static int gve_rx_dqo()

in google/gve/gve_rx_dqo.c [526:642]

• 94 lines of code
• 18 McCabe index (conditional complexity)

static int gve_rx_dqo(struct napi_struct *napi, struct gve_rx_ring *rx,
		      const struct gve_rx_compl_desc_dqo *compl_desc,
		      u32 desc_idx, int queue_idx)
{
	const u16 buffer_id = le16_to_cpu(compl_desc->buf_id);
	const bool hbo = compl_desc->header_buffer_overflow;
	const bool eop = compl_desc->end_of_packet != 0;
	const bool hsplit = compl_desc->split_header;
	struct gve_rx_buf_state_dqo *buf_state;
	struct gve_priv *priv = rx->gve;
	u16 buf_len;
	u16 hdr_len;

	if (unlikely(buffer_id >= rx->dqo.num_buf_states)) {
		net_err_ratelimited("%s: Invalid RX buffer_id=%u\n",
				    priv->dev->name, buffer_id);
		return -EINVAL;
	}
	buf_state = &rx->dqo.buf_states[buffer_id];
	if (unlikely(!gve_buf_state_is_allocated(rx, buf_state))) {
		net_err_ratelimited("%s: RX buffer_id is not allocated: %u\n",
				    priv->dev->name, buffer_id);
		return -EINVAL;
	}

	if (unlikely(compl_desc->rx_error)) {
		gve_free_buffer(rx, buf_state);
		return -EINVAL;
	}

	buf_len = compl_desc->packet_len;
	hdr_len = compl_desc->header_len;

	/* Page might have not been used for awhile and was likely last written
	 * by a different thread.
	 */
	prefetch(buf_state->page_info.page);

	/* Copy the header into the skb in the case of header split */
	if (hsplit) {
		int unsplit = 0;

		if (hdr_len && !hbo) {
			rx->ctx.skb_head = gve_rx_copy_data(priv->dev, napi,
							    rx->dqo.hdr_bufs.data +
							    desc_idx * priv->header_buf_size,
							    hdr_len);
			if (unlikely(!rx->ctx.skb_head))
				goto error;
			rx->ctx.skb_tail = rx->ctx.skb_head;

			if (rx->dqo.page_pool)
				skb_mark_for_recycle(rx->ctx.skb_head);
		} else {
			unsplit = 1;
		}
		u64_stats_update_begin(&rx->statss);
		rx->rx_hsplit_pkt++;
		rx->rx_hsplit_unsplit_pkt += unsplit;
		rx->rx_hsplit_bytes += hdr_len;
		u64_stats_update_end(&rx->statss);
	}

	/* Sync the portion of dma buffer for CPU to read. */
	dma_sync_single_range_for_cpu(&priv->pdev->dev, buf_state->addr,
				      buf_state->page_info.page_offset,
				      buf_len, DMA_FROM_DEVICE);

	/* Append to current skb if one exists. */
	if (rx->ctx.skb_head) {
		if (unlikely(gve_rx_append_frags(napi, buf_state, buf_len, rx,
						 priv)) != 0) {
			goto error;
		}
		return 0;
	}

	if (eop && buf_len <= priv->rx_copybreak) {
		rx->ctx.skb_head = gve_rx_copy(priv->dev, napi,
					       &buf_state->page_info, buf_len);
		if (unlikely(!rx->ctx.skb_head))
			goto error;
		rx->ctx.skb_tail = rx->ctx.skb_head;

		u64_stats_update_begin(&rx->statss);
		rx->rx_copied_pkt++;
		rx->rx_copybreak_pkt++;
		u64_stats_update_end(&rx->statss);

		gve_free_buffer(rx, buf_state);
		return 0;
	}

	rx->ctx.skb_head = napi_get_frags(napi);
	if (unlikely(!rx->ctx.skb_head))
		goto error;
	rx->ctx.skb_tail = rx->ctx.skb_head;

	if (gve_rx_should_trigger_copy_ondemand(rx)) {
		if (gve_rx_copy_ondemand(rx, buf_state, buf_len) < 0)
			goto error;
		return 0;
	}

	if (rx->dqo.page_pool)
		skb_mark_for_recycle(rx->ctx.skb_head);

	skb_add_rx_frag(rx->ctx.skb_head, 0, buf_state->page_info.page,
			buf_state->page_info.page_offset, buf_len,
			buf_state->page_info.buf_size);
	gve_reuse_buffer(rx, buf_state);
	return 0;

error:
	gve_free_buffer(rx, buf_state);
	return -ENOMEM;
}