On Tue, Oct 19, 2021 at 07:52:35PM +0800, Xuan Zhuo wrote:
> When using indirect with packed, we don't check for allocation failures.
> This patch checks that and fall back on direct.
>
> Fixes: 1ce9e6055fa ("virtio_ring: introduce packed ring support")
> Signed-off-by: Xuan Zhuo <[email protected]>
Was a crash observed with this? It seems quite likely ...
> ---
> drivers/virtio/virtio_ring.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 91a46c4da87d..44a03b6e4dc4 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -1065,6 +1065,9 @@ 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)
> + /* fall back on direct */
> + return -EAGAIN;
>
> if (unlikely(vq->vq.num_free < 1)) {
> pr_debug("Can't add buf len 1 - avail = 0\n");
> @@ -1176,6 +1179,7 @@ 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 +1195,12 @@ 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 != -EAGAIN)
> + return err;
> + }
>
> head = vq->packed.next_avail_idx;
> avail_used_flags = vq->packed.avail_used_flags;
> --
> 2.31.0
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