tty: The big operations rework

- Operations are now a shared const function block as with most other Linux
  objects

- Introduce wrappers for some optional functions to get consistent behaviour

- Wrap put_char which used to be patched by the tty layer

- Document which functions are needed/optional

- Make put_char report success/fail

- Cache the driver->ops pointer in the tty as tty->ops

- Remove various surplus lock calls we no longer need

- Remove proc_write method as noted by Alexey Dobriyan

- Introduce some missing sanity checks where certain driver/ldisc
  combinations would oops as they didn't check needed methods were present

[akpm@linux-foundation.org: fix fs/compat_ioctl.c build]
[akpm@linux-foundation.org: fix isicom]
[akpm@linux-foundation.org: fix arch/ia64/hp/sim/simserial.c build]
[akpm@linux-foundation.org: fix kgdb]
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

30 files changed, 537 insertions, 664 deletions

diff --git a/arch/ia64/hp/sim/simserial.c b/arch/ia64/hp/sim/simserial.c
index eb0c32a85fd7..23cafc80d2a4 100644
--- a/arch/ia64/hp/sim/simserial.c
+++ b/arch/ia64/hp/sim/simserial.c
@@ -210,21 +210,23 @@ static void do_softint(struct work_struct *private_)
         printk(KERN_ERR "simserial: do_softint called\n");
 }
 
-static void rs_put_char(struct tty_struct *tty, unsigned char ch)
+static int rs_put_char(struct tty_struct *tty, unsigned char ch)
 {
         struct async_struct *info = (struct async_struct *)tty->driver_data;
         unsigned long flags;
 
-        if (!tty || !info->xmit.buf) return;
+        if (!tty || !info->xmit.buf)
+                return 0;
 
         local_irq_save(flags);
         if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) == 0) {
                 local_irq_restore(flags);
-                return;
+                return 0;
         }
         info->xmit.buf[info->xmit.head] = ch;
         info->xmit.head = (info->xmit.head + 1) & (SERIAL_XMIT_SIZE-1);
         local_irq_restore(flags);
+        return 1;
 }
 
 static void transmit_chars(struct async_struct *info, int *intr_done)
@@ -621,7 +623,8 @@ static void rs_close(struct tty_struct *tty, struct file * filp)
          * the line discipline to only process XON/XOFF characters.
          */
         shutdown(info);
-        if (tty->driver->flush_buffer) tty->driver->flush_buffer(tty);
+        if (tty->ops->flush_buffer)
+                tty->ops->flush_buffer(tty);
         if (tty->ldisc.flush_buffer) tty->ldisc.flush_buffer(tty);
         info->event = 0;
         info->tty = NULL;
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 7e31d5f1bc8a..a6c2619ec782 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -143,7 +143,7 @@ restart:
                 int len;
 
                 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-                len = tty->driver->write(tty, skb->data, skb->len);
+                len = tty->ops->write(tty, skb->data, skb->len);
                 hdev->stat.byte_tx += len;
 
                 skb_pull(skb, len);
@@ -190,8 +190,7 @@ static int hci_uart_flush(struct hci_dev *hdev)
 
         /* Flush any pending characters in the driver and discipline. */
         tty_ldisc_flush(tty);
-        if (tty->driver && tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        tty_driver_flush_buffer(tty);
 
         if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
                 hu->proto->flush(hu);
@@ -285,9 +284,7 @@ static int hci_uart_tty_open(struct tty_struct *tty)
 
         if (tty->ldisc.flush_buffer)
                 tty->ldisc.flush_buffer(tty);
-
-        if (tty->driver && tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        tty_driver_flush_buffer(tty);
 
         return 0;
 }
@@ -374,8 +371,8 @@ static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data, char *f
         spin_unlock(&hu->rx_lock);
 
         if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
-                                        tty->driver->unthrottle)
-                tty->driver->unthrottle(tty);
+                                        tty->ops->unthrottle)
+                tty->ops->unthrottle(tty);
 }
 
 static int hci_uart_register_dev(struct hci_uart *hu)
diff --git a/drivers/char/ip2/ip2main.c b/drivers/char/ip2/ip2main.c
index c4f4ca31f7c0..5ef69dcd2588 100644
--- a/drivers/char/ip2/ip2main.c
+++ b/drivers/char/ip2/ip2main.c
@@ -169,7 +169,7 @@ static int Fip_firmware_size;
 static int  ip2_open(PTTY, struct file *);
 static void ip2_close(PTTY, struct file *);
 static int  ip2_write(PTTY, const unsigned char *, int);
-static void ip2_putchar(PTTY, unsigned char);
+static int  ip2_putchar(PTTY, unsigned char);
 static void ip2_flush_chars(PTTY);
 static int  ip2_write_room(PTTY);
 static int  ip2_chars_in_buf(PTTY);
@@ -1616,10 +1616,9 @@ ip2_close( PTTY tty, struct file *pFile )
 
         serviceOutgoingFifo ( pCh->pMyBord );
 
-        if ( tty->driver->flush_buffer ) 
-                tty->driver->flush_buffer(tty);
-        if ( tty->ldisc.flush_buffer )  
-                tty->ldisc.flush_buffer(tty);
+        if ( tty->driver->ops->flush_buffer )
+                tty->driver->ops->flush_buffer(tty);
+        tty_ldisc_flush(tty);
         tty->closing = 0;
         
         pCh->pTTY = NULL;
@@ -1738,7 +1737,7 @@ ip2_write( PTTY tty, const unsigned char *pData, int count)
 /*                                                                            */
 /*                                                                            */
 /******************************************************************************/
-static void
+static int
 ip2_putchar( PTTY tty, unsigned char ch )
 {
         i2ChanStrPtr  pCh = tty->driver_data;
@@ -1753,6 +1752,7 @@ ip2_putchar( PTTY tty, unsigned char ch )
                 ip2_flush_chars( tty );
         } else
                 write_unlock_irqrestore(&pCh->Pbuf_spinlock, flags);
+        return 1;
 
 //      ip2trace (CHANN, ITRC_PUTC, ITRC_RETURN, 1, ch );
 }
diff --git a/drivers/char/isicom.c b/drivers/char/isicom.c
index 57b115272aaa..9c6be8da220c 100644
--- a/drivers/char/isicom.c
+++ b/drivers/char/isicom.c
@@ -1140,28 +1140,29 @@ static int isicom_write(struct tty_struct *tty,	const unsigned char *buf,
 }
 
 /* put_char et all */
-static void isicom_put_char(struct tty_struct *tty, unsigned char ch)
+static int isicom_put_char(struct tty_struct *tty, unsigned char ch)
 {
         struct isi_port *port = tty->driver_data;
         struct isi_board *card = port->card;
         unsigned long flags;
 
         if (isicom_paranoia_check(port, tty->name, "isicom_put_char"))
-                return;
+                return 0;
 
         if (!port->xmit_buf)
-                return;
+                return 0;
 
         spin_lock_irqsave(&card->card_lock, flags);
-        if (port->xmit_cnt >= SERIAL_XMIT_SIZE - 1)
-                goto out;
+        if (port->xmit_cnt >= SERIAL_XMIT_SIZE - 1) {
+                spin_unlock_irqrestore(&card->card_lock, flags);
+                return 0;
+        }
 
         port->xmit_buf[port->xmit_head++] = ch;
         port->xmit_head &= (SERIAL_XMIT_SIZE - 1);
         port->xmit_cnt++;
         spin_unlock_irqrestore(&card->card_lock, flags);
-out:
-        return;
+        return 1;
 }
 
 /* flush_chars et all */
diff --git a/drivers/char/keyboard.c b/drivers/char/keyboard.c
index 60b934adea65..d1c50b3302e5 100644
--- a/drivers/char/keyboard.c
+++ b/drivers/char/keyboard.c
@@ -1230,7 +1230,7 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
 
         if (rep &&
             (!vc_kbd_mode(kbd, VC_REPEAT) ||
-             (tty && !L_ECHO(tty) && tty->driver->chars_in_buffer(tty)))) {
+             (tty && !L_ECHO(tty) && tty_chars_in_buffer(tty)))) {
                 /*
                  * Don't repeat a key if the input buffers are not empty and the
                  * characters get aren't echoed locally. This makes key repeat
diff --git a/drivers/char/n_hdlc.c b/drivers/char/n_hdlc.c
index a07c0af4819e..a35bfd7ee80e 100644
--- a/drivers/char/n_hdlc.c
+++ b/drivers/char/n_hdlc.c
@@ -342,12 +342,10 @@ static int n_hdlc_tty_open (struct tty_struct *tty)
 #endif
         
         /* Flush any pending characters in the driver and discipline. */
-        
         if (tty->ldisc.flush_buffer)
-                tty->ldisc.flush_buffer (tty);
+                tty->ldisc.flush_buffer(tty);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer (tty);
+        tty_driver_flush_buffer(tty);
                 
         if (debuglevel >= DEBUG_LEVEL_INFO)     
                 printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__);
@@ -399,7 +397,7 @@ static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
                         
                 /* Send the next block of data to device */
                 tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
-                actual = tty->driver->write(tty, tbuf->buf, tbuf->count);
+                actual = tty->ops->write(tty, tbuf->buf, tbuf->count);
 
                 /* rollback was possible and has been done */
                 if (actual == -ERESTARTSYS) {
@@ -752,8 +750,7 @@ static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
 
         case TIOCOUTQ:
                 /* get the pending tx byte count in the driver */
-                count = tty->driver->chars_in_buffer ?
-                                tty->driver->chars_in_buffer(tty) : 0;
+                count = tty_chars_in_buffer(tty);
                 /* add size of next output frame in queue */
                 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags);
                 if (n_hdlc->tx_buf_list.head)
diff --git a/drivers/char/n_r3964.c b/drivers/char/n_r3964.c
index 3f6486e9f1ec..902169062332 100644
--- a/drivers/char/n_r3964.c
+++ b/drivers/char/n_r3964.c
@@ -376,8 +376,9 @@ static void put_char(struct r3964_info *pInfo, unsigned char ch)
         if (tty == NULL)
                 return;
 
-        if (tty->driver->put_char) {
-                tty->driver->put_char(tty, ch);
+        /* FIXME: put_char should not be called from an IRQ */
+        if (tty->ops->put_char) {
+                tty->ops->put_char(tty, ch);
         }
         pInfo->bcc ^= ch;
 }
@@ -386,12 +387,9 @@ static void flush(struct r3964_info *pInfo)
 {
         struct tty_struct *tty = pInfo->tty;
 
-        if (tty == NULL)
+        if (tty == NULL || tty->ops->flush_chars == NULL)
                 return;
-
-        if (tty->driver->flush_chars) {
-                tty->driver->flush_chars(tty);
-        }
+        tty->ops->flush_chars(tty);
 }
 
 static void trigger_transmit(struct r3964_info *pInfo)
@@ -449,12 +447,11 @@ static void transmit_block(struct r3964_info *pInfo)
         struct r3964_block_header *pBlock = pInfo->tx_first;
         int room = 0;
 
-        if ((tty == NULL) || (pBlock == NULL)) {
+        if (tty == NULL || pBlock == NULL) {
                 return;
         }
 
-        if (tty->driver->write_room)
-                room = tty->driver->write_room(tty);
+        room = tty_write_room(tty);
 
         TRACE_PS("transmit_block %p, room %d, length %d",
                  pBlock, room, pBlock->length);
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index e1518e17e09d..abc93a93dcdd 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -149,8 +149,8 @@ static void check_unthrottle(struct tty_struct *tty)
 {
         if (tty->count &&
             test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
-            tty->driver->unthrottle)
-                tty->driver->unthrottle(tty);
+            tty->ops->unthrottle)
+                tty->ops->unthrottle(tty);
 }
 
 /**
@@ -273,7 +273,7 @@ static int opost(unsigned char c, struct tty_struct *tty)
 {
         int     space, spaces;
 
-        space = tty->driver->write_room(tty);
+        space = tty_write_room(tty);
         if (!space)
                 return -1;
 
@@ -286,7 +286,7 @@ static int opost(unsigned char c, struct tty_struct *tty)
                         if (O_ONLCR(tty)) {
                                 if (space < 2)
                                         return -1;
-                                tty->driver->put_char(tty, '\r');
+                                tty_put_char(tty, '\r');
                                 tty->column = 0;
                         }
                         tty->canon_column = tty->column;
@@ -308,7 +308,7 @@ static int opost(unsigned char c, struct tty_struct *tty)
                                 if (space < spaces)
                                         return -1;
                                 tty->column += spaces;
-                                tty->driver->write(tty, "        ", spaces);
+                                tty->ops->write(tty, "        ", spaces);
                                 return 0;
                         }
                         tty->column += spaces;
@@ -325,7 +325,7 @@ static int opost(unsigned char c, struct tty_struct *tty)
                         break;
                 }
         }
-        tty->driver->put_char(tty, c);
+        tty_put_char(tty, c);
         unlock_kernel();
         return 0;
 }
@@ -352,7 +352,7 @@ static ssize_t opost_block(struct tty_struct *tty,
         int     i;
         const unsigned char *cp;
 
-        space = tty->driver->write_room(tty);
+        space = tty_write_room(tty);
         if (!space)
                 return 0;
         if (nr > space)
@@ -390,28 +390,15 @@ static ssize_t opost_block(struct tty_struct *tty,
                 }
         }
 break_out:
-        if (tty->driver->flush_chars)
-                tty->driver->flush_chars(tty);
-        i = tty->driver->write(tty, buf, i);
+        if (tty->ops->flush_chars)
+                tty->ops->flush_chars(tty);
+        i = tty->ops->write(tty, buf, i);
         unlock_kernel();
         return i;
 }
 
