irttp.c

linux 内核源代码

 *
 *    Duplicate TSAP, can be used by servers to confirm a connection on a
 *    new TSAP so it can keep listening on the old one.
 */
struct tsap_cb *irttp_dup(struct tsap_cb *orig, void *instance)
{
	struct tsap_cb *new;
	unsigned long flags;

	IRDA_DEBUG(1, "%s()\n", __FUNCTION__);

	/* Protect our access to the old tsap instance */
	spin_lock_irqsave(&irttp->tsaps->hb_spinlock, flags);

	/* Find the old instance */
	if (!hashbin_find(irttp->tsaps, (long) orig, NULL)) {
		IRDA_DEBUG(0, "%s(), unable to find TSAP\n", __FUNCTION__);
		spin_unlock_irqrestore(&irttp->tsaps->hb_spinlock, flags);
		return NULL;
	}

	/* Allocate a new instance */
	new = kmalloc(sizeof(struct tsap_cb), GFP_ATOMIC);
	if (!new) {
		IRDA_DEBUG(0, "%s(), unable to kmalloc\n", __FUNCTION__);
		spin_unlock_irqrestore(&irttp->tsaps->hb_spinlock, flags);
		return NULL;
	}
	/* Dup */
	memcpy(new, orig, sizeof(struct tsap_cb));

	/* We don't need the old instance any more */
	spin_unlock_irqrestore(&irttp->tsaps->hb_spinlock, flags);

	/* Try to dup the LSAP (may fail if we were too slow) */
	new->lsap = irlmp_dup(orig->lsap, new);
	if (!new->lsap) {
		IRDA_DEBUG(0, "%s(), dup failed!\n", __FUNCTION__);
		kfree(new);
		return NULL;
	}

	/* Not everything should be copied */
	new->notify.instance = instance;

	/* Initialize internal objects */
	irttp_init_tsap(new);

	/* This is locked */
	hashbin_insert(irttp->tsaps, (irda_queue_t *) new, (long) new, NULL);

	return new;
}
EXPORT_SYMBOL(irttp_dup);

/*
 * Function irttp_disconnect_request (self)
 *
 *    Close this connection please! If priority is high, the queued data
 *    segments, if any, will be deallocated first
 *
 */
int irttp_disconnect_request(struct tsap_cb *self, struct sk_buff *userdata,
			     int priority)
{
	int ret;

	IRDA_ASSERT(self != NULL, return -1;);
	IRDA_ASSERT(self->magic == TTP_TSAP_MAGIC, return -1;);

	/* Already disconnected? */
	if (!self->connected) {
		IRDA_DEBUG(4, "%s(), already disconnected!\n", __FUNCTION__);
		if (userdata)
			dev_kfree_skb(userdata);
		return -1;
	}

	/* Disconnect already pending ?
	 * We need to use an atomic operation to prevent reentry. This
	 * function may be called from various context, like user, timer
	 * for following a disconnect_indication() (i.e. net_bh).
	 * Jean II */
	if(test_and_set_bit(0, &self->disconnect_pend)) {
		IRDA_DEBUG(0, "%s(), disconnect already pending\n",
			   __FUNCTION__);
		if (userdata)
			dev_kfree_skb(userdata);

		/* Try to make some progress */
		irttp_run_tx_queue(self);
		return -1;
	}

	/*
	 *  Check if there is still data segments in the transmit queue
	 */
	if (!skb_queue_empty(&self->tx_queue)) {
		if (priority == P_HIGH) {
			/*
			 *  No need to send the queued data, if we are
			 *  disconnecting right now since the data will
			 *  not have any usable connection to be sent on
			 */
			IRDA_DEBUG(1, "%s(): High priority!!()\n", __FUNCTION__);
			irttp_flush_queues(self);
		} else if (priority == P_NORMAL) {
			/*
			 *  Must delay disconnect until after all data segments
			 *  have been sent and the tx_queue is empty
			 */
			/* We'll reuse this one later for the disconnect */
			self->disconnect_skb = userdata;  /* May be NULL */

			irttp_run_tx_queue(self);

			irttp_start_todo_timer(self, HZ/10);
			return -1;
		}
	}
	/* Note : we don't need to check if self->rx_queue is full and the
	 * state of self->rx_sdu_busy because the disconnect response will
	 * be sent at the LMP level (so even if the peer has its Tx queue
	 * full of data). - Jean II */

