[PATCH 5/5] [RFC]drm: add syncobj timeline support v3

zhoucm1 zhoucm1 at amd.com
Thu Aug 30 10:40:13 UTC 2018



On 2018年08月30日 15:25, Christian König wrote:
> Am 30.08.2018 um 05:50 schrieb zhoucm1:
>>
>>
>> On 2018年08月29日 19:42, Christian König wrote:
>>> Am 29.08.2018 um 12:44 schrieb Chunming Zhou:
>>>> VK_KHR_timeline_semaphore:
>>>> This extension introduces a new type of semaphore that has an 
>>>> integer payload
>>>> identifying a point in a timeline. Such timeline semaphores support 
>>>> the
>>>> following operations:
>>>>     * CPU query - A host operation that allows querying the payload 
>>>> of the
>>>>       timeline semaphore.
>>>>     * CPU wait - A host operation that allows a blocking wait for a
>>>>       timeline semaphore to reach a specified value.
>>>>     * Device wait - A device operation that allows waiting for a
>>>>       timeline semaphore to reach a specified value.
>>>>     * Device signal - A device operation that allows advancing the
>>>>       timeline semaphore to a specified value.
>>>>
>>>> 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. semaphore 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. some bug fix and clean up
>>>> 3. tested by ./deqp-vk -n dEQP-VK*semaphore* for normal syncobj
>>>>
>>>> TODO:
>>>> 1. CPU query and wait on timeline semaphore.
>>>>
>>>> Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
>>>> Cc: Christian Konig <christian.koenig at amd.com>
>>>> Cc: Dave Airlie <airlied at redhat.com>
>>>> Cc: Daniel Rakos <Daniel.Rakos at amd.com>
>>>> Cc: Daniel Vetter <daniel at ffwll.ch>
>>>> ---
>>>>   drivers/gpu/drm/drm_syncobj.c              | 593 
>>>> ++++++++++++++++-----
>>>>   drivers/gpu/drm/i915/i915_gem_execbuffer.c |   4 +-
>>>>   include/drm/drm_syncobj.h                  |  78 +--
>>>>   include/uapi/drm/drm.h                     |   1 +
>>>>   4 files changed, 505 insertions(+), 171 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_syncobj.c 
>>>> b/drivers/gpu/drm/drm_syncobj.c
>>>> index ab43559398d0..f701d9ef1b81 100644
>>>> --- a/drivers/gpu/drm/drm_syncobj.c
>>>> +++ b/drivers/gpu/drm/drm_syncobj.c
>>>> @@ -56,6 +56,50 @@
>>>>   #include "drm_internal.h"
>>>>   #include <drm/drm_syncobj.h>
>>>>   +/* merge normal syncobj to timeline syncobj, the point interval 
>>>> is 1 */
>>>> +#define DRM_SYNCOBJ_NORMAL_POINT 1
>>>> +
>>>> +struct drm_syncobj_stub_fence {
>>>> +    struct dma_fence base;
>>>> +    spinlock_t lock;
>>>> +};
>>>> +
>>>> +static const char *drm_syncobj_stub_fence_get_name(struct 
>>>> dma_fence *fence)
>>>> +{
>>>> +        return "syncobjstub";
>>>> +}
>>>> +
>>>> +static bool drm_syncobj_stub_fence_enable_signaling(struct 
>>>> dma_fence *fence)
>>>> +{
>>>> +    return !dma_fence_is_signaled(fence);
>>>> +}
>>>> +static void drm_syncobj_stub_fence_release(struct dma_fence *f)
>>>> +{
>>>> +    kfree(f);
>>>> +}
>>>> +static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
>>>> +    .get_driver_name = drm_syncobj_stub_fence_get_name,
>>>> +    .get_timeline_name = drm_syncobj_stub_fence_get_name,
>>>> +    .enable_signaling = drm_syncobj_stub_fence_enable_signaling,
>>>> +    .release = drm_syncobj_stub_fence_release,
>>>> +};
>>>
>>> Do we really need to move that around? Could reduce the size of the 
>>> patch quite a bit if we don't.
>>
>> stub fence is used widely in both normal and timeline syncobj, if you 
>> think which increase patch size, I can do a separate patch for that.
>>
>>>
>>>> +
>>>> +struct drm_syncobj_wait_pt {
>>>> +    struct drm_syncobj_stub_fence base;
>>>> +    u64    value;
>>>> +    struct rb_node   node;
>>>> +};
>>>> +struct drm_syncobj_signal_pt {
>>>> +    struct drm_syncobj_stub_fence base;
>>>> +    struct dma_fence *signal_fence;
>>>> +    struct dma_fence *pre_pt_base;
>>>> +    struct dma_fence_cb signal_cb;
>>>> +    struct dma_fence_cb pre_pt_cb;
>>>> +    struct drm_syncobj *syncobj;
>>>> +    u64    value;
>>>> +    struct list_head list;
>>>> +};
>>>
>>> What are those two structures good for
>> They are used to record wait ops points and signal ops points.
