xenbus: rebind irq on restore

When restoring, rebind the existing xenbus irq to the new xenbus event
channel.  (It turns out in practice that this is always the same, and
is never updated on restore.  That's a bug, but Xeno-linux has been
like this for a long time, so it can't really be fixed.)

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 12 insertions, 11 deletions

diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
index 6efbe3f29ca5..090c61ee8fd0 100644
--- a/drivers/xen/xenbus/xenbus_comms.c
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -203,7 +203,6 @@ int xb_read(void *data, unsigned len)
 int xb_init_comms(void)
 {
         struct xenstore_domain_interface *intf = xen_store_interface;
-        int err;
 
         if (intf->req_prod != intf->req_cons)
                 printk(KERN_ERR "XENBUS request ring is not quiescent "
@@ -216,18 +215,20 @@ int xb_init_comms(void)
                 intf->rsp_cons = intf->rsp_prod;
         }
 
-        if (xenbus_irq)
-                unbind_from_irqhandler(xenbus_irq, &xb_waitq);
+        if (xenbus_irq) {
+                /* Already have an irq; assume we're resuming */
+                rebind_evtchn_irq(xen_store_evtchn, xenbus_irq);
+        } else {
+                int err;
+                err = bind_evtchn_to_irqhandler(xen_store_evtchn, wake_waiting,
+                                                0, "xenbus", &xb_waitq);
+                if (err <= 0) {
+                        printk(KERN_ERR "XENBUS request irq failed %i\n", err);
+                        return err;
+                }
 
-        err = bind_evtchn_to_irqhandler(
-                xen_store_evtchn, wake_waiting,
-                0, "xenbus", &xb_waitq);
-        if (err <= 0) {
-                printk(KERN_ERR "XENBUS request irq failed %i\n", err);
-                return err;
+                xenbus_irq = err;
         }
 
-        xenbus_irq = err;
-
         return 0;
 }