RT-AC66 3.0.0.4.374.130 core

[tomato.git] / release / src-rt-6.x / linux / linux-2.6 / net / irda / irttp.c

/*********************************************************************
 *
 * Filename:      irttp.c
 * Version:       1.2
 * Description:   Tiny Transport Protocol (TTP) implementation
 * Status:        Stable
 * Author:        Dag Brattli <dagb@cs.uit.no>
 * Created at:    Sun Aug 31 20:14:31 1997
 * Modified at:   Wed Jan  5 11:31:27 2000
 * Modified by:   Dag Brattli <dagb@cs.uit.no>
 *
 *     Copyright (c) 1998-2000 Dag Brattli <dagb@cs.uit.no>,
 *     All Rights Reserved.
 *     Copyright (c) 2000-2003 Jean Tourrilhes <jt@hpl.hp.com>
 *
 *     This program is free software; you can redistribute it and/or
 *     modify it under the terms of the GNU General Public License as
 *     published by the Free Software Foundation; either version 2 of
 *     the License, or (at your option) any later version.
 *
 *     Neither Dag Brattli nor University of Tromsø admit liability nor
 *     provide warranty for any of this software. This material is
 *     provided "AS-IS" and at no charge.
 *
 ********************************************************************/

#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/seq_file.h>

#include <asm/byteorder.h>
#include <asm/unaligned.h>

#include <net/irda/irda.h>
#include <net/irda/irlap.h>
#include <net/irda/irlmp.h>
#include <net/irda/parameters.h>
#include <net/irda/irttp.h>

static struct irttp_cb *irttp;

static void __irttp_close_tsap(struct tsap_cb *self);

static int irttp_data_indication(void *instance, void *sap,
                                 struct sk_buff *skb);
static int irttp_udata_indication(void *instance, void *sap,
                                  struct sk_buff *skb);
static void irttp_disconnect_indication(void *instance, void *sap,
                                        LM_REASON reason, struct sk_buff *);
static void irttp_connect_indication(void *instance, void *sap,
                                     struct qos_info *qos, __u32 max_sdu_size,
                                     __u8 header_size, struct sk_buff *skb);
static void irttp_connect_confirm(void *instance, void *sap,
                                  struct qos_info *qos, __u32 max_sdu_size,
                                  __u8 header_size, struct sk_buff *skb);
static void irttp_run_tx_queue(struct tsap_cb *self);
static void irttp_run_rx_queue(struct tsap_cb *self);

static void irttp_flush_queues(struct tsap_cb *self);
static void irttp_fragment_skb(struct tsap_cb *self, struct sk_buff *skb);
static struct sk_buff *irttp_reassemble_skb(struct tsap_cb *self);
static void irttp_todo_expired(unsigned long data);
static int irttp_param_max_sdu_size(void *instance, irda_param_t *param,
                                    int get);

static void irttp_flow_indication(void *instance, void *sap, LOCAL_FLOW flow);
static void irttp_status_indication(void *instance,
                                    LINK_STATUS link, LOCK_STATUS lock);

/* Information for parsing parameters in IrTTP */
static pi_minor_info_t pi_minor_call_table[] = {
        { NULL, 0 },                                             /* 0x00 */
        { irttp_param_max_sdu_size, PV_INTEGER | PV_BIG_ENDIAN } /* 0x01 */
};
static pi_major_info_t pi_major_call_table[] = {{ pi_minor_call_table, 2 }};
static pi_param_info_t param_info = { pi_major_call_table, 1, 0x0f, 4 };

/************************ GLOBAL PROCEDURES ************************/

/*
 * Function irttp_init (void)
 *
 *    Initialize the IrTTP layer. Called by module initialization code
 *
 */
int __init irttp_init(void)
{
        irttp = kzalloc(sizeof(struct irttp_cb), GFP_KERNEL);
        if (irttp == NULL)
                return -ENOMEM;

        irttp->magic = TTP_MAGIC;

        irttp->tsaps = hashbin_new(HB_LOCK);
        if (!irttp->tsaps) {
                IRDA_ERROR("%s: can't allocate IrTTP hashbin!\n",
                           __FUNCTION__);
                kfree(irttp);
                return -ENOMEM;
        }

        return 0;
}

/*
 * Function irttp_cleanup (void)
 *
 *    Called by module destruction/cleanup code
 *
 */
void __exit irttp_cleanup(void)
{
        /* Check for main structure */
        IRDA_ASSERT(irttp->magic == TTP_MAGIC, return;);

