Re: [PATCH 1/4] blkcg: Drop unnecessary RCU read [un]locks from blkg_conf_prep/finish()

From: Christoph Hellwig
Date: Tue Jan 10 2023 - 01:49:16 EST


On Mon, Jan 09, 2023 at 10:48:55AM -1000, Tejun Heo wrote:
> Now that all RCU flavors have been combined, holding a spin lock, disabling
> irq, disabling preemption all imply RCU read lock.

Can you write it like this in the commit log, please?

> I can drop the changes but this actually bothers me. The annotation has been
> broken for a *long* time and nobody noticed. Furthermore, I can't remember a
> time when __acquires/__releases notation caught anything that lockdep
> couldn't trivially and can't even think of a way how it could. AFAICS, these
> annotations don't contribute anything other than preservation of themselves.
> I don't see why we would want to keep them.

People have noticed it. It just hasn't been a priority as there are
lots of even more problematic things.