Hello,

Thank you very much for your time and pointing out problems in my patch.
I have sent the modified patch again just now.

We use pty to simulate 6pack device, the released resource is tty_struct->tty_port
in tty layer. 

The free trace is shown as below:
tty_release()->tty_release_struct()->release_tty()->tty_kref_put()->
queue_release_one_tty()->release_one_tty()->pty_cleanup()->tty_port_put(tty->port);

The use trace is shown as below:
sp_xmit_on_air()->pty_write()->tty_flip_buffer_push()->tty_schedule_flip(port);


Best wishes,
Duoming Zhou