irttp.c

linux 内核源代码

	/* First make sure we're connected. */
	IRDA_ASSERT(self != NULL, return;);
	IRDA_ASSERT(self->magic == TTP_TSAP_MAGIC, return;);

	irttp_flush_queues(self);

	del_timer(&self->todo_timer);

	/* This one won't be cleaned up if we are disconnect_pend + close_pend
	 * and we receive a disconnect_indication */
	if (self->disconnect_skb)
		dev_kfree_skb(self->disconnect_skb);

	self->connected = FALSE;
	self->magic = ~TTP_TSAP_MAGIC;

	kfree(self);
}

/*
 * Function irttp_close (self)
 *
 *    Remove TSAP from list of all TSAPs and then deallocate all resources
 *    associated with this TSAP
 *
 * Note : because we *free* the tsap structure, it is the responsibility
 * of the caller to make sure we are called only once and to deal with
 * possible race conditions. - Jean II
 */
int irttp_close_tsap(struct tsap_cb *self)
{
	struct tsap_cb *tsap;

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

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

	/* Make sure tsap has been disconnected */
	if (self->connected) {
		/* Check if disconnect is not pending */
		if (!test_bit(0, &self->disconnect_pend)) {
			IRDA_WARNING("%s: TSAP still connected!\n",
				     __FUNCTION__);
			irttp_disconnect_request(self, NULL, P_NORMAL);
		}
		self->close_pend = TRUE;
		irttp_start_todo_timer(self, HZ/10);

		return 0; /* Will be back! */
	}

	tsap = hashbin_remove(irttp->tsaps, (long) self, NULL);

	IRDA_ASSERT(tsap == self, return -1;);

	/* Close corresponding LSAP */
	if (self->lsap) {
		irlmp_close_lsap(self->lsap);
		self->lsap = NULL;
	}

	__irttp_close_tsap(self);

	return 0;
}
EXPORT_SYMBOL(irttp_close_tsap);

/*
 * Function irttp_udata_request (self, skb)
 *
 *    Send unreliable data on this TSAP
 *
 */
int irttp_udata_request(struct tsap_cb *self, struct sk_buff *skb)
{
	IRDA_ASSERT(self != NULL, return -1;);
	IRDA_ASSERT(self->magic == TTP_TSAP_MAGIC, return -1;);
	IRDA_ASSERT(skb != NULL, return -1;);

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

	/* Check that nothing bad happens */
	if ((skb->len == 0) || (!self->connected)) {
		IRDA_DEBUG(1, "%s(), No data, or not connected\n",
			   __FUNCTION__);
		goto err;
	}

	if (skb->len > self->max_seg_size) {
		IRDA_DEBUG(1, "%s(), UData is too large for IrLAP!\n",
			   __FUNCTION__);
		goto err;
	}

	irlmp_udata_request(self->lsap, skb);
	self->stats.tx_packets++;

	return 0;

err:
	dev_kfree_skb(skb);
	return -1;
}
EXPORT_SYMBOL(irttp_udata_request);


/*
 * Function irttp_data_request (handle, skb)
 *
 *    Queue frame for transmission. If SAR is enabled, fragement the frame
 *    and queue the fragments for transmission
 */
int irttp_data_request(struct tsap_cb *self, struct sk_buff *skb)
{
	__u8 *frame;
	int ret;

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

	IRDA_DEBUG(2, "%s() : queue len = %d\n", __FUNCTION__,
		   skb_queue_len(&self->tx_queue));

	/* Check that nothing bad happens */
	if ((skb->len == 0) || (!self->connected)) {
		IRDA_WARNING("%s: No data, or not connected\n", __FUNCTION__);
		ret = -ENOTCONN;
		goto err;
	}

	/*
	 *  Check if SAR is disabled, and the frame is larger than what fits
	 *  inside an IrLAP frame
	 */
	if ((self->tx_max_sdu_size == 0) && (skb->len > self->max_seg_size)) {
		IRDA_ERROR("%s: SAR disabled, and data is too large for IrLAP!\n",
			   __FUNCTION__);
		ret = -EMSGSIZE;
		goto err;
	}

	/*
	 *  Check if SAR is enabled, and the frame is larger than the
	 *  TxMaxSduSize
	 */
	if ((self->tx_max_sdu_size != 0) &&
	    (self->tx_max_sdu_size != TTP_SAR_UNBOUND) &&
	    (skb->len > self->tx_max_sdu_size))
	{
		IRDA_ERROR("%s: SAR enabled, but data is larger than TxMaxSduSize!\n",
			   __FUNCTION__);
		ret = -EMSGSIZE;
		goto err;
	}
	/*
	 *  Check if transmit queue is full
	 */
	if (skb_queue_len(&self->tx_queue) >= TTP_TX_MAX_QUEUE) {
		/*
		 *  Give it a chance to empty itself
		 */
		irttp_run_tx_queue(self);

