iser-target: Fix multi network portal shutdown regression

commit 2363d196 upstream.

This patch fixes a iser-target specific regression introduced in
v3.15-rc6 with:

commit 14f4b54f
Author: Sagi Grimberg <sagig@mellanox.com>
Date:   Tue Apr 29 13:13:47 2014 +0300

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

where the change to set iscsi_np->enabled = false within
iscsit_clear_tpg_np_login_thread() meant that a iscsi_np with
two iscsi_tpg_np exports would have it's parent iscsi_np set
to a disabled state, even if other iscsi_tpg_np exports still
existed.

This patch changes iscsit_clear_tpg_np_login_thread() to only
set iscsi_np->enabled = false when shutdown = true, and also
changes iscsit_del_np() to set iscsi_np->enabled = true when
iscsi_np->np_exports is non zero.

(Fix up context changes for v3.10.y - nab)

Cc: Sagi Grimberg <sagig@dev.mellanox.co.il>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/target/iscsi/iscsi_target.c

@@ -460,6 +460,7 @@ int iscsit_del_np(struct iscsi_np *np)
 	spin_lock_bh(&np->np_thread_lock);
 	np->np_exports--;
 	if (np->np_exports) {
+		np->enabled = true;
 		spin_unlock_bh(&np->np_thread_lock);
 		return 0;
 	}

drivers/target/iscsi/iscsi_target_tpg.c

@@ -175,14 +175,16 @@ void iscsit_put_tpg(struct iscsi_portal_group *tpg)
 
 static void iscsit_clear_tpg_np_login_thread(
 	struct iscsi_tpg_np *tpg_np,
-	struct iscsi_portal_group *tpg)
+	struct iscsi_portal_group *tpg,
+	bool shutdown)
 {
 	if (!tpg_np->tpg_np) {
 		pr_err("struct iscsi_tpg_np->tpg_np is NULL!\n");
 		return;
 	}
 
-	tpg_np->tpg_np->enabled = false;
+	if (shutdown)
+		tpg_np->tpg_np->enabled = false;
 	iscsit_reset_np_thread(tpg_np->tpg_np, tpg_np, tpg);
 }
 
@@ -198,7 +200,7 @@ void iscsit_clear_tpg_np_login_threads(
 			continue;
 		}
 		spin_unlock(&tpg->tpg_np_lock);
-		iscsit_clear_tpg_np_login_thread(tpg_np, tpg);
+		iscsit_clear_tpg_np_login_thread(tpg_np, tpg, false);
 		spin_lock(&tpg->tpg_np_lock);
 	}
 	spin_unlock(&tpg->tpg_np_lock);
@@ -521,7 +523,7 @@ static int iscsit_tpg_release_np(
 	struct iscsi_portal_group *tpg,
 	struct iscsi_np *np)
 {
-	iscsit_clear_tpg_np_login_thread(tpg_np, tpg);
+	iscsit_clear_tpg_np_login_thread(tpg_np, tpg, true);
 
 	pr_debug("CORE[%s] - Removed Network Portal: %s:%hu,%hu on %s\n",
 		tpg->tpg_tiqn->tiqn, np->np_ip, np->np_port, tpg->tpgt,