From patchwork Thu Dec 21 06:54:24 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Packard X-Patchwork-Id: 10127013 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 63EB96019C for ; Thu, 21 Dec 2017 06:54:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5701229AAA for ; Thu, 21 Dec 2017 06:54:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4B6FB29AAD; Thu, 21 Dec 2017 06:54:38 +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=-4.2 required=2.0 tests=BAYES_00, 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 0493B29AAA for ; Thu, 21 Dec 2017 06:54:38 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5E13B6E588; Thu, 21 Dec 2017 06:54:37 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from elaine.keithp.com (home.keithp.com [63.227.221.253]) by gabe.freedesktop.org (Postfix) with ESMTP id E93EE6E583 for ; Thu, 21 Dec 2017 06:54:35 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by elaine.keithp.com (Postfix) with ESMTP id 87DE83F20635; Wed, 20 Dec 2017 22:54:35 -0800 (PST) X-Virus-Scanned: Debian amavisd-new at keithp.com Received: from elaine.keithp.com ([127.0.0.1]) by localhost (elaine.keithp.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id vvvDH6N4_MZg; Wed, 20 Dec 2017 22:54:35 -0800 (PST) Received: from vr.keithp.com (vr.keithp.com [10.0.0.39]) by elaine.keithp.com (Postfix) with ESMTP id 03D3B3F200FC; Wed, 20 Dec 2017 22:54:35 -0800 (PST) Received: by vr.keithp.com (Postfix, from userid 1000) id DD3CE740087; Wed, 20 Dec 2017 22:54:34 -0800 (PST) From: Keith Packard To: linux-kernel@vger.kernel.org, Dave Airlie , Daniel Vetter Subject: [PATCH] drm: move lease init after validation in drm_lease_create Date: Wed, 20 Dec 2017 22:54:24 -0800 Message-Id: <20171221065424.1304-1-keithp@keithp.com> X-Mailer: git-send-email 2.15.1 Cc: Keith Packard , dri-devel@lists.freedesktop.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP Patch bd36d3bab2e3d08f80766c86487090dbceed4651 fixed a deadlock in the failure path of drm_lease_create. This made the partially initialized lease object visible for a short window of time. To avoid having the lessee state appear transiently, I've rearranged the code so that the lessor fields are not filled in until the parameters are all validated and the function will succeed. Signed-off-by: Keith Packard --- drivers/gpu/drm/drm_lease.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c index 59849f02e2ad..1402c0e71b03 100644 --- a/drivers/gpu/drm/drm_lease.c +++ b/drivers/gpu/drm/drm_lease.c @@ -220,17 +220,6 @@ static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr mutex_lock(&dev->mode_config.idr_mutex); - /* Insert the new lessee into the tree */ - id = idr_alloc(&(drm_lease_owner(lessor)->lessee_idr), lessee, 1, 0, GFP_KERNEL); - if (id < 0) { - error = id; - goto out_lessee; - } - - lessee->lessee_id = id; - lessee->lessor = drm_master_get(lessor); - list_add_tail(&lessee->lessee_list, &lessor->lessees); - idr_for_each_entry(leases, entry, object) { error = 0; if (!idr_find(&dev->mode_config.crtc_idr, object)) @@ -246,6 +235,17 @@ static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr } } + /* Insert the new lessee into the tree */ + id = idr_alloc(&(drm_lease_owner(lessor)->lessee_idr), lessee, 1, 0, GFP_KERNEL); + if (id < 0) { + error = id; + goto out_lessee; + } + + lessee->lessee_id = id; + lessee->lessor = drm_master_get(lessor); + list_add_tail(&lessee->lessee_list, &lessor->lessees); + /* Move the leases over */ lessee->leases = *leases; DRM_DEBUG_LEASE("new lessee %d %p, lessor %d %p\n", lessee->lessee_id, lessee, lessor->lessee_id, lessor);