From 57fcd550eb15bce14a7154736379dfd4ed60ae81 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 28 Oct 2020 12:31:20 +0100 Subject: [PATCH] drm/ttm: Warn on pinning without holding a reference MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Christian König Signed-off-by: Daniel Vetter Cc: Christian Koenig Cc: Huang Rui Link: https://patchwork.freedesktop.org/patch/msgid/20201028113120.3641237-1-daniel.vetter@ffwll.ch --- 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 9a03c7834b1e..fc6b619c0329 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -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); diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h index 2564e66e67d7..79b9367e0ffd 100644 --- a/include/drm/ttm/ttm_bo_api.h +++ b/include/drm/ttm/ttm_bo_api.h @@ -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; }