From patchwork Thu Apr 18 14:51:23 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Janusz Krzysztofik X-Patchwork-Id: 10907481 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 4251717E0 for ; Thu, 18 Apr 2019 14:51:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2731228A1B for ; Thu, 18 Apr 2019 14:51:46 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2532128D96; Thu, 18 Apr 2019 14:51:46 +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=unavailable 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 C421628A1B for ; Thu, 18 Apr 2019 14:51:45 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5FB776E159; Thu, 18 Apr 2019 14:51:45 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by gabe.freedesktop.org (Postfix) with ESMTPS id 713276E159; Thu, 18 Apr 2019 14:51:40 +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 fmsmga102.fm.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 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 Subject: [Intel-gfx] [PATCH v2 1/1] drm/i915: Use drm_dev_unplug() X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: janusz.krzysztofik@intel.com, David Airlie , Daniel Vetter , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 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: 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); }