1 files changed, 116 insertions, 149 deletions

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 74fa02b23772..92f7e752f862 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -790,7 +790,6 @@ static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
 {
 	struct uart_state *state = container_of(port, struct uart_state, port);
 	struct uart_port *uport;
-	int ret = -ENODEV;
 
 	/* Initialize structure in case we error out later to prevent any stack info leakage. */
 	*retinfo = (struct serial_struct){};
@@ -799,10 +798,10 @@ static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
 	 * Ensure the state we copy is consistent and no hardware changes
 	 * occur as we go
 	 */
-	mutex_lock(&port->mutex);
+	guard(mutex)(&port->mutex);
 	uport = uart_port_check(state);
 	if (!uport)
-		goto out;
+		return -ENODEV;
 
 	retinfo->type	    = uport->type;
 	retinfo->line	    = uport->line;
@@ -823,10 +822,7 @@ static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
 	retinfo->iomem_reg_shift = uport->regshift;
 	retinfo->iomem_base      = (void *)(unsigned long)uport->mapbase;
 
-	ret = 0;
-out:
-	mutex_unlock(&port->mutex);
-	return ret;
+	return 0;
 }
 
 static int uart_get_info_user(struct tty_struct *tty,
@@ -838,6 +834,61 @@ static int uart_get_info_user(struct tty_struct *tty,
 	return uart_get_info(port, ss) < 0 ? -EIO : 0;
 }
 
+static int uart_change_port(struct uart_port *uport,
+			    const struct serial_struct *new_info,
+			    unsigned long new_port)
+{
+	unsigned long old_iobase, old_mapbase;
+	unsigned int old_type, old_iotype, old_hub6, old_shift;
+	int retval;
+
+	old_iobase = uport->iobase;
+	old_mapbase = uport->mapbase;
+	old_type = uport->type;
+	old_hub6 = uport->hub6;
+	old_iotype = uport->iotype;
+	old_shift = uport->regshift;
+
+	if (old_type != PORT_UNKNOWN && uport->ops->release_port)
+		uport->ops->release_port(uport);
+
+	uport->iobase = new_port;
+	uport->type = new_info->type;
+	uport->hub6 = new_info->hub6;
+	uport->iotype = new_info->io_type;
+	uport->regshift = new_info->iomem_reg_shift;
+	uport->mapbase = (unsigned long)new_info->iomem_base;
+
+	if (uport->type == PORT_UNKNOWN || !uport->ops->request_port)
+		return 0;
+
+	retval = uport->ops->request_port(uport);
+	if (retval == 0)
+		return 0; /* succeeded => done */
+
+	/*
+	 * If we fail to request resources for the new port, try to restore the
+	 * old settings.
+	 */
+	uport->iobase = old_iobase;
+	uport->type = old_type;
+	uport->hub6 = old_hub6;
+	uport->iotype = old_iotype;
+	uport->regshift = old_shift;
+	uport->mapbase = old_mapbase;
+
+	if (old_type == PORT_UNKNOWN)
+		return retval;
+
+	retval = uport->ops->request_port(uport);
+	/* If we failed to restore the old settings, we fail like this. */
+	if (retval)
+		uport->type = PORT_UNKNOWN;
+
+	/* We failed anyway. */
+	return -EBUSY;
+}
+
 static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 			 struct uart_state *state,
 			 struct serial_struct *new_info)
@@ -847,7 +898,7 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 	unsigned int change_irq, change_port, closing_wait;
 	unsigned int old_custom_divisor, close_delay;
 	upf_t old_flags, new_flags;
-	int retval = 0;
+	int retval;
 
 	if (!uport)
 		return -EIO;
@@ -886,13 +937,10 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 	if (!(uport->flags & UPF_FIXED_PORT)) {
 		unsigned int uartclk = new_info->baud_base * 16;
 		/* check needs to be done here before other settings made */
-		if (uartclk == 0) {
-			retval = -EINVAL;
-			goto exit;
-		}
+		if (uartclk == 0)
+			return -EINVAL;
 	}
 	if (!capable(CAP_SYS_ADMIN)) {
-		retval = -EPERM;
 		if (change_irq || change_port ||
 		    (new_info->baud_base != uport->uartclk / 16) ||
 		    (close_delay != port->close_delay) ||
@@ -900,7 +948,7 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 		    (new_info->xmit_fifo_size &&
 		     new_info->xmit_fifo_size != uport->fifosize) ||
 		    (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
-			goto exit;
+			return -EPERM;
 		uport->flags = ((uport->flags & ~UPF_USR_MASK) |
 			       (new_flags & UPF_USR_MASK));
 		uport->custom_divisor = new_info->custom_divisor;
@@ -910,30 +958,24 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 	if (change_irq || change_port) {
 		retval = security_locked_down(LOCKDOWN_TIOCSSERIAL);
 		if (retval)
-			goto exit;
+			return retval;
 	}
 
