Commit d8fd01e8 authored by Jean Tourrilhes's avatar Jean Tourrilhes Committed by Linus Torvalds

irda update 2/7:

        o [CORRECT] Fix race condition when starting todo timer
        o [CORRECT] Fix race condition when stopping higher layer
                Higher layer would think it is stopped and us it is started
        o [CORRECT] Give credit even if packets in Tx queue
                If Tx queue was stopped, could starve peer and deadlock
        o [CORRECT] Protect Rx credit update with spinlock
        o [CORRECT] Calculate properly self->avail_credit
                Didn't take into account queued Rx fragments
                Incremented even if Rx frame not delivered to higher layer
                -> would never stop the peer (i.e. not flow control)
                -> could become infinite
        o [CORRECT] Send credit when higher layer reenable receive
                Peer wouldn't restart Tx to us if flow stopped
        o [FEATURE] Implement LAP queue not full notification
                Lower latency, ...
        o [FEATURE] Reduce Tx queue to 8 packets (from 10)
                But make sure we can always send a full LAP window (7)
        o [FEATURE] Fix and optimise TTP flow control
                Make sure peer can always send a full LAP window (7)
                Minimise explicit credit updates (give_credit)
        o [FEATURE] Remove need for todo timer in Tx/Rx paths
                Less potential races, lower latency, lower context switches
                Could not use tasklet because broken API, better anyway ;-)
parent 4b1a0f62
...@@ -42,11 +42,48 @@ ...@@ -42,11 +42,48 @@
#define TTP_PARAMETERS 0x80 #define TTP_PARAMETERS 0x80
#define TTP_MORE 0x80 #define TTP_MORE 0x80
#define DEFAULT_INITIAL_CREDIT 14 /* Transmission queue sizes */
/* Worst case scenario, two window of data - Jean II */
#define TTP_LOW_THRESHOLD 4 #define TTP_TX_MAX_QUEUE 14
#define TTP_HIGH_THRESHOLD 10 /* We need to keep at least 5 frames to make sure that we can refill
#define TTP_MAX_QUEUE 14 * appropriately the LAP layer. LAP keeps only two buffers, and we need
* to have 7 to make a full window - Jean II */
#define TTP_TX_LOW_THRESHOLD 5
/* Most clients are synchronous with respect to flow control, so we can
* keep a low number of Tx buffers in TTP - Jean II */
#define TTP_TX_HIGH_THRESHOLD 7
/* Receive queue sizes */
/* Minimum of credit that the peer should hold.
* If the peer has less credits than 9 frames, we will explicitely send
* him some credits (through irttp_give_credit() and a specific frame).
* Note that when we give credits it's likely that it won't be sent in
* this LAP window, but in the next one. So, we make sure that the peer
* has something to send while waiting for credits (one LAP window == 7
* + 1 frames while he process the credits). - Jean II */
#define TTP_RX_MIN_CREDIT 8
/* This is the default maximum number of credits held by the peer, so the
* default maximum number of frames he can send us before needing flow
* control answer from us (this may be negociated differently at TSAP setup).
* We want to minimise the number of times we have to explicitely send some
* credit to the peer, hoping we can piggyback it on the return data. In
* particular, it doesn't make sense for us to send credit more than once
* per LAP window.
* Moreover, giving credits has some latency, so we need strictly more than
* a LAP window, otherwise we may already have credits in our Tx queue.
* But on the other hand, we don't want to keep too many Rx buffer here
* before starting to flow control the other end, so make it exactly one
* LAP window + 1 + MIN_CREDITS. - Jean II */
#define TTP_RX_DEFAULT_CREDIT 16
/* Maximum number of credits we can allow the peer to have, and therefore
* maximum Rx queue size.
