C++ skb_clone函数代码示例

/*
 *	Process Router Attention IP option (RFC 2113)
 */
bool ip_call_ra_chain(struct sk_buff *skb)
{
	struct ip_ra_chain *ra;
	u8 protocol = ip_hdr(skb)->protocol;
	struct sock *last = NULL;
	struct net_device *dev = skb->dev;

	for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
		struct sock *sk = ra->sk;

		/* If socket is bound to an interface, only report
		 * the packet if it came  from that interface.
		 */
		if (sk && inet_sk(sk)->inet_num == protocol &&
		    (!sk->sk_bound_dev_if ||
		     sk->sk_bound_dev_if == dev->ifindex) &&
		    net_eq(sock_net(sk), dev_net(dev))) {
			if (ip_is_fragment(ip_hdr(skb))) {
				if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
					return true;
			}
			if (last) {
				struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
				if (skb2)
					raw_rcv(last, skb2);
			}
			last = sk;
		}
	}

	if (last) {
		raw_rcv(last, skb);
		return true;
	}
	return false;
}

/*
 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
 * any circumstances.
 */
void dccp_send_close(struct sock *sk, const int active)
{
	struct dccp_sock *dp = dccp_sk(sk);
	struct sk_buff *skb;
	const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;

	skb = alloc_skb(sk->sk_prot->max_header, prio);
	if (skb == NULL)
		return;

	/* Reserve space for headers and prepare control bits. */
	skb_reserve(skb, sk->sk_prot->max_header);
	if (dp->dccps_role == DCCP_ROLE_SERVER && !dp->dccps_server_timewait)
		DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSEREQ;
	else
		DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSE;

	if (active) {
		dccp_write_xmit(sk, 1);
		dccp_skb_entail(sk, skb);
		dccp_transmit_skb(sk, skb_clone(skb, prio));
		/*
		 * Retransmission timer for active-close: RFC 4340, 8.3 requires
		 * to retransmit the Close/CloseReq until the CLOSING/CLOSEREQ
		 * state can be left. The initial timeout is 2 RTTs.
		 * Since RTT measurement is done by the CCIDs, there is no easy
		 * way to get an RTT sample. The fallback RTT from RFC 4340, 3.4
		 * is too low (200ms); we use a high value to avoid unnecessary
		 * retransmissions when the link RTT is > 0.2 seconds.
		 * FIXME: Let main module sample RTTs and use that instead.
		 */
		inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
					  DCCP_TIMEOUT_INIT, DCCP_RTO_MAX);
	} else
		dccp_transmit_skb(sk, skb);
}

PNDIS_PACKET DuplicatePacket(
	IN	PRTMP_ADAPTER	pAd,
	IN	PNDIS_PACKET	pPacket,
	IN	UCHAR			FromWhichBSSID)
{
	struct sk_buff	*skb;
	PNDIS_PACKET	pRetPacket = NULL;
	USHORT			DataSize;
	UCHAR			*pData;

	DataSize = (USHORT) GET_OS_PKT_LEN(pPacket);
	pData = (PUCHAR) GET_OS_PKT_DATAPTR(pPacket);


	skb = skb_clone(RTPKT_TO_OSPKT(pPacket), MEM_ALLOC_FLAG);
	if (skb)
	{
		skb->dev = get_netdev_from_bssid(pAd, FromWhichBSSID);
		pRetPacket = OSPKT_TO_RTPKT(skb);
	}

	return pRetPacket;

}

static int ip6_output2(struct sk_buff *skb)
{
	struct dst_entry *dst = skb->dst;
	struct net_device *dev = dst->dev;

	skb->protocol = htons(ETH_P_IPV6);
	skb->dev = dev;

	if (ipv6_addr_is_multicast(&skb->nh.ipv6h->daddr)) {
		struct ipv6_pinfo* np = skb->sk ? inet6_sk(skb->sk) : NULL;

		if (!(dev->flags & IFF_LOOPBACK) && (!np || np->mc_loop) &&
		    ipv6_chk_mcast_addr(dev, &skb->nh.ipv6h->daddr,
				&skb->nh.ipv6h->saddr)) {
			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);

