linux-kernel - Re: [RFC PATCH v3 0/6] Deduplicating RISCV cmpxchg.h macros

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Date:   Thu, 6 Apr 2023 05:04:03 -0300
From:   Leonardo Bras Soares Passos <leobras@...hat.com>
To:     Guo Ren <guoren@...nel.org>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andrea Parri <parri.andrea@...il.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v3 0/6] Deduplicating RISCV cmpxchg.h macros

On Wed, Apr 5, 2023 at 11:40 PM Guo Ren <guoren@...nel.org> wrote:
>
> Thx Leonardo,
>
> It's a good point for cleaning up.

Hello Guo,
Thanks for the feedback!

>
> On Wed, Apr 5, 2023 at 12:37 AM Leonardo Bras <leobras@...hat.com> wrote:
> >
> > While studying riscv's cmpxchg.h file, I got really interested in
> > understanding how RISCV asm implemented the different versions of
> > {cmp,}xchg.
> >
> > When I understood the pattern, it made sense for me to remove the
> > duplications and create macros to make it easier to understand what exactly
> > changes between the versions: Instruction sufixes & barriers.
> >
> > I split those changes in 3 levels for each cmpxchg and xchg, resulting a
> But how about merging 3 levels into one? (I mean one for cmpxchg and
> one for xchg, resulting in 2 patches.)

Sure, as mentioned below, I have no issue squashing the patches, so 2
should work fine.

I was previously worried about the changes, so I split them in 3 so
it's easier to understand my thought process.

I will resend it in a couple minutes.

>
> > total of 6 patches. I did this so it becomes easier to review and remove
> > the last levels if desired, but I have no issue squashing them if it's
> > better.
> >
> > Please provide comments.
> >
> > Thanks!
> > Leo
> >
> > Changes since v2:
> > - Fixed  macros that depend on having a local variable with a magic name
> > - Previous cast to (long) is now only applied on 4-bytes cmpxchg
> >
> > Changes since v1:
> > - Fixed patch 4/6 suffix from 'w.aqrl' to '.w.aqrl', to avoid build error
> >
> >
> > Leonardo Bras (6):
> >   riscv/cmpxchg: Deduplicate cmpxchg() asm functions
> >   riscv/cmpxchg: Deduplicate cmpxchg() macros
> >   riscv/cmpxchg: Deduplicate arch_cmpxchg() macros
> >   riscv/cmpxchg: Deduplicate xchg() asm functions
> >   riscv/cmpxchg: Deduplicate xchg() macros
> >   riscv/cmpxchg: Deduplicate arch_xchg() macros
> >
> >  arch/riscv/include/asm/cmpxchg.h | 319 +++++++------------------------
> >  1 file changed, 67 insertions(+), 252 deletions(-)
> >
> > --
> > 2.40.0
> >
>
>
> --
> Best Regards
>  Guo Ren
>

Best regards,
Leo