* Note that we try to deliver packets to the higher layer every time we
* receive something, so in normal mode the Rx queue will never contains
* more than one or two packets. - Jean II */
#define TTP_RX_MAX_CREDIT 21
/* What clients should use when calling ttp_open_tsap() */
#define DEFAULT_INITIAL_CREDIT TTP_RX_DEFAULT_CREDIT
/* Some priorities for disconnect requests */ /* Some priorities for disconnect requests */
#define P_NORMAL 0 #define P_NORMAL 0
...@@ -90,7 +127,7 @@ struct tsap_cb { ...@@ -90,7 +127,7 @@ struct tsap_cb {
struct net_device_stats stats; struct net_device_stats stats;
struct timer_list todo_timer; struct timer_list todo_timer;
__u32 max_seg_size; /* Max data that fit into an IrLAP frame */ __u32 max_seg_size; /* Max data that fit into an IrLAP frame */
__u8 max_header_size; __u8 max_header_size;
...@@ -131,6 +168,7 @@ int irttp_disconnect_request(struct tsap_cb *self, struct sk_buff *skb, ...@@ -131,6 +168,7 @@ int irttp_disconnect_request(struct tsap_cb *self, struct sk_buff *skb,
void irttp_flow_request(struct tsap_cb *self, LOCAL_FLOW flow); void irttp_flow_request(struct tsap_cb *self, LOCAL_FLOW flow);
void irttp_status_indication(void *instance, void irttp_status_indication(void *instance,
LINK_STATUS link, LOCK_STATUS lock); LINK_STATUS link, LOCK_STATUS lock);
void irttp_flow_indication(void *instance, void *sap, LOCAL_FLOW flow);
struct tsap_cb *irttp_dup(struct tsap_cb *self, void *instance); struct tsap_cb *irttp_dup(struct tsap_cb *self, void *instance);
static __inline __u32 irttp_get_saddr(struct tsap_cb *self) static __inline __u32 irttp_get_saddr(struct tsap_cb *self)
......
...@@ -59,8 +59,8 @@ static void irttp_run_rx_queue(struct tsap_cb *self); ...@@ -59,8 +59,8 @@ static void irttp_run_rx_queue(struct tsap_cb *self);
static void irttp_flush_queues(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 void irttp_fragment_skb(struct tsap_cb *self, struct sk_buff *skb);
static void irttp_start_todo_timer(struct tsap_cb *self, int timeout);
static struct sk_buff *irttp_reassemble_skb(struct tsap_cb *self); 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, static int irttp_param_max_sdu_size(void *instance, irda_param_t *param,
int get); int get);
...@@ -72,6 +72,8 @@ static pi_minor_info_t pi_minor_call_table[] = { ...@@ -72,6 +72,8 @@ static pi_minor_info_t pi_minor_call_table[] = {
static pi_major_info_t pi_major_call_table[] = {{ pi_minor_call_table, 2 }}; 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 }; static pi_param_info_t param_info = { pi_major_call_table, 1, 0x0f, 4 };
/************************ GLOBAL PROCEDURES ************************/
/* /*
* Function irttp_init (void) * Function irttp_init (void)
* *
...@@ -126,6 +128,239 @@ void irttp_cleanup(void) ...@@ -126,6 +128,239 @@ void irttp_cleanup(void)
} }
#endif #endif
/*************************** 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, __FUNCTION__ "(instance=%p)\n", 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, __FUNCTION__ "()\n");
ASSERT(self != NULL, return;);
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 */
ASSERT(self != NULL, return NULL;);
ASSERT(self->magic == TTP_TSAP_MAGIC, return NULL;);
IRDA_DEBUG(2, __FUNCTION__ "(), self->rx_sdu_size=%d\n",
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) {
memcpy(skb->data+n, frag->data, frag->len);
n += frag->len;
dev_kfree_skb(frag);
}
IRDA_DEBUG(2, __FUNCTION__ "(), frame len=%d\n", n);
IRDA_DEBUG(2, __FUNCTION__ "(), rx_sdu_size=%d\n", self->rx_sdu_size);
ASSERT(n <= self->rx_sdu_size, return NULL;);
/* 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, __FUNCTION__ "()\n");
ASSERT(self != NULL, return;);
ASSERT(self->magic == TTP_TSAP_MAGIC, return;);
ASSERT(skb != NULL, return;);
/*
* Split frame into a number of segments
*/
while (skb->len > self->max_seg_size) {
IRDA_DEBUG(2, __FUNCTION__ "(), fragmenting ...\n");
/* Make new segment */
frag = dev_alloc_skb(self->max_seg_size+self->max_header_size);
if (!frag)
return;
skb_reserve(frag, self->max_header_size);
