[PATCH v2 08/10] drm/xe: remove workaround for TTM internals

[Natalie Vock <nat@pixelcluster.dev>]

This should no longer be necessary, TTM doesn't lock the BO without a
reference any more.

Only compile tested!

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Natalie Vock <nat@pixelcluster.dev>
---
 drivers/gpu/drm/xe/xe_bo.c | 32 +++++---------------------------
 1 file changed, 5 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 5843f850339c7..34eae56716076 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -1642,31 +1642,6 @@ static unsigned long xe_ttm_io_mem_pfn(struct ttm_buffer_object *ttm_bo,
 
 static void __xe_bo_vunmap(struct xe_bo *bo);
 
-/*
- * TODO: Move this function to TTM so we don't rely on how TTM does its
- * locking, thereby abusing TTM internals.
- */
-static bool xe_ttm_bo_lock_in_destructor(struct ttm_buffer_object *ttm_bo)
-{
-	struct xe_device *xe = ttm_to_xe_device(ttm_bo->bdev);
-	bool locked;
-
-	xe_assert(xe, !kref_read(&ttm_bo->base.refcount));
-
-	/*
-	 * We can typically only race with TTM trylocking under the
-	 * lru_lock, which will immediately be unlocked again since
-	 * the ttm_bo refcount is zero at this point. So trylocking *should*
-	 * always succeed here, as long as we hold the lru lock.
-	 */
-	spin_lock(&ttm_bo->bdev->lru_lock);
-	locked = dma_resv_trylock(&ttm_bo->base._resv);
-	spin_unlock(&ttm_bo->bdev->lru_lock);
-	xe_assert(xe, locked);
-
-	return locked;
-}
-
 static void xe_ttm_bo_release_notify(struct ttm_buffer_object *ttm_bo)
 {
 	struct dma_resv_iter cursor;
@@ -1680,8 +1655,11 @@ static void xe_ttm_bo_release_notify(struct ttm_buffer_object *ttm_bo)
 	bo = ttm_to_xe_bo(ttm_bo);
 	xe_assert(xe_bo_device(bo), !(bo->created && kref_read(&ttm_bo->base.refcount)));
 
-	if (!xe_ttm_bo_lock_in_destructor(ttm_bo))
-		return;
+	/*
+	 * This should never fail since there are no other references to the BO
+	 * any more.
+	 */
+	WARN_ON(!dma_resv_trylock(ttm_bo->base.resv));
 
 	/*
 	 * Scrub the preempt fences if any. The unbind fence is already

-- 
2.55.0