C++ skb_unlink函数代码示例

static int bfusb_send_bulk(struct bfusb_data *data, struct sk_buff *skb)
{
	struct bfusb_data_scb *scb = (void *) skb->cb;
	struct urb *urb = bfusb_get_completed(data);
	int err, pipe;

	BT_DBG("bfusb %p skb %p len %d", data, skb, skb->len);

	if (!urb && !(urb = usb_alloc_urb(0, GFP_ATOMIC)))
		return -ENOMEM;

	pipe = usb_sndbulkpipe(data->udev, data->bulk_out_ep);

	usb_fill_bulk_urb(urb, data->udev, pipe, skb->data, skb->len,
			bfusb_tx_complete, skb);

	scb->urb = urb;

	skb_queue_tail(&data->pending_q, skb);

	err = usb_submit_urb(urb, GFP_ATOMIC);
	if (err) {
		BT_ERR("%s bulk tx submit failed urb %p err %d", 
					data->hdev->name, urb, err);
		skb_unlink(skb, &data->pending_q);
		usb_free_urb(urb);
	} else
		atomic_inc(&data->pending_tx);

	return err;
}

static void bfusb_tx_complete(struct urb *urb)
{
	struct sk_buff *skb = (struct sk_buff *) urb->context;
	struct bfusb_data *data = (struct bfusb_data *) skb->dev;

	BT_DBG("bfusb %p urb %p skb %p len %d", data, urb, skb, skb->len);

	atomic_dec(&data->pending_tx);

	if (!test_bit(HCI_RUNNING, &data->hdev->flags))
		return;

	if (!urb->status)
		data->hdev->stat.byte_tx += skb->len;
	else
		data->hdev->stat.err_tx++;

	read_lock(&data->lock);

	skb_unlink(skb, &data->pending_q);
	skb_queue_tail(&data->completed_q, skb);

	bfusb_tx_wakeup(data);

	read_unlock(&data->lock);
}

static void try_fill_recv(struct virtnet_info *vi)
{
	struct sk_buff *skb;
	struct scatterlist sg[1+MAX_SKB_FRAGS];
	int num, err;

	sg_init_table(sg, 1+MAX_SKB_FRAGS);
	for (;;) {
		skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN);
		if (unlikely(!skb))
			break;

		skb_put(skb, MAX_PACKET_LEN);
		vnet_hdr_to_sg(sg, skb);
		num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
		skb_queue_head(&vi->recv, skb);

		err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
		if (err) {
			skb_unlink(skb, &vi->recv);
			kfree_skb(skb);
			break;
		}
		vi->num++;
	}
	if (unlikely(vi->num > vi->max))
		vi->max = vi->num;
	vi->rvq->vq_ops->kick(vi->rvq);
}

static int start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct virtnet_info *vi = netdev_priv(dev);
	int num, err;
	struct scatterlist sg[1+MAX_SKB_FRAGS];
	struct virtio_net_hdr *hdr;
	const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
	DECLARE_MAC_BUF(mac);

	sg_init_table(sg, 1+MAX_SKB_FRAGS);

	pr_debug("%s: xmit %p %s\n", dev->name, skb, print_mac(mac, dest));

	free_old_xmit_skbs(vi);

	/* Encode metadata header at front. */
	hdr = skb_vnet_hdr(skb);
	if (skb->ip_summed == CHECKSUM_PARTIAL) {
		hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
		hdr->csum_start = skb->csum_start - skb_headroom(skb);
		hdr->csum_offset = skb->csum_offset;
	} else {
		hdr->flags = 0;
		hdr->csum_offset = hdr->csum_start = 0;
	}

	if (skb_is_gso(skb)) {
		hdr->gso_size = skb_shinfo(skb)->gso_size;
		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
			hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4_ECN;
		else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
			hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
		else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
			hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
		else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
			hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
		else
			BUG();
	} else {
		hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
		hdr->gso_size = 0;
	}

