[PATCH v2 01/11] drm/sched: Split drm_sched_job_init
Christian König
christian.koenig at amd.com
Thu Jul 8 10:54:08 UTC 2021
Am 08.07.21 um 12:02 schrieb Daniel Vetter:
> On Thu, Jul 08, 2021 at 09:53:00AM +0200, Christian König wrote:
>> Am 08.07.21 um 09:19 schrieb Daniel Vetter:
>>> On Thu, Jul 8, 2021 at 9:09 AM Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
>>>> On Thu, Jul 8, 2021 at 8:56 AM Christian König <christian.koenig at amd.com> wrote:
>>>>> Am 07.07.21 um 18:32 schrieb Daniel Vetter:
>>>>>> On Wed, Jul 7, 2021 at 2:58 PM Christian König <christian.koenig at amd.com> wrote:
>>>>>>> Am 07.07.21 um 14:13 schrieb Daniel Vetter:
>>>>>>>> On Wed, Jul 7, 2021 at 1:57 PM Christian König <christian.koenig at amd.com> wrote:
>>>>>>>>> Am 07.07.21 um 13:14 schrieb Daniel Vetter:
>>>>>>>>>> On Wed, Jul 7, 2021 at 11:30 AM Christian König
>>>>>>>>>> <christian.koenig at amd.com> wrote:
>>>>>>>>>>> Am 02.07.21 um 23:38 schrieb Daniel Vetter:
>>>>>>>>>>>> This is a very confusingly named function, because not just does it
>>>>>>>>>>>> init an object, it arms it and provides a point of no return for
>>>>>>>>>>>> pushing a job into the scheduler. It would be nice if that's a bit
>>>>>>>>>>>> clearer in the interface.
>>>>>>>>>>>>
>>>>>>>>>>>> But the real reason is that I want to push the dependency tracking
>>>>>>>>>>>> helpers into the scheduler code, and that means drm_sched_job_init
>>>>>>>>>>>> must be called a lot earlier, without arming the job.
>>>>>>>>>>>>
>>>>>>>>>>>> v2:
>>>>>>>>>>>> - don't change .gitignore (Steven)
>>>>>>>>>>>> - don't forget v3d (Emma)
>>>>>>>>>>>>
>>>>>>>>>>>> v3: Emma noticed that I leak the memory allocated in
>>>>>>>>>>>> drm_sched_job_init if we bail out before the point of no return in
>>>>>>>>>>>> subsequent driver patches. To be able to fix this change
>>>>>>>>>>>> drm_sched_job_cleanup() so it can handle being called both before and
>>>>>>>>>>>> after drm_sched_job_arm().
>>>>>>>>>>> Thinking more about this, I'm not sure if this really works.
>>>>>>>>>>>
>>>>>>>>>>> See drm_sched_job_init() was also calling drm_sched_entity_select_rq()
>>>>>>>>>>> to update the entity->rq association.
>>>>>>>>>>>
>>>>>>>>>>> And that can only be done later on when we arm the fence as well.
>>>>>>>>>> Hm yeah, but that's a bug in the existing code I think: We already
>>>>>>>>>> fail to clean up if we fail to allocate the fences. So I think the
>>>>>>>>>> right thing to do here is to split the checks into job_init, and do
>>>>>>>>>> the actual arming/rq selection in job_arm? I'm not entirely sure
>>>>>>>>>> what's all going on there, the first check looks a bit like trying to
>>>>>>>>>> schedule before the entity is set up, which is a driver bug and should
>>>>>>>>>> have a WARN_ON?
>>>>>>>>> No you misunderstood me, the problem is something else.
>>>>>>>>>
>>>>>>>>> You asked previously why the call to drm_sched_job_init() was so late in
>>>>>>>>> the CS.
>>>>>>>>>
>>>>>>>>> The reason for this was not alone the scheduler fence init, but also the
>>>>>>>>> call to drm_sched_entity_select_rq().
>>>>>>>> Ah ok, I think I can fix that. Needs a prep patch to first make
>>>>>>>> drm_sched_entity_select infallible, then should be easy to do.
>>>>>>>>
>>>>>>>>>> The 2nd check around last_scheduled I have honeslty no idea what it's
>>>>>>>>>> even trying to do.
>>>>>>>>> You mean that here?
