/*
   * kernel/lockdep.c
   *
   * Runtime locking correctness validator
   *
   * Started by Ingo Molnar:
   *

   *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>

   *
   * this code maps all the lock dependencies as they occur in a live kernel
   * and will warn about the following classes of locking bugs:
   *
   * - lock inversion scenarios
   * - circular lock dependencies
   * - hardirq/softirq safe/unsafe locking bugs
   *
   * Bugs are reported even if the current locking scenario does not cause
   * any deadlock at this point.
   *
   * I.e. if anytime in the past two locks were taken in a different order,
   * even if it happened for another task, even if those were different
   * locks (but of the same class as this lock), this code will detect it.
   *
   * Thanks to Arjan van de Ven for coming up with the initial idea of
   * mapping lock dependencies runtime.
   */
  #include <linux/mutex.h>
  #include <linux/sched.h>
  #include <linux/delay.h>
  #include <linux/module.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/spinlock.h>
  #include <linux/kallsyms.h>
  #include <linux/interrupt.h>
  #include <linux/stacktrace.h>
  #include <linux/debug_locks.h>
  #include <linux/irqflags.h>

  #include <linux/utsname.h>

  #include <linux/hash.h>

  #include <linux/ftrace.h>

  
  #include <asm/sections.h>
  
  #include "lockdep_internals.h"

  #ifdef CONFIG_PROVE_LOCKING
  int prove_locking = 1;
  module_param(prove_locking, int, 0644);
  #else
  #define prove_locking 0
  #endif
  
  #ifdef CONFIG_LOCK_STAT
  int lock_stat = 1;
  module_param(lock_stat, int, 0644);
  #else
  #define lock_stat 0
  #endif

  /*

   * lockdep_lock: protects the lockdep graph, the hashes and the
   *               class/list/hash allocators.

   *
   * This is one of the rare exceptions where it's justified
   * to use a raw spinlock - we really dont want the spinlock

   * code to recurse back into the lockdep code...

   */

  static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
  
  static int graph_lock(void)
  {
  	__raw_spin_lock(&lockdep_lock);
  	/*
  	 * Make sure that if another CPU detected a bug while
  	 * walking the graph we dont change it (while the other
  	 * CPU is busy printing out stuff with the graph lock
  	 * dropped already)
  	 */
  	if (!debug_locks) {
  		__raw_spin_unlock(&lockdep_lock);
  		return 0;
  	}

  	/* prevent any recursions within lockdep from causing deadlocks */
  	current->lockdep_recursion++;

  	return 1;
  }
  
  static inline int graph_unlock(void)
  {

  	if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
  		return DEBUG_LOCKS_WARN_ON(1);

  	current->lockdep_recursion--;

  	__raw_spin_unlock(&lockdep_lock);
  	return 0;
  }
  
  /*
   * Turn lock debugging off and return with 0 if it was off already,
   * and also release the graph lock:
   */
  static inline int debug_locks_off_graph_unlock(void)
  {
  	int ret = debug_locks_off();
  
  	__raw_spin_unlock(&lockdep_lock);
  
  	return ret;
  }

  
  static int lockdep_initialized;
  
  unsigned long nr_list_entries;
  static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];

  /*
   * All data structures here are protected by the global debug_lock.
   *
   * Mutex key structs only get allocated, once during bootup, and never
   * get freed - this significantly simplifies the debugging code.
   */
  unsigned long nr_lock_classes;
  static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];

  static inline struct lock_class *hlock_class(struct held_lock *hlock)
  {
  	if (!hlock->class_idx) {
  		DEBUG_LOCKS_WARN_ON(1);
  		return NULL;
  	}
  	return lock_classes + hlock->class_idx - 1;
  }

  #ifdef CONFIG_LOCK_STAT
  static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
  
  static int lock_contention_point(struct lock_class *class, unsigned long ip)
  {
  	int i;
  
  	for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
  		if (class->contention_point[i] == 0) {
  			class->contention_point[i] = ip;
  			break;
  		}
  		if (class->contention_point[i] == ip)
  			break;
  	}
  
  	return i;
  }
  
  static void lock_time_inc(struct lock_time *lt, s64 time)
  {
  	if (time > lt->max)
  		lt->max = time;
  
  	if (time < lt->min || !lt->min)
  		lt->min = time;
  
  	lt->total += time;
  	lt->nr++;
  }

  static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
  {
  	dst->min += src->min;
  	dst->max += src->max;
  	dst->total += src->total;
  	dst->nr += src->nr;
  }
  
  struct lock_class_stats lock_stats(struct lock_class *class)
  {
  	struct lock_class_stats stats;
  	int cpu, i;
  
  	memset(&stats, 0, sizeof(struct lock_class_stats));
  	for_each_possible_cpu(cpu) {
  		struct lock_class_stats *pcs =
  			&per_cpu(lock_stats, cpu)[class - lock_classes];
  
  		for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
  			stats.contention_point[i] += pcs->contention_point[i];
  
  		lock_time_add(&pcs->read_waittime, &stats.read_waittime);
  		lock_time_add(&pcs->write_waittime, &stats.write_waittime);
  
  		lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
  		lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);

  
  		for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
  			stats.bounces[i] += pcs->bounces[i];

  	}
  
  	return stats;
  }
  
  void clear_lock_stats(struct lock_class *class)
  {
  	int cpu;
  
  	for_each_possible_cpu(cpu) {
  		struct lock_class_stats *cpu_stats =
  			&per_cpu(lock_stats, cpu)[class - lock_classes];
  
  		memset(cpu_stats, 0, sizeof(struct lock_class_stats));
  	}
  	memset(class->contention_point, 0, sizeof(class->contention_point));
  }

  static struct lock_class_stats *get_lock_stats(struct lock_class *class)
  {
  	return &get_cpu_var(lock_stats)[class - lock_classes];
  }
  
  static void put_lock_stats(struct lock_class_stats *stats)
  {
  	put_cpu_var(lock_stats);
  }
  
  static void lock_release_holdtime(struct held_lock *hlock)
  {
  	struct lock_class_stats *stats;
  	s64 holdtime;
  
  	if (!lock_stat)
  		return;
  
  	holdtime = sched_clock() - hlock->holdtime_stamp;

  	stats = get_lock_stats(hlock_class(hlock));

  	if (hlock->read)
  		lock_time_inc(&stats->read_holdtime, holdtime);
  	else
  		lock_time_inc(&stats->write_holdtime, holdtime);
  	put_lock_stats(stats);
  }
  #else
  static inline void lock_release_holdtime(struct held_lock *hlock)
  {
  }
  #endif

  /*
   * We keep a global list of all lock classes. The list only grows,
   * never shrinks. The list is only accessed with the lockdep
   * spinlock lock held.
   */
  LIST_HEAD(all_lock_classes);
  
  /*
   * The lockdep classes are in a hash-table as well, for fast lookup:
   */
  #define CLASSHASH_BITS		(MAX_LOCKDEP_KEYS_BITS - 1)
  #define CLASSHASH_SIZE		(1UL << CLASSHASH_BITS)

  #define __classhashfn(key)	hash_long((unsigned long)key, CLASSHASH_BITS)

  #define classhashentry(key)	(classhash_table + __classhashfn((key)))
  
  static struct list_head classhash_table[CLASSHASH_SIZE];

  /*
   * We put the lock dependency chains into a hash-table as well, to cache
   * their existence:
   */
  #define CHAINHASH_BITS		(MAX_LOCKDEP_CHAINS_BITS-1)
  #define CHAINHASH_SIZE		(1UL << CHAINHASH_BITS)

  #define __chainhashfn(chain)	hash_long(chain, CHAINHASH_BITS)

  #define chainhashentry(chain)	(chainhash_table + __chainhashfn((chain)))
  
  static struct list_head chainhash_table[CHAINHASH_SIZE];
  
  /*
   * The hash key of the lock dependency chains is a hash itself too:
   * it's a hash of all locks taken up to that lock, including that lock.
   * It's a 64-bit hash, because it's important for the keys to be
   * unique.
   */
  #define iterate_chain_key(key1, key2) \

  	(((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
  	((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \

  	(key2))

  void lockdep_off(void)

  {
  	current->lockdep_recursion++;
  }
  
  EXPORT_SYMBOL(lockdep_off);

  void lockdep_on(void)

  {
  	current->lockdep_recursion--;
  }
  
  EXPORT_SYMBOL(lockdep_on);

  /*
   * Debugging switches:
   */
  
  #define VERBOSE			0

  #define VERY_VERBOSE		0

  
  #if VERBOSE
  # define HARDIRQ_VERBOSE	1
  # define SOFTIRQ_VERBOSE	1
  #else
  # define HARDIRQ_VERBOSE	0
  # define SOFTIRQ_VERBOSE	0
  #endif
  
  #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
  /*
   * Quick filtering for interesting events:
   */
  static int class_filter(struct lock_class *class)
  {

  #if 0
  	/* Example */

  	if (class->name_version == 1 &&

  			!strcmp(class->name, "lockname"))

  		return 1;
  	if (class->name_version == 1 &&

  			!strcmp(class->name, "&struct->lockfield"))

  		return 1;

  #endif

  	/* Filter everything else. 1 would be to allow everything else */
  	return 0;

  }
  #endif
  
  static int verbose(struct lock_class *class)
  {
  #if VERBOSE
  	return class_filter(class);
  #endif
  	return 0;
  }

  /*
   * Stack-trace: tightly packed array of stack backtrace

   * addresses. Protected by the graph_lock.

   */
  unsigned long nr_stack_trace_entries;
  static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
  
  static int save_trace(struct stack_trace *trace)
  {
  	trace->nr_entries = 0;
  	trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
  	trace->entries = stack_trace + nr_stack_trace_entries;

  	trace->skip = 3;

  	save_stack_trace(trace);

  
  	trace->max_entries = trace->nr_entries;
  
  	nr_stack_trace_entries += trace->nr_entries;

  
  	if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {

  		if (!debug_locks_off_graph_unlock())
  			return 0;
  
  		printk("BUG: MAX_STACK_TRACE_ENTRIES too low!
  ");
  		printk("turning off the locking correctness validator.
  ");
  		dump_stack();

  		return 0;
  	}
  
  	return 1;
  }
  
  unsigned int nr_hardirq_chains;
  unsigned int nr_softirq_chains;
  unsigned int nr_process_chains;
  unsigned int max_lockdep_depth;
  unsigned int max_recursion_depth;

  static unsigned int lockdep_dependency_gen_id;
  
  static bool lockdep_dependency_visit(struct lock_class *source,
  				     unsigned int depth)
  {
  	if (!depth)
  		lockdep_dependency_gen_id++;
  	if (source->dep_gen_id == lockdep_dependency_gen_id)
  		return true;
  	source->dep_gen_id = lockdep_dependency_gen_id;
  	return false;
  }

  #ifdef CONFIG_DEBUG_LOCKDEP
  /*
   * We cannot printk in early bootup code. Not even early_printk()
   * might work. So we mark any initialization errors and printk
   * about it later on, in lockdep_info().
   */
  static int lockdep_init_error;

  static unsigned long lockdep_init_trace_data[20];
  static struct stack_trace lockdep_init_trace = {
  	.max_entries = ARRAY_SIZE(lockdep_init_trace_data),
  	.entries = lockdep_init_trace_data,
  };

  
  /*
   * Various lockdep statistics:
   */
  atomic_t chain_lookup_hits;
  atomic_t chain_lookup_misses;
  atomic_t hardirqs_on_events;
  atomic_t hardirqs_off_events;
  atomic_t redundant_hardirqs_on;
  atomic_t redundant_hardirqs_off;
  atomic_t softirqs_on_events;
  atomic_t softirqs_off_events;
  atomic_t redundant_softirqs_on;
  atomic_t redundant_softirqs_off;
  atomic_t nr_unused_locks;
  atomic_t nr_cyclic_checks;
  atomic_t nr_cyclic_check_recursions;
  atomic_t nr_find_usage_forwards_checks;
  atomic_t nr_find_usage_forwards_recursions;
  atomic_t nr_find_usage_backwards_checks;
  atomic_t nr_find_usage_backwards_recursions;
  # define debug_atomic_inc(ptr)		atomic_inc(ptr)
  # define debug_atomic_dec(ptr)		atomic_dec(ptr)
  # define debug_atomic_read(ptr)		atomic_read(ptr)
  #else
  # define debug_atomic_inc(ptr)		do { } while (0)
  # define debug_atomic_dec(ptr)		do { } while (0)
  # define debug_atomic_read(ptr)		0
  #endif
  
