[PATCH -next 03/27] tty: Remove TTY_HUPPING

Peter Hurley
2014-10-16T20:28:40Z

Now that tty_ldisc_hangup() does not drop the tty lock, it is no
longer possible to observe TTY_HUPPING while holding the tty lock
on another cpu.

Remove TTY_HUPPING bit definition.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
drivers/tty/tty_io.c | 12 +-----------
drivers/tty/tty_ldisc.c | 3 +--
include/linux/tty.h | 1 -
3 files changed, 2 insertions(+), 14 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index e18491a..fd06512 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -690,9 +690,6 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session)
return;
}

- /* some functions below drop BTM, so we need this bit */
- set_bit(TTY_HUPPING, &tty->flags);
-
/* inuse_filps is protected by the single tty lock,
this really needs to change if we want to flush the
workqueue with the lock held */
@@ -717,10 +714,6 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session)
while (refs--)
tty_kref_put(tty);

- /*
- * it drops BTM and thus races with reopen
- * we protect the race by TTY_HUPPING
- */
tty_ldisc_hangup(tty);

spin_lock_irq(&tty->ctrl_lock);
@@ -752,8 +745,6 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session)
* can't yet guarantee all that.
*/
set_bit(TTY_HUPPED, &tty->flags);
- clear_bit(TTY_HUPPING, &tty->flags);
-
tty_unlock(tty);

if (f)
@@ -1461,8 +1452,7 @@ static int tty_reopen(struct tty_struct *tty)
{
struct tty_driver *driver = tty->driver;

- if (test_bit(TTY_CLOSING, &tty->flags) ||
- test_bit(TTY_HUPPING, &tty->flags))
+ if (test_bit(TTY_CLOSING, &tty->flags))
return -EIO;

if (driver->type == TTY_DRIVER_TYPE_PTY &&
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 28858eb..49001fa 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -544,8 +544,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)

old_ldisc = tty->ldisc;

- if (test_bit(TTY_HUPPING, &tty->flags) ||
- test_bit(TTY_HUPPED, &tty->flags)) {
+ if (test_bit(TTY_HUPPED, &tty->flags)) {
/* We were raced by the hangup method. It will have stomped
the ldisc data and closed the ldisc down */
tty_ldisc_enable_pair(tty, o_tty);
diff --git a/include/linux/tty.h b/include/linux/tty.h
index b36b0b4..ff0dd7a 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -321,7 +321,6 @@ struct tty_file_private {
#define TTY_PTY_LOCK 16 /* pty private */
#define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */
#define TTY_HUPPED 18 /* Post driver->hangup() */
-#define TTY_HUPPING 21 /* ->hangup() in progress */
#define TTY_LDISC_HALTED 22 /* Line discipline is halted */

#define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
--
2.1.1