Messages in this thread | | | Date | Thu, 7 Jul 2022 10:58:56 +0100 | Subject | Re: [PATCH v3 03/15] iommu: Always register bus notifiers | From | Robin Murphy <> |
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On 2022-07-07 07:31, Tian, Kevin wrote: >> From: Robin Murphy <robin.murphy@arm.com> >> Sent: Wednesday, July 6, 2022 1:08 AM >> >> The number of bus types that the IOMMU subsystem deals with is small and >> manageable, so pull that list into core code as a first step towards >> cleaning up all the boilerplate bus-awareness from drivers. Calling >> iommu_probe_device() before bus->iommu_ops is set will simply return >> -ENODEV and not break the notifier call chain, so there should be no >> harm in proactively registering all our bus notifiers at init time. >> > > Suppose we miss a check on iommu ops in iommu_release_device(): > > if (!dev->iommu) <<<<<<< > return; > > iommu_device_unlink(dev->iommu->iommu_dev, dev); > > ops = dev_iommu_ops(dev); > ops->release_device(dev); > > following the rationale in patch01 a device could be removed when > it's associated with a known but not registered instance.
No, because at that point the instance is only known internally to the driver. As long as it isn't erroneously returned from ->probe_device(dev), dev->iommu will remain NULL and the rest of the core code works as expected.
Thanks, Robin.
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