1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index 1ab9517c24c5..585fac179ec6 100644
--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -1280,6 +1280,7 @@ static int moxa_chars_in_buffer(struct tty_struct *tty)
          */
         if (ch == NULL)
                 return 0;
+        lock_kernel();
         chars = MoxaPortTxQueue(ch);
         if (chars) {
                 /*
@@ -1289,6 +1290,7 @@ static int moxa_chars_in_buffer(struct tty_struct *tty)
                 if (!(ch->statusflags & EMPTYWAIT))
                         moxa_setup_empty_event(tty);
         }
+        unlock_kernel();
         return chars;
 }