C++ MUTEX_HELD函数代码示例

static int
__zvol_remove_minor(const char *name)
{
	zvol_state_t *zv;

	ASSERT(MUTEX_HELD(&zvol_state_lock));

	zv = zvol_find_by_name(name);
	if (zv == NULL)
		return (ENXIO);

	if (zv->zv_open_count > 0)
		return (EBUSY);

	zvol_remove(zv);
	zvol_free(zv);

	return (0);
}

/*
 * Find the multicast address `addr', return B_TRUE if it is one that
 * we receive. If `remove', remove it from the set received.
 */
static boolean_t
xnbo_mcast_find(xnb_t *xnbp, ether_addr_t *addr, boolean_t remove)
{
	xnbo_t *xnbop = xnbp->xnb_flavour_data;
	xmca_t *prev, *del, *this;

	ASSERT(MUTEX_HELD(&xnbp->xnb_state_lock));
	ASSERT(xnbop->o_promiscuous == B_FALSE);

	prev = del = NULL;

	this = xnbop->o_mca;

	while (this != NULL) {
		if (bcmp(&this->addr, addr, sizeof (this->addr)) == 0) {
			del = this;
			if (remove) {
				if (prev == NULL)
					xnbop->o_mca = this->next;
				else
					prev->next = this->next;
			}
			break;
		}

		prev = this;
		this = this->next;
	}

	if (del == NULL)
		return (B_FALSE);

	if (remove) {
		DTRACE_PROBE3(mcast_remove,
		    (char *), "remove",
		    (void *), xnbp,
		    (etheraddr_t *), del->addr);
		mac_multicast_remove(xnbop->o_mch, del->addr);
		kmem_free(del, sizeof (*del));
	}

	return (B_TRUE);
}

/*
 * Rename a zfs_snapentry_t in the zfs_snapshots_by_name.  The structure is
 * removed, renamed, and added back to the new correct location in the tree.
 */
static int
zfsctl_snapshot_rename(char *old_snapname, char *new_snapname)
{
	zfs_snapentry_t *se;

	ASSERT(MUTEX_HELD(&zfs_snapshot_lock));

	se = zfsctl_snapshot_find_by_name(old_snapname);
	if (se == NULL)
		return (ENOENT);

	zfsctl_snapshot_remove(se);
	strfree(se->se_name);
	se->se_name = strdup(new_snapname);
	zfsctl_snapshot_add(se);
	zfsctl_snapshot_rele(se);

	return (0);
}

/*
 * The port_remove_fd_object() function frees all resources associated with
 * delivered portfd_t structure. Returns 1 if the port_kevent was found
 * and removed from the port queue.
 */
int
port_remove_fd_object(portfd_t *pfd, port_t *pp, port_fdcache_t *pcp)
{
	port_queue_t	*portq;
	polldat_t	*pdp = PFTOD(pfd);
	port_kevent_t	*pkevp;
	int		error;
	int		removed = 0;

	ASSERT(MUTEX_HELD(&pcp->pc_lock));
	if (pdp->pd_php != NULL) {
		pollhead_delete(pdp->pd_php, pdp);
		pdp->pd_php = NULL;
	}
	pkevp =  pdp->pd_portev;
	portq = &pp->port_queue;
	mutex_enter(&portq->portq_mutex);
	port_block(portq);
	if (pkevp->portkev_flags & PORT_KEV_DONEQ) {
		if (portq->portq_getn && portq->portq_tnent) {
			/*
			 * move events from the temporary "get" queue
			 * back to the port queue
			 */
			port_push_eventq(portq);
		}
		/* cleanup merged port queue */
		port_remove_event_doneq(pkevp, portq);
		removed = 1;
	}
	port_unblock(portq);
	mutex_exit(&portq->portq_mutex);
	if (pkevp->portkev_callback) {
		(void) (*pkevp->portkev_callback)(pkevp->portkev_arg,
		    &error, pkevp->portkev_pid, PORT_CALLBACK_DISSOCIATE,
		    pkevp);
	}
	port_free_event_local(pkevp, 0);

	/* remove polldat struct */
	port_pcache_remove_fd(pcp, pfd);
	return (removed);
}

/*
 * Search path of "offline:stop" status, and minimum path number
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_search_min_stop_path(void)
{
	upath_t	*upath, *min_upath;
	lpath_t	*lpath;
	int	min_no = UNDEFINED;
	int	active_flag = 0;

	ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
	ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));

	upath = oplmsu_uinst->first_upath;
	while (upath) {
		if ((upath->status == MSU_PSTAT_ACTIVE) &&
		    (upath->traditional_status == MSU_ACTIVE)) {
			active_flag = 1;
			break;
		} else if ((upath->status == MSU_PSTAT_STOP) &&
		    (upath->traditional_status == MSU_STOP)) {
			if (upath->lpath != NULL) {
				if ((min_no == UNDEFINED) ||
				    (upath->path_no < min_no)) {
					lpath = upath->lpath;
					mutex_enter(&oplmsu_uinst->l_lock);
					if (lpath->status == MSU_EXT_NOTUSED) {
						min_upath = upath;
						min_no = upath->path_no;
					}
					mutex_exit(&oplmsu_uinst->l_lock);
				}
			}
		}
		upath = upath->u_next;
	}

	if (active_flag == 0) {
		lpath = min_upath->lpath;
		mutex_enter(&oplmsu_uinst->l_lock);
		lpath->src_upath = NULL;
		lpath->status = MSU_EXT_ACTIVE_CANDIDATE;
		mutex_exit(&oplmsu_uinst->l_lock);
	}
}

/*
 * Check whether lower path is usable by lower path info table address
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : M
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_check_lpath_usable(void)
{
	lpath_t	*lpath;
	int	rval = SUCCESS;

	ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
	ASSERT(MUTEX_HELD(&oplmsu_uinst->l_lock));

	lpath = oplmsu_uinst->first_lpath;
	while (lpath) {
		if ((lpath->hndl_uqueue != NULL) || (lpath->hndl_mp != NULL)) {
			rval = BUSY;
			break;
		}
		lpath = lpath->l_next;
	}
	return (rval);
}

/*
 * Find the next available range of ZVOL_MINORS minor numbers.  The
 * zvol_state_list is kept in ascending minor order so we simply need
 * to scan the list for the first gap in the sequence.  This allows us
 * to recycle minor number as devices are created and removed.
 */
static int
zvol_find_minor(unsigned *minor)
{
	zvol_state_t *zv;

	*minor = 0;
	ASSERT(MUTEX_HELD(&zvol_state_lock));
	for (zv = list_head(&zvol_state_list); zv != NULL;
	     zv = list_next(&zvol_state_list, zv), *minor += ZVOL_MINORS) {
		if (MINOR(zv->zv_dev) != MINOR(*minor))
			break;
	}

	/* All minors are in use */
	if (*minor >= (1 << MINORBITS))
		return ENXIO;

	return 0;
}

/*
 * cyclic_expand() will cross call onto the CPU to perform the actual
 * expand operation.
 */
static void
cyclic_expand(cyc_cpu_t *cpu)
{
	cyc_index_t new_size, old_size;
	cyc_index_t *new_heap, *old_heap;
	cyclic_t *new_cyclics, *old_cyclics;
	cyc_xcallarg_t arg;
	cyc_backend_t *be = cpu->cyp_backend;

	ASSERT(MUTEX_HELD(&cpu_lock));

	old_heap = cpu->cyp_heap;
	old_cyclics = cpu->cyp_cyclics;

	if ((new_size = ((old_size = cpu->cyp_size) << 1)) == 0) {
		new_size = CY_DEFAULT_PERCPU;
		ASSERT(old_heap == NULL && old_cyclics == NULL);
	}

	/*
	 * Check that the new_size is a power of 2.
	 */
	ASSERT(((new_size - 1) & new_size) == 0);

	new_heap = malloc(sizeof(cyc_index_t) * new_size, M_CYCLIC, M_WAITOK);
	new_cyclics = malloc(sizeof(cyclic_t) * new_size, M_CYCLIC, M_ZERO | M_WAITOK);

	arg.cyx_cpu = cpu;
	arg.cyx_heap = new_heap;
	arg.cyx_cyclics = new_cyclics;
	arg.cyx_size = new_size;

	be->cyb_xcall(be->cyb_arg, cpu->cyp_cpu,
	    (cyc_func_t)cyclic_expand_xcall, &arg);

	if (old_cyclics != NULL) {
		ASSERT(old_heap != NULL);
		ASSERT(old_size != 0);
		free(old_cyclics, M_CYCLIC);
		free(old_heap, M_CYCLIC);
	}
}