>> For timeline, they are connected by timeline value, works like:
>>     a. signal pt increase timeline value to signal_pt value when 
>> signal_pt is signaled. signal_pt is depending on previous pt fence 
>> and itself signal fence from signal ops.
>>     b. wait pt tree checks if timeline value over itself value.
>>
>> For normal, works like:
>>     a. signal pt increase 1 for syncobj_timeline->signal_point every 
>> time when signal ops is performed.
>>     b. when wait ops is comming, wait pt will fetch above last signal 
>> pt value as its wait point. wait pt will be only signaled by equal 
>> point value signal_pt.
>>
>>
>>> and why is the stub fence their base?
>> Good question, I tried to kzalloc for them as well when I debug them, 
>> I encountered a problem:
>> I lookup/find wait_pt or signal_pt successfully, but when I tried to 
>> use them, they are freed sometimes, and results in NULL point.
>> and generally, when lookup them, we often need their stub fence as 
>> well, and in the meantime,  their lifecycle are same.
>> Above reason, I make stub fence as their base.
>
> That sounds like you only did this because you messed up the lifecycle.
>
> Additional to that I don't think you correctly considered the 
> lifecycle of the waits and the sync object itself. E.g. blocking in 
> drm_syncobj_timeline_fini() until all waits are done is not a good idea.
>
> What you should do instead is to create a fence_array object with all 
> the fence we need to wait for when a wait point is requested.
Yeah, this is our initial discussion result, but when I tried to do 
that, I found that cannot meet the advance signal requirement:
     a. We need to consider the wait and signal pt value are not 
one-to-one match, it's difficult to find dependent point, at least, 
there is some overhead.
     b. because we allowed "wait-before-signal", if "wait-before-signal" 
happens, there isn't signal fence which can be used to create fence array.
So timeline value is good to resolve that.

>
> Otherwise somebody can easily construct a situation where timeline 
> sync obj A waits on B and B waits on A.
Same situation also can happens with fence-array, we only can see this 
is a programming bug with incorrect use.

>
>>
>>>
>>>> +
>>>>   /**
>>>>    * drm_syncobj_find - lookup and reference a sync object.
>>>>    * @file_private: drm file private pointer
>>>> @@ -82,59 +126,247 @@ 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)
>>>> +static void drm_syncobj_timeline_init(struct drm_syncobj_timeline
>>>> +                      *syncobj_timeline)
>>>>   {
>>>> -    cb->func = func;
>>>> -    list_add_tail(&cb->node, &syncobj->cb_list);
>>>> +    syncobj_timeline->timeline_context = dma_fence_context_alloc(1);
>>>> +    syncobj_timeline->timeline = 0;
>>>> +    syncobj_timeline->signal_point = 0;
>>>> +    init_waitqueue_head(&syncobj_timeline->wq);
>>>> +
>>>> +    syncobj_timeline->wait_pt_tree = RB_ROOT;
>>>> + INIT_LIST_HEAD(&syncobj_timeline->signal_pt_list);
>>>>   }
>>>>   -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)
>>>> +static void drm_syncobj_timeline_fini(struct drm_syncobj *syncobj,
>>>> +                      struct drm_syncobj_timeline *syncobj_timeline)
>>>>   {
>>>> -    int ret;
>>>> +    struct rb_node *node = NULL;
>>>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>>>> +    struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
>>>> +
>>>> +    spin_lock(&syncobj->lock);
>>>> +    for(node = rb_first(&syncobj_timeline->wait_pt_tree);
>>>> +        node != NULL; ) {
>>>
>>> Better use rbtree_postorder_for_each_entry_safe() for this.
>> From the comments, seems we cannot use it here, we need erase node here.
>> Comments:
>>  * Note, however, that it cannot handle other modifications that 
>> re-order the
>>  * rbtree it is iterating over. This includes calling rb_erase() on 
>> @pos, as
>>  * rb_erase() may rebalance the tree, causing us to miss some nodes.
>>  */
>
> Yeah, but your current implementation has the same problem :)
>
> You need to use something like "while (node = rb_first(...))" instead 
> if you want to destruct the whole tree.
>
> Regards,
> Christian.
>
>>
>> Thanks,
>> David Zhou
>>>
>>> Regards,
>>> Christian.
>>>
>>>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>>>> +        node = rb_next(node);
I already get the next node before erasing this node, so the "for (..." 
sentence is equal with "while (...)"

