scsi: target: core: De-RCU of se_lun and se_lun acl

se_lun and se_lun_acl are immutable pointers of struct se_dev_entry.
Remove RCU usage for access to those pointers.

Link: https://lore.kernel.org/r/20220727214125.19647-3-d.bogdanov@yadro.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: logost

drivers/target/target_core_alua.c

@@ -934,8 +934,7 @@ static void core_alua_queue_state_change_ua(struct t10_alua_tg_pt_gp *tg_pt_gp)
 
 		spin_lock(&lun->lun_deve_lock);
 		list_for_each_entry(se_deve, &lun->lun_deve_list, lun_link) {
-			lacl = rcu_dereference_check(se_deve->se_lun_acl,
-					lockdep_is_held(&lun->lun_deve_lock));
+			lacl = se_deve->se_lun_acl;
 
 			/*
 			 * spc4r37 p.242:

drivers/target/target_core_device.c

@@ -75,7 +75,7 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd)
 			return TCM_WRITE_PROTECTED;
 		}
 
-		se_lun = rcu_dereference(deve->se_lun);
+		se_lun = deve->se_lun;
 
 		if (!percpu_ref_tryget_live(&se_lun->lun_ref)) {
 			se_lun = NULL;
@@ -152,7 +152,7 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd)
 	rcu_read_lock();
 	deve = target_nacl_find_deve(nacl, se_cmd->orig_fe_lun);
 	if (deve) {
-		se_lun = rcu_dereference(deve->se_lun);
+		se_lun = deve->se_lun;
 
 		if (!percpu_ref_tryget_live(&se_lun->lun_ref)) {
 			se_lun = NULL;
@@ -216,7 +216,7 @@ struct se_dev_entry *core_get_se_deve_from_rtpi(
 
 	rcu_read_lock();
 	hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link) {
-		lun = rcu_dereference(deve->se_lun);
+		lun = deve->se_lun;
 		if (!lun) {
 			pr_err("%s device entries device pointer is"
 				" NULL, but Initiator has access.\n",
@@ -243,11 +243,8 @@ void core_free_device_list_for_node(
 	struct se_dev_entry *deve;
 
 	mutex_lock(&nacl->lun_entry_mutex);
-	hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link) {
-		struct se_lun *lun = rcu_dereference_check(deve->se_lun,
-					lockdep_is_held(&nacl->lun_entry_mutex));
-		core_disable_device_list_for_node(lun, deve, nacl, tpg);
-	}
+	hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link)
+		core_disable_device_list_for_node(deve->se_lun, deve, nacl, tpg);
 	mutex_unlock(&nacl->lun_entry_mutex);
 }
 
@@ -334,8 +331,7 @@ int core_enable_device_list_for_node(
 	mutex_lock(&nacl->lun_entry_mutex);
 	orig = target_nacl_find_deve(nacl, mapped_lun);
 	if (orig && orig->se_lun) {
-		struct se_lun *orig_lun = rcu_dereference_check(orig->se_lun,
-					lockdep_is_held(&nacl->lun_entry_mutex));
+		struct se_lun *orig_lun = orig->se_lun;
 
 		if (orig_lun != lun) {
 			pr_err("Existing orig->se_lun doesn't match new lun"
@@ -355,8 +351,8 @@ int core_enable_device_list_for_node(
 			return -EINVAL;
 		}
 
-		rcu_assign_pointer(new->se_lun, lun);
-		rcu_assign_pointer(new->se_lun_acl, lun_acl);
+		new->se_lun = lun;
+		new->se_lun_acl = lun_acl;
 		hlist_del_rcu(&orig->link);
 		hlist_add_head_rcu(&new->link, &nacl->lun_entry_hlist);
 		mutex_unlock(&nacl->lun_entry_mutex);
@@ -374,8 +370,8 @@ int core_enable_device_list_for_node(
 		return 0;
 	}
 
