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From: Tejun Heo <tj@kernel.org>
To: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: serge@hallyn.com, linux-kernel@vger.kernel.org,
	adityakali@google.com, linux-api@vger.kernel.org,
	containers@lists.linux-foundation.org, cgroups@vger.kernel.org,
	lxc-devel@lists.linuxcontainers.org, akpm@linux-foundation.org,
	ebiederm@xmission.com
Subject: Re: [PATCH 1/8] kernfs: Add API to generate relative kernfs path
Date: Mon, 30 Nov 2015 10:11:47 -0500	[thread overview]
Message-ID: <20151130151147.GG3535@mtj.duckdns.org> (raw)
In-Reply-To: <20151127052511.GA25490@mail.hallyn.com>

Hello,

On Thu, Nov 26, 2015 at 11:25:11PM -0600, Serge E. Hallyn wrote:
> > > +	/* Short-circuit the easy case - kn_to is the root node. */
> > > +	if ((kn_from == kn_to) || (!kn_from && !kn_to->parent)) {
> > > +		*p = '/';
> > > +		*(p + 1) = '\0';
> > 
> > Hmm... so if kn_from == kn_to, the output is "/"?
> 
> Yes, that's what seems to make the most sense for cgroup namespaces.  I
> could see a case for '.' being used instead in general, but for cgroup
> namespaces I think we'd have to convert those back to '/'.  Otherwise
> we'll fail in being able to run legacy software, which would get
> confused.

Yeah, I agree but the name is kinda misleading tho.  The output isn't
really a relative path but rather absolute path against the specified
root.  Maybe updating the function and parameter names would be
helpful?

Thanks.

-- 
tejun

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: "Serge E. Hallyn" <serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>
Cc: adityakali-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
	linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	lxc-devel-cunTk1MwBs9qMoObBWhMNEqPaTDuhLve2LY78lusg7I@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
	serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org
Subject: Re: [PATCH 1/8] kernfs: Add API to generate relative kernfs path
Date: Mon, 30 Nov 2015 10:11:47 -0500	[thread overview]
Message-ID: <20151130151147.GG3535@mtj.duckdns.org> (raw)
In-Reply-To: <20151127052511.GA25490-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>

Hello,

On Thu, Nov 26, 2015 at 11:25:11PM -0600, Serge E. Hallyn wrote:
> > > +	/* Short-circuit the easy case - kn_to is the root node. */
> > > +	if ((kn_from == kn_to) || (!kn_from && !kn_to->parent)) {
> > > +		*p = '/';
> > > +		*(p + 1) = '\0';
> > 
> > Hmm... so if kn_from == kn_to, the output is "/"?
> 
> Yes, that's what seems to make the most sense for cgroup namespaces.  I
> could see a case for '.' being used instead in general, but for cgroup
> namespaces I think we'd have to convert those back to '/'.  Otherwise
> we'll fail in being able to run legacy software, which would get
> confused.

Yeah, I agree but the name is kinda misleading tho.  The output isn't
really a relative path but rather absolute path against the specified
root.  Maybe updating the function and parameter names would be
helpful?

Thanks.

-- 
tejun
_______________________________________________
lxc-devel mailing list
lxc-devel@lists.linuxcontainers.org
http://lists.linuxcontainers.org/listinfo/lxc-devel

  parent reply	other threads:[~2015-11-30 15:18 UTC|newest]

