mxser: Switch to kref tty

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 103 insertions, 89 deletions

diff --git a/drivers/char/mxser.c b/drivers/char/mxser.c
index b638403e8e9c..308cb6014002 100644
--- a/drivers/char/mxser.c
+++ b/drivers/char/mxser.c
@@ -610,15 +610,16 @@ static int mxser_block_til_ready(struct tty_struct *tty, struct file *filp,
         return 0;
 }
 
-static int mxser_set_baud(struct mxser_port *info, long newspd)
+static int mxser_set_baud(struct tty_struct *tty, long newspd)
 {
+        struct mxser_port *info = tty->driver_data;
         int quot = 0, baud;
         unsigned char cval;
 
-        if (!info->port.tty || !info->port.tty->termios)
+        if (!tty->termios)
                 return -1;
 
-        if (!(info->ioaddr))
+        if (!info->ioaddr)
                 return -1;
 
         if (newspd > info->max_baud)
@@ -626,13 +627,13 @@ static int mxser_set_baud(struct mxser_port *info, long newspd)
 
         if (newspd == 134) {
                 quot = 2 * info->baud_base / 269;
-                tty_encode_baud_rate(info->port.tty, 134, 134);
+                tty_encode_baud_rate(tty, 134, 134);
         } else if (newspd) {
                 quot = info->baud_base / newspd;
                 if (quot == 0)
                         quot = 1;
                 baud = info->baud_base/quot;
-                tty_encode_baud_rate(info->port.tty, baud, baud);
+                tty_encode_baud_rate(tty, baud, baud);
         } else {
                 quot = 0;
         }
@@ -658,7 +659,7 @@ static int mxser_set_baud(struct mxser_port *info, long newspd)
         outb(cval, info->ioaddr + UART_LCR);    /* reset DLAB */
 
 #ifdef BOTHER
-        if (C_BAUD(info->port.tty) == BOTHER) {
+        if (C_BAUD(tty) == BOTHER) {
                 quot = info->baud_base % newspd;
                 quot *= 8;
                 if (quot % newspd > newspd / 2) {
@@ -679,21 +680,22 @@ static int mxser_set_baud(struct mxser_port *info, long newspd)
  * This routine is called to set the UART divisor registers to match
  * the specified baud rate for a serial port.
  */
-static int mxser_change_speed(struct mxser_port *info,
-                struct ktermios *old_termios)
+static int mxser_change_speed(struct tty_struct *tty,
+                                        struct ktermios *old_termios)
 {
+        struct mxser_port *info = tty->driver_data;
         unsigned cflag, cval, fcr;
         int ret = 0;
         unsigned char status;
 
-        if (!info->port.tty || !info->port.tty->termios)
+        if (!tty->termios)
                 return ret;
-        cflag = info->port.tty->termios->c_cflag;
-        if (!(info->ioaddr))
+        cflag = tty->termios->c_cflag;
+        if (!info->ioaddr)
                 return ret;
 
-        if (mxser_set_baud_method[info->port.tty->index] == 0)
-                mxser_set_baud(info, tty_get_baud_rate(info->port.tty));
+        if (mxser_set_baud_method[tty->index] == 0)
+                mxser_set_baud(tty, tty_get_baud_rate(tty));
 