			/* Do not check for IFF_ALLMULTI; multicast routing
			   is not supported in any case.
			 */
			if (newskb)
				NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, newskb, NULL,
					newskb->dev,
					ip6_dev_loopback_xmit);

			if (skb->nh.ipv6h->hop_limit == 0) {
				IP6_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
				kfree_skb(skb);
				return 0;
			}
		}

		IP6_INC_STATS(IPSTATS_MIB_OUTMCASTPKTS);
	}

	return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb,NULL, skb->dev,ip6_output_finish);
}

static int rose_rebuild_header(struct sk_buff *skb)
{
#ifdef CONFIG_INET
	struct net_device *dev = skb->dev;
	struct net_device_stats *stats = &dev->stats;
	unsigned char *bp = (unsigned char *)skb->data;
	struct sk_buff *skbn;
	unsigned int len;

	if (arp_find(bp + 7, skb)) {
		return 1;
	}

	if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
		kfree_skb(skb);
		return 1;
	}

	if (skb->sk != NULL)
		skb_set_owner_w(skbn, skb->sk);

	kfree_skb(skb);

	len = skbn->len;

	if (!rose_route_frame(skbn, NULL)) {
		kfree_skb(skbn);
		stats->tx_errors++;
		return 1;
	}

	stats->tx_packets++;
	stats->tx_bytes += len;
#endif
	return 1;
}

void nr_send_nak_frame(struct sock *sk)
{
	struct sk_buff *skb, *skbn;
	struct nr_sock *nr = nr_sk(sk);

	if ((skb = skb_peek(&nr->ack_queue)) == NULL)
		return;

	if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL)
		return;

	skbn->data[2] = nr->va;
	skbn->data[3] = nr->vr;

	if (nr->condition & NR_COND_OWN_RX_BUSY)
		skbn->data[4] |= NR_CHOKE_FLAG;

	nr_transmit_buffer(sk, skbn);

	nr->condition &= ~NR_COND_ACK_PENDING;
	nr->vl         = nr->vr;

	nr_stop_t1timer(sk);
}

static int ip6_finish_output2(struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);
	struct net_device *dev = dst->dev;
	struct neighbour *neigh;
	int res;

	skb->protocol = htons(ETH_P_IPV6);
	skb->dev = dev;

	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));

		if (!(dev->flags & IFF_LOOPBACK) && sk_mc_loop(skb->sk) &&
		    ((mroute6_socket(dev_net(dev), skb) &&
		     !(IP6CB(skb)->flags & IP6SKB_FORWARDED)) ||
		     ipv6_chk_mcast_addr(dev, &ipv6_hdr(skb)->daddr,
					 &ipv6_hdr(skb)->saddr))) {
			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);

			/* Do not check for IFF_ALLMULTI; multicast routing
			   is not supported in any case.
			 */
			if (newskb)
				NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING,
					newskb, NULL, newskb->dev,
					ip6_dev_loopback_xmit);

			if (ipv6_hdr(skb)->hop_limit == 0) {
				IP6_INC_STATS(dev_net(dev), idev,
					      IPSTATS_MIB_OUTDISCARDS);
				kfree_skb(skb);
				return 0;
			}
		}

