From 2b7b3ad2fb8f904ae9ba7ca71323bc11c0978d91 Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst Date: Wed, 28 Nov 2012 11:25:42 +0000 Subject: [PATCH] drm/ttm: cope with reserved buffers on swap list in ttm_bo_swapout, v2 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 Reviewed-by: Thomas Hellstrom Signed-off-by: Dave Airlie --- drivers/gpu/drm/ttm/ttm_bo.c | 48 ++++++++++++------------------------ 1 file changed, 16 insertions(+), 32 deletions(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index ef223d581a70..9a479885bf59 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -1813,41 +1813,25 @@ 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); - - kref_put(&bo->list_kref, ttm_bo_release_list); - spin_lock(&glob->lru_lock); - continue; - } - - /** - * Reserve buffer. Since we unlock while sleeping, we need - * to re-check that nobody removed us from the swap-list while - * we slept. - */ - + list_for_each_entry(bo, &glob->swap_lru, swap) { 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);