From 63d8cb3f19dabb409a09b4f2b8827934ab9365a3 Mon Sep 17 00:00:00 2001
From: Peter Hurley <peter@hurleysoftware.com>
Date: Sun, 8 Nov 2015 09:29:38 -0500
Subject: tty: Simplify tty_set_ldisc() exit handling
Perform common exit for both successful and error exit handling
in tty_set_ldisc(). Fixes unlikely possibility of failing to restart
input kworker when switching to the same line discipline (noop case).
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/tty_ldisc.c | 42 +++++++++++++-----------------------------
1 file changed, 13 insertions(+), 29 deletions(-)
(limited to 'drivers')
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 7d43ff12f6e2..9ec125046343 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -529,34 +529,21 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty_lock(tty);
retval = tty_ldisc_lock(tty, 5 * HZ);
- if (retval) {
- tty_ldisc_put(new_ldisc);
- tty_unlock(tty);
- return retval;
- }
+ if (retval)
+ goto err;
- /*
- * Check the no-op case
- */
+ /* Check the no-op case */
+ if (tty->ldisc->ops->num == ldisc)
+ goto out;
- if (tty->ldisc->ops->num == ldisc) {
- tty_ldisc_unlock(tty);
- tty_ldisc_put(new_ldisc);
- tty_unlock(tty);
- return 0;
+ if (test_bit(TTY_HUPPED, &tty->flags)) {
+ /* We were raced by hangup */
+ retval = -EIO;
+ goto out;
}
old_ldisc = tty->ldisc;
- 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_unlock(tty);
- tty_ldisc_put(new_ldisc);
- tty_unlock(tty);
- return -EIO;
- }
-
/* Shutdown the old discipline. */
tty_ldisc_close(tty, old_ldisc);
@@ -582,18 +569,15 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
the old ldisc (if it was restored as part of error cleanup
above). In either case, releasing a single reference from
the old ldisc is correct. */
-
- tty_ldisc_put(old_ldisc);
-
- /*
- * Allow ldisc referencing to occur again
- */
+ new_ldisc = old_ldisc;
+out:
tty_ldisc_unlock(tty);
/* Restart the work queue in case no characters kick it off. Safe if
already running */
tty_buffer_restart_work(tty->port);
-
+err:
+ tty_ldisc_put(new_ldisc); /* drop the extra reference */
tty_unlock(tty);
return retval;
}
--
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