vsock: prevent transport modules unloading
This patch adds 'module' member in the 'struct vsock_transport'
in order to get/put the transport module. This prevents the
module unloading while sockets are assigned to it.
We increase the module refcnt when a socket is assigned to a
transport, and we decrease the module refcnt when the socket
is destructed.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Jorgen Hansen <jhansen@vmware.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 5357714..5cb0ae4 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -380,6 +380,16 @@ void vsock_enqueue_accept(struct sock *listener, struct sock *connected)
}
EXPORT_SYMBOL_GPL(vsock_enqueue_accept);
+static void vsock_deassign_transport(struct vsock_sock *vsk)
+{
+ if (!vsk->transport)
+ return;
+
+ vsk->transport->destruct(vsk);
+ module_put(vsk->transport->module);
+ vsk->transport = NULL;
+}
+
/* Assign a transport to a socket and call the .init transport callback.
*
* Note: for stream socket this must be called when vsk->remote_addr is set
@@ -418,10 +428,13 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
return 0;
vsk->transport->release(vsk);
- vsk->transport->destruct(vsk);
+ vsock_deassign_transport(vsk);
}
- if (!new_transport)
+ /* We increase the module refcnt to prevent the transport unloading
+ * while there are open sockets assigned to it.
+ */
+ if (!new_transport || !try_module_get(new_transport->module))
return -ENODEV;
vsk->transport = new_transport;
@@ -741,8 +754,7 @@ static void vsock_sk_destruct(struct sock *sk)
{
struct vsock_sock *vsk = vsock_sk(sk);
- if (vsk->transport)
- vsk->transport->destruct(vsk);
+ vsock_deassign_transport(vsk);
/* When clearing these addresses, there's no need to set the family and
* possibly register the address family with the kernel.