linux-kernel - Re: [PATCH 02/27] x86/syscalls: fix -Wmissing-prototypes warnings from COND

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Message-ID: <41f7ad59-6ee7-db95-0e56-861c61e8318f@digikod.net>
Date:   Thu, 4 Feb 2021 15:16:29 +0100
From:   Mickaël Salaün <mic@...ikod.net>
To:     Masahiro Yamada <masahiroy@...nel.org>, linux-arch@...r.kernel.org,
        x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH 02/27] x86/syscalls: fix -Wmissing-prototypes warnings
 from COND_SYSCALL()


On 28/01/2021 01:50, Masahiro Yamada wrote:
> Building kernel/sys_ni.c with W=1 omits tons of -Wmissing-prototypes
> warnings.
> 
> $ make W=1 kernel/sys_ni.o
>   [ snip ]
>   CC      kernel/sys_ni.o
> In file included from kernel/sys_ni.c:10:
> ./arch/x86/include/asm/syscall_wrapper.h:83:14: warning: no previous prototype for '__x64_sys_io_setup' [-Wmissing-prototypes]
>    83 |  __weak long __##abi##_##name(const struct pt_regs *__unused) \
>       |              ^~
> ./arch/x86/include/asm/syscall_wrapper.h:100:2: note: in expansion of macro '__COND_SYSCALL'
>   100 |  __COND_SYSCALL(x64, sys_##name)
>       |  ^~~~~~~~~~~~~~
> ./arch/x86/include/asm/syscall_wrapper.h:256:2: note: in expansion of macro '__X64_COND_SYSCALL'
>   256 |  __X64_COND_SYSCALL(name)     \
>       |  ^~~~~~~~~~~~~~~~~~
> kernel/sys_ni.c:39:1: note: in expansion of macro 'COND_SYSCALL'
>    39 | COND_SYSCALL(io_setup);
>       | ^~~~~~~~~~~~
> ./arch/x86/include/asm/syscall_wrapper.h:83:14: warning: no previous prototype for '__ia32_sys_io_setup' [-Wmissing-prototypes]
>    83 |  __weak long __##abi##_##name(const struct pt_regs *__unused) \
>       |              ^~
> ./arch/x86/include/asm/syscall_wrapper.h:120:2: note: in expansion of macro '__COND_SYSCALL'
>   120 |  __COND_SYSCALL(ia32, sys_##name)
>       |  ^~~~~~~~~~~~~~
> ./arch/x86/include/asm/syscall_wrapper.h:257:2: note: in expansion of macro '__IA32_COND_SYSCALL'
>   257 |  __IA32_COND_SYSCALL(name)
>       |  ^~~~~~~~~~~~~~~~~~~
> kernel/sys_ni.c:39:1: note: in expansion of macro 'COND_SYSCALL'
>    39 | COND_SYSCALL(io_setup);
>       | ^~~~~~~~~~~~
>   ...
> 
> __SYS_STUB0() and __SYS_STUBx() defined a few lines above have forward
> declarations. Let's do likewise for __COND_SYSCALL() to fix the
> warnings.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>

Tested-by: Mickaël Salaün <mic@...ux.microsoft.com>

Thanks to this patch we avoid multiple emails from Intel's bot when
adding new syscalls. :)


> ---
> 
>  arch/x86/include/asm/syscall_wrapper.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h
> index a84333adeef2..80c08c7d5e72 100644
> --- a/arch/x86/include/asm/syscall_wrapper.h
> +++ b/arch/x86/include/asm/syscall_wrapper.h
> @@ -80,6 +80,7 @@ extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);
>  	}
>  
>  #define __COND_SYSCALL(abi, name)					\
> +	__weak long __##abi##_##name(const struct pt_regs *__unused);	\
>  	__weak long __##abi##_##name(const struct pt_regs *__unused)	\
>  	{								\
>  		return sys_ni_syscall();				\
>