Re: [PATCH] media: rkvdec: Fix an error handling path in rkvdec_probe()

[Christophe JAILLET]

Le 29/07/2025 à 00:50, Nicolas Dufresne a écrit :
> Hi,
>
> Le dimanche 27 juillet 2025 à 12:02 +0200, Christophe JAILLET a écrit :
> > If an error occurs after a successful iommu_paging_domain_alloc() call, it
> > should be undone by a corresponding iommu_domain_free() call, as already
> > done in the remove function.
> >
> > Fixes: ff8c5622f9f7 ("media: rkvdec: Restore iommu addresses on errors")
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> > Compile tested only
> > ---
> >   drivers/media/platform/rockchip/rkvdec/rkvdec.c | 11 ++++++++---
> >   1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> > b/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> > index d707088ec0dc..eb0d41f85d89 100644
> > --- a/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> > +++ b/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> > @@ -1169,15 +1169,17 @@ static int rkvdec_probe(struct platform_device *pdev)
> >   	vb2_dma_contig_set_max_seg_size(&pdev->dev, DMA_BIT_MASK(32));
> >   
> >   	irq = platform_get_irq(pdev, 0);
> > -	if (irq <= 0)
> > -		return -ENXIO;
> > +	if (irq <= 0) {
> > +		ret = -ENXIO;
> > +		goto err_free_domain;
> > +	}
> >   
> >   	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
> >   					rkvdec_irq_handler, IRQF_ONESHOT,
> >   					dev_name(&pdev->dev), rkvdec);
> >   	if (ret) {
> >   		dev_err(&pdev->dev, "Could not request vdec IRQ\n");
> > -		return ret;
> > +		goto err_free_domain;
> >   	}
> >   
> >   	pm_runtime_set_autosuspend_delay(&pdev->dev, 100);
>
> Have you considered moving the allocation of the domain right above the above
> line instead ? The empty domain can't possibly be used unless the probe have
> fully completed.

That would not change things much. We still need to handle 
rkvdec_v4l2_init() failure a few lines below.

If it is correct to move it at the very end of the function, after 
rkvdec_v4l2_init(), then the patch would be simpler.


Honestly, I'm not very confident with it. request_threaded_irq() 
documentation states that "From the point this call is made your handler 
function may be invoked."
And rkvdec_irq_handler() may call rkvdec_iommu_restore() which uses 
empty_domain.

Not sure if I'm right and if this can happen, but the existing order 
looks safer to me.


That said, if it is fine for you, I can send a v2.


This would be:

diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec.c 
b/drivers/media/platform/rockchip/rkvdec/rkvdec.c
index d707088ec0dc..6eae10e16c73 100644
--- a/drivers/media/platform/rockchip/rkvdec/rkvdec.c
+++ b/drivers/media/platform/rockchip/rkvdec/rkvdec.c
@@ -1159,13 +1159,6 @@ static int rkvdec_probe(struct platform_device *pdev)
                return ret;
        }

-       if (iommu_get_domain_for_dev(&pdev->dev)) {
-               rkvdec->empty_domain = 
iommu_paging_domain_alloc(rkvdec->dev);
-
-               if (!rkvdec->empty_domain)
-                       dev_warn(rkvdec->dev, "cannot alloc new empty 
domain\n");
-       }
-
        vb2_dma_contig_set_max_seg_size(&pdev->dev, DMA_BIT_MASK(32));

        irq = platform_get_irq(pdev, 0);
@@ -1188,6 +1181,13 @@ static int rkvdec_probe(struct platform_device *pdev)
        if (ret)
                goto err_disable_runtime_pm;

+       if (iommu_get_domain_for_dev(&pdev->dev)) {
+               rkvdec->empty_domain = 
iommu_paging_domain_alloc(rkvdec->dev);
+
+               if (!rkvdec->empty_domain)
+                       dev_warn(rkvdec->dev, "cannot alloc new empty 
domain\n");
+       }
+
        return 0;

 err_disable_runtime_pm:


CJ

> Nicolas
>
> > @@ -1193,6 +1195,9 @@ static int rkvdec_probe(struct platform_device *pdev)
> >   err_disable_runtime_pm:
> >   	pm_runtime_dont_use_autosuspend(&pdev->dev);
> >   	pm_runtime_disable(&pdev->dev);
> > +err_free_domain:
> > +	if (rkvdec->empty_domain)
> > +		iommu_domain_free(rkvdec->empty_domain);
> >   	return ret;
> >   }
> >