Re: [PATCH v1 0/4] iommu: Fix device lookup lifetime and probe cleanup

[Pranjal Shrivastava]

On Tue, Jul 14, 2026 at 02:09:26PM +0800, weimin xiong wrote:
> Fix a few IOMMU driver lifetime and error-path issues found while
> auditing fwnode-based device lookup and probe cleanup paths.
> 
> The first three patches avoid deriving driver private data after
> dropping the device reference returned by bus_find_device_by_fwnode().
> They also make the ARM SMMU v2 and VSI probe paths fail cleanly when the
> IOMMU lookup fails.

I'm not sure if that's really needed? All these drivers are doing is
dropping the "extra" refcount (incremented by calling find_device)  back
to the state *before* the fwnode function call. If you find that this
put_device caused the count to drop to 0, I believe that's the real
problem/bug. These fwnode functions are usually called in probe and the
refcount shouldn't be 0 inside probe.

Could you share your observation / failing logs where this fails? Maybe
something else is wrong with the system?

Thanks,
Praan