From: Oleg Nesterov <oleg@redhat.com>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: serge@hallyn.com, ebiederm@xmission.com, agruenba@redhat.com,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
paul@paul-moore.com, viro@zeniv.linux.org.uk, avagin@openvz.org,
linux-fsdevel@vger.kernel.org, mtk.manpages@gmail.com,
akpm@linux-foundation.org, luto@amacapital.net,
gorcunov@openvz.org, mingo@kernel.org, keescook@chromium.org
Subject: Re: [PATCH 2/2] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy
Date: Tue, 2 May 2017 18:33:25 +0200 [thread overview]
Message-ID: <20170502163324.GA25036@redhat.com> (raw)
In-Reply-To: <43249645-f621-511e-dfa8-7bd78c547d2c@virtuozzo.com>
sorry for delay, vacation...
On 04/28, Kirill Tkhai wrote:
>
> On 27.04.2017 19:22, Oleg Nesterov wrote:
> >
> > Ah, OK, I didn't notice the ns->child_reaper check in pidns_for_children_get().
> >
> > But note that it doesn't need tasklist_lock too.
>
> Hm, are there possible strange situations with memory ordering, when we see
> ns->child_reaper of already died ns, which was placed in the same memory?
> Do we have to use some memory barriers here?
Could you spell please? I don't understand your concerns...
I don't see how, say,
static struct ns_common *pidns_for_children_get(struct task_struct *task)
{
struct ns_common *ns = NULL;
struct pid_namespace *pid_ns;
task_lock(task);
if (task->nsproxy) {
pid_ns = task->nsproxy->pid_ns_for_children;
if (pid_ns->child_reaper) {
ns = &pid_ns->ns;
get_pid_ns(ns);
}
}
task_unlock(task);
return ns;
}
can be wrong. It also looks more clean to me.
->child_reaper is not stable without tasklist, it can be dead/etc, but
we do not care?
Oleg.
next prev parent reply other threads:[~2017-05-02 16:33 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-17 17:34 [PATCH 0/2] nsfs: Introduce ioctl to set vector of ns_last_pid's on pid ns hierarhy Kirill Tkhai
[not found] ` <149245014695.17600.12640895883798122726.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-04-17 17:36 ` [PATCH 1/2] nsfs: Add namespace-specific ioctl (NS_SPECIFIC_IOC) Kirill Tkhai
2017-04-17 17:36 ` [PATCH 2/2] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy Kirill Tkhai
[not found] ` <149245057248.17600.1341652606136269734.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-04-19 20:27 ` Serge E. Hallyn
2017-04-24 19:03 ` Cyrill Gorcunov
2017-04-26 15:53 ` Oleg Nesterov
[not found] ` <20170426155352.GA12131-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-04-26 16:11 ` Kirill Tkhai
[not found] ` <785e1986-da03-72aa-06c0-234ed2dbc0fd-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-26 16:33 ` Kirill Tkhai
[not found] ` <005f52d9-efbe-9eaa-7f36-19945c8b06c3-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-26 16:32 ` Eric W. Biederman
[not found] ` <87h91bcep5.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-26 16:43 ` Kirill Tkhai
2017-04-26 17:01 ` Eric W. Biederman
2017-04-27 16:12 ` Oleg Nesterov
2017-04-27 16:17 ` Kirill Tkhai
[not found] ` <fdd61d9c-6f88-1669-4d12-31748395fe99-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-27 16:22 ` Oleg Nesterov
2017-04-28 9:17 ` Kirill Tkhai
2017-05-02 16:33 ` Oleg Nesterov [this message]
[not found] ` <20170502163324.GA25036-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-05-02 17:22 ` Eric W. Biederman
2017-05-02 17:33 ` Kirill Tkhai
[not found] ` <de392430-18b8-d296-b868-82fdedcd0c0e-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-05-02 21:13 ` Eric W. Biederman
[not found] ` <8737cngdxi.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-05-03 10:20 ` Kirill Tkhai
2017-04-27 16:39 ` Eric W. Biederman
[not found] ` <87o9vhztwv.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-28 9:22 ` Kirill Tkhai
2017-04-27 16:16 ` Oleg Nesterov
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