C++ cv_broadcast函数代码示例

/*
 * ehci_intr:
 *
 * EHCI (EHCI) interrupt handling routine.
 */
uint_t
ehci_intr(caddr_t arg1, caddr_t arg2)
{
	uint_t			intr;
	ehci_state_t		*ehcip = (ehci_state_t *)arg1;

	USB_DPRINTF_L3(PRINT_MASK_INTR, ehcip->ehci_log_hdl,
	    "ehci_intr: Interrupt occurred, arg1 0x%p arg2 0x%p", arg1, arg2);

	/* Get the ehci global mutex */
	mutex_enter(&ehcip->ehci_int_mutex);

	/*
	 * Now process the actual ehci interrupt events  that caused
	 * invocation of this ehci interrupt handler.
	 */
	intr = (Get_OpReg(ehci_status) & Get_OpReg(ehci_interrupt));

	/* Update kstat values */
	ehci_do_intrs_stats(ehcip, intr);

	/*
	 * We could have gotten a spurious interrupts. If so, do not
	 * claim it.  This is quite  possible on some  architectures
	 * where more than one PCI slots share the IRQs.  If so, the
	 * associated driver's interrupt routine may get called even
	 * if the interrupt is not meant for them.
	 *
	 * By unclaiming the interrupt, the other driver gets chance
	 * to service its interrupt.
	 */
	if (!intr) {
		mutex_exit(&ehcip->ehci_int_mutex);

		return (DDI_INTR_UNCLAIMED);
	}

	/* Acknowledge the interrupt */
	Set_OpReg(ehci_status, intr);

	if (ehcip->ehci_hc_soft_state == EHCI_CTLR_ERROR_STATE) {
		mutex_exit(&ehcip->ehci_int_mutex);

		return (DDI_INTR_CLAIMED);
	}

	USB_DPRINTF_L3(PRINT_MASK_INTR, ehcip->ehci_log_hdl,
	    "Interrupt status 0x%x", intr);

	/*
	 * If necessary broadcast that an interrupt has occured.  This
	 * is only necessary during controller init.
	 */
	if (ehcip->ehci_flags & EHCI_CV_INTR) {
		ehcip->ehci_flags &= ~EHCI_CV_INTR;
		cv_broadcast(&ehcip->ehci_async_schedule_advance_cv);
	}

	/* Check for Frame List Rollover */
	if (intr & EHCI_INTR_FRAME_LIST_ROLLOVER) {
		USB_DPRINTF_L3(PRINT_MASK_INTR, ehcip->ehci_log_hdl,
		    "ehci_intr: Frame List Rollover");

		ehci_handle_frame_list_rollover(ehcip);

		/* VIA VT6202 looses EHCI_INTR_USB interrupts, workaround. */
		if ((ehcip->ehci_vendor_id == PCI_VENDOR_VIA) &&
		    (ehci_vt62x2_workaround & EHCI_VIA_LOST_INTERRUPTS)) {
			ehcip->ehci_missed_intr_sts |= EHCI_INTR_USB;
		}
	}

	/* Check for Advance on Asynchronous Schedule */
	if (intr & EHCI_INTR_ASYNC_ADVANCE) {
		USB_DPRINTF_L3(PRINT_MASK_INTR, ehcip->ehci_log_hdl,
		    "ehci_intr: Asynchronous Schedule Advance Notification");

		/* Disable async list advance interrupt */
		Set_OpReg(ehci_interrupt,
		    (Get_OpReg(ehci_interrupt) & ~EHCI_INTR_ASYNC_ADVANCE));

		/*
		 * Call cv_broadcast on every this interrupt to wakeup
		 * all the threads that are waiting the async list advance
		 * event.
		 */
		cv_broadcast(&ehcip->ehci_async_schedule_advance_cv);
	}

	/* Always process completed itds */
	ehci_traverse_active_isoc_list(ehcip);

	/*
	 * Check for any USB transaction completion notification. Also
	 * process any missed USB transaction completion interrupts.
//.........这里部分代码省略.........

int
drm_queue_vblank_event(struct drm_device *dev, int crtc,
    union drm_wait_vblank *vblwait, struct drm_file *file_priv)
{
	struct drm_pending_vblank_event	*vev;
	struct timeval			 now;
	u_int				 seq;


	vev = drm_calloc(1, sizeof(*vev));
	if (vev == NULL)
		return (ENOMEM);

	vev->event.base.type = DRM_EVENT_VBLANK;
	vev->event.base.length = sizeof(vev->event);
	vev->event.user_data = vblwait->request.signal;
	vev->base.event = &vev->event.base;
	vev->base.file_priv = file_priv;
	vev->base.destroy = (void (*) (struct drm_pending_event *))drm_free;

	microtime(&now);

	mtx_enter(&dev->event_lock);
	if (file_priv->event_space < sizeof(vev->event)) {
		mtx_leave(&dev->event_lock);
		drm_free(vev);
		return (ENOMEM);
	}


	seq = drm_vblank_count(dev, crtc);
	file_priv->event_space -= sizeof(vev->event);

