linux-kernel - Re: [PATCH] virtio_ring: add an error code check in virtqueue

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Date:   Mon, 23 Oct 2023 17:50:46 +0800
From:   Su Hui <suhui@...china.com>
To:     Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        "Michael S. Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH] virtio_ring: add an error code check in virtqueue_resize

On 2023/10/23 13:46, Xuan Zhuo wrote:
>>>>>>>> Well, what are the cases where it can happen practically?
>>>>>>> Device error. Such as vp_active_vq()
>>>>>>>
>>>>>>> Thanks.
>>>>>> Hmm interesting. OK. But do callers know to recover?
>>>>> No.
>>>>>
>>>>> So I think WARN + broken is suitable.
>>>>>
>>>>> Thanks.
>>>> Sorry for the late, is the following code okay?
>>>>
>>>> @@ -2739,7 +2739,7 @@ int virtqueue_resize(struct virtqueue *_vq, u32 num,
>>>>                         void (*recycle)(struct virtqueue *vq, void *buf))
>>>>     {
>>>>            struct vring_virtqueue *vq = to_vvq(_vq);
>>>> -       int err;
>>>> +       int err, err_reset;
>>>>
>>>>            if (num > vq->vq.num_max)
>>>>                    return -E2BIG;
>>>> @@ -2759,7 +2759,15 @@ int virtqueue_resize(struct virtqueue *_vq, u32 num,
>>>>            else
>>>>                    err = virtqueue_resize_split(_vq, num);
>>>>
>>>> -       return virtqueue_enable_after_reset(_vq);
>>>> +       err_reset = virtqueue_enable_after_reset(_vq);
>>>> +
>>>> +       if (err) {
>>> No err.
>>>
>>> err is not important.
>>> You can remove that.
>> Emm, I'm a little confused that which code should I remove ?
>>
>>
>> like this:
>> 	if (vq->packed_ring)
>> 		virtqueue_resize_packed(_vq, num);
>> 	else
>> 		virtqueue_resize_split(_vq, num);
>>
>> And we should set broken and warn inside virtqueue_enable_after_reset()?

In my opinion, we should return the error code of virtqueue_resize_packed() / virtqueue_resize_split().
But if this err is not important, this patch makes no sense.
Maybe I misunderstand somewhere...
If you think it's worth sending a patch, you can send it :).(I'm not familiar with this code).

Thanks,
Su Hui