rxrpc: Fix apparent leak of rxrpc_local objects

rxrpc_local objects cannot be disposed of until all the connections that
point to them have been RCU'd as a connection object holds refcount on the
local endpoint it is communicating through.  Currently, this can cause an
assertion failure to occur when a network namespace is destroyed as there's
no check that the RCU destructors for the connections have been run before
we start trying to destroy local endpoints.

The kernel reports:

	rxrpc: AF_RXRPC: Leaked local 0000000036a41bc1 {5}
	------------[ cut here ]------------
	kernel BUG at ../net/rxrpc/local_object.c:439!

Fix this by keeping a count of the live connections and waiting for it to
go to zero at the end of rxrpc_destroy_all_connections().

Fixes: dee46364ce6f ("rxrpc: Add RCU destruction for connections and calls")
Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/net/rxrpc/conn_object.c b/net/rxrpc/conn_object.c
index bfc46fd69a62..0950ee3d26f5 100644
--- a/net/rxrpc/conn_object.c
+++ b/net/rxrpc/conn_object.c
@@ -365,6 +365,9 @@ static void rxrpc_destroy_connection(struct rcu_head *rcu)
 	key_put(conn->params.key);
 	key_put(conn->server_key);
 	rxrpc_put_peer(conn->params.peer);
+
+	if (atomic_dec_and_test(&conn->params.local->rxnet->nr_conns))
+		wake_up_atomic_t(&conn->params.local->rxnet->nr_conns);
 	rxrpc_put_local(conn->params.local);
 
 	kfree(conn);
@@ -458,6 +461,7 @@ void rxrpc_destroy_all_connections(struct rxrpc_net *rxnet)
 
 	_enter("");
 
+	atomic_dec(&rxnet->nr_conns);
 	rxrpc_destroy_all_client_connections(rxnet);
 
 	del_timer_sync(&rxnet->service_conn_reap_timer);
@@ -475,5 +479,9 @@ void rxrpc_destroy_all_connections(struct rxrpc_net *rxnet)
 
 	ASSERT(list_empty(&rxnet->conn_proc_list));
 
+	/* We need to wait for the connections to be destroyed by RCU as they
+	 * pin things that we still need to get rid of.
+	 */
+	wait_on_atomic_t(&rxnet->nr_conns, atomic_t_wait, TASK_UNINTERRUPTIBLE);
 	_leave("");
 }