[PATCH 14/17] powerpc/qspinlock: use spin_begin/end API

[Nicholas Piggin]

On Thu Nov 10, 2022 at 10:43 AM AEST, Jordan Niethe wrote:
> On Thu, 2022-07-28 at 16:31 +1000, Nicholas Piggin wrote:
> [resend as utf-8, not utf-7]
> > Use the spin_begin/spin_cpu_relax/spin_end APIs in qspinlock, which helps
> > to prevent threads issuing a lot of expensive priority nops which may not
> > have much effect due to immediately executing low then medium priority.
>
> Just a general comment regarding the spin_{begin,end} API, more complicated
> than something like
>
> 	spin_begin()
> 	for(;;)
> 		spin_cpu_relax()
> 	spin_end()
>
> it becomes difficult to keep track of. Unfortunately, I don't have any good
> suggestions how to improve it. Hopefully with P10s wait instruction we can
> maybe try and move away from this.
>
> It might be useful to comment the functions pre and post conditions regarding
> expectations about spin_begin() and spin_end().

Yep, added some small comments.

Thanks,
Nick