 
 /**
- *      put_char        -       write character to driver
- *      @c: character (or part of unicode symbol)
- *      @tty: terminal device
- *
- *      Queue a byte to the driver layer for output
- */
-
-static inline void put_char(unsigned char c, struct tty_struct *tty)
-{
-        tty->driver->put_char(tty, c);
-}
-
-/**
  *      echo_char       -       echo characters
  *      @c: unicode byte to echo
  *      @tty: terminal device
@@ -423,8 +410,8 @@ static inline void put_char(unsigned char c, struct tty_struct *tty)
 static void echo_char(unsigned char c, struct tty_struct *tty)
 {
         if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
-                put_char('^', tty);
-                put_char(c ^ 0100, tty);
+                tty_put_char(tty, '^');
+                tty_put_char(tty, c ^ 0100);
                 tty->column += 2;
         } else
                 opost(c, tty);
@@ -433,7 +420,7 @@ static void echo_char(unsigned char c, struct tty_struct *tty)
 static inline void finish_erasing(struct tty_struct *tty)
 {
         if (tty->erasing) {
-                put_char('/', tty);
+                tty_put_char(tty, '/');
                 tty->column++;
                 tty->erasing = 0;
         }
@@ -517,7 +504,7 @@ static void eraser(unsigned char c, struct tty_struct *tty)
                 if (L_ECHO(tty)) {
                         if (L_ECHOPRT(tty)) {
                                 if (!tty->erasing) {
-                                        put_char('\\', tty);
+                                        tty_put_char(tty, '\\');
                                         tty->column++;
                                         tty->erasing = 1;
                                 }
@@ -525,7 +512,7 @@ static void eraser(unsigned char c, struct tty_struct *tty)
                                 echo_char(c, tty);
                                 while (--cnt > 0) {
                                         head = (head+1) & (N_TTY_BUF_SIZE-1);
-                                        put_char(tty->read_buf[head], tty);
+                                        tty_put_char(tty, tty->read_buf[head]);
                                 }
                         } else if (kill_type == ERASE && !L_ECHOE(tty)) {
                                 echo_char(ERASE_CHAR(tty), tty);
@@ -553,22 +540,22 @@ static void eraser(unsigned char c, struct tty_struct *tty)
                                 /* Now backup to that column. */
                                 while (tty->column > col) {
                                         /* Can't use opost here. */
-                                        put_char('\b', tty);
+                                        tty_put_char(tty, '\b');
                                         if (tty->column > 0)
                                                 tty->column--;
                                 }
                         } else {
                                 if (iscntrl(c) && L_ECHOCTL(tty)) {
-                                        put_char('\b', tty);
-                                        put_char(' ', tty);
-                                        put_char('\b', tty);
+                                        tty_put_char(tty, '\b');
+                                        tty_put_char(tty, ' ');
+                                        tty_put_char(tty, '\b');
                                         if (tty->column > 0)
                                                 tty->column--;
                                 }
                                 if (!iscntrl(c) || L_ECHOCTL(tty)) {
-                                        put_char('\b', tty);
-                                        put_char(' ', tty);
-                                        put_char('\b', tty);
+                                        tty_put_char(tty, '\b');
+                                        tty_put_char(tty, ' ');
+                                        tty_put_char(tty, '\b');
                                         if (tty->column > 0)
                                                 tty->column--;
                                 }
@@ -599,8 +586,7 @@ static inline void isig(int sig, struct tty_struct *tty, int flush)
                 kill_pgrp(tty->pgrp, sig, 1);
         if (flush || !L_NOFLSH(tty)) {
                 n_tty_flush_buffer(tty);
-                if (tty->driver->flush_buffer)
-                        tty->driver->flush_buffer(tty);
+                tty_driver_flush_buffer(tty);
         }
 }
 
@@ -732,7 +718,7 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
                 tty->lnext = 0;
                 if (L_ECHO(tty)) {
                         if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
-                                put_char('\a', tty); /* beep if no space */
+                                tty_put_char(tty, '\a'); /* beep if no space */
                                 return;
                         }
                         /* Record the column of first canon char. */
@@ -776,8 +762,7 @@ send_signal:
                          */
                         if (!L_NOFLSH(tty)) {
                                 n_tty_flush_buffer(tty);
-                                if (tty->driver->flush_buffer)
-                                        tty->driver->flush_buffer(tty);
+                                tty_driver_flush_buffer(tty);
                         }
                         if (L_ECHO(tty))
                                 echo_char(c, tty);
@@ -806,8 +791,8 @@ send_signal:
                         if (L_ECHO(tty)) {
                                 finish_erasing(tty);
                                 if (L_ECHOCTL(tty)) {
-                                        put_char('^', tty);
-                                        put_char('\b', tty);
+                                        tty_put_char(tty, '^');
+                                        tty_put_char(tty, '\b');
                                 }
                         }
                         return;
@@ -828,7 +813,7 @@ send_signal:
                 if (c == '\n') {
                         if (L_ECHO(tty) || L_ECHONL(tty)) {
                                 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
-                                        put_char('\a', tty);
+                                        tty_put_char(tty, '\a');
                                 opost('\n', tty);
                         }
                         goto handle_newline;
@@ -846,7 +831,7 @@ send_signal:
                          */
                         if (L_ECHO(tty)) {
                                 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
-                                        put_char('\a', tty);
+                                        tty_put_char(tty, '\a');
                                 /* Record the column of first canon char. */
                                 if (tty->canon_head == tty->read_head)
                                         tty->canon_column = tty->column;
@@ -876,7 +861,7 @@ handle_newline:
         finish_erasing(tty);
         if (L_ECHO(tty)) {
                 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
-                        put_char('\a', tty); /* beep if no space */
+                        tty_put_char(tty, '\a'); /* beep if no space */
                         return;
                 }
                 if (c == '\n')
@@ -980,8 +965,8 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
                                 break;
                         }
                 }
-                if (tty->driver->flush_chars)
-                        tty->driver->flush_chars(tty);
+                if (tty->ops->flush_chars)
+                        tty->ops->flush_chars(tty);
         }
 
         n_tty_set_room(tty);
@@ -1000,8 +985,8 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
         if (tty->receive_room < TTY_THRESHOLD_THROTTLE) {
                 /* check TTY_THROTTLED first so it indicates our state */
                 if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
-                    tty->driver->throttle)
-                        tty->driver->throttle(tty);
+                    tty->ops->throttle)
+                        tty->ops->throttle(tty);
         }
 }
 
@@ -1086,6 +1071,9 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
                         tty->real_raw = 0;
         }
         n_tty_set_room(tty);
+        /* The termios change make the tty ready for I/O */
+        wake_up_interruptible(&tty->write_wait);
+        wake_up_interruptible(&tty->read_wait);
 }
 
 /**
@@ -1513,11 +1501,11 @@ static ssize_t write_chan(struct tty_struct *tty, struct file *file,
                                         break;
                                 b++; nr--;
                         }
-                        if (tty->driver->flush_chars)
-                                tty->driver->flush_chars(tty);
+                        if (tty->ops->flush_chars)
+                                tty->ops->flush_chars(tty);
                 } else {
                         while (nr > 0) {
-                                c = tty->driver->write(tty, b, nr);
+                                c = tty->ops->write(tty, b, nr);
                                 if (c < 0) {
                                         retval = c;
                                         goto break_out;
@@ -1554,11 +1542,6 @@ break_out:
  *
  *      This code must be sure never to sleep through a hangup.
  *      Called without the kernel lock held - fine
- *
- *      FIXME: if someone changes the VMIN or discipline settings for the
- *      terminal while another process is in poll() the poll does not
- *      recompute the new limits. Possibly set_termios should issue
- *      a read wakeup to fix this bug.
  */
 
 static unsigned int normal_poll(struct tty_struct *tty, struct file *file,
@@ -1582,9 +1565,9 @@ static unsigned int normal_poll(struct tty_struct *tty, struct file *file,
                 else
                         tty->minimum_to_wake = 1;
         }
-        if (!tty_is_writelocked(tty) &&
-                        tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS &&
-                        tty->driver->write_room(tty) > 0)
+        if (tty->ops->write && !tty_is_writelocked(tty) &&
+                        tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
+                        tty_write_room(tty) > 0)
                 mask |= POLLOUT | POLLWRNORM;
         return mask;
 }
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index b1692afd797e..f69fb8d7a680 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1108,8 +1108,8 @@ restart:
            a reference to the old ldisc. If we ended up flipping back
            to the existing ldisc we have two references to it */
 
-        if (tty->ldisc.num != o_ldisc.num && tty->driver->set_ldisc)
-                tty->driver->set_ldisc(tty);
+        if (tty->ldisc.num != o_ldisc.num && tty->ops->set_ldisc)
+                tty->ops->set_ldisc(tty);
 
         tty_ldisc_put(o_ldisc.num);
 
@@ -1181,9 +1181,8 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
                 if (*str == '\0')
                         str = NULL;
 
-                if (tty_line >= 0 && tty_line <= p->num && p->poll_init &&
-                                !p->poll_init(p, tty_line, str)) {
-
+                if (tty_line >= 0 && tty_line <= p->num && p->ops &&
+                    p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
                         res = p;
                         *line = tty_line;
                         break;
@@ -1452,8 +1451,7 @@ static void do_tty_hangup(struct work_struct *work)
                 /* We may have no line discipline at this point */
                 if (ld->flush_buffer)
                         ld->flush_buffer(tty);
-                if (tty->driver->flush_buffer)
-                        tty->driver->flush_buffer(tty);
+                tty_driver_flush_buffer(tty);
                 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
                     ld->write_wakeup)
                         ld->write_wakeup(tty);
@@ -1516,11 +1514,11 @@ static void do_tty_hangup(struct work_struct *work)
          * So we just call close() the right number of times.
          */
         if (cons_filp) {
-                if (tty->driver->close)
+                if (tty->ops->close)
                         for (n = 0; n < closecount; n++)
-                                tty->driver->close(tty, cons_filp);
-        } else if (tty->driver->hangup)
-                (tty->driver->hangup)(tty);
+                                tty->ops->close(tty, cons_filp);
+        } else if (tty->ops->hangup)
+                (tty->ops->hangup)(tty);
         /*
          * We don't want to have driver/ldisc interactions beyond
          * the ones we did here. The driver layer expects no
@@ -1752,8 +1750,8 @@ void stop_tty(struct tty_struct *tty)
                 wake_up_interruptible(&tty->link->read_wait);
         }
         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
-        if (tty->driver->stop)
-                (tty->driver->stop)(tty);
+        if (tty->ops->stop)
+                (tty->ops->stop)(tty);
 }
 
 EXPORT_SYMBOL(stop_tty);
@@ -1786,8 +1784,8 @@ void start_tty(struct tty_struct *tty)
                 wake_up_interruptible(&tty->link->read_wait);
         }
         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
-        if (tty->driver->start)
-                (tty->driver->start)(tty);
+        if (tty->ops->start)
+                (tty->ops->start)(tty);
         /* If we have a running line discipline it may need kicking */
         tty_wakeup(tty);
 }
@@ -1972,10 +1970,13 @@ static ssize_t tty_write(struct file *file, const char __user *buf,
         tty = (struct tty_struct *)file->private_data;
         if (tty_paranoia_check(tty, inode, "tty_write"))
                 return -EIO;
-        if (!tty || !tty->driver->write ||
+        if (!tty || !tty->ops->write ||
                 (test_bit(TTY_IO_ERROR, &tty->flags)))
                         return -EIO;
-
+        /* Short term debug to catch buggy drivers */
+        if (tty->ops->write_room == NULL)
+                printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
+                        tty->driver->name);
         ld = tty_ldisc_ref_wait(tty);
         if (!ld->write)
                 ret = -EIO;
@@ -2122,6 +2123,7 @@ static int init_dev(struct tty_driver *driver, int idx,
                 goto fail_no_mem;
         initialize_tty_struct(tty);
         tty->driver = driver;
+        tty->ops = driver->ops;
         tty->index = idx;
         tty_line_name(driver, idx, tty->name);
 
@@ -2152,6 +2154,7 @@ static int init_dev(struct tty_driver *driver, int idx,
                         goto free_mem_out;
                 initialize_tty_struct(o_tty);
                 o_tty->driver = driver->other;
+                o_tty->ops = driver->ops;
                 o_tty->index = idx;
                 tty_line_name(driver->other, idx, o_tty->name);
 
@@ -2456,8 +2459,8 @@ static void release_dev(struct file *filp)
                 }
         }
 #endif
-        if (tty->driver->close)
-                tty->driver->close(tty, filp);
+        if (tty->ops->close)
+                tty->ops->close(tty, filp);
 
         /*
          * Sanity check: if tty->count is going to zero, there shouldn't be
@@ -2740,8 +2743,8 @@ got_driver:
         printk(KERN_DEBUG "opening %s...", tty->name);
 #endif
         if (!retval) {
-                if (tty->driver->open)
-                        retval = tty->driver->open(tty, filp);
+                if (tty->ops->open)
+                        retval = tty->ops->open(tty, filp);
                 else
                         retval = -ENODEV;
         }
@@ -2840,7 +2843,7 @@ static int ptmx_open(struct inode *inode, struct file *filp)
                 goto out1;
 
         check_tty_count(tty, "tty_open");
-        retval = ptm_driver->open(tty, filp);
+        retval = ptm_driver->ops->open(tty, filp);
         if (!retval)
                 return 0;
 out1:
@@ -3336,25 +3339,20 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
 
 static int send_break(struct tty_struct *tty, unsigned int duration)
 {
-        int retval = -EINTR;
-
-        lock_kernel();
         if (tty_write_lock(tty, 0) < 0)
-                goto out;
-        tty->driver->break_ctl(tty, -1);
+                return -EINTR;
+        tty->ops->break_ctl(tty, -1);
         if (!signal_pending(current))
                 msleep_interruptible(duration);
-        tty->driver->break_ctl(tty, 0);
+        tty->ops->break_ctl(tty, 0);
         tty_write_unlock(tty);
         if (!signal_pending(current))
-                retval = 0;
-out:
-        unlock_kernel();
-        return retval;
+                return -EINTR;
+        return 0;
 }
 
