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drm/ttm: Warn on pinning without holding a reference

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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
This commit is contained in:
Daniel Vetter 2020-10-28 12:31:20 +01:00
parent c6c90c70db
commit 57fcd550eb
2 changed files with 3 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
drivers/gpu/drm/ttm/ttm_bo.c
View file

@ -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);

2
include/drm/ttm/ttm_bo_api.h
View file

@ -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;
}