net: Batch inet_twsk_purge

This function walks the whole hashtable so there is no point in
passing it a network namespace.  Instead I purge all timewait
sockets from dead network namespaces that I find.  If the namespace
is one of the once I am trying to purge I am guaranteed no new timewait
sockets can be formed so this will get them all.  If the namespace
is one I am not acting for it might form a few more but I will
call inet_twsk_purge again and  shortly to get rid of them.  In
any even if the network namespace is dead timewait sockets are
useless.

Move the calls of inet_twsk_purge into batch_exit routines so
that if I am killing a bunch of namespaces at once I will just
call inet_twsk_purge once and save a lot of redundant unnecessary
work.

My simple 4k network namespace exit test the cleanup time dropped from
roughly 8.2s to 1.6s.  While the time spent running inet_twsk_purge fell
to about 2ms.  1ms for ipv4 and 1ms for ipv6.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 3 deletions

diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
index 773b10fa38e4..4fd007f34dd5 100644
--- a/include/net/inet_timewait_sock.h
+++ b/include/net/inet_timewait_sock.h
@@ -212,14 +212,14 @@ extern void inet_twsk_schedule(struct inet_timewait_sock *tw,
 extern void inet_twsk_deschedule(struct inet_timewait_sock *tw,
                                  struct inet_timewait_death_row *twdr);
 
-extern void inet_twsk_purge(struct net *net, struct inet_hashinfo *hashinfo,
+extern void inet_twsk_purge(struct inet_hashinfo *hashinfo,
                             struct inet_timewait_death_row *twdr, int family);
 
 static inline
 struct net *twsk_net(const struct inet_timewait_sock *twsk)
 {
 #ifdef CONFIG_NET_NS
-        return twsk->tw_net;
+        return rcu_dereference(twsk->tw_net);
 #else
         return &init_net;
 #endif
@@ -229,7 +229,7 @@ static inline
 void twsk_net_set(struct inet_timewait_sock *twsk, struct net *net)
 {
 #ifdef CONFIG_NET_NS
-        twsk->tw_net = net;
+        rcu_assign_pointer(twsk->tw_net, net);
 #endif
 }
 #endif  /* _INET_TIMEWAIT_SOCK_ */