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

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Date:   Mon, 23 Oct 2023 17:52:02 +0800
From:   Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To:     Su Hui <suhui@...china.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 Mon, 23 Oct 2023 17:50:46 +0800, Su Hui <suhui@...china.com> wrote:
> 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).

OK.

Thanks.


>
> Thanks,
> Su Hui
>