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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Ingo Molnar <mingo@kernel.org>,
	Jan Kratochvil <jan.kratochvil@redhat.com>,
	Pedro Alves <palves@redhat.com>, Peter Anvin <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"the arch/x86 maintainers" <x86@kernel.org>
Subject: Re: [PATCH] ptrace/x86: introduce TS_COMPAT_RESTART to fix get_nr_restart_syscall()
Date: Tue, 26 Nov 2019 20:04:08 -0800	[thread overview]
Message-ID: <CAHk-=whrhuNg_53wc3pBVToH-AUwKDbC5P_cb7=8bYfn=BYCJA@mail.gmail.com> (raw)
In-Reply-To: <20191126110758.GA14051@redhat.com>

On Tue, Nov 26, 2019 at 3:08 AM Oleg Nesterov <oleg@redhat.com> wrote:
>
> Alternatively we could add ->compat_restart into struct restart_block,
> logically this is the same thing.

That sounds like the better model to me. That's what the restart_block
is about: it's supposed to contain the restart information.

I'd much rather see the system call number added into the restart
block (or just the "compat bit" - but we have that X32 case too, so
why not put it all there). And then the get_nr_restart_syscall() hack
goes away and is just "set state from the restart block".

How painful would that be? I guess right now we always just set all
the restart_block info manually in all the restart cases, and that
could make it a bit painful to add this kind of architecture-specific
flag, but it _sounds_ conceptually like the right thing to do.

I definitely don't love the "magic sticky bit in thread status" field model.

             Linus

  reply	other threads:[~2019-11-27  4:04 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-26 11:06 [PATCH] ptrace/x86: introduce TS_COMPAT_RESTART to fix get_nr_restart_syscall() Oleg Nesterov
2019-11-26 11:07 ` Oleg Nesterov
2019-11-27  4:04   ` Linus Torvalds [this message]
2019-11-27  5:46     ` Andy Lutomirski
2019-11-27 17:06       ` Oleg Nesterov
2019-11-27 17:02     ` Oleg Nesterov
2019-11-27 17:21       ` Linus Torvalds
2019-11-28 15:36         ` Oleg Nesterov
2019-11-28 19:24           ` Linus Torvalds
2019-11-28 21:13             ` Andy Lutomirski
2019-11-29 17:32               ` Oleg Nesterov
2019-11-29 18:19                 ` Andy Lutomirski
2019-11-29 17:21             ` Oleg Nesterov
2019-12-03 14:12 ` [PATCH v2 0/4] x86: " Oleg Nesterov
2019-12-03 14:13   ` [PATCH v2 1/4] introduce set_restart_fn() and arch_set_restart_data() Oleg Nesterov
2019-12-04 15:09     ` Oleg Nesterov
2019-12-04 15:09     ` [PATCH v3 " Oleg Nesterov
2019-12-03 14:13   ` [PATCH v2 2/4] x86: mv TS_COMPAT from asm/processor.h to asm/thread_info.h Oleg Nesterov
2019-12-03 14:13   ` [PATCH v2 3/4] x86: introduce TS_COMPAT_RESTART to fix get_nr_restart_syscall() Oleg Nesterov
2019-12-03 14:14   ` [PATCH v2 4/4] x86: introduce restart_block->arch_data to kill TS_COMPAT_RESTART Oleg Nesterov
2019-12-18 15:19   ` [PATCH v2 0/4] x86: fix get_nr_restart_syscall() Oleg Nesterov
2019-12-18 20:02     ` Linus Torvalds
2019-12-19  2:48       ` Andy Lutomirski
2020-02-17 15:54         ` Thomas Gleixner

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