linux-kernel - Re: [PATCH v6 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group

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Message-ID: <YxilZbRL0WBR97oi@8bytes.org>
Date:   Wed, 7 Sep 2022 16:06:29 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     Nicolin Chen <nicolinc@...dia.com>, will@...nel.org,
        robin.murphy@....com, alex.williamson@...hat.com,
        suravee.suthikulpanit@....com, marcan@...can.st,
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        thunder.leizhen@...wei.com, christophe.jaillet@...adoo.fr,
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Subject: Re: [PATCH v6 1/5] iommu: Return -EMEDIUMTYPE for incompatible
 domain and device/group

On Wed, Sep 07, 2022 at 10:47:39AM -0300, Jason Gunthorpe wrote:
> Would you be happier if we wrote it like
> 
>  #define IOMMU_EINCOMPATIBLE_DEVICE xx
> 
> Which tells "which of the function parameters is actually invalid" ?

Having done some Rust hacking in the last months, I have to say I like
to concept of error handling with Result<> there. Ideally we have a way
to emulate that in our C code without having to change all callers.

What I am proposing is a way this could be emulated here, but I am open
to other suggestions. Still better than re-using random error codes for
special purposes.

Regards,

	Joerg