irlap_event.c

linux 内核源代码

/*********************************************************************
 *
 * Filename:      irlap_event.c
 * Version:       0.9
 * Description:   IrLAP state machine implementation
 * Status:        Experimental.
 * Author:        Dag Brattli <[e-mail]>
 * Created at:    Sat Aug 16 00:59:29 1997
 * Modified at:   Sat Dec 25 21:07:57 1999
 * Modified by:   Dag Brattli <[e-mail]>
 *
 *     Copyright (c) 1998-2000 Dag Brattli <[e-mail]>,
 *     Copyright (c) 1998      Thomas Davis <[e-mail]>
 *     All Rights Reserved.
 *     Copyright (c) 2000-2003 Jean Tourrilhes <[e-mail]>
 *
 *     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/string.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/skbuff.h>

#include <net/irda/irda.h>
#include <net/irda/irlap_event.h>

#include <net/irda/timer.h>
#include <net/irda/irlap.h>
#include <net/irda/irlap_frame.h>
#include <net/irda/qos.h>
#include <net/irda/parameters.h>
#include <net/irda/irlmp.h>		/* irlmp_flow_indication(), ... */

#include <net/irda/irda_device.h>

#ifdef CONFIG_IRDA_FAST_RR
int sysctl_fast_poll_increase = 50;
#endif

static int irlap_state_ndm    (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_query  (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_reply  (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_conn   (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_setup  (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_offline(struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_xmit_p (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_pclose (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_nrm_p  (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_reset_wait(struct irlap_cb *self, IRLAP_EVENT event,
				  struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_reset  (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_nrm_s  (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_xmit_s (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_sclose (struct irlap_cb *self, IRLAP_EVENT event,
			       struct sk_buff *skb, struct irlap_info *info);
static int irlap_state_reset_check(struct irlap_cb *, IRLAP_EVENT event,
				   struct sk_buff *, struct irlap_info *);

#ifdef CONFIG_IRDA_DEBUG
static const char *irlap_event[] = {
	"DISCOVERY_REQUEST",
	"CONNECT_REQUEST",
	"CONNECT_RESPONSE",
	"DISCONNECT_REQUEST",
	"DATA_REQUEST",
	"RESET_REQUEST",
	"RESET_RESPONSE",
	"SEND_I_CMD",
	"SEND_UI_FRAME",
	"RECV_DISCOVERY_XID_CMD",
	"RECV_DISCOVERY_XID_RSP",
	"RECV_SNRM_CMD",
	"RECV_TEST_CMD",
	"RECV_TEST_RSP",
	"RECV_UA_RSP",
	"RECV_DM_RSP",
	"RECV_RD_RSP",
	"RECV_I_CMD",
	"RECV_I_RSP",
	"RECV_UI_FRAME",
	"RECV_FRMR_RSP",
	"RECV_RR_CMD",
	"RECV_RR_RSP",
	"RECV_RNR_CMD",
	"RECV_RNR_RSP",
	"RECV_REJ_CMD",
	"RECV_REJ_RSP",
	"RECV_SREJ_CMD",
	"RECV_SREJ_RSP",
	"RECV_DISC_CMD",
	"SLOT_TIMER_EXPIRED",
	"QUERY_TIMER_EXPIRED",
	"FINAL_TIMER_EXPIRED",
	"POLL_TIMER_EXPIRED",
	"DISCOVERY_TIMER_EXPIRED",
	"WD_TIMER_EXPIRED",
	"BACKOFF_TIMER_EXPIRED",
	"MEDIA_BUSY_TIMER_EXPIRED",
};
#endif	/* CONFIG_IRDA_DEBUG */

const char *irlap_state[] = {
	"LAP_NDM",
	"LAP_QUERY",
	"LAP_REPLY",
	"LAP_CONN",
	"LAP_SETUP",
	"LAP_OFFLINE",
	"LAP_XMIT_P",
	"LAP_PCLOSE",
	"LAP_NRM_P",
	"LAP_RESET_WAIT",
	"LAP_RESET",
	"LAP_NRM_S",
	"LAP_XMIT_S",
	"LAP_SCLOSE",
	"LAP_RESET_CHECK",
};

static int (*state[])(struct irlap_cb *self, IRLAP_EVENT event,
		      struct sk_buff *skb, struct irlap_info *info) =
{
	irlap_state_ndm,
	irlap_state_query,
	irlap_state_reply,
	irlap_state_conn,
	irlap_state_setup,
	irlap_state_offline,
	irlap_state_xmit_p,
	irlap_state_pclose,
	irlap_state_nrm_p,
	irlap_state_reset_wait,
	irlap_state_reset,
	irlap_state_nrm_s,
	irlap_state_xmit_s,
	irlap_state_sclose,
	irlap_state_reset_check,
};

/*
 * Function irda_poll_timer_expired (data)
 *
 *    Poll timer has expired. Normally we must now send a RR frame to the
 *    remote device
 */
static void irlap_poll_timer_expired(void *data)
{
	struct irlap_cb *self = (struct irlap_cb *) data;