        /*
         *  Delete hashbin and close all TSAP instances in it
         */
        hashbin_delete(irttp->tsaps, (FREE_FUNC) __irttp_close_tsap);

        irttp->magic = 0;

        /* De-allocate main structure */
        kfree(irttp);

        irttp = NULL;
}

/*************************** SUBROUTINES ***************************/

/*
 * Function irttp_start_todo_timer (self, timeout)
 *
 *    Start todo timer.
 *
 * Made it more effient and unsensitive to race conditions - Jean II
 */
static inline void irttp_start_todo_timer(struct tsap_cb *self, int timeout)
{
        /* Set new value for timer */
        mod_timer(&self->todo_timer, jiffies + timeout);
}

/*
 * Function irttp_todo_expired (data)
 *
 *    Todo timer has expired!
 *
 * One of the restriction of the timer is that it is run only on the timer
 * interrupt which run every 10ms. This mean that even if you set the timer
 * with a delay of 0, it may take up to 10ms before it's run.
 * So, to minimise latency and keep cache fresh, we try to avoid using
 * it as much as possible.
 * Note : we can't use tasklets, because they can't be asynchronously
 * killed (need user context), and we can't guarantee that here...
 * Jean II
 */
static void irttp_todo_expired(unsigned long data)
{
        struct tsap_cb *self = (struct tsap_cb *) data;

        /* Check that we still exist */
        if (!self || self->magic != TTP_TSAP_MAGIC)
                return;

        IRDA_DEBUG(4, "%s(instance=%p)\n", __FUNCTION__, self);

        /* Try to make some progress, especially on Tx side - Jean II */
        irttp_run_rx_queue(self);
        irttp_run_tx_queue(self);

        /* Check if time for disconnect */
        if (test_bit(0, &self->disconnect_pend)) {
                /* Check if it's possible to disconnect yet */
                if (skb_queue_empty(&self->tx_queue)) {
                        /* Make sure disconnect is not pending anymore */
                        clear_bit(0, &self->disconnect_pend);   /* FALSE */

                        /* Note : self->disconnect_skb may be NULL */
                        irttp_disconnect_request(self, self->disconnect_skb,
                                                 P_NORMAL);
                        self->disconnect_skb = NULL;
                } else {
                        /* Try again later */
                        irttp_start_todo_timer(self, HZ/10);

                        /* No reason to try and close now */
                        return;
                }
        }

        /* Check if it's closing time */
        if (self->close_pend)
                /* Finish cleanup */
                irttp_close_tsap(self);
}

/*
 * Function irttp_flush_queues (self)
 *
 *     Flushes (removes all frames) in transitt-buffer (tx_list)
 */
void irttp_flush_queues(struct tsap_cb *self)
{
        struct sk_buff* skb;

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

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

        /* Deallocate frames waiting to be sent */
        while ((skb = skb_dequeue(&self->tx_queue)) != NULL)
                dev_kfree_skb(skb);

        /* Deallocate received frames */
        while ((skb = skb_dequeue(&self->rx_queue)) != NULL)
                dev_kfree_skb(skb);

        /* Deallocate received fragments */
        while ((skb = skb_dequeue(&self->rx_fragments)) != NULL)
                dev_kfree_skb(skb);
}

/*
 * Function irttp_reassemble (self)
 *
 *    Makes a new (continuous) skb of all the fragments in the fragment
 *    queue
 *
 */
static struct sk_buff *irttp_reassemble_skb(struct tsap_cb *self)
{
        struct sk_buff *skb, *frag;
        int n = 0;  /* Fragment index */

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

        IRDA_DEBUG(2, "%s(), self->rx_sdu_size=%d\n", __FUNCTION__,
                   self->rx_sdu_size);

        skb = dev_alloc_skb(TTP_HEADER + self->rx_sdu_size);
        if (!skb)
                return NULL;

        /*
         * Need to reserve space for TTP header in case this skb needs to
         * be requeued in case delivery failes
         */
        skb_reserve(skb, TTP_HEADER);
        skb_put(skb, self->rx_sdu_size);