  /*
   * Locking printouts:
   */
  
  static const char *usage_str[] =
  {
  	[LOCK_USED] =			"initial-use ",
  	[LOCK_USED_IN_HARDIRQ] =	"in-hardirq-W",
  	[LOCK_USED_IN_SOFTIRQ] =	"in-softirq-W",
  	[LOCK_ENABLED_SOFTIRQS] =	"softirq-on-W",
  	[LOCK_ENABLED_HARDIRQS] =	"hardirq-on-W",
  	[LOCK_USED_IN_HARDIRQ_READ] =	"in-hardirq-R",
  	[LOCK_USED_IN_SOFTIRQ_READ] =	"in-softirq-R",
  	[LOCK_ENABLED_SOFTIRQS_READ] =	"softirq-on-R",
  	[LOCK_ENABLED_HARDIRQS_READ] =	"hardirq-on-R",
  };
  
  const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
  {

  	return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);

  }
  
  void
  get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
  {
  	*c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
  
  	if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
  		*c1 = '+';
  	else
  		if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
  			*c1 = '-';
  
  	if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
  		*c2 = '+';
  	else
  		if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
  			*c2 = '-';
  
  	if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
  		*c3 = '-';
  	if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
  		*c3 = '+';
  		if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
  			*c3 = '?';
  	}
  
  	if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
  		*c4 = '-';
  	if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
  		*c4 = '+';
  		if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
  			*c4 = '?';
  	}
  }
  
  static void print_lock_name(struct lock_class *class)
  {

  	char str[KSYM_NAME_LEN], c1, c2, c3, c4;

  	const char *name;
  
  	get_usage_chars(class, &c1, &c2, &c3, &c4);
  
  	name = class->name;
  	if (!name) {
  		name = __get_key_name(class->key, str);
  		printk(" (%s", name);
  	} else {
  		printk(" (%s", name);
  		if (class->name_version > 1)
  			printk("#%d", class->name_version);
  		if (class->subclass)
  			printk("/%d", class->subclass);
  	}
  	printk("){%c%c%c%c}", c1, c2, c3, c4);
  }
  
  static void print_lockdep_cache(struct lockdep_map *lock)
  {
  	const char *name;

  	char str[KSYM_NAME_LEN];

  
  	name = lock->name;
  	if (!name)
  		name = __get_key_name(lock->key->subkeys, str);
  
  	printk("%s", name);
  }
  
  static void print_lock(struct held_lock *hlock)
  {

  	print_lock_name(hlock_class(hlock));

  	printk(", at: ");
  	print_ip_sym(hlock->acquire_ip);
  }
  
  static void lockdep_print_held_locks(struct task_struct *curr)
  {
  	int i, depth = curr->lockdep_depth;
  
  	if (!depth) {

  		printk("no locks held by %s/%d.
  ", curr->comm, task_pid_nr(curr));

  		return;
  	}
  	printk("%d lock%s held by %s/%d:
  ",

  		depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));

  
  	for (i = 0; i < depth; i++) {
  		printk(" #%d: ", i);
  		print_lock(curr->held_locks + i);
  	}
  }

  
  static void print_lock_class_header(struct lock_class *class, int depth)
  {
  	int bit;

  	printk("%*s->", depth, "");

  	print_lock_name(class);
  	printk(" ops: %lu", class->ops);
  	printk(" {
  ");
  
  	for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
  		if (class->usage_mask & (1 << bit)) {
  			int len = depth;

  			len += printk("%*s   %s", depth, "", usage_str[bit]);

  			len += printk(" at:
  ");
  			print_stack_trace(class->usage_traces + bit, len);
  		}
  	}

  	printk("%*s }
  ", depth, "");

  	printk("%*s ... key      at: ",depth,"");

  	print_ip_sym((unsigned long)class->key);
  }
  
  /*
   * printk all lock dependencies starting at <entry>:
   */
  static void print_lock_dependencies(struct lock_class *class, int depth)
  {
  	struct lock_list *entry;

  	if (lockdep_dependency_visit(class, depth))
  		return;

  	if (DEBUG_LOCKS_WARN_ON(depth >= 20))
  		return;
  
  	print_lock_class_header(class, depth);
  
  	list_for_each_entry(entry, &class->locks_after, entry) {

  		if (DEBUG_LOCKS_WARN_ON(!entry->class))
  			return;

  		print_lock_dependencies(entry->class, depth + 1);

  		printk("%*s ... acquired at:
  ",depth,"");

  		print_stack_trace(&entry->trace, 2);
  		printk("
  ");
  	}
  }

  static void print_kernel_version(void)
  {
  	printk("%s %.*s
  ", init_utsname()->release,
  		(int)strcspn(init_utsname()->version, " "),
  		init_utsname()->version);
  }
  
  static int very_verbose(struct lock_class *class)
  {
  #if VERY_VERBOSE
  	return class_filter(class);
  #endif
  	return 0;
  }

  /*

   * Is this the address of a static object:

   */

  static int static_obj(void *obj)

  {

  	unsigned long start = (unsigned long) &_stext,
  		      end   = (unsigned long) &_end,
  		      addr  = (unsigned long) obj;
  #ifdef CONFIG_SMP
  	int i;
  #endif

  	/*

  	 * static variable?

  	 */

  	if ((addr >= start) && (addr < end))
  		return 1;

  #ifdef CONFIG_SMP

  	/*

  	 * percpu var?

  	 */

  	for_each_possible_cpu(i) {
  		start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
  		end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
  					+ per_cpu_offset(i);

  		if ((addr >= start) && (addr < end))
  			return 1;
  	}

  #endif

  	/*
  	 * module var?
  	 */
  	return is_module_address(addr);

  }

  /*

   * To make lock name printouts unique, we calculate a unique
   * class->name_version generation counter:

   */

  static int count_matching_names(struct lock_class *new_class)

  {

  	struct lock_class *class;
  	int count = 0;

  	if (!new_class->name)

  		return 0;

  	list_for_each_entry(class, &all_lock_classes, lock_entry) {
  		if (new_class->key - new_class->subclass == class->key)
  			return class->name_version;
  		if (class->name && !strcmp(class->name, new_class->name))
  			count = max(count, class->name_version);
  	}

  	return count + 1;

  }

  /*
   * Register a lock's class in the hash-table, if the class is not present
   * yet. Otherwise we look it up. We cache the result in the lock object
   * itself, so actual lookup of the hash should be once per lock object.
   */
  static inline struct lock_class *
  look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)

  {

  	struct lockdep_subclass_key *key;
  	struct list_head *hash_head;
  	struct lock_class *class;

  #ifdef CONFIG_DEBUG_LOCKDEP
  	/*
  	 * If the architecture calls into lockdep before initializing
  	 * the hashes then we'll warn about it later. (we cannot printk
  	 * right now)
  	 */
  	if (unlikely(!lockdep_initialized)) {
  		lockdep_init();
  		lockdep_init_error = 1;

  		save_stack_trace(&lockdep_init_trace);

  	}
  #endif

  	/*
  	 * Static locks do not have their class-keys yet - for them the key
  	 * is the lock object itself:
  	 */
  	if (unlikely(!lock->key))
  		lock->key = (void *)lock;

  	/*
  	 * NOTE: the class-key must be unique. For dynamic locks, a static
  	 * lock_class_key variable is passed in through the mutex_init()
  	 * (or spin_lock_init()) call - which acts as the key. For static
  	 * locks we use the lock object itself as the key.
  	 */

  	BUILD_BUG_ON(sizeof(struct lock_class_key) >
  			sizeof(struct lockdep_map));

  	key = lock->key->subkeys + subclass;

  	hash_head = classhashentry(key);

  	/*
  	 * We can walk the hash lockfree, because the hash only
  	 * grows, and we are careful when adding entries to the end:
  	 */

  	list_for_each_entry(class, hash_head, hash_entry) {
  		if (class->key == key) {
  			WARN_ON_ONCE(class->name != lock->name);

  			return class;

  		}
  	}

  	return NULL;

  }
  
  /*

   * Register a lock's class in the hash-table, if the class is not present
   * yet. Otherwise we look it up. We cache the result in the lock object
   * itself, so actual lookup of the hash should be once per lock object.

   */

  static inline struct lock_class *
  register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)

  {

  	struct lockdep_subclass_key *key;
  	struct list_head *hash_head;
  	struct lock_class *class;
  	unsigned long flags;
  
  	class = look_up_lock_class(lock, subclass);
  	if (likely(class))
  		return class;
  
  	/*
  	 * Debug-check: all keys must be persistent!
   	 */
  	if (!static_obj(lock->key)) {
  		debug_locks_off();
  		printk("INFO: trying to register non-static key.
  ");
  		printk("the code is fine but needs lockdep annotation.
  ");
  		printk("turning off the locking correctness validator.
  ");
  		dump_stack();
  
  		return NULL;
  	}
  
  	key = lock->key->subkeys + subclass;
  	hash_head = classhashentry(key);
  
  	raw_local_irq_save(flags);
  	if (!graph_lock()) {
  		raw_local_irq_restore(flags);
  		return NULL;
  	}
  	/*
  	 * We have to do the hash-walk again, to avoid races
  	 * with another CPU:
  	 */
  	list_for_each_entry(class, hash_head, hash_entry)
  		if (class->key == key)
  			goto out_unlock_set;
  	/*
  	 * Allocate a new key from the static array, and add it to
  	 * the hash:
  	 */
  	if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
  		if (!debug_locks_off_graph_unlock()) {
  			raw_local_irq_restore(flags);
  			return NULL;
  		}
  		raw_local_irq_restore(flags);
  
  		printk("BUG: MAX_LOCKDEP_KEYS too low!
  ");
  		printk("turning off the locking correctness validator.
  ");
  		return NULL;
  	}
  	class = lock_classes + nr_lock_classes++;
  	debug_atomic_inc(&nr_unused_locks);
  	class->key = key;
  	class->name = lock->name;
  	class->subclass = subclass;
  	INIT_LIST_HEAD(&class->lock_entry);
  	INIT_LIST_HEAD(&class->locks_before);
  	INIT_LIST_HEAD(&class->locks_after);
  	class->name_version = count_matching_names(class);
  	/*
  	 * We use RCU's safe list-add method to make
  	 * parallel walking of the hash-list safe:
  	 */
  	list_add_tail_rcu(&class->hash_entry, hash_head);

  	/*
  	 * Add it to the global list of classes:
  	 */
  	list_add_tail_rcu(&class->lock_entry, &all_lock_classes);

  
  	if (verbose(class)) {
  		graph_unlock();
  		raw_local_irq_restore(flags);
  
  		printk("
  new class %p: %s", class->key, class->name);
  		if (class->name_version > 1)
  			printk("#%d", class->name_version);
  		printk("
  ");
  		dump_stack();
  
  		raw_local_irq_save(flags);
  		if (!graph_lock()) {
  			raw_local_irq_restore(flags);
  			return NULL;
  		}
  	}
  out_unlock_set:
  	graph_unlock();
  	raw_local_irq_restore(flags);
  
  	if (!subclass || force)
  		lock->class_cache = class;
  
  	if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
  		return NULL;
  
  	return class;
  }
  
  #ifdef CONFIG_PROVE_LOCKING
  /*
   * Allocate a lockdep entry. (assumes the graph_lock held, returns
   * with NULL on failure)
   */
  static struct lock_list *alloc_list_entry(void)
  {
  	if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
  		if (!debug_locks_off_graph_unlock())
  			return NULL;
  
  		printk("BUG: MAX_LOCKDEP_ENTRIES too low!
  ");
  		printk("turning off the locking correctness validator.
  ");
  		return NULL;
  	}
  	return list_entries + nr_list_entries++;
  }
  
  /*
   * Add a new dependency to the head of the list:
   */
  static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
  			    struct list_head *head, unsigned long ip, int distance)
  {
  	struct lock_list *entry;
  	/*
  	 * Lock not present yet - get a new dependency struct and
  	 * add it to the list:
  	 */
  	entry = alloc_list_entry();
  	if (!entry)
  		return 0;

  	if (!save_trace(&entry->trace))
  		return 0;

  	entry->class = this;
  	entry->distance = distance;

  	/*
  	 * Since we never remove from the dependency list, the list can
  	 * be walked lockless by other CPUs, it's only allocation
  	 * that must be protected by the spinlock. But this also means
  	 * we must make new entries visible only once writes to the
  	 * entry become visible - hence the RCU op:
  	 */
  	list_add_tail_rcu(&entry->entry, head);
  
  	return 1;
  }
  
  /*
   * Recursive, forwards-direction lock-dependency checking, used for
   * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
   * checking.
   *
   * (to keep the stackframe of the recursive functions small we
   *  use these global variables, and we also mark various helper
   *  functions as noinline.)
   */
  static struct held_lock *check_source, *check_target;
  
  /*
   * Print a dependency chain entry (this is only done when a deadlock
   * has been detected):
   */
  static noinline int
  print_circular_bug_entry(struct lock_list *target, unsigned int depth)
  {
  	if (debug_locks_silent)
  		return 0;
  	printk("
  -> #%u", depth);
  	print_lock_name(target->class);
  	printk(":
  ");
  	print_stack_trace(&target->trace, 6);
  
  	return 0;
  }
  
  /*
   * When a circular dependency is detected, print the
   * header first:
   */
  static noinline int
  print_circular_bug_header(struct lock_list *entry, unsigned int depth)
  {
  	struct task_struct *curr = current;
  
  	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
  		return 0;
  
  	printk("
  =======================================================
  ");
  	printk(  "[ INFO: possible circular locking dependency detected ]
  ");
  	print_kernel_version();
  	printk(  "-------------------------------------------------------
  ");
  	printk("%s/%d is trying to acquire lock:
  ",

  		curr->comm, task_pid_nr(curr));

  	print_lock(check_source);
  	printk("
  but task is already holding lock:
  ");
  	print_lock(check_target);
  	printk("
  which lock already depends on the new lock.
  
