tty: n_gsm: fix missing tty wakeup in convergence layer type 2

commit 1adf6fee58ca25fb6720b8d34c919dcf5425cc9c upstream.

gsm_control_modem() informs the virtual tty that more data can be written
after receiving a control signal octet via modem status command (MSC).
However, gsm_dlci_data() fails to do the same after receiving a control
signal octet from the convergence layer type 2 header.
Add tty_wakeup() in gsm_dlci_data() for convergence layer type 2 to fix
this.

Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220414094225.4527-14-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 07f8aaf..0985009 100644 (file)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1586,6 +1586,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
                tty = tty_port_tty_get(port);
                if (tty) {
                        gsm_process_modem(tty, dlci, modem, slen);
+                       tty_wakeup(tty);
                        tty_kref_put(tty);
                }
                fallthrough;