xpc_channel.c

linux-2.6.15.6

		return xpcSuccess;
	}

	dev_dbg(xpc_chan, "can't get memory for local message queue and notify "
		"queue, partid=%d, channel=%d\n", ch->partid, ch->number);
	return xpcNoMemory;
}


/*
 * Allocate the cached remote message queue.
 */
static enum xpc_retval
xpc_allocate_remote_msgqueue(struct xpc_channel *ch)
{
	unsigned long irq_flags;
	int nentries;
	size_t nbytes;


	DBUG_ON(ch->remote_nentries <= 0);

	// >>> may want to check for ch->flags & XPC_C_DISCONNECTING between
	// >>> iterations of the for-loop, bail if set?

	// >>> should we impose a minumum #of entries? like 4 or 8?
	for (nentries = ch->remote_nentries; nentries > 0; nentries--) {

		nbytes = nentries * ch->msg_size;
		ch->remote_msgqueue = xpc_kmalloc_cacheline_aligned(nbytes,
						(GFP_KERNEL | GFP_DMA),
						&ch->remote_msgqueue_base);
		if (ch->remote_msgqueue == NULL) {
			continue;
		}
		memset(ch->remote_msgqueue, 0, nbytes);

		spin_lock_irqsave(&ch->lock, irq_flags);
		if (nentries < ch->remote_nentries) {
			dev_dbg(xpc_chan, "nentries=%d remote_nentries=%d, "
				"partid=%d, channel=%d\n", nentries,
				ch->remote_nentries, ch->partid, ch->number);

			ch->remote_nentries = nentries;
		}
		spin_unlock_irqrestore(&ch->lock, irq_flags);
		return xpcSuccess;
	}

	dev_dbg(xpc_chan, "can't get memory for cached remote message queue, "
		"partid=%d, channel=%d\n", ch->partid, ch->number);
	return xpcNoMemory;
}


/*
 * Allocate message queues and other stuff associated with a channel.
 *
 * Note: Assumes all of the channel sizes are filled in.
 */
static enum xpc_retval
xpc_allocate_msgqueues(struct xpc_channel *ch)
{
	unsigned long irq_flags;
	int i;
	enum xpc_retval ret;


	DBUG_ON(ch->flags & XPC_C_SETUP);

	if ((ret = xpc_allocate_local_msgqueue(ch)) != xpcSuccess) {
		return ret;
	}

	if ((ret = xpc_allocate_remote_msgqueue(ch)) != xpcSuccess) {
		kfree(ch->local_msgqueue_base);
		ch->local_msgqueue = NULL;
		kfree(ch->notify_queue);
		ch->notify_queue = NULL;
		return ret;
	}

	for (i = 0; i < ch->local_nentries; i++) {
		/* use a semaphore as an event wait queue */
		sema_init(&ch->notify_queue[i].sema, 0);
	}

	spin_lock_irqsave(&ch->lock, irq_flags);
	ch->flags |= XPC_C_SETUP;
	spin_unlock_irqrestore(&ch->lock, irq_flags);

	return xpcSuccess;
}


/*
 * Process a connect message from a remote partition.
 *
 * Note: xpc_process_connect() is expecting to be called with the
 * spin_lock_irqsave held and will leave it locked upon return.
 */
static void
xpc_process_connect(struct xpc_channel *ch, unsigned long *irq_flags)
{
	enum xpc_retval ret;


	DBUG_ON(!spin_is_locked(&ch->lock));

	if (!(ch->flags & XPC_C_OPENREQUEST) ||
				!(ch->flags & XPC_C_ROPENREQUEST)) {
		/* nothing more to do for now */
		return;
	}
	DBUG_ON(!(ch->flags & XPC_C_CONNECTING));

	if (!(ch->flags & XPC_C_SETUP)) {
		spin_unlock_irqrestore(&ch->lock, *irq_flags);
		ret = xpc_allocate_msgqueues(ch);
		spin_lock_irqsave(&ch->lock, *irq_flags);

		if (ret != xpcSuccess) {
			XPC_DISCONNECT_CHANNEL(ch, ret, irq_flags);
		}
		if (ch->flags & (XPC_C_CONNECTED | XPC_C_DISCONNECTING)) {
			return;
		}

