tty: Remove TTY_HUPPING

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.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 2 insertions, 14 deletions

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 9d1e247ee330..873793c426df 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 28858ebe2912..49001fa2ea2f 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 b36b0b445c1f..ff0dd7aeaf3b 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))