	IRDA_DEBUG(1, "%s(), Disconnecting ...\n", __FUNCTION__);
	self->connected = FALSE;

	if (!userdata) {
		struct sk_buff *tx_skb;
		tx_skb = alloc_skb(LMP_MAX_HEADER, GFP_ATOMIC);
		if (!tx_skb)
			return -ENOMEM;

		/*
		 *  Reserve space for MUX and LAP header
		 */
		skb_reserve(tx_skb, LMP_MAX_HEADER);

		userdata = tx_skb;
	}
	ret = irlmp_disconnect_request(self->lsap, userdata);

	/* The disconnect is no longer pending */
	clear_bit(0, &self->disconnect_pend);	/* FALSE */

	return ret;
}
EXPORT_SYMBOL(irttp_disconnect_request);

/*
 * Function irttp_disconnect_indication (self, reason)
 *
 *    Disconnect indication, TSAP disconnected by peer?
 *
 */
void irttp_disconnect_indication(void *instance, void *sap, LM_REASON reason,
				 struct sk_buff *skb)
{
	struct tsap_cb *self;

	IRDA_DEBUG(4, "%s()\n", __FUNCTION__);

	self = (struct tsap_cb *) instance;

	IRDA_ASSERT(self != NULL, return;);
	IRDA_ASSERT(self->magic == TTP_TSAP_MAGIC, return;);

	/* Prevent higher layer to send more data */
	self->connected = FALSE;

	/* Check if client has already tried to close the TSAP */
	if (self->close_pend) {
		/* In this case, the higher layer is probably gone. Don't
		 * bother it and clean up the remains - Jean II */
		if (skb)
			dev_kfree_skb(skb);
		irttp_close_tsap(self);
		return;
	}

	/* If we are here, we assume that is the higher layer is still
	 * waiting for the disconnect notification and able to process it,
	 * even if he tried to disconnect. Otherwise, it would have already
	 * attempted to close the tsap and self->close_pend would be TRUE.
	 * Jean II */

	/* No need to notify the client if has already tried to disconnect */
	if(self->notify.disconnect_indication)
		self->notify.disconnect_indication(self->notify.instance, self,
						   reason, skb);
	else
		if (skb)
			dev_kfree_skb(skb);
}

/*
 * Function irttp_do_data_indication (self, skb)
 *
 *    Try to deliver reassembled skb to layer above, and requeue it if that
 *    for some reason should fail. We mark rx sdu as busy to apply back
 *    pressure is necessary.
 */
static void irttp_do_data_indication(struct tsap_cb *self, struct sk_buff *skb)
{
	int err;

	/* Check if client has already closed the TSAP and gone away */
	if (self->close_pend) {
		dev_kfree_skb(skb);
		return;
	}

	err = self->notify.data_indication(self->notify.instance, self, skb);

	/* Usually the layer above will notify that it's input queue is
	 * starting to get filled by using the flow request, but this may
	 * be difficult, so it can instead just refuse to eat it and just
	 * give an error back
	 */
	if (err) {
		IRDA_DEBUG(0, "%s() requeueing skb!\n", __FUNCTION__);

		/* Make sure we take a break */
		self->rx_sdu_busy = TRUE;

		/* Need to push the header in again */
		skb_push(skb, TTP_HEADER);
		skb->data[0] = 0x00; /* Make sure MORE bit is cleared */

		/* Put skb back on queue */
		skb_queue_head(&self->rx_queue, skb);
	}
}

/*
 * Function irttp_run_rx_queue (self)
 *
 *     Check if we have any frames to be transmitted, or if we have any
 *     available credit to give away.
 */
void irttp_run_rx_queue(struct tsap_cb *self)
{
	struct sk_buff *skb;
	int more = 0;

