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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, Daniel Starke <daniel.starke@siemens.com>
Subject: [PATCH 5.15 169/177] tty: n_gsm: fix missing tty wakeup in convergence layer type 2
Date:   Wed,  4 May 2022 18:46:02 +0200
Message-Id: <20220504153108.699326364@linuxfoundation.org>
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From: Daniel Starke <daniel.starke@siemens.com>

commit 1adf6fee58ca25fb6720b8d34c919dcf5425cc9c upstream.

gsm_control_modem() informs the virtual tty that more data can be written
after receiving a control signal octet via modem status command (MSC).
However, gsm_dlci_data() fails to do the same after receiving a control
signal octet from the convergence layer type 2 header.
Add tty_wakeup() in gsm_dlci_data() for convergence layer type 2 to fix
this.

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/20220414094225.4527-14-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/n_gsm.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1586,6 +1586,7 @@ static void gsm_dlci_data(struct gsm_dlc
 		tty = tty_port_tty_get(port);
 		if (tty) {
 			gsm_process_modem(tty, dlci, modem, slen);
+			tty_wakeup(tty);
 			tty_kref_put(tty);
 		}
 		fallthrough;