Re: [PATCH 05/10] sched/core: Remove the tsk_cpus_allowed() wrapper

From: Ingo Molnar
Date: Thu Feb 09 2017 - 04:08:20 EST

* Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Wed, Feb 08, 2017 at 07:34:18PM +0100, Ingo Molnar wrote:
> > So the original intention of tsk_cpus_allowed() was to 'future-proof' the
> > field - but it's pretty ineffectual at that, because half of the code uses
> > ->cpus_allowed directly ...
> >
> > Also, the wrapper makes the code longer than the original expression!
> I still object to taking this out without replacement.

Yeah, that would have been my next suggestion.

> This leaves RT stranded.

Well, no, it leaves -rt with slightly more patching work than it already has...

Because note how the wrappery is _already_ incomplete to a significant degree:

triton:~/tip> git grep -Ee '->cpus_allowed' | grep -vE 'tsk_|cpuset|core.c' | wc -l
triton:~/tip> git grep tsk_cpus_allowed | wc -l

I.e. around 40% of the places that use ->cpus_allowed in the upstream kernel are
not properly wrapped. That fact already 'wrecks' -rt.