Re: [PATCH v2 4/7] drm/panfrost: Add the ability to create submit queues

On 01/07/2021 10:12, Boris Brezillon wrote:

Needed to keep VkQueues isolated from each other.

One more comment I noticed when I tried this out:

[...]

+struct panfrost_submitqueue * +panfrost_submitqueue_create(struct panfrost_file_priv *ctx,

• 	    enum panfrost_submitqueue_priority priority,
  

• 	    u32 flags)
  

+{

• struct panfrost_submitqueue *queue;
• enum drm_sched_priority sched_prio;
• int ret, i;
• if (flags || priority >= PANFROST_SUBMITQUEUE_PRIORITY_COUNT)

• return ERR_PTR(-EINVAL);
  

• queue = kzalloc(sizeof(*queue), GFP_KERNEL);
• if (!queue)

• return ERR_PTR(-ENOMEM);
  

• queue->pfdev = ctx->pfdev;
• sched_prio = to_sched_prio(priority);
• for (i = 0; i < NUM_JOB_SLOTS; i++) {

• struct drm_gpu_scheduler *sched;
  

• sched = panfrost_job_get_sched(ctx->pfdev, i);
  

• ret = drm_sched_entity_init(&queue->sched_entity[i],
  

• 			    sched_prio, &sched, 1, NULL);
  

• if (ret)
  

• 	break;
  

• }
• if (ret) {

• for (i--; i >= 0; i--)
  

• 	drm_sched_entity_destroy(&queue->sched_entity[i]);
  

• return ERR_PTR(ret);
  

• }
• kref_init(&queue->refcount);
• idr_lock(&ctx->queues);
• ret = idr_alloc(&ctx->queues, queue, 0, INT_MAX, GFP_KERNEL);

This makes lockdep complain. idr_lock() is a spinlock and GFP_KERNEL can sleep. So either we need to bring our own mutex here or not use GFP_KERNEL.

Steve