drm: add syncobj timeline support v9

This patch is for VK_KHR_timeline_semaphore extension, semaphore is called syncobj in kernel side:
This extension introduces a new type of syncobj that has an integer payload
identifying a point in a timeline. Such timeline syncobjs support the
following operations:
   * CPU query - A host operation that allows querying the payload of the
     timeline syncobj.
   * CPU wait - A host operation that allows a blocking wait for a
     timeline syncobj to reach a specified value.
   * Device wait - A device operation that allows waiting for a
     timeline syncobj to reach a specified value.
   * Device signal - A device operation that allows advancing the
     timeline syncobj to a specified value.

v1:
Since it's a timeline, that means the front time point(PT) always is signaled before the late PT.
a. signal PT design:
Signal PT fence N depends on PT[N-1] fence and signal opertion fence, when PT[N] fence is signaled,
the timeline will increase to value of PT[N].
b. wait PT design:
Wait PT fence is signaled by reaching timeline point value, when timeline is increasing, will compare
wait PTs value with new timeline value, if PT value is lower than timeline value, then wait PT will be
signaled, otherwise keep in list. syncobj wait operation can wait on any point of timeline,
so need a RB tree to order them. And wait PT could ahead of signal PT, we need a sumission fence to
perform that.

v2:
1. remove unused DRM_SYNCOBJ_CREATE_TYPE_NORMAL. (Christian)
2. move unexposed denitions to .c file. (Daniel Vetter)
3. split up the change to drm_syncobj_find_fence() in a separate patch. (Christian)
4. split up the change to drm_syncobj_replace_fence() in a separate patch.
5. drop the submission_fence implementation and instead use wait_event() for that. (Christian)
6. WARN_ON(point != 0) for NORMAL type syncobj case. (Daniel Vetter)

v3:
1. replace normal syncobj with timeline implemenation. (Vetter and Christian)
    a. normal syncobj signal op will create a signal PT to tail of signal pt list.
    b. normal syncobj wait op will create a wait pt with last signal point, and this wait PT is only signaled by related signal point PT.
2. many bug fix and clean up
3. stub fence moving is moved to other patch.

v4：
1. fix RB tree loop with while(node=rb_first(...)). (Christian)
2. fix syncobj lifecycle. (Christian)
3. only enable_signaling when there is wait_pt. (Christian)
4. fix timeline path issues.
5. write a timeline test in libdrm

v5: (Christian)
1. semaphore is called syncobj in kernel side.
2. don't need 'timeline' characters in some function name.
3. keep syncobj cb.

v6: (Christian)
1. merge syncobj_timeline to syncobj structure.
2. simplify some check sentences.
3. some misc change.
4. fix CTS failed issue.

v7: (Christian)
1. error handling when creating signal pt.
2. remove timeline naming in func.
3. export flags in find_fence.
4. allow reset timeline.

v8:
1. use wait_event_interruptible without timeout
2. rename _TYPE_INDIVIDUAL to _TYPE_BINARY

v9:
1. rename signal_pt->base to signal_pt->fence_array to avoid misleading
2. improve kerneldoc

individual syncobj is tested by ./deqp-vk -n dEQP-VK*semaphore*
timeline syncobj is tested by ./amdgpu_test -s 9
Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Cc: Christian Konig <christian.koenig@amd.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Daniel Rakos <Daniel.Rakos@amd.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/257258/

drivers/gpu/drm/drm_syncobj.c

@@ -56,6 +56,9 @@
 #include "drm_internal.h"
 #include <drm/drm_syncobj.h>
 
+/* merge normal syncobj to timeline syncobj, the point interval is 1 */
+#define DRM_SYNCOBJ_BINARY_POINT 1
+
 struct drm_syncobj_stub_fence {
 	struct dma_fence base;
 	spinlock_t lock;
@@ -71,6 +74,11 @@ static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
 	.get_timeline_name = drm_syncobj_stub_fence_get_name,
 };
 
+struct drm_syncobj_signal_pt {
+	struct dma_fence_array *fence_array;
+	u64    value;
+	struct list_head list;
+};
 
 /**
  * drm_syncobj_find - lookup and reference a sync object.
@@ -113,8 +121,8 @@ static int drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,
 {
 	int ret;
 