         /* byte size and parity */
         switch (cflag & CSIZE) {
@@ -762,9 +764,9 @@ static int mxser_change_speed(struct mxser_port *info,
                         info->MCR |= UART_MCR_AFE;
                 } else {
                         status = inb(info->ioaddr + UART_MSR);
-                        if (info->port.tty->hw_stopped) {
+                        if (tty->hw_stopped) {
                                 if (status & UART_MSR_CTS) {
-                                        info->port.tty->hw_stopped = 0;
+                                        tty->hw_stopped = 0;
                                         if (info->type != PORT_16550A &&
                                                         !info->board->chip_flag) {
                                                 outb(info->IER & ~UART_IER_THRI,
@@ -774,11 +776,11 @@ static int mxser_change_speed(struct mxser_port *info,
                                                 outb(info->IER, info->ioaddr +
                                                                 UART_IER);
                                         }
-                                        tty_wakeup(info->port.tty);
+                                        tty_wakeup(tty);
                                 }
                         } else {
                                 if (!(status & UART_MSR_CTS)) {
-                                        info->port.tty->hw_stopped = 1;
+                                        tty->hw_stopped = 1;
                                         if ((info->type != PORT_16550A) &&
                                                         (!info->board->chip_flag)) {
                                                 info->IER &= ~UART_IER_THRI;
@@ -804,21 +806,21 @@ static int mxser_change_speed(struct mxser_port *info,
          * Set up parity check flag
          */
         info->read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
-        if (I_INPCK(info->port.tty))
+        if (I_INPCK(tty))
                 info->read_status_mask |= UART_LSR_FE | UART_LSR_PE;
-        if (I_BRKINT(info->port.tty) || I_PARMRK(info->port.tty))
+        if (I_BRKINT(tty) || I_PARMRK(tty))
                 info->read_status_mask |= UART_LSR_BI;
 
         info->ignore_status_mask = 0;
 
-        if (I_IGNBRK(info->port.tty)) {
+        if (I_IGNBRK(tty)) {
                 info->ignore_status_mask |= UART_LSR_BI;
                 info->read_status_mask |= UART_LSR_BI;
                 /*
                  * If we're ignore parity and break indicators, ignore
                  * overruns too.  (For real raw support).
                  */
-                if (I_IGNPAR(info->port.tty)) {
+                if (I_IGNPAR(tty)) {
                         info->ignore_status_mask |=
                                                 UART_LSR_OE |
                                                 UART_LSR_PE |
@@ -830,16 +832,16 @@ static int mxser_change_speed(struct mxser_port *info,
                 }
         }
         if (info->board->chip_flag) {
-                mxser_set_must_xon1_value(info->ioaddr, START_CHAR(info->port.tty));
-                mxser_set_must_xoff1_value(info->ioaddr, STOP_CHAR(info->port.tty));
-                if (I_IXON(info->port.tty)) {
+                mxser_set_must_xon1_value(info->ioaddr, START_CHAR(tty));
+                mxser_set_must_xoff1_value(info->ioaddr, STOP_CHAR(tty));
+                if (I_IXON(tty)) {
                         mxser_enable_must_rx_software_flow_control(
                                         info->ioaddr);
                 } else {
                         mxser_disable_must_rx_software_flow_control(
                                         info->ioaddr);
                 }
-                if (I_IXOFF(info->port.tty)) {
+                if (I_IXOFF(tty)) {
                         mxser_enable_must_tx_software_flow_control(
                                         info->ioaddr);
                 } else {
@@ -855,7 +857,8 @@ static int mxser_change_speed(struct mxser_port *info,
         return ret;
 }
 
-static void mxser_check_modem_status(struct mxser_port *port, int status)
+static void mxser_check_modem_status(struct tty_struct *tty,
+                                struct mxser_port *port, int status)
 {
         /* update input line counters */
         if (status & UART_MSR_TERI)
@@ -874,10 +877,11 @@ static void mxser_check_modem_status(struct mxser_port *port, int status)
                         wake_up_interruptible(&port->port.open_wait);
         }
 
+        tty = tty_port_tty_get(&port->port);
         if (port->port.flags & ASYNC_CTS_FLOW) {
-                if (port->port.tty->hw_stopped) {
+                if (tty->hw_stopped) {
                         if (status & UART_MSR_CTS) {
-                                port->port.tty->hw_stopped = 0;
+                                tty->hw_stopped = 0;
 
