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, 4 insertions, 2 deletions

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)