linux-kernel - [PATCH 4.9 02/66] compiler, clang: suppress warning for unused static inline functions

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Message-Id: <20180720121407.391832846@linuxfoundation.org>
Date:   Fri, 20 Jul 2018 14:13:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Rientjes <rientjes@...gle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.9 02/66] compiler, clang: suppress warning for unused static inline functions

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Rientjes <rientjes@...gle.com>

commit abb2ea7dfd82451d85ce669b811310c05ab5ca46 upstream.

GCC explicitly does not warn for unused static inline functions for
-Wunused-function.  The manual states:

	Warn whenever a static function is declared but not defined or
	a non-inline static function is unused.

Clang does warn for static inline functions that are unused.

It turns out that suppressing the warnings avoids potentially complex
#ifdef directives, which also reduces LOC.

Suppress the warning for clang.

Signed-off-by: David Rientjes <rientjes@...gle.com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 include/linux/compiler-clang.h |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -16,6 +16,13 @@
  */
 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
 
+/*
+ * GCC does not warn about unused static inline functions for
+ * -Wunused-function.  This turns out to avoid the need for complex #ifdef
+ * directives.  Suppress the warning in clang as well.
+ */
+#define inline inline __attribute__((unused))
+
 /* Clang doesn't have a way to turn it off per-function, yet. */
 #ifdef __noretpoline
 #undef __noretpoline