hv_netvsc: use RCU to fix concurrent rx and queue changes

The receive processing may continue to happen while the
internal network device state is in RCU grace period.
The internal RNDIS structure is associated with the
internal netvsc_device structure; both have the same
RCU lifetime.

Defer freeing all associated parts until after grace
period.

Fixes: 0cf737808ae7 ("hv_netvsc: netvsc_teardown_gpadl() split")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index e70a442..12c044b 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -90,6 +90,11 @@ static void free_netvsc_device(struct rcu_head *head)
 		= container_of(head, struct netvsc_device, rcu);
 	int i;
 
+	kfree(nvdev->extension);
+	vfree(nvdev->recv_buf);
+	vfree(nvdev->send_buf);
+	kfree(nvdev->send_section_map);
+
 	for (i = 0; i < VRSS_CHANNEL_MAX; i++)
 		vfree(nvdev->chan_table[i].mrc.slots);
 
@@ -211,12 +216,6 @@ static void netvsc_teardown_gpadl(struct hv_device *device,
 		net_device->recv_buf_gpadl_handle = 0;
 	}
 
-	if (net_device->recv_buf) {
-		/* Free up the receive buffer */
-		vfree(net_device->recv_buf);
-		net_device->recv_buf = NULL;
-	}
-
 	if (net_device->send_buf_gpadl_handle) {
 		ret = vmbus_teardown_gpadl(device->channel,
 					   net_device->send_buf_gpadl_handle);
@@ -231,12 +230,6 @@ static void netvsc_teardown_gpadl(struct hv_device *device,
 		}
 		net_device->send_buf_gpadl_handle = 0;
 	}
-	if (net_device->send_buf) {
-		/* Free up the send buffer */
-		vfree(net_device->send_buf);
-		net_device->send_buf = NULL;
-	}
-	kfree(net_device->send_section_map);
 }
 
 int netvsc_alloc_recv_comp_ring(struct netvsc_device *net_device, u32 q_idx)