@@ -35,6 +35,7 @@ extern int rtnl_is_locked(void);
extern wait_queue_head_t netdev_unregistering_wq;
extern struct mutex net_mutex;
+extern struct rw_semaphore net_sem;
#ifdef CONFIG_PROVE_LOCKING
extern bool lockdep_rtnl_is_held(void);
@@ -32,6 +32,11 @@
static LIST_HEAD(pernet_list);
static struct list_head *first_device = &pernet_list;
DEFINE_MUTEX(net_mutex);
+/*
+ * net_sem: protects: pernet_list, net_generic_ids,
+ * init_net_initialized and first_device pointer.
+ */
+DECLARE_RWSEM(net_sem);
LIST_HEAD(net_namespace_list);
EXPORT_SYMBOL_GPL(net_namespace_list);
@@ -302,7 +307,7 @@ static void dec_net_namespaces(struct ucounts *ucounts)
*/
static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
{
- /* Must be called with net_mutex held */
+ /* Must be called with net_sem held */
const struct pernet_operations *ops, *saved_ops;
int error = 0;
LIST_HEAD(net_exit_list);
@@ -421,12 +426,18 @@ struct net *copy_net_ns(unsigned long flags,
net->ucounts = ucounts;
get_user_ns(user_ns);
- rv = mutex_lock_killable(&net_mutex);
+ rv = down_read_killable(&net_sem);
if (rv < 0)
goto put_userns;
+ rv = mutex_lock_killable(&net_mutex);
+ if (rv < 0)
+ goto up_read;
+
rv = setup_net(net, user_ns);
mutex_unlock(&net_mutex);
+up_read:
+ up_read(&net_sem);
if (rv < 0) {
put_userns:
put_user_ns(user_ns);
@@ -482,6 +493,7 @@ static void cleanup_net(struct work_struct *work)
list_replace_init(&cleanup_list, &net_kill_list);
spin_unlock_irq(&cleanup_list_lock);
+ down_read(&net_sem);
mutex_lock(&net_mutex);
/* Don't let anyone else find us. */
@@ -521,6 +533,9 @@ static void cleanup_net(struct work_struct *work)
list_for_each_entry_reverse(ops, &pernet_list, list)
ops_free_list(ops, &net_exit_list);
+ mutex_unlock(&net_mutex);
+ up_read(&net_sem);
+
list_for_each_entry(net, &net_kill_list, cleanup_list) {
struct ve_struct *ve = net->owner_ve;
@@ -528,8 +543,6 @@ static void cleanup_net(struct work_struct *work)
put_ve(ve);
}
- mutex_unlock(&net_mutex);
-
/* Ensure there are no outstanding rcu callbacks using this
* network namespace.
*/
@@ -838,11 +851,11 @@ static int __init net_ns_init(void)
rcu_assign_pointer(init_net.gen, ng);
- mutex_lock(&net_mutex);
+ down_write(&net_sem);
if (setup_net(&init_net, &init_user_ns))
panic("Could not setup the initial network namespace");
- mutex_unlock(&net_mutex);
+ up_write(&net_sem);
register_pernet_subsys(&net_ns_ops);
@@ -972,9 +985,9 @@ static void unregister_pernet_operations(struct pernet_operations *ops)
int register_pernet_subsys(struct pernet_operations *ops)
{
int error;
- mutex_lock(&net_mutex);
+ down_write(&net_sem);
error = register_pernet_operations(first_device, ops);
- mutex_unlock(&net_mutex);
+ up_write(&net_sem);
return error;
}
EXPORT_SYMBOL_GPL(register_pernet_subsys);
@@ -990,9 +1003,9 @@ EXPORT_SYMBOL_GPL(register_pernet_subsys);
*/
void unregister_pernet_subsys(struct pernet_operations *ops)
{
- mutex_lock(&net_mutex);
+ down_write(&net_sem);
unregister_pernet_operations(ops);
- mutex_unlock(&net_mutex);
+ up_write(&net_sem);
}
EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
@@ -1018,11 +1031,11 @@ EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
int register_pernet_device(struct pernet_operations *ops)
{
int error;
- mutex_lock(&net_mutex);
+ down_write(&net_sem);
error = register_pernet_operations(&pernet_list, ops);
if (!error && (first_device == &pernet_list))
first_device = &ops->list;
- mutex_unlock(&net_mutex);
+ up_write(&net_sem);
return error;
}
EXPORT_SYMBOL_GPL(register_pernet_device);
@@ -1038,11 +1051,11 @@ EXPORT_SYMBOL_GPL(register_pernet_device);
*/
void unregister_pernet_device(struct pernet_operations *ops)
{
- mutex_lock(&net_mutex);
+ down_write(&net_sem);
if (&ops->list == first_device)
first_device = first_device->next;
unregister_pernet_operations(ops);
- mutex_unlock(&net_mutex);
+ up_write(&net_sem);
}
EXPORT_SYMBOL_GPL(unregister_pernet_device);
@@ -504,11 +504,11 @@ static void rtnl_lock_unregistering_all(void)
void rtnl_link_unregister(struct rtnl_link_ops *ops)
{
/* Close the race with cleanup_net() */
- mutex_lock(&net_mutex);
+ down_write(&net_sem);
rtnl_lock_unregistering_all();
__rtnl_link_unregister(ops);
rtnl_unlock();
- mutex_unlock(&net_mutex);
+ up_write(&net_sem);
}
EXPORT_SYMBOL_GPL(rtnl_link_unregister);