Thanks,
David Zhou

>>>> + rb_erase(&wait_pt->node,
>>>> +             &syncobj_timeline->wait_pt_tree);
>>>> +        RB_CLEAR_NODE(&wait_pt->node);
>>>> +        spin_unlock(&syncobj->lock);
>>>> +        dma_fence_wait(&wait_pt->base.base, true);
>>>> +        spin_lock(&syncobj->lock);
>>>> +        /* kfree(wait_pt) is excuted by fence put */
>>>> +        dma_fence_put(&wait_pt->base.base);
>>>> +    }
>>>> +    list_for_each_entry_safe(signal_pt, tmp,
>>>> +                 &syncobj_timeline->signal_pt_list, list) {
>>>> +        list_del(&signal_pt->list);
>>>> +        if (signal_pt->signal_fence) {
>>>> + dma_fence_remove_callback(signal_pt->signal_fence,
>>>> +                          &signal_pt->signal_cb);
>>>> +            dma_fence_put(signal_pt->signal_fence);
>>>> +        }
>>>> +        if (signal_pt->pre_pt_base) {
>>>> + dma_fence_remove_callback(signal_pt->pre_pt_base,
>>>> +                          &signal_pt->pre_pt_cb);
>>>> +            dma_fence_put(signal_pt->pre_pt_base);
>>>> +        }
>>>> +        dma_fence_put(&signal_pt->base.base);
>>>> +    }
>>>> +    spin_unlock(&syncobj->lock);
>>>> +}
>>>> +
>>>>   -    *fence = drm_syncobj_fence_get(syncobj);
>>>> -    if (*fence)
>>>> -        return 1;
>>>> +static bool drm_syncobj_normal_signal_wait_pts(struct drm_syncobj 
>>>> *syncobj,
>>>> +                           u64 signal_pt)
>>>> +{
>>>> +    struct rb_node *node = NULL;
>>>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>>>>         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);
>>>> -        ret = 0;
>>>> +    for(node = rb_first(&syncobj->syncobj_timeline.wait_pt_tree);
>>>> +        node != NULL; ) {
>>>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>>>> +        node = rb_next(node);
>>>> +        /* for normal syncobj */
>>>> +        if (wait_pt->value == signal_pt) {
>>>> +            dma_fence_signal(&wait_pt->base.base);
>>>> +            rb_erase(&wait_pt->node,
>>>> + &syncobj->syncobj_timeline.wait_pt_tree);
>>>> +            RB_CLEAR_NODE(&wait_pt->node);
>>>> +            /* kfree(wait_pt) is excuted by fence put */
>>>> +            dma_fence_put(&wait_pt->base.base);
>>>> +            spin_unlock(&syncobj->lock);
>>>> +            return true;
>>>> +        }
>>>>       }
>>>>       spin_unlock(&syncobj->lock);
>>>> +    return false;
>>>> +}
>>>>   -    return ret;
>>>> +static void drm_syncobj_timeline_signal_wait_pts(struct 
>>>> drm_syncobj *syncobj)
>>>> +{
>>>> +    struct rb_node *node = NULL;
>>>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>>>> +
>>>> +    spin_lock(&syncobj->lock);
>>>> +    for(node = rb_first(&syncobj->syncobj_timeline.wait_pt_tree);
>>>> +        node != NULL; ) {
>>>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>>>> +        node = rb_next(node);
>>>> +        if (wait_pt->value <= syncobj->syncobj_timeline.timeline) {
>>>> +            dma_fence_signal(&wait_pt->base.base);
>>>> +            rb_erase(&wait_pt->node,
>>>> + &syncobj->syncobj_timeline.wait_pt_tree);
>>>> +            RB_CLEAR_NODE(&wait_pt->node);
>>>> +            /* kfree(wait_pt) is excuted by fence put */
>>>> +            dma_fence_put(&wait_pt->base.base);
>>>> +        } else {
>>>> +            /* the loop is from left to right, the later entry 
>>>> value is
>>>> +             * bigger, so don't need to check any more */
>>>> +            break;
>>>> +        }
>>>> +    }
>>>> +    spin_unlock(&syncobj->lock);
>>>>   }
>>>>   -void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
>>>> -                  struct drm_syncobj_cb *cb,
>>>> -                  drm_syncobj_func_t func)
>>>> +
>>>> +
>>>> +static void pt_fence_cb(struct drm_syncobj_signal_pt *signal_pt)
>>>>   {
>>>> +    struct dma_fence *fence = NULL;
>>>> +    struct drm_syncobj *syncobj;
>>>> +    struct drm_syncobj_signal_pt *tail_pt;
>>>> +    u64 pt_value = signal_pt->value;
>>>> +
>>>> +    dma_fence_signal(&signal_pt->base.base);
>>>> +    fence = signal_pt->signal_fence;
>>>> +    signal_pt->signal_fence = NULL;
>>>> +    dma_fence_put(fence);
>>>> +    fence = signal_pt->pre_pt_base;
>>>> +    signal_pt->pre_pt_base = NULL;
>>>> +    dma_fence_put(fence);
>>>> +
>>>> +    syncobj = signal_pt->syncobj;
>>>>       spin_lock(&syncobj->lock);
>>>> -    drm_syncobj_add_callback_locked(syncobj, cb, func);
>>>> +    syncobj->syncobj_timeline.timeline = pt_value;
