linux-kernel - Re: [PATCH 1/3] microblaze: Replace NR

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Date:   Thu, 9 Aug 2018 08:48:30 +0200
From:   Michal Simek <michal.simek@...inx.com>
To:     Firoz Khan <firoz.khan@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kate Stewart <kstewart@...uxfoundation.org>
CC:     <y2038@...ts.linaro.org>, <linux-kernel@...r.kernel.org>,
        <linux-arch@...r.kernel.org>, <arnd@...db.de>,
        <deepa.kernel@...il.com>, <marcin.juszkiewicz@...aro.org>
Subject: Re: [PATCH 1/3] microblaze: Replace NR_syscalls macro from
 asm/unistd.h

On 9.8.2018 07:27, Firoz Khan wrote:
> __NR_syscalls macro holds the number of system call exist in this
> architecture. This macro is currently the part of asm/unistd.h file.
> We have 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 number of system call information. So we have
> two option to update __NR_syscalls value.
> 
> 1. Update __NR_syscalls in asm/unistd.h manually by counting the
>    no.of system calls. No need to update __NR_syscalls untill
>    we either add a new system call or delete an existing system
>    call.
> 
> 2. We can keep this feature it above mentioned script, that'll
>    count the number of syscalls and keep it in a generated file.
>    In this case we don't need to explicitly update __NR_syscalls
>    in asm/unistd.h file.
> 
> The 2nd option will be the recommended one. For that, I moved the
> NR_syscalls macro from asm/unistd.h to uapi/asm/unistd.h. The macro
> name also changed form NR_syscalls to __NR_syscalls for making the
> name convention same across all architecture. While __NR_syscalls
> isn't strictly part of the uapi, having it as part of the generated
> header to simplifies the implementation.

This macro was in unistd.h in past but it was moved out because it was
causing problem with strace.

commit 40c2702a02b755e0183b702778331b351f3be20c
Author:     Michal Simek <michal.simek@...inx.com>
AuthorDate: Mon Jul 8 09:50:24 2013 +0200
Commit:     Michal Simek <michal.simek@...inx.com>
CommitDate: Wed Jul 10 07:32:09 2013 +0200

    microblaze: Move __NR_syscalls from uapi


That's why I don't think this is the right thing to do.
I have grepped strace and glibc and none is using this macro that's why
I think it shouldn't be exported via uapi.

Thanks,
Michal