From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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 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> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [PATCH v4] signal: add taskfd_send_signal() syscall Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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