Messages in this thread Patch in this message | | | From | behanw@converse ... | Subject | [PATCH v3] module: LLVMLinux: Remove unused function warning from __param_check macro | Date | Tue, 11 Mar 2014 14:24:51 -0700 |
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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:
linux/kernel/panic.c:471:1: warning: unused function '__check_panic' [-Wunused-function] core_param(panic, panic_timeout, int, 0644); ^ linux/moduleparam.h:283:2: note: expanded from macro 'core_param' param_check_##type(name, &(var)); \ ^ <scratch space>:87:1: note: expanded from here param_check_int ^ linux/moduleparam.h:369:34: note: expanded from macro 'param_check_int' #define param_check_int(name, p) __param_check(name, p, int) ^ linux/moduleparam.h:349:22: note: expanded from macro '__param_check' static inline type *__check_##name(void) { return(p); } ^ <scratch space>:88:1: note: expanded from here __check_panic
GCC won't complain for a static inline function but would if it was just a static function.
Adding the unused attribute to the function declaration removes the warning. Per request from Rusty Russell it is marked as __always_unused as the code is meant to be optimized away.
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(-)
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index c3eb102..175f699 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 type __always_unused *__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); -- 1.8.3.2
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