From: Thiago Macieira <thiago.macieira@intel.com>
To: josh@joshtriplett.org
Cc: Kees Cook <keescook@chromium.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Oleg Nesterov <oleg@redhat.com>,
"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>,
Michael Kerrisk <mtk.manpages@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>
Subject: Re: [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor
Date: Mon, 16 Mar 2015 17:49:52 -0700 [thread overview]
Message-ID: <4157103.KzTpXff0QK@tjmaciei-mobl4> (raw)
In-Reply-To: <20150316232949.GB31751@cloud>
On Monday 16 March 2015 16:29:49 josh@joshtriplett.org wrote:
> > A child without CLONE_AUTOREAP should be wait()able. If it gets wait()ed
> > before the clonefd is read, the clonefd() will return a 0 read. If it
> > gets
> > read before wait, then wait() reaps another child or returns -ECHILD.
> > That's no different than two threads doing simultaneous wait() on the
> > same child.
> Hrm? That isn't the semantics we implemented; you'll *always* get an
> exit notification via the clonefd if you have it open, with or without
> autoreap and whether or not a wait has occurred yet. And reading from
> the clonefd does not serve as a wait; if you don't pass CLONE_AUTOREAP,
> you'll still need to wait on the process.
Ah, I see what you're saying. Ok, I stand corrected: a child without
CLONE_AUTOREAP must be wait()ed on and whoever waits on it will get
information. In addition to that, the information is available on the clonefd
and it can happen at any time, before or after the wait().
In the case of an orphaned child, the file descriptor will close, that's all.
No modification is necessary to init.
--
Thiago Macieira - thiago.macieira (AT) intel.com
Software Architect - Intel Open Source Technology Center
next prev parent reply other threads:[~2015-03-17 0:50 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-15 7:59 [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor Josh Triplett
2015-03-15 7:59 ` [PATCH v2 1/7] clone: Support passing tls argument via C rather than pt_regs magic Josh Triplett
2015-03-15 7:59 ` [PATCH v2 2/7] x86: Opt into HAVE_COPY_THREAD_TLS, for both 32-bit and 64-bit Josh Triplett
2015-03-15 7:59 ` [PATCH v2 3/7] Introduce a new clone4 syscall with more flag bits and extensible arguments Josh Triplett
2015-03-23 14:11 ` David Drysdale
2015-03-23 15:05 ` josh
2015-03-31 14:41 ` David Drysdale
2015-03-15 7:59 ` [PATCH v2 4/7] kernel/fork.c: Pass arguments to _do_fork and copy_process using clone4_args Josh Triplett
2015-03-15 8:00 ` [PATCH v2 5/7] clone4: Add a CLONE_AUTOREAP flag to automatically reap the child process Josh Triplett
2015-03-15 14:52 ` Oleg Nesterov
2015-03-15 17:18 ` Josh Triplett
2015-03-15 19:55 ` Oleg Nesterov
2015-03-15 23:34 ` Josh Triplett
2015-03-20 18:14 ` Oleg Nesterov
2015-03-20 18:46 ` Thiago Macieira
2015-03-20 19:09 ` Oleg Nesterov
2015-03-20 21:10 ` josh
2015-03-15 8:00 ` [PATCH v2 6/7] signal: Factor out a helper function to process task_struct exit_code Josh Triplett
2015-03-15 8:00 ` [PATCH v2 7/7] clone4: Add a CLONE_FD flag to get task exit notification via fd Josh Triplett
2015-03-23 17:38 ` David Drysdale
2015-03-25 14:53 ` Josh Triplett
2015-04-06 8:30 ` Sergey Senozhatsky
2015-04-06 9:31 ` Josh Triplett
2015-03-15 8:00 ` [PATCH v2 man-pages] clone4.2: New manpage documenting clone4(2) Josh Triplett
2015-03-15 8:04 ` [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor Josh Triplett
2015-03-16 21:44 ` Kees Cook
2015-03-16 22:14 ` Thiago Macieira
2015-03-16 22:36 ` Kees Cook
2015-03-16 22:50 ` Thiago Macieira
2015-03-16 23:26 ` Kees Cook
2015-03-16 23:35 ` josh
2015-03-16 23:29 ` josh
2015-03-17 0:49 ` Thiago Macieira [this message]
2015-03-23 14:12 ` David Drysdale
2015-03-23 15:03 ` josh
2015-03-16 23:25 ` josh
2015-03-31 20:08 ` Jonathan Corbet
2015-03-31 22:02 ` josh
2015-04-01 7:24 ` Jonathan Corbet
2015-04-09 2:19 ` Josh Triplett
2015-05-29 7:43 ` Florian Weimer
2015-05-29 20:27 ` Thiago Macieira
2015-06-15 10:06 ` Florian Weimer
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