-	rcu_assign_pointer(new->se_lun, lun);
-	rcu_assign_pointer(new->se_lun_acl, lun_acl);
+	new->se_lun = lun;
+	new->se_lun_acl = lun_acl;
 	hlist_add_head_rcu(&new->link, &nacl->lun_entry_hlist);
 	mutex_unlock(&nacl->lun_entry_mutex);
 
@@ -454,10 +450,7 @@ void core_clear_lun_from_tpg(struct se_lun *lun, struct se_portal_group *tpg)
 
 		mutex_lock(&nacl->lun_entry_mutex);
 		hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link) {
-			struct se_lun *tmp_lun = rcu_dereference_check(deve->se_lun,
-					lockdep_is_held(&nacl->lun_entry_mutex));
-
-			if (lun != tmp_lun)
+			if (lun != deve->se_lun)
 				continue;
 
 			core_disable_device_list_for_node(lun, deve, nacl, tpg);

drivers/target/target_core_pr.c

@@ -739,8 +739,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
 			if (!deve_tmp->se_lun_acl)
 				continue;
 
-			lacl_tmp = rcu_dereference_check(deve_tmp->se_lun_acl,
-						lockdep_is_held(&lun_tmp->lun_deve_lock));
+			lacl_tmp = deve_tmp->se_lun_acl;
 			nacl_tmp = lacl_tmp->se_lun_nacl;
 			/*
 			 * Skip the matching struct se_node_acl that is allocated
@@ -784,8 +783,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
 			 * the original *pr_reg is processed in
 			 * __core_scsi3_add_registration()
 			 */
-			dest_lun = rcu_dereference_check(deve_tmp->se_lun,
-				kref_read(&deve_tmp->pr_kref) != 0);
+			dest_lun = deve_tmp->se_lun;
 
 			pr_reg_atp = __core_scsi3_do_alloc_registration(dev,
 						nacl_tmp, dest_lun, deve_tmp,
@@ -1437,34 +1435,26 @@ static void core_scsi3_nodeacl_undepend_item(struct se_node_acl *nacl)
 
 static int core_scsi3_lunacl_depend_item(struct se_dev_entry *se_deve)
 {
-	struct se_lun_acl *lun_acl;
-
 	/*
 	 * For nacl->dynamic_node_acl=1
 	 */
-	lun_acl = rcu_dereference_check(se_deve->se_lun_acl,
-				kref_read(&se_deve->pr_kref) != 0);
-	if (!lun_acl)
+	if (!se_deve->se_lun_acl)
 		return 0;
 
-	return target_depend_item(&lun_acl->se_lun_group.cg_item);
+	return target_depend_item(&se_deve->se_lun_acl->se_lun_group.cg_item);
 }
 
 static void core_scsi3_lunacl_undepend_item(struct se_dev_entry *se_deve)
 {
-	struct se_lun_acl *lun_acl;
-
 	/*
 	 * For nacl->dynamic_node_acl=1
 	 */
-	lun_acl = rcu_dereference_check(se_deve->se_lun_acl,
-				kref_read(&se_deve->pr_kref) != 0);
-	if (!lun_acl) {
+	if (!se_deve->se_lun_acl) {
 		kref_put(&se_deve->pr_kref, target_pr_kref_release);
 		return;
 	}
 
-	target_undepend_item(&lun_acl->se_lun_group.cg_item);
+	target_undepend_item(&se_deve->se_lun_acl->se_lun_group.cg_item);
 	kref_put(&se_deve->pr_kref, target_pr_kref_release);
 }
 