	DPRINTF("%s: queueing event %d on crtc %d\n", __func__, seq, crtc);

	if ((vblwait->request.type & _DRM_VBLANK_NEXTONMISS) &&
	    (seq - vblwait->request.sequence) <= (1 << 23)) {
		vblwait->request.sequence = seq + 1;
		vblwait->reply.sequence = vblwait->request.sequence;
	}

	vev->event.sequence = vblwait->request.sequence;
	if ((seq - vblwait->request.sequence) <= (1 << 23)) {
		vev->event.tv_sec = now.tv_sec;
		vev->event.tv_usec = now.tv_usec;
		DPRINTF("%s: already passed, dequeuing: crtc %d, value %d\n",
		    __func__, crtc, seq);
		drm_vblank_put(dev, crtc);
		TAILQ_INSERT_TAIL(&file_priv->evlist, &vev->base, link);
#if !defined(__NetBSD__)
		wakeup(&file_priv->evlist);
#else /* !defined(__NetBSD__) */
		cv_broadcast(&file_priv->evlist_condvar);
#endif /* !defined(__NetBSD__) */
		selwakeup(&file_priv->rsel);
	} else {
		TAILQ_INSERT_TAIL(&dev->vblank->vb_crtcs[crtc].vbl_events,
		    &vev->base, link);
	}
	mtx_leave(&dev->event_lock);

	return (0);
}

static int
traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
    const blkptr_t *bp, const zbookmark_phys_t *zb)
{
	zbookmark_phys_t czb;
	int err = 0;
	arc_buf_t *buf = NULL;
	prefetch_data_t *pd = td->td_pfd;
	boolean_t hard = td->td_flags & TRAVERSE_HARD;

	switch (resume_skip_check(td, dnp, zb)) {
	case RESUME_SKIP_ALL:
		return (0);
	case RESUME_SKIP_CHILDREN:
		goto post;
	case RESUME_SKIP_NONE:
		break;
	default:
		ASSERT(0);
	}

	if (bp->blk_birth == 0) {
		/*
		 * Since this block has a birth time of 0 it must be one of
		 * two things: a hole created before the
		 * SPA_FEATURE_HOLE_BIRTH feature was enabled, or a hole
		 * which has always been a hole in an object.
		 *
		 * If a file is written sparsely, then the unwritten parts of
		 * the file were "always holes" -- that is, they have been
		 * holes since this object was allocated.  However, we (and
		 * our callers) can not necessarily tell when an object was
		 * allocated.  Therefore, if it's possible that this object
		 * was freed and then its object number reused, we need to
		 * visit all the holes with birth==0.
		 *
		 * If it isn't possible that the object number was reused,
		 * then if SPA_FEATURE_HOLE_BIRTH was enabled before we wrote
		 * all the blocks we will visit as part of this traversal,
		 * then this hole must have always existed, so we can skip
		 * it.  We visit blocks born after (exclusive) td_min_txg.
		 *
		 * Note that the meta-dnode cannot be reallocated.
		 */
		if (!send_holes_without_birth_time &&
		    (!td->td_realloc_possible ||
		    zb->zb_object == DMU_META_DNODE_OBJECT) &&
		    td->td_hole_birth_enabled_txg <= td->td_min_txg)
			return (0);
	} else if (bp->blk_birth <= td->td_min_txg) {
		return (0);
	}

	if (pd != NULL && !pd->pd_exited && prefetch_needed(pd, bp)) {
		uint64_t size = BP_GET_LSIZE(bp);
		mutex_enter(&pd->pd_mtx);
		ASSERT(pd->pd_bytes_fetched >= 0);
		while (pd->pd_bytes_fetched < size && !pd->pd_exited)
			cv_wait(&pd->pd_cv, &pd->pd_mtx);
		pd->pd_bytes_fetched -= size;
		cv_broadcast(&pd->pd_cv);
		mutex_exit(&pd->pd_mtx);
	}

	if (BP_IS_HOLE(bp)) {
		err = td->td_func(td->td_spa, NULL, bp, zb, dnp, td->td_arg);
		if (err != 0)
			goto post;
		return (0);
	}

	if (td->td_flags & TRAVERSE_PRE) {
		err = td->td_func(td->td_spa, NULL, bp, zb, dnp,
		    td->td_arg);
		if (err == TRAVERSE_VISIT_NO_CHILDREN)
			return (0);
		if (err != 0)
			goto post;
	}

	if (BP_GET_LEVEL(bp) > 0) {
		arc_flags_t flags = ARC_FLAG_WAIT;
		int i;
		blkptr_t *cbp;
		int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;

		err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
		if (err != 0)
			goto post;
		cbp = buf->b_data;

		for (i = 0; i < epb; i++) {
			SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
			    zb->zb_level - 1,
			    zb->zb_blkid * epb + i);
			traverse_prefetch_metadata(td, &cbp[i], &czb);
		}

		/* recursively visitbp() blocks below this */
//.........这里部分代码省略.........

//.........这里部分代码省略.........
	/*
	 * Clear the retry write flag if the buffer was written without
	 * error.  The presence of B_DELWRI means the buffer has not yet
	 * been written and the presence of B_ERROR means that an error
	 * is still occurring.
	 */
	if ((bp->b_flags & (B_ERROR | B_DELWRI | B_RETRYWRI)) == B_RETRYWRI) {
		bp->b_flags &= ~B_RETRYWRI;
	}

	/* Check for anomalous conditions */
	if (bp->b_flags & (B_ERROR|B_NOCACHE)) {
		if (bp->b_flags & B_NOCACHE) {
			/* Don't add to the freelist. Destroy it now */
			kmem_free(bp->b_un.b_addr, bp->b_bufsize);
			sema_destroy(&bp->b_sem);
			sema_destroy(&bp->b_io);
			kmem_free(bp, sizeof (struct buf));
			return;
		}
		/*
		 * If a write failed and we are supposed to retry write,
		 * don't toss the buffer.  Keep it around and mark it
		 * delayed write in the hopes that it will eventually
		 * get flushed (and still keep the system running.)
		 */
		if ((bp->b_flags & (B_READ | B_RETRYWRI)) == B_RETRYWRI) {
			bp->b_flags |= B_DELWRI;
			/* keep fsflush from trying continuously to flush */
			bp->b_start = ddi_get_lbolt();
		} else
			bp->b_flags |= B_AGE|B_STALE;
		bp->b_flags &= ~B_ERROR;
		bp->b_error = 0;
	}

