OSDN Git Service

drm: Revert syncobj timeline changes.
authorEric Anholt <eric@anholt.net>
Thu, 8 Nov 2018 16:04:22 +0000 (08:04 -0800)
committerChristian König <christian.koenig@amd.com>
Mon, 12 Nov 2018 11:54:21 +0000 (12:54 +0100)
Daniel suggested I submit this, since we're still seeing regressions
from it.  This is a revert to before 48197bc564c7 ("drm: add syncobj
timeline support v9") and its followon fixes.

Fixes this on first V3D testcase execution:

[   48.767088] ============================================
[   48.772410] WARNING: possible recursive locking detected
[   48.777739] 4.19.0-rc6+ #489 Not tainted
[   48.781668] --------------------------------------------
[   48.786993] shader_runner/3284 is trying to acquire lock:
[   48.792408] ce309d7f (&(&array->lock)->rlock){....}, at: dma_fence_add_callback+0x30/0x23c
[   48.800714]
[   48.800714] but task is already holding lock:
[   48.806559] c5952bd3 (&(&array->lock)->rlock){....}, at: dma_fence_add_callback+0x30/0x23c
[   48.814862]
[   48.814862] other info that might help us debug this:
[   48.821410]  Possible unsafe locking scenario:
[   48.821410]
[   48.827338]        CPU0
[   48.829788]        ----
[   48.832239]   lock(&(&array->lock)->rlock);
[   48.836434]   lock(&(&array->lock)->rlock);
[   48.840640]
[   48.840640]  *** DEADLOCK ***
[   48.840640]
[   48.846582]  May be due to missing lock nesting notation
[  130.763560] 1 lock held by cts-runner/3270:
[  130.767745]  #0: 7834b793 (&(&array->lock)->rlock){-...}, at: dma_fence_add_callback+0x30/0x23c
[  130.776461]
               stack backtrace:
[  130.780825] CPU: 1 PID: 3270 Comm: cts-runner Not tainted 4.19.0-rc6+ #486
[  130.787706] Hardware name: Broadcom STB (Flattened Device Tree)
[  130.793645] [<c021269c>] (unwind_backtrace) from [<c020db1c>] (show_stack+0x10/0x14)
[  130.801404] [<c020db1c>] (show_stack) from [<c0c2c4b0>] (dump_stack+0xa8/0xd4)
[  130.808642] [<c0c2c4b0>] (dump_stack) from [<c0281a84>] (__lock_acquire+0x848/0x1a68)
[  130.816483] [<c0281a84>] (__lock_acquire) from [<c02835d8>] (lock_acquire+0xd8/0x22c)
[  130.824326] [<c02835d8>] (lock_acquire) from [<c0c49948>] (_raw_spin_lock_irqsave+0x54/0x68)
[  130.832777] [<c0c49948>] (_raw_spin_lock_irqsave) from [<c086bf54>] (dma_fence_add_callback+0x30/0x23c)
[  130.842183] [<c086bf54>] (dma_fence_add_callback) from [<c086d4c8>] (dma_fence_array_enable_signaling+0x58/0xec)
[  130.852371] [<c086d4c8>] (dma_fence_array_enable_signaling) from [<c086c00c>] (dma_fence_add_callback+0xe8/0x23c)
[  130.862647] [<c086c00c>] (dma_fence_add_callback) from [<c06d8774>] (drm_syncobj_wait_ioctl+0x518/0x614)
[  130.872143] [<c06d8774>] (drm_syncobj_wait_ioctl) from [<c06b8458>] (drm_ioctl_kernel+0xb0/0xf0)
[  130.880940] [<c06b8458>] (drm_ioctl_kernel) from [<c06b8818>] (drm_ioctl+0x1d8/0x390)
[  130.888782] [<c06b8818>] (drm_ioctl) from [<c03a4510>] (do_vfs_ioctl+0xb0/0x8ac)
[  130.896187] [<c03a4510>] (do_vfs_ioctl) from [<c03a4d40>] (ksys_ioctl+0x34/0x60)
[  130.903593] [<c03a4d40>] (ksys_ioctl) from [<c0201000>] (ret_fast_syscall+0x0/0x28)

