Re: [PATCH v3 07/11] dmaengine: switchtec-dma: disable channels before freeing on registration failure

[Frank Li]

On Mon, Jul 27, 2026 at 12:15:22PM -0600, Logan Gunthorpe wrote:
> When switchtec_dma_create() fails after channels have been added to
> dma_dev->channels (either from switchtec_dma_chans_enumerate()'s own
> error path, or from dma_async_device_register() failing), the channels
> are released and freed but never removed from dma_dev->channels.
>
> Add switchtec_dma_chans_disable() which disables interrupts and
> removes the channels from the list.. Call it before releasing and
> freeing channels in both error paths.
>
> Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
> Link: https://lore.kernel.org/dmaengine/20260717223431.625EE1F000E9@xxxxxxxxxxxxxxx
> Link: https://lore.kernel.org/dmaengine/20260721162822.05CDD1F000E9@xxxxxxxxxxxxxxx
> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> ---
>  drivers/dma/switchtec_dma.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/dma/switchtec_dma.c b/drivers/dma/switchtec_dma.c
> index 31feb2816e79..800d8ecd0717 100644
> --- a/drivers/dma/switchtec_dma.c
> +++ b/drivers/dma/switchtec_dma.c
> @@ -1184,6 +1184,20 @@ static void switchtec_dma_chans_free(struct switchtec_dma_dev *swdma_dev)
>  	kfree(swdma_dev->swdma_chans);
>  }
>
> +static void switchtec_dma_chans_disable(struct pci_dev *pdev,
> +					struct switchtec_dma_dev *swdma_dev)
> +{
> +	int i;
> +
> +	if (swdma_dev->chan_status_irq >= 0) {
> +		pci_free_irq(pdev, swdma_dev->chan_status_irq, swdma_dev);
> +		swdma_dev->chan_status_irq = -1;
> +	}
> +
> +	for (i = 0; i < swdma_dev->chan_cnt; i++)
> +		list_del(&swdma_dev->swdma_chans[i]->dma_chan.device_node);
> +}
> +

Maybe historic reason, it is not good to touch dma_chan::device_node.
Suppose some hepler function to manage channels.

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

>  static int switchtec_dma_chans_enumerate(struct switchtec_dma_dev *swdma_dev,
>  					 struct pci_dev *pdev, int chan_cnt)
>  {
> @@ -1217,6 +1231,7 @@ static int switchtec_dma_chans_enumerate(struct switchtec_dma_dev *swdma_dev,
>  	return chan_cnt;
>
>  err_exit:
> +	switchtec_dma_chans_disable(pdev, swdma_dev);
>  	switchtec_dma_chans_release(pdev, swdma_dev);
>  	switchtec_dma_chans_free(swdma_dev);
>
> @@ -1320,6 +1335,7 @@ static int switchtec_dma_create(struct pci_dev *pdev)
>  	return 0;
>
>  err_chans_release_exit:
> +	switchtec_dma_chans_disable(pdev, swdma_dev);
>  	switchtec_dma_chans_release(pdev, swdma_dev);
>  	switchtec_dma_chans_free(swdma_dev);
>
> --
> 2.47.3
>