        /*
         *  Copy all fragments to a new buffer
         */
        while ((frag = skb_dequeue(&self->rx_fragments)) != NULL) {
                skb_copy_to_linear_data_offset(skb, n, frag->data, frag->len);
                n += frag->len;

                dev_kfree_skb(frag);
        }

        IRDA_DEBUG(2,
                   "%s(), frame len=%d, rx_sdu_size=%d, rx_max_sdu_size=%d\n",
                   __FUNCTION__, n, self->rx_sdu_size, self->rx_max_sdu_size);
        /* Note : irttp_run_rx_queue() calculate self->rx_sdu_size
         * by summing the size of all fragments, so we should always
         * have n == self->rx_sdu_size, except in cases where we
         * droped the last fragment (when self->rx_sdu_size exceed
         * self->rx_max_sdu_size), where n < self->rx_sdu_size.
         * Jean II */
        IRDA_ASSERT(n <= self->rx_sdu_size, n = self->rx_sdu_size;);

        /* Set the new length */
        skb_trim(skb, n);

        self->rx_sdu_size = 0;

        return skb;
}

/*
 * Function irttp_fragment_skb (skb)
 *
 *    Fragments a frame and queues all the fragments for transmission
 *
 */
static inline void irttp_fragment_skb(struct tsap_cb *self,
                                      struct sk_buff *skb)
{
        struct sk_buff *frag;
        __u8 *frame;

        IRDA_DEBUG(2, "%s()\n", __FUNCTION__);

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

        /*
         *  Split frame into a number of segments
         */
        while (skb->len > self->max_seg_size) {
                IRDA_DEBUG(2, "%s(), fragmenting ...\n", __FUNCTION__);

                /* Make new segment */
                frag = alloc_skb(self->max_seg_size+self->max_header_size,
                                 GFP_ATOMIC);
                if (!frag)
                        return;

                skb_reserve(frag, self->max_header_size);

                /* Copy data from the original skb into this fragment. */
                skb_copy_from_linear_data(skb, skb_put(frag, self->max_seg_size),
                              self->max_seg_size);

                /* Insert TTP header, with the more bit set */
                frame = skb_push(frag, TTP_HEADER);
                frame[0] = TTP_MORE;

                /* Hide the copied data from the original skb */
                skb_pull(skb, self->max_seg_size);

                /* Queue fragment */
                skb_queue_tail(&self->tx_queue, frag);
        }
        /* Queue what is left of the original skb */
        IRDA_DEBUG(2, "%s(), queuing last segment\n", __FUNCTION__);

        frame = skb_push(skb, TTP_HEADER);
        frame[0] = 0x00; /* Clear more bit */

        /* Queue fragment */
        skb_queue_tail(&self->tx_queue, skb);
}

/*
 * Function irttp_param_max_sdu_size (self, param)
 *
 *    Handle the MaxSduSize parameter in the connect frames, this function
 *    will be called both when this parameter needs to be inserted into, and
 *    extracted from the connect frames
 */
static int irttp_param_max_sdu_size(void *instance, irda_param_t *param,
                                    int get)
{
        struct tsap_cb *self;

        self = (struct tsap_cb *) instance;

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

        if (get)
                param->pv.i = self->tx_max_sdu_size;
        else
                self->tx_max_sdu_size = param->pv.i;

        IRDA_DEBUG(1, "%s(), MaxSduSize=%d\n", __FUNCTION__, param->pv.i);

        return 0;
}

/*************************** CLIENT CALLS ***************************/
/************************** LMP CALLBACKS **************************/
/* Everything is happily mixed up. Waiting for next clean up - Jean II */

/*
 * Function irttp_open_tsap (stsap, notify)
 *
 *    Create TSAP connection endpoint,
 */
struct tsap_cb *irttp_open_tsap(__u8 stsap_sel, int credit, notify_t *notify)
{
        struct tsap_cb *self;
        struct lsap_cb *lsap;
        notify_t ttp_notify;

        IRDA_ASSERT(irttp->magic == TTP_MAGIC, return NULL;);

        /* The IrLMP spec (IrLMP 1.1 p10) says that we have the right to
         * use only 0x01-0x6F. Of course, we can use LSAP_ANY as well.
         * JeanII */
        if((stsap_sel != LSAP_ANY) &&
           ((stsap_sel < 0x01) || (stsap_sel >= 0x70))) {
                IRDA_DEBUG(0, "%s(), invalid tsap!\n", __FUNCTION__);
                return NULL;
        }

        self = kzalloc(sizeof(struct tsap_cb), GFP_ATOMIC);
        if (self == NULL) {
                IRDA_DEBUG(0, "%s(), unable to kmalloc!\n", __FUNCTION__);
                return NULL;
        }
        spin_lock_init(&self->lock);