                                 if ((port->type != PORT_16550A) &&
                                                 (!port->board->chip_flag)) {
@@ -887,11 +891,11 @@ static void mxser_check_modem_status(struct mxser_port *port, int status)
                                         outb(port->IER, port->ioaddr +
                                                         UART_IER);
                                 }
-                                tty_wakeup(port->port.tty);
+                                tty_wakeup(tty);
                         }
                 } else {
                         if (!(status & UART_MSR_CTS)) {
-                                port->port.tty->hw_stopped = 1;
+                                tty->hw_stopped = 1;
                                 if (port->type != PORT_16550A &&
                                                 !port->board->chip_flag) {
                                         port->IER &= ~UART_IER_THRI;
@@ -903,8 +907,9 @@ static void mxser_check_modem_status(struct mxser_port *port, int status)
         }
 }
 
-static int mxser_startup(struct mxser_port *info)
+static int mxser_startup(struct tty_struct *tty)
 {
+        struct mxser_port *info = tty->driver_data;
         unsigned long page;
         unsigned long flags;
 
@@ -921,8 +926,7 @@ static int mxser_startup(struct mxser_port *info)
         }
 
         if (!info->ioaddr || !info->type) {
-                if (info->port.tty)
-                        set_bit(TTY_IO_ERROR, &info->port.tty->flags);
+                set_bit(TTY_IO_ERROR, &tty->flags);
                 free_page(page);
                 spin_unlock_irqrestore(&info->slock, flags);
                 return 0;
@@ -952,8 +956,8 @@ static int mxser_startup(struct mxser_port *info)
         if (inb(info->ioaddr + UART_LSR) == 0xff) {
                 spin_unlock_irqrestore(&info->slock, flags);
                 if (capable(CAP_SYS_ADMIN)) {
-                        if (info->port.tty)
-                                set_bit(TTY_IO_ERROR, &info->port.tty->flags);
+                        if (tty)
+                                set_bit(TTY_IO_ERROR, &tty->flags);
                         return 0;
                 } else
                         return -ENODEV;
@@ -991,14 +995,13 @@ static int mxser_startup(struct mxser_port *info)
         (void) inb(info->ioaddr + UART_IIR);
         (void) inb(info->ioaddr + UART_MSR);
 
-        if (info->port.tty)
-                clear_bit(TTY_IO_ERROR, &info->port.tty->flags);
+        clear_bit(TTY_IO_ERROR, &tty->flags);
         info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
 
         /*
          * and set the speed of the serial port
          */
-        mxser_change_speed(info, NULL);
+        mxser_change_speed(tty, NULL);
         info->port.flags |= ASYNC_INITIALIZED;
         spin_unlock_irqrestore(&info->slock, flags);
 
@@ -1009,8 +1012,9 @@ static int mxser_startup(struct mxser_port *info)
  * This routine will shutdown a serial port; interrupts maybe disabled, and
  * DTR is dropped if the hangup on close termio flag is on.
  */
-static void mxser_shutdown(struct mxser_port *info)
+static void mxser_shutdown(struct tty_struct *tty)
 {
+        struct mxser_port *info = tty->driver_data;
         unsigned long flags;
 
         if (!(info->port.flags & ASYNC_INITIALIZED))
@@ -1035,7 +1039,7 @@ static void mxser_shutdown(struct mxser_port *info)
         info->IER = 0;
         outb(0x00, info->ioaddr + UART_IER);
 
-        if (!info->port.tty || (info->port.tty->termios->c_cflag & HUPCL))
+        if (tty->termios->c_cflag & HUPCL)
                 info->MCR &= ~(UART_MCR_DTR | UART_MCR_RTS);
         outb(info->MCR, info->ioaddr + UART_MCR);
 
@@ -1051,8 +1055,7 @@ static void mxser_shutdown(struct mxser_port *info)
         /* read data port to reset things */
         (void) inb(info->ioaddr + UART_RX);
 
-        if (info->port.tty)
-                set_bit(TTY_IO_ERROR, &info->port.tty->flags);
+        set_bit(TTY_IO_ERROR, &tty->flags);
 
         info->port.flags &= ~ASYNC_INITIALIZED;
 
