diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index a232bb5..1f5e55d 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -180,7 +180,8 @@
 		return has_ns_capability(current, ns, CAP_SYS_PTRACE);
 }
 
-int __ptrace_may_access(struct task_struct *task, unsigned int mode)
+/* Returns 0 on success, -errno on denial. */
+static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
 	const struct cred *cred = current_cred(), *tcred;