/*
   * Common framework for low-level network console, dump, and debugger code
   *
   * Sep 8 2003  Matt Mackall <mpm@selenic.com>
   *
   * based on the netconsole code from:
   *
   * Copyright (C) 2001  Ingo Molnar <mingo@redhat.com>
   * Copyright (C) 2002  Red Hat, Inc.
   */

  #include <linux/moduleparam.h>

  #include <linux/netdevice.h>
  #include <linux/etherdevice.h>
  #include <linux/string.h>

  #include <linux/if_arp.h>

  #include <linux/inetdevice.h>
  #include <linux/inet.h>
  #include <linux/interrupt.h>
  #include <linux/netpoll.h>
  #include <linux/sched.h>
  #include <linux/delay.h>
  #include <linux/rcupdate.h>
  #include <linux/workqueue.h>

  #include <linux/slab.h>

  #include <linux/export.h>

  #include <net/tcp.h>
  #include <net/udp.h>
  #include <asm/unaligned.h>

  #include <trace/events/napi.h>

  
  /*
   * We maintain a small pool of fully-sized skbs, to make sure the
   * message gets out even in extreme OOM situations.
   */
  
  #define MAX_UDP_CHUNK 1460
  #define MAX_SKBS 32

  static struct sk_buff_head skb_pool;

  
  static atomic_t trapped;

  #define USEC_PER_POLL	50

  #define NETPOLL_RX_ENABLED  1
  #define NETPOLL_RX_DROP     2

  
  #define MAX_SKB_SIZE \
  		(MAX_UDP_CHUNK + sizeof(struct udphdr) + \
  				sizeof(struct iphdr) + sizeof(struct ethhdr))

  static void zap_completion_queue(void);

  static void arp_reply(struct sk_buff *skb);

  static unsigned int carrier_timeout = 4;
  module_param(carrier_timeout, uint, 0644);

  static void queue_process(struct work_struct *work)

  {

  	struct netpoll_info *npinfo =
  		container_of(work, struct netpoll_info, tx_work.work);

  	struct sk_buff *skb;

  	unsigned long flags;

  	while ((skb = skb_dequeue(&npinfo->txq))) {
  		struct net_device *dev = skb->dev;

  		const struct net_device_ops *ops = dev->netdev_ops;

  		struct netdev_queue *txq;

  		if (!netif_device_present(dev) || !netif_running(dev)) {
  			__kfree_skb(skb);
  			continue;
  		}

  		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));

  		local_irq_save(flags);

  		__netif_tx_lock(txq, smp_processor_id());

  		if (netif_xmit_frozen_or_stopped(txq) ||

  		    ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) {

  			skb_queue_head(&npinfo->txq, skb);

  			__netif_tx_unlock(txq);

  			local_irq_restore(flags);

  			schedule_delayed_work(&npinfo->tx_work, HZ/10);

  			return;
  		}

  		__netif_tx_unlock(txq);

  		local_irq_restore(flags);

  	}

  }

  static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
  			    unsigned short ulen, __be32 saddr, __be32 daddr)

  {

  	__wsum psum;

  	if (uh->check == 0 || skb_csum_unnecessary(skb))

  		return 0;

  	psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);

  	if (skb->ip_summed == CHECKSUM_COMPLETE &&

  	    !csum_fold(csum_add(psum, skb->csum)))

  		return 0;

  	skb->csum = psum;

  	return __skb_checksum_complete(skb);

  }
  
  /*
   * Check whether delayed processing was scheduled for our NIC. If so,
   * we attempt to grab the poll lock and use ->poll() to pump the card.
   * If this fails, either we've recursed in ->poll() or it's already
   * running on another CPU.
   *
   * Note: we don't mask interrupts with this lock because we're using
   * trylock here and interrupts are already disabled in the softirq
   * case. Further, we test the poll_owner to avoid recursion on UP
   * systems where the lock doesn't exist.
   *
   * In cases where there is bi-directional communications, reading only
   * one message at a time can lead to packets being dropped by the
   * network adapter, forcing superfluous retries and possibly timeouts.
   * Thus, we set our budget to greater than 1.
   */

  static int poll_one_napi(struct netpoll_info *npinfo,
  			 struct napi_struct *napi, int budget)
  {
  	int work;
  
