Yeah, completely correct explained.

I was unfortunately really busy today, but going to give that a look as soon as I have time.

Christian.

Am 11.12.18 um 17:01 schrieb Grodzovsky, Andrey:
A I understand you say that by the time the fence callback runs the job
might have already been released,

but how so if the job gets released from drm_sched_job_finish work
handler in the normal flow - so, after the HW

fence (s_fence->parent) cb is executed. Other 2 flows are error use
cases where amdgpu_job_free is called directly in which

cases I assume the job wasn't submitted to HW. Last flow I see is
drm_sched_entity_kill_jobs_cb and here I actually see a problem

with the code as it's today - drm_sched_fence_finished is called which
will trigger s_fence->finished callback to run which today

schedules drm_sched_job_finish which releases the job, but we don't even
wait for that and call free_job cb directly from

after that which seems wrong to me.

Andrey


On 12/10/2018 09:45 PM, Zhou, David(ChunMing) wrote:
I don't think adding cb to sched job would work as soon as their lifetime is 
different with fence.
Unless you make the sched job reference, otherwise we will get trouble sooner 
or later.

-David

-----Original Message-----
From: amd-gfx <amd-gfx-boun...@lists.freedesktop.org> On Behalf Of
Andrey Grodzovsky
Sent: Tuesday, December 11, 2018 5:44 AM
To: dri-devel@lists.freedesktop.org; amd-...@lists.freedesktop.org;
ckoenig.leichtzumer...@gmail.com; e...@anholt.net;
etna...@lists.freedesktop.org
Cc: Zhou, David(ChunMing) <david1.z...@amd.com>; Liu, Monk
<monk....@amd.com>; Grodzovsky, Andrey
<andrey.grodzov...@amd.com>
Subject: [PATCH v3 2/2] drm/sched: Rework HW fence processing.

Expedite job deletion from ring mirror list to the HW fence signal callback
instead from finish_work, together with waiting for all such fences to signal in
drm_sched_stop we garantee that already signaled job will not be processed
twice.
Remove the sched finish fence callback and just submit finish_work directly
from the HW fence callback.

v2: Fix comments.

v3: Attach  hw fence cb to sched_job

Suggested-by: Christian Koenig <christian.koe...@amd.com>
Signed-off-by: Andrey Grodzovsky <andrey.grodzov...@amd.com>
---
   drivers/gpu/drm/scheduler/sched_main.c | 58 ++++++++++++++++----------
--------
   include/drm/gpu_scheduler.h            |  6 ++--
   2 files changed, 30 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c
b/drivers/gpu/drm/scheduler/sched_main.c
index cdf95e2..f0c1f32 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -284,8 +284,6 @@ static void drm_sched_job_finish(struct work_struct
*work)
        cancel_delayed_work_sync(&sched->work_tdr);

        spin_lock_irqsave(&sched->job_list_lock, flags);
-       /* remove job from ring_mirror_list */
-       list_del_init(&s_job->node);
        /* queue TDR for next job */
        drm_sched_start_timeout(sched);
        spin_unlock_irqrestore(&sched->job_list_lock, flags); @@ -293,22
+291,11 @@ static void drm_sched_job_finish(struct work_struct *work)
        sched->ops->free_job(s_job);
   }

-static void drm_sched_job_finish_cb(struct dma_fence *f,
-                                   struct dma_fence_cb *cb)
-{
-       struct drm_sched_job *job = container_of(cb, struct drm_sched_job,
-                                                finish_cb);
-       schedule_work(&job->finish_work);
-}
-
   static void drm_sched_job_begin(struct drm_sched_job *s_job)  {
        struct drm_gpu_scheduler *sched = s_job->sched;
        unsigned long flags;

-       dma_fence_add_callback(&s_job->s_fence->finished, &s_job-
finish_cb,
-                              drm_sched_job_finish_cb);
-
        spin_lock_irqsave(&sched->job_list_lock, flags);
        list_add_tail(&s_job->node, &sched->ring_mirror_list);
        drm_sched_start_timeout(sched);
@@ -359,12 +346,11 @@ void drm_sched_stop(struct drm_gpu_scheduler
*sched, struct drm_sched_job *bad,
        list_for_each_entry_reverse(s_job, &sched->ring_mirror_list, node)
{
                if (s_job->s_fence->parent &&
                    dma_fence_remove_callback(s_job->s_fence->parent,
-                                             &s_job->s_fence->cb)) {
+                                             &s_job->cb)) {
                        dma_fence_put(s_job->s_fence->parent);
                        s_job->s_fence->parent = NULL;
                        atomic_dec(&sched->hw_rq_count);
-               }
-               else {
+               } else {
                        /* TODO Is it get/put neccessey here ? */
                        dma_fence_get(&s_job->s_fence->finished);
                        list_add(&s_job->finish_node, &wait_list); @@ -
417,31 +403,34 @@ EXPORT_SYMBOL(drm_sched_stop);  void
drm_sched_start(struct drm_gpu_scheduler *sched, bool unpark_only)  {
        struct drm_sched_job *s_job, *tmp;
-       unsigned long flags;
        int r;

        if (unpark_only)
                goto unpark;