/* Copy data from the original skb into this fragment. */
memcpy(skb_put(frag, self->max_seg_size), skb->data,
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, __FUNCTION__ "(), queuing last segment\n");
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;
ASSERT(self != NULL, return -1;);
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, __FUNCTION__ "(), MaxSduSize=%d\n", 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) * Function irttp_open_tsap (stsap, notify)
* *
...@@ -157,7 +392,10 @@ struct tsap_cb *irttp_open_tsap(__u8 stsap_sel, int credit, notify_t *notify) ...@@ -157,7 +392,10 @@ struct tsap_cb *irttp_open_tsap(__u8 stsap_sel, int credit, notify_t *notify)
memset(self, 0, sizeof(struct tsap_cb)); memset(self, 0, sizeof(struct tsap_cb));
spin_lock_init(&self->lock); spin_lock_init(&self->lock);
/* Initialise todo timer */
init_timer(&self->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 */ /* Initialize callbacks for IrLMP to use */
irda_notify_init(&ttp_notify); irda_notify_init(&ttp_notify);
...@@ -166,6 +404,7 @@ struct tsap_cb *irttp_open_tsap(__u8 stsap_sel, int credit, notify_t *notify) ...@@ -166,6 +404,7 @@ struct tsap_cb *irttp_open_tsap(__u8 stsap_sel, int credit, notify_t *notify)
ttp_notify.disconnect_indication = irttp_disconnect_indication; ttp_notify.disconnect_indication = irttp_disconnect_indication;
ttp_notify.data_indication = irttp_data_indication; ttp_notify.data_indication = irttp_data_indication;
ttp_notify.udata_indication = irttp_udata_indication; ttp_notify.udata_indication = irttp_udata_indication;
ttp_notify.flow_indication = irttp_flow_indication;
if(notify->status_indication != NULL) if(notify->status_indication != NULL)
ttp_notify.status_indication = irttp_status_indication; ttp_notify.status_indication = irttp_status_indication;
ttp_notify.instance = self; ttp_notify.instance = self;
...@@ -199,8 +438,8 @@ struct tsap_cb *irttp_open_tsap(__u8 stsap_sel, int credit, notify_t *notify) ...@@ -199,8 +438,8 @@ struct tsap_cb *irttp_open_tsap(__u8 stsap_sel, int credit, notify_t *notify)
hashbin_insert(irttp->tsaps, (irda_queue_t *) self, (int) self, NULL); hashbin_insert(irttp->tsaps, (irda_queue_t *) self, (int) self, NULL);
if (credit > TTP_MAX_QUEUE) if (credit > TTP_RX_MAX_CREDIT)
self->initial_credit = TTP_MAX_QUEUE; self->initial_credit = TTP_RX_MAX_CREDIT;
else else
self->initial_credit = credit; self->initial_credit = credit;
...@@ -224,7 +463,7 @@ static void __irttp_close_tsap(struct tsap_cb *self) ...@@ -224,7 +463,7 @@ static void __irttp_close_tsap(struct tsap_cb *self)
del_timer(&self->todo_timer); del_timer(&self->todo_timer);
/* This one won't be cleaned up if we are diconnect_pend + close_pend /* This one won't be cleaned up if we are disconnect_pend + close_pend
* and we receive a disconnect_indication */ * and we receive a disconnect_indication */
if (self->disconnect_skb) if (self->disconnect_skb)
dev_kfree_skb(self->disconnect_skb); dev_kfree_skb(self->disconnect_skb);
...@@ -262,7 +501,7 @@ int irttp_close_tsap(struct tsap_cb *self) ...@@ -262,7 +501,7 @@ int irttp_close_tsap(struct tsap_cb *self)
irttp_disconnect_request(self, NULL, P_NORMAL); irttp_disconnect_request(self, NULL, P_NORMAL);
} }
self->close_pend = TRUE; self->close_pend = TRUE;
irttp_start_todo_timer(self, 1*HZ); irttp_start_todo_timer(self, HZ/10);
return 0; /* Will be back! */ return 0; /* Will be back! */
} }
...@@ -327,6 +566,9 @@ int irttp_data_request(struct tsap_cb *self, struct sk_buff *skb) ...@@ -327,6 +566,9 @@ int irttp_data_request(struct tsap_cb *self, struct sk_buff *skb)
ASSERT(self->magic == TTP_TSAP_MAGIC, return -1;); ASSERT(self->magic == TTP_TSAP_MAGIC, return -1;);
ASSERT(skb != NULL, return -1;); ASSERT(skb != NULL, return -1;);
IRDA_DEBUG(2, __FUNCTION__ " : queue len = %d\n",
skb_queue_len(&self->tx_queue));
/* Check that nothing bad happens */ /* Check that nothing bad happens */
if ((skb->len == 0) || (!self->connected)) { if ((skb->len == 0) || (!self->connected)) {