>>>> +    tail_pt = 
>>>> list_last_entry(&syncobj->syncobj_timeline.signal_pt_list,
>>>> +                  struct drm_syncobj_signal_pt, list);
>>>> +    if ((syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL && signal_pt != 
>>>> tail_pt)
>>>> +        || syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>>>> +        list_del(&signal_pt->list);
>>>> +        /* kfree(signal_pt) will be  executed by below fence put */
>>>> +        dma_fence_put(&signal_pt->base.base);
>>>> +    }
>>>>       spin_unlock(&syncobj->lock);
>>>> +    if (syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL)
>>>> +        drm_syncobj_normal_signal_wait_pts(syncobj, pt_value);
>>>> +    else
>>>> +        drm_syncobj_timeline_signal_wait_pts(syncobj);
>>>>   }
>>>> +static void pt_signal_fence_func(struct dma_fence *fence,
>>>> +                 struct dma_fence_cb *cb)
>>>> +{
>>>> +    struct drm_syncobj_signal_pt *signal_pt =
>>>> +        container_of(cb, struct drm_syncobj_signal_pt, signal_cb);
>>>>   -void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
>>>> -                 struct drm_syncobj_cb *cb)
>>>> +    if (signal_pt->pre_pt_base &&
>>>> +        !dma_fence_is_signaled(signal_pt->pre_pt_base))
>>>> +        return;
>>>> +
>>>> +    pt_fence_cb(signal_pt);
>>>> +}
>>>> +static void pt_pre_fence_func(struct dma_fence *fence,
>>>> +                 struct dma_fence_cb *cb)
>>>> +{
>>>> +    struct drm_syncobj_signal_pt *signal_pt =
>>>> +        container_of(cb, struct drm_syncobj_signal_pt, pre_pt_cb);
>>>> +
>>>> +    if (signal_pt->signal_fence &&
>>>> +        !dma_fence_is_signaled(signal_pt->pre_pt_base))
>>>> +        return;
>>>> +
>>>> +    pt_fence_cb(signal_pt);
>>>> +}
>>>> +
>>>> +static int drm_syncobj_timeline_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_stub_fence *base;
>>>> +    struct drm_syncobj_signal_pt *tail_pt;
>>>> +    struct dma_fence *tail_pt_fence = NULL;
>>>> +    int ret = 0;
>>>> +
>>>> +    if (!signal_pt)
>>>> +        return -ENOMEM;
>>>> +    if (syncobj->syncobj_timeline.signal_point >= point) {
>>>> +        DRM_WARN("A later signal is ready!");
>>>> +        goto out;
>>>> +    }
>>>> +    if (!fence)
>>>> +        goto out;
>>>> +    dma_fence_get(fence);
>>>>       spin_lock(&syncobj->lock);
>>>> -    list_del_init(&cb->node);
>>>> +    base = &signal_pt->base;
>>>> +    spin_lock_init(&base->lock);
>>>> +    dma_fence_init(&base->base,
>>>> +               &drm_syncobj_stub_fence_ops,
>>>> +               &base->lock,
>>>> + syncobj->syncobj_timeline.timeline_context, point);
>>>> +    signal_pt->signal_fence = fence;
>>>> +    /* timeline syncobj must take this dependency */
>>>> +    if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>>>> +        if (!list_empty(&syncobj->syncobj_timeline.signal_pt_list)) {
>>>> +            tail_pt = 
>>>> list_last_entry(&syncobj->syncobj_timeline.signal_pt_list,
>>>> +                          struct drm_syncobj_signal_pt, list);
>>>> +            tail_pt_fence = &tail_pt->base.base;
>>>> +            if (dma_fence_is_signaled(tail_pt_fence))
>>>> +                tail_pt_fence = NULL;
>>>> +            else
>>>> +                signal_pt->pre_pt_base =
>>>> +                    dma_fence_get(tail_pt_fence);
>>>> +        }
>>>> +    }
>>>> +
>>>> +    signal_pt->value = point;
>>>> +    syncobj->syncobj_timeline.signal_point = point;
>>>> +    signal_pt->syncobj = syncobj;
>>>> +    INIT_LIST_HEAD(&signal_pt->list);
>>>> +    list_add_tail(&signal_pt->list, 
>>>> &syncobj->syncobj_timeline.signal_pt_list);
>>>>       spin_unlock(&syncobj->lock);
>>>> +    wake_up_all(&syncobj->syncobj_timeline.wq);
>>>> +    /**
>>>> +     * Every pt is depending on signal fence and previous pt 
>>>> fence, add
>>>> +     * callbacks to them
>>>> +     */
>>>> +    ret = dma_fence_add_callback(signal_pt->signal_fence,
>>>> +                     &signal_pt->signal_cb,
>>>> +                     pt_signal_fence_func);
>>>> +
>>>> +    if (signal_pt->pre_pt_base) {
>>>> +        ret = dma_fence_add_callback(signal_pt->pre_pt_base,
>>>> +                         &signal_pt->pre_pt_cb,
>>>> +                         pt_pre_fence_func);
>>>> +        if (ret == -ENOENT)
>>>> +            pt_pre_fence_func(signal_pt->pre_pt_base,
>>>> +                      &signal_pt->pre_pt_cb);
