hv_netvsc: Add close of RNDIS filter into change mtu call

The current change mtu call only stops tx before removing RNDIS filter.
In case ringbufer is not empty, the rndis_filter_device_remove() may
hang on removing the buffers.

This patch adds close of RNDIS filter before removing it, also a
gradual waiting loop until the ring is empty. The change_mtu hang
issue under heavy traffic is solved by this patch.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index b855ba9a507d5b0eeda334b0eb3e254ee5ba26f8..7b36d5fecc1f24b95c87477ebd43a06ec5a4f914 100644 (file)
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -106,7 +106,7 @@ static int netvsc_open(struct net_device *net)
                return ret;
        }
 
-       netif_tx_start_all_queues(net);
+       netif_tx_wake_all_queues(net);
 
        nvdev = hv_get_drvdata(device_obj);
        rdev = nvdev->extension;
@@ -120,15 +120,56 @@ static int netvsc_close(struct net_device *net)
 {
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_device *device_obj = net_device_ctx->device_ctx;
+       struct netvsc_device *nvdev = hv_get_drvdata(device_obj);
        int ret;
+       u32 aread, awrite, i, msec = 10, retry = 0, retry_max = 20;
+       struct vmbus_channel *chn;
 
        netif_tx_disable(net);
 
        /* Make sure netvsc_set_multicast_list doesn't re-enable filter! */
        cancel_work_sync(&net_device_ctx->work);
        ret = rndis_filter_close(device_obj);
-       if (ret != 0)
+       if (ret != 0) {
                netdev_err(net, "unable to close device (ret %d).\n", ret);
+               return ret;
+       }
+
+       /* Ensure pending bytes in ring are read */
+       while (true) {
+               aread = 0;
+               for (i = 0; i < nvdev->num_chn; i++) {
+                       chn = nvdev->chn_table[i];
+                       if (!chn)
+                               continue;
+
+                       hv_get_ringbuffer_availbytes(&chn->inbound, &aread,
+                                                    &awrite);
+
+                       if (aread)
+                               break;
+
+                       hv_get_ringbuffer_availbytes(&chn->outbound, &aread,
+                                                    &awrite);
+
+                       if (aread)
+                               break;
+               }
+
+               retry++;
+               if (retry > retry_max || aread == 0)
+                       break;
+
+               msleep(msec);
+
+               if (msec < 1000)
+                       msec *= 2;
+       }
+
+       if (aread) {
+               netdev_err(net, "Ring buffer not empty after closing rndis\n");
+               ret = -ETIMEDOUT;
+       }
 
        return ret;
 }
@@ -736,6 +777,7 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
        struct netvsc_device *nvdev = hv_get_drvdata(hdev);
        struct netvsc_device_info device_info;
        int limit = ETH_DATA_LEN;
+       int ret = 0;
 
        if (nvdev == NULL || nvdev->destroy)
                return -ENODEV;
@@ -746,9 +788,11 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
        if (mtu < NETVSC_MTU_MIN || mtu > limit)
                return -EINVAL;
 
+       ret = netvsc_close(ndev);
+       if (ret)
+               goto out;
+
        nvdev->start_remove = true;
-       cancel_work_sync(&ndevctx->work);
-       netif_tx_disable(ndev);
        rndis_filter_device_remove(hdev);
 
        ndev->mtu = mtu;
@@ -758,9 +802,11 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
        device_info.ring_size = ring_size;
        device_info.max_num_vrss_chns = max_num_vrss_chns;
        rndis_filter_device_add(hdev, &device_info);
-       netif_tx_wake_all_queues(ndev);
 
-       return 0;
+out:
+       netvsc_open(ndev);
+
+       return ret;
 }
 
 static struct rtnl_link_stats64 *netvsc_get_stats64(struct net_device *net,