On 2023-12-14 13:31, Michael Chan wrote:
> From: Andy Gospodarek <andrew.gospodarek@xxxxxxxxxxxx>
>
> Remove double-mapping of DMA buffers as it can prevent page pool entries
> from being freed. Mapping is managed by page pool infrastructure and
> was previously managed by the driver in __bnxt_alloc_rx_page before
> allowing the page pool infrastructure to manage it.
>
> Fixes: 578fcfd26e2a ("bnxt_en: Let the page pool manage the DMA mapping")
> Reviewed-by: Somnath Kotur <somnath.kotur@xxxxxxxxxxxx>
> Signed-off-by: Andy Gospodarek <andrew.gospodarek@xxxxxxxxxxxx>
> Signed-off-by: Michael Chan <michael.chan@xxxxxxxxxxxx>
> ---
> drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c | 11 ++---------
> 1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
> index 96f5ca778c67..8cb9a99154aa 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
> @@ -59,7 +59,6 @@ struct bnxt_sw_tx_bd *bnxt_xmit_bd(struct bnxt *bp,
> for (i = 0; i < num_frags ; i++) {
> skb_frag_t *frag = &sinfo->frags[i];
> struct bnxt_sw_tx_bd *frag_tx_buf;
> - struct pci_dev *pdev = bp->pdev;
> dma_addr_t frag_mapping;
> int frag_len;
>
> @@ -73,16 +72,10 @@ struct bnxt_sw_tx_bd *bnxt_xmit_bd(struct bnxt *bp,
> txbd = &txr->tx_desc_ring[TX_RING(prod)][TX_IDX(prod)];
>
> frag_len = skb_frag_size(frag);
> - frag_mapping = skb_frag_dma_map(&pdev->dev, frag, 0,
> - frag_len, DMA_TO_DEVICE);
> -
> - if (unlikely(dma_mapping_error(&pdev->dev, frag_mapping)))
> - return NULL;
> -
> - dma_unmap_addr_set(frag_tx_buf, mapping, frag_mapping);
If this is no longer set, what would happen to dma_unmap_single() in
bnxt_tx_int_xdp() that is then reading `mapping` via dma_unmap_addr()?
> -
> flags = frag_len << TX_BD_LEN_SHIFT;
> txbd->tx_bd_len_flags_type = cpu_to_le32(flags);
> + frag_mapping = page_pool_get_dma_addr(skb_frag_page(frag)) +
> + skb_frag_off(frag);
> txbd->tx_bd_haddr = cpu_to_le64(frag_mapping);
>
> len = frag_len;