		DBUG_ON(!(ch->flags & XPC_C_SETUP));
		DBUG_ON(ch->local_msgqueue == NULL);
		DBUG_ON(ch->remote_msgqueue == NULL);
	}

	if (!(ch->flags & XPC_C_OPENREPLY)) {
		ch->flags |= XPC_C_OPENREPLY;
		xpc_IPI_send_openreply(ch, irq_flags);
	}

	if (!(ch->flags & XPC_C_ROPENREPLY)) {
		return;
	}

	DBUG_ON(ch->remote_msgqueue_pa == 0);

	ch->flags = (XPC_C_CONNECTED | XPC_C_SETUP);	/* clear all else */

	dev_info(xpc_chan, "channel %d to partition %d connected\n",
		ch->number, ch->partid);

	spin_unlock_irqrestore(&ch->lock, *irq_flags);
	xpc_create_kthreads(ch, 1);
	spin_lock_irqsave(&ch->lock, *irq_flags);
}


/*
 * Notify those who wanted to be notified upon delivery of their message.
 */
static void
xpc_notify_senders(struct xpc_channel *ch, enum xpc_retval reason, s64 put)
{
	struct xpc_notify *notify;
	u8 notify_type;
	s64 get = ch->w_remote_GP.get - 1;


	while (++get < put && atomic_read(&ch->n_to_notify) > 0) {

		notify = &ch->notify_queue[get % ch->local_nentries];

		/*
		 * See if the notify entry indicates it was associated with
		 * a message who's sender wants to be notified. It is possible
		 * that it is, but someone else is doing or has done the
		 * notification.
		 */
		notify_type = notify->type;
		if (notify_type == 0 ||
				cmpxchg(&notify->type, notify_type, 0) !=
								notify_type) {
			continue;
		}

		DBUG_ON(notify_type != XPC_N_CALL);

		atomic_dec(&ch->n_to_notify);

		if (notify->func != NULL) {
			dev_dbg(xpc_chan, "notify->func() called, notify=0x%p, "
				"msg_number=%ld, partid=%d, channel=%d\n",
				(void *) notify, get, ch->partid, ch->number);

			notify->func(reason, ch->partid, ch->number,
								notify->key);

			dev_dbg(xpc_chan, "notify->func() returned, "
				"notify=0x%p, msg_number=%ld, partid=%d, "
				"channel=%d\n", (void *) notify, get,
				ch->partid, ch->number);
		}
	}
}


/*
 * Free up message queues and other stuff that were allocated for the specified
 * channel.
 *
 * Note: ch->reason and ch->reason_line are left set for debugging purposes,
 * they're cleared when XPC_C_DISCONNECTED is cleared.
 */
static void
xpc_free_msgqueues(struct xpc_channel *ch)
{
	DBUG_ON(!spin_is_locked(&ch->lock));
	DBUG_ON(atomic_read(&ch->n_to_notify) != 0);

	ch->remote_msgqueue_pa = 0;
	ch->func = NULL;
	ch->key = NULL;
	ch->msg_size = 0;
	ch->local_nentries = 0;
	ch->remote_nentries = 0;
	ch->kthreads_assigned_limit = 0;
	ch->kthreads_idle_limit = 0;

	ch->local_GP->get = 0;
	ch->local_GP->put = 0;
	ch->remote_GP.get = 0;
	ch->remote_GP.put = 0;
	ch->w_local_GP.get = 0;
	ch->w_local_GP.put = 0;
	ch->w_remote_GP.get = 0;
	ch->w_remote_GP.put = 0;
	ch->next_msg_to_pull = 0;

