Re: [PATCH RFC] drm/msm: move VM_BIND op validation to Rust

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 10/26/26 3:39 PM, Rob Clark wrote:
> On Mon, Oct 26, 2026 at 4:40 AM Konrad Dybcio <konradybcio@kernel.org> wrote:
>>
>> From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
>>
>> Much of the VM handling code is a headache to read and maintain.
>> There's a soup of mixed-signedness/size types which need to be compared
>> and added and getting that wrong in C is very easy.

[...]

>> @@ -1118,11 +1071,10 @@ vm_bind_job_lookup_ops(struct msm_vm_bind_job *job, struct drm_msm_vm_bind *args
>>                 op->obj = obj;
>>                 cnt++;
>>
>> -               if ((op->range + op->obj_offset) > obj->size) {
>> -                       ret = UERR(EINVAL, dev, "invalid range: %016llx + %016llx > %016zx\n",
>> -                                  op->range, op->obj_offset, obj->size);
>> +               ret = msm_vm_bind_check_bo_range(dev->dev, op->obj_offset, op->range,
>> +                                                obj->size);
>> +               if (ret)
> 
> I think the ioctl surface area is a sensible place to start using
> rust.. but seems like this patch could instead be a 1-ish line patch
> to use check_add_overflow() here?

Yeah I said that under the --- line, my main objective here is to
encourage rs

> Big picture, I'm a bit more interested in the
> goto-error-unwind-spagatti-monstors.  Even there, just using more
> cleanup.h would be an improvement.

Same. I'm done reviewing gotos. LLMs help a lot, but LLMs probably
prefer Rust too.

Konrad