tomoyo: Suppress RCU warning at list_for_each_entry_rcu().

John Garry has reported that allmodconfig kernel on arm64 causes flood of
"RCU-list traversed in non-reader section!!" warning. I don't know what
change caused this warning, but this warning is safe because TOMOYO uses
SRCU lock instead. Let's suppress this warning by explicitly telling that
the caller is holding SRCU lock.

Reported-and-tested-by: John Garry <john.garry@huawei.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 8526a0a..7869d6a 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -41,7 +41,8 @@ int tomoyo_update_policy(struct tomoyo_acl_head *new_entry, const int size,
 
 	if (mutex_lock_interruptible(&tomoyo_policy_lock))
 		return -ENOMEM;
-	list_for_each_entry_rcu(entry, list, list) {
+	list_for_each_entry_rcu(entry, list, list,
+				srcu_read_lock_held(&tomoyo_ss)) {
 		if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)
 			continue;
 		if (!check_duplicate(entry, new_entry))
@@ -119,7 +120,8 @@ int tomoyo_update_domain(struct tomoyo_acl_info *new_entry, const int size,
 	}
 	if (mutex_lock_interruptible(&tomoyo_policy_lock))
 		goto out;
-	list_for_each_entry_rcu(entry, list, list) {
+	list_for_each_entry_rcu(entry, list, list,
+				srcu_read_lock_held(&tomoyo_ss)) {
 		if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)
 			continue;
 		if (!tomoyo_same_acl_head(entry, new_entry) ||
@@ -166,7 +168,8 @@ void tomoyo_check_acl(struct tomoyo_request_info *r,
 	u16 i = 0;
 
 retry:
-	list_for_each_entry_rcu(ptr, list, list) {
+	list_for_each_entry_rcu(ptr, list, list,
+				srcu_read_lock_held(&tomoyo_ss)) {
 		if (ptr->is_deleted || ptr->type != r->param_type)
 			continue;
 		if (!check_entry(r, ptr))
@@ -298,7 +301,8 @@ static inline bool tomoyo_scan_transition
 {
 	const struct tomoyo_transition_control *ptr;
 
-	list_for_each_entry_rcu(ptr, list, head.list) {
+	list_for_each_entry_rcu(ptr, list, head.list,
+				srcu_read_lock_held(&tomoyo_ss)) {
 		if (ptr->head.is_deleted || ptr->type != type)
 			continue;
 		if (ptr->domainname) {
@@ -735,7 +739,8 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
 
 		/* Check 'aggregator' directive. */
 		candidate = &exename;
-		list_for_each_entry_rcu(ptr, list, head.list) {
+		list_for_each_entry_rcu(ptr, list, head.list,
+					srcu_read_lock_held(&tomoyo_ss)) {
 			if (ptr->head.is_deleted ||
 			    !tomoyo_path_matches_pattern(&exename,
 							 ptr->original_name))