[PATCH AUTOSEL 5.0 135/262] drm/sched: Fix entities with 0 rqs.

Sasha Levin
2019-03-27T19:23:24Z

From: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>

[ Upstream commit 1decbf6bb0b4dc56c9da6c5e57b994ebfc2be3aa ]

Some blocks in amdgpu can have 0 rqs.

Job creation already fails with -ENOENT when entity->rq is NULL,
so jobs cannot be pushed. Without a rq there is no scheduler to
pop jobs, and rq selection already does the right thing with a
list of length 0.

So the operations we need to fix are:
- Creation, do not set rq to rq_list[0] if the list can have length 0.
- Do not flush any jobs when there is no rq.
- On entity destruction handle the rq = NULL case.
- on set_priority, do not try to change the rq if it is NULL.

Signed-off-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/scheduler/sched_entity.c | 39 ++++++++++++++++--------
1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index e2942c9a11a7..35ddbec1375a 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -52,12 +52,12 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
{
int i;

- if (!(entity && rq_list && num_rq_list > 0 && rq_list[0]))
+ if (!(entity && rq_list && (num_rq_list == 0 || rq_list[0])))
return -EINVAL;

memset(entity, 0, sizeof(struct drm_sched_entity));
INIT_LIST_HEAD(&entity->list);
- entity->rq = rq_list[0];
+ entity->rq = NULL;
entity->guilty = guilty;
entity->num_rq_list = num_rq_list;
entity->rq_list = kcalloc(num_rq_list, sizeof(struct drm_sched_rq *),
@@ -67,6 +67,10 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,

for (i = 0; i < num_rq_list; ++i)
entity->rq_list[i] = rq_list[i];
+
+ if (num_rq_list)
+ entity->rq = rq_list[0];
+
entity->last_scheduled = NULL;

spin_lock_init(&entity->rq_lock);
@@ -165,6 +169,9 @@ long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
struct task_struct *last_user;
long ret = timeout;

+ if (!entity->rq)
+ return 0;
+
sched = entity->rq->sched;
/**
* The client will not queue more IBs during this fini, consume existing
@@ -264,20 +271,24 @@ static void drm_sched_entity_kill_jobs(struct drm_sched_entity *entity)
*/
void drm_sched_entity_fini(struct drm_sched_entity *entity)
{
- struct drm_gpu_scheduler *sched;
+ struct drm_gpu_scheduler *sched = NULL;

- sched = entity->rq->sched;
- drm_sched_rq_remove_entity(entity->rq, entity);
+ if (entity->rq) {
+ sched = entity->rq->sched;
+ drm_sched_rq_remove_entity(entity->rq, entity);
+ }

/* Consumption of existing IBs wasn't completed. Forcefully
* remove them here.
*/
if (spsc_queue_peek(&entity->job_queue)) {
- /* Park the kernel for a moment to make sure it isn't processing
- * our enity.
- */
- kthread_park(sched->thread);
- kthread_unpark(sched->thread);
+ if (sched) {
+ /* Park the kernel for a moment to make sure it isn't processing
+ * our enity.
+ */
+ kthread_park(sched->thread);
+ kthread_unpark(sched->thread);
+ }
if (entity->dependency) {
dma_fence_remove_callback(entity->dependency,
&entity->cb);
@@ -362,9 +373,11 @@ void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
for (i = 0; i < entity->num_rq_list; ++i)
drm_sched_entity_set_rq_priority(&entity->rq_list[i], priority);

- drm_sched_rq_remove_entity(entity->rq, entity);
- drm_sched_entity_set_rq_priority(&entity->rq, priority);
- drm_sched_rq_add_entity(entity->rq, entity);
+ if (entity->rq) {
+ drm_sched_rq_remove_entity(entity->rq, entity);
+ drm_sched_entity_set_rq_priority(&entity->rq, priority);
+ drm_sched_rq_add_entity(entity->rq, entity);
+ }

spin_unlock(&entity->rq_lock);
}
--
2.19.1