Introduce code to properly manage outstanding sends.

Signed-off-by: K. Y. Srinivasan <[email protected]>
Signed-off-by: Haiyang Zhang <[email protected]>
Signed-off-by: Abhishek Kane <[email protected]>
Signed-off-by: Hank Janssen <[email protected]>
---
 drivers/staging/hv/hyperv_net.h |   10 ++++++++++
 drivers/staging/hv/netvsc.c     |    6 +++++-
 2 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/drivers/staging/hv/hyperv_net.h b/drivers/staging/hv/hyperv_net.h
index 5782fea..b5bee9e 100644
--- a/drivers/staging/hv/hyperv_net.h
+++ b/drivers/staging/hv/hyperv_net.h
@@ -371,6 +371,8 @@ struct netvsc_device {
 
        atomic_t refcnt;
        atomic_t num_outstanding_sends;
+       bool drain_notify;
+       wait_queue_head_t waiting_to_drain;
        /*
         * List of free preallocated hv_netvsc_packet to represent receive
         * packet
@@ -1051,6 +1053,14 @@ struct rndis_filter_packet {
 #define NDIS_PACKET_TYPE_FUNCTIONAL    0x00000400
 #define NDIS_PACKET_TYPE_MAC_FRAME     0x00000800
 
+static inline void netvsc_wait_to_drain(struct netvsc_device *dev)
+{
+       dev->drain_notify = true;
+       wait_event(dev->waiting_to_drain,
+               atomic_read(&dev->num_outstanding_sends) == 0);
+       dev->drain_notify = false;
+}
+
 
 
 #endif /* _HYPERV_NET_H */
diff --git a/drivers/staging/hv/netvsc.c b/drivers/staging/hv/netvsc.c
index 551537a..bdd5c2b 100644
--- a/drivers/staging/hv/netvsc.c
+++ b/drivers/staging/hv/netvsc.c
@@ -42,6 +42,8 @@ static struct netvsc_device *alloc_net_device(struct 
hv_device *device)
 
        /* Set to 2 to allow both inbound and outbound traffic */
        atomic_cmpxchg(&net_device->refcnt, 0, 2);
+       net_device->drain_notify = false;
+       init_waitqueue_head(&net_device->waiting_to_drain);
 
        net_device->dev = device;
        device->ext = net_device;
@@ -483,7 +485,9 @@ static void netvsc_send_completion(struct hv_device *device,
                nvsc_packet->completion.send.send_completion(
                        nvsc_packet->completion.send.send_completion_ctx);
 
-               atomic_dec(&net_device->num_outstanding_sends);
+               if (atomic_dec_and_test(&net_device->num_outstanding_sends) &&
+                       net_device->drain_notify)
+                       wake_up(&net_device->waiting_to_drain);
        } else {
                netdev_err(ndev, "Unknown send completion packet type- "
                           "%d received!!\n", nvsp_packet->hdr.msg_type);
-- 
1.7.4.1

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