Commit 57fcd550 authored Oct 28, 2020 by Daniel Vetter

drm/ttm: Warn on pinning without holding a reference



Not technically a problem for ttm, but very likely a driver bug and
pretty big time confusing for reviewing code.

So warn about it, both at cleanup time (so we catch these for sure)
and at pin/unpin time (so we know who's the culprit).

Reviewed-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Cc: Huang Rui <ray.huang@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201028113120.3641237-1-daniel.vetter@ffwll.ch

parent c6c90c70

drivers/gpu/drm/ttm/ttm_bo.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -514,7 +514,7 @@ static void ttm_bo_release(struct kref *kref)
		* shrinkers, now that they are queued for
		* destruction.
		*/
		if (bo->pin_count) {
		if (WARN_ON(bo->pin_count)) {
		bo->pin_count = 0;
		ttm_bo_del_from_lru(bo);
		ttm_bo_add_mem_to_lru(bo, &bo->mem);

include/drm/ttm/ttm_bo_api.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -600,6 +600,7 @@ static inline bool ttm_bo_uses_embedded_gem_object(struct ttm_buffer_object *bo)
		static inline void ttm_bo_pin(struct ttm_buffer_object *bo)
		{
		dma_resv_assert_held(bo->base.resv);
		WARN_ON_ONCE(!kref_read(&bo->kref));
		++bo->pin_count;
		}

		@@ -613,6 +614,7 @@ static inline void ttm_bo_unpin(struct ttm_buffer_object *bo)
		{
		dma_resv_assert_held(bo->base.resv);
		WARN_ON_ONCE(!bo->pin_count);
		WARN_ON_ONCE(!kref_read(&bo->kref));
		--bo->pin_count;
		}