  ");
  	printk("
  the existing dependency chain (in reverse order) is:
  ");
  
  	print_circular_bug_entry(entry, depth);
  
  	return 0;
  }
  
  static noinline int print_circular_bug_tail(void)
  {
  	struct task_struct *curr = current;
  	struct lock_list this;
  
  	if (debug_locks_silent)
  		return 0;

  	this.class = hlock_class(check_source);

  	if (!save_trace(&this.trace))
  		return 0;
  
  	print_circular_bug_entry(&this, 0);
  
  	printk("
  other info that might help us debug this:
  
  ");
  	lockdep_print_held_locks(curr);
  
  	printk("
  stack backtrace:
  ");
  	dump_stack();
  
  	return 0;
  }
  
  #define RECURSION_LIMIT 40
  
  static int noinline print_infinite_recursion_bug(void)
  {
  	if (!debug_locks_off_graph_unlock())
  		return 0;
  
  	WARN_ON(1);
  
  	return 0;
  }

  unsigned long __lockdep_count_forward_deps(struct lock_class *class,
  					   unsigned int depth)
  {
  	struct lock_list *entry;
  	unsigned long ret = 1;
  
  	if (lockdep_dependency_visit(class, depth))
  		return 0;
  
  	/*
  	 * Recurse this class's dependency list:
  	 */
  	list_for_each_entry(entry, &class->locks_after, entry)
  		ret += __lockdep_count_forward_deps(entry->class, depth + 1);
  
  	return ret;
  }
  
  unsigned long lockdep_count_forward_deps(struct lock_class *class)
  {
  	unsigned long ret, flags;
  
  	local_irq_save(flags);
  	__raw_spin_lock(&lockdep_lock);
  	ret = __lockdep_count_forward_deps(class, 0);
  	__raw_spin_unlock(&lockdep_lock);
  	local_irq_restore(flags);
  
  	return ret;
  }
  
  unsigned long __lockdep_count_backward_deps(struct lock_class *class,
  					    unsigned int depth)
  {
  	struct lock_list *entry;
  	unsigned long ret = 1;
  
  	if (lockdep_dependency_visit(class, depth))
  		return 0;
  	/*
  	 * Recurse this class's dependency list:
  	 */
  	list_for_each_entry(entry, &class->locks_before, entry)
  		ret += __lockdep_count_backward_deps(entry->class, depth + 1);
  
  	return ret;
  }
  
  unsigned long lockdep_count_backward_deps(struct lock_class *class)
  {
  	unsigned long ret, flags;
  
  	local_irq_save(flags);
  	__raw_spin_lock(&lockdep_lock);
  	ret = __lockdep_count_backward_deps(class, 0);
  	__raw_spin_unlock(&lockdep_lock);
  	local_irq_restore(flags);
  
  	return ret;
  }

  /*
   * Prove that the dependency graph starting at <entry> can not
   * lead to <target>. Print an error and return 0 if it does.
   */
  static noinline int
  check_noncircular(struct lock_class *source, unsigned int depth)
  {
  	struct lock_list *entry;

  	if (lockdep_dependency_visit(source, depth))
  		return 1;

  	debug_atomic_inc(&nr_cyclic_check_recursions);
  	if (depth > max_recursion_depth)

  		max_recursion_depth = depth;

  	if (depth >= RECURSION_LIMIT)

  		return print_infinite_recursion_bug();
  	/*
  	 * Check this lock's dependency list:
  	 */
  	list_for_each_entry(entry, &source->locks_after, entry) {

  		if (entry->class == hlock_class(check_target))

  			return print_circular_bug_header(entry, depth+1);
  		debug_atomic_inc(&nr_cyclic_checks);
  		if (!check_noncircular(entry->class, depth+1))
  			return print_circular_bug_entry(entry, depth+1);
  	}
  	return 1;
  }

  #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)

  /*
   * Forwards and backwards subgraph searching, for the purposes of
   * proving that two subgraphs can be connected by a new dependency
   * without creating any illegal irq-safe -> irq-unsafe lock dependency.
   */
  static enum lock_usage_bit find_usage_bit;
  static struct lock_class *forwards_match, *backwards_match;
  
  /*
   * Find a node in the forwards-direction dependency sub-graph starting
   * at <source> that matches <find_usage_bit>.
   *
   * Return 2 if such a node exists in the subgraph, and put that node
   * into <forwards_match>.
   *
   * Return 1 otherwise and keep <forwards_match> unchanged.
   * Return 0 on error.
   */
  static noinline int
  find_usage_forwards(struct lock_class *source, unsigned int depth)
  {
  	struct lock_list *entry;
  	int ret;

  	if (lockdep_dependency_visit(source, depth))
  		return 1;

  	if (depth > max_recursion_depth)
  		max_recursion_depth = depth;

  	if (depth >= RECURSION_LIMIT)

  		return print_infinite_recursion_bug();
  
  	debug_atomic_inc(&nr_find_usage_forwards_checks);
  	if (source->usage_mask & (1 << find_usage_bit)) {
  		forwards_match = source;
  		return 2;
  	}
  
  	/*
  	 * Check this lock's dependency list:
  	 */
  	list_for_each_entry(entry, &source->locks_after, entry) {
  		debug_atomic_inc(&nr_find_usage_forwards_recursions);
  		ret = find_usage_forwards(entry->class, depth+1);
  		if (ret == 2 || ret == 0)
  			return ret;
  	}
  	return 1;
  }
  
  /*
   * Find a node in the backwards-direction dependency sub-graph starting
   * at <source> that matches <find_usage_bit>.
   *
   * Return 2 if such a node exists in the subgraph, and put that node
   * into <backwards_match>.
   *
   * Return 1 otherwise and keep <backwards_match> unchanged.
   * Return 0 on error.
   */

  static noinline int

  find_usage_backwards(struct lock_class *source, unsigned int depth)
  {
  	struct lock_list *entry;
  	int ret;

  	if (lockdep_dependency_visit(source, depth))
  		return 1;

  	if (!__raw_spin_is_locked(&lockdep_lock))
  		return DEBUG_LOCKS_WARN_ON(1);

  	if (depth > max_recursion_depth)
  		max_recursion_depth = depth;

  	if (depth >= RECURSION_LIMIT)

  		return print_infinite_recursion_bug();
  
  	debug_atomic_inc(&nr_find_usage_backwards_checks);
  	if (source->usage_mask & (1 << find_usage_bit)) {
  		backwards_match = source;
  		return 2;
  	}

  	if (!source && debug_locks_off_graph_unlock()) {
  		WARN_ON(1);
  		return 0;
  	}

  	/*
  	 * Check this lock's dependency list:
  	 */
  	list_for_each_entry(entry, &source->locks_before, entry) {
  		debug_atomic_inc(&nr_find_usage_backwards_recursions);
  		ret = find_usage_backwards(entry->class, depth+1);
  		if (ret == 2 || ret == 0)
  			return ret;
  	}
  	return 1;
  }
  
  static int
  print_bad_irq_dependency(struct task_struct *curr,
  			 struct held_lock *prev,
  			 struct held_lock *next,
  			 enum lock_usage_bit bit1,
  			 enum lock_usage_bit bit2,
  			 const char *irqclass)
  {

  	if (!debug_locks_off_graph_unlock() || debug_locks_silent)

  		return 0;
  
  	printk("
  ======================================================
  ");
  	printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]
  ",
  		irqclass, irqclass);

  	print_kernel_version();

  	printk(  "------------------------------------------------------
  ");
  	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:
  ",

  		curr->comm, task_pid_nr(curr),

  		curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
  		curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
  		curr->hardirqs_enabled,
  		curr->softirqs_enabled);
  	print_lock(next);
  
  	printk("
  and this task is already holding:
  ");
  	print_lock(prev);
  	printk("which would create a new lock dependency:
  ");

  	print_lock_name(hlock_class(prev));

  	printk(" ->");

  	print_lock_name(hlock_class(next));

  	printk("
  ");
  
  	printk("
  but this new dependency connects a %s-irq-safe lock:
  ",
  		irqclass);
  	print_lock_name(backwards_match);
  	printk("
  ... which became %s-irq-safe at:
  ", irqclass);
  
  	print_stack_trace(backwards_match->usage_traces + bit1, 1);
  
  	printk("
  to a %s-irq-unsafe lock:
  ", irqclass);
  	print_lock_name(forwards_match);
  	printk("
  ... which became %s-irq-unsafe at:
  ", irqclass);
  	printk("...");
  
  	print_stack_trace(forwards_match->usage_traces + bit2, 1);
  
  	printk("
  other info that might help us debug this:
  
  ");
  	lockdep_print_held_locks(curr);
  
  	printk("
  the %s-irq-safe lock's dependencies:
  ", irqclass);
  	print_lock_dependencies(backwards_match, 0);
  
  	printk("
  the %s-irq-unsafe lock's dependencies:
  ", irqclass);
  	print_lock_dependencies(forwards_match, 0);
  
  	printk("
  stack backtrace:
  ");
  	dump_stack();
  
  	return 0;
  }
  
  static int
  check_usage(struct task_struct *curr, struct held_lock *prev,
  	    struct held_lock *next, enum lock_usage_bit bit_backwards,
  	    enum lock_usage_bit bit_forwards, const char *irqclass)
  {
  	int ret;
  
  	find_usage_bit = bit_backwards;
  	/* fills in <backwards_match> */

  	ret = find_usage_backwards(hlock_class(prev), 0);

  	if (!ret || ret == 1)
  		return ret;
  
  	find_usage_bit = bit_forwards;

  	ret = find_usage_forwards(hlock_class(next), 0);

  	if (!ret || ret == 1)
  		return ret;
  	/* ret == 2 */
  	return print_bad_irq_dependency(curr, prev, next,
  			bit_backwards, bit_forwards, irqclass);
  }

  static int
  check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
  		struct held_lock *next)
  {
  	/*
  	 * Prove that the new dependency does not connect a hardirq-safe
  	 * lock with a hardirq-unsafe lock - to achieve this we search
  	 * the backwards-subgraph starting at <prev>, and the
  	 * forwards-subgraph starting at <next>:
  	 */
  	if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
  					LOCK_ENABLED_HARDIRQS, "hard"))
  		return 0;
  
  	/*
  	 * Prove that the new dependency does not connect a hardirq-safe-read
  	 * lock with a hardirq-unsafe lock - to achieve this we search
  	 * the backwards-subgraph starting at <prev>, and the
  	 * forwards-subgraph starting at <next>:
  	 */
  	if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
  					LOCK_ENABLED_HARDIRQS, "hard-read"))
  		return 0;
  
  	/*
  	 * Prove that the new dependency does not connect a softirq-safe
  	 * lock with a softirq-unsafe lock - to achieve this we search
  	 * the backwards-subgraph starting at <prev>, and the
  	 * forwards-subgraph starting at <next>:
  	 */
  	if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
  					LOCK_ENABLED_SOFTIRQS, "soft"))
  		return 0;
  	/*
  	 * Prove that the new dependency does not connect a softirq-safe-read
  	 * lock with a softirq-unsafe lock - to achieve this we search
  	 * the backwards-subgraph starting at <prev>, and the
  	 * forwards-subgraph starting at <next>:
  	 */
  	if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
  					LOCK_ENABLED_SOFTIRQS, "soft"))
  		return 0;
  
  	return 1;
  }
  
  static void inc_chains(void)
  {
  	if (current->hardirq_context)
  		nr_hardirq_chains++;
  	else {
  		if (current->softirq_context)
  			nr_softirq_chains++;
  		else
  			nr_process_chains++;
  	}
  }
  