@@ -1084,14 +1087,14 @@ static int mxser_open(struct tty_struct *tty, struct file *filp)
                 return -ENODEV;
 
         tty->driver_data = info;
-        info->port.tty = tty;
+        tty_port_tty_set(&info->port, tty);
         /*
          * Start up serial port
          */
         spin_lock_irqsave(&info->slock, flags);
         info->port.count++;
         spin_unlock_irqrestore(&info->slock, flags);
-        retval = mxser_startup(info);
+        retval = mxser_startup(tty);
         if (retval)
                 return retval;
 
@@ -1209,13 +1212,13 @@ static void mxser_close(struct tty_struct *tty, struct file *filp)
                                 break;
                 }
         }
-        mxser_shutdown(info);
+        mxser_shutdown(tty);
 
         mxser_flush_buffer(tty);
         tty_ldisc_flush(tty);
 
         tty->closing = 0;
-        info->port.tty = NULL;
+        tty_port_tty_set(&info->port, NULL);
         if (info->port.blocked_open) {
                 if (info->port.close_delay)
                         schedule_timeout_interruptible(info->port.close_delay);
@@ -1337,12 +1340,13 @@ static int mxser_chars_in_buffer(struct tty_struct *tty)
  * friends of mxser_ioctl()
  * ------------------------------------------------------------
  */
-static int mxser_get_serial_info(struct mxser_port *info,
+static int mxser_get_serial_info(struct tty_struct *tty,
                 struct serial_struct __user *retinfo)
 {
+        struct mxser_port *info = tty->driver_data;
         struct serial_struct tmp = {
                 .type = info->type,
-                .line = info->port.tty->index,
+                .line = tty->index,
                 .port = info->ioaddr,
                 .irq = info->board->irq,
                 .flags = info->port.flags,
@@ -1357,9 +1361,10 @@ static int mxser_get_serial_info(struct mxser_port *info,
         return 0;
 }
 
-static int mxser_set_serial_info(struct mxser_port *info,
+static int mxser_set_serial_info(struct tty_struct *tty,
                 struct serial_struct __user *new_info)
 {
+        struct mxser_port *info = tty->driver_data;
         struct serial_struct new_serial;
         speed_t baud;
         unsigned long sl_flags;
@@ -1393,14 +1398,14 @@ static int mxser_set_serial_info(struct mxser_port *info,
                                 (new_serial.flags & ASYNC_FLAGS));
                 info->port.close_delay = new_serial.close_delay * HZ / 100;
                 info->port.closing_wait = new_serial.closing_wait * HZ / 100;
-                info->port.tty->low_latency =
-                                (info->port.flags & ASYNC_LOW_LATENCY) ? 1 : 0;
+                tty->low_latency = (info->port.flags & ASYNC_LOW_LATENCY)
+                                                                ? 1 : 0;
                 if ((info->port.flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST &&
                                 (new_serial.baud_base != info->baud_base ||
                                 new_serial.custom_divisor !=
                                 info->custom_divisor)) {
                         baud = new_serial.baud_base / new_serial.custom_divisor;
-                        tty_encode_baud_rate(info->port.tty, baud, baud);
+                        tty_encode_baud_rate(tty, baud, baud);
                 }
         }
 
@@ -1411,11 +1416,11 @@ static int mxser_set_serial_info(struct mxser_port *info,
         if (info->port.flags & ASYNC_INITIALIZED) {
                 if (flags != (info->port.flags & ASYNC_SPD_MASK)) {
                         spin_lock_irqsave(&info->slock, sl_flags);
-                        mxser_change_speed(info, NULL);
+                        mxser_change_speed(tty, NULL);
                         spin_unlock_irqrestore(&info->slock, sl_flags);
                 }
         } else
-                retval = mxser_startup(info);
+                retval = mxser_startup(tty);
 
