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/wireless | |
| parent | 906edee91e79af5a348f1ad1b3f9b4b948db3db7 (diff) | |
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/wireless')
| -rw-r--r-- | net/wireless/wext-core.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index 9efbfc753347..544d7b62d7ca 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -349,11 +349,13 @@ void wireless_nlevent_flush(void) ASSERT_RTNL(); + down_read(&net_rwsem); for_each_net(net) { while ((skb = skb_dequeue(&net->wext_nlevents))) rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_KERNEL); } + up_read(&net_rwsem); } EXPORT_SYMBOL_GPL(wireless_nlevent_flush); |