From: ebiederm@xmission.com (Eric W. Biederman)
To: Oleg Nesterov <oleg@redhat.com>
Cc: "Jürg Billeter" <j@bitron.ch>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Kees Cook" <keescook@chromium.org>,
"Andy Lutomirski" <luto@kernel.org>,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT
Date: Wed, 28 Nov 2018 09:23:39 -0600 [thread overview]
Message-ID: <87r2f5gr9g.fsf@xmission.com> (raw)
In-Reply-To: <20181128144230.GG30395@redhat.com> (Oleg Nesterov's message of "Wed, 28 Nov 2018 15:42:31 +0100")
Oleg Nesterov <oleg@redhat.com> writes:
> On 11/27, Jürg Billeter wrote:
>>
>> @@ -704,6 +713,9 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
>> struct task_struct *p, *n;
>> LIST_HEAD(dead);
>>
>> + if (group_dead && tsk->signal->kill_descendants_on_exit)
>> + walk_process_tree(tsk, kill_descendant_visitor, NULL);
>
> Well, this is not exactly right, at least this is suboptimal in that
> other sub-threads can too call walk_process_tree(kill_descendant_visitor)
> later for no reason.
Oleg I think I am missing something.
Reading kernel/exit.c I see "group_dead = atomic_dec_and_test(&tsk->signal->live)".
Which seems like enough to ensure exactly one task/thread calls walk_process_tree.
Can you explain what I am missing?
Eric
next prev parent reply other threads:[~2018-11-28 15:23 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-27 22:54 [PATCH 0/1] Add prctl to kill descendants on exit Jürg Billeter
2018-11-27 22:54 ` [PATCH] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT Jürg Billeter
2018-11-28 14:42 ` Oleg Nesterov
2018-11-28 15:23 ` Eric W. Biederman [this message]
2018-11-29 12:34 ` Oleg Nesterov
2018-11-29 15:41 ` Jürg Billeter
2018-11-30 10:33 ` Oleg Nesterov
2018-12-01 4:28 ` Kees Cook
2018-11-30 8:00 ` [PATCH v2 0/1] Add prctl to kill descendants on exit Jürg Billeter
2018-11-30 8:00 ` [PATCH v2 1/1] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT Jürg Billeter
2018-11-30 11:22 ` Oleg Nesterov
2018-11-30 13:40 ` Florian Weimer
2018-12-01 10:39 ` Jürg Billeter
2018-12-01 12:28 ` Florian Weimer
2018-12-01 13:57 ` Jürg Billeter
2018-12-06 15:54 ` [PATCH v2 0/1] Add prctl to kill descendants on exit Jürg Billeter
2019-01-18 13:11 ` [RESEND PATCH " Jürg Billeter
2019-01-18 13:11 ` [RESEND PATCH v2 1/1] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT Jürg Billeter
2019-01-29 1:23 ` Andrew Morton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87r2f5gr9g.fsf@xmission.com \
--to=ebiederm@xmission.com \
--cc=akpm@linux-foundation.org \
--cc=j@bitron.ch \
--cc=keescook@chromium.org \
--cc=linux-api@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=oleg@redhat.com \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.