Re: [PATCH v2 2/2] drm/qxl: avoid dependency lock

[poma <pomidorabelisima@gmail.com>]

On 24.09.2015 15:25, Frediano Ziglio wrote:
> qxl_bo_unref calls drm_gem_object_unreference_unlocked which
> locks dev->struct_mutex. However this lock could be already
> locked if the call came from qxl_gem_object_free.
> As we don't need to call qxl_bo_ref/qxl_bo_unref cause
> qxl_release_list_add will hold a reference by itself avoid
> to call them and the possible deadlock.
> 
> Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
> ---
>  drivers/gpu/drm/qxl/qxl_release.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/qxl/qxl_release.c b/drivers/gpu/drm/qxl/qxl_release.c
> index b66ec33..4efa8e2 100644
> --- a/drivers/gpu/drm/qxl/qxl_release.c
> +++ b/drivers/gpu/drm/qxl/qxl_release.c
> @@ -307,7 +307,7 @@ int qxl_alloc_surface_release_reserved(struct qxl_device *qdev,
>  		idr_ret = qxl_release_alloc(qdev, QXL_RELEASE_SURFACE_CMD, release);
>  		if (idr_ret < 0)
>  			return idr_ret;
> -		bo = qxl_bo_ref(to_qxl_bo(entry->tv.bo));
> +		bo = to_qxl_bo(entry->tv.bo);
>  
>  		(*release)->release_offset = create_rel->release_offset + 64;
>  
> @@ -316,8 +316,6 @@ int qxl_alloc_surface_release_reserved(struct qxl_device *qdev,
>  		info = qxl_release_map(qdev, *release);
>  		info->id = idr_ret;
>  		qxl_release_unmap(qdev, *release, info);
> -
> -		qxl_bo_unref(&bo);
>  		return 0;
>  	}
>  
> 


Tested with:
 - Rawhide-Xfce-Live-1001.iso
  \ 4.3.0-0.rc3.git2.4.fc24.x86_64
   + v2-1-2-drm-qxl-avoid-buffer-reservation-in-qxl_crtc_page_flip.patch
   + v2-2-2-drm-qxl-avoid-dependency-lock.patch

Tested-by: poma <pomidorabelisima@gmail.com>


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