1 files changed, 17 insertions, 54 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 2d02ca8a3da5..d8dd293a7a27 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -168,28 +168,6 @@ static int call_netdevice_notifiers_extack(unsigned long val,
 					   struct net_device *dev,
 					   struct netlink_ext_ack *extack);
 
-/*
- * The @dev_base_head list is protected by @dev_base_lock and the rtnl
- * semaphore.
- *
- * Pure readers hold dev_base_lock for reading, or rcu_read_lock()
- *
- * Writers must hold the rtnl semaphore while they loop through the
- * dev_base_head list, and hold dev_base_lock for writing when they do the
- * actual updates.  This allows pure readers to access the list even
- * while a writer is preparing to update it.
- *
- * To put it another way, dev_base_lock is held for writing only to
- * protect against pure readers; the rtnl semaphore provides the
- * protection against other writers.
- *
- * See, for example usages, register_netdevice() and
- * unregister_netdevice(), which must be called with the rtnl
- * semaphore held.
- */
-DEFINE_RWLOCK(dev_base_lock);
-EXPORT_SYMBOL(dev_base_lock);
-
 static DEFINE_MUTEX(ifalias_mutex);
 
 /* protects napi_hash addition/deletion and napi_gen_id */
@@ -395,12 +373,10 @@ static void list_netdevice(struct net_device *dev)
 
 	ASSERT_RTNL();
 
-	write_lock(&dev_base_lock);
 	list_add_tail_rcu(&dev->dev_list, &net->dev_base_head);
 	netdev_name_node_add(net, dev->name_node);
 	hlist_add_head_rcu(&dev->index_hlist,
 			   dev_index_hash(net, dev->ifindex));
-	write_unlock(&dev_base_lock);
 
 	netdev_for_each_altname(dev, name_node)
 		netdev_name_node_add(net, name_node);
@@ -414,7 +390,7 @@ static void list_netdevice(struct net_device *dev)
 /* Device list removal
  * caller must respect a RCU grace period before freeing/reusing dev
  */
-static void unlist_netdevice(struct net_device *dev, bool lock)
+static void unlist_netdevice(struct net_device *dev)
 {
 	struct netdev_name_node *name_node;
 	struct net *net = dev_net(dev);
@@ -427,13 +403,9 @@ static void unlist_netdevice(struct net_device *dev, bool lock)
 		netdev_name_node_del(name_node);
 
 	/* Unlink dev from the device chain */
-	if (lock)
-		write_lock(&dev_base_lock);
 	list_del_rcu(&dev->dev_list);
 	netdev_name_node_del(dev->name_node);
 	hlist_del_rcu(&dev->index_hlist);
-	if (lock)
-		write_unlock(&dev_base_lock);
 
 	dev_base_seq_inc(dev_net(dev));
 }
@@ -754,9 +726,9 @@ EXPORT_SYMBOL_GPL(dev_fill_forward_path);
  *	@net: the applicable net namespace
  *	@name: name to find
  *
- *	Find an interface by name. Must be called under RTNL semaphore
- *	or @dev_base_lock. If the name is found a pointer to the device
- *	is returned. If the name is not found then %NULL is returned. The
+ *	Find an interface by name. Must be called under RTNL semaphore.
+ *	If the name is found a pointer to the device is returned.
+ *	If the name is not found then %NULL is returned. The
  *	reference counters are not incremented so the caller must be
  *	careful with locks.
  */
@@ -837,8 +809,7 @@ EXPORT_SYMBOL(netdev_get_by_name);
  *	Search for an interface by index. Returns %NULL if the device
  *	is not found or a pointer to the device. The device has not
  *	had its reference counter increased so the caller must be careful
- *	about locking. The caller must hold either the RTNL semaphore
- *	or @dev_base_lock.
+ *	about locking. The caller must hold the RTNL semaphore.
  */
 
 struct net_device *__dev_get_by_index(struct net *net, int ifindex)
@@ -1228,13 +1199,13 @@ int dev_change_name(struct net_device *dev, const char *newname)
 			    dev->flags & IFF_UP ? " (while UP)" : "");
 
