[PATCH v2] hv_sock: Add the support of hibernation

[Dexuan Cui <decui@microsoft.com>]

Add the necessary dummy callbacks for hibernation.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Acked-by: David S. Miller <davem@davemloft.net>
---

In v2:
    Added David's Acked-by.
    Removed [net-next] from the Subject.

    @Sasha, can you please pick this up into the hyper-v tree?

 net/vmw_vsock/hyperv_transport.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
index f2084e3f7aa4..4c02e38aa728 100644
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -930,6 +930,24 @@ static int hvs_remove(struct hv_device *hdev)
 	return 0;
 }
 
+/* hv_sock connections can not persist across hibernation, and all the hv_sock
+ * channels are forced to be rescinded before hibernation: see
+ * vmbus_bus_suspend(). Here the dummy hvs_suspend() and hvs_resume()
+ * are only needed because hibernation requires that every vmbus device's
+ * driver should have a .suspend and .resume callback: see vmbus_suspend().
+ */
+static int hvs_suspend(struct hv_device *hv_dev)
+{
+	/* Dummy */
+	return 0;
+}
+
+static int hvs_resume(struct hv_device *dev)
+{
+	/* Dummy */
+	return 0;
+}
+
 /* This isn't really used. See vmbus_match() and vmbus_probe() */
 static const struct hv_vmbus_device_id id_table[] = {
 	{},
@@ -941,6 +959,8 @@ static struct hv_driver hvs_drv = {
 	.id_table	= id_table,
 	.probe		= hvs_probe,
 	.remove		= hvs_remove,
+	.suspend	= hvs_suspend,
+	.resume		= hvs_resume,
 };
 
 static int __init hvs_init(void)
-- 
2.19.1