@@ -1795,41 +1795,25 @@ 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);
-
- if (!list_empty(&bo->ddestroy)) {
- ttm_bo_reserve_locked(bo, false, false, false, 0);
- ttm_bo_cleanup_refs_and_unlock(bo, false, false);
+ list_for_each_entry(bo, &glob->swap_lru, swap) {
+ ret = ttm_bo_reserve_locked(bo, false, true, false, 0);
+ if (!ret)
+ break;
+ }
- kref_put(&bo->list_kref, ttm_bo_release_list);
- spin_lock(&glob->lru_lock);
- continue;
- }
+ if (ret) {
+ spin_unlock(&glob->lru_lock);
+ return ret;
+ }
- /**
- * Reserve buffer. Since we unlock while sleeping, we need
- * to re-check that nobody removed us from the swap-list while
- * we slept.
- */
+ kref_get(&bo->list_kref);
- 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 (!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);
Replace the while loop with a simple for each loop, and only run the delayed destroy cleanup if we can reserve the buffer first. No race occurs, since lru lock is never dropped any more. An empty list and a list full of unreservable buffers both cause -EBUSY to be returned, which is identical to the previous situation. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> --- drivers/gpu/drm/ttm/ttm_bo.c | 44 ++++++++++++++------------------------------ 1 file changed, 14 insertions(+), 30 deletions(-)