	vnet_hdr_to_sg(sg, skb);
	num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
	__skb_queue_head(&vi->send, skb);
	err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
	if (err) {
		pr_debug("%s: virtio not prepared to send\n", dev->name);
		skb_unlink(skb, &vi->send);
		netif_stop_queue(dev);
		return NETDEV_TX_BUSY;
	}
	vi->svq->vq_ops->kick(vi->svq);

	return 0;
}

/**
 * ieee80211s_lookup_nexthop - put the appropriate next hop on a mesh frame
 *
 * @next_hop: output argument for next hop address
 * @skb: frame to be sent
 * @dev: network device the frame will be sent through
 *
 * Returns: 0 if the next hop was found. Nonzero otherwise. If no next hop is
 * found, the function will start a path discovery and queue the frame so it is
 * sent when the path is resolved. This means the caller must not free the skb
 * in this case.
 */
int mesh_nexthop_lookup(u8 *next_hop, struct sk_buff *skb,
		struct net_device *dev)
{
	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
	struct sk_buff *skb_to_free = NULL;
	struct mesh_path *mpath;
	int err = 0;

	rcu_read_lock();
	mpath = mesh_path_lookup(skb->data, dev);

	if (!mpath) {
		mesh_path_add(skb->data, dev);
		mpath = mesh_path_lookup(skb->data, dev);
		if (!mpath) {
			dev_kfree_skb(skb);
			sdata->u.sta.mshstats.dropped_frames_no_route++;
			err = -ENOSPC;
			goto endlookup;
		}
	}

	if (mpath->flags & MESH_PATH_ACTIVE) {
		if (time_after(jiffies, mpath->exp_time -
			msecs_to_jiffies(sdata->u.sta.mshcfg.path_refresh_time))
				&& skb->pkt_type != PACKET_OTHERHOST
				&& !(mpath->flags & MESH_PATH_RESOLVING)
				&& !(mpath->flags & MESH_PATH_FIXED)) {
			mesh_queue_preq(mpath,
					PREQ_Q_F_START | PREQ_Q_F_REFRESH);
		}
		memcpy(next_hop, mpath->next_hop->addr,
				ETH_ALEN);
	} else {
		if (!(mpath->flags & MESH_PATH_RESOLVING)) {
			/* Start discovery only if it is not running yet */
			mesh_queue_preq(mpath, PREQ_Q_F_START);
		}

		if (skb_queue_len(&mpath->frame_queue) >=
				MESH_FRAME_QUEUE_LEN) {
			skb_to_free = mpath->frame_queue.next;
			skb_unlink(skb_to_free, &mpath->frame_queue);
		}

		skb_queue_tail(&mpath->frame_queue, skb);
		if (skb_to_free)
			mesh_path_discard_frame(skb_to_free, dev);
		err = -ENOENT;
	}

endlookup:
	rcu_read_unlock();
	return err;
}

void brcmf_rx_frames(struct device *dev, struct sk_buff_head *skb_list)
{
	struct sk_buff *skb, *pnext;
	struct brcmf_if *ifp;
	struct brcmf_bus *bus_if = dev_get_drvdata(dev);
	struct brcmf_pub *drvr = bus_if->drvr;
	u8 ifidx;
	int ret;

	brcmf_dbg(DATA, "Enter\n");

	skb_queue_walk_safe(skb_list, skb, pnext) {
		skb_unlink(skb, skb_list);

		/* process and remove protocol-specific header */
		ret = brcmf_proto_hdrpull(drvr, drvr->fw_signals, &ifidx, skb);
		ifp = drvr->iflist[ifidx];

		if (ret || !ifp || !ifp->ndev) {
			if ((ret != -ENODATA) && ifp)
				ifp->stats.rx_errors++;
			brcmu_pkt_buf_free_skb(skb);
			continue;
		}

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

		if (skb->pkt_type == PACKET_MULTICAST)
			ifp->stats.multicast++;