  	/* net_rx_action's ->poll() invocations and our's are
  	 * synchronized by this test which is only made while
  	 * holding the napi->poll_lock.
  	 */
  	if (!test_bit(NAPI_STATE_SCHED, &napi->state))
  		return budget;

  	npinfo->rx_flags |= NETPOLL_RX_DROP;

  	atomic_inc(&trapped);

  	set_bit(NAPI_STATE_NPSVC, &napi->state);

  
  	work = napi->poll(napi, budget);

  	trace_napi_poll(napi);

  	clear_bit(NAPI_STATE_NPSVC, &napi->state);

  	atomic_dec(&trapped);

  	npinfo->rx_flags &= ~NETPOLL_RX_DROP;

  
  	return budget - work;
  }

  static void poll_napi(struct net_device *dev)

  {

  	struct napi_struct *napi;

  	int budget = 16;

  	list_for_each_entry(napi, &dev->napi_list, dev_list) {

  		if (napi->poll_owner != smp_processor_id() &&

  		    spin_trylock(&napi->poll_lock)) {

  			budget = poll_one_napi(dev->npinfo, napi, budget);

  			spin_unlock(&napi->poll_lock);

  
  			if (!budget)
  				break;

  		}

  	}
  }

  static void service_arp_queue(struct netpoll_info *npi)
  {

  	if (npi) {
  		struct sk_buff *skb;

  		while ((skb = skb_dequeue(&npi->arp_tx)))
  			arp_reply(skb);

  	}

  }

  static void netpoll_poll_dev(struct net_device *dev)

  {

  	const struct net_device_ops *ops;

  	if (!dev || !netif_running(dev))
  		return;
  
  	ops = dev->netdev_ops;
  	if (!ops->ndo_poll_controller)

  		return;
  
  	/* Process pending work on NIC */

  	ops->ndo_poll_controller(dev);

  
  	poll_napi(dev);

  	if (dev->priv_flags & IFF_SLAVE) {
  		if (dev->npinfo) {
  			struct net_device *bond_dev = dev->master;
  			struct sk_buff *skb;
  			while ((skb = skb_dequeue(&dev->npinfo->arp_tx))) {
  				skb->dev = bond_dev;
  				skb_queue_tail(&bond_dev->npinfo->arp_tx, skb);
  			}
  		}
  	}

  	service_arp_queue(dev->npinfo);

  	zap_completion_queue();

  }
  
  static void refill_skbs(void)
  {
  	struct sk_buff *skb;
  	unsigned long flags;

  	spin_lock_irqsave(&skb_pool.lock, flags);
  	while (skb_pool.qlen < MAX_SKBS) {

  		skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
  		if (!skb)
  			break;

  		__skb_queue_tail(&skb_pool, skb);

  	}

  	spin_unlock_irqrestore(&skb_pool.lock, flags);

  }

  static void zap_completion_queue(void)
  {
  	unsigned long flags;
  	struct softnet_data *sd = &get_cpu_var(softnet_data);
  
  	if (sd->completion_queue) {
  		struct sk_buff *clist;
  
  		local_irq_save(flags);
  		clist = sd->completion_queue;
  		sd->completion_queue = NULL;
  		local_irq_restore(flags);
  
  		while (clist != NULL) {
  			struct sk_buff *skb = clist;
  			clist = clist->next;
  			if (skb->destructor) {
  				atomic_inc(&skb->users);
  				dev_kfree_skb_any(skb); /* put this one back */
  			} else {
  				__kfree_skb(skb);
  			}
  		}
  	}
  
  	put_cpu_var(softnet_data);
  }

  static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)

  {

  	int count = 0;
  	struct sk_buff *skb;

  	zap_completion_queue();

  	refill_skbs();

  repeat:

  
  	skb = alloc_skb(len, GFP_ATOMIC);

  	if (!skb)
  		skb = skb_dequeue(&skb_pool);

  
  	if (!skb) {

  		if (++count < 10) {

  			netpoll_poll_dev(np->dev);

  			goto repeat;

  		}

  		return NULL;