/*
 * taskq_ent_alloc()
 *
 * Allocates a new taskq_ent_t structure either from the free list or from the
 * cache. Returns NULL if it can't be allocated.
 *
 * Assumes: tq->tq_lock is held.
 */
static taskq_ent_t *
taskq_ent_alloc(taskq_t *tq, int flags)
{
    int kmflags = KM_NOSLEEP;

    taskq_ent_t *tqe;

    ASSERT(MUTEX_HELD(&tq->tq_lock));

    /*
     * TQ_NOALLOC allocations are allowed to use the freelist, even if
     * we are below tq_minalloc.
     */
    if ((tqe = tq->tq_freelist) != NULL &&
            ((flags & TQ_NOALLOC) || tq->tq_nalloc >= tq->tq_minalloc)) {
        tq->tq_freelist = tqe->tqent_next;
    } else {
        if (flags & TQ_NOALLOC)
            return (NULL);

        mutex_exit(&tq->tq_lock);
        if (tq->tq_nalloc >= tq->tq_maxalloc) {
            if (kmflags & KM_NOSLEEP) {
                mutex_enter(&tq->tq_lock);
                return (NULL);
            }
            /*
             * We don't want to exceed tq_maxalloc, but we can't
             * wait for other tasks to complete (and thus free up
             * task structures) without risking deadlock with
             * the caller.  So, we just delay for one second
             * to throttle the allocation rate.
             */
            delay(hz);
        }
        tqe = kmem_cache_alloc(taskq_ent_cache, kmflags);
        mutex_enter(&tq->tq_lock);
        if (tqe != NULL)
            tq->tq_nalloc++;
    }
    return (tqe);
}

/*
 * Write to the PCF8591 chip.
 * byteaddress = chip type base address | chip offset address.
 */
int
ehc_write_pcf8591(struct ehc_envcunit *ehcp, int byteaddress, int channel,
	int autoinc, int amode, int aenable, uint8_t *buf, int size)
{
	int i, status;
	register uint8_t control;

	ASSERT((byteaddress & 0x1) == 0);
	ASSERT(MUTEX_HELD(&ehcp->umutex));

	control = ((aenable << 6) | (amode << 4) | (autoinc << 2) | channel);

	status = ehc_start_pcf8584(ehcp, byteaddress);
	if (status != EHC_SUCCESS) {
		if (status == EHC_NO_SLAVE_ACK) {
			/*
			 * Send the "stop" condition.
			 */
			ehc_stop_pcf8584(ehcp);
		}
		return (EHC_FAILURE);
	}

	if ((status = ehc_write_pcf8584(ehcp, control)) != EHC_SUCCESS) {
		if (status == EHC_NO_SLAVE_ACK)
			ehc_stop_pcf8584(ehcp);
		return (EHC_FAILURE);
	}

	for (i = 0; i < size; i++) {
		status = ehc_write_pcf8584(ehcp, buf[i]);
		if (status != EHC_SUCCESS) {
			if (status == EHC_NO_SLAVE_ACK)
				ehc_stop_pcf8584(ehcp);
			return (EHC_FAILURE);
		}
	}

	ehc_stop_pcf8584(ehcp);

	return (EHC_SUCCESS);
}

/*
 * Write to the PCF8574A chip.
 * byteaddress = chip type base address | chip offset address.
 */
int
ehc_write_pcf8574a(struct ehc_envcunit *ehcp, int byteaddress, uint8_t *buf,
	int size)
{
	int i;
	int status;

	ASSERT((byteaddress & 0x1) == 0);
	ASSERT(MUTEX_HELD(&ehcp->umutex));

	/*
	 * Put the bus into the start condition (write)
	 */
	if ((status = ehc_start_pcf8584(ehcp, byteaddress)) != EHC_SUCCESS) {
		if (status == EHC_NO_SLAVE_ACK) {
			/*
			 * Send the "stop" condition.
			 */
			ehc_stop_pcf8584(ehcp);
		}
		return (EHC_FAILURE);
	}