		IP6_UPD_PO_STATS(dev_net(dev), idev, IPSTATS_MIB_OUTMCAST,
				skb->len);
	}

	rcu_read_lock();
	if (dst->hh) {
		res = neigh_hh_output(dst->hh, skb);

		rcu_read_unlock();
		return res;
	} else {
		neigh = dst_get_neighbour(dst);
		if (neigh) {
			res = neigh->output(skb);

			rcu_read_unlock();
			return res;
		}
		rcu_read_unlock();
	}

	IP6_INC_STATS_BH(dev_net(dst->dev),
			 ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
	kfree_skb(skb);
	return -EINVAL;
}

void ax25_kick(ax25_cb *ax25)
{
    struct sk_buff *skb, *skbn;
    int last = 1;
    unsigned short start, end, next;

    if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
        return;

    if (ax25->condition & AX25_COND_PEER_RX_BUSY)
        return;

    if (skb_peek(&ax25->write_queue) == NULL)
        return;

    start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
    end   = (ax25->va + ax25->window) % ax25->modulus;

    if (start == end)
        return;

    /*
     * Transmit data until either we're out of data to send or
     * the window is full. Send a poll on the final I frame if
     * the window is filled.
     */

    /*
     * Dequeue the frame and copy it.
     * Check for race with ax25_clear_queues().
     */
    skb  = skb_dequeue(&ax25->write_queue);
    if (!skb)
        return;

    ax25->vs = start;

    do {
        if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
            skb_queue_head(&ax25->write_queue, skb);
            break;
        }

        if (skb->sk != NULL)
            skb_set_owner_w(skbn, skb->sk);

        next = (ax25->vs + 1) % ax25->modulus;
        last = (next == end);

        /*
         * Transmit the frame copy.
         * bke 960114: do not set the Poll bit on the last frame
         * in DAMA mode.
         */
        switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
        case AX25_PROTO_STD_SIMPLEX:
        case AX25_PROTO_STD_DUPLEX:
            ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
            break;

#ifdef CONFIG_AX25_DAMA_SLAVE
        case AX25_PROTO_DAMA_SLAVE:
            ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
            break;
#endif
        }

        ax25->vs = next;

        /*
         * Requeue the original data frame.
         */
        skb_queue_tail(&ax25->ack_queue, skb);

    } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);

    ax25->condition &= ~AX25_COND_ACK_PENDING;

    if (!ax25_t1timer_running(ax25)) {
        ax25_stop_t3timer(ax25);
        ax25_calculate_t1(ax25);
        ax25_start_t1timer(ax25);
    }
}

int rtw_recv_indicatepkt(struct adapter *padapter,
			 struct recv_frame *precv_frame)
{
	struct recv_priv *precvpriv;
	struct __queue *pfree_recv_queue;
	struct sk_buff *skb;
	struct mlme_priv *pmlmepriv = &padapter->mlmepriv;


	precvpriv = &(padapter->recvpriv);
	pfree_recv_queue = &(precvpriv->free_recv_queue);

	skb = precv_frame->pkt;
	if (!skb) {
		RT_TRACE(_module_recv_osdep_c_, _drv_err_,
			 ("rtw_recv_indicatepkt():skb == NULL something wrong!!!!\n"));
		goto _recv_indicatepkt_drop;
	}

	RT_TRACE(_module_recv_osdep_c_, _drv_info_,
		 ("rtw_recv_indicatepkt():skb != NULL !!!\n"));
	RT_TRACE(_module_recv_osdep_c_, _drv_info_,
		 ("rtw_recv_indicatepkt():precv_frame->rx_head =%p  precv_frame->hdr.rx_data =%p\n",
		 precv_frame->rx_head, precv_frame->rx_data));
	RT_TRACE(_module_recv_osdep_c_, _drv_info_,
		 ("precv_frame->hdr.rx_tail =%p precv_frame->rx_end =%p precv_frame->hdr.len =%d\n",
		 precv_frame->rx_tail, precv_frame->rx_end,
		 precv_frame->len));

	skb->data = precv_frame->rx_data;

	skb_set_tail_pointer(skb, precv_frame->len);

	skb->len = precv_frame->len;