 /**
- *      tiocmget                -       get modem status
+ *      tty_tiocmget            -       get modem status
  *      @tty: tty device
  *      @file: user file pointer
  *      @p: pointer to result
@@ -3369,10 +3367,8 @@ static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p
 {
         int retval = -EINVAL;
 
-        if (tty->driver->tiocmget) {
-                lock_kernel();
-                retval = tty->driver->tiocmget(tty, file);
-                unlock_kernel();
+        if (tty->ops->tiocmget) {
+                retval = tty->ops->tiocmget(tty, file);
 
                 if (retval >= 0)
                         retval = put_user(retval, p);
@@ -3381,7 +3377,7 @@ static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p
 }
 
 /**
- *      tiocmset                -       set modem status
+ *      tty_tiocmset            -       set modem status
  *      @tty: tty device
  *      @file: user file pointer
  *      @cmd: command - clear bits, set bits or set all
@@ -3398,7 +3394,7 @@ static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int
 {
         int retval = -EINVAL;
 
-        if (tty->driver->tiocmset) {
+        if (tty->ops->tiocmset) {
                 unsigned int set, clear, val;
 
                 retval = get_user(val, p);
@@ -3422,9 +3418,7 @@ static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int
                 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
                 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
 
-                lock_kernel();
-                retval = tty->driver->tiocmset(tty, file, set, clear);
-                unlock_kernel();
+                retval = tty->ops->tiocmset(tty, file, set, clear);
         }
         return retval;
 }
@@ -3455,23 +3449,25 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
         retval = -EINVAL;
 
-        if (!tty->driver->break_ctl) {
+        if (!tty->ops->break_ctl) {
                 switch (cmd) {
                 case TIOCSBRK:
                 case TIOCCBRK:
-                        if (tty->driver->ioctl)
-                                retval = tty->driver->ioctl(tty, file, cmd, arg);
+                        if (tty->ops->ioctl)
+                                retval = tty->ops->ioctl(tty, file, cmd, arg);
+                        if (retval != -EINVAL && retval != -ENOIOCTLCMD)
+                                printk(KERN_WARNING "tty: driver %s needs updating to use break_ctl\n", tty->driver->name);
                         return retval;
 
                 /* These two ioctl's always return success; even if */
                 /* the driver doesn't support them. */
                 case TCSBRK:
                 case TCSBRKP:
-                        if (!tty->driver->ioctl)
+                        if (!tty->ops->ioctl)
                                 return 0;
-                        lock_kernel();
-                        retval = tty->driver->ioctl(tty, file, cmd, arg);
-                        unlock_kernel();
+                        retval = tty->ops->ioctl(tty, file, cmd, arg);
+                        if (retval != -EINVAL && retval != -ENOIOCTLCMD)
+                                printk(KERN_WARNING "tty: driver %s needs updating to use break_ctl\n", tty->driver->name);
                         if (retval == -ENOIOCTLCMD)
                                 retval = 0;
                         return retval;
@@ -3491,9 +3487,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 if (retval)
                         return retval;
                 if (cmd != TIOCCBRK) {
-                        lock_kernel();
                         tty_wait_until_sent(tty, 0);
-                        unlock_kernel();
                         if (signal_pending(current))
                                 return -EINTR;
                 }
@@ -3531,7 +3525,6 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         case TIOCGSID:
                 return tiocgsid(tty, real_tty, p);
         case TIOCGETD:
-                /* FIXME: check this is ok */
                 return put_user(tty->ldisc.num, (int __user *)p);
         case TIOCSETD:
                 return tiocsetd(tty, p);
@@ -3543,15 +3536,13 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
          * Break handling
          */
         case TIOCSBRK:  /* Turn break on, unconditionally */
-                lock_kernel();
-                tty->driver->break_ctl(tty, -1);
-                unlock_kernel();
+                if (tty->ops->break_ctl)
+                        tty->ops->break_ctl(tty, -1);
                 return 0;
 
         case TIOCCBRK:  /* Turn break off, unconditionally */
-                lock_kernel();
-                tty->driver->break_ctl(tty, 0);
-                unlock_kernel();
+                if (tty->ops->break_ctl)
+                        tty->ops->break_ctl(tty, 0);
                 return 0;
         case TCSBRK:   /* SVID version: non-zero arg --> no break */
                 /* non-zero arg means wait for all output data
@@ -3580,8 +3571,8 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 }
                 break;
         }
-        if (tty->driver->ioctl) {
-                retval = (tty->driver->ioctl)(tty, file, cmd, arg);
+        if (tty->ops->ioctl) {
+                retval = (tty->ops->ioctl)(tty, file, cmd, arg);
                 if (retval != -ENOIOCTLCMD)
                         return retval;
         }
@@ -3608,8 +3599,8 @@ static long tty_compat_ioctl(struct file *file, unsigned int cmd,
         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
                 return -EINVAL;
 
-        if (tty->driver->compat_ioctl) {
-                retval = (tty->driver->compat_ioctl)(tty, file, cmd, arg);
+        if (tty->ops->compat_ioctl) {
+                retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
                 if (retval != -ENOIOCTLCMD)
                         return retval;
         }
@@ -3659,8 +3650,7 @@ void __do_SAK(struct tty_struct *tty)
 
         tty_ldisc_flush(tty);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        tty_driver_flush_buffer(tty);
 
         read_lock(&tasklist_lock);
         /* Kill the entire session */
@@ -3871,15 +3861,27 @@ static void initialize_tty_struct(struct tty_struct *tty)
         INIT_WORK(&tty->SAK_work, do_SAK_work);
 }
 
-/*
- * The default put_char routine if the driver did not define one.
+/**
+ *      tty_put_char    -       write one character to a tty
+ *      @tty: tty
+ *      @ch: character
+ *
+ *      Write one byte to the tty using the provided put_char method
+ *      if present. Returns the number of characters successfully output.
+ *
+ *      Note: the specific put_char operation in the driver layer may go
+ *      away soon. Don't call it directly, use this method
  */
 
-static void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
+int tty_put_char(struct tty_struct *tty, unsigned char ch)
 {
-        tty->driver->write(tty, &ch, 1);
+        if (tty->ops->put_char)
+                return tty->ops->put_char(tty, ch);
+        return tty->ops->write(tty, &ch, 1);
 }
 
+EXPORT_SYMBOL_GPL(tty_put_char);
+
 static struct class *tty_class;
 
 /**
@@ -3962,37 +3964,8 @@ void put_tty_driver(struct tty_driver *driver)
 void tty_set_operations(struct tty_driver *driver,
                         const struct tty_operations *op)
 {
-        driver->open = op->open;
-        driver->close = op->close;
-        driver->write = op->write;
-        driver->put_char = op->put_char;
-        driver->flush_chars = op->flush_chars;
-        driver->write_room = op->write_room;
-        driver->chars_in_buffer = op->chars_in_buffer;
-        driver->ioctl = op->ioctl;
-        driver->compat_ioctl = op->compat_ioctl;
-        driver->set_termios = op->set_termios;
-        driver->throttle = op->throttle;
-        driver->unthrottle = op->unthrottle;
-        driver->stop = op->stop;
-        driver->start = op->start;
-        driver->hangup = op->hangup;
-        driver->break_ctl = op->break_ctl;
-        driver->flush_buffer = op->flush_buffer;
-        driver->set_ldisc = op->set_ldisc;
-        driver->wait_until_sent = op->wait_until_sent;
-        driver->send_xchar = op->send_xchar;
-        driver->read_proc = op->read_proc;
-        driver->write_proc = op->write_proc;
-        driver->tiocmget = op->tiocmget;
-        driver->tiocmset = op->tiocmset;
-#ifdef CONFIG_CONSOLE_POLL
-        driver->poll_init = op->poll_init;
-        driver->poll_get_char = op->poll_get_char;
-        driver->poll_put_char = op->poll_put_char;
-#endif
-}
-
+        driver->ops = op;
+};
 
 EXPORT_SYMBOL(alloc_tty_driver);
 EXPORT_SYMBOL(put_tty_driver);
@@ -4055,9 +4028,6 @@ int tty_register_driver(struct tty_driver *driver)
                 return error;
         }
 
-        if (!driver->put_char)
-                driver->put_char = tty_default_put_char;
-
         mutex_lock(&tty_mutex);
         list_add(&driver->tty_drivers, &tty_drivers);
         mutex_unlock(&tty_mutex);
diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index 8c4bf3e48d5b..c10d40c4c5ca 100644
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -40,6 +40,34 @@
 #define TERMIOS_OLD     8
 
 
+int tty_chars_in_buffer(struct tty_struct *tty)
+{
+        if (tty->ops->chars_in_buffer)
+                return tty->ops->chars_in_buffer(tty);
+        else
+                return 0;
+}
+
+EXPORT_SYMBOL(tty_chars_in_buffer);
+
+int tty_write_room(struct tty_struct *tty)
+{
+        if (tty->ops->write_room)
+                return tty->ops->write_room(tty);
+        return 2048;
+}
+
+EXPORT_SYMBOL(tty_write_room);
+
+void tty_driver_flush_buffer(struct tty_struct *tty)
+{
+        if (tty->ops->flush_buffer)
+                tty->ops->flush_buffer(tty);
+}
+
+EXPORT_SYMBOL(tty_driver_flush_buffer);
+
+
 /**
  *      tty_wait_until_sent     -       wait for I/O to finish
  *      @tty: tty we are waiting for
@@ -58,17 +86,13 @@ void tty_wait_until_sent(struct tty_struct *tty, long timeout)
 
         printk(KERN_DEBUG "%s wait until sent...\n", tty_name(tty, buf));
 #endif
-        if (!tty->driver->chars_in_buffer)
-                return;
         if (!timeout)
                 timeout = MAX_SCHEDULE_TIMEOUT;
-        lock_kernel();
         if (wait_event_interruptible_timeout(tty->write_wait,
-                        !tty->driver->chars_in_buffer(tty), timeout) >= 0) {
-                if (tty->driver->wait_until_sent)
-                        tty->driver->wait_until_sent(tty, timeout);
+                        !tty_chars_in_buffer(tty), timeout) >= 0) {
+                if (tty->ops->wait_until_sent)
+                        tty->ops->wait_until_sent(tty, timeout);
         }
-        unlock_kernel();
 }
 EXPORT_SYMBOL(tty_wait_until_sent);
 
@@ -444,8 +468,8 @@ static void change_termios(struct tty_struct *tty, struct ktermios *new_termios)
                 }
         }
 
-        if (tty->driver->set_termios)
-                (*tty->driver->set_termios)(tty, &old_termios);
+        if (tty->ops->set_termios)
+                (*tty->ops->set_termios)(tty, &old_termios);
         else
                 tty_termios_copy_hw(tty->termios, &old_termios);
 
@@ -748,8 +772,8 @@ static int send_prio_char(struct tty_struct *tty, char ch)
 {
         int     was_stopped = tty->stopped;
 
-        if (tty->driver->send_xchar) {
-                tty->driver->send_xchar(tty, ch);
+        if (tty->ops->send_xchar) {
+                tty->ops->send_xchar(tty, ch);
                 return 0;
         }
 
@@ -758,7 +782,7 @@ static int send_prio_char(struct tty_struct *tty, char ch)
 
         if (was_stopped)
                 start_tty(tty);
-        tty->driver->write(tty, &ch, 1);
+        tty->ops->write(tty, &ch, 1);
         if (was_stopped)
                 stop_tty(tty);
         tty_write_unlock(tty);
@@ -778,13 +802,14 @@ static int tty_change_softcar(struct tty_struct *tty, int arg)
 {
         int ret = 0;
         int bit = arg ? CLOCAL : 0;
-        struct ktermios old = *tty->termios;
+        struct ktermios old;
 
         mutex_lock(&tty->termios_mutex);
+        old = *tty->termios;
         tty->termios->c_cflag &= ~CLOCAL;
         tty->termios->c_cflag |= bit;
-        if (tty->driver->set_termios)
-                tty->driver->set_termios(tty, &old);
+        if (tty->ops->set_termios)
+                tty->ops->set_termios(tty, &old);
         if ((tty->termios->c_cflag & CLOCAL) != bit)
                 ret = -EINVAL;
         mutex_unlock(&tty->termios_mutex);
@@ -926,8 +951,7 @@ int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
                         ld->flush_buffer(tty);
                 /* fall through */
         case TCOFLUSH:
-                if (tty->driver->flush_buffer)
-                        tty->driver->flush_buffer(tty);
+                tty_driver_flush_buffer(tty);
                 break;
         default:
                 tty_ldisc_deref(ld);
@@ -984,9 +1008,7 @@ int n_tty_ioctl(struct tty_struct *tty, struct file *file,
         case TCFLSH:
                 return tty_perform_flush(tty, arg);
         case TIOCOUTQ:
-                return put_user(tty->driver->chars_in_buffer ?
-                                tty->driver->chars_in_buffer(tty) : 0,
-                                (int __user *) arg);
+                return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
         case TIOCINQ:
                 retval = tty->read_cnt;
                 if (L_ICANON(tty))
diff --git a/drivers/input/serio/serport.c b/drivers/input/serio/serport.c
index e1a3a79ab3f9..7ff71ba7b7c9 100644
--- a/drivers/input/serio/serport.c
+++ b/drivers/input/serio/serport.c
@@ -46,7 +46,7 @@ struct serport {
 static int serport_serio_write(struct serio *serio, unsigned char data)
 {
         struct serport *serport = serio->port_data;
-        return -(serport->tty->driver->write(serport->tty, &data, 1) != 1);
+        return -(serport->tty->ops->write(serport->tty, &data, 1) != 1);
 }
 
 static int serport_serio_open(struct serio *serio)
diff --git a/drivers/isdn/gigaset/ser-gigaset.c b/drivers/isdn/gigaset/ser-gigaset.c
index fceeb1d57682..45d1ee93cd39 100644
--- a/drivers/isdn/gigaset/ser-gigaset.c
+++ b/drivers/isdn/gigaset/ser-gigaset.c
@@ -68,10 +68,10 @@ static int write_modem(struct cardstate *cs)
         struct tty_struct *tty = cs->hw.ser->tty;
         struct bc_state *bcs = &cs->bcs[0];     /* only one channel */
         struct sk_buff *skb = bcs->tx_skb;
-        int sent;
+        int sent = -EOPNOTSUPP;
 
         if (!tty || !tty->driver || !skb)
-                return -EFAULT;
+                return -EINVAL;
 
         if (!skb->len) {
                 dev_kfree_skb_any(skb);
@@ -80,7 +80,8 @@ static int write_modem(struct cardstate *cs)
         }
 
