2019-09-04 07:49:39

by Gerd Hoffmann

Subject: [PATCH] drm/virtio: fix command submission with objects but without fence.

Only call virtio_gpu_array_add_fence if we actually have a fence.

Fixes: da758d51968a ("drm/virtio: rework virtio_gpu_execbuffer_ioctl fencing")
Signed-off-by: Gerd Hoffmann <[email protected]>
---
drivers/gpu/drm/virtio/virtgpu_vq.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 595fa6ec2d58..7fd2851f7b97 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -339,11 +339,12 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
goto again;
}

- if (fence)
+ if (fence) {
virtio_gpu_fence_emit(vgdev, hdr, fence);
- if (vbuf->objs) {
- virtio_gpu_array_add_fence(vbuf->objs, &fence->f);
- virtio_gpu_array_unlock_resv(vbuf->objs);
+ if (vbuf->objs) {
+ virtio_gpu_array_add_fence(vbuf->objs, &fence->f);
+ virtio_gpu_array_unlock_resv(vbuf->objs);
+ }
}
notify = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf);
spin_unlock(&vgdev->ctrlq.qlock);
--
2.18.1

2019-09-04 23:11:48

by Chia-I Wu

Subject: Re: [PATCH] drm/virtio: fix command submission with objects but without fence.

On Wed, Sep 4, 2019 at 12:48 AM Gerd Hoffmann <[email protected]> wrote:
>
> Only call virtio_gpu_array_add_fence if we actually have a fence.
>
> Fixes: da758d51968a ("drm/virtio: rework virtio_gpu_execbuffer_ioctl fencing")
> Signed-off-by: Gerd Hoffmann <[email protected]>
> ---
> drivers/gpu/drm/virtio/virtgpu_vq.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
> index 595fa6ec2d58..7fd2851f7b97 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_vq.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
> @@ -339,11 +339,12 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
> goto again;
> }
>
> - if (fence)
> + if (fence) {
> virtio_gpu_fence_emit(vgdev, hdr, fence);
> - if (vbuf->objs) {
> - virtio_gpu_array_add_fence(vbuf->objs, &fence->f);
> - virtio_gpu_array_unlock_resv(vbuf->objs);
> + if (vbuf->objs) {
> + virtio_gpu_array_add_fence(vbuf->objs, &fence->f);
> + virtio_gpu_array_unlock_resv(vbuf->objs);
> + }
This leaks when fence == NULL and vbuf->objs != NULL (which can really
happen IIRC... not at my desk to check).


> }
> notify = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf);
> spin_unlock(&vgdev->ctrlq.qlock);
> --
> 2.18.1
>

2019-09-05 06:11:21

by Gerd Hoffmann

Subject: Re: [PATCH] drm/virtio: fix command submission with objects but without fence.

On Wed, Sep 04, 2019 at 04:10:30PM -0700, Chia-I Wu wrote:
> On Wed, Sep 4, 2019 at 12:48 AM Gerd Hoffmann <[email protected]> wrote:
> >
> > Only call virtio_gpu_array_add_fence if we actually have a fence.
> >
> > Fixes: da758d51968a ("drm/virtio: rework virtio_gpu_execbuffer_ioctl fencing")
> > Signed-off-by: Gerd Hoffmann <[email protected]>
> > ---
> > drivers/gpu/drm/virtio/virtgpu_vq.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
> > index 595fa6ec2d58..7fd2851f7b97 100644
> > --- a/drivers/gpu/drm/virtio/virtgpu_vq.c
> > +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
> > @@ -339,11 +339,12 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
> > goto again;
> > }
> >
> > - if (fence)
> > + if (fence) {
> > virtio_gpu_fence_emit(vgdev, hdr, fence);
> > - if (vbuf->objs) {
> > - virtio_gpu_array_add_fence(vbuf->objs, &fence->f);
> > - virtio_gpu_array_unlock_resv(vbuf->objs);
> > + if (vbuf->objs) {
> > + virtio_gpu_array_add_fence(vbuf->objs, &fence->f);
> > + virtio_gpu_array_unlock_resv(vbuf->objs);
> > + }
> This leaks when fence == NULL and vbuf->objs != NULL (which can really
> happen IIRC... not at my desk to check).

Yes, it can happen, for example when flushing dumb buffers.

But I don't think we leak in this case. The code paths which don't need
a fence also do not call virtio_gpu_array_lock_resv(), so things are
balanced. The actual release of the objs happens in
virtio_gpu_dequeue_ctrl_func() via virtio_gpu_array_put_free_delayed().

cheers,
Gerd

2019-09-06 01:17:14

by Chia-I Wu

Subject: Re: [PATCH] drm/virtio: fix command submission with objects but without fence.

On Wed, Sep 4, 2019 at 10:23 PM Gerd Hoffmann <[email protected]> wrote:
>
> On Wed, Sep 04, 2019 at 04:10:30PM -0700, Chia-I Wu wrote:
> > On Wed, Sep 4, 2019 at 12:48 AM Gerd Hoffmann <[email protected]> wrote:
> > >
> > > Only call virtio_gpu_array_add_fence if we actually have a fence.
> > >
> > > Fixes: da758d51968a ("drm/virtio: rework virtio_gpu_execbuffer_ioctl fencing")
> > > Signed-off-by: Gerd Hoffmann <[email protected]>
> > > ---
> > > drivers/gpu/drm/virtio/virtgpu_vq.c | 9 +++++----
> > > 1 file changed, 5 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
> > > index 595fa6ec2d58..7fd2851f7b97 100644
> > > --- a/drivers/gpu/drm/virtio/virtgpu_vq.c
> > > +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
> > > @@ -339,11 +339,12 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
> > > goto again;
> > > }
> > >
> > > - if (fence)
> > > + if (fence) {
> > > virtio_gpu_fence_emit(vgdev, hdr, fence);
> > > - if (vbuf->objs) {
> > > - virtio_gpu_array_add_fence(vbuf->objs, &fence->f);
> > > - virtio_gpu_array_unlock_resv(vbuf->objs);
> > > + if (vbuf->objs) {
> > > + virtio_gpu_array_add_fence(vbuf->objs, &fence->f);
> > > + virtio_gpu_array_unlock_resv(vbuf->objs);
> > > + }
> > This leaks when fence == NULL and vbuf->objs != NULL (which can really
> > happen IIRC... not at my desk to check).
>
> Yes, it can happen, for example when flushing dumb buffers.
>
> But I don't think we leak in this case. The code paths which don't need
> a fence also do not call virtio_gpu_array_lock_resv(), so things are
> balanced. The actual release of the objs happens in
> virtio_gpu_dequeue_ctrl_func() via virtio_gpu_array_put_free_delayed().
I misread and thought this was in virtio_gpu_dequeue_ctrl_func. Sorry :(

Reviewed-by: Chia-I Wu <[email protected]>



>
> cheers,
> Gerd
>