Re: [PATCH v7 2/2] virtio_ring: check desc == NULL when using indirect with packed

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On Mon, Oct 25, 2021 at 9:56 AM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> When using indirect with packed, we don't check for allocation failures.
> This patch checks that and fall back on direct.
>
> Fixes: 1ce9e6055fa0 ("virtio_ring: introduce packed ring support")
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---

Acked-by: Jason Wang <jasowang@xxxxxxxxxx>

>  drivers/virtio/virtio_ring.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 91a46c4da87d..bc92a2faa28f 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -1065,6 +1065,8 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
>
>         head = vq->packed.next_avail_idx;
>         desc = alloc_indirect_packed(total_sg, gfp);
> +       if (!desc)
> +               return -ENOMEM;
>
>         if (unlikely(vq->vq.num_free < 1)) {
>                 pr_debug("Can't add buf len 1 - avail = 0\n");
> @@ -1176,6 +1178,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
>         unsigned int i, n, c, descs_used, err_idx;
>         __le16 head_flags, flags;
>         u16 head, id, prev, curr, avail_used_flags;
> +       int err;
>
>         START_USE(vq);
>
> @@ -1191,9 +1194,14 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
>
>         BUG_ON(total_sg == 0);
>
> -       if (virtqueue_use_indirect(_vq, total_sg))
> -               return virtqueue_add_indirect_packed(vq, sgs, total_sg,
> -                               out_sgs, in_sgs, data, gfp);
> +       if (virtqueue_use_indirect(_vq, total_sg)) {
> +               err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
> +                                                   in_sgs, data, gfp);
> +               if (err != -ENOMEM)
> +                       return err;
> +
> +               /* fall back on direct */
> +       }
>
>         head = vq->packed.next_avail_idx;
>         avail_used_flags = vq->packed.avail_used_flags;
> --
> 2.31.0
>

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