	/*
	 * If delayed write is set then put in on the delayed
	 * write list instead of the free buffer list.
	 */
	index = bio_bhash(bp->b_edev, bp->b_blkno);
	hmp   = &hbuf[index].b_lock;

	mutex_enter(hmp);
	hp = &hbuf[index];
	dp = (struct buf *)hp;

	/*
	 * Make sure that the number of entries on this list are
	 * Zero <= count <= total # buffers
	 */
	ASSERT(hp->b_length >= 0);
	ASSERT(hp->b_length < nbuf);

	hp->b_length++;		/* We are adding this buffer */

	if (bp->b_flags & B_DELWRI) {
		/*
		 * This buffer goes on the delayed write buffer list
		 */
		dp = (struct buf *)&dwbuf[index];
	}
	ASSERT(bp->b_bufsize > 0);
	ASSERT(bp->b_bcount > 0);
	ASSERT(bp->b_un.b_addr != NULL);

	if (bp->b_flags & B_AGE) {
		backp = &dp->av_forw;
		(*backp)->av_back = bp;
		bp->av_forw = *backp;
		*backp = bp;
		bp->av_back = dp;
	} else {
		backp = &dp->av_back;
		(*backp)->av_forw = bp;
		bp->av_back = *backp;
		*backp = bp;
		bp->av_forw = dp;
	}
	mutex_exit(hmp);

	if (bfreelist.b_flags & B_WANTED) {
		/*
		 * Should come here very very rarely.
		 */
		mutex_enter(&bfree_lock);
		if (bfreelist.b_flags & B_WANTED) {
			bfreelist.b_flags &= ~B_WANTED;
			cv_broadcast(&bio_mem_cv);
		}
		mutex_exit(&bfree_lock);
	}

	bp->b_flags &= ~(B_WANTED|B_BUSY|B_ASYNC);
	/*
	 * Don't let anyone get the buffer off the freelist before we
	 * release our hold on it.
	 */
	sema_v(&bp->b_sem);
}

/*
 * dm2s_event_handler - Mailbox event handler.
 */
void
dm2s_event_handler(scf_event_t event, void *arg)
{
	dm2s_t *dm2sp = (dm2s_t *)arg;
	queue_t	*rq;

	ASSERT(dm2sp != NULL);
	mutex_enter(&dm2sp->ms_lock);
	if (!(dm2sp->ms_state & DM2S_MB_INITED)) {
		/*
		 * Ignore all events if the state flag indicates that the
		 * mailbox not initialized, this may happen during the close.
		 */
		mutex_exit(&dm2sp->ms_lock);
		DPRINTF(DBG_MBOX,
		    ("Event(0x%X) received - Mailbox not inited\n", event));
		return;
	}
	switch (event) {
	case SCF_MB_CONN_OK:
		/*
		 * Now the mailbox is ready to use, lets wake up
		 * any one waiting for this event.
		 */
		dm2sp->ms_state |= DM2S_MB_CONN;
		cv_broadcast(&dm2sp->ms_wait);
		DPRINTF(DBG_MBOX, ("Event received = CONN_OK\n"));
		break;

	case SCF_MB_MSG_DATA:
		if (!DM2S_MBOX_READY(dm2sp)) {
			DPRINTF(DBG_MBOX,
			    ("Event(MSG_DATA) received - Mailbox not READY\n"));
			break;
		}
		/*
		 * A message is available in the mailbox.
		 * Lets enable the read service procedure
		 * to receive this message.
		 */
		if (dm2sp->ms_rq != NULL) {
			qenable(dm2sp->ms_rq);
		}
		DPRINTF(DBG_MBOX, ("Event received = MSG_DATA\n"));
		break;

	case SCF_MB_SPACE:
		if (!DM2S_MBOX_READY(dm2sp)) {
			DPRINTF(DBG_MBOX,
			    ("Event(MB_SPACE) received - Mailbox not READY\n"));
			break;
		}

		/*
		 * Now the mailbox is ready to transmit, lets
		 * schedule the write service procedure.
		 */
		if (dm2sp->ms_wq != NULL) {
			qenable(dm2sp->ms_wq);
		}
		DPRINTF(DBG_MBOX, ("Event received = MB_SPACE\n"));
		break;
	case SCF_MB_DISC_ERROR:
		dm2sp->ms_state |= DM2S_MB_DISC;
		if (dm2sp->ms_state & DM2S_MB_CONN) {
			/*
			 * If it was previously connected,
			 * then send a hangup message.
			 */
			rq = dm2sp->ms_rq;
			if (rq != NULL) {
				mutex_exit(&dm2sp->ms_lock);
				/*
				 * Send a hangup message to indicate
				 * disconnect event.
				 */
				(void) putctl(rq, M_HANGUP);
				DTRACE_PROBE1(dm2s_hangup, dm2s_t, dm2sp);
				mutex_enter(&dm2sp->ms_lock);
			}
		} else {
			/*
			 * Signal if the open is waiting for a
			 * connection.
			 */
			cv_broadcast(&dm2sp->ms_wait);
		}
		DPRINTF(DBG_MBOX, ("Event received = DISC_ERROR\n"));
		break;
	default:
		cmn_err(CE_WARN, "Unexpected event received\n");
		break;
	}
	mutex_exit(&dm2sp->ms_lock);
}

static int				/* ERRNO if error, 0 if ok */
syscall_stage_response(
	sam_mount_t *mp,		/* pointer to mount entry. */
	sam_fsstage_arg_t *stage,	/* pointer to syscall stage response */
	rval_t *rvp,			/* returned value pointer */
	cred_t *credp)			/* credentials pointer. */
{
	sam_handle_t *fhandle;
	sam_node_t *ip;
	vnode_t *vp;
	int	error;
	int opened = 0;

	rvp->r_val1 = 0;

	fhandle = (sam_handle_t *)&stage->handle;

