On 07/27/2018 05:56 AM, Xiao Liang wrote:
> 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.
>
> Current state:
> [vm]# ethtool eth0
> Settings for eth0:
> Link detected: yes
> [vm]# modprobe -r xen_netfront
> [vm]# modprobe xen_netfront
> [vm]# ethtool eth0
> Settings for eth0:
> Cannot get device settings: No such device
> Cannot get wake-on-lan settings: No such device
> Cannot get message level: No such device
> Cannot get link status: No such device
> No data available
>
> With the patch installed.
> [vm]# ethtool eth0
> Settings for eth0:
> Link detected: yes
> [vm]# modprobe -r xen_netfront
> [vm]# modprobe xen_netfront
> [vm]# ethtool eth0
> Settings for eth0:
> Link detected: yes
>
> Signed-off-by: Xiao Liang <xili...@redhat.com>
> ---
> drivers/net/xen-netfront.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index a57daecf1d57..2d8812dd1534 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -87,6 +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);
>
> struct netfront_stats {
> @@ -1330,6 +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);
> return netdev;
>
> exit:
Should we have a wake_up somewhere? And what about other states --- is,
for example, XenbusStateClosing a valid reason to continue?
-boris
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