On Mon, Jan 30, 2017 at 9:27 PM, Jakub Kicinski <kubak...@wp.pl> wrote:
> On Mon, 30 Jan 2017 20:49:35 -0500, Michael Chan wrote:
>> +static int bnxt_xmit_xdp(struct bnxt *bp, struct bnxt_napi *bnapi,
>> + struct page *page, dma_addr_t mapping, u32 offset,
>> + u32 len)
>> +{
>> + struct bnxt_tx_ring_info *txr = bnapi->tx_ring;
>> + struct bnxt_sw_tx_bd *tx_buf;
>> + struct tx_bd_ext *txbd1;
>> + struct tx_bd *txbd;
>> + u32 flags;
>> + u16 prod;
>> +
>> + if (bnxt_tx_avail(bp, txr) < 2)
>> + return -ENOSPC;
>> +
>> + prod = txr->tx_prod;
>> + txbd = &txr->tx_desc_ring[TX_RING(prod)][TX_IDX(prod)];
>> +
>> + tx_buf = &txr->tx_buf_ring[prod];
>> + tx_buf->page = page;
>> + dma_unmap_addr_set(tx_buf, mapping, mapping);
>> + flags = (len << TX_BD_LEN_SHIFT) | TX_BD_TYPE_LONG_TX_BD |
>> + (2 << TX_BD_FLAGS_BD_CNT_SHIFT) | TX_BD_FLAGS_PACKET_END |
>> + bnxt_lhint_arr[len >> 9];
>> + txbd->tx_bd_len_flags_type = cpu_to_le32(flags);
>> + txbd->tx_bd_opaque = prod;
>> + txbd->tx_bd_haddr = cpu_to_le64(mapping + offset);
>> +
>> + prod = NEXT_TX(prod);
>> + txbd1 = (struct tx_bd_ext *)
>> + &txr->tx_desc_ring[TX_RING(prod)][TX_IDX(prod)];
>> +
>> + txbd1->tx_bd_hsize_lflags = cpu_to_le32(0);
>> + txbd1->tx_bd_mss = cpu_to_le32(0);
>> + txbd1->tx_bd_cfa_action = cpu_to_le32(0);
>> + txbd1->tx_bd_cfa_meta = cpu_to_le32(0);
>> +
>> + prod = NEXT_TX(prod);
>> + txr->tx_prod = prod;
>> + return 0;
>> +}
>
> Are you not lacking DMA syncs in general? You map the buffers
> bidirectionally, but I failed to find any dma_syncs. I would expect
> one before you run xdp and one before you TX because packet could have
> been modified. What am I missing?
You are right. I missed the DMA syncs.