	/* Is this inode still waiting for the stage? */
	if ((error = sam_find_ino(mp->mi.m_vfsp, IG_EXISTS,
	    &fhandle->id, &ip))) {
		return (ECANCELED);
	}
	vp = SAM_ITOV(ip);
	if (stage->ret_err == EEXIST) {
		/*
		 * Outstanding stage request already exists, wake up anyone
		 * waiting
		 */
		mutex_enter(&ip->rm_mutex);
		if (ip->rm_wait)  cv_broadcast(&ip->rm_cv);
		mutex_exit(&ip->rm_mutex);

		sam_rele_ino(ip);
		return (0);
	}
	RW_LOCK_OS(&ip->inode_rwl, RW_WRITER);
	if (ip->stage_pid > 0) {
		/*
		 * Another stage is in progress. This can happen if the incore
		 * inode is released after a nowait stage for copy 1, then stage
		 * for copy 2.
		 */
		RW_UNLOCK_OS(&ip->inode_rwl, RW_WRITER);
		sam_rele_ino(ip);
		return (ECANCELED);
	}
	ip->flags.b.staging = 1;	/* Reset for acquired incore inode */
	ip->copy = 0;
	ip->stage_off = fhandle->stage_off;
	ip->stage_len = fhandle->stage_len;
	if (stage->ret_err == 0) {
		if ((!ip->di.status.b.offline &&
		    !(ip->di.rm.ui.flags & RM_DATA_VERIFY)) ||
		    !ip->di.arch_status ||
		    ip->stage_err) {
			error = ECANCELED;
			TRACE(T_SAM_IOCTL_STCAN, vp,
			    fhandle->id.ino, ip->stage_err,
			    ip->flags.bits);
		} else {
			offset_t cur_size = ip->size;

			error = 0;
			if (!fhandle->flags.b.stage_wait) {
				/*
				 * Allocate file now for nowait stage.
				 *
				 * Assert
				 * permissions based on the uid of the handle
				 * structure, not the stager.  Root can force
				 * staging, but users have to live with quotas.
				 */
				if (ip->di.blocks == 0) {
					error =
					    sam_set_unit(ip->mp, &(ip->di));
				}
				if (error == 0) {
					error = sam_map_block(ip, ip->stage_off,
					    ip->stage_len,
					    SAM_WRITE_BLOCK, NULL, credp);
					ip->size = cur_size;
				}
			}

			if (error == 0) {
				/*
				 * Simulate the open because we don't
				 * have the path.
				 */
				if ((error = sam_get_fd(vp,
				    &rvp->r_val1)) == 0) {
					if (vp->v_type == VREG) {
						atomic_add_32(&vp->v_rdcnt, 1);
						atomic_add_32(&vp->v_wrcnt, 1);
					}
					ip->stage_pid = SAM_CUR_PID;
					ip->no_opens++;
					opened = 1;
					if (stage->directio) {
						sam_set_directio(ip,
//.........这里部分代码省略.........

static int
traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
    arc_buf_t *pbuf, blkptr_t *bp, const zbookmark_t *zb)
{
	zbookmark_t czb;
	int err = 0, lasterr = 0;
	arc_buf_t *buf = NULL;
	prefetch_data_t *pd = td->td_pfd;
	boolean_t hard = td->td_flags & TRAVERSE_HARD;
	boolean_t pause = B_FALSE;

	switch (resume_skip_check(td, dnp, zb)) {
	case RESUME_SKIP_ALL:
		return (0);
	case RESUME_SKIP_CHILDREN:
		goto post;
	case RESUME_SKIP_NONE:
		break;
	default:
		ASSERT(0);
	}

	if (BP_IS_HOLE(bp)) {
		err = td->td_func(td->td_spa, NULL, NULL, pbuf, zb, dnp,
		    td->td_arg);
		return (err);
	}

	if (bp->blk_birth <= td->td_min_txg)
		return (0);

	if (pd && !pd->pd_exited &&
	    ((pd->pd_flags & TRAVERSE_PREFETCH_DATA) ||
	    BP_GET_TYPE(bp) == DMU_OT_DNODE || BP_GET_LEVEL(bp) > 0)) {
		mutex_enter(&pd->pd_mtx);
		ASSERT(pd->pd_blks_fetched >= 0);
		while (pd->pd_blks_fetched == 0 && !pd->pd_exited)
			cv_wait(&pd->pd_cv, &pd->pd_mtx);
		pd->pd_blks_fetched--;
		cv_broadcast(&pd->pd_cv);
		mutex_exit(&pd->pd_mtx);
	}

	if (td->td_flags & TRAVERSE_PRE) {
		err = td->td_func(td->td_spa, NULL, bp, pbuf, zb, dnp,
		    td->td_arg);
		if (err == TRAVERSE_VISIT_NO_CHILDREN)
			return (0);
		if (err == ERESTART)
			pause = B_TRUE; /* handle pausing at a common point */
		if (err != 0)
			goto post;
	}

	if (BP_GET_LEVEL(bp) > 0) {
		uint32_t flags = ARC_WAIT;
		int i;
		blkptr_t *cbp;
		int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;

		err = dsl_read(NULL, td->td_spa, bp, pbuf,
		    arc_getbuf_func, &buf,
		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
		if (err)
			return (err);

		/* recursively visitbp() blocks below this */
		cbp = buf->b_data;
		for (i = 0; i < epb; i++, cbp++) {
			SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
			    zb->zb_level - 1,
			    zb->zb_blkid * epb + i);
			err = traverse_visitbp(td, dnp, buf, cbp, &czb);
			if (err) {
				if (!hard)
					break;
				lasterr = err;
			}
		}
	} else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {

static void
rtems_bsd_sim_set_state_and_notify(struct cam_sim *sim, enum bsd_sim_state state)
{
	sim->state = state;
	cv_broadcast(&sim->state_changed);
}

