diff options
| -rw-r--r-- | include/linux/rtnetlink.h | 1 | ||||
| -rw-r--r-- | include/net/net_namespace.h | 12 | ||||
| -rw-r--r-- | net/core/net_namespace.c | 75 |
3 files changed, 47 insertions, 41 deletions
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index e9ee9ad0a681..3573b4bf2fdf 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -35,7 +35,6 @@ extern int rtnl_trylock(void); 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 diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 9158ec1ad06f..d4417495773a 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -59,8 +59,12 @@ struct net { atomic64_t cookie_gen; struct list_head list; /* list of network namespaces */ - struct list_head cleanup_list; /* namespaces on death row */ - struct list_head exit_list; /* Use only net_mutex */ + struct list_head exit_list; /* To linked to call pernet exit + * methods on dead net (net_sem + * read locked), or to unregister + * pernet ops (net_sem wr locked). + */ + struct llist_node cleanup_list; /* namespaces on death row */ struct user_namespace *user_ns; /* Owning user namespace */ struct ucounts *ucounts; @@ -89,7 +93,7 @@ struct net { /* core fib_rules */ struct list_head rules_ops; - struct list_head fib_notifier_ops; /* protected by net_mutex */ + struct list_head fib_notifier_ops; /* protected by net_sem */ struct net_device *loopback_dev; /* The loopback */ struct netns_core core; @@ -316,7 +320,7 @@ struct pernet_operations { /* * Indicates above methods are allowed to be executed in parallel * with methods of any other pernet_operations, i.e. they are not - * need synchronization via net_mutex. + * need write locked net_sem. */ bool async; }; diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index bcab9a938d6f..27a55236ad64 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -29,8 +29,6 @@ static LIST_HEAD(pernet_list); static struct list_head *first_device = &pernet_list; -/* Used only if there are !async pernet_operations registered */ -DEFINE_MUTEX(net_mutex); LIST_HEAD(net_namespace_list); EXPORT_SYMBOL_GPL(net_namespace_list); @@ -407,6 +405,7 @@ struct net *copy_net_ns(unsigned long flags, { struct ucounts *ucounts; struct net *net; + unsigned write; int rv; if (!(flags & CLONE_NEWNET)) @@ -424,20 +423,26 @@ struct net *copy_net_ns(unsigned long flags, refcount_set(&net->passive, 1); net->ucounts = ucounts; get_user_ns(user_ns); - - rv = down_read_killable(&net_sem); +again: + write = READ_ONCE(nr_sync_pernet_ops); + if (write) + rv = down_write_killable(&net_sem); + else + rv = down_read_killable(&net_sem); if (rv < 0) goto put_userns; - if (nr_sync_pernet_ops) { - rv = mutex_lock_killable(&net_mutex); - if (rv < 0) - goto up_read; + + if (!write && unlikely(READ_ONCE(nr_sync_pernet_ops))) { + up_read(&net_sem); + goto again; } rv = setup_net(net, user_ns); - if (nr_sync_pernet_ops) - mutex_unlock(&net_mutex); -up_read: - up_read(&net_sem); + + if (write) + up_write(&net_sem); + else + up_read(&net_sem); + if (rv < 0) { put_userns: put_user_ns(user_ns); @@ -476,28 +481,33 @@ static void unhash_nsid(struct net *net, struct net *last) spin_unlock_bh(&net->nsid_lock); } -static DEFINE_SPINLOCK(cleanup_list_lock); -static LIST_HEAD(cleanup_list); /* Must hold cleanup_list_lock to touch */ +static LLIST_HEAD(cleanup_list); static void cleanup_net(struct work_struct *work) { const struct pernet_operations *ops; struct net *net, *tmp, *last; - struct list_head net_kill_list; + struct llist_node *net_kill_list; LIST_HEAD(net_exit_list); + unsigned write; /* Atomically snapshot the list of namespaces to cleanup */ - spin_lock_irq(&cleanup_list_lock); - list_replace_init(&cleanup_list, &net_kill_list); - spin_unlock_irq(&cleanup_list_lock); + net_kill_list = llist_del_all(&cleanup_list); +again: + write = READ_ONCE(nr_sync_pernet_ops); + if (write) + down_write(&net_sem); + else + down_read(&net_sem); - down_read(&net_sem); - if (nr_sync_pernet_ops) - mutex_lock(&net_mutex); + if (!write && unlikely(READ_ONCE(nr_sync_pernet_ops))) { + up_read(&net_sem); + goto again; + } /* Don't let anyone else find us. */ rtnl_lock(); - list_for_each_entry(net, &net_kill_list, cleanup_list) + llist_for_each_entry(net, net_kill_list, cleanup_list) list_del_rcu(&net->list); /* Cache last net. After we unlock rtnl, no one new net * added to net_namespace_list can assign nsid pointer @@ -512,7 +522,7 @@ static void cleanup_net(struct work_struct *work) last = list_last_entry(&net_namespace_list, struct net, list); rtnl_unlock(); - list_for_each_entry(net, &net_kill_list, cleanup_list) { + llist_for_each_entry(net, net_kill_list, cleanup_list) { unhash_nsid(net, last); list_add_tail(&net->exit_list, &net_exit_list); } @@ -528,14 +538,14 @@ static void cleanup_net(struct work_struct *work) list_for_each_entry_reverse(ops, &pernet_list, list) ops_exit_list(ops, &net_exit_list); - if (nr_sync_pernet_ops) - mutex_unlock(&net_mutex); - /* Free the net generic variables */ list_for_each_entry_reverse(ops, &pernet_list, list) ops_free_list(ops, &net_exit_list); - up_read(&net_sem); + if (write) + up_write(&net_sem); + else + up_read(&net_sem); /* Ensure there are no outstanding rcu callbacks using this * network namespace. @@ -563,8 +573,6 @@ static void cleanup_net(struct work_struct *work) void net_ns_barrier(void) { down_write(&net_sem); - mutex_lock(&net_mutex); - mutex_unlock(&net_mutex); up_write(&net_sem); } EXPORT_SYMBOL(net_ns_barrier); @@ -574,13 +582,8 @@ static DECLARE_WORK(net_cleanup_work, cleanup_net); void __put_net(struct net *net) { /* Cleanup the network namespace in process context */ - unsigned long flags; - - spin_lock_irqsave(&cleanup_list_lock, flags); - list_add(&net->cleanup_list, &cleanup_list); - spin_unlock_irqrestore(&cleanup_list_lock, flags); - - queue_work(netns_wq, &net_cleanup_work); + if (llist_add(&net->cleanup_list, &cleanup_list)) + queue_work(netns_wq, &net_cleanup_work); } EXPORT_SYMBOL_GPL(__put_net); |