	IRDA_DEBUG(2, "%s() send=%d,avail=%d,remote=%d\n", __FUNCTION__,
		   self->send_credit, self->avail_credit, self->remote_credit);

	/* Get exclusive access to the rx queue, otherwise don't touch it */
	if (irda_lock(&self->rx_queue_lock) == FALSE)
		return;

	/*
	 *  Reassemble all frames in receive queue and deliver them
	 */
	while (!self->rx_sdu_busy && (skb = skb_dequeue(&self->rx_queue))) {
		/* This bit will tell us if it's the last fragment or not */
		more = skb->data[0] & 0x80;

		/* Remove TTP header */
		skb_pull(skb, TTP_HEADER);

		/* Add the length of the remaining data */
		self->rx_sdu_size += skb->len;

		/*
		 * If SAR is disabled, or user has requested no reassembly
		 * of received fragments then we just deliver them
		 * immediately. This can be requested by clients that
		 * implements byte streams without any message boundaries
		 */
		if (self->rx_max_sdu_size == TTP_SAR_DISABLE) {
			irttp_do_data_indication(self, skb);
			self->rx_sdu_size = 0;

			continue;
		}

		/* Check if this is a fragment, and not the last fragment */
		if (more) {
			/*
			 *  Queue the fragment if we still are within the
			 *  limits of the maximum size of the rx_sdu
			 */
			if (self->rx_sdu_size <= self->rx_max_sdu_size) {
				IRDA_DEBUG(4, "%s(), queueing frag\n",
					   __FUNCTION__);
				skb_queue_tail(&self->rx_fragments, skb);
			} else {
				/* Free the part of the SDU that is too big */
				dev_kfree_skb(skb);
			}
			continue;
		}
		/*
		 *  This is the last fragment, so time to reassemble!
		 */
		if ((self->rx_sdu_size <= self->rx_max_sdu_size) ||
		    (self->rx_max_sdu_size == TTP_SAR_UNBOUND))
		{
			/*
			 * A little optimizing. Only queue the fragment if
			 * there are other fragments. Since if this is the
			 * last and only fragment, there is no need to
			 * reassemble :-)
			 */
			if (!skb_queue_empty(&self->rx_fragments)) {
				skb_queue_tail(&self->rx_fragments,
					       skb);

				skb = irttp_reassemble_skb(self);
			}

			/* Now we can deliver the reassembled skb */
			irttp_do_data_indication(self, skb);
		} else {
			IRDA_DEBUG(1, "%s(), Truncated frame\n", __FUNCTION__);

			/* Free the part of the SDU that is too big */
			dev_kfree_skb(skb);

			/* Deliver only the valid but truncated part of SDU */
			skb = irttp_reassemble_skb(self);

			irttp_do_data_indication(self, skb);
		}
		self->rx_sdu_size = 0;
	}

	/*
	 * It's not trivial to keep track of how many credits are available
	 * by incrementing at each packet, because delivery may fail
	 * (irttp_do_data_indication() may requeue the frame) and because
	 * we need to take care of fragmentation.
	 * We want the other side to send up to initial_credit packets.
	 * We have some frames in our queues, and we have already allowed it
	 * to send remote_credit.
	 * No need to spinlock, write is atomic and self correcting...
	 * Jean II
	 */
	self->avail_credit = (self->initial_credit -
			      (self->remote_credit +
			       skb_queue_len(&self->rx_queue) +
			       skb_queue_len(&self->rx_fragments)));

	/* Do we have too much credits to send to peer ? */
	if ((self->remote_credit <= TTP_RX_MIN_CREDIT) &&
	    (self->avail_credit > 0)) {
		/* Send explicit credit frame */
		irttp_give_credit(self);
		/* Note : do *NOT* check if tx_queue is non-empty, that
		 * will produce deadlocks. I repeat : send a credit frame
		 * even if we have something to send in our Tx queue.
		 * If we have credits, it means that our Tx queue is blocked.
		 *
		 * Let's suppose the peer can't keep up with our Tx. He will
		 * flow control us by not sending us any credits, and we
		 * will stop Tx and start accumulating credits here.
		 * Up to the point where the peer will stop its Tx queue,
		 * for lack of credits.
		 * Let's assume the peer application is single threaded.
		 * It will block on Tx and never consume any Rx buffer.
		 * Deadlock. Guaranteed. - Jean II
		 */
	}