		/* Process special event packets */
		brcmf_fweh_process_skb(drvr, skb);

		if (!(ifp->ndev->flags & IFF_UP)) {
			brcmu_pkt_buf_free_skb(skb);
			continue;
		}

		ifp->stats.rx_bytes += skb->len;
		ifp->stats.rx_packets++;

		if (in_interrupt())
			netif_rx(skb);
		else
			/* If the receive is not processed inside an ISR,
			 * the softirqd must be woken explicitly to service the
			 * NET_RX_SOFTIRQ. This is handled by netif_rx_ni().
			 */
			netif_rx_ni(skb);
	}

static void p54u_rx_cb(struct urb *urb)
{
	struct sk_buff *skb = (struct sk_buff *) urb->context;
	struct p54u_rx_info *info = (struct p54u_rx_info *)skb->cb;
	struct ieee80211_hw *dev = info->dev;
	struct p54u_priv *priv = dev->priv;

	if (unlikely(urb->status)) {
		info->urb = NULL;
		usb_free_urb(urb);
		return;
	}

	skb_unlink(skb, &priv->rx_queue);
	skb_put(skb, urb->actual_length);
	if (!priv->hw_type)
		skb_pull(skb, sizeof(struct net2280_tx_hdr));

	if (p54_rx(dev, skb)) {
		skb = dev_alloc_skb(MAX_RX_SIZE);
		if (unlikely(!skb)) {
			usb_free_urb(urb);
			/* TODO check rx queue length and refill *somewhere* */
			return;
		}

		info = (struct p54u_rx_info *) skb->cb;
		info->urb = urb;
		info->dev = dev;
		urb->transfer_buffer = skb_tail_pointer(skb);
		urb->context = skb;
		skb_queue_tail(&priv->rx_queue, skb);
	} else {
		if (!priv->hw_type)
			skb_push(skb, sizeof(struct net2280_tx_hdr));

		skb_reset_tail_pointer(skb);
		skb_trim(skb, 0);
		if (urb->transfer_buffer != skb_tail_pointer(skb)) {
			/* this should not happen */
			WARN_ON(1);
			urb->transfer_buffer = skb_tail_pointer(skb);
		}

		skb_queue_tail(&priv->rx_queue, skb);
	}

	usb_submit_urb(urb, GFP_ATOMIC);
}

void
brcmu_pktq_pflush(struct pktq *pq, int prec, bool dir,
                  bool (*fn)(struct sk_buff *, void *), void *arg)
{
    struct sk_buff_head *q;
    struct sk_buff *p, *next;

    q = &pq->q[prec].skblist;
    skb_queue_walk_safe(q, p, next) {
        if (fn == NULL || (*fn) (p, arg)) {
            skb_unlink(p, q);
            brcmu_pkt_buf_free_skb(p);
            pq->len--;
        }
    }
}

/**
 * tx_urb_complete - completes the execution of an URB
 * @urb: a URB
 *
 * This function is called if the URB has been transferred to a device or an
 * error has happened.
 */
static void tx_urb_complete(struct urb *urb)
{
	int r;
	struct sk_buff *skb;
	struct ieee80211_tx_info *info;
	struct zd_usb *usb;
	struct zd_usb_tx *tx;

	skb = (struct sk_buff *)urb->context;
	info = IEEE80211_SKB_CB(skb);
	/*
	 * grab 'usb' pointer before handing off the skb (since
	 * it might be freed by zd_mac_tx_to_dev or mac80211)
	 */
	usb = &zd_hw_mac(info->rate_driver_data[0])->chip.usb;
	tx = &usb->tx;

	switch (urb->status) {
	case 0:
		break;
	case -ESHUTDOWN:
	case -EINVAL:
	case -ENODEV:
	case -ENOENT:
	case -ECONNRESET:
	case -EPIPE:
		dev_dbg_f(urb_dev(urb), "urb %p error %d\n", urb, urb->status);
		break;
	default:
		dev_dbg_f(urb_dev(urb), "urb %p error %d\n", urb, urb->status);
		goto resubmit;
	}
free_urb:
	skb_unlink(skb, &usb->tx.submitted_skbs);
	zd_mac_tx_to_dev(skb, urb->status);
	usb_free_urb(urb);
	tx_dec_submitted_urbs(usb);
	return;
resubmit:
	usb_anchor_urb(urb, &tx->submitted);
	r = usb_submit_urb(urb, GFP_ATOMIC);
	if (r) {
		usb_unanchor_urb(urb);
		dev_dbg_f(urb_dev(urb), "error resubmit urb %p %d\n", urb, r);
		goto free_urb;
	}
}

static void shaper_kick(struct shaper *shaper)
{
	struct sk_buff *skb;

