Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752042AbdGaJuL (ORCPT ); Mon, 31 Jul 2017 05:50:11 -0400 Received: from regular1.263xmail.com ([211.150.99.135]:37519 "EHLO regular1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750944AbdGaJuI (ORCPT ); Mon, 31 Jul 2017 05:50:08 -0400 X-263anti-spam: KSV:0; X-MAIL-GRAY: 0 X-MAIL-DELIVERY: 1 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-RL-SENDER: mark.yao@rock-chips.com X-FST-TO: mark.yao@rock-chips.com X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: mark.yao@rock-chips.com X-UNIQUE-TAG: <5ddb67ae24b45b171782f372a447eea3> X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 From: Mark Yao To: Mark Yao , David Airlie , Heiko Stuebner Cc: dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 6/6] drm/rockchip: fix race with kms hotplug and fbdev Date: Mon, 31 Jul 2017 17:50:00 +0800 Message-Id: <1501494601-7140-1-git-send-email-mark.yao@rock-chips.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1501494569-6825-1-git-send-email-mark.yao@rock-chips.com> References: <1501494569-6825-1-git-send-email-mark.yao@rock-chips.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2075 Lines: 46 Since fb_helper is not a pointer on rockchip_drm_private, it's no need to check pointer. Kms hotplug event may race into fbdev helper initial, and fb_helper->dev may be NULL pointer, that would cause the bug: [ 0.735411] [00000200] *pgd=00000000f6ffe003, *pud=00000000f6ffe003, *pmd=0000000000000000 [ 0.736156] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 0.736648] Modules linked in: [ 0.736930] CPU: 2 PID: 20 Comm: kworker/2:0 Not tainted 4.4.41 #20 [ 0.737480] Hardware name: Rockchip RK3399 Board rev2 (BOX) (DT) [ 0.738020] Workqueue: events cdn_dp_pd_event_work [ 0.738447] task: ffffffc0f21f3100 ti: ffffffc0f2218000 task.ti: ffffffc0f2218000 [ 0.739109] PC is at mutex_lock+0x14/0x44 [ 0.739469] LR is at drm_fb_helper_hotplug_event+0x30/0x114 [ 0.756253] [] mutex_lock+0x14/0x44 [ 0.756260] [] drm_fb_helper_hotplug_event+0x30/0x114 [ 0.756271] [] rockchip_drm_output_poll_changed+0x18/0x20 [ 0.756280] [] drm_kms_helper_hotplug_event+0x28/0x34 [ 0.756286] [] cdn_dp_pd_event_work+0x394/0x3c4 [ 0.756295] [] process_one_work+0x218/0x3e0 [ 0.756302] [] worker_thread+0x2e8/0x404 [ 0.756308] [] kthread+0xe8/0xf0 [ 0.756316] [] ret_from_fork+0x10/0x40 Signed-off-by: Mark Yao --- drivers/gpu/drm/rockchip/rockchip_drm_fb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c index 81f9548..e6bd0f4 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c @@ -170,7 +170,7 @@ static void rockchip_drm_output_poll_changed(struct drm_device *dev) struct rockchip_drm_private *private = dev->dev_private; struct drm_fb_helper *fb_helper = &private->fbdev_helper; - if (fb_helper) + if (fb_helper->dev) drm_fb_helper_hotplug_event(fb_helper); } -- 1.9.1