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>

1 files changed, 5 insertions, 8 deletions

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 7e31d5f1bc8..a6c2619ec78 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)