On 12/15/25 16:53, Tvrtko Ursulin wrote:
>
> On 15/12/2025 15:38, Christian König wrote:
>> On 12/15/25 10:20, Tvrtko Ursulin wrote:
>>>
>>> On 12/12/2025 15:50, Christian König wrote:
>>>> On 12/11/25 16:13, Tvrtko Ursulin wrote:
>>>>>
>>>>> On 11/12/2025 13:16, Christian König wrote:
>>>>>> Using the inline lock is now the recommended way for dma_fence
>>>>>> implementations.
>>>>>>
>>>>>> So use this approach for the scheduler fences as well just in case if
>>>>>> anybody uses this as blueprint for its own implementation.
>>>>>>
>>>>>> Also saves about 4 bytes for the external spinlock.
>>>>>>
>>>>>> Signed-off-by: Christian König <[email protected]>
>>>>>> ---
>>>>>> drivers/gpu/drm/scheduler/sched_fence.c | 7 +++----
>>>>>> include/drm/gpu_scheduler.h | 4 ----
>>>>>> 2 files changed, 3 insertions(+), 8 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/scheduler/sched_fence.c
>>>>>> b/drivers/gpu/drm/scheduler/sched_fence.c
>>>>>> index 08ccbde8b2f5..47471b9e43f9 100644
>>>>>> --- a/drivers/gpu/drm/scheduler/sched_fence.c
>>>>>> +++ b/drivers/gpu/drm/scheduler/sched_fence.c
>>>>>> @@ -161,7 +161,7 @@ static void
>>>>>> drm_sched_fence_set_deadline_finished(struct dma_fence *f,
>>>>>> /* If we already have an earlier deadline, keep it: */
>>>>>> if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
>>>>>> ktime_before(fence->deadline, deadline)) {
>>>>>> - spin_unlock_irqrestore(&fence->lock, flags);
>>>>>> + dma_fence_unlock_irqrestore(f, flags);
>>>>>
>>>>> Rebase error I guess. Pull into the locking helpers patch.
>>>>
>>>> No that is actually completely intentional here.
>>>>
>>>> Previously we had a separate lock which protected both the DMA-fences as
>>>> well as the deadline state.
>>>>
>>>> Now we turn that upside down by dropping the separate lock and protecting
>>>> the deadline state with the dma_fence lock instead.
>>>
>>> I don't follow. The code is currently like this:
>>>
>>> static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
>>> ktime_t deadline)
>>> {
>>> struct drm_sched_fence *fence = to_drm_sched_fence(f);
>>> struct dma_fence *parent;
>>> unsigned long flags;
>>>
>>> spin_lock_irqsave(&fence->lock, flags);
>>>
>>> /* If we already have an earlier deadline, keep it: */
>>> if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
>>> ktime_before(fence->deadline, deadline)) {
>>> spin_unlock_irqrestore(&fence->lock, flags);
>>> return;
>>> }
>>>
>>> fence->deadline = deadline;
>>> set_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
>>>
>>> spin_unlock_irqrestore(&fence->lock, flags);...
>>>
>>> The diff changes one out of the three lock/unlock operations. Other two are
>>> changed in 3/19. All three should surely be changed in the same patch.
>>
>> We could change those spin_lock/unlock calls in patch #3, but I don't think
>> that this is clean.
>>
>> See the code here currently uses fence->lock and patch #3 would change it to
>> use fence->finished->lock instead. That might be the pointer at the moment,
>> but that is just by coincident and not design.
>>
>> Only this change here ontop makes it intentional that we use
>> fence->finished->lock for everything.
>
> Sorry I still don't follow. After 3/19 and before this 9/19 the function
> looks like this:
>
> static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
> ktime_t deadline)
> {
> struct drm_sched_fence *fence = to_drm_sched_fence(f);
> struct dma_fence *parent;
> unsigned long flags;
>
> dma_fence_lock_irqsave(f, flags);
>
> /* If we already have an earlier deadline, keep it: */
> if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
> ktime_before(fence->deadline, deadline)) {
> spin_unlock_irqrestore(&fence->lock, flags);
> return;
> }
>
> fence->deadline = deadline;
> set_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
>
> dma_fence_unlock_irqrestore(f, flags);
>
> Notice the lonely spin_unlock_irqrestore on the early return path while other
> two use the dma_fence_(un)lock helpers. Am I blind or how is that clean?
Oh, that's what you mean. Sorry I was blind!
Yeah that is clearly unintentional.
Thanks,
Christian.
>
> Regards,
>
> Tvrtko
>
>>
>> Regards,
>> Christian.
>>
>>>
>>> Regards,
>>>
>>> Tvrtko
>>>
>>>>
>>>> Regards,
>>>> Christian.
>>>>
>>>>>
>>>>> Regards,
>>>>>
>>>>> Tvrtko
>>>>>
>>>>>> return;
>>>>>> }
>>>>>> @@ -217,7 +217,6 @@ struct drm_sched_fence
>>>>>> *drm_sched_fence_alloc(struct drm_sched_entity *entity,
>>>>>> fence->owner = owner;
>>>>>> fence->drm_client_id = drm_client_id;
>>>>>> - spin_lock_init(&fence->lock);
>>>>>> return fence;
>>>>>> }
>>>>>> @@ -230,9 +229,9 @@ void drm_sched_fence_init(struct drm_sched_fence
>>>>>> *fence,
>>>>>> fence->sched = entity->rq->sched;
>>>>>> seq = atomic_inc_return(&entity->fence_seq);
>>>>>> dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
>>>>>> - &fence->lock, entity->fence_context, seq);
>>>>>> + NULL, entity->fence_context, seq);
>>>>>> dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
>>>>>> - &fence->lock, entity->fence_context + 1, seq);
>>>>>> + NULL, entity->fence_context + 1, seq);
>>>>>> }
>>>>>> module_init(drm_sched_fence_slab_init);
>>>>>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>>>>>> index fb88301b3c45..b77f24a783e3 100644
>>>>>> --- a/include/drm/gpu_scheduler.h
>>>>>> +++ b/include/drm/gpu_scheduler.h
>>>>>> @@ -297,10 +297,6 @@ struct drm_sched_fence {
>>>>>> * belongs to.
>>>>>> */
>>>>>> struct drm_gpu_scheduler *sched;
>>>>>> - /**
>>>>>> - * @lock: the lock used by the scheduled and the finished
>>>>>> fences.
>>>>>> - */
>>>>>> - spinlock_t lock;
>>>>>> /**
>>>>>> * @owner: job owner for debugging
>>>>>> */
>>>>>
>>>>
>>>
>>
>
