drm/syncobj: Add a callback mechanism for replace_fence (v3)
It is useful in certain circumstances to know when the fence is replaced
in a syncobj. Specifically, it may be useful to know when the fence
goes from NULL to something valid. This does make syncobj_replace_fence
a little more expensive because it has to take a lock but, in the common
case where there is no callback list, it spends a very short amount of
time inside the lock.
v2:
- Don't lock in drm_syncobj_fence_get. We only really need to lock
around fence_replace to make the callback work.
v3:
- Fix the cb_list comment to make kbuild happy
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
index ce94d14..c00fee5 100644
--- a/include/drm/drm_syncobj.h
+++ b/include/drm/drm_syncobj.h
@@ -28,6 +28,8 @@
#include "linux/dma-fence.h"
+struct drm_syncobj_cb;
+
/**
* struct drm_syncobj - sync object.
*
@@ -43,15 +45,47 @@ struct drm_syncobj {
/**
* @fence:
* NULL or a pointer to the fence bound to this object.
+ *
+ * This field should not be used directly. Use drm_syncobj_fence_get
+ * and drm_syncobj_replace_fence instead.
*/
struct dma_fence *fence;
/**
+ * @cb_list:
+ * List of callbacks to call when the fence gets replaced
+ */
+ struct list_head cb_list;
+ /**
+ * @lock:
+ * locks cb_list and write-locks fence.
+ */
+ spinlock_t lock;
+ /**
* @file:
* a file backing for this syncobj.
*/
struct file *file;
};
+typedef void (*drm_syncobj_func_t)(struct drm_syncobj *syncobj,
+ struct drm_syncobj_cb *cb);
+
+/**
+ * struct drm_syncobj_cb - callback for drm_syncobj_add_callback
+ * @node: used by drm_syncob_add_callback to append this struct to
+ * syncobj::cb_list
+ * @func: drm_syncobj_func_t to call
+ *
+ * This struct will be initialized by drm_syncobj_add_callback, additional
+ * data can be passed along by embedding drm_syncobj_cb in another struct.
+ * The callback will get called the next time drm_syncobj_replace_fence is
+ * called.
+ */
+struct drm_syncobj_cb {
+ struct list_head node;
+ drm_syncobj_func_t func;
+};
+
void drm_syncobj_free(struct kref *kref);
/**
@@ -91,6 +125,11 @@ drm_syncobj_fence_get(struct drm_syncobj *syncobj)
struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
u32 handle);
+void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
+ struct drm_syncobj_cb *cb,
+ drm_syncobj_func_t func);
+void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
+ struct drm_syncobj_cb *cb);
void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
struct dma_fence *fence);
int drm_syncobj_find_fence(struct drm_file *file_private,
