From: Christian König <easy2remember....@googlemail.com>

Still contains some bugs.

This reverts commit 48197bc564c7a1888c86024a1ba4f956e0ec2300.

Bugs: https://bugs.freedesktop.org/show_bug.cgi?id=108490
Signed-off-by: Christian König <christian.koe...@amd.com>
---
 drivers/gpu/drm/drm_syncobj.c              | 306 +++------------------
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |   2 +-
 include/drm/drm_syncobj.h                  |  67 +++--
 include/uapi/drm/drm.h                     |   1 -
 4 files changed, 75 insertions(+), 301 deletions(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 57bf6006394d..e2c5b3ca4824 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -56,9 +56,6 @@
 #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;
@@ -74,11 +71,6 @@ 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.
@@ -121,8 +113,8 @@ static int drm_syncobj_fence_get_or_add_callback(struct 
drm_syncobj *syncobj,
 {
        int ret;
 
-       ret = drm_syncobj_search_fence(syncobj, 0, 0, fence);
-       if (!ret)
+       *fence = drm_syncobj_fence_get(syncobj);
+       if (*fence)
                return 1;
 
        spin_lock(&syncobj->lock);
@@ -130,12 +122,10 @@ 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 (!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);
+       if (syncobj->fence) {
+               *fence = dma_fence_get(rcu_dereference_protected(syncobj->fence,
+                                                                
lockdep_is_held(&syncobj->lock)));
+               ret = 1;
        } else {
                *fence = NULL;
                drm_syncobj_add_callback_locked(syncobj, cb, func);
@@ -163,160 +153,6 @@ 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
@@ -329,29 +165,28 @@ void drm_syncobj_replace_fence(struct drm_syncobj 
*syncobj,
                               u64 point,
                               struct dma_fence *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;
+       struct dma_fence *old_fence;
+       struct drm_syncobj_cb *cur, *tmp;
+
+       if (fence)
+               dma_fence_get(fence);
 
-               spin_lock(&syncobj->lock);
+       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);
        }
+
+       spin_unlock(&syncobj->lock);
+
+       dma_fence_put(old_fence);
 }
 EXPORT_SYMBOL(drm_syncobj_replace_fence);
 
@@ -374,64 +209,6 @@ 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
@@ -441,7 +218,7 @@ EXPORT_SYMBOL(drm_syncobj_search_fence);
  * @fence: out parameter for the fence
  *
  * This is just a convenience function that combines drm_syncobj_find() and
- * drm_syncobj_lookup_fence().
+ * drm_syncobj_fence_get().
  *
  * 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
@@ -452,9 +229,15 @@ 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;
+       int ret = 0;
 
-       ret = drm_syncobj_search_fence(syncobj, point, flags, fence);
+       if (!syncobj)
+               return -ENOENT;
+
+       *fence = drm_syncobj_fence_get(syncobj);
+       if (!*fence) {
+               ret = -EINVAL;
+       }
        drm_syncobj_put(syncobj);
        return ret;
 }
@@ -471,7 +254,7 @@ void drm_syncobj_free(struct kref *kref)
        struct drm_syncobj *syncobj = container_of(kref,
                                                   struct drm_syncobj,
                                                   refcount);
-       drm_syncobj_fini(syncobj);
+       drm_syncobj_replace_fence(syncobj, 0, NULL);
        kfree(syncobj);
 }
 EXPORT_SYMBOL(drm_syncobj_free);
@@ -501,11 +284,6 @@ 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);
@@ -788,8 +566,7 @@ drm_syncobj_create_ioctl(struct drm_device *dev, void *data,
                return -EOPNOTSUPP;
 
        /* no valid flags yet */
-       if (args->flags & ~(DRM_SYNCOBJ_CREATE_SIGNALED |
-                           DRM_SYNCOBJ_CREATE_TYPE_TIMELINE))
+       if (args->flags & ~DRM_SYNCOBJ_CREATE_SIGNALED)
                return -EINVAL;
 
        return drm_syncobj_create_as_handle(file_private,
@@ -882,8 +659,9 @@ static void syncobj_wait_syncobj_func(struct drm_syncobj 
*syncobj,
        struct syncobj_wait_entry *wait =
                container_of(cb, struct syncobj_wait_entry, syncobj_cb);
 
-       drm_syncobj_search_fence(syncobj, 0, 0, &wait->fence);
-
+       /* This happens inside the syncobj lock */
+       wait->fence = dma_fence_get(rcu_dereference_protected(syncobj->fence,
+                                                             
lockdep_is_held(&syncobj->lock)));
        wake_up_process(wait->task);
 }
 
@@ -909,8 +687,7 @@ 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;
-               drm_syncobj_search_fence(syncobjs[i], 0, 0,
-                                        &entries[i].fence);
+               entries[i].fence = drm_syncobj_fence_get(syncobjs[i]);
                if (!entries[i].fence) {
                        if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
                                continue;
@@ -1172,13 +949,12 @@ 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_fini(syncobjs[i]);
-               drm_syncobj_init(syncobjs[i]);
-       }
+       for (i = 0; i < args->count_handles; i++)
+               drm_syncobj_replace_fence(syncobjs[i], 0, NULL);
+
        drm_syncobj_array_free(syncobjs, args->count_handles);
 
-       return ret;
+       return 0;
 }
 
 int
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c 
b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 6d99651c6c4b..22b4cb775576 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/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;
 
-               drm_syncobj_search_fence(syncobj, 0, 0, &fence);
+               fence = drm_syncobj_fence_get(syncobj);
                if (!fence)
                        return -EINVAL;
 
diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
index 5e8c5c027e09..2eda44def639 100644
--- a/include/drm/drm_syncobj.h
+++ b/include/drm/drm_syncobj.h
@@ -30,15 +30,10 @@
 
 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 is timeline based.
+ * This structure defines a generic sync object which wraps a &dma_fence.
  */
 struct drm_syncobj {
        /**
@@ -46,36 +41,19 @@ struct drm_syncobj {
         */
        struct kref refcount;
        /**
-        * @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
+        * @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.
         */
-       u64 timeline_context;
+       struct dma_fence __rcu *fence;
        /**
-        * @timeline: syncobj timeline value, which indicates point is signaled.
+        * @cb_list: List of callbacks to call when the &fence gets replaced.
         */
-       u64 timeline;
-       /**
-        * @signal_point: which indicates the latest signaler point.
-        */
-       u64 signal_point;
-       /**
-        * @signal_pt_list: signaler point list.
-        */
-       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 syncobj list and write-locks &fence.
+        * @lock: Protects &cb_list and write-locks &fence.
         */
        spinlock_t lock;
        /**
@@ -90,7 +68,7 @@ typedef void (*drm_syncobj_func_t)(struct drm_syncobj 
*syncobj,
 /**
  * struct drm_syncobj_cb - callback for drm_syncobj_add_callback
  * @node: used by drm_syncob_add_callback to append this struct to
- *       &drm_syncobj.cb_list
+ *       &drm_syncobj.cb_list
  * @func: drm_syncobj_func_t to call
  *
  * This struct will be initialized by drm_syncobj_add_callback, additional
@@ -128,6 +106,29 @@ 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,
@@ -141,7 +142,5 @@ 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
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index cebdb2541eb7..300f336633f2 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -717,7 +717,6 @@ 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;
 };
 
-- 
2.17.1

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