Re: [PATCH v1 2/4] pid: add pidctl()

[Christian Brauner]

On Tue, Mar 26, 2019 at 09:17:07AM -0700, Daniel Colascione wrote:
> Thanks for the patch.
> 
> On Tue, Mar 26, 2019 at 8:55 AM Christian Brauner <christian@xxxxxxxxxx> wrote:
> >
> > The pidctl() syscalls builds on, extends, and improves translate_pid() [4].
> > I quote Konstantins original patchset first that has already been acked and
> > picked up by Eric before and whose functionality is preserved in this
> > syscall:
> 
> We still haven't had a much-needed conversation about splitting this
> system call into smaller logical operations. It's important that we
> address this point before this patch is merged and becomes permanent
> kernel ABI.

I don't particularly mind splitting this into an additional syscall like
e.g.  pidfd_open() but then we have - and yes, I know you'll say
syscalls are cheap - translate_pid(), and pidfd_open(). What I like
about this rn is that it connects both apis in a single syscall
and allows pidfd retrieval across pid namespaces. So I guess we'll see
what other people think.