	RT_TRACE(_module_recv_osdep_c_, _drv_info_,
		 ("skb->head =%p skb->data =%p skb->tail =%p skb->end =%p skb->len =%d\n",
		 skb->head, skb->data, skb_tail_pointer(skb),
		 skb_end_pointer(skb), skb->len));

	if (check_fwstate(pmlmepriv, WIFI_AP_STATE)) {
		struct sk_buff *pskb2 = NULL;
		struct sta_info *psta = NULL;
		struct sta_priv *pstapriv = &padapter->stapriv;
		struct rx_pkt_attrib *pattrib = &precv_frame->attrib;
		int bmcast = IS_MCAST(pattrib->dst);

		if (memcmp(pattrib->dst, myid(&padapter->eeprompriv),
			   ETH_ALEN)) {
			if (bmcast) {
				psta = rtw_get_bcmc_stainfo(padapter);
				pskb2 = skb_clone(skb, GFP_ATOMIC);
			} else {
				psta = rtw_get_stainfo(pstapriv, pattrib->dst);
			}

			if (psta) {
				struct net_device *pnetdev;

				pnetdev = (struct net_device *)padapter->pnetdev;
				skb->dev = pnetdev;
				skb_set_queue_mapping(skb, rtw_recv_select_queue(skb));

				rtw_xmit_entry(skb, pnetdev);

				if (bmcast)
					skb = pskb2;
				else
					goto _recv_indicatepkt_end;
			}
		}
	}

	rcu_read_lock();
	rcu_dereference(padapter->pnetdev->rx_handler_data);
	rcu_read_unlock();

	skb->ip_summed = CHECKSUM_NONE;
	skb->dev = padapter->pnetdev;
	skb->protocol = eth_type_trans(skb, padapter->pnetdev);

	netif_rx(skb);

_recv_indicatepkt_end:

	/*  pointers to NULL before rtw_free_recvframe() */
	precv_frame->pkt = NULL;

	rtw_free_recvframe(precv_frame, pfree_recv_queue);

	RT_TRACE(_module_recv_osdep_c_, _drv_info_,
		 ("\n rtw_recv_indicatepkt :after netif_rx!!!!\n"));


	return _SUCCESS;

_recv_indicatepkt_drop:

	 /* enqueue back to free_recv_queue */
	rtw_free_recvframe(precv_frame, pfree_recv_queue);
//.........这里部分代码省略.........

static int pep_connreq_rcv(struct sock *sk, struct sk_buff *skb)
{
	struct sock *newsk;
	struct pep_sock *newpn, *pn = pep_sk(sk);
	struct pnpipehdr *hdr;
	struct sockaddr_pn dst;
	u16 peer_type;
	u8 pipe_handle, enabled, n_sb;
	u8 aligned = 0;

	if (!pskb_pull(skb, sizeof(*hdr) + 4))
		return -EINVAL;

	hdr = pnp_hdr(skb);
	pipe_handle = hdr->pipe_handle;
	switch (hdr->state_after_connect) {
	case PN_PIPE_DISABLE:
		enabled = 0;
		break;
	case PN_PIPE_ENABLE:
		enabled = 1;
		break;
	default:
		pep_reject_conn(sk, skb, PN_PIPE_ERR_INVALID_PARAM);
		return -EINVAL;
	}
	peer_type = hdr->other_pep_type << 8;

	if (unlikely(sk->sk_state != TCP_LISTEN) || sk_acceptq_is_full(sk)) {
		pep_reject_conn(sk, skb, PN_PIPE_ERR_PEP_IN_USE);
		return -ENOBUFS;
	}

	/* Parse sub-blocks (options) */
	n_sb = hdr->data[4];
	while (n_sb > 0) {
		u8 type, buf[1], len = sizeof(buf);
		const u8 *data = pep_get_sb(skb, &type, &len, buf);

		if (data == NULL)
			return -EINVAL;
		switch (type) {
		case PN_PIPE_SB_CONNECT_REQ_PEP_SUB_TYPE:
			if (len < 1)
				return -EINVAL;
			peer_type = (peer_type & 0xff00) | data[0];
			break;
		case PN_PIPE_SB_ALIGNED_DATA:
			aligned = data[0] != 0;
			break;
		}
		n_sb--;
	}

	skb = skb_clone(skb, GFP_ATOMIC);
	if (!skb)
		return -ENOMEM;

