diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-10-20 14:53:33 -1000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-10-20 14:53:33 -1000 |
| commit | 6303381334e3ac3f0762c5db2f240e0348c36c9b (patch) | |
| tree | 84340da1196aa21a4dc0bb745b8040aa4b0fafb4 /include | |
| parent | 14c897740388216acd59477a382de327d5e27ba4 (diff) | |
| parent | 558ccc91ddf98d58ae726ed7ccaf5838f284084f (diff) | |
Merge tag 'cmpxchg-emu.2026.10.12b' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull two-byte cmpxchg emulation from Paul McKenney:
"These commits add a cmpxchg_emu_u16() function that emulates two-byte
cmpxchg() in terms of four-byte cmpxchg() for architectures not having
native instructions for this purpose. They also make use of this
cmpxchg_emu_u16() function in those architectures, namely sh, arc,
csky, and xtensa. This permits use of two-byte cmpxchg() in common
code.
However, it sadly does not permit easy implementation of all
algorithms needing on two-byte atomic operations because there are
some systems still supported by Linux that do not have native two-byte
store instructions.
There is reason to believe that these systems will soon no longer be
supported by Linux [1]"
Link: https://lore.kernel.org/all/20260908152808.3928630-4-arnd@kernel.org/ [1]
* tag 'cmpxchg-emu.2026.10.12b' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
xtensa: Emulate two-byte cmpxchg
csky: Emulate two-byte cmpxchg
ARC: Emulate two-byte cmpxchg
sh: Emulate two-byte cmpxchg
lib: Add two-byte cmpxchg emulation function
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/cmpxchg-emu.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/cmpxchg-emu.h b/include/linux/cmpxchg-emu.h index 998deec67740..2db70f1e3925 100644 --- a/include/linux/cmpxchg-emu.h +++ b/include/linux/cmpxchg-emu.h @@ -4,12 +4,14 @@ * lacking direct support for these sizes. These are implemented in terms * of 4-byte cmpxchg operations. * - * Copyright (C) 2024 Paul E. McKenney. + * Copyright (C) 2024 Paul E. McKenney <paulmck@kernel.org> + * Copyright (C) 2026 Bradley Morgan <brads@mainlining.org> */ #ifndef __LINUX_CMPXCHG_EMU_H #define __LINUX_CMPXCHG_EMU_H uintptr_t cmpxchg_emu_u8(volatile u8 *p, uintptr_t old, uintptr_t new); +unsigned long cmpxchg_emu_u16(volatile u16 *p, unsigned long old, unsigned long new); #endif /* __LINUX_CMPXCHG_EMU_H */ |