locking/lockdep: Add a function building a chain between two classes

	return 1;

}

/*

 * This is for building a chain between just two different classes,

 * instead of adding a new hlock upon current, which is done by

 * add_chain_cache().

 *

 * This can be called in any context with two classes, while

 * add_chain_cache() must be done within the lock owener's context

 * since it uses hlock which might be racy in another context.

 */

static inline int add_chain_cache_classes(unsigned int prev,

					  unsigned int next,

					  unsigned int irq_context,

					  u64 chain_key)

{

	struct hlist_head *hash_head = chainhashentry(chain_key);

	struct lock_chain *chain;

	/*

	 * Allocate a new chain entry from the static array, and add

	 * it to the hash:

	 */

	/*

	 * We might need to take the graph lock, ensure we've got IRQs

	 * disabled to make this an IRQ-safe lock.. for recursion reasons

	 * lockdep won't complain about its own locking errors.

	 */

	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))

		return 0;

	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {

		if (!debug_locks_off_graph_unlock())

			return 0;

		print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");

		dump_stack();

		return 0;

	}

	chain = lock_chains + nr_lock_chains++;

	chain->chain_key = chain_key;

	chain->irq_context = irq_context;

	chain->depth = 2;

	if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {

		chain->base = nr_chain_hlocks;

		nr_chain_hlocks += chain->depth;

		chain_hlocks[chain->base] = prev - 1;

		chain_hlocks[chain->base + 1] = next -1;

	}

#ifdef CONFIG_DEBUG_LOCKDEP

	/*

	 * Important for check_no_collision().

	 */

	else {

		if (!debug_locks_off_graph_unlock())

			return 0;

		print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");

		dump_stack();

		return 0;

	}

#endif

	hlist_add_head_rcu(&chain->entry, hash_head);

	debug_atomic_inc(chain_lookup_misses);

	inc_chains();

	return 1;

}

/*

 * Adds a dependency chain into chain hashtable. And must be called with

 * graph_lock held.