This is a note to let you know that I've just added the patch titled
serial: core: fix sanitizing check for RTS settings
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-testing branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will be merged to the tty-next branch sometime soon,
after it passes testing, and the merge window is open.
If you have any questions about this process, please let me know.
>From 4afeced55baa391490b61ed9164867e2927353ed Mon Sep 17 00:00:00 2001
From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Date: Wed, 3 Jan 2024 07:18:14 +0100
Subject: serial: core: fix sanitizing check for RTS settings
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Among other things uart_sanitize_serial_rs485() tests the sanity of the RTS
settings in a RS485 configuration that has been passed by userspace.
If RTS-on-send and RTS-after-send are both set or unset the configuration
is adjusted and RTS-after-send is disabled and RTS-on-send enabled.
This however makes only sense if both RTS modes are actually supported by
the driver.
With commit be2e2cb1d281 ("serial: Sanitize rs485_struct") the code does
take the driver support into account but only checks if one of both RTS
modes are supported. This may lead to the errorneous result of RTS-on-send
being set even if only RTS-after-send is supported.
Fix this by changing the implemented logic: First clear all unsupported
flags in the RS485 configuration, then adjust an invalid RTS setting by
taking into account which RTS mode is supported.
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: be2e2cb1d281 ("serial: Sanitize rs485_struct")
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Signed-off-by: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240103061818.564-4-l.sanfilippo@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/serial_core.c | 32 ++++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 850f24cc53e5..cd8c3a70455e 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1376,20 +1376,28 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
return;
}
- /* Pick sane settings if the user hasn't */
- if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&
- !(rs485->flags & SER_RS485_RTS_ON_SEND) ==
- !(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
- dev_warn_ratelimited(port->dev,
- "%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
- port->name, port->line);
- rs485->flags |= SER_RS485_RTS_ON_SEND;
- rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
- supported_flags |= SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND;
- }
-
rs485->flags &= supported_flags;
+ /* Pick sane settings if the user hasn't */
+ if (!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
+ !(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
+ if (supported_flags & SER_RS485_RTS_ON_SEND) {
+ rs485->flags |= SER_RS485_RTS_ON_SEND;
+ rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
+
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
+ port->name, port->line);
+ } else {
+ rs485->flags |= SER_RS485_RTS_AFTER_SEND;
+ rs485->flags &= ~SER_RS485_RTS_ON_SEND;
+
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): invalid RTS setting, using RTS_AFTER_SEND instead\n",
+ port->name, port->line);
+ }
+ }
+
uart_sanitize_serial_rs485_delays(port, rs485);
/* Return clean padding area to userspace */
--
2.43.0
