Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-androidlsk-v4.4-17.03-android

4 files changed, 136 insertions, 37 deletions

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index bd810c109277..6ed80b05d674 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -3436,7 +3436,7 @@ iscsit_build_sendtargets_response(struct iscsi_cmd *cmd,
 
 			if ((tpg->tpg_attrib.generate_node_acls == 0) &&
 			    (tpg->tpg_attrib.demo_mode_discovery == 0) &&
-			    (!core_tpg_get_initiator_node_acl(&tpg->tpg_se_tpg,
+			    (!target_tpg_has_node_acl(&tpg->tpg_se_tpg,
 				cmd->conn->sess->sess_ops->InitiatorName))) {
 				continue;
 			}
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 356c80fbb304..bb6a6c35324a 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -77,12 +77,16 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
 					&deve->read_bytes);
 
 		se_lun = rcu_dereference(deve->se_lun);
+
+		if (!percpu_ref_tryget_live(&se_lun->lun_ref)) {
+			se_lun = NULL;
+			goto out_unlock;
+		}
+
 		se_cmd->se_lun = rcu_dereference(deve->se_lun);
 		se_cmd->pr_res_key = deve->pr_res_key;
 		se_cmd->orig_fe_lun = unpacked_lun;
 		se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
-
-		percpu_ref_get(&se_lun->lun_ref);
 		se_cmd->lun_ref_active = true;
 
 		if ((se_cmd->data_direction == DMA_TO_DEVICE) &&
@@ -96,6 +100,7 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
 			goto ref_dev;
 		}
 	}
+out_unlock:
 	rcu_read_unlock();
 
 	if (!se_lun) {
@@ -826,6 +831,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
 	xcopy_lun = &dev->xcopy_lun;
 	rcu_assign_pointer(xcopy_lun->lun_se_dev, dev);
 	init_completion(&xcopy_lun->lun_ref_comp);
+	init_completion(&xcopy_lun->lun_shutdown_comp);
 	INIT_LIST_HEAD(&xcopy_lun->lun_deve_list);
 	INIT_LIST_HEAD(&xcopy_lun->lun_dev_link);
 	mutex_init(&xcopy_lun->lun_tg_pt_md_mutex);
diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index 5fb9dd7f08bb..2794c6ec5c3c 100644
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -75,9 +75,21 @@ struct se_node_acl *core_tpg_get_initiator_node_acl(
 	unsigned char *initiatorname)
 {
 	struct se_node_acl *acl;
-
+	/*
+	 * Obtain se_node_acl->acl_kref using fabric driver provided
+	 * initiatorname[] during node acl endpoint lookup driven by
+	 * new se_session login.
+	 *
+	 * The reference is held until se_session shutdown -> release
+	 * occurs via fabric driver invoked transport_deregister_session()
+	 * or transport_free_session() code.
+	 */
 	mutex_lock(&tpg->acl_node_mutex);
 	acl = __core_tpg_get_initiator_node_acl(tpg, initiatorname);
+	if (acl) {
+		if (!kref_get_unless_zero(&acl->acl_kref))
+			acl = NULL;
+	}
 	mutex_unlock(&tpg->acl_node_mutex);
 
 	return acl;
@@ -232,6 +244,25 @@ static void target_add_node_acl(struct se_node_acl *acl)
 		acl->initiatorname);
 }
 
+bool target_tpg_has_node_acl(struct se_portal_group *tpg,
+			     const char *initiatorname)
+{
+	struct se_node_acl *acl;
+	bool found = false;
+
+	mutex_lock(&tpg->acl_node_mutex);
+	list_for_each_entry(acl, &tpg->acl_node_list, acl_list) {
+		if (!strcmp(acl->initiatorname, initiatorname)) {
+			found = true;
+			break;
+		}
+	}
+	mutex_unlock(&tpg->acl_node_mutex);
+
+	return found;
+}
+EXPORT_SYMBOL(target_tpg_has_node_acl);
+
 struct se_node_acl *core_tpg_check_initiator_node_acl(
 	struct se_portal_group *tpg,
 	unsigned char *initiatorname)
@@ -248,6 +279,15 @@ struct se_node_acl *core_tpg_check_initiator_node_acl(
 	acl = target_alloc_node_acl(tpg, initiatorname);
 	if (!acl)
 		return NULL;
+	/*
+	 * When allocating a dynamically generated node_acl, go ahead
+	 * and take the extra kref now before returning to the fabric
+	 * driver caller.
+	 *
+	 * Note this reference will be released at session shutdown
+	 * time within transport_free_session() code.
+	 */
+	kref_get(&acl->acl_kref);
 	acl->dynamic_node_acl = 1;
 
