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/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 4e8563c..bade497 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -80,6 +80,46 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
}
EXPORT_SYMBOL(drm_syncobj_find);
+static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
+ struct drm_syncobj_cb *cb,
+ drm_syncobj_func_t func)
+{
+ cb->func = func;
+ list_add_tail(&cb->node, &syncobj->cb_list);
+}
+
+/**
+ * drm_syncobj_add_callback - adds a callback to syncobj::cb_list
+ * @syncobj: Sync object to which to add the callback
+ * @cb: Callback to add
+ * @func: Func to use when initializing the drm_syncobj_cb struct
+ *
+ * This adds a callback to be called next time the fence is replaced
+ */
+void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
+ struct drm_syncobj_cb *cb,
+ drm_syncobj_func_t func)
+{
+ spin_lock(&syncobj->lock);
+ drm_syncobj_add_callback_locked(syncobj, cb, func);
+ spin_unlock(&syncobj->lock);
+}
+EXPORT_SYMBOL(drm_syncobj_add_callback);
+
+/**
+ * drm_syncobj_add_callback - removes a callback to syncobj::cb_list
+ * @syncobj: Sync object from which to remove the callback
+ * @cb: Callback to remove
+ */
+void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
+ struct drm_syncobj_cb *cb)
+{
+ spin_lock(&syncobj->lock);
+ list_del_init(&cb->node);
+ spin_unlock(&syncobj->lock);
+}
+EXPORT_SYMBOL(drm_syncobj_remove_callback);
+
/**
* drm_syncobj_replace_fence - replace fence in a sync object.
* @syncobj: Sync object to replace fence in
@@ -91,10 +131,24 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
struct dma_fence *fence)
{
struct dma_fence *old_fence;
+ struct drm_syncobj_cb *cur, *tmp;
if (fence)
dma_fence_get(fence);
- old_fence = xchg(&syncobj->fence, fence);
+
+ spin_lock(&syncobj->lock);
+
+ old_fence = syncobj->fence;
+ syncobj->fence = fence;
+
+ if (fence != old_fence) {
+ list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) {
+ list_del_init(&cur->node);
+ cur->func(syncobj, cur);
+ }
+ }
+
+ spin_unlock(&syncobj->lock);
dma_fence_put(old_fence);
}
@@ -130,7 +184,7 @@ void drm_syncobj_free(struct kref *kref)
struct drm_syncobj *syncobj = container_of(kref,
struct drm_syncobj,
refcount);
- dma_fence_put(syncobj->fence);
+ drm_syncobj_replace_fence(syncobj, NULL);
kfree(syncobj);
}
EXPORT_SYMBOL(drm_syncobj_free);
@@ -146,6 +200,8 @@ static int drm_syncobj_create(struct drm_file *file_private,
return -ENOMEM;
kref_init(&syncobj->refcount);
+ INIT_LIST_HEAD(&syncobj->cb_list);
+ spin_lock_init(&syncobj->lock);
idr_preload(GFP_KERNEL);
spin_lock(&file_private->syncobj_table_lock);