         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-        sent = tty->driver->write(tty, skb->data, skb->len);
+        if (tty->ops->write)
+                sent = tty->ops->write(tty, skb->data, skb->len);
         gig_dbg(DEBUG_OUTPUT, "write_modem: sent %d", sent);
         if (sent < 0) {
                 /* error */
@@ -120,7 +121,7 @@ static int send_cb(struct cardstate *cs)
 
         if (cb->len) {
                 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-                sent = tty->driver->write(tty, cb->buf + cb->offset, cb->len);
+                sent = tty->ops->write(tty, cb->buf + cb->offset, cb->len);
                 if (sent < 0) {
                         /* error */
                         gig_dbg(DEBUG_OUTPUT, "send_cb: write error %d", sent);
@@ -440,14 +441,14 @@ static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state, unsi
         struct tty_struct *tty = cs->hw.ser->tty;
         unsigned int set, clear;
 
-        if (!tty || !tty->driver || !tty->driver->tiocmset)
-                return -EFAULT;
+        if (!tty || !tty->driver || !tty->ops->tiocmset)
+                return -EINVAL;
         set = new_state & ~old_state;
         clear = old_state & ~new_state;
         if (!set && !clear)
                 return 0;
         gig_dbg(DEBUG_IF, "tiocmset set %x clear %x", set, clear);
-        return tty->driver->tiocmset(tty, NULL, set, clear);
+        return tty->ops->tiocmset(tty, NULL, set, clear);
 }
 
 static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
index 1da55dd2a5a0..82a36266dfc9 100644
--- a/drivers/net/hamradio/6pack.c
+++ b/drivers/net/hamradio/6pack.c
@@ -148,13 +148,13 @@ static void sp_xmit_on_air(unsigned long channel)
 
         if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
                 sp->led_state = 0x70;
-                sp->tty->driver->write(sp->tty, &sp->led_state, 1);
+                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
                 sp->tx_enable = 1;
-                actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2);
+                actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
                 sp->xleft -= actual;
                 sp->xhead += actual;
                 sp->led_state = 0x60;
-                sp->tty->driver->write(sp->tty, &sp->led_state, 1);
+                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
                 sp->status2 = 0;
         } else
                 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
@@ -220,13 +220,13 @@ static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
          */
         if (sp->duplex == 1) {
                 sp->led_state = 0x70;
-                sp->tty->driver->write(sp->tty, &sp->led_state, 1);
+                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
                 sp->tx_enable = 1;
-                actual = sp->tty->driver->write(sp->tty, sp->xbuff, count);
+                actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
                 sp->xleft = count - actual;
                 sp->xhead = sp->xbuff + actual;
                 sp->led_state = 0x60;
-                sp->tty->driver->write(sp->tty, &sp->led_state, 1);
+                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
         } else {
                 sp->xleft = count;
                 sp->xhead = sp->xbuff;
@@ -444,7 +444,7 @@ static void sixpack_write_wakeup(struct tty_struct *tty)
         }
 
         if (sp->tx_enable) {
-                actual = tty->driver->write(tty, sp->xhead, sp->xleft);
+                actual = tty->ops->write(tty, sp->xhead, sp->xleft);
                 sp->xleft -= actual;
                 sp->xhead += actual;
         }
@@ -492,8 +492,8 @@ static void sixpack_receive_buf(struct tty_struct *tty,
 
         sp_put(sp);
         if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
-            && tty->driver->unthrottle)
-                tty->driver->unthrottle(tty);
+            && tty->ops->unthrottle)
+                tty->ops->unthrottle(tty);
 }
 
 /*
@@ -554,8 +554,8 @@ static void resync_tnc(unsigned long channel)
         /* resync the TNC */
 
         sp->led_state = 0x60;
-        sp->tty->driver->write(sp->tty, &sp->led_state, 1);
-        sp->tty->driver->write(sp->tty, &resync_cmd, 1);
+        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+        sp->tty->ops->write(sp->tty, &resync_cmd, 1);
 
 
         /* Start resync timer again -- the TNC might be still absent */
@@ -573,7 +573,7 @@ static inline int tnc_init(struct sixpack *sp)
 
         tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
 
-        sp->tty->driver->write(sp->tty, &inbyte, 1);
+        sp->tty->ops->write(sp->tty, &inbyte, 1);
 
         del_timer(&sp->resync_t);
         sp->resync_t.data = (unsigned long) sp;
@@ -601,6 +601,8 @@ static int sixpack_open(struct tty_struct *tty)
 
         if (!capable(CAP_NET_ADMIN))
                 return -EPERM;
+        if (tty->ops->write == NULL)
+                return -EOPNOTSUPP;
 
         dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup);
         if (!dev) {
@@ -914,9 +916,9 @@ static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
         } else { /* output watchdog char if idle */
                 if ((sp->status2 != 0) && (sp->duplex == 1)) {
                         sp->led_state = 0x70;
-                        sp->tty->driver->write(sp->tty, &sp->led_state, 1);
+                        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
                         sp->tx_enable = 1;
-                        actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2);
+                        actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
                         sp->xleft -= actual;
                         sp->xhead += actual;
                         sp->led_state = 0x60;
@@ -926,7 +928,7 @@ static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
         }
 
         /* needed to trigger the TNC watchdog */
-        sp->tty->driver->write(sp->tty, &sp->led_state, 1);
+        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 
         /* if the state byte has been received, the TNC is present,
            so the resync timer can be reset. */
@@ -956,12 +958,12 @@ static void decode_std_command(struct sixpack *sp, unsigned char cmd)
                         if ((sp->status & SIXP_RX_DCD_MASK) ==
                                 SIXP_RX_DCD_MASK) {
                                 sp->led_state = 0x68;
-                                sp->tty->driver->write(sp->tty, &sp->led_state, 1);
+                                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
                         }
                 } else {
                         sp->led_state = 0x60;
                         /* fill trailing bytes with zeroes */
-                        sp->tty->driver->write(sp->tty, &sp->led_state, 1);
+                        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
                         rest = sp->rx_count;
                         if (rest != 0)
                                  for (i = rest; i <= 3; i++)
diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index 30c9b3b0d131..ebcc5adee7cc 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -516,7 +516,7 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len)
         spin_unlock_bh(&ax->buflock);
 
         set_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags);
-        actual = ax->tty->driver->write(ax->tty, ax->xbuff, count);
+        actual = ax->tty->ops->write(ax->tty, ax->xbuff, count);
         ax->stats.tx_packets++;
         ax->stats.tx_bytes += actual;
 
@@ -546,7 +546,7 @@ static int ax_xmit(struct sk_buff *skb, struct net_device *dev)
                 }
 
                 printk(KERN_ERR "mkiss: %s: transmit timed out, %s?\n", dev->name,
-                       (ax->tty->driver->chars_in_buffer(ax->tty) || ax->xleft) ?
+                       (ax->tty->ops->chars_in_buffer(ax->tty) || ax->xleft) ?
                        "bad line quality" : "driver error");
 
                 ax->xleft = 0;
@@ -736,6 +736,8 @@ static int mkiss_open(struct tty_struct *tty)
 
         if (!capable(CAP_NET_ADMIN))
                 return -EPERM;
+        if (tty->ops->write == NULL)
+                return -EOPNOTSUPP;
 
         dev = alloc_netdev(sizeof(struct mkiss), "ax%d", ax_setup);
         if (!dev) {
@@ -754,8 +756,7 @@ static int mkiss_open(struct tty_struct *tty)
         tty->disc_data = ax;
         tty->receive_room = 65535;
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        tty_driver_flush_buffer(tty);
 
         /* Restore default settings */
         dev->type = ARPHRD_AX25;
@@ -936,8 +937,8 @@ static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 
         mkiss_put(ax);
         if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
-            && tty->driver->unthrottle)
-                tty->driver->unthrottle(tty);
+            && tty->ops->unthrottle)
+                tty->ops->unthrottle(tty);
 }
 
 /*
@@ -962,7 +963,7 @@ static void mkiss_write_wakeup(struct tty_struct *tty)
                 goto out;
         }
 
-        actual = tty->driver->write(tty, ax->xhead, ax->xleft);
+        actual = tty->ops->write(tty, ax->xhead, ax->xleft);
         ax->xleft -= actual;
         ax->xhead += actual;
 
diff --git a/drivers/net/irda/irtty-sir.c b/drivers/net/irda/irtty-sir.c
index fc753d7f674e..e6f40b7f9041 100644
--- a/drivers/net/irda/irtty-sir.c
+++ b/drivers/net/irda/irtty-sir.c
@@ -64,7 +64,7 @@ static int irtty_chars_in_buffer(struct sir_dev *dev)
         IRDA_ASSERT(priv != NULL, return -1;);
         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
 
-        return priv->tty->driver->chars_in_buffer(priv->tty);
+        return tty_chars_in_buffer(priv->tty);
 }
 
 /* Wait (sleep) until underlaying hardware finished transmission
@@ -93,10 +93,8 @@ static void irtty_wait_until_sent(struct sir_dev *dev)
         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
 
         tty = priv->tty;
-        if (tty->driver->wait_until_sent) {
-                lock_kernel();
-                tty->driver->wait_until_sent(tty, msecs_to_jiffies(100));
-                unlock_kernel();
+        if (tty->ops->wait_until_sent) {
+                tty->ops->wait_until_sent(tty, msecs_to_jiffies(100));
         }
         else {
                 msleep(USBSERIAL_TX_DONE_DELAY);
@@ -125,48 +123,14 @@ static int irtty_change_speed(struct sir_dev *dev, unsigned speed)
 
         tty = priv->tty;
 
-        lock_kernel();
+        mutex_lock(&tty->termios_mutex);
         old_termios = *(tty->termios);
         cflag = tty->termios->c_cflag;
-
-        cflag &= ~CBAUD;
-
-        IRDA_DEBUG(2, "%s(), Setting speed to %d\n", __FUNCTION__, speed);
-
-        switch (speed) {
-        case 1200:
-                cflag |= B1200;
-                break;
-        case 2400:
-                cflag |= B2400;
-                break;
-        case 4800:
-                cflag |= B4800;
-                break;
-        case 19200:
-                cflag |= B19200;
-                break;
-        case 38400:
-                cflag |= B38400;
-                break;
-        case 57600:
-                cflag |= B57600;
-                break;
-        case 115200:
-                cflag |= B115200;
-                break;
-        case 9600:
-        default:
-                cflag |= B9600;
-                break;
-        }       
-
-        tty->termios->c_cflag = cflag;
-        if (tty->driver->set_termios)
-                tty->driver->set_termios(tty, &old_termios);
-        unlock_kernel();
-
+        tty_encode_baud_rate(tty, speed, speed);
+        if (tty->ops->set_termios)
+                tty->ops->set_termios(tty, &old_termios);
         priv->io.speed = speed;
+        mutex_unlock(&tty->termios_mutex);
 
         return 0;
 }
@@ -202,8 +166,8 @@ static int irtty_set_dtr_rts(struct sir_dev *dev, int dtr, int rts)
          * This function is not yet defined for all tty driver, so
          * let's be careful... Jean II
          */
-        IRDA_ASSERT(priv->tty->driver->tiocmset != NULL, return -1;);
-        priv->tty->driver->tiocmset(priv->tty, NULL, set, clear);
+        IRDA_ASSERT(priv->tty->ops->tiocmset != NULL, return -1;);
+        priv->tty->ops->tiocmset(priv->tty, NULL, set, clear);
 
         return 0;
 }
@@ -225,17 +189,13 @@ static int irtty_do_write(struct sir_dev *dev, const unsigned char *ptr, size_t
         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
 
         tty = priv->tty;
-        if (!tty->driver->write)
+        if (!tty->ops->write)
                 return 0;
         tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
-        if (tty->driver->write_room) {
-                writelen = tty->driver->write_room(tty);
-                if (writelen > len)
-                        writelen = len;
-        }
-        else
+        writelen = tty_write_room(tty);
+        if (writelen > len)
                 writelen = len;
-        return tty->driver->write(tty, ptr, writelen);
+        return tty->ops->write(tty, ptr, writelen);
 }
 
