On Tue, Jun 07, 2011 at 11:59:02PM +0100, Al Viro wrote:
> Completely untested patch follows:
FWIW, modulo a couple of brainos it seems to work here without blowing
everything up. Actual freeing of struct net is delayed until after
umount of sysfs instances refering it, shutdown is *not* delayed, sysfs
entries are removed nicely as they ought to, no objects from other net_ns
are picked by readdir or lookup...
If somebody has objections - yell. If I don't hear anything, the following
goes to -next:
commit 72d4e98002b45598bb88af74eeac20874f2789be
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Jun 8 21:13:01 2011 -0400
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 (->put_ns())
* ->current_ns() semantics change - it's supposed to be followed by
corresponding ->put_ns(). For struct net in case of CONFIG_NET_NS it bumps
the new refcount; net_put_ns() decrements it and calls net_free() if the
last reference has been dropped.
* old net_free() callers call net_put_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@xxxxxxxxxxxxxxxxxx>
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 2668957..1e7a2ee 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -111,8 +111,11 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
info->ns[type] = kobj_ns_current(type);
sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info);
- if (IS_ERR(sb) || sb->s_fs_info != info)
+ if (IS_ERR(sb) || sb->s_fs_info != info) {
+ for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
+ kobj_ns_put(type, info->ns[type]);
kfree(info);
+ }
if (IS_ERR(sb))
return ERR_CAST(sb);
if (!sb->s_root) {
@@ -131,11 +134,14 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
static void sysfs_kill_sb(struct super_block *sb)
{
struct sysfs_super_info *info = sysfs_info(sb);
+ int type;
/* Remove the superblock from fs_supers/s_instances
* so we can't find it, before freeing sysfs_super_info.
*/
kill_anon_super(sb);
+ for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
+ kobj_ns_put(type, info->ns[type]);
kfree(info);
}
@@ -145,28 +151,6 @@ static struct file_system_type sysfs_fs_type = {
.kill_sb = sysfs_kill_sb,
};
-void sysfs_exit_ns(enum kobj_ns_type type, const void *ns)
-{
- struct super_block *sb;
-
- mutex_lock(&sysfs_mutex);
- spin_lock(&sb_lock);
- list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) {
- struct sysfs_super_info *info = sysfs_info(sb);
- /*
- * If we see a superblock on the fs_supers/s_instances
- * list the unmount has not completed and sb->s_fs_info
- * points to a valid struct sysfs_super_info.
- */
- /* Ignore superblocks with the wrong ns */
- if (info->ns[type] != ns)
- continue;
- info->ns[type] = NULL;
- }
- spin_unlock(&sb_lock);
- mutex_unlock(&sysfs_mutex);
-}
-
int __init sysfs_init(void)
{
int err = -ENOMEM;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 3d28af3..2ed2404 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -136,7 +136,7 @@ struct sysfs_addrm_cxt {
* instance).
*/
struct sysfs_super_info {
- const void *ns[KOBJ_NS_TYPES];
+ void *ns[KOBJ_NS_TYPES];
};
#define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
extern struct sysfs_dirent sysfs_root;
diff --git a/include/linux/kobject_ns.h b/include/linux/kobject_ns.h
index 82cb5bf..5fa481c 100644
--- a/include/linux/kobject_ns.h
+++ b/include/linux/kobject_ns.h
@@ -38,9 +38,10 @@ enum kobj_ns_type {
*/
struct kobj_ns_type_operations {
enum kobj_ns_type type;
- const void *(*current_ns)(void);
+ void *(*current_ns)(void);
const void *(*netlink_ns)(struct sock *sk);
const void *(*initial_ns)(void);
+ void (*put_ns)(void *);
};
int kobj_ns_type_register(const struct kobj_ns_type_operations *ops);
@@ -48,9 +49,9 @@ int kobj_ns_type_registered(enum kobj_ns_type type);
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_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_put(enum kobj_ns_type type, void *ns);
#endif /* _LINUX_KOBJECT_NS_H */
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index c3acda6..e2696d7 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -177,9 +177,6 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd);
void sysfs_put(struct sysfs_dirent *sd);
-/* Called to clear a ns tag when it is no longer valid */
-void sysfs_exit_ns(enum kobj_ns_type type, const void *tag);
-
int __must_check sysfs_init(void);
#else /* CONFIG_SYSFS */
@@ -338,10 +335,6 @@ static inline void sysfs_put(struct sysfs_dirent *sd)
{
}
-static inline void sysfs_exit_ns(int type, const void *tag)
-{
-}
-
static inline int __must_check sysfs_init(void)
{
return 0;
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 2bf9ed9..415af64 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -35,8 +35,11 @@ struct netns_ipvs;
#define NETDEV_HASHENTRIES (1 << NETDEV_HASHBITS)
struct net {
+ atomic_t passive; /* To decided when the network
+ * namespace should be freed.