/*
 * This routine is used to notify the framework when a provider is being
 * removed.  Hardware providers call this routine in their detach routines.
 * Software providers call this routine in their _fini() routine.
 */
int
crypto_unregister_provider(crypto_kcf_provider_handle_t handle)
{
	uint_t mech_idx;
	kcf_provider_desc_t *desc;
	kcf_prov_state_t saved_state;

	/* lookup provider descriptor */
	if ((desc = kcf_prov_tab_lookup((crypto_provider_id_t)handle)) == NULL)
		return (CRYPTO_UNKNOWN_PROVIDER);

	mutex_enter(&desc->pd_lock);
	/*
	 * Check if any other thread is disabling or removing
	 * this provider. We return if this is the case.
	 */
	if (desc->pd_state >= KCF_PROV_DISABLED) {
		mutex_exit(&desc->pd_lock);
		/* Release reference held by kcf_prov_tab_lookup(). */
		KCF_PROV_REFRELE(desc);
		return (CRYPTO_BUSY);
	}

	saved_state = desc->pd_state;
	desc->pd_state = KCF_PROV_REMOVED;

	if (saved_state == KCF_PROV_BUSY) {
		/*
		 * The per-provider taskq threads may be waiting. We
		 * signal them so that they can start failing requests.
		 */
		cv_broadcast(&desc->pd_resume_cv);
	}

	if (desc->pd_prov_type == CRYPTO_SW_PROVIDER) {
		/*
		 * Check if this provider is currently being used.
		 * pd_irefcnt is the number of holds from the internal
		 * structures. We add one to account for the above lookup.
		 */
		if (desc->pd_refcnt > desc->pd_irefcnt + 1) {
			desc->pd_state = saved_state;
			mutex_exit(&desc->pd_lock);
			/* Release reference held by kcf_prov_tab_lookup(). */
			KCF_PROV_REFRELE(desc);
			/*
			 * The administrator presumably will stop the clients
			 * thus removing the holds, when they get the busy
			 * return value.  Any retry will succeed then.
			 */
			return (CRYPTO_BUSY);
		}
	}
	mutex_exit(&desc->pd_lock);

	if (desc->pd_prov_type != CRYPTO_SW_PROVIDER) {
		remove_provider(desc);
	}

	if (desc->pd_prov_type != CRYPTO_LOGICAL_PROVIDER) {
		/* remove the provider from the mechanisms tables */
		for (mech_idx = 0; mech_idx < desc->pd_mech_list_count;
		    mech_idx++) {
			kcf_remove_mech_provider(
			    desc->pd_mechanisms[mech_idx].cm_mech_name, desc);
		}
	}

	/* remove provider from providers table */
	if (kcf_prov_tab_rem_provider((crypto_provider_id_t)handle) !=
	    CRYPTO_SUCCESS) {
		/* Release reference held by kcf_prov_tab_lookup(). */
		KCF_PROV_REFRELE(desc);
		return (CRYPTO_UNKNOWN_PROVIDER);
	}

	delete_kstat(desc);

	if (desc->pd_prov_type == CRYPTO_SW_PROVIDER) {
		/* Release reference held by kcf_prov_tab_lookup(). */
		KCF_PROV_REFRELE(desc);

		/*
		 * Wait till the existing requests complete.
		 */
		mutex_enter(&desc->pd_lock);
		while (desc->pd_state != KCF_PROV_FREED)
			cv_wait(&desc->pd_remove_cv, &desc->pd_lock);
		mutex_exit(&desc->pd_lock);
	} else {
		/*
		 * Wait until requests that have been sent to the provider
		 * complete.
		 */
		mutex_enter(&desc->pd_lock);
//.........这里部分代码省略.........

//.........这里部分代码省略.........

	/*
	 * Clear the lwp directory and the lwpid hash table
	 * now that /proc can't bother us any more.
	 * We free the memory below, after dropping p->p_lock.
	 */
	lwpdir = p->p_lwpdir;
	lwpdir_sz = p->p_lwpdir_sz;
	tidhash = p->p_tidhash;
	tidhash_sz = p->p_tidhash_sz;
	ret_tidhash = p->p_ret_tidhash;
	p->p_lwpdir = NULL;
	p->p_lwpfree = NULL;
	p->p_lwpdir_sz = 0;
	p->p_tidhash = NULL;
	p->p_tidhash_sz = 0;
	p->p_ret_tidhash = NULL;

	/*
	 * If the process has context ops installed, call the exit routine
	 * on behalf of this last remaining thread. Normally exitpctx() is
	 * called during thread_exit() or lwp_exit(), but because this is the
	 * last thread in the process, we must call it here. By the time
	 * thread_exit() is called (below), the association with the relevant
	 * process has been lost.
	 *
	 * We also free the context here.
	 */
	if (p->p_pctx) {
		kpreempt_disable();
		exitpctx(p);
		kpreempt_enable();

		freepctx(p, 0);
	}

	/*
	 * curthread's proc pointer is changed to point to the 'sched'
	 * process for the corresponding zone, except in the case when
	 * the exiting process is in fact a zsched instance, in which
	 * case the proc pointer is set to p0.  We do so, so that the
	 * process still points at the right zone when we call the VN_RELE()
	 * below.
	 *
	 * This is because curthread's original proc pointer can be freed as
	 * soon as the child sends a SIGCLD to its parent.  We use zsched so
	 * that for user processes, even in the final moments of death, the
	 * process is still associated with its zone.
	 */
	if (p != t->t_procp->p_zone->zone_zsched)
		t->t_procp = t->t_procp->p_zone->zone_zsched;
	else
		t->t_procp = &p0;

	mutex_exit(&p->p_lock);
	if (!evaporate) {
		p->p_pidflag &= ~CLDPEND;
		sigcld(p, sqp);
	} else {
		/*
		 * Do what sigcld() would do if the disposition
		 * of the SIGCHLD signal were set to be ignored.
		 */
		cv_broadcast(&p->p_srwchan_cv);
		freeproc(p);
	}
	mutex_exit(&pidlock);

