Re: [Qemu-devel] [PATCH v12 2/7] virtio-pmem: Add virtio pmem driver

Pankaj Gupta
2019-06-12T10:50:45Z

>
> Hi Pankaj,
>
> On Tue, 11 Jun 2019 23:34:50 -0400 (EDT)
> Pankaj Gupta <pagupta@redhat.com> wrote:
>
> > Hi Cornelia,
> >
> > > On Tue, 11 Jun 2019 22:07:57 +0530
> > > Pankaj Gupta <pagupta@redhat.com> wrote:
>
>
> > > > + err1 = virtqueue_kick(vpmem->req_vq);
> > > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
> > > > + /*
> > > > + * virtqueue_add_sgs failed with error different than -ENOSPC, we
> > > > can't
> > > > + * do anything about that.
> > > > + */
> > >
> > > Does it make sense to kick if you couldn't add at all?
> >
> > When we could not add because of -ENOSPC we are waiting and when buffer is
> > added
> > then only we do a kick. For any other error which might be a rare
> > occurrence, I think
> > kick is harmless here and keeps the code clean?
>
> Yes, I agree it does not hurt. Let's keep it as-is.

Sure.

>
>
> > Sure, Thank you. Attaching below on top changes on current patch2 based on
> > your suggestions. Let me know if these are okay and then will send official
> > v13 to for upstream merging.
>
> Looks good to me, except for one change.

Sure. Will send v13 shortly.

>
> [Again sorry for the late review, did not want to get the version
> numbers up :)]

Thank you :)

>
> >
> > Thanks,
> > Pankaj
> >
> > ===============
> >
> > diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c
> > index efc535723517..5b8d2367da0b 100644
> > --- a/drivers/nvdimm/nd_virtio.c
> > +++ b/drivers/nvdimm/nd_virtio.c
> > @@ -10,7 +10,7 @@
> > #include "nd.h"
> >
> > /* The interrupt handler */
> > -void host_ack(struct virtqueue *vq)
> > +void virtio_pmem_host_ack(struct virtqueue *vq)
> > {
> > struct virtio_pmem *vpmem = vq->vdev->priv;
> > struct virtio_pmem_request *req_data, *req_buf;
> > @@ -32,10 +32,10 @@ void host_ack(struct virtqueue *vq)
> > }
> > spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
> > }
> > -EXPORT_SYMBOL_GPL(host_ack);
> > +EXPORT_SYMBOL_GPL(virtio_pmem_host_ack);
> >
> > /* The request submission function */
> > -int virtio_pmem_flush(struct nd_region *nd_region)
> > +static int virtio_pmem_flush(struct nd_region *nd_region)
> > {
> > struct virtio_device *vdev = nd_region->provider_data;
> > struct virtio_pmem *vpmem = vdev->priv;
> > @@ -69,7 +69,7 @@ int virtio_pmem_flush(struct nd_region *nd_region)
> > while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req_data,
> > GFP_ATOMIC)) == -ENOSPC) {
> >
> > - dev_err(&vdev->dev, "failed to send command to virtio pmem
> > device, no free slots in the virtqueue\n");
> > + dev_info(&vdev->dev, "failed to send command to virtio pmem
> > device, no free slots in the virtqueue\n");
> > req_data->wq_buf_avail = false;
> > list_add_tail(&req_data->list, &vpmem->req_list);
> > spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
> > @@ -90,7 +90,8 @@ int virtio_pmem_flush(struct nd_region *nd_region)
> > } else {
> > /* A host repsonse results in "host_ack" getting called */
> > wait_event(req_data->host_acked, req_data->done);
> > - err = virtio32_to_cpu(vdev, req_data->resp.ret);
> > + if ((err = virtio32_to_cpu(vdev, req_data->resp.ret)))
> > + err = -EIO;
>
> Hm, why are you making this change? I think the previous code was fine.

Yes, Something came to my mind while making the change but I agree will keep
this as it was before.

>
> > }
> >
> > kfree(req_data);
> > @@ -100,7 +101,8 @@ int virtio_pmem_flush(struct nd_region *nd_region)
> > /* The asynchronous flush callback function */
> > int async_pmem_flush(struct nd_region *nd_region, struct bio *bio)
> > {
> > - /* Create child bio for asynchronous flush and chain with
> > + /*
> > + * Create child bio for asynchronous flush and chain with
> > * parent bio. Otherwise directly call nd_region flush.
> > */
> > if (bio && bio->bi_iter.bi_sector != -1) {
> > diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c
> > index b60ebd8cd2fd..5e3d07b47e0c 100644
> > --- a/drivers/nvdimm/virtio_pmem.c
> > +++ b/drivers/nvdimm/virtio_pmem.c
> > @@ -19,7 +19,7 @@ static int init_vq(struct virtio_pmem *vpmem)
> > {
> > /* single vq */
> > vpmem->req_vq = virtio_find_single_vq(vpmem->vdev,
> > - host_ack, "flush_queue");
> > + virtio_pmem_host_ack,
> > "flush_queue");
> > if (IS_ERR(vpmem->req_vq))
> > return PTR_ERR(vpmem->req_vq);
> >
> > diff --git a/drivers/nvdimm/virtio_pmem.h b/drivers/nvdimm/virtio_pmem.h
> > index 6e47521be158..998efbc7660c 100644
> > --- a/drivers/nvdimm/virtio_pmem.h
> > +++ b/drivers/nvdimm/virtio_pmem.h
> > @@ -50,6 +50,6 @@ struct virtio_pmem {
> > uint64_t size;
> > };
> >
> > -void host_ack(struct virtqueue *vq);
> > +void virtio_pmem_host_ack(struct virtqueue *vq);
> > int async_pmem_flush(struct nd_region *nd_region, struct bio *bio);
> > #endif
>
>
>