  	}
  
  	atomic_set(&skb->users, 1);
  	skb_reserve(skb, reserve);
  	return skb;
  }

  static int netpoll_owner_active(struct net_device *dev)
  {
  	struct napi_struct *napi;
  
  	list_for_each_entry(napi, &dev->napi_list, dev_list) {
  		if (napi->poll_owner == smp_processor_id())
  			return 1;
  	}
  	return 0;
  }

  void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
  			     struct net_device *dev)

  {

  	int status = NETDEV_TX_BUSY;
  	unsigned long tries;

  	const struct net_device_ops *ops = dev->netdev_ops;

  	/* It is up to the caller to keep npinfo alive. */

  	struct netpoll_info *npinfo = np->dev->npinfo;

  	if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
  		__kfree_skb(skb);
  		return;
  	}

  
  	/* don't get messages out of order, and no recursion */

  	if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {

  		struct netdev_queue *txq;

  		unsigned long flags;

  		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));

  		local_irq_save(flags);

  		/* try until next clock tick */
  		for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
  		     tries > 0; --tries) {

  			if (__netif_tx_trylock(txq)) {

  				if (!netif_xmit_stopped(txq)) {

  					status = ops->ndo_start_xmit(skb, dev);

  					if (status == NETDEV_TX_OK)
  						txq_trans_update(txq);
  				}

  				__netif_tx_unlock(txq);

  
  				if (status == NETDEV_TX_OK)
  					break;

  			}

  
  			/* tickle device maybe there is some cleanup */

  			netpoll_poll_dev(np->dev);

  
  			udelay(USEC_PER_POLL);

  		}

  
  		WARN_ONCE(!irqs_disabled(),
  			"netpoll_send_skb(): %s enabled interrupts in poll (%pF)
  ",
  			dev->name, ops->ndo_start_xmit);

  		local_irq_restore(flags);

  	}

  	if (status != NETDEV_TX_OK) {

  		skb_queue_tail(&npinfo->txq, skb);

  		schedule_delayed_work(&npinfo->tx_work,0);

  	}

  }

  EXPORT_SYMBOL(netpoll_send_skb_on_dev);

  
  void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
  {
  	int total_len, eth_len, ip_len, udp_len;
  	struct sk_buff *skb;
  	struct udphdr *udph;
  	struct iphdr *iph;
  	struct ethhdr *eth;
  
  	udp_len = len + sizeof(*udph);
  	ip_len = eth_len = udp_len + sizeof(*iph);
  	total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
  
  	skb = find_skb(np, total_len, total_len - len);
  	if (!skb)
  		return;

  	skb_copy_to_linear_data(skb, msg, len);

  	skb->len += len;

  	skb_push(skb, sizeof(*udph));
  	skb_reset_transport_header(skb);
  	udph = udp_hdr(skb);

  	udph->source = htons(np->local_port);
  	udph->dest = htons(np->remote_port);
  	udph->len = htons(udp_len);
  	udph->check = 0;

  	udph->check = csum_tcpudp_magic(np->local_ip,
  					np->remote_ip,

  					udp_len, IPPROTO_UDP,

  					csum_partial(udph, udp_len, 0));

  	if (udph->check == 0)

  		udph->check = CSUM_MANGLED_0;

  	skb_push(skb, sizeof(*iph));
  	skb_reset_network_header(skb);

  	iph = ip_hdr(skb);

  
  	/* iph->version = 4; iph->ihl = 5; */
  	put_unaligned(0x45, (unsigned char *)iph);
  	iph->tos      = 0;
  	put_unaligned(htons(ip_len), &(iph->tot_len));
  	iph->id       = 0;
  	iph->frag_off = 0;
  	iph->ttl      = 64;
  	iph->protocol = IPPROTO_UDP;
  	iph->check    = 0;

  	put_unaligned(np->local_ip, &(iph->saddr));
  	put_unaligned(np->remote_ip, &(iph->daddr));

  	iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
  
  	eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);

  	skb_reset_mac_header(skb);

  	skb->protocol = eth->h_proto = htons(ETH_P_IP);

  	memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
  	memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);

  
  	skb->dev = np->dev;
  
  	netpoll_send_skb(np, skb);
  }

  EXPORT_SYMBOL(netpoll_send_udp);

  
  static void arp_reply(struct sk_buff *skb)
  {

  	struct netpoll_info *npinfo = skb->dev->npinfo;

  	struct arphdr *arp;
  	unsigned char *arp_ptr;
  	int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;

