Re: [PATCH 8/8] Input: usbtouchscreen - switch to using __free() cleanup facility

[Greg KH]

On Thu, Jul 11, 2024 at 10:18:50PM -0700, Dmitry Torokhov wrote:
> Use __free(kfree) cleanup facility when allocating temporary buffers
> for USB transfers.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> ---
>  drivers/input/touchscreen/usbtouchscreen.c | 90 ++++++++--------------
>  1 file changed, 33 insertions(+), 57 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
> index 0015f0a6de01..7567efabe014 100644
> --- a/drivers/input/touchscreen/usbtouchscreen.c
> +++ b/drivers/input/touchscreen/usbtouchscreen.c
> @@ -167,9 +167,8 @@ static const struct usbtouch_device_info e2i_dev_info = {
>  
>  static int egalax_init(struct usbtouch_usb *usbtouch)
>  {
> -	int ret, i;
> -	unsigned char *buf;
>  	struct usb_device *udev = interface_to_usbdev(usbtouch->interface);
> +	int ret, i;
>  
>  	/*
>  	 * An eGalax diagnostic packet kicks the device into using the right
> @@ -177,7 +176,7 @@ static int egalax_init(struct usbtouch_usb *usbtouch)
>  	 * read later and ignored.
>  	 */
>  
> -	buf = kmalloc(3, GFP_KERNEL);
> +	u8 *buf __free(kfree) = kmalloc(3, GFP_KERNEL);
>  	if (!buf)
>  		return -ENOMEM;
>  
> @@ -191,17 +190,11 @@ static int egalax_init(struct usbtouch_usb *usbtouch)
>  				      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
>  				      0, 0, buf, 3,
>  				      USB_CTRL_SET_TIMEOUT);
> -		if (ret >= 0) {
> -			ret = 0;
> -			break;
> -		}
>  		if (ret != -EPIPE)
>  			break;
>  	}
>  
> -	kfree(buf);
> -
> -	return ret;
> +	return ret < 0 ? ret : 0;

Personally I hate ? : usage, but it's your subsystem and it's used
elsewhere in this file, so you have to live with it :)

>  }
>  
>  static int egalax_read_data(struct usbtouch_usb *dev, unsigned char *pkt)
> @@ -358,10 +351,9 @@ static int mtouch_get_fw_revision(struct usbtouch_usb *usbtouch)
>  {
>  	struct usb_device *udev = interface_to_usbdev(usbtouch->interface);
>  	struct mtouch_priv *priv = usbtouch->priv;
> -	u8 *buf;
>  	int ret;
>  
> -	buf = kzalloc(MTOUCHUSB_REQ_CTRLLR_ID_LEN, GFP_NOIO);
> +	u8 *buf __free(kfree) = kzalloc(MTOUCHUSB_REQ_CTRLLR_ID_LEN, GFP_NOIO);
>  	if (!buf)
>  		return -ENOMEM;
>  
> @@ -373,18 +365,13 @@ static int mtouch_get_fw_revision(struct usbtouch_usb *usbtouch)
>  	if (ret != MTOUCHUSB_REQ_CTRLLR_ID_LEN) {
>  		dev_warn(&usbtouch->interface->dev,
>  			 "Failed to read FW rev: %d\n", ret);
> -		ret = ret < 0 ? ret : -EIO;
> -		goto free;
> +		return ret < 0 ? ret : -EIO;
>  	}
>  
>  	priv->fw_rev_major = buf[3];
>  	priv->fw_rev_minor = buf[4];
>  
> -	ret = 0;
> -
> -free:
> -	kfree(buf);
> -	return ret;
> +	return 0;
>  }
>  
>  static int mtouch_alloc(struct usbtouch_usb *usbtouch)
> @@ -636,24 +623,23 @@ static const struct usbtouch_device_info gunze_dev_info = {
>  static int dmc_tsc10_init(struct usbtouch_usb *usbtouch)
>  {
>  	struct usb_device *dev = interface_to_usbdev(usbtouch->interface);
> -	int ret = -ENOMEM;
> -	unsigned char *buf;
> +	int ret;
>  
> -	buf = kmalloc(2, GFP_NOIO);
> +	u8 *buf __free(kfree) = kmalloc(2, GFP_NOIO);
>  	if (!buf)
> -		goto err_nobuf;
> +		return -ENOMEM;
> +
>  	/* reset */
>  	buf[0] = buf[1] = 0xFF;
>  	ret = usb_control_msg(dev, usb_rcvctrlpipe (dev, 0),
> -	                      TSC10_CMD_RESET,
> -	                      USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
> -	                      0, 0, buf, 2, USB_CTRL_SET_TIMEOUT);
> +			      TSC10_CMD_RESET,
> +			      USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
> +			      0, 0, buf, 2, USB_CTRL_SET_TIMEOUT);

Unintentional whitespace change?

Anyway, not a big deal, cleanup looks good:

Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>