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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 24 Jun 2021 13:11:18 -0700
Message-ID: <CAHk-=wg16ZBqtLngzE2edV8e68Qxje2kFehnKTrBBe5opcsj-w@mail.gmail.com>
Subject: Re: [PATCH 7/9] signal: Make individual tasks exiting a first class concept.
To:     "Eric W. Biederman" <ebiederm@xmission.com>
Cc:     Al Viro <viro@zeniv.linux.org.uk>,
        Michael Schmitz <schmitzmic@gmail.com>,
        linux-arch <linux-arch@vger.kernel.org>,
        Jens Axboe <axboe@kernel.dk>, Oleg Nesterov <oleg@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Richard Henderson <rth@twiddle.net>,
        Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
        Matt Turner <mattst88@gmail.com>,
        alpha <linux-alpha@vger.kernel.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        linux-m68k <linux-m68k@lists.linux-m68k.org>,
        Arnd Bergmann <arnd@kernel.org>,
        Ley Foon Tan <ley.foon.tan@intel.com>,
        Tejun Heo <tj@kernel.org>, Kees Cook <keescook@chromium.org>
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Precedence: bulk

On Thu, Jun 24, 2021 at 12:03 PM Eric W. Biederman
<ebiederm@xmission.com> wrote:
>
> Implement start_task_exit_locked and rewrite the de_thread logic
> in exec using it.
>
> Calling start_task_exit_locked is equivalent to asyncrhonously
> calling exit(2) aka pthread_exit on a task.

Ok, so this is the patch that makes me go "Yeah, this seems to all go together".

The whole "start_exit()" thing seemed fairly sane as an interesting
concept to the whole ptrace notification thing, but this one actually
made me think it makes conceptual sense and how we had exactly that
"start exit asynchronously" case already in zap_other_threads().

So doing that zap_other_threads() as that async exit makes me just
thin kthat yes, this series is the right thing, because it not only
cleans up the ptrace condition, it makes sense in this entirely
unrelated area too.

So I think I'm convinced. I'd like Oleg in particular to Ack this
series, and Al to look it over, but I do think this is the right
direction.

           Linus