C++ skb_orphan函数代码示例

/*
 * The higher levels take care of making this non-reentrant (it's
 * called with bh's disabled).
 */
static netdev_tx_t loopback_xmit(struct sk_buff *skb,
				 struct net_device *dev)
{
	struct pcpu_lstats *pcpu_lstats, *lb_stats;
	int len;

#ifdef CONFIG_VE
	if (unlikely(get_exec_env()->disable_net)) {
		kfree_skb(skb);
		return 0;
	}
#endif
	skb_orphan(skb);

	skb->protocol = eth_type_trans(skb, dev);

	/* it's OK to use per_cpu_ptr() because BHs are off */
	pcpu_lstats = dev->ml_priv;
	lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());

	len = skb->len;
	if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
		lb_stats->bytes += len;
		lb_stats->packets++;
	} else
		lb_stats->drops++;

	return NETDEV_TX_OK;
}

/**
 * tipc_msg_reverse(): swap source and destination addresses and add error code
 * @buf:  buffer containing message to be reversed
 * @dnode: return value: node where to send message after reversal
 * @err:  error code to be set in message
 * Consumes buffer if failure
 * Returns true if success, otherwise false
 */
bool tipc_msg_reverse(struct sk_buff *buf, u32 *dnode, int err)
{
	struct tipc_msg *msg = buf_msg(buf);
	uint imp = msg_importance(msg);
	struct tipc_msg ohdr;
	uint rdsz = min_t(uint, msg_data_sz(msg), MAX_FORWARD_SIZE);

	if (skb_linearize(buf))
		goto exit;
	if (msg_dest_droppable(msg))
		goto exit;
	if (msg_errcode(msg))
		goto exit;

	memcpy(&ohdr, msg, msg_hdr_sz(msg));
	imp = min_t(uint, imp + 1, TIPC_CRITICAL_IMPORTANCE);
	if (msg_isdata(msg))
		msg_set_importance(msg, imp);
	msg_set_errcode(msg, err);
	msg_set_origport(msg, msg_destport(&ohdr));
	msg_set_destport(msg, msg_origport(&ohdr));
	msg_set_prevnode(msg, tipc_own_addr);
	if (!msg_short(msg)) {
		msg_set_orignode(msg, msg_destnode(&ohdr));
		msg_set_destnode(msg, msg_orignode(&ohdr));
	}
	msg_set_size(msg, msg_hdr_sz(msg) + rdsz);
	skb_trim(buf, msg_size(msg));
	skb_orphan(buf);
	*dnode = msg_orignode(&ohdr);
	return true;
exit:
	kfree_skb(buf);
	return false;
}

/* Process an incoming IP datagram fragment. */
int ip_defrag(struct net *net, struct sk_buff *skb, u32 user)
{
	struct net_device *dev = skb->dev ? : skb_dst(skb)->dev;
	int vif = l3mdev_master_ifindex_rcu(dev);
	struct ipq *qp;

	__IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS);
	skb_orphan(skb);

	/* Lookup (or create) queue header */
	qp = ip_find(net, ip_hdr(skb), user, vif);
	if (qp) {
		int ret;

		spin_lock(&qp->q.lock);

		ret = ip_frag_queue(qp, skb);

		spin_unlock(&qp->q.lock);
		ipq_put(qp);
		return ret;
	}

	__IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
	kfree_skb(skb);
	return -ENOMEM;
}

static void sc_send_8023(struct sk_buff *skb, struct net_device *dev)
{
	struct ethhdr *eh;

	if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
		return;

	/* drop conntrack reference */
	nf_reset(skb);

	/* detach skb from CAPWAP */
	skb_orphan(skb);
	secpath_reset(skb);

	/* drop any routing info */
	skb_dst_drop(skb);

	skb->dev = dev;
	skb_reset_mac_header(skb);
	eh = eth_hdr(skb);
	if (likely(eth_proto_is_802_3(eh->h_proto)))
		skb->protocol = eh->h_proto;
	else
		skb->protocol = htons(ETH_P_802_2);
	skb_set_network_header(skb, ETH_HLEN);