@@ -1751,8 +1741,7 @@ core_scsi3_decode_spec_i_port(
 		 * and then call __core_scsi3_add_registration() in the
 		 * 2nd loop which will never fail.
 		 */
-		dest_lun = rcu_dereference_check(dest_se_deve->se_lun,
-				kref_read(&dest_se_deve->pr_kref) != 0);
+		dest_lun = dest_se_deve->se_lun;
 
 		dest_pr_reg = __core_scsi3_alloc_registration(cmd->se_dev,
 					dest_node_acl, dest_lun, dest_se_deve,
@@ -3446,8 +3435,7 @@ core_scsi3_emulate_pro_register_and_move(struct se_cmd *cmd, u64 res_key,
 	dest_pr_reg = __core_scsi3_locate_pr_reg(dev, dest_node_acl,
 					iport_ptr);
 	if (!dest_pr_reg) {
-		struct se_lun *dest_lun = rcu_dereference_check(dest_se_deve->se_lun,
-				kref_read(&dest_se_deve->pr_kref) != 0);
+		struct se_lun *dest_lun = dest_se_deve->se_lun;
 
 		spin_unlock(&dev->dev_reservation_lock);
 		if (core_scsi3_alloc_registration(cmd->se_dev, dest_node_acl,

drivers/target/target_core_stat.c

@@ -877,7 +877,6 @@ static ssize_t target_stat_auth_dev_show(struct config_item *item,
 	struct se_lun_acl *lacl = auth_to_lacl(item);
 	struct se_node_acl *nacl = lacl->se_lun_nacl;
 	struct se_dev_entry *deve;
-	struct se_lun *lun;
 	ssize_t ret;
 
 	rcu_read_lock();
@@ -886,9 +885,9 @@ static ssize_t target_stat_auth_dev_show(struct config_item *item,
 		rcu_read_unlock();
 		return -ENODEV;
 	}
-	lun = rcu_dereference(deve->se_lun);
+
 	/* scsiDeviceIndex */
-	ret = snprintf(page, PAGE_SIZE, "%u\n", lun->lun_index);
+	ret = snprintf(page, PAGE_SIZE, "%u\n", deve->se_lun->lun_index);
 	rcu_read_unlock();
 	return ret;
 }
@@ -1217,7 +1216,6 @@ static ssize_t target_stat_iport_dev_show(struct config_item *item,
 	struct se_lun_acl *lacl = iport_to_lacl(item);
 	struct se_node_acl *nacl = lacl->se_lun_nacl;
 	struct se_dev_entry *deve;
-	struct se_lun *lun;
 	ssize_t ret;
 
 	rcu_read_lock();
@@ -1226,9 +1224,9 @@ static ssize_t target_stat_iport_dev_show(struct config_item *item,
 		rcu_read_unlock();
 		return -ENODEV;
 	}
-	lun = rcu_dereference(deve->se_lun);
+
 	/* scsiDeviceIndex */
-	ret = snprintf(page, PAGE_SIZE, "%u\n", lun->lun_index);
+	ret = snprintf(page, PAGE_SIZE, "%u\n", deve->se_lun->lun_index);
 	rcu_read_unlock();
 	return ret;
 }

drivers/target/target_core_xcopy.c

@@ -88,7 +88,7 @@ static int target_xcopy_locate_se_dev_e4(struct se_session *sess,
 		struct se_device *this_dev;
 		int rc;
 
-		this_lun = rcu_dereference(deve->se_lun);
+		this_lun = deve->se_lun;
 		this_dev = rcu_dereference_raw(this_lun->lun_se_dev);
 
 		rc = target_xcopy_locate_se_dev_e4_iter(this_dev, dev_wwn);

include/target/target_core_base.h

@@ -665,9 +665,9 @@ struct se_dev_entry {
 	/* Used for PR SPEC_I_PT=1 and REGISTER_AND_MOVE */
 	struct kref		pr_kref;
 	struct completion	pr_comp;
-	struct se_lun_acl __rcu	*se_lun_acl;
+	struct se_lun_acl	*se_lun_acl;
 	spinlock_t		ua_lock;
-	struct se_lun __rcu	*se_lun;
+	struct se_lun		*se_lun;
 #define DEF_PR_REG_ACTIVE		1
 	unsigned long		deve_flags;
 	struct list_head	alua_port_list;