On Fri, Oct 01, 2021 at 08:57:19AM +0200, Himadri Pandya wrote:
> usb_control_msg_send/recv are new wrapper functions for usb_control_msg()
> that have proper error checks for short reads. These functions can also
> accept data buffer on stack. Hence use these functions to simplify error
> handling for short reads. Short reads will now get reported as
> -EREMOTEIO with no indication of how short the transfer was.
You're no longer using usb_control_msg_send() so the commit message
including Subject needs to be updated.
> Signed-off-by: Himadri Pandya <himadrispandya@xxxxxxxxx>
> ---
> Changes in v3:
> - Rephrase the commit message
> - Include a note on not reporting size of the short reads in the commit
> - Drop unnecessary changes in ch341_control_out()
> - Drop a non-relevant style change
> - Remove some more "out" labels
> - Remove unnecessary return statement from a void function
>
> Changes in v2:
> - Fix callers of ch341_control_out() and ch341_control_in()
> - Remove label "out"
> - Remove an unnecessary assignment statement
> ---
> drivers/usb/serial/ch341.c | 90 ++++++++++----------------------------
> 1 file changed, 24 insertions(+), 66 deletions(-)
>
> diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
> index 2db917eab799..8aecc1f0dee4 100644
> --- a/drivers/usb/serial/ch341.c
> +++ b/drivers/usb/serial/ch341.c
> @@ -131,23 +131,13 @@ static int ch341_control_in(struct usb_device *dev,
> dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__,
> request, value, index, bufsize);
>
> - r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
> - USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
> - value, index, buf, bufsize, DEFAULT_TIMEOUT);
> - if (r < (int)bufsize) {
> - if (r >= 0) {
> - dev_err(&dev->dev,
> - "short control message received (%d < %u)\n",
> - r, bufsize);
> - r = -EIO;
> - }
> -
> - dev_err(&dev->dev, "failed to receive control message: %d\n",
> - r);
> - return r;
> - }
> + r = usb_control_msg_recv(dev, 0, request,
> + USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
> + value, index, buf, bufsize, DEFAULT_TIMEOUT, GFP_KERNEL);
Line is now over 80 chars for no good reason.
> + if (r)
> + dev_err(&dev->dev, "failed to receive control message: %d\n", r);
Here too.
>
> - return 0;
> + return r;
I'd prefer returning the errno in the error path above and keep an
explicit zero here.
> }
>
> #define CH341_CLKRATE 48000000
> @@ -287,23 +277,18 @@ static int ch341_set_handshake(struct usb_device *dev, u8 control)
> static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
> {
> const unsigned int size = 2;
> - char *buffer;
> + u8 buffer[2];
> int r;
> unsigned long flags;
>
> - buffer = kmalloc(size, GFP_KERNEL);
> - if (!buffer)
> - return -ENOMEM;
> -
> r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
> - if (r < 0)
> - goto out;
> + if (r)
> + return r;
>
> spin_lock_irqsave(&priv->lock, flags);
> priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
> spin_unlock_irqrestore(&priv->lock, flags);
>
> -out: kfree(buffer);
> return r;
This should now be
return 0;
> }
>
> @@ -312,30 +297,25 @@ out: kfree(buffer);
> static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
> {
> const unsigned int size = 2;
> - char *buffer;
> + u8 buffer[2];
> int r;
>
> - buffer = kmalloc(size, GFP_KERNEL);
> - if (!buffer)
> - return -ENOMEM;
> -
> /* expect two bytes 0x27 0x00 */
> r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
> - if (r < 0)
> - goto out;
> + if (r)
> + return r;
> dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
>
> r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
> - if (r < 0)
> - goto out;
> + if (r)
> + return r;
Now an unrelated change.
>
> r = ch341_set_baudrate_lcr(dev, priv, priv->baud_rate, priv->lcr);
> if (r < 0)
> - goto out;
> + return r;
>
> r = ch341_set_handshake(dev, priv->mcr);
>
> -out: kfree(buffer);
> return r;
This looks a bit inconsistent now so I'll make this an explicit return
0 too.
> }
>
> @@ -345,39 +325,23 @@ static int ch341_detect_quirks(struct usb_serial_port *port)
> struct usb_device *udev = port->serial->dev;
> const unsigned int size = 2;
> unsigned long quirks = 0;
> - char *buffer;
> + u8 buffer[2];
> int r;
>
> - buffer = kmalloc(size, GFP_KERNEL);
> - if (!buffer)
> - return -ENOMEM;
> -
> /*
> * A subset of CH34x devices does not support all features. The
> * prescaler is limited and there is no support for sending a RS232
> * break condition. A read failure when trying to set up the latter is
> * used to detect these devices.
> */
> - r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), CH341_REQ_READ_REG,
> - USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
> - CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT);
> + r = usb_control_msg_recv(udev, 0, CH341_REQ_READ_REG,
> + USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
> + CH341_REG_BREAK, 0, &buffer, size, DEFAULT_TIMEOUT, GFP_KERNEL);
Unnecessarily long line > 80 chars.
> if (r == -EPIPE) {
> dev_info(&port->dev, "break control not supported, using simulated break\n");
> quirks = CH341_QUIRK_LIMITED_PRESCALER | CH341_QUIRK_SIMULATE_BREAK;
> - r = 0;
Oops, you just broke the driver. :(
This request is used to detect quirky devices and a return value of
-EPIPE here should not abort probe by returning an error to the caller
of this function.
> - goto out;
> - }
> -
> - if (r != size) {
> - if (r >= 0)
> - r = -EIO;
> + } else if (r)
And you still need brackets on the else branch.
> dev_err(&port->dev, "failed to read break control: %d\n", r);
> - goto out;
> - }
> -
> - r = 0;
> -out:
> - kfree(buffer);
>
> if (quirks) {
> dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks);
> @@ -647,23 +611,19 @@ static void ch341_break_ctl(struct tty_struct *tty, int break_state)
> struct ch341_private *priv = usb_get_serial_port_data(port);
> int r;
> uint16_t reg_contents;
> - uint8_t *break_reg;
> + uint8_t break_reg[2];
>
> if (priv->quirks & CH341_QUIRK_SIMULATE_BREAK) {
> ch341_simulate_break(tty, break_state);
> return;
> }
>
> - break_reg = kmalloc(2, GFP_KERNEL);
> - if (!break_reg)
> - return;
> -
> r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
> ch341_break_reg, 0, break_reg, 2);
> - if (r < 0) {
> + if (r) {
> dev_err(&port->dev, "%s - USB control read error (%d)\n",
> __func__, r);
> - goto out;
> + return;
> }
> dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
> __func__, break_reg[0], break_reg[1]);
> @@ -681,11 +641,9 @@ static void ch341_break_ctl(struct tty_struct *tty, int break_state)
> reg_contents = get_unaligned_le16(break_reg);
> r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
> ch341_break_reg, reg_contents);
> - if (r < 0)
> + if (r)
Now also an unrelated change.
> dev_err(&port->dev, "%s - USB control write error (%d)\n",
> __func__, r);
> -out:
> - kfree(break_reg);
> }
>
> static int ch341_tiocmset(struct tty_struct *tty,
I've fixed up the above so we don't have to spend any more time on this.
The result is here
https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial.git/commit/?h=usb-next&id=74f266455062c158f343bc3aa35ef84b3eb7adf1
Johan