Thread overview: 180+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-16 19:51 CGroup Namespaces (v4) serge-A9i7LUbDfNHQT0dZR+AlfA
2015-11-16 19:51 ` serge
2015-11-16 19:51 ` [PATCH 2/8] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace serge
2015-11-16 19:51   ` serge-A9i7LUbDfNHQT0dZR+AlfA
     [not found] ` <1447703505-29672-1-git-send-email-serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2015-11-16 19:51   ` [PATCH 1/8] kernfs: Add API to generate relative kernfs path serge-A9i7LUbDfNHQT0dZR+AlfA
2015-11-16 19:51     ` serge
     [not found]     ` <1447703505-29672-2-git-send-email-serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2015-11-24 16:16       ` Tejun Heo
2015-11-24 16:16     ` Tejun Heo
2015-11-24 16:16       ` Tejun Heo
2015-11-24 16:17       ` Tejun Heo
2015-11-24 16:17         ` Tejun Heo
2015-11-24 17:43         ` Serge E. Hallyn
2015-11-24 17:43           ` Serge E. Hallyn
     [not found]         ` <20151124161709.GM17033-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-11-24 17:43           ` Serge E. Hallyn
     [not found]       ` <20151124161630.GL17033-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-11-24 16:17         ` Tejun Heo
2015-11-27  5:25         ` Serge E. Hallyn
2015-11-27  5:25       ` Serge E. Hallyn
2015-11-27  5:25         ` Serge E. Hallyn
     [not found]         ` <20151127052511.GA25490-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-11-30 15:11           ` Tejun Heo
2015-11-30 15:11         ` Tejun Heo [this message]
2015-11-30 15:11           ` Tejun Heo
2015-11-30 18:37           ` Serge E. Hallyn
2015-11-30 18:37             ` Serge E. Hallyn
2015-11-30 22:53             ` Tejun Heo
     [not found]               ` <20151130225318.GD9039-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-01  2:08                 ` Serge E. Hallyn
2015-12-01  2:08               ` Serge E. Hallyn
2015-12-01  2:08                 ` Serge E. Hallyn
     [not found]             ` <20151130183758.GA25433-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-11-30 22:53               ` Tejun Heo
     [not found]           ` <20151130151147.GG3535-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-11-30 18:37             ` Serge E. Hallyn
2015-11-16 19:51   ` [PATCH 2/8] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace serge-A9i7LUbDfNHQT0dZR+AlfA
2015-11-16 19:51   ` [PATCH 3/8] cgroup: add function to get task's cgroup serge-A9i7LUbDfNHQT0dZR+AlfA
2015-11-16 19:51     ` serge
     [not found]     ` <1447703505-29672-4-git-send-email-serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2015-11-24 16:27       ` Tejun Heo
2015-11-24 16:27         ` Tejun Heo
     [not found]         ` <20151124162728.GN17033-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-11-24 16:54           ` Tejun Heo
2015-11-24 16:54         ` Tejun Heo
2015-11-24 16:54           ` Tejun Heo
2015-11-16 19:51   ` [PATCH 4/8] cgroup: export cgroup_get() and cgroup_put() serge-A9i7LUbDfNHQT0dZR+AlfA
2015-11-16 19:51   ` [PATCH 5/8] cgroup: introduce cgroup namespaces serge-A9i7LUbDfNHQT0dZR+AlfA
2015-11-16 19:51     ` serge
2015-11-24 16:49     ` Tejun Heo
2015-11-24 16:49       ` Tejun Heo
     [not found]     ` <1447703505-29672-6-git-send-email-serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2015-11-24 16:49       ` Tejun Heo
2015-11-16 19:51   ` [PATCH 6/8] cgroup: cgroup namespace setns support serge-A9i7LUbDfNHQT0dZR+AlfA
2015-11-16 19:51     ` serge
     [not found]     ` <1447703505-29672-7-git-send-email-serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2015-11-24 16:52       ` Tejun Heo
2015-11-24 16:52     ` Tejun Heo
2015-11-24 16:52       ` Tejun Heo
2015-11-16 19:51   ` [PATCH 7/8] cgroup: mount cgroupns-root when inside non-init cgroupns serge-A9i7LUbDfNHQT0dZR+AlfA
2015-11-16 19:51     ` serge
     [not found]     ` <1447703505-29672-8-git-send-email-serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2015-11-24 17:16       ` Tejun Heo
2015-11-24 17:16     ` Tejun Heo
2015-11-24 17:16       ` Tejun Heo
2015-11-25  6:01       ` Serge E. Hallyn
     [not found]         ` <20151125060156.GA678-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-11-25 19:10           ` Tejun Heo
2015-11-25 19:10         ` Tejun Heo
2015-11-25 19:10           ` Tejun Heo
     [not found]           ` <20151125191041.GB14240-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2015-11-25 19:55             ` Serge Hallyn
2015-11-25 19:55           ` Serge Hallyn
2015-11-25 19:55             ` Serge Hallyn
2015-11-25 19:57             ` Tejun Heo
2015-11-25 19:57               ` Tejun Heo
2015-11-25 19:57             ` Tejun Heo
     [not found]       ` <20151124171610.GS17033-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-11-25  6:01         ` Serge E. Hallyn
2015-11-27  5:17         ` Serge E. Hallyn