WARNING(__FUNCTION__ "(), No data, or not connected\n"); WARNING(__FUNCTION__ "(), No data, or not connected\n");
...@@ -358,12 +600,14 @@ int irttp_data_request(struct tsap_cb *self, struct sk_buff *skb) ...@@ -358,12 +600,14 @@ int irttp_data_request(struct tsap_cb *self, struct sk_buff *skb)
/* /*
* Check if transmit queue is full * Check if transmit queue is full
*/ */
if (skb_queue_len(&self->tx_queue) >= TTP_MAX_QUEUE) { if (skb_queue_len(&self->tx_queue) >= TTP_TX_MAX_QUEUE) {
/* /*
* Give it a chance to empty itself * Give it a chance to empty itself
*/ */
irttp_run_tx_queue(self); irttp_run_tx_queue(self);
/* Drop packet. This error code should trigger the caller
* to requeue the packet in the client code - Jean II */
return -ENOBUFS; return -ENOBUFS;
} }
...@@ -387,20 +631,25 @@ int irttp_data_request(struct tsap_cb *self, struct sk_buff *skb) ...@@ -387,20 +631,25 @@ int irttp_data_request(struct tsap_cb *self, struct sk_buff *skb)
/* Check if we can accept more data from client */ /* Check if we can accept more data from client */
if ((!self->tx_sdu_busy) && if ((!self->tx_sdu_busy) &&
(skb_queue_len(&self->tx_queue) > TTP_HIGH_THRESHOLD)) { (skb_queue_len(&self->tx_queue) > TTP_TX_HIGH_THRESHOLD)) {
/* Tx queue filling up, so stop client. */
/* Tx queue filling up, so stop client */ if (self->notify.flow_indication) {
self->tx_sdu_busy = TRUE;
if (self->notify.flow_indication) {
self->notify.flow_indication(self->notify.instance, self->notify.flow_indication(self->notify.instance,
self, FLOW_STOP); 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 */ /* Try to make some progress */
irttp_run_tx_queue(self); irttp_run_tx_queue(self);
return 0; return 0;
} }
...@@ -416,28 +665,20 @@ static void irttp_run_tx_queue(struct tsap_cb *self) ...@@ -416,28 +665,20 @@ static void irttp_run_tx_queue(struct tsap_cb *self)
unsigned long flags; unsigned long flags;
int n; int n;
IRDA_DEBUG(2, __FUNCTION__ "() : send_credit = %d, queue_len = %d\n",
self->send_credit, skb_queue_len(&self->tx_queue));
/* Get exclusive access to the tx queue, otherwise don't touch it */ /* Get exclusive access to the tx queue, otherwise don't touch it */
if (irda_lock(&self->tx_queue_lock) == FALSE) if (irda_lock(&self->tx_queue_lock) == FALSE)
return; return;
/* Try to send out frames as long as we have credits */ /* 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) && while ((self->send_credit > 0) &&
(!irlmp_lap_tx_queue_full(self->lsap)) &&
(skb = skb_dequeue(&self->tx_queue))) (skb = skb_dequeue(&self->tx_queue)))
{ {
/*
* Make sure we don't flood IrLAP with frames just because
* the remote device has given us a lot of credits
*/
if (irlmp_get_lap_tx_queue_len(self->lsap) > LAP_MAX_QUEUE) {
/* Re-queue packet */
skb_queue_head(&self->tx_queue, skb);
/* Try later. Would be better if IrLAP could notify us */
irttp_start_todo_timer(self, MSECS_TO_JIFFIES(10));
break;
}
/* /*
* Since we can transmit and receive frames concurrently, * Since we can transmit and receive frames concurrently,
* the code below is a critical region and we must assure that * the code below is a critical region and we must assure that
...@@ -484,32 +725,35 @@ static void irttp_run_tx_queue(struct tsap_cb *self) ...@@ -484,32 +725,35 @@ static void irttp_run_tx_queue(struct tsap_cb *self)
* Jean II */ * Jean II */
if (skb->sk != NULL) { if (skb->sk != NULL) {
/* IrSOCK application, IrOBEX, ... */ /* IrSOCK application, IrOBEX, ... */
IRDA_DEBUG(4, __FUNCTION__ "() : Detaching SKB from socket.\n");
/* That's the right way to do it - Jean II */
skb_orphan(skb); skb_orphan(skb);
} else {
/* IrCOMM over IrTTP, IrLAN, ... */
IRDA_DEBUG(4, __FUNCTION__ "() : Got SKB not attached to a socket.\n");
} }
/* IrCOMM over IrTTP, IrLAN, ... */
/* Pass the skb to IrLMP - done */ /* Pass the skb to IrLMP - done */
irlmp_data_request(self->lsap, skb); irlmp_data_request(self->lsap, skb);
self->stats.tx_packets++; self->stats.tx_packets++;
}
/* Check if we can accept more frames from client */ /* Check if we can accept more frames from client.
