lkml.org 
[lkml]   [2017]   [May]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy
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.

\
 
 \ /
  Last update: 2017-05-02 18:35    [W:0.083 / U:0.320 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site