drm/sched: Disallow initializing entities with no schedulers

Since we have removed the case where amdgpu was initializing entitites
with either no schedulers on the list, or with a single NULL scheduler,
and there appears no other drivers which rely on this, we can simplify the
scheduler by explicitly rejecting that early.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Philipp Stanner <phasta@kernel.org>
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Philipp Stanner <phasta@kernel.org>
Tested-by: Vitaly Prosyak <vitaly.prosyak@amd.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://patch.msgid.link/20260417103744.76020-2-tvrtko.ursulin@igalia.com

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 85aa54d51b2d7d3cada4fb144e85928106a0a7f5..37c1fe3d469f9618ba11a6df0fc86409027a2d87 100644 (file)
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -61,32 +61,27 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
                          unsigned int num_sched_list,
                          atomic_t *guilty)
 {
-       if (!(entity && sched_list && (num_sched_list == 0 || sched_list[0])))
+       if (!entity || !sched_list || !num_sched_list || !sched_list[0])
                return -EINVAL;
 
        memset(entity, 0, sizeof(struct drm_sched_entity));
        INIT_LIST_HEAD(&entity->list);
        entity->rq = NULL;
        entity->guilty = guilty;
-       entity->num_sched_list = num_sched_list;
        entity->priority = priority;
        entity->last_user = current->group_leader;
-       /*
-        * It's perfectly valid to initialize an entity without having a valid
-        * scheduler attached. It's just not valid to use the scheduler before it
-        * is initialized itself.
-        */
+       entity->num_sched_list = num_sched_list;
        entity->sched_list = num_sched_list > 1 ? sched_list : NULL;
        RCU_INIT_POINTER(entity->last_scheduled, NULL);
        RB_CLEAR_NODE(&entity->rb_tree_node);
 
-       if (num_sched_list && !sched_list[0]->sched_rq) {
+       if (!sched_list[0]->sched_rq) {
                /* Since every entry covered by num_sched_list
                 * should be non-NULL and therefore we warn drivers
                 * not to do this and to fix their DRM calling order.
                 */
                pr_warn("%s: called with uninitialized scheduler\n", __func__);
-       } else if (num_sched_list) {
+       } else {
                /* The "priority" of an entity cannot exceed the number of run-queues of a
                 * scheduler. Protect against num_rqs being 0, by converting to signed. Choose
                 * the lowest priority available.