	/*
	 * We don't release u_cdir and u_rdir until SZOMB is set.
	 * This protects us against dofusers().
	 */
	if (cdir)
		VN_RELE(cdir);
	if (rdir)
		VN_RELE(rdir);
	if (cwd)
		refstr_rele(cwd);

	/*
	 * task_rele() may ultimately cause the zone to go away (or
	 * may cause the last user process in a zone to go away, which
	 * signals zsched to go away).  So prior to this call, we must
	 * no longer point at zsched.
	 */
	t->t_procp = &p0;

	kmem_free(lwpdir, lwpdir_sz * sizeof (lwpdir_t));
	kmem_free(tidhash, tidhash_sz * sizeof (tidhash_t));
	while (ret_tidhash != NULL) {
		ret_tidhash_t *next = ret_tidhash->rth_next;
		kmem_free(ret_tidhash->rth_tidhash,
		    ret_tidhash->rth_tidhash_sz * sizeof (tidhash_t));
		kmem_free(ret_tidhash, sizeof (*ret_tidhash));
		ret_tidhash = next;
	}

	thread_exit();
	/* NOTREACHED */
}

/*------------------------------------------------------------------------*
 *	usb_process
 *
 * This function is the USB process dispatcher.
 *------------------------------------------------------------------------*/
static void
usb_process(void *arg)
{
	struct usb_process *up = arg;
	struct usb_proc_msg *pm;
	struct thread *td;

	/* in case of attach error, check for suspended */
	USB_THREAD_SUSPEND_CHECK();

	/* adjust priority */
	td = curthread;
	thread_lock(td);
	sched_prio(td, up->up_prio);
	thread_unlock(td);

	mtx_lock(up->up_mtx);

	up->up_curtd = td;

	while (1) {

		if (up->up_gone)
			break;

		/*
		 * NOTE to reimplementors: dequeueing a command from the
		 * "used" queue and executing it must be atomic, with regard
		 * to the "up_mtx" mutex. That means any attempt to queue a
		 * command by another thread must be blocked until either:
		 *
		 * 1) the command sleeps
		 *
		 * 2) the command returns
		 *
		 * Here is a practical example that shows how this helps
		 * solving a problem:
		 *
		 * Assume that you want to set the baud rate on a USB serial
		 * device. During the programming of the device you don't
		 * want to receive nor transmit any data, because it will be
		 * garbage most likely anyway. The programming of our USB
		 * device takes 20 milliseconds and it needs to call
		 * functions that sleep.
		 *
		 * Non-working solution: Before we queue the programming
		 * command, we stop transmission and reception of data. Then
		 * we queue a programming command. At the end of the
		 * programming command we enable transmission and reception
		 * of data.
		 *
		 * Problem: If a second programming command is queued while the
		 * first one is sleeping, we end up enabling transmission
		 * and reception of data too early.
		 *
		 * Working solution: Before we queue the programming command,
		 * we stop transmission and reception of data. Then we queue
		 * a programming command. Then we queue a second command
		 * that only enables transmission and reception of data.
		 *
		 * Why it works: If a second programming command is queued
		 * while the first one is sleeping, then the queueing of a
		 * second command to enable the data transfers, will cause
		 * the previous one, which is still on the queue, to be
		 * removed from the queue, and re-inserted after the last
		 * baud rate programming command, which then gives the
		 * desired result.
		 */
		pm = TAILQ_FIRST(&up->up_qhead);

		if (pm) {
			DPRINTF("Message pm=%p, cb=%p (enter)\n",
			    pm, pm->pm_callback);

			(pm->pm_callback) (pm);

			if (pm == TAILQ_FIRST(&up->up_qhead)) {
				/* nothing changed */
				TAILQ_REMOVE(&up->up_qhead, pm, pm_qentry);
				pm->pm_qentry.tqe_prev = NULL;
			}
			DPRINTF("Message pm=%p (leave)\n", pm);

			continue;
		}
		/* end if messages - check if anyone is waiting for sync */
		if (up->up_dsleep) {
			up->up_dsleep = 0;
			cv_broadcast(&up->up_drain);
		}
		up->up_msleep = 1;
		cv_wait(&up->up_cv, up->up_mtx);
	}

	up->up_ptr = NULL;
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		ASSERT(asize >= size);

		if (lpthrt != 0) {
			/* try to update the throttle value */
			lpthrt = atomic_inc_ulong_nv(lpthrtp);
			if (lpthrt >= segkmem_lpthrottle_max) {
				lpthrt = atomic_cas_ulong(lpthrtp, lpthrt,
				    segkmem_lpthrottle_max / 4);
			}

			/*
			 * when we get above throttle start do an exponential
			 * backoff at trying large pages and reaping
			 */
			if (lpthrt > segkmem_lpthrottle_start &&
			    !ISP2(lpthrt)) {
				lpcb->allocs_throttled++;
				lpthrt--;
				if (ISP2(lpthrt))
					kmem_reap();
				return (segkmem_alloc(vmp, size, vmflag));
			}
		}

		if (!(vmflag & VM_NOSLEEP) &&
		    segkmem_heaplp_quantum >= (8 * kmemlp_qnt) &&
		    vmem_size(kmem_lp_arena, VMEM_FREE) <= kmemlp_qnt &&
		    asize < (segkmem_heaplp_quantum - kmemlp_qnt)) {

