From: Daniel Starke <daniel.starke@xxxxxxxxxxx> 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@xxxxxxxxxxxxxxx Signed-off-by: Daniel Starke <daniel.starke@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20220414094225.4527-14-daniel.starke@xxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/tty/n_gsm.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1615,6 +1615,7 @@ static void gsm_dlci_data(struct gsm_dlc tty = tty_port_tty_get(port); if (tty) { gsm_process_modem(tty, dlci, modem, slen); + tty_wakeup(tty); tty_kref_put(tty); } fallthrough;