af_wanpipe.c

Linux Kernel 2.6.9 for OMAP1710

	wp_sk(sk) = wan_opt;

	/* Use timer to send data to the driver. This will act
         * as a BH handler for sendmsg functions */
	init_timer(&wan_opt->tx_timer);
	wan_opt->tx_timer.data	   = (unsigned long)sk;
	wan_opt->tx_timer.function = wanpipe_delayed_transmit;

	sock_init_data(NULL, sk);
	return sk;
}


/*============================================================
 * wanpipe_sendmsg
 *
 *	This function implements a sendto() system call,
 *      for AF_WANPIPE socket family. 
 *      During socket bind() sk->sk_bound_dev_if is initialized
 *      to a correct network device. This number is used
 *      to find a network device to which the packet should
 *      be passed to.
 *
 *      Each packet is queued into sk->sk_write_queue and 
 *      delayed transmit bottom half handler is marked for 
 *      execution.
 *
 *      A socket must be in WANSOCK_CONNECTED state before
 *      a packet is queued into sk->sk_write_queue.
 *===========================================================*/

static int wanpipe_sendmsg(struct kiocb *iocb, struct socket *sock,
			   struct msghdr *msg, int len)
{
	wanpipe_opt *wp;
	struct sock *sk = sock->sk;
	struct wan_sockaddr_ll *saddr=(struct wan_sockaddr_ll *)msg->msg_name;
	struct sk_buff *skb;
	struct net_device *dev;
	unsigned short proto;
	unsigned char *addr;
	int ifindex, err, reserve = 0;

	
	if (!sk->sk_zapped)
		return -ENETDOWN;

	if (sk->sk_state != WANSOCK_CONNECTED)
		return -ENOTCONN;	

	if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_CMSG_COMPAT)) 
		return(-EINVAL);

	/* it was <=, now one can send
         * zero length packets */
	if (len < sizeof(x25api_hdr_t))
		return -EINVAL;

	wp = wp_sk(sk);

	if (saddr == NULL) {
		ifindex	= sk->sk_bound_dev_if;
		proto	= wp->num;
		addr	= NULL;

	}else{
		if (msg->msg_namelen < sizeof(struct wan_sockaddr_ll)){ 
			return -EINVAL;
		}

		ifindex = sk->sk_bound_dev_if;
		proto	= saddr->sll_protocol;
		addr	= saddr->sll_addr;
	}

	dev = dev_get_by_index(ifindex);
	if (dev == NULL){
		printk(KERN_INFO "wansock: Send failed, dev index: %i\n",ifindex);
		return -ENXIO;
	}
	dev_put(dev);
	
	if (sock->type == SOCK_RAW)
		reserve = dev->hard_header_len;

	if (len > dev->mtu+reserve){
  		return -EMSGSIZE;
	}

	skb = sock_alloc_send_skb(sk, len + LL_RESERVED_SPACE(dev),
				msg->msg_flags & MSG_DONTWAIT, &err);

	if (skb==NULL){
		goto out_unlock;
	}
		
	skb_reserve(skb, LL_RESERVED_SPACE(dev));
	skb->nh.raw = skb->data;

	/* Returns -EFAULT on error */
	err = memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len);
	if (err){
		goto out_free;
	}

	if (dev->hard_header) {
		int res;
		err = -EINVAL;
		res = dev->hard_header(skb, dev, ntohs(proto), addr, NULL, len);
		if (res<0){
			goto out_free;
		}
	}

	skb->protocol = proto;
	skb->dev = dev;
	skb->priority = sk->sk_priority;
	skb->pkt_type = WAN_PACKET_DATA;

	err = -ENETDOWN;
	if (!(dev->flags & IFF_UP))
		goto out_free;

	if (atomic_read(&sk->sk_wmem_alloc) + skb->truesize >
	    (unsigned int)sk->sk_sndbuf){
		kfree_skb(skb);
		return -ENOBUFS;
	}

	skb_queue_tail(&sk->sk_write_queue,skb);
	atomic_inc(&wp->packet_sent);

