On Mon, 27 Sep 2021 11:20:16 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote:
> On Mon, Sep 27, 2021 at 11:06 AM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
> >
> > In the case of packed, use indirect desc, since desc is allocated by
> > kmalloc_array(), we should check whether its return value is NULL.
> >
> > Fixes: 1ce9e6055fa ("virtio_ring: introduce packed ring support")
> > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > ---
> > drivers/virtio/virtio_ring.c | 27 ++++++++++++++++-----------
> > 1 file changed, 16 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index dd95dfd85e98..7dd381eae725 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -1050,21 +1050,20 @@ static struct vring_packed_desc *alloc_indirect_packed(unsigned int total_sg,
> > }
> >
> > static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
> > - struct scatterlist *sgs[],
> > - unsigned int total_sg,
> > - unsigned int out_sgs,
> > - unsigned int in_sgs,
> > - void *data,
> > - gfp_t gfp)
> > + struct scatterlist *sgs[],
> > + struct vring_packed_desc *desc,
> > + unsigned int total_sg,
> > + unsigned int out_sgs,
> > + unsigned int in_sgs,
> > + void *data,
> > + gfp_t gfp)
>
> It looks to me the style changes are mixed with bug fix here.
I will make a separate patch for the next version.
>
> > {
> > - struct vring_packed_desc *desc;
> > struct scatterlist *sg;
> > unsigned int i, n, err_idx;
> > u16 head, id;
> > dma_addr_t addr;
> >
> > head = vq->packed.next_avail_idx;
> > - desc = alloc_indirect_packed(total_sg, gfp);
> >
> > if (unlikely(vq->vq.num_free < 1)) {
> > pr_debug("Can't add buf len 1 - avail = 0\n");
> > @@ -1191,9 +1190,15 @@ 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)) {
> > + desc = alloc_indirect_packed(total_sg, gfp);
> > + if (desc) {
> > + return virtqueue_add_indirect_packed(vq, sgs, desc,
> > + total_sg,
> > + out_sgs, in_sgs,
> > + data, gfp);
> > + }
> > + }
>
> Any reason that we can't fix virtqueue_add_indirect_packed()? It can
> help to reduce the changeset and ease the backport.
The purpose of this is to fall back to not using indirect when
alloc_indirect_packed returns NULL.
If we check the return value of alloc_indirect_packed() in
virtqueue_add_indirect_packed(), then MUST check the error returned by
virtqueue_add_indirect_packed() to determine whether to fall back to the mode
that does not use indirect.
Thanks.
>
> Thanks
>
> >
> > head = vq->packed.next_avail_idx;
> > avail_used_flags = vq->packed.avail_used_flags;
> > --
> > 2.31.0
> >
>
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