[RFC] rwlock: prevent readers from starving writers

[Stephen Hemminger]

On Sat, 9 Jul 2022 00:04:27 +0200
Morten Brørup <mb at smartsharesystems.com> wrote:

> Always the creative mind, Stephen. :-)
> 
> You might consider adding/updating even more comments.
> 
> Acked-by: Morten Brørup <mb at smartsharesystems.com>

The motivation is that our work load is reader/writer lock heavy
with small number of threads. Therefore the number of atomic operations
per lock matters, but starving is bad. And any compare-exchange on ARM
is expensive and should be avoided if possible.

The concept here came from this great page.
https://locklessinc.com/articles/locks/

Will add link in next version.