On Mon, Sep 27, 2021 at 11:29 AM Xuan Zhuo <[email protected]> wrote:
>
> On Mon, 27 Sep 2021 11:20:16 +0800, Jason Wang <[email protected]> wrote:
> > On Mon, Sep 27, 2021 at 11:06 AM Xuan Zhuo <[email protected]>
> > 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 <[email protected]>
> > > ---
> > > 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.
Please make it a patch on top of the fix to ease the backport.
>
> >
> > > {
> > > - 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.
Right, this aligns the behaviour of the split path. But please
describe this in the commit log.
Thanks
>
> Thanks.
>
> >
> > Thanks
> >
> > >
> > > head = vq->packed.next_avail_idx;
> > > avail_used_flags = vq->packed.avail_used_flags;
> > > --
> > > 2.31.0
> > >
> >
>
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