	/* Create a new to-be-accepted sock */
	newsk = sk_alloc(sock_net(sk), PF_PHONET, GFP_ATOMIC, sk->sk_prot);
	if (!newsk) {
		kfree_skb(skb);
		return -ENOMEM;
	}
	sock_init_data(NULL, newsk);
	newsk->sk_state = TCP_SYN_RECV;
	newsk->sk_backlog_rcv = pipe_do_rcv;
	newsk->sk_protocol = sk->sk_protocol;
	newsk->sk_destruct = pipe_destruct;

	newpn = pep_sk(newsk);
	pn_skb_get_dst_sockaddr(skb, &dst);
	newpn->pn_sk.sobject = pn_sockaddr_get_object(&dst);
	newpn->pn_sk.resource = pn->pn_sk.resource;
	skb_queue_head_init(&newpn->ctrlreq_queue);
	newpn->pipe_handle = pipe_handle;
	atomic_set(&newpn->tx_credits, 0);
	newpn->peer_type = peer_type;
	newpn->rx_credits = 0;
	newpn->rx_fc = newpn->tx_fc = PN_LEGACY_FLOW_CONTROL;
	newpn->init_enable = enabled;
	newpn->aligned = aligned;

	BUG_ON(!skb_queue_empty(&newsk->sk_receive_queue));
	skb_queue_head(&newsk->sk_receive_queue, skb);
	if (!sock_flag(sk, SOCK_DEAD))
		sk->sk_data_ready(sk, 0);

	sk_acceptq_added(sk);
	sk_add_node(newsk, &pn->ackq);
	return 0;
}

//.........这里部分代码省略.........
		 *	Make sure we haven't missed an interrupt. 
		 */
		printk("dev_queue_xmit: worked around a missed interrupt\n");
		start_bh_atomic();
		dev->hard_start_xmit(NULL, dev);
		end_bh_atomic();
		return;
  	}

	/*
	 *	Negative priority is used to flag a frame that is being pulled from the
	 *	queue front as a retransmit attempt. It therefore goes back on the queue
	 *	start on a failure.
	 */
	 
  	if (pri < 0) 
  	{
		pri = -pri-1;
		where = 1;
  	}

	if (pri >= DEV_NUMBUFFS) 
	{
		printk("bad priority in dev_queue_xmit.\n");
		pri = 1;
	}

	/*
	 *	If the address has not been resolved. Call the device header rebuilder.
	 *	This can cover all protocols and technically not just ARP either.
	 */
	 
	if (!skb->arp && dev->rebuild_header(skb->data, dev, skb->raddr, skb)) {
		return;
	}

	save_flags(flags);
	cli();	
	if (!where) {
#ifdef CONFIG_SLAVE_BALANCING	
		skb->in_dev_queue=1;
#endif		
		skb_queue_tail(dev->buffs + pri,skb);
		skb_device_unlock(skb);		/* Buffer is on the device queue and can be freed safely */
		skb = skb_dequeue(dev->buffs + pri);
		skb_device_lock(skb);		/* New buffer needs locking down */
#ifdef CONFIG_SLAVE_BALANCING		
		skb->in_dev_queue=0;
#endif		
	}
	restore_flags(flags);

