On Mon, May 14, 2018 at 03:31:06PM -0400, Waiman Long wrote: > There are use cases where a rwsem can be acquired by one task, but > released by another task. In thess cases, it may not be appropriate > for the lock waiters to spin on the task that acquires the lock. > One example will be the filesystem freeze/thaw code. > > To handle such use cases, a new RWSEM_WRITER_OWNED_NOSPIN > flag can now be set in the owner field of the rwsem by the new > rwsem_set_writer_owned_nospin() function to indicate that the rwsem is > writer owned, but optimistic spinning on the rwsem should be disabled. > > Later on, the new rwsem_set_writer_owned() function can be called to > set the new owner, if it is known. This function should not be called > without a prior rwsem_set_writer_owned_nospin() call. Urgh.. no please don't do this. Aside from the horrible naming, do not expose 'set-owner' semantics. Can't we just stick to the existing _non_owner() interface without further polluting the API?
