From patchwork Fri Apr 5 07:26:57 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Janusz Krzysztofik X-Patchwork-Id: 10886971 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 69470922 for ; Fri, 5 Apr 2019 07:27:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4881E28AC6 for ; Fri, 5 Apr 2019 07:27:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3B28828B04; Fri, 5 Apr 2019 07:27:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id DE26D28AC6 for ; Fri, 5 Apr 2019 07:27:09 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BDD8E6EA42; Fri, 5 Apr 2019 07:27:07 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTPS id CD5F76EA42; Fri, 5 Apr 2019 07:27:06 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Apr 2019 00:27:06 -0700 X-IronPort-AV: E=Sophos;i="5.60,310,1549958400"; d="scan'208";a="131667186" 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; 05 Apr 2019 00:27:03 -0700 From: Janusz Krzysztofik To: Joonas Lahtinen , Jani Nikula , Rodrigo Vivi Subject: [PATCH] drm/i915: Use drm_dev_unplug() Date: Fri, 5 Apr 2019 09:26:57 +0200 Message-Id: <20190405072657.9997-1-janusz.krzysztofik@linux.intel.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Janusz Krzysztofik , David Airlie , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, michal.wajdeczko@intel.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP 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: Chris Wilson --- 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); }