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

	irlap_do_event(self, POLL_TIMER_EXPIRED, NULL, NULL);
}

/*
 * Calculate and set time before we will have to send back the pf bit
 * to the peer. Use in primary.
 * Make sure that state is XMIT_P/XMIT_S when calling this function
 * (and that nobody messed up with the state). - Jean II
 */
static void irlap_start_poll_timer(struct irlap_cb *self, int timeout)
{
	IRDA_ASSERT(self != NULL, return;);
	IRDA_ASSERT(self->magic == LAP_MAGIC, return;);

#ifdef CONFIG_IRDA_FAST_RR
	/*
	 * Send out the RR frames faster if our own transmit queue is empty, or
	 * if the peer is busy. The effect is a much faster conversation
	 */
	if (skb_queue_empty(&self->txq) || self->remote_busy) {
		if (self->fast_RR == TRUE) {
			/*
			 *  Assert that the fast poll timer has not reached the
			 *  normal poll timer yet
			 */
			if (self->fast_RR_timeout < timeout) {
				/*
				 *  FIXME: this should be a more configurable
				 *         function
				 */
				self->fast_RR_timeout +=
					(sysctl_fast_poll_increase * HZ/1000);

				/* Use this fast(er) timeout instead */
				timeout = self->fast_RR_timeout;
			}
		} else {
			self->fast_RR = TRUE;

			/* Start with just 0 ms */
			self->fast_RR_timeout = 0;
			timeout = 0;
		}
	} else
		self->fast_RR = FALSE;

	IRDA_DEBUG(3, "%s(), timeout=%d (%ld)\n", __FUNCTION__, timeout, jiffies);
#endif /* CONFIG_IRDA_FAST_RR */

	if (timeout == 0)
		irlap_do_event(self, POLL_TIMER_EXPIRED, NULL, NULL);
	else
		irda_start_timer(&self->poll_timer, timeout, self,
				 irlap_poll_timer_expired);
}

/*
 * Function irlap_do_event (event, skb, info)
 *
 *    Rushes through the state machine without any delay. If state == XMIT
 *    then send queued data frames.
 */
void irlap_do_event(struct irlap_cb *self, IRLAP_EVENT event,
		    struct sk_buff *skb, struct irlap_info *info)
{
	int ret;

	if (!self || self->magic != LAP_MAGIC)
		return;

	IRDA_DEBUG(3, "%s(), event = %s, state = %s\n", __FUNCTION__,
		   irlap_event[event], irlap_state[self->state]);

	ret = (*state[self->state])(self, event, skb, info);

	/*
	 *  Check if there are any pending events that needs to be executed
	 */
	switch (self->state) {
	case LAP_XMIT_P: /* FALLTHROUGH */
	case LAP_XMIT_S:
		/*
		 * We just received the pf bit and are at the beginning
		 * of a new LAP transmit window.
		 * Check if there are any queued data frames, and do not
		 * try to disconnect link if we send any data frames, since
		 * that will change the state away form XMIT
		 */
		IRDA_DEBUG(2, "%s() : queue len = %d\n", __FUNCTION__,
			   skb_queue_len(&self->txq));

		if (!skb_queue_empty(&self->txq)) {
			/* Prevent race conditions with irlap_data_request() */
			self->local_busy = TRUE;

			/* Theory of operation.
			 * We send frames up to when we fill the window or
			 * reach line capacity. Those frames will queue up
			 * in the device queue, and the driver will slowly
			 * send them.
			 * After each frame that we send, we poll the higher
			 * layer for more data. It's the right time to do
			 * that because the link layer need to perform the mtt
			 * and then send the first frame, so we can afford
			 * to send a bit of time in kernel space.
			 * The explicit flow indication allow to minimise
			 * buffers (== lower latency), to avoid higher layer
			 * polling via timers (== less context switches) and
			 * to implement a crude scheduler - Jean II */

			/* Try to send away all queued data frames */
			while ((skb = skb_dequeue(&self->txq)) != NULL) {
				/* Send one frame */
				ret = (*state[self->state])(self, SEND_I_CMD,
							    skb, NULL);
				/* Drop reference count.
				 * It will be increase as needed in
				 * irlap_send_data_xxx() */
				kfree_skb(skb);

				/* Poll the higher layers for one more frame */
				irlmp_flow_indication(self->notify.instance,
						      FLOW_START);

				if (ret == -EPROTO)
					break; /* Try again later! */
			}
			/* Finished transmitting */
			self->local_busy = FALSE;
		} else if (self->disconnect_pending) {
			self->disconnect_pending = FALSE;

			ret = (*state[self->state])(self, DISCONNECT_REQUEST,
						    NULL, NULL);
		}
		break;
/*	case LAP_NDM: */
/*	case LAP_CONN: */
/*	case LAP_RESET_WAIT: */
/*	case LAP_RESET_CHECK: */
	default:
		break;
	}
}