>>>>>>>>>
>>>>>>>>> fence = READ_ONCE(entity->last_scheduled);
>>>>>>>>> if (fence && !dma_fence_is_signaled(fence))
>>>>>>>>> return;
>>>>>>>>>
>>>>>>>>> This makes sure that load balancing is not moving the entity to a
>>>>>>>>> different scheduler while there are still jobs running from this entity
>>>>>>>>> on the hardware,
>>>>>>>> Yeah after a nap that idea crossed my mind too. But now I have locking
>>>>>>>> questions, afaiui the scheduler thread updates this, without taking
>>>>>>>> any locks - entity dequeuing is lockless. And here we read the fence
>>>>>>>> and then seem to yolo check whether it's signalled? What's preventing
>>>>>>>> a use-after-free here? There's no rcu or anything going on here at
>>>>>>>> all, and it's outside of the spinlock section, which starts a bit
>>>>>>>> further down.
>>>>>>> The last_scheduled fence of an entity can only change when there are
>>>>>>> jobs on the entities queued, and we have just ruled that out in the
>>>>>>> check before.
>>>>>> There aren't any barriers, so the cpu could easily run the two checks
>>>>>> the other way round. I'll ponder this and figure out where exactly we
>>>>>> need docs for the constraint and/or barriers to make this work as
>>>>>> intended. As-is I'm not seeing how it does ...
>>>>> spsc_queue_count() provides the necessary barrier with the atomic_read().
>>>> atomic_t is fully unordered, except when it's a read-modify-write
>>> Wasn't awake yet, I think the rule is read-modify-write and return
>>> previous value gives you full barrier. So stuff like cmpxchg, but also
>>> a few others. See atomic_t.txt under ODERING heading (yes that
>>> maintainer refuses to accept .rst so I can't just link you to the
>>> right section, it's silly). get/set and even RMW atomic ops that don't
>>> return anything are all fully unordered.
>> As far as I know that not completely correct. The rules around atomics i
>> once learned are:
>>
>> 1. Everything which modifies something is a write barrier.
>> 2. Everything which returns something is a read barrier.
>>
>> And I know a whole bunch of use cases where this is relied upon in the core
>> kernel, so I'm pretty sure that's correct.
> That's against what the doc says, and also it would mean stuff like
> atomic_read_acquire or smp_mb__after/before_atomic is completely pointless.
>
> On x86 you're right, anywhere else where there's no total store ordering I
> you're wrong.
Good to know. I always thought that atomic_read_acquire() was just for
documentation purpose.
> If there's code that relies on this it needs to be fixed and properly
> documented. I did go through the squeue code a bit, and might be better to
> just replace this with a core data structure.
Well the spsc was especially crafted for this use case and performed
quite a bit better then a double linked list.
Or what core data structure do you have in mind?
Christian.
> -Daniel
>
>> In this case the write barrier is the atomic_dec() in spsc_queue_pop() and
>> the read barrier is the aromic_read() in spsc_queue_count().
>>
>> The READ_ONCE() is actually not even necessary as far as I can see.
>>
>> Christian.
>>
>>> -Daniel
>>>
>>>
>>>> atomic op, then it's a full barrier. So yeah you need more here. But
>>>> also since you only need a read barrier on one side, and a write
>>>> barrier on the other, you don't actually need a cpu barriers on x86.
>>>> And READ_ONCE gives you the compiler barrier on one side at least, I
>>>> haven't found it on the writer side yet.
>>>>
>>>>> But yes a comment would be really nice here. I had to think for a while
>>>>> why we don't need this as well.
>>>> I'm typing a patch, which after a night's sleep I realized has the
>>>> wrong barriers. And now I'm also typing some doc improvements for
>>>> drm_sched_entity and related functions.
>>>>
>>>>> Christian.
>>>>>
>>>>>> -Daniel
>>>>>>
>>>>>>> Christian.
>>>>>>>
>>>>>>>
>>>>>>>> -Daniel
>>>>>>>>
>>>>>>>>> Regards
>>>>>>>>> Christian.
>>>>>>>>>
>>>>>>>>>> -Daniel
>>>>>>>>>>
>>>>>>>>>>> Christian.
>>>>>>>>>>>
>>>>>>>>>>>> Also improve the kerneldoc for this.