 	old_assign_type = dev->name_assign_type;
-	dev->name_assign_type = NET_NAME_RENAMED;
+	WRITE_ONCE(dev->name_assign_type, NET_NAME_RENAMED);
 
 rollback:
 	ret = device_rename(&dev->dev, dev->name);
 	if (ret) {
 		memcpy(dev->name, oldname, IFNAMSIZ);
-		dev->name_assign_type = old_assign_type;
+		WRITE_ONCE(dev->name_assign_type, old_assign_type);
 		up_write(&devnet_rename_sem);
 		return ret;
 	}
@@ -1243,15 +1214,11 @@ rollback:
 
 	netdev_adjacent_rename_links(dev, oldname);
 
-	write_lock(&dev_base_lock);
 	netdev_name_node_del(dev->name_node);
-	write_unlock(&dev_base_lock);
 
 	synchronize_net();
 
-	write_lock(&dev_base_lock);
 	netdev_name_node_add(net, dev->name_node);
-	write_unlock(&dev_base_lock);
 
 	ret = call_netdevice_notifiers(NETDEV_CHANGENAME, dev);
 	ret = notifier_to_errno(ret);
@@ -1263,7 +1230,7 @@ rollback:
 			down_write(&devnet_rename_sem);
 			memcpy(dev->name, oldname, IFNAMSIZ);
 			memcpy(oldname, newname, IFNAMSIZ);
-			dev->name_assign_type = old_assign_type;
+			WRITE_ONCE(dev->name_assign_type, old_assign_type);
 			old_assign_type = NET_NAME_RENAMED;
 			goto rollback;
 		} else {
@@ -8993,7 +8960,7 @@ int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
 }
 EXPORT_SYMBOL(dev_set_mac_address);
 
-static DECLARE_RWSEM(dev_addr_sem);
+DECLARE_RWSEM(dev_addr_sem);
 
 int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
 			     struct netlink_ext_ack *extack)
@@ -10338,9 +10305,9 @@ int register_netdevice(struct net_device *dev)
 		goto err_ifindex_release;
 
 	ret = netdev_register_kobject(dev);
-	write_lock(&dev_base_lock);
-	dev->reg_state = ret ? NETREG_UNREGISTERED : NETREG_REGISTERED;
-	write_unlock(&dev_base_lock);
+
+	WRITE_ONCE(dev->reg_state, ret ? NETREG_UNREGISTERED : NETREG_REGISTERED);
+
 	if (ret)
 		goto err_uninit_notify;
 
@@ -10629,9 +10596,7 @@ void netdev_run_todo(void)
 			continue;
 		}
 
-		write_lock(&dev_base_lock);
-		dev->reg_state = NETREG_UNREGISTERED;
-		write_unlock(&dev_base_lock);
+		WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERED);
 		linkwatch_sync_dev(dev);
 	}
 
@@ -11050,7 +11015,7 @@ void free_netdev(struct net_device *dev)
 	}
 
 	BUG_ON(dev->reg_state != NETREG_UNREGISTERED);
-	dev->reg_state = NETREG_RELEASED;
+	WRITE_ONCE(dev->reg_state, NETREG_RELEASED);
 
 	/* will free via device release */
 	put_device(&dev->dev);
@@ -11138,10 +11103,8 @@ void unregister_netdevice_many_notify(struct list_head *head,
 
 	list_for_each_entry(dev, head, unreg_list) {
 		/* And unlink it from device chain. */
-		write_lock(&dev_base_lock);
-		unlist_netdevice(dev, false);
-		dev->reg_state = NETREG_UNREGISTERING;
-		write_unlock(&dev_base_lock);
+		unlist_netdevice(dev);
+		WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERING);
 	}
 	flush_all_backlogs();
 
@@ -11323,7 +11286,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net,
 	dev_close(dev);
 
 	/* And unlink it from device chain */
-	unlist_netdevice(dev, true);
+	unlist_netdevice(dev);
 
 	synchronize_net();