On Tue, Jul 13, 2021 at 8:40 AM Christian König
<christian.koenig@xxxxxxx> wrote:
>
> Am 12.07.21 um 19:53 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().
> >
> > Also improve the kerneldoc for this.
> >
> > v4:
> > - Fix the drm_sched_job_cleanup logic, I inverted the booleans, as
> > usual (Melissa)
> >
> > - Christian pointed out that drm_sched_entity_select_rq() also needs
> > to be moved into drm_sched_job_arm, which made me realize that the
> > job->id definitely needs to be moved too.
>
> As far as I can see you still have drm_sched_entity_select_rq() in
> drm_sched_job_init()?
Yeah it's again in there, but everything else which changes entity->rq
state isn't in there anymore, but in job_arm(). I also checked the
cleanup code, and we only update entity state in there, not job state,
so there's no additional complications for cleanup.
Of course this is quite a bit earlier, than if we do it in job_arm(),
but also not fundamentally a new race window. Just a bigger one, so
assuming the current code is correct, should be all fine. But also,
very possible I missed something else again :-)
-Daniel
> Christian.
>
> >
> > Shuffle things to fit between job_init and job_arm.
> >
> > v5:
> > Reshuffle the split between init/arm once more, amdgpu abuses
> > drm_sched.ready to signal gpu reset failures. Also document this
> > somewhat. (Christian)
> >
> > Cc: Melissa Wen <melissa.srw@xxxxxxxxx>
> > Acked-by: Steven Price <steven.price@xxxxxxx> (v2)
> > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> > Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> > Cc: Russell King <linux+etnaviv@xxxxxxxxxxxxxxx>
> > Cc: Christian Gmeiner <christian.gmeiner@xxxxxxxxx>
> > Cc: Qiang Yu <yuq825@xxxxxxxxx>
> > Cc: Rob Herring <robh@xxxxxxxxxx>
> > Cc: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> > Cc: Steven Price <steven.price@xxxxxxx>
> > Cc: Alyssa Rosenzweig <alyssa.rosenzweig@xxxxxxxxxxxxx>
> > Cc: David Airlie <airlied@xxxxxxxx>
> > Cc: Daniel Vetter <daniel@xxxxxxxx>
> > Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> > Cc: "Christian König" <christian.koenig@xxxxxxx>
> > Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> > Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > Cc: Adam Borowski <kilobyte@xxxxxxxxxx>
> > Cc: Nick Terrell <terrelln@xxxxxx>
> > Cc: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> > Cc: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
> > Cc: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
> > Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> > Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> > Cc: Dave Airlie <airlied@xxxxxxxxxx>
> > Cc: Nirmoy Das <nirmoy.das@xxxxxxx>
> > Cc: Deepak R Varma <mh12gx2825@xxxxxxxxx>
> > Cc: Lee Jones <lee.jones@xxxxxxxxxx>
> > Cc: Kevin Wang <kevin1.wang@xxxxxxx>
> > Cc: Chen Li <chenli@xxxxxxxxxxxxx>
> > Cc: Luben Tuikov <luben.tuikov@xxxxxxx>
> > Cc: "Marek Olšák" <marek.olsak@xxxxxxx>
> > Cc: Dennis Li <Dennis.Li@xxxxxxx>
> > Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> > Cc: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
> > Cc: Sonny Jiang <sonny.jiang@xxxxxxx>
> > Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> > Cc: Tian Tao <tiantao6@xxxxxxxxxxxxx>
> > Cc: etnaviv@xxxxxxxxxxxxxxxxxxxxx
> > Cc: lima@xxxxxxxxxxxxxxxxxxxxx
> > Cc: linux-media@xxxxxxxxxxxxxxx
> > Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx
> > Cc: Emma Anholt <emma@xxxxxxxxxx>
> > ---
> > 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 | 19 ++++---
> > drivers/gpu/drm/scheduler/sched_main.c | 69 ++++++++++++++++++++----
> > drivers/gpu/drm/v3d/v3d_gem.c | 2 +
> > include/drm/gpu_scheduler.h | 7 ++-
> > 10 files changed, 91 insertions(+), 22 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..bcea035cf4c6 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);
> > @@ -152,27 +152,32 @@ 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)
> > return NULL;
> >
> > fence->owner = owner;
> > - 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;
> > +
> > + 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);
> > 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..454cb6164bdc 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
> > @@ -577,27 +578,28 @@ 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.
> > + *
> > + * WARNING: amdgpu abuses &drm_sched.ready to signal when the hardware
> > + * has died, which can mean that there's no valid runqueue for a @entity.
> > + * This function returns -ENOENT in this case (which probably should be -EIO as
> > + * a more meanigful return value).
> > + *
> > * Returns 0 for success, negative error code otherwise.
> > */
> > int drm_sched_job_init(struct drm_sched_job *job,
> > struct drm_sched_entity *entity,
> > void *owner)
> > {
> > - struct drm_gpu_scheduler *sched;
> > -
> > drm_sched_entity_select_rq(entity);
> > if (!entity->rq)
> > return -ENOENT;
> >
> > - sched = entity->rq->sched;
> > -
> > - 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);
> >
> > INIT_LIST_HEAD(&job->list);
> >
> > @@ -606,13 +608,58 @@ 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)
> > +{
> > + struct drm_gpu_scheduler *sched;
> > + struct drm_sched_entity *entity = job->entity;
> > +
> > + BUG_ON(!entity);
> > +
> > + sched = entity->rq->sched;
> > +
> > + job->sched = sched;
> > + job->s_priority = entity->rq - sched->sched_rq;
> > + job->id = atomic64_inc_return(&sched->job_id_count);
> > +
> > + 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
http://blog.ffwll.ch