>>>>>>>>>>>>
>>>>>>>>>>>> Acked-by: Steven Price <steven.price at arm.com> (v2)
>>>>>>>>>>>> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
>>>>>>>>>>>> Cc: Lucas Stach <l.stach at pengutronix.de>
>>>>>>>>>>>> Cc: Russell King <linux+etnaviv at armlinux.org.uk>
>>>>>>>>>>>> Cc: Christian Gmeiner <christian.gmeiner at gmail.com>
>>>>>>>>>>>> Cc: Qiang Yu <yuq825 at gmail.com>
>>>>>>>>>>>> Cc: Rob Herring <robh at kernel.org>
>>>>>>>>>>>> Cc: Tomeu Vizoso <tomeu.vizoso at collabora.com>
>>>>>>>>>>>> Cc: Steven Price <steven.price at arm.com>
>>>>>>>>>>>> Cc: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
>>>>>>>>>>>> Cc: David Airlie <airlied at linux.ie>
>>>>>>>>>>>> Cc: Daniel Vetter <daniel at ffwll.ch>
>>>>>>>>>>>> Cc: Sumit Semwal <sumit.semwal at linaro.org>
>>>>>>>>>>>> Cc: "Christian König" <christian.koenig at amd.com>
>>>>>>>>>>>> Cc: Masahiro Yamada <masahiroy at kernel.org>
>>>>>>>>>>>> Cc: Kees Cook <keescook at chromium.org>
>>>>>>>>>>>> Cc: Adam Borowski <kilobyte at angband.pl>
>>>>>>>>>>>> Cc: Nick Terrell <terrelln at fb.com>
>>>>>>>>>>>> Cc: Mauro Carvalho Chehab <mchehab+huawei at kernel.org>
>>>>>>>>>>>> Cc: Paul Menzel <pmenzel at molgen.mpg.de>
>>>>>>>>>>>> Cc: Sami Tolvanen <samitolvanen at google.com>
>>>>>>>>>>>> Cc: Viresh Kumar <viresh.kumar at linaro.org>
>>>>>>>>>>>> Cc: Alex Deucher <alexander.deucher at amd.com>
>>>>>>>>>>>> Cc: Dave Airlie <airlied at redhat.com>
>>>>>>>>>>>> Cc: Nirmoy Das <nirmoy.das at amd.com>
>>>>>>>>>>>> Cc: Deepak R Varma <mh12gx2825 at gmail.com>
>>>>>>>>>>>> Cc: Lee Jones <lee.jones at linaro.org>
>>>>>>>>>>>> Cc: Kevin Wang <kevin1.wang at amd.com>
>>>>>>>>>>>> Cc: Chen Li <chenli at uniontech.com>
>>>>>>>>>>>> Cc: Luben Tuikov <luben.tuikov at amd.com>
>>>>>>>>>>>> Cc: "Marek Olšák" <marek.olsak at amd.com>
>>>>>>>>>>>> Cc: Dennis Li <Dennis.Li at amd.com>
>>>>>>>>>>>> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>>>>>>>>>>>> Cc: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
>>>>>>>>>>>> Cc: Sonny Jiang <sonny.jiang at amd.com>
>>>>>>>>>>>> Cc: Boris Brezillon <boris.brezillon at collabora.com>
>>>>>>>>>>>> Cc: Tian Tao <tiantao6 at hisilicon.com>
>>>>>>>>>>>> Cc: Jack Zhang <Jack.Zhang1 at amd.com>
>>>>>>>>>>>> Cc: etnaviv at lists.freedesktop.org
>>>>>>>>>>>> Cc: lima at lists.freedesktop.org
>>>>>>>>>>>> Cc: linux-media at vger.kernel.org
>>>>>>>>>>>> Cc: linaro-mm-sig at lists.linaro.org
>>>>>>>>>>>> Cc: Emma Anholt <emma at anholt.net>
>>>>>>>>>>>> ---
>>>>>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 2 ++
>>>>>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 2 ++
>>>>>>>>>>>> drivers/gpu/drm/etnaviv/etnaviv_sched.c | 2 ++
>>>>>>>>>>>> drivers/gpu/drm/lima/lima_sched.c | 2 ++
>>>>>>>>>>>> drivers/gpu/drm/panfrost/panfrost_job.c | 2 ++
>>>>>>>>>>>> drivers/gpu/drm/scheduler/sched_entity.c | 6 ++--
>>>>>>>>>>>> drivers/gpu/drm/scheduler/sched_fence.c | 17 +++++----
>>>>>>>>>>>> drivers/gpu/drm/scheduler/sched_main.c | 46 +++++++++++++++++++++---
>>>>>>>>>>>> drivers/gpu/drm/v3d/v3d_gem.c | 2 ++
>>>>>>>>>>>> include/drm/gpu_scheduler.h | 7 +++-
>>>>>>>>>>>> 10 files changed, 74 insertions(+), 14 deletions(-)
>>>>>>>>>>>>
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>>>>>>>>>>> index c5386d13eb4a..a4ec092af9a7 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>>>>>>>>>>> @@ -1226,6 +1226,8 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
>>>>>>>>>>>> if (r)
>>>>>>>>>>>> goto error_unlock;
>>>>>>>>>>>>
>>>>>>>>>>>> + drm_sched_job_arm(&job->base);
>>>>>>>>>>>> +
>>>>>>>>>>>> /* No memory allocation is allowed while holding the notifier lock.