2015-11-27  5:17       ` Serge E. Hallyn
2015-11-27  5:17         ` Serge E. Hallyn
     [not found]         ` <20151127051745.GA24521-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-11-30 15:09           ` Tejun Heo
2015-11-30 15:09         ` Tejun Heo
2015-11-30 15:09           ` Tejun Heo
     [not found]           ` <20151130150938.GF3535-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-01  4:07             ` Serge E. Hallyn
2015-12-01  4:07           ` Serge E. Hallyn
2015-12-01  4:07             ` Serge E. Hallyn
     [not found]             ` <20151201040704.GA31067-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-12-01 16:46               ` Tejun Heo
2015-12-01 16:46             ` Tejun Heo
2015-12-01 16:46               ` Tejun Heo
2015-12-01 21:58               ` Serge E. Hallyn
2015-12-01 21:58                 ` Serge E. Hallyn
2015-12-02 16:53                 ` Tejun Heo
2015-12-02 16:53                   ` Tejun Heo
     [not found]                   ` <20151202165312.GB19878-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-02 16:56                     ` Serge E. Hallyn
2015-12-02 16:56                   ` Serge E. Hallyn
2015-12-02 16:56                     ` Serge E. Hallyn
2015-12-02 16:58                     ` Tejun Heo
2015-12-02 16:58                       ` Tejun Heo
     [not found]                       ` <20151202165839.GD19878-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-02 17:02                         ` Serge E. Hallyn
2015-12-02 17:02                       ` Serge E. Hallyn
2015-12-02 17:02                         ` Serge E. Hallyn
     [not found]                         ` <20151202170239.GA21009-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-12-02 17:05                           ` Tejun Heo
2015-12-02 17:05                             ` Tejun Heo
2015-12-03 22:47                             ` Serge E. Hallyn
2015-12-03 22:47                               ` Serge E. Hallyn
2015-12-07 15:39                               ` Tejun Heo
2015-12-07 15:39                                 ` Tejun Heo
     [not found]                                 ` <20151207153911.GF9175-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-07 15:53                                   ` Serge Hallyn
2015-12-07 15:53                                     ` Serge Hallyn
     [not found]                               ` <20151203224706.GA19971-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-12-07 15:39                                 ` Tejun Heo
     [not found]                             ` <20151202170551.GE19878-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-03 22:47                               ` Serge E. Hallyn
     [not found]                     ` <20151202165637.GA20840-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-12-02 16:58                       ` Tejun Heo
     [not found]                 ` <20151201215853.GA9153-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-12-02 16:53                   ` Tejun Heo
     [not found]               ` <20151201164649.GD12922-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-01 21:58                 ` Serge E. Hallyn
2015-11-16 19:51   ` [PATCH 8/8] cgroup: Add documentation for cgroup namespaces serge-A9i7LUbDfNHQT0dZR+AlfA
2015-11-16 19:51     ` serge
2015-11-24 17:16     ` Tejun Heo
2015-11-24 17:16       ` Tejun Heo
     [not found]     ` <1447703505-29672-9-git-send-email-serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2015-11-24 17:16       ` Tejun Heo
2015-11-16 20:41   ` CGroup Namespaces (v4) Richard Weinberger
2015-11-16 19:51 ` [PATCH 4/8] cgroup: export cgroup_get() and cgroup_put() serge
2015-11-16 19:51   ` serge-A9i7LUbDfNHQT0dZR+AlfA
     [not found]   ` <1447703505-29672-5-git-send-email-serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2015-11-24 16:30     ` Tejun Heo
2015-11-24 16:30       ` Tejun Heo
2015-11-24 22:35       ` Serge E. Hallyn
2015-11-24 22:35         ` Serge E. Hallyn
     [not found]       ` <20151124163056.GO17033-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-11-24 22:35         ` Serge E. Hallyn
2015-11-16 20:41 ` CGroup Namespaces (v4) Richard Weinberger
2015-11-16 20:41   ` Richard Weinberger
2015-11-16 20:46   ` Serge E. Hallyn
2015-11-16 20:46     ` Serge E. Hallyn
2015-11-16 20:50     ` Richard Weinberger
2015-11-16 20:50       ` Richard Weinberger
2015-11-16 20:54       ` Serge E. Hallyn
2015-11-16 20:54         ` Serge E. Hallyn
2015-11-16 22:24         ` Eric W. Biederman
2015-11-16 22:24           ` Eric W. Biederman
2015-11-16 22:37           ` Tejun Heo
2015-11-16 22:37             ` Tejun Heo
     [not found]           ` <87y4dxh9b8.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org>
2015-11-16 22:37             ` Tejun Heo
2015-11-17  1:13             ` Serge E. Hallyn
