serial: serial_core: use guard()s
Use guards in the serial_core 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) <jirislaby@kernel.org> Link: https://patch.msgid.link/20251119100140.830761-11-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE)
Greg Kroah-Hartman
parent
f374a33e90
commit
b844e63807
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@ -1034,9 +1034,8 @@ static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
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{
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struct uart_state *state = tty->driver_data;
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struct tty_port *port = &state->port;
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int retval;
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down_write(&tty->termios_rwsem);
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guard(rwsem_write)(&tty->termios_rwsem);
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/*
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* This semaphore protects port->count. It is also
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* very useful to prevent opens. Also, take the
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@ -1044,11 +1043,8 @@ static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
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* module insertion/removal doesn't change anything
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* under us.
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*/
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mutex_lock(&port->mutex);
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retval = uart_set_info(tty, port, state, ss);
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mutex_unlock(&port->mutex);
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up_write(&tty->termios_rwsem);
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return retval;
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guard(mutex)(&port->mutex);
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return uart_set_info(tty, port, state, ss);
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}
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/**
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@ -1562,10 +1558,8 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
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/* This ioctl doesn't rely on the hardware to be present. */
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if (cmd == TIOCSERCONFIG) {
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down_write(&tty->termios_rwsem);
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ret = uart_do_autoconfig(tty, state);
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up_write(&tty->termios_rwsem);
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return ret;
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guard(rwsem_write)(&tty->termios_rwsem);
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return uart_do_autoconfig(tty, state);
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}
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if (tty_io_error(tty))
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@ -1579,46 +1573,46 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
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if (cmd == TIOCSRS485)
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down_write(&tty->termios_rwsem);
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mutex_lock(&port->mutex);
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uport = uart_port_check(state);
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scoped_guard(mutex, &port->mutex) {
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uport = uart_port_check(state);
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if (!uport || tty_io_error(tty)) {
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ret = -EIO;
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goto out_up;
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if (!uport || tty_io_error(tty)) {
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ret = -EIO;
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break;
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}
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/*
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* All these rely on hardware being present and need to be
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* protected against the tty being hung up.
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*/
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switch (cmd) {
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case TIOCSERGETLSR: /* Get line status register */
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ret = uart_get_lsr_info(tty, state, uarg);
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break;
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case TIOCGRS485:
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ret = uart_get_rs485_config(uport, uarg);
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break;
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case TIOCSRS485:
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ret = uart_set_rs485_config(tty, uport, uarg);
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break;
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case TIOCSISO7816:
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ret = uart_set_iso7816_config(state->uart_port, uarg);
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break;
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case TIOCGISO7816:
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ret = uart_get_iso7816_config(state->uart_port, uarg);
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break;
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default:
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if (uport->ops->ioctl)
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ret = uport->ops->ioctl(uport, cmd, arg);
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break;
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}
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}
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/*
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* All these rely on hardware being present and need to be
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* protected against the tty being hung up.
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*/
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switch (cmd) {
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case TIOCSERGETLSR: /* Get line status register */
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ret = uart_get_lsr_info(tty, state, uarg);
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break;
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case TIOCGRS485:
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ret = uart_get_rs485_config(uport, uarg);
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break;
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case TIOCSRS485:
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ret = uart_set_rs485_config(tty, uport, uarg);
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break;
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case TIOCSISO7816:
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ret = uart_set_iso7816_config(state->uart_port, uarg);
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break;
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case TIOCGISO7816:
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ret = uart_get_iso7816_config(state->uart_port, uarg);
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break;
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default:
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if (uport->ops->ioctl)
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ret = uport->ops->ioctl(uport, cmd, arg);
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break;
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}
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out_up:
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mutex_unlock(&port->mutex);
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if (cmd == TIOCSRS485)
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up_write(&tty->termios_rwsem);
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@ -1634,11 +1628,10 @@ static void uart_set_ldisc(struct tty_struct *tty)
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if (!tty_port_initialized(port))
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return;
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mutex_lock(&state->port.mutex);