if ((self->tx_sdu_busy) && * We don't want to wait until the todo timer to do that, and we
(skb_queue_len(&self->tx_queue) < TTP_LOW_THRESHOLD)) * 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
self->tx_sdu_busy = FALSE; * (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->notify.flow_indication) if ((self->tx_sdu_busy) &&
self->notify.flow_indication( (skb_queue_len(&self->tx_queue) < TTP_TX_LOW_THRESHOLD) &&
self->notify.instance, self, (!self->close_pend))
FLOW_START); {
} 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 */ /* Reset lock */
self->tx_queue_lock = 0; self->tx_queue_lock = 0;
} }
...@@ -520,7 +764,7 @@ static void irttp_run_tx_queue(struct tsap_cb *self) ...@@ -520,7 +764,7 @@ static void irttp_run_tx_queue(struct tsap_cb *self)
* Send a dataless flowdata TTP-PDU and give available credit to peer * Send a dataless flowdata TTP-PDU and give available credit to peer
* TSAP * TSAP
*/ */
void irttp_give_credit(struct tsap_cb *self) static inline void irttp_give_credit(struct tsap_cb *self)
{ {
struct sk_buff *tx_skb = NULL; struct sk_buff *tx_skb = NULL;
unsigned long flags; unsigned long flags;
...@@ -531,7 +775,7 @@ void irttp_give_credit(struct tsap_cb *self) ...@@ -531,7 +775,7 @@ void irttp_give_credit(struct tsap_cb *self)
IRDA_DEBUG(4, __FUNCTION__ "() send=%d,avail=%d,remote=%d\n", IRDA_DEBUG(4, __FUNCTION__ "() send=%d,avail=%d,remote=%d\n",
self->send_credit, self->avail_credit, self->remote_credit); self->send_credit, self->avail_credit, self->remote_credit);
/* Give credit to peer */ /* Give credit to peer */
tx_skb = dev_alloc_skb(64); tx_skb = dev_alloc_skb(64);
if (!tx_skb) if (!tx_skb)
...@@ -606,6 +850,7 @@ static int irttp_data_indication(void *instance, void *sap, ...@@ -606,6 +850,7 @@ static int irttp_data_indication(void *instance, void *sap,
struct sk_buff *skb) struct sk_buff *skb)
{ {
struct tsap_cb *self; struct tsap_cb *self;
unsigned long flags;
int n; int n;
self = (struct tsap_cb *) instance; self = (struct tsap_cb *) instance;
...@@ -614,47 +859,66 @@ static int irttp_data_indication(void *instance, void *sap, ...@@ -614,47 +859,66 @@ static int irttp_data_indication(void *instance, void *sap,
self->stats.rx_packets++; 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 * Data or dataless packet? Dataless frames contains only the
* TTP_HEADER. * TTP_HEADER.
*/ */
if (skb->len > 1) { if (skb->len > 1) {
/* Deal with inbound credit */
self->send_credit += n;
self->remote_credit--;
/* /*
* We don't remove the TTP header, since we must preserve the * We don't remove the TTP header, since we must preserve the
* more bit, so the defragment routing knows what to do * more bit, so the defragment routing knows what to do
*/ */
skb_queue_tail(&self->rx_queue, skb); skb_queue_tail(&self->rx_queue, skb);
} else { } else {
self->send_credit += n; /* Dataless flowdata TTP-PDU */ /* Dataless flowdata TTP-PDU */
dev_kfree_skb(skb); 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); irttp_run_rx_queue(self);
/* /* We now give credits to peer in irttp_run_rx_queue().
