linux-kernel - Re: [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor

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Message-ID: <556818A7.3030804@redhat.com>
Date:	Fri, 29 May 2015 09:43:35 +0200
From:	Florian Weimer <fweimer@...hat.com>
To:	Josh Triplett <josh@...htriplett.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Kees Cook <keescook@...omium.org>,
	Oleg Nesterov <oleg@...hat.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	"H. Peter Anvin" <hpa@...or.com>, Rik van Riel <riel@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Thiago Macieira <thiago.macieira@...el.com>,
	linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor

On 03/15/2015 08:59 AM, Josh Triplett wrote:
> This patch series introduces a new clone flag, CLONE_FD, which lets the caller
> receive child process exit notification via a file descriptor rather than
> SIGCHLD.  CLONE_FD makes it possible for libraries to safely launch and manage
> child processes on behalf of their caller, *without* taking over process-wide
> SIGCHLD handling (either via signal handler or signalfd).
> 
> Note that signalfd for SIGCHLD does not suffice here, because that still
> receives notification for all child processes, and interferes with process-wide
> signal handling.

It has been suggested (e.g.,
<https://sourceware.org/bugzilla/show_bug.cgi?id=15661#c3>) that you can
use the existing clone(2) without specifying SIGCHLD to create a new
process.  The resulting child process is not supposed to show up in
wait(2), only in a waitpid(2) (or similar) explicitly specifying the
PID.  Is this not the case?

-- 
Florian Weimer / Red Hat Product Security
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