	/* Reset lock */
	self->rx_queue_lock = 0;
}

#ifdef CONFIG_PROC_FS
struct irttp_iter_state {
	int id;
};

static void *irttp_seq_start(struct seq_file *seq, loff_t *pos)
{
	struct irttp_iter_state *iter = seq->private;
	struct tsap_cb *self;

	/* Protect our access to the tsap list */
	spin_lock_irq(&irttp->tsaps->hb_spinlock);
	iter->id = 0;

	for (self = (struct tsap_cb *) hashbin_get_first(irttp->tsaps);
	     self != NULL;
	     self = (struct tsap_cb *) hashbin_get_next(irttp->tsaps)) {
		if (iter->id == *pos)
			break;
		++iter->id;
	}

	return self;
}

static void *irttp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct irttp_iter_state *iter = seq->private;

	++*pos;
	++iter->id;
	return (void *) hashbin_get_next(irttp->tsaps);
}

static void irttp_seq_stop(struct seq_file *seq, void *v)
{
	spin_unlock_irq(&irttp->tsaps->hb_spinlock);
}

static int irttp_seq_show(struct seq_file *seq, void *v)
{
	const struct irttp_iter_state *iter = seq->private;
	const struct tsap_cb *self = v;

	seq_printf(seq, "TSAP %d, ", iter->id);
	seq_printf(seq, "stsap_sel: %02x, ",
		   self->stsap_sel);
	seq_printf(seq, "dtsap_sel: %02x\n",
		   self->dtsap_sel);
	seq_printf(seq, "  connected: %s, ",
		   self->connected? "TRUE":"FALSE");
	seq_printf(seq, "avail credit: %d, ",
		   self->avail_credit);
	seq_printf(seq, "remote credit: %d, ",
		   self->remote_credit);
	seq_printf(seq, "send credit: %d\n",
		   self->send_credit);
	seq_printf(seq, "  tx packets: %ld, ",
		   self->stats.tx_packets);
	seq_printf(seq, "rx packets: %ld, ",
		   self->stats.rx_packets);
	seq_printf(seq, "tx_queue len: %d ",
		   skb_queue_len(&self->tx_queue));
	seq_printf(seq, "rx_queue len: %d\n",
		   skb_queue_len(&self->rx_queue));
	seq_printf(seq, "  tx_sdu_busy: %s, ",
		   self->tx_sdu_busy? "TRUE":"FALSE");
	seq_printf(seq, "rx_sdu_busy: %s\n",
		   self->rx_sdu_busy? "TRUE":"FALSE");
	seq_printf(seq, "  max_seg_size: %d, ",
		   self->max_seg_size);
	seq_printf(seq, "tx_max_sdu_size: %d, ",
		   self->tx_max_sdu_size);
	seq_printf(seq, "rx_max_sdu_size: %d\n",
		   self->rx_max_sdu_size);

	seq_printf(seq, "  Used by (%s)\n\n",
		   self->notify.name);
	return 0;
}

static const struct seq_operations irttp_seq_ops = {
	.start  = irttp_seq_start,
	.next   = irttp_seq_next,
	.stop   = irttp_seq_stop,
	.show   = irttp_seq_show,
};

static int irttp_seq_open(struct inode *inode, struct file *file)
{
	return seq_open_private(file, &irttp_seq_ops,
			sizeof(struct irttp_iter_state));
}

const struct file_operations irttp_seq_fops = {
	.owner		= THIS_MODULE,
	.open           = irttp_seq_open,
	.read           = seq_read,
	.llseek         = seq_lseek,
	.release	= seq_release_private,
};

#endif /* PROC_FS */