[PATCH] GCC 3.3.x/3.4 compatiblity fix in include/linux/init.h

GCC 3.4 miscompiles the kernel because it silently optimizes away
data placed in the .init.setup section by the __setup() macro.

__attribute__((unused)) does only avoid the warning, but doesn't
mark the data as being used.

Since GCC 3.3, __attribute__((used)) should be applied to such
variables.  The __attribute_used__ macro from linux/compiler.h already
takes care of compiler differences for us.

In this patch, I've gone a step further and proactively fixed that in
all places.

include/linux/init.h

@@ -43,12 +43,12 @@
 #define __init		__attribute__ ((__section__ (".init.text")))
 #define __initdata	__attribute__ ((__section__ (".init.data")))
 #define __exitdata	__attribute__ ((__section__(".exit.data")))
-#define __exit_call	__attribute__ ((unused,__section__ (".exitcall.exit")))
+#define __exit_call	__attribute_used__ __attribute__ ((__section__ (".exitcall.exit")))
 
 #ifdef MODULE
 #define __exit		__attribute__ ((__section__(".exit.text")))
 #else
-#define __exit		__attribute__ ((unused,__section__(".exit.text")))
+#define __exit		__attribute_used__ __attribute__ ((__section__(".exit.text")))
 #endif
 
 /* For assembly routines */
@@ -79,7 +79,8 @@ extern initcall_t __security_initcall_start, __security_initcall_end;
  */
 
 #define __define_initcall(level,fn) \
-	static initcall_t __initcall_##fn __attribute__ ((unused,__section__ (".initcall" level ".init"))) = fn
+	static initcall_t __initcall_##fn __attribute_used__ \
+	__attribute__((__section__(".initcall" level ".init"))) = fn
 
 #define core_initcall(fn)		__define_initcall("1",fn)
 #define postcore_initcall(fn)		__define_initcall("2",fn)
@@ -95,10 +96,12 @@ extern initcall_t __security_initcall_start, __security_initcall_end;
 	static exitcall_t __exitcall_##fn __exit_call = fn
 
 #define console_initcall(fn) \
-	static initcall_t __initcall_##fn __attribute__ ((unused,__section__ (".con_initcall.init")))=fn
+	static initcall_t __initcall_##fn \
+	__attribute_used__ __attribute__((__section__(".con_initcall.init")))=fn
 
 #define security_initcall(fn) \
-	static initcall_t __initcall_##fn __attribute__ ((unused,__section__ (".security_initcall.init"))) = fn
+	static initcall_t __initcall_##fn \
+	__attribute_used__ __attribute__((__section__(".security_initcall.init"))) = fn
 
 struct obs_kernel_param {
 	const char *str;
@@ -109,7 +112,8 @@ struct obs_kernel_param {
 #define __setup(str, fn)					\
 	static char __setup_str_##fn[] __initdata = str;	\
 	static struct obs_kernel_param __setup_##fn		\
-		 __attribute__((unused,__section__ (".init.setup")))	\
+		 __attribute_used__				\
+		 __attribute__((__section__(".init.setup")))	\
 		= { __setup_str_##fn, fn }
 
 #endif /* __ASSEMBLY__ */