        /* Initialise todo timer */
        init_timer(&self->todo_timer);
        self->todo_timer.data     = (unsigned long) self;
        self->todo_timer.function = &irttp_todo_expired;

        /* Initialize callbacks for IrLMP to use */
        irda_notify_init(&ttp_notify);
        ttp_notify.connect_confirm = irttp_connect_confirm;
        ttp_notify.connect_indication = irttp_connect_indication;
        ttp_notify.disconnect_indication = irttp_disconnect_indication;
        ttp_notify.data_indication = irttp_data_indication;
        ttp_notify.udata_indication = irttp_udata_indication;
        ttp_notify.flow_indication = irttp_flow_indication;
        if(notify->status_indication != NULL)
                ttp_notify.status_indication = irttp_status_indication;
        ttp_notify.instance = self;
        strncpy(ttp_notify.name, notify->name, NOTIFY_MAX_NAME);

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

        skb_queue_head_init(&self->rx_queue);
        skb_queue_head_init(&self->tx_queue);
        skb_queue_head_init(&self->rx_fragments);
        /*
         *  Create LSAP at IrLMP layer
         */
        lsap = irlmp_open_lsap(stsap_sel, &ttp_notify, 0);
        if (lsap == NULL) {
                IRDA_WARNING("%s: unable to allocate LSAP!!\n", __FUNCTION__);
                return NULL;
        }

        /*
         *  If user specified LSAP_ANY as source TSAP selector, then IrLMP
         *  will replace it with whatever source selector which is free, so
         *  the stsap_sel we have might not be valid anymore
         */
        self->stsap_sel = lsap->slsap_sel;
        IRDA_DEBUG(4, "%s(), stsap_sel=%02x\n", __FUNCTION__, self->stsap_sel);

        self->notify = *notify;
        self->lsap = lsap;

        hashbin_insert(irttp->tsaps, (irda_queue_t *) self, (long) self, NULL);

        if (credit > TTP_RX_MAX_CREDIT)
                self->initial_credit = TTP_RX_MAX_CREDIT;
        else
                self->initial_credit = credit;

        return self;
}
EXPORT_SYMBOL(irttp_open_tsap);

/*
 * Function irttp_close (handle)
 *
 *    Remove an instance of a TSAP. This function should only deal with the
 *    deallocation of the TSAP, and resetting of the TSAPs values;
 *
 */
static void __irttp_close_tsap(struct tsap_cb *self)
{
        /* 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
         * a while before it's run... - Jean II */

        /*
         * If the peer device has given us some credits and we didn't have
         * anyone from before, then we need to shedule the tx queue.
         * We need to do that because our Tx have stopped (so we may not
         * get any LAP flow indication) and the user may be stopped as
         * well. - Jean II
         */
        if (self->send_credit == n) {
                /* Restart pushing stuff to LAP */
                irttp_run_tx_queue(self);
                /* Note : we don't want to schedule the todo timer
                 * because it has horrible latency. No tasklets
                 * because the tasklet API is broken. - Jean II */
        }

        return 0;
}

/*
 * Function irttp_status_indication (self, reason)
 *
 *    Status_indication, just pass to the higher layer...
 *
 */
static void irttp_status_indication(void *instance,
                                    LINK_STATUS link, LOCK_STATUS lock)
{
        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;);

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

        /*
         *  Inform service user if he has requested it
         */
        if (self->notify.status_indication != NULL)
                self->notify.status_indication(self->notify.instance,
                                               link, lock);
        else
                IRDA_DEBUG(2, "%s(), no handler\n", __FUNCTION__);
}

/*
 * Function irttp_flow_indication (self, reason)
 *
 *    Flow_indication : IrLAP tells us to send more data.
 *
 */
static void irttp_flow_indication(void *instance, void *sap, LOCAL_FLOW flow)
{
        struct tsap_cb *self;

        self = (struct tsap_cb *) instance;

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

        IRDA_DEBUG(4, "%s(instance=%p)\n", __FUNCTION__, self);

