--- a/arch/mips/kernel/gdb-stub.c
+++ b/arch/mips/kernel/gdb-stub.c
@@ -656,6 +656,7 @@ void set_async_breakpoint(unsigned long 
 	*epc = (unsigned long)async_breakpoint;
 }
 
+#ifdef CONFIG_SMP
 static void kgdb_wait(void *arg)
 {
 	unsigned flags;
@@ -668,6 +669,7 @@ static void kgdb_wait(void *arg)
 
 	local_irq_restore(flags);
 }
+#endif
 
 /*
  * GDB stub needs to call kgdb_wait on all processor with interrupts
