Merge tag 'tty-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial updates from Greg KH:
 "Here is the big set of tty/serial driver changes for 6.19-rc1. Nothing
  major at all, just small constant churn to make the tty layer
  "cleaner" as well as serial driver updates and even a new test added!
  Included in here are:

   - More tty/serial cleanups from Jiri

   - tty tiocsti test added to hopefully ensure we don't regress in this
     area again

   - sc16is7xx driver updates

   - imx serial driver updates

   - 8250 driver updates

   - new hardware device ids added

   - other minor serial/tty driver cleanups and tweaks

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (60 commits)
  serial: sh-sci: Fix deadlock during RSCI FIFO overrun error
  dt-bindings: serial: rsci: Drop "uart-has-rtscts: false"
  LoongArch: dts: Add uart new compatible string
  serial: 8250: Add Loongson uart driver support
  dt-bindings: serial: 8250: Add Loongson uart compatible
  serial: 8250: add driver for KEBA UART
  serial: Keep rs485 settings for devices without firmware node
  serial: qcom-geni: Enable Serial on SA8255p Qualcomm platforms
  serial: qcom-geni: Enable PM runtime for serial driver
  serial: sprd: Return -EPROBE_DEFER when uart clock is not ready
  tty: serial: samsung: Declare earlycon for Exynos850
  serial: icom: Convert PCIBIOS_* return codes to errnos
  serial: 8250-of: Fix style issues in 8250_of.c
  serial: add support of CPCI cards
  serial: mux: Fix kernel doc for mux_poll()
  tty: replace use of system_unbound_wq with system_dfl_wq
  serial: 8250_platform: simplify IRQF_SHARED handling
  serial: 8250: make share_irqs local to 8250_platform
  serial: 8250: move skip_txen_test to core
  serial: drop SERIAL_8250_DEPRECATED_OPTIONS
  ...

41 files changed, 1659 insertions, 1134 deletions

diff --git a/drivers/tty/moxa.c b/drivers/tty/moxa.c
index 329b30fac8fc..1bb2376af85c 100644
--- a/drivers/tty/moxa.c
+++ b/drivers/tty/moxa.c
@@ -487,25 +487,20 @@ static void moxa_wait_finish(void __iomem *ofsAddr)
 
 static void moxafunc(void __iomem *ofsAddr, u16 cmd, u16 arg)
 {
-        unsigned long flags;
-        spin_lock_irqsave(&moxafunc_lock, flags);
+	guard(spinlock_irqsave)(&moxafunc_lock);
 	writew(arg, ofsAddr + FuncArg);
 	writew(cmd, ofsAddr + FuncCode);
 	moxa_wait_finish(ofsAddr);
-	spin_unlock_irqrestore(&moxafunc_lock, flags);
 }
 
 static int moxafuncret(void __iomem *ofsAddr, u16 cmd, u16 arg)
 {
-        unsigned long flags;
-        u16 ret;
-        spin_lock_irqsave(&moxafunc_lock, flags);
+	guard(spinlock_irqsave)(&moxafunc_lock);
 	writew(arg, ofsAddr + FuncArg);
 	writew(cmd, ofsAddr + FuncCode);
 	moxa_wait_finish(ofsAddr);
-	ret = readw(ofsAddr + FuncArg);
-	spin_unlock_irqrestore(&moxafunc_lock, flags);
-	return ret;
+
+	return readw(ofsAddr + FuncArg);
 }
 
 static void moxa_low_water_check(void __iomem *ofsAddr)
@@ -1002,11 +997,11 @@ static int moxa_init_board(struct moxa_board_conf *brd, struct device *dev)
 	if (ret)
 		goto err_free;
 
