nvmet: cleanups the loop in nvmet_async_events_process

Based-on-a-patch-by: NChristoph Hellwig <hch@infradead.org>
Tested-by: NYi Zhang <yi.zhang@redhat.com>
Signed-off-by: NDavid Milburn <dmilburn@redhat.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

drivers/nvme/target/core.c

@@ -134,15 +134,10 @@ static void nvmet_async_events_process(struct nvmet_ctrl *ctrl, u16 status)
 	struct nvmet_async_event *aen;
 	struct nvmet_req *req;
 
-	while (1) {
-		mutex_lock(&ctrl->lock);
-		aen = list_first_entry_or_null(&ctrl->async_events,
-				struct nvmet_async_event, entry);
-		if (!aen || !ctrl->nr_async_event_cmds) {
-			mutex_unlock(&ctrl->lock);
-			break;
-		}
-
+	mutex_lock(&ctrl->lock);
+	while (ctrl->nr_async_event_cmds && !list_empty(&ctrl->async_events)) {
+		aen = list_first_entry(&ctrl->async_events,
+				       struct nvmet_async_event, entry);
 		req = ctrl->async_event_cmds[--ctrl->nr_async_event_cmds];
 		if (status == 0)
 			nvmet_set_result(req, nvmet_async_event_result(aen));
@@ -153,7 +148,9 @@ static void nvmet_async_events_process(struct nvmet_ctrl *ctrl, u16 status)
 		mutex_unlock(&ctrl->lock);
 		trace_nvmet_async_event(ctrl, req->cqe->result.u32);
 		nvmet_req_complete(req, status);
+		mutex_lock(&ctrl->lock);
 	}
+	mutex_unlock(&ctrl->lock);
 }
 
 static void nvmet_async_events_free(struct nvmet_ctrl *ctrl)