Re: [PATCH v3 2/2] virtio: decrement avail idx with buffer detach for packed ring

[Pankaj Gupta]

> 
> On 2019/8/9 下午2:48, Pankaj Gupta wrote:
> > This patch decrements 'next_avail_idx' count when detaching a buffer
> > from vq for packed ring code. Split ring code already does this in
> > virtqueue_detach_unused_buf_split function. This updates the
> > 'next_avail_idx' to the previous correct index after an unused buffer
> > is detatched from the vq.
> >
> > Signed-off-by: Pankaj Gupta 
> > ---
> >   drivers/virtio/virtio_ring.c | 6 ++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index c8be1c4f5b55..7c69181113e2 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -1537,6 +1537,12 @@ static void
> > *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq)
> > /* detach_buf clears data, so grab it now. */
> > buf = vq->packed.desc_state[i].data;
> > detach_buf_packed(vq, i, NULL);
> > +   vq->packed.next_avail_idx--;
> > +   if (vq->packed.next_avail_idx < 0) {
> > +   vq->packed.next_avail_idx = vq->packed.vring.num - 1;
> > +   vq->packed.avail_wrap_counter ^= 1;
> > +   }
> > +
> > END_USE(vq);
> > return buf;
> > }
> 
> 
> Acked-by: Jason Wang 

Thank you, Jason.

Best regards,
Pankaj

> 
> 
> 
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Re: [PATCH v3 2/2] virtio: decrement avail idx with buffer detach for packed ring

[Pankaj Gupta]

> On Fri, Aug 09, 2019 at 12:18:47PM +0530, Pankaj Gupta wrote:
> > This patch decrements 'next_avail_idx' count when detaching a buffer
> > from vq for packed ring code. Split ring code already does this in
> > virtqueue_detach_unused_buf_split function. This updates the
> > 'next_avail_idx' to the previous correct index after an unused buffer
> > is detatched from the vq.
> > 
> > Signed-off-by: Pankaj Gupta 
> 
> I would make this patch 1, not patch 2, otherwise
> patch 1 corrupts the ring.

Sure. Will post this patch as patch 1 in next version.

Thanks,
Pankaj 

> 
> 
> > ---
> >  drivers/virtio/virtio_ring.c | 6 ++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index c8be1c4f5b55..7c69181113e2 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -1537,6 +1537,12 @@ static void
> > *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq)
> > /* detach_buf clears data, so grab it now. */
> > buf = vq->packed.desc_state[i].data;
> > detach_buf_packed(vq, i, NULL);
> > +   vq->packed.next_avail_idx--;
> > +   if (vq->packed.next_avail_idx < 0) {
> > +   vq->packed.next_avail_idx = vq->packed.vring.num - 1;
> > +   vq->packed.avail_wrap_counter ^= 1;
> > +   }
> > +
> > END_USE(vq);
> > return buf;
> > }
> > --
> > 2.20.1
> 
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Re: [PATCH v3 2/2] virtio: decrement avail idx with buffer detach for packed ring

[Jason Wang]

On 2019/8/9 下午2:48, Pankaj Gupta wrote:

This patch decrements 'next_avail_idx' count when detaching a buffer
from vq for packed ring code. Split ring code already does this in
virtqueue_detach_unused_buf_split function. This updates the
'next_avail_idx' to the previous correct index after an unused buffer
is detatched from the vq.

Signed-off-by: Pankaj Gupta 
---
  drivers/virtio/virtio_ring.c | 6 ++
  1 file changed, 6 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index c8be1c4f5b55..7c69181113e2 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1537,6 +1537,12 @@ static void *virtqueue_detach_unused_buf_packed(struct 
virtqueue *_vq)
/* detach_buf clears data, so grab it now. */
buf = vq->packed.desc_state[i].data;
detach_buf_packed(vq, i, NULL);
+   vq->packed.next_avail_idx--;
+   if (vq->packed.next_avail_idx < 0) {
+   vq->packed.next_avail_idx = vq->packed.vring.num - 1;
+   vq->packed.avail_wrap_counter ^= 1;
+   }
+
END_USE(vq);
return buf;
}



Acked-by: Jason Wang 


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Re: [PATCH v3 2/2] virtio: decrement avail idx with buffer detach for packed ring

[Michael S. Tsirkin]

On Fri, Aug 09, 2019 at 12:18:47PM +0530, Pankaj Gupta wrote:
> This patch decrements 'next_avail_idx' count when detaching a buffer
> from vq for packed ring code. Split ring code already does this in
> virtqueue_detach_unused_buf_split function. This updates the
> 'next_avail_idx' to the previous correct index after an unused buffer
> is detatched from the vq.
> 
> Signed-off-by: Pankaj Gupta 

I would make this patch 1, not patch 2, otherwise
patch 1 corrupts the ring.


> ---
>  drivers/virtio/virtio_ring.c | 6 ++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index c8be1c4f5b55..7c69181113e2 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -1537,6 +1537,12 @@ static void *virtqueue_detach_unused_buf_packed(struct 
> virtqueue *_vq)
>   /* detach_buf clears data, so grab it now. */
>   buf = vq->packed.desc_state[i].data;
>   detach_buf_packed(vq, i, NULL);
> + vq->packed.next_avail_idx--;
> + if (vq->packed.next_avail_idx < 0) {
> + vq->packed.next_avail_idx = vq->packed.vring.num - 1;
> + vq->packed.avail_wrap_counter ^= 1;
> + }
> +
>   END_USE(vq);
>   return buf;
>   }
> -- 
> 2.20.1
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[PATCH v3 2/2] virtio: decrement avail idx with buffer detach for packed ring

[Pankaj Gupta]

This patch decrements 'next_avail_idx' count when detaching a buffer
from vq for packed ring code. Split ring code already does this in
virtqueue_detach_unused_buf_split function. This updates the
'next_avail_idx' to the previous correct index after an unused buffer
is detatched from the vq.

Signed-off-by: Pankaj Gupta 
---
 drivers/virtio/virtio_ring.c | 6 ++
 1 file changed, 6 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index c8be1c4f5b55..7c69181113e2 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1537,6 +1537,12 @@ static void *virtqueue_detach_unused_buf_packed(struct 
virtqueue *_vq)
/* detach_buf clears data, so grab it now. */
buf = vq->packed.desc_state[i].data;
detach_buf_packed(vq, i, NULL);
+   vq->packed.next_avail_idx--;
+   if (vq->packed.next_avail_idx < 0) {
+   vq->packed.next_avail_idx = vq->packed.vring.num - 1;
+   vq->packed.avail_wrap_counter ^= 1;
+   }
+
END_USE(vq);
return buf;
}
-- 
2.20.1

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