static int ctcm_transmit_skb()

in net/ctcm_main.c [465:595]

• 101 lines of code
• 12 McCabe index (conditional complexity)

static int ctcm_transmit_skb(struct channel *ch, struct sk_buff *skb)
{
	unsigned long saveflags;
	struct ll_header header;
	int rc = 0;
	__u16 block_len;
	int ccw_idx;
	struct sk_buff *nskb;
	unsigned long hi;

	/* we need to acquire the lock for testing the state
	 * otherwise we can have an IRQ changing the state to
	 * TXIDLE after the test but before acquiring the lock.
	 */
	spin_lock_irqsave(&ch->collect_lock, saveflags);
	if (fsm_getstate(ch->fsm) != CTC_STATE_TXIDLE) {
		int l = skb->len + LL_HEADER_LENGTH;

		if (ch->collect_len + l > ch->max_bufsize - 2) {
			spin_unlock_irqrestore(&ch->collect_lock, saveflags);
			return -EBUSY;
		} else {
			refcount_inc(&skb->users);
			header.length = l;
			header.type = be16_to_cpu(skb->protocol);
			header.unused = 0;
			memcpy(skb_push(skb, LL_HEADER_LENGTH), &header,
			       LL_HEADER_LENGTH);
			skb_queue_tail(&ch->collect_queue, skb);
			ch->collect_len += l;
		}
		spin_unlock_irqrestore(&ch->collect_lock, saveflags);
				goto done;
	}
	spin_unlock_irqrestore(&ch->collect_lock, saveflags);
	/*
	 * Protect skb against beeing free'd by upper
	 * layers.
	 */
	refcount_inc(&skb->users);
	ch->prof.txlen += skb->len;
	header.length = skb->len + LL_HEADER_LENGTH;
	header.type = be16_to_cpu(skb->protocol);
	header.unused = 0;
	memcpy(skb_push(skb, LL_HEADER_LENGTH), &header, LL_HEADER_LENGTH);
	block_len = skb->len + 2;
	*((__u16 *)skb_push(skb, 2)) = block_len;

	/*
	 * IDAL support in CTCM is broken, so we have to
	 * care about skb's above 2G ourselves.
	 */
	hi = ((unsigned long)skb_tail_pointer(skb) + LL_HEADER_LENGTH) >> 31;
	if (hi) {
		nskb = alloc_skb(skb->len, GFP_ATOMIC | GFP_DMA);
		if (!nskb) {
			refcount_dec(&skb->users);
			skb_pull(skb, LL_HEADER_LENGTH + 2);
			ctcm_clear_busy(ch->netdev);
			return -ENOMEM;
		} else {
			skb_put_data(nskb, skb->data, skb->len);
			refcount_inc(&nskb->users);
			refcount_dec(&skb->users);
			dev_kfree_skb_irq(skb);
			skb = nskb;
		}
	}

	ch->ccw[4].count = block_len;
	if (set_normalized_cda(&ch->ccw[4], skb->data)) {
		/*
		 * idal allocation failed, try via copying to
		 * trans_skb. trans_skb usually has a pre-allocated
		 * idal.
		 */
		if (ctcm_checkalloc_buffer(ch)) {
			/*
			 * Remove our header. It gets added
			 * again on retransmit.
			 */
			refcount_dec(&skb->users);
			skb_pull(skb, LL_HEADER_LENGTH + 2);
			ctcm_clear_busy(ch->netdev);
			return -ENOMEM;
		}

		skb_reset_tail_pointer(ch->trans_skb);
		ch->trans_skb->len = 0;
		ch->ccw[1].count = skb->len;
		skb_copy_from_linear_data(skb,
				skb_put(ch->trans_skb, skb->len), skb->len);
		refcount_dec(&skb->users);
		dev_kfree_skb_irq(skb);
		ccw_idx = 0;
	} else {
		skb_queue_tail(&ch->io_queue, skb);
		ccw_idx = 3;
	}
	if (do_debug_ccw)
		ctcmpc_dumpit((char *)&ch->ccw[ccw_idx],
					sizeof(struct ccw1) * 3);
	ch->retry = 0;
	fsm_newstate(ch->fsm, CTC_STATE_TX);
	fsm_addtimer(&ch->timer, CTCM_TIME_5_SEC, CTC_EVENT_TIMER, ch);
	spin_lock_irqsave(get_ccwdev_lock(ch->cdev), saveflags);
	ch->prof.send_stamp = jiffies;
	rc = ccw_device_start(ch->cdev, &ch->ccw[ccw_idx], 0, 0xff, 0);
	spin_unlock_irqrestore(get_ccwdev_lock(ch->cdev), saveflags);
	if (ccw_idx == 3)
		ch->prof.doios_single++;
	if (rc != 0) {
		fsm_deltimer(&ch->timer);
		ctcm_ccw_check_rc(ch, rc, "single skb TX");
		if (ccw_idx == 3)
			skb_dequeue_tail(&ch->io_queue);
		/*
		 * Remove our header. It gets added
		 * again on retransmit.
		 */
		skb_pull(skb, LL_HEADER_LENGTH + 2);
	} else if (ccw_idx == 0) {
		struct net_device *dev = ch->netdev;
		struct ctcm_priv *priv = dev->ml_priv;
		priv->stats.tx_packets++;
		priv->stats.tx_bytes += skb->len - LL_HEADER_LENGTH;
	}
done:
	ctcm_clear_busy(ch->netdev);
	return rc;
}