Merge commit 'v2.6.26-rc9' into cpus4096

[linux-2.6-omap-h63xx.git] / include / linux / compiler.h

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index d0e17e1657dca11b86f151084a10bc87204c80a1..c8bd2daf95ec51e0f42ad05e6b8c13be1300ce16 100644 (file)
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -138,6 +138,12 @@ extern void __chk_io_ptr(const volatile void __iomem *);
 #define noinline
 #endif
 
+/*
+ * Rather then using noinline to prevent stack consumption, use
+ * noinline_for_stack instead.  For documentaiton reasons.
+ */
+#define noinline_for_stack noinline
+
 #ifndef __always_inline
 #define __always_inline inline
 #endif
@@ -176,4 +182,16 @@ extern void __chk_io_ptr(const volatile void __iomem *);
 # define __section(S) __attribute__ ((__section__(#S)))
 #endif
 
+/*
+ * Prevent the compiler from merging or refetching accesses.  The compiler
+ * is also forbidden from reordering successive instances of ACCESS_ONCE(),
+ * but only when the compiler is aware of some particular ordering.  One way
+ * to make the compiler aware of ordering is to put the two invocations of
+ * ACCESS_ONCE() in different C statements.
+ *
+ * This macro does absolutely -nothing- to prevent the CPU from reordering,
+ * merging, or refetching absolutely anything at any time.
+ */
+#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
+
 #endif /* __LINUX_COMPILER_H */