IOC_IN
if (cmd & (IOC_IN | IOC_OUT)) {
if (cmd & IOC_IN) {
if ((cmd & ioctl->cmd & IOC_IN) == 0)
if (com&IOC_IN) {
#define IOC_INOUT (IOC_IN|IOC_OUT)
#define _IOW(g,n,t) _IOC(IOC_IN, (g), (n), sizeof(t))
if (cmd & IOC_IN)