  #else
  
  static inline int
  check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
  		struct held_lock *next)
  {
  	return 1;
  }
  
  static inline void inc_chains(void)
  {
  	nr_process_chains++;
  }

  #endif
  
  static int
  print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
  		   struct held_lock *next)
  {

  	if (!debug_locks_off_graph_unlock() || debug_locks_silent)

  		return 0;
  
  	printk("
  =============================================
  ");
  	printk(  "[ INFO: possible recursive locking detected ]
  ");

  	print_kernel_version();

  	printk(  "---------------------------------------------
  ");
  	printk("%s/%d is trying to acquire lock:
  ",

  		curr->comm, task_pid_nr(curr));

  	print_lock(next);
  	printk("
  but task is already holding lock:
  ");
  	print_lock(prev);
  
  	printk("
  other info that might help us debug this:
  ");
  	lockdep_print_held_locks(curr);
  
  	printk("
  stack backtrace:
  ");
  	dump_stack();
  
  	return 0;
  }
  
  /*
   * Check whether we are holding such a class already.
   *
   * (Note that this has to be done separately, because the graph cannot
   * detect such classes of deadlocks.)
   *
   * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
   */
  static int
  check_deadlock(struct task_struct *curr, struct held_lock *next,
  	       struct lockdep_map *next_instance, int read)
  {
  	struct held_lock *prev;

  	struct held_lock *nest = NULL;

  	int i;
  
  	for (i = 0; i < curr->lockdep_depth; i++) {
  		prev = curr->held_locks + i;

  
  		if (prev->instance == next->nest_lock)
  			nest = prev;

  		if (hlock_class(prev) != hlock_class(next))

  			continue;

  		/*
  		 * Allow read-after-read recursion of the same

  		 * lock class (i.e. read_lock(lock)+read_lock(lock)):

  		 */

  		if ((read == 2) && prev->read)

  			return 2;

  
  		/*
  		 * We're holding the nest_lock, which serializes this lock's
  		 * nesting behaviour.
  		 */
  		if (nest)
  			return 2;

  		return print_deadlock_bug(curr, prev, next);
  	}
  	return 1;
  }
  
  /*
   * There was a chain-cache miss, and we are about to add a new dependency
   * to a previous lock. We recursively validate the following rules:
   *
   *  - would the adding of the <prev> -> <next> dependency create a
   *    circular dependency in the graph? [== circular deadlock]
   *
   *  - does the new prev->next dependency connect any hardirq-safe lock
   *    (in the full backwards-subgraph starting at <prev>) with any
   *    hardirq-unsafe lock (in the full forwards-subgraph starting at
   *    <next>)? [== illegal lock inversion with hardirq contexts]
   *
   *  - does the new prev->next dependency connect any softirq-safe lock
   *    (in the full backwards-subgraph starting at <prev>) with any
   *    softirq-unsafe lock (in the full forwards-subgraph starting at
   *    <next>)? [== illegal lock inversion with softirq contexts]
   *
   * any of these scenarios could lead to a deadlock.
   *
   * Then if all the validations pass, we add the forwards and backwards
   * dependency.
   */
  static int
  check_prev_add(struct task_struct *curr, struct held_lock *prev,

  	       struct held_lock *next, int distance)

  {
  	struct lock_list *entry;
  	int ret;
  
  	/*
  	 * Prove that the new <prev> -> <next> dependency would not
  	 * create a circular dependency in the graph. (We do this by
  	 * forward-recursing into the graph starting at <next>, and
  	 * checking whether we can reach <prev>.)
  	 *
  	 * We are using global variables to control the recursion, to
  	 * keep the stackframe size of the recursive functions low:
  	 */
  	check_source = next;
  	check_target = prev;

  	if (!(check_noncircular(hlock_class(next), 0)))

  		return print_circular_bug_tail();

  	if (!check_prev_add_irq(curr, prev, next))

  		return 0;
  
  	/*

  	 * For recursive read-locks we do all the dependency checks,
  	 * but we dont store read-triggered dependencies (only
  	 * write-triggered dependencies). This ensures that only the
  	 * write-side dependencies matter, and that if for example a
  	 * write-lock never takes any other locks, then the reads are
  	 * equivalent to a NOP.
  	 */
  	if (next->read == 2 || prev->read == 2)
  		return 1;
  	/*
  	 * Is the <prev> -> <next> dependency already present?
  	 *
  	 * (this may occur even though this is a new chain: consider
  	 *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
  	 *  chains - the second one will be new, but L1 already has
  	 *  L2 added to its dependency list, due to the first chain.)
  	 */

  	list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
  		if (entry->class == hlock_class(next)) {

  			if (distance == 1)
  				entry->distance = 1;

  			return 2;

  		}

  	}
  
  	/*
  	 * Ok, all validations passed, add the new lock
  	 * to the previous lock's dependency list:
  	 */

  	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
  			       &hlock_class(prev)->locks_after,
  			       next->acquire_ip, distance);

  	if (!ret)
  		return 0;

  	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
  			       &hlock_class(next)->locks_before,
  			       next->acquire_ip, distance);

  	if (!ret)
  		return 0;

  
  	/*

  	 * Debugging printouts:
  	 */

  	if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {

  		graph_unlock();
  		printk("
   new dependency: ");

  		print_lock_name(hlock_class(prev));

  		printk(" => ");

  		print_lock_name(hlock_class(next));

  		printk("
  ");

  		dump_stack();

  		return graph_lock();

  	}

  	return 1;
  }

  /*
   * Add the dependency to all directly-previous locks that are 'relevant'.
   * The ones that are relevant are (in increasing distance from curr):
   * all consecutive trylock entries and the final non-trylock entry - or
   * the end of this context's lock-chain - whichever comes first.
   */
  static int
  check_prevs_add(struct task_struct *curr, struct held_lock *next)
  {
  	int depth = curr->lockdep_depth;
  	struct held_lock *hlock;

  	/*

  	 * Debugging checks.
  	 *
  	 * Depth must not be zero for a non-head lock:

  	 */

  	if (!depth)
  		goto out_bug;

  	/*

  	 * At least two relevant locks must exist for this
  	 * to be a head:

  	 */

  	if (curr->held_locks[depth].irq_context !=
  			curr->held_locks[depth-1].irq_context)
  		goto out_bug;

  	for (;;) {
  		int distance = curr->lockdep_depth - depth + 1;
  		hlock = curr->held_locks + depth-1;
  		/*
  		 * Only non-recursive-read entries get new dependencies
  		 * added:
  		 */
  		if (hlock->read != 2) {
  			if (!check_prev_add(curr, hlock, next, distance))
  				return 0;
  			/*
  			 * Stop after the first non-trylock entry,
  			 * as non-trylock entries have added their
  			 * own direct dependencies already, so this
  			 * lock is connected to them indirectly:
  			 */
  			if (!hlock->trylock)
  				break;

  		}

  		depth--;
  		/*
  		 * End of lock-stack?
  		 */
  		if (!depth)
  			break;
  		/*
  		 * Stop the search if we cross into another context:
  		 */
  		if (curr->held_locks[depth].irq_context !=
  				curr->held_locks[depth-1].irq_context)
  			break;

  	}

  	return 1;
  out_bug:
  	if (!debug_locks_off_graph_unlock())
  		return 0;

  	WARN_ON(1);

  	return 0;

  }

  unsigned long nr_lock_chains;

  struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];

  int nr_chain_hlocks;

  static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
  
  struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
  {
  	return lock_classes + chain_hlocks[chain->base + i];
  }

  /*
   * Look up a dependency chain. If the key is not present yet then

   * add it and return 1 - in this case the new dependency chain is
   * validated. If the key is already hashed, return 0.
   * (On return with 1 graph_lock is held.)

   */

  static inline int lookup_chain_cache(struct task_struct *curr,
  				     struct held_lock *hlock,
  				     u64 chain_key)

  {

  	struct lock_class *class = hlock_class(hlock);

  	struct list_head *hash_head = chainhashentry(chain_key);
  	struct lock_chain *chain;

  	struct held_lock *hlock_curr, *hlock_next;

  	int i, j, n, cn;

  	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
  		return 0;

  	/*
  	 * We can walk it lock-free, because entries only get added
  	 * to the hash:
  	 */
  	list_for_each_entry(chain, hash_head, entry) {
  		if (chain->chain_key == chain_key) {
  cache_hit:
  			debug_atomic_inc(&chain_lookup_hits);

  			if (very_verbose(class))

  				printk("
  hash chain already cached, key: "
  					"%016Lx tail class: [%p] %s
  ",
  					(unsigned long long)chain_key,
  					class->key, class->name);

  			return 0;
  		}
  	}

  	if (very_verbose(class))

  		printk("
  new hash chain, key: %016Lx tail class: [%p] %s
  ",
  			(unsigned long long)chain_key, class->key, class->name);

  	/*
  	 * Allocate a new chain entry from the static array, and add
  	 * it to the hash:
  	 */

  	if (!graph_lock())
  		return 0;

  	/*
  	 * We have to walk the chain again locked - to avoid duplicates:
  	 */
  	list_for_each_entry(chain, hash_head, entry) {
  		if (chain->chain_key == chain_key) {

  			graph_unlock();

  			goto cache_hit;
  		}
  	}
  	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {

  		if (!debug_locks_off_graph_unlock())
  			return 0;

  		printk("BUG: MAX_LOCKDEP_CHAINS too low!
  ");
  		printk("turning off the locking correctness validator.
  ");
  		return 0;
  	}
  	chain = lock_chains + nr_lock_chains++;
  	chain->chain_key = chain_key;

  	chain->irq_context = hlock->irq_context;
  	/* Find the first held_lock of current chain */
  	hlock_next = hlock;
  	for (i = curr->lockdep_depth - 1; i >= 0; i--) {
  		hlock_curr = curr->held_locks + i;
  		if (hlock_curr->irq_context != hlock_next->irq_context)
  			break;
  		hlock_next = hlock;
  	}
  	i++;
  	chain->depth = curr->lockdep_depth + 1 - i;

  	cn = nr_chain_hlocks;
  	while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
  		n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
  		if (n == cn)
  			break;
  		cn = n;
  	}
  	if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
  		chain->base = cn;

  		for (j = 0; j < chain->depth - 1; j++, i++) {

  			int lock_id = curr->held_locks[i].class_idx - 1;

  			chain_hlocks[chain->base + j] = lock_id;
  		}
  		chain_hlocks[chain->base + j] = class - lock_classes;
  	}

  	list_add_tail_rcu(&chain->entry, hash_head);
  	debug_atomic_inc(&chain_lookup_misses);

  	inc_chains();
  
  	return 1;
  }
  
  static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,

  		struct held_lock *hlock, int chain_head, u64 chain_key)

  {
  	/*
  	 * Trylock needs to maintain the stack of held locks, but it
  	 * does not add new dependencies, because trylock can be done
  	 * in any order.
  	 *
  	 * We look up the chain_key and do the O(N^2) check and update of
  	 * the dependencies only if this is a new dependency chain.
  	 * (If lookup_chain_cache() returns with 1 it acquires
  	 * graph_lock for us)
  	 */
  	if (!hlock->trylock && (hlock->check == 2) &&

  	    lookup_chain_cache(curr, hlock, chain_key)) {

  		/*
  		 * Check whether last held lock:
  		 *
  		 * - is irq-safe, if this lock is irq-unsafe
  		 * - is softirq-safe, if this lock is hardirq-unsafe
  		 *
  		 * And check whether the new lock's dependency graph
  		 * could lead back to the previous lock.
  		 *
  		 * any of these scenarios could lead to a deadlock. If
  		 * All validations
  		 */
  		int ret = check_deadlock(curr, hlock, lock, hlock->read);
  
  		if (!ret)
  			return 0;
  		/*
  		 * Mark recursive read, as we jump over it when
  		 * building dependencies (just like we jump over
  		 * trylock entries):
  		 */
  		if (ret == 2)
  			hlock->read = 2;
  		/*
  		 * Add dependency only if this lock is not the head
  		 * of the chain, and if it's not a secondary read-lock:
  		 */
  		if (!chain_head && ret != 2)
  			if (!check_prevs_add(curr, hlock))
  				return 0;
  		graph_unlock();
  	} else
  		/* after lookup_chain_cache(): */
  		if (unlikely(!debug_locks))
  			return 0;

  
  	return 1;
  }

  #else
  static inline int validate_chain(struct task_struct *curr,
  	       	struct lockdep_map *lock, struct held_lock *hlock,

  		int chain_head, u64 chain_key)

  {
  	return 1;
  }

  #endif

  
  /*
   * We are building curr_chain_key incrementally, so double-check
   * it from scratch, to make sure that it's done correctly:
   */

  static void check_chain_key(struct task_struct *curr)

