[PATCH] netvsc: make sure napi enabled before vmbus_open

[Stephen Hemminger]

This fixes a race where vmbus callback for new packet arriving
could occur before NAPI is initialized. Happens more on WS2008
which takes longer to setup channel.

Signed-off-by: Stephen Hemminger <sthem...@microsoft.com>
---
 drivers/net/hyperv/netvsc.c       | 8 +++++---
 drivers/net/hyperv/rndis_filter.c | 4 +++-
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index f99651c03e0a..8150febb86d6 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1323,6 +1323,10 @@ int netvsc_device_add(struct hv_device *device,
                nvchan->channel = device->channel;
        }
 
+       /* Enable NAPI handler before init callbacks */
+       netif_napi_add(ndev, &net_device->chan_table[0].napi,
+                      netvsc_poll, NAPI_POLL_WEIGHT);
+
        /* Open the channel */
        ret = vmbus_open(device->channel, ring_size * PAGE_SIZE,
                         ring_size * PAGE_SIZE, NULL, 0,
@@ -1330,6 +1334,7 @@ int netvsc_device_add(struct hv_device *device,
                         net_device->chan_table);
 
        if (ret != 0) {
+               netif_napi_del(&net_device->chan_table[0].napi);
                netdev_err(ndev, "unable to open channel: %d\n", ret);
                goto cleanup;
        }
@@ -1337,9 +1342,6 @@ int netvsc_device_add(struct hv_device *device,
        /* Channel is opened */
        netdev_dbg(ndev, "hv_netvsc channel opened successfully\n");
 
-       /* Enable NAPI handler for init callbacks */
-       netif_napi_add(ndev, &net_device->chan_table[0].napi,
-                      netvsc_poll, NAPI_POLL_WEIGHT);
        napi_enable(&net_device->chan_table[0].napi);
 
        /* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is
diff --git a/drivers/net/hyperv/rndis_filter.c 
b/drivers/net/hyperv/rndis_filter.c
index ab92c3c95951..a9e9fb4bb9c5 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1017,8 +1017,10 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
                         netvsc_channel_cb, nvchan);
        if (ret == 0)
                napi_enable(&nvchan->napi);
-       else
+       else {
+               netif_napi_del(&nvchan->napi);
                netdev_err(ndev, "sub channel open failed (%d)\n", ret);
+       }
 
        if (refcount_dec_and_test(&nvscdev->sc_offered))
                complete(&nvscdev->channel_init_wait);
-- 
2.11.0