tty close cleanup

Hi Greg,

This series is a redux of cleanup I originally submitted back in 2014; the point is to remove the cruft which stems from dropping the tty lock while waiting for output to drain before closing the tty.

Dropping the tty lock during close was added by "TTY: define tty_wait_until_sent_from_close" to fix stalls on other parallel tty operations while a tty was draining output while closing.

Since commit 89c8d91e31f2 ("tty: localise the lock") and commit aa3cb814a8ef ("tty: Drop tty_mutex before tty reopen"), parallel tty open/close/hangup on _other_ ttys no longer stall waiting for a tty close to complete.

Continuing to hold the tty lock for the tty which is closing significantly simplifies the state handling when opening a tty, since the tty cannot have been closed concurrently. [Ideally, I would have liked to entirely remove the TTY_CLOSING state flag, but unfortunately some older bit-rotting drivers have co-opted it for dubious purposes].

In the previous series, David Laight had raised concerns about non-blocking opens on the _same_ tty which is closing. However, as I pointed out in this reply http://www.spinics.net/lists/linux-serial/msg14216.html, the outcome of a parallel open while closing the same tty has not changed with this series, since the existing code has blocked while ASYNC_CLOSING (and has done since at least before 2.6.29).

I cc'd the commenters from the original series, Felipe Balbi for the gserial usb gadget changes, and David Miller for the ISDN/IRDA changes.

Regards,

Peter Hurley (7):
tty: Remove tty_wait_until_sent_from_close()
tty: Remove ASYNC_CLOSING checks in open()/hangup() methods
usb: gadget: gserial: Privatize close_wait
tty: Remove tty_port::close_wait
tty: r3964: Use tty->read_wait waitqueue
tty: r3964: Replace/remove bogus tty lock use
tty: Remove wait_event_interruptible_tty()

 drivers/char/pcmcia/synclink_cs.c      |  9 -------
 drivers/isdn/i4l/isdn_tty.c            |  2 +-
 drivers/tty/cyclades.c                 |  9 -------
 drivers/tty/hvc/hvc_console.c          |  2 +-
 drivers/tty/hvc/hvcs.c                 |  2 +-
 drivers/tty/n_r3964.c                  | 28 ++++++++++++---------
 drivers/tty/rocket.c                   | 13 ----------
 drivers/tty/serial/68328serial.c       |  1 -
 drivers/tty/serial/crisv10.c           | 34 +------------------------
 drivers/tty/serial/serial_core.c       |  1 -
 drivers/tty/synclink.c                 | 18 +++-----------
 drivers/tty/synclink_gt.c              | 14 ++---------
 drivers/tty/synclinkmp.c               | 14 ++---------
 drivers/tty/tty_port.c                 | 26 +++-----------------
 drivers/usb/gadget/function/u_serial.c |  6 +++--
 include/linux/n_r3964.h                |  8 +++---
 include/linux/tty.h                    | 45 ----------------------------------
 net/irda/ircomm/ircomm_tty.c           | 31 +----------------------
 18 files changed, 39 insertions(+), 224 deletions(-)

2.6.1