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>

1 files changed, 14 insertions, 16 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;