	if (!(test_and_set_bit(0, &wp->timer)))
		mod_timer(&wp->tx_timer, jiffies + 1);
	
	return(len);

out_free:
	kfree_skb(skb);
out_unlock:
	return err;
}

/*============================================================
 * wanpipe_delayed_tarnsmit
 *
 *	Transmit bottom half handler. It dequeues packets
 *      from sk->sk_write_queue and passes them to the 
 *      driver.  If the driver is busy, the packet is 
 *      re-enqueued.  
 *
 *      Packet Sent counter is decremented on successful
 *      transmission. 
 *===========================================================*/


static void wanpipe_delayed_transmit (unsigned long data)
{
	struct sock *sk=(struct sock *)data;
	struct sk_buff *skb;
	wanpipe_opt *wp = wp_sk(sk);
	struct net_device *dev = wp->dev;
	sdla_t *card = (sdla_t*)wp->card;

	if (!card || !dev){
		clear_bit(0, &wp->timer);
		DBG_PRINTK(KERN_INFO "wansock: Transmit delay, no dev or card\n");
		return;
	}
	
	if (sk->sk_state != WANSOCK_CONNECTED || !sk->sk_zapped) {
		clear_bit(0, &wp->timer);
		DBG_PRINTK(KERN_INFO "wansock: Tx Timer, State not CONNECTED\n");
		return;
	}
	
	/* If driver is executing command, we must offload
         * the board by not sending data. Otherwise a 
         * pending command will never get a free buffer
         * to execute */ 	
	if (atomic_read(&card->u.x.command_busy)){
		wp->tx_timer.expires = jiffies + SLOW_BACKOFF;
		add_timer(&wp->tx_timer);
		DBG_PRINTK(KERN_INFO "wansock: Tx Timer, command bys BACKOFF\n");
		return;
	}

	
	if (test_and_set_bit(0,&wanpipe_tx_critical)){
		printk(KERN_INFO "WanSock: Tx timer critical %s\n",dev->name);
		wp->tx_timer.expires = jiffies + SLOW_BACKOFF;
		add_timer(&wp->tx_timer);
		return;
	}	
	
	/* Check for a packet in the fifo and send */
	if ((skb = skb_dequeue(&sk->sk_write_queue)) != NULL){

		if (dev->hard_start_xmit(skb, dev) != 0){			

			/* Driver failed to transmit, re-enqueue
                         * the packet and retry again later */
			skb_queue_head(&sk->sk_write_queue,skb);
			clear_bit(0,&wanpipe_tx_critical);
			return;
		}else{

			/* Packet Sent successful. Check for more packets
                         * if more packets, re-trigger the transmit routine 
                         * other wise exit
                         */
			atomic_dec(&wp->packet_sent);

			if (skb_peek(&sk->sk_write_queue) == NULL) {
				/* If there is nothing to send, kick
				 * the poll routine, which will trigger
				 * the application to send more data */
				sk->sk_data_ready(sk, 0);
				clear_bit(0, &wp->timer);
			}else{
				/* Reschedule as fast as possible */
				wp->tx_timer.expires = jiffies + 1;
				add_timer(&wp->tx_timer);
			}
		}
	}
	clear_bit(0,&wanpipe_tx_critical);
}

/*============================================================
 * execute_command 
 *
 *	Execute x25api commands.  The atomic variable
 *      chan->command is used to indicate to the driver that
 *      command is pending for execution.  The acutal command
 *      structure is placed into a sock mbox structure 
 *      (wp_sk(sk)->mbox).
 *
 *      The sock private structure, mbox is
 *      used as shared memory between sock and the driver.
 *      Driver uses the sock mbox to execute the command
 *      and return the result.  
 *
 *      For all command except PLACE CALL, the function
 *      waits for the result.  PLACE CALL can be ether
 *      blocking or nonblocking. The user sets this option
 *      via ioctl call.
 *===========================================================*/


