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Subject[PATCH RESEND1 03/12] ALSA: vsnd: Implement Xen bus state handling
Date
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Initial handling for Xen bus states: implement
Xen bus state machine for the front driver according to
the state diagram and recovery flow from sound para-virtualized
protocol: xen/interface/io/sndif.h.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
sound/drivers/xen-front.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)

diff --git a/sound/drivers/xen-front.c b/sound/drivers/xen-front.c
index 8c5de7b0e7b5..c4fd21cac3a7 100644
--- a/sound/drivers/xen-front.c
+++ b/sound/drivers/xen-front.c
@@ -36,9 +36,99 @@ static void xdrv_remove_internal(struct xdrv_info *drv_info)
{
}

+static int xdrv_be_on_initwait(struct xdrv_info *drv_info)
+{
+ return 0;
+}
+
+static inline int xdrv_be_on_connected(struct xdrv_info *drv_info)
+{
+ return 0;
+}
+
+static inline void xdrv_be_on_disconnected(struct xdrv_info *drv_info)
+{
+ xdrv_remove_internal(drv_info);
+}
+
static void xdrv_be_on_changed(struct xenbus_device *xb_dev,
enum xenbus_state backend_state)
{
+ struct xdrv_info *drv_info = dev_get_drvdata(&xb_dev->dev);
+ int ret;
+
+ switch (backend_state) {
+ case XenbusStateReconfiguring:
+ /* fall through */
+ case XenbusStateReconfigured:
+ /* fall through */
+ case XenbusStateInitialised:
+ /* fall through */
+ break;
+
+ case XenbusStateInitialising:
+ if (xb_dev->state == XenbusStateInitialising)
+ break;
+
+ /* recovering after backend unexpected closure */
+ mutex_lock(&drv_info->mutex);
+ xdrv_be_on_disconnected(drv_info);
+ mutex_unlock(&drv_info->mutex);
+ xenbus_switch_state(xb_dev, XenbusStateInitialising);
+ break;
+
+ case XenbusStateInitWait:
+ if (xb_dev->state != XenbusStateInitialising)
+ break;
+
+ mutex_lock(&drv_info->mutex);
+ ret = xdrv_be_on_initwait(drv_info);
+ mutex_unlock(&drv_info->mutex);
+ if (ret < 0) {
+ xenbus_dev_fatal(xb_dev, ret,
+ "initializing " XENSND_DRIVER_NAME);
+ break;
+ }
+
+ xenbus_switch_state(xb_dev, XenbusStateInitialised);
+ break;
+
+ case XenbusStateConnected:
+ if (xb_dev->state != XenbusStateInitialised)
+ break;
+
+ mutex_lock(&drv_info->mutex);
+ ret = xdrv_be_on_connected(drv_info);
+ mutex_unlock(&drv_info->mutex);
+ if (ret < 0) {
+ xenbus_dev_fatal(xb_dev, ret,
+ "connecting " XENSND_DRIVER_NAME);
+ break;
+ }
+
+ xenbus_switch_state(xb_dev, XenbusStateConnected);
+ break;
+
+ case XenbusStateClosing:
+ /*
+ * in this state backend starts freeing resources,
+ * so let it go into closed state first, so we can also
+ * remove ours
+ */
+ break;
+
+ case XenbusStateUnknown:
+ /* fall through */
+ case XenbusStateClosed:
+ if (xb_dev->state == XenbusStateClosed)
+ break;
+
+ mutex_lock(&drv_info->mutex);
+ xdrv_be_on_disconnected(drv_info);
+ mutex_unlock(&drv_info->mutex);
+ xenbus_switch_state(xb_dev, XenbusStateInitialising);
+ break;
+ }
}

static int xdrv_probe(struct xenbus_device *xb_dev,
@@ -56,6 +146,7 @@ static int xdrv_probe(struct xenbus_device *xb_dev,
spin_lock_init(&drv_info->io_lock);
mutex_init(&drv_info->mutex);
dev_set_drvdata(&xb_dev->dev, drv_info);
+ xenbus_switch_state(xb_dev, XenbusStateInitialising);
return 0;
}

@@ -63,6 +154,7 @@ static int xdrv_remove(struct xenbus_device *dev)
{
struct xdrv_info *drv_info = dev_get_drvdata(&dev->dev);

+ xenbus_switch_state(dev, XenbusStateClosed);
mutex_lock(&drv_info->mutex);
xdrv_remove_internal(drv_info);
mutex_unlock(&drv_info->mutex);
--
2.7.4
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