Function ithread_loop

freebsd/kern/kern_intr.c:1218–1305

* This is the main code for interrupt threads. */

 * This is the main code for interrupt threads.
 */
static void
ithread_loop(void *arg)
{
	struct epoch_tracker et;
	struct intr_thread *ithd;
	struct intr_event *ie;
	struct thread *td;
	struct proc *p;
	int wake, epoch_count;
	bool needs_epoch;

	td = curthread;
	p = td->td_proc;
	ithd = (struct intr_thread *)arg;
	KASSERT(ithd->it_thread == td,
	    ("%s: ithread and proc linkage out of sync", __func__));
	ie = ithd->it_event;
	ie->ie_count = 0;
	wake = 0;

	/*
	 * As long as we have interrupts outstanding, go through the
	 * list of handlers, giving each one a go at it.
	 */
	for (;;) {
		/*
		 * If we are an orphaned thread, then just die.
		 */
		if (ithd->it_flags & IT_DEAD) {
			CTR3(KTR_INTR, "%s: pid %d (%s) exiting", __func__,
			    p->p_pid, td->td_name);
			free(ithd, M_ITHREAD);
			kthread_exit();
		}

		/*
		 * Service interrupts.  If another interrupt arrives while
		 * we are running, it will set it_need to note that we
		 * should make another pass.
		 *
		 * The load_acq part of the following cmpset ensures
		 * that the load of ih_need in ithread_execute_handlers()
		 * is ordered after the load of it_need here.
		 */
		needs_epoch =
		    (atomic_load_int(&ie->ie_hflags) & IH_NET) != 0;
		if (needs_epoch) {
			epoch_count = 0;
			NET_EPOCH_ENTER(et);
		}
		while (atomic_cmpset_acq_int(&ithd->it_need, 1, 0) != 0) {
			ithread_execute_handlers(p, ie);
			if (needs_epoch &&
			    ++epoch_count >= intr_epoch_batch) {
				NET_EPOCH_EXIT(et);
				epoch_count = 0;
				NET_EPOCH_ENTER(et);
			}