-	spin_lock_bh(&moxa_lock);
-	brd->ready = 1;
-	if (!timer_pending(&moxaTimer))
-		mod_timer(&moxaTimer, jiffies + HZ / 50);
-	spin_unlock_bh(&moxa_lock);
+	scoped_guard(spinlock_bh, &moxa_lock) {
+		brd->ready = 1;
+		if (!timer_pending(&moxaTimer))
+			mod_timer(&moxaTimer, jiffies + HZ / 50);
+	}
 
 	first_idx = (brd - moxa_boards) * MAX_PORTS_PER_BOARD;
 	for (i = 0; i < brd->numPorts; i++)
@@ -1026,29 +1021,29 @@ static void moxa_board_deinit(struct moxa_board_conf *brd)
 {
 	unsigned int a, opened, first_idx;
 
-	mutex_lock(&moxa_openlock);
-	spin_lock_bh(&moxa_lock);
-	brd->ready = 0;
-	spin_unlock_bh(&moxa_lock);
-
-	/* pci hot-un-plug support */
-	for (a = 0; a < brd->numPorts; a++)
-		if (tty_port_initialized(&brd->ports[a].port))
-			tty_port_tty_hangup(&brd->ports[a].port, false);
-
-	for (a = 0; a < MAX_PORTS_PER_BOARD; a++)
-		tty_port_destroy(&brd->ports[a].port);
+	scoped_guard(mutex, &moxa_openlock) {
+		scoped_guard(spinlock_bh, &moxa_lock)
+			brd->ready = 0;
 
-	while (1) {
-		opened = 0;
+		/* pci hot-un-plug support */
 		for (a = 0; a < brd->numPorts; a++)
 			if (tty_port_initialized(&brd->ports[a].port))
-				opened++;
-		mutex_unlock(&moxa_openlock);
-		if (!opened)
-			break;
-		msleep(50);
-		mutex_lock(&moxa_openlock);
+				tty_port_tty_hangup(&brd->ports[a].port, false);
+
+		for (a = 0; a < MAX_PORTS_PER_BOARD; a++)
+			tty_port_destroy(&brd->ports[a].port);
+
+		while (1) {
+			opened = 0;
+			for (a = 0; a < brd->numPorts; a++)
+				if (tty_port_initialized(&brd->ports[a].port))
+					opened++;
+			if (!opened)
+				break;
+			mutex_unlock(&moxa_openlock);
+			msleep(50);
+			mutex_lock(&moxa_openlock);
+		}
 	}
 
 	first_idx = (brd - moxa_boards) * MAX_PORTS_PER_BOARD;
@@ -1206,12 +1201,9 @@ static void moxa_shutdown(struct tty_port *port)
 static bool moxa_carrier_raised(struct tty_port *port)
 {
 	struct moxa_port *ch = container_of(port, struct moxa_port, port);
-	int dcd;
 
-	spin_lock_irq(&port->lock);
-	dcd = ch->DCDState;
-	spin_unlock_irq(&port->lock);
-	return dcd;
+	guard(spinlock_irq)(&port->lock);
+	return ch->DCDState;
 }
 
 static void moxa_dtr_rts(struct tty_port *port, bool active)
@@ -1225,37 +1217,31 @@ static int moxa_open(struct tty_struct *tty, struct file *filp)
 {
 	struct moxa_board_conf *brd;
 	struct moxa_port *ch;
-	int port;
-
-	port = tty->index;
-	if (mutex_lock_interruptible(&moxa_openlock))
-		return -ERESTARTSYS;
-	brd = &moxa_boards[port / MAX_PORTS_PER_BOARD];
-	if (!brd->ready) {
-		mutex_unlock(&moxa_openlock);
-		return -ENODEV;
-	}
+	int port = tty->index;
 
