drm/omap: fix race condition with dev->obj_list
omap_gem_objects are added to dev->obj_list in omap_gem_new, and removed
in omap_gem_free_object. Unfortunately there's no locking for
dev->obj_list, which eventually leads to a crash:
WARNING: CPU: 1 PID: 1123 at lib/list_debug.c:59 __list_del_entry+0xa4/0xe0()
list_del corruption. prev->next should be e9281344, but was ea722b84
Add a spinlock to protect dev->obj_list.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c b/drivers/gpu/drm/omapdrm/omap_drv.c
index c4c2373..c698098 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -491,6 +491,7 @@
priv->wq = alloc_ordered_workqueue("omapdrm", 0);
+ spin_lock_init(&priv->list_lock);
INIT_LIST_HEAD(&priv->obj_list);
omap_gem_init(dev);
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.h b/drivers/gpu/drm/omapdrm/omap_drv.h
index 57e11c1..b31c79f 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.h
+++ b/drivers/gpu/drm/omapdrm/omap_drv.h
@@ -105,6 +105,9 @@
struct workqueue_struct *wq;
+ /* lock for obj_list below */
+ spinlock_t list_lock;
+
/* list of GEM objects: */
struct list_head obj_list;
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index d37ee75..e9718b9 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -1273,13 +1273,16 @@
void omap_gem_free_object(struct drm_gem_object *obj)
{
struct drm_device *dev = obj->dev;
+ struct omap_drm_private *priv = dev->dev_private;
struct omap_gem_object *omap_obj = to_omap_bo(obj);
evict(obj);
WARN_ON(!mutex_is_locked(&dev->struct_mutex));
+ spin_lock(&priv->list_lock);
list_del(&omap_obj->mm_list);
+ spin_unlock(&priv->list_lock);
drm_gem_free_mmap_offset(obj);
@@ -1377,7 +1380,9 @@
if (!omap_obj)
goto fail;
+ spin_lock(&priv->list_lock);
list_add(&omap_obj->mm_list, &priv->obj_list);
+ spin_unlock(&priv->list_lock);
obj = &omap_obj->base;