[PATCH 07/10] drm/ttm: cope with reserved buffers on swap list in ttm_bo_swapout

[Maarten Lankhorst]

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at canonical.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 1d77ad1..b9c26a5 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1761,16 +1761,7 @@ static int ttm_bo_swapout(struct ttm_mem_shrink *shrink)
 	uint32_t swap_placement = (TTM_PL_FLAG_CACHED | TTM_PL_FLAG_SYSTEM);
 
 	spin_lock(&glob->lru_lock);
-	while (ret == -EBUSY) {
-		if (unlikely(list_empty(&glob->swap_lru))) {
-			spin_unlock(&glob->lru_lock);
-			return -EBUSY;
-		}
-
-		bo = list_first_entry(&glob->swap_lru,
-				      struct ttm_buffer_object, swap);
-		kref_get(&bo->list_kref);
-
+	list_for_each_entry(bo, &glob->swap_lru, swap) {
 		/**
 		 * Reserve buffer. Since we unlock while sleeping, we need
 		 * to re-check that nobody removed us from the swap-list while
@@ -1778,21 +1769,23 @@ static int ttm_bo_swapout(struct ttm_mem_shrink *shrink)
 		 */
 
 		ret = ttm_bo_reserve_locked(bo, false, true, false, 0);
-		if (unlikely(ret == -EBUSY)) {
-			spin_unlock(&glob->lru_lock);
-			ttm_bo_wait_unreserved(bo, false);
-			kref_put(&bo->list_kref, ttm_bo_release_list);
-			spin_lock(&glob->lru_lock);
-		}
+		if (!ret)
+			break;
 	}
 
+	if (ret) {
+		spin_unlock(&glob->lru_lock);
+		return ret;
+	}
+
+	kref_get(&bo->list_kref);
+
 	if (!list_empty(&bo->ddestroy)) {
 		ret = ttm_bo_cleanup_refs_and_unlock(bo, false, false);
 		kref_put(&bo->list_kref, ttm_bo_release_list);
 		return ret;
 	}
 
-	BUG_ON(ret != 0);
 	put_count = ttm_bo_del_from_lru(bo);
 	spin_unlock(&glob->lru_lock);
 
-- 
1.8.0