target: Fix se_tpg_tfo->tf_subsys regression + remove tf_subsystem

There is just one configfs subsystem in the target code, so we might as
well add two helpers to reference / unreference it from the core code
instead of passing pointers to it around.

This fixes a regression introduced for v4.1-rc1 with commit 9ac8928e6,
where configfs_depend_item() callers using se_tpg_tfo->tf_subsys would
fail, because the assignment from the original target_core_subsystem[]
is no longer happening at target_register_template() time.

(Fix target_core_exit_configfs pointer dereference - Sagi)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

4 files changed, 27 insertions, 53 deletions

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index ddaf76a4ac2a..1580077971f8 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -212,10 +212,6 @@ static struct config_group *target_core_register_fabric(
 
 	pr_debug("Target_Core_ConfigFS: REGISTER -> Allocated Fabric:"
 			" %s\n", tf->tf_group.cg_item.ci_name);
-	/*
-	 * Setup tf_ops.tf_subsys pointer for usage with configfs_depend_item()
-	 */
-	tf->tf_ops.tf_subsys = tf->tf_subsys;
 	tf->tf_fabric = &tf->tf_group.cg_item;
 	pr_debug("Target_Core_ConfigFS: REGISTER -> Set tf->tf_fabric"
 			" for %s\n", name);
@@ -291,10 +287,17 @@ static struct configfs_subsystem target_core_fabrics = {
 	},
 };
 
-struct configfs_subsystem *target_core_subsystem[] = {
-	&target_core_fabrics,
-	NULL,
-};
+int target_depend_item(struct config_item *item)
+{
+	return configfs_depend_item(&target_core_fabrics, item);
+}
+EXPORT_SYMBOL(target_depend_item);
+
+void target_undepend_item(struct config_item *item)
+{
+	return configfs_undepend_item(&target_core_fabrics, item);
+}
+EXPORT_SYMBOL(target_undepend_item);
 
 /*##############################################################################
 // Start functions called by external Target Fabrics Modules
@@ -467,7 +470,6 @@ int target_register_template(const struct target_core_fabric_ops *fo)
 	 * struct target_fabric_configfs->tf_cit_tmpl
 	 */
 	tf->tf_module = fo->module;
-	tf->tf_subsys = target_core_subsystem[0];
 	snprintf(tf->tf_name, TARGET_FABRIC_NAME_SIZE, "%s", fo->name);
 
 	tf->tf_ops = *fo;
@@ -2870,7 +2872,7 @@ static int __init target_core_init_configfs(void)
 {
 	struct config_group *target_cg, *hba_cg = NULL, *alua_cg = NULL;
 	struct config_group *lu_gp_cg = NULL;
-	struct configfs_subsystem *subsys;
+	struct configfs_subsystem *subsys = &target_core_fabrics;
 	struct t10_alua_lu_gp *lu_gp;
 	int ret;
 
@@ -2878,7 +2880,6 @@ static int __init target_core_init_configfs(void)
 		" Engine: %s on %s/%s on "UTS_RELEASE"\n",
 		TARGET_CORE_VERSION, utsname()->sysname, utsname()->machine);
 
-	subsys = target_core_subsystem[0];
 	config_group_init(&subsys->su_group);
 	mutex_init(&subsys->su_mutex);
 
@@ -3008,13 +3009,10 @@ out_global:
 
 static void __exit target_core_exit_configfs(void)
 {
-	struct configfs_subsystem *subsys;
 	struct config_group *hba_cg, *alua_cg, *lu_gp_cg;
 	struct config_item *item;
 	int i;
 
-	subsys = target_core_subsystem[0];
-
 	lu_gp_cg = &alua_lu_gps_group;
 	for (i = 0; lu_gp_cg->default_groups[i]; i++) {
 		item = &lu_gp_cg->default_groups[i]->cg_item;
@@ -3045,8 +3043,8 @@ static void __exit target_core_exit_configfs(void)
 	 * We expect subsys->su_group.default_groups to be released
 	 * by configfs subsystem provider logic..
 	 */
-	configfs_unregister_subsystem(subsys);
-	kfree(subsys->su_group.default_groups);
+	configfs_unregister_subsystem(&target_core_fabrics);
+	kfree(target_core_fabrics.su_group.default_groups);
 
 	core_alua_free_lu_gp(default_lu_gp);
 	default_lu_gp = NULL;
diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h
index 874a9bc988d8..68bd7f5d9f73 100644
--- a/drivers/target/target_core_internal.h
+++ b/drivers/target/target_core_internal.h
@@ -4,9 +4,6 @@
 /* target_core_alua.c */
 extern struct t10_alua_lu_gp *default_lu_gp;
 
