2018-09-07 14:12:57

by Jürgen Groß

Subject: [PATCH] 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: <[email protected]> #4.18
Signed-off-by: Juergen Gross <[email protected]>
---
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

2018-09-07 15:45:50

by Boris Ostrovsky

Subject: Re: [PATCH] xen/netfront: fix waiting for xenbus state change

On 09/07/2018 08:21 AM, Juergen Gross wrote:
> 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: <[email protected]> #4.18
> Signed-off-by: Juergen Gross <[email protected]>


Reviewed-by: Boris Ostrovsky <[email protected]>

2018-09-08 06:05:16

by David Miller

Subject: Re: [PATCH] xen/netfront: fix waiting for xenbus state change

From: Juergen Gross <[email protected]>
Date: Fri, 7 Sep 2018 14:21:30 +0200

> 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: <[email protected]> #4.18
> Signed-off-by: Juergen Gross <[email protected]>

Applied.