/*
 * Function irlap_state_ndm (event, skb, frame)
 *
 *    NDM (Normal Disconnected Mode) state
 *
 */
static int irlap_state_ndm(struct irlap_cb *self, IRLAP_EVENT event,
			   struct sk_buff *skb, struct irlap_info *info)
{
	discovery_t *discovery_rsp;
	int ret = 0;

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

	switch (event) {
	case CONNECT_REQUEST:
		IRDA_ASSERT(self->netdev != NULL, return -1;);

		if (self->media_busy) {
			/* Note : this will never happen, because we test
			 * media busy in irlap_connect_request() and
			 * postpone the event... - Jean II */
			IRDA_DEBUG(0, "%s(), CONNECT_REQUEST: media busy!\n",
				   __FUNCTION__);

			/* Always switch state before calling upper layers */
			irlap_next_state(self, LAP_NDM);

			irlap_disconnect_indication(self, LAP_MEDIA_BUSY);
		} else {
			irlap_send_snrm_frame(self, &self->qos_rx);

			/* Start Final-bit timer */
			irlap_start_final_timer(self, self->final_timeout);

			self->retry_count = 0;
			irlap_next_state(self, LAP_SETUP);
		}
		break;
	case RECV_SNRM_CMD:
		/* Check if the frame contains and I field */
		if (info) {
			self->daddr = info->daddr;
			self->caddr = info->caddr;

			irlap_next_state(self, LAP_CONN);

			irlap_connect_indication(self, skb);
		} else {
			IRDA_DEBUG(0, "%s(), SNRM frame does not "
				   "contain an I field!\n", __FUNCTION__);
		}
		break;
	case DISCOVERY_REQUEST:
		IRDA_ASSERT(info != NULL, return -1;);

		if (self->media_busy) {
			IRDA_DEBUG(1, "%s(), DISCOVERY_REQUEST: media busy!\n",
				   __FUNCTION__);
			/* irlap->log.condition = MEDIA_BUSY; */

			/* This will make IrLMP try again */
			irlap_discovery_confirm(self, NULL);
			/* Note : the discovery log is not cleaned up here,
			 * it will be done in irlap_discovery_request()
			 * Jean II */
			return 0;
		}

		self->S = info->S;
		self->s = info->s;
		irlap_send_discovery_xid_frame(self, info->S, info->s, TRUE,
					       info->discovery);
		self->frame_sent = FALSE;
		self->s++;

		irlap_start_slot_timer(self, self->slot_timeout);
		irlap_next_state(self, LAP_QUERY);
		break;
	case RECV_DISCOVERY_XID_CMD:
		IRDA_ASSERT(info != NULL, return -1;);

		/* Assert that this is not the final slot */
		if (info->s <= info->S) {
			self->slot = irlap_generate_rand_time_slot(info->S,
								   info->s);
			if (self->slot == info->s) {
				discovery_rsp = irlmp_get_discovery_response();
				discovery_rsp->data.daddr = info->daddr;

				irlap_send_discovery_xid_frame(self, info->S,
							       self->slot,
							       FALSE,
							       discovery_rsp);
				self->frame_sent = TRUE;
			} else
				self->frame_sent = FALSE;

			/*
			 * Go to reply state until end of discovery to
			 * inhibit our own transmissions. Set the timer
			 * to not stay forever there... Jean II
			 */
			irlap_start_query_timer(self, info->S, info->s);
			irlap_next_state(self, LAP_REPLY);
		} else {
		/* This is the final slot. How is it possible ?
		 * This would happen is both discoveries are just slightly
		 * offset (if they are in sync, all packets are lost).
		 * Most often, all the discovery requests will be received
		 * in QUERY state (see my comment there), except for the
		 * last frame that will come here.
		 * The big trouble when it happen is that active discovery
		 * doesn't happen, because nobody answer the discoveries
		 * frame of the other guy, so the log shows up empty.
		 * What should we do ?
		 * Not much. It's too late to answer those discovery frames,
		 * so we just pass the info to IrLMP who will put it in the
		 * log (and post an event).
		 * Another cause would be devices that do discovery much
		 * slower than us, however the latest fixes should minimise
		 * those cases...
		 * Jean II
		 */
			IRDA_DEBUG(1, "%s(), Receiving final discovery request, missed the discovery slots :-(\n", __FUNCTION__);

			/* Last discovery request -> in the log */
			irlap_discovery_indication(self, info->discovery);
		}
		break;
	case MEDIA_BUSY_TIMER_EXPIRED:
		/* A bunch of events may be postponed because the media is
		 * busy (usually immediately after we close a connection),
		 * or while we are doing discovery (state query/reply).
		 * In all those cases, the media busy flag will be cleared
		 * when it's OK for us to process those postponed events.
		 * This event is not mentioned in the state machines in the
		 * IrLAP spec. It's because they didn't consider Ultra and
		 * postponing connection request is optional.
		 * Jean II */