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Commit b3834acd authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'net_rwsem-fixes' 



Kirill Tkhai says:

====================
net_rwsem fixes

there is wext_netdev_notifier_call()->wireless_nlevent_flush()
netdevice notifier, which takes net_rwsem, so we can't take
net_rwsem in {,un}register_netdevice_notifier().

Since {,un}register_netdevice_notifier() is executed under
pernet_ops_rwsem, net_namespace_list can't change, while we
holding it, so there is no need net_rwsem in these functions [1/2].

The same is in [2/2]. We make callers of __rtnl_link_unregister()
take pernet_ops_rwsem, and close the race with setup_net()
and cleanup_net(), so __rtnl_link_unregister() does not need it.
This also fixes the problem of that __rtnl_link_unregister() does
not see initializing and exiting nets.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents c679f6a2 554873e5

drivers/net/dummy.c

+2 −0
Original line number Diff line number Diff line
@@ -219,6 +219,7 @@ static int __init dummy_init_module(void) 
{

	int i, err = 0;



	down_write(&pernet_ops_rwsem);

	rtnl_lock();

	err = __rtnl_link_register(&dummy_link_ops);

	if (err < 0)
@@ -233,6 +234,7 @@ static int __init dummy_init_module(void) 


out:

	rtnl_unlock();

	up_write(&pernet_ops_rwsem);



	return err;

}

drivers/net/ifb.c

+2 −0
Original line number Diff line number Diff line
@@ -330,6 +330,7 @@ static int __init ifb_init_module(void) 
{

	int i, err;



	down_write(&pernet_ops_rwsem);

	rtnl_lock();

	err = __rtnl_link_register(&ifb_link_ops);

	if (err < 0)
@@ -344,6 +345,7 @@ static int __init ifb_init_module(void) 


out:

	rtnl_unlock();

	up_write(&pernet_ops_rwsem);



	return err;

}

net/core/dev.c

+0 −5
Original line number Diff line number Diff line
@@ -1633,7 +1633,6 @@ int register_netdevice_notifier(struct notifier_block *nb) 
		goto unlock;

	if (dev_boot_phase)

		goto unlock;

	down_read(&net_rwsem);

	for_each_net(net) {

		for_each_netdev(net, dev) {

			err = call_netdevice_notifier(nb, NETDEV_REGISTER, dev);
@@ -1647,7 +1646,6 @@ int register_netdevice_notifier(struct notifier_block *nb) 
			call_netdevice_notifier(nb, NETDEV_UP, dev);

		}

	}

	up_read(&net_rwsem);



unlock:

	rtnl_unlock();
@@ -1671,7 +1669,6 @@ int register_netdevice_notifier(struct notifier_block *nb) 
	}



outroll:

	up_read(&net_rwsem);

	raw_notifier_chain_unregister(&netdev_chain, nb);

	goto unlock;

}
@@ -1704,7 +1701,6 @@ int unregister_netdevice_notifier(struct notifier_block *nb) 
	if (err)

		goto unlock;



	down_read(&net_rwsem);

	for_each_net(net) {

		for_each_netdev(net, dev) {

			if (dev->flags & IFF_UP) {
@@ -1715,7 +1711,6 @@ int unregister_netdevice_notifier(struct notifier_block *nb) 
			call_netdevice_notifier(nb, NETDEV_UNREGISTER, dev);

		}

	}

	up_read(&net_rwsem);

unlock:

	rtnl_unlock();

	up_write(&pernet_ops_rwsem);

net/core/net_namespace.c

+1 −0
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ static bool init_net_initialized; 
 * outside.

 */

DECLARE_RWSEM(pernet_ops_rwsem);

EXPORT_SYMBOL_GPL(pernet_ops_rwsem);



#define MIN_PERNET_OPS_ID	\

	((sizeof(struct net_generic) + sizeof(void *) - 1) / sizeof(void *))

net/core/rtnetlink.c

+3 −3
Original line number Diff line number Diff line
@@ -412,17 +412,17 @@ static void __rtnl_kill_links(struct net *net, struct rtnl_link_ops *ops) 
 * __rtnl_link_unregister - Unregister rtnl_link_ops from rtnetlink.

 * @ops: struct rtnl_link_ops * to unregister

 *

 * The caller must hold the rtnl_mutex.

 * The caller must hold the rtnl_mutex and guarantee net_namespace_list

 * integrity (hold pernet_ops_rwsem for writing to close the race

 * with setup_net() and cleanup_net()).

 */

void __rtnl_link_unregister(struct rtnl_link_ops *ops)

{

	struct net *net;



	down_read(&net_rwsem);

	for_each_net(net) {

		__rtnl_kill_links(net, ops);

	}

	up_read(&net_rwsem);

	list_del(&ops->list);

}

EXPORT_SYMBOL_GPL(__rtnl_link_unregister);