Messages in this thread | | | Date | Tue, 2 May 2017 18:33:25 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 2/2] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy |
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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.
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