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Subject[PATCH v3 21/23] tty: Re-parent orphaned tty_set_ldisc() comments
Date

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
drivers/tty/tty_ldisc.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 92629c1..49e4825 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -545,10 +545,18 @@ static int tty_ldisc_halt(struct tty_struct *tty, struct tty_struct *o_tty,
{
int scheduled, o_scheduled, retval;

+ /*
+ * The TTY_LDISC bit prevents anyone taking an ldisc
+ * reference once it is clear.
+ */
clear_bit(TTY_LDISC, &tty->flags);
if (o_tty)
clear_bit(TTY_LDISC, &o_tty->flags);

+ /*
+ * Make sure we don't change while someone holds a
+ * reference to the line discipline.
+ */
retval = tty_ldisc_wait_idle(tty, timeout);
if (!retval && o_tty)
retval = tty_ldisc_wait_idle(o_tty, timeout);
@@ -702,13 +710,9 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
o_ldisc = tty->ldisc;

tty_unlock(tty);
+
/*
- * Make sure we don't change while someone holds a
- * reference to the line discipline. The TTY_LDISC bit
- * prevents anyone taking a reference once it is clear.
- * We need the lock to avoid racing reference takers.
- *
- * We must clear the TTY_LDISC bit here to avoid a livelock
+ * We must halt the line discipline here to avoid a livelock
* with a userspace app continually trying to use the tty in
* parallel to the change and re-referencing the tty.
*/
--
1.8.1.2


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