        /* We are "polled" directly from LAP, and the LAP want to fill
         * its Tx window. We want to do our best to send it data, so that
         * we maximise the window. On the other hand, we want to limit the
         * amount of work here so that LAP doesn't hang forever waiting
         * for packets. - Jean II */

        /* Try to send some packets. Currently, LAP calls us every time
         * there is one free slot, so we will send only one packet.
         * This allow the scheduler to do its round robin - Jean II */
        irttp_run_tx_queue(self);

        /* Note regarding the interraction with higher layer.
         * irttp_run_tx_queue() may call the client when its queue
         * start to empty, via notify.flow_indication(). Initially.
         * I wanted this to happen in a tasklet, to avoid client
         * grabbing the CPU, but we can't use tasklets safely. And timer
         * is definitely too slow.
         * This will happen only once per LAP window, and usually at
         * the third packet (unless window is smaller). LAP is still
         * doing mtt and sending first packet so it's sort of OK
         * to do that. Jean II */

        /* If we need to send disconnect. try to do it now */
        if(self->disconnect_pend)
                irttp_start_todo_timer(self, 0);
}

/*
 * Function irttp_flow_request (self, command)
 *
 *    This function could be used by the upper layers to tell IrTTP to stop
 *    delivering frames if the receive queues are starting to get full, or
 *    to tell IrTTP to start delivering frames again.
 */
void irttp_flow_request(struct tsap_cb *self, LOCAL_FLOW flow)
{
        IRDA_DEBUG(1, "%s()\n", __FUNCTION__);

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

        switch (flow) {
        case FLOW_STOP:
                IRDA_DEBUG(1, "%s(), flow stop\n", __FUNCTION__);
                self->rx_sdu_busy = TRUE;
                break;
        case FLOW_START:
                IRDA_DEBUG(1, "%s(), flow start\n", __FUNCTION__);
                self->rx_sdu_busy = FALSE;

                /* Client say he can accept more data, try to free our
                 * queues ASAP - Jean II */
                irttp_run_rx_queue(self);

                break;
        default:
                IRDA_DEBUG(1, "%s(), Unknown flow command!\n", __FUNCTION__);
        }
}
EXPORT_SYMBOL(irttp_flow_request);

/*
 * Function irttp_connect_request (self, dtsap_sel, daddr, qos)
 *
 *    Try to connect to remote destination TSAP selector
 *
 */
int irttp_connect_request(struct tsap_cb *self, __u8 dtsap_sel,
                          __u32 saddr, __u32 daddr,
                          struct qos_info *qos, __u32 max_sdu_size,
                          struct sk_buff *userdata)
{
        struct sk_buff *tx_skb;
        __u8 *frame;
        __u8 n;

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

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

        if (self->connected) {
                if(userdata)
                        dev_kfree_skb(userdata);
                return -EISCONN;
        }

        /* Any userdata supplied? */
        if (userdata == NULL) {
                tx_skb = alloc_skb(TTP_MAX_HEADER + TTP_SAR_HEADER,
                                   GFP_ATOMIC);
                if (!tx_skb)
                        return -ENOMEM;

                /* Reserve space for MUX_CONTROL and LAP header */
                skb_reserve(tx_skb, TTP_MAX_HEADER + TTP_SAR_HEADER);
        } else {
                tx_skb = userdata;
                /*
                 *  Check that the client has reserved enough space for
                 *  headers
                 */
                IRDA_ASSERT(skb_headroom(userdata) >= TTP_MAX_HEADER,
                        { dev_kfree_skb(userdata); return -1; } );
        }

        /* Initialize connection parameters */
        self->connected = FALSE;
        self->avail_credit = 0;
        self->rx_max_sdu_size = max_sdu_size;
        self->rx_sdu_size = 0;
        self->rx_sdu_busy = FALSE;
        self->dtsap_sel = dtsap_sel;

        n = self->initial_credit;

        self->remote_credit = 0;
        self->send_credit = 0;

        /*
         *  Give away max 127 credits for now
         */
        if (n > 127) {
                self->avail_credit=n-127;
                n = 127;
        }

        self->remote_credit = n;

        /* SAR enabled? */
        if (max_sdu_size > 0) {
                IRDA_ASSERT(skb_headroom(tx_skb) >= (TTP_MAX_HEADER + TTP_SAR_HEADER),
                        { dev_kfree_skb(tx_skb); return -1; } );

