207 lines
6.3 KiB
Diff
207 lines
6.3 KiB
Diff
From e015593573b3e3f74bd8a63c05fa92902194a354 Mon Sep 17 00:00:00 2001
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From: Aleksander Jan Bajkowski <olek2@wp.pl>
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Date: Tue, 4 Jan 2022 16:11:44 +0100
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Subject: [PATCH 715/715] net: lantiq_xrx200: convert to build_skb
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We can increase the efficiency of rx path by using buffers to receive
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packets then build SKBs around them just before passing into the network
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stack. In contrast, preallocating SKBs too early reduces CPU cache
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efficiency.
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NAT Performance results on BT Home Hub 5A (kernel 5.10.89, mtu 1500):
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Down Up
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Before 577 Mbps 648 Mbps
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After 624 Mbps 695 Mbps
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Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
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Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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---
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drivers/net/ethernet/lantiq_xrx200.c | 56 ++++++++++++++++++----------
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1 file changed, 36 insertions(+), 20 deletions(-)
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--- a/drivers/net/ethernet/lantiq_xrx200.c
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+++ b/drivers/net/ethernet/lantiq_xrx200.c
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@@ -63,7 +63,11 @@ struct xrx200_chan {
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struct napi_struct napi;
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struct ltq_dma_channel dma;
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- struct sk_buff *skb[LTQ_DESC_NUM];
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+
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+ union {
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+ struct sk_buff *skb[LTQ_DESC_NUM];
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+ void *rx_buff[LTQ_DESC_NUM];
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+ };
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struct sk_buff *skb_head;
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struct sk_buff *skb_tail;
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@@ -78,6 +82,7 @@ struct xrx200_priv {
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struct xrx200_chan chan_rx;
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u16 rx_buf_size;
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+ u16 rx_skb_size;
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struct net_device *net_dev;
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struct device *dev;
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@@ -115,6 +120,12 @@ static int xrx200_buffer_size(int mtu)
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return round_up(xrx200_max_frame_len(mtu), 4 * XRX200_DMA_BURST_LEN);
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}
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+static int xrx200_skb_size(u16 buf_size)
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+{
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+ return SKB_DATA_ALIGN(buf_size + NET_SKB_PAD + NET_IP_ALIGN) +
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+ SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
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+}
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+
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/* drop all the packets from the DMA ring */
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static void xrx200_flush_dma(struct xrx200_chan *ch)
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{
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@@ -173,30 +184,29 @@ static int xrx200_close(struct net_devic
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return 0;
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}
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-static int xrx200_alloc_skb(struct xrx200_chan *ch)
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+static int xrx200_alloc_buf(struct xrx200_chan *ch, void *(*alloc)(unsigned int size))
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{
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- struct sk_buff *skb = ch->skb[ch->dma.desc];
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+ void *buf = ch->rx_buff[ch->dma.desc];
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struct xrx200_priv *priv = ch->priv;
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dma_addr_t mapping;
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int ret = 0;
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- ch->skb[ch->dma.desc] = netdev_alloc_skb_ip_align(priv->net_dev,
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- priv->rx_buf_size);
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- if (!ch->skb[ch->dma.desc]) {
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+ ch->rx_buff[ch->dma.desc] = alloc(priv->rx_skb_size);
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+ if (!ch->rx_buff[ch->dma.desc]) {
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ret = -ENOMEM;
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goto skip;
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}
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- mapping = dma_map_single(priv->dev, ch->skb[ch->dma.desc]->data,
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+ mapping = dma_map_single(priv->dev, ch->rx_buff[ch->dma.desc],
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priv->rx_buf_size, DMA_FROM_DEVICE);
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if (unlikely(dma_mapping_error(priv->dev, mapping))) {
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- dev_kfree_skb_any(ch->skb[ch->dma.desc]);
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- ch->skb[ch->dma.desc] = skb;
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+ skb_free_frag(ch->rx_buff[ch->dma.desc]);
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+ ch->rx_buff[ch->dma.desc] = buf;
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ret = -ENOMEM;
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goto skip;
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}
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- ch->dma.desc_base[ch->dma.desc].addr = mapping;
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+ ch->dma.desc_base[ch->dma.desc].addr = mapping + NET_SKB_PAD + NET_IP_ALIGN;
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/* Make sure the address is written before we give it to HW */
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wmb();
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skip:
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@@ -210,13 +220,14 @@ static int xrx200_hw_receive(struct xrx2
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{
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struct xrx200_priv *priv = ch->priv;
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struct ltq_dma_desc *desc = &ch->dma.desc_base[ch->dma.desc];
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- struct sk_buff *skb = ch->skb[ch->dma.desc];
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+ void *buf = ch->rx_buff[ch->dma.desc];
