net/hyperv: Fix the code handling tx busy

Instead of dropping the packet, we keep the skb buffer, and return
NETDEV_TX_BUSY to let upper layer retry send. This will not cause
endless loop, because the host is taking data away from ring buffer,
and we have called the stop_queue before returning NETDEV_TX_BUSY.

The stop_queue was called in the function netvsc_send() in file 
netvsc.c, then it returns to rndis_filter_send(), which returns to
netvsc_start_xmit() in file netvsc_drv.c. So the NETDEV_TX_BUSY is
indeed returned AFTER queue is stopped.

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

1 files changed, 1 insertions, 4 deletions

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 2517d209d602..dd294783b5c5 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -223,13 +223,10 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
                 net->stats.tx_bytes += skb->len;
                 net->stats.tx_packets++;
         } else {
-                /* we are shutting down or bus overloaded, just drop packet */
-                net->stats.tx_dropped++;
                 kfree(packet);
-                dev_kfree_skb_any(skb);
         }
 
-        return NETDEV_TX_OK;
+        return ret ? NETDEV_TX_BUSY : NETDEV_TX_OK;
 }
 
 /*