Bluetooth: Fix H4 crash from incoming UART packets

This patch adds a check HCI_UART_REGISTERED before reading UART data in
the HCI UART H4 driver. UART data could arrive when inside the
hci_uart_tty_ioctl function after calling test_and_set_bit for
HCI_UART_PROTO_SET but before the hci_uart_set_proto function has
returned.

Backtrace:
[<c05f27ec>] (hci_recv_stream_fragment+0x0/0x74) from [<c04126f4>] (h4_recv+0x18/0x40)
 r7:eb1d4d1c r6:eb7683b0 r5:eae8e800 r4:0000000c
[<c04126dc>] (h4_recv+0x0/0x40) from [<c0411870>] (hci_uart_tty_receive+0x6c/0x94)
 r5:eae8e800 r4:eb768380
[<c0411804>] (hci_uart_tty_receive+0x0/0x94) from [<c027be88>] (flush_to_ldisc+0x16c/0x17c)
 r6:eae8e8d8 r5:eae8e800 r4:eae8e8c8
[<c027bd1c>] (flush_to_ldisc+0x0/0x17c) from [<c0050ae8>] (process_one_work+0x144/0x4d4)
[<c00509a4>] (process_one_work+0x0/0x4d4) from [<c0051208>] (worker_thread+0x180/0x370)
[<c0051088>] (worker_thread+0x0/0x370) from [<c005617c>] (kthread+0x90/0x9c)
[<c00560ec>] (kthread+0x0/0x9c) from [<c003a3a0>] (do_exit+0x0/0x7ec)

Signed-off-by: Chan-yeol Park <chanyeol.park@samsung.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
 Bluetooth: hci_uart: check the return value of recv()

Check the return value of hu->proto->recv() in hci_uart_tty_receive()
the recv() may return error, check it, not add this to statistics.

Signed-off-by: Jiejing Zhang <jiejing.zhang@freescale.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
 Bluetooth: uart-ldisc: Fix memory leak and remove destruct cb

We currently leak the hci_uart object if HCI_UART_PROTO_SET is never set
because the hci-destruct callback will then never be called.  This fix
removes the hci-destruct callback and frees the driver internal private
hci_uart object directly on tty-close. We call hci_unregister_dev() here
so the hci-core will never call our callbacks again (except destruct).
Therefore, we can safely free the driver internal data right away and
set the destruct callback to NULL.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>