 	/*
@@ -499,7 +539,7 @@ static void core_tpg_lun_ref_release(struct percpu_ref *ref)
 {
 	struct se_lun *lun = container_of(ref, struct se_lun, lun_ref);
 
-	complete(&lun->lun_ref_comp);
+	complete(&lun->lun_shutdown_comp);
 }
 
 int core_tpg_register(
@@ -626,6 +666,7 @@ struct se_lun *core_tpg_alloc_lun(
 	lun->lun_link_magic = SE_LUN_LINK_MAGIC;
 	atomic_set(&lun->lun_acl_count, 0);
 	init_completion(&lun->lun_ref_comp);
+	init_completion(&lun->lun_shutdown_comp);
 	INIT_LIST_HEAD(&lun->lun_deve_list);
 	INIT_LIST_HEAD(&lun->lun_dev_link);
 	atomic_set(&lun->lun_tg_pt_secondary_offline, 0);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index aa517c4fadb9..df2059984e14 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -341,7 +341,6 @@ 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);
 		/*
@@ -424,14 +423,27 @@ static void target_complete_nacl(struct kref *kref)
 {
 	struct se_node_acl *nacl = container_of(kref,
 				struct se_node_acl, acl_kref);
+	struct se_portal_group *se_tpg = nacl->se_tpg;
 
-	complete(&nacl->acl_free_comp);
+	if (!nacl->dynamic_stop) {
+		complete(&nacl->acl_free_comp);
+		return;
+	}
+
+	mutex_lock(&se_tpg->acl_node_mutex);
+	list_del(&nacl->acl_list);
+	mutex_unlock(&se_tpg->acl_node_mutex);
+
+	core_tpg_wait_for_nacl_pr_ref(nacl);
+	core_free_device_list_for_node(nacl, se_tpg);
+	kfree(nacl);
 }
 
 void target_put_nacl(struct se_node_acl *nacl)
 {
 	kref_put(&nacl->acl_kref, target_complete_nacl);
 }
+EXPORT_SYMBOL(target_put_nacl);
 
 void transport_deregister_session_configfs(struct se_session *se_sess)
 {
@@ -464,6 +476,42 @@ EXPORT_SYMBOL(transport_deregister_session_configfs);
 
 void transport_free_session(struct se_session *se_sess)
 {
+	struct se_node_acl *se_nacl = se_sess->se_node_acl;
+
+	/*
+	 * Drop the se_node_acl->nacl_kref obtained from within
+	 * core_tpg_get_initiator_node_acl().
+	 */
+	if (se_nacl) {
+		struct se_portal_group *se_tpg = se_nacl->se_tpg;
+		const struct target_core_fabric_ops *se_tfo = se_tpg->se_tpg_tfo;
+		unsigned long flags;
+
+		se_sess->se_node_acl = NULL;
+
+		/*
+		 * Also determine if we need to drop the extra ->cmd_kref if
+		 * it had been previously dynamically generated, and
+		 * the endpoint is not caching dynamic ACLs.
+		 */
+		mutex_lock(&se_tpg->acl_node_mutex);
+		if (se_nacl->dynamic_node_acl &&
+		    !se_tfo->tpg_check_demo_mode_cache(se_tpg)) {
+			spin_lock_irqsave(&se_nacl->nacl_sess_lock, flags);
+			if (list_empty(&se_nacl->acl_sess_list))
+				se_nacl->dynamic_stop = true;
+			spin_unlock_irqrestore(&se_nacl->nacl_sess_lock, flags);
+
+			if (se_nacl->dynamic_stop)
+				list_del(&se_nacl->acl_list);
+		}
+		mutex_unlock(&se_tpg->acl_node_mutex);
+
+		if (se_nacl->dynamic_stop)
+			target_put_nacl(se_nacl);
+
+		target_put_nacl(se_nacl);
+	}
 	if (se_sess->sess_cmd_map) {
 		percpu_ida_destroy(&se_sess->sess_tag_pool);
 		kvfree(se_sess->sess_cmd_map);
@@ -475,16 +523,12 @@ EXPORT_SYMBOL(transport_free_session);
 void transport_deregister_session(struct se_session *se_sess)
 {
 	struct se_portal_group *se_tpg = se_sess->se_tpg;
-	const struct target_core_fabric_ops *se_tfo;
-	struct se_node_acl *se_nacl;
 	unsigned long flags;
-	bool comp_nacl = true, drop_nacl = false;
 
