Drivers: hv: vmbus: Fix a rescind handling bug

The host can rescind a channel that has been offered to the
guest and once the channel is rescinded, the host does not
respond to any requests on that channel. Deal with the case where
the guest may be blocked waiting for a response from the host.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 42fe43f..7ea20bd 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -627,6 +627,7 @@
 
 	/* Synchronize the request/response if needed */
 	struct completion  waitevent;
+	struct vmbus_channel *waiting_channel;
 	union {
 		struct vmbus_channel_version_supported version_supported;
 		struct vmbus_channel_open_result open_result;