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[209.132.180.67]) by mx.google.com with ESMTP id l194si407043pga.594.2018.12.06.06.53.05; Thu, 06 Dec 2018 06:53:20 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=xmission.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730140AbeLFOuk (ORCPT + 99 others); Thu, 6 Dec 2018 09:50:40 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:44743 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731382AbeLFOrM (ORCPT ); Thu, 6 Dec 2018 09:47:12 -0500 Received: from in01.mta.xmission.com ([166.70.13.51]) by out03.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1gUuvl-0006KF-SQ; Thu, 06 Dec 2018 07:47:09 -0700 Received: from ip68-227-174-240.om.om.cox.net ([68.227.174.240] helo=x220.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1gUuvk-0007EM-V4; Thu, 06 Dec 2018 07:47:09 -0700 From: ebiederm@xmission.com (Eric W. Biederman) To: Florian Weimer Cc: =?utf-8?Q?J=C3=BCrg?= Billeter , Christian Brauner , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, luto@kernel.org, arnd@arndb.de, 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 References: <20181206121858.12215-1-christian@brauner.io> <87h8fq7s84.fsf@oldenburg2.str.redhat.com> <87pnue6bp2.fsf@oldenburg2.str.redhat.com> <87efaun587.fsf@xmission.com> <877egm6a7v.fsf@oldenburg2.str.redhat.com> Date: Thu, 06 Dec 2018 08:46:57 -0600 In-Reply-To: <877egm6a7v.fsf@oldenburg2.str.redhat.com> (Florian Weimer's message of "Thu, 06 Dec 2018 14:44:36 +0100") Message-ID: <87bm5yiufy.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1gUuvk-0007EM-V4;;;mid=<87bm5yiufy.fsf@xmission.com>;;;hst=in01.mta.xmission.com;;;ip=68.227.174.240;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX19jtjKamkrEUK9Q6nfr2VyLBcCUuaxvkmM= X-SA-Exim-Connect-IP: 68.227.174.240 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on sa06.xmission.com X-Spam-Level: X-Spam-Status: No, score=-0.2 required=8.0 tests=ALL_TRUSTED,BAYES_50, DCC_CHECK_NEGATIVE,T_TM2_M_HEADER_IN_MSG,T_TooManySym_01, T_TooManySym_02 autolearn=disabled version=3.4.2 X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.5000] * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.0 T_TooManySym_02 5+ unique symbols in subject X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Florian Weimer X-Spam-Relay-Country: X-Spam-Timing: total 253 ms - load_scoreonly_sql: 0.03 (0.0%), signal_user_changed: 2.4 (1.0%), b_tie_ro: 1.71 (0.7%), parse: 0.82 (0.3%), extract_message_metadata: 2.4 (1.0%), get_uri_detail_list: 0.80 (0.3%), tests_pri_-1000: 4.0 (1.6%), tests_pri_-950: 1.22 (0.5%), tests_pri_-900: 1.07 (0.4%), tests_pri_-90: 20 (8.0%), check_bayes: 19 (7.4%), b_tokenize: 6 (2.4%), b_tok_get_all: 6 (2.5%), b_comp_prob: 1.94 (0.8%), b_tok_touch_all: 2.9 (1.1%), b_finish: 0.55 (0.2%), tests_pri_0: 204 (80.5%), check_dkim_signature: 0.48 (0.2%), check_dkim_adsp: 2.4 (1.0%), poll_dns_idle: 0.74 (0.3%), tests_pri_10: 2.4 (1.0%), tests_pri_500: 7 (2.9%), rewrite_mail: 0.00 (0.0%) Subject: Re: [PATCH v4] signal: add taskfd_send_signal() syscall X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Florian Weimer writes: > * Eric W. Biederman: > >> Floriam are you seeing a problem with this behavior or the way Christian >> was describing it? > > My hope is that you could use taskfd_send_signal one day to send a > signal to a process which you *known* (based on how you've written your > application) should be running and not in a zombie state, and get back > an error if it has exited. > > If you get this error, only then you wait on the process, using the file > descriptor you have, and run some recovery code. > > Wouldn't that be a reasonable approach once we've got task descriptors? Getting an error back if the target was a zombie does seem reasonable, as in principle it is an easy thing to notice, and post zombie once the process has been reaped we definitely get an error back. I also agree that it sounds like an extension, as changing the default would violate the princile of least surprise. Eric