From daed244102a3b3772f74a43cc5a04632d425910a Mon Sep 17 00:00:00 2001
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Date: Tue, 21 Jun 2011 12:00:55 -0700
Subject: [PATCH] --- yaml --- r: 269548 b: refs/heads/master c:
 433b3520616be694e0aa777089346c8718c91a7b h: refs/heads/master v: v3

---
 [refs]                               |  2 +-
 trunk/arch/x86/include/asm/cmpxchg.h | 43 ++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index e163c2026161..b905e479d074 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e9826380d83d1bda3ee5663bf3fa4667a6fbe60a
+refs/heads/master: 433b3520616be694e0aa777089346c8718c91a7b
diff --git a/trunk/arch/x86/include/asm/cmpxchg.h b/trunk/arch/x86/include/asm/cmpxchg.h
index efe3ec778a58..0d0d9cdd3309 100644
--- a/trunk/arch/x86/include/asm/cmpxchg.h
+++ b/trunk/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 */