[PATCH v2 08/18] xen/pvcalls: implement connect command

[Stefano Stabellini]

Allocate a socket. Keep track of socket <-> ring mappings with a new data
structure, called sock_mapping. Implement the connect command by calling
inet_stream_connect, and mapping the new indexes page and data ring.
Allocate a workqueue and a work_struct, called ioworker, to perform
reads and writes to the socket.

When an active socket is closed (sk_state_change), set in_error to
-ENOTCONN and notify the other end, as specified by the protocol.

sk_data_ready and pvcalls_back_ioworker will be implemented later.

Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
CC: boris.ostrovsky@xxxxxxxxxx
CC: jgross@xxxxxxxx
---
 drivers/xen/pvcalls-back.c | 161 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 161 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index fed54bf..65fbc39 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -57,6 +57,40 @@ struct pvcalls_back_priv {
 	struct work_struct register_work;
 };
 
+struct pvcalls_ioworker {
+	struct work_struct register_work;
+	struct workqueue_struct *wq;
+	unsigned int cpu;
+};
+
+struct sock_mapping {
+	struct list_head list;
+	struct pvcalls_back_priv *priv;
+	struct socket *sock;
+	uint64_t id;
+	grant_ref_t ref;
+	struct pvcalls_data_intf *ring;
+	void *bytes;
+	struct pvcalls_data data;
+	uint32_t ring_order;
+	int irq;
+	atomic_t read;
+	atomic_t write;
+	atomic_t io;
+	atomic_t release;
+	void (*saved_data_ready)(struct sock *sk);
+	struct pvcalls_ioworker ioworker;
+};
+
+static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
+static int pvcalls_back_release_active(struct xenbus_device *dev,
+				       struct pvcalls_back_priv *priv,
+				       struct sock_mapping *map);
+
+static void pvcalls_back_ioworker(struct work_struct *work)
+{
+}
+
 static int pvcalls_back_socket(struct xenbus_device *dev,
 		struct xen_pvcalls_request *req)
 {
@@ -85,9 +119,131 @@ static int pvcalls_back_socket(struct xenbus_device *dev,
 	return ret;
 }
 
+static void pvcalls_sk_state_change(struct sock *sock)
+{
+	struct sock_mapping *map = sock->sk_user_data;
+	struct pvcalls_data_intf *intf;
+
+	if (map == NULL)
+		return;
+
+	intf = map->ring;
+	intf->in_error = -ENOTCONN;
+	notify_remote_via_irq(map->irq);
+}
+
+static void pvcalls_sk_data_ready(struct sock *sock)
+{
+}
+
 static int pvcalls_back_connect(struct xenbus_device *dev,
 				struct xen_pvcalls_request *req)
 {
+	struct pvcalls_back_priv *priv;
+	int ret;
+	struct socket *sock;
+	struct sock_mapping *map = NULL;
+	void *page;
+	struct xen_pvcalls_response *rsp;
+
+	priv = dev_get_drvdata(&dev->dev);
+
+	map = kzalloc(sizeof(*map), GFP_KERNEL);
+	if (map == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
+	if (ret < 0) {
+		kfree(map);
+		goto out;
+	}
+
+	map->priv = priv;
+	map->sock = sock;
+	map->id = req->u.connect.id;
+	map->ref = req->u.connect.ref;
+
+	ret = xenbus_map_ring_valloc(dev, &req->u.connect.ref, 1, &page);
+	if (ret < 0) {
+		sock_release(map->sock);
+		kfree(map);
+		goto out;
+	}
+	map->ring = page;
+	map->ring_order = map->ring->ring_order;
+	/* first read the order, then map the data ring */
+	virt_rmb();
+	if (map->ring_order > MAX_RING_ORDER) {
+		ret = -EFAULT;
+		goto out;
+	}
+	ret = xenbus_map_ring_valloc(dev, map->ring->ref,
+				     (1 << map->ring_order), &page);
+	if (ret < 0) {
+		sock_release(map->sock);
+		xenbus_unmap_ring_vfree(dev, map->ring);
+		kfree(map);
+		goto out;
+	}
+	map->bytes = page;
+
+	ret = bind_interdomain_evtchn_to_irqhandler(priv->dev->otherend_id,
+						    req->u.connect.evtchn,
+						    pvcalls_back_conn_event,
+						    0,
+						    "pvcalls-backend",
+						    map);
+	if (ret < 0) {
+		sock_release(map->sock);
+		kfree(map);
+		goto out;
+	}
+	map->irq = ret;
+
+	map->data.in = map->bytes;
+	map->data.out = map->bytes + XEN_FLEX_RING_SIZE(map->ring_order);
+
+	map->ioworker.wq = alloc_workqueue("pvcalls_io", WQ_UNBOUND, 1);
+	if (!map->ioworker.wq) {
+	    ret = -ENOMEM;
+	    goto out;
+	}
+	map->ioworker.cpu = get_random_int() % num_online_cpus();
+	atomic_set(&map->io, 1);
+	INIT_WORK(&map->ioworker.register_work,	pvcalls_back_ioworker);
+
+	down(&priv->socket_lock);
+	list_add_tail(&map->list, &priv->socket_mappings);
+	up(&priv->socket_lock);
+
+	ret = inet_stream_connect(sock, (struct sockaddr *)&req->u.connect.addr,
+				  req->u.connect.len, req->u.connect.flags);
+	if (ret < 0) {
+		pvcalls_back_release_active(dev, priv, map);
+	} else {
+		write_lock_bh(&sock->sk->sk_callback_lock);
+		map->saved_data_ready = sock->sk->sk_data_ready;
+		sock->sk->sk_user_data = map;
+		sock->sk->sk_data_ready = pvcalls_sk_data_ready;
+		sock->sk->sk_state_change = pvcalls_sk_state_change;
+		write_unlock_bh(&sock->sk->sk_callback_lock);
+	}
+
+out:
+	rsp = RING_GET_RESPONSE(&priv->ring, priv->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->cmd = req->cmd;
+	rsp->u.connect.id = req->u.connect.id;
+	rsp->ret = ret;
+
+	return ret;
+}
+
+static int pvcalls_back_release_active(struct xenbus_device *dev,
+				       struct pvcalls_back_priv *priv,
+				       struct sock_mapping *map)
+{
 	return 0;
 }
 
@@ -203,6 +359,11 @@ static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
+{
+	return IRQ_HANDLED;
+}
+
 static int backend_connect(struct xenbus_device *dev)
 {
 	int err, evtchn;
-- 
1.9.1