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guard(mutex)(&state->port.mutex);
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uport = uart_port_check(state);
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if (uport && uport->ops->set_ldisc)
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uport->ops->set_ldisc(uport, &tty->termios);
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mutex_unlock(&state->port.mutex);
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}
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static void uart_set_termios(struct tty_struct *tty,
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@ -1712,9 +1705,8 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
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state = drv->state + tty->index;
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port = &state->port;
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spin_lock_irq(&port->lock);
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guard(spinlock_irq)(&port->lock);
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--port->count;
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spin_unlock_irq(&port->lock);
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return;
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}
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@ -1826,20 +1818,18 @@ static void uart_hangup(struct tty_struct *tty)
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struct uart_state *state = tty->driver_data;
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struct tty_port *port = &state->port;
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struct uart_port *uport;
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unsigned long flags;
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pr_debug("uart_hangup(%d)\n", tty->index);
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mutex_lock(&port->mutex);
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guard(mutex)(&port->mutex);
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uport = uart_port_check(state);
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WARN(!uport, "hangup of detached port!\n");
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if (tty_port_active(port)) {
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uart_flush_buffer(tty);
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uart_shutdown(tty, state);
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spin_lock_irqsave(&port->lock, flags);
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port->count = 0;
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spin_unlock_irqrestore(&port->lock, flags);
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scoped_guard(spinlock_irqsave, &port->lock)
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port->count = 0;
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tty_port_set_active(port, false);
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tty_port_tty_set(port, NULL);
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if (uport && !uart_console(uport))
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@ -1847,7 +1837,6 @@ static void uart_hangup(struct tty_struct *tty)
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wake_up_interruptible(&port->open_wait);
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wake_up_interruptible(&port->delta_msr_wait);
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}
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mutex_unlock(&port->mutex);
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}
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/* uport == NULL if uart_port has already been removed */
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@ -2952,11 +2941,11 @@ static ssize_t console_show(struct device *dev,
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struct uart_port *uport;
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bool console = false;
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mutex_lock(&port->mutex);
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uport = uart_port_check(state);
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if (uport)
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console = uart_console_registered(uport);
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mutex_unlock(&port->mutex);
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scoped_guard(mutex, &port->mutex) {
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uport = uart_port_check(state);
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if (uport)
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console = uart_console_registered(uport);
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}
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return sprintf(buf, "%c\n", console ? 'Y' : 'N');
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}
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@ -3141,17 +3130,14 @@ static void serial_core_remove_one_port(struct uart_driver *drv,
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struct tty_port *port = &state->port;
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struct uart_port *uart_port;
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mutex_lock(&port->mutex);
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uart_port = uart_port_check(state);
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if (uart_port != uport)
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dev_alert(uport->dev, "Removing wrong port: %p != %p\n",
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uart_port, uport);
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scoped_guard(mutex, &port->mutex) {
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uart_port = uart_port_check(state);
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if (uart_port != uport)
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dev_alert(uport->dev, "Removing wrong port: %p != %p\n", uart_port, uport);
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if (!uart_port) {
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mutex_unlock(&port->mutex);
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return;
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if (!uart_port)
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return;
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}
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mutex_unlock(&port->mutex);
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/*
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* Remove the devices from the tty layer
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@ -3180,11 +3166,10 @@ static void serial_core_remove_one_port(struct uart_driver *drv,
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uport->type = PORT_UNKNOWN;
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uport->port_dev = NULL;
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mutex_lock(&port->mutex);
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guard(mutex)(&port->mutex);
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WARN_ON(atomic_dec_return(&state->refcount) < 0);
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wait_event(state->remove_wait, !atomic_read(&state->refcount));
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state->uart_port = NULL;
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mutex_unlock(&port->mutex);
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}
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/**
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@ -3337,7 +3322,7 @@ void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port
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struct serial_ctrl_device *ctrl_dev = serial_core_get_ctrl_dev(port_dev);
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int ctrl_id = port->ctrl_id;
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mutex_lock(&port_mutex);
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guard(mutex)(&port_mutex);
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port->flags |= UPF_DEAD;
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@ -3349,8 +3334,6 @@ void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port
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/* Drop the serial core controller device if no ports are using it */
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if (!serial_core_ctrl_find(drv, phys_dev, ctrl_id))
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serial_base_ctrl_device_remove(ctrl_dev);
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mutex_unlock(&port_mutex);
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}
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/**
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