-	if (port % MAX_PORTS_PER_BOARD >= brd->numPorts) {
-		mutex_unlock(&moxa_openlock);
-		return -ENODEV;
-	}
-
-	ch = &brd->ports[port % MAX_PORTS_PER_BOARD];
-	ch->port.count++;
-	tty->driver_data = ch;
-	tty_port_tty_set(&ch->port, tty);
-	mutex_lock(&ch->port.mutex);
-	if (!tty_port_initialized(&ch->port)) {
-		ch->statusflags = 0;
-		moxa_set_tty_param(tty, &tty->termios);
-		MoxaPortLineCtrl(ch, true, true);
-		MoxaPortEnable(ch);
-		MoxaSetFifo(ch, ch->type == PORT_16550A);
-		tty_port_set_initialized(&ch->port, true);
+	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &moxa_openlock) {
+		brd = &moxa_boards[port / MAX_PORTS_PER_BOARD];
+		if (!brd->ready)
+			return -ENODEV;
+
+		if (port % MAX_PORTS_PER_BOARD >= brd->numPorts)
+			return -ENODEV;
+
+		ch = &brd->ports[port % MAX_PORTS_PER_BOARD];
+		ch->port.count++;
+		tty->driver_data = ch;
+		tty_port_tty_set(&ch->port, tty);
+
+		guard(mutex)(&ch->port.mutex);
+		if (!tty_port_initialized(&ch->port)) {
+			ch->statusflags = 0;
+			moxa_set_tty_param(tty, &tty->termios);
+			MoxaPortLineCtrl(ch, true, true);
+			MoxaPortEnable(ch);
+			MoxaSetFifo(ch, ch->type == PORT_16550A);
+			tty_port_set_initialized(&ch->port, true);
+		}
 	}
-	mutex_unlock(&ch->port.mutex);
-	mutex_unlock(&moxa_openlock);
 
 	return tty_port_block_til_ready(&ch->port, tty, filp);
 }
@@ -1270,15 +1256,13 @@ static void moxa_close(struct tty_struct *tty, struct file *filp)
 static ssize_t moxa_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct moxa_port *ch = tty->driver_data;
-	unsigned long flags;
 	int len;
 
 	if (ch == NULL)
 		return 0;
 
-	spin_lock_irqsave(&moxa_lock, flags);
-	len = MoxaPortWriteData(tty, buf, count);
-	spin_unlock_irqrestore(&moxa_lock, flags);
+	scoped_guard(spinlock_irqsave, &moxa_lock)
+		len = MoxaPortWriteData(tty, buf, count);
 
 	set_bit(LOWWAIT, &ch->statusflags);
 	return len;
@@ -1349,12 +1333,10 @@ static int moxa_tiocmset(struct tty_struct *tty,
 	bool dtr_active, rts_active;
 	struct moxa_port *ch;
 
-	mutex_lock(&moxa_openlock);
+	guard(mutex)(&moxa_openlock);
 	ch = tty->driver_data;
-	if (!ch) {
-		mutex_unlock(&moxa_openlock);
+	if (!ch)
 		return -EINVAL;
-	}
 
 	MoxaPortGetLineOut(ch, &dtr_active, &rts_active);
 	if (set & TIOCM_RTS)
@@ -1366,7 +1348,7 @@ static int moxa_tiocmset(struct tty_struct *tty,
 	if (clear & TIOCM_DTR)
 		dtr_active = false;
 	MoxaPortLineCtrl(ch, dtr_active, rts_active);
-	mutex_unlock(&moxa_openlock);
+
 	return 0;
 }
 
@@ -1415,18 +1397,17 @@ static void moxa_hangup(struct tty_struct *tty)
 
 static void moxa_new_dcdstate(struct moxa_port *p, u8 dcd)
 {
-	unsigned long flags;
 	dcd = !!dcd;
 
-	spin_lock_irqsave(&p->port.lock, flags);
-	if (dcd != p->DCDState) {
-        	p->DCDState = dcd;
-        	spin_unlock_irqrestore(&p->port.lock, flags);
-		if (!dcd)
-			tty_port_tty_hangup(&p->port, true);
+	scoped_guard(spinlock_irqsave, &p->port.lock) {
+		if (dcd == p->DCDState)
+			return;
+
+		p->DCDState = dcd;
 	}
-	else
-		spin_unlock_irqrestore(&p->port.lock, flags);
+
+	if (!dcd)
+		tty_port_tty_hangup(&p->port, true);
 }
 
 static int moxa_poll_port(struct moxa_port *p, unsigned int handle,
@@ -1494,7 +1475,7 @@ static void moxa_poll(struct timer_list *unused)
 	u16 __iomem *ip;
 	unsigned int card, port, served = 0;
 
