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>

4 files changed, 24 insertions, 5 deletions

diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index 9cdfd061eacf..bbed260ec71f 100644
--- a/drivers/target/target_core_tpg.c
+++ b/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);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 9e61abc5d9d3..efefbec286fc 100644
--- a/drivers/target/target_core_transport.c
+++ b/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);
 
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index f8aa300b0d25..2cda5638a4cc 100644
--- a/include/target/target_core_base.h
+++ b/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 {
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index 7e76aa167009..032c48753cfa 100644
--- a/include/target/target_core_fabric.h
+++ b/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 *);