net: Remove net_rwsem from {, un}register_netdevice_notifier()
These functions take net_rwsem, while wireless_nlevent_flush()
also takes it. But down_read() can't be taken recursive,
because of rw_semaphore design, which prevents it to be occupied
by only readers forever.
Since we take pernet_ops_rwsem in {,un}register_netdevice_notifier(),
net list can't change, so these down_read()/up_read() can be removed.
Fixes: f0b07bb151b0 "net: Introduce net_rwsem to protect net_namespace_list"
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 07da7ad..8edb588 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1633,7 +1633,6 @@
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 @@
call_netdevice_notifier(nb, NETDEV_UP, dev);
}
}
- up_read(&net_rwsem);
unlock:
rtnl_unlock();
@@ -1671,7 +1669,6 @@
}
outroll:
- up_read(&net_rwsem);
raw_notifier_chain_unregister(&netdev_chain, nb);
goto unlock;
}
@@ -1704,7 +1701,6 @@
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 @@
call_netdevice_notifier(nb, NETDEV_UNREGISTER, dev);
}
}
- up_read(&net_rwsem);
unlock:
rtnl_unlock();
up_write(&pernet_ops_rwsem);