* Give avay some credits to peer? * We need to send credit *NOW*, otherwise we are going
*/ * to miss the next Tx window. The todo timer may take
if ((skb_queue_empty(&self->tx_queue)) && * a while before it's run... - Jean II */
(self->remote_credit < TTP_LOW_THRESHOLD) &&
(self->avail_credit > 0))
{
/* Schedule to start immediately after this thread */
irttp_start_todo_timer(self, 0);
/*irttp_give_credit(self);*/
}
/* /*
* If the peer device has given us some credits and we didn't have * If the peer device has given us some credits and we didn't have
* anyone from before, the we need to shedule the tx queue? * 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) { if (self->send_credit == n) {
/*irttp_run_tx_queue(self);*/ /* Restart pushing stuff to LAP */
irttp_start_todo_timer(self, 0); 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; return 0;
} }
...@@ -686,6 +950,50 @@ void irttp_status_indication(void *instance, ...@@ -686,6 +950,50 @@ void irttp_status_indication(void *instance,
IRDA_DEBUG(2, __FUNCTION__ "(), no handler\n"); IRDA_DEBUG(2, __FUNCTION__ "(), no handler\n");
} }
/*
* Function irttp_flow_indication (self, reason)
*
* Flow_indication : IrLAP tells us to send more data.
*
*/
void irttp_flow_indication(void *instance, void *sap, LOCAL_FLOW flow)
{
struct tsap_cb *self;
self = (struct tsap_cb *) instance;
ASSERT(self != NULL, return;);
ASSERT(self->magic == TTP_TSAP_MAGIC, return;);
IRDA_DEBUG(4, __FUNCTION__ "(instance=%p)\n", 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) * Function irttp_flow_request (self, command)
* *
...@@ -709,7 +1017,10 @@ void irttp_flow_request(struct tsap_cb *self, LOCAL_FLOW flow) ...@@ -709,7 +1017,10 @@ void irttp_flow_request(struct tsap_cb *self, LOCAL_FLOW flow)
IRDA_DEBUG(1, __FUNCTION__ "(), flow start\n"); IRDA_DEBUG(1, __FUNCTION__ "(), flow start\n");
self->rx_sdu_busy = FALSE; 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); irttp_run_rx_queue(self);
break; break;
default: default:
IRDA_DEBUG(1, __FUNCTION__ "(), Unknown flow command!\n"); IRDA_DEBUG(1, __FUNCTION__ "(), Unknown flow command!\n");
...@@ -1147,10 +1458,15 @@ int irttp_disconnect_request(struct tsap_cb *self, struct sk_buff *userdata, ...@@ -1147,10 +1458,15 @@ int irttp_disconnect_request(struct tsap_cb *self, struct sk_buff *userdata,
irttp_run_tx_queue(self); irttp_run_tx_queue(self);
irttp_start_todo_timer(self, MSECS_TO_JIFFIES(1000)); irttp_start_todo_timer(self, HZ/10);
return -1; 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, __FUNCTION__ "(), Disconnecting ...\n"); IRDA_DEBUG(1, __FUNCTION__ "(), Disconnecting ...\n");
self->connected = FALSE; self->connected = FALSE;
...@@ -1281,8 +1597,7 @@ void irttp_run_rx_queue(struct tsap_cb *self) ...@@ -1281,8 +1597,7 @@ void irttp_run_rx_queue(struct tsap_cb *self)
* Reassemble all frames in receive queue and deliver them * Reassemble all frames in receive queue and deliver them
*/ */
while (!self->rx_sdu_busy && (skb = skb_dequeue(&self->rx_queue))) { while (!self->rx_sdu_busy && (skb = skb_dequeue(&self->rx_queue))) {
self->avail_credit++; /* This bit will tell us if it's the last fragment or not */
more = skb->data[0] & 0x80; more = skb->data[0] & 0x80;
/* Remove TTP header */ /* Remove TTP header */
...@@ -1293,7 +1608,7 @@ void irttp_run_rx_queue(struct tsap_cb *self) ...@@ -1293,7 +1608,7 @@ void irttp_run_rx_queue(struct tsap_cb *self)
/* /*
* If SAR is disabled, or user has requested no reassembly * If SAR is disabled, or user has requested no reassembly
* of received fragements then we just deliver them * of received fragments then we just deliver them
* immediately. This can be requested by clients that * immediately. This can be requested by clients that