         return retval;
 }
@@ -1461,7 +1466,7 @@ static int mxser_tiocmget(struct tty_struct *tty, struct file *file)
         spin_lock_irqsave(&info->slock, flags);
         status = inb(info->ioaddr + UART_MSR);
         if (status & UART_MSR_ANY_DELTA)
-                mxser_check_modem_status(info, status);
+                mxser_check_modem_status(tty, info, status);
         spin_unlock_irqrestore(&info->slock, flags);
         return ((control & UART_MCR_RTS) ? TIOCM_RTS : 0) |
                     ((control & UART_MCR_DTR) ? TIOCM_DTR : 0) |
@@ -1606,6 +1611,7 @@ static int __init mxser_read_register(int port, unsigned short *regs)
 static int mxser_ioctl_special(unsigned int cmd, void __user *argp)
 {
         struct mxser_port *port;
+        struct tty_struct *tty;
         int result, status;
         unsigned int i, j;
         int ret = 0;
@@ -1643,12 +1649,14 @@ static int mxser_ioctl_special(unsigned int cmd, void __user *argp)
 
                                 if (!port->ioaddr)
                                         goto copy;
+                                
+                                tty = tty_port_tty_get(&port->port);
 
-                                if (!port->port.tty || !port->port.tty->termios)
+                                if (!tty || !tty->termios)
                                         ms.cflag = port->normal_termios.c_cflag;
                                 else
-                                        ms.cflag = port->port.tty->termios->c_cflag;
-
+                                        ms.cflag = tty->termios->c_cflag;
+                                tty_kref_put(tty);
                                 status = inb(port->ioaddr + UART_MSR);
                                 if (status & UART_MSR_DCD)
                                         ms.dcd = 1;
@@ -1704,15 +1712,18 @@ static int mxser_ioctl_special(unsigned int cmd, void __user *argp)
                                 me->up_txcnt[p] = port->mon_data.up_txcnt;
                                 me->modem_status[p] =
                                         port->mon_data.modem_status;
-                                me->baudrate[p] = tty_get_baud_rate(port->port.tty);
+                                tty = tty_port_tty_get(&port->port);
 
-                                if (!port->port.tty || !port->port.tty->termios) {
+                                if (!tty || !tty->termios) {
                                         cflag = port->normal_termios.c_cflag;
                                         iflag = port->normal_termios.c_iflag;
+                                        me->baudrate[p] = tty_termios_baud_rate(&port->normal_termios);
                                 } else {
-                                        cflag = port->port.tty->termios->c_cflag;
-                                        iflag = port->port.tty->termios->c_iflag;
+                                        cflag = tty->termios->c_cflag;
+                                        iflag = tty->termios->c_iflag;
+                                        me->baudrate[p] = tty_get_baud_rate(tty);
                                 }
+                                tty_kref_put(tty);
 
                                 me->databits[p] = cflag & CSIZE;
                                 me->stopbits[p] = cflag & CSTOPB;
@@ -1822,12 +1833,12 @@ static int mxser_ioctl(struct tty_struct *tty, struct file *file,
         switch (cmd) {
         case TIOCGSERIAL:
                 lock_kernel();
-                retval = mxser_get_serial_info(info, argp);
+                retval = mxser_get_serial_info(tty, argp);
                 unlock_kernel();
                 return retval;
         case TIOCSSERIAL:
                 lock_kernel();
-                retval = mxser_set_serial_info(info, argp);
+                retval = mxser_set_serial_info(tty, argp);
                 unlock_kernel();
                 return retval;
         case TIOCSERGETLSR:     /* Get line status register */
@@ -1896,7 +1907,7 @@ static int mxser_ioctl(struct tty_struct *tty, struct file *file,
 
                 lock_kernel();
                 status = mxser_get_msr(info->ioaddr, 1, tty->index);
-                mxser_check_modem_status(info, status);
+                mxser_check_modem_status(tty, info, status);
 
                 mcr = inb(info->ioaddr + UART_MCR);
                 if (mcr & MOXA_MUST_MCR_XON_FLAG)
@@ -1909,7 +1920,7 @@ static int mxser_ioctl(struct tty_struct *tty, struct file *file,
                 else
                         info->mon_data.hold_reason |= NPPI_NOTIFY_XOFFXENT;
 
