Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752991AbdLUGyj (ORCPT ); Thu, 21 Dec 2017 01:54:39 -0500 Received: from home.keithp.com ([63.227.221.253]:44490 "EHLO elaine.keithp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751739AbdLUGyg (ORCPT ); Thu, 21 Dec 2017 01:54:36 -0500 From: Keith Packard To: linux-kernel@vger.kernel.org, Dave Airlie , Daniel Vetter Cc: Keith Packard , dri-devel@lists.freedesktop.org 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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1904 Lines: 55 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); -- 2.15.1