On Wed, Oct 28, 2020 at 01:11:51PM +0100, Christian König wrote:
> Am 28.10.20 um 12:31 schrieb Daniel Vetter:
> > 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).
> >
> > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> > Cc: Christian Koenig <christian.koenig@xxxxxxx>
> > Cc: Huang Rui <ray.huang@xxxxxxx>
>
> Reviewed-by: Christian König <christian.koenig@xxxxxxx>
Remembered this patch, pushed it. Thanks to you both for the reviews.
-Daniel
>
> > ---
> > drivers/gpu/drm/ttm/ttm_bo.c | 2 +-
> > include/drm/ttm/ttm_bo_api.h | 2 ++
> > 2 files changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> > index f51b5e20fa17..a011072ab61d 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> > @@ -509,7 +509,7 @@ 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);
> > diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> > index 37102e45e496..b45aee23d7d0 100644
> > --- a/include/drm/ttm/ttm_bo_api.h
> > +++ b/include/drm/ttm/ttm_bo_api.h
> > @@ -571,6 +571,7 @@ 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;
> > }
> > @@ -584,6 +585,7 @@ 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;
> > }
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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