	if (ch->flags & XPC_C_SETUP) {
		ch->flags &= ~XPC_C_SETUP;

		dev_dbg(xpc_chan, "ch->flags=0x%x, partid=%d, channel=%d\n",
			ch->flags, ch->partid, ch->number);

		kfree(ch->local_msgqueue_base);
		ch->local_msgqueue = NULL;
		kfree(ch->remote_msgqueue_base);
		ch->remote_msgqueue = NULL;
		kfree(ch->notify_queue);
		ch->notify_queue = NULL;
	}
}


/*
 * spin_lock_irqsave() is expected to be held on entry.
 */
static void
xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
{
	struct xpc_partition *part = &xpc_partitions[ch->partid];
	u32 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);


	DBUG_ON(!spin_is_locked(&ch->lock));

	if (!(ch->flags & XPC_C_DISCONNECTING)) {
		return;
	}

	DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));

	/* make sure all activity has settled down first */

	if (atomic_read(&ch->references) > 0) {
		return;
	}
	DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);

	if (part->act_state == XPC_P_DEACTIVATING) {
		/* can't proceed until the other side disengages from us */
		if (xpc_partition_engaged(1UL << ch->partid)) {
			return;
		}

	} else {

		/* as long as the other side is up do the full protocol */

		if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
			return;
		}

		if (!(ch->flags & XPC_C_CLOSEREPLY)) {
			ch->flags |= XPC_C_CLOSEREPLY;
			xpc_IPI_send_closereply(ch, irq_flags);
		}

		if (!(ch->flags & XPC_C_RCLOSEREPLY)) {
			return;
		}
	}

	/* wake those waiting for notify completion */
	if (atomic_read(&ch->n_to_notify) > 0) {
		/* >>> we do callout while holding ch->lock */
		xpc_notify_senders(ch, ch->reason, ch->w_local_GP.put);
	}

	/* both sides are disconnected now */

	/* it's now safe to free the channel's message queues */
	xpc_free_msgqueues(ch);

	/* mark disconnected, clear all other flags except XPC_C_WDISCONNECT */
	ch->flags = (XPC_C_DISCONNECTED | (ch->flags & XPC_C_WDISCONNECT));

	atomic_dec(&part->nchannels_active);

	if (channel_was_connected) {
		dev_info(xpc_chan, "channel %d to partition %d disconnected, "
			"reason=%d\n", ch->number, ch->partid, ch->reason);
	}

	if (ch->flags & XPC_C_WDISCONNECT) {
		spin_unlock_irqrestore(&ch->lock, *irq_flags);
		up(&ch->wdisconnect_sema);
		spin_lock_irqsave(&ch->lock, *irq_flags);

	} else if (ch->delayed_IPI_flags) {
		if (part->act_state != XPC_P_DEACTIVATING) {
			/* time to take action on any delayed IPI flags */
			spin_lock(&part->IPI_lock);
			XPC_SET_IPI_FLAGS(part->local_IPI_amo, ch->number,
							ch->delayed_IPI_flags);
			spin_unlock(&part->IPI_lock);
		}
		ch->delayed_IPI_flags = 0;
	}
}


/*
 * Process a change in the channel's remote connection state.
 */
static void
xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
				u8 IPI_flags)
{
	unsigned long irq_flags;
	struct xpc_openclose_args *args =
				&part->remote_openclose_args[ch_number];
	struct xpc_channel *ch = &part->channels[ch_number];
	enum xpc_retval reason;



	spin_lock_irqsave(&ch->lock, irq_flags);

again:

	if ((ch->flags & XPC_C_DISCONNECTED) &&
					(ch->flags & XPC_C_WDISCONNECT)) {
		/*
		 * Delay processing IPI flags until thread waiting disconnect
		 * has had a chance to see that the channel is disconnected.
		 */
		ch->delayed_IPI_flags |= IPI_flags;
		spin_unlock_irqrestore(&ch->lock, irq_flags);
		return;
	}


	if (IPI_flags & XPC_IPI_CLOSEREQUEST) {

		dev_dbg(xpc_chan, "XPC_IPI_CLOSEREQUEST (reason=%d) received "
			"from partid=%d, channel=%d\n", args->reason,
			ch->partid, ch->number);

