On 10/08/2017 18:40, Richard W.M. Jones wrote: > If using indirect descriptors, you can make the total_sg as large as > you want. If not, BUG is too serious because the function later > returns -ENOSPC. > > Thanks Paolo Bonzini, Christoph Hellwig. > > Signed-off-by: Richard W.M. Jones <rjones@xxxxxxxxxx> > --- > drivers/virtio/virtio_ring.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 5e1b548828e6..27cbc1eab868 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -296,7 +296,6 @@ static inline int virtqueue_add(struct virtqueue *_vq, > } > #endif > > - BUG_ON(total_sg > vq->vring.num); > BUG_ON(total_sg == 0); > > head = vq->free_head; > @@ -305,8 +304,10 @@ static inline int virtqueue_add(struct virtqueue *_vq, > * buffers, then go indirect. FIXME: tune this threshold */ > if (vq->indirect && total_sg > 1 && vq->vq.num_free) > desc = alloc_indirect(_vq, total_sg, gfp); > - else > + else { > desc = NULL; > + WARN_ON_ONCE(total_sg > vq->vring.num && !vq->indirect); So we get here only if vq->vq.num_free is zero. In that case, vq->indirect makes no difference for the appropriateness of the warning (that is, it should never be issued for indirect descriptors). > + } > > if (desc) { > /* Use a single buffer which doesn't continue */ > Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Paolo _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization