sctp: use new rhlist interface on sctp transport rhashtable

Now sctp transport rhashtable uses hash(lport, dport, daddr) as the key
to hash a node to one chain. If in one host thousands of assocs connect
to one server with the same lport and different laddrs (although it's
not a normal case), all the transports would be hashed into the same
chain.

It may cause to keep returning -EBUSY when inserting a new node, as the
chain is too long and sctp inserts a transport node in a loop, which
could even lead to system hangs there.

The new rhlist interface works for this case that there are many nodes
with the same key in one chain. It puts them into a list then makes this
list be as a node of the chain.

This patch is to replace rhashtable_ interface with rhltable_ interface.
Since a chain would not be too long and it would not return -EBUSY with
this fix when inserting a node, the reinsert loop is also removed here.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 5 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index f23ad913dc7a..d5f4b4a8369b 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4392,10 +4392,7 @@ int sctp_transport_walk_start(struct rhashtable_iter *iter)
 {
 	int err;
 
-	err = rhashtable_walk_init(&sctp_transport_hashtable, iter,
-				   GFP_KERNEL);
-	if (err)
-		return err;
+	rhltable_walk_enter(&sctp_transport_hashtable, iter);
 
 	err = rhashtable_walk_start(iter);
 	if (err && err != -EAGAIN) {
@@ -4479,7 +4476,7 @@ int sctp_transport_lookup_process(int (*cb)(struct sctp_transport *, void *),
 
 	rcu_read_lock();
 	transport = sctp_addrs_lookup_transport(net, laddr, paddr);
-	if (!transport || !sctp_transport_hold(transport))
+	if (!transport)
 		goto out;
 
 	rcu_read_unlock();