tty: serial - fix various misuses/mishandlings of port->tty

Make it robust against hang up events. In most cases we can do this simply
by passing the right things in the first place.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 7f28307095121766d685350dad865e72f7d312c2..12ee7e0f99cea40480ccfc5104b2326f4cfaf0bf 100644 (file)
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -58,7 +58,7 @@ static struct lock_class_key port_lock_key;
 #define uart_console(port)     (0)
 #endif
 
-static void uart_change_speed(struct uart_state *state,
+static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
                                        struct ktermios *old_termios);
 static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
 static void uart_change_pm(struct uart_state *state, int pm_state);
@@ -137,7 +137,7 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
  * Startup the port.  This will be called once per open.  All calls
  * will be serialised by the per-port mutex.
  */
-static int uart_startup(struct uart_state *state, int init_hw)
+static int uart_startup(struct tty_struct *tty, struct uart_state *state, int init_hw)
 {
        struct uart_port *uport = state->uart_port;
        struct tty_port *port = &state->port;
@@ -152,7 +152,7 @@ static int uart_startup(struct uart_state *state, int init_hw)
         * once we have successfully opened the port.  Also set
         * up the tty->alt_speed kludge
         */
-       set_bit(TTY_IO_ERROR, &port->tty->flags);
+       set_bit(TTY_IO_ERROR, &tty->flags);
 
        if (uport->type == PORT_UNKNOWN)
                return 0;
@@ -177,26 +177,26 @@ static int uart_startup(struct uart_state *state, int init_hw)
                        /*
                         * Initialise the hardware port settings.
                         */
-                       uart_change_speed(state, NULL);
+                       uart_change_speed(tty, state, NULL);
 
                        /*
                         * Setup the RTS and DTR signals once the
                         * port is open and ready to respond.
                         */
-                       if (port->tty->termios->c_cflag & CBAUD)
+                       if (tty->termios->c_cflag & CBAUD)
                                uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
                }
 
                if (port->flags & ASYNC_CTS_FLOW) {
                        spin_lock_irq(&uport->lock);
                        if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS))
-                               port->tty->hw_stopped = 1;
+                               tty->hw_stopped = 1;
                        spin_unlock_irq(&uport->lock);
                }
 
                set_bit(ASYNCB_INITIALIZED, &port->flags);
 
-               clear_bit(TTY_IO_ERROR, &port->tty->flags);
+               clear_bit(TTY_IO_ERROR, &tty->flags);
        }
 
        if (retval && capable(CAP_SYS_ADMIN))
@@ -210,11 +210,10 @@ static int uart_startup(struct uart_state *state, int init_hw)
  * DTR is dropped if the hangup on close termio flag is on.  Calls to
  * uart_shutdown are serialised by the per-port semaphore.
  */
-static void uart_shutdown(struct uart_state *state)
+static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
 {
        struct uart_port *uport = state->uart_port;
        struct tty_port *port = &state->port;
-       struct tty_struct *tty = port->tty;
 
        /*
         * Set the TTY IO error marker
@@ -430,11 +429,10 @@ uart_get_divisor(struct uart_port *port, unsigned int baud)
 EXPORT_SYMBOL(uart_get_divisor);
 
 /* FIXME: Consistent locking policy */
-static void
-uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
+static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
+                                       struct ktermios *old_termios)
 {
        struct tty_port *port = &state->port;
-       struct tty_struct *tty = port->tty;
        struct uart_port *uport = state->uart_port;
        struct ktermios *termios;
 
@@ -463,8 +461,8 @@ uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
        uport->ops->set_termios(uport, termios, old_termios);
 }
 
-static inline int
-__uart_put_char(struct uart_port *port, struct circ_buf *circ, unsigned char c)
+static inline int __uart_put_char(struct uart_port *port,
+                               struct circ_buf *circ, unsigned char c)
 {
        unsigned long flags;
        int ret = 0;
@@ -494,8 +492,8 @@ static void uart_flush_chars(struct tty_struct *tty)
        uart_start(tty);
 }
 
