linux-kernel - Re: [PATCH 2/6] move _body_io_syscall to the generic syscall.h

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Date:   Fri, 05 Jan 2018 11:25:17 -0500
From:   Jeff Moyer <jmoyer@...hat.com>
To:     Christoph Hellwig <hch@....de>,
        Benjamin LaHaise <ben@...munityfibre.ca>
Cc:     linux-aio@...ck.org, Avi Kivity <avi@...lladb.com>,
        linux-fsdevel@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] move _body_io_syscall to the generic syscall.h

Christoph Hellwig <hch@....de> writes:

> This way it can be used for the fallback 6-argument version on
> all architectures.
>
> Signed-off-by: Christoph Hellwig <hch@....de>

This is a strange way to do things.  However, I was never really sold on
libaio having to implement its own system call wrappers.  That decision
definitely resulted in some maintenance overhead.

Ben, what was your reasoning for not just using syscall?

-Jeff

> ---
>  src/syscall-generic.h | 6 ------
>  src/syscall.h         | 7 +++++++
>  2 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/src/syscall-generic.h b/src/syscall-generic.h
> index 24d7c7c..35b8580 100644
> --- a/src/syscall-generic.h
> +++ b/src/syscall-generic.h
> @@ -2,12 +2,6 @@
>  #include <unistd.h>
>  #include <sys/syscall.h>
>  
> -#define _body_io_syscall(sname, args...) \
> -{ \
> -	int ret = syscall(__NR_##sname, ## args); \
> -	return ret < 0 ? -errno : ret; \
> -}
> -
>  #define io_syscall1(type,fname,sname,type1,arg1) \
>  type fname(type1 arg1) \
>  _body_io_syscall(sname, (long)arg1)
> diff --git a/src/syscall.h b/src/syscall.h
> index a2da030..3819519 100644
> --- a/src/syscall.h
> +++ b/src/syscall.h
> @@ -10,6 +10,13 @@
>  #define DEFSYMVER(compat_sym, orig_sym, ver_sym)	\
>  	__asm__(".symver " SYMSTR(compat_sym) "," SYMSTR(orig_sym) "@@LIBAIO_" SYMSTR(ver_sym));
>  
> +/* generic fallback */
> +#define _body_io_syscall(sname, args...) \
> +{ \
> +	int ret = syscall(__NR_##sname, ## args); \
> +	return ret < 0 ? -errno : ret; \
> +}
> +
>  #if defined(__i386__)
>  #include "syscall-i386.h"
>  #elif defined(__x86_64__)