diff options
| 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/netfilter | |
| parent | 906edee91e79af5a348f1ad1b3f9b4b948db3db7 (diff) | |
| download | linux-f0b07bb151b098d291fd1fd71ef7a2df56fb124a.tar.gz | |
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/netfilter')
| -rw-r--r-- | net/netfilter/nf_conntrack_core.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 705198de671d..370f9b7f051b 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1764,12 +1764,14 @@ nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data), void *data) struct net *net; rtnl_lock(); + down_read(&net_rwsem); for_each_net(net) { if (atomic_read(&net->ct.count) == 0) continue; __nf_ct_unconfirmed_destroy(net); nf_queue_nf_hook_drop(net); } + up_read(&net_rwsem); rtnl_unlock(); /* Need to wait for netns cleanup worker to finish, if its |