diff mbox series

[SRU,jammy:linux-xilinx-zynqmp,14/14] serial: fix TIOCSRS485 locking

Message ID 20240822091117.1760423-15-portia.stephens@canonical.com
State New
Headers show
Series Backport ps uart RS485 driver | expand

Commit Message

Portia Stephens Aug. 22, 2024, 9:11 a.m. UTC 
From: Johan Hovold <johan@kernel.org>

BugLink: https://bugs.launchpad.net/bugs/2055237

The RS485 multipoint addressing support for some reason added a new
ADDRB termios cflag which is (only!) updated from one of the RS485
ioctls.

Make sure to take the termios rw semaphore for the right ioctl (i.e.
set, not get).

Fixes: ae50bb275283 ("serial: take termios_rwsem for ->rs485_config() & pass termios as param")
Cc: stable@vger.kernel.org	# 6.0
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20230412124811.11217-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from 9e4f2a8004213339e9d837d891a59cc80e082966)
Signed-off-by: Portia Stephens <portia.stephens@canonical.com>
---
 drivers/tty/serial/serial_core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 2170721186f6b..d90184953977c 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1445,7 +1445,7 @@  uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 		goto out;
 
 	/* rs485_config requires more locking than others */
-	if (cmd == TIOCGRS485)
+	if (cmd == TIOCSRS485)
 		down_write(&tty->termios_rwsem);
 
 	mutex_lock(&port->mutex);
@@ -1488,7 +1488,7 @@  uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 	}
 out_up:
 	mutex_unlock(&port->mutex);
-	if (cmd == TIOCGRS485)
+	if (cmd == TIOCSRS485)
 		up_write(&tty->termios_rwsem);
 out:
 	return ret;