                /* Insert SAR parameters */
                frame = skb_push(tx_skb, TTP_HEADER+TTP_SAR_HEADER);

                frame[0] = TTP_PARAMETERS | n;
                frame[1] = 0x04; /* Length */
                frame[2] = 0x01; /* MaxSduSize */
                frame[3] = 0x02; /* Value length */

                put_unaligned(cpu_to_be16((__u16) max_sdu_size),
                              (__be16 *)(frame+4));
        } else {
                /* Insert plain TTP header */
                frame = skb_push(tx_skb, TTP_HEADER);

                /* Insert initial credit in frame */
                frame[0] = n & 0x7f;
        }

        /* Connect with IrLMP. No QoS parameters for now */
        return irlmp_connect_request(self->lsap, dtsap_sel, saddr, daddr, qos,
                                     tx_skb);
}
EXPORT_SYMBOL(irttp_connect_request);

/*
 * Function irttp_connect_confirm (handle, qos, skb)
 *
 *    Sevice user confirms TSAP connection with peer.
 *
 */
static void irttp_connect_confirm(void *instance, void *sap,
                                  struct qos_info *qos, __u32 max_seg_size,
                                  __u8 max_header_size, struct sk_buff *skb)
{
        struct tsap_cb *self;
        int parameters;
        int ret;
        __u8 plen;
        __u8 n;

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

        self = (struct tsap_cb *) instance;

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

        self->max_seg_size = max_seg_size - TTP_HEADER;
        self->max_header_size = max_header_size + TTP_HEADER;

        /*
         *  Check if we have got some QoS parameters back! This should be the
         *  negotiated QoS for the link.
         */
        if (qos) {
                IRDA_DEBUG(4, "IrTTP, Negotiated BAUD_RATE: %02x\n",
                       qos->baud_rate.bits);
                IRDA_DEBUG(4, "IrTTP, Negotiated BAUD_RATE: %d bps.\n",
                       qos->baud_rate.value);
        }

        n = skb->data[0] & 0x7f;

        IRDA_DEBUG(4, "%s(), Initial send_credit=%d\n", __FUNCTION__, n);

        self->send_credit = n;
        self->tx_max_sdu_size = 0;
        self->connected = TRUE;

        parameters = skb->data[0] & 0x80;

        IRDA_ASSERT(skb->len >= TTP_HEADER, return;);
        skb_pull(skb, TTP_HEADER);

        if (parameters) {
                plen = skb->data[0];

                ret = irda_param_extract_all(self, skb->data+1,
                                             IRDA_MIN(skb->len-1, plen),
                                             &param_info);

                /* Any errors in the parameter list? */
                if (ret < 0) {
                        IRDA_WARNING("%s: error extracting parameters\n",
                                     __FUNCTION__);
                        dev_kfree_skb(skb);

                        /* Do not accept this connection attempt */
                        return;
                }
                /* Remove parameters */
                skb_pull(skb, IRDA_MIN(skb->len, plen+1));
        }

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

        IRDA_DEBUG(2, "%s(), MaxSduSize=%d\n", __FUNCTION__,
                   self->tx_max_sdu_size);

        if (self->notify.connect_confirm) {
                self->notify.connect_confirm(self->notify.instance, self, qos,
                                             self->tx_max_sdu_size,
                                             self->max_header_size, skb);
        } else
                dev_kfree_skb(skb);
}

/*
 * Function irttp_connect_indication (handle, skb)
 *
 *    Some other device is connecting to this TSAP
 *
 */
void irttp_connect_indication(void *instance, void *sap, struct qos_info *qos,
                              __u32 max_seg_size, __u8 max_header_size,
                              struct sk_buff *skb)
{
        struct tsap_cb *self;
        struct lsap_cb *lsap;
        int parameters;
        int ret;
        __u8 plen;
        __u8 n;

        self = (struct tsap_cb *) instance;

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

        lsap = (struct lsap_cb *) sap;

        self->max_seg_size = max_seg_size - TTP_HEADER;
        self->max_header_size = max_header_size+TTP_HEADER;

        IRDA_DEBUG(4, "%s(), TSAP sel=%02x\n", __FUNCTION__, self->stsap_sel);

        /* Need to update dtsap_sel if its equal to LSAP_ANY */
        self->dtsap_sel = lsap->dlsap_sel;

        n = skb->data[0] & 0x7f;

        self->send_credit = n;
        self->tx_max_sdu_size = 0;

        parameters = skb->data[0] & 0x80;