			/*
			 * we are low on free memory in kmem_lp_arena
			 * we let only one guy to allocate heap_lp
			 * quantum size chunk that everybody is going to
			 * share
			 */
			mutex_enter(&lpcb->lp_lock);

			if (lpcb->lp_wait) {

				/* we are not the first one - wait */
				cv_wait(&lpcb->lp_cv, &lpcb->lp_lock);
				if (vmem_size(kmem_lp_arena, VMEM_FREE) <
				    kmemlp_qnt)  {
					doalloc = 0;
				}
			} else if (vmem_size(kmem_lp_arena, VMEM_FREE) <=
			    kmemlp_qnt) {

				/*
				 * we are the first one, make sure we import
				 * a large page
				 */
				if (asize == kmemlp_qnt)
					asize += kmemlp_qnt;
				dowakeup = 1;
				lpcb->lp_wait = 1;
			}

			mutex_exit(&lpcb->lp_lock);
		}

		/*
		 * VM_ABORT flag prevents sleeps in vmem_xalloc when
		 * large pages are not available. In that case this allocation
		 * attempt will fail and we will retry allocation with small
		 * pages. We also do not want to panic if this allocation fails
		 * because we are going to retry.
		 */
		if (doalloc) {
			addr = vmem_alloc(kmem_lp_arena, asize,
			    (vmflag | VM_ABORT) & ~VM_PANIC);

			if (dowakeup) {
				mutex_enter(&lpcb->lp_lock);
				ASSERT(lpcb->lp_wait != 0);
				lpcb->lp_wait = 0;
				cv_broadcast(&lpcb->lp_cv);
				mutex_exit(&lpcb->lp_lock);
			}
		}

		if (addr != NULL) {
			*sizep = asize;
			*lpthrtp = 0;
			return (addr);
		}

		if (vmflag & VM_NOSLEEP)
			lpcb->nosleep_allocs_failed++;
		else
			lpcb->sleep_allocs_failed++;
		lpcb->alloc_bytes_failed += size;

		/* if large page throttling is not started yet do it */
		if (segkmem_use_lpthrottle && lpthrt == 0) {
			lpthrt = atomic_cas_ulong(lpthrtp, lpthrt, 1);
		}
	}
	return (segkmem_alloc(vmp, size, vmflag));
}

//.........这里部分代码省略.........
		aprint_error_dev(atabus_sc->sc_dev,
		    "SATA port multiplier not supported\n");
		/* no problems going on, all drives are ATA_DRIVET_NONE */
#endif
	}

	/*
	 * Attach an ATAPI bus, if needed.
	 */
	KASSERT(chp->ch_ndrives == 0 || chp->ch_drive != NULL);
	for (i = 0; i < chp->ch_ndrives && chp->atapibus == NULL; i++) {
		if (chp->ch_drive[i].drive_type == ATA_DRIVET_ATAPI) {
#if NATAPIBUS > 0
			(*atac->atac_atapibus_attach)(atabus_sc);
#else
			/*
			 * Fake the autoconfig "not configured" message
			 */
			aprint_normal("atapibus at %s not configured\n",
			    device_xname(atac->atac_dev));
			chp->atapibus = NULL;
			s = splbio();
			for (i = 0; i < chp->ch_ndrives; i++) {
				if (chp->ch_drive[i].drive_type == ATA_DRIVET_ATAPI)
					chp->ch_drive[i].drive_type = ATA_DRIVET_NONE;
			}
			splx(s);
#endif
			break;
		}
	}

	for (i = 0; i < chp->ch_ndrives; i++) {
		struct ata_device adev;
		if (chp->ch_drive[i].drive_type != ATA_DRIVET_ATA &&
		    chp->ch_drive[i].drive_type != ATA_DRIVET_OLD) {
			continue;
		}
		if (chp->ch_drive[i].drv_softc != NULL)
			continue;
		memset(&adev, 0, sizeof(struct ata_device));
		adev.adev_bustype = atac->atac_bustype_ata;
		adev.adev_channel = chp->ch_channel;
		adev.adev_openings = 1;
		adev.adev_drv_data = &chp->ch_drive[i];
		chp->ch_drive[i].drv_softc = config_found_ia(atabus_sc->sc_dev,
		    "ata_hl", &adev, ataprint);
		if (chp->ch_drive[i].drv_softc != NULL) {
			ata_probe_caps(&chp->ch_drive[i]);
		} else {
			s = splbio();
			chp->ch_drive[i].drive_type = ATA_DRIVET_NONE;
			splx(s);
		}
	}

	/* now that we know the drives, the controller can set its modes */
	if (atac->atac_set_modes) {
		(*atac->atac_set_modes)(chp);
		ata_print_modes(chp);
	}
#if NATARAID > 0
	if (atac->atac_cap & ATAC_CAP_RAID) {
		for (i = 0; i < chp->ch_ndrives; i++) {
			if (chp->ch_drive[i].drive_type == ATA_DRIVET_ATA) {
				ata_raid_check_component(
				    chp->ch_drive[i].drv_softc);
			}
		}
	}
#endif /* NATARAID > 0 */

	/*
	 * reset drive_flags for unattached devices, reset state for attached
	 * ones
	 */
	s = splbio();
	for (i = 0; i < chp->ch_ndrives; i++) {
		if (chp->ch_drive[i].drive_type == ATA_DRIVET_PM)
			continue;
		if (chp->ch_drive[i].drv_softc == NULL) {
			chp->ch_drive[i].drive_flags = 0;
			chp->ch_drive[i].drive_type = ATA_DRIVET_NONE;
		} else
			chp->ch_drive[i].state = 0;
	}
	splx(s);

	mutex_enter(&atabus_qlock);
	TAILQ_REMOVE(&atabus_initq_head, atabus_initq, atabus_initq);
	cv_broadcast(&atabus_qcv);
	mutex_exit(&atabus_qlock);

	free(atabus_initq, M_DEVBUF);

	ata_delref(chp);

	config_pending_decr(atac->atac_dev);
	kthread_exit(0);
}

static void
atabusconfig(struct atabus_softc *atabus_sc)
{
	struct ata_channel *chp = atabus_sc->sc_chan;
	struct atac_softc *atac = chp->ch_atac;
	struct atabus_initq *atabus_initq = NULL;
	int i, s, error;

