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[PATCH v4 06/18] xen/pvcalls: handle commands from the frontend

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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 | 119 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index e4c2e46..437c2ad 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -51,12 +51,131 @@ struct pvcalls_fedata {
 	struct work_struct register_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:
+		ret = -ENOTSUPP;
+		break;
+	}
+	return ret;
+}
+
 static void pvcalls_back_work(struct work_struct *work)
 {
+	struct pvcalls_fedata *fedata = container_of(work,
+		struct pvcalls_fedata, register_work);
+	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);
+
+		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;
+
+	/*
+	 * TODO: a small theoretical race exists if we try to queue work
+	 * after pvcalls_back_work checked for final requests and before
+	 * it returns. The queuing will fail, and pvcalls_back_work
+	 * won't do the work because it is about to return. In that
+	 * case, we lose the notification.
+	 */
+	queue_work(fedata->wq, &fedata->register_work);
+
 	return IRQ_HANDLED;
 }
 
-- 
1.9.1

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[PATCH v4 00/18] introduce the Xen PV Calls backend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:10 +0200
  [PATCH v4 06/18] xen/pvcalls: handle commands from the frontend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 04/18] xen/pvcalls: xenbus state handling Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 16/18] xen/pvcalls: implement read Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 08/18] xen/pvcalls: implement connect command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 15/18] xen/pvcalls: implement the ioworker functions Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 12/18] xen/pvcalls: implement poll command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 02/18] xen/pvcalls: introduce the pvcalls xenbus backend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 10/18] xen/pvcalls: implement listen command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 09/18] xen/pvcalls: implement bind command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 17/18] xen/pvcalls: implement write Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 07/18] xen/pvcalls: implement socket command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 03/18] xen/pvcalls: initialize the module and register the xenbus backend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 18/18] xen: introduce a Kconfig option to enable the pvcalls backend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 05/18] xen/pvcalls: connect to a frontend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 14/18] xen/pvcalls: disconnect and module_exit Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
  [PATCH v4 01/18] xen: introduce the pvcalls interface header Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
    [PATCH v4 13/18] xen/pvcalls: implement release command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200
    [PATCH v4 11/18] xen/pvcalls: implement accept command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-15 21:20 +0200

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