From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0767BC10F14 for ; Thu, 18 Apr 2019 14:51:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D0774206B6 for ; Thu, 18 Apr 2019 14:51:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389183AbfDROvk (ORCPT ); Thu, 18 Apr 2019 10:51:40 -0400 Received: from mga07.intel.com ([134.134.136.100]:23236 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733192AbfDROvk (ORCPT ); Thu, 18 Apr 2019 10:51:40 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Apr 2019 07:51:39 -0700 X-IronPort-AV: E=Sophos;i="5.60,366,1549958400"; d="scan'208";a="135450495" Received: from jkrzyszt-desk.igk.intel.com ([172.22.244.18]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Apr 2019 07:51:36 -0700 From: Janusz Krzysztofik To: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi Cc: David Airlie , Daniel Vetter , Chris Wilson , michal.wajdeczko@intel.com, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, janusz.krzysztofik@linux.intel.com, janusz.krzysztofik@intel.com, Daniel Vetter Subject: [PATCH v2 1/1] drm/i915: Use drm_dev_unplug() Date: Thu, 18 Apr 2019 16:51:23 +0200 Message-Id: <20190418145123.11085-2-janusz.krzysztofik@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190418145123.11085-1-janusz.krzysztofik@linux.intel.com> References: <20190405130235.7707-1-janusz.krzysztofik@linux.intel.com> <155445268803.8259.16095445514284244974@skylake-alporthouse-com> <20190415093225.GZ2665@phenom.ffwll.local> <20190418145123.11085-1-janusz.krzysztofik@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Janusz Krzysztofik The driver does not currently support unbinding from a device which is in use. Since open file descriptors may still be pointing into kernel memory where the device structures used to be, entirely correct kernel panics protect the driver from being unbound as we should not be unbinding it before those dangling pointers have been made safe. According to the documentation found inside drivers/gpu/drm/drm_drv.c, drm_dev_unplug() should be used instead of drm_dev_unregister() in order to make a device inaccessible to users as soon as it is unpluged. Follow that advice to make those possibly dangling pointers safe, protected by DRM layer from a user who is otherwise left pointing into possibly reused kernel memory after the driver has been unbound from the device. Signed-off-by: Janusz Krzysztofik Reviewed-by: Chris Wilson Reviewed-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 9df65d386d11..66163378c481 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -1596,7 +1596,7 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv) i915_pmu_unregister(dev_priv); i915_teardown_sysfs(dev_priv); - drm_dev_unregister(&dev_priv->drm); + drm_dev_unplug(&dev_priv->drm); i915_gem_shrinker_unregister(dev_priv); } -- 2.20.1