	/* Force the device to verify it. */
	skb->ip_summed = CHECKSUM_NONE;

	dev_queue_xmit(skb);
}

/*
 * The higher levels take care of making this non-reentrant (it's
 * called with bh's disabled).
 */
static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct net_device_stats *lb_stats;

	skb_orphan(skb);

	skb->protocol=eth_type_trans(skb,dev);
	skb->dev=dev;
#ifndef LOOPBACK_MUST_CHECKSUM
	skb->ip_summed = CHECKSUM_UNNECESSARY;
#endif

	if (skb_shinfo(skb)->tso_size) {
		BUG_ON(skb->protocol != htons(ETH_P_IP));
		BUG_ON(skb->nh.iph->protocol != IPPROTO_TCP);

		emulate_large_send_offload(skb);
		return 0;
	}

	dev->last_rx = jiffies;

	lb_stats = &per_cpu(loopback_stats, get_cpu());
	lb_stats->rx_bytes += skb->len;
	lb_stats->tx_bytes += skb->len;
	lb_stats->rx_packets++;
	lb_stats->tx_packets++;
	put_cpu();

	netif_rx(skb);

	return(0);
}

/* Requeue received messages for a kcm socket to other kcm sockets. This is
 * called with a kcm socket is receive disabled.
 * RX mux lock held.
 */
static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
{
	struct sk_buff *skb;
	struct kcm_sock *kcm;

	while ((skb = __skb_dequeue(head))) {
		/* Reset destructor to avoid calling kcm_rcv_ready */
		skb->destructor = sock_rfree;
		skb_orphan(skb);
try_again:
		if (list_empty(&mux->kcm_rx_waiters)) {
			skb_queue_tail(&mux->rx_hold_queue, skb);
			continue;
		}

		kcm = list_first_entry(&mux->kcm_rx_waiters,
				       struct kcm_sock, wait_rx_list);

		if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
			/* Should mean socket buffer full */
			list_del(&kcm->wait_rx_list);
			kcm->rx_wait = false;

			/* Commit rx_wait to read in kcm_free */
			smp_wmb();

			goto try_again;
		}
	}
}

/* The higher levels take care of making this non-reentrant (it's
 * called with bh's disabled).
 */
static netdev_tx_t loopback_xmit(struct sk_buff *skb,
				 struct net_device *dev)
{
	struct pcpu_lstats *lb_stats;
	int len;

	skb_tx_timestamp(skb);
	skb_orphan(skb);

	/* Before queueing this packet to netif_rx(),
	 * make sure dst is refcounted.
	 */
	skb_dst_force(skb);

	skb->protocol = eth_type_trans(skb, dev);

	/* it's OK to use per_cpu_ptr() because BHs are off */
	lb_stats = this_cpu_ptr(dev->lstats);

	len = skb->len;
	if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
		u64_stats_update_begin(&lb_stats->syncp);
		lb_stats->bytes += len;
		lb_stats->packets++;
		u64_stats_update_end(&lb_stats->syncp);
	}

	return NETDEV_TX_OK;
}

static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
	struct sk_buff_head *list = &sk->sk_receive_queue;

	if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
		return -ENOMEM;

	if (!sk_rmem_schedule(sk, skb, skb->truesize))
		return -ENOBUFS;

	skb->dev = NULL;

	skb_orphan(skb);
	skb->sk = sk;
	skb->destructor = kcm_rfree;
	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
	sk_mem_charge(sk, skb->truesize);

	skb_queue_tail(list, skb);

	if (!sock_flag(sk, SOCK_DEAD))
		sk->sk_data_ready(sk);

	return 0;
}

/** Handle some skbs on a varp socket (if any).
 *
 * @param fd socket file descriptor
 * @param n maximum number of skbs to handle
 * @return number of skbs handled
 */
static int handle_varp_sock(int fd, int n){
    int ret = 0;
    int err = 0;
    struct sk_buff *skb;
    struct socket *sock = NULL;

    sock = sockfd_lookup(fd, &err);
    if (!sock){
        wprintf("> no sock for fd=%d\n", fd);
        goto exit;
    }
    for( ; ret < n; ret++){
        if(!sock->sk) break;
        skb = skb_dequeue(&sock->sk->sk_receive_queue);
        if(!skb) break;
        // Call the skb destructor so it isn't charged to the socket anymore.
        // An skb from a socket receive queue is charged to the socket
        // by skb_set_owner_r() until its destructor is called.
        // If the destructor is not called the socket will run out of
        // receive queue space and be unable to accept incoming skbs.
        // The destructor used is sock_rfree(), see 'include/net/sock.h'.
        // Other destructors: sock_wfree, sk_stream_rfree.
        skb_orphan(skb);
        handle_varp_skb(skb);
    }
    sockfd_put(sock);
  exit:
    dprintf("< ret=%d\n", ret);
    return ret;
}

