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

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Date:   Thu, 28 Jan 2021 10:59:07 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...il.com>
To:     Masahiro Yamada <masahiroy@...nel.org>, linux-arch@...r.kernel.org,
        x86@...nel.org
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-alpha@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-ia64@...r.kernel.org, linux-m68k@...ts.linux-m68k.org,
        linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
        linux-sh@...r.kernel.org, linux-um@...ts.infradead.org,
        linux-xtensa@...ux-xtensa.org, linuxppc-dev@...ts.ozlabs.org,
        sparclinux@...r.kernel.org
Subject: Re: [PATCH 02/27] x86/syscalls: fix -Wmissing-prototypes warnings
 from COND_SYSCALL()

Hello!

On 28.01.2021 3:50, Masahiro Yamada wrote:

> Building kernel/sys_ni.c with W=1 omits tons of -Wmissing-prototypes

    Emits?

> 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>
> ---
> 
>   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)	\

    Aren't these two lines identical?

[...]

MBR, Sergei