From: Oleg Nesterov <oleg@redhat.com>
To: Christian Brauner <christian@brauner.io>
Cc: linux-kernel@vger.kernel.org, arnd@arndb.de,
ebiederm@xmission.com, keescook@chromium.org,
joel@joelfernandes.org, tglx@linutronix.de, tj@kernel.org,
dhowells@redhat.com, jannh@google.com, luto@kernel.org,
akpm@linux-foundation.org, cyphar@cyphar.com,
torvalds@linux-foundation.org, viro@zeniv.linux.org.uk,
kernel-team@android.com, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-api@vger.kernel.org
Subject: Re: [PATCH 4/5] pidfd: add CLONE_WAIT_PID
Date: Thu, 25 Jul 2019 13:43:59 +0200 [thread overview]
Message-ID: <20190725114359.GH4707@redhat.com> (raw)
In-Reply-To: <20190725112503.GG4707@redhat.com>
Or. We can change wait_consider_task() to not clear ->notask_error if
WXXX and the child is PF_WAIT_PID.
This way you can "safely" use wait() without WNOHANG, it won't block if
all the children which can report an even are PF_WAIT_PID.
But I do not understand your use-cases, I have no idea if this can help
or not. Just I think the more discussion is always better when we are
going to add the new API.
On 07/25, Oleg Nesterov wrote:
>
> On 07/25, Christian Brauner wrote:
> >
> > On Thu, Jul 25, 2019 at 12:35:44PM +0200, Oleg Nesterov wrote:
> > >
> > > I have to admit this feature looks a bit exotic to me...
> >
> > It might look like it from the kernels perspective but from the feedback
> > on this when presenting on this userspace has real usecases for this.
>
> OK...
>
> but then perhaps we can make PF_WAIT_PID more flexible.
>
> Say, we can add the new WXXX wait option and change eligible_child()
>
> if ((p->flags & PF_WAIT_PID) && (wo->options & WXXX))
> return 0;
>
> this way the parent can tell waitid() whether the PF_WAIT_PID tasks should
> be filtered or not.
>
> And if we do this we can even add PR_SET_WAIT_PID/PR_CLR_WAIT_PID instead
> of the new CLONE_ flag.
>
> Oleg.
next prev parent reply other threads:[~2019-07-25 11:44 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-24 14:46 [PATCH 0/5] pidfd: waiting on processes through pidfds Christian Brauner
2019-07-24 14:46 ` [RFC][PATCH 1/5] exit: kill struct waitid_info Christian Brauner
2019-07-24 17:37 ` Linus Torvalds
2019-07-24 22:01 ` Christian Brauner
2019-07-25 12:46 ` Eric W. Biederman
2019-07-26 8:01 ` Christian Brauner
2019-07-26 11:59 ` Eric W. Biederman
2019-07-26 12:37 ` Christian Brauner
2019-07-25 9:40 ` Oleg Nesterov
2019-07-25 10:07 ` Christian Brauner
2019-07-24 14:46 ` [PATCH 2/5] pidfd: add pidfd_wait() Christian Brauner
2019-07-24 17:45 ` Linus Torvalds
2019-07-24 17:50 ` Christian Brauner
2019-07-24 17:52 ` Christian Brauner
2019-07-25 14:34 ` Eric W. Biederman
2019-07-25 10:16 ` Oleg Nesterov
2019-07-25 10:21 ` Christian Brauner
2019-07-26 8:19 ` Arnd Bergmann
2019-07-26 8:24 ` Christian Brauner
2019-07-26 9:57 ` Arnd Bergmann
2019-07-24 14:46 ` [PATCH 3/5] arch: wire-up pidfd_wait() Christian Brauner
2019-07-24 14:46 ` [PATCH 4/5] pidfd: add CLONE_WAIT_PID Christian Brauner
2019-07-24 18:14 ` Jann Horn
2019-07-24 18:27 ` Christian Brauner
2019-07-24 19:07 ` Jann Horn
2019-07-24 19:10 ` Christian Brauner
2019-07-25 10:11 ` Christian Brauner
2019-07-25 10:30 ` Oleg Nesterov
2019-07-25 10:36 ` Christian Brauner
2019-07-25 10:35 ` Oleg Nesterov
2019-07-25 10:40 ` Christian Brauner
2019-07-25 11:25 ` Oleg Nesterov
2019-07-25 11:41 ` Christian Brauner
2019-07-25 11:43 ` Oleg Nesterov [this message]
2019-07-25 12:26 ` Christian Brauner
2019-07-25 16:13 ` Oleg Nesterov
2019-07-25 16:56 ` Christian Brauner
2019-07-25 16:57 ` Eric W. Biederman
2019-07-24 14:46 ` [PATCH 5/5] pidfd: add pidfd_wait tests Christian Brauner
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