3.16.44-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Johan Hovold <[email protected]> commit a0467a967f347842b30739aae636c44980265265 upstream. The modem-status register was read as part of device configuration at port_probe and then again at open (and reset-resume). During open (and reset-resume) the MSR was read before submitting the interrupt URB, something which could lead to an MSR-change going unnoticed when it races with open (reset-resume). Fix this by dropping the redundant reconfiguration of the port at every open, and only read the MSR after the interrupt URB has been submitted. Fixes: 664d5df92e88 ("USB: usb-serial ch341: support for DTR/RTS/CTS") Signed-off-by: Johan Hovold <[email protected]> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- drivers/usb/serial/ch341.c | 27 ++++++++++++--------------- 1 file changed, 12 insertions(+), 15 deletions(-) --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -246,21 +246,11 @@ static int ch341_configure(struct usb_de if (r < 0) goto out; - /* expect 0xff 0xee */ - r = ch341_get_status(dev, priv); - if (r < 0) - goto out; - r = ch341_set_baudrate_lcr(dev, priv, 0); if (r < 0) goto out; r = ch341_set_handshake(dev, priv->line_control); - if (r < 0) - goto out; - - /* expect 0x9f 0xee */ - r = ch341_get_status(dev, priv); out: kfree(buffer); return r; @@ -332,14 +322,9 @@ static void ch341_close(struct usb_seria /* open this device, set default parameters */ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port) { - struct usb_serial *serial = port->serial; struct ch341_private *priv = usb_get_serial_port_data(port); int r; - r = ch341_configure(serial->dev, priv); - if (r) - return r; - if (tty) ch341_set_termios(tty, port, NULL); @@ -351,6 +336,12 @@ static int ch341_open(struct tty_struct return r; } + r = ch341_get_status(port->serial->dev, priv); + if (r < 0) { + dev_err(&port->dev, "failed to read modem status: %d\n", r); + goto err_kill_interrupt_urb; + } + r = usb_serial_generic_open(tty, port); if (r) goto err_kill_interrupt_urb; @@ -593,6 +584,12 @@ static int ch341_reset_resume(struct usb ret); return ret; } + + ret = ch341_get_status(port->serial->dev, priv); + if (ret < 0) { + dev_err(&port->dev, "failed to read modem status: %d\n", + ret); + } } return usb_serial_generic_resume(serial);