 /* ------------------------------------------------------- */
@@ -321,7 +281,7 @@ static inline void irtty_stop_receiver(struct tty_struct *tty, int stop)
         struct ktermios old_termios;
         int cflag;
 
-        lock_kernel();
+        mutex_lock(&tty->termios_mutex);
         old_termios = *(tty->termios);
         cflag = tty->termios->c_cflag;
         
@@ -331,9 +291,9 @@ static inline void irtty_stop_receiver(struct tty_struct *tty, int stop)
                 cflag |= CREAD;
 
         tty->termios->c_cflag = cflag;
-        if (tty->driver->set_termios)
-                tty->driver->set_termios(tty, &old_termios);
-        unlock_kernel();
+        if (tty->ops->set_termios)
+                tty->ops->set_termios(tty, &old_termios);
+        mutex_unlock(&tty->termios_mutex);
 }
 
 /*****************************************************************/
@@ -359,8 +319,8 @@ static int irtty_start_dev(struct sir_dev *dev)
 
         tty = priv->tty;
 
-        if (tty->driver->start)
-                tty->driver->start(tty);
+        if (tty->ops->start)
+                tty->ops->start(tty);
         /* Make sure we can receive more data */
         irtty_stop_receiver(tty, FALSE);
 
@@ -388,8 +348,8 @@ static int irtty_stop_dev(struct sir_dev *dev)
 
         /* Make sure we don't receive more data */
         irtty_stop_receiver(tty, TRUE);
-        if (tty->driver->stop)
-                tty->driver->stop(tty);
+        if (tty->ops->stop)
+                tty->ops->stop(tty);
 
         mutex_unlock(&irtty_mutex);
 
@@ -483,11 +443,10 @@ static int irtty_open(struct tty_struct *tty)
 
         /* stop the underlying  driver */
         irtty_stop_receiver(tty, TRUE);
-        if (tty->driver->stop)
-                tty->driver->stop(tty);
+        if (tty->ops->stop)
+                tty->ops->stop(tty);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        tty_driver_flush_buffer(tty);
         
         /* apply mtt override */
         sir_tty_drv.qos_mtt_bits = qos_mtt_bits;
@@ -564,8 +523,8 @@ static void irtty_close(struct tty_struct *tty)
         /* Stop tty */
         irtty_stop_receiver(tty, TRUE);
         tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
-        if (tty->driver->stop)
-                tty->driver->stop(tty);
+        if (tty->ops->stop)
+                tty->ops->stop(tty);
 
         kfree(priv);
 
diff --git a/drivers/net/ppp_async.c b/drivers/net/ppp_async.c
index f023d5b67e6e..1c4b7e37912c 100644
--- a/drivers/net/ppp_async.c
+++ b/drivers/net/ppp_async.c
@@ -158,6 +158,9 @@ ppp_asynctty_open(struct tty_struct *tty)
         struct asyncppp *ap;
         int err;
 
+        if (tty->ops->write == NULL)
+                return -EOPNOTSUPP;
+
         err = -ENOMEM;
         ap = kzalloc(sizeof(*ap), GFP_KERNEL);
         if (!ap)
@@ -359,8 +362,8 @@ ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
                 tasklet_schedule(&ap->tsk);
         ap_put(ap);
         if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
-            && tty->driver->unthrottle)
-                tty->driver->unthrottle(tty);
+            && tty->ops->unthrottle)
+                tty->ops->unthrottle(tty);
 }
 
 static void
@@ -676,7 +679,7 @@ ppp_async_push(struct asyncppp *ap)
                 if (!tty_stuffed && ap->optr < ap->olim) {
                         avail = ap->olim - ap->optr;
                         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-                        sent = tty->driver->write(tty, ap->optr, avail);
+                        sent = tty->ops->write(tty, ap->optr, avail);
                         if (sent < 0)
                                 goto flush;     /* error, e.g. loss of CD */
                         ap->optr += sent;
diff --git a/drivers/net/ppp_synctty.c b/drivers/net/ppp_synctty.c
index 0d80fa546719..48ed5fdbfe18 100644
--- a/drivers/net/ppp_synctty.c
+++ b/drivers/net/ppp_synctty.c
@@ -207,6 +207,9 @@ ppp_sync_open(struct tty_struct *tty)
         struct syncppp *ap;
         int err;
 
+        if (tty->ops->write == NULL)
+                return -EOPNOTSUPP;
+
         ap = kzalloc(sizeof(*ap), GFP_KERNEL);
         err = -ENOMEM;
         if (!ap)
@@ -399,8 +402,8 @@ ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
                 tasklet_schedule(&ap->tsk);
         sp_put(ap);
         if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
-            && tty->driver->unthrottle)
-                tty->driver->unthrottle(tty);
+            && tty->ops->unthrottle)
+                tty->ops->unthrottle(tty);
 }
 
 static void
@@ -653,7 +656,7 @@ ppp_sync_push(struct syncppp *ap)
                         tty_stuffed = 0;
                 if (!tty_stuffed && ap->tpkt) {
                         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-                        sent = tty->driver->write(tty, ap->tpkt->data, ap->tpkt->len);
+                        sent = tty->ops->write(tty, ap->tpkt->data, ap->tpkt->len);
                         if (sent < 0)
                                 goto flush;     /* error, e.g. loss of CD */
                         if (sent < ap->tpkt->len) {
diff --git a/drivers/net/slip.c b/drivers/net/slip.c
index 5a55ede352f4..84af68fdb6c2 100644
--- a/drivers/net/slip.c
+++ b/drivers/net/slip.c
@@ -396,14 +396,14 @@ static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 
         /* Order of next two lines is *very* important.
          * When we are sending a little amount of data,
-         * the transfer may be completed inside driver.write()
+         * the transfer may be completed inside the ops->write()
          * routine, because it's running with interrupts enabled.
          * In this case we *never* got WRITE_WAKEUP event,
          * if we did not request it before write operation.
          *       14 Oct 1994  Dmitry Gorodchanin.
          */
         sl->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
-        actual = sl->tty->driver->write(sl->tty, sl->xbuff, count);
+        actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
 #ifdef SL_CHECK_TRANSMIT
         sl->dev->trans_start = jiffies;
 #endif
@@ -437,7 +437,7 @@ static void slip_write_wakeup(struct tty_struct *tty)
                 return;
         }
 
-        actual = tty->driver->write(tty, sl->xhead, sl->xleft);
+        actual = tty->ops->write(tty, sl->xhead, sl->xleft);
         sl->xleft -= actual;
         sl->xhead += actual;
 }
@@ -462,7 +462,7 @@ static void sl_tx_timeout(struct net_device *dev)
                 }
                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
                         dev->name,
-                        (sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft) ?
+                        (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
                                 "bad line quality" : "driver error");
                 sl->xleft = 0;
                 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
@@ -830,6 +830,9 @@ static int slip_open(struct tty_struct *tty)
         if (!capable(CAP_NET_ADMIN))
                 return -EPERM;
 
+        if (tty->ops->write == NULL)
+                return -EOPNOTSUPP;
+
         /* RTnetlink lock is misused here to serialize concurrent
            opens of slip channels. There are better ways, but it is
            the simplest one.
@@ -1432,7 +1435,7 @@ static void sl_outfill(unsigned long sls)
                         /* put END into tty queue. Is it right ??? */
                         if (!netif_queue_stopped(sl->dev)) {
                                 /* if device busy no outfill */
-                                sl->tty->driver->write(sl->tty, &s, 1);
+                                sl->tty->ops->write(sl->tty, &s, 1);
                         }
                 } else
                         set_bit(SLF_OUTWAIT, &sl->flags);
diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c
index 0f8aca8a4d43..249e18053d5f 100644
--- a/drivers/net/wan/x25_asy.c
+++ b/drivers/net/wan/x25_asy.c
@@ -17,7 +17,7 @@
 #include <linux/module.h>
 
 #include <asm/system.h>
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 #include <linux/bitops.h>
 #include <linux/string.h>
 #include <linux/mm.h>
@@ -95,7 +95,7 @@ static struct x25_asy *x25_asy_alloc(void)
                         x25_asy_devs[i] = dev;
                         return sl;
                 } else {
-                        printk("x25_asy_alloc() - register_netdev() failure.\n");
+                        printk(KERN_WARNING "x25_asy_alloc() - register_netdev() failure.\n");
                         free_netdev(dev);
                 }
         }
@@ -112,23 +112,22 @@ static void x25_asy_free(struct x25_asy *sl)
         kfree(sl->xbuff);
         sl->xbuff = NULL;
 
-        if (!test_and_clear_bit(SLF_INUSE, &sl->flags)) {
-                printk("%s: x25_asy_free for already free unit.\n", sl->dev->name);
-        }
+        if (!test_and_clear_bit(SLF_INUSE, &sl->flags))
+                printk(KERN_ERR "%s: x25_asy_free for already free unit.\n",
+                        sl->dev->name);
 }
 
 static int x25_asy_change_mtu(struct net_device *dev, int newmtu)
 {
         struct x25_asy *sl = dev->priv;
         unsigned char *xbuff, *rbuff;
-        int len = 2* newmtu;
+        int len = 2 * newmtu;
 
         xbuff = kmalloc(len + 4, GFP_ATOMIC);
         rbuff = kmalloc(len + 4, GFP_ATOMIC);
 
-        if (xbuff == NULL || rbuff == NULL)  
-        {
-                printk("%s: unable to grow X.25 buffers, MTU change cancelled.\n",
+        if (xbuff == NULL || rbuff == NULL) {
+                printk(KERN_WARNING "%s: unable to grow X.25 buffers, MTU change cancelled.\n",
                        dev->name);
                 kfree(xbuff);
                 kfree(rbuff);
@@ -193,25 +192,23 @@ static void x25_asy_bump(struct x25_asy *sl)
         int err;
 
         count = sl->rcount;
-        sl->stats.rx_bytes+=count;
-        
+        sl->stats.rx_bytes += count;
+
         skb = dev_alloc_skb(count+1);
-        if (skb == NULL)  
-        {
-                printk("%s: memory squeeze, dropping packet.\n", sl->dev->name);
+        if (skb == NULL) {
+                printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n",
+                        sl->dev->name);
                 sl->stats.rx_dropped++;
                 return;
         }
-        skb_push(skb,1);        /* LAPB internal control */
-        memcpy(skb_put(skb,count), sl->rbuff, count);
+        skb_push(skb, 1);       /* LAPB internal control */
+        memcpy(skb_put(skb, count), sl->rbuff, count);
         skb->protocol = x25_type_trans(skb, sl->dev);
-        if((err=lapb_data_received(skb->dev, skb))!=LAPB_OK)
-        {
+        err = lapb_data_received(skb->dev, skb);
+        if (err != LAPB_OK) {
                 kfree_skb(skb);
-                printk(KERN_DEBUG "x25_asy: data received err - %d\n",err);
-        }
-        else
-        {
+                printk(KERN_DEBUG "x25_asy: data received err - %d\n", err);
+        } else {
                 netif_rx(skb);
                 sl->dev->last_rx = jiffies;
                 sl->stats.rx_packets++;
@@ -224,10 +221,11 @@ static void x25_asy_encaps(struct x25_asy *sl, unsigned char *icp, int len)
         unsigned char *p;
         int actual, count, mtu = sl->dev->mtu;
 
-        if (len > mtu) 
-        {               /* Sigh, shouldn't occur BUT ... */
+        if (len > mtu) {
+                /* Sigh, shouldn't occur BUT ... */
                 len = mtu;
-                printk ("%s: truncating oversized transmit packet!\n", sl->dev->name);
+                printk(KERN_DEBUG "%s: truncating oversized transmit packet!\n",
+                                        sl->dev->name);
                 sl->stats.tx_dropped++;
                 x25_asy_unlock(sl);
                 return;
@@ -245,7 +243,7 @@ static void x25_asy_encaps(struct x25_asy *sl, unsigned char *icp, int len)
          *       14 Oct 1994  Dmitry Gorodchanin.
          */
         sl->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
-        actual = sl->tty->driver->write(sl->tty, sl->xbuff, count);
+        actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
         sl->xleft = count - actual;
         sl->xhead = sl->xbuff + actual;
         /* VSV */
@@ -265,8 +263,7 @@ static void x25_asy_write_wakeup(struct tty_struct *tty)
         if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
                 return;
 
-        if (sl->xleft <= 0)  
-        {
+        if (sl->xleft <= 0) {
                 /* Now serial buffer is almost free & we can start
                  * transmission of another packet */
                 sl->stats.tx_packets++;
@@ -275,14 +272,14 @@ static void x25_asy_write_wakeup(struct tty_struct *tty)
                 return;
         }
 