  {
  #ifdef CONFIG_DEBUG_LOCKDEP
  	struct held_lock *hlock, *prev_hlock = NULL;
  	unsigned int i, id;
  	u64 chain_key = 0;
  
  	for (i = 0; i < curr->lockdep_depth; i++) {
  		hlock = curr->held_locks + i;
  		if (chain_key != hlock->prev_chain_key) {
  			debug_locks_off();

  			WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx
  ",

  				curr->lockdep_depth, i,
  				(unsigned long long)chain_key,
  				(unsigned long long)hlock->prev_chain_key);

  			return;
  		}

  		id = hlock->class_idx - 1;

  		if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
  			return;

  		if (prev_hlock && (prev_hlock->irq_context !=
  							hlock->irq_context))
  			chain_key = 0;
  		chain_key = iterate_chain_key(chain_key, id);
  		prev_hlock = hlock;
  	}
  	if (chain_key != curr->curr_chain_key) {
  		debug_locks_off();

  		WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx
  ",

  			curr->lockdep_depth, i,
  			(unsigned long long)chain_key,
  			(unsigned long long)curr->curr_chain_key);

  	}
  #endif
  }

  static int
  print_usage_bug(struct task_struct *curr, struct held_lock *this,
  		enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
  {
  	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
  		return 0;
  
  	printk("
  =================================
  ");
  	printk(  "[ INFO: inconsistent lock state ]
  ");
  	print_kernel_version();
  	printk(  "---------------------------------
  ");
  
  	printk("inconsistent {%s} -> {%s} usage.
  ",
  		usage_str[prev_bit], usage_str[new_bit]);
  
  	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:
  ",

  		curr->comm, task_pid_nr(curr),

  		trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
  		trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
  		trace_hardirqs_enabled(curr),
  		trace_softirqs_enabled(curr));
  	print_lock(this);
  
  	printk("{%s} state was registered at:
  ", usage_str[prev_bit]);

  	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);

  
  	print_irqtrace_events(curr);
  	printk("
  other info that might help us debug this:
  ");
  	lockdep_print_held_locks(curr);
  
  	printk("
  stack backtrace:
  ");
  	dump_stack();
  
  	return 0;
  }
  
  /*
   * Print out an error if an invalid bit is set:
   */
  static inline int
  valid_state(struct task_struct *curr, struct held_lock *this,
  	    enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
  {

  	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))

  		return print_usage_bug(curr, this, bad_bit, new_bit);
  	return 1;
  }
  
  static int mark_lock(struct task_struct *curr, struct held_lock *this,
  		     enum lock_usage_bit new_bit);

  #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)

  
  /*
   * print irq inversion bug:
   */
  static int
  print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
  			struct held_lock *this, int forwards,
  			const char *irqclass)
  {

  	if (!debug_locks_off_graph_unlock() || debug_locks_silent)

  		return 0;
  
  	printk("
  =========================================================
  ");
  	printk(  "[ INFO: possible irq lock inversion dependency detected ]
  ");

  	print_kernel_version();

  	printk(  "---------------------------------------------------------
  ");
  	printk("%s/%d just changed the state of lock:
  ",

  		curr->comm, task_pid_nr(curr));

  	print_lock(this);
  	if (forwards)
  		printk("but this lock took another, %s-irq-unsafe lock in the past:
  ", irqclass);
  	else
  		printk("but this lock was taken by another, %s-irq-safe lock in the past:
  ", irqclass);
  	print_lock_name(other);
  	printk("
  
  and interrupts could create inverse lock ordering between them.
  
  ");
  
  	printk("
  other info that might help us debug this:
  ");
  	lockdep_print_held_locks(curr);
  
  	printk("
  the first lock's dependencies:
  ");

  	print_lock_dependencies(hlock_class(this), 0);

  
  	printk("
  the second lock's dependencies:
  ");
  	print_lock_dependencies(other, 0);
  
  	printk("
  stack backtrace:
  ");
  	dump_stack();
  
  	return 0;
  }
  
  /*
   * Prove that in the forwards-direction subgraph starting at <this>
   * there is no lock matching <mask>:
   */
  static int
  check_usage_forwards(struct task_struct *curr, struct held_lock *this,
  		     enum lock_usage_bit bit, const char *irqclass)
  {
  	int ret;
  
  	find_usage_bit = bit;
  	/* fills in <forwards_match> */

  	ret = find_usage_forwards(hlock_class(this), 0);

  	if (!ret || ret == 1)
  		return ret;
  
  	return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
  }
  
  /*
   * Prove that in the backwards-direction subgraph starting at <this>
   * there is no lock matching <mask>:
   */
  static int
  check_usage_backwards(struct task_struct *curr, struct held_lock *this,
  		      enum lock_usage_bit bit, const char *irqclass)
  {
  	int ret;
  
  	find_usage_bit = bit;
  	/* fills in <backwards_match> */

  	ret = find_usage_backwards(hlock_class(this), 0);

  	if (!ret || ret == 1)
  		return ret;
  
  	return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
  }

  void print_irqtrace_events(struct task_struct *curr)

  {
  	printk("irq event stamp: %u
  ", curr->irq_events);
  	printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
  	print_ip_sym(curr->hardirq_enable_ip);
  	printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
  	print_ip_sym(curr->hardirq_disable_ip);
  	printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
  	print_ip_sym(curr->softirq_enable_ip);
  	printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
  	print_ip_sym(curr->softirq_disable_ip);
  }

  static int hardirq_verbose(struct lock_class *class)

  {

  #if HARDIRQ_VERBOSE
  	return class_filter(class);
  #endif

  	return 0;
  }

  static int softirq_verbose(struct lock_class *class)

  {

  #if SOFTIRQ_VERBOSE
  	return class_filter(class);
  #endif
  	return 0;

  }
  
  #define STRICT_READ_CHECKS	1

  static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
  		enum lock_usage_bit new_bit)

  {

  	int ret = 1;

  	switch(new_bit) {

  	case LOCK_USED_IN_HARDIRQ:
  		if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
  			return 0;
  		if (!valid_state(curr, this, new_bit,
  				 LOCK_ENABLED_HARDIRQS_READ))
  			return 0;
  		/*
  		 * just marked it hardirq-safe, check that this lock
  		 * took no hardirq-unsafe lock in the past:
  		 */
  		if (!check_usage_forwards(curr, this,
  					  LOCK_ENABLED_HARDIRQS, "hard"))
  			return 0;
  #if STRICT_READ_CHECKS
  		/*
  		 * just marked it hardirq-safe, check that this lock
  		 * took no hardirq-unsafe-read lock in the past:
  		 */
  		if (!check_usage_forwards(curr, this,
  				LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
  			return 0;
  #endif

  		if (hardirq_verbose(hlock_class(this)))

  			ret = 2;
  		break;
  	case LOCK_USED_IN_SOFTIRQ:
  		if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
  			return 0;
  		if (!valid_state(curr, this, new_bit,
  				 LOCK_ENABLED_SOFTIRQS_READ))
  			return 0;
  		/*
  		 * just marked it softirq-safe, check that this lock
  		 * took no softirq-unsafe lock in the past:
  		 */
  		if (!check_usage_forwards(curr, this,
  					  LOCK_ENABLED_SOFTIRQS, "soft"))
  			return 0;
  #if STRICT_READ_CHECKS
  		/*
  		 * just marked it softirq-safe, check that this lock
  		 * took no softirq-unsafe-read lock in the past:
  		 */
  		if (!check_usage_forwards(curr, this,
  				LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
  			return 0;
  #endif

  		if (softirq_verbose(hlock_class(this)))

  			ret = 2;
  		break;
  	case LOCK_USED_IN_HARDIRQ_READ:
  		if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
  			return 0;
  		/*
  		 * just marked it hardirq-read-safe, check that this lock
  		 * took no hardirq-unsafe lock in the past:
  		 */
  		if (!check_usage_forwards(curr, this,
  					  LOCK_ENABLED_HARDIRQS, "hard"))
  			return 0;

  		if (hardirq_verbose(hlock_class(this)))

  			ret = 2;
  		break;
  	case LOCK_USED_IN_SOFTIRQ_READ:
  		if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
  			return 0;
  		/*
  		 * just marked it softirq-read-safe, check that this lock
  		 * took no softirq-unsafe lock in the past:
  		 */
  		if (!check_usage_forwards(curr, this,
  					  LOCK_ENABLED_SOFTIRQS, "soft"))
  			return 0;

  		if (softirq_verbose(hlock_class(this)))

  			ret = 2;
  		break;
  	case LOCK_ENABLED_HARDIRQS:
  		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
  			return 0;
  		if (!valid_state(curr, this, new_bit,
  				 LOCK_USED_IN_HARDIRQ_READ))
  			return 0;
  		/*
  		 * just marked it hardirq-unsafe, check that no hardirq-safe
  		 * lock in the system ever took it in the past:
  		 */
  		if (!check_usage_backwards(curr, this,
  					   LOCK_USED_IN_HARDIRQ, "hard"))
  			return 0;
  #if STRICT_READ_CHECKS
  		/*
  		 * just marked it hardirq-unsafe, check that no
  		 * hardirq-safe-read lock in the system ever took
  		 * it in the past:
  		 */
  		if (!check_usage_backwards(curr, this,
  				   LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
  			return 0;
  #endif

  		if (hardirq_verbose(hlock_class(this)))

  			ret = 2;
  		break;
  	case LOCK_ENABLED_SOFTIRQS:
  		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
  			return 0;
  		if (!valid_state(curr, this, new_bit,
  				 LOCK_USED_IN_SOFTIRQ_READ))
  			return 0;
  		/*
  		 * just marked it softirq-unsafe, check that no softirq-safe
  		 * lock in the system ever took it in the past:
  		 */
  		if (!check_usage_backwards(curr, this,
  					   LOCK_USED_IN_SOFTIRQ, "soft"))
  			return 0;
  #if STRICT_READ_CHECKS
  		/*
  		 * just marked it softirq-unsafe, check that no
  		 * softirq-safe-read lock in the system ever took
  		 * it in the past:
  		 */
  		if (!check_usage_backwards(curr, this,
  				   LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
  			return 0;
  #endif

  		if (softirq_verbose(hlock_class(this)))

  			ret = 2;
  		break;
  	case LOCK_ENABLED_HARDIRQS_READ:
  		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
  			return 0;
  #if STRICT_READ_CHECKS
  		/*
  		 * just marked it hardirq-read-unsafe, check that no
  		 * hardirq-safe lock in the system ever took it in the past:
  		 */
  		if (!check_usage_backwards(curr, this,
  					   LOCK_USED_IN_HARDIRQ, "hard"))
  			return 0;
  #endif

  		if (hardirq_verbose(hlock_class(this)))

  			ret = 2;
  		break;
  	case LOCK_ENABLED_SOFTIRQS_READ:
  		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
  			return 0;
  #if STRICT_READ_CHECKS
  		/*
  		 * just marked it softirq-read-unsafe, check that no
  		 * softirq-safe lock in the system ever took it in the past:
  		 */
  		if (!check_usage_backwards(curr, this,
  					   LOCK_USED_IN_SOFTIRQ, "soft"))
  			return 0;
  #endif

  		if (softirq_verbose(hlock_class(this)))

  			ret = 2;
  		break;

  	default:

  		WARN_ON(1);

  		break;

  	}
  
  	return ret;
  }

  /*
   * Mark all held locks with a usage bit:
   */

  static int

  mark_held_locks(struct task_struct *curr, int hardirq)

  {
  	enum lock_usage_bit usage_bit;
  	struct held_lock *hlock;
  	int i;
  
  	for (i = 0; i < curr->lockdep_depth; i++) {
  		hlock = curr->held_locks + i;
  
  		if (hardirq) {
  			if (hlock->read)
  				usage_bit = LOCK_ENABLED_HARDIRQS_READ;
  			else
  				usage_bit = LOCK_ENABLED_HARDIRQS;
  		} else {
  			if (hlock->read)
  				usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
  			else
  				usage_bit = LOCK_ENABLED_SOFTIRQS;
  		}

  		if (!mark_lock(curr, hlock, usage_bit))

  			return 0;
  	}
  
  	return 1;
  }
  
  /*
   * Debugging helper: via this flag we know that we are in
   * 'early bootup code', and will warn about any invalid irqs-on event:
   */
  static int early_boot_irqs_enabled;
  
  void early_boot_irqs_off(void)
  {
  	early_boot_irqs_enabled = 0;
  }
  
  void early_boot_irqs_on(void)
  {
  	early_boot_irqs_enabled = 1;
  }
  
  /*
   * Hardirqs will be enabled:
   */

  void trace_hardirqs_on_caller(unsigned long a0)

