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authorKirill Tkhai <ktkhai@virtuozzo.com>2018-03-29 19:20:32 +0300
committerDavid S. Miller <davem@davemloft.net>2018-03-29 13:47:53 -0400
commitf0b07bb151b098d291fd1fd71ef7a2df56fb124a (patch)
tree24f28ec5ec61e4b0950fef35da79853357a34afb /security
parent906edee91e79af5a348f1ad1b3f9b4b948db3db7 (diff)
downloadlinux-stericsson-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 'security')
-rw-r--r--security/selinux/include/xfrm.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/security/selinux/include/xfrm.h b/security/selinux/include/xfrm.h
index 1f173a7a4daa..31d66431be1e 100644
--- a/security/selinux/include/xfrm.h
+++ b/security/selinux/include/xfrm.h
@@ -48,8 +48,10 @@ static inline void selinux_xfrm_notify_policyload(void)
struct net *net;
rtnl_lock();
+ down_read(&net_rwsem);
for_each_net(net)
rt_genid_bump_all(net);
+ up_read(&net_rwsem);
rtnl_unlock();
}
#else