  	__be32 sip, tip;

  	unsigned char *sha;

  	struct sk_buff *send_skb;

  	struct netpoll *np, *tmp;
  	unsigned long flags;

  	int hlen, tlen;

  	int hits = 0;
  
  	if (list_empty(&npinfo->rx_np))
  		return;
  
  	/* Before checking the packet, we do some early
  	   inspection whether this is interesting at all */
  	spin_lock_irqsave(&npinfo->rx_lock, flags);
  	list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
  		if (np->dev == skb->dev)
  			hits++;
  	}
  	spin_unlock_irqrestore(&npinfo->rx_lock, flags);

  	/* No netpoll struct is using this dev */
  	if (!hits)

  		return;

  
  	/* No arp on this interface */
  	if (skb->dev->flags & IFF_NOARP)
  		return;

  	if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))

  		return;

  	skb_reset_network_header(skb);

  	skb_reset_transport_header(skb);

  	arp = arp_hdr(skb);

  
  	if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
  	     arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
  	    arp->ar_pro != htons(ETH_P_IP) ||
  	    arp->ar_op != htons(ARPOP_REQUEST))
  		return;

  	arp_ptr = (unsigned char *)(arp+1);
  	/* save the location of the src hw addr */
  	sha = arp_ptr;
  	arp_ptr += skb->dev->addr_len;

  	memcpy(&sip, arp_ptr, 4);

  	arp_ptr += 4;

  	/* If we actually cared about dst hw addr,
  	   it would get copied here */

  	arp_ptr += skb->dev->addr_len;

  	memcpy(&tip, arp_ptr, 4);
  
  	/* Should we ignore arp? */

  	if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip))

  		return;

  	size = arp_hdr_len(skb->dev);

  	spin_lock_irqsave(&npinfo->rx_lock, flags);
  	list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
  		if (tip != np->local_ip)
  			continue;

  		hlen = LL_RESERVED_SPACE(np->dev);
  		tlen = np->dev->needed_tailroom;
  		send_skb = find_skb(np, size + hlen + tlen, hlen);

  		if (!send_skb)
  			continue;

  		skb_reset_network_header(send_skb);
  		arp = (struct arphdr *) skb_put(send_skb, size);
  		send_skb->dev = skb->dev;
  		send_skb->protocol = htons(ETH_P_ARP);

  		/* Fill the device header for the ARP frame */
  		if (dev_hard_header(send_skb, skb->dev, ptype,
  				    sha, np->dev->dev_addr,
  				    send_skb->len) < 0) {
  			kfree_skb(send_skb);
  			continue;
  		}

  		/*
  		 * Fill out the arp protocol part.
  		 *
  		 * we only support ethernet device type,
  		 * which (according to RFC 1390) should
  		 * always equal 1 (Ethernet).
  		 */

  		arp->ar_hrd = htons(np->dev->type);
  		arp->ar_pro = htons(ETH_P_IP);
  		arp->ar_hln = np->dev->addr_len;
  		arp->ar_pln = 4;
  		arp->ar_op = htons(type);
  
  		arp_ptr = (unsigned char *)(arp + 1);
  		memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
  		arp_ptr += np->dev->addr_len;
  		memcpy(arp_ptr, &tip, 4);
  		arp_ptr += 4;
  		memcpy(arp_ptr, sha, np->dev->addr_len);
  		arp_ptr += np->dev->addr_len;
  		memcpy(arp_ptr, &sip, 4);
  
  		netpoll_send_skb(np, send_skb);
  
  		/* If there are several rx_hooks for the same address,
  		   we're fine by sending a single reply */
  		break;
  	}
  	spin_unlock_irqrestore(&npinfo->rx_lock, flags);

  }
  
  int __netpoll_rx(struct sk_buff *skb)
  {
  	int proto, len, ulen;

  	int hits = 0;

  	const struct iphdr *iph;

  	struct udphdr *uh;

  	struct netpoll_info *npinfo = skb->dev->npinfo;
  	struct netpoll *np, *tmp;

  	if (list_empty(&npinfo->rx_np))

  		goto out;

  	if (skb->dev->type != ARPHRD_ETHER)
  		goto out;

