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85 lines
3.2 KiB
Diff
85 lines
3.2 KiB
Diff
From 1f00fa355829b510beb900ce1136f40802e6076e Mon Sep 17 00:00:00 2001
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From: Camelia Groza <camelia.groza@nxp.com>
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Date: Mon, 10 Sep 2018 14:31:05 +0300
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Subject: [PATCH] sdk_dpaa: store the skb backpointer in the skb headroom
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The skb backpointer is stored right before the FMan buffer, in order to
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avoid overwriting. The memory area storing the backpointer was outside of
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the skb. This made it hard to guarantee its size.
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This patch changes the layout of the skb at buffer seed time: the area
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reserved for storing the skb backpointer is part of the skb's headroom.
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This makes it easier to track if the backpointer can be safely stored
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when recycling the buffer.
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Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
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---
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.../net/ethernet/freescale/sdk_dpaa/dpaa_eth_sg.c | 33 ++++++++++++++++------
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1 file changed, 24 insertions(+), 9 deletions(-)
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--- a/drivers/net/ethernet/freescale/sdk_dpaa/dpaa_eth_sg.c
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+++ b/drivers/net/ethernet/freescale/sdk_dpaa/dpaa_eth_sg.c
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@@ -82,8 +82,8 @@ static void dpa_bp_recycle_frag(struct d
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static int _dpa_bp_add_8_bufs(const struct dpa_bp *dpa_bp)
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{
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+ void *new_buf, *fman_buf;
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struct bm_buffer bmb[8];
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- void *new_buf;
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dma_addr_t addr;
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uint8_t i;
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struct device *dev = dpa_bp->dev;
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@@ -113,21 +113,37 @@ static int _dpa_bp_add_8_bufs(const stru
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if (unlikely(!new_buf))
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goto netdev_alloc_failed;
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- new_buf = PTR_ALIGN(new_buf + SMP_CACHE_BYTES, SMP_CACHE_BYTES);
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+ new_buf = PTR_ALIGN(new_buf, SMP_CACHE_BYTES);
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- skb = build_skb(new_buf, DPA_SKB_SIZE(dpa_bp->size) +
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- SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
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+ /* Apart from the buffer that will be used by the FMan, the
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+ * skb also guarantees enough space to hold the backpointer
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+ * in the headroom and the shared info at the end.
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+ */
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+ skb = build_skb(new_buf,
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+ SMP_CACHE_BYTES + DPA_SKB_SIZE(dpa_bp->size) +
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+ SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
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if (unlikely(!skb)) {
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put_page(virt_to_head_page(new_buf));
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goto build_skb_failed;
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}
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- /* Store the skb back-pointer before the start of the buffer.
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- * Otherwise it will be overwritten by the FMan.
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+ /* Reserve SMP_CACHE_BYTES in the skb's headroom to store the
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+ * backpointer. This area will not be synced to, or
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+ * overwritten by, the FMan.
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+ */
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+ skb_reserve(skb, SMP_CACHE_BYTES);
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+
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+ /* We don't sync the first SMP_CACHE_BYTES of the buffer to
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+ * the FMan. The skb backpointer is stored at the end of the
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+ * reserved headroom. Otherwise it will be overwritten by the
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+ * FMan.
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+ * The buffer synced with the FMan starts right after the
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+ * reserved headroom.
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*/
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- DPA_WRITE_SKB_PTR(skb, skbh, new_buf, -1);
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+ fman_buf = new_buf + SMP_CACHE_BYTES;
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+ DPA_WRITE_SKB_PTR(skb, skbh, fman_buf, -1);
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- addr = dma_map_single(dev, new_buf,
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+ addr = dma_map_single(dev, fman_buf,
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dpa_bp->size, DMA_BIDIRECTIONAL);
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if (unlikely(dma_mapping_error(dev, addr)))
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goto dma_map_failed;
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@@ -477,7 +493,6 @@ static struct sk_buff *__hot sg_fd_to_sk
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DMA_BIDIRECTIONAL);
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if (i == 0) {
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DPA_READ_SKB_PTR(skb, skbh, sg_vaddr, -1);
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- DPA_BUG_ON(skb->head != sg_vaddr);
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#ifdef CONFIG_FSL_DPAA_1588
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if (priv->tsu && priv->tsu->valid &&
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priv->tsu->hwts_rx_en_ioctl)
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