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From: josh@joshtriplett.org
To: Andy Lutomirski <luto@amacapital.net>
Cc: Oleg Nesterov <oleg@redhat.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>, Kees Cook <keescook@chromium.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Rik van Riel <riel@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Thiago Macieira <thiago.macieira@intel.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>,
	X86 ML <x86@kernel.org>
Subject: Re: [PATCH 6/6] clone4: Introduce new CLONE_FD flag to get task exit notification via fd
Date: Fri, 13 Mar 2015 15:34:09 -0700	[thread overview]
Message-ID: <20150313223409.GE10954@cloud> (raw)
In-Reply-To: <CALCETrVRqgsbpi9pPRwy42cuXiDzyPgWRJmfSRSQM7eGFfsZYA@mail.gmail.com>

On Fri, Mar 13, 2015 at 03:28:26PM -0700, Andy Lutomirski wrote:
> On Fri, Mar 13, 2015 at 3:20 PM,  <josh@joshtriplett.org> wrote:
> > On Fri, Mar 13, 2015 at 02:34:58PM -0700, Andy Lutomirski wrote:
> >> On Fri, Mar 13, 2015 at 12:57 PM,  <josh@joshtriplett.org> wrote:
> >> > A process launching a new process with CLONE_FD is explicitly requesting
> >> > that the process be automatically reaped without any other process
> >> > having to wait on it.  The task needs to not become a zombie, because
> >> > otherwise, it'll show up in waitpid(-1, ...) calls in the parent
> >> > process, which would break the ability to use this to completely
> >> > encapsulate process management within a library and not interfere with
> >> > the parent's process handling via SIGCHLD and wait{pid,3,4}.
> >>
> >> Wouldn't the correct behavior be to keep it alive as a zombie but
> >> *not* show it in waitpid, etc?
> >
> > That's a significant change to the semantics of waitpid.  And then
> > someone would still need to wait on the process, which we'd like to
> > avoid.  (We don't want to have magic "reap on read(2)" semantics,
> > because among other things, what if we add a means in the future to get
> > an additional file descriptor corresponding to an existing process?)
> 
> Do we not already have a state "dead, successfully waited on by
> parent, but still around because ptraced"?  If not, shouldn't we?
> Isn't that what PTRACE_SEIZE does?  Or am I just confused?

I don't think that affects the task's exit_state though.

- Josh Triplett

WARNING: multiple messages have this Message-ID (diff)
From: josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org
To: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
Cc: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
	"Paul E. McKenney"
	<paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>,
	"H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>,
	Rik van Riel <riel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
	Thiago Macieira
	<thiago.macieira-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Michael Kerrisk
	<mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Linux API <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Linux FS Devel
	<linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	X86 ML <x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH 6/6] clone4: Introduce new CLONE_FD flag to get task exit notification via fd
Date: Fri, 13 Mar 2015 15:34:09 -0700	[thread overview]
Message-ID: <20150313223409.GE10954@cloud> (raw)
In-Reply-To: <CALCETrVRqgsbpi9pPRwy42cuXiDzyPgWRJmfSRSQM7eGFfsZYA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Fri, Mar 13, 2015 at 03:28:26PM -0700, Andy Lutomirski wrote:
> On Fri, Mar 13, 2015 at 3:20 PM,  <josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org> wrote:
> > On Fri, Mar 13, 2015 at 02:34:58PM -0700, Andy Lutomirski wrote:
> >> On Fri, Mar 13, 2015 at 12:57 PM,  <josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org> wrote:
> >> > A process launching a new process with CLONE_FD is explicitly requesting
> >> > that the process be automatically reaped without any other process
> >> > having to wait on it.  The task needs to not become a zombie, because
> >> > otherwise, it'll show up in waitpid(-1, ...) calls in the parent
> >> > process, which would break the ability to use this to completely
> >> > encapsulate process management within a library and not interfere with
> >> > the parent's process handling via SIGCHLD and wait{pid,3,4}.
> >>
> >> Wouldn't the correct behavior be to keep it alive as a zombie but
> >> *not* show it in waitpid, etc?
> >
> > That's a significant change to the semantics of waitpid.  And then
> > someone would still need to wait on the process, which we'd like to
> > avoid.  (We don't want to have magic "reap on read(2)" semantics,
> > because among other things, what if we add a means in the future to get
> > an additional file descriptor corresponding to an existing process?)
> 
> Do we not already have a state "dead, successfully waited on by
> parent, but still around because ptraced"?  If not, shouldn't we?
> Isn't that what PTRACE_SEIZE does?  Or am I just confused?

I don't think that affects the task's exit_state though.

