[PATCH 1/2] x86/syscalls: fix -Wmissing-prototypes warnings from COND_SYSCALL()

[Masahiro Yamada <masahiroy@kernel.org>]

Building kernel/sys_ni.c with W=1 emits 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@kernel.org>
Tested-by: Mickaël Salaün <mic@linux.microsoft.com>
---

 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();				\
-- 
2.27.0