Allow a tty driver to safely access termios settings while handling
the set_ldisc() notification. UART drivers use the set_ldisc()
notification to check if the N_PPS line discipline is being enabled;
if so, modem status interrupts may also need to be enabled. Conversely,
modem status interrupts may need to be disabled if switching away
from the N_PPS line discipline.
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/tty_ldisc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index b66a81d..3737f55 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -572,8 +572,11 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty_ldisc_restore(tty, old_ldisc);
}
- if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc)
+ if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) {
+ down_read(&tty->termios_rwsem);
tty->ops->set_ldisc(tty);
+ up_read(&tty->termios_rwsem);
+ }
/* At this point we hold a reference to the new ldisc and a
reference to the old ldisc, or we hold two references to
--
2.1.3
--
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