>>>>>>>>>>>> * The lock is held until amdgpu_cs_submit is finished and fence is
>>>>>>>>>>>> * added to BOs.
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>>>>>>>>> index d33e6d97cc89..5ddb955d2315 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>>>>>>>>> @@ -170,6 +170,8 @@ int amdgpu_job_submit(struct amdgpu_job *job, struct drm_sched_entity *entity,
>>>>>>>>>>>> if (r)
>>>>>>>>>>>> return r;
>>>>>>>>>>>>
>>>>>>>>>>>> + drm_sched_job_arm(&job->base);
>>>>>>>>>>>> +
>>>>>>>>>>>> *f = dma_fence_get(&job->base.s_fence->finished);
>>>>>>>>>>>> amdgpu_job_free_resources(job);
>>>>>>>>>>>> drm_sched_entity_push_job(&job->base, entity);
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_sched.c b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
>>>>>>>>>>>> index feb6da1b6ceb..05f412204118 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/etnaviv/etnaviv_sched.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
>>>>>>>>>>>> @@ -163,6 +163,8 @@ int etnaviv_sched_push_job(struct drm_sched_entity *sched_entity,
>>>>>>>>>>>> if (ret)
>>>>>>>>>>>> goto out_unlock;
>>>>>>>>>>>>
>>>>>>>>>>>> + drm_sched_job_arm(&submit->sched_job);
>>>>>>>>>>>> +
>>>>>>>>>>>> submit->out_fence = dma_fence_get(&submit->sched_job.s_fence->finished);
>>>>>>>>>>>> submit->out_fence_id = idr_alloc_cyclic(&submit->gpu->fence_idr,
>>>>>>>>>>>> submit->out_fence, 0,
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/lima/lima_sched.c b/drivers/gpu/drm/lima/lima_sched.c
>>>>>>>>>>>> index dba8329937a3..38f755580507 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/lima/lima_sched.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/lima/lima_sched.c
>>>>>>>>>>>> @@ -129,6 +129,8 @@ int lima_sched_task_init(struct lima_sched_task *task,
>>>>>>>>>>>> return err;
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> + drm_sched_job_arm(&task->base);
>>>>>>>>>>>> +
>>>>>>>>>>>> task->num_bos = num_bos;
>>>>>>>>>>>> task->vm = lima_vm_get(vm);
>>>>>>>>>>>>
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
>>>>>>>>>>>> index 71a72fb50e6b..2992dc85325f 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
>>>>>>>>>>>> @@ -288,6 +288,8 @@ int panfrost_job_push(struct panfrost_job *job)
>>>>>>>>>>>> goto unlock;
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> + drm_sched_job_arm(&job->base);
>>>>>>>>>>>> +
>>>>>>>>>>>> job->render_done_fence = dma_fence_get(&job->base.s_fence->finished);
>>>>>>>>>>>>
>>>>>>>>>>>> ret = panfrost_acquire_object_fences(job->bos, job->bo_count,
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
>>>>>>>>>>>> index 79554aa4dbb1..f7347c284886 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/scheduler/sched_entity.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
>>>>>>>>>>>> @@ -485,9 +485,9 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
>>>>>>>>>>>> * @sched_job: job to submit
>>>>>>>>>>>> * @entity: scheduler entity
>>>>>>>>>>>> *
>>>>>>>>>>>> - * Note: To guarantee that the order of insertion to queue matches
>>>>>>>>>>>> - * the job's fence sequence number this function should be
>>>>>>>>>>>> - * called with drm_sched_job_init under common lock.