-        actual = tty->driver->write(tty, sl->xhead, sl->xleft);
+        actual = tty->ops->write(tty, sl->xhead, sl->xleft);
         sl->xleft -= actual;
         sl->xhead += actual;
 }
 
 static void x25_asy_timeout(struct net_device *dev)
 {
-        struct x25_asy *sl = (struct x25_asy*)(dev->priv);
+        struct x25_asy *sl = dev->priv;
 
         spin_lock(&sl->lock);
         if (netif_queue_stopped(dev)) {
@@ -290,7 +287,7 @@ static void x25_asy_timeout(struct net_device *dev)
                  *      14 Oct 1994 Dmitry Gorodchanin.
                  */
                 printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
-                       (sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft) ?
+                       (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
                        "bad line quality" : "driver error");
                 sl->xleft = 0;
                 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
@@ -303,31 +300,34 @@ static void x25_asy_timeout(struct net_device *dev)
 
 static int x25_asy_xmit(struct sk_buff *skb, struct net_device *dev)
 {
-        struct x25_asy *sl = (struct x25_asy*)(dev->priv);
+        struct x25_asy *sl = dev->priv;
         int err;
 
         if (!netif_running(sl->dev)) {
-                printk("%s: xmit call when iface is down\n", dev->name);
+                printk(KERN_ERR "%s: xmit call when iface is down\n",
+                        dev->name);
                 kfree_skb(skb);
                 return 0;
         }
-        
-        switch(skb->data[0])
-        {
-                case 0x00:break;
-                case 0x01: /* Connection request .. do nothing */
-                        if((err=lapb_connect_request(dev))!=LAPB_OK)
-                                printk(KERN_ERR "x25_asy: lapb_connect_request error - %d\n", err);
-                        kfree_skb(skb);
-                        return 0;
-                case 0x02: /* Disconnect request .. do nothing - hang up ?? */
-                        if((err=lapb_disconnect_request(dev))!=LAPB_OK)
-                                printk(KERN_ERR "x25_asy: lapb_disconnect_request error - %d\n", err);
-                default:
-                        kfree_skb(skb);
-                        return  0;
+
+        switch (skb->data[0]) {
+        case 0x00:
+                break;
+        case 0x01: /* Connection request .. do nothing */
+                err = lapb_connect_request(dev);
+                if (err != LAPB_OK)
+                        printk(KERN_ERR "x25_asy: lapb_connect_request error - %d\n", err);
+                kfree_skb(skb);
+                return 0;
+        case 0x02: /* Disconnect request .. do nothing - hang up ?? */
+                err = lapb_disconnect_request(dev);
+                if (err != LAPB_OK)
+                        printk(KERN_ERR "x25_asy: lapb_disconnect_request error - %d\n", err);
+        default:
+                kfree_skb(skb);
+                return  0;
         }
-        skb_pull(skb,1);        /* Remove control byte */
+        skb_pull(skb, 1);       /* Remove control byte */
         /*
          * If we are busy already- too bad.  We ought to be able
          * to queue things at this point, to allow for a little
@@ -338,10 +338,10 @@ static int x25_asy_xmit(struct sk_buff *skb, struct net_device *dev)
          * So, no queues !
          *        14 Oct 1994  Dmitry Gorodchanin.
          */
-        
-        if((err=lapb_data_request(dev,skb))!=LAPB_OK)
-        {
-                printk(KERN_ERR "lapbeth: lapb_data_request error - %d\n", err);
+
+        err = lapb_data_request(dev, skb);
+        if (err != LAPB_OK) {
+                printk(KERN_ERR "x25_asy: lapb_data_request error - %d\n", err);
                 kfree_skb(skb);
                 return 0;
         }
@@ -357,7 +357,7 @@ static int x25_asy_xmit(struct sk_buff *skb, struct net_device *dev)
  *      Called when I frame data arrives. We did the work above - throw it
  *      at the net layer.
  */
-  
+
 static int x25_asy_data_indication(struct net_device *dev, struct sk_buff *skb)
 {
         skb->dev->last_rx = jiffies;
@@ -369,24 +369,22 @@ static int x25_asy_data_indication(struct net_device *dev, struct sk_buff *skb)
  *      busy cases too well. Its tricky to see how to do this nicely -
  *      perhaps lapb should allow us to bounce this ?
  */
- 
+
 static void x25_asy_data_transmit(struct net_device *dev, struct sk_buff *skb)
 {
-        struct x25_asy *sl=dev->priv;
-        
+        struct x25_asy *sl = dev->priv;
+
         spin_lock(&sl->lock);
-        if (netif_queue_stopped(sl->dev) || sl->tty == NULL)
-        {
+        if (netif_queue_stopped(sl->dev) || sl->tty == NULL) {
                 spin_unlock(&sl->lock);
                 printk(KERN_ERR "x25_asy: tbusy drop\n");
                 kfree_skb(skb);
                 return;
         }
         /* We were not busy, so we are now... :-) */
-        if (skb != NULL) 
-        {
+        if (skb != NULL) {
                 x25_asy_lock(sl);
-                sl->stats.tx_bytes+=skb->len;
+                sl->stats.tx_bytes += skb->len;
                 x25_asy_encaps(sl, skb->data, skb->len);
                 dev_kfree_skb(skb);
         }
@@ -396,15 +394,16 @@ static void x25_asy_data_transmit(struct net_device *dev, struct sk_buff *skb)
 /*
  *      LAPB connection establish/down information.
  */
- 
+
 static void x25_asy_connected(struct net_device *dev, int reason)
 {
         struct x25_asy *sl = dev->priv;
         struct sk_buff *skb;
         unsigned char *ptr;
 
-        if ((skb = dev_alloc_skb(1)) == NULL) {
-                printk(KERN_ERR "lapbeth: out of memory\n");
+        skb = dev_alloc_skb(1);
+        if (skb == NULL) {
+                printk(KERN_ERR "x25_asy: out of memory\n");
                 return;
         }
 
@@ -422,7 +421,8 @@ static void x25_asy_disconnected(struct net_device *dev, int reason)
         struct sk_buff *skb;
         unsigned char *ptr;
 
-        if ((skb = dev_alloc_skb(1)) == NULL) {
+        skb = dev_alloc_skb(1);
+        if (skb == NULL) {
                 printk(KERN_ERR "x25_asy: out of memory\n");
                 return;
         }
@@ -449,7 +449,7 @@ static struct lapb_register_struct x25_asy_callbacks = {
 /* Open the low-level part of the X.25 channel. Easy! */
 static int x25_asy_open(struct net_device *dev)
 {
-        struct x25_asy *sl = (struct x25_asy*)(dev->priv);
+        struct x25_asy *sl = dev->priv;
         unsigned long len;
         int err;
 
@@ -466,13 +466,11 @@ static int x25_asy_open(struct net_device *dev)
         len = dev->mtu * 2;
 
         sl->rbuff = kmalloc(len + 4, GFP_KERNEL);
-        if (sl->rbuff == NULL)   {
+        if (sl->rbuff == NULL)
                 goto norbuff;
-        }
         sl->xbuff = kmalloc(len + 4, GFP_KERNEL);
-        if (sl->xbuff == NULL)   {
+        if (sl->xbuff == NULL)
                 goto noxbuff;
-        }
 
         sl->buffsize = len;
         sl->rcount   = 0;
@@ -480,11 +478,12 @@ static int x25_asy_open(struct net_device *dev)
         sl->flags   &= (1 << SLF_INUSE);      /* Clear ESCAPE & ERROR flags */
 
         netif_start_queue(dev);
-                        
+
         /*
          *      Now attach LAPB
          */
-        if((err=lapb_register(dev, &x25_asy_callbacks))==LAPB_OK)
+        err = lapb_register(dev, &x25_asy_callbacks);
+        if (err == LAPB_OK)
                 return 0;
 
         /* Cleanup */
@@ -499,18 +498,20 @@ norbuff:
 /* Close the low-level part of the X.25 channel. Easy! */
 static int x25_asy_close(struct net_device *dev)
 {
-        struct x25_asy *sl = (struct x25_asy*)(dev->priv);
+        struct x25_asy *sl = dev->priv;
         int err;
 
         spin_lock(&sl->lock);
-        if (sl->tty) 
+        if (sl->tty)
                 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
 
         netif_stop_queue(dev);
         sl->rcount = 0;
         sl->xleft  = 0;
-        if((err=lapb_unregister(dev))!=LAPB_OK)
-                printk(KERN_ERR "x25_asy_close: lapb_unregister error -%d\n",err);
+        err = lapb_unregister(dev);
+        if (err != LAPB_OK)
+                printk(KERN_ERR "x25_asy_close: lapb_unregister error -%d\n",
+                        err);
         spin_unlock(&sl->lock);
         return 0;
 }
@@ -521,8 +522,9 @@ static int x25_asy_close(struct net_device *dev)
  * a block of X.25 data has been received, which can now be decapsulated
  * and sent on to some IP layer for further processing.
  */
- 
-static void x25_asy_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
+
+static void x25_asy_receive_buf(struct tty_struct *tty,
+                                const unsigned char *cp, char *fp, int count)
 {
         struct x25_asy *sl = (struct x25_asy *) tty->disc_data;
 
@@ -533,9 +535,8 @@ static void x25_asy_receive_buf(struct tty_struct *tty, const unsigned char *cp,
         /* Read the characters out of the buffer */
         while (count--) {
                 if (fp && *fp++) {
-                        if (!test_and_set_bit(SLF_ERROR, &sl->flags))  {
+                        if (!test_and_set_bit(SLF_ERROR, &sl->flags))
                                 sl->stats.rx_errors++;
-                        }
                         cp++;
                         continue;
                 }
@@ -556,31 +557,31 @@ static int x25_asy_open_tty(struct tty_struct *tty)
         struct x25_asy *sl = (struct x25_asy *) tty->disc_data;
         int err;
 
+        if (tty->ops->write == NULL)
+                return -EOPNOTSUPP;
+
         /* First make sure we're not already connected. */
-        if (sl && sl->magic == X25_ASY_MAGIC) {
+        if (sl && sl->magic == X25_ASY_MAGIC)
                 return -EEXIST;
-        }
 
         /* OK.  Find a free X.25 channel to use. */
-        if ((sl = x25_asy_alloc()) == NULL) {
+        sl = x25_asy_alloc();
+        if (sl == NULL)
                 return -ENFILE;
-        }
 
         sl->tty = tty;
         tty->disc_data = sl;
         tty->receive_room = 65536;
-        if (tty->driver->flush_buffer)  {
-                tty->driver->flush_buffer(tty);
-        }
+        tty_driver_flush_buffer(tty);
         tty_ldisc_flush(tty);
 
         /* Restore default settings */
         sl->dev->type = ARPHRD_X25;
-        
+
         /* Perform the low-level X.25 async init */
-        if ((err = x25_asy_open(sl->dev)))
+        err = x25_asy_open(sl->dev);
+        if (err)
                 return err;
-
         /* Done.  We have linked the TTY line to a channel. */
         return sl->dev->base_addr;
 }
@@ -601,9 +602,7 @@ static void x25_asy_close_tty(struct tty_struct *tty)
                 return;
 
         if (sl->dev->flags & IFF_UP)
-        {
-                (void) dev_close(sl->dev);
-        }
+                dev_close(sl->dev);
 
         tty->disc_data = NULL;
         sl->tty = NULL;
@@ -613,8 +612,7 @@ static void x25_asy_close_tty(struct tty_struct *tty)
 
 static struct net_device_stats *x25_asy_get_stats(struct net_device *dev)
 {
-        struct x25_asy *sl = (struct x25_asy*)(dev->priv);
-
+        struct x25_asy *sl = dev->priv;
         return &sl->stats;
 }
 
@@ -641,21 +639,19 @@ int x25_asy_esc(unsigned char *s, unsigned char *d, int len)
          * character sequence, according to the X.25 protocol.
          */
 
-        while (len-- > 0) 
-        {
-                switch(c = *s++) 
-                {
-                        case X25_END:
-                                *ptr++ = X25_ESC;
-                                *ptr++ = X25_ESCAPE(X25_END);
-                                break;
-                        case X25_ESC:
-                                *ptr++ = X25_ESC;
-                                *ptr++ = X25_ESCAPE(X25_ESC);
-                                break;
-                         default:
-                                *ptr++ = c;
-                                break;
+        while (len-- > 0) {
+                switch (c = *s++) {
+                case X25_END:
+                        *ptr++ = X25_ESC;
+                        *ptr++ = X25_ESCAPE(X25_END);
+                        break;
+                case X25_ESC:
+                        *ptr++ = X25_ESC;
+                        *ptr++ = X25_ESCAPE(X25_ESC);
+                        break;
+                default:
+                        *ptr++ = c;
+                        break;
                 }
         }
         *ptr++ = X25_END;
@@ -665,31 +661,25 @@ int x25_asy_esc(unsigned char *s, unsigned char *d, int len)
 static void x25_asy_unesc(struct x25_asy *sl, unsigned char s)
 {
 
-        switch(s) 
-        {
-                case X25_END:
-                        if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && (sl->rcount > 2))  
-                        {
-                                x25_asy_bump(sl);
-                        }
-                        clear_bit(SLF_ESCAPE, &sl->flags);
-                        sl->rcount = 0;
-                        return;
-
-                case X25_ESC:
-                        set_bit(SLF_ESCAPE, &sl->flags);
-                        return;
-                        
-                case X25_ESCAPE(X25_ESC):
-                case X25_ESCAPE(X25_END):
-                        if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
-                                s = X25_UNESCAPE(s);
-                        break;
-        }
-        if (!test_bit(SLF_ERROR, &sl->flags))  
-        {
-                if (sl->rcount < sl->buffsize)  
-                {
+        switch (s) {
+        case X25_END:
+                if (!test_and_clear_bit(SLF_ERROR, &sl->flags)
+                        && sl->rcount > 2)
+                        x25_asy_bump(sl);
+                clear_bit(SLF_ESCAPE, &sl->flags);
+                sl->rcount = 0;
+                return;
+        case X25_ESC:
+                set_bit(SLF_ESCAPE, &sl->flags);
+                return;
+        case X25_ESCAPE(X25_ESC):
+        case X25_ESCAPE(X25_END):
+                if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
+                        s = X25_UNESCAPE(s);
+                break;
+        }
+        if (!test_bit(SLF_ERROR, &sl->flags)) {
+                if (sl->rcount < sl->buffsize) {
                         sl->rbuff[sl->rcount++] = s;
                         return;
                 }
@@ -709,7 +699,7 @@ static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,
         if (!sl || sl->magic != X25_ASY_MAGIC)
                 return -EINVAL;
 
