From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?J=FCrg?= Billeter Subject: Re: [PATCH v4] signal: add taskfd_send_signal() syscall Date: Thu, 06 Dec 2018 13:45:39 +0100 Message-ID: References: <20181206121858.12215-1-christian@brauner.io> <87h8fq7s84.fsf@oldenburg2.str.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <87h8fq7s84.fsf@oldenburg2.str.redhat.com> Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: linux-api@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