linux-kernel - [PATCH AUTOSEL 5.0 256/262] drm: Reorder set_property_atomic to avoid returning with an active ww

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Message-Id: <20190327180158.10245-256-sashal@kernel.org>
Date:   Wed, 27 Mar 2019 14:01:51 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Chris Wilson <chris@...is-wilson.co.uk>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Sasha Levin <sashal@...nel.org>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.0 256/262] drm: Reorder set_property_atomic to avoid returning with an active ww_ctx

From: Chris Wilson <chris@...is-wilson.co.uk>

[ Upstream commit 227ad6d957898a88b1746e30234ece64d305f066 ]

Delay the drm_modeset_acquire_init() until after we check for an
allocation failure so that we can return immediately upon error without
having to unwind.

WARNING: lock held when returning to user space!
4.20.0+ #174 Not tainted
------------------------------------------------
syz-executor556/8153 is leaving the kernel with locks still held!
1 lock held by syz-executor556/8153:
  #0: 000000005100c85c (crtc_ww_class_acquire){+.+.}, at:
set_property_atomic+0xb3/0x330 drivers/gpu/drm/drm_mode_object.c:462

Reported-by: syzbot+6ea337c427f5083ebdf2@...kaller.appspotmail.com
Fixes: 144a7999d633 ("drm: Handle properties in the core for atomic drivers")
Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Cc: Sean Paul <sean@...rly.run>
Cc: David Airlie <airlied@...ux.ie>
Cc: <stable@...r.kernel.org> # v4.14+
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181230122842.21917-1-chris@chris-wilson.co.uk

Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/drm_mode_object.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c
index 004191d01772..15b919f90c5a 100644
--- a/drivers/gpu/drm/drm_mode_object.c
+++ b/drivers/gpu/drm/drm_mode_object.c
@@ -465,6 +465,7 @@ static int set_property_atomic(struct drm_mode_object *obj,
 
 	drm_modeset_acquire_init(&ctx, 0);
 	state->acquire_ctx = &ctx;
+
 retry:
 	if (prop == state->dev->mode_config.dpms_property) {
 		if (obj->type != DRM_MODE_OBJECT_CONNECTOR) {
-- 
2.19.1