-	spin_lock(&moxa_lock);
+	guard(spinlock)(&moxa_lock);
 	for (card = 0; card < MAX_BOARDS; card++) {
 		brd = &moxa_boards[card];
 		if (!brd->ready)
@@ -1525,7 +1506,6 @@ static void moxa_poll(struct timer_list *unused)
 
 	if (served)
 		mod_timer(&moxaTimer, jiffies + HZ / 50);
-	spin_unlock(&moxa_lock);
 }
 
 /******************************************************************************/
@@ -1861,13 +1841,11 @@ static int MoxaPortSetTermio(struct moxa_port *port, struct ktermios *termio,
 	baud = MoxaPortSetBaud(port, baud);
 
 	if (termio->c_iflag & (IXON | IXOFF | IXANY)) {
-	        spin_lock_irq(&moxafunc_lock);
+		guard(spinlock_irq)(&moxafunc_lock);
 		writeb(termio->c_cc[VSTART], ofsAddr + FuncArg);
 		writeb(termio->c_cc[VSTOP], ofsAddr + FuncArg1);
 		writeb(FC_SetXonXoff, ofsAddr + FuncCode);
 		moxa_wait_finish(ofsAddr);
-		spin_unlock_irq(&moxafunc_lock);
-
 	}
 	return baud;
 }
@@ -2098,13 +2076,13 @@ static int moxa_get_serial_info(struct tty_struct *tty,
 
 	if (!info)
 		return -ENODEV;
-	mutex_lock(&info->port.mutex);
+	guard(mutex)(&info->port.mutex);
 	ss->type = info->type;
 	ss->line = info->port.tty->index;
 	ss->flags = info->port.flags;
 	ss->baud_base = 921600;
 	ss->close_delay = jiffies_to_msecs(info->port.close_delay) / 10;
-	mutex_unlock(&info->port.mutex);
+
 	return 0;
 }
 
@@ -2120,13 +2098,12 @@ static int moxa_set_serial_info(struct tty_struct *tty,
 
 	close_delay = msecs_to_jiffies(ss->close_delay * 10);
 
-	mutex_lock(&info->port.mutex);
+	guard(mutex)(&info->port.mutex);
 	if (!capable(CAP_SYS_ADMIN)) {
 		if (close_delay != info->port.close_delay ||
 		    ss->type != info->type ||
 		    ((ss->flags & ~ASYNC_USR_MASK) !=
 		     (info->port.flags & ~ASYNC_USR_MASK))) {
-			mutex_unlock(&info->port.mutex);
 			return -EPERM;
 		}
 	} else {
@@ -2136,7 +2113,7 @@ static int moxa_set_serial_info(struct tty_struct *tty,
 
 		info->type = ss->type;
 	}
-	mutex_unlock(&info->port.mutex);
+
 	return 0;
 }
 
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 553d8c70352b..214abeb89aaa 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -4165,7 +4165,7 @@ static int gsm_modem_upd_via_msc(struct gsm_dlci *dlci, u8 brk)
 /**
  * gsm_modem_send_initial_msc - Send initial modem status message
  *
- * @dlci channel
+ * @dlci: channel
  *
  * Send an initial MSC message after DLCI open to set the initial
  * modem status lines. This is only done for basic mode.
diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c
index 4a4dc58b866a..3c9dcb0928c6 100644
--- a/drivers/tty/n_hdlc.c
+++ b/drivers/tty/n_hdlc.c
@@ -263,21 +263,18 @@ static int n_hdlc_tty_open(struct tty_struct *tty)
  */
 static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
 {
-	unsigned long flags;
 	struct n_hdlc_buf *tbuf;
 	ssize_t actual;
 
