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| author | Kirill Tkhai <ktkhai@virtuozzo.com> | 2018-03-30 19:38:37 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-03-31 22:24:58 -0400 |
| commit | 554873e517115c4b7207259f1cadfd77d90b5395 (patch) | |
| tree | bc6dd02f1ba8878c6fd3ecb8ce86e1f0d6fdb4c9 /net/core | |
| parent | fc1dd36992bb041b4470120aecf8986910c56088 (diff) | |
| download | linux-stable-554873e517115c4b7207259f1cadfd77d90b5395.tar.gz linux-stable-554873e517115c4b7207259f1cadfd77d90b5395.tar.bz2 linux-stable-554873e517115c4b7207259f1cadfd77d90b5395.zip | |
net: Do not take net_rwsem in __rtnl_link_unregister()
This function calls call_netdevice_notifier(), which also
may take net_rwsem. So, we can't use net_rwsem here.
This patch makes callers of this functions take pernet_ops_rwsem,
like register_netdevice_notifier() does. This will protect
the modifications of net_namespace_list, and allows notifiers
to take it (they won't have to care about context).
Since __rtnl_link_unregister() is used on module load
and unload (which are not frequent operations), this looks
for me better, than make all call_netdevice_notifier()
always executing in "protected net_namespace_list" context.
Also, this fixes the problem we had a deal in 328fbe747ad4
"Close race between {un, }register_netdevice_notifier and ...",
and guarantees __rtnl_link_unregister() does not skip
exitting net.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/net_namespace.c | 1 | ||||
| -rw-r--r-- | net/core/rtnetlink.c | 6 |
2 files changed, 4 insertions, 3 deletions
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 7fdf321d4997..a11e03f920d3 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -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 *)) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index e86b28482ca7..45936922d7e2 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -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); |