linux-kernel - [PATCH] module: Remove const attribute from alias for MODULE_DEVICE

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Message-Id: <20170725012725.120097-1-mka@chromium.org>
Date:   Mon, 24 Jul 2017 18:27:25 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Jessica Yu <jeyu@...nel.org>, Rusty Russell <rusty@...tcorp.com.au>
Cc:     linux-kernel@...r.kernel.org,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <mmarek@...e.com>,
        Kees Cook <keescook@...omium.org>,
        Arnd Bergmann <arnd@...db.de>,
        Doug Anderson <dianders@...omium.org>,
        Grant Grundler <grundler@...omium.org>,
        Greg Hackmann <ghackmann@...gle.com>,
        Michael Davidson <md@...gle.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Bernhard.Rosenkranzer@...aro.org,
        Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH] module: Remove const attribute from alias for MODULE_DEVICE_TABLE

MODULE_DEVICE_TABLE(type, name) creates an alias of type 'extern const
typeof(name)'. If 'name' is already constant the 'const' attribute is
specified twice, which is not allowed in C89 (see discussion at
https://lkml.org/lkml/2017/5/23/1440). Since the kernel is built with
-std=gnu89 clang generates warnings like this:

drivers/thermal/x86_pkg_temp_thermal.c:509:1: warning: duplicate 'const'
  declaration specifier
      [-Wduplicate-decl-specifier]
MODULE_DEVICE_TABLE(x86cpu, pkg_temp_thermal_ids);
^
./include/linux/module.h:212:8: note: expanded from macro 'MODULE_DEVICE_TABLE'
extern const typeof(name) __mod_##type##__##name##_device_table

Remove the const attribute from the alias to avoid the duplicate
specifier. After all it is only an alias and the attribute shouldn't
have any effect.

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
---
 include/linux/module.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index e7bdd549e527..fe5aa3736707 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -209,7 +209,7 @@ extern void cleanup_module(void);
 #ifdef MODULE
 /* Creates an alias so file2alias.c can find device table. */
 #define MODULE_DEVICE_TABLE(type, name)					\
-extern const typeof(name) __mod_##type##__##name##_device_table		\
+extern typeof(name) __mod_##type##__##name##_device_table		\
   __attribute__ ((unused, alias(__stringify(name))))
 #else  /* !MODULE */
 #define MODULE_DEVICE_TABLE(type, name)
-- 
2.14.0.rc0.284.gd933b75aa4-goog