>>>>>>>>>>>> + * Note: To guarantee that the order of insertion to queue matches the job's
>>>>>>>>>>>> + * fence sequence number this function should be called with drm_sched_job_arm()
>>>>>>>>>>>> + * under common lock.
>>>>>>>>>>>> *
>>>>>>>>>>>> * Returns 0 for success, negative error code otherwise.
>>>>>>>>>>>> */
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c
>>>>>>>>>>>> index 69de2c76731f..c451ee9a30d7 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/scheduler/sched_fence.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/scheduler/sched_fence.c
>>>>>>>>>>>> @@ -90,7 +90,7 @@ static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
>>>>>>>>>>>> *
>>>>>>>>>>>> * Free up the fence memory after the RCU grace period.
>>>>>>>>>>>> */
>>>>>>>>>>>> -static void drm_sched_fence_free(struct rcu_head *rcu)
>>>>>>>>>>>> +void drm_sched_fence_free(struct rcu_head *rcu)
>>>>>>>>>>>> {
>>>>>>>>>>>> struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
>>>>>>>>>>>> struct drm_sched_fence *fence = to_drm_sched_fence(f);
>>>>>>>>>>>> @@ -152,11 +152,10 @@ struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
>>>>>>>>>>>> }
>>>>>>>>>>>> EXPORT_SYMBOL(to_drm_sched_fence);
>>>>>>>>>>>>
>>>>>>>>>>>> -struct drm_sched_fence *drm_sched_fence_create(struct drm_sched_entity *entity,
>>>>>>>>>>>> - void *owner)
>>>>>>>>>>>> +struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
>>>>>>>>>>>> + void *owner)
>>>>>>>>>>>> {
>>>>>>>>>>>> struct drm_sched_fence *fence = NULL;
>>>>>>>>>>>> - unsigned seq;
>>>>>>>>>>>>
>>>>>>>>>>>> fence = kmem_cache_zalloc(sched_fence_slab, GFP_KERNEL);
>>>>>>>>>>>> if (fence == NULL)
>>>>>>>>>>>> @@ -166,13 +165,19 @@ struct drm_sched_fence *drm_sched_fence_create(struct drm_sched_entity *entity,
>>>>>>>>>>>> fence->sched = entity->rq->sched;
>>>>>>>>>>>> spin_lock_init(&fence->lock);
>>>>>>>>>>>>
>>>>>>>>>>>> + return fence;
>>>>>>>>>>>> +}
>>>>>>>>>>>> +
>>>>>>>>>>>> +void drm_sched_fence_init(struct drm_sched_fence *fence,
>>>>>>>>>>>> + struct drm_sched_entity *entity)
>>>>>>>>>>>> +{
>>>>>>>>>>>> + unsigned seq;
>>>>>>>>>>>> +
>>>>>>>>>>>> seq = atomic_inc_return(&entity->fence_seq);
>>>>>>>>>>>> dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
>>>>>>>>>>>> &fence->lock, entity->fence_context, seq);
>>>>>>>>>>>> dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
>>>>>>>>>>>> &fence->lock, entity->fence_context + 1, seq);
>>>>>>>>>>>> -
>>>>>>>>>>>> - return fence;
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> module_init(drm_sched_fence_slab_init);
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
>>>>>>>>>>>> index 33c414d55fab..5e84e1500c32 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>>>>>>>>>>>> @@ -48,9 +48,11 @@
>>>>>>>>>>>> #include <linux/wait.h>
>>>>>>>>>>>> #include <linux/sched.h>
>>>>>>>>>>>> #include <linux/completion.h>
>>>>>>>>>>>> +#include <linux/dma-resv.h>
>>>>>>>>>>>> #include <uapi/linux/sched/types.h>
>>>>>>>>>>>>
>>>>>>>>>>>> #include <drm/drm_print.h>
>>>>>>>>>>>> +#include <drm/drm_gem.h>
>>>>>>>>>>>> #include <drm/gpu_scheduler.h>
>>>>>>>>>>>> #include <drm/spsc_queue.h>
>>>>>>>>>>>>
>>>>>>>>>>>> @@ -569,7 +571,6 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs_ext);
>>>>>>>>>>>>
>>>>>>>>>>>> /**
>>>>>>>>>>>> * drm_sched_job_init - init a scheduler job
>>>>>>>>>>>> - *
>>>>>>>>>>>> * @job: scheduler job to init
>>>>>>>>>>>> * @entity: scheduler entity to use
>>>>>>>>>>>> * @owner: job owner for debugging
>>>>>>>>>>>> @@ -577,6 +578,9 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs_ext);
>>>>>>>>>>>> * Refer to drm_sched_entity_push_job() documentation
>>>>>>>>>>>> * for locking considerations.
