serial: core: Prevent unsafe uart port access, part 1
uart_remove_one_port() may race with every serial core operation requiring a valid dereference of state->uart_port. In particular, uart_remove_one_port() may unlink the uart port concurrently with any serial core operation that may dereference same. Ensure safe dereference for those operations that already claim the port->mutex, and extend that guarantee for trivial cases, such as the ioctl handlers. Introduce the uart_port_check() helper which asserts port->mutex is held (only when lockdep is on). For ioctls, return -EIO as if the port has been hung up (since it has). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley
Greg Kroah-Hartman
Родитель
49c02304fe
Коммит
4047b37122
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@ -64,6 +64,14 @@ static int uart_dcd_enabled(struct uart_port *uport)
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return !!(uport->status & UPSTAT_DCD_ENABLE);
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}
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static inline struct uart_port *uart_port_check(struct uart_state *state)
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{
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#ifdef CONFIG_LOCKDEP
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WARN_ON(!lockdep_is_held(&state->port.mutex));
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#endif
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return state->uart_port;
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}
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/*
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* This routine is used by the interrupt handler to schedule processing in
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* the software interrupt portion of the driver.
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@ -134,7 +142,7 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
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static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
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int init_hw)
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{
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport = uart_port_check(state);
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unsigned long page;
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int retval = 0;
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@ -222,7 +230,7 @@ static int uart_startup(struct tty_struct *tty, struct uart_state *state,
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*/
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static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
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{
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport = uart_port_check(state);
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struct tty_port *port = &state->port;
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/*
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@ -443,7 +451,7 @@ EXPORT_SYMBOL(uart_get_divisor);
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static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
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struct ktermios *old_termios)
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{
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport = uart_port_check(state);
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struct ktermios *termios;
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int hw_stopped;
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@ -673,10 +681,11 @@ static void uart_unthrottle(struct tty_struct *tty)
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uart_send_xchar(tty, START_CHAR(tty));
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}
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static void uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
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static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
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{
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struct uart_state *state = container_of(port, struct uart_state, port);
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport;
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int ret = -ENODEV;
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memset(retinfo, 0, sizeof(*retinfo));
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@ -685,6 +694,10 @@ static void uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
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* occur as we go
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*/
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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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goto out;
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retinfo->type = uport->type;
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retinfo->line = uport->line;
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retinfo->port = uport->iobase;
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@ -703,7 +716,11 @@ static void uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
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retinfo->io_type = uport->iotype;
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retinfo->iomem_reg_shift = uport->regshift;
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retinfo->iomem_base = (void *)(unsigned long)uport->mapbase;
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ret = 0;
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out:
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mutex_unlock(&port->mutex);
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return ret;
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}
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static int uart_get_info_user(struct tty_port *port,
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@ -711,7 +728,8 @@ static int uart_get_info_user(struct tty_port *port,
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{
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struct serial_struct tmp;
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uart_get_info(port, &tmp);
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if (uart_get_info(port, &tmp) < 0)
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return -EIO;
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if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
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return -EFAULT;
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@ -722,13 +740,16 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
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struct uart_state *state,
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struct serial_struct *new_info)
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{
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport = uart_port_check(state);
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unsigned long new_port;
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unsigned int change_irq, change_port, closing_wait;
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unsigned int old_custom_divisor, close_delay;
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upf_t old_flags, new_flags;
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int retval = 0;
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if (!uport)
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return -EIO;
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new_port = new_info->port;
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if (HIGH_BITS_OFFSET)
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new_port += (unsigned long) new_info->port_high << HIGH_BITS_OFFSET;
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@ -938,13 +959,11 @@ static int uart_set_info_user(struct tty_struct *tty, struct uart_state *state,
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* @tty: tty associated with the UART
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* @state: UART being queried
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* @value: returned modem value
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*
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* Note: uart_ioctl protects us against hangups.
