target/linux/generic/patches-3.18/077-07-bgmac-simplify-rx-DMA-error-handling.patch

   1 From: Felix Fietkau <nbd@openwrt.org>
   2 Date: Sun, 12 Apr 2015 22:23:07 +0200
   3 Subject: [PATCH] bgmac: simplify rx DMA error handling
   4
   5 Unmap the DMA buffer before checking it. If an error occurs, free the
   6 buffer and allocate a new one. If allocation or mapping fails, retry as
   7 long as there is NAPI poll budget left (count every attempt instead of
   8 every frame).
   9
  10 Signed-off-by: Felix Fietkau <nbd@openwrt.org>
  11 ---
  12
  13 --- a/drivers/net/ethernet/broadcom/bgmac.c
  14 +++ b/drivers/net/ethernet/broadcom/bgmac.c
  15 @@ -404,51 +404,33 @@ static int bgmac_dma_rx_read(struct bgma
  16                 void *buf = slot->buf;
  17                 u16 len, flags;
  18
  19 -               /* Unmap buffer to make it accessible to the CPU */
  20 -               dma_sync_single_for_cpu(dma_dev, slot->dma_addr,
  21 -                                       BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
  22 -
  23 -               /* Get info from the header */
  24 -               len = le16_to_cpu(rx->len);
  25 -               flags = le16_to_cpu(rx->flags);
  26 +               if (++handled >= weight - 1) /* Should never be greater */
  27 +                       break;
  28
  29                 do {
  30 -                       dma_addr_t old_dma_addr = slot->dma_addr;
  31 -                       int err;
  32 +                       if (!slot->dma_addr)
  33 +                               break;
  34 +
  35 +                       /* Unmap buffer to make it accessible to the CPU */
  36 +                       dma_unmap_single(dma_dev, slot->dma_addr,
  37 +                                        BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
  38 +                       slot->dma_addr = 0;
  39 +
  40 +                       /* Get info from the header */
  41 +                       len = le16_to_cpu(rx->len);
  42 +                       flags = le16_to_cpu(rx->flags);
  43
  44                         /* Check for poison and drop or pass the packet */
  45                         if (len == 0xdead && flags == 0xbeef) {
  46                                 bgmac_err(bgmac, "Found poisoned packet at slot %d, DMA issue!\n",
  47                                           ring->start);
  48 -                               dma_sync_single_for_device(dma_dev,
  49 -                                                          slot->dma_addr,
  50 -                                                          BGMAC_RX_BUF_SIZE,
  51 -                                                          DMA_FROM_DEVICE);
  52 +                               put_page(virt_to_head_page(buf));
  53                                 break;
  54                         }
  55
  56                         /* Omit CRC. */
  57                         len -= ETH_FCS_LEN;
  58
  59 -                       /* Prepare new skb as replacement */
  60 -                       err = bgmac_dma_rx_skb_for_slot(bgmac, slot);
  61 -                       if (err) {
  62 -                               /* Poison the old skb */
  63 -                               rx->len = cpu_to_le16(0xdead);
  64 -                               rx->flags = cpu_to_le16(0xbeef);
  65 -
  66 -                               dma_sync_single_for_device(dma_dev,
  67 -                                                          slot->dma_addr,
  68 -                                                          BGMAC_RX_BUF_SIZE,
  69 -                                                          DMA_FROM_DEVICE);
  70 -                               break;
  71 -                       }
  72 -                       bgmac_dma_rx_setup_desc(bgmac, ring, ring->start);
  73 -
  74 -                       /* Unmap old skb, we'll pass it to the netfif */
  75 -                       dma_unmap_single(dma_dev, old_dma_addr,
  76 -                                        BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
  77 -
  78                         skb = build_skb(buf, BGMAC_RX_ALLOC_SIZE);
  79                         skb_put(skb, BGMAC_RX_FRAME_OFFSET +
  80                                 BGMAC_RX_BUF_OFFSET + len);
  81 @@ -458,14 +440,16 @@ static int bgmac_dma_rx_read(struct bgma
  82                         skb_checksum_none_assert(skb);
  83                         skb->protocol = eth_type_trans(skb, bgmac->net_dev);
  84                         napi_gro_receive(&bgmac->napi, skb);
  85 -                       handled++;
  86                 } while (0);
  87
  88 +               /* Prepare new skb as replacement */
  89 +               if (bgmac_dma_rx_skb_for_slot(bgmac, slot))
  90 +                       continue;
  91 +
  92 +               bgmac_dma_rx_setup_desc(bgmac, ring, ring->start);
  93 +
  94                 if (++ring->start >= BGMAC_RX_RING_SLOTS)
  95                         ring->start = 0;
  96 -
  97 -               if (handled >= weight) /* Should never be greater */
  98 -                       break;
  99         }
 100
 101         return handled;
 102 @@ -528,14 +512,14 @@ static void bgmac_dma_rx_ring_free(struc
 103
 104         for (i = 0; i < ring->num_slots; i++) {
 105                 slot = &ring->slots[i];
 106 -               if (!slot->buf)
 107 +               if (!slot->dma_addr)
 108                         continue;
 109
 110 -               if (slot->dma_addr)
 111 -                       dma_unmap_single(dma_dev, slot->dma_addr,
 112 -                                        BGMAC_RX_BUF_SIZE,
 113 -                                        DMA_FROM_DEVICE);
 114 +               dma_unmap_single(dma_dev, slot->dma_addr,
 115 +                                BGMAC_RX_BUF_SIZE,
 116 +                                DMA_FROM_DEVICE);
 117                 put_page(virt_to_head_page(slot->buf));
 118 +               slot->dma_addr = 0;
 119         }
 120  }
 121