Drivers: hv: vmbus: Reduce the delay between retries in vmbus_post_msg()

BugLink: http://bugs.launchpad.net/bugs/1650059

The current delay between retries is unnecessarily high and is negatively
affecting the time it takes to boot the system.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 8de0d7e9)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/hv/connection.c

@@ -439,7 +439,7 @@ int vmbus_post_msg(void *buffer, size_t buflen)
 	union hv_connection_id conn_id;
 	int ret = 0;
 	int retries = 0;
-	u32 msec = 1;
+	u32 usec = 1;
 
 	conn_id.asu32 = 0;
 	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
@@ -472,9 +472,9 @@ int vmbus_post_msg(void *buffer, size_t buflen)
 		}
 
 		retries++;
-		msleep(msec);
-		if (msec < 2048)
-			msec *= 2;
+		udelay(usec);
+		if (usec < 2048)
+			usec *= 2;
 	}
 	return ret;
 }