>>>>>>>>>>>> *
>>>>>>>>>>>> + * Drivers must make sure drm_sched_job_cleanup() if this function returns
>>>>>>>>>>>> + * successfully, even when @job is aborted before drm_sched_job_arm() is called.
>>>>>>>>>>>> + *
>>>>>>>>>>>> * Returns 0 for success, negative error code otherwise.
>>>>>>>>>>>> */
>>>>>>>>>>>> int drm_sched_job_init(struct drm_sched_job *job,
>>>>>>>>>>>> @@ -594,7 +598,7 @@ int drm_sched_job_init(struct drm_sched_job *job,
>>>>>>>>>>>> job->sched = sched;
>>>>>>>>>>>> job->entity = entity;
>>>>>>>>>>>> job->s_priority = entity->rq - sched->sched_rq;
>>>>>>>>>>>> - job->s_fence = drm_sched_fence_create(entity, owner);
>>>>>>>>>>>> + job->s_fence = drm_sched_fence_alloc(entity, owner);
>>>>>>>>>>>> if (!job->s_fence)
>>>>>>>>>>>> return -ENOMEM;
>>>>>>>>>>>> job->id = atomic64_inc_return(&sched->job_id_count);
>>>>>>>>>>>> @@ -606,13 +610,47 @@ int drm_sched_job_init(struct drm_sched_job *job,
>>>>>>>>>>>> EXPORT_SYMBOL(drm_sched_job_init);
>>>>>>>>>>>>
>>>>>>>>>>>> /**
>>>>>>>>>>>> - * drm_sched_job_cleanup - clean up scheduler job resources
>>>>>>>>>>>> + * drm_sched_job_arm - arm a scheduler job for execution
>>>>>>>>>>>> + * @job: scheduler job to arm
>>>>>>>>>>>> + *
>>>>>>>>>>>> + * This arms a scheduler job for execution. Specifically it initializes the
>>>>>>>>>>>> + * &drm_sched_job.s_fence of @job, so that it can be attached to struct dma_resv
>>>>>>>>>>>> + * or other places that need to track the completion of this job.
>>>>>>>>>>>> + *
>>>>>>>>>>>> + * Refer to drm_sched_entity_push_job() documentation for locking
>>>>>>>>>>>> + * considerations.
>>>>>>>>>>>> *
>>>>>>>>>>>> + * This can only be called if drm_sched_job_init() succeeded.
>>>>>>>>>>>> + */
>>>>>>>>>>>> +void drm_sched_job_arm(struct drm_sched_job *job)
>>>>>>>>>>>> +{
>>>>>>>>>>>> + drm_sched_fence_init(job->s_fence, job->entity);
>>>>>>>>>>>> +}
>>>>>>>>>>>> +EXPORT_SYMBOL(drm_sched_job_arm);
>>>>>>>>>>>> +
>>>>>>>>>>>> +/**
>>>>>>>>>>>> + * drm_sched_job_cleanup - clean up scheduler job resources
>>>>>>>>>>>> * @job: scheduler job to clean up
>>>>>>>>>>>> + *
>>>>>>>>>>>> + * Cleans up the resources allocated with drm_sched_job_init().
>>>>>>>>>>>> + *
>>>>>>>>>>>> + * Drivers should call this from their error unwind code if @job is aborted
>>>>>>>>>>>> + * before drm_sched_job_arm() is called.
>>>>>>>>>>>> + *
>>>>>>>>>>>> + * After that point of no return @job is committed to be executed by the
>>>>>>>>>>>> + * scheduler, and this function should be called from the
>>>>>>>>>>>> + * &drm_sched_backend_ops.free_job callback.