-                if (info->port.tty->hw_stopped)
+                if (tty->hw_stopped)
                         info->mon_data.hold_reason |= NPPI_NOTIFY_CTSHOLD;
                 else
                         info->mon_data.hold_reason &= ~NPPI_NOTIFY_CTSHOLD;
@@ -1958,7 +1969,7 @@ static void mxser_stoprx(struct tty_struct *tty)
                 }
         }
 
-        if (info->port.tty->termios->c_cflag & CRTSCTS) {
+        if (tty->termios->c_cflag & CRTSCTS) {
                 info->MCR &= ~UART_MCR_RTS;
                 outb(info->MCR, info->ioaddr + UART_MCR);
         }
@@ -1995,7 +2006,7 @@ static void mxser_unthrottle(struct tty_struct *tty)
                 }
         }
 
-        if (info->port.tty->termios->c_cflag & CRTSCTS) {
+        if (tty->termios->c_cflag & CRTSCTS) {
                 info->MCR |= UART_MCR_RTS;
                 outb(info->MCR, info->ioaddr + UART_MCR);
         }
@@ -2040,7 +2051,7 @@ static void mxser_set_termios(struct tty_struct *tty, struct ktermios *old_termi
         unsigned long flags;
 
         spin_lock_irqsave(&info->slock, flags);
-        mxser_change_speed(info, old_termios);
+        mxser_change_speed(tty, old_termios);
         spin_unlock_irqrestore(&info->slock, flags);
 
         if ((old_termios->c_cflag & CRTSCTS) &&
@@ -2138,10 +2149,10 @@ static void mxser_hangup(struct tty_struct *tty)
         struct mxser_port *info = tty->driver_data;
 
         mxser_flush_buffer(tty);
-        mxser_shutdown(info);
+        mxser_shutdown(tty);
         info->port.count = 0;
         info->port.flags &= ~ASYNC_NORMAL_ACTIVE;
-        info->port.tty = NULL;
+        tty_port_tty_set(&info->port, NULL);
         wake_up_interruptible(&info->port.open_wait);
 }
 
@@ -2164,9 +2175,9 @@ static int mxser_rs_break(struct tty_struct *tty, int break_state)
         return 0;
 }
 
-static void mxser_receive_chars(struct mxser_port *port, int *status)
+static void mxser_receive_chars(struct tty_struct *tty,
+                                struct mxser_port *port, int *status)
 {
-        struct tty_struct *tty = port->port.tty;
         unsigned char ch, gdl;
         int ignored = 0;
         int cnt = 0;
@@ -2174,9 +2185,8 @@ static void mxser_receive_chars(struct mxser_port *port, int *status)
         int max = 256;
 
         recv_room = tty->receive_room;
-        if ((recv_room == 0) && (!port->ldisc_stop_rx))
+        if (recv_room == 0 && !port->ldisc_stop_rx)
                 mxser_stoprx(tty);
-
         if (port->board->chip_flag != MOXA_OTHER_UART) {
 
                 if (*status & UART_LSR_SPECIAL)
@@ -2253,7 +2263,7 @@ intr_old:
         } while (*status & UART_LSR_DR);
 
 end_intr:
-        mxvar_log.rxcnt[port->port.tty->index] += cnt;
+        mxvar_log.rxcnt[tty->index] += cnt;
         port->mon_data.rxcnt += cnt;
         port->mon_data.up_rxcnt += cnt;
 
@@ -2267,14 +2277,14 @@ end_intr:
         spin_lock(&port->slock);
 }
 
-static void mxser_transmit_chars(struct mxser_port *port)
+static void mxser_transmit_chars(struct tty_struct *tty, struct mxser_port *port)
 {
         int count, cnt;
 
         if (port->x_char) {
                 outb(port->x_char, port->ioaddr + UART_TX);
                 port->x_char = 0;
-                mxvar_log.txcnt[port->port.tty->index]++;
+                mxvar_log.txcnt[tty->index]++;
                 port->mon_data.txcnt++;
                 port->mon_data.up_txcnt++;
                 port->icount.tx++;
@@ -2284,8 +2294,8 @@ static void mxser_transmit_chars(struct mxser_port *port)
         if (port->port.xmit_buf == NULL)
                 return;
 
