Target/iscsi,iser: Avoid accepting transport connections during stop stage

When the target is in stop stage, iSER transport initiates RDMA disconnects.
The iSER initiator may wish to establish a new connection over the
still existing network portal. In this case iSER transport should not
accept and resume new RDMA connections. In order to learn that, iscsi_np
is added with enabled flag so the iSER transport can check when deciding
weather to accept and resume a new connection request.

The iscsi_np is enabled after successful transport setup, and disabled
before iscsi_np login threads are cleaned up.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index 826eaf5..a171046 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -562,7 +562,15 @@
 	struct isert_device *device;
 	struct ib_device *ib_dev = cma_id->device;
 	int ret = 0;
-	u8 pi_support = np->tpg_np->tpg->tpg_attrib.t10_pi;
+	u8 pi_support;
+
+	spin_lock_bh(&np->np_thread_lock);
+	if (!np->enabled) {
+		spin_unlock_bh(&np->np_thread_lock);
+		pr_debug("iscsi_np is not enabled, reject connect request\n");
+		return rdma_reject(cma_id, NULL, 0);
+	}
+	spin_unlock_bh(&np->np_thread_lock);
 
 	pr_debug("Entering isert_connect_request cma_id: %p, context: %p\n",
 		 cma_id, cma_id->context);
@@ -653,6 +661,7 @@
 		goto out_mr;
 	}
 
+	pi_support = np->tpg_np->tpg->tpg_attrib.t10_pi;
 	if (pi_support && !device->pi_capable) {
 		pr_err("Protection information requested but not supported\n");
 		ret = -EINVAL;