	/* we are in the atabus's thread context */
	s = splbio();
	chp->ch_flags |= ATACH_TH_RUN;
	splx(s);

	/*
	 * Probe for the drives attached to controller, unless a PMP
	 * is already known
	 */
	/* XXX for SATA devices we will power up all drives at once */
	if (chp->ch_satapmp_nports == 0)
		(*atac->atac_probe)(chp);

	if (chp->ch_ndrives >= 2) {
		ATADEBUG_PRINT(("atabusattach: ch_drive_type 0x%x 0x%x\n",
		    chp->ch_drive[0].drive_type, chp->ch_drive[1].drive_type),
		    DEBUG_PROBE);
	}

	/* next operations will occurs in a separate thread */
	s = splbio();
	chp->ch_flags &= ~ATACH_TH_RUN;
	splx(s);

	/* Make sure the devices probe in atabus order to avoid jitter. */
	mutex_enter(&atabus_qlock);
	for (;;) {
		atabus_initq = TAILQ_FIRST(&atabus_initq_head);
		if (atabus_initq->atabus_sc == atabus_sc)
			break;
		cv_wait(&atabus_qcv, &atabus_qlock);
	}
	mutex_exit(&atabus_qlock);

	/* If no drives, abort here */
	if (chp->ch_drive == NULL)
		goto out;
	KASSERT(chp->ch_ndrives == 0 || chp->ch_drive != NULL);
	for (i = 0; i < chp->ch_ndrives; i++)
		if (chp->ch_drive[i].drive_type != ATA_DRIVET_NONE)
			break;
	if (i == chp->ch_ndrives)
		goto out;

	/* Shortcut in case we've been shutdown */
	if (chp->ch_flags & ATACH_SHUTDOWN)
		goto out;

	if ((error = kthread_create(PRI_NONE, 0, NULL, atabusconfig_thread,
	    atabus_sc, &atabus_cfg_lwp,
	    "%scnf", device_xname(atac->atac_dev))) != 0)
		aprint_error_dev(atac->atac_dev,
		    "unable to create config thread: error %d\n", error);
	return;

 out:
	mutex_enter(&atabus_qlock);
	TAILQ_REMOVE(&atabus_initq_head, atabus_initq, atabus_initq);
	cv_broadcast(&atabus_qcv);
	mutex_exit(&atabus_qlock);

	free(atabus_initq, M_DEVBUF);

	ata_delref(chp);

	config_pending_decr(atac->atac_dev);
}

/**
 * instructor - Piazza answer-editing thread.
 *
 * Each instructor thread should, for NCYCLES iterations, choose a random
 * Piazza question and then update the answer.  The answer should always
 * consist of a lowercase alphabetic character repeated 10 times, e.g.,
 *
 *    "aaaaaaaaaa"
 *
 * and each update should increment all ten characters (cycling back to a's
 * from z's if a question is updated enough times).
 *
 * After each update, (including the first update, in which you should create
 * the question and initialize the answer to all a's), the instructor should
 * print the answer string using piazza_print().
 *
 * TODO: Implement this.
 */
static void
instructor(void *p, unsigned long which)
{
  (void)p;
  (void)which;

  int i, n;
  char letter, *pos;

  for (i = 0; i < NCYCLES; ++i) {
    // Choose a random Piazza question.
    n = random() % NANSWERS;

    // If first instructor to see the question, initalize answers
    lock_acquire(creation_lock[n]);
    if (questions[n] == NULL) {
      questions[n] = kmalloc(sizeof(struct piazza_question));
      questions[n]->mutex = lock_create("mutex");
      questions[n]->readerQ = cv_create("readerQ");
      questions[n]->writerQ = cv_create("writerQ");
      questions[n]->readers = 0;
      questions[n]->writers = 0;
      questions[n]->active_writer = 0;

      const char *answer = "aaaaaaaaaa"; //TODO: have const here?
      questions[n]->pq_answer = kstrdup(answer);      

      lock_release(creation_lock[n]);

      // Print submitted answer
      piazza_print(n);
    }

    // Not the first instructor
    else{
      lock_release(creation_lock[n]);

      // Set up writer lock
      lock_acquire(questions[n]->mutex);
      questions[n]->writers++;
      while(!((questions[n]->readers == 0) && (questions[n]->active_writer == 0)))
        cv_wait(questions[n]->writerQ, questions[n]->mutex);
      questions[n]->active_writer++;
      lock_release(questions[n]->mutex);

      /* Start write */
      pos = questions[n]->pq_answer;
      letter = *pos;

      // Update answer
      if(letter != 'z'){
        while (*(pos) == letter) {
          (*pos)++;
          pos++;
        }        
      }

      // Loop answer back to A's
      else{
        while (*(pos) == letter) {
          *pos = 'a';
          pos++;
        }
      }
    
      // Print submitted answer
      piazza_print(n);

      /* End write */

      // Clean up writer lock
      lock_acquire(questions[n]->mutex);
      questions[n]->active_writer--;
      questions[n]->writers--;
      if(questions[n]->writers==0)
        cv_broadcast(questions[n]->readerQ, questions[n]->mutex);
      else
        cv_signal(questions[n]->writerQ, questions[n]->mutex);
      lock_release(questions[n]->mutex);
    }
  }
  // Exiting thread
//.........这里部分代码省略.........