 check_again:
-
-	spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
-	if (n_hdlc->tbusy) {
-		n_hdlc->woke_up = true;
-		spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
-		return;
+	scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock) {
+		if (n_hdlc->tbusy) {
+			n_hdlc->woke_up = true;
+			return;
+		}
+		n_hdlc->tbusy = true;
+		n_hdlc->woke_up = false;
 	}
-	n_hdlc->tbusy = true;
-	n_hdlc->woke_up = false;
-	spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
 
 	tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
 	while (tbuf) {
@@ -324,9 +321,8 @@ check_again:
 		clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 
 	/* Clear the re-entry flag */
-	spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
-	n_hdlc->tbusy = false;
-	spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
+	scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock)
+		n_hdlc->tbusy = false;
 
 	if (n_hdlc->woke_up)
 		goto check_again;
@@ -584,9 +580,7 @@ static int n_hdlc_tty_ioctl(struct tty_struct *tty, unsigned int cmd,
 			    unsigned long arg)
 {
 	struct n_hdlc *n_hdlc = tty->disc_data;
-	int error = 0;
 	int count;
-	unsigned long flags;
 	struct n_hdlc_buf *buf = NULL;
 
 	pr_debug("%s() called %d\n", __func__, cmd);
@@ -595,29 +589,27 @@ static int n_hdlc_tty_ioctl(struct tty_struct *tty, unsigned int cmd,
 	case FIONREAD:
 		/* report count of read data available */
 		/* in next available frame (if any) */
-		spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock, flags);
-		buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list,
-						struct n_hdlc_buf, list_item);
-		if (buf)
-			count = buf->count;
-		else
-			count = 0;
-		spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock, flags);
-		error = put_user(count, (int __user *)arg);
-		break;
+		scoped_guard(spinlock_irqsave, &n_hdlc->rx_buf_list.spinlock) {
+			buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list,
+						       struct n_hdlc_buf, list_item);
+			if (buf)
+				count = buf->count;
+			else
+				count = 0;
+		}
+		return put_user(count, (int __user *)arg);
 
 	case TIOCOUTQ:
 		/* get the pending tx byte count in the driver */
 		count = tty_chars_in_buffer(tty);
 		/* add size of next output frame in queue */
-		spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
-		buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list,
-						struct n_hdlc_buf, list_item);
-		if (buf)
-			count += buf->count;
-		spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
-		error = put_user(count, (int __user *)arg);
-		break;
+		scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock) {
+			buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list,
+						       struct n_hdlc_buf, list_item);
+			if (buf)
+				count += buf->count;
+		}
+		return put_user(count, (int __user *)arg);
 
 	case TCFLSH:
 		switch (arg) {
@@ -628,11 +620,8 @@ static int n_hdlc_tty_ioctl(struct tty_struct *tty, unsigned int cmd,
 		fallthrough;	/* to default */
 
 	default:
-		error = n_tty_ioctl_helper(tty, cmd, arg);
-		break;
+		return n_tty_ioctl_helper(tty, cmd, arg);
 	}
-	return error;
-
 }	/* end of n_hdlc_tty_ioctl() */
 
 /**
@@ -726,14 +715,10 @@ static struct n_hdlc *n_hdlc_alloc(void)
 static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list,
 						struct n_hdlc_buf *buf)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&buf_list->spinlock, flags);
+	guard(spinlock_irqsave)(&buf_list->spinlock);
 
 	list_add(&buf->list_item, &buf_list->list);
 	buf_list->count++;
-
-	spin_unlock_irqrestore(&buf_list->spinlock, flags);
 }
 
 /**
@@ -744,14 +729,10 @@ static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list,
 static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list,
 			   struct n_hdlc_buf *buf)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&buf_list->spinlock, flags);
+	guard(spinlock_irqsave)(&buf_list->spinlock);
 
 	list_add_tail(&buf->list_item, &buf_list->list);
 	buf_list->count++;
-
-	spin_unlock_irqrestore(&buf_list->spinlock, flags);
 }	/* end of n_hdlc_buf_put() */
 
