From 9637e17d2d435e1e9d4b662d1405b9cda8d9c21d Mon Sep 17 00:00:00 2001
From: Changpeng Liu <changpeng.liu@intel.com>
Date: Wed, 12 Sep 2018 04:20:08 -0400
Subject: [PATCH] iscsi: reserve value 0xffffffff for TTT in R2T

According to RFC3720 10.8.5, value 0xffffffff is reserved
for Target Transfer Tag when sending an R2T to initiator.

Change-Id: I0d92539d7640d3a4ffc5f8452cfe16f34269e7d0
Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-on: https://review.gerrithub.io/425369
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
---
 lib/iscsi/iscsi.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/iscsi/iscsi.c b/lib/iscsi/iscsi.c
index b0fa9aded7..99fd851ccb 100644
--- a/lib/iscsi/iscsi.c
+++ b/lib/iscsi/iscsi.c
@@ -3398,7 +3398,13 @@ spdk_add_transfer_task(struct spdk_iscsi_conn *conn,
 	task->next_expected_r2t_offset = data_len;
 	task->current_r2t_length = 0;
 	task->R2TSN = 0;
-	task->ttt = ++conn->ttt;
+	/* According to RFC3720 10.8.5, 0xffffffff is
+	 * reserved for TTT in R2T.
+	 */
+	if (++conn->ttt == 0xffffffffu) {
+		conn->ttt = 0;
+	}
+	task->ttt = conn->ttt;
 
 	while (data_len != transfer_len) {
 		len = DMIN32(max_burst_len, (transfer_len - data_len));