tty: Fix double grabbing of a spinlock

The HSO changes for kref introduced a recursive spinlock take. All
functions which call put_rxbuf_data already have serial->serial_lock
grabbed.

[Comment to code added-AC]

Signed-off-by: Denis Joseph Barrow <D.Barrow@option.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 9df04dd1332c..e25a58f6ff69 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2044,9 +2044,8 @@ static int put_rxbuf_data(struct urb *urb, struct hso_serial *serial)
                 return -2;
         }
 
-        spin_lock(&serial->serial_lock);
+        /* All callers to put_rxbuf_data hold serial_lock */
         tty = tty_kref_get(serial->tty);
-        spin_unlock(&serial->serial_lock);
 
         /* Push data to tty */
         if (tty) {