Re: [v4] virtio-gpu: use consistent error checking style for virtio_gpu_create_mapping_iov

[Honglei Huang <honghuan@amd.com>]

On 2025/11/18 09:48, Dmitry Osipenko wrote:
> On 11/17/25 16:22, Markus Armbruster wrote:
>> Dmitry Osipenko <dmitry.osipenko@collabora.com> writes:
>>
>>> On 11/17/25 13:51, Honglei Huang wrote:
>>>> diff --git a/hw/display/virtio-gpu-rutabaga.c b/hw/display/virtio-gpu-rutabaga.c
>>>> index ed5ae52acb..ea2928b706 100644
>>>> --- a/hw/display/virtio-gpu-rutabaga.c
>>>> +++ b/hw/display/virtio-gpu-rutabaga.c
>>>> @@ -466,7 +466,7 @@ rutabaga_cmd_attach_backing(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
>>>>   
>>>>       ret = virtio_gpu_create_mapping_iov(g, att_rb.nr_entries, sizeof(att_rb),
>>>>                                           cmd, NULL, &res->iov, &res->iov_cnt);
>>>> -    CHECK(!ret, cmd);
>>>> +    CHECK(ret >= 0, cmd);
>>>
>>> virtio_gpu_create_mapping_iov() doesn't return positive values, don't
>>> see how this change improves anything. You now saying that ret > 0 is
>>> okay, while it shall never happen.
>>
>> Please see
>>
>>      Subject: Re: [PATCH] virtio-gpu-virgl: fix error handling in virgl_cmd_resource_create_blob
>>      Date: Mon, 17 Nov 2025 08:49:42 +0100
>>      Message-ID: <87ms4lrtd5.fsf@pond.sub.org>
>>      https://lore.kernel.org/qemu-devel/87ms4lrtd5.fsf@pond.sub.org/
> 
> It's a rather common bug when errno isn't negated by mistake and a
> positive error code is returned. Ignoring positive values when they
> aren't expected opens door to unnecessary problems, IMO.
> 

How about apply the v2 or v3 firstly to fix the 
virtio_gpu_create_mapping_iov() block issue in virtio-gpu?

I will create another thread for the `CHECK(!ret, cmd);` thing in rutabaga.

Regards,
Honglei