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authorAl Viro <viro@zeniv.linux.org.uk>2011-06-08 21:13:01 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2011-06-12 17:45:41 -0400
commita685e08987d1edf1995b76511d4c98ea0e905377 (patch)
tree1d42593e2bc320f8d93b98851b2df0fd432e3859
parentdde194a64bb5c3fd05d965775dc92e8a4920a53a (diff)
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>
-rw-r--r--fs/sysfs/mount.c37
-rw-r--r--fs/sysfs/sysfs.h2
-rw-r--r--include/linux/kobject_ns.h10
-rw-r--r--include/linux/sysfs.h7
-rw-r--r--include/net/net_namespace.h10
-rw-r--r--lib/kobject.c26
-rw-r--r--net/core/net-sysfs.c23
-rw-r--r--net/core/net_namespace.c12
8 files changed, 55 insertions, 72 deletions
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 266895783b4..e34f0d99ea4 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -95,6 +95,14 @@ static int sysfs_set_super(struct super_block *sb, void *data)
return error;
}
+static void free_sysfs_super_info(struct sysfs_super_info *info)
+{
+ int type;
+ for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
+ kobj_ns_drop(type, info->ns[type]);
+ kfree(info);
+}
+
static struct dentry *sysfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
@@ -108,11 +116,11 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
return ERR_PTR(-ENOMEM);
for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
- info->ns[type] = kobj_ns_current(type);
+ info->ns[type] = kobj_ns_grab_current(type);
sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info);
if (IS_ERR(sb) || sb->s_fs_info != info)
- kfree(info);
+ free_sysfs_super_info(info);
if (IS_ERR(sb))
return ERR_CAST(sb);
if (!sb->s_root) {
@@ -131,12 +139,11 @@ 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);
-
/* Remove the superblock from fs_supers/s_instances
* so we can't find it, before freeing sysfs_super_info.
*/
kill_anon_super(sb);
- kfree(info);
+ free_sysfs_super_info(info);
}
static struct file_system_type sysfs_fs_type = {
@@ -145,28 +152,6 @@ 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 3d28af31d86..2ed2404f311 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 82cb5bf461f..f66b065a8b5 100644
--- a/include/linux/kobject_ns.h
+++ b/include/linux/kobject_ns.h
@@ -32,15 +32,17 @@ enum kobj_ns_type {
/*
* 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 @@ 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_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 */
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index c3acda60eee..e2696d76a59 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 2bf9ed9ef26..aef430d779b 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_drop_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_drop_ns NULL
#endif
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);
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 11b98bc2aa8..33d2a1fba13 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_grab_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)
@@ -1196,22 +1201,13 @@ static const void *net_netlink_ns(struct sock *sk)
struct kobj_ns_type_operations net_ns_type_operations = {
.type = KOBJ_NS_TYPE_NET,
- .current_ns = net_current_ns,
+ .grab_current_ns = net_grab_current_ns,
.netlink_ns = net_netlink_ns,
.initial_ns = net_initial_ns,
+ .drop_ns = net_drop_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 6c6b86d0da1..cdcbc3cb00a 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_drop_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_drop_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_drop_ns(net);
}
}
static DECLARE_WORK(net_cleanup_work, cleanup_net);