[PATCH v6 06/18] xen/pvcalls: handle commands from the frontend

[Stefano Stabellini <sstabellini@kernel.org>]

When the other end notifies us that there are commands to be read
(pvcalls_back_event), wake up the backend thread to parse the command.

The command ring works like most other Xen rings, so use the usual
ring macros to read and write to it. The functions implementing the
commands are empty stubs for now.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 144 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 129 insertions(+), 15 deletions(-)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index e4c2e46..9e00971 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -47,16 +47,135 @@ struct pvcalls_fedata {
 	struct list_head socket_mappings;
 	struct radix_tree_root socketpass_mappings;
 	struct semaphore socket_lock;
-	struct workqueue_struct *wq;
-	struct work_struct register_work;
 };
 
-static void pvcalls_back_work(struct work_struct *work)
+static int pvcalls_back_socket(struct xenbus_device *dev,
+		struct xen_pvcalls_request *req)
 {
+	return 0;
+}
+
+static int pvcalls_back_connect(struct xenbus_device *dev,
+				struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_release(struct xenbus_device *dev,
+				struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_bind(struct xenbus_device *dev,
+			     struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_listen(struct xenbus_device *dev,
+			       struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_accept(struct xenbus_device *dev,
+			       struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_poll(struct xenbus_device *dev,
+			     struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_handle_cmd(struct xenbus_device *dev,
+				   struct xen_pvcalls_request *req)
+{
+	int ret = 0;
+
+	switch (req->cmd) {
+	case PVCALLS_SOCKET:
+		ret = pvcalls_back_socket(dev, req);
+		break;
+	case PVCALLS_CONNECT:
+		ret = pvcalls_back_connect(dev, req);
+		break;
+	case PVCALLS_RELEASE:
+		ret = pvcalls_back_release(dev, req);
+		break;
+	case PVCALLS_BIND:
+		ret = pvcalls_back_bind(dev, req);
+		break;
+	case PVCALLS_LISTEN:
+		ret = pvcalls_back_listen(dev, req);
+		break;
+	case PVCALLS_ACCEPT:
+		ret = pvcalls_back_accept(dev, req);
+		break;
+	case PVCALLS_POLL:
+		ret = pvcalls_back_poll(dev, req);
+		break;
+	default:
+	{
+		struct pvcalls_fedata *fedata;
+		struct xen_pvcalls_response *rsp;
+
+		fedata = dev_get_drvdata(&dev->dev);
+		rsp = RING_GET_RESPONSE(
+				&fedata->ring, fedata->ring.rsp_prod_pvt++);
+		rsp->req_id = req->req_id;
+		rsp->cmd = req->cmd;
+		rsp->ret = -ENOTSUPP;
+		break;
+	}
+	}
+	return ret;
+}
+
+static void pvcalls_back_work(struct pvcalls_fedata *fedata)
+{
+	int notify, notify_all = 0, more = 1;
+	struct xen_pvcalls_request req;
+	struct xenbus_device *dev = fedata->dev;
+
+	while (more) {
+		while (RING_HAS_UNCONSUMED_REQUESTS(&fedata->ring)) {
+			RING_COPY_REQUEST(&fedata->ring,
+					  fedata->ring.req_cons++,
+					  &req);
+
+			if (!pvcalls_back_handle_cmd(dev, &req)) {
+				RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(
+					&fedata->ring, notify);
+				notify_all += notify;
+			}
+		}
+
+		if (notify_all) {
+			notify_remote_via_irq(fedata->irq);
+			notify_all = 0;
+		}
+
+		RING_FINAL_CHECK_FOR_REQUESTS(&fedata->ring, more);
+	}
 }
 
 static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
 {
+	struct xenbus_device *dev = dev_id;
+	struct pvcalls_fedata *fedata = NULL;
+
+	if (dev == NULL)
+		return IRQ_HANDLED;
+
+	fedata = dev_get_drvdata(&dev->dev);
+	if (fedata == NULL)
+		return IRQ_HANDLED;
+
+	pvcalls_back_work(fedata);
 	return IRQ_HANDLED;
 }
 
@@ -87,18 +206,15 @@ static int backend_connect(struct xenbus_device *dev)
 		goto error;
 	}
 
-	err = bind_interdomain_evtchn_to_irqhandler(dev->otherend_id, evtchn,
-						    pvcalls_back_event, 0,
-						    "pvcalls-backend", dev);
+	err = bind_interdomain_evtchn_to_irq(dev->otherend_id, evtchn);
 	if (err < 0)
 		goto error;
 	fedata->irq = err;
-
-	fedata->wq = alloc_workqueue("pvcalls_back_wq", WQ_UNBOUND, 1);
-	if (!fedata->wq) {
-		err = -ENOMEM;
+	
+	err = request_threaded_irq(fedata->irq, NULL, pvcalls_back_event,
+				   IRQF_ONESHOT, "pvcalls-back", dev);
+	if (err < 0)
 		goto error;
-	}
 
 	err = xenbus_map_ring_valloc(dev, &ring_ref, 1, (void**)&fedata->sring);
 	if (err < 0)
@@ -107,7 +223,6 @@ static int backend_connect(struct xenbus_device *dev)
 	BACK_RING_INIT(&fedata->ring, fedata->sring, XEN_PAGE_SIZE * 1);
 	fedata->dev = dev;
 
-	INIT_WORK(&fedata->register_work, pvcalls_back_work);
 	INIT_LIST_HEAD(&fedata->socket_mappings);
 	INIT_RADIX_TREE(&fedata->socketpass_mappings, GFP_KERNEL);
 	sema_init(&fedata->socket_lock, 1);
@@ -116,15 +231,14 @@ static int backend_connect(struct xenbus_device *dev)
 	down(&pvcalls_back_global.frontends_lock);
 	list_add_tail(&fedata->list, &pvcalls_back_global.frontends);
 	up(&pvcalls_back_global.frontends_lock);
-	queue_work(fedata->wq, &fedata->register_work);
+
+	pvcalls_back_work(fedata);
 
 	return 0;
 
  error:
 	if (fedata->sring != NULL)
 		xenbus_unmap_ring_vfree(dev, fedata->sring);
-	if (fedata->wq)
-		destroy_workqueue(fedata->wq);
 	unbind_from_irqhandler(fedata->irq, dev);
 	kfree(fedata);
 	return err;
-- 
1.9.1