On 2018-08-03 10:19, Huang Shijie wrote:
> Use dmaenginem_async_device_register to simplify the code:
>    remove dma_async_device_unregister
> 
> Signed-off-by: Huang Shijie <[email protected]>
> ---
>  drivers/dma/ti/cppi41.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/dma/ti/cppi41.c b/drivers/dma/ti/cppi41.c
> index 1497da367710..d2998a19ed2e 100644
> --- a/drivers/dma/ti/cppi41.c
> +++ b/drivers/dma/ti/cppi41.c
> @@ -1096,21 +1096,19 @@ static int cppi41_dma_probe(struct platform_device 
> *pdev)
>               goto err_chans;
>       cdd->irq = irq;
>  
> -     ret = dma_async_device_register(&cdd->ddev);
> +     ret = dmaenginem_async_device_register(&cdd->ddev);
>       if (ret)
>               goto err_chans;
>  
>       ret = of_dma_controller_register(dev->of_node,
>                       cppi41_dma_xlate, &cpp41_dma_info);
>       if (ret)
> -             goto err_of;
> +             goto err_chans;
>  
>       pm_runtime_mark_last_busy(dev);
>       pm_runtime_put_autosuspend(dev);
>  
>       return 0;
> -err_of:
> -     dma_async_device_unregister(&cdd->ddev);
>  err_chans:
>       deinit_cppi41(dev, cdd);
>  err_init_cppi:
> @@ -1132,7 +1130,6 @@ static int cppi41_dma_remove(struct platform_device 
> *pdev)
>               dev_err(&pdev->dev, "%s could not pm_runtime_get: %i\n",
>                       __func__, error);
>       of_dma_controller_free(pdev->dev.of_node);
> -     dma_async_device_unregister(&cdd->ddev);

If I read the code right then this is not safe.
We would have deinitalized cppi41 driver which is not functional, but we
will still have the dma device registered and if a channel is requested
we will have kernel crash.

It falls in the same case as omap-dma, edma.

>  
>       devm_free_irq(&pdev->dev, cdd->irq, cdd);
>       deinit_cppi41(&pdev->dev, cdd);
> 

- Péter

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