4026static void
4027print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4028                     const void *mem_to, struct held_lock *hlock)
4029{
4030        if (!debug_locks_off())
4031                return;
4032        if (debug_locks_silent)
4033                return;
4034
4035        printk("\n");
4036        printk("=========================\n");
4037        printk("[ BUG: held lock freed! ]\n");
4038        print_kernel_ident();
4039        printk("-------------------------\n");
4040        printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4041                curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4042        print_lock(hlock);
4043        lockdep_print_held_locks(curr);
4044
4045        printk("\nstack backtrace:\n");
4046        dump_stack();
4047}
4048
4049static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4050                                const void* lock_from, unsigned long lock_len)
4051{
4052        return lock_from + lock_len <= mem_from ||
4053                mem_from + mem_len <= lock_from;
4054}
4055
4056/*
4057 * Called when kernel memory is freed (or unmapped), or if a lock
4058 * is destroyed or reinitialized - this code checks whether there is
4059 * any held lock in the memory range of <from> to <to>:
4060 */
4061void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4062{
4063        struct task_struct *curr = current;
4064        struct held_lock *hlock;
4065        unsigned long flags;
4066        int i;
4067
4068        if (unlikely(!debug_locks))
4069                return;
4070
4071        local_irq_save(flags);
4072        for (i = 0; i < curr->lockdep_depth; i++) {
4073                hlock = curr->held_locks + i;
4074
4075                if (not_in_range(mem_from, mem_len, hlock->instance,
4076                                        sizeof(*hlock->instance)))
4077                        continue;
4078
4079                print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4080                break;
4081        }
4082        local_irq_restore(flags);
4083}
4084EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4085
4086static void print_held_locks_bug(struct task_struct *curr)
4087{
4088        if (!debug_locks_off())
4089                return;
4090        if (debug_locks_silent)
4091                return;
4092
4093        printk("\n");
4094        printk("=====================================\n");
4095        printk("[ BUG: lock held at task exit time! ]\n");
4096        print_kernel_ident();
4097        printk("-------------------------------------\n");
4098        printk("%s/%d is exiting with locks still held!\n",
4099                curr->comm, task_pid_nr(curr));
4100        lockdep_print_held_locks(curr);
4101
4102        printk("\nstack backtrace:\n");
4103        dump_stack();
4104}
4105
4106void debug_check_no_locks_held(struct task_struct *task)
4107{
4108        if (unlikely(task->lockdep_depth > 0))
4109                print_held_locks_bug(task);
4110}
4111
4112void debug_show_all_locks(void)
4113{
4114        struct task_struct *g, *p;
4115        int count = 10;
4116        int unlock = 1;
4117
4118        if (unlikely(!debug_locks)) {
4119                printk("INFO: lockdep is turned off.\n");
4120                return;
4121        }
4122        printk("\nShowing all locks held in the system:\n");
4123
4124        /*
4125         * Here we try to get the tasklist_lock as hard as possible,
4126         * if not successful after 2 seconds we ignore it (but keep
4127         * trying). This is to enable a debug printout even if a
4128         * tasklist_lock-holding task deadlocks or crashes.
4129         */
4130retry:
4131        if (!read_trylock(&tasklist_lock)) {
4132                if (count == 10)
4133                        printk("hm, tasklist_lock locked, retrying... ");
4134                if (count) {
4135                        count--;
4136                        printk(" #%d", 10-count);
4137                        mdelay(200);
4138                        goto retry;
4139                }
4140                printk(" ignoring it.\n");
4141                unlock = 0;
4142        } else {
4143                if (count != 10)
4144                        printk(KERN_CONT " locked it.\n");
4145        }
4146
4147        do_each_thread(g, p) {
4148                /*
4149                 * It's not reliable to print a task's held locks
4150                 * if it's not sleeping (or if it's not the current
4151                 * task):
4152                 */
4153                if (p->state == TASK_RUNNING && p != current)
4154                        continue;
4155                if (p->lockdep_depth)
4156                        lockdep_print_held_locks(p);
4157                if (!unlock)
4158                        if (read_trylock(&tasklist_lock))
4159                                unlock = 1;
4160        } while_each_thread(g, p);
4161
4162        printk("\n");
4163        printk("=============================================\n\n");
4164
4165        if (unlock)
4166                read_unlock(&tasklist_lock);
4167}
4168EXPORT_SYMBOL_GPL(debug_show_all_locks);
4169
4170/*
4171 * Careful: only use this function if you are sure that
4172 * the task cannot run in parallel!
4173 */
4174void debug_show_held_locks(struct task_struct *task)
4175{
4176        if (unlikely(!debug_locks)) {
4177                printk("INFO: lockdep is turned off.\n");
4178                return;
4179        }
4180        lockdep_print_held_locks(task);
4181}
4182EXPORT_SYMBOL_GPL(debug_show_held_locks);
4183
4184void lockdep_sys_exit(void)
4185{
4186        struct task_struct *curr = current;
4187
4188        if (unlikely(curr->lockdep_depth)) {
4189                if (!debug_locks_off())
4190                        return;
4191                printk("\n");
4192                printk("================================================\n");
4193                printk("[ BUG: lock held when returning to user space! ]\n");
4194                print_kernel_ident();
4195                printk("------------------------------------------------\n");
4196                printk("%s/%d is leaving the kernel with locks still held!\n",
4197                                curr->comm, curr->pid);
4198                lockdep_print_held_locks(curr);
4199        }
4200}
4201
4202void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4203{
4204        struct task_struct *curr = current;
4205
4206#ifndef CONFIG_PROVE_RCU_REPEATEDLY
4207        if (!debug_locks_off())
4208                return;
4209#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4210        /* Note: the following can be executed concurrently, so be careful. */
4211        printk("\n");
4212        printk("===============================\n");
4213        printk("[ INFO: suspicious RCU usage. ]\n");
4214        print_kernel_ident();
4215        printk("-------------------------------\n");
4216        printk("%s:%d %s!\n", file, line, s);
4217        printk("\nother info that might help us debug this:\n\n");
4218        printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4219               !rcu_lockdep_current_cpu_online()
4220                        ? "RCU used illegally from offline CPU!\n"
4221                        : rcu_is_cpu_idle()
4222                                ? "RCU used illegally from idle CPU!\n"
4223                                : "",
4224               rcu_scheduler_active, debug_locks);
4225
4226        /*
4227         * If a CPU is in the RCU-free window in idle (ie: in the section
4228         * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4229         * considers that CPU to be in an "extended quiescent state",
4230         * which means that RCU will be completely ignoring that CPU.
4231         * Therefore, rcu_read_lock() and friends have absolutely no
4232         * effect on a CPU running in that state. In other words, even if
4233         * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4234         * delete data structures out from under it.  RCU really has no
4235         * choice here: we need to keep an RCU-free window in idle where
4236         * the CPU may possibly enter into low power mode. This way we can
4237         * notice an extended quiescent state to other CPUs that started a grace
4238         * period. Otherwise we would delay any grace period as long as we run
4239         * in the idle task.
4240         *
4241         * So complain bitterly if someone does call rcu_read_lock(),
4242         * rcu_read_lock_bh() and so on from extended quiescent states.
4243         */
4244        if (rcu_is_cpu_idle())
4245                printk("RCU used illegally from extended quiescent state!\n");
4246
4247        lockdep_print_held_locks(curr);
4248        printk("\nstack backtrace:\n");
4249        dump_stack();
4250}
4251EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
4252
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.