Cc: Chunming Zhou <david1.zhou@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/261044/
drivers/gpu/drm/drm_syncobj.c
include/drm/drm_syncobj.h

index da2b85e..90e0a6d 100644 (file)
@@ -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;
@@ -74,29 +71,7 @@ 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;
-};
-
-static DEFINE_SPINLOCK(signaled_fence_lock);
-static struct dma_fence signaled_fence;
 
-static struct dma_fence *drm_syncobj_get_stub_fence(void)
-{
-       spin_lock(&signaled_fence_lock);
-       if (!signaled_fence.ops) {
-               dma_fence_init(&signaled_fence,
-                              &drm_syncobj_stub_fence_ops,
-                              &signaled_fence_lock,
-                              0, 0);
-               dma_fence_signal_locked(&signaled_fence);
-       }
-       spin_unlock(&signaled_fence_lock);
-
-       return dma_fence_get(&signaled_fence);
-}
 /**
  * drm_syncobj_find - lookup and reference a sync object.
  * @file_private: drm file private pointer
@@ -123,27 +98,6 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
 }
 EXPORT_SYMBOL(drm_syncobj_find);
 
-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))
-               return drm_syncobj_get_stub_fence();
-
-       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 void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
                                            struct drm_syncobj_cb *cb,
                                            drm_syncobj_func_t func)
@@ -152,158 +106,53 @@ static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
        list_add_tail(&cb->node, &syncobj->cb_list);
 }
 
-static void drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,
-                                                 struct dma_fence **fence,
-                                                 struct drm_syncobj_cb *cb,
-                                                 drm_syncobj_func_t func)
+static int drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,
+                                                struct dma_fence **fence,
+                                                struct drm_syncobj_cb *cb,
+                                                drm_syncobj_func_t func)
 {
-       u64 pt_value = 0;
-
-       WARN_ON(*fence);
+       int ret;
 
-       if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) {
-               /*BINARY syncobj always wait on last pt */
-               pt_value = syncobj->signal_point;
+       *fence = drm_syncobj_fence_get(syncobj);
+       if (*fence)
+               return 1;
 
-               if (pt_value == 0)
-                       pt_value += DRM_SYNCOBJ_BINARY_POINT;
-       }
-
-       mutex_lock(&syncobj->cb_mutex);
-       spin_lock(&syncobj->pt_lock);
-       *fence = drm_syncobj_find_signal_pt_for_point(syncobj, pt_value);
-       spin_unlock(&syncobj->pt_lock);
-       if (!*fence)
+       spin_lock(&syncobj->lock);
+       /* We've already tried once to get a fence and failed.  Now that we
+        * 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;
+       } else {
+               *fence = NULL;
                drm_syncobj_add_callback_locked(syncobj, cb, func);
-       mutex_unlock(&syncobj->cb_mutex);
-}
-
-static void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
-                                       struct drm_syncobj_cb *cb)
-{
-       mutex_lock(&syncobj->cb_mutex);
-       list_del_init(&cb->node);
-       mutex_unlock(&syncobj->cb_mutex);
-}
+               ret = 0;
+       }
+       spin_unlock(&syncobj->lock);
 
-static void drm_syncobj_init(struct drm_syncobj *syncobj)
-{
-       spin_lock(&syncobj->pt_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->pt_lock);
+       return ret;
 }
 
-static void drm_syncobj_fini(struct drm_syncobj *syncobj)
+void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
+                             struct drm_syncobj_cb *cb,
+                             drm_syncobj_func_t func)
 {
-       struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
-
-       spin_lock(&syncobj->pt_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->pt_lock);
+       spin_lock(&syncobj->lock);
+       drm_syncobj_add_callback_locked(syncobj, cb, func);
+       spin_unlock(&syncobj->lock);
 }
 
-static int drm_syncobj_create_signal_pt(struct drm_syncobj *syncobj,
-                                       struct dma_fence *fence,
-                                       u64 point)
+void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
+                                struct drm_syncobj_cb *cb)
 {
-       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->pt_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->pt_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->pt_lock);
-       if (syncobj->signal_point >= point) {
-               DRM_WARN("A later signal is ready!");
-               spin_unlock(&syncobj->pt_lock);
-               goto exist;
-       }
-       signal_pt->value = point;
-       list_add_tail(&signal_pt->list, &syncobj->signal_pt_list);
-       syncobj->signal_point = point;
-       spin_unlock(&syncobj->pt_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;
+       spin_lock(&syncobj->lock);
+       list_del_init(&cb->node);
+       spin_unlock(&syncobj->lock);
 }
 
