Function arptimer

freebsd/netinet/if_ether.c:205–321

* Timeout routine. Age arp_tab entries periodically. */

 * Timeout routine.  Age arp_tab entries periodically.
 */
static void
arptimer(void *arg)
{
	struct llentry *lle = (struct llentry *)arg;
	struct ifnet *ifp;
	int r_skip_req;

	if (lle->la_flags & LLE_STATIC) {
		return;
	}
	LLE_WLOCK(lle);
	if (callout_pending(&lle->lle_timer)) {
		/*
		 * Here we are a bit odd here in the treatment of
		 * active/pending. If the pending bit is set, it got
		 * rescheduled before I ran. The active
		 * bit we ignore, since if it was stopped
		 * in ll_tablefree() and was currently running
		 * it would have return 0 so the code would
		 * not have deleted it since the callout could
		 * not be stopped so we want to go through
		 * with the delete here now. If the callout
		 * was restarted, the pending bit will be back on and
		 * we just want to bail since the callout_reset would
		 * return 1 and our reference would have been removed
		 * by arpresolve() below.
		 */
		LLE_WUNLOCK(lle);
 		return;
 	}
	ifp = lle->lle_tbl->llt_ifp;
	CURVNET_SET(ifp->if_vnet);

	switch (lle->ln_state) {
	case ARP_LLINFO_REACHABLE:

		/*
		 * Expiration time is approaching.
		 * Let's try to refresh entry if it is still
		 * in use.
		 *
		 * Set r_skip_req to get feedback from
		 * fast path. Change state and re-schedule
		 * ourselves.
		 */
		LLE_REQ_LOCK(lle);
		lle->r_skip_req = 1;
		LLE_REQ_UNLOCK(lle);
		lle->ln_state = ARP_LLINFO_VERIFY;
		callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
		LLE_WUNLOCK(lle);
		CURVNET_RESTORE();
		return;
	case ARP_LLINFO_VERIFY:
		LLE_REQ_LOCK(lle);
		r_skip_req = lle->r_skip_req;
		LLE_REQ_UNLOCK(lle);