On 09/06/2018 08:21 PM, Ben Hutchings wrote:
On Sat, 2018-08-04 at 11:01 +0200, Greg Kroah-Hartman wrote:
4.4-stable review patch. If anyone has any objections, please let me know.
From: Xiao Liang xiliang@redhat.com
[ Upstream commit 822fb18a82abaf4ee7058793d95d340f5dab7bfc ]
When loading module manually, after call xenbus_switch_state to initializes the state of the netfront device, the driver state did not change so fast that may lead no dev created in latest kernel. This patch adds wait to make sure xenbus knows the driver is not in closed/unknown state.
[...]
--- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -86,6 +86,7 @@ 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); struct netfront_stats { @@ -1335,6 +1336,11 @@ 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);return netdev; exit:
This won't work; it will hang. Something (maybe netback_changed()?) needs to wake up tasks on the module_load_q.
https://lkml.org/lkml/2018/9/7/691
-boris