  {
  	struct task_struct *curr = current;
  	unsigned long ip;

  	time_hardirqs_on(CALLER_ADDR0, a0);

  	if (unlikely(!debug_locks || current->lockdep_recursion))
  		return;
  
  	if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
  		return;
  
  	if (unlikely(curr->hardirqs_enabled)) {
  		debug_atomic_inc(&redundant_hardirqs_on);
  		return;
  	}
  	/* we'll do an OFF -> ON transition: */
  	curr->hardirqs_enabled = 1;
  	ip = (unsigned long) __builtin_return_address(0);
  
  	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
  		return;
  	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
  		return;
  	/*
  	 * We are going to turn hardirqs on, so set the
  	 * usage bit for all held locks:
  	 */

  	if (!mark_held_locks(curr, 1))

  		return;
  	/*
  	 * If we have softirqs enabled, then set the usage
  	 * bit for all held locks. (disabled hardirqs prevented
  	 * this bit from being set before)
  	 */
  	if (curr->softirqs_enabled)

  		if (!mark_held_locks(curr, 0))

  			return;

  	curr->hardirq_enable_ip = ip;
  	curr->hardirq_enable_event = ++curr->irq_events;
  	debug_atomic_inc(&hardirqs_on_events);
  }

  EXPORT_SYMBOL(trace_hardirqs_on_caller);

  void trace_hardirqs_on(void)

  {
  	trace_hardirqs_on_caller(CALLER_ADDR0);
  }

  EXPORT_SYMBOL(trace_hardirqs_on);
  
  /*
   * Hardirqs were disabled:
   */

  void trace_hardirqs_off_caller(unsigned long a0)

  {
  	struct task_struct *curr = current;

  	time_hardirqs_off(CALLER_ADDR0, a0);

  	if (unlikely(!debug_locks || current->lockdep_recursion))
  		return;
  
  	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
  		return;
  
  	if (curr->hardirqs_enabled) {
  		/*
  		 * We have done an ON -> OFF transition:
  		 */
  		curr->hardirqs_enabled = 0;
  		curr->hardirq_disable_ip = _RET_IP_;
  		curr->hardirq_disable_event = ++curr->irq_events;
  		debug_atomic_inc(&hardirqs_off_events);
  	} else
  		debug_atomic_inc(&redundant_hardirqs_off);
  }

  EXPORT_SYMBOL(trace_hardirqs_off_caller);

  void trace_hardirqs_off(void)

  {
  	trace_hardirqs_off_caller(CALLER_ADDR0);
  }

  EXPORT_SYMBOL(trace_hardirqs_off);
  
  /*
   * Softirqs will be enabled:
   */
  void trace_softirqs_on(unsigned long ip)
  {
  	struct task_struct *curr = current;
  
  	if (unlikely(!debug_locks))
  		return;
  
  	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
  		return;
  
  	if (curr->softirqs_enabled) {
  		debug_atomic_inc(&redundant_softirqs_on);
  		return;
  	}
  
  	/*
  	 * We'll do an OFF -> ON transition:
  	 */
  	curr->softirqs_enabled = 1;
  	curr->softirq_enable_ip = ip;
  	curr->softirq_enable_event = ++curr->irq_events;
  	debug_atomic_inc(&softirqs_on_events);
  	/*
  	 * We are going to turn softirqs on, so set the
  	 * usage bit for all held locks, if hardirqs are
  	 * enabled too:
  	 */
  	if (curr->hardirqs_enabled)
  		mark_held_locks(curr, 0);
  }
  
  /*
   * Softirqs were disabled:
   */
  void trace_softirqs_off(unsigned long ip)
  {
  	struct task_struct *curr = current;
  
  	if (unlikely(!debug_locks))
  		return;
  
  	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
  		return;
  
  	if (curr->softirqs_enabled) {
  		/*
  		 * We have done an ON -> OFF transition:
  		 */
  		curr->softirqs_enabled = 0;
  		curr->softirq_disable_ip = ip;
  		curr->softirq_disable_event = ++curr->irq_events;
  		debug_atomic_inc(&softirqs_off_events);
  		DEBUG_LOCKS_WARN_ON(!softirq_count());
  	} else
  		debug_atomic_inc(&redundant_softirqs_off);
  }
  
  static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
  {
  	/*
  	 * If non-trylock use in a hardirq or softirq context, then
  	 * mark the lock as used in these contexts:
  	 */
  	if (!hlock->trylock) {
  		if (hlock->read) {
  			if (curr->hardirq_context)
  				if (!mark_lock(curr, hlock,
  						LOCK_USED_IN_HARDIRQ_READ))
  					return 0;
  			if (curr->softirq_context)
  				if (!mark_lock(curr, hlock,
  						LOCK_USED_IN_SOFTIRQ_READ))
  					return 0;
  		} else {
  			if (curr->hardirq_context)
  				if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
  					return 0;
  			if (curr->softirq_context)
  				if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
  					return 0;
  		}
  	}
  	if (!hlock->hardirqs_off) {
  		if (hlock->read) {
  			if (!mark_lock(curr, hlock,
  					LOCK_ENABLED_HARDIRQS_READ))
  				return 0;
  			if (curr->softirqs_enabled)
  				if (!mark_lock(curr, hlock,
  						LOCK_ENABLED_SOFTIRQS_READ))
  					return 0;
  		} else {
  			if (!mark_lock(curr, hlock,
  					LOCK_ENABLED_HARDIRQS))
  				return 0;
  			if (curr->softirqs_enabled)
  				if (!mark_lock(curr, hlock,
  						LOCK_ENABLED_SOFTIRQS))
  					return 0;
  		}
  	}
  
  	return 1;
  }
  
  static int separate_irq_context(struct task_struct *curr,
  		struct held_lock *hlock)
  {
  	unsigned int depth = curr->lockdep_depth;
  
  	/*
  	 * Keep track of points where we cross into an interrupt context:
  	 */
  	hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
  				curr->softirq_context;
  	if (depth) {
  		struct held_lock *prev_hlock;
  
  		prev_hlock = curr->held_locks + depth-1;
  		/*
  		 * If we cross into another context, reset the
  		 * hash key (this also prevents the checking and the
  		 * adding of the dependency to 'prev'):
  		 */
  		if (prev_hlock->irq_context != hlock->irq_context)
  			return 1;
  	}
  	return 0;

  }

  #else

  static inline
  int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
  		enum lock_usage_bit new_bit)

  {

  	WARN_ON(1);
  	return 1;
  }

  static inline int mark_irqflags(struct task_struct *curr,
  		struct held_lock *hlock)
  {
  	return 1;
  }

  static inline int separate_irq_context(struct task_struct *curr,
  		struct held_lock *hlock)
  {
  	return 0;

  }

  #endif

  
  /*

   * Mark a lock with a usage bit, and validate the state transition:

   */

  static int mark_lock(struct task_struct *curr, struct held_lock *this,

  			     enum lock_usage_bit new_bit)

  {

  	unsigned int new_mask = 1 << new_bit, ret = 1;

  
  	/*

  	 * If already set then do not dirty the cacheline,
  	 * nor do any checks:

  	 */

  	if (likely(hlock_class(this)->usage_mask & new_mask))

  		return 1;
  
  	if (!graph_lock())
  		return 0;

  	/*

  	 * Make sure we didnt race:

  	 */

  	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {

  		graph_unlock();
  		return 1;
  	}

  	hlock_class(this)->usage_mask |= new_mask;

  	if (!save_trace(hlock_class(this)->usage_traces + new_bit))

  		return 0;

  	switch (new_bit) {
  	case LOCK_USED_IN_HARDIRQ:
  	case LOCK_USED_IN_SOFTIRQ:
  	case LOCK_USED_IN_HARDIRQ_READ:
  	case LOCK_USED_IN_SOFTIRQ_READ:
  	case LOCK_ENABLED_HARDIRQS:
  	case LOCK_ENABLED_SOFTIRQS:
  	case LOCK_ENABLED_HARDIRQS_READ:
  	case LOCK_ENABLED_SOFTIRQS_READ:
  		ret = mark_lock_irq(curr, this, new_bit);
  		if (!ret)
  			return 0;
  		break;
  	case LOCK_USED:

  		debug_atomic_dec(&nr_unused_locks);
  		break;
  	default:
  		if (!debug_locks_off_graph_unlock())
  			return 0;
  		WARN_ON(1);
  		return 0;
  	}

  	graph_unlock();
  
  	/*
  	 * We must printk outside of the graph_lock:
  	 */
  	if (ret == 2) {
  		printk("
  marked lock as {%s}:
  ", usage_str[new_bit]);
  		print_lock(this);
  		print_irqtrace_events(curr);
  		dump_stack();
  	}
  
  	return ret;
  }

  
  /*
   * Initialize a lock instance's lock-class mapping info:
   */
  void lockdep_init_map(struct lockdep_map *lock, const char *name,

  		      struct lock_class_key *key, int subclass)

  {
  	if (unlikely(!debug_locks))
  		return;
  
  	if (DEBUG_LOCKS_WARN_ON(!key))
  		return;
  	if (DEBUG_LOCKS_WARN_ON(!name))
  		return;
  	/*
  	 * Sanity check, the lock-class key must be persistent:
  	 */
  	if (!static_obj(key)) {
  		printk("BUG: key %p not in .data!
  ", key);
  		DEBUG_LOCKS_WARN_ON(1);
  		return;
  	}
  	lock->name = name;
  	lock->key = key;

  	lock->class_cache = NULL;

  #ifdef CONFIG_LOCK_STAT
  	lock->cpu = raw_smp_processor_id();
  #endif

  	if (subclass)
  		register_lock_class(lock, subclass, 1);

  }
  
  EXPORT_SYMBOL_GPL(lockdep_init_map);
  
  /*
   * This gets called for every mutex_lock*()/spin_lock*() operation.
   * We maintain the dependency maps and validate the locking attempt:
   */
  static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
  			  int trylock, int read, int check, int hardirqs_off,

  			  struct lockdep_map *nest_lock, unsigned long ip)

  {
  	struct task_struct *curr = current;

  	struct lock_class *class = NULL;

  	struct held_lock *hlock;

  	unsigned int depth, id;
  	int chain_head = 0;
  	u64 chain_key;

  	if (!prove_locking)
  		check = 1;

  	if (unlikely(!debug_locks))
  		return 0;
  
  	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
  		return 0;
  
  	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
  		debug_locks_off();
  		printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!
  ");
  		printk("turning off the locking correctness validator.
  ");
  		return 0;
  	}

  	if (!subclass)
  		class = lock->class_cache;
  	/*
  	 * Not cached yet or subclass?
  	 */

  	if (unlikely(!class)) {

  		class = register_lock_class(lock, subclass, 0);

  		if (!class)
  			return 0;
  	}
  	debug_atomic_inc((atomic_t *)&class->ops);
  	if (very_verbose(class)) {
  		printk("
  acquire class [%p] %s", class->key, class->name);
  		if (class->name_version > 1)
  			printk("#%d", class->name_version);
  		printk("
  ");
  		dump_stack();
  	}
  
  	/*
  	 * Add the lock to the list of currently held locks.
  	 * (we dont increase the depth just yet, up until the
  	 * dependency checks are done)
  	 */
  	depth = curr->lockdep_depth;
  	if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
  		return 0;
  
  	hlock = curr->held_locks + depth;

  	if (DEBUG_LOCKS_WARN_ON(!class))
  		return 0;
  	hlock->class_idx = class - lock_classes + 1;

  	hlock->acquire_ip = ip;
  	hlock->instance = lock;

  	hlock->nest_lock = nest_lock;

  	hlock->trylock = trylock;
  	hlock->read = read;
  	hlock->check = check;

  	hlock->hardirqs_off = !!hardirqs_off;

  #ifdef CONFIG_LOCK_STAT
  	hlock->waittime_stamp = 0;
  	hlock->holdtime_stamp = sched_clock();
  #endif

  	if (check == 2 && !mark_irqflags(curr, hlock))
  		return 0;

  	/* mark it as used: */

  	if (!mark_lock(curr, hlock, LOCK_USED))

  		return 0;

  	/*

  	 * Calculate the chain hash: it's the combined hash of all the

  	 * lock keys along the dependency chain. We save the hash value
  	 * at every step so that we can get the current hash easily
  	 * after unlock. The chain hash is then used to cache dependency
  	 * results.
  	 *
  	 * The 'key ID' is what is the most compact key value to drive
  	 * the hash, not class->key.
  	 */
  	id = class - lock_classes;
  	if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
  		return 0;
  
  	chain_key = curr->curr_chain_key;
  	if (!depth) {
  		if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
  			return 0;
  		chain_head = 1;
  	}
  
  	hlock->prev_chain_key = chain_key;

  	if (separate_irq_context(curr, hlock)) {
  		chain_key = 0;
  		chain_head = 1;

