From: Christian Brauner <brauner@kernel.org>
To: Tycho Andersen <tycho@tycho.pizza>
Cc: Oleg Nesterov <oleg@redhat.com>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
Tycho Andersen <tandersen@netflix.com>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH v3 1/3] pidfd: allow pidfd_open() on non-thread-group leaders
Date: Fri, 26 Jan 2024 10:49:02 +0100 [thread overview]
Message-ID: <20240126-indiz-radrennen-8554de0bc074@brauner> (raw)
In-Reply-To: <ZbKqQl39WlqX8dgp@tycho.pizza>
On Thu, Jan 25, 2024 at 11:36:50AM -0700, Tycho Andersen wrote:
> On Thu, Jan 25, 2024 at 07:30:46PM +0100, Oleg Nesterov wrote:
> > On 01/25, Oleg Nesterov wrote:
> > >
> > > On 01/25, Tycho Andersen wrote:
> > > >
> > > > One of the things I don't like about PIDFD_THREAD is that it's hard to
> > > > tell whether an arbitrary thread is a leader or not. Right now we do
> > > > it by parsing /proc/pid/status, which shows all the stuff from
> > > > do_task_stat() that we don't care about but which is quite expensive
> > > > to compute. (Maybe there's a better way?)
> > > >
> > > > With PIDFD_THREAD we could could do it twice, once with the flag, get
> > > > EINVAL, and then do it again. But ideally we wouldn't have to.
> > >
> > > Too late for me, most probably I misunderstood.
> > >
> > > If you want the PIDFD_THREAD behaviour, you can always use this flag
> > > without any check...
>
> Sorry, I hadn't read the patch. If it's ok to use PIDFD_THREAD on a
> leader, then we can just always specify it. (We don't care about the
> behavior of pidfd_poll().)
>
> > > Could you spell?
> >
> > Just in case, we can even add PIDFD_AUTO (modulo naming) which acts as
> > PIDFD_THREAD if the target task is not a leader or 0 (current behaviour)
> > otherwise. Trivial.
>
> Yep, or given the above, maybe it'll work as-is, thank you.
Yes, let's rather do the explicit PIDFD_THREAD.
next prev parent reply other threads:[~2024-01-26 9:49 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-23 15:34 [PATCH v3 0/3] pidfds for non thread group leaders Tycho Andersen
2024-01-23 15:34 ` [PATCH v3 1/3] pidfd: allow pidfd_open() on non-thread-group leaders Tycho Andersen
2024-01-23 19:56 ` Oleg Nesterov
2024-01-23 21:10 ` Tycho Andersen
2024-01-23 22:22 ` Oleg Nesterov
2024-01-24 1:25 ` Oleg Nesterov
2024-01-25 14:08 ` Oleg Nesterov
2024-01-25 17:17 ` Christian Brauner
2024-01-25 17:51 ` Oleg Nesterov
2024-01-25 18:03 ` Tycho Andersen
2024-01-25 18:25 ` Oleg Nesterov
2024-01-25 18:30 ` Oleg Nesterov
2024-01-25 18:36 ` Tycho Andersen
2024-01-26 9:49 ` Christian Brauner [this message]
2024-01-26 9:42 ` Christian Brauner
2024-01-26 14:33 ` Oleg Nesterov
2024-01-26 9:47 ` Christian Brauner
2024-01-26 14:33 ` Oleg Nesterov
2024-01-27 14:26 ` Christian Brauner
2024-01-26 21:50 ` Tycho Andersen
2024-01-27 10:54 ` Oleg Nesterov
2024-01-27 14:33 ` Christian Brauner
2024-01-27 15:55 ` Tycho Andersen
2024-01-27 16:31 ` Oleg Nesterov
2024-01-27 17:20 ` Tycho Andersen
2024-01-27 19:31 ` Oleg Nesterov
2024-01-27 20:44 ` Tycho Andersen
2024-01-27 21:10 ` Oleg Nesterov
2024-01-29 11:23 ` [RFC PATCH] pidfd: implement PIDFD_THREAD flag for pidfd_open() Oleg Nesterov
2024-01-29 13:41 ` Christian Brauner
2024-01-29 14:31 ` Tycho Andersen
2024-01-29 15:14 ` Christian Brauner
2024-01-30 11:21 ` Oleg Nesterov
2024-01-31 18:11 ` Andy Lutomirski
2024-01-31 18:48 ` Oleg Nesterov
2024-01-31 19:14 ` Oleg Nesterov
2024-01-31 19:24 ` Andy Lutomirski
2024-01-31 19:46 ` Christian Brauner
2024-01-31 19:50 ` Andy Lutomirski
2024-02-01 13:30 ` Christian Brauner
2024-02-01 13:39 ` Christian Brauner
2024-02-01 19:33 ` Andy Lutomirski
2024-01-23 15:34 ` [PATCH v3 2/3] selftests/pidfd: add non-thread-group leader tests Tycho Andersen
2024-01-23 15:34 ` [PATCH v3 3/3] clone: allow CLONE_THREAD | CLONE_PIDFD together Tycho Andersen
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