| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame] | 1 | From 1f00fa355829b510beb900ce1136f40802e6076e Mon Sep 17 00:00:00 2001 |
| 2 | From: Camelia Groza <camelia.groza@nxp.com> |
| 3 | Date: Mon, 10 Sep 2018 14:31:05 +0300 |
| 4 | Subject: [PATCH] sdk_dpaa: store the skb backpointer in the skb headroom |
| 5 | |
| 6 | The skb backpointer is stored right before the FMan buffer, in order to |
| 7 | avoid overwriting. The memory area storing the backpointer was outside of |
| 8 | the skb. This made it hard to guarantee its size. |
| 9 | |
| 10 | This patch changes the layout of the skb at buffer seed time: the area |
| 11 | reserved for storing the skb backpointer is part of the skb's headroom. |
| 12 | This makes it easier to track if the backpointer can be safely stored |
| 13 | when recycling the buffer. |
| 14 | |
| 15 | Signed-off-by: Camelia Groza <camelia.groza@nxp.com> |
| 16 | --- |
| 17 | .../net/ethernet/freescale/sdk_dpaa/dpaa_eth_sg.c | 33 ++++++++++++++++------ |
| 18 | 1 file changed, 24 insertions(+), 9 deletions(-) |
| 19 | |
| 20 | --- a/drivers/net/ethernet/freescale/sdk_dpaa/dpaa_eth_sg.c |
| 21 | +++ b/drivers/net/ethernet/freescale/sdk_dpaa/dpaa_eth_sg.c |
| 22 | @@ -82,8 +82,8 @@ static void dpa_bp_recycle_frag(struct d |
| 23 | |
| 24 | static int _dpa_bp_add_8_bufs(const struct dpa_bp *dpa_bp) |
| 25 | { |
| 26 | + void *new_buf, *fman_buf; |
| 27 | struct bm_buffer bmb[8]; |
| 28 | - void *new_buf; |
| 29 | dma_addr_t addr; |
| 30 | uint8_t i; |
| 31 | struct device *dev = dpa_bp->dev; |
| 32 | @@ -113,21 +113,37 @@ static int _dpa_bp_add_8_bufs(const stru |
| 33 | |
| 34 | if (unlikely(!new_buf)) |
| 35 | goto netdev_alloc_failed; |
| 36 | - new_buf = PTR_ALIGN(new_buf + SMP_CACHE_BYTES, SMP_CACHE_BYTES); |
| 37 | + new_buf = PTR_ALIGN(new_buf, SMP_CACHE_BYTES); |
| 38 | |
| 39 | - skb = build_skb(new_buf, DPA_SKB_SIZE(dpa_bp->size) + |
| 40 | - SKB_DATA_ALIGN(sizeof(struct skb_shared_info))); |
| 41 | + /* Apart from the buffer that will be used by the FMan, the |
| 42 | + * skb also guarantees enough space to hold the backpointer |
| 43 | + * in the headroom and the shared info at the end. |
| 44 | + */ |
| 45 | + skb = build_skb(new_buf, |
| 46 | + SMP_CACHE_BYTES + DPA_SKB_SIZE(dpa_bp->size) + |
| 47 | + SKB_DATA_ALIGN(sizeof(struct skb_shared_info))); |
| 48 | if (unlikely(!skb)) { |
| 49 | put_page(virt_to_head_page(new_buf)); |
| 50 | goto build_skb_failed; |
| 51 | } |
| 52 | |
| 53 | - /* Store the skb back-pointer before the start of the buffer. |
| 54 | - * Otherwise it will be overwritten by the FMan. |
| 55 | + /* Reserve SMP_CACHE_BYTES in the skb's headroom to store the |
| 56 | + * backpointer. This area will not be synced to, or |
| 57 | + * overwritten by, the FMan. |
| 58 | + */ |
| 59 | + skb_reserve(skb, SMP_CACHE_BYTES); |
| 60 | + |
| 61 | + /* We don't sync the first SMP_CACHE_BYTES of the buffer to |
| 62 | + * the FMan. The skb backpointer is stored at the end of the |
| 63 | + * reserved headroom. Otherwise it will be overwritten by the |
| 64 | + * FMan. |
| 65 | + * The buffer synced with the FMan starts right after the |
| 66 | + * reserved headroom. |
| 67 | */ |
| 68 | - DPA_WRITE_SKB_PTR(skb, skbh, new_buf, -1); |
| 69 | + fman_buf = new_buf + SMP_CACHE_BYTES; |
| 70 | + DPA_WRITE_SKB_PTR(skb, skbh, fman_buf, -1); |
| 71 | |
| 72 | - addr = dma_map_single(dev, new_buf, |
| 73 | + addr = dma_map_single(dev, fman_buf, |
| 74 | dpa_bp->size, DMA_BIDIRECTIONAL); |
| 75 | if (unlikely(dma_mapping_error(dev, addr))) |
| 76 | goto dma_map_failed; |
| 77 | @@ -477,7 +493,6 @@ static struct sk_buff *__hot sg_fd_to_sk |
| 78 | DMA_BIDIRECTIONAL); |
| 79 | if (i == 0) { |
| 80 | DPA_READ_SKB_PTR(skb, skbh, sg_vaddr, -1); |
| 81 | - DPA_BUG_ON(skb->head != sg_vaddr); |
| 82 | #ifdef CONFIG_FSL_DPAA_1588 |
| 83 | if (priv->tsu && priv->tsu->valid && |
| 84 | priv->tsu->hwts_rx_en_ioctl) |