On Sat, 9 Dec 2023, Lino Sanfilippo wrote:
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@vger.kernel.org Fixes: be2e2cb1d281 ("serial: Sanitize rs485_struct") Signed-off-by: Lino Sanfilippo l.sanfilippo@kunbus.com
drivers/tty/serial/serial_core.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index c254e88c8452..4eae1406cb6c 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1371,19 +1371,27 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4 return; }
- rs485->flags &= supported_flags;
- /* 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) ==
- if (!(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;- }
if (supported_flags & SER_RS485_RTS_ON_SEND) {rs485->flags |= SER_RS485_RTS_ON_SEND;rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
- rs485->flags &= supported_flags;
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);}- }
Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com