linux-kernel - Re: [PATCH v3 1/3] sh: add __NR_syscalls along with NR

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Date:   Tue, 20 Nov 2018 12:35:44 +0530
From:   Firoz Khan <firoz.khan@...aro.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     linux-sh@...r.kernel.org,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        y2038 Mailman List <y2038@...ts.linaro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        Marcin Juszkiewicz <marcin.juszkiewicz@...aro.org>
Subject: Re: [PATCH v3 1/3] sh: add __NR_syscalls along with NR_syscalls

Hi Arnd,

On Mon, 19 Nov 2018 at 22:21, Arnd Bergmann <arnd@...db.de> wrote:
>
> On Wed, Nov 14, 2018 at 5:32 AM Firoz Khan <firoz.khan@...aro.org> wrote:
> >
> > NR_syscalls macro holds the number of system call exist
> > in sh architecture. We have to change the value of NR-
> > _syscalls, if we add or delete a system call.
> >
> > One of the patch in this patch series has a script which
> > will generate a uapi header based on syscall.tbl file.
> > The syscall.tbl file contains the total number of system
> > calls information. So we have two option to update NR_sy-
> > scalls value.
> >
> > 1. Update NR_syscalls in asm/unistd.h manually by count-
> >    ing the no.of system calls. No need to update NR_sys-
> >    calls until we either add a new system call or delete
> >    existing system call.
> >
> > 2. We can keep this feature it above mentioned script,
> >    that will count the number of syscalls and keep it in
> >    a generated file. In this case we don't need to expli-
> >    citly update NR_syscalls in asm/unistd.h file.
> >
> > The 2nd option will be the recommended one. For that, I
> > added the __NR_syscalls macro in uapi/asm/unistd_32/64.h
> > along with NR_syscalls which is moved to asm/unistd.h.
> > The macro __NR_syscalls also added for making the name
> > convention same across all architecture. While __NR_sys-
> > calls isn't strictly part of the uapi, having it as part
> > of the generated header to simplifies the implementation.
> > We also need to enclose this macro with #ifdef __KERNEL__
> > to avoid side effects.
> >
> > Signed-off-by: Firoz Khan <firoz.khan@...aro.org>
>
> Looks correct to me, but since there are only three references to
> 'NR_syscalls' in arch/sh, I wonder if we should just replace it with
> __NR_syscalls in the same patch.

This is the approach I had initially, But someone pointed out that doing
this way - #define NR_syscalls    __NR_syscalls would be better. The
only difference is here the number of occurrence 3 and there 5-7
occurrence of NR_syscalls.

Thanks
Firoz

>
>        Arnd