target: Convert se_node_acl->acl_group removal to use ->acl_kref

This patch converts core_tpg_del_initiator_node_acl() shutdown from configfs
context to use se_node_acl->acl_kref and ->acl_free_comp in order to wait for
outstanding fabric callbacks to complete via transport_deregister_session()
callbacks before waking ->acl_free_comp from the last ->acl_kref put.

It also changes core_tpg_del_initiator_node_acl() to setup a local sess_list
with target_get_session() + acl->acl_stop = 1 for active sessions that will
be shutdown, and changes transport_deregister_session_configfs() to check
for ->acl_stop usage.

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, 28 insertions, 19 deletions

diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index bbed260ec71f..f3ea385737d5 100644
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -452,9 +452,10 @@ int core_tpg_del_initiator_node_acl(
         struct se_node_acl *acl,
         int force)
 {
+        LIST_HEAD(sess_list);
         struct se_session *sess, *sess_tmp;
         unsigned long flags;
-        int dynamic_acl = 0;
+        int dynamic_acl = 0, rc;
 
         spin_lock_irq(&tpg->acl_node_lock);
         if (acl->dynamic_node_acl) {
@@ -465,27 +466,34 @@ int core_tpg_del_initiator_node_acl(
         tpg->num_node_acls--;
         spin_unlock_irq(&tpg->acl_node_lock);
 
-        spin_lock_irqsave(&tpg->session_lock, flags);
-        list_for_each_entry_safe(sess, sess_tmp,
-                                &tpg->tpg_sess_list, sess_list) {
-                if (sess->se_node_acl != acl)
-                        continue;
-                /*
-                 * Determine if the session needs to be closed by our context.
-                 */
-                if (!tpg->se_tpg_tfo->shutdown_session(sess))
+        spin_lock_irqsave(&acl->nacl_sess_lock, flags);
+        acl->acl_stop = 1;
+
+        list_for_each_entry_safe(sess, sess_tmp, &acl->acl_sess_list,
+                                sess_acl_list) {
+                if (sess->sess_tearing_down != 0)
                         continue;
 
-                spin_unlock_irqrestore(&tpg->session_lock, flags);
-                /*
-                 * If the $FABRIC_MOD session for the Initiator Node ACL exists,
-                 * forcefully shutdown the $FABRIC_MOD session/nexus.
-                 */
-                tpg->se_tpg_tfo->close_session(sess);
+                target_get_session(sess);
+                list_move(&sess->sess_acl_list, &sess_list);
+        }
+        spin_unlock_irqrestore(&acl->nacl_sess_lock, flags);
+
+        list_for_each_entry_safe(sess, sess_tmp, &sess_list, sess_acl_list) {
+                list_del(&sess->sess_acl_list);
 
-                spin_lock_irqsave(&tpg->session_lock, flags);
+                rc = tpg->se_tpg_tfo->shutdown_session(sess);
+                target_put_session(sess);
+                if (!rc)
+                        continue;
+                target_put_session(sess);
         }
-        spin_unlock_irqrestore(&tpg->session_lock, flags);
+        target_put_nacl(acl);
+        /*
+         * Wait for last target_put_nacl() to complete in target_complete_nacl()
+         * for active fabric session transport_deregister_session() callbacks.
+         */
+        wait_for_completion(&acl->acl_free_comp);
 
         core_tpg_wait_for_nacl_pr_ref(acl);
         core_clear_initiator_node_from_tpg(acl, tpg);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index efefbec286fc..ba8eb8373032 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -360,7 +360,8 @@ void transport_deregister_session_configfs(struct se_session *se_sess)
         se_nacl = se_sess->se_node_acl;
         if (se_nacl) {
                 spin_lock_irqsave(&se_nacl->nacl_sess_lock, flags);
-                list_del(&se_sess->sess_acl_list);
+                if (se_nacl->acl_stop == 0)
+                        list_del(&se_sess->sess_acl_list);
                 /*
                  * If the session list is empty, then clear the pointer.
                  * Otherwise, set the struct se_session pointer from the tail