	/*
	 *	Walk the list (may be empty)
	 */

	while((skb=skb_peek(&shaper->sendq))!=NULL)
	{
		/*
		 *	Each packet due to go out by now (within an error
		 *	of SHAPER_BURST) gets kicked onto the link
		 */

		if(sh_debug)
			printk("Clock = %ld, jiffies = %ld\n", SHAPERCB(skb)->shapeclock, jiffies);
		if(time_before_eq(SHAPERCB(skb)->shapeclock, jiffies + SHAPER_BURST))
		{
			/*
			 *	Pull the frame and get interrupts back on.
			 */

			skb_unlink(skb, &shaper->sendq);
			if (shaper->recovery <
			    SHAPERCB(skb)->shapeclock + SHAPERCB(skb)->shapelen)
				shaper->recovery = SHAPERCB(skb)->shapeclock + SHAPERCB(skb)->shapelen;
			/*
			 *	Pass on to the physical target device via
			 *	our low level packet thrower.
			 */

			SHAPERCB(skb)->shapepend=0;
			shaper_queue_xmit(shaper, skb);	/* Fire */
		}
		else
			break;
	}

	/*
	 *	Next kick.
	 */

	if(skb!=NULL)
		mod_timer(&shaper->timer, SHAPERCB(skb)->shapeclock);
}

/*
 * precedence based dequeue with match function. Passing a NULL pointer
 * for the match function parameter is considered to be a wildcard so
 * any packet on the queue is returned. In that case it is no different
 * from brcmu_pktq_pdeq() above.
 */
struct sk_buff *brcmu_pktq_pdeq_match(struct pktq *pq, int prec,
                                      bool (*match_fn)(struct sk_buff *skb,
                                              void *arg), void *arg)
{
    struct sk_buff_head *q;
    struct sk_buff *p, *next;

    q = &pq->q[prec].skblist;
    skb_queue_walk_safe(q, p, next) {
        if (match_fn == NULL || match_fn(p, arg)) {
            skb_unlink(p, q);
            pq->len--;
            return p;
        }
    }
    return NULL;
}

static int spi_transmit_data(struct spi_device *spi,
		unsigned char *buf, size_t len)
{
	int ret;

	struct spi_message msg;
	struct spi_transfer t = {
		.len = len,
		.tx_buf = buf,
		.delay_usecs = 10,
	};

	spi_message_init(&msg);
	spi_message_add_tail(&t, &msg);

	ret = spi_sync(spi, &msg);
	if (ret < 0)
		mif_err("spi_sync() fail(%d)\n", ret);

	return ret;
}

static int spi_boot_tx_skb(struct link_device *ld, struct io_device *iod,
			struct sk_buff *skb)
{
	int ret = -EINVAL;

	struct spi_boot_link_device *sbld = to_spi_boot_link_dev(ld);

	unsigned char *buf = skb->data + SIPC5_MIN_HEADER_SIZE;
	int len = skb->len - SIPC5_MIN_HEADER_SIZE;

	skb_queue_tail(&sbld->tx_q, skb);

	ret = spi_transmit_data(sbld->spi, buf, len);
	if (ret < 0) {
		mif_err("spi_transmit_data() failed(%d)\n", ret);
		goto exit;
	}

exit:
	skb_unlink(skb, &sbld->tx_q);

	return ret;
}

static int bfusb_rx_submit(struct bfusb_data *data, struct urb *urb)
{
	struct bfusb_data_scb *scb;
	struct sk_buff *skb;
	int err, pipe, size = HCI_MAX_FRAME_SIZE + 32;

