Re: [PATCH] dmaengine: sprd-dma: handle runtime PM get failure

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] IRQ handler is registered before IO memory is mapped and virtual channels are initialized.
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--- Patch [1]: [PATCH] dmaengine: sprd-dma: handle runtime PM get failure ---
commit 7b4114d448d81c577f92d85ac8c943dc9f9107c9
Author: jiawen <[email protected]>

dmaengine: sprd-dma: handle runtime PM get failure

Route failed runtime-PM acquisition through its existing cleanup path.

Release and disable runtime PM before continuing with the hardware
teardown, so an unsuccessful pm_runtime_get_sync() does not leave
runtime PM enabled.

> diff --git a/drivers/dma/sprd-dma.c b/drivers/dma/sprd-dma.c
> index 087fea3af2e41..19b32a23c882d 100644
> --- a/drivers/dma/sprd-dma.c
> +++ b/drivers/dma/sprd-dma.c
> @@ -1212,7 +1212,7 @@ static int sprd_dma_probe(struct platform_device *pdev)
>  
>  	ret = pm_runtime_get_sync(&pdev->dev);

[Severity: High]
This isn't a bug introduced by this patch, but I noticed a pre-existing
issue earlier in sprd_dma_probe() where the IRQ handler is registered
before sdev->glb_base is mapped:

    ret = devm_request_irq(&pdev->dev, sdev->irq, dma_irq_handle,
                   0, "sprd_dma", (void *)sdev);
    ...
    sdev->glb_base = devm_platform_ioremap_resource(pdev, 0);

If an interrupt is pending from a previous kernel (e.g. kexec) or a
bootloader, the unmasked interrupt could cause dma_irq_handle() to
execute immediately.

Because the handler attempts to read from glb_base:

    u32 irq_status = readl(sdev->glb_base + SPRD_DMA_GLB_INT_MSK_STS);

could this cause a NULL pointer dereference and subsequent kernel panic
if the hardware asserts an interrupt before initialization completes?

>  	if (ret < 0)
> -		goto err_rpm;
> +		goto err_register;
>  
>  	ret = dma_async_device_register(&sdev->dma_dev);
[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1