>>>> +        else if (ret)
>>>> +            goto out;
>>>> +    } else if (ret == -ENOENT) {
>>>> +        pt_signal_fence_func(signal_pt->signal_fence,
>>>> +                     &signal_pt->signal_cb);
>>>> +    } else if (ret) {
>>>> +            goto out;
>>>> +    }
>>>> +
>>>> +    return 0;
>>>> +out:
>>>> +    dma_fence_put(&signal_pt->base.base);
>>>> +    return ret;
>>>>   }
>>>>     /**
>>>> @@ -149,53 +381,30 @@ void drm_syncobj_replace_fence(struct 
>>>> drm_syncobj *syncobj,
>>>>                      u64 point,
>>>>                      struct dma_fence *fence)
>>>>   {
>>>> -    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);
>>>> -
>>>> -    if (fence != old_fence) {
>>>> -        list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) {
>>>> -            list_del_init(&cur->node);
>>>> -            cur->func(syncobj, cur);
>>>> +    if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>>>> +        if (fence)
>>>> +            drm_syncobj_timeline_create_signal_pt(syncobj, fence,
>>>> +                                  point);
>>>> +        return;
>>>> +    } else if (syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL) {
>>>> +        u64 pt_value;
>>>> +
>>>> +        if (!fence) {
>>>> +            drm_syncobj_timeline_fini(syncobj,
>>>> + &syncobj->syncobj_timeline);
>>>> + drm_syncobj_timeline_init(&syncobj->syncobj_timeline);
>>>> +            return;
>>>>           }
>>>> +        pt_value = syncobj->syncobj_timeline.signal_point +
>>>> +            DRM_SYNCOBJ_NORMAL_POINT;
>>>> +        drm_syncobj_timeline_create_signal_pt(syncobj, fence, 
>>>> pt_value);
>>>> +        return;
>>>> +    } else {
>>>> +        DRM_ERROR("the syncobj type isn't support\n");
>>>>       }
>>>> -
>>>> -    spin_unlock(&syncobj->lock);
>>>> -
>>>> -    dma_fence_put(old_fence);
>>>>   }
>>>>   EXPORT_SYMBOL(drm_syncobj_replace_fence);
>>>>   -struct drm_syncobj_stub_fence {
>>>> -    struct dma_fence base;
>>>> -    spinlock_t lock;
>>>> -};
>>>> -
>>>> -static const char *drm_syncobj_stub_fence_get_name(struct 
>>>> dma_fence *fence)
>>>> -{
>>>> -        return "syncobjstub";
>>>> -}
>>>> -
>>>> -static bool drm_syncobj_stub_fence_enable_signaling(struct 
>>>> dma_fence *fence)
>>>> -{
>>>> -    return !dma_fence_is_signaled(fence);
>>>> -}
>>>> -
>>>> -static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
>>>> -    .get_driver_name = drm_syncobj_stub_fence_get_name,
>>>> -    .get_timeline_name = drm_syncobj_stub_fence_get_name,
>>>> -    .enable_signaling = drm_syncobj_stub_fence_enable_signaling,
>>>> -    .release = NULL,
>>>> -};
>>>> -
>>>>   static int drm_syncobj_assign_null_handle(struct drm_syncobj 
>>>> *syncobj)
>>>>   {
>>>>       struct drm_syncobj_stub_fence *fence;
>>>> @@ -215,6 +424,143 @@ static int 
>>>> drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>>>>       return 0;
>>>>   }
>>>>   +static struct drm_syncobj_wait_pt *
>>>> +drm_syncobj_timeline_lookup_wait_pt_fence(struct drm_syncobj 
>>>> *syncobj,
>>>> +                      u64 point,
>>>> +                      struct dma_fence **fence)
>>>> +{
>>>> +    struct rb_node *node = 
>>>> syncobj->syncobj_timeline.wait_pt_tree.rb_node;
>>>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>>>> +
>>>> +
>>>> +    spin_lock(&syncobj->lock);
>>>> +    while(node) {
>>>> +        int result;
>>>> +
>>>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>>>> +        result = point - wait_pt->value;
>>>> +        if (result < 0) {
>>>> +            node = node->rb_left;
>>>> +        } else if (result > 0) {
>>>> +            node = node->rb_right;
>>>> +        } else {
>>>> +            if (fence)
>>>> +            *fence = dma_fence_get(&wait_pt->base.base);
>>>> +            break;
>>>> +        }
>>>> +    }
>>>> +    spin_unlock(&syncobj->lock);
>>>> +
>>>> +    return wait_pt;
>>>> +}
>>>> +
>>>> +static struct drm_syncobj_wait_pt *
>>>> +drm_syncobj_timeline_create_wait_pt_and_return_fence(struct 
>>>> drm_syncobj *syncobj,
>>>> +                             u64 point,
>>>> +                             struct dma_fence **fence)
>>>> +{
>>>> +    struct drm_syncobj_wait_pt *wait_pt = kzalloc(sizeof(*wait_pt),
>>>> +                              GFP_KERNEL);
>>>> +    struct drm_syncobj_stub_fence *base;
>>>> +    struct rb_node **new = 
>>>> &(syncobj->syncobj_timeline.wait_pt_tree.rb_node), *parent = NULL;
