Commit 9e5269a9 authored by Shay Agroskin's avatar Shay Agroskin Committed by David S. Miller
Browse files

net: ena: use build_skb() in RX path 



This patch converts the RX path to use build_skb() for packets larger
than copybreak (set to 256 by default). This function makes the first
descriptor's page to be the linear part of the sk_buff struct buffer.

Also remove the SKB description from the README since most of it no
longer relevant and the parts that are left don't add information.

Signed-off-by: default avatarShay Agroskin <shayagr@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 091d0e85

drivers/net/ethernet/amazon/ena/ena_netdev.c

+41 −25
Original line number Diff line number Diff line
@@ -529,7 +529,7 @@ static void ena_xdp_exchange_program_rx_in_range(struct ena_adapter *adapter, 
			rx_ring->rx_headroom = XDP_PACKET_HEADROOM;

		} else {

			ena_xdp_unregister_rxq_info(rx_ring);

			rx_ring->rx_headroom = 0;

			rx_ring->rx_headroom = NET_SKB_PAD;

		}

	}

}
@@ -720,6 +720,7 @@ static void ena_init_io_rings(struct ena_adapter *adapter, 
			rxr->smoothed_interval =

				ena_com_get_nonadaptive_moderation_interval_rx(ena_dev);

			rxr->empty_rx_queue = 0;

			rxr->rx_headroom = NET_SKB_PAD;

			adapter->ena_napi[i].dim.mode = DIM_CQ_PERIOD_MODE_START_FROM_EQE;

			rxr->xdp_ring = &adapter->tx_ring[i + adapter->num_io_queues];

		}
@@ -982,6 +983,7 @@ static int ena_alloc_rx_page(struct ena_ring *rx_ring, 
	struct ena_com_buf *ena_buf;

	struct page *page;

	dma_addr_t dma;

	int tailroom;



	/* restore page offset value in case it has been changed by device */

	rx_info->page_offset = headroom;
@@ -1012,10 +1014,12 @@ static int ena_alloc_rx_page(struct ena_ring *rx_ring, 
	netif_dbg(rx_ring->adapter, rx_status, rx_ring->netdev,

		  "Allocate page %p, rx_info %p\n", page, rx_info);



	tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));



	rx_info->page = page;

	ena_buf = &rx_info->ena_buf;

	ena_buf->paddr = dma + headroom;

	ena_buf->len = ENA_PAGE_SIZE - headroom;

	ena_buf->len = ENA_PAGE_SIZE - headroom - tailroom;



	return 0;

}
@@ -1381,21 +1385,23 @@ static int ena_clean_tx_irq(struct ena_ring *tx_ring, u32 budget) 
	return tx_pkts;

}



static struct sk_buff *ena_alloc_skb(struct ena_ring *rx_ring, bool frags)

static struct sk_buff *ena_alloc_skb(struct ena_ring *rx_ring, void *first_frag)

{

	struct sk_buff *skb;



	if (frags)

		skb = napi_get_frags(rx_ring->napi);

	else

	if (!first_frag)

		skb = netdev_alloc_skb_ip_align(rx_ring->netdev,

						rx_ring->rx_copybreak);

	else

		skb = build_skb(first_frag, ENA_PAGE_SIZE);



	if (unlikely(!skb)) {

		ena_increase_stat(&rx_ring->rx_stats.skb_alloc_fail, 1,

				  &rx_ring->syncp);



		netif_dbg(rx_ring->adapter, rx_err, rx_ring->netdev,

			  "Failed to allocate skb. frags: %d\n", frags);

			  "Failed to allocate skb. first_frag %s\n",

			  first_frag ? "provided" : "not provided");

		return NULL;

	}
@@ -1410,7 +1416,9 @@ static struct sk_buff *ena_rx_skb(struct ena_ring *rx_ring, 
	struct sk_buff *skb;

	struct ena_rx_buffer *rx_info;

	u16 len, req_id, buf = 0;

	void *va;

	void *page_addr;

	u32 page_offset;

	void *data_addr;



	len = ena_bufs[buf].len;

	req_id = ena_bufs[buf].req_id;
@@ -1428,12 +1436,14 @@ static struct sk_buff *ena_rx_skb(struct ena_ring *rx_ring, 
		  rx_info, rx_info->page);



	/* save virt address of first buffer */

	va = page_address(rx_info->page) + rx_info->page_offset;

	page_addr = page_address(rx_info->page);

	page_offset = rx_info->page_offset;

	data_addr = page_addr + page_offset;



	prefetch(va);

	prefetch(data_addr);



	if (len <= rx_ring->rx_copybreak) {

		skb = ena_alloc_skb(rx_ring, false);

		skb = ena_alloc_skb(rx_ring, NULL);

		if (unlikely(!skb))

			return NULL;
@@ -1446,7 +1456,7 @@ static struct sk_buff *ena_rx_skb(struct ena_ring *rx_ring, 
					dma_unmap_addr(&rx_info->ena_buf, paddr),

					len,

					DMA_FROM_DEVICE);

		skb_copy_to_linear_data(skb, va, len);

		skb_copy_to_linear_data(skb, data_addr, len);

		dma_sync_single_for_device(rx_ring->dev,

					   dma_unmap_addr(&rx_info->ena_buf, paddr),

					   len,
@@ -1460,16 +1470,18 @@ static struct sk_buff *ena_rx_skb(struct ena_ring *rx_ring, 
		return skb;

	}



	skb = ena_alloc_skb(rx_ring, true);

	ena_unmap_rx_buff(rx_ring, rx_info);



	skb = ena_alloc_skb(rx_ring, page_addr);

	if (unlikely(!skb))

		return NULL;



	do {

		ena_unmap_rx_buff(rx_ring, rx_info);



		skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, rx_info->page,

				rx_info->page_offset, len, ENA_PAGE_SIZE);

	/* Populate skb's linear part */

	skb_reserve(skb, page_offset);

	skb_put(skb, len);

	skb->protocol = eth_type_trans(skb, rx_ring->netdev);



	do {

		netif_dbg(rx_ring->adapter, rx_status, rx_ring->netdev,

			  "RX skb updated. len %d. data_len %d\n",

			  skb->len, skb->data_len);
@@ -1488,6 +1500,12 @@ static struct sk_buff *ena_rx_skb(struct ena_ring *rx_ring, 
		req_id = ena_bufs[buf].req_id;



		rx_info = &rx_ring->rx_buffer_info[req_id];



		ena_unmap_rx_buff(rx_ring, rx_info);



		skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, rx_info->page,

				rx_info->page_offset, len, ENA_PAGE_SIZE);



	} while (1);



	return skb;
@@ -1700,14 +1718,12 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi, 


		skb_record_rx_queue(skb, rx_ring->qid);



		if (rx_ring->ena_bufs[0].len <= rx_ring->rx_copybreak) {

			total_len += rx_ring->ena_bufs[0].len;

		if (rx_ring->ena_bufs[0].len <= rx_ring->rx_copybreak)

			rx_copybreak_pkt++;

			napi_gro_receive(napi, skb);

		} else {



		total_len += skb->len;

			napi_gro_frags(napi);

		}



		napi_gro_receive(napi, skb);



		res_budget--;

	} while (likely(res_budget));