Re: [PATCH v2 net 4/6] net: mvneta: fix error path for building skb

[Simon Guinot]

On Thu, Nov 26, 2015 at 07:08:11PM +0100, Marcin Wojtas wrote:
> In the actual RX processing, there is same error path for both descriptor
> ring refilling and building skb fails. This is not correct, because after
> successful refill, the ring is already updated with newly allocated
> buffer. Then, in case of build_skb() fail, hitherto code left the original
> buffer unmapped.
> 
> This patch fixes above situation by swapping error check of skb build with
> DMA-unmap of original buffer.
> 
> Signed-off-by: Marcin Wojtas <mw@xxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.2+
> Fixes a84e32894191 ("net: mvneta: fix refilling for Rx DMA buffers")
> ---
>  drivers/net/ethernet/marvell/mvneta.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 

Acked-by: Simon Guinot <simon.guinot@xxxxxxxxxxxx>

Thanks,

Simon

> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index 0c3d923..62cf971 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -1580,12 +1580,16 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
>  		}
>  
>  		skb = build_skb(data, pp->frag_size > PAGE_SIZE ? 0 : pp->frag_size);
> -		if (!skb)
> -			goto err_drop_frame;
>  
> +		/* After refill old buffer has to be unmapped regardless
> +		 * the skb is successfully built or not.
> +		 */
>  		dma_unmap_single(dev->dev.parent, phys_addr,
>  				 MVNETA_RX_BUF_SIZE(pp->pkt_size), DMA_FROM_DEVICE);
>  
> +		if (!skb)
> +			goto err_drop_frame;
> +
>  		rcvd_pkts++;
>  		rcvd_bytes += rx_bytes;
>  
> -- 
> 1.8.3.1
> 
> 
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