-	*fence = drm_syncobj_fence_get(syncobj);
-	if (*fence)
+	ret = drm_syncobj_search_fence(syncobj, 0, 0, fence);
+	if (!ret)
 		return 1;
 
 	spin_lock(&syncobj->lock);
@@ -122,10 +130,12 @@ static int drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,
 	 * have the lock, try one more time just to be sure we don't add a
 	 * callback when a fence has already been set.
 	 */
-	if (syncobj->fence) {
-		*fence = dma_fence_get(rcu_dereference_protected(syncobj->fence,
-								 lockdep_is_held(&syncobj->lock)));
-		ret = 1;
+	if (!list_empty(&syncobj->signal_pt_list)) {
+		spin_unlock(&syncobj->lock);
+		drm_syncobj_search_fence(syncobj, 0, 0, fence);
+		if (*fence)
+			return 1;
+		spin_lock(&syncobj->lock);
 	} else {
 		*fence = NULL;
 		drm_syncobj_add_callback_locked(syncobj, cb, func);
@@ -153,6 +163,160 @@ void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
 	spin_unlock(&syncobj->lock);
 }
 
+static void drm_syncobj_init(struct drm_syncobj *syncobj)
+{
+	spin_lock(&syncobj->lock);
+	syncobj->timeline_context = dma_fence_context_alloc(1);
+	syncobj->timeline = 0;
+	syncobj->signal_point = 0;
+	init_waitqueue_head(&syncobj->wq);
+
+	INIT_LIST_HEAD(&syncobj->signal_pt_list);
+	spin_unlock(&syncobj->lock);
+}
+
+static void drm_syncobj_fini(struct drm_syncobj *syncobj)
+{
+	struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
+
+	spin_lock(&syncobj->lock);
+	list_for_each_entry_safe(signal_pt, tmp,
+				 &syncobj->signal_pt_list, list) {
+		list_del(&signal_pt->list);
+		dma_fence_put(&signal_pt->fence_array->base);
+		kfree(signal_pt);
+	}
+	spin_unlock(&syncobj->lock);
+}
+
+static struct dma_fence
+*drm_syncobj_find_signal_pt_for_point(struct drm_syncobj *syncobj,
+				      uint64_t point)
+{
+	struct drm_syncobj_signal_pt *signal_pt;
+
+	if ((syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) &&
+	    (point <= syncobj->timeline)) {
+		struct drm_syncobj_stub_fence *fence =
+			kzalloc(sizeof(struct drm_syncobj_stub_fence),
+				GFP_KERNEL);
+
+		if (!fence)
+			return NULL;
+		spin_lock_init(&fence->lock);
+		dma_fence_init(&fence->base,
+			       &drm_syncobj_stub_fence_ops,
+			       &fence->lock,
+			       syncobj->timeline_context,
+			       point);
+
+		dma_fence_signal(&fence->base);
+		return &fence->base;
+	}
+
+	list_for_each_entry(signal_pt, &syncobj->signal_pt_list, list) {
+		if (point > signal_pt->value)
+			continue;
+		if ((syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) &&
+		    (point != signal_pt->value))
+			continue;
+		return dma_fence_get(&signal_pt->fence_array->base);
+	}
+	return NULL;
+}
+
+static int drm_syncobj_create_signal_pt(struct drm_syncobj *syncobj,
+					struct dma_fence *fence,
+					u64 point)
+{
+	struct drm_syncobj_signal_pt *signal_pt =
+		kzalloc(sizeof(struct drm_syncobj_signal_pt), GFP_KERNEL);
+	struct drm_syncobj_signal_pt *tail_pt;
+	struct dma_fence **fences;
+	int num_fences = 0;
+	int ret = 0, i;
