On Thu, Dec 06, 2018 at 01:30:19PM +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. Apart from my objection that this is not actually a reliable state because of timing issues between e.g. calling wait and a process exiting I have two more concerns and one helpful suggestion. First, this is hooking pretty deep into kernel internals. So far EXIT_ZOMBIE is only exposed in kernel/exit.c and I don't see enough value to drag all of this into kernel/signal.c Second, all other signal syscalls don't do report errors when signaling to zombies as well. It would be odd if this one suddenly did. Third, if this really becomes such a big issue for userspace in the future that we want to do that work then we can add a flag like TASKFD_DETECT_ZOMBIE (or some such name) that will allow userspace to get an error back when signaling a zombie. As far as I'm concerned, this is out of scope for an initial implementation. We are going to use fds for tasks that's enough excitement for one patchset! > > Rest looks good to me (with the usual caveats). I take it that's your way of saying Acked-by? :) Christian
