Re: [PATCH v4 2/3] iommu/tegra-smmu: Rework tegra_smmu_probe_device()

Thierry Reding
2020-10-05T09:53:57Z

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On Fri, Oct 02, 2020 at 05:50:08PM +0300, Dmitry Osipenko wrote:
> 02.10.2020 17:22, Dmitry Osipenko пишет:
> >> static int tegra_smmu_of_xlate(struct device *dev,
> >> struct of_phandle_args *args)
> >> {
> >> + struct platform_device *iommu_pdev = of_find_device_by_node(args->np);
> >> + struct tegra_mc *mc = platform_get_drvdata(iommu_pdev);
> >> u32 id = args->args[0];
> >>
> >> + of_node_put(args->np);
> >> +
> >> + if (!mc || !mc->smmu)
> >> + return -EPROBE_DEFER;
> > platform_get_drvdata(NULL) will crash.
> >
>
> Actually, platform_get_drvdata(NULL) can't happen. I overlooked this.

How so? It's technically possible for the iommus property to reference a
device tree node for which no platform device will ever be created, in
which case of_find_device_by_node() will return NULL. That's very
unlikely and perhaps worth just crashing on to make sure it gets fixed
immediately.

Thierry

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