linux-kernel - Re: [PATCH v2 0/4] x86: fix get_nr_restart

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Date:   Wed, 18 Dec 2019 16:19:04 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...en8.de>,
        Ingo Molnar <mingo@...nel.org>,
        Jan Kratochvil <jan.kratochvil@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Pedro Alves <palves@...hat.com>, Peter Anvin <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH v2 0/4] x86: fix get_nr_restart_syscall()

Andy, Linus, do you have any objections?

On 12/03, Oleg Nesterov wrote:
>
> This version follows the latest recommendation from Linus,
> arch_set_restart_data() just saves ti->status in restart->arch_data.
>
> Andy, I can add another patch or change 4/4 to save the syscall number
> instead, I am fine either way.
>
> However, personally I dislike restart->arch_data, imo 3/4 is all we need.
>
> I agree, set_restart_fn() is better than the ugly ERESTART_RESTARTBLOCK
> check in syscall_return_slowpath() added by v1. But to me the x86-only
> arch_data field in restart_block is much worse than the sticky TS_ flag.
>
> To remind, there is another reason for the "transient" 3/4, 4/4 is not
> easily backportable.
>
> Oleg.
> ---
>  arch/x86/include/asm/processor.h   |  9 ---------
>  arch/x86/include/asm/thread_info.h | 15 ++++++++++++++-
>  arch/x86/kernel/signal.c           | 24 +-----------------------
>  fs/select.c                        | 10 ++++------
>  include/linux/restart_block.h      |  1 +
>  include/linux/thread_info.h        | 12 ++++++++++++
>  kernel/futex.c                     |  3 +--
>  kernel/time/alarmtimer.c           |  2 +-
>  kernel/time/hrtimer.c              |  2 +-
>  kernel/time/posix-cpu-timers.c     |  2 +-
>  10 files changed, 36 insertions(+), 44 deletions(-)