  	}

  	chain_key = iterate_chain_key(chain_key, id);

  	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))

  		return 0;

  	curr->curr_chain_key = chain_key;

  	curr->lockdep_depth++;
  	check_chain_key(curr);

  #ifdef CONFIG_DEBUG_LOCKDEP
  	if (unlikely(!debug_locks))
  		return 0;
  #endif

  	if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
  		debug_locks_off();
  		printk("BUG: MAX_LOCK_DEPTH too low!
  ");
  		printk("turning off the locking correctness validator.
  ");
  		return 0;
  	}

  	if (unlikely(curr->lockdep_depth > max_lockdep_depth))
  		max_lockdep_depth = curr->lockdep_depth;
  
  	return 1;
  }
  
  static int
  print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
  			   unsigned long ip)
  {
  	if (!debug_locks_off())
  		return 0;
  	if (debug_locks_silent)
  		return 0;
  
  	printk("
  =====================================
  ");
  	printk(  "[ BUG: bad unlock balance detected! ]
  ");
  	printk(  "-------------------------------------
  ");
  	printk("%s/%d is trying to release lock (",

  		curr->comm, task_pid_nr(curr));

  	print_lockdep_cache(lock);
  	printk(") at:
  ");
  	print_ip_sym(ip);
  	printk("but there are no more locks to release!
  ");
  	printk("
  other info that might help us debug this:
  ");
  	lockdep_print_held_locks(curr);
  
  	printk("
  stack backtrace:
  ");
  	dump_stack();
  
  	return 0;
  }
  
  /*
   * Common debugging checks for both nested and non-nested unlock:
   */
  static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
  			unsigned long ip)
  {
  	if (unlikely(!debug_locks))
  		return 0;
  	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
  		return 0;
  
  	if (curr->lockdep_depth <= 0)
  		return print_unlock_inbalance_bug(curr, lock, ip);
  
  	return 1;
  }

  static int
  __lock_set_subclass(struct lockdep_map *lock,
  		    unsigned int subclass, unsigned long ip)
  {
  	struct task_struct *curr = current;
  	struct held_lock *hlock, *prev_hlock;
  	struct lock_class *class;
  	unsigned int depth;
  	int i;
  
  	depth = curr->lockdep_depth;
  	if (DEBUG_LOCKS_WARN_ON(!depth))
  		return 0;
  
  	prev_hlock = NULL;
  	for (i = depth-1; i >= 0; i--) {
  		hlock = curr->held_locks + i;
  		/*
  		 * We must not cross into another context:
  		 */
  		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
  			break;
  		if (hlock->instance == lock)
  			goto found_it;
  		prev_hlock = hlock;
  	}
  	return print_unlock_inbalance_bug(curr, lock, ip);
  
  found_it:
  	class = register_lock_class(lock, subclass, 0);

  	hlock->class_idx = class - lock_classes + 1;

  
  	curr->lockdep_depth = i;
  	curr->curr_chain_key = hlock->prev_chain_key;
  
  	for (; i < depth; i++) {
  		hlock = curr->held_locks + i;
  		if (!__lock_acquire(hlock->instance,

  			hlock_class(hlock)->subclass, hlock->trylock,

  				hlock->read, hlock->check, hlock->hardirqs_off,

  				hlock->nest_lock, hlock->acquire_ip))

  			return 0;
  	}
  
  	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
  		return 0;
  	return 1;
  }

  /*
   * Remove the lock to the list of currently held locks in a
   * potentially non-nested (out of order) manner. This is a
   * relatively rare operation, as all the unlock APIs default
   * to nested mode (which uses lock_release()):
   */
  static int
  lock_release_non_nested(struct task_struct *curr,
  			struct lockdep_map *lock, unsigned long ip)
  {
  	struct held_lock *hlock, *prev_hlock;
  	unsigned int depth;
  	int i;
  
  	/*
  	 * Check whether the lock exists in the current stack
  	 * of held locks:
  	 */
  	depth = curr->lockdep_depth;
  	if (DEBUG_LOCKS_WARN_ON(!depth))
  		return 0;
  
  	prev_hlock = NULL;
  	for (i = depth-1; i >= 0; i--) {
  		hlock = curr->held_locks + i;
  		/*
  		 * We must not cross into another context:
  		 */
  		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
  			break;
  		if (hlock->instance == lock)
  			goto found_it;
  		prev_hlock = hlock;
  	}
  	return print_unlock_inbalance_bug(curr, lock, ip);
  
  found_it:

  	lock_release_holdtime(hlock);

  	/*
  	 * We have the right lock to unlock, 'hlock' points to it.
  	 * Now we remove it from the stack, and add back the other
  	 * entries (if any), recalculating the hash along the way:
  	 */
  	curr->lockdep_depth = i;
  	curr->curr_chain_key = hlock->prev_chain_key;
  
  	for (i++; i < depth; i++) {
  		hlock = curr->held_locks + i;
  		if (!__lock_acquire(hlock->instance,

  			hlock_class(hlock)->subclass, hlock->trylock,

  				hlock->read, hlock->check, hlock->hardirqs_off,

  				hlock->nest_lock, hlock->acquire_ip))

  			return 0;
  	}
  
  	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
  		return 0;
  	return 1;
  }
  
  /*
   * Remove the lock to the list of currently held locks - this gets
   * called on mutex_unlock()/spin_unlock*() (or on a failed
   * mutex_lock_interruptible()). This is done for unlocks that nest
   * perfectly. (i.e. the current top of the lock-stack is unlocked)
   */
  static int lock_release_nested(struct task_struct *curr,
  			       struct lockdep_map *lock, unsigned long ip)
  {
  	struct held_lock *hlock;
  	unsigned int depth;
  
  	/*
  	 * Pop off the top of the lock stack:
  	 */
  	depth = curr->lockdep_depth - 1;
  	hlock = curr->held_locks + depth;
  
  	/*
  	 * Is the unlock non-nested:
  	 */
  	if (hlock->instance != lock)
  		return lock_release_non_nested(curr, lock, ip);
  	curr->lockdep_depth--;
  
  	if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
  		return 0;
  
  	curr->curr_chain_key = hlock->prev_chain_key;

  	lock_release_holdtime(hlock);

  #ifdef CONFIG_DEBUG_LOCKDEP
  	hlock->prev_chain_key = 0;

  	hlock->class_idx = 0;

  	hlock->acquire_ip = 0;
  	hlock->irq_context = 0;
  #endif
  	return 1;
  }
  
  /*
   * Remove the lock to the list of currently held locks - this gets
   * called on mutex_unlock()/spin_unlock*() (or on a failed
   * mutex_lock_interruptible()). This is done for unlocks that nest
   * perfectly. (i.e. the current top of the lock-stack is unlocked)
   */
  static void
  __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
  {
  	struct task_struct *curr = current;
  
  	if (!check_unlock(curr, lock, ip))
  		return;
  
  	if (nested) {
  		if (!lock_release_nested(curr, lock, ip))
  			return;
  	} else {
  		if (!lock_release_non_nested(curr, lock, ip))
  			return;
  	}
  
  	check_chain_key(curr);
  }
  
  /*
   * Check whether we follow the irq-flags state precisely:
   */

  static void check_flags(unsigned long flags)

  {

  #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
      defined(CONFIG_TRACE_IRQFLAGS)

  	if (!debug_locks)
  		return;

  	if (irqs_disabled_flags(flags)) {
  		if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
  			printk("possible reason: unannotated irqs-off.
  ");
  		}
  	} else {
  		if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
  			printk("possible reason: unannotated irqs-on.
  ");
  		}
  	}

  
  	/*
  	 * We dont accurately track softirq state in e.g.
  	 * hardirq contexts (such as on 4KSTACKS), so only
  	 * check if not in hardirq contexts:
  	 */
  	if (!hardirq_count()) {
  		if (softirq_count())
  			DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
  		else
  			DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
  	}
  
  	if (!debug_locks)
  		print_irqtrace_events(current);
  #endif
  }

  void
  lock_set_subclass(struct lockdep_map *lock,
  		  unsigned int subclass, unsigned long ip)
  {
  	unsigned long flags;
  
  	if (unlikely(current->lockdep_recursion))
  		return;
  
  	raw_local_irq_save(flags);
  	current->lockdep_recursion = 1;
  	check_flags(flags);
  	if (__lock_set_subclass(lock, subclass, ip))
  		check_chain_key(current);
  	current->lockdep_recursion = 0;
  	raw_local_irq_restore(flags);
  }
  
  EXPORT_SYMBOL_GPL(lock_set_subclass);

  /*
   * We are not always called with irqs disabled - do that here,
   * and also avoid lockdep recursion:
   */

  void lock_acquire(struct lockdep_map *lock, unsigned int subclass,

  			  int trylock, int read, int check,
  			  struct lockdep_map *nest_lock, unsigned long ip)

  {
  	unsigned long flags;
  
  	if (unlikely(current->lockdep_recursion))
  		return;
  
  	raw_local_irq_save(flags);
  	check_flags(flags);
  
  	current->lockdep_recursion = 1;
  	__lock_acquire(lock, subclass, trylock, read, check,

  		       irqs_disabled_flags(flags), nest_lock, ip);

  	current->lockdep_recursion = 0;
  	raw_local_irq_restore(flags);
  }
  
  EXPORT_SYMBOL_GPL(lock_acquire);

  void lock_release(struct lockdep_map *lock, int nested,

  			  unsigned long ip)

  {
  	unsigned long flags;
  
  	if (unlikely(current->lockdep_recursion))
  		return;
  
  	raw_local_irq_save(flags);
  	check_flags(flags);
  	current->lockdep_recursion = 1;
  	__lock_release(lock, nested, ip);
  	current->lockdep_recursion = 0;
  	raw_local_irq_restore(flags);
  }
  
  EXPORT_SYMBOL_GPL(lock_release);

  #ifdef CONFIG_LOCK_STAT
  static int
  print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
  			   unsigned long ip)
  {
  	if (!debug_locks_off())
  		return 0;
  	if (debug_locks_silent)
  		return 0;
  
  	printk("
  =================================
  ");
  	printk(  "[ BUG: bad contention detected! ]
  ");
  	printk(  "---------------------------------
  ");
  	printk("%s/%d is trying to contend lock (",

  		curr->comm, task_pid_nr(curr));

  	print_lockdep_cache(lock);
  	printk(") at:
  ");
  	print_ip_sym(ip);
  	printk("but there are no locks held!
  ");
  	printk("
  other info that might help us debug this:
  ");
  	lockdep_print_held_locks(curr);
  
  	printk("
  stack backtrace:
  ");
  	dump_stack();
  
  	return 0;
  }
  
  static void
  __lock_contended(struct lockdep_map *lock, unsigned long ip)
  {
  	struct task_struct *curr = current;
  	struct held_lock *hlock, *prev_hlock;
  	struct lock_class_stats *stats;
  	unsigned int depth;
  	int i, point;
  
  	depth = curr->lockdep_depth;
  	if (DEBUG_LOCKS_WARN_ON(!depth))
  		return;
  
  	prev_hlock = NULL;
  	for (i = depth-1; i >= 0; i--) {
  		hlock = curr->held_locks + i;
  		/*
  		 * We must not cross into another context:
  		 */
  		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
  			break;
  		if (hlock->instance == lock)
  			goto found_it;
  		prev_hlock = hlock;
  	}
  	print_lock_contention_bug(curr, lock, ip);
  	return;
  
  found_it:
  	hlock->waittime_stamp = sched_clock();

  	point = lock_contention_point(hlock_class(hlock), ip);

  	stats = get_lock_stats(hlock_class(hlock));

  	if (point < ARRAY_SIZE(stats->contention_point))

  		stats->contention_point[point]++;

  	if (lock->cpu != smp_processor_id())
  		stats->bounces[bounce_contended + !!hlock->read]++;

  	put_lock_stats(stats);
  }
  
  static void
  __lock_acquired(struct lockdep_map *lock)
  {
  	struct task_struct *curr = current;
  	struct held_lock *hlock, *prev_hlock;
  	struct lock_class_stats *stats;
  	unsigned int depth;
  	u64 now;

  	s64 waittime = 0;
  	int i, cpu;

  
  	depth = curr->lockdep_depth;
  	if (DEBUG_LOCKS_WARN_ON(!depth))
  		return;
  
  	prev_hlock = NULL;
  	for (i = depth-1; i >= 0; i--) {
  		hlock = curr->held_locks + i;
  		/*
  		 * We must not cross into another context:
  		 */
  		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
  			break;
  		if (hlock->instance == lock)
  			goto found_it;
  		prev_hlock = hlock;
  	}
  	print_lock_contention_bug(curr, lock, _RET_IP_);
  	return;
  
  found_it:

  	cpu = smp_processor_id();
  	if (hlock->waittime_stamp) {
  		now = sched_clock();
  		waittime = now - hlock->waittime_stamp;
  		hlock->holdtime_stamp = now;
  	}

  	stats = get_lock_stats(hlock_class(hlock));

  	if (waittime) {
  		if (hlock->read)
  			lock_time_inc(&stats->read_waittime, waittime);
  		else
  			lock_time_inc(&stats->write_waittime, waittime);
  	}
  	if (lock->cpu != cpu)
  		stats->bounces[bounce_acquired + !!hlock->read]++;

  	put_lock_stats(stats);

  
  	lock->cpu = cpu;

