lockdep.c

Kernel code of linux kernel

		 * 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("\nmarked lock as {%s}:\n", 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!\n", 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!\n");
		printk("turning off the locking correctness validator.\n");
		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("\nacquire class [%p] %s", class->key, class->name);
		if (class->name_version > 1)
			printk("#%d", class->name_version);
		printk("\n");
		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();