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From: "Jürg Billeter" <j@bitron.ch>
To: Florian Weimer <fweimer@redhat.com>,
	Christian Brauner <christian@brauner.io>
Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
	luto@kernel.org, arnd@arndb.de, ebiederm@xmission.com,
	serge@hallyn.com, jannh@google.com, akpm@linux-foundation.org,
	oleg@redhat.com, cyphar@cyphar.com, viro@zeniv.linux.org.uk,
	linux-fsdevel@vger.kernel.org, dancol@google.com,
	timmurray@google.com, linux-man@vger.kernel.org,
	keescook@chromium.org, tglx@linutronix.de, x86@kernel.org
Subject: Re: [PATCH v4] signal: add taskfd_send_signal() syscall
Date: Thu, 06 Dec 2018 13:45:39 +0100
Message-ID: <b0e946bcac12358841c9a99017da819b00794d9c.camel@bitron.ch> (raw)
In-Reply-To: <87h8fq7s84.fsf@oldenburg2.str.redhat.com>

On Thu, 2018-12-06 at 13:30 +0100, Florian Weimer wrote:
> * Christian Brauner:
> 
> > /* zombies */
> > Zombies can be signaled just as any other process. No special error will be
> > reported since a zombie state is an unreliable state (cf. [3]).
> 
> I still disagree with this analysis.  If I know that the target process
> is still alive, and it is not, this is a persistent error condition
> which can be reliably reported.  Given that someone might send SIGKILL
> to the process behind my back, detecting this error condition could be
> useful.

As I understand it, kill() behaves the same way. I think it's good that
this new syscall keeps the behavior as close as possible to kill().
E.g., this would allow emulating kill() (or a higher level API
equivalent) on top of taskfds without subtle differences in behavior.

As the new syscall supports flags, we could consider introducing a flag
that changes the behavior in the zombie case. However, I think that
should be a separate discussion (after merge of the syscall) and the
default behavior makes sense as is.

Jürg


  reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-06 12:18 Christian Brauner
2018-12-06 12:30 ` Florian Weimer
2018-12-06 12:45   ` Jürg Billeter [this message]
2018-12-06 13:12     ` Florian Weimer
2018-12-06 13:18       ` Jürg Billeter
2018-12-06 13:20         ` Florian Weimer
2018-12-06 13:40       ` Eric W. Biederman
2018-12-06 13:44         ` Florian Weimer
2018-12-06 14:27           ` Aleksa Sarai
2018-12-06 14:46           ` Eric W. Biederman
2018-12-06 12:53   ` Christian Brauner
2018-12-06 13:17     ` Florian Weimer
2018-12-06 15:01 ` Eric W. Biederman
2018-12-06 16:17   ` Daniel Colascione
2018-12-06 17:24     ` Eric W. Biederman
2018-12-06 17:41       ` Christian Brauner
2018-12-06 18:30         ` Kees Cook
2018-12-06 22:27           ` Serge E. Hallyn
2018-12-06 17:14   ` Christian Brauner
2018-12-06 19:17     ` Eric W. Biederman
2018-12-06 19:30       ` Christian Brauner
2018-12-06 20:29         ` Eric W. Biederman
2018-12-06 20:37           ` Daniel Colascione
2018-12-06 22:22             ` Eric W. Biederman
2018-12-06 22:43               ` Daniel Colascione
2018-12-06 21:31           ` Christian Brauner
2018-12-06 21:46             ` Eric W. Biederman
2018-12-06 22:01               ` Daniel Colascione
2018-12-06 22:39               ` Christian Brauner
2018-12-06 23:17                 ` Christian Brauner
2018-12-07  0:31                   ` Serge E. Hallyn
2018-12-07  0:34                     ` Daniel Colascione
2018-12-07  0:59                       ` Serge E. Hallyn
2018-12-07  1:39                         ` Daniel Colascione
2018-12-07  1:54                           ` Christian Brauner
2018-12-07 16:49                             ` Serge E. Hallyn
2018-12-07 16:47 ` Serge E. Hallyn
2018-12-08 21:46 ` kbuild test robot

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