On 03-03-20, 14:05, Sebastian von Ohr wrote:
> The DMA transfer might finish just after checking the state with
> dma_cookie_status, but before the lock is acquired. Not checking
> for an empty list in xilinx_dma_tx_status may result in reading
> random data or data corruption when desc is written to. This can
> be reliably triggered by using dma_sync_wait to wait for DMA
> completion.
Appana, Radhey can you please test this..?
>
> Signed-off-by: Sebastian von Ohr <vonohr@xxxxxxxxxxx>
> ---
> drivers/dma/xilinx/xilinx_dma.c | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
> index a9c5d5cc9f2b..5d5f1d0ce16c 100644
> --- a/drivers/dma/xilinx/xilinx_dma.c
> +++ b/drivers/dma/xilinx/xilinx_dma.c
> @@ -1229,16 +1229,16 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
> return ret;
>
> spin_lock_irqsave(&chan->lock, flags);
> -
> - desc = list_last_entry(&chan->active_list,
> - struct xilinx_dma_tx_descriptor, node);
> - /*
> - * VDMA and simple mode do not support residue reporting, so the
> - * residue field will always be 0.
> - */
> - if (chan->has_sg && chan->xdev->dma_config->dmatype != XDMA_TYPE_VDMA)
> - residue = xilinx_dma_get_residue(chan, desc);
> -
> + if (!list_empty(&chan->active_list)) {
> + desc = list_last_entry(&chan->active_list,
> + struct xilinx_dma_tx_descriptor, node);
> + /*
> + * VDMA and simple mode do not support residue reporting, so the
> + * residue field will always be 0.
> + */
> + if (chan->has_sg && chan->xdev->dma_config->dmatype != XDMA_TYPE_VDMA)
> + residue = xilinx_dma_get_residue(chan, desc);
> + }
> spin_unlock_irqrestore(&chan->lock, flags);
>
> dma_set_residue(txstate, residue);
> --
> 2.17.1
--
~Vinod
