The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 48473802506d2d6151f59e0e764932b33b53cb3b Mon Sep 17 00:00:00 2001
From: Daniel Starke <daniel.starke@xxxxxxxxxxx>
Date: Wed, 20 Apr 2022 03:13:44 -0700
Subject: [PATCH] tty: n_gsm: fix missing update of modem controls after DLCI
open
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@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Starke <daniel.starke@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220420101346.3315-1-daniel.starke@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index e440c7f6d20e..979dc9151383 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -370,6 +370,7 @@ 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
@@ -1483,6 +1484,9 @@ static void gsm_dlci_open(struct gsm_dlci *dlci)
pr_debug("DLCI %d goes open.\n", dlci->addr);
/* Register gsmtty driver,report gsmtty dev add uevent for user */
tty_register_device(gsm_tty_driver, dlci->addr, NULL);
+ /* Send current modem state */
+ if (dlci->addr)
+ gsmtty_modem_update(dlci, 0);
wake_up(&dlci->gsm->event);
}
