| From | Peter Hurley <> | Subject | [PATCH v3 21/23] tty: Re-parent orphaned tty_set_ldisc() comments | Date | Tue, 5 Feb 2013 15:20:36 -0500 |
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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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