Hello, Here is version three of the patches previously posted here: v1: https://lwn.net/Articles/650862/ v2: https://lwn.net/Articles/651293/ 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 v2 include: - Re-organised the series so it's more amenable to getting merged (i.e. included an extra qrwlock dependency) - Added some comments to the qrwlock code - Added extra comments to delimit the relaxed atomic macros - Fixed typo in comment message Build tested on ARM, arm64, PowerPC and x86. All feedback welcome, Will --->8 Will Deacon (8): 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: implement queue_write_unlock using smp_store_release 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 +----- arch/x86/include/asm/qrwlock.h | 10 -- include/asm-generic/atomic-long.h | 263 +++++++++++-------------------- include/asm-generic/qrwlock.h | 22 +-- include/linux/atomic.h | 323 ++++++++++++++++++++++++++++++++++++++ include/linux/llist.h | 2 +- kernel/locking/qrwlock.c | 23 ++- lib/lockref.c | 8 - 9 files changed, 463 insertions(+), 272 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
