From a839ed599343541edd84a37691376636d835079f Mon Sep 17 00:00:00 2001
From: Vladislav Andresov <v.andresov@partner.samsung.com>
Date: Tue, 24 Apr 2018 01:11:08 +0300
Subject: [PATCH] fix deadlock in drm_mode_obj_set_property_ioctl

Change-Id: I558a2e00c077d6c19de82acb4214d39999034c7f
Signed-off-by: Vladislav Andresov <v.andresov@partner.samsung.com>
(cherry picked from commit f6fd5336d495cf1f731c85d041e79cf3cf3a8e2b)
---
 drivers/gpu/drm/drm_crtc.c         |  2 ++
 drivers/gpu/drm/drm_fb_helper.c    | 14 ++++++++++----
 drivers/gpu/drm/drm_modeset_lock.c | 18 ++++++++++++++++++
 drivers/gpu/drm/vigs/vigs_fbdev.c  | 14 ++++++++++----
 include/drm/drm_modeset_lock.h     |  5 +++++
 5 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 5e4bb48..6f65f06 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -4966,6 +4966,7 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data,
 		return -EINVAL;
 
 	drm_modeset_lock_all(dev);
+	drm_modeset_set_locker_all(dev, current);
 
 	arg_obj = drm_mode_object_find(dev, arg->obj_id, arg->obj_type);
 	if (!arg_obj) {
@@ -5010,6 +5011,7 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data,
 	drm_property_change_valid_put(property, ref);
 
 out:
+	drm_modeset_set_locker_all(dev, NULL);
 	drm_modeset_unlock_all(dev);
 	return ret;
 }
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 5ad0367..d121492 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1294,14 +1294,18 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
 	struct drm_mode_set *modeset;
 	int ret = 0;
 	int i;
+	bool need_lock = current != drm_modeset_get_locker_all(dev);
 
 	if (oops_in_progress)
 		return -EBUSY;
 
-	drm_modeset_lock_all(dev);
+	if (need_lock) {
+		drm_modeset_lock_all(dev);
+	}
+
 	if (!drm_fb_helper_is_bound(fb_helper)) {
-		drm_modeset_unlock_all(dev);
-		return -EBUSY;
+		ret = -EBUSY;
+		goto unlock;
 	}
 
 	if (fb_helper->atomic) {
@@ -1324,7 +1328,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
 		}
 	}
 unlock:
-	drm_modeset_unlock_all(dev);
+	if (need_lock) {
+		drm_modeset_unlock_all(dev);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(drm_fb_helper_pan_display);
diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c
index 6675b14..66db681 100644
--- a/drivers/gpu/drm/drm_modeset_lock.c
+++ b/drivers/gpu/drm/drm_modeset_lock.c
@@ -455,3 +455,21 @@ int drm_modeset_lock_all_crtcs(struct drm_device *dev,
 	return 0;
 }
 EXPORT_SYMBOL(drm_modeset_lock_all_crtcs);
+
+struct task_struct *drm_modeset_get_locker_all(struct drm_device *dev)
+{
+#if defined(CONFIG_MUTEX_SPIN_ON_OWNER)
+	return ((struct mutex *)&dev->mode_config.mutex)->owner;
+#endif
+	return NULL;
+}
+EXPORT_SYMBOL(drm_modeset_get_locker_all);
+
+void drm_modeset_set_locker_all(struct drm_device *dev,
+		struct task_struct *locker)
+{
+#if defined(CONFIG_MUTEX_SPIN_ON_OWNER)
+	((struct mutex *)&dev->mode_config.mutex)->owner = locker;
+#endif
+}
+EXPORT_SYMBOL(drm_modeset_set_locker_all);
diff --git a/drivers/gpu/drm/vigs/vigs_fbdev.c b/drivers/gpu/drm/vigs/vigs_fbdev.c
index 11468ea..2f7803f 100644
--- a/drivers/gpu/drm/vigs/vigs_fbdev.c
+++ b/drivers/gpu/drm/vigs/vigs_fbdev.c
@@ -125,11 +125,15 @@ static int vigs_fbdev_setcmap(struct fb_cmap *cmap, struct fb_info *fbi)
     struct drm_crtc *crtc;
     int i, j, ret = 0;
     int start;
+    bool need_lock = current != drm_modeset_get_locker_all(dev);
+
+    if (need_lock) {
+        drm_modeset_lock_all(dev);
+    }
 
-    drm_modeset_lock_all(dev);
     if (!vigs_fbdev_helper_is_bound(fb_helper)) {
-        drm_modeset_unlock_all(dev);
-        return -EBUSY;
+        ret = -EBUSY;
+        goto out;
     }
 
     for (i = 0; i < fb_helper->crtc_count; i++) {
@@ -166,7 +170,9 @@ static int vigs_fbdev_setcmap(struct fb_cmap *cmap, struct fb_info *fbi)
     }
 
  out:
-    drm_modeset_unlock_all(dev);
+    if (need_lock) {
+        drm_modeset_unlock_all(dev);
+    }
     return ret;
 }
 
diff --git a/include/drm/drm_modeset_lock.h b/include/drm/drm_modeset_lock.h
index 94938d8..7bde5a9 100644
--- a/include/drm/drm_modeset_lock.h
+++ b/include/drm/drm_modeset_lock.h
@@ -141,4 +141,9 @@ drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);
 int drm_modeset_lock_all_crtcs(struct drm_device *dev,
 		struct drm_modeset_acquire_ctx *ctx);
 
+struct task_struct *drm_modeset_get_locker_all(struct drm_device *dev);
+
+void drm_modeset_set_locker_all(struct drm_device *dev,
+		struct task_struct *locker);
+
 #endif /* DRM_MODESET_LOCK_H_ */
-- 
2.7.4