 /**
@@ -764,10 +745,9 @@ static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list,
  */
 static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list)
 {
-	unsigned long flags;
 	struct n_hdlc_buf *buf;
 
-	spin_lock_irqsave(&buf_list->spinlock, flags);
+	guard(spinlock_irqsave)(&buf_list->spinlock);
 
 	buf = list_first_entry_or_null(&buf_list->list,
 						struct n_hdlc_buf, list_item);
@@ -776,7 +756,6 @@ static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list)
 		buf_list->count--;
 	}
 
-	spin_unlock_irqrestore(&buf_list->spinlock, flags);
 	return buf;
 }	/* end of n_hdlc_buf_get() */
 
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 6af3f3a0b531..e6a0f5b40d0a 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -324,12 +324,9 @@ static void reset_buffer_flags(struct n_tty_data *ldata)
 
 static void n_tty_packet_mode_flush(struct tty_struct *tty)
 {
-	unsigned long flags;
-
 	if (tty->link->ctrl.packet) {
-		spin_lock_irqsave(&tty->ctrl.lock, flags);
-		tty->ctrl.pktstatus |= TIOCPKT_FLUSHREAD;
-		spin_unlock_irqrestore(&tty->ctrl.lock, flags);
+		scoped_guard(spinlock_irqsave, &tty->ctrl.lock)
+			tty->ctrl.pktstatus |= TIOCPKT_FLUSHREAD;
 		wake_up_interruptible(&tty->link->read_wait);
 	}
 }
@@ -349,13 +346,12 @@ static void n_tty_packet_mode_flush(struct tty_struct *tty)
  */
 static void n_tty_flush_buffer(struct tty_struct *tty)
 {
-	down_write(&tty->termios_rwsem);
+	guard(rwsem_write)(&tty->termios_rwsem);
 	reset_buffer_flags(tty->disc_data);
 	n_tty_kick_worker(tty);
 
 	if (tty->link)
 		n_tty_packet_mode_flush(tty);
-	up_write(&tty->termios_rwsem);
 }
 
 /**
@@ -737,24 +733,22 @@ static void commit_echoes(struct tty_struct *tty)
 	size_t nr, old, echoed;
 	size_t head;
 
-	mutex_lock(&ldata->output_lock);
-	head = ldata->echo_head;
-	ldata->echo_mark = head;
-	old = ldata->echo_commit - ldata->echo_tail;
-
-	/* Process committed echoes if the accumulated # of bytes
-	 * is over the threshold (and try again each time another
-	 * block is accumulated) */
-	nr = head - ldata->echo_tail;
-	if (nr < ECHO_COMMIT_WATERMARK ||
-	    (nr % ECHO_BLOCK > old % ECHO_BLOCK)) {
-		mutex_unlock(&ldata->output_lock);
-		return;
-	}
+	scoped_guard(mutex, &ldata->output_lock) {
+		head = ldata->echo_head;
+		ldata->echo_mark = head;
+		old = ldata->echo_commit - ldata->echo_tail;
+
+		/*
+		 * Process committed echoes if the accumulated # of bytes is over the threshold
+		 * (and try again each time another block is accumulated)
+		 */
+		nr = head - ldata->echo_tail;
+		if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
+			return;
 
-	ldata->echo_commit = head;
-	echoed = __process_echoes(tty);
-	mutex_unlock(&ldata->output_lock);
+		ldata->echo_commit = head;
+		echoed = __process_echoes(tty);
+	}
 
 	if (echoed && tty->ops->flush_chars)
 		tty->ops->flush_chars(tty);
@@ -768,10 +762,10 @@ static void process_echoes(struct tty_struct *tty)
 	if (ldata->echo_mark == ldata->echo_tail)
 		return;
 
