[PATCH 5.10 381/545] tty: n_gsm: Delete gsmtty open SABM frame when config requester

Greg Kroah-Hartman
2022-08-19T16:37:07Z

From: Zhenguo Zhao <Zhenguo.Zhao1@unisoc.com>

[ Upstream commit cbff2b32516881bef30bbebf413d1b49495bab1d ]

When n_gsm config "initiator=0",as requester ,it doesn't need to
send SABM frame data during gsmtty open.

Example,when gsmtty open,it will send SABM frame.for initiator,it
maybe not want to receive the frame.

[ 88.410426] c1 gsmld_output: 00000000: f9 07 3f 01 de f9
[ 88.420839] c1 --> 1) R: SABM(F)

Signed-off-by: Zhenguo Zhao <Zhenguo.Zhao1@unisoc.com>
Link: https://lore.kernel.org/r/1629461872-26965-6-git-send-email-zhenguo6858@gmail.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, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index b05b7862778c..405b55bceba8 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -3024,6 +3024,7 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp)
{
struct gsm_dlci *dlci = tty->driver_data;
struct tty_port *port = &dlci->port;
+ struct gsm_mux *gsm = dlci->gsm;

port->count++;
tty_port_tty_set(port, tty);
@@ -3033,7 +3034,8 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp)
a DM straight back. This is ok as that will have caused a hangup */
tty_port_set_initialized(port, 1);
/* Start sending off SABM messages */
- gsm_dlci_begin_open(dlci);
+ if (gsm->initiator)
+ gsm_dlci_begin_open(dlci);
/* And wait for virtual carrier */
return tty_port_block_til_ready(port, tty, filp);
}
--
2.35.1