        IRDA_ASSERT(skb->len >= TTP_HEADER, return;);
        skb_pull(skb, TTP_HEADER);

        if (parameters) {
                plen = skb->data[0];

                ret = irda_param_extract_all(self, skb->data+1,
                                             IRDA_MIN(skb->len-1, plen),
                                             &param_info);

                /* Any errors in the parameter list? */
                if (ret < 0) {
                        IRDA_WARNING("%s: error extracting parameters\n",
                                     __FUNCTION__);
                        dev_kfree_skb(skb);

                        /* Do not accept this connection attempt */
                        return;
                }

                /* Remove parameters */
                skb_pull(skb, IRDA_MIN(skb->len, plen+1));
        }

        if (self->notify.connect_indication) {
                self->notify.connect_indication(self->notify.instance, self,
                                                qos, self->tx_max_sdu_size,
                                                self->max_header_size, skb);
        } else
                dev_kfree_skb(skb);
}

/*
 * Function irttp_connect_response (handle, userdata)
 *
 *    Service user is accepting the connection, just pass it down to
 *    IrLMP!
 *
 */
int irttp_connect_response(struct tsap_cb *self, __u32 max_sdu_size,
                           struct sk_buff *userdata)
{
        struct sk_buff *tx_skb;
        __u8 *frame;
        int ret;
        __u8 n;

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

        IRDA_DEBUG(4, "%s(), Source TSAP selector=%02x\n", __FUNCTION__,
                   self->stsap_sel);

        /* Any userdata supplied? */
        if (userdata == NULL) {
                tx_skb = alloc_skb(TTP_MAX_HEADER + TTP_SAR_HEADER,
                                   GFP_ATOMIC);
                if (!tx_skb)
                        return -ENOMEM;

                /* Reserve space for MUX_CONTROL and LAP header */
                skb_reserve(tx_skb, TTP_MAX_HEADER + TTP_SAR_HEADER);
        } else {
                tx_skb = userdata;
                /*
                 *  Check that the client has reserved enough space for
                 *  headers
                 */
                IRDA_ASSERT(skb_headroom(userdata) >= TTP_MAX_HEADER,
                        { dev_kfree_skb(userdata); return -1; } );
        }

        self->avail_credit = 0;
        self->remote_credit = 0;
        self->rx_max_sdu_size = max_sdu_size;
        self->rx_sdu_size = 0;
        self->rx_sdu_busy = FALSE;

        n = self->initial_credit;

        /* Frame has only space for max 127 credits (7 bits) */
        if (n > 127) {
                self->avail_credit = n - 127;
                n = 127;
        }

        self->remote_credit = n;
        self->connected = TRUE;

        /* SAR enabled? */
        if (max_sdu_size > 0) {
                IRDA_ASSERT(skb_headroom(tx_skb) >= (TTP_MAX_HEADER + TTP_SAR_HEADER),
                        { dev_kfree_skb(tx_skb); return -1; } );

                /* Insert TTP header with SAR parameters */
                frame = skb_push(tx_skb, TTP_HEADER+TTP_SAR_HEADER);

                frame[0] = TTP_PARAMETERS | n;
                frame[1] = 0x04; /* Length */

                /* irda_param_insert(self, IRTTP_MAX_SDU_SIZE, frame+1,  */
/*                                TTP_SAR_HEADER, &param_info) */

                frame[2] = 0x01; /* MaxSduSize */
                frame[3] = 0x02; /* Value length */

                put_unaligned(cpu_to_be16((__u16) max_sdu_size),
                              (__be16 *)(frame+4));
        } else {
                /* Insert TTP header */
                frame = skb_push(tx_skb, TTP_HEADER);

                frame[0] = n & 0x7f;
        }

        ret = irlmp_connect_response(self->lsap, tx_skb);

        return ret;
}
EXPORT_SYMBOL(irttp_connect_response);

/*
 * Function irttp_dup (self, instance)
 *
 *    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;
        spin_lock_init(&new->lock);
        init_timer(&new->todo_timer);

        skb_queue_head_init(&new->rx_queue);
        skb_queue_head_init(&new->tx_queue);
        skb_queue_head_init(&new->rx_fragments);

        /* 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 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 */