NULLACTIVITY
activity_data_t *node = NULLACTIVITY;
if (*act_start == NULLACTIVITY) {
node->prev != NULLACTIVITY) {
(*act_end)->next = NULLACTIVITY;
static activity_data_t *disk_act_start = NULLACTIVITY;
static activity_data_t *disk_act_end = NULLACTIVITY;
while (node->next != NULLACTIVITY) {
static activity_data_t *tty_act_start = NULLACTIVITY;
static activity_data_t *tty_act_end = NULLACTIVITY;
static activity_data_t *nfs_act_start = NULLACTIVITY;
static activity_data_t *nfs_act_end = NULLACTIVITY;