[PATCH] drm/scheduler: Partially revert "drm/scheduler: track GPU active time per entity"

[Pan, Xinhui]

[AMD Official Use Only - General]

Can we just add kref for entity?
Or just collect such job time usage somewhere else?

-----Original Message-----
From: Pan, Xinhui <Xinhui.Pan at amd.com>
Sent: Thursday, August 17, 2023 1:05 PM
To: amd-gfx at lists.freedesktop.org
Cc: Tuikov, Luben <Luben.Tuikov at amd.com>; airlied at gmail.com; dri-devel at lists.freedesktop.org; l.stach at pengutronix.de; Koenig, Christian <Christian.Koenig at amd.com>; Pan, Xinhui <Xinhui.Pan at amd.com>
Subject: [PATCH] drm/scheduler: Partially revert "drm/scheduler: track GPU active time per entity"

This patch partially revert commit df622729ddbf ("drm/scheduler: track GPU active time per entity") which touchs entity without any reference.

I notice there is one memory overwritten from gpu scheduler side.
The case is like below.
A(drm_sched_main)                       B(vm fini)
drm_sched_job_begin                     drm_sched_entity_kill
        //job in pending_list                   wait_for_completion
complete_all                            ...
...                                     kfree entity
drm_sched_get_cleanup_job
        //fetch job from pending_list
        access job->entity //memory overwitten

As long as we can NOT guarantee entity is alive in this case, lets revert it for now.

Signed-off-by: xinhui pan <xinhui.pan at amd.com>
---
 drivers/gpu/drm/scheduler/sched_main.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 602361c690c9..1b3f1a6a8514 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -907,12 +907,6 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)

        spin_unlock(&sched->job_list_lock);

-       if (job) {
-               job->entity->elapsed_ns += ktime_to_ns(
-                       ktime_sub(job->s_fence->finished.timestamp,
-                                 job->s_fence->scheduled.timestamp));
-       }
-
        return job;
 }

--
2.34.1