Make sure that the driver crtscts state is not updated in the unlikely event that the flow-control request fails. Not doing so could break RTS control.

Fixes: 5951b8508855 ("USB: serial: cp210x: suppress modem-control errors") Cc: stable@vger.kernel.org # 5.11 Signed-off-by: Johan Hovold johan@kernel.org --- drivers/usb/serial/cp210x.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index b41e2c7649fb..eb3be4f65603 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -1191,6 +1191,7 @@ static void cp210x_set_flow_control(struct tty_struct *tty, struct cp210x_flow_ctl flow_ctl; u32 flow_repl; u32 ctl_hs; + bool crtscts; int ret;

/* @@ -1246,14 +1247,14 @@ static void cp210x_set_flow_control(struct tty_struct *tty, flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL; else flow_repl |= CP210X_SERIAL_RTS_INACTIVE; - port_priv->crtscts = true; + crtscts = true; } else { ctl_hs &= ~CP210X_SERIAL_CTS_HANDSHAKE; if (port_priv->rts) flow_repl |= CP210X_SERIAL_RTS_ACTIVE; else flow_repl |= CP210X_SERIAL_RTS_INACTIVE; - port_priv->crtscts = false; + crtscts = false; }

if (I_IXOFF(tty)) { @@ -1276,8 +1277,12 @@ static void cp210x_set_flow_control(struct tty_struct *tty, flow_ctl.ulControlHandshake = cpu_to_le32(ctl_hs); flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl);

- cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl, + ret = cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl, sizeof(flow_ctl)); + if (ret) + goto out_unlock; + + port_priv->crtscts = crtscts; out_unlock: mutex_unlock(&port_priv->mutex); }