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Date: Fri, 29 May 2015 09:43:35 +0200
From: Florian Weimer <fweimer@redhat.com>
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To: Josh Triplett <josh@joshtriplett.org>, Al Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
        Kees Cook <keescook@chromium.org>, 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>,
        Thiago Macieira <thiago.macieira@intel.com>,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor
References: <cover.1426376419.git.josh@joshtriplett.org>
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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