Re: [PATCH v3 05/12] usb: misc: ezusb: update to use usb_control_msg_send()

[Johan Hovold <johan@kernel.org>]

On Wed, Jan 27, 2021 at 12:03:56AM +0530, Anant Thazhemadam wrote:
> The newer usb_control_msg_{send|recv}() API are an improvement on the
> existing usb_control_msg() as it ensures that a short read/write is treated
> as an error, data can be used off the stack, and raw usb pipes need not be
> created in the calling functions.
> For this reason, the instance of usb_control_msg() has been replaced with
> usb_control_msg_send() appropriately.
> 
> Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
> ---
>  drivers/usb/misc/ezusb.c | 16 ++--------------
>  1 file changed, 2 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/usb/misc/ezusb.c b/drivers/usb/misc/ezusb.c
> index f058d8029761..78aaee56c2b7 100644
> --- a/drivers/usb/misc/ezusb.c
> +++ b/drivers/usb/misc/ezusb.c
> @@ -31,24 +31,12 @@ static const struct ezusb_fx_type ezusb_fx1 = {
>  static int ezusb_writememory(struct usb_device *dev, int address,
>  				unsigned char *data, int length, __u8 request)
>  {
> -	int result;
> -	unsigned char *transfer_buffer;
> -
>  	if (!dev)
>  		return -ENODEV;
>  
> -	transfer_buffer = kmemdup(data, length, GFP_KERNEL);
> -	if (!transfer_buffer) {
> -		dev_err(&dev->dev, "%s - kmalloc(%d) failed.\n",
> -							__func__, length);
> -		return -ENOMEM;
> -	}
> -	result = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
> +	return usb_control_msg_send(dev, 0, request,
>  				 USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
> -				 address, 0, transfer_buffer, length, 3000);
> -
> -	kfree(transfer_buffer);
> -	return result;
> +				 address, 0, data, length, 3000, GFP_KERNEL);
>  }
>  
>  static int ezusb_set_reset(struct usb_device *dev, unsigned short cpucs_reg,

This is a prime example of how the new helpers should be used. 

With the short-write bit dropped from the commit message:

Reviewed-by: Johan Hovold <johan@kernel.org>

Johan