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authorKirill Tkhai <ktkhai@virtuozzo.com>2018-03-30 19:38:27 +0300
committerDavid S. Miller <davem@davemloft.net>2018-03-31 22:24:58 -0400
commitfc1dd36992bb041b4470120aecf8986910c56088 (patch)
tree7fbea89ad406d55660f89abf4f380b7e010b565d /net/core
parentc679f6a26dc3d450b76e94717850a14ff706cc58 (diff)
downloadlinux-fc1dd36992bb041b4470120aecf8986910c56088.tar.gz
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>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/dev.c5
1 files changed, 0 insertions, 5 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 07da7add4845..8edb58829124 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -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 @@ rollback:
 	}
 
 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);