Re: [PATCH 3/3] sched: Add cond_resched_rwlock

[Davidlohr Bueso]

On Tue, 27 Oct 2020, Sean Christopherson wrote:

> On Tue, Oct 27, 2020 at 09:49:50AM -0700, Ben Gardon wrote:
> > Rescheduling while holding a spin lock is essential for keeping long
> > running kernel operations running smoothly. Add the facility to
> > cond_resched rwlocks.

Nit: I would start the paragraph with 'Safely rescheduling ...'
While obvious when reading the code, 'Rescheduling while holding
a spin lock' can throw the reader off.

> This adds two new exports and two new macros without any in-tree users, which
> is generally frowned upon.  You and I know these will be used by KVM's new
> TDP MMU, but the non-KVM folks, and more importantly the maintainers of this
> code, are undoubtedly going to ask "why".  I.e. these patches probably belong
> in the KVM series to switch to a rwlock for the TDP MMU.
>
> Regarding the code, it's all copy-pasted from the spinlock code and darn near
> identical.  It might be worth adding builder macros for these.

Agreed, all three could be nicely consolidated. Otherwise this series looks
sane, feel free to add my:

Acked-by: Davidlohr Bueso <dbueso@xxxxxxx>