/* On transmit, associate with the tunnel socket */
static void vxlan_set_owner(struct sock *sk, struct sk_buff *skb)
{
	skb_orphan(skb);
	sock_hold(sk);
	skb->sk = sk;
	skb->destructor = vxlan_sock_put;
}

static __inline__ int ethertap_rx_skb(struct sk_buff *skb, struct net_device *dev)
{
	struct net_local *lp = (struct net_local *)dev->priv;
#ifdef CONFIG_ETHERTAP_MC
	struct ethhdr *eth = (struct ethhdr*)(skb->data + 2);
#endif
	int len = skb->len;

	if (len < 16) {
		printk(KERN_DEBUG "%s : rx len = %d\n", dev->name, len);
		kfree_skb(skb);
		return -EINVAL;
	}
	if (NETLINK_CREDS(skb)->uid) {
		printk(KERN_INFO "%s : user %d\n", dev->name, NETLINK_CREDS(skb)->uid);
		kfree_skb(skb);
		return -EPERM;
	}

#ifdef CONFIG_ETHERTAP_MC
	if (!(dev->flags&(IFF_NOARP|IFF_PROMISC))) {
		int drop = 0;

		if (eth->h_dest[0]&1) {
			if (!(ethertap_mc_hash(eth->h_dest)&lp->groups))
				drop = 1;
		} else if (memcmp(eth->h_dest, dev->dev_addr, 6) != 0)
			drop = 1;

		if (drop) {
			if (ethertap_debug > 3)
				printk(KERN_DEBUG "%s : not for us\n", dev->name);
			kfree_skb(skb);
			return -EINVAL;
		}
	}
#endif

	if (skb_shared(skb)) {
	  	struct sk_buff *skb2 = skb;
	  	skb = skb_clone(skb, GFP_KERNEL);	/* Clone the buffer */
	  	if (skb==NULL) {
			kfree_skb(skb2);
			return -ENOBUFS;
		}
	  	kfree_skb(skb2);
	} else
		skb_orphan(skb);

	skb_pull(skb, 2);
	skb->dev = dev;
	skb->protocol=eth_type_trans(skb,dev);
	memset(skb->cb, 0, sizeof(skb->cb));
	lp->stats.rx_packets++;
	lp->stats.rx_bytes+=len;
	netif_rx(skb);
	dev->last_rx = jiffies;
	return len;
}

static void hci_smd_recv_event(void)
{
	int len = 0;
	int rc = 0;
	struct sk_buff *skb = NULL;
	struct hci_smd_data *hsmd = &hs;
	wake_lock(&hs.wake_lock_rx);

	len = smd_read_avail(hsmd->event_channel);
	if (len > HCI_MAX_FRAME_SIZE) {
		BT_ERR("Frame larger than the allowed size, flushing frame");
		rc = smd_read(hsmd->event_channel, NULL, len);
		goto out_event;
	}

	while (len > 0) {
		skb = bt_skb_alloc(len, GFP_ATOMIC);
		if (!skb) {
			BT_ERR("Error in allocating socket buffer");
			smd_read(hsmd->event_channel, NULL, len);
			goto out_event;
		}

		rc = smd_read(hsmd->event_channel, skb_put(skb, len), len);
		if (rc < len) {
			BT_ERR("Error in reading from the event channel");
			goto out_event;
		}

		skb->dev = (void *)hsmd->hdev;
		bt_cb(skb)->pkt_type = HCI_EVENT_PKT;

		skb_orphan(skb);

		rc = hci_recv_frame(skb);
		if (rc < 0) {
			BT_ERR("Error in passing the packet to HCI Layer");
			/*
			 * skb is getting freed in hci_recv_frame, making it
			 *  to null to avoid multiple access
			 */
			skb = NULL;
			goto out_event;
		}

		len = smd_read_avail(hsmd->event_channel);
		/*
		 * Start the timer to monitor whether the Rx queue is
		 * empty for releasing the Rx wake lock
		 */
		BT_DBG("Rx Timer is starting");
		mod_timer(&hsmd->rx_q_timer,
				jiffies + msecs_to_jiffies(RX_Q_MONITOR));
	}
out_event:
	release_lock();
	if (rc)
		kfree_skb(skb);
}

