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>

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;

drivers/bluetooth/hci_ldisc.c

@@ -143,7 +143,7 @@ int hci_uart_tx_wakeup(struct hci_uart *hu)
 		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)

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 );
 }

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 */

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

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)

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);