From: Daniel Starke daniel.starke@siemens.com
[ Upstream commit 48473802506d2d6151f59e0e764932b33b53cb3b ]
Currently the peer is not informed about the initial state of the modem control lines after a new DLCI has been opened. Fix this by sending the initial modem control line states after DLCI open.
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/20220420101346.3315-1-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/n_gsm.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index d3d5308daf35..c52d5e0d5c6f 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -371,6 +371,7 @@ static const u8 gsm_fcs8[256] = { #define GOOD_FCS 0xCF
static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len); +static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk);
/** * gsm_fcs_add - update FCS @@ -1489,6 +1490,9 @@ static void gsm_dlci_open(struct gsm_dlci *dlci) dlci->state = DLCI_OPEN; if (debug & 8) pr_debug("DLCI %d goes open.\n", dlci->addr); + /* Send current modem state */ + if (dlci->addr) + gsmtty_modem_update(dlci, 0); wake_up(&dlci->gsm->event); }