linux-kernel - [PATCH v4 7/9] tty: n_gsm: fix packet re-transmission without open control channel

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Message-Id: <20220701061652.39604-7-daniel.starke@siemens.com>
Date:   Fri,  1 Jul 2022 08:16:50 +0200
From:   "D. Starke" <daniel.starke@...mens.com>
To:     linux-serial@...r.kernel.org, gregkh@...uxfoundation.org,
        jirislaby@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Daniel Starke <daniel.starke@...mens.com>
Subject: [PATCH v4 7/9] tty: n_gsm: fix packet re-transmission without open control channel

From: Daniel Starke <daniel.starke@...mens.com>

In the current implementation control packets are re-transmitted even if
the control channel closed down during T2. This is wrong.
Check whether the control channel is open before re-transmitting any
packets. Note that control channel open/close is handled by T1 and not T2
and remains unaffected by this.

Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Signed-off-by: Daniel Starke <daniel.starke@...mens.com>
---
 drivers/tty/n_gsm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Stable backport remark has been removed compared to v3. No other changes applied.

Link: https://lore.kernel.org/all/20220530144512.2731-7-daniel.starke@siemens.com/

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index b82efb63f4e6..9e4ada510c9f 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1624,7 +1624,7 @@ static void gsm_control_retransmit(struct timer_list *t)
 	spin_lock_irqsave(&gsm->control_lock, flags);
 	ctrl = gsm->pending_cmd;
 	if (ctrl) {
-		if (gsm->cretries == 0) {
+		if (gsm->cretries == 0 || !gsm->dlci[0] || gsm->dlci[0]->dead) {
 			gsm->pending_cmd = NULL;
 			ctrl->error = -ETIMEDOUT;
 			ctrl->done = 1;
-- 
2.34.1