-/* target_core_configfs.c */
-extern struct configfs_subsystem *target_core_subsystem[];
-
 /* target_core_device.c */
 extern struct mutex g_device_mutex;
 extern struct list_head g_device_list;
diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index c1aa9655e96e..b7c81acf08d0 100644
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -1367,41 +1367,26 @@ void core_scsi3_free_all_registrations(
 
 static int core_scsi3_tpg_depend_item(struct se_portal_group *tpg)
 {
-	return configfs_depend_item(tpg->se_tpg_tfo->tf_subsys,
-			&tpg->tpg_group.cg_item);
+	return target_depend_item(&tpg->tpg_group.cg_item);
 }
 
 static void core_scsi3_tpg_undepend_item(struct se_portal_group *tpg)
 {
-	configfs_undepend_item(tpg->se_tpg_tfo->tf_subsys,
-			&tpg->tpg_group.cg_item);
-
+	target_undepend_item(&tpg->tpg_group.cg_item);
 	atomic_dec_mb(&tpg->tpg_pr_ref_count);
 }
 
 static int core_scsi3_nodeacl_depend_item(struct se_node_acl *nacl)
 {
-	struct se_portal_group *tpg = nacl->se_tpg;
-
 	if (nacl->dynamic_node_acl)
 		return 0;
-
-	return configfs_depend_item(tpg->se_tpg_tfo->tf_subsys,
-			&nacl->acl_group.cg_item);
+	return target_depend_item(&nacl->acl_group.cg_item);
 }
 
 static void core_scsi3_nodeacl_undepend_item(struct se_node_acl *nacl)
 {
-	struct se_portal_group *tpg = nacl->se_tpg;
-
-	if (nacl->dynamic_node_acl) {
-		atomic_dec_mb(&nacl->acl_pr_ref_count);
-		return;
-	}
-
-	configfs_undepend_item(tpg->se_tpg_tfo->tf_subsys,
-			&nacl->acl_group.cg_item);
-
+	if (!nacl->dynamic_node_acl)
+		target_undepend_item(&nacl->acl_group.cg_item);
 	atomic_dec_mb(&nacl->acl_pr_ref_count);
 }
 
@@ -1419,8 +1404,7 @@ static int core_scsi3_lunacl_depend_item(struct se_dev_entry *se_deve)
 	nacl = lun_acl->se_lun_nacl;
 	tpg = nacl->se_tpg;
 
-	return configfs_depend_item(tpg->se_tpg_tfo->tf_subsys,
-			&lun_acl->se_lun_group.cg_item);
+	return target_depend_item(&lun_acl->se_lun_group.cg_item);
 }
 
 static void core_scsi3_lunacl_undepend_item(struct se_dev_entry *se_deve)
@@ -1438,9 +1422,7 @@ static void core_scsi3_lunacl_undepend_item(struct se_dev_entry *se_deve)
 	nacl = lun_acl->se_lun_nacl;
 	tpg = nacl->se_tpg;
 
-	configfs_undepend_item(tpg->se_tpg_tfo->tf_subsys,
-			&lun_acl->se_lun_group.cg_item);
-
+	target_undepend_item(&lun_acl->se_lun_group.cg_item);
 	atomic_dec_mb(&se_deve->pr_ref_count);
 }
 
diff --git a/drivers/target/target_core_xcopy.c b/drivers/target/target_core_xcopy.c
index a600ff15dcfd..8fd680ac941b 100644
--- a/drivers/target/target_core_xcopy.c
+++ b/drivers/target/target_core_xcopy.c
@@ -58,7 +58,6 @@ static int target_xcopy_locate_se_dev_e4(struct se_cmd *se_cmd, struct xcopy_op
 					bool src)
 {
 	struct se_device *se_dev;
-	struct configfs_subsystem *subsys = target_core_subsystem[0];
 	unsigned char tmp_dev_wwn[XCOPY_NAA_IEEE_REGEX_LEN], *dev_wwn;
 	int rc;
 
@@ -90,8 +89,7 @@ static int target_xcopy_locate_se_dev_e4(struct se_cmd *se_cmd, struct xcopy_op
 				" se_dev\n", xop->src_dev);
 		}
 
-		rc = configfs_depend_item(subsys,
-				&se_dev->dev_group.cg_item);
+		rc = target_depend_item(&se_dev->dev_group.cg_item);
 		if (rc != 0) {
 			pr_err("configfs_depend_item attempt failed:"
 				" %d for se_dev: %p\n", rc, se_dev);
@@ -99,8 +97,8 @@ static int target_xcopy_locate_se_dev_e4(struct se_cmd *se_cmd, struct xcopy_op
 			return rc;
 		}
 
-		pr_debug("Called configfs_depend_item for subsys: %p se_dev: %p"
-			" se_dev->se_dev_group: %p\n", subsys, se_dev,
+		pr_debug("Called configfs_depend_item for se_dev: %p"
+			" se_dev->se_dev_group: %p\n", se_dev,
 			&se_dev->dev_group);
 
 		mutex_unlock(&g_device_mutex);
@@ -373,7 +371,6 @@ static int xcopy_pt_get_cmd_state(struct se_cmd *se_cmd)
 
 static void xcopy_pt_undepend_remotedev(struct xcopy_op *xop)
 {
-	struct configfs_subsystem *subsys = target_core_subsystem[0];
 	struct se_device *remote_dev;
 
 	if (xop->op_origin == XCOL_SOURCE_RECV_OP)
@@ -381,11 +378,11 @@ static void xcopy_pt_undepend_remotedev(struct xcopy_op *xop)
 	else
 		remote_dev = xop->src_dev;
 
-	pr_debug("Calling configfs_undepend_item for subsys: %p"
+	pr_debug("Calling configfs_undepend_item for"
 		  " remote_dev: %p remote_dev->dev_group: %p\n",
-		  subsys, remote_dev, &remote_dev->dev_group.cg_item);
+		  remote_dev, &remote_dev->dev_group.cg_item);
 
-	configfs_undepend_item(subsys, &remote_dev->dev_group.cg_item);
+	target_undepend_item(&remote_dev->dev_group.cg_item);
 }
 
 static void xcopy_pt_release_cmd(struct se_cmd *se_cmd)