>>>> +    struct drm_syncobj_signal_pt *tail_signal_pt =
>>>> + list_last_entry(&syncobj->syncobj_timeline.signal_pt_list,
>>>> +                struct drm_syncobj_signal_pt, list);
>>>> +
>>>> +    if (!wait_pt)
>>>> +        return NULL;
>>>> +    base = &wait_pt->base;
>>>> +    spin_lock_init(&base->lock);
>>>> +    dma_fence_init(&base->base,
>>>> +               &drm_syncobj_stub_fence_ops,
>>>> +               &base->lock,
>>>> + syncobj->syncobj_timeline.timeline_context, point);
>>>> +    wait_pt->value = point;
>>>> +
>>>> +    /* wait pt must be in an order, so that we can easily lookup 
>>>> and signal
>>>> +     * it */
>>>> +    spin_lock(&syncobj->lock);
>>>> +    if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE &&
>>>> +        point <= syncobj->syncobj_timeline.timeline)
>>>> +        dma_fence_signal(&wait_pt->base.base);
>>>> +    if ((syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL) &&
>>>> +        (point == tail_signal_pt->value) &&
>>>> + dma_fence_is_signaled(&tail_signal_pt->base.base))
>>>> +        dma_fence_signal(&wait_pt->base.base);
>>>> +    while(*new) {
>>>> +        struct drm_syncobj_wait_pt *this =
>>>> +            rb_entry(*new, struct drm_syncobj_wait_pt, node);
>>>> +        int result = wait_pt->value - this->value;
>>>> +
>>>> +        parent = *new;
>>>> +        if (result < 0)
>>>> +            new = &((*new)->rb_left);
>>>> +        else if (result > 0)
>>>> +            new = &((*new)->rb_right);
>>>> +        else
>>>> +            goto exist;
>>>> +    }
>>>> +    if (fence)
>>>> +        *fence = dma_fence_get(&wait_pt->base.base);
>>>> +    rb_link_node(&wait_pt->node, parent, new);
>>>> +    rb_insert_color(&wait_pt->node, 
>>>> &syncobj->syncobj_timeline.wait_pt_tree);
>>>> +    spin_unlock(&syncobj->lock);
>>>> +    return wait_pt;
>>>> +exist:
>>>> +    spin_unlock(&syncobj->lock);
>>>> +    dma_fence_put(&wait_pt->base.base);
>>>> +    wait_pt = drm_syncobj_timeline_lookup_wait_pt_fence(syncobj, 
>>>> point,
>>>> +                                fence);
>>>> +    return wait_pt;
>>>> +}
>>>> +
>>>> +static struct dma_fence *
>>>> +drm_syncobj_timeline_point_get(struct drm_syncobj *syncobj, u64 
>>>> point, u64 flags)
>>>> +{
>>>> +    struct drm_syncobj_wait_pt *wait_pt;
>>>> +    struct dma_fence *fence = NULL;
>>>> +
>>>> +    /* already signaled, simply return a signaled stub fence */
>>>> +    if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE &&
>>>> +        point <= syncobj->syncobj_timeline.timeline) {
>>>> +        struct drm_syncobj_stub_fence *fence;
>>>> +
>>>> +        fence = kzalloc(sizeof(*fence), GFP_KERNEL);
>>>> +        if (fence == NULL)
>>>> +            return NULL;
>>>> +
>>>> +        spin_lock_init(&fence->lock);
>>>> +        dma_fence_init(&fence->base, &drm_syncobj_stub_fence_ops,
>>>> +                   &fence->lock, 0, 0);
>>>> +        dma_fence_signal(&fence->base);
>>>> +        return &fence->base;
>>>> +    }
>>>> +
>>>> +    /* check if the wait pt exists */
>>>> +    wait_pt = drm_syncobj_timeline_lookup_wait_pt_fence(syncobj, 
>>>> point,
>>>> +                                &fence);
>>>> +    if (!fence) {
>>>> +        /* This is a new wait pt, so create it */
>>>> +        wait_pt = 
>>>> drm_syncobj_timeline_create_wait_pt_and_return_fence(syncobj, point,
>>>> +                                  &fence);
>>>> +        if (!fence)
>>>> +            return NULL;
>>>> +    }
>>>> +    if (wait_pt) {
>>>> +        int ret = 0;
>>>> +
>>>> +        if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
>>>> +            ret = 
>>>> wait_event_interruptible_timeout(syncobj->syncobj_timeline.wq,
>>>> +                                   wait_pt->value <= 
>>>> syncobj->syncobj_timeline.signal_point,
>>>> + msecs_to_jiffies(10000)); /* wait 10s */
>>>> +            if (ret <= 0)
>>>> +                return NULL;
>>>> +        }
>>>> +        return fence;
>>>> +    }
>>>> +    return NULL;
>>>> +}
>>>> +
>>>>   /**
>>>>    * drm_syncobj_find_fence - lookup and reference the fence in a 
>>>> sync object
>>>>    * @file_private: drm file private pointer
>>>> @@ -229,20 +575,45 @@ static int 
>>>> drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>>>>    * contains a reference to the fence, which must be released by 
>>>> calling
>>>>    * dma_fence_put().
