linux-kernel - Re: [RFC 1/5] user namespaces: Add a user_namespace as creator/owner of uts

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Message-ID: <20101217161700.GA5926@peq>
Date:	Fri, 17 Dec 2010 10:17:00 -0600
From:	Serge Hallyn <serge.hallyn@...onical.com>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	"Serge E. Hallyn" <serge@...lyn.com>,
	LSM <linux-security-module@...r.kernel.org>,
	James Morris <jmorris@...ei.org>,
	Kees Cook <kees.cook@...onical.com>,
	containers@...ts.linux-foundation.org,
	kernel list <linux-kernel@...r.kernel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Michael Kerrisk <michael.kerrisk@...il.com>
Subject: Re: [RFC 1/5] user namespaces: Add a user_namespace as
 creator/owner of uts_namespace

Quoting Alexey Dobriyan (adobriyan@...il.com):
> On Fri, Dec 17, 2010 at 5:56 PM, Alexey Dobriyan <adobriyan@...il.com> wrote:
> > On Fri, Dec 17, 2010 at 5:24 PM, Serge E. Hallyn <serge@...lyn.com> wrote:
> >> +/*
> >> + * userns count is 1 for root user, 1 for init_uts_ns,
> >> + * and 1 for... ?
> >> + */
> >>  struct user_namespace init_user_ns = {
> >>        .kref = {
> >> -               .refcount       = ATOMIC_INIT(2),
> >> +               .refcount       = ATOMIC_INIT(3),
> >
> > +1 is for init_nsproxy ;-)
> 
> Err, no.
> 
> +1 is to ensure it's never freed, but since allocator will BUG_ON (?) if fed
> with static object, maybe it's completely bogus.

Right.  On the one hand so long as it's high enough it doesn't really matter.
But I think it's worth getting the # exactly right in order to help document
what's going on.  So I'll try dropping it back down to 2.

thanks,
-serge
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