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*/
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static int uart_get_lsr_info(struct tty_struct *tty,
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struct uart_state *state, unsigned int __user *value)
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{
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport = uart_port_check(state);
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unsigned int result;
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result = uport->ops->tx_empty(uport);
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@ -967,18 +986,22 @@ static int uart_tiocmget(struct tty_struct *tty)
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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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struct uart_port *uport = state->uart_port;
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struct uart_port *uport;
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int result = -EIO;
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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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goto out;
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if (!tty_io_error(tty)) {
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result = uport->mctrl;
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spin_lock_irq(&uport->lock);
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result |= uport->ops->get_mctrl(uport);
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spin_unlock_irq(&uport->lock);
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}
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out:
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mutex_unlock(&port->mutex);
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return result;
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}
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@ -986,15 +1009,20 @@ static int
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uart_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
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{
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struct uart_state *state = tty->driver_data;
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struct uart_port *uport = state->uart_port;
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struct tty_port *port = &state->port;
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struct uart_port *uport;
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int ret = -EIO;
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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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goto out;
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if (!tty_io_error(tty)) {
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uart_update_mctrl(uport, set, clear);
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ret = 0;
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}
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out:
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mutex_unlock(&port->mutex);
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return ret;
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}
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@ -1003,21 +1031,26 @@ static int uart_break_ctl(struct tty_struct *tty, int break_state)
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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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struct uart_port *uport = state->uart_port;
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struct uart_port *uport;
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int ret = -EIO;
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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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goto out;
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if (uport->type != PORT_UNKNOWN)
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uport->ops->break_ctl(uport, break_state);
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ret = 0;
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out:
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mutex_unlock(&port->mutex);
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return 0;
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return ret;
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}
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static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state)
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{
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struct uart_port *uport = state->uart_port;
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struct tty_port *port = &state->port;
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struct uart_port *uport;
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int flags, ret;
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if (!capable(CAP_SYS_ADMIN))
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@ -1031,6 +1064,12 @@ static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state)
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if (mutex_lock_interruptible(&port->mutex))
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return -ERESTARTSYS;
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uport = uart_port_check(state);
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if (!uport) {
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ret = -EIO;
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goto out;
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}
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ret = -EBUSY;
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if (tty_port_users(port) == 1) {
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uart_shutdown(tty, state);
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@ -1054,6 +1093,7 @@ static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state)
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ret = uart_startup(tty, state, 1);
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}
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out:
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mutex_unlock(&port->mutex);
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return ret;
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}
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@ -1202,11 +1242,11 @@ static int uart_set_rs485_config(struct uart_port *port,
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* Called via sys_ioctl. We can use spin_lock_irq() here.
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*/
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static int
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uart_ioctl(struct tty_struct *tty, unsigned int cmd,
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unsigned long arg)
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uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
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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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struct uart_port *uport;
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void __user *uarg = (void __user *)arg;
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int ret = -ENOIOCTLCMD;
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@ -1258,8 +1298,9 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd,
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goto out;
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mutex_lock(&port->mutex);
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uport = uart_port_check(state);
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if (tty_io_error(tty)) {
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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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}
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@ -1275,19 +1316,17 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd,
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break;
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case TIOCGRS485:
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ret = uart_get_rs485_config(state->uart_port, uarg);
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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(state->uart_port, uarg);
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ret = uart_set_rs485_config(uport, uarg);
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break;
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default: {
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struct uart_port *uport = state->uart_port;
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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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out_up:
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mutex_unlock(&port->mutex);
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out:
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@ -1297,24 +1336,29 @@ out:
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static void uart_set_ldisc(struct tty_struct *tty)
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{
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struct uart_state *state = tty->driver_data;
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport;
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if (uport->ops->set_ldisc) {
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mutex_lock(&state->port.mutex);
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mutex_lock(&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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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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struct ktermios *old_termios)
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{
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struct uart_state *state = tty->driver_data;
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport;
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unsigned int cflag = tty->termios.c_cflag;
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unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
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bool sw_changed = false;
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mutex_lock(&state->port.mutex);
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uport = uart_port_check(state);
