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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Zhenguo Zhao <Zhenguo.Zhao1@unisoc.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 582/779] tty: n_gsm: Delete gsmtty open SABM frame when config requester
Date:   Mon, 15 Aug 2022 20:03:46 +0200
Message-Id: <20220815180402.212451203@linuxfoundation.org>
In-Reply-To: <20220815180337.130757997@linuxfoundation.org>
References: <20220815180337.130757997@linuxfoundation.org>
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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 4946a241e323..f86c5ebfcf91 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -3214,6 +3214,7 @@ 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);
@@ -3223,7 +3224,8 @@ 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