/* In the event of a remote destination, it's possible that we would have
 * matches against an old socket (particularly a TIME-WAIT socket). This
 * causes havoc down the line (ip_local_out et. al. expect regular sockets
 * and invalid memory accesses will happen) so simply drop the association
 * in this case.
*/
static inline void ip_vs_drop_early_demux_sk(struct sk_buff *skb)
{
	/* If dev is set, the packet came from the LOCAL_IN callback and
	 * not from a local TCP socket.
	 */
	if (skb->dev)
		skb_orphan(skb);
}

/*
 * Prepends an ISI header and sends a datagram.
 */
static int pn_send(struct sk_buff *skb, struct net_device *dev,
                   u16 dst, u16 src, u8 res, u8 irq)
{
    struct phonethdr *ph;
    int err;

    if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
            skb->len + sizeof(struct phonethdr) > dev->mtu) {
        err = -EMSGSIZE;
        goto drop;
    }

    /* Broadcast sending is not implemented */
    if (pn_addr(dst) == PNADDR_BROADCAST) {
        err = -EOPNOTSUPP;
        goto drop;
    }

    skb_reset_transport_header(skb);
    WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
    skb_push(skb, sizeof(struct phonethdr));
    skb_reset_network_header(skb);
    ph = pn_hdr(skb);
    ph->pn_rdev = pn_dev(dst);
    ph->pn_sdev = pn_dev(src);
    ph->pn_res = res;
    ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
    ph->pn_robj = pn_obj(dst);
    ph->pn_sobj = pn_obj(src);

    skb->protocol = htons(ETH_P_PHONET);
    skb->priority = 0;
    skb->dev = dev;

    if (pn_addr(src) == pn_addr(dst)) {
        skb_reset_mac_header(skb);
        skb->pkt_type = PACKET_LOOPBACK;
        skb_orphan(skb);
        if (irq)
            netif_rx(skb);
        else
            netif_rx_ni(skb);
        err = 0;
    } else {
        err = dev_hard_header(skb, dev, ntohs(skb->protocol),
                              NULL, NULL, skb->len);
        if (err < 0) {
            err = -EHOSTUNREACH;
            goto drop;
        }
        err = dev_queue_xmit(skb);
    }

    return err;
drop:
    kfree_skb(skb);
    return err;
}

static inline int sn_send_tx_queue(struct sn_queue *queue,
			            struct sn_device* dev, struct sk_buff* skb)
{
	struct sn_tx_metadata tx_meta;
	int ret = NET_XMIT_DROP;

#if LINUX_VERSION_CODE < KERNEL_VERSION(3,10,0)
	if (queue->tx.opts.tci) {
		skb = vlan_insert_tag(skb, queue->tx.opts.tci);
		if (unlikely(!skb))
			goto skip_send;
	}
#else
	if (queue->tx.opts.tci) {
		skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
				queue->tx.opts.tci);
		if (unlikely(!skb))
			goto skip_send;
	}

	if (queue->tx.opts.outer_tci) {
		skb = vlan_insert_tag(skb, htons(ETH_P_8021AD),
				queue->tx.opts.outer_tci);
		if (unlikely(!skb))
			goto skip_send;
	}
#endif

	skb_orphan(skb);

	sn_set_tx_metadata(skb, &tx_meta);
	ret = dev->ops->do_tx(queue, skb, &tx_meta);

skip_send:
	switch (ret) {
	case NET_XMIT_CN:
		queue->tx.stats.throttled++;
		/* fall through */

	case NET_XMIT_SUCCESS:
		queue->tx.stats.packets++;
		queue->tx.stats.bytes += skb->len;
		break;

	case NET_XMIT_DROP:
		queue->tx.stats.dropped++;
		break;

	case SN_NET_XMIT_BUFFERED:
		/* should not free skb */
		return NET_XMIT_SUCCESS;
	}

	dev_kfree_skb(skb);
	return ret;
}