[RFC 02/12] lockdep: Add a function building a chain between two hlocks

add_chain_cache() can only be used by current context since it depends on a task's held_locks which is not protected by lock. However, it would be useful if a dependency chain can be built in any context. This patch makes the chain building not depend on its context. Especially, crossrelease

[RFC 02/12] lockdep: Add a function building a chain between two hlocks

add_chain_cache() can only be used by current context since it depends on a task's held_locks which is not protected by lock. However, it would be useful if a dependency chain can be built in any context. This patch makes the chain building not depend on its context. Especially, crossrelease