tty: moxa: use guard()s

Use guards in the moxa code. This improves readability, makes error
handling easier, and marks locked portions of code explicit. All that
while being sure the lock is unlocked.

Signed-off-by: Jiri Slaby (SUSE) <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/moxa.c

···
 
 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)
···
 	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++)
···
 {
 	unsigned int a, opened, first_idx;
 
-	mutex_lock(&moxa_openlock);
-	spin_lock_bh(&moxa_lock);
-	brd->ready = 0;
-	spin_unlock_bh(&moxa_lock);
+	scoped_guard(mutex, &moxa_openlock) {
+		scoped_guard(spinlock_bh, &moxa_lock)
+			brd->ready = 0;
 
-	/* 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);
-
-	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;
···
 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)
···
 {
 	struct moxa_board_conf *brd;
 	struct moxa_port *ch;
-	int port;
+	int port = tty->index;
 
-	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;
-	}
+	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) {
-		mutex_unlock(&moxa_openlock);
-		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);
-	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);
+		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);
 }
···
 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;
···
 	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)
···
 	if (clear & TIOCM_DTR)
 		dtr_active = false;
 	MoxaPortLineCtrl(ch, dtr_active, rts_active);
-	mutex_unlock(&moxa_openlock);
+
 	return 0;
 }
 
···
 
 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,
···
 	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)
···
 
 	if (served)
 		mod_timer(&moxaTimer, jiffies + HZ / 50);
-	spin_unlock(&moxa_lock);
 }
 
 /******************************************************************************/
···
 	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;
 }
···
 
 	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;
 }
 
···
 
 	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 {
···
 
 		info->type = ss->type;
 	}
-	mutex_unlock(&info->port.mutex);
+
 	return 0;
 }