FAILED: patch "[PATCH] hv_netvsc: Fix unwanted wakeup in netvsc_attach()" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f6f13c125e05603f68f5bf31f045b95e6d493598 Mon Sep 17 00:00:00 2001
From: Haiyang Zhang <[email protected]>
Date: Fri, 21 Feb 2020 08:32:18 -0800
Subject: [PATCH] hv_netvsc: Fix unwanted wakeup in netvsc_attach()

When netvsc_attach() is called by operations like changing MTU, etc., an extra wakeup may happen while netvsc_attach() calling rndis_filter_device_add() which sends rndis messages when queue is stopped in netvsc_detach(). The completion message will wake up queue 0.

We can reproduce the issue by changing MTU etc., then the wake_queue counter from "ethtool -S" will increase beyond stop_queue counter:
stop_queue: 0
wake_queue: 1
The issue causes queue wake up, and counter increment, no other ill effects in current code. So we didn't see any network problem for now.

To fix this, initialize tx_disable to true, and set it to false when the NIC is ready to be attached or registered.

index ae3f3084c2ed..1b320bcf150a 100644
@@ -99,7 +99,7 @@ static struct netvsc_device *alloc_net_device(void)
 
 	init_waitqueue_head(&net_device->wait_drain);
 	net_device->destroy = false;
-	net_device->tx_disable = false;
+	net_device->tx_disable = true;
 
 	net_device->max_pkt = RNDIS_MAX_PKT_DEFAULT;
 	net_device->pkt_align = RNDIS_PKT_ALIGN_DEFAULT;

index 65e12cb07f45..2c0a24c606fc 100644
@@ -1068,6 +1068,7 @@ static int netvsc_attach(struct net_device *ndev,
 	}
 
 	/* In any case device is now ready */
+	nvdev->tx_disable = false;
 	netif_device_attach(ndev);
 
 	/* Note: enable and attach happen when sub-channels setup */

@@ -2476,6 +2477,8 @@ static int netvsc_probe(struct hv_device *dev,
 	else
 		net->max_mtu = ETH_DATA_LEN;
 
+	nvdev->tx_disable = false;
+
 	ret = register_netdevice(net);
 	if (ret != 0) {
 		pr_err("Unable to register netdev.\n");