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| author | Kirill Tkhai <ktkhai@virtuozzo.com> | 2018-03-29 19:20:32 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-03-29 13:47:53 -0400 |
| commit | f0b07bb151b098d291fd1fd71ef7a2df56fb124a (patch) | |
| tree | 24f28ec5ec61e4b0950fef35da79853357a34afb /net/openvswitch | |
| parent | 906edee91e79af5a348f1ad1b3f9b4b948db3db7 (diff) | |
| download | linux-f0b07bb151b098d291fd1fd71ef7a2df56fb124a.tar.gz linux-f0b07bb151b098d291fd1fd71ef7a2df56fb124a.tar.bz2 linux-f0b07bb151b098d291fd1fd71ef7a2df56fb124a.zip | |
net: Introduce net_rwsem to protect net_namespace_list
rtnl_lock() is used everywhere, and contention is very high.
When someone wants to iterate over alive net namespaces,
he/she has no a possibility to do that without exclusive lock.
But the exclusive rtnl_lock() in such places is overkill,
and it just increases the contention. Yes, there is already
for_each_net_rcu() in kernel, but it requires rcu_read_lock(),
and this can't be sleepable. Also, sometimes it may be need
really prevent net_namespace_list growth, so for_each_net_rcu()
is not fit there.
This patch introduces new rw_semaphore, which will be used
instead of rtnl_mutex to protect net_namespace_list. It is
sleepable and allows not-exclusive iterations over net
namespaces list. It allows to stop using rtnl_lock()
in several places (what is made in next patches) and makes
less the time, we keep rtnl_mutex. Here we just add new lock,
while the explanation of we can remove rtnl_lock() there are
in next patches.
Fine grained locks generally are better, then one big lock,
so let's do that with net_namespace_list, while the situation
allows that.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/openvswitch')
| -rw-r--r-- | net/openvswitch/datapath.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c index ef38e5aecd28..9746ee30a99b 100644 --- a/net/openvswitch/datapath.c +++ b/net/openvswitch/datapath.c @@ -2364,8 +2364,10 @@ static void __net_exit ovs_exit_net(struct net *dnet) __dp_destroy(dp); rtnl_lock(); + down_read(&net_rwsem); for_each_net(net) list_vports_from_net(net, dnet, &head); + up_read(&net_rwsem); rtnl_unlock(); /* Detach all vports from given namespace. */ |