drm/msm: Split out idr_lock

Otherwise if we hit reclaim pinning objects in the submit path, we'll be
blocking retire_worker trying to free a submit.

Signed-off-by: Rob Clark <[e-mail]>
Patchwork: https://patchwork.freedesktop.org/patch/496116/
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpu/drm/msm/msm_drv.c

···
 	 * retired, so if the fence is not found it means there is nothing
 	 * to wait for
 	 */
-	ret = mutex_lock_interruptible(&queue->lock);
+	ret = mutex_lock_interruptible(&queue->idr_lock);
 	if (ret)
 		return ret;
 	fence = idr_find(&queue->fence_idr, fence_id);
 	if (fence)
 		fence = dma_fence_get_rcu(fence);
-	mutex_unlock(&queue->lock);
+	mutex_unlock(&queue->idr_lock);
 
 	if (!fence)
 		return 0;

drivers/gpu/drm/msm/msm_gem_submit.c

···
 	unsigned i;
 
 	if (submit->fence_id) {
-		mutex_lock(&submit->queue->lock);
+		mutex_lock(&submit->queue->idr_lock);
 		idr_remove(&submit->queue->fence_idr, submit->fence_id);
-		mutex_unlock(&submit->queue->lock);
+		mutex_unlock(&submit->queue->idr_lock);
 	}
 
 	dma_fence_put(submit->user_fence);
···
 
 	submit->nr_cmds = i;
 
+	mutex_lock(&queue->idr_lock);
+
 	/*
 	 * If using userspace provided seqno fence, validate that the id
 	 * is available before arming sched job.  Since access to fence_idr
···
 	 */
 	if ((args->flags & MSM_SUBMIT_FENCE_SN_IN) &&
 			idr_find(&queue->fence_idr, args->fence)) {
+		mutex_unlock(&queue->idr_lock);
 		ret = -EINVAL;
 		goto out;
 	}
···
 						    submit->user_fence, 1,
 						    INT_MAX, GFP_KERNEL);
 	}
+
+	mutex_unlock(&queue->idr_lock);
+
 	if (submit->fence_id < 0) {
 		ret = submit->fence_id;
 		submit->fence_id = 0;

drivers/gpu/drm/msm/msm_gpu.h

···
  * @node:      node in the context's list of submitqueues
  * @fence_idr: maps fence-id to dma_fence for userspace visible fence
  *             seqno, protected by submitqueue lock
- * @lock:      submitqueue lock
+ * @idr_lock:  for serializing access to fence_idr
+ * @lock:      submitqueue lock for serializing submits on a queue
  * @ref:       reference count
  * @entity:    the submit job-queue
  */
···
 	struct msm_file_private *ctx;
 	struct list_head node;
 	struct idr fence_idr;
+	struct mutex idr_lock;
 	struct mutex lock;
 	struct kref ref;
 	struct drm_sched_entity *entity;

drivers/gpu/drm/msm/msm_submitqueue.c

···
 		*id = queue->id;
 
 	idr_init(&queue->fence_idr);
+	mutex_init(&queue->idr_lock);
 	mutex_init(&queue->lock);
 
 	list_add_tail(&queue->node, &ctx->submitqueues);