Reviewed-by: monk....@amd.com

_____________________________________
Monk Liu|GPU Virtualization Team |AMD


-----Original Message-----
From: Christian König <ckoenig.leichtzumer...@gmail.com> 
Sent: Friday, August 9, 2019 11:31 PM
To: Grodzovsky, Andrey <andrey.grodzov...@amd.com>; 
dri-devel@lists.freedesktop.org; Liu, Monk <monk....@amd.com>; Deng, Emily 
<emily.d...@amd.com>
Subject: [PATCH] drm/scheduler: use job count instead of peek

The spsc_queue_peek function is accessing queue->head which belongs to the 
consumer thread and shouldn't be accessed by the producer

This is fixing a rare race condition when destroying entities.

Signed-off-by: Christian König <christian.koe...@amd.com>
---
 drivers/gpu/drm/scheduler/sched_entity.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c 
b/drivers/gpu/drm/scheduler/sched_entity.c
index 35ddbec1375a..671c90f34ede 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -95,7 +95,7 @@ static bool drm_sched_entity_is_idle(struct drm_sched_entity 
*entity)
        rmb(); /* for list_empty to work without lock */
 
        if (list_empty(&entity->list) ||
-           spsc_queue_peek(&entity->job_queue) == NULL)
+           spsc_queue_count(&entity->job_queue) == 0)
                return true;
 
        return false;
@@ -281,7 +281,7 @@ void drm_sched_entity_fini(struct drm_sched_entity *entity)
        /* Consumption of existing IBs wasn't completed. Forcefully
         * remove them here.
         */
-       if (spsc_queue_peek(&entity->job_queue)) {
+       if (spsc_queue_count(&entity->job_queue)) {
                if (sched) {
                        /* Park the kernel for a moment to make sure it isn't 
processing
                         * our enity.
--
2.17.1

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