Re: [PATCH v6 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group
From: Joerg Roedel <joro@8bytes.org>
Date: 2022-09-08 13:29:02
Also in:
asahi, kvm, linux-arm-msm, linux-iommu, linux-s390, linux-tegra, lkml, virtualization
On Wed, Sep 07, 2022 at 02:10:33PM -0300, Jason Gunthorpe wrote:
Sure, rust has all sorts of nice things. But the kernel doesn't follow rust idioms, and I don't think this is a great place to start experimenting with them.
It is actually a great place to start experimenting. The IOMMU interfaces are rather domain specific and if we get something wrong the damage is limited to a few callers. There are APIs much more exposed in the kernel which would be worse for that. But anyway, I am not insisting on it.
It has been 3 months since EMEDIUMTYPE was first proposed and 6 iterations of the series, don't you think it is a bit late in the game to try to experiment with rust error handling idioms?
If I am not mistaken, I am the person who gets blamed when crappy IOMMU code is sent upstream. So it is also up to me to decide in which state and how close to merging a given patch series is an whether it is already 'late in the game'.
So, again, would you be happy with a simple #define IOMMU_EINCOMPATIBLE_DEVICE xx to make it less "re-using random error codes"?
I am wondering if this can be solved by better defining what the return codes mean and adjust the call-back functions to match the definition. Something like: -ENODEV : Device not mapped my an IOMMU -EBUSY : Device attached and domain can not be changed -EINVAL : Device and domain are incompatible ... That would be much more intuitive than using something obscure like EMEDIUMTYPE. Regards, Joerg _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel