x86, perfcounters: add atomic64_xchg()
Complete atomic64_t support on the 32-bit side by adding atomic64_xch().
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090406094518.445450972@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/include/asm/atomic_32.h b/arch/x86/include/asm/atomic_32.h
index 977250e..aff9f1f 100644
--- a/arch/x86/include/asm/atomic_32.h
+++ b/arch/x86/include/asm/atomic_32.h
@@ -291,6 +291,28 @@
}
/**
+ * atomic64_xchg - xchg atomic64 variable
+ * @ptr: pointer to type atomic64_t
+ * @new_val: value to assign
+ * @old_val: old value that was there
+ *
+ * Atomically xchgs the value of @ptr to @new_val and returns
+ * the old value.
+ */
+
+static inline unsigned long long
+atomic64_xchg(atomic64_t *ptr, unsigned long long new_val)
+{
+ unsigned long long old_val;
+
+ do {
+ old_val = atomic_read(ptr);
+ } while (atomic64_cmpxchg(ptr, old_val, new_val) != old_val);
+
+ return old_val;
+}
+
+/**
* atomic64_set - set atomic64 variable
* @ptr: pointer to type atomic64_t
* @new_val: value to assign
@@ -299,11 +321,7 @@
*/
static inline void atomic64_set(atomic64_t *ptr, unsigned long long new_val)
{
- unsigned long long old_val;
-
- do {
- old_val = atomic_read(ptr);
- } while (atomic64_cmpxchg(ptr, old_val, new_val) != old_val);
+ atomic64_xchg(ptr, new_val);
}
/**