TOMOYO: Use RCU primitives for list operation

Replace list operation with RCU primitives and replace
down_read()/up_read() with srcu_read_lock()/srcu_read_unlock().

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c
index e3c7aa0..62363b3 100644
--- a/security/tomoyo/realpath.c
+++ b/security/tomoyo/realpath.c
@@ -402,11 +402,13 @@
 		INIT_LIST_HEAD(&tomoyo_name_list[i]);
 	INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
 	tomoyo_kernel_domain.domainname = tomoyo_save_name(TOMOYO_ROOT_NAME);
-	list_add_tail(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
-	down_read(&tomoyo_domain_list_lock);
+	/*
+	 * tomoyo_read_lock() is not needed because this function is
+	 * called before the first "delete" request.
+	 */
+	list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
 	if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
 		panic("Can't register tomoyo_kernel_domain");
-	up_read(&tomoyo_domain_list_lock);
 }
 
 /* Memory allocated for temporary purpose. */