From: Tetsuo Handa Date: Sun, 3 Aug 2014 10:59:35 +0000 (+0900) Subject: drm/ttm: Fix possible division by 0 in ttm_dma_pool_shrink_scan(). X-Git-Tag: firefly_0821_release~3679^2~1539 X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=0f90c9c088df9196dbb322175413a79f41f9975f;p=firefly-linux-kernel-4.4.55.git drm/ttm: Fix possible division by 0 in ttm_dma_pool_shrink_scan(). commit 11e504cc705e8ccb06ac93a276e11b5e8fee4d40 upstream. 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 Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c index b8b394319b45..e9f65ad2a0eb 100644 --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c @@ -1016,6 +1016,8 @@ static int ttm_dma_pool_mm_shrink(struct shrinker *shrink, return 0; 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; @@ -1033,6 +1035,7 @@ static int ttm_dma_pool_mm_shrink(struct shrinker *shrink, p->pool->dev_name, p->pool->name, current->pid, nr_free, shrink_pages); } +out: mutex_unlock(&_manager->lock); /* return estimated number of unused pages in pool */ return ttm_dma_pool_get_num_unused_pages();