	/* copy outgoing packets to any sniffer packet handlers */
	if(!where)
	{
		for (nitcount= dev_nit, ptype = ptype_base; nitcount > 0 && ptype != NULL; ptype = ptype->next) 
		{
			/* Never send packets back to the socket
			 * they originated from - MvS ([email protected])
			 */
			if (ptype->type == htons(ETH_P_ALL) &&
			   (ptype->dev == dev || !ptype->dev) &&
			   ((struct sock *)ptype->data != skb->sk))
			{
				struct sk_buff *skb2;
				if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL)
					break;
				/*
				 *	The protocol knows this has (for other paths) been taken off
				 *	and adds it back.
				 */
				skb2->len-=skb->dev->hard_header_len;
				ptype->func(skb2, skb->dev, ptype);
				nitcount--;
			}
		}
	}
	start_bh_atomic();
	if (dev->hard_start_xmit(skb, dev) == 0) {
		end_bh_atomic();
		/*
		 *	Packet is now solely the responsibility of the driver
		 */
		return;
	}
	end_bh_atomic();

	/*
	 *	Transmission failed, put skb back into a list. Once on the list it's safe and
	 *	no longer device locked (it can be freed safely from the device queue)
	 */
	cli();
#ifdef CONFIG_SLAVE_BALANCING
	skb->in_dev_queue=1;
	dev->pkt_queue++;
#endif		
	skb_device_unlock(skb);
	skb_queue_head(dev->buffs + pri,skb);
	restore_flags(flags);
}

static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);
	struct net_device *dev = dst->dev;
	struct neighbour *neigh;
	struct in6_addr *nexthop;
	int ret;

	skb->protocol = htons(ETH_P_IPV6);
	skb->dev = dev;

	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));

		if (!(dev->flags & IFF_LOOPBACK) && sk_mc_loop(sk) &&
		    ((mroute6_socket(net, skb) &&
		     !(IP6CB(skb)->flags & IP6SKB_FORWARDED)) ||
		     ipv6_chk_mcast_addr(dev, &ipv6_hdr(skb)->daddr,
					 &ipv6_hdr(skb)->saddr))) {
			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);

			/* Do not check for IFF_ALLMULTI; multicast routing
			   is not supported in any case.
			 */
			if (newskb)
				NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING,
					net, sk, newskb, NULL, newskb->dev,
					dev_loopback_xmit);

			if (ipv6_hdr(skb)->hop_limit == 0) {
				IP6_INC_STATS(net, idev,
					      IPSTATS_MIB_OUTDISCARDS);
				kfree_skb(skb);
				return 0;
			}
		}

		IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUTMCAST, skb->len);

		if (IPV6_ADDR_MC_SCOPE(&ipv6_hdr(skb)->daddr) <=
		    IPV6_ADDR_SCOPE_NODELOCAL &&
		    !(dev->flags & IFF_LOOPBACK)) {
			kfree_skb(skb);
			return 0;
		}
	}

	rcu_read_lock_bh();
	nexthop = rt6_nexthop((struct rt6_info *)dst, &ipv6_hdr(skb)->daddr);
	neigh = __ipv6_neigh_lookup_noref(dst->dev, nexthop);
	if (unlikely(!neigh))
		neigh = __neigh_create(&nd_tbl, nexthop, dst->dev, false);
	if (!IS_ERR(neigh)) {
		ret = dst_neigh_output(dst, neigh, skb);
		rcu_read_unlock_bh();
		return ret;
	}
	rcu_read_unlock_bh();

	IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
	kfree_skb(skb);
	return -EINVAL;
}

/*	Check if this packet is complete.
 *	Returns NULL on failure by any reason, and pointer
 *	to current nexthdr field in reassembled frame.
 *
 *	It is called with locked fq, and caller must check that
 *	queue is eligible for reassembly i.e. it is not COMPLETE,
 *	the last and the first frames arrived and all the bits are here.
 */
static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *prev,
			     struct net_device *dev)
{
	struct sk_buff *fp, *head = fq->q.fragments;
	int sum_truesize;

	inet_frag_kill(&fq->q, &lowpan_frags);

