ipvs: convert dests to rcu

In previous commits the schedulers started to access
svc->destinations with _rcu list traversal primitives
because the IP_VS_WAIT_WHILE macro still plays the role of
grace period. Now it is time to finish the updating part,
i.e. adding and deleting of dests with _rcu suffix before
removing the IP_VS_WAIT_WHILE in next commit.

We use the same rule for conns as for the
schedulers: dests can be searched in RCU read-side critical
section where ip_vs_dest_hold can be called by ip_vs_bind_dest.

Some things are not perfect, for example, calling
functions like ip_vs_lookup_dest from updating code under
RCU, just because we use some function both from reader
and from updater.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

1 files changed, 4 insertions, 7 deletions

diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
index 6cc3e52f1f35..97241749216d 100644
--- a/net/netfilter/ipvs/ip_vs_sync.c
+++ b/net/netfilter/ipvs/ip_vs_sync.c
@@ -858,23 +858,20 @@ static void ip_vs_proc_conn(struct net *net, struct ip_vs_conn_param *param,
 		flags |= cp->flags & ~IP_VS_CONN_F_BACKUP_UPD_MASK;
 		cp->flags = flags;
 		spin_unlock(&cp->lock);
-		if (!dest) {
-			dest = ip_vs_try_bind_dest(cp);
-			if (dest)
-				ip_vs_dest_put(dest);
-		}
+		if (!dest)
+			ip_vs_try_bind_dest(cp);
 	} else {
 		/*
 		 * Find the appropriate destination for the connection.
 		 * If it is not found the connection will remain unbound
 		 * but still handled.
 		 */
+		rcu_read_lock();
 		dest = ip_vs_find_dest(net, type, daddr, dport, param->vaddr,
 				       param->vport, protocol, fwmark, flags);
 
 		cp = ip_vs_conn_new(param, daddr, dport, flags, dest, fwmark);
-		if (dest)
-			ip_vs_dest_put(dest);
+		rcu_read_unlock();
 		if (!cp) {
 			if (param->pe_data)
 				kfree(param->pe_data);