Re: [PATCH RESEND] drm/msm: Add missing check and destroy for alloc_ordered_workqueue

[Dmitry Baryshkov]

On 06/01/2023 10:47, Jiasheng Jiang wrote:
> Add check for the return value of alloc_ordered_workqueue as it may return
> NULL pointer.
> Moreover, use the destroy_workqueue in the later fails in order to avoid
> memory leak.
>
> Fixes: c8afe684c95c ("drm/msm: basic KMS driver for snapdragon")
> Signed-off-by: Jiasheng Jiang <jiasheng@xxxxxxxxxxx>
> ---
>   drivers/gpu/drm/msm/msm_drv.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 8b0b0ac74a6f..b82d938226ad 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -418,6 +418,8 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   	priv->dev = ddev;
>   
>   	priv->wq = alloc_ordered_workqueue("msm", 0);
> +	if (!priv->wq)
> +		return -ENOMEM;
>   
>   	INIT_LIST_HEAD(&priv->objects);
>   	mutex_init(&priv->obj_lock);
> @@ -440,12 +442,12 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   
>   	ret = msm_init_vram(ddev);
>   	if (ret)
> -		return ret;
> +		goto err_destroy_workqueue;
>   
>   	/* Bind all our sub-components: */
>   	ret = component_bind_all(dev, ddev);
>   	if (ret)
> -		return ret;
> +		goto err_destroy_workqueue;
>   
>   	dma_set_max_seg_size(dev, UINT_MAX);
>   
> @@ -540,6 +542,8 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   
>   err_msm_uninit:
>   	msm_drm_uninit(dev);

return ret is missing here. Your code will result in double free.

However the intent was to unroll each and every action of msm_drm_init() 
in msm_drm_uninit(). So in all your cases please goto err_msm_unit.

> +err_destroy_workqueue:
> +	destroy_workqueue(priv->wq);
>   	return ret;
>   }
>   

--
With best wishes
Dmitry