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Subject[PATCH 4.18 101/235] xen/netfront: fix waiting for xenbus state change
Date
4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Juergen Gross <jgross@suse.com>

commit 8edfe2e992b75aee3da9316e9697c531194c2f53 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/xen-netfront.c | 24 ++++++++++--------------
1 file changed, 10 insertions(+), 14 deletions(-)

--- 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;
@@ -1331,11 +1330,11 @@ static struct net_device *xennet_create_
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:
@@ -2009,15 +2008,14 @@ static void netback_changed(struct xenbu

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:
@@ -2033,12 +2031,10 @@ static void netback_changed(struct xenbu
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;
}
@@ -2146,14 +2142,14 @@ static int xennet_remove(struct xenbus_d

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) ==

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