target: Add se_node_acl->acl_free_comp for NodeACL release path

Add se_node_acl->acl_free_comp for NodeACL release path to wait for outstanding
fabric session shutdown to complete in transport_deregister_session() before
finishing NodeACL release from configfs process context.

Also make transport_deregister_session() clear the comp_nacl bit
to skip se_node_acl->acl_free_comp completion for dynamically generated
NodeACL during fabric session shutdown.

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>

2 files changed, 26 insertions, 16 deletions

diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index 32153404da1..9cdfd061eac 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);
+        init_completion(&acl->acl_free_comp);
         spin_lock_init(&acl->device_list_lock);
         spin_lock_init(&acl->nacl_sess_lock);
         atomic_set(&acl->acl_pr_ref_count, 0);
@@ -402,6 +403,7 @@ struct se_node_acl *core_tpg_add_initiator_node_acl(
 
         INIT_LIST_HEAD(&acl->acl_list);
         INIT_LIST_HEAD(&acl->acl_sess_list);
+        init_completion(&acl->acl_free_comp);
         spin_lock_init(&acl->device_list_lock);
         spin_lock_init(&acl->nacl_sess_lock);
         atomic_set(&acl->acl_pr_ref_count, 0);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 7badc87e4bb..9e61abc5d9d 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -372,13 +372,16 @@ EXPORT_SYMBOL(transport_free_session);
 void transport_deregister_session(struct se_session *se_sess)
 {
         struct se_portal_group *se_tpg = se_sess->se_tpg;
+        struct target_core_fabric_ops *se_tfo;
         struct se_node_acl *se_nacl;
         unsigned long flags;
+        bool comp_nacl = true;
 
         if (!se_tpg) {
                 transport_free_session(se_sess);
                 return;
         }
+        se_tfo = se_tpg->se_tpg_tfo;
 
         spin_lock_irqsave(&se_tpg->session_lock, flags);
         list_del(&se_sess->sess_list);
@@ -391,29 +394,34 @@ void transport_deregister_session(struct se_session *se_sess)
          * struct se_node_acl if it had been previously dynamically generated.
          */
         se_nacl = se_sess->se_node_acl;
-        if (se_nacl) {
-                spin_lock_irqsave(&se_tpg->acl_node_lock, flags);
-                if (se_nacl->dynamic_node_acl) {
-                        if (!se_tpg->se_tpg_tfo->tpg_check_demo_mode_cache(
-                                        se_tpg)) {
-                                list_del(&se_nacl->acl_list);
-                                se_tpg->num_node_acls--;
-                                spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);
-
-                                core_tpg_wait_for_nacl_pr_ref(se_nacl);
-                                core_free_device_list_for_node(se_nacl, se_tpg);
-                                se_tpg->se_tpg_tfo->tpg_release_fabric_acl(se_tpg,
-                                                se_nacl);
-                                spin_lock_irqsave(&se_tpg->acl_node_lock, flags);
-                        }
+
+        spin_lock_irqsave(&se_tpg->acl_node_lock, flags);
+        if (se_nacl && se_nacl->dynamic_node_acl) {
+                if (!se_tfo->tpg_check_demo_mode_cache(se_tpg)) {
+                        list_del(&se_nacl->acl_list);
+                        se_tpg->num_node_acls--;
+                        spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);
+                        core_tpg_wait_for_nacl_pr_ref(se_nacl);
+                        core_free_device_list_for_node(se_nacl, se_tpg);
+                        se_tfo->tpg_release_fabric_acl(se_tpg, se_nacl);
+
+                        comp_nacl = false;
+                        spin_lock_irqsave(&se_tpg->acl_node_lock, flags);
                 }
-                spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);
         }
+        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 (se_nacl && comp_nacl == true)
+                complete(&se_nacl->acl_free_comp);
+
 }
 EXPORT_SYMBOL(transport_deregister_session);