Re: [PATCHv3 03/15] dmaengine: fsldma: halt DMA engine before freeing resources

[Frank Li]

On Tue, Jun 09, 2026 at 03:19:14PM -0700, Rosen Penev wrote:
> When a channel is released (fsl_dma_free_chan_resources) or the driver is
> unbound (fsl_dma_chan_remove), the descriptor pool and channel resources
> are freed without stopping the DMA hardware first.  An active transfer
> could continue executing in the background, fetching descriptors or
> writing data to physical memory pages that have already been freed.
>
> Fix by calling dma_halt() in both paths before cleaning up, matching
> the pattern already used in fsl_dma_device_terminate_all().
>
> Assisted-by: opencode:big-pickle
> Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  drivers/dma/fsldma.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
> index 455d21d738de..1ba10d065278 100644
> --- a/drivers/dma/fsldma.c
> +++ b/drivers/dma/fsldma.c
> @@ -748,6 +748,7 @@ static void fsl_dma_free_chan_resources(struct dma_chan *dchan)
>
>  	chan_dbg(chan, "free all channel resources\n");
>  	spin_lock_bh(&chan->desc_lock);
> +	dma_halt(chan);
>  	fsldma_cleanup_descriptors(chan);
>  	fsldma_free_desc_list(chan, &chan->ld_pending);
>  	fsldma_free_desc_list(chan, &chan->ld_running);
> @@ -1207,6 +1208,10 @@ static int fsl_dma_chan_probe(struct fsldma_device *fdev,
>
>  static void fsl_dma_chan_remove(struct fsldma_chan *chan)
>  {
> +	spin_lock_bh(&chan->desc_lock);
> +	dma_halt(chan);
> +	spin_unlock_bh(&chan->desc_lock);
> +
>  	tasklet_kill(&chan->tasklet);
>  	irq_dispose_mapping(chan->irq);
>  	list_del(&chan->common.device_node);
> --
> 2.54.0
>