+
+	if (!signal_pt)
+		return -ENOMEM;
+	if (!fence)
+		goto out;
+
+	fences = kmalloc_array(sizeof(void *), 2, GFP_KERNEL);
+	if (!fences) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	fences[num_fences++] = dma_fence_get(fence);
+	/* timeline syncobj must take this dependency */
+	if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
+		spin_lock(&syncobj->lock);
+		if (!list_empty(&syncobj->signal_pt_list)) {
+			tail_pt = list_last_entry(&syncobj->signal_pt_list,
+						  struct drm_syncobj_signal_pt, list);
+			fences[num_fences++] =
+				dma_fence_get(&tail_pt->fence_array->base);
+		}
+		spin_unlock(&syncobj->lock);
+	}
+	signal_pt->fence_array = dma_fence_array_create(num_fences, fences,
+							syncobj->timeline_context,
+							point, false);
+	if (!signal_pt->fence_array) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	spin_lock(&syncobj->lock);
+	if (syncobj->signal_point >= point) {
+		DRM_WARN("A later signal is ready!");
+		spin_unlock(&syncobj->lock);
+		goto exist;
+	}
+	signal_pt->value = point;
+	list_add_tail(&signal_pt->list, &syncobj->signal_pt_list);
+	syncobj->signal_point = point;
+	spin_unlock(&syncobj->lock);
+	wake_up_all(&syncobj->wq);
+
+	return 0;
+exist:
+	dma_fence_put(&signal_pt->fence_array->base);
+fail:
+	for (i = 0; i < num_fences; i++)
+		dma_fence_put(fences[i]);
+	kfree(fences);
+out:
+	kfree(signal_pt);
+	return ret;
+}
+
+static void drm_syncobj_garbage_collection(struct drm_syncobj *syncobj)
+{
+	struct drm_syncobj_signal_pt *signal_pt, *tmp, *tail_pt;
+
+	spin_lock(&syncobj->lock);
+	tail_pt = list_last_entry(&syncobj->signal_pt_list,
+				  struct drm_syncobj_signal_pt,
+				  list);
+	list_for_each_entry_safe(signal_pt, tmp,
+				 &syncobj->signal_pt_list, list) {
+		if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY &&
+		    signal_pt == tail_pt)
+			continue;
+		if (dma_fence_is_signaled(&signal_pt->fence_array->base)) {
+			syncobj->timeline = signal_pt->value;
+			list_del(&signal_pt->list);
+			dma_fence_put(&signal_pt->fence_array->base);
+			kfree(signal_pt);
+		} else {
+			/*signal_pt is in order in list, from small to big, so
+			 * the later must not be signal either */
+			break;
+		}
+	}
+
+	spin_unlock(&syncobj->lock);
+}
 /**
  * drm_syncobj_replace_fence - replace fence in a sync object.
  * @syncobj: Sync object to replace fence in
@@ -165,28 +329,29 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
 			       u64 point,
 			       struct dma_fence *fence)
 {
-	struct dma_fence *old_fence;
+	u64 pt_value = point;
+
+	drm_syncobj_garbage_collection(syncobj);
+	if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) {
+		if (!fence) {
+			drm_syncobj_fini(syncobj);
+			drm_syncobj_init(syncobj);
+			return;
+		}
+		pt_value = syncobj->signal_point +
+			DRM_SYNCOBJ_BINARY_POINT;
+	}
+	drm_syncobj_create_signal_pt(syncobj, fence, pt_value);
+	if (fence) {
 		struct drm_syncobj_cb *cur, *tmp;
 
