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Date:   Mon, 24 Jun 2019 11:52:50 +0200
From:   Christian Brauner <christian@brauner.io>
To:     "Dmitry V. Levin" <ldv@altlinux.org>
Cc:     Jann Horn <jannh@google.com>, Oleg Nesterov <oleg@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>, linux-api@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] samples: make pidfd-metadata fail gracefully on older
 kernels
Message-ID: <20190624095250.wtl5t5cewo7scyby@brauner.io>
References: <20190620103105.cdxgqfelzlnkmblv@brauner.io>
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 <20190621170613.GA26182@altlinux.org>
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 <20190623113230.GC20697@altlinux.org>
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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.

Christian