>>>>    */
>>>> -int drm_syncobj_find_fence(struct drm_file *file_private,
>>>> -               u32 handle, u64 point,
>>>> -               struct dma_fence **fence)
>>>> +int drm_syncobj_search_fence(struct drm_syncobj *syncobj, u64 point,
>>>> +                 u64 flags, struct dma_fence **fence)
>>>>   {
>>>> -    struct drm_syncobj *syncobj = drm_syncobj_find(file_private, 
>>>> handle);
>>>>       int ret = 0;
>>>>         if (!syncobj)
>>>>           return -ENOENT;
>>>>   -    *fence = drm_syncobj_fence_get(syncobj);
>>>> +    if (syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL) {
>>>> +        /*NORMAL syncobj always wait on last pt */
>>>> +        u64 tail_pt_value = syncobj->syncobj_timeline.signal_point;
>>>> +
>>>> +        if (tail_pt_value == 0)
>>>> +            tail_pt_value += DRM_SYNCOBJ_NORMAL_POINT;
>>>> +        /* NORMAL syncobj doesn't care point value */
>>>> +        WARN_ON(point != 0);
>>>> +        *fence = drm_syncobj_timeline_point_get(syncobj, 
>>>> tail_pt_value,
>>>> +                            flags);
>>>> +    } else if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>>>> +        *fence = drm_syncobj_timeline_point_get(syncobj, point,
>>>> +                            flags);
>>>> +    } else {
>>>> +        DRM_ERROR("Don't support this type syncobj\n");
>>>> +        *fence = NULL;
>>>> +    }
>>>>       if (!*fence) {
>>>>           ret = -EINVAL;
>>>>       }
>>>> +    return ret;
>>>> +}
>>>> +EXPORT_SYMBOL(drm_syncobj_search_fence);
>>>> +int drm_syncobj_find_fence(struct drm_file *file_private,
>>>> +               u32 handle, u64 point,
>>>> +               struct dma_fence **fence) {
>>>> +    struct drm_syncobj *syncobj = drm_syncobj_find(file_private, 
>>>> handle);
>>>> +
>>>> +    int ret = drm_syncobj_search_fence(syncobj, point,
>>>> +                    DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT,
>>>> +                    fence);
>>>>       drm_syncobj_put(syncobj);
>>>>       return ret;
>>>>   }
>>>> @@ -259,7 +630,7 @@ 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_timeline_fini(syncobj, &syncobj->syncobj_timeline);
>>>>       kfree(syncobj);
>>>>   }
>>>>   EXPORT_SYMBOL(drm_syncobj_free);
>>>> @@ -287,8 +658,12 @@ int drm_syncobj_create(struct drm_syncobj 
>>>> **out_syncobj, uint32_t flags,
>>>>           return -ENOMEM;
>>>>         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_NORMAL;
>>>> + drm_syncobj_timeline_init(&syncobj->syncobj_timeline);
>>>>         if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
>>>>           ret = drm_syncobj_assign_null_handle(syncobj);
>>>> @@ -646,7 +1021,6 @@ struct syncobj_wait_entry {
>>>>       struct task_struct *task;
>>>>       struct dma_fence *fence;
>>>>       struct dma_fence_cb fence_cb;
>>>> -    struct drm_syncobj_cb syncobj_cb;
>>>>   };
>>>>     static void syncobj_wait_fence_func(struct dma_fence *fence,
>>>> @@ -658,18 +1032,6 @@ static void syncobj_wait_fence_func(struct 
>>>> dma_fence *fence,
>>>>       wake_up_process(wait->task);
>>>>   }
>>>>   -static void syncobj_wait_syncobj_func(struct drm_syncobj *syncobj,
>>>> -                      struct drm_syncobj_cb *cb)
>>>> -{
>>>> -    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)));
>>>> -    wake_up_process(wait->task);
>>>> -}
>>>> -
>>>>   static signed long drm_syncobj_array_wait_timeout(struct 
>>>> drm_syncobj **syncobjs,
>>>>                             uint32_t count,
>>>>                             uint32_t flags,
>>>> @@ -693,14 +1055,11 @@ 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]);
>>>> +        ret = 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;
>>>> -            } else {
>>>> -                ret = -EINVAL;
>>>> -                goto cleanup_entries;
>>>> -            }
>>>> +            ret = -EINVAL;
>>>> +            goto cleanup_entries;
>>>>           }
>>>>             if (dma_fence_is_signaled(entries[i].fence)) {
>>>> @@ -728,15 +1087,6 @@ static signed long 
>>>> drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
>>>>        * fallthough and try a 0 timeout wait!