-	/*
-	 * Ask the low level driver to verify the settings.
-	 */
-	if (uport->ops->verify_port)
+	 /* Ask the low level driver to verify the settings. */
+	if (uport->ops->verify_port) {
 		retval = uport->ops->verify_port(uport, new_info);
+		if (retval)
+			return retval;
+	}
 
 	if ((new_info->irq >= irq_get_nr_irqs()) || (new_info->irq < 0) ||
 	    (new_info->baud_base < 9600))
-		retval = -EINVAL;
-
-	if (retval)
-		goto exit;
+		return -EINVAL;
 
 	if (change_port || change_irq) {
-		retval = -EBUSY;
-
-		/*
-		 * Make sure that we are the sole user of this port.
-		 */
+		 /* Make sure that we are the sole user of this port. */
 		if (tty_port_users(port) > 1)
-			goto exit;
+			return -EBUSY;
 
 		/*
 		 * We need to shutdown the serial port at the old
@@ -943,69 +985,9 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 	}
 
 	if (change_port) {
-		unsigned long old_iobase, old_mapbase;
-		unsigned int old_type, old_iotype, old_hub6, old_shift;
-
-		old_iobase = uport->iobase;
-		old_mapbase = uport->mapbase;
-		old_type = uport->type;
-		old_hub6 = uport->hub6;
-		old_iotype = uport->iotype;
-		old_shift = uport->regshift;
-
-		/*
-		 * Free and release old regions
-		 */
-		if (old_type != PORT_UNKNOWN && uport->ops->release_port)
-			uport->ops->release_port(uport);
-
-		uport->iobase = new_port;
-		uport->type = new_info->type;
-		uport->hub6 = new_info->hub6;
-		uport->iotype = new_info->io_type;
-		uport->regshift = new_info->iomem_reg_shift;
-		uport->mapbase = (unsigned long)new_info->iomem_base;
-
-		/*
-		 * Claim and map the new regions
-		 */
-		if (uport->type != PORT_UNKNOWN && uport->ops->request_port) {
-			retval = uport->ops->request_port(uport);
-		} else {
-			/* Always success - Jean II */
-			retval = 0;
-		}
-
-		/*
-		 * If we fail to request resources for the
-		 * new port, try to restore the old settings.
-		 */
-		if (retval) {
-			uport->iobase = old_iobase;
-			uport->type = old_type;
-			uport->hub6 = old_hub6;
-			uport->iotype = old_iotype;
-			uport->regshift = old_shift;
-			uport->mapbase = old_mapbase;
-
-			if (old_type != PORT_UNKNOWN) {
-				retval = uport->ops->request_port(uport);
-				/*
-				 * If we failed to restore the old settings,
-				 * we fail like this.
-				 */
-				if (retval)
-					uport->type = PORT_UNKNOWN;
-
-				/*
-				 * We failed anyway.
-				 */
-				retval = -EBUSY;
-			}
-
-			/* Added to return the correct error -Ram Gupta */
-			goto exit;
-		}
+		retval = uart_change_port(uport, new_info, new_port);
+		if (retval)
+			return retval;
 	}
 
 	if (change_irq)
@@ -1021,9 +1003,9 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 		uport->fifosize = new_info->xmit_fifo_size;
 
  check_and_exit:
-	retval = 0;
 	if (uport->type == PORT_UNKNOWN)
-		goto exit;
+		return 0;
+
 	if (tty_port_initialized(port)) {
 		if (((old_flags ^ uport->flags) & UPF_SPD_MASK) ||
 		    old_custom_divisor != uport->custom_divisor) {
@@ -1039,15 +1021,17 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 			}
 			uart_change_line_settings(tty, state, NULL);
 		}
-	} else {
-		retval = uart_startup(tty, state, true);
-		if (retval == 0)
-			tty_port_set_initialized(port, true);
-		if (retval > 0)
-			retval = 0;
+
+		return 0;
 	}
- exit:
-	return retval;
+
+	retval = uart_startup(tty, state, true);
+	if (retval < 0)
+		return retval;
+	if (retval == 0)
+		tty_port_set_initialized(port, true);
+
+	return 0;
 }
 
 static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
@@ -2365,9 +2349,9 @@ struct uart_match {
 	struct uart_driver *driver;
 };
 
