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Date: Tue, 30 Aug 2011 05:24:20 GMT From: tip-bot for Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com> To: linux-tip-commits@...r.kernel.org Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com, tglx@...utronix.de, hpa@...ux.intel.com, jeremy.fitzhardinge@...rix.com Subject: [tip:x86/spinlocks] x86: Add xadd helper macro Commit-ID: 433b3520616be694e0aa777089346c8718c91a7b Gitweb: http://git.kernel.org/tip/433b3520616be694e0aa777089346c8718c91a7b Author: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com> AuthorDate: Tue, 21 Jun 2011 12:00:55 -0700 Committer: H. Peter Anvin <hpa@...ux.intel.com> CommitDate: Mon, 29 Aug 2011 13:42:20 -0700 x86: Add xadd helper macro Add a common xadd implementation. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com> Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.org Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com> --- arch/x86/include/asm/cmpxchg.h | 43 ++++++++++++++++++++++++++++++++++++++++ 1 files changed, 43 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h index efe3ec7..0d0d9cd 100644 --- a/arch/x86/include/asm/cmpxchg.h +++ b/arch/x86/include/asm/cmpxchg.h @@ -6,6 +6,7 @@ /* Non-existant functions to indicate usage errors at link time. */ extern void __xchg_wrong_size(void); extern void __cmpxchg_wrong_size(void); +extern void __xadd_wrong_size(void); /* * Constants for operation sizes. On 32-bit, the 64-bit size it set to @@ -157,4 +158,46 @@ extern void __cmpxchg_wrong_size(void); __cmpxchg_local((ptr), (old), (new), sizeof(*ptr)) #endif +#define __xadd(ptr, inc, lock) \ + ({ \ + __typeof__ (*(ptr)) __ret = (inc); \ + switch (sizeof(*(ptr))) { \ + case __X86_CASE_B: \ + asm volatile (lock "xaddb %b0, %1\n" \ + : "+r" (__ret), "+m" (*(ptr)) \ + : : "memory", "cc"); \ + break; \ + case __X86_CASE_W: \ + asm volatile (lock "xaddw %w0, %1\n" \ + : "+r" (__ret), "+m" (*(ptr)) \ + : : "memory", "cc"); \ + break; \ + case __X86_CASE_L: \ + asm volatile (lock "xaddl %0, %1\n" \ + : "+r" (__ret), "+m" (*(ptr)) \ + : : "memory", "cc"); \ + break; \ + case __X86_CASE_Q: \ + asm volatile (lock "xaddq %q0, %1\n" \ + : "+r" (__ret), "+m" (*(ptr)) \ + : : "memory", "cc"); \ + break; \ + default: \ + __xadd_wrong_size(); \ + } \ + __ret; \ + }) + +/* + * xadd() adds "inc" to "*ptr" and atomically returns the previous + * value of "*ptr". + * + * xadd() is locked when multiple CPUs are online + * xadd_sync() is always locked + * xadd_local() is never locked + */ +#define xadd(ptr, inc) __xadd((ptr), (inc), LOCK_PREFIX) +#define xadd_sync(ptr, inc) __xadd((ptr), (inc), "lock; ") +#define xadd_local(ptr, inc) __xadd((ptr), (inc), "") + #endif /* ASM_X86_CMPXCHG_H */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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