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.

Fixes: 7b2ee50c0cd5 ("hv_netvsc: common detach logic")
Signed-off-by: Haiyang Zhang <haiyangz@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 ae3f308..1b320bc 100644 (file)
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -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;

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 65e12cb..2c0a24c 100644 (file)
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -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");