qobject atomics osdep: Make a few macros more hygienic

[mirror_qemu.git] / include / qemu / atomic.h

diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
index d95612f7a084ef11af68ddd1733285a2edba3e63..f1d3d1702a93c20b83eac503fa74a77b3895cbef 100644 (file)
--- a/include/qemu/atomic.h
+++ b/include/qemu/atomic.h
@@ -157,13 +157,20 @@
     smp_read_barrier_depends();
 #endif
 
-#define qatomic_rcu_read(ptr)                          \
-    ({                                                 \
+/*
+ * Preprocessor sorcery ahead: use a different identifier for the
+ * local variable in each expansion, so we can nest macro calls
+ * without shadowing variables.
+ */
+#define qatomic_rcu_read_internal(ptr, _val)            \
+    ({                                                  \
     qemu_build_assert(sizeof(*ptr) <= ATOMIC_REG_SIZE); \
-    typeof_strip_qual(*ptr) _val;                      \
-    qatomic_rcu_read__nocheck(ptr, &_val);             \
-    _val;                                              \
+    typeof_strip_qual(*ptr) _val;                       \
+    qatomic_rcu_read__nocheck(ptr, &_val);              \
+    _val;                                               \
     })
+#define qatomic_rcu_read(ptr) \
+    qatomic_rcu_read_internal((ptr), MAKE_IDENTFIER(_val))
 
 #define qatomic_rcu_set(ptr, i) do {                   \
     qemu_build_assert(sizeof(*ptr) <= ATOMIC_REG_SIZE); \