2015-11-17  1:13               ` Serge E. Hallyn
2015-11-17  1:13               ` Serge E. Hallyn
2015-11-17  1:40               ` Serge E. Hallyn
2015-11-17  1:40                 ` Serge E. Hallyn
2015-11-17  3:54                 ` Serge E. Hallyn
2015-11-17  3:54                   ` Serge E. Hallyn
     [not found]                 ` <20151117014026.GA2331-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-11-17  3:54                   ` Serge E. Hallyn
     [not found]               ` <20151117011349.GA1958-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-11-17  1:40                 ` Serge E. Hallyn
2015-11-18  2:30             ` Serge E. Hallyn
2015-11-18  2:30               ` Serge E. Hallyn
     [not found]               ` <20151118023022.GA17501-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-11-18  9:18                 ` Eric W. Biederman
2015-11-18  9:18                   ` Eric W. Biederman
     [not found]                   ` <87r3jnfyx7.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org>
2015-11-18 15:43                     ` Serge E. Hallyn
2015-11-18 15:43                       ` Serge E. Hallyn
     [not found]         ` <20151116205452.GA30975-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-11-16 22:24           ` Eric W. Biederman
     [not found]       ` <564A41AF.4040208-/L3Ra7n9ekc@public.gmane.org>
2015-11-16 20:54         ` Serge E. Hallyn
     [not found]     ` <20151116204606.GA30681-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2015-11-16 20:50       ` Richard Weinberger
     [not found]   ` <CAFLxGvzVmbZHrpaTmXUAK03hsnVPwEs3SJGNFNXfthh3NL8EDg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-11-16 20:46     ` Serge E. Hallyn
2015-12-09 19:28 CGroup Namespaces (v7) serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA
2015-12-09 19:28 ` [PATCH 1/8] kernfs: Add API to generate relative kernfs path serge.hallyn
2015-12-09 21:38   ` Tejun Heo
2015-12-09 21:38     ` Tejun Heo
2015-12-09 22:13     ` Serge Hallyn
2015-12-09 22:13       ` Serge Hallyn
2015-12-09 22:36       ` Tejun Heo
2015-12-09 22:36         ` Tejun Heo
2015-12-09 22:51         ` Serge E. Hallyn
     [not found]         ` <20151209223651.GQ30240-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-09 22:51           ` Serge E. Hallyn
2015-12-10  1:28           ` Serge E. Hallyn
2015-12-10  1:28             ` Serge E. Hallyn
2015-12-09 22:36       ` Tejun Heo
     [not found]     ` <20151209213806.GP30240-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-09 22:13       ` Serge Hallyn
     [not found]   ` <1449689341-28742-2-git-send-email-serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>
2015-12-09 21:38     ` Tejun Heo
     [not found] ` <1449689341-28742-1-git-send-email-serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>
2015-12-09 19:28   ` serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA
2015-12-23  4:23 CGroup Namespaces (v8) serge.hallyn
     [not found] ` <1450844609-9194-1-git-send-email-serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>
2015-12-23  4:23   ` [PATCH 1/8] kernfs: Add API to generate relative kernfs path serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA
2015-12-23  4:23     ` serge.hallyn
2015-12-23 16:08     ` Tejun Heo
2015-12-23 16:08       ` Tejun Heo
2015-12-23 16:36       ` Serge E. Hallyn
2015-12-23 16:36         ` Serge E. Hallyn
     [not found]       ` <20151223160854.GF5003-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-23 16:36         ` Serge E. Hallyn
2015-12-23 16:24     ` Tejun Heo
2015-12-23 16:24       ` Tejun Heo
2015-12-23 16:51       ` Greg KH
2015-12-23 16:51         ` Greg KH
     [not found]       ` <20151223162433.GH5003-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2015-12-23 16:51         ` Greg KH
     [not found]     ` <1450844609-9194-2-git-send-email-serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>
2015-12-23 16:08       ` Tejun Heo
2015-12-23 16:24       ` Tejun Heo
2016-01-04 19:54 CGroup Namespaces (v9) serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA
     [not found] ` <1451937294-22589-1-git-send-email-serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>
2016-01-04 19:54   ` [PATCH 1/8] kernfs: Add API to generate relative kernfs path serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA
2016-01-04 19:54     ` serge.hallyn
2016-01-29  8:54 CGroup Namespaces (v10) serge.hallyn
2016-01-29  8:54 ` [PATCH 1/8] kernfs: Add API to generate relative kernfs path serge.hallyn
2016-01-29  8:54   ` serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA
     [not found] ` <1454057651-23959-1-git-send-email-serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>
2016-01-29  8:54   ` serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA

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