FAILED: patch "[PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-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@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1adf6fee58ca25fb6720b8d34c919dcf5425cc9c Mon Sep 17 00:00:00 2001
From: Daniel Starke <daniel.starke@siemens.com>
Date: Thu, 14 Apr 2022 02:42:19 -0700
Subject: [PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type
 2

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>

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 23418ee93156..f3fb66be8513 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1615,6 +1615,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
 		tty = tty_port_tty_get(port);
 		if (tty) {
 			gsm_process_modem(tty, dlci, modem, slen);
+			tty_wakeup(tty);
 			tty_kref_put(tty);
 		}
 		fallthrough;