On 6/2/25 15:05, Tvrtko Ursulin wrote:
>
> Hi,
>
> On 15/05/2025 14:15, Christian König wrote:
>> Hey drm-misc maintainers,
>>
>> can you guys please backmerge drm-next into drm-misc-next?
>>
>> I want to push this patch here but it depends on changes which are partially
>> in drm-next and partially in drm-misc-next.
>
> Looks like the backmerge is still pending?
Yes, @Maarten, @Maxime and @Thomas ping on this.
> In the meantime, Christian, any chance you will have some bandwith to think
> about the tail end of the series? Specifically patch 6 and how that is used
> onward.
Well the RCU grace period is quite a nifty hack. I wanted to go over it again
after merging the first patches from this series.
In general looks like a good idea to me, I just don't like that we explicitely
need to expose dma_fence_access_begin() and dma_fence_access_end().
Especially we can't do that while calling fence->ops->release.
Regards,
Christian.
>
> Regards,
>
> Tvrtko
>
>> On 5/15/25 11:49, Tvrtko Ursulin wrote:
>>> With the goal of reducing the need for drivers to touch (and dereference)
>>> fence->ops, we move the 64-bit seqnos flag from struct dma_fence_ops to
>>> the fence->flags.
>>>
>>> Drivers which were setting this flag are changed to use new
>>> dma_fence_init64() instead of dma_fence_init().
>>>
>>> v2:
>>> * Streamlined init and added kerneldoc.
>>> * Rebase for amdgpu userq which landed since.
>>>
>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@igalia.com>
>>> Reviewed-by: Christian König <christian.koe...@amd.com> # v1
>>> ---
>>> drivers/dma-buf/dma-fence-chain.c | 5 +-
>>> drivers/dma-buf/dma-fence.c | 69 ++++++++++++++-----
>>> .../drm/amd/amdgpu/amdgpu_eviction_fence.c | 7 +-
>>> .../gpu/drm/amd/amdgpu/amdgpu_userq_fence.c | 5 +-
>>> .../gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c | 5 +-
>>> include/linux/dma-fence.h | 14 ++--
>>> 6 files changed, 64 insertions(+), 41 deletions(-)
>>>
>>> diff --git a/drivers/dma-buf/dma-fence-chain.c
>>> b/drivers/dma-buf/dma-fence-chain.c
>>> index 90424f23fd73..a8a90acf4f34 100644
>>> --- a/drivers/dma-buf/dma-fence-chain.c
>>> +++ b/drivers/dma-buf/dma-fence-chain.c
>>> @@ -218,7 +218,6 @@ static void dma_fence_chain_set_deadline(struct
>>> dma_fence *fence,
>>> }
>>> const struct dma_fence_ops dma_fence_chain_ops = {
>>> - .use_64bit_seqno = true,
>>> .get_driver_name = dma_fence_chain_get_driver_name,
>>> .get_timeline_name = dma_fence_chain_get_timeline_name,
>>> .enable_signaling = dma_fence_chain_enable_signaling,
>>> @@ -262,8 +261,8 @@ void dma_fence_chain_init(struct dma_fence_chain *chain,
>>> seqno = max(prev->seqno, seqno);
>>> }
>>> - dma_fence_init(&chain->base, &dma_fence_chain_ops,
>>> - &chain->lock, context, seqno);
>>> + dma_fence_init64(&chain->base, &dma_fence_chain_ops, &chain->lock,
>>> + context, seqno);
>>> /*
>>> * Chaining dma_fence_chain container together is only allowed through
>>> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
>>> index f0cdd3e99d36..705b59787731 100644
>>> --- a/drivers/dma-buf/dma-fence.c
>>> +++ b/drivers/dma-buf/dma-fence.c
>>> @@ -989,24 +989,9 @@ void dma_fence_describe(struct dma_fence *fence,
>>> struct seq_file *seq)
>>> }
>>> EXPORT_SYMBOL(dma_fence_describe);
>>> -/**
>>> - * dma_fence_init - Initialize a custom fence.
>>> - * @fence: the fence to initialize
>>> - * @ops: the dma_fence_ops for operations on this fence
>>> - * @lock: the irqsafe spinlock to use for locking this fence
>>> - * @context: the execution context this fence is run on
>>> - * @seqno: a linear increasing sequence number for this context
>>> - *
>>> - * Initializes an allocated fence, the caller doesn't have to keep its
>>> - * refcount after committing with this fence, but it will need to hold a
>>> - * refcount again if &dma_fence_ops.enable_signaling gets called.
>>> - *
>>> - * context and seqno are used for easy comparison between fences, allowing
>>> - * to check which fence is later by simply using dma_fence_later().
