caif: Protected in-flight packets using dev or sock refcont.

CAIF Socket Layer and ip-interface registers reference counters
in CAIF service layer. The functions sock_hold, sock_put and
dev_hold, dev_put are used by CAIF Stack to protect from freeing
memory while packets are in-flight.
Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/caif/caif_dev.h

@@ -73,6 +73,23 @@ int caif_connect_client(struct caif_connect_request *conn_req,
  */
 int caif_disconnect_client(struct cflayer *client_layer);
 
+/**
+ * caif_client_register_refcnt - register ref-count functions provided by client.
+ *
+ * @adapt_layer: Client layer using CAIF Stack.
+ * @hold:	Function provided by client layer increasing ref-count
+ * @put:	Function provided by client layer decreasing ref-count
+ *
+ * Client of the CAIF Stack must register functions for reference counting.
+ * These functions are called by the CAIF Stack for every upstream packet,
+ * and must therefore be implemented efficiently.
+ *
+ * Client should call caif_free_client when reference count degrease to zero.
+ */
+
+void caif_client_register_refcnt(struct cflayer *adapt_layer,
+					void (*hold)(struct cflayer *lyr),
+					void (*put)(struct cflayer *lyr));
 /**
  * caif_connect_req_to_link_param - Translate configuration parameters
  *				    from socket format to internal format.
@@ -83,8 +100,20 @@ int caif_disconnect_client(struct cflayer *client_layer);
  *			 setting up channels.
  *
  */
+
 int caif_connect_req_to_link_param(struct cfcnfg *cnfg,
 				   struct caif_connect_request *con_req,
 				   struct cfctrl_link_param *setup_param);
 
+/**
+ * caif_free_client - Free memory used to manage the client in the CAIF Stack.
+ *
+ * @client_layer: Client layer to be removed.
+ *
+ * This function must be called from client layer in order to free memory.
+ * Caller must guarantee that no packets are in flight upstream when calling
+ * this function.
+ */
+void caif_free_client(struct cflayer *adap_layer);
+
 #endif /* CAIF_DEV_H_ */

net/caif/caif_socket.c

@@ -209,6 +209,18 @@ static int caif_sktrecv_cb(struct cflayer *layr, struct cfpkt *pkt)
 	return 0;
 }
 
+static void cfsk_hold(struct cflayer *layr)
+{
+	struct caifsock *cf_sk = container_of(layr, struct caifsock, layer);
+	sock_hold(&cf_sk->sk);
+}
+
+static void cfsk_put(struct cflayer *layr)
+{
+	struct caifsock *cf_sk = container_of(layr, struct caifsock, layer);
+	sock_put(&cf_sk->sk);
+}
+
 /* Packet Control Callback function called from CAIF */
 static void caif_ctrl_cb(struct cflayer *layr,
 				enum caif_ctrlcmd flow,
@@ -232,6 +244,8 @@ static void caif_ctrl_cb(struct cflayer *layr,
 
 	case CAIF_CTRLCMD_INIT_RSP:
 		/* We're now connected */
+		caif_client_register_refcnt(&cf_sk->layer,
+						cfsk_hold, cfsk_put);
 		dbfs_atomic_inc(&cnt.num_connect_resp);
 		cf_sk->sk.sk_state = CAIF_CONNECTED;
 		set_tx_flow_on(cf_sk);
@@ -242,7 +256,6 @@ static void caif_ctrl_cb(struct cflayer *layr,
 		/* We're now disconnected */
 		cf_sk->sk.sk_state = CAIF_DISCONNECTED;
 		cf_sk->sk.sk_state_change(&cf_sk->sk);
-		cfcnfg_release_adap_layer(&cf_sk->layer);
 		break;
 
 	case CAIF_CTRLCMD_INIT_FAIL_RSP:
@@ -837,8 +850,10 @@ static int caif_connect(struct socket *sock, struct sockaddr *uaddr,
 