-        switch(cmd) {
+        switch (cmd) {
         case SIOCGIFNAME:
                 if (copy_to_user((void __user *)arg, sl->dev->name,
                                         strlen(sl->dev->name) + 1))
@@ -724,8 +714,8 @@ static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,
 
 static int x25_asy_open_dev(struct net_device *dev)
 {
-        struct x25_asy *sl = (struct x25_asy*)(dev->priv);
-        if(sl->tty==NULL)
+        struct x25_asy *sl = dev->priv;
+        if (sl->tty == NULL)
                 return -ENODEV;
         return 0;
 }
@@ -741,9 +731,9 @@ static void x25_asy_setup(struct net_device *dev)
         set_bit(SLF_INUSE, &sl->flags);
 
         /*
-         *      Finish setting up the DEVICE info. 
+         *      Finish setting up the DEVICE info.
          */
-         
+
         dev->mtu                = SL_MTU;
         dev->hard_start_xmit    = x25_asy_xmit;
         dev->tx_timeout         = x25_asy_timeout;
@@ -778,9 +768,10 @@ static int __init init_x25_asy(void)
                 x25_asy_maxdev = 4; /* Sanity */
 
         printk(KERN_INFO "X.25 async: version 0.00 ALPHA "
-                        "(dynamic channels, max=%d).\n", x25_asy_maxdev );
+                        "(dynamic channels, max=%d).\n", x25_asy_maxdev);
 
-        x25_asy_devs = kcalloc(x25_asy_maxdev, sizeof(struct net_device*), GFP_KERNEL);
+        x25_asy_devs = kcalloc(x25_asy_maxdev, sizeof(struct net_device *),
+                                GFP_KERNEL);
         if (!x25_asy_devs) {
                 printk(KERN_WARNING "X25 async: Can't allocate x25_asy_ctrls[] "
                                 "array! Uaargh! (-> No X.25 available)\n");
@@ -802,7 +793,7 @@ static void __exit exit_x25_asy(void)
                         struct x25_asy *sl = dev->priv;
 
                         spin_lock_bh(&sl->lock);
-                        if (sl->tty) 
+                        if (sl->tty)
                                 tty_hangup(sl->tty);
 
                         spin_unlock_bh(&sl->lock);
diff --git a/drivers/serial/kgdboc.c b/drivers/serial/kgdboc.c
index 9cf03327386a..eadc1ab6bbce 100644
--- a/drivers/serial/kgdboc.c
+++ b/drivers/serial/kgdboc.c
@@ -96,12 +96,14 @@ static void cleanup_kgdboc(void)
 
 static int kgdboc_get_char(void)
 {
-        return kgdb_tty_driver->poll_get_char(kgdb_tty_driver, kgdb_tty_line);
+        return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver,
+                                                kgdb_tty_line);
 }
 
 static void kgdboc_put_char(u8 chr)
 {
-        kgdb_tty_driver->poll_put_char(kgdb_tty_driver, kgdb_tty_line, chr);
+        kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver,
+                                        kgdb_tty_line, chr);
 }
 
 static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 6c7a5cf76582..1e2b9d826f69 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -532,15 +532,25 @@ uart_write(struct tty_struct *tty, const unsigned char *buf, int count)
 static int uart_write_room(struct tty_struct *tty)
 {
         struct uart_state *state = tty->driver_data;
+        unsigned long flags;
+        int ret;
 
-        return uart_circ_chars_free(&state->info->xmit);
+        spin_lock_irqsave(&state->port->lock, flags);
+        ret = uart_circ_chars_free(&state->info->xmit);
+        spin_unlock_irqrestore(&state->port->lock, flags);
+        return ret;
 }
 
 static int uart_chars_in_buffer(struct tty_struct *tty)
 {
         struct uart_state *state = tty->driver_data;
+        unsigned long flags;
+        int ret;
 
-        return uart_circ_chars_pending(&state->info->xmit);
+        spin_lock_irqsave(&state->port->lock, flags);
+        ret = uart_circ_chars_pending(&state->info->xmit);
+        spin_unlock_irqrestore(&state->port->lock, flags);
+        return ret;
 }
 
 static void uart_flush_buffer(struct tty_struct *tty)
@@ -622,6 +632,11 @@ static int uart_get_info(struct uart_state *state,
         struct serial_struct tmp;
 
         memset(&tmp, 0, sizeof(tmp));
+
+        /* Ensure the state we copy is consistent and no hardware changes
+           occur as we go */
+        mutex_lock(&state->mutex);
+
         tmp.type            = port->type;
         tmp.line            = port->line;
         tmp.port            = port->iobase;
@@ -641,6 +656,8 @@ static int uart_get_info(struct uart_state *state,
         tmp.iomem_reg_shift = port->regshift;
         tmp.iomem_base      = (void *)(unsigned long)port->mapbase;
 
+        mutex_unlock(&state->mutex);
+
         if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
                 return -EFAULT;
         return 0;
@@ -918,14 +935,12 @@ static void uart_break_ctl(struct tty_struct *tty, int break_state)
         struct uart_state *state = tty->driver_data;
         struct uart_port *port = state->port;
 
-        lock_kernel();
         mutex_lock(&state->mutex);
 
         if (port->type != PORT_UNKNOWN)
                 port->ops->break_ctl(port, break_state);
 
         mutex_unlock(&state->mutex);
-        unlock_kernel();
 }
 
 static int uart_do_autoconfig(struct uart_state *state)
@@ -1074,7 +1089,6 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
         int ret = -ENOIOCTLCMD;
 
 
-        lock_kernel();
         /*
          * These ioctls don't rely on the hardware to be present.
          */
@@ -1144,10 +1158,9 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
                 break;
         }
         }
- out_up:
+out_up:
         mutex_unlock(&state->mutex);
- out:
-        unlock_kernel();
+out:
         return ret;
 }
 
@@ -1173,7 +1186,6 @@ static void uart_set_termios(struct tty_struct *tty,
                 return;
         }
 
-        lock_kernel();
         uart_change_speed(state, old_termios);
 
         /* Handle transition to B0 status */
@@ -1206,7 +1218,6 @@ static void uart_set_termios(struct tty_struct *tty,
                 }
                 spin_unlock_irqrestore(&state->port->lock, flags);
         }
-        unlock_kernel();
 #if 0
         /*
          * No need to wake up processes in open wait, since they
@@ -1322,11 +1333,11 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
         struct uart_port *port = state->port;
         unsigned long char_time, expire;
 
-        BUG_ON(!kernel_locked());
-
         if (port->type == PORT_UNKNOWN || port->fifosize == 0)
                 return;
 
+        lock_kernel();
+
         /*
          * Set the check interval to be 1/5 of the estimated time to
          * send a single character, and make it at least 1.  The check
@@ -1372,6 +1383,7 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
                         break;
         }
         set_current_state(TASK_RUNNING); /* might not be needed */
+        unlock_kernel();
 }
 
 /*
@@ -2085,7 +2097,9 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
                 int ret;
 
                 uart_change_pm(state, 0);
+                spin_lock_irq(&port->lock);
                 ops->set_mctrl(port, 0);
+                spin_unlock_irq(&port->lock);
                 ret = ops->startup(port);
                 if (ret == 0) {
                         uart_change_speed(state, NULL);
diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c
index d17d1645714f..04a56f300ea6 100644
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -1421,8 +1421,7 @@ static void digi_close(struct usb_serial_port *port, struct file *filp)
                 tty_wait_until_sent(tty, DIGI_CLOSE_TIMEOUT);
 
         /* flush driver and line discipline buffers */
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        tty_driver_flush_buffer(tty);
         tty_ldisc_flush(tty);
 
         if (port->serial->dev) {
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index a9934a3f9845..0cb0d77dc429 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -296,16 +296,14 @@ static int serial_write (struct tty_struct * tty, const unsigned char *buf, int
         struct usb_serial_port *port = tty->driver_data;
         int retval = -ENODEV;
 
-        if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
+        if (port->serial->dev->state == USB_STATE_NOTATTACHED)
                 goto exit;
 
         dbg("%s - port %d, %d byte(s)", __func__, port->number, count);
 
-        if (!port->open_count) {
-                retval = -EINVAL;
-                dbg("%s - port not opened", __func__);
-                goto exit;
-        }
+        /* open_count is managed under the mutex lock for the tty so cannot
+           drop to zero until after the last close completes */
+        WARN_ON(!port->open_count);
 
         /* pass on to the driver specific version of this function */
         retval = port->serial->type->write(port, buf, count);
@@ -317,61 +315,28 @@ exit:
 static int serial_write_room (struct tty_struct *tty) 
 {
         struct usb_serial_port *port = tty->driver_data;
-        int retval = -ENODEV;
-
-        if (!port)
-                goto exit;
-
         dbg("%s - port %d", __func__, port->number);
-
-        if (!port->open_count) {
-                dbg("%s - port not open", __func__);
-                goto exit;
-        }
-
+        WARN_ON(!port->open_count);
         /* pass on to the driver specific version of this function */
-        retval = port->serial->type->write_room(port);
-
-exit:
-        return retval;
+        return port->serial->type->write_room(port);
 }
 
 static int serial_chars_in_buffer (struct tty_struct *tty) 
 {
         struct usb_serial_port *port = tty->driver_data;
-        int retval = -ENODEV;
-
-        if (!port)
-                goto exit;
-
         dbg("%s = port %d", __func__, port->number);
 
-        if (!port->open_count) {
-                dbg("%s - port not open", __func__);
-                goto exit;
-        }
-
+        WARN_ON(!port->open_count);
         /* pass on to the driver specific version of this function */
-        retval = port->serial->type->chars_in_buffer(port);
-
-exit:
-        return retval;
+        return port->serial->type->chars_in_buffer(port);
 }
 
 static void serial_throttle (struct tty_struct * tty)
 {
         struct usb_serial_port *port = tty->driver_data;
-
-        if (!port)
-                return;
-
         dbg("%s - port %d", __func__, port->number);
 
-        if (!port->open_count) {
-                dbg ("%s - port not open", __func__);
-                return;
-        }
-
+        WARN_ON(!port->open_count);
         /* pass on to the driver specific version of this function */
         if (port->serial->type->throttle)
                 port->serial->type->throttle(port);
@@ -380,17 +345,9 @@ static void serial_throttle (struct tty_struct * tty)
 static void serial_unthrottle (struct tty_struct * tty)
 {
         struct usb_serial_port *port = tty->driver_data;
-
-        if (!port)
-                return;
-
         dbg("%s - port %d", __func__, port->number);
 
-        if (!port->open_count) {
-                dbg("%s - port not open", __func__);
-                return;
-        }
-
+        WARN_ON(!port->open_count);
         /* pass on to the driver specific version of this function */
         if (port->serial->type->unthrottle)
                 port->serial->type->unthrottle(port);
@@ -401,42 +358,27 @@ static int serial_ioctl (struct tty_struct *tty, struct file * file, unsigned in
         struct usb_serial_port *port = tty->driver_data;
         int retval = -ENODEV;
 
-        lock_kernel();
-        if (!port)
-                goto exit;
-
         dbg("%s - port %d, cmd 0x%.4x", __func__, port->number, cmd);
 
-        /* Caution - port->open_count is BKL protected */
-        if (!port->open_count) {
-                dbg ("%s - port not open", __func__);
-                goto exit;
-        }
+        WARN_ON(!port->open_count);
 
         /* pass on to the driver specific version of this function if it is available */
-        if (port->serial->type->ioctl)
+        if (port->serial->type->ioctl) {
+                lock_kernel();
                 retval = port->serial->type->ioctl(port, file, cmd, arg);
+                unlock_kernel();
+        }
         else
                 retval = -ENOIOCTLCMD;
-exit:
-        unlock_kernel();
         return retval;
 }
 
 static void serial_set_termios (struct tty_struct *tty, struct ktermios * old)
 {
         struct usb_serial_port *port = tty->driver_data;
-
-        if (!port)
-                return;
-
         dbg("%s - port %d", __func__, port->number);
 
-        if (!port->open_count) {
-                dbg("%s - port not open", __func__);
-                return;
-        }
-
+        WARN_ON(!port->open_count);
         /* pass on to the driver specific version of this function if it is available */
         if (port->serial->type->set_termios)
                 port->serial->type->set_termios(port, old);
@@ -448,24 +390,15 @@ static void serial_break (struct tty_struct *tty, int break_state)
 {
         struct usb_serial_port *port = tty->driver_data;
 
-        lock_kernel();
-        if (!port) {
-                unlock_kernel();
-                return;
-        }
-
         dbg("%s - port %d", __func__, port->number);
 
-        if (!port->open_count) {
-                dbg("%s - port not open", __func__);
-                unlock_kernel();
-                return;
-        }
-
+        WARN_ON(!port->open_count);
         /* pass on to the driver specific version of this function if it is available */
-        if (port->serial->type->break_ctl)
+        if (port->serial->type->break_ctl) {
+                lock_kernel();
                 port->serial->type->break_ctl(port, break_state);
-        unlock_kernel();
+                unlock_kernel();
+        }
 }
 
 static int serial_read_proc (char *page, char **start, off_t off, int count, int *eof, void *data)
@@ -519,19 +452,11 @@ static int serial_tiocmget (struct tty_struct *tty, struct file *file)
 {
         struct usb_serial_port *port = tty->driver_data;
 
-        if (!port)
-                return -ENODEV;
-
         dbg("%s - port %d", __func__, port->number);
 
