usbtmc_message
struct usbtmc_message msg;
if (copy_from_user(&msg, arg, sizeof(struct usbtmc_message)))
&((struct usbtmc_message __user *)arg)->transferred))
struct usbtmc_message msg;
if (copy_from_user(&msg, arg, sizeof(struct usbtmc_message)))
&((struct usbtmc_message __user *)arg)->transferred))
#define USBTMC_IOCTL_WRITE _IOWR(USBTMC_IOC_NR, 13, struct usbtmc_message)
#define USBTMC_IOCTL_READ _IOWR(USBTMC_IOC_NR, 14, struct usbtmc_message)