xen/netfront: fix waiting for xenbus state change

Commit 822fb18a82aba ("xen-netfront: wait xenbus state change when load
module manually") added a new wait queue to wait on for a state change
when the module is loaded manually. Unfortunately there is no wakeup
anywhere to stop that waiting.

Instead of introducing a new wait queue rename the existing
module_unload_q to module_wq and use it for both purposes (loading and
unloading).

As any state change of the backend might be intended to stop waiting
do the wake_up_all() in any case when netback_changed() is called.

Fixes: 822fb18a82aba ("xen-netfront: wait xenbus state change when load module manually")
Cc: <stable@vger.kernel.org> #4.18
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 14 deletions

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 73f596a90c69..9407acbd19a9 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -87,8 +87,7 @@ struct netfront_cb {
 /* IRQ name is queue name with "-tx" or "-rx" appended */
 #define IRQ_NAME_SIZE (QUEUE_NAME_SIZE + 3)
 
-static DECLARE_WAIT_QUEUE_HEAD(module_load_q);
-static DECLARE_WAIT_QUEUE_HEAD(module_unload_q);
+static DECLARE_WAIT_QUEUE_HEAD(module_wq);
 
 struct netfront_stats {
         u64                     packets;
@@ -1332,11 +1331,11 @@ static struct net_device *xennet_create_dev(struct xenbus_device *dev)
         netif_carrier_off(netdev);
 
         xenbus_switch_state(dev, XenbusStateInitialising);
-        wait_event(module_load_q,
-                           xenbus_read_driver_state(dev->otherend) !=
-                           XenbusStateClosed &&
-                           xenbus_read_driver_state(dev->otherend) !=
-                           XenbusStateUnknown);
+        wait_event(module_wq,
+                   xenbus_read_driver_state(dev->otherend) !=
+                   XenbusStateClosed &&
+                   xenbus_read_driver_state(dev->otherend) !=
+                   XenbusStateUnknown);
         return netdev;
 
  exit:
@@ -2010,15 +2009,14 @@ static void netback_changed(struct xenbus_device *dev,
 
         dev_dbg(&dev->dev, "%s\n", xenbus_strstate(backend_state));
 
+        wake_up_all(&module_wq);
+
         switch (backend_state) {
         case XenbusStateInitialising:
         case XenbusStateInitialised:
         case XenbusStateReconfiguring:
         case XenbusStateReconfigured:
-                break;
-
         case XenbusStateUnknown:
-                wake_up_all(&module_unload_q);
                 break;
 
         case XenbusStateInitWait:
@@ -2034,12 +2032,10 @@ static void netback_changed(struct xenbus_device *dev,
                 break;
 
         case XenbusStateClosed:
-                wake_up_all(&module_unload_q);
                 if (dev->state == XenbusStateClosed)
                         break;
                 /* Missed the backend's CLOSING state -- fallthrough */
         case XenbusStateClosing:
-                wake_up_all(&module_unload_q);
                 xenbus_frontend_closed(dev);
                 break;
         }
@@ -2147,14 +2143,14 @@ static int xennet_remove(struct xenbus_device *dev)
 
         if (xenbus_read_driver_state(dev->otherend) != XenbusStateClosed) {
                 xenbus_switch_state(dev, XenbusStateClosing);
-                wait_event(module_unload_q,
+                wait_event(module_wq,
                            xenbus_read_driver_state(dev->otherend) ==
                            XenbusStateClosing ||
                            xenbus_read_driver_state(dev->otherend) ==
                            XenbusStateUnknown);
 
                 xenbus_switch_state(dev, XenbusStateClosed);
-                wait_event(module_unload_q,
+                wait_event(module_wq,
                            xenbus_read_driver_state(dev->otherend) ==
                            XenbusStateClosed ||
                            xenbus_read_driver_state(dev->otherend) ==