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: dee46364ce ("rxrpc: Add RCU destruction for connections and calls")
Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2018-03-30 21:05:33 +01:00
parent 09d2bf595d
commit 31f5f9a169
6 changed files with 14 additions and 0 deletions

View File

@ -77,6 +77,7 @@ struct rxrpc_net {
rwlock_t call_lock; /* Lock for ->calls */
atomic_t nr_calls; /* Count of allocated calls */
atomic_t nr_conns;
struct list_head conn_proc_list; /* List of conns in this namespace for proc */
struct list_head service_conns; /* Service conns in this namespace */
rwlock_t conn_lock; /* Lock for ->conn_proc_list, ->service_conns */

View File

@ -219,6 +219,8 @@ void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
list_del(&conn->proc_link);
write_unlock(&rxnet->conn_lock);
kfree(conn);
if (atomic_dec_and_test(&rxnet->nr_conns))
wake_up_atomic_t(&rxnet->nr_conns);
tail = (tail + 1) & (size - 1);
}

View File

@ -207,6 +207,7 @@ rxrpc_alloc_client_connection(struct rxrpc_conn_parameters *cp, gfp_t gfp)
if (ret < 0)
goto error_2;
atomic_inc(&rxnet->nr_conns);
write_lock(&rxnet->conn_lock);
list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
write_unlock(&rxnet->conn_lock);

View File

@ -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("");
}

View File

@ -132,6 +132,7 @@ struct rxrpc_connection *rxrpc_prealloc_service_connection(struct rxrpc_net *rxn
conn->state = RXRPC_CONN_SERVICE_PREALLOC;
atomic_set(&conn->usage, 2);
atomic_inc(&rxnet->nr_conns);
write_lock(&rxnet->conn_lock);
list_add_tail(&conn->link, &rxnet->service_conns);
list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);

View File

@ -57,6 +57,7 @@ static __net_init int rxrpc_init_net(struct net *net)
rwlock_init(&rxnet->call_lock);
atomic_set(&rxnet->nr_calls, 1);
atomic_set(&rxnet->nr_conns, 1);
INIT_LIST_HEAD(&rxnet->conn_proc_list);
INIT_LIST_HEAD(&rxnet->service_conns);
rwlock_init(&rxnet->conn_lock);