subscr.c

linux 内核源代码

	if (!found)
		return;

	/* Cancel subscription timer (if used), then delete subscription */

	if (sub->timeout != TIPC_WAIT_FOREVER) {
		sub->timeout = TIPC_WAIT_FOREVER;
		spin_unlock_bh(subscriber->lock);
		k_cancel_timer(&sub->timer);
		k_term_timer(&sub->timer);
		spin_lock_bh(subscriber->lock);
	}
	dbg("Cancel: removing sub %u,%u,%u from subscriber %x list\n",
	    sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
	subscr_del(sub);
}

/**
 * subscr_subscribe - create subscription for subscriber
 *
 * Called with subscriber locked
 */

static void subscr_subscribe(struct tipc_subscr *s,
			     struct subscriber *subscriber)
{
	struct subscription *sub;

	/* Determine/update subscriber's endianness */

	if (s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE))
		subscriber->swap = 0;
	else
		subscriber->swap = 1;

	/* Detect & process a subscription cancellation request */

	if (s->filter & htohl(TIPC_SUB_CANCEL, subscriber->swap)) {
		s->filter &= ~htohl(TIPC_SUB_CANCEL, subscriber->swap);
		subscr_cancel(s, subscriber);
		return;
	}

	/* Refuse subscription if global limit exceeded */

	if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
		warn("Subscription rejected, subscription limit reached (%u)\n",
		     tipc_max_subscriptions);
		subscr_terminate(subscriber);
		return;
	}

	/* Allocate subscription object */

	sub = kzalloc(sizeof(*sub), GFP_ATOMIC);
	if (!sub) {
		warn("Subscription rejected, no memory\n");
		subscr_terminate(subscriber);
		return;
	}

	/* Initialize subscription object */

	sub->seq.type = htohl(s->seq.type, subscriber->swap);
	sub->seq.lower = htohl(s->seq.lower, subscriber->swap);
	sub->seq.upper = htohl(s->seq.upper, subscriber->swap);
	sub->timeout = htohl(s->timeout, subscriber->swap);
	sub->filter = htohl(s->filter, subscriber->swap);
	if ((!(sub->filter & TIPC_SUB_PORTS)
	     == !(sub->filter & TIPC_SUB_SERVICE))
	    || (sub->seq.lower > sub->seq.upper)) {
		warn("Subscription rejected, illegal request\n");
		kfree(sub);
		subscr_terminate(subscriber);
		return;
	}
	memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
	INIT_LIST_HEAD(&sub->subscription_list);
	INIT_LIST_HEAD(&sub->nameseq_list);
	list_add(&sub->subscription_list, &subscriber->subscription_list);
	atomic_inc(&topsrv.subscription_count);
	if (sub->timeout != TIPC_WAIT_FOREVER) {
		k_init_timer(&sub->timer,
			     (Handler)subscr_timeout, (unsigned long)sub);
		k_start_timer(&sub->timer, sub->timeout);
	}
	sub->owner = subscriber;
	tipc_nametbl_subscribe(sub);
}

/**
 * subscr_conn_shutdown_event - handle termination request from subscriber
 */

static void subscr_conn_shutdown_event(void *usr_handle,
				       u32 portref,
				       struct sk_buff **buf,
				       unsigned char const *data,
				       unsigned int size,
				       int reason)
{
	struct subscriber *subscriber;
	spinlock_t *subscriber_lock;

	subscriber = tipc_ref_lock((u32)(unsigned long)usr_handle);
	if (subscriber == NULL)
		return;

	subscriber_lock = subscriber->lock;
	subscr_terminate(subscriber);
	spin_unlock_bh(subscriber_lock);
}

/**
 * subscr_conn_msg_event - handle new subscription request from subscriber
 */

static void subscr_conn_msg_event(void *usr_handle,
				  u32 port_ref,
				  struct sk_buff **buf,
				  const unchar *data,
				  u32 size)
{
	struct subscriber *subscriber;
	spinlock_t *subscriber_lock;

	subscriber = tipc_ref_lock((u32)(unsigned long)usr_handle);
	if (subscriber == NULL)
		return;

	subscriber_lock = subscriber->lock;
	if (size != sizeof(struct tipc_subscr))
		subscr_terminate(subscriber);
	else
		subscr_subscribe((struct tipc_subscr *)data, subscriber);