-static int
-uart_write(struct tty_struct *tty, const unsigned char *buf, int count)
+static int uart_write(struct tty_struct *tty,
+                                       const unsigned char *buf, int count)
 {
        struct uart_state *state = tty->driver_data;
        struct uart_port *port;
@@ -675,7 +673,7 @@ static int uart_get_info(struct uart_state *state,
        return 0;
 }
 
-static int uart_set_info(struct uart_state *state,
+static int uart_set_info(struct tty_struct *tty, struct uart_state *state,
                         struct serial_struct __user *newinfo)
 {
        struct serial_struct new_serial;
@@ -770,7 +768,7 @@ static int uart_set_info(struct uart_state *state,
                 * We need to shutdown the serial port at the old
                 * port/type/irq combination.
                 */
-               uart_shutdown(state);
+               uart_shutdown(tty, state);
        }
 
        if (change_port) {
@@ -869,25 +867,27 @@ static int uart_set_info(struct uart_state *state,
                                       "is deprecated.\n", current->comm,
                                       tty_name(port->tty, buf));
                        }
-                       uart_change_speed(state, NULL);
+                       uart_change_speed(tty, state, NULL);
                }
        } else
-               retval = uart_startup(state, 1);
+               retval = uart_startup(tty, state, 1);
  exit:
        mutex_unlock(&port->mutex);
        return retval;
 }
 
-
-/*
- * uart_get_lsr_info - get line status register info.
- * Note: uart_ioctl protects us against hangups.
+/**
+ *     uart_get_lsr_info       -       get line status register info
+ *     @tty: tty associated with the UART
+ *     @state: UART being queried
+ *     @value: returned modem value
+ *
+ *     Note: uart_ioctl protects us against hangups.
  */
-static int uart_get_lsr_info(struct uart_state *state,
-                            unsigned int __user *value)
+static int uart_get_lsr_info(struct tty_struct *tty,
+                       struct uart_state *state, unsigned int __user *value)
 {
        struct uart_port *uport = state->uart_port;
-       struct tty_port *port = &state->port;
        unsigned int result;
 
        result = uport->ops->tx_empty(uport);
@@ -900,7 +900,7 @@ static int uart_get_lsr_info(struct uart_state *state,
         */
        if (uport->x_char ||
            ((uart_circ_chars_pending(&state->xmit) > 0) &&
-            !port->tty->stopped && !port->tty->hw_stopped))
+            !tty->stopped && !tty->hw_stopped))
                result &= ~TIOCSER_TEMT;
 
        return put_user(result, value);
@@ -961,7 +961,7 @@ static int uart_break_ctl(struct tty_struct *tty, int break_state)
        return 0;
 }
 
-static int uart_do_autoconfig(struct uart_state *state)
+static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state)
 {
        struct uart_port *uport = state->uart_port;
        struct tty_port *port = &state->port;
@@ -980,7 +980,7 @@ static int uart_do_autoconfig(struct uart_state *state)
 
        ret = -EBUSY;
        if (tty_port_users(port) == 1) {
-               uart_shutdown(state);
+               uart_shutdown(tty, state);
 
                /*
                 * If we already have a port type configured,
@@ -999,7 +999,7 @@ static int uart_do_autoconfig(struct uart_state *state)
                 */
                uport->ops->config_port(uport, flags);
 
-               ret = uart_startup(state, 1);
+               ret = uart_startup(tty, state, 1);
        }
        mutex_unlock(&port->mutex);
        return ret;
@@ -1122,11 +1122,11 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
                break;
 
        case TIOCSSERIAL:
-               ret = uart_set_info(state, uarg);
+               ret = uart_set_info(tty, state, uarg);
                break;
 
        case TIOCSERCONFIG:
-               ret = uart_do_autoconfig(state);
+               ret = uart_do_autoconfig(tty, state);
                break;
 
        case TIOCSERGWILD: /* obsolete */
@@ -1172,7 +1172,7 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
         */
        switch (cmd) {
        case TIOCSERGETLSR: /* Get line status register */
-               ret = uart_get_lsr_info(state, uarg);
+               ret = uart_get_lsr_info(tty, state, uarg);
                break;
 
        default: {
@@ -1219,7 +1219,7 @@ static void uart_set_termios(struct tty_struct *tty,
                return;
        }
 