  	/* check if netpoll clients need ARP */

  	if (skb->protocol == htons(ETH_P_ARP) &&

  	    atomic_read(&trapped)) {

  		skb_queue_tail(&npinfo->arp_tx, skb);

  		return 1;
  	}
  
  	proto = ntohs(eth_hdr(skb)->h_proto);
  	if (proto != ETH_P_IP)
  		goto out;
  	if (skb->pkt_type == PACKET_OTHERHOST)
  		goto out;
  	if (skb_shared(skb))
  		goto out;

  	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
  		goto out;

  	iph = (struct iphdr *)skb->data;

  	if (iph->ihl < 5 || iph->version != 4)
  		goto out;
  	if (!pskb_may_pull(skb, iph->ihl*4))
  		goto out;

  	iph = (struct iphdr *)skb->data;

  	if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
  		goto out;
  
  	len = ntohs(iph->tot_len);
  	if (skb->len < len || len < iph->ihl*4)
  		goto out;

  	/*
  	 * Our transport medium may have padded the buffer out.
  	 * Now We trim to the true length of the frame.
  	 */
  	if (pskb_trim_rcsum(skb, len))
  		goto out;

  	iph = (struct iphdr *)skb->data;

  	if (iph->protocol != IPPROTO_UDP)
  		goto out;
  
  	len -= iph->ihl*4;
  	uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
  	ulen = ntohs(uh->len);
  
  	if (ulen != len)
  		goto out;

  	if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))

  		goto out;

  	list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
  		if (np->local_ip && np->local_ip != iph->daddr)
  			continue;
  		if (np->remote_ip && np->remote_ip != iph->saddr)
  			continue;
  		if (np->local_port && np->local_port != ntohs(uh->dest))
  			continue;
  
  		np->rx_hook(np, ntohs(uh->source),
  			       (char *)(uh+1),
  			       ulen - sizeof(struct udphdr));
  		hits++;
  	}
  
  	if (!hits)
  		goto out;

  
  	kfree_skb(skb);
  	return 1;
  
  out:
  	if (atomic_read(&trapped)) {
  		kfree_skb(skb);
  		return 1;
  	}
  
  	return 0;
  }

  void netpoll_print_options(struct netpoll *np)
  {
  	printk(KERN_INFO "%s: local port %d
  ",
  			 np->name, np->local_port);

  	printk(KERN_INFO "%s: local IP %pI4
  ",
  			 np->name, &np->local_ip);

  	printk(KERN_INFO "%s: interface '%s'
  ",

  			 np->name, np->dev_name);
  	printk(KERN_INFO "%s: remote port %d
  ",
  			 np->name, np->remote_port);

  	printk(KERN_INFO "%s: remote IP %pI4
  ",
  			 np->name, &np->remote_ip);

  	printk(KERN_INFO "%s: remote ethernet address %pM
  ",
  	                 np->name, np->remote_mac);

  }

  EXPORT_SYMBOL(netpoll_print_options);

  int netpoll_parse_options(struct netpoll *np, char *opt)
  {
  	char *cur=opt, *delim;

  	if (*cur != '@') {

  		if ((delim = strchr(cur, '@')) == NULL)
  			goto parse_failed;

  		*delim = 0;
  		np->local_port = simple_strtol(cur, NULL, 10);
  		cur = delim;

  	}
  	cur++;

  	if (*cur != '/') {

  		if ((delim = strchr(cur, '/')) == NULL)
  			goto parse_failed;

  		*delim = 0;

  		np->local_ip = in_aton(cur);

  		cur = delim;

  	}
  	cur++;

  	if (*cur != ',') {

  		/* parse out dev name */
  		if ((delim = strchr(cur, ',')) == NULL)
  			goto parse_failed;

  		*delim = 0;

  		strlcpy(np->dev_name, cur, sizeof(np->dev_name));

  		cur = delim;

  	}
  	cur++;

  	if (*cur != '@') {

  		/* dst port */
  		if ((delim = strchr(cur, '@')) == NULL)
  			goto parse_failed;