-        if (!port->open_count) {
-                dbg("%s - port not open", __func__);
-                return -ENODEV;
-        }
-
+        WARN_ON(!port->open_count);
         if (port->serial->type->tiocmget)
                 return port->serial->type->tiocmget(port, file);
-
         return -EINVAL;
 }
 
@@ -540,19 +465,11 @@ static int serial_tiocmset (struct tty_struct *tty, struct file *file,
 {
         struct usb_serial_port *port = tty->driver_data;
 
-        if (!port)
-                return -ENODEV;
-
         dbg("%s - port %d", __func__, port->number);
 
-        if (!port->open_count) {
-                dbg("%s - port not open", __func__);
-                return -ENODEV;
-        }
-
+        WARN_ON(!port->open_count);
         if (port->serial->type->tiocmset)
                 return port->serial->type->tiocmset(port, file, set, clear);
-
         return -EINVAL;
 }
 
diff --git a/drivers/usb/serial/whiteheat.c b/drivers/usb/serial/whiteheat.c
index e96bf8663ffc..f07e8a4c1f3d 100644
--- a/drivers/usb/serial/whiteheat.c
+++ b/drivers/usb/serial/whiteheat.c
@@ -673,15 +673,13 @@ static void whiteheat_close(struct usb_serial_port *port, struct file * filp)
         }
 */
 
-        if (port->tty->driver->flush_buffer)
-                port->tty->driver->flush_buffer(port->tty);
+        tty_driver_flush_buffer(port->tty);
         tty_ldisc_flush(port->tty);
 
         firm_report_tx_done(port);
 
         firm_close(port);
 
-printk(KERN_ERR"Before processing rx_urbs_submitted.\n");
         /* shutdown our bulk reads and writes */
         mutex_lock(&info->deathwarrant);
         spin_lock_irq(&info->lock);
diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index 9663e8776724..97dba0d92348 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -1053,7 +1053,7 @@ static int vt_check(struct file *file)
         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
                 return -EINVAL;
                                                         
-        if (tty->driver->ioctl != vt_ioctl)
+        if (tty->ops->ioctl != vt_ioctl)
                 return -EINVAL;
 
         vc = (struct vc_data *)tty->driver_data;
diff --git a/fs/proc/proc_tty.c b/fs/proc/proc_tty.c
index ac26ccc25f42..21f490f5d65c 100644
--- a/fs/proc/proc_tty.c
+++ b/fs/proc/proc_tty.c
@@ -192,16 +192,14 @@ void proc_tty_register_driver(struct tty_driver *driver)
 {
         struct proc_dir_entry *ent;
                 
-        if ((!driver->read_proc && !driver->write_proc) ||
-            !driver->driver_name ||
+        if (!driver->ops->read_proc || !driver->driver_name ||
             driver->proc_entry)
                 return;
 
         ent = create_proc_entry(driver->driver_name, 0, proc_tty_driver);
         if (!ent)
                 return;
-        ent->read_proc = driver->read_proc;
-        ent->write_proc = driver->write_proc;
+        ent->read_proc = driver->ops->read_proc;
         ent->owner = driver->owner;
         ent->data = driver;
 
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 2699298b00ef..c36a76da2ae2 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -177,9 +177,13 @@ struct signal_struct;
  * size each time the window is created or resized anyway.
  *                                              - TYT, 9/14/92
  */
+
+struct tty_operations;
+
 struct tty_struct {
         int     magic;
         struct tty_driver *driver;
+        const struct tty_operations *ops;
         int index;
         struct tty_ldisc ldisc;
         struct mutex termios_mutex;
@@ -295,6 +299,10 @@ extern void tty_unregister_device(struct tty_driver *driver, unsigned index);
 extern int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp,
                              int buflen);
 extern void tty_write_message(struct tty_struct *tty, char *msg);
+extern int tty_put_char(struct tty_struct *tty, unsigned char c);
+extern int tty_chars_in_buffer(struct tty_struct *tty);
+extern int tty_write_room(struct tty_struct *tty);
+extern void tty_driver_flush_buffer(struct tty_struct *tty);
 
 extern int is_current_pgrp_orphaned(void);
 extern struct pid *tty_get_pgrp(struct tty_struct *tty);
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 21f69aca4505..f80d73b690f6 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -12,11 +12,15 @@
  *      This routine is called when a particular tty device is opened.
  *      This routine is mandatory; if this routine is not filled in,
  *      the attempted open will fail with ENODEV.
+ *
+ *      Required method.
  *     
  * void (*close)(struct tty_struct * tty, struct file * filp);
  *
  *      This routine is called when a particular tty device is closed.
  *
+ *      Required method.
+ *
  * int (*write)(struct tty_struct * tty,
  *               const unsigned char *buf, int count);
  *
@@ -26,7 +30,9 @@
  *      number of characters actually accepted for writing.  This
  *      routine is mandatory.
  *
- * void (*put_char)(struct tty_struct *tty, unsigned char ch);
+ *      Optional: Required for writable devices.
+ *
+ * int (*put_char)(struct tty_struct *tty, unsigned char ch);
  *
  *      This routine is called by the kernel to write a single
  *      character to the tty device.  If the kernel uses this routine,
@@ -34,10 +40,18 @@
  *      done stuffing characters into the driver.  If there is no room
  *      in the queue, the character is ignored.
  *
+ *      Optional: Kernel will use the write method if not provided.
+ *
+ *      Note: Do not call this function directly, call tty_put_char
+ *
  * void (*flush_chars)(struct tty_struct *tty);
  *
  *      This routine is called by the kernel after it has written a
  *      series of characters to the tty device using put_char().  
+ *
+ *      Optional:
+ *
+ *      Note: Do not call this function directly, call tty_driver_flush_chars
  * 
  * int  (*write_room)(struct tty_struct *tty);
  *
@@ -45,6 +59,10 @@
  *      will accept for queuing to be written.  This number is subject
  *      to change as output buffers get emptied, or if the output flow
  *      control is acted.
+ *
+ *      Required if write method is provided else not needed.
+ *
+ *      Note: Do not call this function directly, call tty_write_room
  * 
  * int  (*ioctl)(struct tty_struct *tty, struct file * file,
  *          unsigned int cmd, unsigned long arg);
@@ -53,22 +71,29 @@
  *      device-specific ioctl's.  If the ioctl number passed in cmd
  *      is not recognized by the driver, it should return ENOIOCTLCMD.
  *
+ *      Optional
+ *
  * long (*compat_ioctl)(struct tty_struct *tty, struct file * file,
  *                      unsigned int cmd, unsigned long arg);
  *
  *      implement ioctl processing for 32 bit process on 64 bit system
+ *
+ *      Optional
  * 
  * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
  *
  *      This routine allows the tty driver to be notified when
- *      device's termios settings have changed.  Note that a
- *      well-designed tty driver should be prepared to accept the case
- *      where old == NULL, and try to do something rational.
+ *      device's termios settings have changed.
+ *
+ *      Optional: Called under the termios lock
+ *
  *
  * void (*set_ldisc)(struct tty_struct *tty);
  *
  *      This routine allows the tty driver to be notified when the
  *      device's termios settings have changed.
+ *
+ *      Optional: Called under BKL (currently)
  * 
  * void (*throttle)(struct tty_struct * tty);
  *
@@ -86,17 +111,27 @@
  *
  *      This routine notifies the tty driver that it should stop
  *      outputting characters to the tty device.  
+ *
+ *      Optional:
+ *
+ *      Note: Call stop_tty not this method.
  * 
  * void (*start)(struct tty_struct *tty);
  *
  *      This routine notifies the tty driver that it resume sending
  *      characters to the tty device.
+ *
+ *      Optional:
+ *
+ *      Note: Call start_tty not this method.
  * 
  * void (*hangup)(struct tty_struct *tty);
  *
  *      This routine notifies the tty driver that it should hangup the
  *      tty device.
  *
+ *      Required:
+ *
  * void (*break_ctl)(struct tty_stuct *tty, int state);
  *
  *      This optional routine requests the tty driver to turn on or
@@ -106,18 +141,26 @@
  *
  *      If this routine is implemented, the high-level tty driver will
  *      handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,
- *      TIOCCBRK.  Otherwise, these ioctls will be passed down to the
- *      driver to handle.
+ *      TIOCCBRK.
+ *
+ *      Optional: Required for TCSBRK/BRKP/etc handling.
  *
  * void (*wait_until_sent)(struct tty_struct *tty, int timeout);
  * 
  *      This routine waits until the device has written out all of the
  *      characters in its transmitter FIFO.
  *
+ *      Optional: If not provided the device is assumed to have no FIFO
+ *
+ *      Note: Usually correct to call tty_wait_until_sent
+ *
  * void (*send_xchar)(struct tty_struct *tty, char ch);
  *
  *      This routine is used to send a high-priority XON/XOFF
  *      character to the device.
+ *
+ *      Optional: If not provided then the write method is called under
+ *      the atomic write lock to keep it serialized with the ldisc.
  */
 
 #include <linux/fs.h>
@@ -132,7 +175,7 @@ struct tty_operations {
         void (*close)(struct tty_struct * tty, struct file * filp);
         int  (*write)(struct tty_struct * tty,
                       const unsigned char *buf, int count);
-        void (*put_char)(struct tty_struct *tty, unsigned char ch);
+        int  (*put_char)(struct tty_struct *tty, unsigned char ch);
         void (*flush_chars)(struct tty_struct *tty);
         int  (*write_room)(struct tty_struct *tty);
         int  (*chars_in_buffer)(struct tty_struct *tty);
@@ -153,8 +196,6 @@ struct tty_operations {
         void (*send_xchar)(struct tty_struct *tty, char ch);
         int (*read_proc)(char *page, char **start, off_t off,
                           int count, int *eof, void *data);
-        int (*write_proc)(struct file *file, const char __user *buffer,
-                          unsigned long count, void *data);
         int (*tiocmget)(struct tty_struct *tty, struct file *file);
         int (*tiocmset)(struct tty_struct *tty, struct file *file,
                         unsigned int set, unsigned int clear);
@@ -190,48 +231,13 @@ struct tty_driver {
         struct tty_struct **ttys;
         struct ktermios **termios;
         struct ktermios **termios_locked;
-        void *driver_state;     /* only used for the PTY driver */
-        
+        void *driver_state;
+
         /*
-         * Interface routines from the upper tty layer to the tty
-         * driver.      Will be replaced with struct tty_operations.
+         * Driver methods
          */
-        int  (*open)(struct tty_struct * tty, struct file * filp);
-        void (*close)(struct tty_struct * tty, struct file * filp);
-        int  (*write)(struct tty_struct * tty,
-                      const unsigned char *buf, int count);
-        void (*put_char)(struct tty_struct *tty, unsigned char ch);
-        void (*flush_chars)(struct tty_struct *tty);
-        int  (*write_room)(struct tty_struct *tty);
-        int  (*chars_in_buffer)(struct tty_struct *tty);
-        int  (*ioctl)(struct tty_struct *tty, struct file * file,
-                    unsigned int cmd, unsigned long arg);
-        long (*compat_ioctl)(struct tty_struct *tty, struct file * file,
-                             unsigned int cmd, unsigned long arg);
-        void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
-        void (*throttle)(struct tty_struct * tty);
-        void (*unthrottle)(struct tty_struct * tty);
-        void (*stop)(struct tty_struct *tty);
-        void (*start)(struct tty_struct *tty);
-        void (*hangup)(struct tty_struct *tty);
-        void (*break_ctl)(struct tty_struct *tty, int state);
-        void (*flush_buffer)(struct tty_struct *tty);
-        void (*set_ldisc)(struct tty_struct *tty);
-        void (*wait_until_sent)(struct tty_struct *tty, int timeout);
-        void (*send_xchar)(struct tty_struct *tty, char ch);
-        int (*read_proc)(char *page, char **start, off_t off,
-                          int count, int *eof, void *data);
-        int (*write_proc)(struct file *file, const char __user *buffer,
-                          unsigned long count, void *data);
-        int (*tiocmget)(struct tty_struct *tty, struct file *file);
-        int (*tiocmset)(struct tty_struct *tty, struct file *file,
-                        unsigned int set, unsigned int clear);
-#ifdef CONFIG_CONSOLE_POLL
-        int (*poll_init)(struct tty_driver *driver, int line, char *options);
-        int (*poll_get_char)(struct tty_driver *driver, int line);
-        void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
-#endif
 
+        const struct tty_operations *ops;
         struct list_head tty_drivers;
 };
 
diff --git a/kernel/printk.c b/kernel/printk.c
index d3f9c0f788bf..0d232589a923 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1272,8 +1272,8 @@ late_initcall(disable_boot_consoles);
  */
 void tty_write_message(struct tty_struct *tty, char *msg)
 {
-        if (tty && tty->driver->write)
-                tty->driver->write(tty, msg, strlen(msg));
+        if (tty && tty->ops->write)
+                tty->ops->write(tty, msg, strlen(msg));
         return;
 }
 
diff --git a/net/irda/ircomm/ircomm_tty.c b/net/irda/ircomm/ircomm_tty.c
index d2620410cb0a..76c3057d0179 100644
--- a/net/irda/ircomm/ircomm_tty.c
+++ b/net/irda/ircomm/ircomm_tty.c
@@ -555,10 +555,8 @@ static void ircomm_tty_close(struct tty_struct *tty, struct file *filp)
 
         ircomm_tty_shutdown(self);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
-        if (tty->ldisc.flush_buffer)
-                tty->ldisc.flush_buffer(tty);
+        tty_driver_flush_buffer(tty);
+        tty_ldisc_flush(tty);
 
         tty->closing = 0;
         self->tty = NULL;