On Mon, Apr 17, 2023 at 9:33 PM Nikita Zhandarovich <
n.zhandarovich@xxxxxxxxxx> wrote:
> dma_request_slave_channel() may return NULL which will lead to
> NULL pointer dereference error in 'tmp_chan->private'.
>
> Correct this behaviour by, first, switching from deprecated function
> dma_request_slave_channel() to dma_request_chan(). Secondly, enable
> sanity check for the resuling value of dma_request_chan().
> Also, fix description that follows the enacted changes and that
> concerns the use of dma_request_slave_channel().
>
> Fixes: 706e2c881158 ("ASoC: fsl_asrc_dma: Reuse the dma channel if
> available in Back-End")
> Co-developed-by: Natalia Petrova <n.petrova@xxxxxxxxxx>
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>
>
Acked-by: Shengjiu Wang <shengjiu.wang@xxxxxxxxx>
Best regards
wang shengjiu
> ---
> sound/soc/fsl/fsl_asrc_dma.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/sound/soc/fsl/fsl_asrc_dma.c b/sound/soc/fsl/fsl_asrc_dma.c
> index 3b81a465814a..05a7d1588d20 100644
> --- a/sound/soc/fsl/fsl_asrc_dma.c
> +++ b/sound/soc/fsl/fsl_asrc_dma.c
> @@ -209,14 +209,19 @@ static int fsl_asrc_dma_hw_params(struct
> snd_soc_component *component,
> be_chan =
> soc_component_to_pcm(component_be)->chan[substream->stream];
> tmp_chan = be_chan;
> }
> - if (!tmp_chan)
> - tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" :
> "rx");
> + if (!tmp_chan) {
> + tmp_chan = dma_request_chan(dev_be, tx ? "tx" : "rx");
> + if (IS_ERR(tmp_chan)) {
> + dev_err(dev, "failed to request DMA channel for
> Back-End\n");
> + return -EINVAL;
> + }
> + }
>
> /*
> * An EDMA DEV_TO_DEV channel is fixed and bound with DMA event of
> each
> * peripheral, unlike SDMA channel that is allocated dynamically.
> So no
> * need to configure dma_request and dma_request2, but get
> dma_chan of
> - * Back-End device directly via dma_request_slave_channel.
> + * Back-End device directly via dma_request_chan.
> */
> if (!asrc->use_edma) {
> /* Get DMA request of Back-End */
>
