[PATCH] net: mvneta: fix DMA buffer unmapping in mvneta_rx()

[Oren Laskin]

This fixes the regression we saw.

Tested-by: Oren Laskin <oren at igneous.io>

On Tue, Sep 15, 2015 at 1:41 PM, Simon Guinot <simon.guinot at sequanux.org> wrote:
> This patch fixes a regression introduced by the commit a84e32894191
> ("net: mvneta: fix refilling for Rx DMA buffers"). Due to this commit
> the newly allocated Rx buffers are DMA-unmapped in place of those passed
> to the networking stack. Obviously, this causes data corruptions.
>
> This patch fixes the issue by ensuring that the right Rx buffers are
> DMA-unmapped.
>
> Reported-by: Oren Laskin <oren at igneous.io>
> Signed-off-by: Simon Guinot <simon.guinot at sequanux.org>
> Fixes: a84e32894191 ("net: mvneta: fix refilling for Rx DMA buffers")
> Cc: <stable at vger.kernel.org> # v3.8+
> ---
>  drivers/net/ethernet/marvell/mvneta.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index 62e48bc0cb23..03e052a1cf5a 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -1479,6 +1479,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
>                 struct mvneta_rx_desc *rx_desc = mvneta_rxq_next_desc_get(rxq);
>                 struct sk_buff *skb;
>                 unsigned char *data;
> +               dma_addr_t phys_addr;
>                 u32 rx_status;
>                 int rx_bytes, err;
>
> @@ -1486,6 +1487,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
>                 rx_status = rx_desc->status;
>                 rx_bytes = rx_desc->data_size - (ETH_FCS_LEN + MVNETA_MH_SIZE);
>                 data = (unsigned char *)rx_desc->buf_cookie;
> +               phys_addr = rx_desc->buf_phys_addr;
>
>                 if (!mvneta_rxq_desc_is_first_last(rx_status) ||
>                     (rx_status & MVNETA_RXD_ERR_SUMMARY)) {
> @@ -1534,7 +1536,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
>                 if (!skb)
>                         goto err_drop_frame;
>
> -               dma_unmap_single(dev->dev.parent, rx_desc->buf_phys_addr,
> +               dma_unmap_single(dev->dev.parent, phys_addr,
>                                  MVNETA_RX_BUF_SIZE(pp->pkt_size), DMA_FROM_DEVICE);
>
>                 rcvd_pkts++;
> --
> 2.1.4
>