	spin_unlock_bh(subscriber_lock);
}

/**
 * subscr_named_msg_event - handle request to establish a new subscriber
 */

static void subscr_named_msg_event(void *usr_handle,
				   u32 port_ref,
				   struct sk_buff **buf,
				   const unchar *data,
				   u32 size,
				   u32 importance,
				   struct tipc_portid const *orig,
				   struct tipc_name_seq const *dest)
{
	struct subscriber *subscriber;
	struct iovec msg_sect = {NULL, 0};
	spinlock_t *subscriber_lock;

	dbg("subscr_named_msg_event: orig = %x own = %x,\n",
	    orig->node, tipc_own_addr);
	if (size && (size != sizeof(struct tipc_subscr))) {
		warn("Subscriber rejected, invalid subscription size\n");
		return;
	}

	/* Create subscriber object */

	subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
	if (subscriber == NULL) {
		warn("Subscriber rejected, no memory\n");
		return;
	}
	INIT_LIST_HEAD(&subscriber->subscription_list);
	INIT_LIST_HEAD(&subscriber->subscriber_list);
	subscriber->ref = tipc_ref_acquire(subscriber, &subscriber->lock);
	if (subscriber->ref == 0) {
		warn("Subscriber rejected, reference table exhausted\n");
		kfree(subscriber);
		return;
	}

	/* Establish a connection to subscriber */

	tipc_createport(topsrv.user_ref,
			(void *)(unsigned long)subscriber->ref,
			importance,
			NULL,
			NULL,
			subscr_conn_shutdown_event,
			NULL,
			NULL,
			subscr_conn_msg_event,
			NULL,
			&subscriber->port_ref);
	if (subscriber->port_ref == 0) {
		warn("Subscriber rejected, unable to create port\n");
		tipc_ref_discard(subscriber->ref);
		kfree(subscriber);
		return;
	}
	tipc_connect2port(subscriber->port_ref, orig);


	/* Add subscriber to topology server's subscriber list */

	tipc_ref_lock(subscriber->ref);
	spin_lock_bh(&topsrv.lock);
	list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
	spin_unlock_bh(&topsrv.lock);

	/*
	 * Subscribe now if message contains a subscription,
	 * otherwise send an empty response to complete connection handshaking
	 */

	subscriber_lock = subscriber->lock;
	if (size)
		subscr_subscribe((struct tipc_subscr *)data, subscriber);
	else
		tipc_send(subscriber->port_ref, 1, &msg_sect);

	spin_unlock_bh(subscriber_lock);
}

int tipc_subscr_start(void)
{
	struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
	int res = -1;

	memset(&topsrv, 0, sizeof (topsrv));
	spin_lock_init(&topsrv.lock);
	INIT_LIST_HEAD(&topsrv.subscriber_list);

	spin_lock_bh(&topsrv.lock);
	res = tipc_attach(&topsrv.user_ref, NULL, NULL);
	if (res) {
		spin_unlock_bh(&topsrv.lock);
		return res;
	}

	res = tipc_createport(topsrv.user_ref,
			      NULL,
			      TIPC_CRITICAL_IMPORTANCE,
			      NULL,
			      NULL,
			      NULL,
			      NULL,
			      subscr_named_msg_event,
			      NULL,
			      NULL,
			      &topsrv.setup_port);
	if (res)
		goto failed;

	res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
	if (res)
		goto failed;

	spin_unlock_bh(&topsrv.lock);
	return 0;

failed:
	err("Failed to create subscription service\n");
	tipc_detach(topsrv.user_ref);
	topsrv.user_ref = 0;
	spin_unlock_bh(&topsrv.lock);
	return res;
}

void tipc_subscr_stop(void)
{
	struct subscriber *subscriber;
	struct subscriber *subscriber_temp;
	spinlock_t *subscriber_lock;

	if (topsrv.user_ref) {
		tipc_deleteport(topsrv.setup_port);
		list_for_each_entry_safe(subscriber, subscriber_temp,
					 &topsrv.subscriber_list,
					 subscriber_list) {
			tipc_ref_lock(subscriber->ref);
			subscriber_lock = subscriber->lock;
			subscr_terminate(subscriber);
			spin_unlock_bh(subscriber_lock);
		}
		tipc_detach(topsrv.user_ref);
		topsrv.user_ref = 0;
	}
}


int tipc_ispublished(struct tipc_name const *name)
{
	u32 domain = 0;

	return(tipc_nametbl_translate(name->type, name->instance,&domain) != 0);
}