* implements byte streams without any message boundaries * implements byte streams without any message boundaries
*/ */
...@@ -1353,236 +1668,46 @@ void irttp_run_rx_queue(struct tsap_cb *self) ...@@ -1353,236 +1668,46 @@ void irttp_run_rx_queue(struct tsap_cb *self)
} }
self->rx_sdu_size = 0; self->rx_sdu_size = 0;
} }
/* Reset lock */
self->rx_queue_lock = 0;
}
/*
* 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, __FUNCTION__ "()\n");
ASSERT(self != NULL, return;);
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_reasseble (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 */
ASSERT(self != NULL, return NULL;);
ASSERT(self->magic == TTP_TSAP_MAGIC, return NULL;);
IRDA_DEBUG(2, __FUNCTION__ "(), self->rx_sdu_size=%d\n",
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) {
memcpy(skb->data+n, frag->data, frag->len);
n += frag->len;
dev_kfree_skb(frag);
}
IRDA_DEBUG(2, __FUNCTION__ "(), frame len=%d\n", n);
IRDA_DEBUG(2, __FUNCTION__ "(), rx_sdu_size=%d\n", self->rx_sdu_size);
ASSERT(n <= self->rx_sdu_size, return NULL;);
/* 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 void irttp_fragment_skb(struct tsap_cb *self, struct sk_buff *skb)
{
struct sk_buff *frag;
__u8 *frame;
IRDA_DEBUG(2, __FUNCTION__ "()\n");
ASSERT(self != NULL, return;);
ASSERT(self->magic == TTP_TSAP_MAGIC, return;);
ASSERT(skb != NULL, return;);
/* /*
* Split frame into a number of segments * 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
*/ */
while (skb->len > self->max_seg_size) { self->avail_credit = (self->initial_credit -
IRDA_DEBUG(2, __FUNCTION__ "(), fragmenting ...\n"); (self->remote_credit +
skb_queue_len(&self->rx_queue) +
/* Make new segment */ skb_queue_len(&self->rx_fragments)));
frag = dev_alloc_skb(self->max_seg_size+self->max_header_size);
if (!frag) /* Do we have too much credits to send to peer ? */
return; if ((self->remote_credit <= TTP_RX_MIN_CREDIT) &&
(self->avail_credit > 0)) {
skb_reserve(frag, self->max_header_size); /* Send explicit credit frame */
/* Copy data from the original skb into this fragment. */
memcpy(skb_put(frag, self->max_seg_size), skb->data,
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, __FUNCTION__ "(), queuing last segment\n");
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;
ASSERT(self != NULL, return -1;);
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, __FUNCTION__ "(), MaxSduSize=%d\n", param->pv.i);
return 0;
}
/*
* Function irttp_todo_expired (data)
*
* Todo timer has expired!
*
*/
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;
irttp_run_rx_queue(self);
irttp_run_tx_queue(self);
/* Give avay some credits to peer? */
if ((self->remote_credit < TTP_LOW_THRESHOLD) &&
(self->avail_credit > 0) && (skb_queue_empty(&self->tx_queue)))
{
irttp_give_credit(self); 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
*/
} }
/* Check if time for disconnect */ /* Reset lock */
if (test_bit(0, &self->disconnect_pend)) { self->rx_queue_lock = 0;
/* 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, 1*HZ);
/* No reason to try and close now */
return;
}
}
/* Check if it's closing time */
if (self->close_pend)
irttp_close_tsap(self);
}
/*
* Function irttp_start_todo_timer (self, timeout)
*
* Start todo timer.
*
*/
static void irttp_start_todo_timer(struct tsap_cb *self, int timeout)
{
ASSERT(self != NULL, return;);
ASSERT(self->magic == TTP_TSAP_MAGIC, return;);
del_timer(&self->todo_timer);
self->todo_timer.data = (unsigned long) self;
self->todo_timer.function = &irttp_todo_expired;
self->todo_timer.expires = jiffies + timeout;
add_timer(&self->todo_timer);
} }
#ifdef CONFIG_PROC_FS #ifdef CONFIG_PROC_FS
......
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