Commit dbd0da24 authored by Christian König's avatar Christian König
Browse files

drm/ttm: fix locking in vmap/vunmap TTM GEM helpers 



I've stumbled over this while reviewing patches for DMA-buf and it looks
like we completely messed the locking up here.

In general most TTM function should only be called while holding the
appropriate BO resv lock. Without this we could break the internal
buffer object state here.

Only compile tested!

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Fixes: 43676605 ("drm/ttm: Add vmap/vunmap to TTM and TTM GEM helpers")
Cc: stable@vger.kernel.org
Reviewed-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220715111533.467012-1-christian.koenig@amd.com
parent 9b04369b

drivers/gpu/drm/drm_gem_ttm_helper.c

+8 −1
Original line number Diff line number Diff line
@@ -64,8 +64,13 @@ int drm_gem_ttm_vmap(struct drm_gem_object *gem, 
		     struct iosys_map *map)

{

	struct ttm_buffer_object *bo = drm_gem_ttm_of_gem(gem);

	int ret;



	dma_resv_lock(gem->resv, NULL);

	ret = ttm_bo_vmap(bo, map);

	dma_resv_unlock(gem->resv);



	return ttm_bo_vmap(bo, map);

	return ret;

}

EXPORT_SYMBOL(drm_gem_ttm_vmap);
@@ -82,7 +87,9 @@ void drm_gem_ttm_vunmap(struct drm_gem_object *gem, 
{

	struct ttm_buffer_object *bo = drm_gem_ttm_of_gem(gem);



	dma_resv_lock(gem->resv, NULL);

	ttm_bo_vunmap(bo, map);

	dma_resv_unlock(gem->resv);

}

EXPORT_SYMBOL(drm_gem_ttm_vunmap);