-static void drm_syncobj_garbage_collection(struct drm_syncobj *syncobj)
-{
-       struct drm_syncobj_signal_pt *signal_pt, *tmp, *tail_pt;
-
-       spin_lock(&syncobj->pt_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->pt_lock);
-}
 /**
  * drm_syncobj_replace_fence - replace fence in a sync object.
  * @syncobj: Sync object to replace fence in
@@ -316,30 +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;
-               LIST_HEAD(cb_list);
+       struct dma_fence *old_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);
 
-               mutex_lock(&syncobj->cb_mutex);
+       if (fence != old_fence) {
                list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) {
                        list_del_init(&cur->node);
                        cur->func(syncobj, cur);
                }
-               mutex_unlock(&syncobj->cb_mutex);
        }
+
+       spin_unlock(&syncobj->lock);
+
+       dma_fence_put(old_fence);
 }
 EXPORT_SYMBOL(drm_syncobj_replace_fence);
 
@@ -362,64 +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->pt_lock);
-       *fence = drm_syncobj_find_signal_pt_for_point(syncobj, point);
-       if (!*fence)
-               ret = -EINVAL;
-       spin_unlock(&syncobj->pt_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
@@ -429,7 +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
@@ -440,11 +229,16 @@ 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)
-               drm_syncobj_put(syncobj);
+       if (!syncobj)
+               return -ENOENT;
+
+       *fence = drm_syncobj_fence_get(syncobj);
+       if (!*fence) {
+               ret = -EINVAL;
+       }
+       drm_syncobj_put(syncobj);
        return ret;
 }
 EXPORT_SYMBOL(drm_syncobj_find_fence);
@@ -460,7 +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);
@@ -493,13 +287,7 @@ 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->pt_lock);
-       mutex_init(&syncobj->cb_mutex);
-       if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE)
-               syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;
-       else
-               syncobj->type = DRM_SYNCOBJ_TYPE_BINARY;
-       drm_syncobj_init(syncobj);
+       spin_lock_init(&syncobj->lock);
 
        if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
                ret = drm_syncobj_assign_null_handle(syncobj);
@@ -782,8 +570,7 @@ 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,
@@ -876,8 +663,9 @@ 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);
 }
 
@@ -903,8 +691,7 @@ 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;
@@ -935,9 +722,6 @@ static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 
        if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
                for (i = 0; i < count; ++i) {
-                       if (entries[i].fence)
-                               continue;
-
                        drm_syncobj_fence_get_or_add_callback(syncobjs[i],
                                                              &entries[i].fence,
                                                              &entries[i].syncobj_cb,
@@ -1169,13 +953,12 @@ 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
index ffd1f4f..2eda44d 100644 (file)
 
 struct drm_syncobj_cb;
 
-/* Move the define here for the moment to avoid exposing the UAPI just yet */
-#define DRM_SYNCOBJ_CREATE_TYPE_TIMELINE (1 << 1)
-
-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 {
        /**
@@ -49,42 +41,21 @@ 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
-        */
-       u64 timeline_context;
-       /**
-        * @timeline: syncobj timeline value, which indicates point is signaled.
+        * @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;
+       struct dma_fence __rcu *fence;
        /**
-        * @signal_point: which indicates the latest signaler point.
+        * @cb_list: List of callbacks to call when the &fence gets replaced.
         */
-       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;
        /**
-        * @pt_lock: Protects pt list.
-        */
-       spinlock_t pt_lock;
-       /**
-        * @cb_mutex: Protects syncobj cb list.
+        * @lock: Protects &cb_list and write-locks &fence.
         */
-       struct mutex cb_mutex;
+       spinlock_t lock;
        /**
         * @file: A file backing for this syncobj.
         */
@@ -97,7 +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
@@ -135,6 +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,
@@ -148,7 +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