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>

drivers/infiniband/ulp/isert/ib_isert.c

@@ -562,7 +562,15 @@ isert_connect_request(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
 	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 @@ isert_connect_request(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
 		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;

drivers/target/iscsi/iscsi_target_core.h

@@ -775,6 +775,7 @@ struct iscsi_np {
 	int			np_ip_proto;
 	int			np_sock_type;
 	enum np_thread_state_table np_thread_state;
+	bool                    enabled;
 	enum iscsi_timer_flags_table np_login_timer_flags;
 	u32			np_exports;
 	enum np_flags_table	np_flags;

drivers/target/iscsi/iscsi_target_login.c

@@ -984,6 +984,7 @@ int iscsi_target_setup_login_socket(
 	}
 
 	np->np_transport = t;
+	np->enabled = true;
 	return 0;
 }
 

drivers/target/iscsi/iscsi_target_tpg.c

@@ -184,6 +184,7 @@ static void iscsit_clear_tpg_np_login_thread(
 		return;
 	}
 
+	tpg_np->tpg_np->enabled = false;
 	iscsit_reset_np_thread(tpg_np->tpg_np, tpg_np, tpg, shutdown);
 }