	BT_DBG("bfusb %p urb %p", data, urb);

	if (!urb) {
		urb = usb_alloc_urb(0, GFP_ATOMIC);
		if (!urb)
			return -ENOMEM;
	}

	skb = bt_skb_alloc(size, GFP_ATOMIC);
	if (!skb) {
		usb_free_urb(urb);
		return -ENOMEM;
	}

	skb->dev = (void *) data;

	scb = (struct bfusb_data_scb *) skb->cb;
	scb->urb = urb;

	pipe = usb_rcvbulkpipe(data->udev, data->bulk_in_ep);

	usb_fill_bulk_urb(urb, data->udev, pipe, skb->data, size,
			bfusb_rx_complete, skb);

	skb_queue_tail(&data->pending_q, skb);

	err = usb_submit_urb(urb, GFP_ATOMIC);
	if (err) {
		BT_ERR("%s bulk rx submit failed urb %p err %d",
					data->hdev->name, urb, err);
		skb_unlink(skb, &data->pending_q);
		kfree_skb(skb);
		usb_free_urb(urb);
	}

	return err;
}

static ssize_t
nanopci_read(struct file *filp, char __user *buf, size_t count, loff_t *off)
{
   struct nano_pci_card *card = filp->private_data;
   struct sk_buff *skb;

   size_t n;

   if(down_interruptible(&card->sem))
      return -ERESTARTSYS;

   while((skb = skb_peek(&card->rx_queue)) == NULL) {
      up(&card->sem);
      if(filp->f_flags & O_NONBLOCK)
	 return -EAGAIN;
      if(wait_event_interruptible(card->rx_waitqueue, 
				  !skb_queue_empty(&card->rx_queue)))
	 return -ERESTARTSYS;
      if(down_interruptible(&card->sem))
	 return -ERESTARTSYS;
   }

   n = skb->len;
   if(n > count)
      n = count;
   if(copy_to_user(buf, skb->data, n)) {
      KDEBUG(ERROR, "EFAULT copying out data");
      up(&card->sem);
      return -EFAULT;
   }
   skb_pull(skb, n);
   if(skb->len == 0) {
      skb_unlink(skb, &card->rx_queue);
      dev_kfree_skb(skb);
   }
   card->status.irq_handled = card->status.irq_count - 
     skb_queue_len(&card->rx_queue);

   up(&card->sem);
   return n;
}

/**
 * zd_usb_tx: initiates transfer of a frame of the device
 *
 * @usb: the zd1211rw-private USB structure
 * @skb: a &struct sk_buff pointer
 *
 * This function tranmits a frame to the device. It doesn't wait for
 * completion. The frame must contain the control set and have all the
 * control set information available.
 *
 * The function returns 0 if the transfer has been successfully initiated.
 */
int zd_usb_tx(struct zd_usb *usb, struct sk_buff *skb)
{
	int r;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	struct usb_device *udev = zd_usb_to_usbdev(usb);
	struct urb *urb;
	struct zd_usb_tx *tx = &usb->tx;

	if (!atomic_read(&tx->enabled)) {
		r = -ENOENT;
		goto out;
	}

	urb = usb_alloc_urb(0, GFP_ATOMIC);
	if (!urb) {
		r = -ENOMEM;
		goto out;
	}

	usb_fill_bulk_urb(urb, udev, usb_sndbulkpipe(udev, EP_DATA_OUT),
		          skb->data, skb->len, tx_urb_complete, skb);

	info->rate_driver_data[1] = (void *)jiffies;
	skb_queue_tail(&tx->submitted_skbs, skb);
	usb_anchor_urb(urb, &tx->submitted);

	r = usb_submit_urb(urb, GFP_ATOMIC);
	if (r) {
		dev_dbg_f(zd_usb_dev(usb), "error submit urb %p %d\n", urb, r);
		usb_unanchor_urb(urb);
		skb_unlink(skb, &tx->submitted_skbs);
		goto error;
	}
	tx_inc_submitted_urbs(usb);
	return 0;
error:
	usb_free_urb(urb);
out:
	return r;
}