target: Add se_node_acl->acl_kref for ->acl_free_comp usage

This patch adds se_node_acl->acl_kref for use with ->acl_free_comp
during explict se_node_acl release.  It adds kref_init() during
se_node_acl setup, kref_get() during __transport_register_session()
-> target_put_nacl() with existing transport_deregister_session()
fabric callback usage.

It also moves transport_free_session() to release *se_sess memory
after target_put_nacl() execution in transport_deregister_session()

Cc: Roland Dreier <roland@purestorage.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Joern Engel <joern@logfs.org>
Cc: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_tpg.c

@@ -274,6 +274,7 @@ struct se_node_acl *core_tpg_check_initiator_node_acl(
 
 	INIT_LIST_HEAD(&acl->acl_list);
 	INIT_LIST_HEAD(&acl->acl_sess_list);
+	kref_init(&acl->acl_kref);
 	init_completion(&acl->acl_free_comp);
 	spin_lock_init(&acl->device_list_lock);
 	spin_lock_init(&acl->nacl_sess_lock);
@@ -403,6 +404,7 @@ struct se_node_acl *core_tpg_add_initiator_node_acl(
 
 	INIT_LIST_HEAD(&acl->acl_list);
 	INIT_LIST_HEAD(&acl->acl_sess_list);
+	kref_init(&acl->acl_kref);
 	init_completion(&acl->acl_free_comp);
 	spin_lock_init(&acl->device_list_lock);
 	spin_lock_init(&acl->nacl_sess_lock);

drivers/target/target_core_transport.c

@@ -282,6 +282,8 @@ void __transport_register_session(
 					&buf[0], PR_REG_ISID_LEN);
 			se_sess->sess_bin_isid = get_unaligned_be64(&buf[0]);
 		}
+		kref_get(&se_nacl->acl_kref);
+
 		spin_lock_irq(&se_nacl->nacl_sess_lock);
 		/*
 		 * The se_nacl->nacl_sess pointer will be set to the
@@ -335,6 +337,19 @@ int target_put_session(struct se_session *se_sess)
 }
 EXPORT_SYMBOL(target_put_session);
 
+static void target_complete_nacl(struct kref *kref)
+{
+	struct se_node_acl *nacl = container_of(kref,
+				struct se_node_acl, acl_kref);
+
+	complete(&nacl->acl_free_comp);
+}
+
+void target_put_nacl(struct se_node_acl *nacl)
+{
+	kref_put(&nacl->acl_kref, target_complete_nacl);
+}
+
 void transport_deregister_session_configfs(struct se_session *se_sess)
 {
 	struct se_node_acl *se_nacl;
@@ -411,17 +426,17 @@ void transport_deregister_session(struct se_session *se_sess)
 	}
 	spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);
 
-	transport_free_session(se_sess);
-
 	pr_debug("TARGET_CORE[%s]: Deregistered fabric_sess\n",
 		se_tpg->se_tpg_tfo->get_fabric_name());
 	/*
-	 * Awake sleeping ->acl_free_comp caller from configfs se_node_acl
-	 * removal context
+	 * If last kref is dropping now for an explict NodeACL, awake sleeping
+	 * ->acl_free_comp caller to wakeup configfs se_node_acl->acl_group
+	 * removal context.
 	 */
 	if (se_nacl && comp_nacl == true)
-		complete(&se_nacl->acl_free_comp);
+		target_put_nacl(se_nacl);
 
+	transport_free_session(se_sess);
 }
 EXPORT_SYMBOL(transport_deregister_session);
 

include/target/target_core_base.h

@@ -642,6 +642,7 @@ struct se_node_acl {
 	struct list_head	acl_list;
 	struct list_head	acl_sess_list;
 	struct completion	acl_free_comp;
+	struct kref		acl_kref;
 };
 
 struct se_session {

include/target/target_core_fabric.h

@@ -108,6 +108,7 @@ void	transport_register_session(struct se_portal_group *,
 void	target_get_session(struct se_session *);
 int	target_put_session(struct se_session *);
 void	transport_free_session(struct se_session *);
+void	target_put_nacl(struct se_node_acl *);
 void	transport_deregister_session_configfs(struct se_session *);
 void	transport_deregister_session(struct se_session *);