-        if ((port->xmit_cnt <= 0) || port->port.tty->stopped ||
-                        (port->port.tty->hw_stopped &&
+        if (port->xmit_cnt <= 0 || tty->stopped ||
+                        (tty->hw_stopped &&
                         (port->type != PORT_16550A) &&
                         (!port->board->chip_flag))) {
                 port->IER &= ~UART_IER_THRI;
@@ -2302,14 +2312,14 @@ static void mxser_transmit_chars(struct mxser_port *port)
                 if (--port->xmit_cnt <= 0)
                         break;
         } while (--count > 0);
-        mxvar_log.txcnt[port->port.tty->index] += (cnt - port->xmit_cnt);
+        mxvar_log.txcnt[tty->index] += (cnt - port->xmit_cnt);
 
         port->mon_data.txcnt += (cnt - port->xmit_cnt);
         port->mon_data.up_txcnt += (cnt - port->xmit_cnt);
         port->icount.tx += (cnt - port->xmit_cnt);
 
-        if (port->xmit_cnt < WAKEUP_CHARS)
-                tty_wakeup(port->port.tty);
+        if (port->xmit_cnt < WAKEUP_CHARS && tty)
+                tty_wakeup(tty);
 
         if (port->xmit_cnt <= 0) {
                 port->IER &= ~UART_IER_THRI;
@@ -2328,6 +2338,7 @@ static irqreturn_t mxser_interrupt(int irq, void *dev_id)
         int max, irqbits, bits, msr;
         unsigned int int_cnt, pass_counter = 0;
         int handled = IRQ_NONE;
+        struct tty_struct *tty;
 
         for (i = 0; i < MXSER_BOARDS; i++)
                 if (dev_id == &mxser_boards[i]) {
@@ -2360,13 +2371,15 @@ static irqreturn_t mxser_interrupt(int irq, void *dev_id)
                                 if (iir & UART_IIR_NO_INT)
                                         break;
                                 iir &= MOXA_MUST_IIR_MASK;
-                                if (!port->port.tty ||
+                                tty = tty_port_tty_get(&port->port);
+                                if (!tty ||
                                                 (port->port.flags & ASYNC_CLOSING) ||
                                                 !(port->port.flags &
                                                         ASYNC_INITIALIZED)) {
                                         status = inb(port->ioaddr + UART_LSR);
                                         outb(0x27, port->ioaddr + UART_FCR);
                                         inb(port->ioaddr + UART_MSR);
+                                        tty_kref_put(tty);
                                         break;
                                 }
 
@@ -2387,27 +2400,28 @@ static irqreturn_t mxser_interrupt(int irq, void *dev_id)
                                             iir == MOXA_MUST_IIR_RDA ||
                                             iir == MOXA_MUST_IIR_RTO ||
                                             iir == MOXA_MUST_IIR_LSR)
-                                                mxser_receive_chars(port,
+                                                mxser_receive_chars(tty, port,
                                                                 &status);
 
                                 } else {
                                         status &= port->read_status_mask;
                                         if (status & UART_LSR_DR)
-                                                mxser_receive_chars(port,
+                                                mxser_receive_chars(tty, port,
                                                                 &status);
                                 }
                                 msr = inb(port->ioaddr + UART_MSR);
                                 if (msr & UART_MSR_ANY_DELTA)
-                                        mxser_check_modem_status(port, msr);
+                                        mxser_check_modem_status(tty, port, msr);
 
                                 if (port->board->chip_flag) {
                                         if (iir == 0x02 && (status &
                                                                 UART_LSR_THRE))
-                                                mxser_transmit_chars(port);
+                                                mxser_transmit_chars(tty, port);
                                 } else {
                                         if (status & UART_LSR_THRE)
-                                                mxser_transmit_chars(port);
+                                                mxser_transmit_chars(tty, port);
                                 }
+                                tty_kref_put(tty);
                         } while (int_cnt++ < MXSER_ISR_PASS_LIMIT);
                         spin_unlock(&port->slock);
                 }