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

[Manos Pitsidianakis <manos.pitsidianakis@linaro.org>]

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
>>
>>