From 9efe055ec1a45ff3f56a0698d94bea4693765e3d Mon Sep 17 00:00:00 2001
From: Ben Walker <benjamin.walker@intel.com>
Date: Mon, 27 Jun 2016 16:13:49 -0700
Subject: [PATCH] nvmf: Remove pending list for RDMA operations.

The queue depth allowed for incoming commands is set
such that we can do the maximum number of RDMA reads
necessary. There is never a case where a READ will need
to be queued anymore.

Change-Id: I4f7e7f4a59f6358065b82f36a5e22744af210d07
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
---
 lib/nvmf/rdma.c | 53 -------------------------------------------------
 lib/nvmf/rdma.h |  2 --
 2 files changed, 55 deletions(-)

diff --git a/lib/nvmf/rdma.c b/lib/nvmf/rdma.c
index 9152e57fe..1ec3734f5 100644
--- a/lib/nvmf/rdma.c
+++ b/lib/nvmf/rdma.c
@@ -182,19 +182,12 @@ nvmf_drain_cq(struct spdk_nvmf_conn *conn)
 void
 nvmf_rdma_conn_cleanup(struct spdk_nvmf_conn *conn)
 {
-	struct spdk_nvmf_rdma_request *rdma_req;
 	int rc;
 
 	SPDK_TRACELOG(SPDK_TRACE_DEBUG, "Enter\n");
 
 	rdma_destroy_qp(conn->rdma.cm_id);
 
-	while (!STAILQ_EMPTY(&conn->rdma.pending_rdma_reqs)) {
-		rdma_req = STAILQ_FIRST(&conn->rdma.pending_rdma_reqs);
-		STAILQ_REMOVE_HEAD(&conn->rdma.pending_rdma_reqs, link);
-		STAILQ_INSERT_TAIL(&conn->rdma.rdma_reqs, rdma_req, link);
-	}
-
 	free_rdma_reqs(conn);
 
 	nvmf_drain_cq(conn);
@@ -256,19 +249,6 @@ nvmf_post_rdma_read(struct spdk_nvmf_conn *conn,
 	struct spdk_nvmf_rdma_request *rdma_req = get_rdma_req(req);
 	int rc;
 
-	/*
-	 * Queue the rdma read if it would exceed max outstanding
-	 * RDMA read limit.
-	 */
-	if (conn->rdma.pending_rdma_read_count == conn->rdma.queue_depth) {
-		SPDK_TRACELOG(SPDK_TRACE_RDMA, "Insert rdma read into pending queue: rdma_req %p\n",
-			      rdma_req);
-		STAILQ_REMOVE(&conn->rdma.rdma_reqs, rdma_req, spdk_nvmf_rdma_request, link);
-		STAILQ_INSERT_TAIL(&conn->rdma.pending_rdma_reqs, rdma_req, link);
-		return 0;
-	}
-	conn->rdma.pending_rdma_read_count++;
-
 	/* temporarily adjust SGE to only copy what the host is prepared to send. */
 	rdma_req->bb_sgl.length = req->length;
 
@@ -592,7 +572,6 @@ nvmf_rdma_connect(struct rdma_cm_event *event)
 	}
 	SPDK_TRACELOG(SPDK_TRACE_DEBUG, "NVMf fabric connection initialized\n");
 
-	STAILQ_INIT(&conn->rdma.pending_rdma_reqs);
 	STAILQ_INIT(&conn->rdma.rdma_reqs);
 
 	/* Allocate Buffers */
@@ -888,32 +867,6 @@ nvmf_rdma_init(void)
 	return num_devices_found;
 }
 
-static int
-nvmf_process_pending_rdma(struct spdk_nvmf_conn *conn)
-{
-	struct spdk_nvmf_rdma_request *rdma_req;
-	int rc;
-
-	conn->rdma.pending_rdma_read_count--;
-	if (!STAILQ_EMPTY(&conn->rdma.pending_rdma_reqs)) {
-		rdma_req = STAILQ_FIRST(&conn->rdma.pending_rdma_reqs);
-		STAILQ_REMOVE_HEAD(&conn->rdma.pending_rdma_reqs, link);
-		STAILQ_INSERT_TAIL(&conn->rdma.rdma_reqs, rdma_req, link);
-
-		SPDK_TRACELOG(SPDK_TRACE_RDMA, "Issue rdma read from pending queue: rdma_req %p\n",
-			      rdma_req);
-
-		rc = nvmf_post_rdma_read(conn, &rdma_req->req);
-		if (rc) {
-			SPDK_ERRLOG("Unable to post pending rdma read descriptor\n");
-			return -1;
-		}
-	}
-
-	return 0;
-}
-
-
 static int
 nvmf_recv(struct spdk_nvmf_conn *conn, struct ibv_wc *wc)
 {
@@ -1012,12 +965,6 @@ nvmf_check_rdma_completions(struct spdk_nvmf_conn *conn)
 				SPDK_ERRLOG("request_exec error %d after RDMA Read completion\n", rc);
 				return -1;
 			}
-
-			rc = nvmf_process_pending_rdma(conn);
-			if (rc) {
-				SPDK_ERRLOG("nvmf_process_pending_rdma() failed: %d\n", rc);
-				return -1;
-			}
 			break;
 
 		case IBV_WC_RECV:
diff --git a/lib/nvmf/rdma.h b/lib/nvmf/rdma.h
index 2d77655ca..8368b5868 100644
--- a/lib/nvmf/rdma.h
+++ b/lib/nvmf/rdma.h
@@ -50,8 +50,6 @@ struct spdk_nvmf_rdma_conn {
 
 	uint16_t			queue_depth;
 
-	uint8_t						pending_rdma_read_count;
-	STAILQ_HEAD(, spdk_nvmf_rdma_request)		pending_rdma_reqs;
 	STAILQ_HEAD(, spdk_nvmf_rdma_request)		rdma_reqs;
 };