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[v2] module: LLVMLinux: Remove unused function warning from __param_check macro

Message ID 1394244623-25623-1-git-send-email-behanw@converseincode.com
State New
Headers show

Commit Message

Behan Webster March 8, 2014, 2:10 a.m. UTC
From: Mark Charlebois <charlebm@gmail.com>

This code makes a compile time type check that is optimized away. Clang
complains that it generates an unused function.

I believe GCC won't complain for a static inline fuction but would if it
was just a static function.

Adding the unused attribute to the function definition removes the warning.

This code works for both gcc and clang.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>
Signed-off-by: Behan Webster <behanw@converseincode.com>
---
 include/linux/moduleparam.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Joe Perches March 8, 2014, 2:17 a.m. UTC | #1
On Fri, 2014-03-07 at 18:10 -0800, behanw@converseincode.com wrote:
> This code makes a compile time type check that is optimized away. Clang
> complains that it generates an unused function.
[]
> diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
[]
> @@ -346,7 +346,7 @@ static inline void destroy_params(const struct kernel_param *params,
>  /* The macros to do compile-time type checking stolen from Jakub
>     Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
>  #define __param_check(name, p, type) \
> -	static inline type *__check_##name(void) { return(p); }
> +	static inline __always_unused type *__check_##name(void) { return(p); }

Perhaps __maybe_unused ?


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Behan Webster March 8, 2014, 2:21 a.m. UTC | #2
On 03/07/14 18:17, Joe Perches wrote:
> On Fri, 2014-03-07 at 18:10 -0800, behanw@converseincode.com wrote:
>> This code makes a compile time type check that is optimized away. Clang
>> complains that it generates an unused function.
> []
>> diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
> []
>> @@ -346,7 +346,7 @@ static inline void destroy_params(const struct kernel_param *params,
>>   /* The macros to do compile-time type checking stolen from Jakub
>>      Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
>>   #define __param_check(name, p, type) \
>> -	static inline type *__check_##name(void) { return(p); }
>> +	static inline __always_unused type *__check_##name(void) { return(p); }
> Perhaps __maybe_unused ?
I thought about that (and even tested with __maybe_unused), but I 
*think* they are always unused, except at compile time (see comment 
above). Though I could be wrong.

I'm certainly okay with __maybe_unused if that is preferable.

Behan
diff mbox

Patch

diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index c3eb102..7f2a726 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -346,7 +346,7 @@  static inline void destroy_params(const struct kernel_param *params,
 /* The macros to do compile-time type checking stolen from Jakub
    Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 #define __param_check(name, p, type) \
-	static inline type *__check_##name(void) { return(p); }
+	static inline __always_unused type *__check_##name(void) { return(p); }
 
 extern struct kernel_param_ops param_ops_byte;
 extern int param_set_byte(const char *val, const struct kernel_param *kp);