		/* Drop packet. This error code should trigger the caller
		 * to resend the data in the client code - Jean II */
		ret = -ENOBUFS;
		goto err;
	}

	/* Queue frame, or queue frame segments */
	if ((self->tx_max_sdu_size == 0) || (skb->len < self->max_seg_size)) {
		/* Queue frame */
		IRDA_ASSERT(skb_headroom(skb) >= TTP_HEADER, return -1;);
		frame = skb_push(skb, TTP_HEADER);
		frame[0] = 0x00; /* Clear more bit */

		skb_queue_tail(&self->tx_queue, skb);
	} else {
		/*
		 *  Fragment the frame, this function will also queue the
		 *  fragments, we don't care about the fact the transmit
		 *  queue may be overfilled by all the segments for a little
		 *  while
		 */
		irttp_fragment_skb(self, skb);
	}

	/* Check if we can accept more data from client */
	if ((!self->tx_sdu_busy) &&
	    (skb_queue_len(&self->tx_queue) > TTP_TX_HIGH_THRESHOLD)) {
		/* Tx queue filling up, so stop client. */
		if (self->notify.flow_indication) {
			self->notify.flow_indication(self->notify.instance,
						     self, FLOW_STOP);
		}
		/* self->tx_sdu_busy is the state of the client.
		 * Update state after notifying client to avoid
		 * race condition with irttp_flow_indication().
		 * If the queue empty itself after our test but before
		 * we set the flag, we will fix ourselves below in
		 * irttp_run_tx_queue().
		 * Jean II */
		self->tx_sdu_busy = TRUE;
	}

	/* Try to make some progress */
	irttp_run_tx_queue(self);

	return 0;

err:
	dev_kfree_skb(skb);
	return ret;
}
EXPORT_SYMBOL(irttp_data_request);

/*
 * Function irttp_run_tx_queue (self)
 *
 *    Transmit packets queued for transmission (if possible)
 *
 */
static void irttp_run_tx_queue(struct tsap_cb *self)
{
	struct sk_buff *skb;
	unsigned long flags;
	int n;

	IRDA_DEBUG(2, "%s() : send_credit = %d, queue_len = %d\n",
		   __FUNCTION__,
		   self->send_credit, skb_queue_len(&self->tx_queue));

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

	/* Try to send out frames as long as we have credits
	 * and as long as LAP is not full. If LAP is full, it will
	 * poll us through irttp_flow_indication() - Jean II */
	while ((self->send_credit > 0) &&
	       (!irlmp_lap_tx_queue_full(self->lsap)) &&
	       (skb = skb_dequeue(&self->tx_queue)))
	{
		/*
		 *  Since we can transmit and receive frames concurrently,
		 *  the code below is a critical region and we must assure that
		 *  nobody messes with the credits while we update them.
		 */
		spin_lock_irqsave(&self->lock, flags);

		n = self->avail_credit;
		self->avail_credit = 0;

		/* Only room for 127 credits in frame */
		if (n > 127) {
			self->avail_credit = n-127;
			n = 127;
		}
		self->remote_credit += n;
		self->send_credit--;

		spin_unlock_irqrestore(&self->lock, flags);

		/*
		 *  More bit must be set by the data_request() or fragment()
		 *  functions
		 */
		skb->data[0] |= (n & 0x7f);

		/* Detach from socket.
		 * The current skb has a reference to the socket that sent
		 * it (skb->sk). When we pass it to IrLMP, the skb will be
		 * stored in in IrLAP (self->wx_list). When we are within
		 * IrLAP, we lose the notion of socket, so we should not
		 * have a reference to a socket. So, we drop it here.
		 *
		 * Why does it matter ?
		 * When the skb is freed (kfree_skb), if it is associated
		 * with a socket, it release buffer space on the socket
		 * (through sock_wfree() and sock_def_write_space()).
		 * If the socket no longer exist, we may crash. Hard.
		 * When we close a socket, we make sure that associated packets
		 * in IrTTP are freed. However, we have no way to cancel
		 * the packet that we have passed to IrLAP. So, if a packet
		 * remains in IrLAP (retry on the link or else) after we
		 * close the socket, we are dead !
		 * Jean II */
		if (skb->sk != NULL) {
			/* IrSOCK application, IrOBEX, ... */
			skb_orphan(skb);
		}
			/* IrCOMM over IrTTP, IrLAN, ... */

		/* Pass the skb to IrLMP - done */
		irlmp_data_request(self->lsap, skb);
		self->stats.tx_packets++;
	}

