Delay struct net freeing while there's a sysfs instance refering to it
* new refcount in struct net, controlling actual freeing of the memory
* new method in kobj_ns_type_operations (->drop_ns())
* ->current_ns() semantics change - it's supposed to be followed by
corresponding ->drop_ns(). For struct net in case of CONFIG_NET_NS it bumps
the new refcount; net_drop_ns() decrements it and calls net_free() if the
last reference has been dropped. Method renamed to ->grab_current_ns().
* old net_free() callers call net_drop_ns() instead.
* sysfs_exit_ns() is gone, along with a large part of callchain
leading to it; now that the references stored in ->ns[...] stay valid we
do not need to hunt them down and replace them with NULL. That fixes
problems in sysfs_lookup() and sysfs_readdir(), along with getting rid
of sb->s_instances abuse.
Note that struct net *shutdown* logics has not changed - net_cleanup()
is called exactly when it used to be called. The only thing postponed by
having a sysfs instance refering to that struct net is actual freeing of
memory occupied by struct net.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/kobject_ns.h b/include/linux/kobject_ns.h
index 82cb5bf..f66b065 100644
--- a/include/linux/kobject_ns.h
+++ b/include/linux/kobject_ns.h
@@ -32,15 +32,17 @@
/*
* Callbacks so sysfs can determine namespaces
- * @current_ns: return calling task's namespace
+ * @grab_current_ns: return a new reference to calling task's namespace
* @netlink_ns: return namespace to which a sock belongs (right?)
* @initial_ns: return the initial namespace (i.e. init_net_ns)
+ * @drop_ns: drops a reference to namespace
*/
struct kobj_ns_type_operations {
enum kobj_ns_type type;
- const void *(*current_ns)(void);
+ void *(*grab_current_ns)(void);
const void *(*netlink_ns)(struct sock *sk);
const void *(*initial_ns)(void);
+ void (*drop_ns)(void *);
};
int kobj_ns_type_register(const struct kobj_ns_type_operations *ops);
@@ -48,9 +50,9 @@
const struct kobj_ns_type_operations *kobj_child_ns_ops(struct kobject *parent);
const struct kobj_ns_type_operations *kobj_ns_ops(struct kobject *kobj);
-const void *kobj_ns_current(enum kobj_ns_type type);
+void *kobj_ns_grab_current(enum kobj_ns_type type);
const void *kobj_ns_netlink(enum kobj_ns_type type, struct sock *sk);
const void *kobj_ns_initial(enum kobj_ns_type type);
-void kobj_ns_exit(enum kobj_ns_type type, const void *ns);
+void kobj_ns_drop(enum kobj_ns_type type, void *ns);
#endif /* _LINUX_KOBJECT_NS_H */