drm/amdgpu: fix entity wakeup race condition

That actually didn't worked at all.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>

diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
index 2dd9c8a..0133697 100644 (file)
--- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
@@ -108,7 +108,6 @@ static bool amd_sched_ready(struct amd_gpu_scheduler *sched)
 static struct amd_sched_entity *
 amd_sched_select_context(struct amd_gpu_scheduler *sched)
 {
-       struct amd_sched_entity *wake_entity = NULL;
        struct amd_sched_entity *tmp;
 
        if (!amd_sched_ready(sched))
@@ -119,11 +118,6 @@ amd_sched_select_context(struct amd_gpu_scheduler *sched)
        if (tmp == NULL)
                tmp = amd_sched_rq_select_entity(&sched->sched_rq);
 
-       if (sched->current_entity && (sched->current_entity != tmp))
-               wake_entity = sched->current_entity;
-       sched->current_entity = tmp;
-       if (wake_entity && wake_entity->need_wakeup)
-               wake_up(&wake_entity->wait_queue);
        return tmp;
 }
 
@@ -184,16 +178,17 @@ static bool is_context_entity_initialized(struct amd_gpu_scheduler *sched,
                entity->belongto_rq != NULL;
 }
 
-static bool is_context_entity_idle(struct amd_gpu_scheduler *sched,
-                                  struct amd_sched_entity *entity)
+/**
+ * Check if entity is idle
+ *
+ * @entity     The pointer to a valid scheduler entity
+ *
+ * Return true if entity don't has any unscheduled jobs.
+ */
+static bool amd_sched_entity_is_idle(struct amd_sched_entity *entity)
 {
-       /**
-        * Idle means no pending IBs, and the entity is not
-        * currently being used.
-       */
-       barrier();
-       if ((sched->current_entity != entity) &&
-           kfifo_is_empty(&entity->job_queue))
+       rmb();
+       if (kfifo_is_empty(&entity->job_queue))
                return true;
 
        return false;
@@ -210,8 +205,8 @@ static bool is_context_entity_idle(struct amd_gpu_scheduler *sched,
 int amd_sched_entity_fini(struct amd_gpu_scheduler *sched,
                            struct amd_sched_entity *entity)
 {
-       int r = 0;
        struct amd_sched_rq *rq = entity->belongto_rq;
+       long r;
 
        if (!is_context_entity_initialized(sched, entity))
                return 0;
@@ -220,13 +215,11 @@ int amd_sched_entity_fini(struct amd_gpu_scheduler *sched,
         * The client will not queue more IBs during this fini, consume existing
         * queued IBs
        */
-       r = wait_event_timeout(
-               entity->wait_queue,
-               is_context_entity_idle(sched, entity),
-               msecs_to_jiffies(AMD_GPU_WAIT_IDLE_TIMEOUT_IN_MS)
-               ) ?  0 : -1;
+       r = wait_event_timeout(entity->wait_queue,
+               amd_sched_entity_is_idle(entity),
+               msecs_to_jiffies(AMD_GPU_WAIT_IDLE_TIMEOUT_IN_MS));
 
-       if (r)
+       if (r <= 0)
                DRM_INFO("Entity %p is in waiting state during fini\n",
                         entity);
 
@@ -325,6 +318,12 @@ static int amd_sched_main(void *param)
                        fence_put(fence);
                }
                mutex_unlock(&sched->sched_lock);
+
+               if (c_entity->need_wakeup) {
+                       c_entity->need_wakeup = false;
+                       wake_up(&c_entity->wait_queue);
+               }
+
        }
        return 0;
 }

diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
index bbfcc37..d4116bb 100644 (file)
--- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
@@ -117,7 +117,6 @@ struct amd_gpu_scheduler {
        uint32_t                        granularity; /* in ms unit */
        uint32_t                        preemption;
        wait_queue_head_t               wait_queue;
-       struct amd_sched_entity *current_entity;
        struct mutex                    sched_lock;
        uint32_t                        hw_submission_limit;
 };