>>>>>>>>>>>> */
>>>>>>>>>>>> void drm_sched_job_cleanup(struct drm_sched_job *job)
>>>>>>>>>>>> {
>>>>>>>>>>>> - dma_fence_put(&job->s_fence->finished);
>>>>>>>>>>>> + if (!kref_read(&job->s_fence->finished.refcount)) {
>>>>>>>>>>>> + /* drm_sched_job_arm() has been called */
>>>>>>>>>>>> + dma_fence_put(&job->s_fence->finished);
>>>>>>>>>>>> + } else {
>>>>>>>>>>>> + /* aborted job before committing to run it */
>>>>>>>>>>>> + drm_sched_fence_free(&job->s_fence->finished.rcu);
>>>>>>>>>>>> + }
>>>>>>>>>>>> +
>>>>>>>>>>>> job->s_fence = NULL;
>>>>>>>>>>>> }
>>>>>>>>>>>> EXPORT_SYMBOL(drm_sched_job_cleanup);
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
>>>>>>>>>>>> index 4eb354226972..5c3a99027ecd 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/v3d/v3d_gem.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
>>>>>>>>>>>> @@ -475,6 +475,8 @@ v3d_push_job(struct v3d_file_priv *v3d_priv,
>>>>>>>>>>>> if (ret)
>>>>>>>>>>>> return ret;
>>>>>>>>>>>>
>>>>>>>>>>>> + drm_sched_job_arm(&job->base);
>>>>>>>>>>>> +
>>>>>>>>>>>> job->done_fence = dma_fence_get(&job->base.s_fence->finished);
>>>>>>>>>>>>
>>>>>>>>>>>> /* put by scheduler job completion */
>>>>>>>>>>>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>>>>>>>>>>>> index 88ae7f331bb1..83afc3aa8e2f 100644
>>>>>>>>>>>> --- a/include/drm/gpu_scheduler.h
>>>>>>>>>>>> +++ b/include/drm/gpu_scheduler.h
>>>>>>>>>>>> @@ -348,6 +348,7 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched);
>>>>>>>>>>>> int drm_sched_job_init(struct drm_sched_job *job,
>>>>>>>>>>>> struct drm_sched_entity *entity,
>>>>>>>>>>>> void *owner);
>>>>>>>>>>>> +void drm_sched_job_arm(struct drm_sched_job *job);
>>>>>>>>>>>> void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
>>>>>>>>>>>> struct drm_gpu_scheduler **sched_list,
>>>>>>>>>>>> unsigned int num_sched_list);
>>>>>>>>>>>> @@ -387,8 +388,12 @@ void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
>>>>>>>>>>>> enum drm_sched_priority priority);
>>>>>>>>>>>> bool drm_sched_entity_is_ready(struct drm_sched_entity *entity);
>>>>>>>>>>>>
>>>>>>>>>>>> -struct drm_sched_fence *drm_sched_fence_create(
>>>>>>>>>>>> +struct drm_sched_fence *drm_sched_fence_alloc(
>>>>>>>>>>>> struct drm_sched_entity *s_entity, void *owner);
>>>>>>>>>>>> +void drm_sched_fence_init(struct drm_sched_fence *fence,
>>>>>>>>>>>> + struct drm_sched_entity *entity);
>>>>>>>>>>>> +void drm_sched_fence_free(struct rcu_head *rcu);
>>>>>>>>>>>> +
>>>>>>>>>>>> void drm_sched_fence_scheduled(struct drm_sched_fence *fence);
>>>>>>>>>>>> void drm_sched_fence_finished(struct drm_sched_fence *fence);
>>>>>>>>>>>>
>>>> --
>>>> Daniel Vetter
>>>> Software Engineer, Intel Corporation
>>>> https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fblog.ffwll.ch%2F&data=04%7C01%7Cchristian.koenig%40amd.com%7C7086790381b9415f60e708d941f78266%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637613353580226578%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=9GhYoGHD6TlcrW5dvT9Z%2BFukW%2F8%2BicK2t8180coEsJY%3D&reserved=0
>>>
>>> --
>>> Daniel Vetter
>>> Software Engineer, Intel Corporation
>>> https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fblog.ffwll.ch%2F&data=04%7C01%7Cchristian.koenig%40amd.com%7C7086790381b9415f60e708d941f78266%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637613353580236571%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Yt%2FirDjTmtDUjQS1xlYg4x5mz82cHkNyLPkNNpO31ro%3D&reserved=0
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