-static int serial_match_port(struct device *dev, void *data)
+static int serial_match_port(struct device *dev, const void *data)
 {
-	struct uart_match *match = data;
+	const struct uart_match *match = data;
 	struct tty_driver *tty_drv = match->driver->tty_driver;
 	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
 		match->port->line;
@@ -3061,26 +3045,25 @@ static ssize_t console_store(struct device *dev,
 	if (ret)
 		return ret;
 
-	mutex_lock(&port->mutex);
+	guard(mutex)(&port->mutex);
 	uport = uart_port_check(state);
-	if (uport) {
-		oldconsole = uart_console_registered(uport);
-		if (oldconsole && !newconsole) {
-			ret = unregister_console(uport->cons);
-		} else if (!oldconsole && newconsole) {
-			if (uart_console(uport)) {
-				uport->console_reinit = 1;
-				register_console(uport->cons);
-			} else {
-				ret = -ENOENT;
-			}
-		}
-	} else {
-		ret = -ENXIO;
+	if (!uport)
+		return -ENXIO;
+
+	oldconsole = uart_console_registered(uport);
+	if (oldconsole && !newconsole) {
+		ret = unregister_console(uport->cons);
+		if (ret < 0)
+			return ret;
+	} else if (!oldconsole && newconsole) {
+		if (!uart_console(uport))
+			return -ENOENT;
+
+		uport->console_reinit = 1;
+		register_console(uport->cons);
 	}
-	mutex_unlock(&port->mutex);
 
-	return ret < 0 ? ret : count;
+	return count;
 }
 
 static DEVICE_ATTR_RO(uartclk);
@@ -3136,7 +3119,6 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u
 {
 	struct uart_state *state;
 	struct tty_port *port;
-	int ret = 0;
 	struct device *tty_dev;
 	int num_groups;
 
@@ -3146,11 +3128,9 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u
 	state = drv->state + uport->line;
 	port = &state->port;
 
-	mutex_lock(&port->mutex);
-	if (state->uart_port) {
-		ret = -EINVAL;
-		goto out;
-	}
+	guard(mutex)(&port->mutex);
+	if (state->uart_port)
+		return -EINVAL;
 
 	/* Link the port to the driver state table and vice versa */
 	atomic_set(&state->refcount, 1);
@@ -3170,10 +3150,8 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u
 	uport->minor = drv->tty_driver->minor_start + uport->line;
 	uport->name = kasprintf(GFP_KERNEL, "%s%d", drv->dev_name,
 				drv->tty_driver->name_base + uport->line);
-	if (!uport->name) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!uport->name)
+		return -ENOMEM;
 
 	if (uport->cons && uport->dev)
 		of_console_check(uport->dev->of_node, uport->cons->name, uport->line);
@@ -3189,10 +3167,9 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u
 
 	uport->tty_groups = kcalloc(num_groups, sizeof(*uport->tty_groups),
 				    GFP_KERNEL);
-	if (!uport->tty_groups) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!uport->tty_groups)
+		return -ENOMEM;
+
 	uport->tty_groups[0] = &tty_dev_attr_group;
 	if (uport->attr_group)
 		uport->tty_groups[1] = uport->attr_group;
@@ -3215,10 +3192,7 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u
 		       uport->line);
 	}
 
- out:
-	mutex_unlock(&port->mutex);
-
-	return ret;
+	return 0;
 }
 
 /**
@@ -3384,7 +3358,7 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
 	struct serial_ctrl_device *ctrl_dev, *new_ctrl_dev = NULL;
 	int ret;
 
-	mutex_lock(&port_mutex);
+	guard(mutex)(&port_mutex);
 
 	/*
 	 * Prevent serial_port_runtime_resume() from trying to use the port
@@ -3396,10 +3370,8 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
 	ctrl_dev = serial_core_ctrl_find(drv, port->dev, port->ctrl_id);
 	if (!ctrl_dev) {
 		new_ctrl_dev = serial_core_ctrl_device_add(port);
-		if (IS_ERR(new_ctrl_dev)) {
-			ret = PTR_ERR(new_ctrl_dev);
-			goto err_unlock;
-		}
+		if (IS_ERR(new_ctrl_dev))
+			return PTR_ERR(new_ctrl_dev);
 		ctrl_dev = new_ctrl_dev;
 	}
 
@@ -3420,8 +3392,6 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
 	if (ret)
 		goto err_unregister_port_dev;
 
-	mutex_unlock(&port_mutex);
-
 	return 0;
 
 err_unregister_port_dev:
@@ -3430,9 +3400,6 @@ err_unregister_port_dev:
 err_unregister_ctrl_dev:
 	serial_base_ctrl_device_remove(new_ctrl_dev);
 
-err_unlock:
-	mutex_unlock(&port_mutex);
-
 	return ret;
 }