From e72453b39f325e4ff57072a11385e45bbf91ca64 Mon Sep 17 00:00:00 2001
From: Changpeng Liu <changpeng.liu@intel.com>
Date: Tue, 24 Aug 2021 17:47:29 +0800
Subject: [PATCH] nvmf/vfio-user: don't unmap commands without data buffers

libvfio-user will assert if the command didn't have data
buffers.

Fix issue #2124.

Change-Id: I43e9562c614bc65e54dbf650447369317c10f7b5
Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/9264
Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com>
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Dong Yi <dongx.yi@intel.com>
Reviewed-by: Thanos Makatos <thanos.makatos@nutanix.com>
Reviewed-by: John Levon <levon@movementarian.org>
---
 lib/nvmf/vfio_user.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/nvmf/vfio_user.c b/lib/nvmf/vfio_user.c
index a7382fb32..a7ca63251 100644
--- a/lib/nvmf/vfio_user.c
+++ b/lib/nvmf/vfio_user.c
@@ -1328,7 +1328,9 @@ handle_cmd_rsp(struct nvmf_vfio_user_req *vu_req, void *cb_arg)
 	assert(vu_req != NULL);
 	assert(vu_ctrlr != NULL);
 
-	vfu_unmap_sg(vu_ctrlr->endpoint->vfu_ctx, vu_req->sg, vu_req->iov, vu_req->iovcnt);
+	if (spdk_likely(vu_req->iovcnt)) {
+		vfu_unmap_sg(vu_ctrlr->endpoint->vfu_ctx, vu_req->sg, vu_req->iov, vu_req->iovcnt);
+	}
 	sqid = vu_qpair->qpair.qid;
 	cqid = vu_ctrlr->qp[sqid]->sq.cqid;