 	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);
@@ -492,37 +536,16 @@ void transport_deregister_session(struct se_session *se_sess)
 	se_sess->fabric_sess_ptr = NULL;
 	spin_unlock_irqrestore(&se_tpg->session_lock, flags);
 
-	/*
-	 * Determine if we need to do extra work for this initiator node's
-	 * struct se_node_acl if it had been previously dynamically generated.
-	 */
-	se_nacl = se_sess->se_node_acl;
-
-	mutex_lock(&se_tpg->acl_node_mutex);
-	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--;
-			drop_nacl = true;
-		}
-	}
-	mutex_unlock(&se_tpg->acl_node_mutex);
-
-	if (drop_nacl) {
-		core_tpg_wait_for_nacl_pr_ref(se_nacl);
-		core_free_device_list_for_node(se_nacl, se_tpg);
-		kfree(se_nacl);
-		comp_nacl = false;
-	}
 	pr_debug("TARGET_CORE[%s]: Deregistered fabric_sess\n",
 		se_tpg->se_tpg_tfo->get_fabric_name());
 	/*
 	 * If last kref is dropping now for an explicit NodeACL, awake sleeping
 	 * ->acl_free_comp caller to wakeup configfs se_node_acl->acl_group
-	 * removal context.
+	 * removal context from within transport_free_session() code.
+	 *
+	 * For dynamic ACL, target_put_nacl() uses target_complete_nacl()
+	 * to release all remaining generate_node_acl=1 created ACL resources.
 	 */
-	if (se_nacl && comp_nacl)
-		target_put_nacl(se_nacl);
 
 	transport_free_session(se_sess);
 }
@@ -2657,10 +2680,39 @@ void target_wait_for_sess_cmds(struct se_session *se_sess)
 }
 EXPORT_SYMBOL(target_wait_for_sess_cmds);
 
+static void target_lun_confirm(struct percpu_ref *ref)
+{
+	struct se_lun *lun = container_of(ref, struct se_lun, lun_ref);
+
+	complete(&lun->lun_ref_comp);
+}
+
 void transport_clear_lun_ref(struct se_lun *lun)
 {
-	percpu_ref_kill(&lun->lun_ref);
+	/*
+	 * Mark the percpu-ref as DEAD, switch to atomic_t mode, drop
+	 * the initial reference and schedule confirm kill to be
+	 * executed after one full RCU grace period has completed.
+	 */
+	percpu_ref_kill_and_confirm(&lun->lun_ref, target_lun_confirm);
+	/*
+	 * The first completion waits for percpu_ref_switch_to_atomic_rcu()
+	 * to call target_lun_confirm after lun->lun_ref has been marked
+	 * as __PERCPU_REF_DEAD on all CPUs, and switches to atomic_t
+	 * mode so that percpu_ref_tryget_live() lookup of lun->lun_ref
+	 * fails for all new incoming I/O.
+	 */
 	wait_for_completion(&lun->lun_ref_comp);
+	/*
+	 * The second completion waits for percpu_ref_put_many() to
+	 * invoke ->release() after lun->lun_ref has switched to
+	 * atomic_t mode, and lun->lun_ref.count has reached zero.
+	 *
+	 * At this point all target-core lun->lun_ref references have
+	 * been dropped via transport_lun_remove_cmd(), and it's safe
+	 * to proceed with the remaining LUN shutdown.
+	 */
+	wait_for_completion(&lun->lun_shutdown_comp);
 }
 
 static bool