From a685e08987d1edf1995b76511d4c98ea0e905377 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 8 Jun 2011 21:13:01 -0400 Subject: 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 --- lib/kobject.c | 26 +++++++++----------------- 1 file changed, 9 insertions(+), 17 deletions(-) (limited to 'lib') diff --git a/lib/kobject.c b/lib/kobject.c index 82dc34c095c..640bd98a4c8 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -948,14 +948,14 @@ 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 *ns = NULL; + void *ns = NULL; spin_lock(&kobj_ns_type_lock); if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) && kobj_ns_ops_tbl[type]) - ns = kobj_ns_ops_tbl[type]->current_ns(); + ns = kobj_ns_ops_tbl[type]->grab_current_ns(); spin_unlock(&kobj_ns_type_lock); return ns; @@ -987,23 +987,15 @@ const void *kobj_ns_initial(enum kobj_ns_type type) return ns; } -/* - * kobj_ns_exit - invalidate a namespace tag - * - * @type: the namespace type (i.e. KOBJ_NS_TYPE_NET) - * @ns: the actual namespace being invalidated - * - * This is called when a tag is no longer valid. For instance, - * when a network namespace exits, it uses this helper to - * make sure no sb's sysfs_info points to the now-invalidated - * netns. - */ -void kobj_ns_exit(enum kobj_ns_type type, const void *ns) +void kobj_ns_drop(enum kobj_ns_type type, void *ns) { - sysfs_exit_ns(type, ns); + spin_lock(&kobj_ns_type_lock); + if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) && + kobj_ns_ops_tbl[type] && kobj_ns_ops_tbl[type]->drop_ns) + kobj_ns_ops_tbl[type]->drop_ns(ns); + spin_unlock(&kobj_ns_type_lock); } - EXPORT_SYMBOL(kobject_get); EXPORT_SYMBOL(kobject_put); EXPORT_SYMBOL(kobject_del); -- cgit v1.2.3