	/*
	 * Send the data - poll as needed.
	 */
	for (i = 0; i < size; i++) {
		if ((status = ehc_write_pcf8584(ehcp, buf[i])) != EHC_SUCCESS) {
			if (status == EHC_NO_SLAVE_ACK)
				ehc_stop_pcf8584(ehcp);
			return (EHC_FAILURE);
		}
	}

	/*
	 * Transmission complete - generate stop condition and
	 * put device back into slave receiver mode.
	 */
	ehc_stop_pcf8584(ehcp);

	return (EHC_SUCCESS);
}

/*
 * Similar to but more general than ip_sctp's conn_match().
 *
 * Matches sets of addresses as follows: if the argument addr set is
 * a complete subset of the corresponding addr set in the sctp_t, it
 * is a match.
 *
 * Caller must hold tf->tf_lock.
 *
 * Returns with a SCTP_REFHOLD sctp structure. Caller must do a SCTP_REFRELE.
 */
sctp_t *
sctp_lookup(sctp_t *sctp1, in6_addr_t *faddr, sctp_tf_t *tf, uint32_t *ports,
    int min_state)
{

	sctp_t *sctp;
	sctp_faddr_t *fp;

	ASSERT(MUTEX_HELD(&tf->tf_lock));

	for (sctp = tf->tf_sctp; sctp; sctp = sctp->sctp_conn_hash_next) {
		if (*ports != sctp->sctp_ports || sctp->sctp_state <
		    min_state) {
			continue;
		}

		/* check for faddr match */
		for (fp = sctp->sctp_faddrs; fp; fp = fp->next) {
			if (IN6_ARE_ADDR_EQUAL(faddr, &fp->faddr)) {
				break;
			}
		}

		if (!fp) {
			/* no faddr match; keep looking */
			continue;
		}

		/* check for laddr subset match */
		if (sctp_compare_saddrs(sctp1, sctp) <= SCTP_ADDR_SUBSET) {
			goto done;
		}

		/* no match; continue searching */
	}

done:
	if (sctp) {
		SCTP_REFHOLD(sctp);
	}
	return (sctp);
}

static void
trim_map_free_locked(trim_map_t *tm, uint64_t start, uint64_t end, uint64_t txg)
{
	zio_t zsearch, *zs;

	ASSERT(MUTEX_HELD(&tm->tm_lock));

	zsearch.io_offset = start;
	zsearch.io_size = end - start;

	zs = avl_find(&tm->tm_inflight_writes, &zsearch, NULL);
	if (zs == NULL) {
		trim_map_segment_add(tm, start, end, txg);
		return;
	}
	if (start < zs->io_offset)
		trim_map_free_locked(tm, start, zs->io_offset, txg);
	if (zs->io_offset + zs->io_size < end)
		trim_map_free_locked(tm, zs->io_offset + zs->io_size, end, txg);
}

/*
 * The port_remove_portfd() function dissociates the port from the fd
 * and vive versa.
 */
static void
port_remove_portfd(polldat_t *pdp, port_fdcache_t *pcp)
{
	port_t	*pp;
	file_t	*fp;

	ASSERT(MUTEX_HELD(&pcp->pc_lock));
	pp = pdp->pd_portev->portkev_port;
	fp = getf(pdp->pd_fd);
	/*
	 * If we did not get the fp for pd_fd but its portfd_t
	 * still exist in the cache, it means the pd_fd is being
	 * closed by some other thread which will also free the portfd_t.
	 */
	if (fp != NULL) {
		delfd_port(pdp->pd_fd, PDTOF(pdp));
		releasef(pdp->pd_fd);
		port_remove_fd_object(PDTOF(pdp), pp, pcp);
	}
}

static void
vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio)
{
	spa_t *spa = zio->io_spa;
	avl_tree_t *qtt;
	ASSERT(MUTEX_HELD(&vq->vq_lock));
	ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE);
	avl_add(vdev_queue_class_tree(vq, zio->io_priority), zio);
	qtt = vdev_queue_type_tree(vq, zio->io_type);
	if (qtt)
		avl_add(qtt, zio);

#ifdef illumos
	mutex_enter(&spa->spa_iokstat_lock);
	spa->spa_queue_stats[zio->io_priority].spa_queued++;
	if (spa->spa_iokstat != NULL)
		kstat_waitq_enter(spa->spa_iokstat->ks_data);
	mutex_exit(&spa->spa_iokstat_lock);
#endif
}