[tip:tracing/core] compiler: Introduce __always_unused

[tip-bot for Li Zefan <lizf@cn.fujitsu.com>]

Commit-ID:  7b2a35132ad0a70902dcd2844c27ed64cda0ce9b
Gitweb:     http://git.kernel.org/tip/7b2a35132ad0a70902dcd2844c27ed64cda0ce9b
Author:     Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Mon, 2 Nov 2009 08:50:52 +0800
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 2 Nov 2009 15:47:54 +0100

compiler: Introduce __always_unused

I wrote some code which is used as compile-time checker, and the
code should be elided after compile.

So I need to annotate the code as "always unused", compared to
"maybe unused".

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <4AEE2CEC.8040206@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 include/linux/compiler-gcc.h |    1 +
 include/linux/compiler.h     |    4 ++++
 2 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index a3ed7cb..73dcf80 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -79,6 +79,7 @@
 #define  noinline			__attribute__((noinline))
 #define __attribute_const__		__attribute__((__const__))
 #define __maybe_unused			__attribute__((unused))
+#define __always_unused			__attribute__((unused))
 
 #define __gcc_header(x) #x
 #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 04fb513..7947f4f 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -213,6 +213,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
 # define __maybe_unused		/* unimplemented */
 #endif
 
+#ifndef __always_unused
+# define __always_unused	/* unimplemented */
+#endif
+
 #ifndef noinline
 #define noinline
 #endif