 	dbfs_atomic_inc(&cnt.num_connect_req);
 	cf_sk->layer.receive = caif_sktrecv_cb;
+
 	err = caif_connect_client(&cf_sk->conn_req,
 				&cf_sk->layer, &ifindex, &headroom, &tailroom);
+
 	if (err < 0) {
 		cf_sk->sk.sk_socket->state = SS_UNCONNECTED;
 		cf_sk->sk.sk_state = CAIF_DISCONNECTED;
@@ -940,7 +955,6 @@ static int caif_release(struct socket *sock)
 	wake_up_interruptible_poll(sk_sleep(sk), POLLERR|POLLHUP);
 
 	sock_orphan(sk);
-	cf_sk->layer.dn = NULL;
 	sk_stream_kill_queues(&cf_sk->sk);
 	release_sock(sk);
 	sock_put(sk);
@@ -1036,6 +1050,7 @@ static void caif_sock_destructor(struct sock *sk)
 	}
 	sk_stream_kill_queues(&cf_sk->sk);
 	dbfs_atomic_dec(&cnt.caif_nr_socks);
+	caif_free_client(&cf_sk->layer);
 }
 
 static int caif_create(struct net *net, struct socket *sock, int protocol,

net/caif/chnl_net.c

@@ -153,6 +153,18 @@ static void close_work(struct work_struct *work)
 }
 static DECLARE_WORK(close_worker, close_work);
 
+static void chnl_hold(struct cflayer *lyr)
+{
+	struct chnl_net *priv = container_of(lyr, struct chnl_net, chnl);
+	dev_hold(priv->netdev);
+}
+
+static void chnl_put(struct cflayer *lyr)
+{
+	struct chnl_net *priv = container_of(lyr, struct chnl_net, chnl);
+	dev_put(priv->netdev);
+}
+
 static void chnl_flowctrl_cb(struct cflayer *layr, enum caif_ctrlcmd flow,
 				int phyid)
 {
@@ -190,6 +202,7 @@ static void chnl_flowctrl_cb(struct cflayer *layr, enum caif_ctrlcmd flow,
 		netif_wake_queue(priv->netdev);
 		break;
 	case CAIF_CTRLCMD_INIT_RSP:
+		caif_client_register_refcnt(&priv->chnl, chnl_hold, chnl_put);
 		priv->state = CAIF_CONNECTED;
 		priv->flowenabled = true;
 		netif_wake_queue(priv->netdev);
@@ -373,11 +386,18 @@ static const struct net_device_ops netdev_ops = {
 	.ndo_start_xmit = chnl_net_start_xmit,
 };
 
+static void chnl_net_destructor(struct net_device *dev)
+{
+	struct chnl_net *priv = netdev_priv(dev);
+	caif_free_client(&priv->chnl);
+	free_netdev(dev);
+}
+
 static void ipcaif_net_setup(struct net_device *dev)
 {
 	struct chnl_net *priv;
 	dev->netdev_ops = &netdev_ops;
-	dev->destructor = free_netdev;
+	dev->destructor = chnl_net_destructor;
 	dev->flags |= IFF_NOARP;
 	dev->flags |= IFF_POINTOPOINT;
 	dev->mtu = GPRS_PDP_MTU;
@@ -391,7 +411,7 @@ static void ipcaif_net_setup(struct net_device *dev)
 	priv->conn_req.link_selector = CAIF_LINK_HIGH_BANDW;
 	priv->conn_req.priority = CAIF_PRIO_LOW;
 	/* Insert illegal value */
-	priv->conn_req.sockaddr.u.dgm.connection_id = -1;
+	priv->conn_req.sockaddr.u.dgm.connection_id = 0;
 	priv->flowenabled = false;
 
 	init_waitqueue_head(&priv->netmgmt_wq);
@@ -453,6 +473,10 @@ static int ipcaif_newlink(struct net *src_net, struct net_device *dev,
 		pr_warn("device rtml registration failed\n");
 	else
 		list_add(&caifdev->list_field, &chnl_net_list);
+
+	/* Take ifindex as connection-id if null */
+	if (caifdev->conn_req.sockaddr.u.dgm.connection_id == 0)
+		caifdev->conn_req.sockaddr.u.dgm.connection_id = dev->ifindex;
 	return ret;
 }