Messages in this thread | | | Subject | Re: [PATCH] iommu/rockchip: check return value of of_find_device_by_node() in rk_iommu_of_xlate() | From | "yukuai (C)" <> | Date | Fri, 30 Oct 2020 09:27:23 +0800 |
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On 2020/10/29 21:51, Robin Murphy wrote: > On 2020-10-29 13:19, yukuai (C) wrote: >> >> On 2020/10/29 18:08, Robin Murphy wrote: >>> On 2020-10-29 09:22, Yu Kuai wrote: >>>> If of_find_device_by_node() failed in rk_iommu_of_xlate(), null pointer >>>> dereference will be triggered. Thus return error code if >>>> of_find_device_by_node() failed. >>> >>> How can that happen? (Given that ".suppress_bind_attrs = true") >>> >>> Robin. >> >> I'm not sure if that could happen... >> >> My thought is that it's better to do such checking to aviod any possible >> problem. > > ->of_xlate() is only invoked on the specific set of ops returned by > iommu_ops_from_fwnode(). In turn, iommu_ops_from_fwnode() will only > return those ops if the driver has successfully probed and called > iommu_register_device() with the relevant DT node. For the driver to > have been able to probe at all, a platform device associated with that > DT node must have been created, and therefore of_find_device_by_node() > cannot fail. > > If there ever were some problem serious enough to break that fundamental > assumption, then I *want* these drivers to crash right here, with a nice > clear stack trace to start debugging from. So no, I firmly disagree that > adding redundant code, which will never do anything except attempt to > paper over catastrophic memory corruption, is "better". Sorry :) >
Sounds reasonable, thanks for your explanation
Yu Kuai
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