>>>>        */
>>>>   -    if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
>>>> -        for (i = 0; i < count; ++i) {
>>>> - drm_syncobj_fence_get_or_add_callback(syncobjs[i],
>>>> -                                  &entries[i].fence,
>>>> - &entries[i].syncobj_cb,
>>>> - syncobj_wait_syncobj_func);
>>>> -        }
>>>> -    }
>>>> -
>>>>       do {
>>>>           set_current_state(TASK_INTERRUPTIBLE);
>>>>   @@ -784,13 +1134,10 @@ static signed long 
>>>> drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
>>>>     cleanup_entries:
>>>>       for (i = 0; i < count; ++i) {
>>>> -        if (entries[i].syncobj_cb.func)
>>>> -            drm_syncobj_remove_callback(syncobjs[i],
>>>> -                            &entries[i].syncobj_cb);
>>>> +        dma_fence_put(entries[i].fence);
>>>>           if (entries[i].fence_cb.func)
>>>>               dma_fence_remove_callback(entries[i].fence,
>>>>                             &entries[i].fence_cb);
>>>> -        dma_fence_put(entries[i].fence);
>>>>       }
>>>>       kfree(entries);
>>>>   @@ -965,12 +1312,20 @@ 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++) {
>>>> +        if (syncobjs[i]->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>>>> +            DRM_ERROR("timeline syncobj cannot reset!\n");
>>>> +            ret = -EINVAL;
>>>> +            goto out;
>>>> +        }
>>>> +        drm_syncobj_timeline_fini(syncobjs[i],
>>>> + &syncobjs[i]->syncobj_timeline);
>>>> + drm_syncobj_timeline_init(&syncobjs[i]->syncobj_timeline);
>>>> +    }
>>>> +out:
>>>>       drm_syncobj_array_free(syncobjs, args->count_handles);
>>>>   -    return 0;
>>>> +    return ret;
>>>>   }
>>>>     int
>>>> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c 
>>>> b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
>>>> index 7209dd832d39..bb20d318c9d6 100644
>>>> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
>>>> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
>>>> @@ -2182,7 +2182,9 @@ 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,
>>>> + DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT,
>>>> +                     &fence);
>>>>           if (!fence)
>>>>               return -EINVAL;
>>>>   diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
>>>> index 425432b85a87..657c97dc25ec 100644
>>>> --- a/include/drm/drm_syncobj.h
>>>> +++ b/include/drm/drm_syncobj.h
>>>> @@ -30,6 +30,25 @@
>>>>     struct drm_syncobj_cb;
>>>>   +enum drm_syncobj_type {
>>>> +    DRM_SYNCOBJ_TYPE_NORMAL,
>>>> +    DRM_SYNCOBJ_TYPE_TIMELINE
>>>> +};
>>>> +
>>>> +struct drm_syncobj_timeline {
>>>> +    wait_queue_head_t    wq;
>>>> +    u64 timeline_context;
>>>> +    /**
>>>> +     * @timeline: syncobj timeline
>>>> +     */
>>>> +    u64 timeline;
>>>> +    u64 signal_point;
>>>> +
>>>> +
>>>> +    struct rb_root wait_pt_tree;
>>>> +    struct list_head signal_pt_list;
>>>> +};
>>>> +
>>>>   /**
>>>>    * struct drm_syncobj - sync object.
>>>>    *
>>>> @@ -41,19 +60,16 @@ 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
>>>>        */
>>>> -    struct dma_fence __rcu *fence;
>>>> +    enum drm_syncobj_type type;
>>>>       /**
>>>> -     * @cb_list: List of callbacks to call when the &fence gets 
>>>> replaced.
>>>> +     * @syncobj_timeline: timeline
>>>>        */
>>>> -    struct list_head cb_list;
>>>> +    struct drm_syncobj_timeline syncobj_timeline;
>>>> +
>>>>       /**
>>>> -     * @lock: Protects &cb_list and write-locks &fence.
>>>> +     * @lock: Protects timeline list and write-locks &fence.
>>>>        */
>>>>       spinlock_t lock;
>>>>       /**
>>>> @@ -62,25 +78,6 @@ struct drm_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
>>>> - *      &drm_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);
>>>>     /**
>>>> @@ -106,29 +103,6 @@ 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 +116,7 @@ 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
>>>> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
>>>> index 300f336633f2..cebdb2541eb7 100644
>>>> --- a/include/uapi/drm/drm.h
>>>> +++ b/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;
>>>>   };
>>>
>>
>
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