		/*
		 * If RCLOSEREQUEST is set, we're probably waiting for
		 * RCLOSEREPLY. We should find it and a ROPENREQUEST packed
		 * with this RCLOSEREQUEST in the IPI_flags.
		 */

		if (ch->flags & XPC_C_RCLOSEREQUEST) {
			DBUG_ON(!(ch->flags & XPC_C_DISCONNECTING));
			DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
			DBUG_ON(!(ch->flags & XPC_C_CLOSEREPLY));
			DBUG_ON(ch->flags & XPC_C_RCLOSEREPLY);

			DBUG_ON(!(IPI_flags & XPC_IPI_CLOSEREPLY));
			IPI_flags &= ~XPC_IPI_CLOSEREPLY;
			ch->flags |= XPC_C_RCLOSEREPLY;

			/* both sides have finished disconnecting */
			xpc_process_disconnect(ch, &irq_flags);
			DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
			goto again;
		}

		if (ch->flags & XPC_C_DISCONNECTED) {
			if (!(IPI_flags & XPC_IPI_OPENREQUEST)) {
				if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo,
					 ch_number) & XPC_IPI_OPENREQUEST)) {

					DBUG_ON(ch->delayed_IPI_flags != 0);
					spin_lock(&part->IPI_lock);
					XPC_SET_IPI_FLAGS(part->local_IPI_amo,
							ch_number,
							XPC_IPI_CLOSEREQUEST);
					spin_unlock(&part->IPI_lock);
				}
				spin_unlock_irqrestore(&ch->lock, irq_flags);
				return;
			}

			XPC_SET_REASON(ch, 0, 0);
			ch->flags &= ~XPC_C_DISCONNECTED;

			atomic_inc(&part->nchannels_active);
			ch->flags |= (XPC_C_CONNECTING | XPC_C_ROPENREQUEST);
		}

		IPI_flags &= ~(XPC_IPI_OPENREQUEST | XPC_IPI_OPENREPLY);

		/*
		 * The meaningful CLOSEREQUEST connection state fields are:
		 *      reason = reason connection is to be closed
		 */

		ch->flags |= XPC_C_RCLOSEREQUEST;

		if (!(ch->flags & XPC_C_DISCONNECTING)) {
			reason = args->reason;
			if (reason <= xpcSuccess || reason > xpcUnknownReason) {
				reason = xpcUnknownReason;
			} else if (reason == xpcUnregistering) {
				reason = xpcOtherUnregistering;
			}

			XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);

			DBUG_ON(IPI_flags & XPC_IPI_CLOSEREPLY);
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}

		xpc_process_disconnect(ch, &irq_flags);
	}


	if (IPI_flags & XPC_IPI_CLOSEREPLY) {

		dev_dbg(xpc_chan, "XPC_IPI_CLOSEREPLY received from partid=%d,"
			" channel=%d\n", ch->partid, ch->number);

		if (ch->flags & XPC_C_DISCONNECTED) {
			DBUG_ON(part->act_state != XPC_P_DEACTIVATING);
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}

		DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));

		if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
			if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo, ch_number)
						& XPC_IPI_CLOSEREQUEST)) {

				DBUG_ON(ch->delayed_IPI_flags != 0);
				spin_lock(&part->IPI_lock);
				XPC_SET_IPI_FLAGS(part->local_IPI_amo,
						ch_number, XPC_IPI_CLOSEREPLY);
				spin_unlock(&part->IPI_lock);