hso: fix soft-lockup

Fix soft-lockup in hso.c which is triggered on SMP machine when
modem is removed while file descriptor(s) under /dev are still open:

  old version called kref_put() too early which resulted in destroying
  hso_serial and hso_device objects which were still used later on.

Signed-off-by: Antti Kaijanmäki <antti.kaijanmaki@nomovok.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 746839bb89ff..43bc3fcc0d85 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -1363,7 +1363,7 @@ static void hso_serial_close(struct tty_struct *tty, struct file *filp)
         /* reset the rts and dtr */
         /* do the actual close */
         serial->open_count--;
-        kref_put(&serial->parent->ref, hso_serial_ref_free);
+
         if (serial->open_count <= 0) {
                 serial->open_count = 0;
                 spin_lock_irq(&serial->serial_lock);
@@ -1383,6 +1383,8 @@ static void hso_serial_close(struct tty_struct *tty, struct file *filp)
                 usb_autopm_put_interface(serial->parent->interface);
 
         mutex_unlock(&serial->parent->mutex);
+
+        kref_put(&serial->parent->ref, hso_serial_ref_free);
 }
 
 /* close the requested serial port */