From c1af6a76f8566eeeed049d3cf24635a43b4a83a6 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Date: Sat, 31 May 2014 09:39:22 +0900 Subject: [PATCH 1/5] gpu/drm/ttm: Fix possible division by 0 in ttm_dma_pool_shrink_scan().
list_empty(&_manager->pools) being false before taking _manager->lock does not guarantee that _manager->npools != 0 after taking _manager->lock because _manager->npools is updated under _manager->lock.
Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Cc: stable stable@kernel.org [3.3+] --- drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c index fb8259f..b751fff 100644 --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c @@ -1015,6 +1015,8 @@ ttm_dma_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) return SHRINK_STOP;
mutex_lock(&_manager->lock); + if (!_manager->npools) + goto out; pool_offset = pool_offset % _manager->npools; list_for_each_entry(p, &_manager->pools, pools) { unsigned nr_free; @@ -1034,6 +1036,7 @@ ttm_dma_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) p->pool->dev_name, p->pool->name, current->pid, nr_free, shrink_pages); } +out: mutex_unlock(&_manager->lock); return freed; }