Hi all, This is version two of the patches I previously posted here: https://lwn.net/Articles/650862/ The series adds support for a family of relaxed atomics to the kernel. More specifically: - acquire/release/relaxed flavours of xchg, cmpxchg and {add,sub}_return - atomic_read_acquire - atomic_set_release This came out of a separate patch series porting the (barrier-heavy) qrwlock code to arm64. Rather than have arch-specific hooks littered around the place, it makes more sense to define a core set of relaxed atomics that can be used regardless of architecture. Changes since v1 include: - Added macros to construct acquire/release/fence variants from a relaxed variant + barrier macros - Ported ARM as a proof of concept (with a negative diffstat!) Build tested on ARM, arm64, PowerPC and x86. All feedback welcome, Will --->8 Will Deacon (7): atomics: add acquire/release/relaxed variants of some atomic operations asm-generic: rework atomic-long.h to avoid bulk code duplication asm-generic: add relaxed/acquire/release variants for atomic_long_t lockref: remove homebrew cmpxchg64_relaxed macro definition locking/qrwlock: make use of acquire/release/relaxed atomics include/llist: use linux/atomic.h instead of asm/cmpxchg.h ARM: atomics: define our SMP atomics in terms of _relaxed operations arch/arm/include/asm/atomic.h | 37 ++--- arch/arm/include/asm/cmpxchg.h | 47 +----- include/asm-generic/atomic-long.h | 263 ++++++++++++-------------------- include/asm-generic/qrwlock.h | 13 +- include/linux/atomic.h | 312 ++++++++++++++++++++++++++++++++++++++ include/linux/llist.h | 2 +- kernel/locking/qrwlock.c | 12 +- lib/lockref.c | 8 - 8 files changed, 442 insertions(+), 252 deletions(-) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
