hso: fix soft-lockup

commit dcfcb256cc23c4436691b0fe677275306699d6a1 upstream.

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>

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index f8c6d7ea72646ceb24fe1ccf480f80fffb5c7767..9e1fc2968cf15ead62d965391a70c80fd1eda2b2 100644 (file)
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -1362,7 +1362,7 @@ 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);
@@ -1382,6 +1382,8 @@ 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 */