	/* Make the one we just received the head. */
	if (prev) {
		head = prev->next;
		fp = skb_clone(head, GFP_ATOMIC);

		if (!fp)
			goto out_oom;

		fp->next = head->next;
		if (!fp->next)
			fq->q.fragments_tail = fp;
		prev->next = fp;

		skb_morph(head, fq->q.fragments);
		head->next = fq->q.fragments->next;

		consume_skb(fq->q.fragments);
		fq->q.fragments = head;
	}

	/* Head of list must not be cloned. */
	if (skb_unclone(head, GFP_ATOMIC))
		goto out_oom;

	/* If the first fragment is fragmented itself, we split
	 * it to two chunks: the first with data and paged part
	 * and the second, holding only fragments.
	 */
	if (skb_has_frag_list(head)) {
		struct sk_buff *clone;
		int i, plen = 0;

		clone = alloc_skb(0, GFP_ATOMIC);
		if (!clone)
			goto out_oom;
		clone->next = head->next;
		head->next = clone;
		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
		skb_frag_list_init(head);
		for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
			plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
		clone->len = head->data_len - plen;
		clone->data_len = clone->len;
		head->data_len -= clone->len;
		head->len -= clone->len;
		add_frag_mem_limit(&fq->q, clone->truesize);
	}

	WARN_ON(head == NULL);

	sum_truesize = head->truesize;
	for (fp = head->next; fp;) {
		bool headstolen;
		int delta;
		struct sk_buff *next = fp->next;

		sum_truesize += fp->truesize;
		if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
			kfree_skb_partial(fp, headstolen);
		} else {
			if (!skb_shinfo(head)->frag_list)
				skb_shinfo(head)->frag_list = fp;
			head->data_len += fp->len;
			head->len += fp->len;
			head->truesize += fp->truesize;
		}
		fp = next;
	}
	sub_frag_mem_limit(&fq->q, sum_truesize);

	head->next = NULL;
	head->dev = dev;
	head->tstamp = fq->q.stamp;

	fq->q.fragments = NULL;
	fq->q.fragments_tail = NULL;

	return 1;
out_oom:
	net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
	return -1;
}

static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
			 struct net_device *dev)
{
	struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
	struct iphdr *iph;
	struct sk_buff *fp, *head = qp->q.fragments;
	int len;
	int ihlen;
	int err;
	u8 ecn;

	ipq_kill(qp);

	ecn = ip_frag_ecn_table[qp->ecn];
	if (unlikely(ecn == 0xff)) {
		err = -EINVAL;
		goto out_fail;
	}
	/* Make the one we just received the head. */
	if (prev) {
		head = prev->next;
		fp = skb_clone(head, GFP_ATOMIC);
		if (!fp)
			goto out_nomem;

		fp->next = head->next;
		if (!fp->next)
			qp->q.fragments_tail = fp;
		prev->next = fp;

		skb_morph(head, qp->q.fragments);
		head->next = qp->q.fragments->next;

		consume_skb(qp->q.fragments);
		qp->q.fragments = head;
	}

	WARN_ON(!head);
	WARN_ON(FRAG_CB(head)->offset != 0);

	/* Allocate a new buffer for the datagram. */
	ihlen = ip_hdrlen(head);
	len = ihlen + qp->q.len;

	err = -E2BIG;
	if (len > 65535)
		goto out_oversize;

	/* Head of list must not be cloned. */
	if (skb_unclone(head, GFP_ATOMIC))
		goto out_nomem;

	/* If the first fragment is fragmented itself, we split
	 * it to two chunks: the first with data and paged part
	 * and the second, holding only fragments. */
	if (skb_has_frag_list(head)) {
		struct sk_buff *clone;
		int i, plen = 0;

		clone = alloc_skb(0, GFP_ATOMIC);
		if (!clone)
			goto out_nomem;
		clone->next = head->next;
		head->next = clone;
		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
		skb_frag_list_init(head);
		for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
			plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
		clone->len = clone->data_len = head->data_len - plen;
		head->data_len -= clone->len;
		head->len -= clone->len;
		clone->csum = 0;
		clone->ip_summed = head->ip_summed;
		add_frag_mem_limit(qp->q.net, clone->truesize);
	}

