From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5BCFC04EB8 for ; Thu, 6 Dec 2018 12:46:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 785FB20892 for ; Thu, 6 Dec 2018 12:46:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 785FB20892 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bitron.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729647AbeLFMp7 (ORCPT ); Thu, 6 Dec 2018 07:45:59 -0500 Received: from nov-007-i657.relay.mailchannels.net ([46.232.183.211]:37472 "EHLO nov-007-i657.relay.mailchannels.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729069AbeLFMp6 (ORCPT ); Thu, 6 Dec 2018 07:45:58 -0500 X-Sender-Id: novatrend|x-authuser|juerg@bitron.ch Received: from relay.mailchannels.net (localhost [127.0.0.1]) by relay.mailchannels.net (Postfix) with ESMTP id 9897BBE02DD; Thu, 6 Dec 2018 12:45:51 +0000 (UTC) Received: from srv17.tophost.ch (localhost [127.0.0.1]) by relay.mailchannels.net (Postfix) with ESMTPA id C7472BE0216; Thu, 6 Dec 2018 12:45:42 +0000 (UTC) X-Sender-Id: novatrend|x-authuser|juerg@bitron.ch Received: from srv17.tophost.ch (srv17.tophost.ch [193.33.128.141]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384) by 0.0.0.0:2500 (trex/5.15.2); Thu, 06 Dec 2018 12:45:51 +0000 X-MC-Relay: Neutral X-MailChannels-SenderId: novatrend|x-authuser|juerg@bitron.ch X-MailChannels-Auth-Id: novatrend X-Imminent-Fearful: 4550cf1558334c97_1544100350449_1137243920 X-MC-Loop-Signature: 1544100350449:922322940 X-MC-Ingress-Time: 1544100350448 Received: from [80.219.231.201] (port=47390 helo=jzen.bitron.ch) by srv17.tophost.ch with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from ) id 1gUt2C-00F9ZN-Et; Thu, 06 Dec 2018 13:45:40 +0100 Message-ID: Subject: Re: [PATCH v4] signal: add taskfd_send_signal() syscall From: =?ISO-8859-1?Q?J=FCrg?= Billeter To: Florian Weimer , Christian Brauner 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 Date: Thu, 06 Dec 2018 13:45:39 +0100 In-Reply-To: <87h8fq7s84.fsf@oldenburg2.str.redhat.com> References: <20181206121858.12215-1-christian@brauner.io> <87h8fq7s84.fsf@oldenburg2.str.redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.2 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-AuthUser: juerg@bitron.ch Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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