On Tue, 19 Oct 2021 07:07:58 -0400, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
> On Tue, Oct 19, 2021 at 06:56:57PM +0800, Xuan Zhuo 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.
> >
> > This patch alloc desc inside virtqueue_add_packe(), if desc == NULL,
>
> Can we manage without typos in commit log please?
I'm sorry. virtqueue_add_packe => virtqueue_add_packed
>
> > fall back to not using indirect.
>
>
> It should say why is the patch created, and how it's fixed,
> as opposed to repating what patch does.
>
> E.g.
>
> when using indirect with packed, we don't check for
> allocation failures. Check and fall back on direct.
It's better. I know how to do it.
>
>
>
> > Fixes: 1ce9e6055fa ("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, 9 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index 91a46c4da87d..62323c27bfe4 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -1051,20 +1051,19 @@ 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[],
> > + struct vring_packed_desc *desc,
> > unsigned int total_sg,
> > unsigned int out_sgs,
> > unsigned int in_sgs,
> > void *data,
> > gfp_t gfp)
>
> So this gets desc and will free it. I don't much like this.
Under normal circumstances, this function will not release desc. It will
actually release "desc" in detach_buf_packed(). Of course, if you encounter
an error in this function, it will also release desc in this function.
If we call alloc_indirect_packed() in virtqueue_add_indirect_packed() it is also
possible, we need to make virtqueue_add_indirect_packed() return a special
return value.
Thanks.
>
>
> > {
> > - 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 +1190,14 @@ 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)) {
> > + 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);
> > + }
> >
> > head = vq->packed.next_avail_idx;
> > avail_used_flags = vq->packed.avail_used_flags;
> > --
> > 2.31.0
>
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