[Devel] Re: [RFC PATCH 3/4] namespace containers: add nsproxy to nscont struct

[Serge E. Hallyn]

Quoting Paul Menage (menage at google.com):
> On 2/12/07, Serge E. Hallyn <serue at us.ibm.com> wrote:
> >--- a/kernel/container.c
> >+++ b/kernel/container.c
> >@@ -1581,6 +1581,14 @@ static void get_unused_name(char *buf) {
> >        sprintf(buf, "node%d", atomic_inc_return(&namecnt));
> > }
> >
> >+/* XXX need to create include/linux/ns_container.h and move this there */
> >+#ifdef CONFIG_CONTAINER_NS
> >+void ns_set_nsproxy_from_task(struct container *cont, struct task_struct 
> >*tsk);
> >+#else
> >+static inline void
> >+ns_set_nsproxy_from_task(struct container *cont, struct task_struct *tsk) 
> >{ }
> >+#endif
> >+
> 
> Can't this just go in include/linux/nsproxy.h ?

I didn't want nsproxy.h knowing about containers if it didn't have to.
I'd rather have ns_container.h knowing about nsproxy and not the other
way around.

> >
> >+       /* mark the auto-created container with the new namespace list */
> >+       ns_set_nsproxy_from_task(child, tsk);
> >+
> 
> This should be in ns_container_clone() or some (possibly new)
> subsystem callback, rather than embedded in the generic containers
> code.

Would you complain if I change kernel/container.c:container_clone() to
return the container *, so that ns_container_clone() doesn't need to
deduce that from tsk?  So something like the following (not even
compiled, just to show what I'd be doing):


diff --git a/kernel/container.c b/kernel/container.c
index 4608a12..8895137 100644
--- a/kernel/container.c
+++ b/kernel/container.c
@@ -1593,7 +1593,7 @@ ns_set_nsproxy_from_task(struct containe
  * container_clone - duplicate the current container and move this
  * task into the new child
  */
-int container_clone(struct task_struct *tsk, struct container_subsys *subsys,
+struct container *container_clone(struct task_struct *tsk, struct container_subsys *subsys,
 					struct nsproxy *nsproxy)
 {
 	struct dentry *dentry;
diff --git a/kernel/ns_container.c b/kernel/ns_container.c
index 921c600..4291b18 100644
--- a/kernel/ns_container.c
+++ b/kernel/ns_container.c
@@ -23,9 +23,22 @@ static inline struct nscont *container_n
 			    struct nscont, css);
 }
 
+static void ns_set_nsproxy_from_task(struct container *cont, struct task_struct *tsk)
+{
+	struct nscont *ns = container_nscont(cont);
+	ns->nsproxy = tsk->nsproxy;
+	get_nsproxy(ns->nsproxy);
+}
+
 int ns_container_clone(struct task_struct *tsk, struct nsproxy *nsproxy)
 {
-	return container_clone(tsk, &ns_subsys, nsproxy);
+	struct container *c;
+
+	c = container_clone(tsk, &ns_subsys, nsproxy);
+	if (IS_ERR(c))
+		return ERR_PTR(c);
+	ns_set_nsproxy_from_task(c, tsk);
+	return 0;
 }
 
 /*
@@ -95,14 +108,6 @@ static void ns_create_nsproxy(struct nsc
 	get_nsproxy(ns->nsproxy);
 }
 
-/* called from container_clone */
-void ns_set_nsproxy_from_task(struct container *cont, struct task_struct *tsk)
-{
-	struct nscont *ns = container_nscont(cont);
-	ns->nsproxy = tsk->nsproxy;
-	get_nsproxy(ns->nsproxy);
-}
-
 void ns_attach(struct container_subsys *ss, struct container *cont,
 		   struct container *old_cont, struct task_struct *tsk)
 {