-	mutex_lock(&ldata->output_lock);
-	ldata->echo_commit = ldata->echo_mark;
-	echoed = __process_echoes(tty);
-	mutex_unlock(&ldata->output_lock);
+	scoped_guard(mutex, &ldata->output_lock) {
+		ldata->echo_commit = ldata->echo_mark;
+		echoed = __process_echoes(tty);
+	}
 
 	if (echoed && tty->ops->flush_chars)
 		tty->ops->flush_chars(tty);
@@ -786,10 +780,9 @@ static void flush_echoes(struct tty_struct *tty)
 	    ldata->echo_commit == ldata->echo_head)
 		return;
 
-	mutex_lock(&ldata->output_lock);
+	guard(mutex)(&ldata->output_lock);
 	ldata->echo_commit = ldata->echo_head;
 	__process_echoes(tty);
-	mutex_unlock(&ldata->output_lock);
 }
 
 /**
@@ -1078,18 +1071,19 @@ static void isig(int sig, struct tty_struct *tty)
 	if (L_NOFLSH(tty)) {
 		/* signal only */
 		__isig(sig, tty);
+		return;
+	}
 
-	} else { /* signal and flush */
-		up_read(&tty->termios_rwsem);
-		down_write(&tty->termios_rwsem);
-
+	/* signal and flush */
+	up_read(&tty->termios_rwsem);
+	scoped_guard(rwsem_write, &tty->termios_rwsem) {
 		__isig(sig, tty);
 
 		/* clear echo buffer */
-		mutex_lock(&ldata->output_lock);
-		ldata->echo_head = ldata->echo_tail = 0;
-		ldata->echo_mark = ldata->echo_commit = 0;
-		mutex_unlock(&ldata->output_lock);
+		scoped_guard(mutex, &ldata->output_lock) {
+			ldata->echo_head = ldata->echo_tail = 0;
+			ldata->echo_mark = ldata->echo_commit = 0;
+		}
 
 		/* clear output buffer */
 		tty_driver_flush_buffer(tty);
@@ -1100,10 +1094,8 @@ static void isig(int sig, struct tty_struct *tty)
 		/* notify pty master of flush */
 		if (tty->link)
 			n_tty_packet_mode_flush(tty);
-
-		up_write(&tty->termios_rwsem);
-		down_read(&tty->termios_rwsem);
 	}
+	down_read(&tty->termios_rwsem);
 }
 
 /**
@@ -1683,7 +1675,7 @@ n_tty_receive_buf_common(struct tty_struct *tty, const u8 *cp, const u8 *fp,
 	size_t n, rcvd = 0;
 	int room, overflow;
 
-	down_read(&tty->termios_rwsem);
+	guard(rwsem_read)(&tty->termios_rwsem);
 
 	do {
 		/*
@@ -1752,8 +1744,6 @@ n_tty_receive_buf_common(struct tty_struct *tty, const u8 *cp, const u8 *fp,
 			n_tty_kick_worker(tty);
 	}
 
-	up_read(&tty->termios_rwsem);
-
 	return rcvd;
 }
 
@@ -1879,10 +1869,9 @@ static void n_tty_close(struct tty_struct *tty)
 	if (tty->link)
 		n_tty_packet_mode_flush(tty);
 
-	down_write(&tty->termios_rwsem);
+	guard(rwsem_write)(&tty->termios_rwsem);
 	vfree(ldata);
 	tty->disc_data = NULL;
-	up_write(&tty->termios_rwsem);
 }
 
 /**
@@ -2247,10 +2236,10 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, u8 *kbuf,
 			u8 cs;
 			if (kb != kbuf)
 				break;
-			spin_lock_irq(&tty->link->ctrl.lock);
-			cs = tty->link->ctrl.pktstatus;
-			tty->link->ctrl.pktstatus = 0;
-			spin_unlock_irq(&tty->link->ctrl.lock);
+			scoped_guard(spinlock_irq, &tty->link->ctrl.lock) {
+				cs = tty->link->ctrl.pktstatus;
+				tty->link->ctrl.pktstatus = 0;
+			}
 			*kb++ = cs;
 			nr--;
 			break;
@@ -2357,7 +2346,7 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
 			return retval;
 	}