[PATCH] nvme-tcp: strict pdu pacing to avoid send stalls on TLS

[Sagi Grimberg]

On 17/04/2024 18:39, Hannes Reinecke wrote:
> TLS requires a strict pdu pacing via MSG_EOR to signal the end
> of a record and subsequent encryption. If we do not set MSG_EOR
> at the end of a sequence the record won't be closed, encryption
> doesn't start, and we end up with a send stall as the message
> will never be passed on to the TCP layer.
> So do not check for the queue status when figuring out whether
> MSG_MORE should be set but rather make it dependent on the current
> command only.

How about making nvme_tcp_queue_more take into account nvme_tcp_tls()?
so we preserve the behavior without tls.

i.e. something like:
--
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 0ba62fc647b3..bbffc67f8a1e 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -360,12 +360,18 @@ static inline void nvme_tcp_send_all(struct 
nvme_tcp_queue *queue)
         } while (ret > 0);
  }

-static inline bool nvme_tcp_queue_more(struct nvme_tcp_queue *queue)
+static inline bool nvme_tcp_queue_has_pending(struct nvme_tcp_queue *queue)
  {
         return !list_empty(&queue->send_list) ||
                 !llist_empty(&queue->req_list);
  }

+static inline bool nvme_tcp_queue_more(struct nvme_tcp_queue *queue)
+{
+       return !nvme_tcp_tls(queue->ctrl) &&
+               nvme_tcp_queue_has_pending(queue);
+}
+
  static inline void nvme_tcp_queue_request(struct nvme_tcp_request *req,
                 bool sync, bool last)
  {
@@ -386,7 +392,7 @@ static inline void nvme_tcp_queue_request(struct 
nvme_tcp_request *req,
                 mutex_unlock(&queue->send_mutex);
         }

-       if (last && nvme_tcp_queue_more(queue))
+       if (last && nvme_tcp_queue_has_pending(queue))
                 queue_work_on(queue->io_cpu, nvme_tcp_wq, &queue->io_work);
  }
--