-       uart_change_speed(state, old_termios);
+       uart_change_speed(tty, state, old_termios);
 
        /* Handle transition to B0 status */
        if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
@@ -1335,7 +1335,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
                uart_wait_until_sent(tty, uport->timeout);
        }
 
-       uart_shutdown(state);
+       uart_shutdown(tty, state);
        uart_flush_buffer(tty);
 
        tty_ldisc_flush(tty);
@@ -1436,7 +1436,7 @@ static void uart_hangup(struct tty_struct *tty)
        mutex_lock(&port->mutex);
        if (port->flags & ASYNC_NORMAL_ACTIVE) {
                uart_flush_buffer(tty);
-               uart_shutdown(state);
+               uart_shutdown(tty, state);
                port->count = 0;
                clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
                tty_port_tty_set(port, NULL);
@@ -1446,15 +1446,19 @@ static void uart_hangup(struct tty_struct *tty)
        mutex_unlock(&port->mutex);
 }
 
-/*
- * Copy across the serial console cflag setting into the termios settings
- * for the initial open of the port.  This allows continuity between the
- * kernel settings, and the settings init adopts when it opens the port
- * for the first time.
+/**
+ *     uart_update_termios     -       update the terminal hw settings
+ *     @tty: tty associated with UART
+ *     @state: UART to update
+ *
+ *     Copy across the serial console cflag setting into the termios settings
+ *     for the initial open of the port.  This allows continuity between the
+ *     kernel settings, and the settings init adopts when it opens the port
+ *     for the first time.
  */
-static void uart_update_termios(struct uart_state *state)
+static void uart_update_termios(struct tty_struct *tty,
+                                               struct uart_state *state)
 {
-       struct tty_struct *tty = state->port.tty;
        struct uart_port *port = state->uart_port;
 
        if (uart_console(port) && port->cons->cflag) {
@@ -1471,7 +1475,7 @@ static void uart_update_termios(struct uart_state *state)
                /*
                 * Make termios settings take effect.
                 */
-               uart_change_speed(state, NULL);
+               uart_change_speed(tty, state, NULL);
 
                /*
                 * And finally enable the RTS and DTR signals.
@@ -1668,7 +1672,7 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
        /*
         * Start up the serial port.
         */
-       retval = uart_startup(state, 0);
+       retval = uart_startup(tty, state, 0);
 
        /*
         * If we succeeded, wait until the port is ready.
@@ -1683,7 +1687,7 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
        if (retval == 0 && !(port->flags & ASYNC_NORMAL_ACTIVE)) {
                set_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
 
-               uart_update_termios(state);
+               uart_update_termios(tty, state);
        }
 
 fail:
@@ -2010,9 +2014,13 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
        struct tty_port *port = &state->port;
        struct device *tty_dev;
        struct uart_match match = {uport, drv};
+       struct tty_struct *tty;
 
        mutex_lock(&port->mutex);
 
+       /* Must be inside the mutex lock until we convert to tty_port */
+       tty = port->tty;
+
        tty_dev = device_find_child(uport->dev, &match, serial_match_port);
        if (device_may_wakeup(tty_dev)) {
                enable_irq_wake(uport->irq);
@@ -2105,9 +2113,12 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
                ops->set_mctrl(uport, 0);
                spin_unlock_irq(&uport->lock);
                if (console_suspend_enabled || !uart_console(uport)) {
+                       /* Protected by port mutex for now */
+                       struct tty_struct *tty = port->tty;
                        ret = ops->startup(uport);
                        if (ret == 0) {
-                               uart_change_speed(state, NULL);
+                               if (tty)
+                                       uart_change_speed(tty, state, NULL);
                                spin_lock_irq(&uport->lock);
                                ops->set_mctrl(uport, uport->mctrl);
                                ops->start_tx(uport);
@@ -2119,7 +2130,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
                                 * Clear the "initialized" flag so we won't try
                                 * to call the low level drivers shutdown method.
                                 */
-                               uart_shutdown(state);
+                               uart_shutdown(tty, state);
                        }
                }