From fc1dd36992bb041b4470120aecf8986910c56088 Mon Sep 17 00:00:00 2001 From: Kirill Tkhai Date: Fri, 30 Mar 2018 19:38:27 +0300 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- net/core/dev.c | 5 ----- 1 file changed, 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 @@ 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); -- GitLab