static void gve_rx()

in google/gve/gve_rx.c [793:928]

• 115 lines of code
• 19 McCabe index (conditional complexity)

static void gve_rx(struct gve_rx_ring *rx, netdev_features_t feat,
		   struct gve_rx_desc *desc, u32 idx,
		   struct gve_rx_cnts *cnts)
{
	bool is_last_frag = !GVE_PKTCONT_BIT_IS_SET(desc->flags_seq);
	struct gve_rx_slot_page_info *page_info;
	u16 frag_size = be16_to_cpu(desc->len);
	struct gve_rx_ctx *ctx = &rx->ctx;
	union gve_rx_data_slot *data_slot;
	struct gve_priv *priv = rx->gve;
	struct sk_buff *skb = NULL;
	struct bpf_prog *xprog;
	struct xdp_buff xdp;
	dma_addr_t page_bus;
	void *va;

	u16 len = frag_size;
	struct napi_struct *napi = &priv->ntfy_blocks[rx->ntfy_id].napi;
	bool is_first_frag = ctx->frag_cnt == 0;

	bool is_only_frag = is_first_frag && is_last_frag;

	if (unlikely(ctx->drop_pkt))
		goto finish_frag;

	if (desc->flags_seq & GVE_RXF_ERR) {
		ctx->drop_pkt = true;
		cnts->desc_err_pkt_cnt++;
		napi_free_frags(napi);
		goto finish_frag;
	}

	if (unlikely(frag_size > rx->packet_buffer_size)) {
		netdev_warn(priv->dev, "Unexpected frag size %d, can't exceed %d, scheduling reset",
			    frag_size, rx->packet_buffer_size);
		ctx->drop_pkt = true;
		napi_free_frags(napi);
		gve_schedule_reset(rx->gve);
		goto finish_frag;
	}

	/* Prefetch two packet buffers ahead, we will need it soon. */
	page_info = &rx->data.page_info[(idx + 2) & rx->mask];
	va = page_info->page_address + page_info->page_offset;
	prefetch(page_info->page); /* Kernel page struct. */
	prefetch(va);              /* Packet header. */
	prefetch(va + 64);         /* Next cacheline too. */

	page_info = &rx->data.page_info[idx];
	data_slot = &rx->data.data_ring[idx];
	page_bus = (rx->data.raw_addressing) ?
		be64_to_cpu(data_slot->addr) - page_info->page_offset :
		rx->data.qpl->page_buses[idx];
	dma_sync_single_for_cpu(&priv->pdev->dev, page_bus,
				PAGE_SIZE, DMA_FROM_DEVICE);
	page_info->pad = is_first_frag ? GVE_RX_PAD : 0;
	len -= page_info->pad;
	frag_size -= page_info->pad;

	xprog = READ_ONCE(priv->xdp_prog);
	if (xprog && is_only_frag) {
		void *old_data;
		int xdp_act;

		xdp_init_buff(&xdp, rx->packet_buffer_size, &rx->xdp_rxq);
		xdp_prepare_buff(&xdp, page_info->page_address +
				 page_info->page_offset, GVE_RX_PAD,
				 len, false);
		old_data = xdp.data;
		xdp_act = bpf_prog_run_xdp(xprog, &xdp);
		if (xdp_act != XDP_PASS) {
			gve_xdp_done(priv, rx, &xdp, xprog, xdp_act);
			ctx->total_size += frag_size;
			goto finish_ok_pkt;
		}

		page_info->pad += xdp.data - old_data;
		len = xdp.data_end - xdp.data;

		u64_stats_update_begin(&rx->statss);
		rx->xdp_actions[XDP_PASS]++;
		u64_stats_update_end(&rx->statss);
	}

	skb = gve_rx_skb(priv, rx, page_info, napi, len,
			 data_slot, is_only_frag);
	if (!skb) {
		u64_stats_update_begin(&rx->statss);
		rx->rx_skb_alloc_fail++;
		u64_stats_update_end(&rx->statss);

		napi_free_frags(napi);
		ctx->drop_pkt = true;
		goto finish_frag;
	}
	ctx->total_size += frag_size;

	if (is_first_frag) {
		if (likely(feat & NETIF_F_RXCSUM)) {
			/* NIC passes up the partial sum */
			if (desc->csum)
				skb->ip_summed = CHECKSUM_COMPLETE;
			else
				skb->ip_summed = CHECKSUM_NONE;
			skb->csum = csum_unfold(desc->csum);
		}

		/* parse flags & pass relevant info up */
		if (likely(feat & NETIF_F_RXHASH) &&
		    gve_needs_rss(desc->flags_seq))
			skb_set_hash(skb, be32_to_cpu(desc->rss_hash),
				     gve_rss_type(desc->flags_seq));
	}

	if (is_last_frag) {
		skb_record_rx_queue(skb, rx->q_num);
		if (skb_is_nonlinear(skb))
			napi_gro_frags(napi);
		else
			napi_gro_receive(napi, skb);
		goto finish_ok_pkt;
	}

	goto finish_frag;

finish_ok_pkt:
	cnts->ok_pkt_bytes += ctx->total_size;
	cnts->ok_pkt_cnt++;
finish_frag:
	ctx->frag_cnt++;
	if (is_last_frag) {
		cnts->total_pkt_cnt++;
		cnts->cont_pkt_cnt += (ctx->frag_cnt > 1);
		gve_rx_ctx_clear(ctx);
	}
}