Re: [PATCH v10 0/7] User readable error codes on atomic_ioctl failure

Jani Nikula
2026-02-24T12:07:46Z

On Tue, 24 Feb 2026, "Murthy, Arun R" <arun.r.murthy@intel.com> wrote:
> On 24-02-2026 14:58, Jani Nikula wrote:
>> On Tue, 24 Feb 2026, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
>>> Although I kinda doubt its actual usefulness to drive useful
>>> fallback logic because often the restrictions might be a combination
>>> of many things, and the kernel can only realistically report one of
>>> those things.
>> Yeah, this is my main concern as well. The drivers will have to bail out
>> on the first issue they hit, whatever it is. The drivers may choose to
>> do the checks in different orders, resulting in different failure modes
>> for different drivers. And finally, accidentally making the order of the
>> checks part of the ABI contract is a scary prospect. Imagine user space
>> depending on certain checks happening first in order for the fallback
>> logic to work properly. Is it a kernel regression to change the order of
>> the checks then?
> We are just reporting the 1st error that we see in the KMD and return
> from there.

Yes. But we can't guarantee all drivers will report the *same* first
error in the same circumstances. We can't guarantee we will maintain the
*same* first error over time, we can't make that promise without
painting ourselves in the corner wrt driver maintenance.

BR,
Jani.

--
Jani Nikula, Intel