Hi all,
The helper is tiny and there are advices we can live without it, so
I want to present few arguments why it would be good to have it:
1. Code readability/simplification/number of lines:
- decreases number of lines,
- it often eliminates local variables,
- for real examples see patches 3+.
2. Presence of similar helpers in other somehow related languages/libs:
a) Rust[1]: 'replace' from std::mem module, there is also 'take'
helper (__xchg(&x, 0)), which is the same as private helper in
i915 - fetch_and_zero, see latest patch.
b) C++ [2]: 'exchange' from utility header.
If the idea is OK there are still 2 questions to answer:
1. Name of the helper, __xchg follows kernel conventions,
but for me Rust names are also OK.
2. Where to put the helper:
a) as in this patchset include/linux/non-atomic/xchg.h,
proposed by Andy Shevchenko,
b) include/linux/utils.h ? any better name? Some kind
of container for simple helpers.
All __xchg conversions were performed using cocci script,
then manually adjusted if necessary.
There is lot of places it can be used in, I have just chosen
some of them. I can provide cocci script to detect others (not all),
if necessary.
Changes:
v2: squashed all __xchg -> __arch_xchg t one patch (Arnd)
v3: fixed alpha/xchg_local (lkp@xxxxxxxxx)
v4: adjusted indentation (Heiko)
v5: added more __xchg conversions - patches 3-6, added tags
[1]: https://doc.rust-lang.org/std/mem/index.html
[2]: https://en.cppreference.com/w/cpp/header/utility
Regards
Andrzej
Andrzej Hajda (7):
arch: rename all internal names __xchg to __arch_xchg
linux/include: add non-atomic version of xchg
arch/*/uprobes: simplify arch_uretprobe_hijack_return_addr
llist: simplify __llist_del_all
io_uring: use __xchg if possible
qed: use __xchg if possible
drm/i915/gt: use __xchg instead of internal helper
arch/alpha/include/asm/cmpxchg.h | 10 +++++-----
arch/arc/include/asm/cmpxchg.h | 4 ++--
arch/arm/include/asm/cmpxchg.h | 7 ++++---
arch/arm/probes/uprobes/core.c | 8 ++------
arch/arm64/include/asm/cmpxchg.h | 7 +++----
arch/arm64/kernel/probes/uprobes.c | 9 ++-------
arch/csky/kernel/probes/uprobes.c | 9 ++-------
arch/hexagon/include/asm/cmpxchg.h | 10 +++++-----
arch/ia64/include/asm/cmpxchg.h | 2 +-
arch/ia64/include/uapi/asm/cmpxchg.h | 4 ++--
arch/loongarch/include/asm/cmpxchg.h | 4 ++--
arch/m68k/include/asm/cmpxchg.h | 6 +++---
arch/mips/include/asm/cmpxchg.h | 4 ++--
arch/mips/kernel/uprobes.c | 10 ++--------
arch/openrisc/include/asm/cmpxchg.h | 10 +++++-----
arch/parisc/include/asm/cmpxchg.h | 4 ++--
arch/powerpc/include/asm/cmpxchg.h | 4 ++--
arch/powerpc/kernel/uprobes.c | 10 ++--------
arch/riscv/include/asm/atomic.h | 2 +-
arch/riscv/include/asm/cmpxchg.h | 4 ++--
arch/riscv/kernel/probes/uprobes.c | 9 ++-------
arch/s390/include/asm/cmpxchg.h | 8 ++++----
arch/s390/kernel/uprobes.c | 7 ++-----
arch/sh/include/asm/cmpxchg.h | 4 ++--
arch/sparc/include/asm/cmpxchg_32.h | 4 ++--
arch/sparc/include/asm/cmpxchg_64.h | 6 +++---
arch/sparc/kernel/uprobes.c | 7 ++-----
arch/xtensa/include/asm/cmpxchg.h | 4 ++--
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 +-
.../gpu/drm/i915/gt/intel_engine_heartbeat.c | 4 ++--
.../drm/i915/gt/intel_execlists_submission.c | 4 ++--
drivers/gpu/drm/i915/gt/intel_ggtt.c | 4 ++--
drivers/gpu/drm/i915/gt/intel_gsc.c | 2 +-
drivers/gpu/drm/i915/gt/intel_gt.c | 4 ++--
drivers/gpu/drm/i915/gt/intel_gt_pm.c | 2 +-
drivers/gpu/drm/i915/gt/intel_lrc.c | 6 +++---
drivers/gpu/drm/i915/gt/intel_migrate.c | 2 +-
drivers/gpu/drm/i915/gt/intel_rc6.c | 2 +-
drivers/gpu/drm/i915/gt/intel_rps.c | 2 +-
drivers/gpu/drm/i915/gt/selftest_context.c | 2 +-
.../drm/i915/gt/selftest_ring_submission.c | 2 +-
drivers/gpu/drm/i915/gt/selftest_timeline.c | 2 +-
drivers/gpu/drm/i915/gt/uc/intel_gsc_uc.c | 2 +-
drivers/gpu/drm/i915/gt/uc/intel_uc.c | 2 +-
drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 2 +-
drivers/gpu/drm/i915/i915_utils.h | 1 +
include/linux/llist.h | 6 ++----
include/linux/non-atomic/xchg.h | 19 +++++++++++++++++++
include/linux/qed/qed_chain.h | 19 +++++++------------
io_uring/io_uring.c | 7 ++-----
io_uring/slist.h | 6 ++----
51 files changed, 126 insertions(+), 155 deletions(-)
create mode 100644 include/linux/non-atomic/xchg.h
--
2.34.1
