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

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Message-ID: <20191203141239.GA30688@redhat.com>
Date:   Tue, 3 Dec 2019 15:12:39 +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: [PATCH v2 0/4] x86: fix get_nr_restart_syscall()

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(-)