On Tue, 19 Oct 2021 09:21:51 -0400, Michael S. Tsirkin <[email protected]> wrote:
> 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]>
> > ---
> > 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 */
>
> this comment belongs in virtqueue_add_packed right after
> return.
>
> > + return -EAGAIN;
> >
>
> -ENOMEM surely?
virtqueue_add_indirect_packed() will return -ENOMEM when dma mmap fails, so we
have to choose a different error code.
Thanks.
>
> > 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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