[Qemu-devel] [PATCH v5 22/33] atomic: introduce cmpxchg_bool

["Alex Bennée" <alex.bennee@linaro.org>]

This allows for slightly neater code when checking for success of a
cmpxchg operation.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

---
v4 (base-patches)
   - brought forward from ARM enabling patches
   - remove the un-needed extra temps
---
 include/qemu/atomic.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
index 49cf55f..bd74b75 100644
--- a/include/qemu/atomic.h
+++ b/include/qemu/atomic.h
@@ -205,6 +205,14 @@
     atomic_cmpxchg__nocheck(ptr, old, new);                             \
 })
 
+#define atomic_bool_cmpxchg(ptr, old, new)                              \
+    ({                                                                  \
+    typeof(*ptr) _old = (old), _new = (new);                            \
+    __atomic_compare_exchange(ptr, &_old, &_new, false,                 \
+                                  __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);  \
+    })
+
+
 /* Provide shorter names for GCC atomic builtins, return old value */
 #define atomic_fetch_inc(ptr)  __atomic_fetch_add(ptr, 1, __ATOMIC_SEQ_CST)
 #define atomic_fetch_dec(ptr)  __atomic_fetch_sub(ptr, 1, __ATOMIC_SEQ_CST)
@@ -432,6 +440,7 @@
 
 #define atomic_cmpxchg(ptr, old, new) __sync_val_compare_and_swap(ptr, old, new)
 #define atomic_cmpxchg__nocheck(ptr, old, new)  atomic_cmpxchg(ptr, old, new)
+#define atomic_bool_cmpxchg(ptr, old, new)    __sync_bool_compare_and_swap(ptr, old, new)
 
 /* And even shorter names that return void.  */
 #define atomic_inc(ptr)        ((void) __sync_fetch_and_add(ptr, 1))
-- 
2.10.1