  }
  
  void lock_contended(struct lockdep_map *lock, unsigned long ip)
  {
  	unsigned long flags;
  
  	if (unlikely(!lock_stat))
  		return;
  
  	if (unlikely(current->lockdep_recursion))
  		return;
  
  	raw_local_irq_save(flags);
  	check_flags(flags);
  	current->lockdep_recursion = 1;
  	__lock_contended(lock, ip);
  	current->lockdep_recursion = 0;
  	raw_local_irq_restore(flags);
  }
  EXPORT_SYMBOL_GPL(lock_contended);
  
  void lock_acquired(struct lockdep_map *lock)
  {
  	unsigned long flags;
  
  	if (unlikely(!lock_stat))
  		return;
  
  	if (unlikely(current->lockdep_recursion))
  		return;
  
  	raw_local_irq_save(flags);
  	check_flags(flags);
  	current->lockdep_recursion = 1;
  	__lock_acquired(lock);
  	current->lockdep_recursion = 0;
  	raw_local_irq_restore(flags);
  }
  EXPORT_SYMBOL_GPL(lock_acquired);
  #endif

  /*
   * Used by the testsuite, sanitize the validator state
   * after a simulated failure:
   */
  
  void lockdep_reset(void)
  {
  	unsigned long flags;

  	int i;

  
  	raw_local_irq_save(flags);
  	current->curr_chain_key = 0;
  	current->lockdep_depth = 0;
  	current->lockdep_recursion = 0;
  	memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
  	nr_hardirq_chains = 0;
  	nr_softirq_chains = 0;
  	nr_process_chains = 0;
  	debug_locks = 1;

  	for (i = 0; i < CHAINHASH_SIZE; i++)
  		INIT_LIST_HEAD(chainhash_table + i);

  	raw_local_irq_restore(flags);
  }
  
  static void zap_class(struct lock_class *class)
  {
  	int i;
  
  	/*
  	 * Remove all dependencies this lock is
  	 * involved in:
  	 */
  	for (i = 0; i < nr_list_entries; i++) {
  		if (list_entries[i].class == class)
  			list_del_rcu(&list_entries[i].entry);
  	}
  	/*
  	 * Unhash the class and remove it from the all_lock_classes list:
  	 */
  	list_del_rcu(&class->hash_entry);
  	list_del_rcu(&class->lock_entry);

  	class->key = NULL;

  }

  static inline int within(const void *addr, void *start, unsigned long size)

  {
  	return addr >= start && addr < start + size;
  }
  
  void lockdep_free_key_range(void *start, unsigned long size)
  {
  	struct lock_class *class, *next;
  	struct list_head *head;
  	unsigned long flags;
  	int i;

  	int locked;

  
  	raw_local_irq_save(flags);

  	locked = graph_lock();

  
  	/*
  	 * Unhash all classes that were created by this module:
  	 */
  	for (i = 0; i < CLASSHASH_SIZE; i++) {
  		head = classhash_table + i;
  		if (list_empty(head))
  			continue;

  		list_for_each_entry_safe(class, next, head, hash_entry) {

  			if (within(class->key, start, size))
  				zap_class(class);

  			else if (within(class->name, start, size))
  				zap_class(class);
  		}

  	}

  	if (locked)
  		graph_unlock();

  	raw_local_irq_restore(flags);
  }
  
  void lockdep_reset_lock(struct lockdep_map *lock)
  {

  	struct lock_class *class, *next;

  	struct list_head *head;
  	unsigned long flags;
  	int i, j;

  	int locked;

  
  	raw_local_irq_save(flags);

  
  	/*

  	 * Remove all classes this lock might have:
  	 */
  	for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
  		/*
  		 * If the class exists we look it up and zap it:
  		 */
  		class = look_up_lock_class(lock, j);
  		if (class)
  			zap_class(class);
  	}
  	/*
  	 * Debug check: in the end all mapped classes should
  	 * be gone.

  	 */

  	locked = graph_lock();

  	for (i = 0; i < CLASSHASH_SIZE; i++) {
  		head = classhash_table + i;
  		if (list_empty(head))
  			continue;
  		list_for_each_entry_safe(class, next, head, hash_entry) {

  			if (unlikely(class == lock->class_cache)) {

  				if (debug_locks_off_graph_unlock())
  					WARN_ON(1);

  				goto out_restore;

  			}
  		}
  	}

  	if (locked)
  		graph_unlock();

  
  out_restore:

  	raw_local_irq_restore(flags);
  }

  void lockdep_init(void)

  {
  	int i;
  
  	/*
  	 * Some architectures have their own start_kernel()
  	 * code which calls lockdep_init(), while we also
  	 * call lockdep_init() from the start_kernel() itself,
  	 * and we want to initialize the hashes only once:
  	 */
  	if (lockdep_initialized)
  		return;
  
  	for (i = 0; i < CLASSHASH_SIZE; i++)
  		INIT_LIST_HEAD(classhash_table + i);
  
  	for (i = 0; i < CHAINHASH_SIZE; i++)
  		INIT_LIST_HEAD(chainhash_table + i);
  
  	lockdep_initialized = 1;
  }
  
  void __init lockdep_info(void)
  {
  	printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
  ");
  
  	printk("... MAX_LOCKDEP_SUBCLASSES:    %lu
  ", MAX_LOCKDEP_SUBCLASSES);
  	printk("... MAX_LOCK_DEPTH:          %lu
  ", MAX_LOCK_DEPTH);
  	printk("... MAX_LOCKDEP_KEYS:        %lu
  ", MAX_LOCKDEP_KEYS);
  	printk("... CLASSHASH_SIZE:           %lu
  ", CLASSHASH_SIZE);
  	printk("... MAX_LOCKDEP_ENTRIES:     %lu
  ", MAX_LOCKDEP_ENTRIES);
  	printk("... MAX_LOCKDEP_CHAINS:      %lu
  ", MAX_LOCKDEP_CHAINS);
  	printk("... CHAINHASH_SIZE:          %lu
  ", CHAINHASH_SIZE);
  
  	printk(" memory used by lock dependency info: %lu kB
  ",
  		(sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
  		sizeof(struct list_head) * CLASSHASH_SIZE +
  		sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
  		sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
  		sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
  
  	printk(" per task-struct memory footprint: %lu bytes
  ",
  		sizeof(struct held_lock) * MAX_LOCK_DEPTH);
  
  #ifdef CONFIG_DEBUG_LOCKDEP

  	if (lockdep_init_error) {
  		printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?
  ");
  		printk("Call stack leading to lockdep invocation was:
  ");
  		print_stack_trace(&lockdep_init_trace, 0);
  	}

  #endif
  }

  static void
  print_freed_lock_bug(struct task_struct *curr, const void *mem_from,

  		     const void *mem_to, struct held_lock *hlock)

  {
  	if (!debug_locks_off())
  		return;
  	if (debug_locks_silent)
  		return;
  
  	printk("
  =========================
  ");
  	printk(  "[ BUG: held lock freed! ]
  ");
  	printk(  "-------------------------
  ");
  	printk("%s/%d is freeing memory %p-%p, with a lock still held there!
  ",

  		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);

  	print_lock(hlock);

  	lockdep_print_held_locks(curr);
  
  	printk("
  stack backtrace:
  ");
  	dump_stack();
  }

  static inline int not_in_range(const void* mem_from, unsigned long mem_len,
  				const void* lock_from, unsigned long lock_len)
  {
  	return lock_from + lock_len <= mem_from ||
  		mem_from + mem_len <= lock_from;
  }

  /*
   * Called when kernel memory is freed (or unmapped), or if a lock
   * is destroyed or reinitialized - this code checks whether there is
   * any held lock in the memory range of <from> to <to>:
   */
  void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
  {

  	struct task_struct *curr = current;
  	struct held_lock *hlock;
  	unsigned long flags;
  	int i;
  
  	if (unlikely(!debug_locks))
  		return;
  
  	local_irq_save(flags);
  	for (i = 0; i < curr->lockdep_depth; i++) {
  		hlock = curr->held_locks + i;

  		if (not_in_range(mem_from, mem_len, hlock->instance,
  					sizeof(*hlock->instance)))

  			continue;

  		print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);

  		break;
  	}
  	local_irq_restore(flags);
  }

  EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);

  
  static void print_held_locks_bug(struct task_struct *curr)
  {
  	if (!debug_locks_off())
  		return;
  	if (debug_locks_silent)
  		return;
  
  	printk("
  =====================================
  ");
  	printk(  "[ BUG: lock held at task exit time! ]
  ");
  	printk(  "-------------------------------------
  ");
  	printk("%s/%d is exiting with locks still held!
  ",

  		curr->comm, task_pid_nr(curr));

  	lockdep_print_held_locks(curr);
  
  	printk("
  stack backtrace:
  ");
  	dump_stack();
  }
  
  void debug_check_no_locks_held(struct task_struct *task)
  {
  	if (unlikely(task->lockdep_depth > 0))
  		print_held_locks_bug(task);
  }
  
  void debug_show_all_locks(void)
  {
  	struct task_struct *g, *p;
  	int count = 10;
  	int unlock = 1;

  	if (unlikely(!debug_locks)) {
  		printk("INFO: lockdep is turned off.
  ");
  		return;
  	}

  	printk("
  Showing all locks held in the system:
  ");
  
  	/*
  	 * Here we try to get the tasklist_lock as hard as possible,
  	 * if not successful after 2 seconds we ignore it (but keep
  	 * trying). This is to enable a debug printout even if a
  	 * tasklist_lock-holding task deadlocks or crashes.
  	 */
  retry:
  	if (!read_trylock(&tasklist_lock)) {
  		if (count == 10)
  			printk("hm, tasklist_lock locked, retrying... ");
  		if (count) {
  			count--;
  			printk(" #%d", 10-count);
  			mdelay(200);
  			goto retry;
  		}
  		printk(" ignoring it.
  ");
  		unlock = 0;
  	}
  	if (count != 10)
  		printk(" locked it.
  ");
  
  	do_each_thread(g, p) {

  		/*
  		 * It's not reliable to print a task's held locks
  		 * if it's not sleeping (or if it's not the current
  		 * task):
  		 */
  		if (p->state == TASK_RUNNING && p != current)
  			continue;

  		if (p->lockdep_depth)
  			lockdep_print_held_locks(p);
  		if (!unlock)
  			if (read_trylock(&tasklist_lock))
  				unlock = 1;
  	} while_each_thread(g, p);
  
  	printk("
  ");
  	printk("=============================================
  
  ");
  
  	if (unlock)
  		read_unlock(&tasklist_lock);
  }
  
  EXPORT_SYMBOL_GPL(debug_show_all_locks);

  /*
   * Careful: only use this function if you are sure that
   * the task cannot run in parallel!
   */
  void __debug_show_held_locks(struct task_struct *task)

  {

  	if (unlikely(!debug_locks)) {
  		printk("INFO: lockdep is turned off.
  ");
  		return;
  	}

  	lockdep_print_held_locks(task);
  }

  EXPORT_SYMBOL_GPL(__debug_show_held_locks);
  
  void debug_show_held_locks(struct task_struct *task)
  {
  		__debug_show_held_locks(task);
  }

  
  EXPORT_SYMBOL_GPL(debug_show_held_locks);

  
  void lockdep_sys_exit(void)
  {
  	struct task_struct *curr = current;
  
  	if (unlikely(curr->lockdep_depth)) {
  		if (!debug_locks_off())
  			return;
  		printk("
  ================================================
  ");
  		printk(  "[ BUG: lock held when returning to user space! ]
  ");
  		printk(  "------------------------------------------------
  ");
  		printk("%s/%d is leaving the kernel with locks still held!
  ",
  				curr->comm, curr->pid);
  		lockdep_print_held_locks(curr);
  	}
  }