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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: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2018-03-31 22:24:58 -04:00
parent c679f6a26d 554873e517
commit b3834acdd7
5 changed files with 8 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/dummy.c
View File

@ -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;
}

2
drivers/net/ifb.c
View File

@ -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;
}

5
net/core/dev.c
View File

@ -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);

1
net/core/net_namespace.c
View File

@ -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 *))

6
net/core/rtnetlink.c
View File

@ -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);