diff options
author | Johan Hovold <johan@kernel.org> | 2017-01-06 19:15:17 +0100 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2017-06-05 21:13:41 +0100 |
commit | e56a51958d034d984744994f91b43eea51abe425 (patch) | |
tree | 2bc0cd0059a864c366ec210a8d1e89144230075f | |
parent | 4d1634bb65b9d5a87c01d7a9498cb8eb7bb86272 (diff) |
USB: serial: ch341: fix modem-status handling
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 <johan@kernel.org>
[bwh: Backported to 3.2:
- Adjust context
- Keep the 'serial' variable in ch341_open()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r-- | drivers/usb/serial/ch341.c | 26 |
1 files changed, 12 insertions, 14 deletions
diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c index d50a6a696a8d..57cb577e0be2 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -255,21 +255,11 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv) 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; @@ -345,10 +335,6 @@ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port) dbg("ch341_open()"); - r = ch341_configure(serial->dev, priv); - if (r) - return r; - if (tty) ch341_set_termios(tty, port, NULL); @@ -361,6 +347,12 @@ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port) 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; @@ -656,6 +648,12 @@ static int ch341_reset_resume(struct usb_interface *intf) 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); |