-	if (fence)
-		dma_fence_get(fence);
-
 		spin_lock(&syncobj->lock);
-
-	old_fence = rcu_dereference_protected(syncobj->fence,
-					      lockdep_is_held(&syncobj->lock));
-	rcu_assign_pointer(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);
+	}
 }
 EXPORT_SYMBOL(drm_syncobj_replace_fence);
 
@@ -209,6 +374,64 @@ static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
 	return 0;
 }
 
+static int
+drm_syncobj_point_get(struct drm_syncobj *syncobj, u64 point, u64 flags,
+		      struct dma_fence **fence)
+{
+	int ret = 0;
+
+	if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
+		ret = wait_event_interruptible(syncobj->wq,
+					       point <= syncobj->signal_point);
+		if (ret < 0)
+			return ret;
+	}
+	spin_lock(&syncobj->lock);
+	*fence = drm_syncobj_find_signal_pt_for_point(syncobj, point);
+	if (!*fence)
+		ret = -EINVAL;
+	spin_unlock(&syncobj->lock);
+	return ret;
+}
+
+/**
+ * drm_syncobj_search_fence - lookup and reference the fence in a sync object or
+ * in a timeline point
+ * @syncobj: sync object pointer
+ * @point: timeline point
+ * @flags: DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT or not
+ * @fence: out parameter for the fence
+ *
+ * if flags is DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT, the function will block
+ * here until specific timeline points is reached.
+ * if not, you need a submit thread and block in userspace until all future
+ * timeline points have materialized, only then you can submit to the kernel,
+ * otherwise, function will fail to return fence.
+ *
+ * Returns 0 on success or a negative error value on failure. On success @fence
+ * contains a reference to the fence, which must be released by calling
+ * dma_fence_put().
+ */
+int drm_syncobj_search_fence(struct drm_syncobj *syncobj, u64 point,
+			     u64 flags, struct dma_fence **fence)
+{
+	u64 pt_value = point;
+
+	if (!syncobj)
+		return -ENOENT;
+
+	drm_syncobj_garbage_collection(syncobj);
+	if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) {
+		/*BINARY syncobj always wait on last pt */
+		pt_value = syncobj->signal_point;
+
+		if (pt_value == 0)
+			pt_value += DRM_SYNCOBJ_BINARY_POINT;
+	}
+	return drm_syncobj_point_get(syncobj, pt_value, flags, fence);
+}
+EXPORT_SYMBOL(drm_syncobj_search_fence);
+
 /**
  * drm_syncobj_find_fence - lookup and reference the fence in a sync object
  * @file_private: drm file private pointer
@@ -218,7 +441,7 @@ static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
  * @fence: out parameter for the fence
  *
  * This is just a convenience function that combines drm_syncobj_find() and
- * drm_syncobj_fence_get().
+ * drm_syncobj_lookup_fence().
  *
  * Returns 0 on success or a negative error value on failure. On success @fence
  * contains a reference to the fence, which must be released by calling
@@ -229,15 +452,9 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
 			   struct dma_fence **fence)
 {
 	struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
-	int ret = 0;
-
-	if (!syncobj)
-		return -ENOENT;
+	int ret;
 
-	*fence = drm_syncobj_fence_get(syncobj);
-	if (!*fence) {
-		ret = -EINVAL;
-	}
+	ret = drm_syncobj_search_fence(syncobj, point, flags, fence);
 	drm_syncobj_put(syncobj);
 	return ret;
 }
@@ -254,7 +471,7 @@ void drm_syncobj_free(struct kref *kref)
 	struct drm_syncobj *syncobj = container_of(kref,
 						   struct drm_syncobj,
 						   refcount);
-	drm_syncobj_replace_fence(syncobj, 0, NULL);
+	drm_syncobj_fini(syncobj);
 	kfree(syncobj);
 }
 EXPORT_SYMBOL(drm_syncobj_free);
@@ -284,6 +501,11 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
 	kref_init(&syncobj->refcount);
 	INIT_LIST_HEAD(&syncobj->cb_list);
 	spin_lock_init(&syncobj->lock);
+	if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE)
+		syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;
+	else
+		syncobj->type = DRM_SYNCOBJ_TYPE_BINARY;
+	drm_syncobj_init(syncobj);
 
 	if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
 		ret = drm_syncobj_assign_null_handle(syncobj);
@@ -566,7 +788,8 @@ drm_syncobj_create_ioctl(struct drm_device *dev, void *data,
 		return -EOPNOTSUPP;
 
 	/* no valid flags yet */
-	if (args->flags & ~DRM_SYNCOBJ_CREATE_SIGNALED)
+	if (args->flags & ~(DRM_SYNCOBJ_CREATE_SIGNALED |
+			    DRM_SYNCOBJ_CREATE_TYPE_TIMELINE))
 		return -EINVAL;
 
 	return drm_syncobj_create_as_handle(file_private,
@@ -659,9 +882,8 @@ static void syncobj_wait_syncobj_func(struct drm_syncobj *syncobj,
 	struct syncobj_wait_entry *wait =
 		container_of(cb, struct syncobj_wait_entry, syncobj_cb);
 
-	/* This happens inside the syncobj lock */
-	wait->fence = dma_fence_get(rcu_dereference_protected(syncobj->fence,
-							      lockdep_is_held(&syncobj->lock)));
+	drm_syncobj_search_fence(syncobj, 0, 0, &wait->fence);
+
 	wake_up_process(wait->task);
 }
 
@@ -687,7 +909,8 @@ static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 	signaled_count = 0;
 	for (i = 0; i < count; ++i) {
 		entries[i].task = current;
-		entries[i].fence = drm_syncobj_fence_get(syncobjs[i]);
+		drm_syncobj_search_fence(syncobjs[i], 0, 0,
+					 &entries[i].fence);
 		if (!entries[i].fence) {
 			if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
 				continue;
@@ -949,12 +1172,13 @@ drm_syncobj_reset_ioctl(struct drm_device *dev, void *data,
 	if (ret < 0)
 		return ret;
 
