net: qrtr: Move resume-tx transmission to recvmsg

The confirm-rx bit is used to implement a per port flow control, in
order to make sure that no messages are dropped due to resource
exhaustion. Move the resume-tx transmission to recvmsg to only confirm
messages as they are consumed by the application.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/qrtr/qrtr.c

@@ -362,22 +362,11 @@ static void qrtr_port_put(struct qrtr_sock *ipc);
 static void qrtr_node_rx_work(struct work_struct *work)
 {
 	struct qrtr_node *node = container_of(work, struct qrtr_node, work);
-	struct qrtr_ctrl_pkt *pkt;
-	struct sockaddr_qrtr dst;
-	struct sockaddr_qrtr src;
 	struct sk_buff *skb;
 
 	while ((skb = skb_dequeue(&node->rx_queue)) != NULL) {
 		struct qrtr_sock *ipc;
-		struct qrtr_cb *cb;
-		int confirm;
-
-		cb = (struct qrtr_cb *)skb->cb;
-		src.sq_node = cb->src_node;
-		src.sq_port = cb->src_port;
-		dst.sq_node = cb->dst_node;
-		dst.sq_port = cb->dst_port;
-		confirm = !!cb->confirm_rx;
+		struct qrtr_cb *cb = (struct qrtr_cb *)skb->cb;
 
 		qrtr_node_assign(node, cb->src_node);
 
@@ -390,20 +379,6 @@ static void qrtr_node_rx_work(struct work_struct *work)
 
 			qrtr_port_put(ipc);
 		}
-
-		if (confirm) {
-			skb = qrtr_alloc_ctrl_packet(&pkt);
-			if (!skb)
-				break;
-
-			pkt->cmd = cpu_to_le32(QRTR_TYPE_RESUME_TX);
-			pkt->client.node = cpu_to_le32(dst.sq_node);
-			pkt->client.port = cpu_to_le32(dst.sq_port);
-
-			if (qrtr_node_enqueue(node, skb, QRTR_TYPE_RESUME_TX,
-					      &dst, &src))
-				break;
-		}
 	}
 }
 
@@ -816,6 +791,34 @@ static int qrtr_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 	return rc;
 }
 
+static int qrtr_send_resume_tx(struct qrtr_cb *cb)
+{
+	struct sockaddr_qrtr remote = { AF_QIPCRTR, cb->src_node, cb->src_port };
+	struct sockaddr_qrtr local = { AF_QIPCRTR, cb->dst_node, cb->dst_port };
+	struct qrtr_ctrl_pkt *pkt;
+	struct qrtr_node *node;
+	struct sk_buff *skb;
+	int ret;
+
+	node = qrtr_node_lookup(remote.sq_node);
+	if (!node)
+		return -EINVAL;
+
+	skb = qrtr_alloc_ctrl_packet(&pkt);
+	if (!skb)
+		return -ENOMEM;
+
+	pkt->cmd = cpu_to_le32(QRTR_TYPE_RESUME_TX);
+	pkt->client.node = cpu_to_le32(cb->dst_node);
+	pkt->client.port = cpu_to_le32(cb->dst_port);
+
+	ret = qrtr_node_enqueue(node, skb, QRTR_TYPE_RESUME_TX, &local, &remote);
+
+	qrtr_node_release(node);
+
+	return ret;
+}
+
 static int qrtr_recvmsg(struct socket *sock, struct msghdr *msg,
 			size_t size, int flags)
 {
@@ -838,6 +841,7 @@ static int qrtr_recvmsg(struct socket *sock, struct msghdr *msg,
 		release_sock(sk);
 		return rc;
 	}
+	cb = (struct qrtr_cb *)skb->cb;
 
 	copied = skb->len;
 	if (copied > size) {
@@ -851,7 +855,6 @@ static int qrtr_recvmsg(struct socket *sock, struct msghdr *msg,
 	rc = copied;
 
 	if (addr) {
-		cb = (struct qrtr_cb *)skb->cb;
 		addr->sq_family = AF_QIPCRTR;
 		addr->sq_node = cb->src_node;
 		addr->sq_port = cb->src_port;
@@ -859,6 +862,9 @@ static int qrtr_recvmsg(struct socket *sock, struct msghdr *msg,
 	}
 
 out:
+	if (cb->confirm_rx)
+		qrtr_send_resume_tx(cb);
+
 	skb_free_datagram(sk, skb);
 	release_sock(sk);