Revert "tty: n_gsm: replace kicktimer with delayed_work"

This reverts commit c9ab053e.

The above commit is reverted as it was a prerequisite for tx_mutex
introduction and tx_mutex has been removed as it does not correctly
work in order to protect tx data.
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Reviewed-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20221008110221.13645-3-pchelkin@ispras.ruSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/n_gsm.c

@@ -272,7 +272,7 @@ struct gsm_mux {
 	struct list_head tx_data_list;	/* Pending data packets */
 
 	/* Control messages */
-	struct delayed_work kick_timeout;	/* Kick TX queuing on timeout */
+	struct timer_list kick_timer;	/* Kick TX queuing on timeout */
 	struct timer_list t2_timer;	/* Retransmit timer for commands */
 	int cretries;			/* Command retry counter */
 	struct gsm_control *pending_cmd;/* Our current pending command */
@@ -1029,7 +1029,7 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
 	gsm->tx_bytes += msg->len;
 
 	gsmld_write_trigger(gsm);
-	schedule_delayed_work(&gsm->kick_timeout, 10 * gsm->t1 * HZ / 100);
+	mod_timer(&gsm->kick_timer, jiffies + 10 * gsm->t1 * HZ / 100);
 }
 
 /**
@@ -2022,16 +2022,16 @@ static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
 }
 
 /**
- *	gsm_kick_timeout	-	transmit if possible
- *	@work: work contained in our gsm object
+ *	gsm_kick_timer	-	transmit if possible
+ *	@t: timer contained in our gsm object
  *
  *	Transmit data from DLCIs if the queue is empty. We can't rely on
  *	a tty wakeup except when we filled the pipe so we need to fire off
  *	new data ourselves in other cases.
  */
-static void gsm_kick_timeout(struct work_struct *work)
+static void gsm_kick_timer(struct timer_list *t)
 {
-	struct gsm_mux *gsm = container_of(work, struct gsm_mux, kick_timeout.work);
+	struct gsm_mux *gsm = from_timer(gsm, t, kick_timer);
 	unsigned long flags;
 	int sent = 0;
 
@@ -2496,7 +2496,7 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
 	}
 
 	/* Finish outstanding timers, making sure they are done */
-	cancel_delayed_work_sync(&gsm->kick_timeout);
+	del_timer_sync(&gsm->kick_timer);
 	del_timer_sync(&gsm->t2_timer);
 
 	/* Finish writing to ldisc */
@@ -2643,7 +2643,7 @@ static struct gsm_mux *gsm_alloc_mux(void)
 	kref_init(&gsm->ref);
 	INIT_LIST_HEAD(&gsm->tx_ctrl_list);
 	INIT_LIST_HEAD(&gsm->tx_data_list);
-	INIT_DELAYED_WORK(&gsm->kick_timeout, gsm_kick_timeout);
+	timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);
 	timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
 	INIT_WORK(&gsm->tx_work, gsmld_write_task);
 	init_waitqueue_head(&gsm->event);