[RFC PATCH v2 0/3] Deduplicate RISCV cmpxchg.h and atomic.c macros

From: Leonardo Bras
Date: Thu Aug 03 2023 - 01:15:23 EST

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

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.


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

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

Changes since (cmpxchg) RFCv1:
- Fixed patch 4/6 suffix from 'w.aqrl' to '.w.aqrl', to avoid build error

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(-)