RE: [PATCH] Revert "drm/scheduler: Avoid accessing freed bad job."

["Liu, Monk" <Monk.Liu@amd.com>]

[AMD Official Use Only]

Reviewed-by: Monk Liu <monk.liu@amd.com>

Thanks 

------------------------------------------
Monk Liu | Cloud-GPU Core team
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-----Original Message-----
From: Jingwen Chen <Jingwen.Chen2@amd.com> 
Sent: Tuesday, August 17, 2021 12:28 PM
To: amd-gfx@lists.freedesktop.org
Cc: Liu, Monk <Monk.Liu@amd.com>; Koenig, Christian <Christian.Koenig@amd.com>; Grodzovsky, Andrey <Andrey.Grodzovsky@amd.com>; Chen, JingWen <JingWen.Chen2@amd.com>
Subject: [PATCH] Revert "drm/scheduler: Avoid accessing freed bad job."

[Why]
for bailing job, this commit will delete it from pending list thus the bailing job will never have a chance to be resubmitted even in advance tdr mode.

[How]
after embeded hw_fence into amdgpu_job is done, the race condition that this commit tries to work around is completely solved.So revert this commit.
This reverts commit 135517d3565b48f4def3b1b82008bc17eb5d1c90.

Signed-off-by: Jingwen Chen <Jingwen.Chen2@amd.com>
---
 drivers/gpu/drm/scheduler/sched_main.c | 27 --------------------------
 1 file changed, 27 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index a2a953693b45..31d1176d939f 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -317,21 +317,10 @@ static void drm_sched_job_timedout(struct work_struct *work)
 	enum drm_gpu_sched_stat status = DRM_GPU_SCHED_STAT_NOMINAL;
 
 	sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
-
-	/* Protects against concurrent deletion in drm_sched_get_cleanup_job */
-	spin_lock(&sched->job_list_lock);
 	job = list_first_entry_or_null(&sched->pending_list,
 				       struct drm_sched_job, list);
 
 	if (job) {
-		/*
-		 * Remove the bad job so it cannot be freed by concurrent
-		 * drm_sched_cleanup_jobs. It will be reinserted back after sched->thread
-		 * is parked at which point it's safe.
-		 */
-		list_del_init(&job->list);
-		spin_unlock(&sched->job_list_lock);
-
 		status = job->sched->ops->timedout_job(job);
 
 		/*
@@ -342,8 +331,6 @@ static void drm_sched_job_timedout(struct work_struct *work)
 			job->sched->ops->free_job(job);
 			sched->free_guilty = false;
 		}
-	} else {
-		spin_unlock(&sched->job_list_lock);
 	}
 
 	if (status != DRM_GPU_SCHED_STAT_ENODEV) { @@ -392,20 +379,6 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
 
 	kthread_park(sched->thread);
 
-	/*
-	 * Reinsert back the bad job here - now it's safe as
-	 * drm_sched_get_cleanup_job cannot race against us and release the
-	 * bad job at this point - we parked (waited for) any in progress
-	 * (earlier) cleanups and drm_sched_get_cleanup_job will not be called
-	 * now until the scheduler thread is unparked.
-	 */
-	if (bad && bad->sched == sched)
-		/*
-		 * Add at the head of the queue to reflect it was the earliest
-		 * job extracted.
-		 */
-		list_add(&bad->list, &sched->pending_list);
-
 	/*
 	 * Iterate the job list from later to  earlier one and either deactive
 	 * their HW callbacks or remove them from pending list if they already
--
2.25.1