>>> - */
>>> -void
>>> -dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
>>> - spinlock_t *lock, u64 context, u64 seqno)
>>> +static void
>>> +__dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
>>> + spinlock_t *lock, u64 context, u64 seqno, unsigned long flags)
>>> {
>>> BUG_ON(!lock);
>>> BUG_ON(!ops || !ops->get_driver_name || !ops->get_timeline_name);
>>> @@ -1017,9 +1002,55 @@ dma_fence_init(struct dma_fence *fence, const struct
>>> dma_fence_ops *ops,
>>> fence->lock = lock;
>>> fence->context = context;
>>> fence->seqno = seqno;
>>> - fence->flags = 0UL;
>>> + fence->flags = flags;
>>> fence->error = 0;
>>> trace_dma_fence_init(fence);
>>> }
>>> +
>>> +/**
>>> + * dma_fence_init - Initialize a custom fence.
>>> + * @fence: the fence to initialize
>>> + * @ops: the dma_fence_ops for operations on this fence
>>> + * @lock: the irqsafe spinlock to use for locking this fence
>>> + * @context: the execution context this fence is run on
>>> + * @seqno: a linear increasing sequence number for this context
>>> + *
>>> + * Initializes an allocated fence, the caller doesn't have to keep its
>>> + * refcount after committing with this fence, but it will need to hold a
>>> + * refcount again if &dma_fence_ops.enable_signaling gets called.
>>> + *
>>> + * context and seqno are used for easy comparison between fences, allowing
>>> + * to check which fence is later by simply using dma_fence_later().
>>> + */
>>> +void
>>> +dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
>>> + spinlock_t *lock, u64 context, u64 seqno)
>>> +{
>>> + __dma_fence_init(fence, ops, lock, context, seqno, 0UL);
>>> +}
>>> EXPORT_SYMBOL(dma_fence_init);
>>> +
>>> +/**
>>> + * dma_fence_init64 - Initialize a custom fence with 64-bit seqno support.
>>> + * @fence: the fence to initialize
>>> + * @ops: the dma_fence_ops for operations on this fence
>>> + * @lock: the irqsafe spinlock to use for locking this fence
>>> + * @context: the execution context this fence is run on
>>> + * @seqno: a linear increasing sequence number for this context
>>> + *
>>> + * Initializes an allocated fence, the caller doesn't have to keep its
>>> + * refcount after committing with this fence, but it will need to hold a
>>> + * refcount again if &dma_fence_ops.enable_signaling gets called.
>>> + *
>>> + * Context and seqno are used for easy comparison between fences, allowing
>>> + * to check which fence is later by simply using dma_fence_later().
>>> + */
>>> +void
>>> +dma_fence_init64(struct dma_fence *fence, const struct dma_fence_ops *ops,
>>> + spinlock_t *lock, u64 context, u64 seqno)
>>> +{
>>> + __dma_fence_init(fence, ops, lock, context, seqno,
>>> + BIT(DMA_FENCE_FLAG_SEQNO64_BIT));
>>> +}
>>> +EXPORT_SYMBOL(dma_fence_init64);
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c
>>> index 1a7469543db5..79713421bffe 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c
>>> @@ -134,7 +134,6 @@ static bool
>>> amdgpu_eviction_fence_enable_signaling(struct dma_fence *f)
>>> }
>>> static const struct dma_fence_ops amdgpu_eviction_fence_ops = {
>>> - .use_64bit_seqno = true,
>>> .get_driver_name = amdgpu_eviction_fence_get_driver_name,
>>> .get_timeline_name = amdgpu_eviction_fence_get_timeline_name,
>>> .enable_signaling = amdgpu_eviction_fence_enable_signaling,
>>> @@ -160,9 +159,9 @@ amdgpu_eviction_fence_create(struct
>>> amdgpu_eviction_fence_mgr *evf_mgr)
>>> ev_fence->evf_mgr = evf_mgr;
>>> get_task_comm(ev_fence->timeline_name, current);
>>> spin_lock_init(&ev_fence->lock);
>>> - dma_fence_init(&ev_fence->base, &amdgpu_eviction_fence_ops,
>>> - &ev_fence->lock, evf_mgr->ev_fence_ctx,
>>> - atomic_inc_return(&evf_mgr->ev_fence_seq));