-       spin_lock_irqsave(&sched->job_list_lock, flags);
+       /*
+        * Locking the list is not required here as the sched thread is parked
+        * so no new jobs are being pushed in to HW and in drm_sched_stop
we
+        * flushed all the jobs who were still in mirror list but who already
+        * signaled and removed them self from the list. Also concurrent
+        * GPU recovers can't run in parallel.
+        */
        list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list,
node) {
-               struct drm_sched_fence *s_fence = s_job->s_fence;
                struct dma_fence *fence = s_job->s_fence->parent;

                if (fence) {
-                       r = dma_fence_add_callback(fence, &s_fence->cb,
+                       r = dma_fence_add_callback(fence, &s_job->cb,
                                                   drm_sched_process_job);
                        if (r == -ENOENT)
-                               drm_sched_process_job(fence, &s_fence-
cb);
+                               drm_sched_process_job(fence, &s_job->cb);
                        else if (r)
                                DRM_ERROR("fence add callback failed
(%d)\n",
                                          r);
                } else
-                       drm_sched_process_job(NULL, &s_fence->cb);
+                       drm_sched_process_job(NULL, &s_job->cb);
        }

        drm_sched_start_timeout(sched);
-       spin_unlock_irqrestore(&sched->job_list_lock, flags);

   unpark:
        kthread_unpark(sched->thread);
@@ -590,18 +579,27 @@ drm_sched_select_entity(struct
drm_gpu_scheduler *sched)
    */
   static void drm_sched_process_job(struct dma_fence *f, struct
dma_fence_cb *cb)  {
-       struct drm_sched_fence *s_fence =
-               container_of(cb, struct drm_sched_fence, cb);
+       struct drm_sched_job *s_job = container_of(cb, struct
drm_sched_job, cb);
+       struct drm_sched_fence *s_fence = s_job->s_fence;
        struct drm_gpu_scheduler *sched = s_fence->sched;
+       unsigned long flags;
+
+       cancel_delayed_work(&sched->work_tdr);

-       dma_fence_get(&s_fence->finished);
        atomic_dec(&sched->hw_rq_count);
        atomic_dec(&sched->num_jobs);
+
+       spin_lock_irqsave(&sched->job_list_lock, flags);
+       /* remove job from ring_mirror_list */
+       list_del_init(&s_job->node);
+       spin_unlock_irqrestore(&sched->job_list_lock, flags);
+
        drm_sched_fence_finished(s_fence);

        trace_drm_sched_process_job(s_fence);
-       dma_fence_put(&s_fence->finished);
        wake_up_interruptible(&sched->wake_up_worker);
+
+       schedule_work(&s_job->finish_work);
   }

   /**
@@ -664,16 +662,16 @@ static int drm_sched_main(void *param)

                if (fence) {
                        s_fence->parent = dma_fence_get(fence);
-                       r = dma_fence_add_callback(fence, &s_fence->cb,
+                       r = dma_fence_add_callback(fence, &sched_job->cb,
                                                   drm_sched_process_job);
                        if (r == -ENOENT)
-                               drm_sched_process_job(fence, &s_fence-
cb);
+                               drm_sched_process_job(fence, &sched_job-
cb);
                        else if (r)
                                DRM_ERROR("fence add callback failed
(%d)\n",
                                          r);
                        dma_fence_put(fence);
                } else
-                       drm_sched_process_job(NULL, &s_fence->cb);
+                       drm_sched_process_job(NULL, &sched_job->cb);

                wake_up(&sched->job_scheduled);
        }
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index c94b592..f29aa1c 100644
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -138,10 +138,6 @@ struct drm_sched_fence {
        struct dma_fence                finished;

           /**
-         * @cb: the callback for the parent fence below.
-         */
-       struct dma_fence_cb             cb;
-        /**
            * @parent: the fence returned by &drm_sched_backend_ops.run_job
            * when scheduling the job on hardware. We signal the
            * &drm_sched_fence.finished fence once parent is signalled.
@@ -182,6 +178,7 @@ struct drm_sched_fence
*to_drm_sched_fence(struct dma_fence *f);
    *         be scheduled further.
    * @s_priority: the priority of the job.
    * @entity: the entity to which this job belongs.
+ * @cb: the callback for the parent fence in s_fence.
    *
    * A job is created by the driver using drm_sched_job_init(), and
    * should call drm_sched_entity_push_job() once it wants the scheduler
@@ -199,6 +196,7 @@ struct drm_sched_job {
        atomic_t                        karma;
        enum drm_sched_priority         s_priority;
        struct drm_sched_entity  *entity;
+       struct dma_fence_cb             cb;
   };

   static inline bool drm_sched_invalidate_job(struct drm_sched_job *s_job,
--
2.7.4

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