Re: [PATCH] usb: renesas_usbhs: Use struct assignment instead of memcpy()

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jun 13, 2019 at 08:18:48PM +0900, Yoshihiro Shimoda wrote:
> To avoid the error-proneness of calls to sizeof() in the memcpy,
> this patch uses struct assignment instead of memcpy.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> ---
>  This patch is based on Greg's linux-usb.git / usb-next branch.
>  Note that mod_host.c also has memcpy but we cannot use struct assignment
>  for it because the type of urb->setup_patcket is just "unsigned char *".
> 
>  drivers/usb/renesas_usbhs/common.c | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/usb/renesas_usbhs/common.c b/drivers/usb/renesas_usbhs/common.c
> index a501ea6..ebbe322 100644
> --- a/drivers/usb/renesas_usbhs/common.c
> +++ b/drivers/usb/renesas_usbhs/common.c
> @@ -651,9 +651,8 @@ static struct renesas_usbhs_platform_info *usbhs_parse_dt(struct device *dev)
>  		return NULL;
>  
>  	dparam = &info->driver_param;
> -	memcpy(dparam, &data->param, sizeof(data->param));
> -	memcpy(&info->platform_callback, data->platform_callback,
> -	       sizeof(*data->platform_callback));
> +	*dparam = data->param;
> +	info->platform_callback = *data->platform_callback;

How are the original calls here "error-prone"?  Yes, the compiler will
end up calling memcpy somehow with this change, but it feels "wrong" to
hide a memory copy like this.

So are you _sure_ you want this change?

thanks,

greg k-h