Re: [PATCH] samples: make pidfd-metadata fail gracefully on older kernels

From: Christian Brauner
Date: Mon Jun 24 2019 - 05:52:55 EST

On Sun, Jun 23, 2019 at 02:32:30PM +0300, Dmitry V. Levin wrote:
> On Sat, Jun 22, 2019 at 12:13:39AM +0200, Christian Brauner wrote:
> [...]
> > Out of curiosity: what makes the new flag different than say
> > CLONE_NEWCGROUP or any new clone flag that got introduced?
> > CLONE_NEWCGROUP too would not be detectable apart from the method I gave
> > you above; same for other clone flags. Why are you so keen on being able
> > to detect this flag when other flags didn't seem to matter that much.
> I wasn't following uapi changes closely enough those days. ;)

(Seriously, you had one job. :) I'm joking of course.)

What you want makes sense to me overall. This way userspace can decide
easier whether to manage a process through a pidfd or needs to fallback
to a pid.