1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 5b15d9d8896b..e1f89416ef8c 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -750,7 +750,7 @@ static int acm_tty_chars_in_buffer(struct tty_struct *tty)
 {
         struct acm *acm = tty->driver_data;
         if (!ACM_READY(acm))
-                return -EINVAL;
+                return 0;
         /*
          * This is inaccurate (overcounts), but it works.
          */