Re: [PATCH v2 3/3] virtio-gpu-rutabaga.c: override resource_destroy method

[Manos Pitsidianakis]

On Tue, 30 Jan 2024 03:26, Gurchetan Singh <gurchetansingh@chromium.org> wrote:
> On Mon, Jan 29, 2024 at 7:46 AM Manos Pitsidianakis <
> manos.pitsidianakis@linaro.org> wrote:
>
> > When the Rutabaga GPU device frees resources, it calls
> > rutabaga_resource_unref for that resource_id. However, when the generic
> > VirtIOGPU functions destroys resources, it only removes the
> > virtio_gpu_simple_resource from the device's VirtIOGPU->reslist list.
> > The rutabaga resource associated with that resource_id is then leaked.
> >
> > This commit overrides the resource_destroy class method introduced in
> > the previous commit to fix this.
> >
> > Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
> > ---
> >  hw/display/virtio-gpu-rutabaga.c | 51 ++++++++++++++++++++++++--------
> >  1 file changed, 39 insertions(+), 12 deletions(-)
> >
> > diff --git a/hw/display/virtio-gpu-rutabaga.c
> > b/hw/display/virtio-gpu-rutabaga.c
> > index 9e67f9bd51..6ac0776005 100644
> > --- a/hw/display/virtio-gpu-rutabaga.c
> > +++ b/hw/display/virtio-gpu-rutabaga.c
> > @@ -148,14 +148,42 @@ rutabaga_cmd_create_resource_3d(VirtIOGPU *g,
> >  }
> >
> >  static void
> > +virtio_gpu_rutabaga_resource_unref(VirtIOGPU *g,
> > +                                   struct virtio_gpu_simple_resource *res,
> > +                                   Error **errp)
> > +{
> > +    int32_t result;
> > +    const char *strerror = NULL;
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    result = rutabaga_resource_unref(vr->rutabaga, res->resource_id);
> > +    if (result) {
> > +        error_setg(errp, "%s: rutabaga_resource_unref returned %"PRIi32
> > +                   " for resource_id = %"PRIu32, __func__, result,
> > +                   res->resource_id);
> > +        strerror = strerrorname_np((int)result);
> > +        if (strerror != NULL) {
> > +            error_append_hint(errp, "%s: %s\n",
> > +                              strerror, strerrordesc_np((int)result) ? :
> > "");
> > +        }
>
> Can't we rely on virtio_gpu_rutabaga_debug_cb(..) to report an error when
> the resource ID is not found?


IIUC that callback is called from the external library, and uses its own 
type (const struct rutabaga *debug) which is not how the interface works 
here. rutabaga_resource_unref() returns an int32_t. Besides this isn't a 
debug print but an error print.

> > +    }
> > +
> > +    if (res->image) {
> > +        pixman_image_unref(res->image);
> > +    }
> > +
> > +    QTAILQ_REMOVE(&g->reslist, res, next);
> > +    g_free(res);
> > +}
> > +
> > +static void
> >  rutabaga_cmd_resource_unref(VirtIOGPU *g,
> >                              struct virtio_gpu_ctrl_command *cmd)
> >  {
> > -    int32_t result;
> > +    int32_t result = 0;
> >      struct virtio_gpu_simple_resource *res;
> >      struct virtio_gpu_resource_unref unref;
> > -
> > -    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +    Error *local_err = NULL;
> >
> >      VIRTIO_GPU_FILL_CMD(unref);
> >
> > @@ -164,15 +192,14 @@ rutabaga_cmd_resource_unref(VirtIOGPU *g,
> >      res = virtio_gpu_find_resource(g, unref.resource_id);
> >      CHECK(res, cmd);
> >
> > -    result = rutabaga_resource_unref(vr->rutabaga, unref.resource_id);
> > -    CHECK(!result, cmd);
> > -
> > -    if (res->image) {
> > -        pixman_image_unref(res->image);
> > +    virtio_gpu_rutabaga_resource_unref(g, res, &local_err);
> > +    if (local_err) {
> > +        error_report_err(local_err);
> > +        /* local_err was freed, do not reuse it. */
> > +        local_err = NULL;
> > +        result = 1;
> >      }
> > -
> > -    QTAILQ_REMOVE(&g->reslist, res, next);
> > -    g_free(res);
> > +    CHECK(!result, cmd);
> >  }
> >
> >  static void
> > @@ -1099,7 +1126,7 @@ static void
> > virtio_gpu_rutabaga_class_init(ObjectClass *klass, void *data)
> >      vgc->handle_ctrl = virtio_gpu_rutabaga_handle_ctrl;
> >      vgc->process_cmd = virtio_gpu_rutabaga_process_cmd;
> >      vgc->update_cursor_data = virtio_gpu_rutabaga_update_cursor;
> > -
> > +    vgc->resource_destroy = virtio_gpu_rutabaga_resource_unref;
> >      vdc->realize = virtio_gpu_rutabaga_realize;
> >      device_class_set_props(dc, virtio_gpu_rutabaga_properties);
> >  }
> > --
> > γαῖα πυρί μιχθήτω