Re: [GIT PULL] RCU changes for v5.10

[Linus Torvalds]

On Mon, Oct 12, 2020 at 7:14 AM Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
> Please pull the latest core/rcu git tree from:
>
> RCU changes for v5.10:
>
>  - Debugging for smp_call_function()
>  - RT raw/non-raw lock ordering fixes
>  - Strict grace periods for KASAN
>  - New smp_call_function() torture test
>  - Torture-test updates
>  - Documentation updates
>  - Miscellaneous fixes

I am *very* unhappy with this pull request.

It doesn't even mention the big removal of CONFIR_PREEMPT, that I felt
was still under discussion.

I don't absolutely hate that code, and I'm willing to be convinced
about how little it matter for people who don't want to have the
counting overhead, but I refuse to pull it as some secret hidden thing
that isn't even mentioned in the pull request.

Honestly, I did not get any strong arguments for why making the
preempt count unconditional was such an important thing.

Yes, Thomas pointed me at a couple of uses that were garbage, but even
the people involved in those seemed to agree they were legacy garbage.

So why was this preempt-count thing then pushed through like this?

                 Linus