>>> + dma_fence_init64(&ev_fence->base, &amdgpu_eviction_fence_ops,
>>> + &ev_fence->lock, evf_mgr->ev_fence_ctx,
>>> + atomic_inc_return(&evf_mgr->ev_fence_seq));
>>> return ev_fence;
>>> }
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>>> index 029cb24c28b3..5e92d00a591f 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>>> @@ -239,8 +239,8 @@ static int amdgpu_userq_fence_create(struct
>>> amdgpu_usermode_queue *userq,
>>> fence = &userq_fence->base;
>>> userq_fence->fence_drv = fence_drv;
>>> - dma_fence_init(fence, &amdgpu_userq_fence_ops, &userq_fence->lock,
>>> - fence_drv->context, seq);
>>> + dma_fence_init64(fence, &amdgpu_userq_fence_ops, &userq_fence->lock,
>>> + fence_drv->context, seq);
>>> amdgpu_userq_fence_driver_get(fence_drv);
>>> dma_fence_get(fence);
>>> @@ -334,7 +334,6 @@ static void amdgpu_userq_fence_release(struct dma_fence
>>> *f)
>>> }
>>> static const struct dma_fence_ops amdgpu_userq_fence_ops = {
>>> - .use_64bit_seqno = true,
>>> .get_driver_name = amdgpu_userq_fence_get_driver_name,
>>> .get_timeline_name = amdgpu_userq_fence_get_timeline_name,
>>> .signaled = amdgpu_userq_fence_signaled,
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
>>> index 51cddfa3f1e8..5d26797356a3 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
>>> @@ -71,7 +71,6 @@ static void amdgpu_tlb_fence_work(struct work_struct
>>> *work)
>>> }
>>> static const struct dma_fence_ops amdgpu_tlb_fence_ops = {
>>> - .use_64bit_seqno = true,
>>> .get_driver_name = amdgpu_tlb_fence_get_driver_name,
>>> .get_timeline_name = amdgpu_tlb_fence_get_timeline_name
>>> };
>>> @@ -101,8 +100,8 @@ void amdgpu_vm_tlb_fence_create(struct amdgpu_device
>>> *adev, struct amdgpu_vm *vm
>>> INIT_WORK(&f->work, amdgpu_tlb_fence_work);
>>> spin_lock_init(&f->lock);
>>> - dma_fence_init(&f->base, &amdgpu_tlb_fence_ops, &f->lock,
>>> - vm->tlb_fence_context, atomic64_read(&vm->tlb_seq));
>>> + dma_fence_init64(&f->base, &amdgpu_tlb_fence_ops, &f->lock,
>>> + vm->tlb_fence_context, atomic64_read(&vm->tlb_seq));
>>> /* TODO: We probably need a separate wq here */
>>> dma_fence_get(&f->base);
>>> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
>>> index 48b5202c531d..a34a0dcdc446 100644
>>> --- a/include/linux/dma-fence.h
>>> +++ b/include/linux/dma-fence.h
>>> @@ -97,6 +97,7 @@ struct dma_fence {
>>> };
>>> enum dma_fence_flag_bits {
>>> + DMA_FENCE_FLAG_SEQNO64_BIT,
>>> DMA_FENCE_FLAG_SIGNALED_BIT,
>>> DMA_FENCE_FLAG_TIMESTAMP_BIT,
>>> DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
>>> @@ -124,14 +125,6 @@ struct dma_fence_cb {
>>> *
>>> */
>>> struct dma_fence_ops {
>>> - /**
>>> - * @use_64bit_seqno:
>>> - *
>>> - * True if this dma_fence implementation uses 64bit seqno, false
>>> - * otherwise.
>>> - */
>>> - bool use_64bit_seqno;
>>> -
>>> /**
>>> * @get_driver_name:
>>> *
>>> @@ -262,6 +255,9 @@ struct dma_fence_ops {
>>> void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops
>>> *ops,
>>> spinlock_t *lock, u64 context, u64 seqno);
>>> +void dma_fence_init64(struct dma_fence *fence, const struct
>>> dma_fence_ops *ops,
>>> + spinlock_t *lock, u64 context, u64 seqno);
>>> +
>>> void dma_fence_release(struct kref *kref);
>>> void dma_fence_free(struct dma_fence *fence);
>>> void dma_fence_describe(struct dma_fence *fence, struct seq_file *seq);
>>> @@ -454,7 +450,7 @@ static inline bool __dma_fence_is_later(struct
>>> dma_fence *fence, u64 f1, u64 f2)
>>> * 32bit sequence numbers. Use a 64bit compare when the driver says to
>>> * do so.
>>> */
>>> - if (fence->ops->use_64bit_seqno)
>>> + if (test_bit(DMA_FENCE_FLAG_SEQNO64_BIT, &fence->flags))
>>> return f1 > f2;
>>> return (int)(lower_32_bits(f1) - lower_32_bits(f2)) > 0;
>>
>