	skb_shinfo(head)->frag_list = head->next;
	skb_push(head, head->data - skb_network_header(head));

	for (fp=head->next; fp; fp = fp->next) {
		head->data_len += fp->len;
		head->len += fp->len;
		if (head->ip_summed != fp->ip_summed)
			head->ip_summed = CHECKSUM_NONE;
		else if (head->ip_summed == CHECKSUM_COMPLETE)
			head->csum = csum_add(head->csum, fp->csum);
		head->truesize += fp->truesize;
	}
	sub_frag_mem_limit(qp->q.net, head->truesize);

	head->next = NULL;
	head->dev = dev;
	head->tstamp = qp->q.stamp;
	IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size);

	iph = ip_hdr(head);
	iph->tot_len = htons(len);
	iph->tos |= ecn;

	/* When we set IP_DF on a refragmented skb we must also force a
//.........这里部分代码省略.........

static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
			 struct net_device *dev)
{
	struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
	struct iphdr *iph;
	struct sk_buff *fp, *head = qp->q.fragments;
	int len;
	int ihlen;
	int err;
	int sum_truesize;
	u8 ecn;

	ipq_kill(qp);

	ecn = ip_frag_ecn_table[qp->ecn];
	if (unlikely(ecn == 0xff)) {
		err = -EINVAL;
		goto out_fail;
	}
	/* Make the one we just received the head. */
	if (prev) {
		head = prev->next;
		fp = skb_clone(head, GFP_ATOMIC);
		if (!fp)
			goto out_nomem;

		fp->next = head->next;
		if (!fp->next)
			qp->q.fragments_tail = fp;
		prev->next = fp;

		skb_morph(head, qp->q.fragments);
		head->next = qp->q.fragments->next;

		consume_skb(qp->q.fragments);
		qp->q.fragments = head;
	}

	WARN_ON(head == NULL);
	WARN_ON(FRAG_CB(head)->offset != 0);

	/* Allocate a new buffer for the datagram. */
	ihlen = ip_hdrlen(head);
	len = ihlen + qp->q.len;

	err = -E2BIG;
	if (len > 65535)
		goto out_oversize;

	/* Head of list must not be cloned. */
	if (skb_unclone(head, GFP_ATOMIC))
		goto out_nomem;

	/* If the first fragment is fragmented itself, we split
	 * it to two chunks: the first with data and paged part
	 * and the second, holding only fragments. */
	if (skb_has_frag_list(head)) {
		struct sk_buff *clone;
		int i, plen = 0;

		if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
			goto out_nomem;
		clone->next = head->next;
		head->next = clone;
		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
		skb_frag_list_init(head);
		for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
			plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
		clone->len = clone->data_len = head->data_len - plen;
		head->data_len -= clone->len;
		head->len -= clone->len;
		clone->csum = 0;
		clone->ip_summed = head->ip_summed;
		add_frag_mem_limit(&qp->q, clone->truesize);
	}

	skb_push(head, head->data - skb_network_header(head));

	sum_truesize = head->truesize;
	for (fp = head->next; fp;) {
		bool headstolen;
		int delta;
		struct sk_buff *next = fp->next;

		sum_truesize += fp->truesize;
		if (head->ip_summed != fp->ip_summed)
			head->ip_summed = CHECKSUM_NONE;
		else if (head->ip_summed == CHECKSUM_COMPLETE)
			head->csum = csum_add(head->csum, fp->csum);

		if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
			kfree_skb_partial(fp, headstolen);
		} else {
			if (!skb_shinfo(head)->frag_list)
				skb_shinfo(head)->frag_list = fp;
			head->data_len += fp->len;
			head->len += fp->len;
			head->truesize += fp->truesize;
		}
		fp = next;
//.........这里部分代码省略.........