From: Peter Hurley Subject: [PATCH -next 1/5] tty: Allow safe access to termios for set_ldisc() handlers Date: Wed, 5 Nov 2014 13:11:41 -0500 Message-ID: <1415211105-16668-2-git-send-email-peter@hurleysoftware.com> References: <1415211105-16668-1-git-send-email-peter@hurleysoftware.com> Return-path: In-Reply-To: <1415211105-16668-1-git-send-email-peter@hurleysoftware.com> Sender: linux-kernel-owner@vger.kernel.org To: Greg Kroah-Hartman Cc: Jiri Slaby , One Thousand Gnomes , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Nicolas Ferre , Peter Hurley List-Id: linux-serial@vger.kernel.org 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 --- 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