pf_purge_thread
tsleep(pf_purge_thread, PWAIT, "pftm", 1 * hz);
wakeup(pf_purge_thread);
if (kthread_create(PRI_NONE, 0, NULL, pf_purge_thread, NULL, NULL,
wakeup(pf_purge_thread);
if (kthread_create(pf_purge_thread, NULL, NULL, "pfpurge"))
extern void pf_purge_thread(void *);