drm/ttm: Make LRU removal optional v2

We are already doing this for DMA-buf imports and also for
amdgpu VM BOs for quite a while now.

If this doesn't run into any problems we are probably going
to stop removing BOs from the LRU altogether.

v2: drop BUG_ON from ttm_bo_add_to_lru

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Tested-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

2 files changed, 24 insertions, 19 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 2845fceb2fbd..06bbcd2679b2 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -173,19 +173,20 @@ void ttm_bo_add_to_lru(struct ttm_buffer_object *bo)
 
 	reservation_object_assert_held(bo->resv);
 
-	if (!(bo->mem.placement & TTM_PL_FLAG_NO_EVICT)) {
-		BUG_ON(!list_empty(&bo->lru));
+	if (!list_empty(&bo->lru))
+		return;
 
-		man = &bdev->man[bo->mem.mem_type];
-		list_add_tail(&bo->lru, &man->lru[bo->priority]);
-		kref_get(&bo->list_kref);
+	if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT)
+		return;
 
-		if (bo->ttm && !(bo->ttm->page_flags &
-				 (TTM_PAGE_FLAG_SG | TTM_PAGE_FLAG_SWAPPED))) {
-			list_add_tail(&bo->swap,
-				      &bdev->glob->swap_lru[bo->priority]);
-			kref_get(&bo->list_kref);
-		}
+	man = &bdev->man[bo->mem.mem_type];
+	list_add_tail(&bo->lru, &man->lru[bo->priority]);
+	kref_get(&bo->list_kref);
+
+	if (bo->ttm && !(bo->ttm->page_flags &
+			 (TTM_PAGE_FLAG_SG | TTM_PAGE_FLAG_SWAPPED))) {
+		list_add_tail(&bo->swap, &bdev->glob->swap_lru[bo->priority]);
+		kref_get(&bo->list_kref);
 	}
 }
 EXPORT_SYMBOL(ttm_bo_add_to_lru);
diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
index 0075eb9a0b52..957ec375a4ba 100644
--- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
+++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
@@ -69,7 +69,8 @@ void ttm_eu_backoff_reservation(struct ww_acquire_ctx *ticket,
 	list_for_each_entry(entry, list, head) {
 		struct ttm_buffer_object *bo = entry->bo;
 
-		ttm_bo_add_to_lru(bo);
+		if (list_empty(&bo->lru))
+			ttm_bo_add_to_lru(bo);
 		reservation_object_unlock(bo->resv);
 	}
 	spin_unlock(&glob->lru_lock);
@@ -93,7 +94,7 @@ EXPORT_SYMBOL(ttm_eu_backoff_reservation);
 
 int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
 			   struct list_head *list, bool intr,
-			   struct list_head *dups)
+			   struct list_head *dups, bool del_lru)
 {
 	struct ttm_bo_global *glob;
 	struct ttm_validate_buffer *entry;
@@ -172,11 +173,11 @@ int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
 		list_add(&entry->head, list);
 	}
 
-	if (ticket)
-		ww_acquire_done(ticket);
-	spin_lock(&glob->lru_lock);
-	ttm_eu_del_from_lru_locked(list);
-	spin_unlock(&glob->lru_lock);
+	if (del_lru) {
+		spin_lock(&glob->lru_lock);
+		ttm_eu_del_from_lru_locked(list);
+		spin_unlock(&glob->lru_lock);
+	}
 	return 0;
 }
 EXPORT_SYMBOL(ttm_eu_reserve_buffers);
@@ -203,7 +204,10 @@ void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
 			reservation_object_add_shared_fence(bo->resv, fence);
 		else
 			reservation_object_add_excl_fence(bo->resv, fence);
-		ttm_bo_add_to_lru(bo);
+		if (list_empty(&bo->lru))
+			ttm_bo_add_to_lru(bo);
+		else
+			ttm_bo_move_to_lru_tail(bo, NULL);
 		reservation_object_unlock(bo->resv);
 	}
 	spin_unlock(&glob->lru_lock);