	/* Check if we can accept more frames from client.
	 * We don't want to wait until the todo timer to do that, and we
	 * can't use tasklets (grr...), so we are obliged to give control
	 * to client. That's ok, this test will be true not too often
	 * (max once per LAP window) and we are called from places
	 * where we can spend a bit of time doing stuff. - Jean II */
	if ((self->tx_sdu_busy) &&
	    (skb_queue_len(&self->tx_queue) < TTP_TX_LOW_THRESHOLD) &&
	    (!self->close_pend))
	{
		if (self->notify.flow_indication)
			self->notify.flow_indication(self->notify.instance,
						     self, FLOW_START);

		/* self->tx_sdu_busy is the state of the client.
		 * We don't really have a race here, but it's always safer
		 * to update our state after the client - Jean II */
		self->tx_sdu_busy = FALSE;
	}

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

/*
 * Function irttp_give_credit (self)
 *
 *    Send a dataless flowdata TTP-PDU and give available credit to peer
 *    TSAP
 */
static inline void irttp_give_credit(struct tsap_cb *self)
{
	struct sk_buff *tx_skb = NULL;
	unsigned long flags;
	int n;

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

	IRDA_DEBUG(4, "%s() send=%d,avail=%d,remote=%d\n",
		   __FUNCTION__,
		   self->send_credit, self->avail_credit, self->remote_credit);

	/* Give credit to peer */
	tx_skb = alloc_skb(TTP_MAX_HEADER, GFP_ATOMIC);
	if (!tx_skb)
		return;

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

	/*
	 *  Since we can transmit and receive frames concurrently,
	 *  the code below is a critical region and we must assure that
	 *  nobody messes with the credits while we update them.
	 */
	spin_lock_irqsave(&self->lock, flags);

	n = self->avail_credit;
	self->avail_credit = 0;

	/* Only space for 127 credits in frame */
	if (n > 127) {
		self->avail_credit = n - 127;
		n = 127;
	}
	self->remote_credit += n;

	spin_unlock_irqrestore(&self->lock, flags);

	skb_put(tx_skb, 1);
	tx_skb->data[0] = (__u8) (n & 0x7f);

	irlmp_data_request(self->lsap, tx_skb);
	self->stats.tx_packets++;
}

/*
 * Function irttp_udata_indication (instance, sap, skb)
 *
 *    Received some unit-data (unreliable)
 *
 */
static int irttp_udata_indication(void *instance, void *sap,
				  struct sk_buff *skb)
{
	struct tsap_cb *self;
	int err;

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

	self = (struct tsap_cb *) instance;

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

	self->stats.rx_packets++;

	/* Just pass data to layer above */
	if (self->notify.udata_indication) {
		err = self->notify.udata_indication(self->notify.instance,
						    self,skb);
		/* Same comment as in irttp_do_data_indication() */
		if (!err)
			return 0;
	}
	/* Either no handler, or handler returns an error */
	dev_kfree_skb(skb);

	return 0;
}

/*
 * Function irttp_data_indication (instance, sap, skb)
 *
 *    Receive segment from IrLMP.
 *
 */
static int irttp_data_indication(void *instance, void *sap,
				 struct sk_buff *skb)
{
	struct tsap_cb *self;
	unsigned long flags;
	int n;

	self = (struct tsap_cb *) instance;

	n = skb->data[0] & 0x7f;     /* Extract the credits */

	self->stats.rx_packets++;

	/*  Deal with inbound credit
	 *  Since we can transmit and receive frames concurrently,
	 *  the code below is a critical region and we must assure that
	 *  nobody messes with the credits while we update them.
	 */
	spin_lock_irqsave(&self->lock, flags);
	self->send_credit += n;
	if (skb->len > 1)
		self->remote_credit--;
	spin_unlock_irqrestore(&self->lock, flags);

	/*
	 *  Data or dataless packet? Dataless frames contains only the
	 *  TTP_HEADER.
	 */
	if (skb->len > 1) {
		/*
		 *  We don't remove the TTP header, since we must preserve the
		 *  more bit, so the defragment routing knows what to do
		 */
		skb_queue_tail(&self->rx_queue, skb);
	} else {
		/* Dataless flowdata TTP-PDU */
		dev_kfree_skb(skb);
	}


	/* Push data to the higher layer.
	 * We do it synchronously because running the todo timer for each
	 * receive packet would be too much overhead and latency.
	 * By passing control to the higher layer, we run the risk that
	 * it may take time or grab a lock. Most often, the higher layer
	 * will only put packet in a queue.
	 * Anyway, packets are only dripping through the IrDA, so we can
	 * have time before the next packet.
	 * Further, we are run from NET_BH, so the worse that can happen is
	 * us missing the optimal time to send back the PF bit in LAP.
	 * Jean II */
	irttp_run_rx_queue(self);

	/* We now give credits to peer in irttp_run_rx_queue().
	 * We need to send credit *NOW*, otherwise we are going
	 * to miss the next Tx window. The todo timer may take