Drivers: hv: vmbus: Permit sending of packets without payload

The guest may have to send a completion packet back to the host.
To support this usage, permit sending a packet without a payload -
we would be only sending the descriptor in this case.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 603ce97e9027283044b5da16ed15436a7ddcd3af..c4dcab048cb8ecbc38b7784408bfd7902d5a40a7 100644 (file)
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -601,6 +601,7 @@ int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer,
        u64 aligned_data = 0;
        int ret;
        bool signal = false;
+       int num_vecs = ((bufferlen != 0) ? 3 : 1);
 
 
        /* Setup the descriptor */
@@ -618,7 +619,8 @@ int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer,
        bufferlist[2].iov_base = &aligned_data;
        bufferlist[2].iov_len = (packetlen_aligned - packetlen);
 
-       ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+       ret = hv_ringbuffer_write(&channel->outbound, bufferlist, num_vecs,
+                                 &signal);
 
        /*
         * Signalling the host is conditional on many factors: