Re: [PATCH v5 01/20] drm/sched: Split drm_sched_job_init

["Christian König" <christian.koenig@amd.com>]

Am 05.08.21 um 16:07 schrieb Daniel Vetter:
> On Thu, Aug 5, 2021 at 3:44 PM Christian König <christian.koenig@amd.com> wrote:
>> Am 05.08.21 um 12:46 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.
>>>
>>>     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)
>>>
>>> v6:
>>> Rebase on top of the msm drm/sched support. Note that the
>>> drm_sched_job_init() call is completely misplaced, and hence also the
>>> split-out drm_sched_entity_push_job(). I've put in a FIXME which the next
>>> patch will address.
>>>
>>> Acked-by: Melissa Wen <mwen@igalia.com>
>>> Cc: Melissa Wen <melissa.srw@gmail.com>
>>> Acked-by: Emma Anholt <emma@anholt.net>
>>> Acked-by: Steven Price <steven.price@arm.com> (v2)
>>> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> (v5)
>>> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
>> At least the amdgpu parts look ok of hand, but I can't judge the rest I
>> think.
> The thing that really scares me here and that I got wrong a few times
> is the cleanup for drm_sched_job at the various points. Can you give
> those parts in drm/scheduler/ a full review pls, just to make sure? I
> can note that in the tag ofc, just like a bit more confidence here
> that it's not busted :-)

I can take another look, but I won't have time for that in the next two 
weeks - vacation and kid starting school.

Christian.

>
>> So only Acked-by: Christian König <christian.koenig@amd.com>
> Thanks, Daniel
>
>>> Cc: Lucas Stach <l.stach@pengutronix.de>
>>> Cc: Russell King <linux+etnaviv@armlinux.org.uk>
>>> Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
>>> Cc: Qiang Yu <yuq825@gmail.com>
>>> Cc: Rob Herring <robh@kernel.org>
>>> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
>>> Cc: Steven Price <steven.price@arm.com>
>>> Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
>>> Cc: David Airlie <airlied@linux.ie>
>>> Cc: Daniel Vetter <daniel@ffwll.ch>
>>> Cc: Sumit Semwal <sumit.semwal@linaro.org>
>>> Cc: "Christian König" <christian.koenig@amd.com>
>>> Cc: Masahiro Yamada <masahiroy@kernel.org>
>>> Cc: Kees Cook <keescook@chromium.org>
>>> Cc: Adam Borowski <kilobyte@angband.pl>
>>> Cc: Nick Terrell <terrelln@fb.com>
>>> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
>>> Cc: Paul Menzel <pmenzel@molgen.mpg.de>
>>> Cc: Sami Tolvanen <samitolvanen@google.com>
>>> Cc: Viresh Kumar <viresh.kumar@linaro.org>
>>> Cc: Alex Deucher <alexander.deucher@amd.com>
>>> Cc: Dave Airlie <airlied@redhat.com>
>>> Cc: Nirmoy Das <nirmoy.das@amd.com>
>>> Cc: Deepak R Varma <mh12gx2825@gmail.com>
>>> Cc: Lee Jones <lee.jones@linaro.org>
>>> Cc: Kevin Wang <kevin1.wang@amd.com>
>>> Cc: Chen Li <chenli@uniontech.com>
>>> Cc: Luben Tuikov <luben.tuikov@amd.com>
>>> Cc: "Marek Olšák" <marek.olsak@amd.com>
>>> Cc: Dennis Li <Dennis.Li@amd.com>
>>> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>>> Cc: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>>> Cc: Sonny Jiang <sonny.jiang@amd.com>
>>> Cc: Boris Brezillon <boris.brezillon@collabora.com>
>>> Cc: Tian Tao <tiantao6@hisilicon.com>
>>> Cc: etnaviv@lists.freedesktop.org
>>> Cc: lima@lists.freedesktop.org
>>> Cc: linux-media@vger.kernel.org
>>> Cc: linaro-mm-sig@lists.linaro.org
>>> Cc: Emma Anholt <emma@anholt.net>
>>> Cc: Rob Clark <robdclark@gmail.com>
>>> Cc: Sean Paul <sean@poorly.run>
>>> Cc: linux-arm-msm@vger.kernel.org
>>> Cc: freedreno@lists.freedesktop.org
>>> ---
>>>    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/msm/msm_gem_submit.c     |  3 ++
>>>    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 ++-
>>>    11 files changed, 94 insertions(+), 22 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>> index 139cd3bf1ad6..32e80bc6af22 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/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
>>> index fdc5367aecaa..6d6c44f0e1f3 100644
>>> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
>>> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
>>> @@ -52,6 +52,9 @@ static struct msm_gem_submit *submit_create(struct drm_device *dev,
>>>                return ERR_PTR(ret);
>>>        }
>>>
>>> +     /* FIXME: this is way too early */
>>> +     drm_sched_job_arm(&job->base);
>>> +
>>>        xa_init_flags(&submit->deps, XA_FLAGS_ALLOC);
>>>
>>>        kref_init(&submit->ref);
>>> 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 5689da118197..2e808097b4d1 100644
>>> --- a/drivers/gpu/drm/v3d/v3d_gem.c
>>> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
>>> @@ -480,6 +480,8 @@ 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);
>>>
>