drm: introduce drm_gem_object_[handle_]unreference_unlocked

This patch introduces the drm_gem_object_unreference_unlocked
and drm_gem_object_handle_unreference_unlocked functions that
do not require holding struct_mutex.

drm_gem_object_unreference_unlocked calls the new
->gem_free_object_unlocked entry point if available, and
otherwise just takes struct_mutex and just calls ->gem_free_object

Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 44 insertions, 5 deletions

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 8bf3770f294e..4018b3bfc72e 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -411,8 +411,19 @@ drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
         mutex_unlock(&dev->struct_mutex);
 }
 
+static void
+drm_gem_object_free_common(struct drm_gem_object *obj)
+{
+        struct drm_device *dev = obj->dev;
+        fput(obj->filp);
+        atomic_dec(&dev->object_count);
+        atomic_sub(obj->size, &dev->object_memory);
+        kfree(obj);
+}
+
 /**
  * Called after the last reference to the object has been lost.
+ * Must be called holding struct_ mutex
  *
  * Frees the object
  */
@@ -427,14 +438,40 @@ drm_gem_object_free(struct kref *kref)
         if (dev->driver->gem_free_object != NULL)
                 dev->driver->gem_free_object(obj);
 
-        fput(obj->filp);
-        atomic_dec(&dev->object_count);
-        atomic_sub(obj->size, &dev->object_memory);
-        kfree(obj);
+        drm_gem_object_free_common(obj);
 }
 EXPORT_SYMBOL(drm_gem_object_free);
 
 /**
+ * Called after the last reference to the object has been lost.
+ * Must be called without holding struct_mutex
+ *
+ * Frees the object
+ */
+void
+drm_gem_object_free_unlocked(struct kref *kref)
+{
+        struct drm_gem_object *obj = (struct drm_gem_object *) kref;
+        struct drm_device *dev = obj->dev;
+
+        if (dev->driver->gem_free_object_unlocked != NULL)
+                dev->driver->gem_free_object_unlocked(obj);
+        else if (dev->driver->gem_free_object != NULL) {
+                mutex_lock(&dev->struct_mutex);
+                dev->driver->gem_free_object(obj);
+                mutex_unlock(&dev->struct_mutex);
+        }
+
+        drm_gem_object_free_common(obj);
+}
+EXPORT_SYMBOL(drm_gem_object_free_unlocked);
+
+static void drm_gem_object_ref_bug(struct kref *list_kref)
+{
+        BUG();
+}
+
+/**
  * Called after the last handle to the object has been closed
  *
  * Removes any name for the object. Note that this must be
@@ -458,8 +495,10 @@ drm_gem_object_handle_free(struct kref *kref)
                 /*
                  * The object name held a reference to this object, drop
                  * that now.
+                *
+                * This cannot be the last reference, since the handle holds one too.
                  */
-                drm_gem_object_unreference(obj);
+                kref_put(&obj->refcount, drm_gem_object_ref_bug);
         } else
                 spin_unlock(&dev->object_name_lock);