2 files changed, 37 insertions, 1 deletions

diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index 3159a37d966d..a7e25073de19 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -29,6 +29,8 @@
 #include "xenbus_probe.h"
 
 
+static struct workqueue_struct *xenbus_frontend_wq;
+
 /* device/<type>/<id> => <type>-<id> */
 static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
 {
@@ -89,9 +91,40 @@ static void backend_changed(struct xenbus_watch *watch,
         xenbus_otherend_changed(watch, vec, len, 1);
 }
 
+static void xenbus_frontend_delayed_resume(struct work_struct *w)
+{
+        struct xenbus_device *xdev = container_of(w, struct xenbus_device, work);
+
+        xenbus_dev_resume(&xdev->dev);
+}
+
+static int xenbus_frontend_dev_resume(struct device *dev)
+{
+        /*
+         * If xenstored is running in this domain, we cannot access the backend
+         * state at the moment, so we need to defer xenbus_dev_resume
+         */
+        if (xen_store_domain_type == XS_LOCAL) {
+                struct xenbus_device *xdev = to_xenbus_device(dev);
+
+                if (!xenbus_frontend_wq) {
+                        pr_err("%s: no workqueue to process delayed resume\n",
+                               xdev->nodename);
+                        return -EFAULT;
+                }
+
+                INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume);
+                queue_work(xenbus_frontend_wq, &xdev->work);
+
+                return 0;
+        }
+
+        return xenbus_dev_resume(dev);
+}
+
 static const struct dev_pm_ops xenbus_pm_ops = {
         .suspend        = xenbus_dev_suspend,
-        .resume         = xenbus_dev_resume,
+        .resume         = xenbus_frontend_dev_resume,
         .freeze         = xenbus_dev_suspend,
         .thaw           = xenbus_dev_cancel,
         .restore        = xenbus_dev_resume,
@@ -440,6 +473,8 @@ static int __init xenbus_probe_frontend_init(void)
 
         register_xenstore_notifier(&xenstore_notifier);
 
+        xenbus_frontend_wq = create_workqueue("xenbus_frontend");
+
         return 0;
 }
 subsys_initcall(xenbus_probe_frontend_init);
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index 0a7515c1e3a4..569c07f2e344 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -70,6 +70,7 @@ struct xenbus_device {
         struct device dev;
         enum xenbus_state state;
         struct completion down;
+        struct work_struct work;
 };
 
 static inline struct xenbus_device *to_xenbus_device(struct device *dev)