From ba4bbdabecd11530dca78dbae3ee7e51ffdc0a06 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 5 Jul 2021 10:20:11 +0200 Subject: [PATCH] USB: serial: cp210x: fix flow-control error handling 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 Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold --- 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 ad6aeb44f3e6..d48bed5782a5 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -1190,6 +1190,7 @@ 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; /* @@ -1249,14 +1250,14 @@ 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)) { @@ -1279,8 +1280,12 @@ 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); }