net: Remove net_rwsem from {, un}register_netdevice_notifier() (fc1dd369) · Commits · 戴 / test

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: "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>

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 @@ 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);

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