From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Jim Newsome <jnewsome@torproject.org>,
Andrew Morton <akpm@linux-foundation.org>,
Christian Brauner <christian@brauner.io>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] do_wait: make PIDTYPE_PID case O(1) instead of O(n)
Date: Thu, 11 Mar 2021 16:08:21 +0100 [thread overview]
Message-ID: <20210311150820.GA15552@redhat.com> (raw)
In-Reply-To: <m1blbqmy2u.fsf@fess.ebiederm.org>
On 03/10, Eric W. Biederman wrote:
>
> Jim Newsome <jnewsome@torproject.org> writes:
>
> > +static int do_wait_pid(struct wait_opts *wo)
> > +{
> > + struct task_struct *target = pid_task(wo->wo_pid, PIDTYPE_PID);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This is subtle change in behavior.
>
> Today on the task->children list we only place thread group leaders.
Aaah, yes, thanks Eric!
> So the code either needs a thread_group_leader filter on target before
> the ptrace=0 case or we need to use "pid_task(wo->wo_pid, PIDTYPE_TGID)"
> and "pid_task(wo->wo_pid, PIDTYPE_PID)" for the "ptrace=1" case.
Agreed,
> I would like to make thread_group_leaders go away
Hmm, why?
Oleg.
next prev parent reply other threads:[~2021-03-11 15:09 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 20:39 [PATCH v3] do_wait: make PIDTYPE_PID case O(1) instead of O(n) Jim Newsome
2021-03-10 17:27 ` Oleg Nesterov
2021-03-10 22:40 ` Eric W. Biederman
2021-03-11 0:14 ` Jim Newsome
2021-03-11 15:15 ` Oleg Nesterov
2021-03-11 16:26 ` Jim Newsome
2021-03-11 16:30 ` Eric W. Biederman
2021-03-11 15:08 ` Oleg Nesterov [this message]
2021-03-11 16:37 ` Eric W. Biederman
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