lockdep: Check if nested lock is actually held

struct lock_class_key __lockdep_no_validate__;

static int

print_lock_nested_lock_not_held(struct task_struct *curr,

				struct held_lock *hlock,

				unsigned long ip)

{

	if (!debug_locks_off())

		return 0;

	if (debug_locks_silent)

		return 0;

	printk("\n");

	printk("==================================\n");

	printk("[ BUG: Nested lock was not taken ]\n");

	print_kernel_ident();

	printk("----------------------------------\n");

	printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));

	print_lock(hlock);

	printk("\nbut this task is not holding:\n");

	printk("%s\n", hlock->nest_lock->name);

	printk("\nstack backtrace:\n");

	dump_stack();

	printk("\nother info that might help us debug this:\n");

	lockdep_print_held_locks(curr);

	printk("\nstack backtrace:\n");

	dump_stack();

	return 0;

}

static int __lock_is_held(struct lockdep_map *lock);

/*

 * This gets called for every mutex_lock*()/spin_lock*() operation.

 * We maintain the dependency maps and validate the locking attempt:

	}

	chain_key = iterate_chain_key(chain_key, id);

	if (nest_lock && !__lock_is_held(nest_lock))

		return print_lock_nested_lock_not_held(curr, hlock, ip);

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

		return 0;