From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932579AbaIOWNP (ORCPT ); Mon, 15 Sep 2014 18:13:15 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:50718 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932552AbaIOWNL (ORCPT ); Mon, 15 Sep 2014 18:13:11 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Tetsuo Handa , Dave Airlie , Kamal Mostafa Subject: [PATCH 3.13 145/187] drm/ttm: Fix possible division by 0 in ttm_dma_pool_shrink_scan(). Date: Mon, 15 Sep 2014 15:09:15 -0700 Message-Id: <1410818997-9432-146-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1410818997-9432-1-git-send-email-kamal@canonical.com> References: <1410818997-9432-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.7 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa 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: Kamal Mostafa --- drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 3 +++ 1 file changed, 3 insertions(+) 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; } -- 1.9.1