[Xen-devel] [PATCH] xen/netfront: fix waiting for xenbus state change

[Juergen Gross <jgross@xxxxxxxx>]

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@xxxxxxxxxxxxxxx> #4.18
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 drivers/net/xen-netfront.c | 24 ++++++++++--------------
 1 file 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) ==
-- 
2.16.4


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