- Josh Triplett

  reply	other threads:[~2015-03-13 22:34 UTC|newest]

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-13  1:40 [PATCH 0/6] CLONE_FD: Task exit notification via file descriptor Josh Triplett
2015-03-13  1:40 ` Josh Triplett
2015-03-13  1:40 ` [PATCH 1/6] clone: Support passing tls argument via C rather than pt_regs magic Josh Triplett
2015-03-13  1:40 ` [PATCH 2/6] x86: Opt into HAVE_COPY_THREAD_TLS, for both 32-bit and 64-bit Josh Triplett
2015-03-13  1:40   ` Josh Triplett
2015-03-13 22:01   ` Andy Lutomirski
2015-03-13 22:01     ` Andy Lutomirski
2015-03-13 22:31     ` josh
2015-03-13 22:38       ` Andy Lutomirski
2015-03-13 22:43         ` josh
2015-03-13 22:43           ` josh-iaAMLnmF4UmaiuxdJuQwMA
2015-03-13 22:45           ` Andy Lutomirski
2015-03-13 22:45             ` Andy Lutomirski
2015-03-13 23:01             ` josh
2015-03-13 23:01               ` josh-iaAMLnmF4UmaiuxdJuQwMA
2015-03-13  1:40 ` [PATCH 3/6] Introduce a new clone4 syscall with more flag bits and extensible arguments Josh Triplett
2015-03-13  1:40 ` [PATCH 4/6] signal: Factor out a helper function to process task_struct exit_code Josh Triplett
2015-03-13  1:40 ` [PATCH 5/6] fs: Make alloc_fd non-private Josh Triplett
2015-03-13  1:40   ` Josh Triplett
2015-03-13  1:41 ` [PATCH 6/6] clone4: Introduce new CLONE_FD flag to get task exit notification via fd Josh Triplett
2015-03-13 16:21   ` Oleg Nesterov
2015-03-13 19:57     ` josh
2015-03-13 21:34       ` Andy Lutomirski
2015-03-13 21:34         ` Andy Lutomirski
2015-03-13 22:20         ` josh
2015-03-13 22:28           ` Andy Lutomirski
2015-03-13 22:28             ` Andy Lutomirski
2015-03-13 22:34             ` josh [this message]
2015-03-13 22:34               ` josh-iaAMLnmF4UmaiuxdJuQwMA
2015-03-13 22:38               ` Andy Lutomirski
2015-03-14 14:14       ` Oleg Nesterov
2015-03-14 14:14         ` Oleg Nesterov
2015-03-14 14:32         ` Oleg Nesterov
2015-03-14 14:32           ` Oleg Nesterov
2015-03-14 18:38           ` Thiago Macieira
2015-03-14 18:54             ` Oleg Nesterov
2015-03-14 22:03               ` Josh Triplett
2015-03-14 22:03                 ` Josh Triplett
2015-03-14 22:26                 ` Thiago Macieira
2015-03-14 19:01             ` Josh Triplett
2015-03-14 19:18               ` Oleg Nesterov
2015-03-14 19:18                 ` Oleg Nesterov
2015-03-14 19:47                 ` Oleg Nesterov
2015-03-14 19:47                   ` Oleg Nesterov
2015-03-14 20:14                   ` Josh Triplett
2015-03-14 20:14                     ` Josh Triplett
2015-03-14 20:30                     ` Oleg Nesterov
2015-03-14 22:14                       ` Josh Triplett
2015-03-14 22:14                         ` Josh Triplett
2015-03-14 20:03                 ` Josh Triplett
2015-03-14 20:03                   ` Josh Triplett
2015-03-14 20:20                   ` Oleg Nesterov
2015-03-14 22:09         ` Josh Triplett
2015-03-14 14:35   ` Oleg Nesterov
2015-03-14 14:35     ` Oleg Nesterov
2015-03-14 19:15     ` Josh Triplett
2015-03-14 19:15       ` Josh Triplett
2015-03-14 19:24       ` Oleg Nesterov
2015-03-14 19:48         ` Josh Triplett
2015-03-14 19:48           ` Josh Triplett
2015-03-13  1:41 ` [PATCH] clone4.2: New manpage documenting clone4(2) Josh Triplett
2015-03-13  2:07 ` [PATCH 0/6] CLONE_FD: Task exit notification via file descriptor Thiago Macieira
2015-03-13  2:07   ` Thiago Macieira
2015-03-13 16:05 ` David Drysdale
2015-03-13 16:05   ` David Drysdale
2015-03-13 19:42   ` Josh Triplett
2015-03-13 21:16     ` Thiago Macieira
2015-03-13 21:44       ` josh
2015-03-13 21:33     ` Andy Lutomirski
2015-03-13 21:45       ` josh
2015-03-13 21:45         ` josh-iaAMLnmF4UmaiuxdJuQwMA
2015-03-13 21:51         ` Andy Lutomirski
2015-03-13 21:51           ` Andy Lutomirski
2015-03-14  1:11           ` Thiago Macieira
2015-03-14  1:11             ` Thiago Macieira
2015-03-14 19:03             ` Thiago Macieira
2015-03-14 19:29               ` Josh Triplett
2015-03-14 19:29                 ` Josh Triplett
2015-03-15 10:18                 ` David Drysdale
2015-03-15 10:18                   ` David Drysdale
2015-03-15 10:59                   ` Josh Triplett
2015-03-15  8:55     ` David Drysdale
2015-03-15  8:55       ` David Drysdale

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