static int execute_command(struct sock *sk,  unsigned char cmd, unsigned int flags)
{
	wanpipe_opt *wp = wp_sk(sk);
	struct net_device *dev;
	wanpipe_common_t *chan=NULL;
	int err=0;
	DECLARE_WAITQUEUE(wait, current);
	
	dev = dev_get_by_index(sk->sk_bound_dev_if);
	if (dev == NULL){
		printk(KERN_INFO "wansock: Exec failed no dev %i\n",
			sk->sk_bound_dev_if);
		return -ENODEV;
	}
	dev_put(dev);

	if ((chan=dev->priv) == NULL){
		printk(KERN_INFO "wansock: Exec cmd failed no priv area\n");
		return -ENODEV;
	}

	if (atomic_read(&chan->command)){
		printk(KERN_INFO "wansock: ERROR: Command already running %x, %s\n",
			atomic_read(&chan->command),dev->name);
		return -EINVAL;
	}

	if (!wp->mbox) {
		printk(KERN_INFO "wansock: In execute without MBOX\n");
		return -EINVAL;
	}

	((mbox_cmd_t*)wp->mbox)->cmd.command = cmd;	
	((mbox_cmd_t*)wp->mbox)->cmd.lcn     = wp->lcn;
	((mbox_cmd_t*)wp->mbox)->cmd.result  = 0x7F;


	if (flags & O_NONBLOCK){
		cmd |= 0x80;
		atomic_set(&chan->command, cmd);
	}else{
		atomic_set(&chan->command, cmd);
	}

	add_wait_queue(sk->sk_sleep,&wait);
	current->state = TASK_INTERRUPTIBLE;
	for (;;){
		if (((mbox_cmd_t*)wp->mbox)->cmd.result != 0x7F) {
			err = 0;
			break;
		}
		if (signal_pending(current)) {
			err = -ERESTARTSYS;
			break;
		}
		schedule();
	}
	current->state = TASK_RUNNING;
	remove_wait_queue(sk->sk_sleep,&wait);
	
	return err;
}

/*============================================================
 * wanpipe_destroy_timer 
 *
 *	Used by wanpipe_release, to delay release of
 *      the socket.
 *===========================================================*/

static void wanpipe_destroy_timer(unsigned long data)
{
	struct sock *sk=(struct sock *)data;
	wanpipe_opt *wp = wp_sk(sk);

	if ((!atomic_read(&sk->sk_wmem_alloc) &&
	     !atomic_read(&sk->sk_rmem_alloc)) ||
	    (++wp->force == 5)) {

		if (atomic_read(&sk->sk_wmem_alloc) ||
		    atomic_read(&sk->sk_rmem_alloc))
			printk(KERN_INFO "wansock: Warning, Packet Discarded due to sock shutdown!\n");

		kfree(wp);
		wp_sk(sk) = NULL;
		
		if (atomic_read(&sk->sk_refcnt) != 1) {
			atomic_set(&sk->sk_refcnt, 1);
			DBG_PRINTK(KERN_INFO "wansock: Error, wrong reference count: %i ! :delay.\n",
					atomic_read(&sk->sk_refcnt));
		}
		sock_put(sk);
		atomic_dec(&wanpipe_socks_nr);
		return;
	}

	sk->sk_timer.expires = jiffies + 5 * HZ;
	add_timer(&sk->sk_timer);
	printk(KERN_INFO "wansock: packet sk destroy delayed\n");
}