  		*delim = 0;

  		if (*cur == ' ' || *cur == '\t')
  			printk(KERN_INFO "%s: warning: whitespace"
  					"is not allowed
  ", np->name);

  		np->remote_port = simple_strtol(cur, NULL, 10);
  		cur = delim;

  	}
  	cur++;

  
  	/* dst ip */
  	if ((delim = strchr(cur, '/')) == NULL)
  		goto parse_failed;

  	*delim = 0;

  	np->remote_ip = in_aton(cur);

  	cur = delim + 1;

  	if (*cur != 0) {

  		/* MAC address */

  		if (!mac_pton(cur, np->remote_mac))

  			goto parse_failed;

  	}

  	netpoll_print_options(np);

  
  	return 0;
  
   parse_failed:

  	printk(KERN_INFO "%s: couldn't parse config at '%s'!
  ",

  	       np->name, cur);
  	return -1;
  }

  EXPORT_SYMBOL(netpoll_parse_options);

  int __netpoll_setup(struct netpoll *np)

  {

  	struct net_device *ndev = np->dev;

  	struct netpoll_info *npinfo;

  	const struct net_device_ops *ops;

  	unsigned long flags;

  	int err;

  	if ((ndev->priv_flags & IFF_DISABLE_NETPOLL) ||
  	    !ndev->netdev_ops->ndo_poll_controller) {
  		printk(KERN_ERR "%s: %s doesn't support polling, aborting.
  ",
  		       np->name, np->dev_name);
  		err = -ENOTSUPP;
  		goto out;
  	}
  
  	if (!ndev->npinfo) {
  		npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
  		if (!npinfo) {
  			err = -ENOMEM;
  			goto out;
  		}
  
  		npinfo->rx_flags = 0;
  		INIT_LIST_HEAD(&npinfo->rx_np);
  
  		spin_lock_init(&npinfo->rx_lock);
  		skb_queue_head_init(&npinfo->arp_tx);
  		skb_queue_head_init(&npinfo->txq);
  		INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
  
  		atomic_set(&npinfo->refcnt, 1);
  
  		ops = np->dev->netdev_ops;
  		if (ops->ndo_netpoll_setup) {
  			err = ops->ndo_netpoll_setup(ndev, npinfo);
  			if (err)
  				goto free_npinfo;
  		}
  	} else {
  		npinfo = ndev->npinfo;
  		atomic_inc(&npinfo->refcnt);
  	}
  
  	npinfo->netpoll = np;
  
  	if (np->rx_hook) {
  		spin_lock_irqsave(&npinfo->rx_lock, flags);
  		npinfo->rx_flags |= NETPOLL_RX_ENABLED;
  		list_add_tail(&np->rx, &npinfo->rx_np);
  		spin_unlock_irqrestore(&npinfo->rx_lock, flags);
  	}
  
  	/* last thing to do is link it to the net device structure */

  	rcu_assign_pointer(ndev->npinfo, npinfo);

  
  	return 0;
  
  free_npinfo:
  	kfree(npinfo);
  out:
  	return err;
  }
  EXPORT_SYMBOL_GPL(__netpoll_setup);
  
  int netpoll_setup(struct netpoll *np)
  {
  	struct net_device *ndev = NULL;
  	struct in_device *in_dev;
  	int err;

  	if (np->dev_name)

  		ndev = dev_get_by_name(&init_net, np->dev_name);

  	if (!ndev) {
  		printk(KERN_ERR "%s: %s doesn't exist, aborting.
  ",
  		       np->name, np->dev_name);

  		return -ENODEV;

  	}

  	if (ndev->master) {
  		printk(KERN_ERR "%s: %s is a slave device, aborting.
  ",
  		       np->name, np->dev_name);

  		err = -EBUSY;
  		goto put;

  	}

  	if (!netif_running(ndev)) {
  		unsigned long atmost, atleast;
  
  		printk(KERN_INFO "%s: device %s not up yet, forcing it
  ",
  		       np->name, np->dev_name);

  		rtnl_lock();

  		err = dev_open(ndev);
  		rtnl_unlock();
  
  		if (err) {

  			printk(KERN_ERR "%s: failed to open %s
  ",

  			       np->name, ndev->name);

  			goto put;

