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SubjectRe: WARNING: lock held when returning to user space in set_property_atomic
From
Date
On 2019/01/03 18:04, Dmitry Vyukov wrote:
> On Thu, Jan 3, 2019 at 9:55 AM Maarten Lankhorst <maarten.lankhorst@linux.intel.com> wrote:
>> Just guessing..
>>
>> Does this help?

Yes it will. And while at it, let's fix another one together.

From 291e42211e3cc6d85c915772717dd08d40fb5fed Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Fri, 4 Jan 2019 15:23:47 +0900
Subject: [PATCH] gpu/drm: Fix lock held when returning to user space.

We need to call drm_modeset_acquire_fini() when drm_atomic_state_alloc()
failed or call drm_modeset_acquire_init() after drm_atomic_state_alloc()
succeeded.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+6ea337c427f5083ebdf2@syzkaller.appspotmail.com>
---
drivers/gpu/drm/drm_atomic_uapi.c | 3 +--
drivers/gpu/drm/drm_mode_object.c | 4 ++--
2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index c408898..9a1f41a 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -1296,12 +1296,11 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
(arg->flags & DRM_MODE_PAGE_FLIP_EVENT))
return -EINVAL;

- drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
-
state = drm_atomic_state_alloc(dev);
if (!state)
return -ENOMEM;

+ drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
state->acquire_ctx = &ctx;
state->allow_modeset = !!(arg->flags & DRM_MODE_ATOMIC_ALLOW_MODESET);

diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c
index cd9bc0c..004191d 100644
--- a/drivers/gpu/drm/drm_mode_object.c
+++ b/drivers/gpu/drm/drm_mode_object.c
@@ -459,11 +459,11 @@ static int set_property_atomic(struct drm_mode_object *obj,
struct drm_modeset_acquire_ctx ctx;
int ret;

- drm_modeset_acquire_init(&ctx, 0);
-
state = drm_atomic_state_alloc(dev);
if (!state)
return -ENOMEM;
+
+ drm_modeset_acquire_init(&ctx, 0);
state->acquire_ctx = &ctx;
retry:
if (prop == state->dev->mode_config.dpms_property) {
--
1.8.3.1
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