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u32 ctl = desc->ctl;
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int len = (ctl & LTQ_DMA_SIZE_MASK);
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struct net_device *net_dev = priv->net_dev;
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+ struct sk_buff *skb;
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int ret;
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- ret = xrx200_alloc_skb(ch);
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+ ret = xrx200_alloc_buf(ch, napi_alloc_frag);
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ch->dma.desc++;
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ch->dma.desc %= LTQ_DESC_NUM;
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@@ -227,19 +238,21 @@ static int xrx200_hw_receive(struct xrx2
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return ret;
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}
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+ skb = build_skb(buf, priv->rx_skb_size);
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+ skb_reserve(skb, NET_SKB_PAD);
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skb_put(skb, len);
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/* add buffers to skb via skb->frag_list */
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if (ctl & LTQ_DMA_SOP) {
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ch->skb_head = skb;
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ch->skb_tail = skb;
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+ skb_reserve(skb, NET_IP_ALIGN);
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} else if (ch->skb_head) {
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if (ch->skb_head == ch->skb_tail)
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skb_shinfo(ch->skb_tail)->frag_list = skb;
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else
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ch->skb_tail->next = skb;
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ch->skb_tail = skb;
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- skb_reserve(ch->skb_tail, -NET_IP_ALIGN);
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ch->skb_head->len += skb->len;
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ch->skb_head->data_len += skb->len;
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ch->skb_head->truesize += skb->truesize;
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@@ -395,12 +408,13 @@ xrx200_change_mtu(struct net_device *net
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struct xrx200_chan *ch_rx = &priv->chan_rx;
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int old_mtu = net_dev->mtu;
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bool running = false;
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- struct sk_buff *skb;
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+ void *buff;
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int curr_desc;
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int ret = 0;
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net_dev->mtu = new_mtu;
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priv->rx_buf_size = xrx200_buffer_size(new_mtu);
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+ priv->rx_skb_size = xrx200_skb_size(priv->rx_buf_size);
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if (new_mtu <= old_mtu)
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return ret;
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@@ -416,14 +430,15 @@ xrx200_change_mtu(struct net_device *net
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for (ch_rx->dma.desc = 0; ch_rx->dma.desc < LTQ_DESC_NUM;
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ch_rx->dma.desc++) {
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- skb = ch_rx->skb[ch_rx->dma.desc];
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- ret = xrx200_alloc_skb(ch_rx);
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+ buff = ch_rx->rx_buff[ch_rx->dma.desc];
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+ ret = xrx200_alloc_buf(ch_rx, netdev_alloc_frag);
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if (ret) {
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net_dev->mtu = old_mtu;
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priv->rx_buf_size = xrx200_buffer_size(old_mtu);
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+ priv->rx_skb_size = xrx200_skb_size(priv->rx_buf_size);
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break;
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}
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- dev_kfree_skb_any(skb);
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+ skb_free_frag(buff);
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}
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ch_rx->dma.desc = curr_desc;
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@@ -476,7 +491,7 @@ static int xrx200_dma_init(struct xrx200
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ltq_dma_alloc_rx(&ch_rx->dma);
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for (ch_rx->dma.desc = 0; ch_rx->dma.desc < LTQ_DESC_NUM;
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ch_rx->dma.desc++) {
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- ret = xrx200_alloc_skb(ch_rx);
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+ ret = xrx200_alloc_buf(ch_rx, netdev_alloc_frag);
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if (ret)
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goto rx_free;
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}
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@@ -511,7 +526,7 @@ rx_ring_free:
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/* free the allocated RX ring */
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for (i = 0; i < LTQ_DESC_NUM; i++) {
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if (priv->chan_rx.skb[i])
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- dev_kfree_skb_any(priv->chan_rx.skb[i]);
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+ skb_free_frag(priv->chan_rx.rx_buff[i]);
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}
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rx_free:
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@@ -528,7 +543,7 @@ static void xrx200_hw_cleanup(struct xrx
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/* free the allocated RX ring */
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for (i = 0; i < LTQ_DESC_NUM; i++)
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- dev_kfree_skb_any(priv->chan_rx.skb[i]);
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+ skb_free_frag(priv->chan_rx.rx_buff[i]);
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}
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static int xrx200_probe(struct platform_device *pdev)
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@@ -553,6 +568,7 @@ static int xrx200_probe(struct platform_
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net_dev->min_mtu = ETH_ZLEN;
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net_dev->max_mtu = XRX200_DMA_DATA_LEN - xrx200_max_frame_len(0);
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priv->rx_buf_size = xrx200_buffer_size(ETH_DATA_LEN);
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+ priv->rx_skb_size = xrx200_skb_size(priv->rx_buf_size);
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/* load the memory ranges */
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priv->pmac_reg = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
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