linux-kernel - Re: [RFC PATCH v2 0/3] Deduplicate RISCV cmpxchg.h and atomic.c macros

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Date:   Thu, 3 Aug 2023 15:53:37 +0200
From:   Andrea Parri <parri.andrea@...il.com>
To:     Leonardo Bras <leobras@...hat.com>
Cc:     Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Arnd Bergmann <arnd@...db.de>, Ingo Molnar <mingo@...nel.org>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Guo Ren <guoren@...nel.org>, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [RFC PATCH v2 0/3] Deduplicate RISCV cmpxchg.h and atomic.c
 macros

On Thu, Aug 03, 2023 at 02:13:57AM -0300, Leonardo Bras wrote:
> I unified previous patchsets into a single one, since the work is related.
> 
> 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.
> 
> Also, did the same kind of work on atomic.c.
> 
> Note to Guo Ren:
> I did some further improvement after your previous reviews, so I ended
> up afraid including your Reviewed-by before cheching if the changes are
> ok for you. Please check it out again, I just removed some helper macros
> that were not being used elsewhere in the kernel.
> 
> Thanks!
> Leo
> 
> 
> Changes since squashed cmpxchg:
> - Unified with atomic.c patchset 
> - Rebased on top of torvalds/master (thanks Andrea Parri!)
> - Removed helper macros that were not being used elsewhere in the kernel.
> 
> Changes since (cmpxchg) RFCv3:
> - Squashed the 6 original patches in 2: one for cmpxchg and one for xchg
> https://lore.kernel.org/all/20230404163741.2762165-1-leobras@redhat.com/
> 
> Changes since (cmpxchg) RFCv2:
> - 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
> https://lore.kernel.org/all/20230321074249.2221674-1-leobras@redhat.com/
> 
> Changes since (cmpxchg) RFCv1:
> - Fixed patch 4/6 suffix from 'w.aqrl' to '.w.aqrl', to avoid build error
> https://lore.kernel.org/all/20230318080059.1109286-1-leobras@redhat.com/
> 
> 
> Leonardo Bras (3):
>   riscv/cmpxchg: Deduplicate xchg() asm functions
>   riscv/cmpxchg: Deduplicate cmpxchg() asm and macros
>   riscv/atomic.h : Deduplicate arch_atomic.*
> 
>  arch/riscv/include/asm/atomic.h  | 164 ++++++++--------
>  arch/riscv/include/asm/cmpxchg.h | 318 +++++--------------------------
>  2 files changed, 123 insertions(+), 359 deletions(-)

LGTM.  For the series,

Reviewed-by: Andrea Parri <parri.andrea@...il.com>

  Andrea