  		}

  
  		atleast = jiffies + HZ/10;

  		atmost = jiffies + carrier_timeout * HZ;

  		while (!netif_carrier_ok(ndev)) {
  			if (time_after(jiffies, atmost)) {
  				printk(KERN_NOTICE
  				       "%s: timeout waiting for carrier
  ",
  				       np->name);
  				break;
  			}

  			msleep(1);

  		}
  
  		/* If carrier appears to come up instantly, we don't
  		 * trust it and pause so that we don't pump all our
  		 * queued console messages into the bitbucket.
  		 */
  
  		if (time_before(jiffies, atleast)) {
  			printk(KERN_NOTICE "%s: carrier detect appears"
  			       " untrustworthy, waiting 4 seconds
  ",
  			       np->name);
  			msleep(4000);
  		}
  	}

  	if (!np->local_ip) {
  		rcu_read_lock();

  		in_dev = __in_dev_get_rcu(ndev);

  
  		if (!in_dev || !in_dev->ifa_list) {
  			rcu_read_unlock();
  			printk(KERN_ERR "%s: no IP address for %s, aborting
  ",
  			       np->name, np->dev_name);

  			err = -EDESTADDRREQ;

  			goto put;

  		}

  		np->local_ip = in_dev->ifa_list->ifa_local;

  		rcu_read_unlock();

  		printk(KERN_INFO "%s: local IP %pI4
  ", np->name, &np->local_ip);

  	}

  	np->dev = ndev;
  
  	/* fill up the skb queue */
  	refill_skbs();
  
  	rtnl_lock();

  	err = __netpoll_setup(np);

  	rtnl_unlock();

  	if (err)
  		goto put;

  	return 0;

  put:

  	dev_put(ndev);

  	return err;

  }

  EXPORT_SYMBOL(netpoll_setup);

  static int __init netpoll_init(void)
  {

  	skb_queue_head_init(&skb_pool);
  	return 0;
  }
  core_initcall(netpoll_init);

  void __netpoll_cleanup(struct netpoll *np)

  {

  	struct netpoll_info *npinfo;
  	unsigned long flags;

  	npinfo = np->dev->npinfo;
  	if (!npinfo)

  		return;

  	if (!list_empty(&npinfo->rx_np)) {
  		spin_lock_irqsave(&npinfo->rx_lock, flags);
  		list_del(&np->rx);
  		if (list_empty(&npinfo->rx_np))
  			npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
  		spin_unlock_irqrestore(&npinfo->rx_lock, flags);
  	}

  	if (atomic_dec_and_test(&npinfo->refcnt)) {
  		const struct net_device_ops *ops;

  		ops = np->dev->netdev_ops;
  		if (ops->ndo_netpoll_cleanup)
  			ops->ndo_netpoll_cleanup(np->dev);

  		RCU_INIT_POINTER(np->dev->npinfo, NULL);

  		/* avoid racing with NAPI reading npinfo */
  		synchronize_rcu_bh();

  		skb_queue_purge(&npinfo->arp_tx);
  		skb_queue_purge(&npinfo->txq);

  		cancel_delayed_work_sync(&npinfo->tx_work);

  		/* clean after last, unfinished work */
  		__skb_queue_purge(&npinfo->txq);
  		kfree(npinfo);

  	}

  }
  EXPORT_SYMBOL_GPL(__netpoll_cleanup);

  void netpoll_cleanup(struct netpoll *np)
  {
  	if (!np->dev)
  		return;

  	rtnl_lock();
  	__netpoll_cleanup(np);
  	rtnl_unlock();
  
  	dev_put(np->dev);

  	np->dev = NULL;
  }

  EXPORT_SYMBOL(netpoll_cleanup);

  
  int netpoll_trap(void)
  {
  	return atomic_read(&trapped);
  }

  EXPORT_SYMBOL(netpoll_trap);

  
  void netpoll_set_trap(int trap)
  {
  	if (trap)
  		atomic_inc(&trapped);
  	else
  		atomic_dec(&trapped);
  }

  EXPORT_SYMBOL(netpoll_set_trap);