-	for (i = 0; i < args->count_handles; i++)
-		drm_syncobj_replace_fence(syncobjs[i], 0, NULL);
-
+	for (i = 0; i < args->count_handles; i++) {
+		drm_syncobj_fini(syncobjs[i]);
+		drm_syncobj_init(syncobjs[i]);
+	}
 	drm_syncobj_array_free(syncobjs, args->count_handles);
 
-	return 0;
+	return ret;
 }
 
 int

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -2152,7 +2152,7 @@ await_fence_array(struct i915_execbuffer *eb,
 		if (!(flags & I915_EXEC_FENCE_WAIT))
 			continue;
 
-		fence = drm_syncobj_fence_get(syncobj);
+		drm_syncobj_search_fence(syncobj, 0, 0, &fence);
 		if (!fence)
 			return -EINVAL;
 

include/drm/drm_syncobj.h

@@ -30,10 +30,15 @@
 
 struct drm_syncobj_cb;
 
+enum drm_syncobj_type {
+	DRM_SYNCOBJ_TYPE_BINARY,
+	DRM_SYNCOBJ_TYPE_TIMELINE
+};
+
 /**
  * struct drm_syncobj - sync object.
  *
- * This structure defines a generic sync object which wraps a &dma_fence.
+ * This structure defines a generic sync object which is timeline based.
  */
 struct drm_syncobj {
 	/**
@@ -41,19 +46,36 @@ struct drm_syncobj {
 	 */
 	struct kref refcount;
 	/**
-	 * @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.
+	 * @type: indicate syncobj type
+	 */
+	enum drm_syncobj_type type;
+	/**
+	 * @wq: wait signal operation work queue
+	 */
+	wait_queue_head_t	wq;
+	/**
+	 * @timeline_context: fence context used by timeline
+	 */
+	u64 timeline_context;
+	/**
+	 * @timeline: syncobj timeline value, which indicates point is signaled.
+	 */
+	u64 timeline;
+	/**
+	 * @signal_point: which indicates the latest signaler point.
+	 */
+	u64 signal_point;
+	/**
+	 * @signal_pt_list: signaler point list.
 	 */
-	struct dma_fence __rcu *fence;
+	struct list_head signal_pt_list;
+
 	/**
          * @cb_list: List of callbacks to call when the &fence gets replaced.
          */
 	struct list_head cb_list;
 	/**
-	 * @lock: Protects &cb_list and write-locks &fence.
+	 * @lock: Protects syncobj list and write-locks &fence.
 	 */
 	spinlock_t lock;
 	/**
@@ -106,29 +128,6 @@ drm_syncobj_put(struct drm_syncobj *obj)
 	kref_put(&obj->refcount, drm_syncobj_free);
 }
 
-/**
- * drm_syncobj_fence_get - get a reference to a fence in a sync object
- * @syncobj: sync object.
- *
- * This acquires additional reference to &drm_syncobj.fence contained in @obj,
- * if not NULL. It is illegal to call this without already holding a reference.
- * No locks required.
- *
- * Returns:
- * Either the fence of @obj or NULL if there's none.
- */
-static inline struct dma_fence *
-drm_syncobj_fence_get(struct drm_syncobj *syncobj)
-{
-	struct dma_fence *fence;
-
-	rcu_read_lock();
-	fence = dma_fence_get_rcu_safe(&syncobj->fence);
-	rcu_read_unlock();
-
-	return fence;
-}
-
 struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
 				     u32 handle);
 void drm_syncobj_replace_fence(struct drm_syncobj *syncobj, u64 point,
@@ -142,5 +141,7 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
 int drm_syncobj_get_handle(struct drm_file *file_private,
 			   struct drm_syncobj *syncobj, u32 *handle);
 int drm_syncobj_get_fd(struct drm_syncobj *syncobj, int *p_fd);
+int drm_syncobj_search_fence(struct drm_syncobj *syncobj, u64 point, u64 flags,
+			     struct dma_fence **fence);
 
 #endif

include/uapi/drm/drm.h

@@ -717,6 +717,7 @@ struct drm_prime_handle {
 struct drm_syncobj_create {
 	__u32 handle;
 #define DRM_SYNCOBJ_CREATE_SIGNALED (1 << 0)
+#define DRM_SYNCOBJ_CREATE_TYPE_TIMELINE (1 << 1)
 	__u32 flags;
 };