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if (!uport)
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goto out;
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/*
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* Drivers doing software flow control also need to know
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* about changes to these input settings.
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@ -1337,12 +1381,10 @@ static void uart_set_termios(struct tty_struct *tty,
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tty->termios.c_ispeed == old_termios->c_ispeed &&
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((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
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!sw_changed) {
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return;
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goto out;
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}
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mutex_lock(&state->port.mutex);
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uart_change_speed(tty, state, old_termios);
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mutex_unlock(&state->port.mutex);
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/* reload cflag from termios; port driver may have overriden flags */
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cflag = tty->termios.c_cflag;
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@ -1356,6 +1398,8 @@ static void uart_set_termios(struct tty_struct *tty,
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mask |= TIOCM_RTS;
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uart_set_mctrl(uport, mask);
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}
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out:
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mutex_unlock(&state->port.mutex);
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}
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/*
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@ -1522,7 +1566,7 @@ static void uart_hangup(struct tty_struct *tty)
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static void uart_port_shutdown(struct tty_port *port)
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{
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struct uart_state *state = container_of(port, struct uart_state, port);
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport = uart_port_check(state);
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/*
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* clear delta_msr_wait queue to avoid mem leaks: we may free
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@ -1585,6 +1629,7 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
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int retval, line = tty->index;
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struct uart_state *state = drv->state + line;
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struct tty_port *port = &state->port;
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struct uart_port *uport;
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pr_debug("uart_open(%d) called\n", line);
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@ -1604,15 +1649,15 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
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goto end;
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}
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if (!state->uart_port || state->uart_port->flags & UPF_DEAD) {
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uport = uart_port_check(state);
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if (!uport || uport->flags & UPF_DEAD) {
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retval = -ENXIO;
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goto err_unlock;
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}
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|
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tty->driver_data = state;
|
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state->uart_port->state = state;
|
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state->port.low_latency =
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(state->uart_port->flags & UPF_LOW_LATENCY) ? 1 : 0;
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uport->state = state;
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port->low_latency = (uport->flags & UPF_LOW_LATENCY) ? 1 : 0;
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tty_port_tty_set(port, tty);
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/*
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|
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@ -1651,13 +1696,15 @@ static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
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struct uart_state *state = drv->state + i;
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struct tty_port *port = &state->port;
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enum uart_pm_state pm_state;
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struct uart_port *uport = state->uart_port;
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struct uart_port *uport;
|
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char stat_buf[32];
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unsigned int status;
|
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int mmio;
|
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|
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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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return;
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goto out;
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|
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mmio = uport->iotype >= UPIO_MEM;
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seq_printf(m, "%d: uart:%s %s%08llX irq:%d",
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@ -1669,11 +1716,10 @@ static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
|
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|
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if (uport->type == PORT_UNKNOWN) {
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seq_putc(m, '\n');
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return;
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goto out;
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}
|
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|
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if (capable(CAP_SYS_ADMIN)) {
|
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mutex_lock(&port->mutex);
|
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pm_state = state->pm_state;
|
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if (pm_state != UART_PM_STATE_ON)
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uart_change_pm(state, UART_PM_STATE_ON);
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|
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@ -1682,7 +1728,6 @@ static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
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spin_unlock_irq(&uport->lock);
|
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if (pm_state != UART_PM_STATE_ON)
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uart_change_pm(state, pm_state);
|
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mutex_unlock(&port->mutex);
|
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|
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seq_printf(m, " tx:%d rx:%d",
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uport->icount.tx, uport->icount.rx);
|
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|
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@ -1720,6 +1765,8 @@ static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
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seq_putc(m, '\n');
|
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#undef STATBIT
|
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#undef INFOBIT
|
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out:
|
||||
mutex_unlock(&port->mutex);
|
||||
}
|
||||
|
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static int uart_proc_show(struct seq_file *m, void *v)
|
||||
|
|
@ -1956,10 +2003,10 @@ EXPORT_SYMBOL_GPL(uart_set_options);
|
|||
static void uart_change_pm(struct uart_state *state,
|
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enum uart_pm_state pm_state)
|
||||
{
|
||||
struct uart_port *port = state->uart_port;
|
||||
struct uart_port *port = uart_port_check(state);
|
||||
|
||||
if (state->pm_state != pm_state) {
|
||||
if (port->ops->pm)
|
||||
if (port && port->ops->pm)
|
||||
port->ops->pm(port, pm_state, state->pm_state);
|
||||
state->pm_state = pm_state;
|
||||
}
|
||||
|
|
@ -2244,8 +2291,8 @@ static int uart_poll_init(struct tty_driver *driver, int line, char *options)
|
|||
tport = &state->port;
|
||||
mutex_lock(&tport->mutex);
|
||||
|
||||
port = state->uart_port;
|
||||
if (!(port->ops->poll_get_char && port->ops->poll_put_char)) {
|
||||
port = uart_port_check(state);
|
||||
if (!port || !(port->ops->poll_get_char && port->ops->poll_put_char)) {
|
||||
ret = -1;
|
||||
goto out;
|
||||
}
|
||||
|
|
@ -2713,15 +2760,12 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
|
|||
{
|
||||
struct uart_state *state = drv->state + uport->line;
|
||||
struct tty_port *port = &state->port;
|
||||
struct uart_port *uart_port;
|
||||
struct tty_struct *tty;
|
||||
int ret = 0;
|
||||
|
||||
BUG_ON(in_interrupt());
|
||||
|
||||
if (state->uart_port != uport)
|
||||
dev_alert(uport->dev, "Removing wrong port: %p != %p\n",
|
||||
state->uart_port, uport);
|
||||
|
||||
mutex_lock(&port_mutex);
|
||||
|
||||
/*
|
||||
|
|
@ -2729,7 +2773,12 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
|
|||
* succeeding while we shut down the port.
|
||||
*/
|
||||
mutex_lock(&port->mutex);
|
||||
if (!state->uart_port) {
|
||||
uart_port = uart_port_check(state);
|
||||
if (uart_port != uport)
|
||||
dev_alert(uport->dev, "Removing wrong port: %p != %p\n",
|
||||
uart_port, uport);
|
||||
|
||||
if (!uart_port) {
|
||||
mutex_unlock(&port->mutex);
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
|
|
@ -2766,7 +2815,9 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
|
|||
*/
|
||||
uport->type = PORT_UNKNOWN;
|
||||
|
||||
mutex_lock(&port->mutex);
|
||||
state->uart_port = NULL;
|
||||
mutex_unlock(&port->mutex);
|
||||
out:
|
||||
mutex_unlock(&port_mutex);
|
||||
|
||||
|
|
|
|||
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