int gve_rx_poll_dqo()

in google/gve/gve_rx_dqo.c [703:796]

• 62 lines of code
• 10 McCabe index (conditional complexity)

int gve_rx_poll_dqo(struct gve_notify_block *block, int budget)
{
	struct napi_struct *napi = &block->napi;
	netdev_features_t feat = napi->dev->features;

	struct gve_rx_ring *rx = block->rx;
	struct gve_rx_compl_queue_dqo *complq = &rx->dqo.complq;

	u32 work_done = 0;
	u64 bytes = 0;
	int err;

	while (work_done < budget) {
		struct gve_rx_compl_desc_dqo *compl_desc =
			&complq->desc_ring[complq->head];
		u32 pkt_bytes;

		/* No more new packets */
		if (compl_desc->generation == complq->cur_gen_bit)
			break;

		/* Prefetch the next two descriptors. */
		prefetch(&complq->desc_ring[(complq->head + 1) & complq->mask]);
		prefetch(&complq->desc_ring[(complq->head + 2) & complq->mask]);

		/* Do not read data until we own the descriptor */
		dma_rmb();

		err = gve_rx_dqo(napi, rx, compl_desc, complq->head, rx->q_num);
		if (err < 0) {
			gve_rx_free_skb(napi, rx);
			u64_stats_update_begin(&rx->statss);
			if (err == -ENOMEM)
				rx->rx_skb_alloc_fail++;
			else if (err == -EINVAL)
				rx->rx_desc_err_dropped_pkt++;
			u64_stats_update_end(&rx->statss);
		}

		complq->head = (complq->head + 1) & complq->mask;
		complq->num_free_slots++;

		/* When the ring wraps, the generation bit is flipped. */
		complq->cur_gen_bit ^= (complq->head == 0);

		/* Receiving a completion means we have space to post another
		 * buffer on the buffer queue.
		 */
		{
			struct gve_rx_buf_queue_dqo *bufq = &rx->dqo.bufq;

			bufq->head = (bufq->head + 1) & bufq->mask;
		}

		/* Free running counter of completed descriptors */
		rx->cnt++;

		if (!rx->ctx.skb_head)
			continue;

		if (!compl_desc->end_of_packet)
			continue;

		work_done++;
		pkt_bytes = rx->ctx.skb_head->len;
		/* The ethernet header (first ETH_HLEN bytes) is snipped off
		 * by eth_type_trans.
		 */
		if (skb_headlen(rx->ctx.skb_head))
			pkt_bytes += ETH_HLEN;

		/* gve_rx_complete_skb() will consume skb if successful */
		if (gve_rx_complete_skb(rx, napi, compl_desc, feat) != 0) {
			gve_rx_free_skb(napi, rx);
			u64_stats_update_begin(&rx->statss);
			rx->rx_desc_err_dropped_pkt++;
			u64_stats_update_end(&rx->statss);
			continue;
		}

		bytes += pkt_bytes;
		rx->ctx.skb_head = NULL;
		rx->ctx.skb_tail = NULL;
	}

	gve_rx_post_buffers_dqo(rx);

	u64_stats_update_begin(&rx->statss);
	rx->rpackets += work_done;
	rx->rbytes += bytes;
	u64_stats_update_end(&rx->statss);

	return work_done;
}