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Message-Id: <1497553787-3709-4-git-send-email-sstabellini@kernel.org>
Date: Thu, 15 Jun 2017 12:09:33 -0700
From: Stefano Stabellini <sstabellini@...nel.org>
To: xen-devel@...ts.xen.org
Cc: linux-kernel@...r.kernel.org, sstabellini@...nel.org,
jgross@...e.com, boris.ostrovsky@...cle.com,
Stefano Stabellini <stefano@...reto.com>
Subject: [PATCH v4 04/18] xen/pvcalls: xenbus state handling
Introduce the code to handle xenbus state changes.
Implement the probe function for the pvcalls backend. Write the
supported versions, max-page-order and function-calls nodes to xenstore,
as required by the protocol.
Introduce stub functions for disconnecting/connecting to a frontend.
Signed-off-by: Stefano Stabellini <stefano@...reto.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
CC: boris.ostrovsky@...cle.com
CC: jgross@...e.com
---
drivers/xen/pvcalls-back.c | 152 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 152 insertions(+)
diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 9044cf2..7bce750 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -25,20 +25,172 @@
#include <xen/xenbus.h>
#include <xen/interface/io/pvcalls.h>
+#define PVCALLS_VERSIONS "1"
+#define MAX_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
+
struct pvcalls_back_global {
struct list_head frontends;
struct semaphore frontends_lock;
} pvcalls_back_global;
+static int backend_connect(struct xenbus_device *dev)
+{
+ return 0;
+}
+
+static int backend_disconnect(struct xenbus_device *dev)
+{
+ return 0;
+}
+
static int pvcalls_back_probe(struct xenbus_device *dev,
const struct xenbus_device_id *id)
{
+ int err, abort;
+ struct xenbus_transaction xbt;
+
+again:
+ abort = 1;
+
+ err = xenbus_transaction_start(&xbt);
+ if (err) {
+ pr_warn("%s cannot create xenstore transaction\n", __func__);
+ return err;
+ }
+
+ err = xenbus_printf(xbt, dev->nodename, "versions", "%s",
+ PVCALLS_VERSIONS);
+ if (err) {
+ pr_warn("%s write out 'version' failed\n", __func__);
+ goto abort;
+ }
+
+ err = xenbus_printf(xbt, dev->nodename, "max-page-order", "%u",
+ MAX_RING_ORDER);
+ if (err) {
+ pr_warn("%s write out 'max-page-order' failed\n", __func__);
+ goto abort;
+ }
+
+ err = xenbus_printf(xbt, dev->nodename, "function-calls",
+ XENBUS_FUNCTIONS_CALLS);
+ if (err) {
+ pr_warn("%s write out 'function-calls' failed\n", __func__);
+ goto abort;
+ }
+
+ abort = 0;
+abort:
+ err = xenbus_transaction_end(xbt, abort);
+ if (err) {
+ if (err == -EAGAIN && !abort)
+ goto again;
+ pr_warn("%s cannot complete xenstore transaction\n", __func__);
+ return err;
+ }
+
+ xenbus_switch_state(dev, XenbusStateInitWait);
+
return 0;
}
+static void set_backend_state(struct xenbus_device *dev,
+ enum xenbus_state state)
+{
+ while (dev->state != state) {
+ switch (dev->state) {
+ case XenbusStateClosed:
+ switch (state) {
+ case XenbusStateInitWait:
+ case XenbusStateConnected:
+ xenbus_switch_state(dev, XenbusStateInitWait);
+ break;
+ case XenbusStateClosing:
+ xenbus_switch_state(dev, XenbusStateClosing);
+ break;
+ default:
+ __WARN();
+ }
+ break;
+ case XenbusStateInitWait:
+ case XenbusStateInitialised:
+ switch (state) {
+ case XenbusStateConnected:
+ backend_connect(dev);
+ xenbus_switch_state(dev, XenbusStateConnected);
+ break;
+ case XenbusStateClosing:
+ case XenbusStateClosed:
+ xenbus_switch_state(dev, XenbusStateClosing);
+ break;
+ default:
+ __WARN();
+ }
+ break;
+ case XenbusStateConnected:
+ switch (state) {
+ case XenbusStateInitWait:
+ case XenbusStateClosing:
+ case XenbusStateClosed:
+ down(&pvcalls_back_global.frontends_lock);
+ backend_disconnect(dev);
+ up(&pvcalls_back_global.frontends_lock);
+ xenbus_switch_state(dev, XenbusStateClosing);
+ break;
+ default:
+ __WARN();
+ }
+ break;
+ case XenbusStateClosing:
+ switch (state) {
+ case XenbusStateInitWait:
+ case XenbusStateConnected:
+ case XenbusStateClosed:
+ xenbus_switch_state(dev, XenbusStateClosed);
+ break;
+ default:
+ __WARN();
+ }
+ break;
+ default:
+ __WARN();
+ }
+ }
+}
+
static void pvcalls_back_changed(struct xenbus_device *dev,
enum xenbus_state frontend_state)
{
+ switch (frontend_state) {
+ case XenbusStateInitialising:
+ set_backend_state(dev, XenbusStateInitWait);
+ break;
+
+ case XenbusStateInitialised:
+ case XenbusStateConnected:
+ set_backend_state(dev, XenbusStateConnected);
+ break;
+
+ case XenbusStateClosing:
+ set_backend_state(dev, XenbusStateClosing);
+ break;
+
+ case XenbusStateClosed:
+ set_backend_state(dev, XenbusStateClosed);
+ if (xenbus_dev_is_online(dev))
+ break;
+ device_unregister(&dev->dev);
+ break;
+ case XenbusStateUnknown:
+ set_backend_state(dev, XenbusStateClosed);
+ device_unregister(&dev->dev);
+ break;
+
+ default:
+ xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
+ frontend_state);
+ break;
+ }
}
static int pvcalls_back_remove(struct xenbus_device *dev)
--
1.9.1
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