+ */
atomic_t count; /* To decided when the network
- * namespace should be freed.
+ * namespace should be shut down.
*/
#ifdef NETNS_REFCNT_DEBUG
atomic_t use_count; /* To track references we
@@ -154,6 +157,9 @@ int net_eq(const struct net *net1, const struct net *net2)
{
return net1 == net2;
}
+
+extern void net_put_ns(void *);
+
#else
static inline struct net *get_net(struct net *net)
@@ -175,6 +181,8 @@ int net_eq(const struct net *net1, const struct net *net2)
{
return 1;
}
+
+#define net_put_ns NULL
#endif
diff --git a/lib/kobject.c b/lib/kobject.c
index 82dc34c..43116b2 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -948,9 +948,9 @@ 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_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) &&
@@ -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_put(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]->put_ns)
+ kobj_ns_ops_tbl[type]->put_ns(ns);
+ spin_unlock(&kobj_ns_type_lock);
}
-
EXPORT_SYMBOL(kobject_get);
EXPORT_SYMBOL(kobject_put);
EXPORT_SYMBOL(kobject_del);
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 11b98bc..0c799f1 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1179,9 +1179,14 @@ static void remove_queue_kobjects(struct net_device *net)
#endif
}
-static const void *net_current_ns(void)
+static void *net_current_ns(void)
{
- return current->nsproxy->net_ns;
+ struct net *ns = current->nsproxy->net_ns;
+#ifdef CONFIG_NET_NS
+ if (ns)
+ atomic_inc(&ns->passive);
+#endif
+ return ns;
}
static const void *net_initial_ns(void)
@@ -1199,19 +1204,10 @@ struct kobj_ns_type_operations net_ns_type_operations = {
.current_ns = net_current_ns,
.netlink_ns = net_netlink_ns,
.initial_ns = net_initial_ns,
+ .put_ns = net_put_ns,
};
EXPORT_SYMBOL_GPL(net_ns_type_operations);
-static void net_kobj_ns_exit(struct net *net)
-{
- kobj_ns_exit(KOBJ_NS_TYPE_NET, net);
-}
-
-static struct pernet_operations kobj_net_ops = {
- .exit = net_kobj_ns_exit,
-};
-
-
#ifdef CONFIG_HOTPLUG
static int netdev_uevent(struct device *d, struct kobj_uevent_env *env)
{
@@ -1339,6 +1335,5 @@ EXPORT_SYMBOL(netdev_class_remove_file);
int netdev_kobject_init(void)
{
kobj_ns_type_register(&net_ns_type_operations);
- register_pernet_subsys(&kobj_net_ops);
return class_register(&net_class);
}
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 6c6b86d..19feb20 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -128,6 +128,7 @@ static __net_init int setup_net(struct net *net)
LIST_HEAD(net_exit_list);
atomic_set(&net->count, 1);
+ atomic_set(&net->passive, 1);
#ifdef NETNS_REFCNT_DEBUG
atomic_set(&net->use_count, 0);
@@ -210,6 +211,13 @@ static void net_free(struct net *net)
kmem_cache_free(net_cachep, net);
}
+void net_put_ns(void *p)
+{
+ struct net *ns = p;
+ if (ns && atomic_dec_and_test(&ns->passive))
+ net_free(ns);
+}
+
struct net *copy_net_ns(unsigned long flags, struct net *old_net)
{
struct net *net;
@@ -230,7 +238,7 @@ struct net *copy_net_ns(unsigned long flags, struct net *old_net)
}
mutex_unlock(&net_mutex);
if (rv < 0) {
- net_free(net);
+ net_put_ns(net);
return ERR_PTR(rv);
}
return net;
@@ -286,7 +294,7 @@ static void cleanup_net(struct work_struct *work)
/* Finally it is safe to free my network namespace structure */
list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
list_del_init(&net->exit_list);
- net_free(net);
+ net_put_ns(net);
}
}
static DECLARE_WORK(net_cleanup_work, cleanup_net);
--
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