tty: serial_core: use more guard(mutex)

Simplify 4 more functions using guard(mutex): uart_get_info(),
console_store(), serial_core_add_one_port(), and
serial_core_register_port(). Especially console_store() is now much less
convoluted. In the others, we save some goto-s and even local variables
are dropped in some.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20241211074933.92973-2-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 74fa02b237729931928b2ae4902c699ec017af94..f595f2336fc01988eb1005a65fe0a6d6b837c04b 100644 (file)
--- 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,
@@ -3061,26 +3057,25 @@ 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 +3131,6 @@ 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 +3140,9 @@ 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 +3162,8 @@ 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 +3179,9 @@ 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 +3204,7 @@ 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 +3370,7 @@ 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 +3382,8 @@ 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 +3404,6 @@ 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 +3412,6 @@ err_unregister_port_dev:
 err_unregister_ctrl_dev:
        serial_base_ctrl_device_remove(new_ctrl_dev);
 
-err_unlock:
-       mutex_unlock(&port_mutex);
-
        return ret;
 }