Re: [PATCH 3/7] net: stmmac: Check for DMA mapping errors

[Mikko Perttunen]

On 23.02.2017 19:24, Thierry Reding wrote:
> From: Thierry Reding <treding@xxxxxxxxxx>
>
> When DMA mapping an SKB fragment, the mapping must be checked for
> errors, otherwise the DMA debug code will complain upon unmap.
>
> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 6b7a5ce19589..d7387919bdb6 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -2072,6 +2072,8 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
>  		des = skb_frag_dma_map(priv->device, frag, 0,
>  				       skb_frag_size(frag),
>  				       DMA_TO_DEVICE);
> +		if (dma_mapping_error(priv->device, des))
> +			goto dma_map_err;

If this map fails, we should also unmap the previously mapped fragments 
and the separate mapping made using dma_map_single.

>  		stmmac_tso_allocator(priv, des, skb_frag_size(frag),
>  				     (i == nfrags - 1));