/*============================================================
 * wanpipe_unlink_driver
 *
 * 	When the socket is released, this function is 
 *      used to remove links that bind the sock and the
 *      driver together.  
 *===========================================================*/
static void wanpipe_unlink_driver (struct sock *sk)
{
	struct net_device *dev;
	wanpipe_common_t *chan=NULL;

	sk->sk_zapped = 0;
	sk->sk_state = WANSOCK_DISCONNECTED;
	wp_sk(sk)->dev = NULL;

	dev = dev_get_by_index(sk->sk_bound_dev_if);
	if (!dev){
		printk(KERN_INFO "wansock: No dev on release\n");
		return;
	}			
	dev_put(dev);

	if ((chan = dev->priv) == NULL){
		printk(KERN_INFO "wansock: No Priv Area on release\n");
		return;
	}

	set_bit(0,&chan->common_critical);
	chan->sk=NULL;
	chan->func=NULL;
	chan->mbox=NULL;
	chan->tx_timer=NULL;
	clear_bit(0,&chan->common_critical);
	release_device(dev);
	
	return;
}

/*============================================================
 * wanpipe_link_driver
 *
 * 	Upon successful bind(), sock is linked to a driver
 *      by binding in the wanpipe_rcv() bottom half handler
 *      to the driver function pointer, as well as sock and
 *      sock mailbox addresses.  This way driver can pass
 *      data up the socket.
 *===========================================================*/

static void wanpipe_link_driver(struct net_device *dev, struct sock *sk)
{
	wanpipe_opt *wp = wp_sk(sk);
	wanpipe_common_t *chan = dev->priv;
	if (!chan)
		return;
	set_bit(0,&chan->common_critical);
	chan->sk=sk;
	chan->func=wanpipe_rcv;
	chan->mbox = wp->mbox;
	chan->tx_timer = &wp->tx_timer;
	wp->dev = dev;
	sk->sk_zapped = 1;
	clear_bit(0,&chan->common_critical);
}


/*============================================================
 * release_device
 *
 *   	During sock release, clear a critical bit, which 
 *      marks the device a being taken.
 *===========================================================*/


static void release_device(struct net_device *dev)
{
	wanpipe_common_t *chan=dev->priv;
	clear_bit(0,(void*)&chan->rw_bind);
}

/*============================================================
 * wanpipe_release
 *
 *	Close a PACKET socket. This is fairly simple. We 
 *      immediately go to 'closed' state and remove our 
 *      protocol entry in the device list.
 *===========================================================*/

static int wanpipe_release(struct socket *sock)
{
	wanpipe_opt *wp;
	struct sock *sk = sock->sk;
	
	if (!sk)
		return 0;

	wp = wp_sk(sk);
	check_write_queue(sk);

	/* Kill the tx timer, if we don't kill it now, the timer
         * will run after we kill the sock.  Timer code will 
         * try to access the sock which has been killed and cause
         * kernel panic */

	del_timer(&wp->tx_timer);

	/*
	 *	Unhook packet receive handler.
	 */

	if (wp->num == htons(X25_PROT) &&
	    sk->sk_state != WANSOCK_DISCONNECTED && sk->sk_zapped) {
		struct net_device *dev = dev_get_by_index(sk->sk_bound_dev_if);
		wanpipe_common_t *chan;
		if (dev){
			chan=dev->priv;
			atomic_set(&chan->disconnect,1);
			DBG_PRINTK(KERN_INFO "wansock: Sending Clear Indication %i\n",
					sk->sk_state);
			dev_put(dev);
		}	
	}

	set_bit(1,&wanpipe_tx_critical);
	write_lock(&wanpipe_sklist_lock);
	sk_del_node_init(sk);
	write_unlock(&wanpipe_sklist_lock);
	clear_bit(1,&wanpipe_tx_critical);


	
	release_driver(sk);

	
	/*
	 *	Now the socket is dead. No more input will appear.
	 */

	sk->sk_state_change(sk);	/* It is useless. Just for sanity. */

	sock->sk = NULL;
	sk->sk_socket = NULL;
	sock_set_flag(sk, SOCK_DEAD);

	/* Purge queues */
	skb_queue_purge(&sk->sk_receive_queue);
	skb_queue_purge(&sk->sk_write_queue);
	skb_queue_purge(&sk->sk_error_queue);

	if (atomic_read(&sk->sk_rmem_alloc) ||
	    atomic_read(&sk->sk_wmem_alloc)) {
		del_timer(&sk->sk_timer);
		printk(KERN_INFO "wansock: Killing in Timer R %i , W %i\n",